Microglia and multiple sclerosis

  1. Aarli JA (2003) Role of cytokines in neurological disorders. Curr.Med.Chem. 10:1931-1937
    Abstract: The balance between cytokines with pro- and anti-inflammatory effects contributes to the course of the Guillain-Barre syndrome and chronic inflammatory demyelinating polyneuropathy. TNFalpha seems to be an important factor in the cascade of events leading to demyelination and even axonal damage. During the acute phase, the serum concentrations of TNFalpha and IL-6 are elevated while anti-inflammatory cytokines are up-regulated in the recovery phase. Cytokines also have a key role in the pathogenesis of multiple sclerosis and most data suggest that this effect is mediated by myelin-specific CD4 T lymphocytes secreting Th type 1 cytokines. However, several different immune cells including B lymphocytes, CD8 T lymphocytes and NK T lymphocytes are also involved in the pathogenesis. Both Th1 and Th2 lymphocytes and cytokines probably participate in the development of myasthenia gravis (MG). The IFNalpha production is probably related to the severity of the disease, with clinical improvement associated with decreased production. The serum levels of IL-18 are significantly elevated in MG, with highest concentrations in patients with generalized disease. The immune system may be involved in the pathogenesis of AD by the effect of Microglia, which can induce Microglial activation with subsequent release of pro-inflammatory cytokines. In parkinsonism, there is evidence of chronic inflammation in the substantia nigra and striatum. Activated Microglia, producing proinflammatory cytokines, surround the degenerating dopaminergic neurons and may contribute to the dopaminergic neuron loss. Studies of patients with epilepsy and animals with experimentally induced seizures indicate that cytokines may also influence the electrophysiological properties of neurons

  2. Arevalo-Martin A, Vela JM, Molina-Holgado E, Borrell J, Guaza C (2003) Therapeutic action of cannabinoids in a murine model of multiple sclerosis. J.Neurosci. 23:2511-2516
    Abstract: Theiler's virus infection of the CNS induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). Cannabinoids may act as immunosuppressive compounds that have shown therapeutic potential in chronic inflammatory disorders. Using the Theiler's murine encephalomyelitis virus model, we report here that treatment with the synthetic cannabinoids WIN 55,212-2, ACEA, and JWH-015 during established disease significantly improved the neurological deficits in a long-lasting way. At a histological level, cannabinoids reduced Microglial activation, abrogated major histocompatibility complex class II antigen expression, and decreased the number of CD4+ infiltrating T cells in the spinal cord. Both recovery of motor function and diminution of inflammation paralleled extensive remyelination. Overall, the data presented may have potential therapeutic implications in demyelinating pathologies such as MS; in particular, the possible involvement of cannabinoid receptor CB2 would enable nonpsychoactive therapy suitable for long-term use

  3. Chan A, Papadimitriou C, Graf W, Toyka KV, Gold R (2003) Effects of polyclonal immunoglobulins and other immunomodulatory agents on Microglial phagocytosis of apoptotic inflammatory T-cells. J.Neuroimmunol. 135:161-165
    Abstract: T-cell apoptosis in the CNS is an effective mechanism for the noninflammatory resolution of autoimmune T-cell infiltrates. Ingestion of apoptotic leukocytes by Microglia results in an efficient clearance of the inflammatory infiltrate, followed by a profound downregulation of proinflammatory phagocyte immune functions. The effects of different immunomodulatory agents on Lewis rat Microglial phagocytosis of apoptotic autologous thymocytes or myelin-basic protein (MBP)-specific, encephalitogenic T-cells were investigated using a standardized, light microscopical in vitro phagocytosis assay. Pretreatment of Microglia with polyclonal 7S immunoglobulins (IVIg) decreased the phagocytosis of apoptotic thymocytes by 38.2% (p<0.0001). Also, immunoglobulin F(ab')(2) fragments decreased Microglial phagocytosis, suggesting an Fc receptor-independent mechanism. Similar results were obtained using MBP-specific T-cells. Pretreatment of Microglia with IFN-gamma increased the phagocytosis of apoptotic cells by 65.4%, which was to a large extent counteracted by IVIg. Glatiramer acetate (GLAT) did not exert an effect on Microglial phagocytosis, while methylprednisolone (MP) induced Microglial apoptosis in vitro. These results indicate that IVIg has a high potential to inhibit Microglial phagocytosis of apoptotic inflammatory T-cells even under proinflammatory conditions and extend our view of the complex immunomodulatory effects of IVIg

  4. Cipriani B, Chen L, Hiromatsu K, Knowles H, Raine CS, Battistini L, Porcelli SA, Brosnan CF (2003) Upregulation of group 1 CD1 antigen presenting molecules in guinea pigs with experimental autoimmune encephalomyelitis: an immunohistochemical study. Brain Pathol. 13:1-9
    Abstract: In humans, group 1 CD1 glycoproteins present foreign and self lipid and glycolipid antigens to T-cells. Homologues of these molecules are not found in mice or rats but are present in guinea pigs (GPs). We examined CD1 and MHC class II expression in the central nervous system (CNS) of GPs sensitized for experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. In normal GPs and the uninflamed CNS, low-level MHC class II (MHC II) immunoreactivity occurred on vascular elements, meningeal macrophages and parenchymal Microglial cells, whereas immunoreactivity for CD1 was absent. In the inflamed CNS, the majority of infiltrating cells were MHC II+ and Microglia showed increased expression. CD1 immunoreactivity was detected on astrocytes and subsets of inflammatory cells Including B cells and macrophages. Minimal CD1 and MHC II co-expression was noted on inflammatory cells or glia. We conclude that group 1 CD1 molecules are strongly upregulated in the inflamed CNS on subsets of cells distinct from the majority of MHC II bearing cells. The expression of CD1 proteins in such lesions broadens the potential repertoire of antigens recognized at these sites and highlights the value of the GP as a model for studies of the relevance of CD1 molecules in host defense and autoimmune diseases

  5. Columba-Cabezas S, Serafini B, Ambrosini E, Aloisi F (2003) Lymphoid chemokines CCL19 and CCL21 are expressed in the central nervous system during experimental autoimmune encephalomyelitis: implications for the maintenance of chronic neuroinflammation. Brain Pathol. 13:38-51
    Abstract: The simultaneous presence of dendritic, T- and B-cells in the central nervous system (CNS) of mice with experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, suggests that interactions among these cell types might be instrumental in the local induction and maintenance of autoimmune reactions. In this study, we explored the possibility that such aberrant leukocyte recruitment in the CNS could be sustained by "lymphoid" chemokines which orchestrate dendritic cell and lymphocyte homing to lymphoid organs. Transcripts for CCL19 and CCL21 and their common receptor CCR7 were induced in the CNS of mice undergoing relapsing-remitting and chronic-relapsing EAE. While CCL21 immunoreactivity was confined to the endothelium of some inflamed blood vessels, CCL19 was expressed by many infiltrating leukocytes and some astrocytes and Microglia in the CNS parenchyma. CCR7+ cells accumulated in inflammatory lesions during EAE progression, when abundant infiltration of the CNS by mature dendritic cells, B-cells and cells expressing naive T-cell markers also occurred. These findings suggest that CCL19 and CCL21 produced in the EAE-affected CNS may be critical for the homing of antigen presenting cells and lymphocytes, resulting in continuous local antigenic stimulation and maintenance of chronic neuroinflammation

  6. Dasgupta S, Jana M, Liu X, Pahan K (2003) Role of very-late antigen-4 (VLA-4) in myelin basic protein-primed T cell contact-induced expression of proinflammatory cytokines in Microglial cells. J.Biol.Chem. 278:22424-22431
    Abstract: The presence of neuroantigen-primed T cells recognizing self-myelin antigens within the CNS is necessary for the development of demyelinating autoimmune disease like multiple sclerosis. This study was undertaken to investigate the role of myelin basic protein (MBP)-primed T cells in the expression of proinflammatory cytokines in Microglial cells. MBP-primed T cells alone induced specifically the Microglial expression of interleukin (IL)-1beta, IL-1alpha tumor necrosis factor alpha, and IL-6, proinflammatory cytokines that are primarily involved in the pathogenesis of MS. This induction was primarily dependent on the contact between MBP-primed T cells and Microglia. The activation of Microglial NF-kappaB and CCAAT/enhancer-binding protein beta (C/EBPbeta) by MBP-primed T cell contact and inhibition of contact-mediated Microglial expression of proinflammatory cytokines by dominant-negative mutants of p65 and C/EBPbeta suggest that MBP-primed T cells induce Microglial expression of cytokines through the activation of NF-kappaB and C/EBPbeta. In addition, we show that MBP-primed T cells express very late antigen-4 (VLA-4), and functional blocking antibodies to alpha4 chain of VLA-4 (CD49d) inhibited the ability of MBP-primed T cells to induce Microglial proinflammatory cytokines. Interestingly, the blocking of VLA-4 impaired the ability of MBP-primed T cells to induce Microglial activation of only C/EBPbeta but not that of NF-kappaB. This study illustrates a novel role of VLA-4 in regulating neuroantigen-primed T cell-induced activation of Microglia through C/EBPbeta

  7. Dasgupta S, Zhou Y, Jana M, Banik NL, Pahan K (2003) Sodium phenylacetate inhibits adoptive transfer of experimental allergic encephalomyelitis in SJL/J mice at multiple steps. J.Immunol. 170:3874-3882
    Abstract: Experimental allergic encephalomyelitis (EAE) is the animal model for multiple sclerosis. The present study underlines the importance of sodium phenylacetate (NaPA), a drug approved for urea cycle disorders, in inhibiting the disease process of adoptively transferred EAE in female SJL/J mice at multiple steps. Myelin basic protein (MBP)-primed T cells alone induced the expression of NO synthase (iNOS) and the activation of NF-kappaB in mouse Microglial cells through cell-cell contact. However, pretreatment of MBP-primed T cells with NaPA markedly inhibited its ability to induce Microglial expression of iNOS and activation of NF-kappaB. Consistently, adoptive transfer of MBP-primed T cells, but not that of NaPA-pretreated MBP-primed T cells, induced the clinical symptoms of EAE in female SJL/J mice. Furthermore, MBP-primed T cells isolated from NaPA-treated donor mice were also less efficient than MBP-primed T cells isolated from normal donor mice in inducing iNOS in Microglial cells and transferring EAE to recipient mice. Interestingly, clinical symptoms of EAE were much less in mice receiving NaPA through drinking water than those without NaPA. Similar to NaPA, sodium phenylbutyrate, a chemically synthesized precursor of NaPA, also inhibited the disease process of EAE. Histological and immunocytochemical analysis showed that NaPA inhibited EAE-induced spinal cord mononuclear cell invasion and normalized iNOS, nitrotyrosine, and p65 (the RelA subunit of NF-kappaB) expression within the spinal cord. Taken together, our results raise the possibility that NaPA or sodium phenylbutyrate taken through drinking water or milk may reduce the observed neuroinflammation and disease process in multiple sclerosis patients

  8. De Keyser J, Zeinstra E, Frohman E (2003) Are astrocytes central players in the pathophysiology of multiple sclerosis? Arch.Neurol. 60:132-136
    Abstract: An interaction between antimyelin T cells and antigen-presenting glial cells is a crucial step in the cascade of immune events that lead to the inflammatory lesions in multiple sclerosis (MS). One of the most debated and controversial issues is whether Microglial cells or astrocytes are the key players in initiating the (auto)immune reactions in the central nervous system in MS. Many investigators consider Microglia to be the responsible intrinsic immunoeffector cells. In this review, we speculate that in MS astrocytes may serve as primary (facultative) antigen-presenting cells due to a failure of noradrenergic suppression of class II major histocompatibility complex molecules, which is caused by a loss of beta(2)-adrenergic receptors. If this hypothesis is correct, pharmacologic suppression of the antigen-presenting capacities of astrocytes may be a potential therapy for MS

  9. Debruyne JC, Versijpt J, Van Laere KJ, De Vos F, Keppens J, Strijckmans K, Achten E, Slegers G, Dierckx RA, Korf J, De Reuck JL (2003) PET visualization of Microglia in multiple sclerosis patients using [11C]PK11195. Eur.J.Neurol. 10:257-264
    Abstract: Activated Microglia are involved in the immune response of multiple sclerosis (MS). The peripheral benzodiazepine receptor (PBR) is expressed on Microglia and up-regulated after neuronal injury. [11C]PK11195 is a positron emission tomography (PET) radioligand for the PBR. The objective of the present study was to investigate [11C]PK11195 imaging in MS patients and its additional value over magnetic resonance imaging (MRI) concerning the immuno-pathophysiological process. Seven healthy and 22 MS subjects were included. Semiquantitative [11C]PK11195 uptake values were assessed with normalization on cortical grey matter. Uptake in Gadolinium-lesions was significantly increased compared with normal white matter. Uptake in T2-lesions was generally decreased, suggesting a PBR down-regulation. However, uptake values increased whenever a clinical or MR-relapse was present, suggestive for a dynamic process with a transient PBR up-regulation. During disease progression, an increase of normal-appearing white matter (NAWM) uptake was found, propagating NAWM as the possible real burden of disease. In conclusion, [11C]PK11195 and PET are able to demonstrate inflammatory processes with Microglial involvement in MS

  10. Delgado M, Ganea D (2003) Vasoactive intestinal peptide prevents activated Microglia-induced neurodegeneration under inflammatory conditions: potential therapeutic role in brain trauma. FASEB J. 17:1922-1924
    Abstract: In most neurodegenerative disorders, including multiple sclerosis, Parkinson's disease, and Alzheimer's disease, a massive neuronal cell death occurs as a consequence of an uncontrolled inflammatory response, where activated Microglia and its cytotoxic agents play a crucial pathologic role. Because current treatments for these diseases are not effective, several regulatory molecules termed "Microglia-deactivating factors" recently have been the focus of considerable research. Vasoactive intestinal peptide (VIP) is a neuropeptide with a potent anti-inflammatory effect, which has been found to protect from other inflammatory disorders, such as endotoxic shock and rheumatoid arthritis. In the present study, we investigate the effect of VIP on inflammation-mediated neurodegeneration in vitro and in vivo as well as on the putative neuroprotective effect of VIP on experimental pathological conditions in which central nervous system (CNS) inflammation is involved, such as brain trauma. The involvement of activated Microglia and their derived cytotoxic products is also studied. VIP has a clear neuroprotective effect on inflammatory conditions by inhibiting the production of Microglia-derived proinflammatory factors (tumor necrosis factor alpha, interleukin-1beta, nitric oxide). In this sense, VIP prevents neuronal cell death following brain trauma by reducing the inflammatory response of neighboring Microglia. Therefore, VIP emerges as a valuable neuroprotective agent for the treatment of pathologic conditions of the CNS where inflammation-induced neurodegeneration occurs

  11. Dimayuga FO, Ding Q, Keller JN, Marchionni MA, Seroogy KB, Bruce-Keller AJ (2003) The neuregulin GGF2 attenuates free radical release from activated Microglial cells. J.Neuroimmunol. 136:67-74
    Abstract: The neuregulin glial growth factor 2 (GGF2) is a neural growth factor that is best known for its ability to promote the survival and proliferation of oligodendrocytes and Schwann cells. While it has been shown in recent years that GGF2 is effective in the treatment of autoimmune models of brain injury, it is not known if the beneficial effects of GGF2 are based in part on modulation of brain inflammation. In this report, we document the anti-inflammatory effects of recombinant human GGF2 (rhGGF2) on Microglial free radical production in vitro. The presence of the neuregulin receptors ErbB2, 3, and 4 was confirmed in N9 Microglial cells by Western blot analysis. Pretreatment of N9 cells with 10-100 ng/ml rhGGF2 24 h before either phorbol 12-myristate 3-acetate (PMA) or interferon gamma (IFNgamma) caused dose-dependent decreases in oxidative burst activity and nitrite release, respectively, with 50 and 100 ng/ml causing significant effects. When cells were co-treated with increasing doses of rhGGF2 and PMA or IFNgamma, only concentrations of 50 ng/ml, but not 10 or 100 ng/ml, were able to decrease oxidative burst activity and nitrite release. Finally, when Microglial cell viability following treatment of cells with IFNgamma with or without rhGGF2 was evaluated, it was observed that 50 and 100 ng/ml rhGGF2 conferred significant protection against IFNgamma-induced cell death in Microglial cells. Overall, these results indicate that the neuregulin rhGGF2 may have anti-inflammatory and antioxidant properties in the brain, and may also provide trophic support for brain-resident Microglial cells

  12. Filipovic R, Jakovcevski I, Zecevic N (2003) GRO-alpha and CXCR2 in the human fetal brain and multiple sclerosis lesions. Dev.Neurosci. 25:279-290
    Abstract: Chemokines, small proinflammatory cytokines, are involved in migration of inflammatory cells, but also have a role in normal central nervous system development. One chemokine, growth-related oncogene-alpha (GRO-alpha) and its receptor CXCR2, are involved in proliferation and migration of oligodendrocyte progenitors in rats. Here we studied the regional and cell type-specific expression of GRO-alpha and CXCR2 in the human telencephalon at midgestation, the time that oligodendrocytes are being generated in the human brain. Our results showed that both GRO-alpha and CXCR2 are predominately expressed by oligodendrocyte progenitors and activated Microglial cells in the highly proliferative subventricular zone. This cellular and regional localization suggests that GRO-alpha/CXCR2 may play a role in human oligodendrocyte proliferation and subsequent migration. We also studied the expression of GRO-alpha and CXCR2 in brain sections of multiple sclerosis (MS) patients. Consistent with their role in the inflammatory process of MS, both GRO-alpha and CXCR2 were expressed in activated Microglia localized on the border of MS lesions. However, neither GRO-alpha nor CXCR2 were present in early oligodendrocyte progenitors, a finding that may partially explain why remyelination is not more efficient in MS

  13. Fukaura H, Kikuchi S (2003) [IL-18 in multiple sclerosis]. Nippon Rinsho 61:1416-1421
    Abstract: IL-18, previously named interferon-gamma inducing factor, is produced by monocytes/macropharges, dendritic cells, B cells and other APC cells as well as by astrocytes, Microglia. IL-18 is a unique cytokine that stimulates both Th1 and Th2 responses depending on its cytokine milieu. Caspase-1 regulates the cellular export of IL-18. Anti IL-18 antibodies prevent EAE. IL-18 directs autoreactive T cells and promotes autodestruction in CNS via induction of IFN-gamma by NK cells in EAE. IL-18 is expressed in MS plaque. Common IL-18 promoter polymorphisms influence the expression on IL-18. IL-18 is linked to raised IFN-gamma in MS and is induced by activated CD4(+) T cells via CD40-CD40 ligand interaction. IL-18 in MS is suppressed by treatments such as GA and IFN-beta

  14. Garcion E, Sindji L, Nataf S, Brachet P, Darcy F, Montero-Menei CN (2003) Treatment of experimental autoimmune encephalomyelitis in rat by 1,25-dihydroxyvitamin D3 leads to early effects within the central nervous system. Acta Neuropathol.(Berl) 105:438-448
    Abstract: We report here that curative treatment of the multiple sclerosis paradigm, chronic relapsing experimental autoimmune encephalomyelitis (EAE) of the Lewis rat, by 1,25-dihydroxyvitamin D(3 )(1,25-D3) leads to a rapid clinical improvement accompanied by an inhibition of CD4, MHC class II and type II nitric oxide synthase (NOS II) expression in the posterior areas of the central nervous system (CNS). In contrast, the hormone has no effect on transforming growth factor-beta1 transcripts. Computer analysis of the NOS II promoter, expressed by Microglia and astrocytes, reveals consensus sequence for vitamin D receptor binding, emphasizing the idea that 1,25-D3 may regulate some aspects of EAE by acting directly on CNS constituent cells. We also demonstrate that vitamin D deprivation leads to minimal effects on the kinetic profile of EAE accompanied by a moderate exacerbation of the clinical symptoms. Interestingly, curative treatment of vitamin D-deprived rats with a non-toxic-1,25-D3 analogue (MC1288) strongly inhibited EAE symptoms, thus promulgating the potential interest of such compounds in the management of multiple sclerosis

  15. Geurts JJ, Wolswijk G, Bo L, van d, V, Polman CH, Troost D, Aronica E (2003) Altered expression patterns of group I and II metabotropic glutamate receptors in multiple sclerosis. Brain 126:1755-1766
    Abstract: Recent evidence supports a role for glutamate receptors in the pathophysiology of multiple sclerosis. In the present study, we have focused specifically on the expression of metabotropic glutamate receptors (mGluRs) in multiple sclerosis brain tissue. The expression of group I (mGluR1alpha and mGluR5) and group II (mGluR2/3) mGluRs was studied using immunohistochemistry in tissue from 12 multiple sclerosis cases and seven non-neurological controls. The expression patterns of both group I and II mGluRs in multiple sclerosis tissue differed significantly from those in control tissue. Strong mGluR1alpha immunoreactivity was observed in axons of the subcortical white matter, particularly in the centre of actively demyelinating lesions and in the borders of chronic active lesions. mGluR1alpha axonal immunopositivity was also found in normal appearing multiple sclerosis white matter, but axons in control white matter were generally negative. mGluR1alpha axonal labelling was associated with the presence of non-phosphorylated neurofilaments and beta-amyloid precursor protein, which are sensitive markers for axonal injury and disturbed axonal transport. Changes in mGluR immunoreactivity were also observed in glia. A diffuse increase in the expression of mGluR5 and mGluR2/3 was detected in reactive astrocytes in multiple sclerosis lesions. However, only a subpopulation of reactive astroglial cells expressed mGluR1alpha. In addition, labelling with antibodies to mGluR2/3 and, to a lesser extent labelling with antibodies to mGluR1alpha, was detected in a population of cells of the Microglial/macrophage lineage that displayed a macrophage-like morphology. Our data suggest that mGluRs, like ionotropic glutamate receptors, play a role in the complex processes that are associated with the progressive brain damage in multiple sclerosis, including both glial activation and pathological changes in axons

  16. Goodman AD, Mock DJ, Powers JM, Baker JV, Blumberg BM (2003) Human herpesvirus 6 genome and antigen in acute multiple sclerosis lesions. J.Infect.Dis. 187:1365-1376
    Abstract: Evidence for a candidate multiple sclerosis (MS) virus, human herpesvirus 6 (HHV-6), was sought in biopsy specimens of acute lesions that presented clinically as cerebral tumors obtained from 5 patients. Histopathology, magnetic resonance imaging, and clinical course confirmed the diagnosis of MS in each case. A sensitive in situ polymerase chain reaction (ISPCR) method was used to detect HHV-6 genome, in conjunction with immunocytochemical staining (ICC) to detect viral and cellular antigens. ISPCR revealed numerous oligodendrocytes, lymphocytes, and Microglia containing HHV-6 genome within all lesions, whereas ICC showed only the HHV-6 glycoprotein 116 antigen in some reactive astrocytes and Microglia. High frequencies of neuroglial and inflammatory cells containing HHV-6 genome were present in acute-phase lesion tissue from patients who were free of the effects of chronic MS and had not been received immunomodulatory therapy for MS. The prevalence of HHV-6 genome-containing cells, including oligodendrocytes, in each lesion suggests that HHV-6 plays a role in the demyelinative pathogenesis of MS; the significance of the discrepant expression of viral antigens remains uncertain

  17. Hisahara S, Okano H, Miura M (2003) Caspase-mediated oligodendrocyte cell death in the pathogenesis of autoimmune demyelination. Neurosci.Res. 46:387-397
    Abstract: multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. MS is believed to be an autoimmune disorder mediated by activated immune cells such as T- and B-lymphocytes and macrophages/Microglia. Lymphocytes are primed in the peripheral tissues by antigens, and clonally expanded cells infiltrate the CNS. They produce large amounts of inflammatory and cytokines that lead to demyelination and axonal degeneration. Although several studies have shown that oligodendrocytes (OLGs), the myelin-forming glial cells in the CNS, are sensitive to cell death stimuli, such as cytotoxic cytokines, anti-myelin antibodies, nitric oxide, and oxidative stress, in vitro, the mechanisms underlying injury to the OLGs in MS/EAE remain unclear. Transgenic mice that express the anti-apoptotic protein specifically in OLGs and caspase-11-deficient mice are significantly resistant to EAE induction. Histopathological analyses show that the number of caspase-activated OLGs and dead OLGs are reduced in the CNS of these mice. The numbers of infiltrating immune cells and the amounts of cytokines are also markedly reduced in EAE lesions. Therefore, caspase-mediated OLG death leads to the exacerbation of demyelination and the deterioration of neurological manifestations by inducing local inflammatory events

  18. Hosokawa M, Klegeris A, Maguire J, McGeer PL (2003) Expression of complement messenger RNAs and proteins by human oligodendroglial cells. Glia 42:417-423
    Abstract: Neurons, astrocytes, Microglia, and endothelial cells are capable of synthesizing most, if not all, of the complement proteins. Little is known, however, about the capacity of oligodendroglial cells to generate complement components. This study evaluated expression of complement mRNAs and their protein products by human oligodendrocytes. Cells were isolated and cultured from white matter of seven adult cases that had undergone surgical temporal lobe resection for epilepsy. Oligodendroglial cultures were characterized by the expression of such cell type-specific mRNAs as myelin proteolipid protein (PLP), oligodendrocyte-specific protein (OSP), and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and were further characterized by immunostaining for such differentiation markers as myelin basic protein (MBP), PLP, CNPase, and O4. RT-PCR analysis showed that the oligodendroglial cells expressed detectable levels of complement mRNAs for the C1q B-chain, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 gamma subunit, and C9. Immunostaining was positive for C1q, C1s, C2, C3, C4, C5, C6, C7, C8, and C9. Double immunostaining for the oligodendrocyte marker O4 and the complement protein C3 demonstrated that all O4-positive cells were also positive for C3, indicating constitutive C3 expression. These results indicate that oligodendroglial cells may be a source of complement proteins in human brain and thus could contribute to the pathogenesis of several neurodegenerative and inflammatory diseases of the CNS, such as Alzheimer's disease, multiple sclerosis, and progressive supranuclear palsy, where complement-activated oligodendrocytes are abundant

  19. Hulshof S, van Haastert ES, Kuipers HF, van den Elsen PJ, De Groot CJ, van d, V, Ravid R, Biber K (2003) CX3CL1 and CX3CR1 expression in human brain tissue: noninflammatory control versus multiple sclerosis. J.Neuropathol.Exp.Neurol. 62:899-907
    Abstract: An important role for CX3CL1 in neuroinflammation and neurodegeneration has been suggested in recent publications. In this study, we compared the expression of CX3CL1 and its receptor CX3CR1 in human brain tissue derived from control patients without neurological complications and in multiple sclerosis (MS) patients. Results from this study demonstrate that CX3CL1 is constitutively expressed in human central nervous system (CNS) astrocytes in vivo and under basal conditions in human adult astrocyte cultures. CX3CR1 is expressed on astrocytes and Microglial cells both in vivo and in vitro. Chemotaxis assay shows a functional response upon CX3CR1 signaling in Microglial cells. Although CX3CL1 expression is upregulated in cultured astrocytes in response to proinflammatory cytokines, no evidence for expression differences of CX3CL1 between control patients and MS patients was found. Our data suggest that CX3CL1 has more general physiological functions, which occur also in the absence of proinflammatory conditions

  20. Kato H, Suzumura A (2003) [Cytokines in MS lesion]. Nippon Rinsho 61:1428-1434
    Abstract: A variety of cytokines are involved in the pathogenesis of multiple sclerosis(MS), either in induction phase and effector phase. In order to interact with immune cells, the cells in the brain have to express MHC antigens which they do not usually express. Cytokines such as IFN gamma, IL-3 and TNF alpha induce MHC antigen expression on neural cells. IFN gamma also induces costimulatory molecule for antigen presentation and also induce IL-12, a critical cytokine in T helper cell differentiation, in Microglia. Although TNF alpha is a critical cytokines in effector phase, other cytokines and chemokines have also been shown to play roles on the development of inflammatory demyelination and gliosis. In this chapter, we will review the cytokine profile of MS lesions

  21. Kielian T, Drew PD (2003) Effects of peroxisome proliferator-activated receptor-gamma agonists on central nervous system inflammation. J.Neurosci.Res. 71:315-325
    Abstract: Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays a critical role in glucose and lipid metabolism. More recently, PPAR-gamma ligands have been reported to inhibit the expression of proinflammatory molecules by monocytes/macrophages. Of relevance to CNS disease is that PPAR-gamma agonists have been demonstrated to have similar effects on Microglia. PPAR-gamma agonists also ameliorate experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. This Mini-Review summarizes the effects of PPAR-gamma agonists in mediating immune responses and the potential of these agonists in the treatment of inflammatory disorders of the CNS

  22. Kleine TO, Zwerenz P, Graser C, Zofel P (2003) Approach to discriminate subgroups in multiple sclerosis with cerebrospinal fluid (CSF) basic inflammation indices and TNF-alpha, IL-1beta, IL-6, IL-8. Brain Res.Bull. 61:327-346
    Abstract: Lumbar CSF and serum pairs of untreated multiple sclerosis patients (MS; n=47) were analyzed on admission. On average, higher CSF leukocyte (lymphocyte and monocyte) counts, IgG index, CSF IgG contents, but not of TNF-alpha, IL-1beta, IL-6, IL-8 in CSF and serum, were revealed in all MS or patients with long disease course (LO-MS) compared with controls. In primary progressive MS (PP-MS) cell counts were low, but IgG contents were high, when compared to relapsing-remitting MS (RR-MS). In clinically probable MS (CP-MS) both contents were low, in clinically definite MS (CD-MS) high. Spearman's correlation with the four monokines and the basic indices in CSF revealed activation patterns known for Microglia/macrophages in the four MS subgroups, for astrocytes in CP-MS and RR-MS, for CSF lymphocytes in CP-MS and PP-MS, for cells of blood-brain barrier (BBB) in CP-MS, for intrathecal IgG synthesis in PP-MS and for lymphocyte transfer in CD-MS. Correlations between CSF and serum parameters indicated CNS disease processes to be associated with systemic processes of inflammation (acute, chronic) in CD-MS, RR-MS, and PP-MS in different ways. CSF IgG content, IgG index and systemic markers of inflammation correlated with overall disability scores in LO-MS; increasing levels may indicate a bad outcome

  23. Kwidzinski E, Mutlu LK, Kovac AD, Bunse J, Goldmann J, Mahlo J, Aktas O, Zipp F, Kamradt T, Nitsch R, Bechmann I (2003) Self-tolerance in the immune privileged CNS: lessons from the entorhinal cortex lesion model. J.Neural Transm.Suppl29-49
    Abstract: Upon peripheral immunization with myelin epitopes, susceptible rats and mice develop T cell-mediated demyelination similar to that observed in the human autoimmune disease multiple sclerosis (MS). In the same animals, brain injury does not induce autoimmune encephalomyelitis despite massive release of myelin antigens and early expansion of myelin specific T cells in local lymph nodes, indicating that the self-specific T cell clones are kept under control. Using entorhinal cortex lesion (ECL) to induce axonal degeneration in the hippocampus, we identified possible mechanisms of immune tolerance after brain trauma. Following ECL, astrocytes upregulate the death ligand CD95L, allowing apoptotic elimination of infiltrating activated T cells. Myelin-phagocytosing Microglia express MHC-II and the costimulatory molecule CD86, but lack CD80, which is found only on activated antigen presenting cells (APCs). Restimulation of invading T cells by such immature APCs (e.g. CD80 negative Microglia) may lead to T cell anergy and/or differentiation of regulatory/Th3-like cells due to insufficient costimulation and presence of high levels of TGF-beta and IL-10 in the CNS. Thus, T cell -apoptosis, -anergy, and -suppression apparently maintain immune tolerance after initial expansion of myelin-specific T lymphocytes following brain injury. This view is supported by a previous metastatistical analysis which rejected the hypothesis that brain trauma is causative of MS (Goddin et al., 1999). However, concomitant trauma-independent proinflammatory signals, e.g., those evoked by clinically quiescent infections, may trigger maturation of APCs, thus shifting a delicate balance from immune tolerance and protective immune responses to destructive autoimmunity

  24. Lampe JB, Schneider-Schaulies S, Aguzzi A (2003) Expression of the interferon-induced MxA protein in viral encephalitis. Neuropathol.Appl.Neurobiol. 29:273-279
    Abstract: MxA protein accumulates cytoplasmically in response to interferon stimulation, and mediates resistance against several viruses. In order to test whether MxA may serve as a diagnostic tool for viral infections of the central nervous system (CNS), we performed MxA immunohistochemistry on biopsies and autopsies of 57 patients with neurological disorders of known viral and nonviral aetiology. MxA was detectable in all HIV patients with proven opportunistic viral encephalitis, in all patients suffering from isolated viral encephalitis, in one of three HIV patients with cerebral toxoplasmosis, and in one case of micronodular encephalitis. No MxA was detectable in HIV patients with isolated HIV encephalitis or HIV infection accompanied by an opportunistic nonviral disorder. We were unable to show MxA expression in a variety of nonviral inflammatory and noninflammatory disorders of the CNS. Several cases of Rasmussen's encephalitis and multiple sclerosis tested negative, arguing against their possible viral aetiology. Two-colour immunohistochemistry identified macrophages and activated Microglia as MxA expressing cells. In all studied cases MxA expression was accompanied by a marked T-cell infiltrate. Therefore, the detection of MxA-protein is a sensitive adjuvant marker for those cases of viral encephalitis which are accompanied by pronounced lymphocytic infiltrates

  25. Lassmann H (2003) Hypoxia-like tissue injury as a component of multiple sclerosis lesions. J.Neurol.Sci. 206:187-191
    Abstract: Recent data suggest that the mechanisms of demyelination and tissue damage in multiple sclerosis (MS) are heterogenous. In this review, evidence is discussed, which show that in a subset of multiple sclerosis patients the central nervous system (CNS) lesions show profound similarities to tissue alterations found in acute white matter stroke, thus suggesting that a hypoxia-like metabolic injury is a pathogenetic component in a subset of inflammatory brain lesions. Both, vascular pathology as well as metabolic disturbances induced by toxins of activated macrophages and Microglia may be responsible for such lesions in multiple sclerosis

  26. Lieb K, Engels S, Fiebich BL (2003) Inhibition of LPS-induced iNOS and NO synthesis in primary rat Microglial cells. Neurochem.Int. 42:131-137
    Abstract: Nitric oxide (NO) has been implicated in the etiopathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), and inhibition of NO synthesis has been proposed to be a possible mechanism of action of drugs to treat MS. In the present study, we investigated the inhibitory effect on NO synthesis of various steroids, cytokines and drugs used or proposed for the treatment of MS. As a model system, we used primary rat Microglial cells which produce NO synthase and subsequently release NO upon stimulation with lipopolysaccharide (LPS). Among the substances tested, the glucocorticoids prednisone, hydrocortisone, dexamethasone and progesterone as well as transforming growth factor-beta (TGF-beta) dose-dependently inhibited LPS-induced nitric oxide synthase (iNOS) and NO synthesis. In contrast, COP-1, the phosphodiesterase inhibitors rolipram and pentoxifylline, the cytokines interleukin-10 (IL-10) and interferon-beta (IFN-beta) as well as the steroids beta-estradiol, testosterone, and dehydroepiandrosterone (DHEA) showed no inhibitory effect. Cholesterol slightly, but not significantly, increased LPS-induced nitric oxide synthesis. We conclude from the present study that with respect to treatment of MS, inhibition of NO synthesis may be an important mechanism of action of glucocorticoids and transforming growth factor-beta, but not of other drugs used or proposed to treat MS

  27. Luttichau HR, Clark-Lewis I, Jensen PO, Moser C, Gerstoft J, Schwartz TW (2003) A highly selective CCR2 chemokine agonist encoded by human herpesvirus 6. J.Biol.Chem. 278:10928-10933
    Abstract: The chemokine-like, secreted protein product of the U83 gene from human herpesvirus 6, here named vCCL4, was chemically synthesized to be characterized in a complete library of the 18 known human chemokine receptors expressed individually in stably transfected cell lines. vCCL4 was found to cause calcium mobilization as efficiently as the endogenous chemokine ligand CCL2 through the CCR2 receptor, whereas the virally encoded chemokine did not affect any of the other 17 human chemokine receptors tested. Mutual cross-desensitization between CCL2 and vCCL4 was demonstrated in the CCR2-transfected cells. The affinity of vCCL4 for the CCR2 receptor was 79 nm as determined in competition binding against radioactively labeled CCL2. In the murine pre-B lymphocyte cell line L1.2 stably transfected with the CCR2 receptor, vCCL4 acted as a relatively low potency but highly efficacious chemoattractant being equally or more efficacious in causing cell migration than CCL2 and CCL7 and considerably more efficacious than CCL8 and CCL13. It is concluded that human herpesvirus 6 encodes a highly selective and efficacious CCR2 agonist, which will attract CCR2 expressing cells, for example macrophages and monocytes, conceivably for the virus to infect and to establish latency in. It is suggested that vCCL4 during reactivation of the virus in for example monocyte-derived Microglia could perhaps be involved in the pathogenesis of the CCR2-dependent disease, multiple sclerosis

  28. Milicevic I, Pekovic S, Subasic S, Mostarica-Stojkovic M, Stosic-Grujicic S, Medic-Mijacevic L, Pejanovic V, Rakic L, Stojiljkovic M (2003) Ribavirin reduces clinical signs and pathological changes of experimental autoimmune encephalomyelitis in Dark Agouti rats. J.Neurosci.Res. 72:268-278
    Abstract: The effect of ribavirin on development of experimental autoimmune encephalomyelitis (EAE) was investigated. The disease was induced in genetically susceptible Dark Agouti rats with syngeneic spinal cord homogenate in complete Freund's adjuvant (SCH-CFA). Depending on the amount of mycobacteria in CFA, the animals developed either moderate or severe EAE. Ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was applied i.p. at a daily dosage of 30 mg/kg in two treatment protocols: from the start of immunization (preventive treatment) or from the onset of the first EAE signs after the induction (therapeutic treatment). Signs of EAE began between 7 and 9 days after induction and peaked at days 11-13. In moderate EAE (mean maximal severity score 3.33 +/- 0.21), the recovery was completed by days 23-26, whereas, in severe EAE (mean maximal severity score 4.5 +/- 0.23), obvious recovery was not detected. Preventive ribavirin treatment significantly decreased clinical signs after both moderate (score 1.75 +/- 0.25, P < 0.05) and severe (score 3.62 +/- 0.31, P < 0.015) immunization. Also, disease manifestations were reduced by therapeutic treatment of ribavirin (mean maximal severity score 2.5 +/- 0.2 vs. 3.33 +/- 0.21 in controls, P < 0.005) but less so in comparison with preventive treatment. Analysis of the effects of ribavirin on histopathologic changes in the spinal cord tissue revealed a reduction of mononuclear cell infiltrates, composed of T cells and macrophages/Microglia, and the absence of demyelination, which were pronounced in control EAE animals. Beneficial effects of preventive and therapeutic treatment with ribavirin on development of EAE suggest this nucleoside analogue as a useful candidate for therapy in multiple sclerosis

  29. Mizuno T, Kawanokuchi J, Numata K, Suzumura A (2003) Production and neuroprotective functions of fractalkine in the central nervous system. Brain Res. 979:65-70
    Abstract: The CX3C-chemokine, fractalkine is reportedly to be expressed in the central nervous system, and up-regulated in certain pathological conditions, such as HIV encephalopathy and multiple sclerosis. In the present study, we examined the production of fractalkine and the expression of its receptor, CX3CR1 in murine glial and neuronal cell in vitro, and investigated its neuroprotective functions. Both fractalkine and CX3CR1 were expressed constitutively in neurons, Microglia, and astrocytes. Neither the production of fractalkine nor its receptor expression was up-regulated by lipopolysaccharide (LPS), as measured by mRNA expression and protein synthesis. Fractalkine dose-dependently suppressed the production of nitric oxide (NO), interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha with activated Microglia. It also significantly suppressed neuronal cell death induced by Microglia activated with LPS and interferon-gamma, in a dose-dependent manner. These results suggest the possible functions of fractalkine as an intrinsic inhibitor against neurotoxicity by activated Microglia

  30. Mokhtarian F, Huan CM, Roman C, Raine CS (2003) Semliki Forest virus-induced demyelination and remyelination--involvement of B cells and anti-myelin antibodies. J.Neuroimmunol. 137:19-31
    Abstract: Semliki Forest virus (SFV) infection induces a demyelinating encephalomyelitis in the central nervous system (CNS) of mice and serves as a model for multiple sclerosis (MS). This study investigated CNS immune responses at different stages of infection and during SFV-induced demyelination and remyelination. Following the initial CNS inflammation, pathology and viral clearance on days 6-10 post-infection (pi), primary demyelination was observed in cerebellar, brainstem and corpus collosal white matter by days 15-21 pi, with plasma cells and Microglia as main participants, and this was followed by remyelination. By day 35 pi, the tissue appeared almost normal. Fluorescent antibody cell sorter (FACS) analysis showed that brain CD8(+) T cells increased during the initial inflammatory response and gradually decreased thereafter. Brain B cell (B220(+)CD19(+)) numbers did not change significantly during the course of infection; however, from days 14 to 35 pi, they matured and produced antibodies to viral and myelin proteins (and peptides) during the period of demyelination and remyelination. The proportion of CD3(-)B220(-)CD11b(+) cells also progressively increased throughout the periods of de- and remyelination. Our results suggest that CD8(+) T cells are involved in the initial destruction of CNS tissue during the first weeks of SFV infection, while B cells, antibodies and Microglia may contribute to the myelin pathology seen after recovery

  31. Molina-Monasterios MC, Molina-Abecia H (2003) [Nasu Hakola disease: a report of the first two cases in Bolivia]. Rev.Neurol. 36:837-840
    Abstract: INTRODUCTION: Nasu Hakola disease (NHD) is a progressive dementia that presents accompanied by bone cysts and, at random, epilepsy. It is an autosomal recessive hereditary disease and its genetic defect is located at the 19q13.1 chromosome. The genetic mutation was identified at DAP 12. It appears that DAP 12 is expressed in the Microglial activation and the differentiation of macrophages in the central nervous system and, at the same time, in the osteoclasts in charge of bone remodelling. This double character consisting of dementia and bone cysts, which contain triglycerides and thin PAS positive membranes in a bone with cortical erosion and medullary hypoplasia, enables us to differentiate this disease from other frontotemporal neurodegenerative disorders, such as Pick s disease. At the same time this also allows it to be distinguished from multiple sclerosis, metachromatic leukodystrophy, Marchafava Bignami disease, and prion diseases (such as new variant Creutzfeldt Jakob). CASE REPORTS: In this paper we describe two cases of NHD, also known as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy, in which progressive dementia, bone cysts and epilepsy were identified. Serious brain atrophy was found and confirmed by imaging studies and brain biopsies, which were also used to rule out other degenerative diseases of the frontal lobe, as well as Creutzfeldt Jakob disease. CONCLUSIONS: Both cases meet all the necessary criteria to satisfy a diagnosis of NHD. This is a hereditary, little known disease whose genetic alterations (i.e. mutations) are still in need of further study. It mainly affects males, who suffer the onset of dementia in their thirties. The neurological disorders constitute a frontal syndrome, due to predominant prefrontal involvement, and they occur in the dorsolateral area, with disorders affecting the executive and planning functions; in the orbitofrontal area, which is reflected in social maladjustment and clear obsessive compulsive traits; and also in the medial or cingulate area, which manifests itself as apathy and lack of motivation. When dealing with this disease, in addition to symptomatic therapy, genetic counselling is also important

  32. Nakanishi H (2003) Microglial functions and proteases. Mol.Neurobiol. 27:163-176
    Abstract: There is accumulating evidence that intracellular and extracellular proteases of Microglia contribute to various events in the central nervous system (CNS) through both nonspecific and limited proteolysis. Cathepsin E and cathepsin S, endosomal/lysosomal proteases, have been shown to play important roles in the major histocompatibility complex (MHC) class II-mediated antigen presentation of Microglia by processing of exogenous antigens and degradation of the invariant chain associated with MHC class II molecules, respectively. Some members of cathepsins are also involved in neuronal death after secreted from Microglia and clearance of phagocytosed amyloid- beta peptides. Tissue-type plasminogen activator, a serine protease, secreted from Microglia participates in neuronal death, enhancement of N-methyl-D-aspartate receptor-mediated neuronal responses, and activation of Microglia via either proteolytic or nonproteolytic activity. Calpain, a calcium-dependent cysteine protease, has been shown to play a pivotal role in the pathogenesis of multiple sclerosis by degrading myelin proteins extracellulary. Furthermore, matrix metalloproteases secreted from Microglia also receive great attention as mediators of inflammation and tissue degradation through processing of pro-inflammatory cytokines and damage to the blood-brain barrier. The growing knowledge about proteolytic events mediated by Microglial proteases will not only contribute to better understanding of Microglial functions in the CNS but also may aid in the development of protease inhibitors as novel neuroprotective agents

  33. Neumann H (2003) Molecular mechanisms of axonal damage in inflammatory central nervous system diseases. Curr.Opin.Neurol. 16:267-273
    Abstract: PURPOSE OF REVIEW: Axonal dysfunction and damage is an early pathological sign of autoimmune central nervous system disease, viral and bacterial infections, and brain trauma. Axonal injury has attracted considerable interest during the past few years because the degree of axonal damage appears to determine long-term clinical outcome. RECENT FINDINGS: Advanced magnetic resonance spectroscopic imaging techniques have suggested that axonal loss and dysfunction is responsible for the persistent neurological deficits that occur in patients with multiple sclerosis. Histopathological methods have shown that axonal damage is defined primarily by dysfunction of axonal transport, and finally by complete transection and degeneration of axons. Recent studies have demonstrated that the extent of axonal damage in the primary demyelinating lesion of multiple sclerosis patients is associated with the number of activated Microglia/macrophages and cytotoxic CD8+ T lymphocytes. In addition, diffuse axonal dysfunction independent of demyelination develops in normal appearing white matter, possibly due to indirect effects of inflammation. SUMMARY: The fact that axonal damage in response to overt inflammatory reactions may occur gradually, leaving a window for therapeutical intervention, has important clinical implications. Determination of the exact molecular mechanism might help in finding new therapies for inflammatory axonal damage

  34. Olson JK, Zamvil SS, Miller SD (2003) Efficient technique for immortalization of murine Microglial cells relevant for studies in murine models of multiple sclerosis. J.Neurosci.Methods 128:33-43
    Abstract: Microglia are macrophage-like cells that populate the central nervous system (CNS) and become activated upon injury or infection. Microglia have been implicated as playing critical roles in various CNS diseases including multiple sclerosis (MS), a human autoimmune demyelinating disease, as well as in other neurodegenerative diseases. Two well-characterized models of MS, relapsing experimental autoimmune encephalomyelitis (R-EAE) and Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease, are inducible in SJL mice and model the relapsing-remitting and chronic-progressive forms of MS, respectively. These models are useful for the study of the mechanisms of initiation, progression, and therapy of the disease. Currently, a major limitation to studying the functions of Microglia in these murine models of MS is the restricted number of cells capable of being isolated from the CNS of neonatal mice and propagated in culture. The current studies describe the preparation of SV-40 large T antigen-immortalized mouse Microglia lines, M4T.4 and M4T.6, from the SJL/J mice. The immortalization technique was very efficient requiring only 6 weeks to develop long-term, highly replicating cell lines. The resulting Microglia cell lines remain quiescent, but are induced to express various immune cytokines and to function as efficient antigen presenting cells upon activation with IFN-gamma or infection with TMEV. Thus, the SV-40 large T antigen immortalized Microglia lines react to innate and infectious stimuli similar to primary Microglia isolated from neonatal mice, but are more easily maintained in culture. This technique should allow for the efficient cultivation of large numbers of Microglial cells from a variety of disease-relevant mouse strains, including knock-out and transgenic mice

  35. Palma JP, Kwon D, Clipstone NA, Kim BS (2003) Infection with Theiler's murine encephalomyelitis virus directly induces proinflammatory cytokines in primary astrocytes via NF-kappaB activation: potential role for the initiation of demyelinating disease. J.Virol. 77:6322-6331
    Abstract: Theiler's virus infection in the central nervous system (CNS) induces a demyelinating disease very similar to human multiple sclerosis. We have assessed cytokine gene activation upon Theiler's murine encephalomyelitis virus (TMEV) infection and potential mechanisms in order to delineate the early events in viral infection that lead to immune-mediated demyelinating disease. Infection of SJL/J primary astrocyte cultures induces selective proinflammatory cytokine genes (interleukin-12p40 [IL-12p40], IL-1, IL-6, tumor necrosis factor alpha, and beta interferon [IFN-beta]) important in the innate immune response to infection. We find that TMEV-induced cytokine gene expression is mediated by the NF-kappaB pathway based on the early nuclear NF-kappaB translocation and suppression of cytokine activation in the presence of specific inhibitors of the NF-kappaB pathway. Further studies show this to be partly independent of dsRNA-dependent protein kinase (PKR) and IFN-alpha/beta pathways. Altogether, these results demonstrate that infection of astrocytes and other CNS-resident cells by TMEV provides the early NF-kappaB-mediated signals that directly activate various proinflammatory cytokine genes involved in the initiation and amplification of inflammatory responses in the CNS known to be critical for the development of immune-mediated demyelination

  36. Perry VH, Newman TA, Cunningham C (2003) The impact of systemic infection on the progression of neurodegenerative disease. Nat.Rev.Neurosci. 4:103-112

  37. Platten M, Eitel K, Wischhusen J, Dichgans J, Weller M (2003) Involvement of protein kinase Cdelta and extracellular signal-regulated kinase-2 in the suppression of Microglial inducible nitric oxide synthase expression by N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast). Biochem.Pharmacol. 66:1263-1270
    Abstract: Excess nitric oxide (NO) in the brain released by Microglial cells contributes to neuronal damage in various pathologies of the central nervous system (CNS) including neurodegenerative diseases and multiple sclerosis. N-[3,4-Dimethoxycinnamoyl]-anthranilic acid (tranilast, TNL) is an anti-allergic compound which suppresses the activation of monocytes. We show that inducible nitric oxide synthase (iNOS) mRNA and protein expression and the release of NO from N9 Microglial cells stimulated with the bacterial endotoxin lipopolysaccharide (LPS) are inhibited when the cells are exposed to TNL. TNL fails to modulate LPS-stimulated nuclear factor-kappaB (NF-kappaB) reporter gene activity and phosphorylation of inhibitory kappaB (IkappaB), indicating that NF-kappaB is not involved in the TNL-mediated suppression of LPS-induced iNOS expression. Moreover, TNL inhibits LPS-induced phosphorylation of extracellular signal-regulated kinase 2 (ERK-2). Finally, TNL abolishes translocation of protein kinase Cdelta (PKCdelta) to the nucleus and suppresses the phosphorylation of the PKCdelta substrate, myristoylated alanin-rich C kinase substrate (MARCKS). We conclude that the anti-allergic compound TNL suppresses Microglial iNOS induction by LPS via inhibition of a signalling pathway involving PKCdelta and ERK-2

  38. Rotshenker S (2003) Microglia and Macrophage Activation and the Regulation of Complement-Receptor-3 (CR3/MAC-1)-Mediated Myelin Phagocytosis in Injury and Disease. J.Mol.Neurosci. 21:65-72
    Abstract: Microglia and macrophages play critical roles in the response of the central and peripheral nervous systems (CNS and PNS, respectively) to injury and disease, one of which is the removal of degenerated myelin by phagocytosis. Myelin removal is efficient during Wallerian degeneration, which follows injury to PNS axons, and in CNS autoimmune demyelinating diseases (e.g., multiple sclerosis) but is inefficient after injury to CNS axons. We suggest that inefficient myelin removal results from deficient Microglia activation, reflected by the failure to up-regulate Galectin-3/MAC-2 expression, which marks a state of activation correlated with efficient myelin phagocytosis. Surprisingly, whether or not executing myelin phagocytosis, CNS Microglia express the alphaM/beta2 integrin complement receptor-3 (CR3/MAC-1), which has the potential of mediating efficient myelin phagocytosis. We hypothesize that CR3/MAC-1 might be present in distinct inactive and active states that determine, respectively, efficient and inefficient CR3/MAC-1-mediated myelin phagocytosis. We present evidence that CR3/MAC-1-mediated myelin phagocytosis is regulated in Microglia and macrophages. First, CR3/MAC-1- mediated myelin phagocytosis has complement-dependent and -independent components. Second, an active complement system augments CR3/MAC-1-mediated myelin phagocytosis. Third, anti-alphaM monoclonal antibodies (MAbs) inhibit and anti-beta2 MAbs augment CR3/MAC-1-mediated myelin phagocytosis in the presence and absence of an active complement system. Fourth, an active complement system modulates MAb-induced regulation of CR3/MAC-1-mediated myelin phagocytosis. Overall, MAb-induced phagocytosis regulation might range three- to sevenfold from inefficient to efficient. We suggest that one of the mechanisms underlying MAbinduced phagocytosis regulation is the induction/stabilization of inactive and active conformational changes. Monoclonal antibody-induced phagocytosis regulation must reveal a mechanism by which native extracellular molecules bind to and regulate CR3/MAC-1-mediated myelin phagocytosis in Microglia and macrophages

  39. Schmidt J, Metselaar JM, Wauben MH, Toyka KV, Storm G, Gold R (2003) Drug targeting by long-circulating liposomal glucocorticosteroids increases therapeutic efficacy in a model of multiple sclerosis. Brain 126:1895-1904
    Abstract: High-dose glucocorticosteroid hormones are a mainstay in the treatment of relapses in multiple sclerosis. We searched for a way to deliver ultra high doses of glucocorticosteroids to the CNS of rats with experimental autoimmune encephalomyelitis (EAE) using a novel formulation of polyethylene glycol (PEG)-coated long-circulating liposomes encapsulating prednisolone (predni solone liposomes, PL). 3H-labelled PL showed selective targeting to the inflamed CNS, where up to 4.5-fold higher radioactivity was achieved than in healthy control animals. HPLC revealed much higher and more persistent levels of prednisolone in spinal cord after PL compared with an equal dose of free prednisolone. Gold-labelled liposomes could be detected in the target tissue, mostly taken up by macrophages (Mphi), Microglial cells and astrocytes. Blood-brain barrier disruption was greatly reduced by 10 mg/kg PL, which was superior to a 5-fold higher dose of free methylprednisolone (MP). PL was also superior to MP in diminishing T-cell infiltration by induction of T-cell apoptosis in spinal cord. Mphi infiltration was clearly decreased only by PL. The percentage of tumour necrosis factor-alpha (TNF-alpha)-positive T cells or Mphi was greatly reduced by PL and by MP. No adverse effects on glial cells were detected. A single injection of PL clearly ameliorated the course of adoptive transfer EAE and EAE induced by immunization. In conclusion, PL is a highly effective drug in treatment of EAE, and is superior to a 5-fold higher dose of free MP, possibly by means of drug targeting. These findings may have implications for future therapy of autoimmune disorders such as multiple sclerosis

  40. Schroeter M, Stoll G, Weissert R, Hartung HP, Lassmann H, Jander S (2003) CD8+ phagocyte recruitment in rat experimental autoimmune encephalomyelitis: association with inflammatory tissue destruction. Am.J.Pathol. 163:1517-1524
    Abstract: Increasing evidence suggests an important role of CD8(+) cells in the pathogenesis of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). In our present study we analyzed the spatiotemporal expression pattern of the CD8 antigen in various rat EAE models characterized by a different extent of inflammation, demyelination, and axonal injury. Unexpectedly, in chronic demyelinating EAE induced by immunization against myelin oligodendrocyte glycoprotein (MOG) the majority of CD8 immunoreactivity was expressed on ED1(+) Microglia/macrophages whereas only limited CD8(+) T-cell infiltration was present. CD8(+) phagocyte recruitment was restricted to sites of severe inflammatory tissue destruction. Contrastingly, macrophages in a perivascular or submeningeal position and in secondarily degenerating fiber tracts were mostly CD8(-). CD8(+) phagocytes were absent in myelin basic protein-induced EAE characterized by a purely inflammatory pathology and lack of demyelination. Our data demonstrate significant heterogeneity of lesion-associated phagocytes in rat models of central nervous system autoimmune disease and suggest a specific role of CD8(+) Microglia/macrophages in the pathogenesis of inflammatory tissue damage

  41. Stangel M, Bernard D (2003) Polyclonal IgM influence oligodendrocyte precursor cells in mixed glial cell cultures: implications for remyelination. J.Neuroimmunol. 138:25-30
    Abstract: Polyclonal immunoglobulins for intravenous use (IVIg) are a potent immunomodulator and have been shown to be effective in several immune-mediated diseases. This includes inflammatory demyelinating diseases of the central nervous system (CNS) like multiple sclerosis (MS). Besides their immunomodulatory function, IVIg have been proposed to enhance remyelination based on studies in the animal model of Theiler's murine encephalomyelitis virus (TMEV). Disappointingly, recent treatment trials in patients with MS have failed to demonstrate repair of longstanding deficits. Since the clinical trials have used IVIg that contained nearly exclusively IgG, whereas the most pronounced effect in TMEV was seen with IgM, this could be a possible explanation for the negative outcome in the MS trials. Here we have examined the effects of a new polyclonal IgM preparation (IVIgM) on cultured oligodendrocyte precursor cells (OPCs). To achieve successful remyelination, OPCs proliferate, migrate, and differentiate into mature myelinating oligodendrocytes. IVIgM and commercial IVIg preparations had no influence on proliferation and differentiation of either isolated OPCs or OPCs in coculture with Microglia. In contrast, IVIgM inhibited the proliferation of OPCs in mixed glial cultures containing astrocytes and Microglia. This was not seen in cultures treated with IVIg, albumin, or interferon-gamma (IFN-gamma), suggesting that this is a specific effect of IVIgM. Differentiation was slightly delayed by IVIgM in mixed glial cultures, but this was not statistically significant and interferon-gamma had a similar effect. These results underline the importance of IgM in influencing OPCs and corroborate the in vivo findings that polyclonal IgM are more potent than IgG in their capacity to influence remyelination. The exact mechanism of how this modulation of OPCs is achieved remains unknown, but a complex interaction among all cells present in the CNS has to be postulated

  42. Takahashi JL, Giuliani F, Power C, Imai Y, Yong VW (2003) Interleukin-1beta promotes oligodendrocyte death through glutamate excitotoxicity. Ann.Neurol. 53:588-595
    Abstract: Glutamate excitotoxicity is implicated in the progressive loss of oligodendrocytes in multiple sclerosis, but how glutamate metabolism is dysregulated in the disease remains unclear. Because there is Microglia activation in all stages of multiple sclerosis, we determined whether a Microglia product, interleukin-1beta, could provide the mechanism for glutamate excitotoxicity. We found that whereas interleukin-1beta did not kill oligodendrocytes in pure culture, it produced apoptosis of oligodendrocytes in coculture with astrocytes and Microglia. This requirement for a mixed glia environment suggests that interleukin-1beta impairs the well-described glutamate-buffering capacity of astrocytes. In support, antagonists at AMPA/kainate glutamate receptors, NBQX and CNQX, blocked the interleukin-1beta toxicity to oligodendrocytes. Another Microglia/macrophage cytokine, tumor necrosis factor-alpha, also evoked apoptosis of oligodendrocytes in a mixed glia environment in an NBQX-blockable manner. These results provide a mechanistic link between the persistent and insidious Microglia activation that is evident in all stages of multiple sclerosis, with the recent appreciation that glutamate excitotoxicity leads to the destruction of oligodendrocytes in the disease

  43. Taylor WR, Rasley A, Bost KL, Marriott I (2003) Murine gammaherpesvirus-68 infects Microglia and induces high levels of pro-inflammatory cytokine production. J.Neuroimmunol. 136:75-83
    Abstract: Murine gammaherpesvirus-68 (MHV-68) has been established as a tractable model for the study of human herpesvirus infections. Recent associations between herpesvirus infections and inflammatory central nervous system (CNS) disorders, including multiple sclerosis (MS), have prompted us to investigate the susceptibility of cultured Microglia and astrocytes to MHV-68 infection. In the present study, we demonstrate that MHV-68 can infect both cell types. Importantly, we show that MHV-68-infected Microglia and astrocytes can produce pro-inflammatory cytokines. Such cytokine production may either contribute to protective host responses to viral challenges or could exacerbate damaging CNS inflammation

  44. Teige I, Treschow A, Teige A, Mattsson R, Navikas V, Leanderson T, Holmdahl R, Issazadeh-Navikas S (2003) IFN-beta gene deletion leads to augmented and chronic demyelinating experimental autoimmune encephalomyelitis. J.Immunol. 170:4776-4784
    Abstract: Since the basic mechanisms behind the beneficial effects of IFN-beta in multiple sclerosis (MS) patients are still obscure, here we have investigated the effects of IFN-beta gene disruption on the commonly used animal model for MS, experimental autoimmune encephalomyelitis (EAE). We show that IFN-beta knockout (KO) mice are more susceptible to EAE than their wild-type (wt) littermates; they develop more severe and chronic neurological symptoms with more extensive CNS inflammation and demyelination. However, there was no discrepancy observed between wt and KO mice regarding the capacity of T cells to proliferate or produce IFN-gamma in response to recall Ag. Consequently, we addressed the effect of IFN-beta on encephalitogenic T cell development and the disease initiation phase by passive transfer of autoreactive T cells from KO or wt littermates to both groups of mice. Interestingly, IFN-beta KO mice acquired a higher incidence and augmented EAE regardless of the source of T cells. This shows that the anti-inflammatory effect of endogenous IFN-beta is predominantly exerted on the effector phase of the disease. Histopathological investigations of CNS in the effector phase revealed an extensive Microglia activation and TNF-alpha production in IFN-beta KO mice; this was virtually absent in wt littermates. This coincided with an increase in effector functions of T cells in IFN-beta KO mice, as measured by IFN-gamma and IL-4 production. We suggest that lack of endogenous IFN-beta in CNS leads to augmented Microglia activation, resulting in a sustained inflammation, cytokine production, and tissue damage with consequent chronic neurological deficits

  45. Trebst C, Staugaitis SM, Kivisakk P, Mahad D, Cathcart MK, Tucky B, Wei T, Rani MR, Horuk R, Aldape KD, Pardo CA, Lucchinetti CF, Lassmann H, Ransohoff RM (2003) CC chemokine receptor 8 in the central nervous system is associated with phagocytic macrophages. Am.J.Pathol. 162:427-438
    Abstract: CC chemokine receptor 8 (CCR8) has been detected in vitro on type 2 helper and regulatory lymphocytes, which might exert beneficial functions in multiple sclerosis (MS) and on macrophages and Microglia, possibly promoting tissue injury in MS lesions. To discriminate the relevant expression pattern in vivo, we defined the cell types that expressed CCR8 in MS lesions and determined the relationship of CCR8 expression and demyelinating activity. CCR8 was not expressed on T cells but was associated with phagocytic macrophages and activated Microglia in MS lesions and directly correlated with demyelinating activity. To identify factors associated with CCR8 expression, the study was extended to other central nervous system (CNS) pathologies. CCR8 was consistently expressed on phagocytic macrophages and activated Microglia in stroke and progressive multifocal leukoencephalopathy, but not expressed on Microglia in pathologies that lacked phagocytic macrophages such as senile change of the Alzheimer's type. CCR8 was up-regulated by macrophage differentiation and activating stimuli in vitro. In summary CNS CCR8 expression was associated with phagocytic macrophages and activated Microglial cells in human CNS diseases, suggesting that CCR8 may be a feasible target for therapeutic intervention in MS. CCR8 expression may also indicate a selective program of mononuclear phagocyte gene expression

  46. Tsunoda I, Kuang LQ, Libbey JE, Fujinami RS (2003) Axonal injury heralds virus-induced demyelination. Am.J.Pathol. 162:1259-1269
    Abstract: Axonal pathology has been highlighted as a cause of neurological disability in multiple sclerosis. The Daniels (DA) strain of Theiler's murine encephalomyelitis virus infects the gray matter of the central nervous system of mice during the acute phase and persistently infects the white matter of the spinal cord during the chronic phase, leading to demyelination. This experimental infection has been used as an animal model for multiple sclerosis. The GDVII strain causes an acute fatal polioencephalomyelitis without demyelination. Injured axons were detected in normal appearing white matter at 1 week after infection with DA virus by immunohistochemistry using antibodies specific for neurofilament protein. The number of damaged axons increased throughout time. By 2 and 3 weeks after infection, injured axons were accompanied by parenchymal infiltration of Ricinus communis agglutinin I(+) Microglia/macrophages, but never associated with perivascular T-cell infiltration or obvious demyelination until the chronic phase. GDVII virus infection resulted in severe axonal injury in normal appearing white matter at 1 week after infection, without the presence of macrophages, T cells, or viral antigen-positive cells. The distribution of axonal injury observed during the early phase corresponded to regions where subsequent demyelination occurs during the chronic phase. The results suggest that axonal injury might herald or trigger demyelination

  47. Versijpt J, Van Laere K, Dierckx RA, Dumont F, De Deyn PP, Slegers G, Korf J (2003) Scintigraphic visualization of inflammation in neurodegenerative disorders. Nucl.Med.Commun. 24:209-221
    Abstract: In the past few decades, our understanding of the central nervous system has evolved from one of an immune-privileged site, to one where inflammation is pathognomonic for some of the most prevalent and tragic neurodegenerative diseases. Current research indicates that diseases as diverse as multiple sclerosis, stroke and Alzheimer's disease exhibit inflammatory processes that contribute to cellular dysfunction or loss. Inflammation, whether in the brain or periphery, is almost always a secondary response to a primary pathogen. In head trauma, for example, the blow to the head is the primary event. What typically concerns the neurologist and neurosurgeon more, however, is the secondary inflammatory response that will ensue and likely cause more neuron loss than the initial injury. This paper reviews the basic neuroinflammatory mechanisms, the potential neurotoxic mediators during activation of Microglia, the brain resident macrophages, and their role in neurodegeneration. Alzheimer's disease is taken as a prototype for exploring these mechanisms, as it expresses more than 40 inflammatory mediators, it is the most extensively studied disorder in terms of immune-related pathogenesis, and because of its importance as the most prevalent type of dementia. Tools for the visualization of these neuroinflammatory processes, both structural and mainly functional, are critically reviewed and discussed

  48. Vos CM, van Haastert ES, De Groot CJ, van d, V, de Vries HE (2003) Matrix metalloproteinase-12 is expressed in phagocytotic macrophages in active multiple sclerosis lesions. J.Neuroimmunol. 138:106-114
    Abstract: Matrix metalloproteinases (MMPs) are proteases involved in extracellular matrix (ECM) remodeling, leukocyte infiltration into lesions and myelin degradation in the central nervous system (CNS) disease multiple sclerosis (MS). We have investigated whether MMP-12 (macrophage metalloelastase) is expressed in MS lesions at various stages. In control patient tissue and (p)reactive MS lesions, only occasional Microglial and astrocyte staining was detected. In contrast, in active demyelinating lesions, phagocytic macrophages were MMP-12 positive. A lower proportion of phagocytes was positive for MMP-12 in chronic active demyelinating lesions and inactive lesions. This suggests a role for MMP-12 during demyelination in MS

  49. Zehntner SP, Brisebois M, Tran E, Owens T, Fournier S (2003) Constitutive expression of a costimulatory ligand on antigen-presenting cells in the nervous system drives demyelinating disease. FASEB J. 17:1910-1912
    Abstract: It has been proposed that the activation status of antigen-presenting cells (APCs) plays a significant role in the development of autoimmune disease. Whether expression of costimulatory ligands on tissue-resident APCs controls organ-specific autoimmune responses has not been tested. We here report that transgenic mice constitutively expressing the costimulatory ligand B7.2/CD86 on Microglia in the central nervous system (CNS) and on related cells in the proximal peripheral nervous tissue spontaneously develop autoimmune demyelinating disease. Disease-affected nervous tissue in transgenic mice showed infiltration characterized by a predominance of CD8+ memory-effector T cells, as well as CD4+ T cells. Transgenic animals lacking alphabeta TCR+ T cells were completely resistant to disease development. Transgenic T cells induced disease when adoptively transferred into T cell-deficient B7.2 transgenic recipients but not into non-transgenic recipients. These data provide evidence that B7/CD28 interactions within the nervous tissue are critical determinants of disease development. Our findings have important implications for understanding the etiology of nervous system autoimmune diseases such as multiple sclerosis (MS) and Guillain-Barre syndrome (GBS)

  50. Basu A, Krady JK, O'Malley M, Styren SD, DeKosky ST, Levison SW (2002) The type 1 interleukin-1 receptor is essential for the efficient activation of Microglia and the induction of multiple proinflammatory mediators in response to brain injury. J.Neurosci. 22:6071-6082
    Abstract: Interleukin-1 (IL-1) is induced immediately after insults to the brain, and elevated levels of IL-1 have been strongly implicated in the neurodegeneration that accompanies stroke, Alzheimer's disease, and multiple sclerosis. In animal models, antagonizing IL-1 has been shown to reduce cell death; however, the basis for this protection has not been elucidated. Here we analyzed the response to penetrating brain injury in mice lacking the type 1 IL-1 receptor (IL-1R1) to determine which cellular and molecular mediators of tissue damage require IL-1 signaling. At the cellular level, fewer amoeboid Microglia/macrophages appeared adjacent to the injured brain tissue in IL-1R1 null mice, and those Microglia present at early postinjury intervals retained their resting morphology. Astrogliosis also was mildly abrogated. At the molecular level, cyclooxygenase-2 (Cox-2) and IL-6 expression were depressed and delayed. Interestingly, basal levels of Cox-2, IL-1, and IL-6 were significantly lower in the IL-1R1 null mice. In addition, stimulation of vascular cell adhesion molecule-1 mRNA was depressed in the IL-1R1 null mice, and correspondingly, there was reduced diapedesis of peripheral macrophages in the IL-1R1 null brain after injury. This observation correlated with a reduced number of Cox-2+ amoeboid phagocytes adjacent to the injury. In contrast, several molecular aspects of the injury response were normal, including expression of tumor necrosis factor-alpha and the production of nerve growth factor. Because antagonizing IL-1 protects neural cells in experimental models of stroke and multiple sclerosis, our data suggest that cell preservation is achieved by abrogating Microglial/macrophage activation and the subsequent self-propagating cycle of inflammation

  51. Bsibsi M, Ravid R, Gveric D, van Noort JM (2002) Broad expression of Toll-like receptors in the human central nervous system. J.Neuropathol.Exp.Neurol. 61:1013-1021
    Abstract: The family of Toll-like receptors (TLRs) plays a key role in controlling innate immune responses to a wide variety of pathogen-associated molecules. In this study we investigated expression of TLRs in vitro by purified human Microglia, astrocytes, and oligodendrocytes, and in vivo by immunohistochemical examination of brain and spinal cord sections. Cultured primary Microglia were found to express mRNA encoding a wide range of different TLR family members while astrocytes and oligodendrocytes primarily express TLR2 and TLR3. Comparisons between Microglia derived from a series of control subjects and neurodegenerative cases indicate distinct differences in levels of mRNA encoding the different TLRs indifferent Microglia samples. Interestingly, expression of TLR proteins in cultured Microglia as revealed by immunocytochemistry was restricted to intracellular vesicles, whereas in astrocytes they were exclusively localized on the cell surface. Finally, in vivo expression of TLR3 and TLR4 was examined by immunohistochemical analysis of brain and spinal cord sections from both control and multiple sclerosis brains, revealing enhanced expression of either TLR in inflamed CNS tissues. Together, our data reveal broad and regulated expression of TLRs both in vitro and in vivo by human glia cells

  52. Cammer W (2002) Apoptosis of oligodendrocytes in secondary cultures from neonatal rat brains. Neurosci.Lett. 327:123-127
    Abstract: The plaques in multiple sclerosis (MS) autopsy tissue contain tumor necrosis factor-alpha (TNF-alpha) at high concentrations. Moreover, Microglia are able to convert L-tryptophan to quinolinic acid. Thus, TNF-alpha and quinolinic acid are endogenous compounds which may compromise oligodendrocytes during inflammatory demyelination. It is also known that cellular functions depend on adequate concentrations of glutathione (GSH). As some apoptotic oligodendrocytes have been observed in MS plaques, it was therefore logical to determine whether oligodendrocyte apoptosis would occur in response to TNF-alpha, quinolinic acid or GSH depletion. Oligodendrocytes were treated in vitro with TNF-alpha, quinolinic acid and the GSH-depleting agent, buthionine sulfoximine (BSO), respectively, and the numbers of intact and apoptotic cells were counted. TNF-alpha reduced the numbers of mature oligodendrocytes, but not immature oligodendrocytes, without producing apoptosis. Quinolinic acid and BSO each caused oligodendrocyte loss via apoptosis, and GSH ethyl ester partly protected the cells against BSO. The data suggest that oligodendrocytes undergo apoptosis under adverse conditions that result from an endogenous toxicant or depletion of GSH

  53. Carson MJ (2002) Microglia as liaisons between the immune and central nervous systems: functional implications for multiple sclerosis. Glia 40:218-231
    Abstract: multiple sclerosis is a chronic demyelinating inflammatory disease of the central nervous system (CNS). As the tissue macrophage of the CNS, Microglia have the potential to regulate and be regulated by cells of the CNS and by CNS-infiltrating immune cells. The exquisite sensitivity of Microglia to these signals, coupled with their ability to develop a broad range of effector functions, allows the CNS to tailor Microglial function for specific physiological needs. However, the great plasticity of Microglial responses can also predispose these cells to amplify disproportionately the irrelevant or dysfunctional signals provided by either the CNS or immune systems. The consequences of such an event could be the conversion of self-limiting inflammatory responses into chronic neurodegeneration and may explain in part the heterogeneous nature of multiple sclerosis

  54. Chabot S, Yong FP, Le DM, Metz LM, Myles T, Yong VW (2002) Cytokine production in T lymphocyte-Microglia interaction is attenuated by glatiramer acetate: a mechanism for therapeutic efficacy in multiple sclerosis. Mult.Scler. 8:299-306
    Abstract: The efficacy of glatiramer acetate in multiple sclerosis (MS) is thought to involve the production of Th2 regulatory lymphocytes that secrete anti-inflammatory cytokines; however, other mechanisms cannot be excluded Given that activated T lymphocytes infiltrate into the CNS and become in dose proximity to Microglia, we evaluated whether glatiramer acetate affects the potential interaction between T cells and Microglia. We report that the co-culture of activated T lymphocytes with Microglia led to the induction of several cytokines, and that these were reduced by glatiramer acetate treatment Morphological transformation of bipolar/ramified Microglia into an activated ameboid form was attenuated by glatiramer acetate. These results reveal a novel mechanism for glatiramer acetate: the impairment of activated T cells to effectively interact with Microglia to produce cytokines. The net result of a non-inflammatory milieu within the CNS, in spite of T cell infiltration, may help account for the amelioration of disease activity in MS patients on glatiramer acetate therapy

  55. Columba-Cabezas S, Serafini B, Ambrosini E, Sanchez M, Penna G, Adorini L, Aloisi F (2002) Induction of macrophage-derived chemokine/CCL22 expression in experimental autoimmune encephalomyelitis and cultured Microglia: implications for disease regulation. J.Neuroimmunol. 130:10-21
    Abstract: Macrophage-derived chemokine (MDC/CCL22) and its receptor CCR4 have been implicated in chronic inflammatory processes and in the homing of monocytes, Th2 cells and regulatory T-cell subsets. Here, we demonstrate that MDC and CCR4 mRNAs are expressed in the central nervous system (CNS) of mice developing relapsing-remitting and chronic-relapsing forms of experimental autoimmune encephalomyelitis (EAE). By immunohistochemistry, we show that MDC is produced by CNS-infiltrating leukocytes and intraparenchymal Microglia, whereas CCR4 is expressed on some invading leukocytes. Upon in vitro activation, mouse Microglia express MDC transcripts and secrete bioactive MDC that induces chemotaxis of Th2, but not Th1 cells. We suggest that MDC produced by Microglia could regulate Th1-mediated CNS inflammation by facilitating the homing of Th2 and, possibly, regulatory T cells into the lesion site

  56. Cosenza MA, Zhao ML, Shankar SL, Shafit-Zagardo B, Lee SC (2002) Up-regulation of MAP2e-expressing oligodendrocytes in the white matter of patients with HIV-1 encephalitis. Neuropathol.Appl.Neurobiol. 28:480-488
    Abstract: HIV-1 encephalitis (HIVE) is characterized by infection of macrophages and Microglial cells, diffuse gliosis, and damage to neuronal populations. The nature of the white matter damage in HIVE remains elusive, and little is known about the status of the oligodendrocyte in HIVE. We have recently described a novel isoform of microtubule-associated protein-2 (MAP2e), which is expressed transiently in developing oligodendrocytes during myelination, and in remyelinating oligodendrocytes in multiple sclerosis lesions. In this study, we tested the hypothesis that MAP2e expression would be increased in the white matter of HIVE. We analysed brain sections from patients with HIVE and controls (HIV+ and HIV-) by immunocytochemistry and found that MAP2e+ cells are significantly increased in HIVE (range, 5-167 cells per cm2) compared to controls (range, 1-25 cells per cm2). MAP2e+ cells were negative for GFAP, CD68, LN3, RCA-1, von Willebrand factor and HIV-1 p24, but positive for MBP or Luxol-Fast Blue, supporting their oligodendroglial lineage. A topographical association between MAP2e and HIV-1 p24 expression was noted, but not between MAP2e and beta-APP, a marker of damaged axons. Our results demonstrate that MAP2e can serve as a marker of white matter damage in HIVE and support the notion that oligodendrocyte damage/repair occurs during HIV-1 infection

  57. D'Aversa TG, Weidenheim KM, Berman JW (2002) CD40-CD40L interactions induce chemokine expression by human Microglia: implications for human immunodeficiency virus encephalitis and multiple sclerosis. Am.J.Pathol. 160:559-567
    Abstract: CD40 is a protein on Microglia that is up-regulated with interferon (IFN)-gamma and is engaged by CD40L, found on CD4+ T cells, B cells, and monocytes. These interactions may be important in central nervous system inflammatory diseases. Microglia have been shown to be a source of chemokines, whose expression plays a key role in central nervous system pathologies. We examined the expression of CD40 on Microglia in human immunodeficiency virus (HIV) encephalitic brain, and the effects of CD40-CD40L interactions on the expression of chemokines by cultured Microglia. We found significantly increased numbers of CD40-positive Microglia in HIV-infected brain tissue. Treatment of cultured Microglia with IFN-gamma and CD40L increased expression of several chemokines. IFN-gamma- and CD40L-induced MCP-1 protein was mediated by activation of the ERK1/2 MAPK pathway, and Western blot analysis demonstrated phosphorylation of ERK1/2 upon stimulation of Microglia. In contrast, IFN-gamma- and CD40L-induced IP-10 protein production was mediated by the p38 MAPK pathway. Our data suggest a mechanism whereby CD40L+ cells can induce Microglia to secrete chemokines, amplifying inflammatory processes seen in HIV encephalitis and multiple sclerosis, and implicate CD40-CD40L interactions as a target for interventional strategies

  58. Dasgupta S, Jana M, Liu X, Pahan K (2002) Myelin basic protein-primed T cells induce nitric oxide synthase in Microglial cells. Implications for multiple sclerosis. J.Biol.Chem. 277:39327-39333
    Abstract: The presence of autoreactive T cells recognizing self myelin antigens is necessary for the development of central nervous system autoimmune diseases such as multiple sclerosis (MS). The present study was undertaken to investigate the role of myelin basic protein (MBP)-primed T cells in the expression of inducible nitric oxide synthase (iNOS) in Microglial cells. MBP-primed T cells alone markedly induced the production of NO and the expression of iNOS protein and mRNA in mouse BV-2 Microglial cells. Similarly, MBP-primed T cells also induced the production of NO in mouse primary Microglia. This induction of NO production was primarily dependent on the contact between MBP-primed T cells and Microglia. The expression of very late antigen-4 (VLA-4) on the surface of MBP-primed T cells and inhibition of MBP-primed T cell-induced Microglial NO production by functional blocking of antibodies to the alpha(4) chain of VLA-4 (CD49d) suggest that VLA-4 integrin on MBP-primed T cells plays an important role in contact-mediated induction of iNOS. Since IFN-beta has been used to treat MS patients, we examined the effect of IFN-beta on MBP-primed T cell-induced the production of NO. Surprisingly, IFN-beta alone induced the production of NO in Microglial cells. However, the pretreatment of MBP-primed T cells with IFN-beta inhibited the expression of VLA-4 integrin on the surface of MBP-primed T cells and thereby inhibited the ability of those T cells to induce the production of NO in Microglial cells. This study illustrates a novel role of neuroantigen-primed T cells in inducing contact-mediated expression of iNOS in Microglial cells that may participate in the pathogenesis of MS

  59. Debruyne JC, Van Laere KJ, Versijpt J, De Vos F, Eng JK, Strijckmans K, Santens P, Achten E, Slegers G, Korf J, Dierckx RA, De Reuck JL (2002) Semiquantification of the peripheral-type benzodiazepine ligand [11C]PK11195 in normal human brain and application in multiple sclerosis patients. Acta Neurol.Belg. 102:127-135
    Abstract: OBJECTIVES: [11C]PK11195 is a peripheral-benzodiazepine-receptor radioligand used for detection of Microglial inflammation. Normal uptake by means of semiquantification was measured in order to establish reference data. The applicability of this semiquantitative approach was tested in three multiple sclerosis patients. MATERIALS AND METHODS: Seven controls and three patients underwent MR and PET scanning. Coregistered static scans 40 minutes postinjection of [11C]PK11195 were used for assessment of relative ligand uptake by comparison to whole-brain uptake. RESULTS: For static scans acquired in near steady-state, the relative ligand uptake was significantly higher in gray matter structures as compared to the whole brain (ratio: 1.041 +/- 0.06, p = 0.036) whereas it was comparable in white matter (1.010 +/- 0.035). Intersubject reproducibility was 11.4% and 12.9% for white and grey matter. Intrasubject reproducibility was of the same order: 14.0% and 14.5% respectively. In two clinically active patients with Gadolinium-positive T1-weighted lesions on MRI the focal ligand uptake was significantly increased (1.36 and 1.14, p = 0.001). In one clinically stable patient, the uptake value corresponding with a T2-weighted MR lesion was not different from normal brain measurements. CONCLUSION: The current investigations show that normal brain uptake of [11C]PK11195 is very low and shows the feasibility of a semiquantitative method which can be applied to larger cohorts of patients subgroups

  60. Diab A, Deng C, Smith JD, Hussain RZ, Phanavanh B, Lovett-Racke AE, Drew PD, Racke MK (2002) Peroxisome proliferator-activated receptor-gamma agonist 15-deoxy-Delta(12,14)-prostaglandin J(2) ameliorates experimental autoimmune encephalomyelitis. J.Immunol. 168:2508-2515
    Abstract: Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear hormone receptor superfamily that includes receptors for steroids, retinoids, and thyroid hormone, all of which are known to affect the immune response. Previous studies dealing with PPAR-gamma expression in the immune system have been limited. Recently, PPAR-gamma was identified in monocyte/macrophage cells. In this study we examined the role of PPAR-gamma in experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. The hypothesis we are testing is whether PPAR-gamma plays an important role in EAE pathogenesis and whether PPAR-gamma ligands can inhibit the clinical expression of EAE. Initial studies have shown that the presence of the PPAR-gamma ligand 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ2) inhibits the proliferation of Ag-specific T cells from the spleen of myelin basic protein Ac(1-11) TCR-transgenic mice. 15d-PGJ2 suppressed IFN-gamma, IL-10, and IL-4 production by both Con A- and myelin basic protein Ac(1-11) peptide-stimulated lymphocytes as determined by ELISA and ELISPOT assay. Culture of encephalitogenic T cells with 15d-PGJ2 in the presence of Ag reduced the ability of these cells to adoptively transfer EAE. Examination of the target organ, the CNS, during the course of EAE revealed expression of PPAR-gamma in the spinal cord inflammatory infiltrate. Administration of 15d-PGJ2 before and at the onset of clinical signs of EAE significantly reduced the severity of disease. These results suggest that PPAR-gamma ligands may be a novel therapeutic agent for diseases such as multiple sclerosis

  61. Dietrich JB (2002) The adhesion molecule ICAM-1 and its regulation in relation with the blood-brain barrier. J.Neuroimmunol. 128:58-68
    Abstract: The blood-brain barrier (BBB) is formed by high resistance tight junctions within the capillary endothelium perfusing the vertebrate brain. Normal BBB maintains a unique microenvironment within the central nervous system (CNS). In neurodegenerative disorders (for example multiple sclerosis, MS), the BBB becomes impaired. Perivascular cells (astrocytes, macrophages and Microglial cells) and brain microvascular endothelial cells (BMEC) produce various inflammatory factors that affect the BBB permeability and the expression of adhesion molecules. Indeed, cytokines can stimulate the expression of several adhesion molecules on brain microvascular endothelial cells. Among these adhesion molecules, the intercellular adhesion molecule-1 (ICAM-1) binds to its leukocyte ligands and allows activated leukocytes entry into the CNS.This review is dealing with the expression and regulation of ICAM-1 in relation with several properties of the BBB. Particularly, the role of ICAM-1 in the control of the leukocyte traffic into the CNS, as well as in cerebral malaria and in CNS infection by viruses, is discussed

  62. Feinstein DL, Heneka MT, Gavrilyuk V, Dello RC, Weinberg G, Galea E (2002) Noradrenergic regulation of inflammatory gene expression in brain. Neurochem.Int. 41:357-365
    Abstract: It is now well accepted that inflammatory events contribute to the pathogenesis of numerous neurological disorders, including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease, and AID's dementia. Whereas inflammation in the periphery is subject to rapid down regulation by increases in anti-inflammatory molecules and the presence of scavenging soluble cytokine receptors, the presence of an intact blood-brain barrier may limit a similar autoregulation from occurring in brain. Mechanisms intrinsic to the brain may provide additional immunomodulatory functions, and whose dysregulation could contribute to increased inflammation in disease. The findings that noradrenaline (NA) reduces cytokine expression in Microglial, astroglial, and brain endothelial cells in vitro, and that modification of the noradrenergic signaling system occurs in some brain diseases having an inflammatory component, suggests that NA could act as an endogenous immunomodulator in brain. Furthermore, accumulating studies indicate that modification of the noradrenergic signaling system occurs in some neurodiseases. In this article, we will briefly review the evidence that NA can modulate inflammatory gene expression in vitro, summarize data supporting a similar immunomodulatory role in brain, and present recent data implicating a role for NA in attenuating the cortical inflammatory response to beta amyloid protein

  63. Feng X, Yau D, Holbrook C, Reder AT (2002) Type I interferons inhibit interleukin-10 production in activated human monocytes and stimulate IL-10 in T cells: implications for Th1-mediated diseases. J.Interferon Cytokine Res. 22:311-319
    Abstract: Type I interferons (IFNs) directly induce development of Th1 cells. However, IFN-alpha and IFN-beta should generate Th2 cells because these IFNs induce interleukin-10 (IL-10) and block secretion of IFN-gamma. We hypothesized that paradoxical effects of IFNs on Th1-mediated immunity could be from monocyte-specific and T cell-specific IL-10 regulation. We demonstrate that IFN-alpha and IFN-beta inhibit IL-10 mRNA and protein production by activated monocytes but stimulate IL-10 production by activated T cells from the same healthy donors. Without IFN-beta, Staphylococcus aureus, Cowan strain I (SAC)-activated monocytes secreted 15-fold more IL-10 than phorbol myristate acetate (PMA) anti-CD3-activated T cells. With IFN-beta, the two subsets had nearly equivalent secretion. Prostaglandin (PGE) and other cAMP agonists had subset-specific effects on IL-10 production opposite to IFN-beta. The differential IFN-beta effect on transcriptional regulation of IL-10 in monocytes and T cells was from lineage-specific modification of RNA stability. IFN-beta decreased the half-life of IL-10 mRNA in activated monocytes but prolonged the half-life in activated T cells. Subset-specific IL-10 regulation has important implications for Th1-mediated disease. When activated macrophages and Microglia are in excess, as in rheumatoid joints or possibly in chronic multiple sclerosis brain lesions, IFNs may inhibit overall IL-10 production and worsen disease. When T cells outnumber monocytes, IFN-beta will induce IL-10 and ameliorate Th1-mediated disease

  64. Fiebich BL, Lieb K, Engels S, Heinrich M (2002) Inhibition of LPS-induced p42/44 MAP kinase activation and iNOS/NO synthesis by parthenolide in rat primary Microglial cells. J.Neuroimmunol. 132:18-24
    Abstract: Nitric oxide (NO) has been implicated in the etiopathology of central nervous system (CNS) diseases such as multiple sclerosis (MS). Inhibition of NO synthesis has been proposed to be a possible mechanism of action of relevance in the treatment of multiple sclerosis and migraine. Here, we investigated the effect of parthenolide on inducible NO synthase (iNOS) synthesis and NO release using primary rat Microglia. We found parthenolide to be an inhibitor of iNOS/NO synthesis. Investigating the molecular mechanisms by which parthenolide prevents iNOS/NO synthesis, we found that parthenolide inhibits the activation of p42/44 mitogen-activated protein kinase (MAPK), but not IkBalpha (IkappaBalpha) degradation or nuclear factor-kappaB (NF-kappaB) p65 activation. The data suggest that parthenolide might have a potential in the treatment of CNS diseases where NO is part of the pathophysiology

  65. Filipovic R, Rakic S, Zecevic N (2002) Expression of Golli proteins in adult human brain and multiple sclerosis lesions. J.Neuroimmunol. 127:1-12
    Abstract: It has been suggested that Golli proteins, structurally related to myelin basic proteins (MBPs), have a role in autoimmune processes. We studied the expression of these proteins in multiple sclerosis (MS) and determined that the number of Golli-immunoreactive (ir) cells was significantly higher around lesions of chronic MS than in control white matter. Golli proteins were expressed in the adult oligodendrocyte precursor cells (OPCs), activated Microglia/macrophages, and some demyelinated axons around MS lesions. Their expression in adult OPCs indicates remyelination attempts, whereas the expression in the subpopulation of Microglia/macrophages suggests roles in the immune processes of MS. In addition, Golli proteins may be markers of axonal transection, which is characteristic for MS

  66. Gran B, Zhang GX, Yu S, Li J, Chen XH, Ventura ES, Kamoun M, Rostami A (2002) IL-12p35-deficient mice are susceptible to experimental autoimmune encephalomyelitis: evidence for redundancy in the IL-12 system in the induction of central nervous system autoimmune demyelination. J.Immunol. 169:7104-7110
    Abstract: Experimental autoimmune encephalomyelitis (EAE) serves as a model for multiple sclerosis and is considered a CD4(+), Th1 cell-mediated autoimmune disease. IL-12 is a heterodimeric cytokine, composed of a p40 and a p35 subunit, which is thought to play an important role in the development of Th1 cells and can exacerbate EAE. We induced EAE with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 (MOG(35-55)) in C57BL/6 mice and found that while IL-12p40-deficient (-/-) mice are resistant to EAE, IL-12p35(-/-) mice are susceptible. Typical spinal cord mononuclear cell infiltration and demyelination were observed in wild-type and IL-12p35(-/-) mice, whereas IL-12p40(-/-) mice had normal spinal cords. A Th1-type response to MOG(35-55) was observed in the draining lymph node and the spleen of wild-type mice. A weaker MOG(35-55)-specific Th1 response was observed in IL-12p35(-/-) mice, with lower production of IFN-gamma. By contrast, a Th2-type response to MOG(35-55) correlated with disease resistance in IL-12p40(-/-) mice. Production of TNF-alpha by Microglia, CNS-infiltrating macrophages, and CD4(+) T cells was detected in wild-type and IL-12p35(-/-), but not in IL-12p40(-/-), mice. In addition, NO production was higher in IL-12p35(-/-) and wild-type mice than in IL-12p40(-/-) mice. These data demonstrate a redundancy of the IL-12 system in the induction of EAE and suggest that p40-related heterodimers, such as the recently cloned IL-23 (p40p19), may play an important role in disease pathogenesis

  67. Hulshof S, Montagne L, De Groot CJ, van d, V (2002) Cellular localization and expression patterns of interleukin-10, interleukin-4, and their receptors in multiple sclerosis lesions. Glia 38:24-35
    Abstract: Cytokines have been shown to play a crucial role in the pathogenesis of multiple sclerosis (MS). However, still limited data are available on the expression of anti-inflammatory cytokines within the central nervous system (CNS) during MS lesion development. Therefore, we have examined the expression of the anti-inflammatory cytokines, interleukin-10 (IL-10) and IL-4, and their specific receptors, IL-10R and IL-4R, in postmortem human brain tissue obtained from MS patients. Specific patterns of protein localization and expression for both proteins could be observed within active and chronic MS lesions. Strongest IL-10 immunoreactivity was observed in reactive astrocytes within active demyelinating lesions and the hypercellular rim of chronic active MS lesions. Moreover, perivascular macrophages were immunoreactive for IL-10 in (chronic) active MS lesions. Most intense IL-4 immunoreactivity was detected in reactive fibrillary astrocytes within the hypocellular regions of chronic active and chronic inactive MS lesions. Strong immunoreactivity for IL-10R and IL-4R was detected on macrophages in both parenchymal and perivascular areas and on reactive astrocytes in active and chronic MS lesions. Our results indicate that IL-10 and IL-4 have an active role in CNS immune responses. The specific patterns of protein localization and protein expression for both IL-10 and IL-4 in MS lesions at different stages of development suggest that these anti-inflammatory cytokines and their receptors participate in processes leading to the formation of chronic MS lesions

  68. Iribarren P, Cui YH, Le Y, Wang JM (2002) The role of dendritic cells in neurodegenerative diseases. Arch.Immunol.Ther.Exp.(Warsz.) 50:187-196
    Abstract: Dendritic cells (DCs) are the most potent antigen-presenting cells (APCs) involved in the induction of adaptive immune responses. The presence of DCs in the central nervous system (CNS) and the active participation of the immune system in a variety of neurodegenerative diseases have been demonstrated. This review will discuss recent findings pertinent to DCs and other antigen-presenting cells in the CNS in health and disease states

  69. Kim MO, Si Q, Zhou JN, Pestell RG, Brosnan CF, Locker J, Lee SC (2002) Interferon-beta activates multiple signaling cascades in primary human Microglia. J.Neurochem. 81:1361-1371
    Abstract: Microglia, the resident brain macrophages, are the principal cells involved in the regulation of inflammatory and antimicrobial responses in the CNS. Interferon-beta (IFNbeta) is an antiviral cytokine induced by viral infection or following non-specific inflammatory challenges of the CNS. Because of the well-known anti-inflammatory properties of IFNbeta, it is also used to treat multiple sclerosis, an inflammatory CNS disease. Despite the importance of IFNbeta signaling in CNS cells, little has been studied, particularly in Microglia. In this report, we investigated the molecular mechanisms underlying IFNbeta-induced beta-chemokine expression in primary human fetal Microglia. Multiple signaling cascades are activated in Microglia by IFNbeta, including nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and Jak/Stat. IFNbeta induced IkappaBalpha degradation and NF-kappaB (p65:p50) DNA binding. Inhibition of NF-kappaB by either adenoviral transduction of a super repressor IkappaBalpha, or an antioxidant inhibitor of NF-kappaB reduced expression of the beta-chemokines, regulated upon activation, normal T-cell expressed and secreted (RANTES) and macrophage inflammatory protein (MIP)-1beta. IFNbeta also induced phosphorylation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase, and the MAP kinase kinase 1 (MEK1) inhibitor PD98059 dose-dependently inhibited beta-chemokine mRNA and protein expression. PD98059 did not inhibit NF-kappaB binding, demonstrating that ERK was not responsible for NF-kappaB activation. Two downstream targets of ERK were identified in Microglia: AP-1 and Stat1. IFNbeta induced AP-1 nuclear binding activity in Microglia and this was suppressed by PD98059. Additionally, IFNbeta induced Stat1 phosphorylation at both tyrosine 701 (Y701) and serine 727 (S727) residues. S727 phosphorylation of Stat1, which is known to be required for maximal transcriptional activation, was inhibited by PD98059. Our results demonstrating multiple signaling cascades initiated by IFNbeta in primary human Microglia are novel and have implications for inflammatory and infectious diseases of the CNS

  70. Kuhlmann T, Lingfeld G, Bitsch A, Schuchardt J, Bruck W (2002) Acute axonal damage in multiple sclerosis is most extensive in early disease stages and decreases over time. Brain 125:2202-2212
    Abstract: multiple sclerosis is characterized morphologically by the key features demyelination, inflammation, gliosis and axonal damage. In recent years, it has become more evident that axonal damage is the major morphological substrate of permanent clinical disability. In our study, we investigated the occurrence of acute axonal damage determined by immunocytochemistry for amyloid precursor protein (APP) which is produced in neurones and accumulates at sites of recent axon transection or damage. The numbers of APP-positive axons in multiple sclerosis lesions were correlated with the disease duration and course. Most APP-positive axons were detected within the first year after disease onset, but acute axonal damage was also detected to a minor degree in lesions of patients with a disease duration of 10 years and more. This effect was not due to the lack of active demyelinating lesions in the chronic disease stage. Late remyelinated lesions (so-called shadow plaques) did not show signs of axon destruction. The number of inflammatory cells showed a decrease over time similar to that of the number of APP-positive axons. There was a significant correlation between the extent of axon damage and the numbers of CD8-positive cytotoxic T cells and macrophages/Microglia. Our results indicate that a putative axon-protective treatment should start as early as possible and include strategies preventing T cell/macrophage-mediated axon destruction and leading to remyelination of axons

  71. Lehnardt S, Lachance C, Patrizi S, Lefebvre S, Follett PL, Jensen FE, Rosenberg PA, Volpe JJ, Vartanian T (2002) The toll-like receptor TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte injury in the CNS. J.Neurosci. 22:2478-2486
    Abstract: The immediate or innate immune response is the first line of defense against diverse microbial pathogens and requires the expression of recently discovered toll-like receptors (TLRs). TLR4 serves as a specific receptor for lipopolysaccharide (LPS) and is localized on the surface of a subset of mammalian cells. Although innate immunity is a necessary host defense against microbial pathogens, the consequences of its activation in the CNS can be deleterious, as we show here in a developing neural model. We examined the major non-neuronal cell types in the CNS for expression of TLR4 and found that Microglia expressed high levels, whereas astrocytes and oligodendrocytes expressed none. Consistent with TLR4 expression solely in Microglia, we show that Microglia are the only CNS glial cells that bind fluorescently tagged lipopolysaccharide. Lipopolysaccharide led to extensive oligodendrocyte death in culture only under conditions in which Microglia were present. To determine whether TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte death in mixed glial cultures, we studied cultures generated from mice bearing a loss-of-function mutation in the tlr4 gene. Lipopolysaccharide failed to induce oligodendrocyte death in such cultures, in contrast to the death induced in cultures from wild-type mice. Finally, stereotactic intracerebral injection of lipopolysaccharide into the developing pericallosal white matter of immature rodents resulted in loss of oligodendrocytes and hypomyelination and periventricular cysts. Our data provide a general mechanistic link between (1) lipopolysaccharide and similar microbial molecular motifs and (2) injury to oligodendrocytes and myelin as occurs in periventricular leukomalacia and multiple sclerosis

  72. Little AR, Benkovic SA, Miller DB, O'Callaghan JP (2002) Chemically induced neuronal damage and gliosis: enhanced expression of the proinflammatory chemokine, monocyte chemoattractant protein (MCP)-1, without a corresponding increase in proinflammatory cytokines(1). Neuroscience 115:307-320
    Abstract: Enhanced expression of proinflammatory cytokines and chemokines has long been linked to neuronal and glial responses to brain injury. Indeed, inflammation in the brain has been associated with damage that stems from conditions as diverse as infection, multiple sclerosis, trauma, and excitotoxicity. In many of these brain injuries, disruption of the blood-brain barrier (BBB) may allow entry of blood-borne factors that contribute to, or serve as the basis of, brain inflammatory responses. Administration of trimethyltin (TMT) to the rat results in loss of hippocampal neurons and an ensuing gliosis without BBB compromise. We used the TMT damage model to discover the proinflammatory cytokines and chemokines that are expressed in response to neuronal injury. TMT caused pyramidal cell damage within 3 days and a substantial loss of these neurons by 21 days post dosing. Marked Microglial activation and astrogliosis were evident over the same time period. The BBB remained intact despite the presence of multiple indicators of TMT-induced neuropathology. TMT caused large increases in whole hippocampal-derived monocyte chemoattractant protein (MCP)-1 mRNA (1,000%) by day 3 and in MCP-1 (300%) by day 7. The mRNA levels for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, cytokines normally expressed during the earliest stage of inflammation, were not increased up to 21 days post dosing. Lipopolysaccharide, used as a positive control, caused large inductions of cytokine mRNA in liver, as well as an increase in IL-1beta in hippocampus, but it did not result in the induction of astrogliosis. The data suggest that enhanced expression of the proinflammatory cytokines, TNF-alpha, IL-1beta and IL-6, is not required for neuronal and glial responses to injury and that MCP-1 may serve a signaling function in the damaged CNS that is distinct from its role in proinflammatory events

  73. Liu B, Gao HM, Wang JY, Jeohn GH, Cooper CL, Hong JS (2002) Role of nitric oxide in inflammation-mediated neurodegeneration. Ann.N.Y.Acad.Sci. 962:318-331
    Abstract: Increasing evidence has suggested that inflammation in the brain is closely associated with the pathogenesis of several degenerative neurologic disorders, including Parkinson's disease, Alzheimer's diseases, multiple sclerosis, amyotrophic lateral sclerosis, and AIDS dementia. The hallmark of brain inflammation is the activation of glial cells, especially that of Microglia that produce a variety of proinflammatory and neurotoxic factors, including cytokines, fatty acid metabolites, free radicals--such as nitric oxide (NO) and superoxide. Excessive production of NO, as a consequence of nitric oxide synthase induction in activated glia, has been attributed to participate in neurodegeneration. Using primary mixed neuron-glia cultures and glia-enriched cultures prepared from embryonic rodent brain tissues, we have systemically studied the relationship between the production of NO and neurodegeneration in response to stimulation by the inflammagen lipopolysaccharide. This review summarizes our recent findings on the kinetics of NO generation, the relative contribution of Microglia and astrocytes to NO accumulation, the relationship between NO production and neurodegeneration, and points of intervention along the pathways associated with NO generation to achieve neuroprotection. We also describe our results relating to the effect of several opioid-related agents on Microglial activation and neuroprotection. Among these agents, the opioid receptor antagonist naloxone, especially its non-opioid enantiomer (+)-naloxone, promises to be of potential therapeutic value for the treatment of inflammation-related diseases

  74. Lu W, Bhasin M, Tsirka SE (2002) Involvement of tissue plasminogen activator in onset and effector phases of experimental allergic encephalomyelitis. J.Neurosci. 22:10781-10789
    Abstract: Inflammation, demyelination, and neurodegeneration are pathological features of multiple sclerosis (MS). In the brains of MS patients, tissue plasminogen activator (tPA) mRNA and protein are upregulated, and changes in the levels of tPA correlate with progression of the disease. However, the role of tPA in MS is as yet unknown. tPA functions in the CNS in neuronal plasticity and cell death. tPA also mediates the activation of Microglia, the CNS "immune cells." In this study, we establish that tPA activity increases during major oligodendrocyte glycoprotein-induced experimental allergic encephalomyelitis (EAE) in normal mice. To explore the role of tPA in this disease as a model for MS, we have examined the EAE course and expression of histopathological markers in mice lacking tPA (tPA(-/-)). We find that tPA(-/-) mice have a delayed onset of EAE but then exhibit increased severity and delayed recovery from the neurological dysfunction. Demyelination and axon degeneration are delayed, Microglial activation is attenuated, and the production of chemokines is decreased. Our results suggest that tPA and activated Microglia have complex roles in MS/EAE, and that these roles are harmful during the onset of the disease but beneficial in the recovery phase. A temporally restricted attenuation of tPA activity could have therapeutic potential in the management of MS

  75. Lucchinetti CF, Mandler RN, McGavern D, Bruck W, Gleich G, Ransohoff RM, Trebst C, Weinshenker B, Wingerchuk D, Parisi JE, Lassmann H (2002) A role for humoral mechanisms in the pathogenesis of Devic's neuromyelitis optica. Brain 125:1450-1461
    Abstract: Devic's disease [neuromyelitis optica (NMO)] is an idiopathic inflammatory demyelinating disease of the CNS, characterized by attacks of optic neuritis and myelitis. The mechanisms that result in selective localization of inflammatory demyelinating lesions to the optic nerves and spinal cord are unknown. Serological and clinical evidence of B cell autoimmunity has been observed in a high proportion of patients with NMO. The purpose of this study was to investigate the importance of humoral mechanisms, including complement activation, in producing the necrotizing demyelination seen in the spinal cord and optic nerves. Eighty-two lesions were examined from nine autopsy cases of clinically confirmed Devic's disease. Demyelinating activity in the lesions was immunocytochemically classified as early active (21 lesions), late active (18 lesions), inactive (35 lesions) or remyelinating (eight lesions) by examining the antigenic profile of myelin degradation products within macrophages. The pathology of the lesions was analysed using a broad spectrum of immunological and neurobiological markers, and lesions were defined on the basis of myelin protein loss, the geography and extension of plaques, the patterns of oligodendrocyte destruction and the immunopathological evidence of complement activation. The pathology was identical in all nine patients. Extensive demyelination was present across multiple spinal cord levels, associated with cavitation, necrosis and acute axonal pathology (spheroids), in both grey and white matter. There was a pronounced loss of oligodendrocytes within the lesions. The inflammatory infiltrates in active lesions were characterized by extensive macrophage infiltration associated with large numbers of perivascular granulocytes and eosinophils and rare CD3(+) and CD8(+) T cells. There was a pronounced perivascular deposition of immunoglobulins (mainly IgM) and complement C9neo antigen in active lesions associated with prominent vascular fibrosis and hyalinization in both active and inactive lesions. The extent of complement activation, eosinophilic infiltration and vascular fibrosis observed in the Devic NMO cases is more prominent compared with that in prototypic multiple sclerosis, and supports a role for humoral immunity in the pathogenesis of NMO. Based on this study, future therapeutic strategies designed to limit the deleterious effects of complement activation, eosinophil degranulation and neutrophil/macrophage/Microglial activation are worthy of further investigation

  76. Magnus T, Chan A, Savill J, Toyka KV, Gold R (2002) Phagocytotic removal of apoptotic, inflammatory lymphocytes in the central nervous system by Microglia and its functional implications. J.Neuroimmunol. 130:1-9
    Abstract: Apoptotic cell death of inflammatory T cells is an established mechanism to terminate an autoimmune inflammatory response in the rodent and human central nervous system (CNS). The efficient clearance of apoptotic cells protects the tissue from leakage of potentially harmful substances from secondary necrotic cells. As the resident phagocyte, the Microglial cell is the primary candidate for the clearance of apoptotic lymphocytes. Furthermore, the phagocytosis of apoptotic cells is accompanied by a spectrum of anti-inflammatory effects. In this review, we focus on the mechanisms for removal of apoptotic inflammatory cells by Microglia in the central nervous system and their functional consequences

  77. Minagar A, Shapshak P, Fujimura R, Ownby R, Heyes M, Eisdorfer C (2002) The role of macrophage/Microglia and astrocytes in the pathogenesis of three neurologic disorders: HIV-associated dementia, Alzheimer disease, and multiple sclerosis. J.Neurol.Sci. 202:13-23
    Abstract: Macrophage/Microglia (M phi) are the principal immune cells in the central nervous system (CNS) concomitant with inflammatory brain disease and play a significant role in the host defense against invading microorganisms. Astrocytes, as a significant component of the blood-brain barrier, behave as one of the immune effector cells in the CNS as well. However, both cell types may play a dual role, amplifying the effects of inflammation and mediating cellular damage as well as protecting the CNS. Interactions of the immune system, M phi, and astrocytes result in altered production of neurotoxins and neurotrophins by these cells. These effects alter the neuronal structure and function during pathogenesis of HIV-1-associated dementia (HAD), Alzheimer disease (AD), and multiple sclerosis (MS). HAD primarily involves subcortical gray matter, and both HAD and MS affect sub-cortical white matter. AD is a cortical disease. The process of M phi and astrocytes activation leading to neurotoxicity share similarities among the three diseases. Human Immunodeficiency Virus (HIV)-1-infected M phi are involved in the pathogenesis of HAD and produce toxic molecules including cytokines, chemokines, and nitric oxide (NO). In AD, M phis produce these molecules and are activated by beta-amyloid proteins and related oligopeptides. Demyelination in MS involves M phi that become lipid laden, spurred by several possible antigens. In these three diseases, cytokine/chemokine communications between M phi and astrocytes occur and are involved in the balance of protective and destructive actions by these cells. This review describes the role of M phi and astrocytes in the pathogenesis of these three progressive neurological diseases, examining both beneficent and deleterious effects in each disease

  78. Ming X, Li W, Maeda Y, Blumberg B, Raval S, Cook SD, Dowling PC (2002) Caspase-1 expression in multiple sclerosis plaques and cultured glial cells. J.Neurol.Sci. 197:9-18
    Abstract: Caspase-1 is responsible for processing inflammatory cytokines and is associated with the induction of apoptosis. Using RT-PCR, we found that caspase-1 mRNA transcripts from frozen brain extracts were significantly elevated in multiple sclerosis (MS) compared to controls. Immunohistochemical staining using a specific antiserum confirmed the marked up regulation of caspase-1 within acute and chronic MS plaques, while little staining was seen in control brains. In addition to the expected caspase-1 expression in Microglia and infiltrating perivascular mononuclear cells, we found that cytoplasmic caspase-1 expression was sharply increased in the resident oligodendrocytes of MS lesions. The TUNEL reaction for fragmented DNA co-localized over an occasional caspase-1-expressing cell and large numbers of caspase-1-positive "corpses" were observed within phagocytic macrophages of an acute evolving MS lesion. Studies using an immortalized human oligodendroglial hybrid cell line exposed to cytokine challenge showed that death induction was blocked by the caspase-1-like inhibitor Z-YVAD-fmk, while the caspase-3-like inhibitor Z-DEVD-fmk was less effective. Cellular levels of procaspase-1 were reduced compared to controls in oligodendroglia induced to die by cytokine challenge, as judged by Western immunoblotting. Our results suggest that caspase-1 may play a role in the inflammatory and apoptotic processes associated with MS pathogenesis

  79. Nakamura Y (2002) Regulating factors for Microglial activation. Biol.Pharm.Bull. 25:945-953
    Abstract: Microglia, residential macrophages in the central nervous system, can release a variety of factors including cytokines, chemokines, etc. to regulate the communication among neuronal and other types of glial cells. Microglia play immunological roles in mechanisms underlying the phagocytosis of invading microorganisms and removal of dead or damaged cells. When Microglia are hyperactivated due to a certain pathological imbalance, they may cause neuronal degeneration. Pathological activation of Microglia has been reported in a wide range of conditions such as cerebral ischemia, Alzheimer's disease, prion diseases, multiple sclerosis, AIDS dementia, and others. Nearly 5000 papers on Microglia can be retrieved on the Web site PubMed at present (November 2001) and half of them were published within the past 5 years. Although it is not possible to read each paper in detail, as many factors as possible affecting Microglial functions in in vitro culture systems are presented in this review. The factors are separated into "activators" and "inhibitors," although it is difficult to classify many of them. An overview on these factors may help in the development of a new strategy for the treatment of various neurodegenerative diseases

  80. Natarajan C, Bright JJ (2002) Curcumin inhibits experimental allergic encephalomyelitis by blocking IL-12 signaling through Janus kinase-STAT pathway in T lymphocytes. J.Immunol. 168:6506-6513
    Abstract: Experimental allergic encephalomyelitis (EAE) is a CD4(+) Th1 cell-mediated inflammatory demyelinating autoimmune disease of the CNS that serves as an animal model for multiple sclerosis (MS). IL-12 is a proinflammatory cytokine that plays a crucial role in the induction of neural Ag-specific Th1 differentiation and pathogenesis of CNS demyelination in EAE and MS. Curcumin (1,7-Bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) is a naturally occurring polyphenolic phytochemical isolated from the rhizome of the medicinal plant Curcuma longa. It has profound anti-inflammatory activity and been traditionally used to treat inflammatory disorders. In this study we have examined the effect and mechanism of action of curcumin on the pathogenesis of CNS demyelination in EAE. In vivo treatment of SJL/J mice with curcumin significantly reduced the duration and clinical severity of active immunization and adoptive transfer EAE. Curcumin inhibited EAE in association with a decrease in IL-12 production from macrophage/Microglial cells and differentiation of neural Ag-specific Th1 cells. In vitro treatment of activated T cells with curcumin inhibited IL-12-induced tyrosine phosphorylation of Janus kinase 2, tyrosine kinase 2, and STAT3 and STAT4 transcription factors. The inhibition of Janus kinase-STAT pathway by curcumin resulted in a decrease in IL-12-induced T cell proliferation and Th1 differentiation. These findings highlight the fact that curcumin inhibits EAE by blocking IL-12 signaling in T cells and suggest its use in the treatment of MS and other Th1 cell-mediated inflammatory diseases

  81. Natarajan C, Bright JJ (2002) Peroxisome proliferator-activated receptor-gamma agonists inhibit experimental allergic encephalomyelitis by blocking IL-12 production, IL-12 signaling and Th1 differentiation. Genes Immun. 3:59-70
    Abstract: Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a nuclear receptor transcription factor that regulates adipocyte differentiation and glucose homeostasis. PPARgamma agonists are potent therapeutic agents for the treatment of type 2 diabetes and obesity. PPARgamma agonists also prevent inflammation in animal models, suggesting their use for the treatment of human inflammatory diseases. Experimental allergic encephalomyelitis (EAE) is a Th1 cell-mediated inflammatory demyelinating disease model of multiple sclerosis (MS) and IL-12 plays a crucial role in the pathogenesis of EAE and MS. In this study we have examined the effect of PPARgamma agonists on the pathogenesis of EAE. In vivo treatment of SJL/J mice with PPARgamma agonists, 15-deoxydelta(12,14) prostaglandin J2 or Ciglitazone, decreased the duration and clinical severity of active immunization and adoptive transfer models of EAE. PPARgamma agonists inhibited EAE in association with a decrease in IL-12 production and differentiation of neural antigen-specific Th1 cells. In vitro treatment of activated T cells with PPARgamma agonists inhibited IL-12-induced activation of JAK-STAT signaling pathway and Th1 differentiation. These findings highlight the fact that PPARgamma agonists regulate central nervous system inflammation and demyelination by inhibiting IL-12 production, IL-12 signaling and Th1 differentiation in EAE

  82. Nelson PT, Soma LA, Lavi E (2002) Microglia in diseases of the central nervous system. Ann.Med. 34:491-500
    Abstract: Microglia (MG) are enigmatic cells of the central nervous system (CNS). MG are morphologically, antigenically and functionally flexible, and have the potential for mobility and proliferation. MG are professional antigen-presenting cells and constitute part of the local CNS innate immune system, communicating with other immune cells via chemokines, cytokines and growth factors. MG contain several antigenic and functional markers similar to macrophages and dendritic cells (DCs), but also present several differences from DCs. The exact role(s) played by MG in the normal human CNS is the topic of lively debate. MG participate in many reactive processes in the CNS and are therefore an integral part of lesions in a variety of pathologic conditions. It is thought that MG may exacerbate diverse neurological conditions, including viral encephalitis, AIDS, multiple sclerosis (MS) and Alzheimer's disease. A recurrent theme is the perpetuation by MG of pathological cycles of monocyte recruitment, activation and cytopathic secretions, and/or auto antigen presentation

  83. Nguyen VT, Benveniste EN (2002) Critical role of tumor necrosis factor-alpha and NF-kappa B in interferon-gamma -induced CD40 expression in Microglia/macrophages. J.Biol.Chem. 277:13796-13803
    Abstract: CD40 is a member of the tumor necrosis factor (TNF) receptor superfamily. CD40 expression on antigen-presenting cells (including macrophages and Microglia) is crucial for T-cell activation. Aberrant expression of CD40 has been associated with autoimmune inflammatory diseases such as multiple sclerosis and rheumatoid arthritis. We have recently shown that the cytokine interferon (IFN)-gamma is the most potent inducer of CD40 expression in macrophages and Microglia, and this induction is mediated by the IFN-gamma-activated transcription factor STAT-1alpha and constitutively expressed PU.1 and/or Spi-B. In this study, we have discovered that a major component of IFN-gamma-induced CD40 expression involves the endogenous production of the cytokine TNF-alpha. The inclusion of anti-TNF-alpha-neutralizing antibody significantly inhibits IFN-gamma-induced CD40 mRNA and CD40 promoter activity. IFN-gamma-induced CD40 protein expression is attenuated in TNF-alpha-deficient Microglia and can be restored with exogenous TNF-alpha. Site-directed mutagenesis studies demonstrate that three of the four NF-kappaB elements in the CD40 promoter are required for IFN-gamma-induced CD40 promoter activity. IFN-gamma treatment leads to the activation of NF-kappaB in a time-dependent manner, which is inhibited in the presence of anti-TNF-alpha-neutralizing antibody. These results indicate that IFN-gamma-induced TNF-alpha production and subsequent NF-kappaB activation are integral parts of the mechanism of IFN-gamma-induced CD40 expression

  84. O'Keefe GM, Nguyen VT, Benveniste EN (2002) Regulation and function of class II major histocompatibility complex, CD40, and B7 expression in macrophages and Microglia: Implications in neurological diseases. J.Neurovirol. 8:496-512
    Abstract: The ability of Microglia, the brain's resident macrophage, to present antigen through the class II major histocompatibility complex (MHC) to T cells allows these normally quiescent cells to play a critical role in shaping the outcome of many neurological diseases. The expression of class II MHC antigens and the costimulatory molecules CD40 and B7 on Microglia and infiltrating macrophages is regulated through a complex network of cytokines in the inflamed brain. In this review, we describe the molecular mechanisms underlying class II MHC, CD40 and B7 regulation in Microglia and macrophages. Our focus is on the cis-elements in the promoters of their genes and the transcription factors activated by cytokines that bind them. The functional implications of aberrant class II MHC, CD40 and B7 expression by Microglia and macrophages as related to the diseases of multiple sclerosis and Alzheimer's Disease are discussed

  85. Owens T (2002) Identification of new therapeutic targets for prevention of CNS inflammation. Expert.Opin.Ther.Targets. 6:203-215
    Abstract: multiple sclerosis (MS) is a disease of complex pathologies, which involves infiltration by CD4(+) and CD8(+) T cells of and response within the central nervous system. Expression in the CNS of cytokines, reactive nitrogen species and costimulator molecules have all been described in MS. Notably, the cytokines IFN-gamma and TNF are strongly expressed. Microglial cells in the CNS express costimulator molecules and it is assumed that they play a role in directing or inducing the T cell response. Transgenic experiments have tested the effects of overexpression of these molecules in mice and have shown that TNF has multiple effects in the CNS. These range from pro-inflammatory effects of soluble TNF signalling through one of its receptors TNF-RI, to protective/regenerative effects of membrane-associated TNF signalling through the other receptor, TNF-RII. Although IFN-gamma induces nitric oxide production via the enzyme inducible nitric oxide synthase, which is immunosuppressive, IFN-gamma is predominantly pro-inflammatory. In CNS disease in mice that involves CD8(+) T cells, IFN-gamma blockade is protective. Finally, Microglial expression of the costimulator ligand B7.2 induces demyelinating pathology. Animal experiments therefore point to IFN-gamma and costimulatory Microglia as logical targets of therapy for MS. IFN-gamma represents a more accessible target and should therefore be pursued at the earliest opportunity

  86. Peterson JW, Bo L, Mork S, Chang A, Ransohoff RM, Trapp BD (2002) VCAM-1-positive Microglia target oligodendrocytes at the border of multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 61:539-546
    Abstract: The distribution and lineage of vascular cell adhesion molecule-1 (VCAM-1)-positive cells was investigated in 43 lesions from the brain tissue of patients with multiple sclerosis (MS). Numerous VCAM-1-positive macrophages/Microglia were detected at the edges of MS lesions. Quantitative analysis of 6 active, 7 chronic active, and 4 chronic inactive MS lesions identified most VCAM-1-positive cells at the actively demyelinating borders of active (102/mm3) and chronic active (29/mm3) lesions, but rarely in chronic inactive lesions (4/mm3). Further, approximately 17% of the VCAM-1-positive cells closely apposed or surrounded oligodendrocyte perikarya at the edges of active and chronic active lesions that were sites of ongoing demyelination. Endothelial cells were VCAM-1-negative in both lesion and non-lesion MS brain tissue. This report is the first to document direct Microglial interaction with oligodendrocytes in MS

  87. Plumb J, McQuaid S, Mirakhur M, Kirk J (2002) Abnormal endothelial tight junctions in active lesions and normal-appearing white matter in multiple sclerosis. Brain Pathol. 12:154-169
    Abstract: Blood-brain barrier (BBB) breakdown, demonstrable in vivo by enhanced MRI is characteristic of new and expanding inflammatory lesions in relapsing-remitting and chronic progressive multiple sclerosis (MS). Subtle leakage may also occur in primary progressive MS. However, the anatomical route(s) of BBB leakage have not been demonstrated. We investigated the possible involvement of interendothelial tight junctions (TJ) by examining the expression of TJ proteins (occludin and ZO-1 ) in blood vessels in active MS lesions from 8 cases of MS and in normal-appearing white (NAWM) matter from 6 cases. Blood vessels (10-50 per frozen section) were scanned using confocal laser scanning microscopy to acquire datasets for analysis. TJ abnormalities manifested as beading, interruption, absence or diffuse cytoplasmic localization of fluorescence, or separation of junctions (putative opening) were frequent (affecting 40% of vessels) in oil-red-O-positive active plaques but less frequent in NAWM (15%), and in normal (< 2%) and neurological controls (6%). Putatively "open" junctions were seen in vessels in active lesions and in microscopically inflamed vessels in NAWM. Dual fluorescence revealed abnormal TJs in vessels with pre-mortem serum protein leakage. Abnormal or open TJs, associated with inflammation may contribute to BBB leakage in enhancing MRI lesions and may also be involved in subtle leakage in non-enhancing focal and diffuse lesions in NAWM. BBB disruption due to tight junctional pathology should be regarded as a significant form of tissue injury in MS, alongside demyelination and axonopathy

  88. Popovic N, Schubart A, Goetz BD, Zhang SC, Linington C, Duncan ID (2002) Inhibition of autoimmune encephalomyelitis by a tetracycline. Ann.Neurol. 51:215-223
    Abstract: We have explored the use of minocycline, a tetracycline with antiinflammatory properties, to treat chronic relapsing-remitting experimental allergic encephalomyelitis, an animal model of multiple sclerosis. Therapeutic treatment with minocycline dramatically suppresses ongoing disease activity and limits disease progression. Disease suppression is associated with immune deviation in the periphery and with suppression of the inflammatory cascade in the central nervous system. This association is demonstrated by inhibition of Microglial activation and metalloproteinase-2 expression, which results in a concomitant decrease in inflammation and demyelination. As an established antiinflammatory drug with neuroprotective properties, minocycline may provide a novel therapeutic agent for relapsing-remitting multiple sclerosis

  89. Pul R, Nguyen D, Schmitz U, Marx P, Stangel M (2002) Comparison of intravenous immunoglobulin preparations on Microglial function in vitro: more potent immunomodulatory capacity of an IgM/IgA-enriched preparation. Clin.Neuropharmacol. 25:254-259
    Abstract: Intravenous immunoglobulins (IVIg) have been used successfully as an immunomodulating treatment for patients with inflammatory diseases of the central nervous system (CNS) including multiple sclerosis (MS). It was shown previously that IVIg could modulate the functions of Microglia, the main immune cell in the CNS. We have compared five commercially available IVIg preparations on their capacity to modulate tumor necrosis factor (TNF)-alpha secretion and nitric oxide production in cultured Microglia. All preparations induced a dose-dependent stimulation of TNF-alpha secretion as measured by ELISA. There were some small differences between preparations consisting of IgG, while the preparation enriched for IgM and IgA induced a considerably higher TNF-alpha production at 1 mg/mL and 10 mg/mL. Similar results were seen for nitric oxide production as measured indirectly by the Griess reaction. These results indicate that IgM/IgA-enriched IVIg may be a more potent immunomodulator than pure IgG preparations on inflammatory reactions in the CNS

  90. Reiman R, Gerard C, Campbell IL, Barnum SR (2002) Disruption of the C5a receptor gene fails to protect against experimental allergic encephalomyelitis. Eur.J.Immunol. 32:1157-1163
    Abstract: Activation of the complement system generates the anaphylatoxic peptide C5a, which elicits a broad range of inflammatory activities. The biological activities of C5a are mediated through its binding to the widely expressed C5a receptor (C5aR), a G-protein-coupled seven transmembrane domain receptor. In experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, the C5aR is expressed on monocytes/macrophages, reactive astrocytes and T cells infiltrating the central nervous system (CNS). To investigate the role of the C5aR in this T cell-driven autoimmune model, we induced EAE in C5aR-deficient mice (C5aR(-/-)) and wild-type mice using a myelin oligodendrocyte glycoprotein (MOG) peptide as the immunogen. We found that C5aR(-/-) mice were fully susceptible to MOG-induced EAE with no difference in disease onset or severity in C5aR(-/-) mice compared to control mice. Cellular infiltrates (macrophages and T cells) were similar in the spinal cords of both animal groups and splenic T cells from C5aR(-/-) mice and control mice responded identically to MOG in T cell proliferation assays. Ribonuclease protection assays demonstrated no significant differences in pro-inflammatory gene expression between receptor-deficient and sufficient mice. These results indicate that the C5aR is not an essential mediator in the induction and progression of EAE

  91. Reynolds R, Dawson M, Papadopoulos D, Polito A, Di Bello IC, Pham-Dinh D, Levine J (2002) The response of NG2-expressing oligodendrocyte progenitors to demyelination in MOG-EAE and MS. J.Neurocytol. 31:523-536
    Abstract: Remyelination of primary demyelinated lesions is a common feature of experimental models of multiple sclerosis (MS) and is also suggested to be the normal response to demyelination during the early stages of MS itself. Many lines of evidence have shown that remyelination is preceded by the division of endogenous oligodendrocyte precursor cells (OPCs) in the lesion and its borders. It is suggested that this rapid response of OPCs to repopulate the lesion site and their subsequent differentiation into new oligodendrocytes is the key to the rapid remyelination. Antibodies to the NG2 chondroitin sulphate proteoglycan have proved exceedingly useful in following and quantitating the response of endogenous OPCs to demyelination. Here we review the literature on the response of NG2-expressing OPCs to demyelination and provide some new evidence on their response to the chronic inflammatory demyelinating environment seen in recombinant myelin oligodendrocyte glycoprotein (MOG) induced experimental allergic encephalomyelitis (EAE) in the DA rat. NG2-expressing OPCs responded to the inflammatory demyelination in this model by becoming reactive and increasing in number in a very focal manner. Evidence of NG2+ OPCs in lesioned areas beginning to express the oligodendrocyte marker CNP was also seen. The response of OPCs appeared to occur following successive relapses but did not always lead to remyelination, with areas of chronic demyelination observed in the spinal cord. The presence of OPCs in the adult human CNS is clearly of vital importance for repair in multiple sclerosis (MS). As in rat tissue, the antibody labels an evenly distributed cell population present in both white and grey matter, distinct from HLA-DR+ Microglia. NG2+ cells are sparsely distributed in the centre of chronic MS lesions. These cells apparently survive demyelination and exhibit a multi-processed or bipolar morphology in the very hypocellular environment of the lesion

  92. Schaecher K, Rocchini A, Dinkins J, Matzelle DD, Banik NL (2002) Calpain expression and infiltration of activated T cells in experimental allergic encephalomyelitis over time: increased calpain activity begins with onset of disease. J.Neuroimmunol. 129:1-9
    Abstract: Calpain activity and expression at the protein level were examined in inflammatory cells, activated Microglia, and astrocytes prior to or at onset of symptomatic experimental allergic encephalomyelitis (EAE), an animal model for the human demyelinating disease multiple sclerosis (MS). EAE was induced in Lewis rats by injection of guinea pig spinal cord homogenate and myelin basic protein (MBP) emulsified with Complete Freund's Adjuvant (CFA). Calpain translational expression, determined by Western blot and immunocytochemistry, was correlated with calpain activity, infiltration of inflammatory cells, and myelin loss at 2-11 days following challenge with antigen. Controls (CFA only) did not show any changes over time in these parameters and very few changes (CD11+ Microglia/mononuclear phagocytes) were seen in either group from days 2 to 8 post-induction. In contrast, from days 9 to 11, the animals that developed the disease (at least grade 1) demonstrated extensive cellular infiltration (CD4+, CD25+, and CD11+ as well as increased calpain expression (content) and activity. This study demonstrates that cell infiltration and increased calpain activity do not begin in the CNS until the onset of clinical signs

  93. Schmid CD, Sautkulis LN, Danielson PE, Cooper J, Hasel KW, Hilbush BS, Sutcliffe JG, Carson MJ (2002) Heterogeneous expression of the triggering receptor expressed on myeloid cells-2 on adult murine Microglia. J.Neurochem. 83:1309-1320
    Abstract: Microglial activation is an early and common feature of almost all neuropathologies, including multiple sclerosis, Alzheimer's disease and mechanical injury. To better understand the relative contributions Microglia make toward neurodegeneration and neuroprotection, we used TOGA(R) to identify molecules expressed by Microglia and regulated by inflammatory signals. Triggering receptor expressed on myeloid cells-2 (TREM-2) was among the mRNAs identified as being expressed by unactivated Microglia, but down-regulated by lipopolysaccharide/interferon gamma. In the healthy CNS, not all Microglia expressed TREM-2. Microglial expression of TREM-2 varied not only between brain regions but also within each brain region. Brain regions with an incomplete blood-brain barrier had the lowest percentages of TREM-2- expressing Microglia, whereas the lateral entorhinal and cingulate cortex had the highest percentages. A novel form of TREM-2b that lacked a transmembrane domain was detected, perhaps indicating a soluble form of the protein. Taken together, these data suggest that (1) subsets of Microglia are specialized to respond to defined extracellular signals; and (2) regional variations in TREM-2 expression may contribute to the varying sensitivities of different brain regions to similar pathological signals

  94. Schwab C, McGeer PL (2002) Complement activated C4d immunoreactive oligodendrocytes delineate small cortical plaques in multiple sclerosis. Exp.Neurol. 174:81-88
    Abstract: C4d-immunoreactive complement-activated oligodendrocytes (C4d-CAOs) have been described in several neurodegenerative diseases but have not been studied in multiple sclerosis (MS). Here we report that such CAOs delineate miniature MS plaques of 300-500 mum diameter. They are devoid of myelin and are surrounded by a rim of activated Microglia intermingled with the C4d-CAOs. Although C4d-immunostained periaxonal oligodendroglial processes are often swollen, the axons of passage appear undamaged and extend through the demyelinated plaque area. No immunostaining with other components of the complement cascade (C1q-C9) was observed in association with these miniature plaques. However, in large MS lesions, C1q-C9 immunoreactive fibers were present, indicating complete activation of the complement cascade in these more developed lesions. It is possible that the miniature plaques, bordered by C4d-CAOs, represent the earliest stage of plaque development, preceding even the larger, transient plaques frequently observed in serial MRI studies. The association of CAOs with miniature areas of demyelination suggests a direct attack on oligodendroglial cells by the early complement components as an initiating event in MS. Incomplete complement activation indicates that this step may be reversible, whereas full and persistent activation as observed in large MS lesions may lead to death of oligodendroglia with permanent axonal damage

  95. Siao CJ, Tsirka SE (2002) Extracellular proteases and neuronal cell death. Cell Mol.Biol.(Noisy.-le-grand) 48:151-161
    Abstract: Neuronal cell death occurs during development of the central nervous system as well as in pathological situations such as acute injury and progressive degenerative diseases. For instance, granule cells in the developing cerebellum and neuronal precursor cells in the cortex undergo programmed cell death, or apoptosis. There is currently strong debate conceming the mechanism of death in many degenerative events such as ischemia, blunt head trauma, excitotoxicity and neurodegenerative diseases, i.e. Alzheimer's disease. Neurons can die a necrotic death when the initial insult is too great; apoptosis requires "planning." For example, the cell death seen in the core of an ischemic infarct is necrotic, while in the surrounding penumbra region the death is probably apoptotic. Regardless of the degenerative pathway, damaged or dead neurons are a hallmark of many diseases including Alzheimer's, Parkinson's, glaucoma, ischemia and multiple sclerosis. Molecules such as cytokines, chemokines, reactive nitrogen/oxygen species, and proteases play an important role in promoting and/or mediating neurodegeneration. Proteases have been implicated in both physiological and pathological events, suggesting their intervention in key points when things go awry. In this review we will summarize recent findings linking extracellular proteases with neuronal cell death in both human diseases and their animal models

  96. Spencer RF, Sismanis A, Kilpatrick JK, Shaia WT (2002) Demyelination of vestibular nerve axons in unilateral Meniere's disease. Ear Nose Throat J. 81:785-789
    Abstract: We conducted a study to determine whether vestibular nerves in patients with unilateral Meniere's disease whose symptoms are refractory to medical management exhibit neuropathologic changes. We also endeavored to determine whether retrocochlear abnormalities are primary or secondary factors in the disease process. To these ends, we obtained vestibular nerve segments from five patients during retrosigmoid (posterior fossa) neurectomy, immediately fixed them, and processed them for light and electron microscopy. We found that all five segments exhibited moderate to severe demyelination with axonal sparing. Moreover, we noted that reactive astrocytes produced an extensive proliferation of fibrous processes and that the Microglia assumed a phagocytic role. We conclude that the possible etiologies of demyelination include viral and/or immune-mediated factors similar to those seen in other demyelinating diseases, such as multiple sclerosis and Guillain-Barre syndrome. Our findings suggest that some forms of Meniere's disease that are refractory to traditional medical management might be the result of retrocochlear pathology that affects the neuroglial portion of the vestibular nerve

  97. Stadelmann C, Kerschensteiner M, Misgeld T, Bruck W, Hohlfeld R, Lassmann H (2002) BDNF and gp145trkB in multiple sclerosis brain lesions: neuroprotective interactions between immune and neuronal cells? Brain 125:75-85
    Abstract: Recent immunohistological and imaging studies emphasize the crucial role of axonal injury in determining the extent of permanent neurological deficits in patients with multiple sclerosis. We have recently shown that human immune cells are capable of producing the neurotrophin brain-derived neurotrophic factor (BDNF), which can prevent axonal and neuronal damage after various pathological insults. BDNF imported into the CNS by immune cells would thus be an attractive candidate for mediating neuroprotective effects in multiple sclerosis. The aim of the present study was to perform a detailed immunohistochemical analysis of the expression of BDNF and its receptor truncated trkB tyrosine kinase receptor (gp145trkB) in a series of multiple sclerosis brain lesions. Our data show that various types of neurones throughout the brain are BDNF immunopositive in multiple sclerosis patients as well as in controls. Furthermore, in multiple sclerosis lesions, BDNF is primarily present in immune cells (T cells, macrophages/Microglia) and reactive astrocytes. The number of BDNF immunopositive cells correlates with lesional demyelinating activity. The BDNF receptor gp145trkB is found in neurones in the immediate vicinity of multiple sclerosis plaques as well as in reactive astrocytes within the lesion, but not in immune cells. Our results demonstrate that both BDNF and gp145trkB are expressed in multiple sclerosis lesions. This suggests that BDNF and gp145trkB are involved in immune-mediated neuroprotective interactions in multiple sclerosis, and supports the concept that immune cells produce both damaging and protective factors in multiple sclerosis lesions

  98. Stangel M, Hartung HP (2002) [Intravenous immunoglobulins in multiple sclerosis. Studies and mechanisms of action--an update]. Nervenarzt 73:119-124
    Abstract: There is no doubt about the immunomodulatory capacity of intravenous immunoglobulins (IVIg). This also holds true for multiple sclerosis (MS), where clinical trials have shown a reduction in relapse rate and number of active lesions on MRI after IVIg treatment. Experimental data in the model of murine Theiler's virus encephalomyelitis (TMEV) gave rise to the hypothesis that IVIg may also promote remyelination. Unfortunately, recent trials were unable to demonstrate clinically relevant remyelination in MS patients treated with IVIg. A possible explanation could lie in the fact that IVIg do not influence the function of oligodendrogilial cells in vitro. In contrast, IVIg can protect oligodendrocytes against complement-mediated injury and thus provide more cells that could engage in remyelination. In addition, IVIg can modulate Microglial functions in vitro, thus creating a microenvironment permissive for remyelination. Should such mechanisms also be operative in vivo, they would have escaped detection in the treatment protocols used to date. It would appear that IVIg need to be administered while the inflammatory process is still ongoing, whereas the published trials included only patients with a stable deficit when there is probably little or no active inflammation. Despite new studies on IVIg, its role in the management of MS remains elusive

  99. Storch MK, Weissert R, Steffer A, Birnbacher R, Wallstrom E, Dahlman I, Ostensson CG, Linington C, Olsson T, Lassmann H (2002) MHC gene related effects on Microglia and macrophages in experimental autoimmune encephalomyelitis determine the extent of axonal injury. Brain Pathol. 12:287-299
    Abstract: Myelin-oligodendrocyte-glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in rats is a chronic inflammatory demyelinating disease of the central nervous system (CNS) strongly mimicking multiple sclerosis (MS). We determined the involvement of macrophages and Microglia in the lesions of MOG-EAE in relation to different major histocompatibility complex (MHC, RT1 in rat) haplotypes. We used intra-RT1 recombinant rat strains with recombinations between the RT1a and RT1u haplotypes on the disease permissive LEW non-MHC genome. Activated Microglia and macrophages were identified morphologically and by expression of ED1 and allograft inhibitory factor-1 (AIF-1), and differentiated by their morphological phenotype. White matter lesions contained more macrophages and less Microglia compared to grey matter lesions. Similarly active lesions were mainly infiltrated by macrophages, while Microglia were abundant in inactive demyelinated plaques. In addition, we found a highly significant genetic association between a macrophage or Microglia dominated lesional phenotype, which was independent from location and activity of the lesions. This was not only the case in demyelinating plaques of chronic EAE, but also in purely inflammatory lesions of acute passive transfer EAE. Rat strains with an u-haplotype in both the Class II and the telomeric non-classical Class I region revealed inflammatory and demyelinating lesions, which were dominated by activated Microglia. The a-haplotype in any of these regions was associated with macrophage dominated lesions. A comparison of lesions, exactly matched for stages of demyelinating activity in these different rat strains, showed that in spite of a similar extent of demyelination, axonal injury was significantly less in Microglia compared to macrophage dominated lesions. Thus, our studies document a genetic influence of the MHC-region on the relative contribution of macrophages versus Microglia in the pathogenesis of EAE

  100. Ure DR, Rodriguez M (2002) Polyreactive antibodies to glatiramer acetate promote myelin repair in murine model of demyelinating disease. FASEB J. 16:1260-1262
    Abstract: Using a murine model of demyelinating disease, we demonstrate that remyelination of spinal cord axons is promoted by antibodies to glatiramer acetate (GA, Copolymer-1, Copaxone), a therapeutic agent for multiple sclerosis (MS). Glatiramer acetate is a mixture of randomly synthesized peptides that induces both T cell activation and antibody production in all treated individuals. These observations prompted us to compare the independent effects of adoptively transferred GA-reactive T cells and antibodies in mice with chronic inflammatory demyelination induced by Theiler's virus. Transferred T cells had no effect on lesion load or the extent of remyelination. Purified polyclonal GA antibodies also did not alter lesion load, which suggests that neither GA T cells or antibodies were pathogenic. On the contrary, GA antibodies enhanced the normally low level of remyelination in chronic lesions. The antibodies, which were primarily immunoglobulin (Ig) G1 and IgG2, cross-reacted with oligodendrocytes, perivascular infiltrating cells, astrocytes, and neurons in spinal cord sections. In glial cultures they bound subsets of early lineage oligodendrocytes and Microglia. Thus, several mechanisms may have contributed to the promotion of remyelination. These results support the hypothesis that the antibody response in GA-treated patients is beneficial by facilitating repair of demyelinated lesions

  101. Valdo P, Stegagno C, Mazzucco S, Zuliani E, Zanusso G, Moretto G, Raine CS, Bonetti B (2002) Enhanced expression of NGF receptors in multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 61:91-98
    Abstract: The receptor for nerve growth factor (NGF) comprises a 75-kDa (NGFRp75) and a tyrosine kinase A (TrkA) subunit. In view of conflicting opinions on the identity of glial targets of NGF in human central nervous system (CNS), we examined the cellular distribution of both NGF receptor subunits in normal CNS and in chronic multiple sclerosis (MS) lesions. For this, we compared the pattern of recognition of 2 monoclonal antibodies (mAbs) and a polyclonal antiserum to NGFRp75. Only the 2 mAbs specifically recognized NGFRp75, while the polyclonal antiserum showed widespread reactivity. In normal CNS and silent MS lesions, immunohistochemistry with anti-NGFRp75 mAbs and for TrkA revealed perivascular cell reactivity. At the edge of chronic active MS lesions, selective NGFRp75 staining was prominent on reactive astrocytes, while throughout the lesion, NGFRp75 was expressed on Microglia/macrophages. The vast majority of mature or precursor oligodendrocytes did not express NGFRp75. Both NGF receptors were co-expressed on a subset of inflammatory cells. Immunoreactivity for NGFRp75 on glial and immune cells did not correlate with the distribution of apoptotic figures, as detected by TUNEL. Thus, expression of NGF receptors in active MS lesions suggests a role for NGF in regulating the autoimmune response at both immune and glial cell levels

  102. Visser L, de Vos AF, Hamann J, Melief MJ, van Meurs M, van Lier RA, Laman JD, Hintzen RQ (2002) Expression of the EGF-TM7 receptor CD97 and its ligand CD55 (DAF) in multiple sclerosis. J.Neuroimmunol. 132:156-163
    Abstract: CD97 is a recently identified seven-span transmembrane (7-TM) protein that is expressed by leukocytes early after activation. CD97 binds to its cellular ligand CD55 (decay accelerating factor), which protects several cell types from complement-mediated damage. The functional consequences of CD97-CD55 binding are largely unknown, but previous data imply that CD97-CD55 interactions play a role in cellular activation, migration, and adhesion under inflammatory conditions.Here we examined the expression of CD97 and CD55 by immunohistochemistry in multiple sclerosis (MS). On the basis of established criteria for inflammation and demyelination, different lesion stages were distinguished in MS post-mortem brain tissue. In normal white matter, CD97 expression was not found, but CD55 was expressed with weak staining intensity on endothelial cells. In pre-active lesions, defined by abnormalities of the white matter, many infiltrating T cells, macrophages (MPhi) and Microglia expressed CD97. CD55 was highly expressed by endothelial cells. In active lesions with myelin degradation, MPhi and Microglia expressed both CD55 and CD97. Furthermore, a sandwich ELISA showed significantly (p<0.05) elevated levels of soluble CD97 in serum but not in cerebrospinal fluid of MS patients (37%) compared to healthy controls (8%).Collectively, these data suggest that CD97-CD55 interactions are involved in the inflammatory processes in MS. CD55, which is expressed in lesions by vessels to protect against complement-mediated damage, might bind to CD97 on infiltrating leukocytes. This interaction may facilitate cell activation and migration through the blood-brain barrier. In addition, CD97-CD55 interactions in the parenchyma of the brain may contribute to the inflammation

  103. Werner K, Bitsch A, Bunkowski S, Hemmerlein B, Bruck W (2002) The relative number of macrophages/Microglia expressing macrophage colony-stimulating factor and its receptor decreases in multiple sclerosis lesions. Glia 40:121-129
    Abstract: The activation of macrophages/Microglia in multiple sclerosis (MS) lesions plays a central role in the effector phase of myelin breakdown. The precise patterns of macrophage/Microglia activation during demyelination have not yet been defined. The growth and activating factor macrophage-colony stimulating factor (M-CSF) and its specific receptor (M-CSFR) may be involved in this process. The present study investigated the expression of M-CSF and M-CSFR mRNA by in situ hybridization in 60 lesions from 32 MS patients. In the control and periplaque white matter, Microglia was almost completely M-CSFR positive. Irrespective of the demyelinating activity, an increased number of cells expressed M-CSF or M-CSFR mRNA within the lesions. However, despite the tremendous increase in macrophages/Microglia within the lesions, the relative number of these cells expressing M-CSF or M-CSFR decreased. There was no correlation of M-CSF or M-CSFR expression with active myelin breakdown. The correlation between the clinical course and the expression of M-CSF or M-CSFR mRNA revealed significant differences with the lowest expression in primary progressive MS. These results suggest a downregulation of M-CSF and M-CSFR inside the MS plaque probably due to the high amount of macrophage-derived cytokines or mediators. Nevertheless, the differences in the relative number of cells expressing the M-CSF/M-CSFR pathway implicate that this pathway may be an important contributory factor in different forms of MS pathology

  104. Wesemann DR, Dong Y, O'Keefe GM, Nguyen VT, Benveniste EN (2002) Suppressor of cytokine signaling 1 inhibits cytokine induction of CD40 expression in macrophages. J.Immunol. 169:2354-2360
    Abstract: CD40 is a type I membrane-bound molecule belonging to the TNFR superfamily that is expressed on various immune cells including macrophages and Microglia. The aberrant expression of CD40 is involved in the initiation and maintenance of various human diseases including multiple sclerosis, arthritis, atherosclerosis, and Alzheimer's disease. Inhibition of CD40 signaling has been shown to provide a significant beneficial effect in a number of animal models of human diseases including the aforementioned examples. We have previously shown that IFN-gamma induces CD40 expression in macrophages and Microglia. IFN-gamma leads to STAT-1alpha activation directly and up-regulation of NF-kappaB activity due to the secretion and subsequent autocrine signaling of TNF-alpha. However, TNF-alpha alone is not capable of inducing CD40 expression in these cells. Suppressor of cytokine signaling 1 protein (SOCS-1) is a cytokine-inducible Src homology 2-containing protein that regulates cytokine receptor signaling by inhibiting STAT-1alpha activation via a specific interaction with activated Janus kinase 2. Given the important role of CD40 in inflammatory events in the CNS as well as other organ systems, it is imperative to understand the molecular mechanisms contributing to both CD40 induction and repression. We show that ectopic expression of SOCS-1 abrogates IFN-gamma-induced CD40 protein expression, mRNA levels, and promoter activity. Additionally, IFN-gamma-induced TNF-alpha secretion, as well as STAT-1alpha and NF-kappaB activation, are inhibited in the presence of SOCS-1. We conclude that SOCS-1 inhibits cytokine-induced CD40 expression by blocking IFN-gamma-mediated STAT-1alpha activation, which also then results in suppression of IFN-gamma-induced TNF-alpha secretion and subsequent NF-kappaB activation

  105. Yoshikawa M, Suzumura A, Ito A, Tamaru T, Takayanagi T (2002) Effect of phosphodiesterase inhibitors on nitric oxide production by glial cells. Tohoku J.Exp.Med. 196:167-177
    Abstract: Nitric oxide (NO) is considered to play a crucial role in the development of various pathological processes in the CNS, such as neuronal degeneration, inflammation and demyelination. In order to search for the agents which suppress NO production in the CNS, we examined the effects of one of the agents which elevate cyclic AMP production, phosphodiesterase inhibitors (PDEIs), on NO production by glial cells in vitro. All the types of PDEIs, from type I- to V-specific and non-specific, suppressed the production of NO by mouse Microglia and astrocytes stimulated with lipopolysaccharide, in a dose-dependent manner. Suppression of inducible NO synthase by PDEIs was confirmed by the expression of mRNA by RT-PCR. Although it required 10 microM or higher concentration to effectively suppress NO production in vitro, certain combinations of three different PDEIs synergistically suppressed NO production by astrocytes at 1 microM which could be obtained in vivo at usual therapeutic doses. Similary, combinations of three PDEIs at 1 microM synergistically increased intracellular cAMP in astrocytes. The suppressive effects of PDEIs on NO production were abolished by addition of tumor necrosis factor alpha (TNFalpha). Thus, the main suppression mechanism of NO might be indirect through suppression of TNFalpha. Since some PDEIs are reported to pass through the blood-brain-barrier, the combination of three PDEIs may be worth trying in neurological diseases, such as multiple sclerosis, human immunodeficiency virus-related neurological diseases and other neurodegenerative disorders in which NO may play a crucial role

  106. Youssef S, Stuve O, Patarroyo JC, Ruiz PJ, Radosevich JL, Hur EM, Bravo M, Mitchell DJ, Sobel RA, Steinman L, Zamvil SS (2002) The HMG-CoA reductase inhibitor, atorvastatin, promotes a Th2 bias and reverses paralysis in central nervous system autoimmune disease. Nature 420:78-84
    Abstract: Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which are approved for cholesterol reduction, may also be beneficial in the treatment of inflammatory diseases. Atorvastatin (Lipitor) was tested in chronic and relapsing experimental autoimmune encephalomyelitis, a CD4(+) Th1-mediated central nervous system (CNS) demyelinating disease model of multiple sclerosis. Here we show that oral atorvastatin prevented or reversed chronic and relapsing paralysis. Atorvastatin induced STAT6 phosphorylation and secretion of Th2 cytokines (interleukin (IL)-4, IL-5 and IL-10) and transforming growth factor (TGF)-beta. Conversely, STAT4 phosphorylation was inhibited and secretion of Th1 cytokines (IL-2, IL-12, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha) was suppressed. Atorvastatin promoted differentiation of Th0 cells into Th2 cells. In adoptive transfer, these Th2 cells protected recipient mice from EAE induction. Atorvastatin reduced CNS infiltration and major histocompatibility complex (MHC) class II expression. Treatment of Microglia inhibited IFN-gamma-inducible transcription at multiple MHC class II transactivator (CIITA) promoters and suppressed class II upregulation. Atorvastatin suppressed IFN-gamma-inducible expression of CD40, CD80 and CD86 co-stimulatory molecules. l-Mevalonate, the product of HMG-CoA reductase, reversed atorvastatin's effects on antigen-presenting cells (APC) and T cells. Atorvastatin treatment of either APC or T cells suppressed antigen-specific T-cell activation. Thus, atorvastatin has pleiotropic immunomodulatory effects involving both APC and T-cell compartments. Statins may be beneficial for multiple sclerosis and other Th1-mediated autoimmune diseases

  107. Zaheer A, Mathur SN, Lim R (2002) Overexpression of glia maturation factor in astrocytes leads to immune activation of Microglia through secretion of granulocyte-macrophage-colony stimulating factor. Biochem.Biophys.Res.Commun. 294:238-244
    Abstract: We infected a mixed culture of primary rat astrocytes and Microglia with a replication-defective adenovirus carrying the rat glia maturation factor (GMF) cDNA. Affymetrix microarray analysis showed a big increase in the expression of several major histocompatibility complex (MHC) class II proteins along with interleukin-1beta (IL-1beta). Subsequent study using reverse transcription-polymerase chain reaction (RT-PCR) yielded the same results with the mixed culture, but not with pure astrocytes or pure Microglia. We also noticed that the GMF/virus construct infected only astrocytes but not Microglia. This led us to suspect that overexpression of GMF in astrocytes resulted in the secretion of an active substance that stimulated the Microglia to express MHC II and IL-1beta. We identified this substance as granulocyte-macrophage-colony stimulating factor (GM-CSF). MHC II are unique to antigen-presenting cells such as Microglia and monocytes. The results suggest that GMF in astrocytes can initiate a series of events, leading to immune activation in the nervous system, and implicates its involvement in autoimmune diseases such as multiple sclerosis

  108. Zekki H, Feinstein DL, Rivest S (2002) The clinical course of experimental autoimmune encephalomyelitis is associated with a profound and sustained transcriptional activation of the genes encoding toll-like receptor 2 and CD14 in the mouse CNS. Brain Pathol. 12:308-319
    Abstract: Experimental autoimmune encephalomyelitis (EAE) is an autoimmune demyelinating disease commonly used to model the pathogenetic mechanisms involved in multiple sclerosis (MS). In this study, we examined the effects of immunization with the myelin oligodendrocyte glycoprotein MOG(35-55) on the expression of molecules of the innate immune system, namely toll-like receptor 2 (TLR2) and CD14. Expression of the mRNA encoding TLR2 increased in the choroid plexus, the leptomeninges and within few isolated cells in the CNS parenchyma 4 to 8 days after immunization with MOG. At day 10, the signal spread across the meninges, few perivascular regions and over isolated groups of parenchymal cells. Three weeks after the MOG treatment, at which time animals showed severe clinical symptoms, a robust expression of both TLR2 and CD14 transcripts occurred in barrier-associated structures, as well as parenchymal elements of the spinal cord, and within numerous regions of the brain including, the medulla, cerebellum and the cortex. Dual labeling provided the anatomical evidence that Microglia/macrophages were positive for TLR2 in the brain of EAE mice. The regions that exhibited chronic expression of TLR2 and CD14 were also associated with an increase in NF-kappaB activity and transcriptional activation of genes encoding numerous proinflammatory molecules. The present data provide evidence that receptors of the pathogen-associated molecular patterns are strongly induced in the CNS of EAE mice, further reinforcing the concept that the innate immune system plays a determinant role in this autoimmune demyelinating disease

  109. Zhang B, Yang L, Konishi Y, Maeda N, Sakanaka M, Tanaka J (2002) Suppressive effects of phosphodiesterase type IV inhibitors on rat cultured Microglial cells: comparison with other types of cAMP-elevating agents. Neuropharmacology 42:262-269
    Abstract: We investigated the effects of inhibitors of cAMP-specific phosphodiesterase type IV (PDE IV) on cultured rat Microglial cells. Microglial cells expressed mRNA encoding PDE IV. Rolipram and RO-20-1724, specific inhibitors of PDE IV, elevated the intracellular cAMP level much higher than the other types of PDE inhibitors. cAMP in astrocytes but not in cerebrocortical neurons was similarly increased in response to treatment with PDE IV inhibitors examined. The PDE IV inhibitors, a beta-adrenergic agonist isoproterenol and an adenylyl cyclase stimulant forskolin suppressed the proliferation of Microglial cells as revealed by PCNA-immunocytochemical staining. The PDE IV inhibitors suppressed release of TNF alpha and nitric oxide (NO) from lipopolysaccharide-activated Microglial cells in pure culture, while they did not affect NO release from Microglial cells in neuron-Microglia coculture. The PDE IV inhibitors also suppressed superoxide anion production by phorbol ester-treated Microglial cells. Isoproterenol and forskolin similarly suppressed the macrophage-like functions of activated Microglial cells. However, the PDE IV inhibitors displayed novel effects distinct from those of isoproterenol, forskolin and 8Br-cAMP, regarding expression of mRNAs encoding PDE IV, metallothionein-1 and hemeoxigenase-1. The present data showed that the PDE IV inhibitors can be available to control Microglial function and that their effects on glial cells should be taken into account when PDE IV inhibitors are used for treatment of brain diseases, such as multiple sclerosis

  110. Allen IV, McQuaid S, Mirakhur M, Nevin G (2001) Pathological abnormalities in the normal-appearing white matter in multiple sclerosis. Neurol.Sci. 22:141-144
    Abstract: In established cases of multiple sclerosis (MS), the normal-appearing white matter (NAWM), as defined for magnetic resonance imaging (MRI), is abnormal in the majority of cases. The clinical significance of these NAWM abnormalities is the subject of debate, but there is strong correlation with degree and progression of disability. New lesions form in NAWM before blood-brain barrier breakdown, as evidenced by gadolinium enhancement. The pathological basis of these neuroimaging abnormalities is largely unknown. Definitive pathological studies on the NAWM are few and are often based on small numbers of samples and of cases. Despite a variety of MS NAWM pathological studies, major research questions, of importance to our understanding of basic pathogenetic mechanisms and consequent rational therapies, remain unanswered. These relate to the frequency and extent of oligodendrocyte/myelin and axonal abnormalities in MS NAWM, and to the cellular basis of very early MS lesions detected by neuroimaging. In a pilot study of MS NAWM, Microglial activation was demonstrated in 9 of 10 MS cases. We are currently testing the hypothesis that Microglial activation, as defined by altered phenotype and HLA-DR positivity, will act as a marker for oligodendrocyte/myelin and axonal pathology in MS NAWM

  111. Bajetto A, Bonavia R, Barbero S, Florio T, Schettini G (2001) Chemokines and their receptors in the central nervous system. Front Neuroendocrinol. 22:147-184
    Abstract: Chemokines are a family of proteins associated with the trafficking of leukocytes in physiological immune surveillance and inflammatory cell recruitment in host defence. They are classified into four classes based on the positions of key cystiene residues: C, CC, CXC, and CX3C. Chemokines act through both specific and shared receptors that all belong to the superfamily of G-protein-coupled receptors. Besides their well-established role in the immune system, several recent reports have demonstrated that these proteins also play a role in the central nervous system (CNS). In the CNS, chemokines are constitutively expressed by Microglial cells, astrocytes, and neurons, and their expression can be increased after induction with inflammatory mediators. Constitutive expression of chemokines and chemokine receptors has been observed in both developing and adult brains, and the role played by these proteins in the normal brain is the object of intense study by many research groups. Chemokines are involved in brain development and in the maintenance of normal brain homeostasis; these proteins play a role in the migration, differentiation, and proliferation of glial and neuronal cells. The chemokine stromal cell-derived factor 1 and its receptor, CXCR4, are essential for life during development, and this ligand-receptor pair has been shown to have a fundamental role in neuron migration during cerebellar formation. Chemokine and chemokine receptor expression can be increased by inflammatory mediators, and this has in turn been associated with several acute and chronic inflammatory conditions. In the CNS, chemokines play an essential role in neuroinflammation as mediators of leukocyte infiltration. Their overexpression has been implicated in different neurological disorders, such as multiple sclerosis, trauma, stroke, Alzheimer's disease, tumor progression, and acquired immunodeficiency syndrome-associated dementia. An emerging area of interest for chemokine action is represented by the communication between the neuroendocrine and the immune system. Chemokines have hormone-like actions, specifically regulating the key host physiopathological responses of fever and appetite. It is now evident that chemokines and their receptors represent a plurifunctional family of proteins whose actions on the CNS are not restricted to neuroinflammation. These molecules constitute crucial regulators of cellular communication in physiological and developmental processes

  112. Chabot S, Charlet D, Wilson TL, Yong VW (2001) Cytokine production consequent to T cell--Microglia interaction: the PMA/IFN gamma-treated U937 cells display similarities to human Microglia. J.Neurosci.Methods 105:111-120
    Abstract: Cognate interactions between human adult Microglia and activated T lymphocytes induce the production of inflammatory cytokines. Since this interaction can occur in a non-antigen-dependent manner, it is relevant to a variety of CNS diseases where activated T cells, regardless of specificities, come into contact with Microglia; these disorders include multiple sclerosis, trauma, stroke and Alzheimer's disease. A model cell line would facilitate studies of the engagement between T cells and human adult Microglia, since the latter are difficult to obtain in substantial quantity or frequency. This study shows that the PMA/IFN gamma-treated U937 cell line shows similarities to Microglia in its interaction with activated T lymphocytes, in that the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, IL-10 and IL-12 is induced. Morphological features and mechanisms of cytokine production resemble those observed in Microglia--T cell co-cultures since CTLA-4 and CD40--CD40L blockades reduce TNF-alpha and IL-10 levels, while anti-CD23 inhibits IL-10 only in U937--T cell interactions. We propose that PMA/IFN gamma-treated U937 cells can serve as a model of human adult Microglia to study cytokine generation in response to interactions with activated T cells

  113. Chan A, Magnus T, Gold R (2001) Phagocytosis of apoptotic inflammatory cells by Microglia and modulation by different cytokines: mechanism for removal of apoptotic cells in the inflamed nervous system. Glia 33:87-95
    Abstract: Apoptosis of autoaggressive T cells in the central nervous system (CNS) is an effective, nonphlogistic mechanism for the termination of autoimmune inflammation in experimental autoimmune encephalomyelitis (EAE). The clearance of apoptotic leukocytes by tissue-specific phagocytes is a critical event in the resolution of the inflammatory attack. To investigate the role of Microglia in the removal of apoptotic cells and potential regulatory mechanisms of Microglial phagocytosis, an in vitro phagocytosis assay was established, using Lewis rat Microglia. Microglia exhibited a high capacity for the uptake of apoptotic autologous thymocytes, as well as apoptotic encephalitogenic myelin basic protein (MBP)-specific T cells, in contrast to nonapoptotic target cells. Pretreatment of Microglia with interferon-gamma (IFN-gamma) raised the proportion of Microglia capable of phagocytosing apoptotic cells to 75% above the untreated controls. The increased phagocytic activity was selective for apoptotic target cells and was not dependent on phosphatidylserine-mediated recognition mechanisms. In contrast, preincubation of Microglia with interleukin-4 (IL-4) inhibited the uptake of apoptotic cells, whereas tumor-necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) did not alter phagocytosis. Phagocytic clearance of apoptotic inflammatory cells by Microglia may be an important mechanism for the termination of autoimmune inflammation in the CNS. Augmentation of Microglial phagocytosis by the Th-1-type cytokine IFN-gamma suggests a feedback mechanism for the accelerated clearance of the inflammatory infiltrate in the CNS

  114. Copelman CA, Diemel LT, Gveric D, Gregson NA, Cuzner ML (2001) Myelin phagocytosis and remyelination of macrophage-enriched central nervous system aggregate cultures. J.Neurosci.Res. 66:1173-1178
    Abstract: An increased level of myelin basic protein (MBP) degradation peptide 80-89, representative of myelin breakdown, is detected in myelinating foetal rat brain aggregate cultures supplemented with peritoneal macrophages at a time coinciding with the onset of myelination. During the period of myelination, the proportion of activated macrophages/Microglia in the aggregates decreases, accompanied by a reduction in the content of MBP degradation products. During the recovery period following a demyelinating episode, the rate of MBP synthesis in antibody-treated standard aggregates was greater than in their medium controls. However, the rate of MBP accumulation was not as efficient in macrophage-enriched aggregates and was associated with persistently raised MBP peptide levels. Thus, as occurs in multiple sclerosis lesions, attempts at remyelination appear to be counterbalanced by macrophage-mediated demyelination, with the continued presence of degraded myelin rendering a local environment that is not fully conducive to remyelination

  115. de Goer de Herve MG, Delfraissy JF, Taoufik Y (2001) Following direct CD40 activation, human primary Microglial cells produce IL-12 p40 but not bioactive IL-12 p70. Cytokine 14:88-96
    Abstract: There is accumulating evidence that interleukin 12 (IL-12) is involved in the pathogenesis of multiple sclerosis. In the periphery, this cytokine is produced by antigen-presenting cells (APCs) following interaction with activated T cells. CD40 ligation plays a crucial role in this production. Microglial cells are thought to play a major role in antigen presentation in the central nervous system. In this work, we examined IL-12 production by human primary Microglial cells after CD40 ligation. These cells expressed CD40 and MHC class II following interferon-gamma activation. IL-12 p40 mRNA and protein, but not bioactive IL-12 p70, were detected in response to direct CD40 activation. Microglial cells co-cultured with activated allogenic CD4+ T lymphocytes also produced IL-12 p40 but not IL-12 p70. This IL-12 p40 production was inhibited by anti-CD40 ligand. Altogether, these results suggest that CD40-CD40-ligand interaction provides a signal that triggers IL-12 p40 expression. However, other interaction(s) may be required during antigen presentation for bioactive heterodimeric IL-12 p70 to be produced by Microglial cells

  116. De Groot CJ, Bergers E, Kamphorst W, Ravid R, Polman CH, Barkhof F, van d, V (2001) Post-mortem MRI-guided sampling of multiple sclerosis brain lesions: increased yield of active demyelinating and (p)reactive lesions. Brain 124:1635-1645
    Abstract: Macroscopic sampling of multiple sclerosis lesions in the brain tends to find chronic lesions. For a better understanding of the dynamics of the multiple sclerosis disease process, research into new and developing lesions is of great interest. As MRI in vivo effectively demonstrates lesions in multiple sclerosis patients, we have applied it to unfixed post-mortem brain slices to identify abnormalities, in order to obtain a higher yield of active lesions. The Netherlands Brain Bank organized the rapid autopsy of 29 multiple sclerosis patients. The brain was cut in 1 cm coronal slices. One or two slices were subjected to T(1)- and T(2)-weighted MRI, and then cut at the plane of the MRI scan into 5 mm thick opposing sections. Areas of interest were identified based on the MRI findings and excised. One half was fixed in 10% formalin and paraffin-embedded, and the corresponding area in the adjacent half was snap-frozen in liquid nitrogen. In total, 136 out of 174 brain tissue samples could be matched with the abnormalities seen on T(2)-weighted MRIs. The stage of lesional development was determined (immuno) histochemically. For 54 MRI-detectable samples, it was recorded whether they were macroscopically detectable, i.e. visible and/or palpable. Histopathological analysis revealed that 48% of the hyperintense areas seen on T(2)-weighted images represented active lesions, including lesions localized in the normal appearing white matter, without apparent loss of myelin but nevertheless showing a variable degree of oedema, small clusters of Microglial cells with enhanced major histocompatibility complex class II antigen, CD45 and CD68 antigen expression and a variable number of perivascular lymphocytes around small blood vessels [designated as (p)reactive lesions]. From the macroscopically not-visible/not-palpable MRI-detected abnormalities, 58% were (p)reactive lesions and 21% contained active demyelinating lesions. In contrast, visible and/or palpable brain tissue samples mainly contained chronic inactive lesions. We conclude that MRI-guided sampling of brain tissue increases the yield of active multiple sclerosis lesions, including active demyelinating and (p)reactive lesions

  117. De Groot CJ, Woodroofe MN (2001) The role of chemokines and chemokine receptors in CNS inflammation. Prog.Brain Res. 132:533-544

  118. Dorries R (2001) The role of T-cell-mediated mechanisms in virus infections of the nervous system. Curr.Top.Microbiol.Immunol. 253:219-245
    Abstract: T lymphocytes play a decisive role in the course and clinical outcome of viral CNS infection. Summarizing the information presented in this review, the following sequence of events might occur during acute virus infection: After invasion of the host and a few initial rounds of replication, the virus reaches the CNS in most cases by hematogeneous spread. After passage through the BBB, CNS cells are infected and replication of virus in brain cells causes activation of the surrounding Microglia population. Moreover, local production of IFN-alpha/beta induces expression of MHC antigens on CNS cells, and Microglial cells start to phagocytose cellular debris, which accumulates as a result of virus-induced cytopathogenic effects. Upon phagocytosis, Microglia becomes more activated; they up-regulate MHC molecules, acquire antigen presentation capabilities and secrete chemokines. This will initiate up-regulation of adhesion molecules on adjacent endothelial cells of the BBB. Transmigration of activated T lymphocytes through the BBB is followed by interaction with APC, presenting the appropriate peptides in the context of MHC antigens. It appears that CD8+ T lymphocytes are amongst the first mononuclear cells to arrive at the infected tissue. Without a doubt, their induction and attraction is deeply influenced by natural killer cells, which, after virus infection, secrete IFN-gamma, a cytokine that stimulates CD8+ T cells and diverts the immune response to a TH1-type CD4+ T cell-dominated response. Following the CD8+ T lymphocytes, tissue-penetrating, TH1 CD4+ T cells contact local APC. This results in a tremendous up-regulation of MHC molecules and secretion of more chemotactic and toxic substances. Consequently an increasing number of inflammatory cells, including macrophages/Microglia and finally antibody-secreting plasma cells, are attracted to the site of virus infection. All trapped cells are mainly terminally differentiated cells that are going to enter apoptosis during or shortly after exerting their effector functions. The clinical consequences and the influence of the effector phase on the further course of the infection depends on the balance and fine-tuning of the contributing lymphoid cell populations. Generally, any delay in the recruitment of effector lymphocytes to the tissue or an unbalanced combination of lymphocyte subsets allows the virus to spread in the CNS, which in turn will cause severe immune-mediated tissue effects as well as disease. If either too late or partially deficient, the immune system response may contribute to a lethal outcome or cause autosensitization to brain-specific antigens by epitope spreading to the antigen-presenting system in peripheral lymphoid tissue. This could form the basis for subsequent booster reactions of autosensitized CD4+ T cells--a process that finally will end in an inflammatory autoimmune reaction, which in humans we call multiple sclerosis. In contrast, a rapid and specific local response in the brain tissue will result in efficient limitation of viral spread and thereby a subclinical immune system-mediated termination of the infection. After clearance of virus-infected cells, downsizing of the local response probably occurs via self-elimination of the contributing T cell populations and/or by so far unidentified signal pathways. However, much of this is highly speculative, and more data have to be collected to make decisive conclusions regarding this matter. Several strategies have been developed by viruses to escape T cell-mediated eradication, including interference with the MHC class I presentation pathway of the host cell or "hiding" in cells which lack MHC class I expression. This may result in life-long persistence of the virus in the brain, a state which probably is actively controlled by T lymphocytes. Under severe immunosuppression, however, reactivation of viral replication can occur, which is a lethal threat to the host

  119. Drew PD, Chavis JA (2001) The cyclopentone prostaglandin 15-deoxy-Delta(12,14) prostaglandin J2 represses nitric oxide, TNF-alpha, and IL-12 production by Microglial cells. J.Neuroimmunol. 115:28-35
    Abstract: Prostaglandins are generally considered pro-inflammatory molecules that contribute to the pathology associated with a variety of immune-mediated diseases including multiple sclerosis. However, recently it has been demonstrated that specific cyclopentone prostaglandin metabolites including 15-deoxy-Delta(12,14) prostaglandin J2 (15d-PGJ2) are capable of repressing the production of pro-inflammatory molecules by cells of the monocyte/macrophage lineage. Activated Microglia produce nitric oxide (NO) and TNF-alpha, molecules which can be toxic to cells including oligodendrocytes, thus potentially contributing to the pathology associated with multiple sclerosis. The current study demonstrates that 15d-PGJ2 inhibits lipopolysachharide (LPS) induction of NO and TNF-alpha production by rat primary Microglia and mouse N9 Microglial cells. 15d-PGJ2 also inhibits NO production by Microglial cells activated in response to IFN-gamma and TNF-alpha, cytokines believed to be important modulators of multiple sclerosis. IL-12 plays a critical role in stimulating the production of Th1 cells, which are believed to contribute to the pathology associated with multiple sclerosis. The current studies demonstrate that 15d-PGJ2 represses the production of IL-12 by Microglial cells. Collectively, these studies demonstrate that the prostaglandin metabolite 15d-PGJ2 represses Microglial production of potentially cytotoxic molecules, as well as molecules capable of altering T-cell phenotype. These in vitro studies suggest the possibility that the prostaglandin 15d-PGJ2 may modulate inflammatory diseases including multiple sclerosis

  120. Espejo C, Carrasco J, Hidalgo J, Penkowa M, Garcia A, Saez-Torres I, Martinez-Caceres EM (2001) Differential expression of metallothioneins in the CNS of mice with experimental autoimmune encephalomyelitis. Neuroscience 105:1055-1065
    Abstract: multiple sclerosis is an inflammatory, demyelinating disease of the CNS. Metallothioneins-I+II are antioxidant proteins induced in the CNS by immobilisation stress, trauma or degenerative diseases which have been postulated to play a neuroprotective role, while the CNS isoform metallothionein-III has been related to Alzheimer's disease. We have analysed metallothioneins-I-III expression in the CNS of mice with experimental autoimmune encephalomyelitis. Moreover, we have examined the putative role of interferon-gamma, a pro-inflammatory cytokine, in the control of metallothioneins expression during experimental autoimmune encephalomyelitis in interferon-gamma receptor knockout mice with two different genetic backgrounds: 129/Sv and C57BL/6x129/Sv.Mice with experimental autoimmune encephalomyelitis showed a significant induction of metallothioneins-I+II in the spinal cord white matter, and to a lower extent in the brain. Interferon-gamma receptor knockout mice suffered from a more severe experimental autoimmune encephalomyelitis, and interestingly showed a higher metallothioneins-I+II induction in both white and grey matter of the spinal cord and in the brain. In contrast to the metallothioneins-I+II isoforms, metallothionein-III expression remained essentially unaltered during experimental autoimmune encephalomyelitis; interferon-gamma receptor knockout mice showed an altered metallothionein-III expression (a slight increase in the spinal cord white matter) only in the C57BL/6x129/Sv background. Metallothioneins-I+II proteins were prominent in areas of induced cellular infiltrates. Reactive astrocytes and activated monocytes/macrophages were the sources of metallothioneins-I+II proteins.From these results we suggest that metallothioneins-I+II but not metallothionein-III may play an important role during experimental autoimmune encephalomyelitis, and indicate that the pro-inflammatory cytokine interferon-gamma is unlikely an important factor in this response

  121. Flugel A, Bradl M, Kreutzberg GW, Graeber MB (2001) Transformation of donor-derived bone marrow precursors into host Microglia during autoimmune CNS inflammation and during the retrograde response to axotomy. J.Neurosci.Res. 66:74-82
    Abstract: Macrophages in the brain can have a triple source. They may originate from recently blood-derived precursors, from the largely resident perivascular cell population (perivascular macrophages and related cells), and from intrinsic parenchymal as well as perivascular Microglia. Although continuous exchange of part of the perivascular cell population with bone marrow-derived precursors is now accepted, the turnover of adult parenchymal Microglia has remained enigmatic. Using bone-marrow chimeras carrying an unexpressed marker gene and carbon labeling of peripheral monocyte/macrophages in a combined model of facial nerve axotomy and transfer experimental autoimmune encephalitis, we demonstrate for the first time that there is an easy to induce exchange between parenchymal central nervous system (CNS) Microglia and the macrophage precursor cell pool of the bone marrow. Furthermore, very low level infiltration of the CNS parenchyma by recently bone marrow-derived Microglia could be observed after simple peripheral nerve axotomy that is followed by neuronal regeneration. Thus, Microglial cells can be considered wanderers between the peripheral immune system and the CNS where they may act as a "Trojan horse" in infections. The fact that recently bone marrow-derived parenchymal Microglia fully integrate into a regenerating brain nucleus' architecture encourages entirely new approaches for delivering genes into the adult CNS

  122. Furlan R, Poliani PL, Marconi PC, Bergami A, Ruffini F, Adorini L, Glorioso JC, Comi G, Martino G (2001) Central nervous system gene therapy with interleukin-4 inhibits progression of ongoing relapsing-remitting autoimmune encephalomyelitis in Biozzi AB/H mice. Gene Ther. 8:13-19
    Abstract: multiple sclerosis (MS) is an immune-mediated inflammatory disease of the central nervous system (CNS) that might benefit from anti-inflammatory therapies. However, systemic delivery of anti-inflammatory drugs in MS patients has so far been disappointing, mostly due to the limited capacity of these molecules to enter the CNS. We injected into the cisterna magna (i.c.) of Biozzi AB/H mice affected by a relapsing-remitting form of experimental autoimmune encephalomyelitis (EAE), the animal model of MS, a non-replicative herpes simplex virus (HSV) type-1-derived vector containing the interleukin (IL)-4 gene (d120:LacZ:IL-4). CNS delivery of the d120:LacZ:IL-4 vector, after EAE onset, induced the in situ production of IL-4 by CNS-resident cells facing the cerebrospinal fluid (CSF) spaces and reduced by 47% (P < 0.02) the disease-related deaths. Compared with mice treated with the control d120:lacZ vector, IL-4-treated mice also showed a shorter duration of the first EAE attack, a longer inter-relapse period, and a reduction in the severity and duration of the first relapse. Protection from EAE progression in IL-4-treated mice was associated with activation of Microglia in spinal cord areas where mRNA content of the pro-inflammatory chemokines, macrophage chemoattractant protein-1 (MCP-1) and Rantes, was reduced and that of the anti-inflammatory cytokine IL-4 was increased. Finally, CNS-infiltrating mononuclear cells from IL-4-treated mice produced lower levels of MCP-1 mRNA compared with control mice. Our results, showing that IL-4 gene delivery using HSV-1 vectors induces protection from EAE by in situ modulating the cytokine/chemokine-mediated circuits sustaining effector cell functions, indicate that the intrathecal 'therapeutic' use of nonreplicative HSV-1-derived vectors containing anti-inflammatory molecules might represent an alternative strategy in inflammatory diseases of the CNS

  123. Gebicke-Haerter PJ, Spleiss O, Ren LQ, Li H, Dichmann S, Norgauer J, Boddeke HW (2001) Microglial chemokines and chemokine receptors. Prog.Brain Res. 132:525-532

  124. Gebicke-Haerter PJ (2001) Microglia in neurodegeneration: molecular aspects. Microsc.Res.Tech. 54:47-58
    Abstract: Inflammatory events in the CNS are associated with injuries as well as with well-known chronic degenerative diseases, such as multiple sclerosis, Parkinson's, or Alzheimer's disease. Compared to inflammation in peripheral tissues, inflammation in brain appears to follow distinct pathways and time-courses, which likely has to do with a relatively strong immunosuppression in that organ. For this reason, it is of great importance to get insights into the molecular mechanism governing immune reactions in brain tissue. This task is hard to achieve in vivo, but can be approached by studying the major cell type responsible for brain inflammation, the Microglia, in culture. Since these cells are the only professional antigen-presenting cells resident in brain parenchyma, molecular mechanisms of antigen presentation are being discussed first. After covering the expression and regulation of anti- and proinflammatory cytokines, induction and regulation of two key enzymes and their products-COX-2 and iNOS-are summarized. Possibly, pivotal molecular targets for drug therapies of brain disorders will be discovered in intracellular signaling pathways leading to activation of transcription factors. Finally, the impact of growth factors, of neurotrophins in particular, is highlighted. It is concluded that the presently available data on the molecular level is far from being statisfying, but that only from better insights into molecular events will we obtain the information required for more specific therapies

  125. Giralt M, Carrasco J, Penkowa M, Morcillo MA, Santamaria J, Campbell IL, Hidalgo J (2001) Astrocyte-targeted expression of interleukin-3 and interferon-alpha causes region-specific changes in metallothionein expression in the brain. Exp.Neurol. 168:334-346
    Abstract: Transgenic mice expressing IL-3 and IFN-alpha under the regulatory control of the GFAP gene promoter (GFAP-IL3 and GFAP-IFNalpha mice) exhibit a cytokine-specific, late-onset chronic-progressive neurological disorder which resemble many of the features of human diseases such as multiple sclerosis, Aicardi-Goutieres syndrome, and some viral encephalopathies including HIV leukoencephalopathy. In this report we show that the metallothionein-I+II (MT-I+II) isoforms were upregulated in the brain of both GFAP-IL3 and GFAP-IFNalpha mice in accordance with the site and amount of expression of the cytokines. In the GFAP-IL3 mice, in situ hybridization analysis for MT-I RNA and radioimmunoassay results for MT-I+II protein revealed that a significant upregulation was observed in the cerebellum and medulla plus pons at the two ages studied, 1-3 and 6-10 months. Increased MT-I RNA levels occurred in the Purkinje and granular layers of the cerebellum, as well as in its white matter tracts. In contrast to the cerebellum and brain stem, MT-I+II were downregulated by IL-3 in the hippocampus and the remaining brain in the older mice. In situ hybridization for MT-III RNA revealed a modest increase in the cerebellum, which was confirmed by immunohistochemistry. MT-III immunoreactivity was present in cells that were mainly round or amoeboid monocytes/macrophages and in astrocytes. MT-I+II induction was more generalized in the GFAP-IFNalpha (GIFN12 and GIFN39 lines) mice, with significant increases in the cerebellum, thalamus, hippocampus, and cortex. In the high expressor line GIFN39, MT-III RNA levels were significantly increased in the cerebellum (Purkinje, granular, and molecular layers), thalamus, and hippocampus (CA2/CA3 and especially lacunosum molecular layers). Reactive astrocytes, activated rod-like Microglia, and macrophages, but not the perivenular infiltrating cells, were identified as the cellular sources of the MT-I+II and MT-III proteins. The pattern of expression of the different MT isoforms in these transgenic mice differed substantially, demonstrating unique effects associated with the expression of each cytokine. The results indicate that the MT expression in the CNS is significantly affected by the cytokine-induced inflammatory response and support a major role of these proteins during CNS injury

  126. Gobin SJ, Montagne L, Van Zutphen M, van d, V, van den Elsen PJ, De Groot CJ (2001) Upregulation of transcription factors controlling MHC expression in multiple sclerosis lesions. Glia 36:68-77
    Abstract: The expression of major histocompatibility complex (MHC) class I and class II in the CNS has received considerable interest because of its importance in neurodegenerative or inflammatory diseases, such as multiple sclerosis (MS). However, at the moment nothing is known about the expression patterns of transcription factors controlling MHC expression in MS lesions. Here, we performed an extensive immunohistochemical analysis on MS affected postmortem brain tissue to determine the cellular localization and distribution of different MHC-controlling transcription factors. We show that phagocytic macrophages in active demyelinating MS lesions displayed a moderate to strong immunostaining of the MHC-specific transcription factors RFX and CIITA, as well as the general transcription factors NF-kappaB, IRF1, STAT1, USF, and CREB, which was congruent with a strongly enhanced expression of HLA-DR, HLA-DQ, HLA-DP, and HLA class I. In the normal-appearing white matter (NAWM), clusters of activated Microglial cells forming preactive lesions displayed an overall stronger expression level of these transcription factors, combined with a strong to intense level of MHC class I and class II immunostaining. In general, astrocytes and oligodendrocytes either did not express, or weakly expressed, these transcription factors, correlating with a lack of MHC class II and weak MHC class I expression. Together, the elevated expression level of transcription factors governing expression of MHC class I and class II molecules in activated Microglial cells and phagocytic macrophages strongly suggests a general state of Microglial cell activation in MS lesions

  127. Imrich H, Harzer K (2001) On the role of peripheral macrophages during active experimental allergic encephalomyelitis (EAE). J.Neural Transm. 108:379-395
    Abstract: Experimental allergic encephalitis (EAE) is an experimental autoimmune inflammatory condition of the central nervous system (CNS) that serves as a disease model for multiple sclerosis (MS). The primary effector mechanisms of the immune system leading to tissue destruction during EAE remain still controversial. T-cells, Microglia, and macrophages infiltrating the brain parenchyma are suggested to be involved. To clarify the role of these cells during disease Lewis rats were immunised with different immunisation protocols: Immunisation with myelin basic protein (MBP) in complete Freunds adjuvant (CFA) containing high dose of mycobacterial components induced severe disease, whereas immunisation with low dose of mycobacterial components induced only mild disease. Severely and mildly diseased animals were analysed with respect to infiltration of T-cells, macrophages and upregulation of MHC class II molecules on Microglia in the brain. All immunised rats showed high T-cell infiltration accompanied by Microglia activation. The degree of disease and the infiltration of macrophages varied with dose of adjuvant. Lowering the dose of adjuvant prevented the development of disease but also the influx of peripheral macrophages into the brain without affecting the peripheral T-cell response to the autoantigen. Thus, appearance of (autoreactive) T-cells in the brain and Microglia activation were probably not sufficient for development of disease. It can be concluded that peripheral macrophages play an essential or even key role in the pathogenesis of active EAE

  128. Langford D, Masliah E (2001) Crosstalk between components of the blood brain barrier and cells of the CNS in Microglial activation in AIDS. Brain Pathol. 11:306-312
    Abstract: During the progression of AIDS, a majority of patients develop cognitive disorders such as HIV encephalitis (HIVE) and AIDS dementia complex (ADC), which correlate closely with macrophage infiltration into the brain and Microglial activation. Microglial activation occurs in response to infection, inflammation and neurological disorders including HIVE, Alzheimer's disease, Parkinson's disease and multiple sclerosis. Microglia can be activated by immunoreactive cells independent of, but enhanced by HIV infection, from at least two routes. Activation may occur from signals originating from activated monocytes and lymphocytes in the blood stream, which initiate a cascade of stimuli that ultimately reach Microglia in the brain or from activated macrophages/Microglia/astrocytes within the brain. Effects of Microglial activation stemming from both systemic and CNS HIV infection act together to commence signaling feedback, leading to HIVE and increased neurodegeneration. Most recent data indicate that in AIDS patients, Microglial activation in the brain with subsequent release of excitotoxins, cytokines and chemokines leads to neurodegeneration and cognitive impairment. Since the presence of HIV in the brain results from migration of infected monocytes and lymphocytes across the vascular boundary, the development of novel therapies aimed at protecting the integrity of the blood brain barrier (BBB) upon systemic HIV infection is critical for controlling CNS infection

  129. Magnus T, Chan A, Grauer O, Toyka KV, Gold R (2001) Microglial phagocytosis of apoptotic inflammatory T cells leads to down-regulation of Microglial immune activation. J.Immunol. 167:5004-5010
    Abstract: Apoptotic cell death is an established mechanism to terminate an inflammatory response in rodent or human brains. Microglia, as the resident phagocyte, is a strong candidate for the clearance of apoptotic lymphocytes. Apoptosis was induced in cultured autologous thymocytes and in myelin basic protein (MBP)-specific, encephalitogenic T cells from Lewis rats by the addition of 0.1 microg/ml methylprednisolone. The amount of phagocytosis of apoptotic cells was assessed using an in vitro phagocytosis assay. Supernatants were collected to measure Microglial cytokine secretion. The state of immune activation in Microglia was investigated by a T cell proliferation assay and by flow cytometric analysis of Microglial surface expression of immune molecules. Microglia ingested specifically apoptotic cells (apoptotic thymocytes as well as MBP-specific T cells) in contrast to nonapoptotic control cells (p < 0.0001). Subsequent secretion of the proinflammatory cytokines TNF-alpha and IL-12 was significantly decreased, while the secretion of IL-10 and TGF-beta was not affected. Furthermore, ingestion of apoptotic cells led to increased Microglial MHC class II expression without concomitant increase in MHC class I, costimulatory molecules, and ICAM expression. The Ag-specific activation of MBP-specific T cells in cocultures with Microglia that had ingested apoptotic cells was significantly less than that of identical T cells that interacted with nonphagocytosing Microglia. Together with negative results obtained in a trans-well system, this is in support of a cell contact-mediated effect. Microglia might play an important role in the clearance of apoptotic cells. The uptake of apoptotic cells by Microglia is tolerogenic and results in a reduced proinflammatory cytokine production and a reduced activation of encephalitogenic T cells. This might help to restrict an autoimmune inflammation and minimize damage in the inflamed brain

  130. Mason JL, Suzuki K, Chaplin DD, Matsushima GK (2001) Interleukin-1beta promotes repair of the CNS. J.Neurosci. 21:7046-7052
    Abstract: Interleukin-1beta (IL-1beta) is a proinflammatory cytokine associated with the pathophysiology of demyelinating disorders such as multiple sclerosis and viral infections of the CNS. However, we demonstrate here that IL-1beta appears to promote remyelination in the adult CNS. In IL-1beta(-/-) mice, acute demyelination progressed similarly to wild-type mice and showed parallel mature oligodendrocyte depletion, Microglia-macrophage accumulation, and the appearance of oligodendrocyte precursors. In contrast, IL-1beta(-/-) mice failed to remyelinate properly, and this appeared to correlate with a lack of insulin-like growth factor-1 (IGF-1) production by Microglia-macrophages and astrocytes and to a profound delay of precursors to differentiate into mature oligodendrocytes. Thus, IL-1beta may be crucial to the repair of the CNS, presumably through the induction of astrocyte and Microglia-macrophage-derived IGF-1

  131. Minagar A, Shapshak P, Heyes M, Sheremata WA, Fujimara R, Ownby R, Goodkin K, Eisdorfer K (2001) Microglia and astrocytes in neuro-AIDS, alzheimers disease, and multiple sclerosis. ScientificWorldJournal. 1:69
    Abstract: The central nervous system (CNS) has traditionally been regarded as an immunologically privileged and isolated organ. This immunoisolation is achieved through the specific structure of the blood brain barrier and CNS immunosuppressive microenvironment. 1,2 However, activated macrophage/Microglia (MO) and astrocytes participate in the pathogenesis of various neurological diseases through expressing of MHC and adhesion molecules and releasing reactive oxygen intermediates, quinolinic acid, chemokines, cytokines, and other components of inflammation. The role of macroglia/macrophages and astrocytes in cellular/molecular mechanisms of pathogenesis of three common dementias; HIV-associated dementia (HAD), Alzheimer's disease (AD), and multiple sclerosis (MS) have been studied. Each disease had its specific clinical course and symptomatology that are well known. At the cellular and molecular levels there are both common and distinct features that are under study and require further elucidation. Recently Link et al. 3 indicated support for roles of both Microglia and astrocytes in regulating demyelination in MS. We have generalized this significant concept of neuropathogenesis to HAD and AD. HIV-1 infection is the original insult in Neuro-AIDS. In fact, our results indicate that there are neurovirulent strains of HIV-1 that invade the brain. Furthermore, we have published preliminary studies showing that there is brain regional heterogeneity of macrophage/Microglia, virus load, and virus strains. At the cellular level, there is a greater virus load in central nervous system (CNS) macrophage/Microglia than in peripheral nervous system (PNS) macrophages. In both tissues, macrophages appear to be involved in pathogenesis and produce toxic molecules including cytokines, chemokines, and nitric oxide (NO). Furthermore, we have demonstrated increased NO synthase in brain interneurons of drug abusers with AIDS associated with increased neuronal death (manuscript under review). The etiologies of AD and MS remain unknown. However, cellular/molecular mechanisms of pathogenesis are specific manifestations of these diseases. For example, it is clear that AD results from production of aberrant eta-amyloid proteins and oligopeptides. Microglia and astrocytes are activated as a result and are associated with further damage. Demyelination in MS involves lipid-laden macrophages perhaps spurred by viral and other antigens. In all three diseases cytokine/chemokine communication between Microglia and astrocytes occur and apoptosis is a mechanism of neuronal death. Also, apoptosis of oligodendrocytes occurs in MS. <?Pub _font AllCap="yes"?

  132. Minami M (2001) [Cytokines and chemokines: mediators for intercellular communication in the brain]. Yakugaku Zasshi 121:875-885
    Abstract: The brain includes glial cells (astrocytes, Microglia and oligodendrocytes) and endothelial cells in addition to neurons. Under some pathological conditions, it is invaded by leukocytes such as neutrophils, monocytes/macrophages and lymphocytes. Intercellular communication across these cell species is supposed to play crucial roles both in the brain functions and dysfunctions. However, the molecular basis of such intercellular communication remains unclear. We have studied the roles of cytokines and chemokines, which have been investigated as essential mediators in the immune and inflammatory systems, in intercellular communication across neurons, glial cells, endothelial cells and leukocytes. Messenger RNA expression of cytokines such as interleukin-1 beta was induced in brain Microglia by i.p. injection of excitotoxin and neurostimulant, at least, partly via catecholaminergic systems. Messenger RNA of other cytokines such as leukemia inhibitory factor was induced in astrocytes. This cytokine specifically induced nociceptin mRNA in the cultured cortical neurons. Constitutive expression of some chemokines such as fractalkine and stromal cell derived factor-1 alpha was observed in the brain, suggesting that they play important roles in maintenance of brain homeostasis or determination of the patterning of neurons and/or glial cells in the developing and adult brains. Cytokines such as interleukin-1 beta and chemokines such as monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha were produced in ischemic brain and implicated in ischemic brain injury. In addition to ischemia, cytokines, chemokines and their receptors have been shown to be involved in various neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease and AIDS dementia syndrome. They are potential targets for therapeutic intervention for neurodegenerative diseases

  133. Morse RH, Seguin R, McCrea EL, Antel JP (2001) NK cell-mediated lysis of autologous human oligodendrocytes. J.Neuroimmunol. 116:107-115
    Abstract: Although considered an autoimmune disease, the mechanisms underlying oligodendrocyte (OL)/myelin injury in multiple sclerosis (MS) remain to be established. We utilized in vitro assays to demonstrate that human OLs, as well as other glial elements (astrocytes, Microglia), were susceptible to injury mediated by peripheral blood-derived mononuclear cell preparations (MNCs) enriched for natural killer (NK cells) by depleting CD3(+) +/- CD19(+) cells through use of either magnetic beads or cell sorting. Cytotoxic effects of the NK cell-enriched effectors were dependent on pre-exposure of these cells to IL-2. Furthermore, we found that autologous OLs were as susceptible to injury mediated by IL-2 activated NK cells as were heterologous OLs. In context of the tissue injury that occurs in MS, our results suggest that the inflammatory milieu in MS lesions could provide conditions required for NK cell activation and that such effector cells can bypass the putative protective effects of self-MHC class I molecules that may be expressed on OLs

  134. Neumann H (2001) Control of glial immune function by neurons. Glia 36:191-199
    Abstract: The immune status of the central nervous system (CNS) is strictly regulated. In the healthy brain, immune responses are kept to a minimum. In contrast, in a variety of inflammatory and neurodegenerative diseases, including multiple sclerosis, infections, trauma, stroke, neoplasia, and Alzheimer's disease, glial cells such as Microglia gain antigen-presenting capacity through the expression of major histocompatibility complex (MHC) molecules. Further, proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF), interleukin-1beta (IL-1beta), and interferon-gamma (IFN-gamma), as well as chemokines, are synthesized by resident brain cells and T lymphocytes invade the affected brain tissue. The proinflammatory cytokines stimulate Microglial MHC expression in the lesioned CNS areas only. However, the induction of brain immunity is strongly counterregulated in intact CNS areas. For instance, recent work demonstrated that Microglia are kept in a quiescent state in the intact CNS by local interactions between the Microglia receptor CD200 and its ligand, which is expressed on neurons. Work done in our laboratory showed that neurons suppressed MHC expression in surrounding glial cells, in particular Microglia and astrocytes. This control of MHC expression by neurons was dependent on their electrical activity. In brain tissue with intact neurons, the MHC class II inducibility of Microglia and astrocytes by the proinflammatory cytokine IFN-gamma was reduced. Paralysis of neuronal electric activity by neurotoxins restored the induction of MHC molecules on Microglia and astrocytes. Loss of neurons or their physiological activity would render the impaired CNS areas recognizable by invading T lymphocytes. Thus, immunity in the CNS is inhibited by the local microenvironment, in particular by physiologically active neurons, to prevent unwanted immune mediated damage of neurons

  135. Nguyen D, Stangel M (2001) Expression of the chemokine receptors CXCR1 and CXCR2 in rat oligodendroglial cells. Brain Res.Dev.Brain Res. 128:77-81
    Abstract: Chemokines are small proteins that act as chemoattractants and activators in leukocytes during physiological and inflammatory processes. In the CNS chemokine receptors have been shown to be expressed on neurons, astrocytes and Microglia but their function in the CNS is poorly understood. CXCR1 and CXCR2 are receptors for ELR-positive CXC chemokines which include growth-regulated oncogene alpha (GRO-alpha) and interleukin-8 (IL-8). GRO-alpha is considered to influence proliferation of cultured oligodendrocyte progenitors (OLPs). Using RT-PCR we show here that the oligodendrocyte precursor cell line CG-4 expresses both CXCR1 and CXCR2. Furthermore we demonstrate that both CG-4 cells and primary cultures of rat OLPs are immunoreactive for CXCR2, the potential receptor for GRO-alpha. This finding demonstrates that the chemokine/chemokine receptor system is probably also involved in the regulation of oligodendroglial cells during developmental processes and may even have implications for inflammatory demyelinating diseases like multiple sclerosis

  136. Pahan K, Sheikh FG, Liu X, Hilger S, McKinney M, Petro TM (2001) Induction of nitric-oxide synthase and activation of NF-kappaB by interleukin-12 p40 in Microglial cells. J.Biol.Chem. 276:7899-7905
    Abstract: Interleukin-12 (IL-12) is composed of two different subunits, p40 and p35. Expression of p40 mRNA but not that of p35 mRNA in excessive amount in the central nervous system of patients with multiple sclerosis (MS) suggests that IL-12 p40 may have a role in the pathogenesis of the disease. However, the mode of action of p40 is completely unknown. Because nitric oxide produced from the induction of nitric-oxide synthase (iNOS) also plays a vital role in the pathophysiology of MS, the present study was undertaken to explore the role of p40 in the induction of NO production and the expression of iNOS in Microglia. Both IL-12 and p40(2), the p40 homodimer, dose-dependently induced the production of NO in BV-2 Microglial cells. This induction of NO production was accompanied by an induction of iNOS protein and mRNA. Induction of NO production by the expression of mouse p40 cDNA but not that of the mouse p35 cDNA suggests that the p40 but not the p35 subunit of IL-12 is involved in the expression of iNOS. In addition to BV-2 glial cells, p40(2) also induced the production of NO in mouse primary Microglia and peritoneal macrophages. However, both IL-12 and p40(2) were unable to induce the production of NO in mouse primary astrocytes. Because activation of NF-kappaB is important for the expression of iNOS, we investigated the effect of p40(2) on the activation of NF-kappaB. Induction of the DNA binding as well as the transcriptional activity of NF-kappaB by p40(2) and inhibition of p40(2)-induced expression of iNOS by SN50, a cell-permeable peptide carrying the nuclear localization sequence of p50 NF-kappaB, but not by SN50M, a nonfunctional peptide mutant, suggests that p40(2) induces the expression of iNOS through the activation of NF-kappaB. This study delineates a novel role of IL-12 p40 in inducing the expression of iNOS in Microglial cells, which may participate in the pathogenesis of neuroinflammatory diseases

  137. Palma JP, Kim BS (2001) Induction of selected chemokines in glial cells infected with Theiler's virus. J.Neuroimmunol. 117:166-170
    Abstract: To elucidate the early events in Theiler's virus-induced demyelination, a model for human multiple sclerosis (MS), chemokine gene activation in the central nervous system (CNS) resident cells upon viral infection was investigated. Viral infection selectively upregulated RANTES and IP-10 gene expression in primary astrocyte cultures and broader chemokine genes in oligodendrocyte and Microglia cultures. Both RANTES and IP-10 were stimulated by proinflammatory cytokine interferon-gamma (IFNgamma), but only RANTES by tumor necrosis factor alpha (TNFalpha), suggesting that virus infection induces chemokines overlapping with those inducible by proinflammatory cytokines. These results suggest that glial cells, astrocytes in particular, may be critical for early recruitment of inflammatory cells in the initiation of virus-induced, immune-mediated demyelination

  138. Pender MP, Rist MJ (2001) Apoptosis of inflammatory cells in immune control of the nervous system: role of glia. Glia 36:137-144
    Abstract: The elimination of inflammatory cells within the central nervous system (CNS) by apoptosis plays an important role in protecting the CNS from immune-mediated damage. T cells, B cells, macrophages, and Microglia all undergo apoptosis in the CNS. The apoptotic elimination of CNS-reactive T cells is particularly important, as these cells can recruit and activate other inflammatory cells. T-cell apoptosis contributes to the resolution of CNS inflammation and clinical recovery from attacks of experimental autoimmune encephalomyelitis (EAE), an animal model of the demyelinating disease multiple sclerosis (MS). T-cell apoptosis in the CNS in EAE occurs in both an antigen-specific and an antigen-nonspecific manner. In antigen-specific T-cell apoptosis, it is proposed that T cells that recognize their antigen in the CNS, such as CNS-reactive T cells, are deleted by the process of activation-induced apoptosis after activation of the T-cell receptor. This may result from the ligation of T-cell death receptors (such as CD95 (Fas) or tumor necrosis factor (TNF) receptor 1) by CD95 ligand (CD95L) or TNF expressed by the same T cell or possibly by Microglia, astrocytes or neurons. Inadequate costimulation of the T cell by antigen-presenting glial cells may render T cells susceptible to activation-induced apoptosis. T cells expressing CD95 may also die in an antigen-nonspecific manner after interacting with glial cells expressing CD95L. Other mechanisms for antigen-nonspecific T-cell apoptosis include the endogenous release of glucocorticosteroids, deprivation of interleukin-2, and the release of nitric oxide by macrophages or glia. Apoptosis of autoreactive T cells in the CNS is likely to be important in preventing the development of autoimmune CNS diseases such as MS

  139. Penninger JM, Irie-Sasaki J, Sasaki T, Oliveira-dos-Santos AJ (2001) CD45: new jobs for an old acquaintance. Nat.Immunol. 2:389-396
    Abstract: Identified as the first and prototypic transmembrane protein tyrosine phosphatase (PTPase), CD45 has been extensively studied for over two decades and is thought to be important for positively regulating antigen-receptor signaling via the dephosphorylation of Src kinases. However, new evidence indicates that CD45 can function as a Janus kinase PTPase that negatively controls cytokine-receptor signaling. A point mutation in CD45, which appears to affect CD45 dimerization, and a genetic polymorphism that affects alternative CD45 splicing are implicated in autoimmunity in mice and multiple sclerosis in humans. CD45 is expressed in multiple isoforms and the modulation of specific CD45 splice variants with antibodies can prevent transplant rejections. In addition, loss of CD45 can affect Microglia activation in a mouse model for Alzheimer's disease. Thus, CD45 is moving rapidly back into the spotlight as a drug target and central regulator involved in differentiation of multiple hematopoietic cell lineages, autoimmunity and antiviral immunity

  140. Peterson JW, Bo L, Mork S, Chang A, Trapp BD (2001) Transected neurites, apoptotic neurons, and reduced inflammation in cortical multiple sclerosis lesions. Ann.Neurol. 50:389-400
    Abstract: multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that causes motor, sensory, and cognitive deficits. The present study characterized demyelinated lesions in the cerebral cortex of MS patients. One hundred twelve cortical lesions were identified in 110 tissue blocks from 50 MS patients. Three patterns of cortical demyelination were identified: Type I lesions were contiguous with subcortical white matter lesions; Type II lesions were small, confined to the cortex, and often perivascular; Type III lesions extended from the pial surface to cortical layer 3 or 4. Inflammation and neuronal pathology were studied in tissue from 8 and 7 patients, respectively. Compared to white matter lesions, cortical lesions contained 13 times fewer CD3-positive lymphocytes (195 vs 2,596/mm3 of tissue) and 6 times fewer CD68-positive Microglia/macrophages (11,948 vs 67,956/mm3 of tissue). Transected neurites (both axons and dendrites) occurred at a density of 4,119/mm3 in active cortical lesions, 1,107/mm3 in chronic active cortical lesions, 25/mm3 in chronic inactive cortical lesions, 8/mm3 in myelinated MS cortex, and 1/mm3 in control cortex. In active and chronic active cortical lesions, activated Microglia closely apposed and ensheathed apical dendrites, neurites, and neuronal perikarya. In addition, apoptotic neurons were increased significantly in demyelinated cortex compared to myelinated cortex. These data support the hypothesis that demyelination, axonal transection, dendritic transection, and apoptotic loss of neurons in the cerebral cortex contribute to neurological dysfunction in MS patients

  141. Portis JL (2001) Genetic determinants of neurovirulence of murine oncornaviruses. Adv.Virus Res. 56:3-38

  142. Prineas JW, Kwon EE, Cho ES, Sharer LR, Barnett MH, Oleszak EL, Hoffman B, Morgan BP (2001) Immunopathology of secondary-progressive multiple sclerosis. Ann.Neurol. 50:646-657
    Abstract: Twenty-three plaques obtained at early autopsy from 2 patients with secondary-progressive multiple sclerosis were examined immunohistochemically for Microglia/macrophages, and for immunoglobulins and components of activated complement. Most of the lesions examined in both cases exhibited evidence of low-grade active demyelination of an unusual type (frustrated phagocytosis) in periplaque white matter. This included linear groups of Microglia engaging short segments of disrupted myelin that were associated with deposits of C3d, an opsonin formed during complement activation. Similar Microglia/C3d/myelin profiles were not observed in newly forming lesions in cases of acute multiple sclerosis or other central white matter diseases. As C3d coupling is known to increase the immunogenicity of potential antigens enormously, present findings point to disrupted myelin close to plaques as a possible source of the putative multiple sclerosis antigen. Ongoing myelin destruction found in a high proportion of old, established plaques was surprising. It suggests that slowly expanding lesions (progressive plaques), in which ongoing myelin breakdown occurs in the absence of florid perivascular cell cuffing or other histological signs of acute inflammation, contribute to disease progression in cases of secondary-progressive multiple sclerosis

  143. Redwine JM, Buchmeier MJ, Evans CF (2001) In vivo expression of major histocompatibility complex molecules on oligodendrocytes and neurons during viral infection. Am.J.Pathol. 159:1219-1224
    Abstract: Demyelination in multiple sclerosis and in animal models is associated with infiltrating CD8+ and CD4+ T cells. Although oligodendrocytes and axons are damaged in these diseases, the roles T cells play in the demyelination process are not completely understood. Antigen-specific CD8+ T cell lysis of target cells is dependent on interactions between the T cell receptor and major histocompatibility complex (MHC) class I-peptide complexes on the target cell. In the normal central nervous system, expression of MHC molecules is very low but often increases during inflammation. We set out to precisely define which central nervous system cells express MHC molecules in vivo during infection with a strain of murine hepatitis virus that causes a chronic, inflammatory demyelinating disease. Using double immunofluorescence labeling, we show that during acute infection with murine hepatitis virus, MHC class I is expressed in vivo by oligodendrocytes, neurons, Microglia, and endothelia, and MHC class II is expressed only by Microglia. These data indicate that oligodendrocytes and neurons have the potential to present antigen to T cells and thus be damaged by direct antigen-specific interactions with CD8+ T lymphocytes

  144. Reynolds R, Cenci dB, I, Dawson M, Levine J (2001) The response of adult oligodendrocyte progenitors to demyelination in EAE. Prog.Brain Res. 132:165-174
    Abstract: Cells with the phenotypic characteristics of oligodendrocyte progenitors (NG2+/PDGF alpha R+/O4+) are found throughout the adult mammalian CNS in numbers similar to Microglia. They are a reactive glial cell population and respond to demyelination by increasing in number, thereby repopulating the lesion site with cells capable of differentiating into remyelinating oligodendrocytes. Direct evidence that they differentiate into remyelinating cells is missing, although this is the most likely scenario. Cells with the same phenotype are found in normal human CNS tissue and also in chronic MS lesions. Further studies on this intriguing cell type are necessary in order to understand the molecular signals involved in their reaction to injury, particularly in multiple sclerosis

  145. Ruprecht K, Kuhlmann T, Seif F, Hummel V, Kruse N, Bruck W, Rieckmann P (2001) Effects of oncostatin M on human cerebral endothelial cells and expression in inflammatory brain lesions. J.Neuropathol.Exp.Neurol. 60:1087-1098
    Abstract: Oncostatin M (OSM) is a member of the interleukin (IL)-6 cytokine family and modulates inflammatory responses. Here we investigated the role of OSM as an immunoregulatory factor for human cerebral endothelial cells (HCEC). Using RT-PCR we detected transcripts of the receptor components involved in OSM signaling, gp130, OSM receptor (OSMR)-beta, and leukemia inhibitory factor receptor (LIFR), in HCEC. A parallel FACS analysis revealed surface expression of gp130 and OSMR-beta, but not of LIFR on these cells. Functionally, OSM upregulated intercellular adhesion molecule-1, but did not induce vascular cell adhesion molecule-1 in HCEC. Further, OSM upregulated IL-6 and monocyte chemoattractant protein (MCP)-1, whereas IL-8 was unaffected. Combined application of tumor necrosis factor (TNF)-alpha and OSM synergistically enhanced IL-6 and MCP-1 production, but downregulated TNF-alpha-induced IL-8. As OSM regulated molecules relevant in inflammatory brain diseases, we investigated its expression in normal and pathological human brains. OSM was detected by immunohistochemistry in brains from multiple sclerosis patients in Microglia, reactive astrocytes, and infiltrating leukocytes, whereas in normal brains and noninflammatory neurological diseases. immunoreactivity was absent from the parenchyma. These data suggest that immunoregulatory functions in human cerebral endothelial cells may be a mechanism by which OSM participates in the pathophysiology of inflammatory brain disease

  146. Smith ME (2001) Phagocytic properties of Microglia in vitro: implications for a role in multiple sclerosis and EAE. Microsc.Res.Tech. 54:81-94
    Abstract: The Microglial cell, after many years of neglect, has become recognized as the sole representative cell of the immune system that resides in the normal central nervous system. While normally dormant, Microglia can be activated by secretory substances or signals associated with disease or injury, and becomes a phagocytic cell, which also produces its own injurious molecules. In the activating process, its morphology is changed from a resting process-bearing cell, into a rounded amoebic form, and displays new or increased amounts of functional markers, such as receptors and Class I and Class II MHC molecules. Microglia prepared from newborn mice or rats for tissue culture are already activated, and can be used for studies of their phagocytic properties. Although they can phagocytize foreign substances, their uptake and metabolism of myelin are emphasized here, in keeping with their role in demyelinating diseases. A number of receptors have been implicated and appear to be important in the attachment to, and ingestion of, myelin particles in vitro, including the Fc, complement, macrophage scavenger, and the Galectin-3/MAC-2 receptors, although the alpha2-macroglobulin/low-density lipoprotein receptor and mannose receptors have also been suggested as participants in myelin phagocytosis. Certain cytokines and adhesion molecules also regulate the phagocytic activity of Microglia. Comparative in vitro studies of phagocytosis by peritoneal macrophages and Microglia have shown that the two kinds of cells respond differently to regulatory molecules, and it is concluded that they have different innate properties. The role of Microglia in the demyelinative diseases experimental autoimmune encephalomyelitis and multiple sclerosis is emphasized here, and the possible means of intervention in the process leading to myelin destruction is discussed. Published 2001 Wiley-Liss, Inc

  147. Solanky M, Maeda Y, Ming X, Husar W, Li W, Cook S, Dowling P (2001) Proliferating oligodendrocytes are present in both active and chronic inactive multiple sclerosis plaques. J.Neurosci.Res. 65:308-317
    Abstract: The proliferation marker Ki-67 labels cell nuclei in the G(1), S, M, and G(2) phases of the cell cycle. We used Ki-67 immunohistochemistry to quantify proliferating glial cells in brain tissue sections from twenty-four patients, comprised of multiple sclerosis, normal brains, and other neurological disease controls. Glial proliferation was greatly increased in MS lesions when compared with control brain white matter. Both actively demyelinating/early remyelinating plaques and chronic inactive plaques of long standing often displayed large numbers of glial cells in the proliferative cycle. The bulk of these proliferating cells were of oligodendroglial lineage in the MS plaques. Ki-67 positive macrophage/Microglial lineage cells were largely restricted to acute lesions. The finding of increased numbers of proliferating oligodendroglia in most MS plaques, regardless of disease duration or activity state, indicates that the MS brain is capable of recruiting unexpectedly large numbers of new oligodendrocytes over long periods of time. The factors within the MS plaque microenvironment that provoke new oligodendrocyte generation and their subsequent loss still need to be identified

  148. Stangel M, Compston A (2001) Polyclonal immunoglobulins (IVIg) modulate nitric oxide production and Microglial functions in vitro via Fc receptors. J.Neuroimmunol. 112:63-71
    Abstract: Controlled trials in multiple sclerosis (MS) and case reports in acute demyelinating encephalomyelitis (ADEM) have shown that intravenous immunoglobulins (IVIg) are of therapeutic benefit in central nervous system (CNS) inflammatory diseases. Studies in experimental autoimmune encephalomyelitis (EAE) have suggested these effects are mediated by modulation of the cytokine network and T cell responses. However, there are no data on the influence of IVIg on the local immune reaction in the CNS, the site of inflammation in EAE. We have therefore studied the effect of IVIg on cultured rat Microglia, the main immune cell in the CNS. IVIg increased nitric oxide (NO) production in a dose-dependent manner in Microglia stimulated with IFNgamma. The increase was only marginal in LPS-treated cells, and no effect was seen in untreated Microglia or after stimulation with TNFalpha or PMA. This enhancement of NO production depended on the Fc portion of IVIg and could be abrogated by the pharmacological inhibition of Syk and phosphatidylinositol 3-kinase, two enzymes involved in the signalling cascade of Fc receptors. TNFalpha secretion was dose-dependently stimulated by IVIg in both untreated Microglia and after stimulation with LPS or IFNgamma. Again, this effect was mediated through the Fc portion. Finally, we showed that Fc receptor-mediated phagocytosis was inhibited by IVIg, presumably by blockade of the Fc receptor. These different effects may protect oligodendrocytes from antibody mediated phagocytosis and on the other hand could terminate the immune reaction by induction of apoptosis in infiltrating T cells via NO and TNFalpha. We propose that IVIg, in addition to known effects on the peripheral immune system, may also modulate the local immune reaction in CNS inflammatory disease

  149. Subramanian S, Bourdette DN, Corless C, Vandenbark AA, Offner H, Jones RE (2001) T lymphocytes promote the development of bone marrow-derived APC in the central nervous system. J.Immunol. 166:370-376
    Abstract: Certain cells within the CNS, Microglial cells and perivascular macrophages, develop from hemopoietic myelomonocytic lineage progenitors in the bone marrow (BM). Such BM-derived cells function as CNS APC during the development of T cell-mediated paralytic inflammation in diseases such as experimental autoimmune encephalomyelitis and multiple sclerosis. We used a novel, interspecies, rat-into-mouse T cell and/or BM cell-transfer method to examine the development and function of BM-derived APC in the CNS. Activated rat T cells, specific for either myelin or nonmyelin Ag, entered the SCID mouse CNS within 3-5 days of cell transfer and caused an accelerated recruitment of BM-derived APC into the CNS. Rat APC in the mouse CNS developed from transferred rat BM within an 8-day period and were entirely sufficient for induction of CNS inflammation and paralysis mediated by myelin-specific rat T cells. The results demonstrate that T cells modulate the development of BM-derived CNS APC in an Ag-independent fashion. This previously unrecognized regulatory pathway, governing the presence of functional APC in the CNS, may be relevant to pathogenesis in experimental autoimmune encephalomyelitis, multiple sclerosis, and/or other CNS diseases involving myelomonocytic lineage cells

  150. Talbot PJ, Arnold D, Antel JP (2001) Virus-induced autoimmune reactions in the CNS. Curr.Top.Microbiol.Immunol. 253:247-271

  151. Tilgner J, Volk B, Kaltschmidt C (2001) Continuous interleukin-6 application in vivo via macroencapsulation of interleukin-6-expressing COS-7 cells induces massive gliosis. Glia 35:234-245
    Abstract: The inflammatory cytokine interleukin-6 (IL-6) was found in senile plaques of Alzheimer's patients and might be involved in the pathology of Parkinson's disease and multiple sclerosis. Interestingly, an astocytosis is also found in these neurodegenerative disorders. To evaluate the direct effects of IL-6 in vivo on glial cells, we created a new in vivo model. IL-6 and mock-transfected (control group) COS-7 cells were encapsulated in a poly-acryl-nitril membrane for implantation into the rat striatum. Afterward, the host immune reaction to the membrane without encapsulated cells and the biological action of IL-6-producing capsules was evaluated. Animals with an implanted membrane without cells showed a moderate astrocytosis 5 days after the operation. Furthermore, Microglia and T-cells could be detected and after 30 days the astrocytosis decreased to a small layer around the membrane. In comparison to the control group, which received a sham operation, our results demonstrate that the response of glial cells is caused by the mechanical damage of the surgical procedure itself rather than due to the introduced membrane material. In contrast, we found a massive proliferation and activation of astrocytes and Microglia after 10 days by IL-6-secreting capsules, indicating that IL-6 is involved in the induction of gliosis. Control animals that received encapsulated mock-transfected COS-7 cells showed only a weak response. These data point to an involvement of IL-6 in the proliferation and activation of glial cells as seen in neurodegenerative disorders

  152. Trebst C, Sorensen TL, Kivisakk P, Cathcart MK, Hesselgesser J, Horuk R, Sellebjerg F, Lassmann H, Ransohoff RM (2001) CCR1+/CCR5+ mononuclear phagocytes accumulate in the central nervous system of patients with multiple sclerosis. Am.J.Pathol. 159:1701-1710
    Abstract: Mononuclear phagocytes (monocytes, macrophages, and Microglia) are considered central to multiple sclerosis (MS) pathogenesis. Molecular cues that mediate mononuclear phagocyte accumulation and activation in the central nervous system (CNS) of MS patients may include chemokines RANTES/CCL5 and macrophage inflammatory protein-1alpha/CCL3. We analyzed expression of CCR1 and CCR5, the monocyte receptors for these chemokines, on circulating and cerebrospinal fluid CD14+ cells, and in MS brain lesions. Approximately 70% of cerebrospinal fluid monocytes were CCR1+/CCR5+, regardless of the presence of CNS pathology, compared to less than 20% of circulating monocytes. In active MS lesions CCR1+/CCR5+ monocytes were found in perivascular cell cuffs and at the demyelinating edges of evolving lesions. Mononuclear phagocytes in early demyelinating stages comprised CCR1+/CCR5+ hematogenous monocytes and CCR1-/CCR5- resident Microglial cells. In later stages, phagocytic macrophages were uniformly CCR1-/CCR5+. Cultured in vitro, adherent monocytes/macrophages up-regulated CCR5 and down-regulated CCR1 expression, compared to freshly-isolated monocytes. Taken together, these findings suggest that monocytes competent to enter the CNS compartment derive from a minority CCR1+/CCR5+ population in the circulating pool. In the presence of ligand, these cells will be retained in the CNS. During further activation in lesions, infiltrating monocytes down-regulate CCR1 but not CCR5, whereas Microglia up-regulate CCR5

  153. Werner P, Pitt D, Raine CS (2001) multiple sclerosis: altered glutamate homeostasis in lesions correlates with oligodendrocyte and axonal damage. Ann.Neurol. 50:169-180
    Abstract: Glutamate excitotoxicity, recently demonstrated in an animal model of multiple sclerosis (MS), is evoked by altered glutamate homeostasis. In the present study, we investigated the major regulating factors in glutamate excitotoxicity by immunohistochemistry in MS and control white matter with markers for glutamate production (glutaminase), glutamate transport (GLAST, GLT-1 and EAAT-1), glutamate metabolism (glutamate dehydrogenase [GDH] and glutamine synthetase [GS]), axonal damage (SMI 32) and CNS cell types. Active MS lesions showed high-level glutaminase expression in macrophages and Microglia in close proximity to dystrophic axons. Correlation between glutaminase expression and axonal damage was confirmed experimentally in animals. White matter from other inflammatory neurologic diseases displayed glutaminase reactivity, whereas normals and noninflammatory conditions showed none. All three glutamate transporters were expressed robustly, mainly on oligodendrocytes, in normal, control and MS white matter, except for GLT-1, which showed low-level expression around active MS lesions. GS and GDH were present in oligodendrocytes in normal and non-MS white matter but were absent from both active and chronic silent MS lesions, suggesting lasting metabolic impediments. Thus, imbalanced glutamate homeostasis contributes to axonal and oligodendroglial pathology in MS. Manipulation of this imbalance may have therapeutic import

  154. Wilms H, Rosenstiel P, Sievers J, Deuschl G, Lucius R (2001) Cerebrospinal fluid from patients with neurodegenerative and neuroinflammatory diseases: no evidence for rat glial activation in vitro. Neurosci.Lett. 314:107-110
    Abstract: To determine the possible contribution of glial cells via oxidative stress/cytokine secretion in the pathogenesis of Parkinson's disease (PD), Alzheimer disease (AD), amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) the concentration of nitric oxide (NO) (by the Griess method) and Interleukin-6 (IL-6) (by enzyme-linked immunosorbent assay) were measured in resting rat Microglial and astrocytic cell culture supernatants stimulated by cerebrospinal fluid (CSF) (dilution 1:4, 1:10) from patients with the aforementioned diseases. Neither the concentration of NO (optical density at 450 nm: control, 0.036+/-0.006; MS, 0.034+/-0.008; AD, 0.031+/-0.006; PD, 0.02+/-0.01; lipopolysaccharide (LPS), 0.26+/-0.018) nor the amount of IL-6 (ng/ml: control, 0.112+/-0.026; PD, 0.12+/-0.027; MS, 0.123+/-0.008; ALS, 0.137+/-0.01; LPS, 1.81+/-0.11) differed in any disease group from those of unaffected controls. These findings suggest that the stimuli for inflammatory activation of glia are quite localized and not present in sufficient concentrations in the CSF of affected patients

  155. Wolf SA, Gimsa U, Bechmann I, Nitsch R (2001) Differential expression of costimulatory molecules B7-1 and B7-2 on Microglial cells induced by Th1 and Th2 cells in organotypic brain tissue. Glia 36:414-420
    Abstract: Autoreactive T-cells are involved in demyelination, neurodegeneration, and the recruitment of peripheral macrophages and nonspecific activated T-cells in autoimmune diseases such as multiple sclerosis (MS). The ligation of costimulatory B7 molecules on Microglia with CD28/CTLA-4 on T-cells is thought to be crucial to the onset and course of MS and its rodent model experimental autoimmune encephalomyelitis (EAE). It is currently unclear as to how far the nature of infiltrating T-cells has an impact on the expression of the B7 molecules on Microglia, the resident antigen-presenting cells (APCs) of the brain. We studied the expression of B7-1 and B7-2 on Microglia after encounter with preactivated Th1 and Th2 cells from transgenic mice whose T-cells express a receptor (TCR) either specific to myelin basic protein (MBP) or ovalbumin (OVA) using murine organotypic entorhinal-hippocampal slice cultures (OEHSC). Our main finding was that Th1 cells downregulate the constitutive expression of B7-2 and induce B7-1 expression while Th2 cells do not induce this B7-1 upregulation. The main difference between MBP- and OVA-specific cells was seen in experiments were Th1 cells had direct contact to APCs but not to brain tissue. In contrast to MBP-specific Th1 cells, OVA-specific Th1 cells required the addition of antigen to upregulate B7-1 and downregulate B7-2. When the cells were allowed to have contact to brain tissue, no difference was seen in the pattern of B7 regulation between OVA- and MBP-specific T-cells. Our data suggest that T-cells are able to modulate B7 expression on Microglial cells in the brain independent of antigen presentation through TCR/MHC-II ligation but presumably by soluble mediators

  156. Zavalishin IA, Zhuchenko TD, Peresedova AV (2001) [Pathogenesis and treatment of multiple sclerosis (state of the art in 2000)]. Vestn.Ross.Akad.Med.Nauk18-22
    Abstract: multiple sclerosis is universally accepted to be a multifactorial disease whose pathogenesis is due to a complex of immunopathological and pathochemical reactions. The key assumption is that only early stages of immunopathological chain reactions involve specific recognition of antigens by autoreactive T cells and antibodies. These early events trigger a demyelinating process at whose later stages of importance are macrophages and glial cells, particularly those of Microglia, which produce a great deal of biologically active substances and inflammatory mediators. A deeper insight into the pathogenesis of multiple sclerosis has provided new therapeutical approaches to treating this disease. In addition to that there are effective IFN-beta drugs (Betaferon, Rebif, Avonex) and Copaxone, other pathogenetically justified approaches are still under search. The next step of further studies is to identify subtypes of multiple sclerosis and to choose a therapy in accordance with its pathogenetical mechanisms

  157. Zheng L, Calenoff MA, Dal Canto MC (2001) Astrocytes, not Microglia, are the main cells responsible for viral persistence in Theiler's murine encephalomyelitis virus infection leading to demyelination. J.Neuroimmunol. 118:256-267
    Abstract: The BeAn strain of Theiler's murine encephalomyelitis virus (TMEV) persists in the CNS and produces a chronic inflammatory demyelinating disease that is an animal model for human multiple sclerosis (MS). The mechanisms leading to TMEV-induced demyelination are still under study but most likely involve both immune-mediated and virus induced damage to cells in the CNS, both depending on viral persistence. It is therefore important to identify the cells in which continued virus production is permitted. In this study, we looked at virus infection in primary astrocytes, Microglia and oligodendrocytes, derived from brains of neonatal susceptible SJL/J mice. As evidenced by Western blots and immunocytochemistry, we were able to detect viral antigens in all these brain-derived cells. In addition, we extended the study to spinal cord tissues from mice suffering TMEV-induced disease. Immunohistochemistry staining with anti-TMEV sera and antibodies to specific cell markers detected viral antigens in all these cells. We then asked the question whether viral antigen present in these cells, particularly in Microglia/macrophages, represented true viral replication or not. By using different techniques, including immunoprecipitation experiments and the very sensitive method of negative RNA detection through RNase protection assay, we show that both astrocytes and oligodendroglia permit de novo viral replication and viral protein synthesis but with only minimal cytopathic effects. Of these two cell types, astrocytes carry the brunt of viral replication. In Microglia, on the other hand, viral replication is restricted since only minimal amounts of negative RNA copies can be demonstrated, while there are clear signs that some of these cells undergo apoptosis. These findings show that the main cell for viral replication is the astrocyte, rather than the Microglia/macrophage. Most of the viral antigen present in macrophages, therefore, is probably the result of phagocytosis, rather than actual viral replication. In view of the demonstrated presence of viral replication in astrocytes and of great amounts of viral antigens in Microglia/macrophages, it is possible that both types of cells act as antigen presenting cells during this immunopathological disease

  158. Aldskogius H (2000) [Microglia--new target cells for neurological therapy]. Lakartidningen 97:3358-3362
    Abstract: Disturbances in the normal homeostasis of the central nervous system induce a localized activation of Microglia. This activation serves to isolate pathological processes from surrounding, intact nervous tissue. Concomitantly, healthy or minimally damaged nerve cells nearby may be negatively influenced by potent molecules released by activated Microglia. This situation appears to exist e.g. in ischemia, multiple sclerosis and Alzheimer's disease. Pharmacologic regulation of Microglial activity is therefore a rational approach to treatment of many central nervous system disorders

  159. Alldinger S, Fonfara S, Kremmer E, Baumgartner W (2000) Up-regulation of the hyaluronate receptor CD44 in canine distemper demyelinated plaques. Acta Neuropathol.(Berl) 99:138-146
    Abstract: CD44 antigen (CD44), the principle cell surface receptor for hyaluronate, is up-regulated in the human demyelinating disease multiple sclerosis on fibrous astrocytes. As astrocytes are the main target cell of canine distemper virus (CDV), the consequences of a CDV infection on the CD44 expression and distribution in brains with spontaneous demyelinating canine distemper encephalitis (CDE) were of interest. Thirteen acute, 35 subacute, and 11 chronic plaques of nine dogs with immunohistologically confirmed CDE and brains of control dogs were included in the study. For light microscopy, 5-micron-thick serial sections were stained with H&E and incubated with monoclonal antibodies (mAbs) against CD44 and canine distemper virus nucleoprotein and polyclonal antibodies (pAbs) against glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP). For immunoelectron microscopy, 90-nm-thick sections were double stained with anti-GFAP and anti-CD44 mAbs to specify CD44-expressing structures. In controls, CD44 was diffusely distributed in the white matter and single meningeal cells exhibited a marginal expression of the antigen. In acute and more prominently in subacute demyelinating encephalitis, there was a plaque-associated up-regulation of CD44 which paralleled GFAP. In chronic demyelinating lesions, a reduction of CD44 associated with a loss of GFAP-positive astrocytes was noted. Additionally, in chronic plaques, CD44 was expressed on the cell membrane of perivascular mononuclear cells. Immunoelectron microscopically, in controls, CD44 was rarely demonstrated on astrocytic cell processes. In contrast, in brains with CDE CD44 was found on the cell membrane of broadened astrocytic cell processes. In summary, CD44 is up-regulated on astrocytes in the early phase of CDE and seems to represent a marker for the activation of immune cells in the late phase of the infection

  160. Bacon KB, Harrison JK (2000) Chemokines and their receptors in neurobiology: perspectives in physiology and homeostasis. J.Neuroimmunol. 104:92-97
    Abstract: Chemokines are a large family of small secreted proteins (8-14 kDa) associated with the trafficking of leukocytes in physiological immunosurveillance as well as inflammatory cell recruitment in different disease processes. A limited repertoire of chemokines and their specific cognate receptors are detectable in cells of the CNS such as Microglia, astrocytes and neurons under physiological conditions. Coupled with distinct patterns of ligand and receptor expression in various pathologies including multiple sclerosis, trauma, neuro-AIDS, Alzheimer's disease, stroke, neuro- and glioblastomas, such phenomena have fueled the strong belief that chemokines must fulfill significant and potentially diverse functional roles in the CNS

  161. Banati RB, Newcombe J, Gunn RN, Cagnin A, Turkheimer F, Heppner F, Price G, Wegner F, Giovannoni G, Miller DH, Perkin GD, Smith T, Hewson AK, Bydder G, Kreutzberg GW, Jones T, Cuzner ML, Myers R (2000) The peripheral benzodiazepine binding site in the brain in multiple sclerosis: quantitative in vivo imaging of Microglia as a measure of disease activity. Brain 123 ( Pt 11):2321-2337
    Abstract: This study identifies by microautoradiography activated Microglia/macrophages as the main cell type expressing the peripheral benzodiazepine binding site (PBBS) at sites of active CNS pathology. Quantitative measurements of PBBS expression in vivo obtained by PET and [(11)C](R)-PK11195 are shown to correspond to animal experimental and human post-mortem data on the distribution pattern of activated Microglia in inflammatory brain disease. Film autoradiography with [(3)H](R)-PK11195, a specific ligand for the PBBS, showed minimal binding in normal control CNS, whereas maximal binding to mononuclear cells was found in multiple sclerosis plaques. However, there was also significantly increased [(3)H](R)-PK11195 binding on activated Microglia outside the histopathologically defined borders of multiple sclerosis plaques and in areas, such as the cerebral central grey matter, that are not normally reported as sites of pathology in multiple sclerosis. A similar pattern of [(3)H](R)-PK11195 binding in areas containing activated Microglia was seen in the CNS of animals with experimental allergic encephalomyelitis (EAE). In areas without identifiable focal pathology, immunocytochemical staining combined with high-resolution emulsion autoradiography demonstrated that the cellular source of [(3)H](R)-PK11195 binding is activated Microglia, which frequently retains a ramified morphology. Furthermore, in vitro radioligand binding studies confirmed that Microglial activation leads to a rise in the number of PBBS and not a change in binding affinity. Quantitative [(11)C](R)-PK11195 PET in multiple sclerosis patients demonstrated increased PBBS expression in areas of focal pathology identified by T(1)- and T(2)-weighted MRI and, importantly, also in normal-appearing anatomical structures, including cerebral central grey matter. The additional binding frequently delineated neuronal projection areas, such as the lateral geniculate bodies in patients with a history of optic neuritis. In summary, [(11)C](R)-PK11195 PET provides a cellular marker of disease activity in vivo in the human brain

  162. Becher B, Prat A, Antel JP (2000) Brain-immune connection: immuno-regulatory properties of CNS-resident cells. Glia 29:293-304
    Abstract: Even though the immune privileged status of the central nervous system (CNS) limits access of systemic immune cells through the blood brain barrier (BBB), an immune response can occur in this compartment with or without major breach of the BBB. In this review, we consider properties of resident cells of the CNS, that participate in regulating the neural antigen (Ag)-directed immune responses implicated in autoimmune diseases such as multiple sclerosis (MS). Under such conditions, the CNS is usually viewed as the target or victim of the immune assault, because such immune responses are thought to be initiated and regulated within the systemic immune compartment. The CNS-endogenous cells may themselves, however, initiate, regulate and sustain an immune response. We consider the immune regulatory functions within the CNS in terms of events occurring within the CNS parenchyma (Microglia, astroglia) and at the vascular interface. These regulatory functions involve antigen presentation to T cells and polarization of the cytokine response of these cells. Such responses may contribute not only to the overall tissue injury in primary immune disorders but also in a wide range of traumatic, ischemic and degenerative processes

  163. Beyer M, Gimsa U, Eyupoglu IY, Hailer NP, Nitsch R (2000) Phagocytosis of neuronal or glial debris by Microglial cells: upregulation of MHC class II expression and multinuclear giant cell formation in vitro. Glia 31:262-266
    Abstract: Most CNS pathologies are accompanied by the occurrence of activated, phagocytic Microglial cells. We intended to investigate whether (1) isolated Microglial cells removed from the CNS cytokine network sustain their capacity to acquire an activated phenotype when challenged with cellular or noncellular debris; and (2) different substrates lead to different patterns of Microglial activation. It was observed that although removed from their usual surroundings Microglial cells preserve their ability to transform to an amoeboid morphology, form multinucleated giant cells, and enhance their expression of MHC class II when exposed to membranes of neuronal or glial origin. Furthermore, cellular substrates derived from primary hippocampal neuronal cultures, neuroblastic cells (B50), or glial cells were all able to induce similar morphological changes and enhanced expression of MHC class II. In contrast, phagocytosis of Latex beads induced an amoeboid morphology but no increase in the expression of immunologically relevant molecules. Interferon-beta (IFN-beta), a substance clinically used in the treatment of the relapsing-remitting form of multiple sclerosis, was shown to inhibit the phagocytosis-induced upregulation of MHC-class II. In summary, phagocytic Microglial cells are independent from the CNS cytokine network in their transition from a resting to an activated phenotype; and different cellular substrates, regardless whether they are of neuronal, glial, or even malignant origin, result in similar morphological and functional changes

  164. Boven LA, Montagne L, Nottet HS, De Groot CJ (2000) Macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and RANTES mRNA semiquantification and protein expression in active demyelinating multiple sclerosis (MS) lesions. Clin.Exp.Immunol. 122:257-263
    Abstract: MS is a demyelinating disease characterized by infiltration of monocytes and lymphocytes into the brain parenchyma, destruction of oligodendrocytes and loss of myelin. Since chemokines play a major role in the migration of monocytes and T cells, we here investigated the expression of the CC chemokines MIP-1alpha, MIP-1beta, and RANTES in brain tissue from MS patients using reverse transcriptase-polymerase chain reaction techniques. Both MIP-1beta as well as RANTES were found to be significantly elevated in brain tissue of MS patients. In addition, MIP-1alpha was also increased, although not significantly. Immunohistochemistry revealed that, whereas RANTES was mainly localized in reactive astrocytes, MIP-1alpha and MIP-1beta immunoreactivity was predominantly found in perivascular and parenchymal macrophages, containing myelin degradation products. Thus, chemokines appear to be associated with MS and an increased chemokine expression may further enhance disease progression by attracting more leucocytes into the brain parenchyma and by activation of effector functions of astrocytes and Microglial cells

  165. Cammer W (2000) Effects of TNFalpha on immature and mature oligodendrocytes and their progenitors in vitro. Brain Res. 864:213-219
    Abstract: Tumor necrosis factor alpha (TNFalpha) appears to take part in the pathogenesis of multiple sclerosis and to contribute to the degeneration of oligodendrocytes as well as neurons. TNFalpha is produced by Microglia and astrocytes, which also produce hormones and cytokines that influence its biological activity. Thus, in mixed cultures the effects of exogenous TNFalpha might be modified by products of astrocytes and Microglia. The effects of TNFalpha in oligodendrocyte-enriched cultures are reported below. We prepared the cultures by shaking oligodendrocytes off primary mixed glial-cell cultures from brains of 2-day-old rats at 7 days in vitro and plating them (0 days post-shake, DPS). Platelet-derived growth factor and fibroblast growth factor were included in the media at 1-5 DPS in order to encourage proliferation. At 2 DPS media were added with no TNFalpha (controls) or 1000, 2000 or 5000 U/ml of TNFalpha, and at 5 DPS media were replaced with fresh serum-free media. Cultures were fixed with 4% paraformaldehyde at 5, 7, 9 and 12 DPS and immunostained. Oligodendrocyte progenitors were not reduced in numbers immediately after the incubation with TNFalpha (i. e. at 5 DPS). However, after an additional 4 days in culture fewer progenitors remained in the cultures that had been treated with TNFalpha than in the untreated cultures. In the absence of the growth factors there were fewer progenitors, but their numbers also were reduced by TNFalpha. Maturation to the myelin basic protein (MBP)-positive stage was inhibited by about 36% at 9 DPS by 1000-2000 U/ml of TNFalpha, while numbers of O4+/MBP- precursors were unaffected. It is interesting that the steady-state number of O4-positive precursors was unchanged by TNFalpha at 9 DPS, when there were reductions in the numbers of A2B5-positive progenitors and MBP-positive mature oligodendrocytes. That observation suggests that the rates of proliferation, death and maturation are controlled by multiple factors, with a particularly vulnerable time at the maturation to the MBP-positive stage. At 5000 U/ml TNFalpha the specific effect on maturation was overtaken cytotoxicity. These data and a summary of the literature suggest that inhibition of MBP expression is sensitive to lower TNFalpha concentrations and incubation times than is cell survival. Specific effects on numbers of MBP-positive cells, morphology and MBP expression occur at 1000-2000 U/ml for 48-72 h or at up to 10000 U/ml for</=24 h, and the deficits remain after removal of the TNFalpha

  166. Chabot S, Yong VW (2000) Interferon beta-1b increases interleukin-10 in a model of T cell-Microglia interaction: relevance to MS. Neurology 55:1497-1505
    Abstract: BACKGROUND: The modes of action of interferon beta (IFN-beta) in MS remain unclear, but enhanced levels of the anti-inflammatory cytokine interleukin-10 (IL-10) in the CSF of patients with MS may be a marker of its prognostic efficacy. OBJECTIVE: To examine potential mechanisms by which IL-10 may be increased by IFN-ss in the milieu of the CNS. METHODS: A model of T cell interaction with Microglia in vitro was used. Production of cytokines was monitored by measuring the levels of various cytokine proteins, using ELISA. RESULTS: Pretreatment of T cells with IFN-beta potentiates the production of IL-10 when they interact with adult human Microglia, human fetal Microglia, or U937 cells treated with phorbol-12-myristate-13-acetate (PMA) and IFN-gamma. The enhancing effect of IFN-beta on IL-10 requires cell-cell contact, but does not seem to depend on pathways implicated in Microglia-T cell interactions, involving CD40, CD23, and B7. In contrast to IL-10, IFN-beta inhibits the production of other cytokines, including tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-4, IL-12, and IL-13. CONCLUSIONS: The increase of IL-10 in Microglia-T cell interaction by IFN-beta together with a decrease of other cytokines may lead to a noninflammatory milieu in the CNS. This mechanism could contribute to the efficacy of IFN-beta in MS

  167. Chang A, Nishiyama A, Peterson J, Prineas J, Trapp BD (2000) NG2-positive oligodendrocyte progenitor cells in adult human brain and multiple sclerosis lesions. J.Neurosci. 20:6404-6412
    Abstract: multiple sclerosis (MS) is characterized by multifocal loss of myelin, oligodendrocytes, and axons. Potential MS therapies include enhancement of remyelination by transplantation or manipulation of endogenous oligodendrocyte progenitor cells. Characteristics of endogenous oligodendrocyte progenitors in normal human brain and in MS lesions have not been studied extensively. This report describes the distribution of cells in sections from normal adult human brain and MS lesions by using antibodies directed against NG2, an integral membrane chondroitin sulfate proteoglycan expressed by oligodendrocyte progenitor cells. Stellate-shaped NG2-positive cells were detected in the white and gray matter of normal adult human brain and appeared as abundant as, but distinct from, astrocytes, oligodendrocytes, and Microglia. Stellate-shaped or elongated NG2-positive cells also were detected in chronic MS lesions. A subpopulation of the elongated NG2-positive cells expressed the putative apoptotic signaling molecule p75(NTR). TUNEL-positive cells in three active, nine chronic active, and four chronic inactive lesions, however, were p75(NTR)-negative. These studies identify cells with phenotypic markers of endogenous oligodendrocyte progenitors in the mature human CNS and suggest that functional subpopulations of NG2-positive cells exist in MS lesions. Endogenous oligodendrocyte progenitor cells may represent a viable target for future therapies intended to enhance remyelination in MS patients

  168. Deininger MH, Kremsner PG, Meyermann R, Schluesener HJ (2000) Differential cellular accumulation of transforming growth factor-beta1, -beta2, and -beta3 in brains of patients who died with cerebral malaria. J.Infect.Dis. 181:2111-2115
    Abstract: In cerebral malaria (CM), pathologic cytokine expression patterns are thought to contribute to disruption of the blood-brain barrier, inflammation, and astrocytic scar formation. Expression of transforming growth factor (TGF)-beta1, -beta2, and -beta3 was analyzed in the brains of 7 patients who died with CM and in 8 control patients. In the brains of patients with CM, there were significantly (P=.0003) more TGF-beta1-immunoreactive astrocytes adjacent to brain vessels with deposition of malarial pigment, significantly (P=.0081) more TGF-beta2-expressing macrophages/Microglial cells in glioses of ring hemorrhages and Durck's granulomas, and significantly (P=.0022) more TGF-beta3-expressing smooth-muscle cells and endothelial cells of brain vessels with sequestration. It is concluded that focal accumulation of TGF-beta1, -beta2, and -beta3 provides evidence for their involvement in the reorganization process of the brain parenchyma, immunologic dysfunction, and endothelial cell activation in patients with CM

  169. Dittel BN (2000) Evidence that Fas and FasL contribute to the pathogenesis of experimental autoimmune encephalomyelitis. Arch.Immunol.Ther.Exp.(Warsz.) 48:381-388
    Abstract: The well established and characterized animal model for the human demyelinating autoimmune disease multiple sclerosis (MS) is known as experimental autoimmune encephalomyelitis (EAE). EAE is clinically characterized by focal areas of inflammation and demyelination and an infiltrate composed of large numbers of lymphocytes and macrophages, often found in a perivascular localization but also throughout the central nervous system (CNS). Active immunization of mice with several different protein components of myelin, including myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG), are capable of eliciting an immune response resulting in the quintessential symptoms of EAE: ascending paralysis involving the tail and then the limbs. Depending on the mouse strain and myelin antigen utilized, the disease course can be acute or chronic relapsing, characterized by a rapid onset of hind limb weakness that commonly progresses to paralysis, followed by spontaneous remission starting 7-10 days after the initial appearance of symptoms. EAE can also be induced passively by the adoptive transfer of in vitro activated CD4+ T cell clones or lines, typically of the Th1 phenotype, into irradiated susceptible recipients. The mechanisms involved in the cellular pathogenesis leading to paralysis and demyelination have been extensively studied and are primarily mediated by CD4+ T cells of the Th1 phenotype, with specificity for myelin antigens. Following activation, Th1 CD4 T cells produce in abundance the inflammatory cytokines TNF-alpha, IFN-gamma and lymphotoxin alpha (LT-alpha, also know as TNF-beta). IFN-gamma production is highly correlated with encephalitogenicity and may contribute to disease by up-regulation of adhesion molecules on endothelial cells, facilitating migration of lymphocytes into the CNS; by induction of major histocompatibility complex (MHC) class I and MHC class II molecules on astrocytes, Microglial cells and brain endothelium, facilitating antigen (Ag) presentation in the CNS; and by activation of macrophages, leading to production of nitric oxide, a potent cytotoxic molecule. TNF-alpha and LT-alpha are both members of the TNF family of molecules and cause cell death by apoptosis following interaction with their counter-receptors, the TNFR1 and TNFR2, leading to a cascade of proteolytic events culminating in the blebbing of the cytoplasmic membrane, nuclear condensation and DNA fragmentation. Consequently, the production of TNF-alpha and LT-alpha by Th1 clones has been correlated with encephalitogenic potential and antibodies (Abs) to both prevents EAE upon transfer of encephalitogenic clones. Even though substantial evidence exists for the role of inflammatory cytokines in the pathogenesis of EAE, other mechanisms of myelin destruction are thought to exist. To date, many reports have implicated a role for the cell death-inducing ligand pair Fas and Fas-ligand (FasL)

  170. Drew PD, Chavis JA (2000) Female sex steroids: effects upon Microglial cell activation. J.Neuroimmunol. 111:77-85
    Abstract: multiple sclerosis occurs more commonly in females than males. However, the mechanisms resulting in gender differences in multiple sclerosis are unknown. Activated Microglia are believed to contribute to multiple sclerosis pathology, perhaps in part due to production of nitric oxide (NO) and TNF-alpha, molecules which can be toxic to cells including oligodendrocytes. The current study demonstrates that the female sex steroids estriol, beta-estradiol and progesterone inhibit lipopolysaccharide (LPS) induction of nitric oxide (NO) production by primary rat Microglia and by the mouse N9 Microglial cell line. These hormones act by inhibiting the production of inducible nitric oxide synthase (iNOS) which catalyses the synthesis of NO. Estriol likely inhibits iNOS gene expression since the hormone blocks LPS induction of iNOS RNA levels. The pro-inflammatory cytokines IFN-gamma and TNF-alpha are believed to be important modulators of multiple sclerosis. Here, we demonstrate that estrogens and progesterone also inhibit NO production by Microglial cells activated in response to these cytokines. Activated Microglia elicit TNF-alpha in addition to NO and we further demonstrate that estrogens and progesterone repress TNF-alpha production by these cells. Finally, estriol and progesterone, at concentrations consistent with late pregnancy, inhibit NO and TNF-alpha production by activated Microglia, suggesting that hormone inhibition of Microglial cell activation may contribute to the decreased severity of multiple sclerosis symptoms commonly associated with pregnancy

  171. Edwards JA, Denis F, Talbot PJ (2000) Activation of glial cells by human coronavirus OC43 infection. J.Neuroimmunol. 108:73-81
    Abstract: multiple sclerosis (MS) is an immune-mediated demyelinating disease that could be triggered by a viral infection. Coronaviruses induce an MS-like disease in rodents, are neuroinvasive in humans and can infect primary cultures of human astrocytes and Microglia. Infection of the human astrocytic cell line U-373MG by the OC43 strain of human coronavirus caused an upregulation of IL-6, TNF-alpha, and MCP-1 mRNA expression. This virus also modulated the activity of matrix metalloproteinases-2 and -9 and augmented nitric oxide production in both U-373MG cells and the human Microglial cell line CHME-5. Thus, a coronaviral infection of glial cells could lead to the production of inflammatory molecules that have been associated with central nervous system pathologies such as MS

  172. Emerson MR, LeVine SM (2000) Heme oxygenase-1 and NADPH cytochrome P450 reductase expression in experimental allergic encephalomyelitis: an expanded view of the stress response. J.Neurochem. 75:2555-2562
    Abstract: Oxidative stress is implicated in the pathogenesis of experimental allergic encephalomyelitis (EAE), a model for multiple sclerosis. Heme oxygenase-1 (HO-1) is a heat shock protein induced by oxidative stress. HO-1 metabolizes the pro-oxidant heme to the antioxidant biliverdin and CO. HO-1 requires electrons, donated by NADPH cytochrome P450 reductase (henceforth, reductase), for catalytic activity. EAE was induced with a peptide of proteolipid protein in SJL mice, and the expression of HO-1 and reductase in the hindbrain was analyzed. HO-1 protein levels were significantly increased in EAE animals compared with control mice. HO-1 expression was present in ameboid macrophages, reactive Microglia, and astrocytes in white matter tracks. Bergmann glia and ameboid macrophages also were occasionally stained in the molecular layer of the cerebellum. Unlike HO-1, reductase protein levels decreased with disease severity. HO-1 and reductase were associated with each other in endoplasmic reticulum micelles, suggesting that the decrease in reductase does not interfere with its association with HO-1. In cells that express HO-1, the association of reductase with HO-1 should competitively inhibit the interaction of reductase with cytochrome P450 isozymes and thereby limit free radical production as the latter two enzymes act cooperatively to produce superoxide. The increase in HO-1 together with the decrease in reductase may be part of a common defense mechanism attempting to minimize tissue damage in several neurological conditions

  173. Frigerio S, Silei V, Ciusani E, Massa G, Lauro GM, Salmaggi A (2000) Modulation of fas-ligand (Fas-L) on human Microglial cells: an in vitro study. J.Neuroimmunol. 105:109-114
    Abstract: The expression of Fas-Ligand (Fas-L) on Microglia could be relevant in multiple sclerosis immunopathology. The present study was performed to evaluate in vitro the expression of Fas-L in human Microglial cells both unstimulated and after stimulation with IFN-gamma, beta-IFN-1b and beta-IFN-1b+IFN-gamma. Cells were stimulated for 6,12, 24 and 48 h. Surface Fas-L was evaluated by flow cytometry, total Fas-L by Western blot, whereas mRNA for Fas-L was measured by RT-PCR. We also evaluated the capacity of Microglial cells to induce, in vitro, apoptosis on Fas-positive T leukemia Jurkat cells. Our results showed a constitutive expression of Fas-L on Microglia. IFN-gamma downregulated the expression of the molecule, while beta-IFN-1b and beta-IFN-1b+IFN- gamma did not. The amount of surface Fas-L was related to the ability of Microglial cells to induce apoptosis in Fas-positive target cells, which was partly inhibited by blockade of the Fas-Fas-L pathway

  174. Gao X, Gillig TA, Ye P, D'Ercole AJ, Matsushima GK, Popko B (2000) Interferon-gamma protects against cuprizone-induced demyelination. Mol.Cell Neurosci. 16:338-349
    Abstract: Evidence suggests that interferon-gamma (IFN-gamma), a proinflammatory cytokine secreted by activated T lymphocytes, contributes a deleterious effect to immune-mediated demyelinating disorders such as multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Nevertheless, mouse strains that are normally resistant to EAE induction become susceptible when the gene encoding either IFN-gamma or its receptor is mutated, demonstrating that the role that this cytokine plays in demyelinating disorders is complex. We have examined the effect of IFN-gamma in a chemically induced model of CNS demyelination. Mice that receive through their diet the copper chelator cuprizone display extensive demyelination of the corpus callosum. Remarkably, transgenic mice that ectopically express low levels of IFN-gamma in the CNS did not display evidence of demyelination when treated with cuprizone, nor did they shows signs of oligodendroglial death, astrogliosis, or microgliosis, which are typically seen in treated animals. Myelin protein gene expression was, however, dramatically reduced in both the treated control and the transgenic animals, indicating that demyelination is not an obligatory consequence of a large diminution of myelin protein synthesis. Interestingly, the CNS of the IFN-gamma-expressing mice contained elevated levels of insulin-like growth factor I, which has been demonstrated to have a protective effect against the demyelinating action of cuprizone

  175. Gimsa U, Peter SV, Lehmann K, Bechmann I, Nitsch R (2000) Axonal damage induced by invading T cells in organotypic central nervous system tissue in vitro: involvement of Microglial cells. Brain Pathol. 10:365-377
    Abstract: Neuroinflammation in the course of multiple sclerosis and experimental autoimmune encephalomyelitis results in demyelination and, recently demonstrated, axonal loss. Invading neuroantigen specific T cells are the crucial cellular elements in these processes. Here we demonstrate that invasion of activated T cells induces a massive Microglial attack on myelinated axons in entorhinal-hippocampal slice cultures. Flow cytometry analysis of activation markers revealed that the activation state of invading MBP-specific T cells was significantly lower in comparison to PMA-activated T cells. Moreover, MBP-specific T cells showed a significantly lower secretion of IFN-gamma. Conversely, MBP-specific T cells displayed a significantly higher potential to trigger activation of Microglial cells, i.e. upregulation of MHC class II and ICAM-1 expression, and, most importantly, Microglial phagocytosis of pre-traced axons. Our data suggest that this was mediated via specific cellular interactions of T cells and Microglial cells since IFN-gamma alone was not sufficient to induce axonal damage while such damage was apparent in response to TNF-alpha which is released by activated Microglial cells. TNF-alpha secretion by both T cell populations was negligible. Thus, MBP-specific T cells which invade nervous tissue in the course of neuroinflammation are more effective in axon-damaging recruiting Microglial cells than activated T cells of other specificities

  176. Hisahara S, Araki T, Sugiyama F, Yagami K, Suzuki M, Abe K, Yamamura K, Miyazaki J, Momoi T, Saruta T, Bernard CC, Okano H, Miura M (2000) Targeted expression of baculovirus p35 caspase inhibitor in oligodendrocytes protects mice against autoimmune-mediated demyelination. EMBO J. 19:341-348
    Abstract: The mechanisms underlying oligodendrocyte (OLG) loss and the precise roles played by OLG death in human demyelinating diseases such as multiple sclerosis (MS), and in the rodent model of MS, experimental autoimmune encephalomyelitis (EAE), remain to be elucidated. To clarify the involvement of OLG death in EAE, we have generated transgenic mice that express the baculovirus anti-apoptotic protein p35 in OLGs through the Cre-loxP system. OLGs from cre/p35 transgenic mice were resistant to tumor necrosis factor-alpha-, anti-Fas antibody- and interferon-gamma-induced cell death. cre/p35 transgenic mice were resistant to EAE induction by immunization with the myelin oligodendrocyte glycoprotein. The numbers of infiltrating T cells and macrophages/Microglia in the EAE lesions were significantly reduced, as were the numbers of apoptotic OLGs expressing the activated form of caspase-3. Thus, inhibition of apoptosis in OLGs by p35 expression alleviated the severity of the neurological manifestations observed in autoimmune demyelinating diseases

  177. Holz A, Bielekova B, Martin R, Oldstone MB (2000) Myelin-associated oligodendrocytic basic protein: identification of an encephalitogenic epitope and association with multiple sclerosis. J.Immunol. 164:1103-1109
    Abstract: Myelin-associated oligodendrocytic basic protein (MOBP) is an abundant myelin constituent expressed exclusively by oligodendrocytes, the myelin-forming cells of the CNS. We report that MOBP causes experimental allergic encephalomyelitis and is associated with multiple sclerosis. First, we note that purified recombinant MOBP inoculated into SJL/J mice produces CNS disease. Tests of overlapping peptides spanning the murine MOBP molecule map the encephalitogenic site to amino acids 37-60. MOBP-induced experimental allergic encephalomyelitis shows a severe clinical course and is characterized by a prominent CD4+ T lymphocyte infiltration and a lesser presence of CD8+ T cells and Microglia/macrophages around vessels and in the white matter of the CNS. Second, PBL obtained from patients with relapsing/remitting multiple sclerosis mount a proliferative response to human MOBP, especially at amino acids 21-39. This response equals or exceeds the response to myelin basic protein and an influenza virus hemagglutinin peptide, both serving as internal controls. Thus, a novel myelin Ag, MOBP aa 37-60, plays a role in rodent autoimmune CNS disease, and its human MOBP counterpart is associated with the human demyelinating disease multiple sclerosis

  178. Kantarci OH, Atkinson EJ, Hebrink DD, McMurray CT, Weinshenker BG (2000) Association of a myeloperoxidase promoter polymorphism with multiple sclerosis. J.Neuroimmunol. 105:189-194
    Abstract: Myeloperoxidase (MPO) generates hypochlorous acid and other reactive oxygen intermediates leading to tissue damage. MPO is expressed in macrophages-Microglia in multiple sclerosis (MS) lesions. A G-->A substitution that abolishes an SP1 transcription factor consensus sequence in the promoter reduces gene expression. We studied the association of the genetic variant with MS. We did not find an association with gender, age at onset, susceptibility to, or the course and severity of MS in a population-based sample of 122 patients from Olmsted County

  179. Krogsgaard M, Wucherpfennig KW, Cannella B, Hansen BE, Svejgaard A, Pyrdol J, Ditzel H, Raine C, Engberg J, Fugger L, Canella B (2000) Visualization of myelin basic protein (MBP) T cell epitopes in multiple sclerosis lesions using a monoclonal antibody specific for the human histocompatibility leukocyte antigen (HLA)-DR2-MBP 85-99 complex. J.Exp.Med. 191:1395-1412
    Abstract: Susceptibility to multiple sclerosis (MS) is associated with the human histocompatibility leukocyte antigen (HLA)-DR2 haplotype, suggesting that major histocompatibility complex class II-restricted presentation of central nervous system-derived antigens is important in the disease process. Antibodies specific for defined HLA-DR2-peptide complexes may therefore be valuable tools for studying antigen presentation in MS. We have used phage display technology to select HLA-DR2-peptide-specific antibodies from HLA-DR2-transgenic mice immunized with HLA-DR2 molecules complexed with an immunodominant myelin basic protein (MBP) peptide (residues 85-99). Detailed characterization of one clone (MK16) demonstrated that both DR2 and the MBP peptide were required for recognition. Furthermore, MK16 labeled intra- and extracellular HLA-DR2-MBP peptide complexes when antigen-presenting cells (APCs) were pulsed with recombinant MBP. In addition, MK16 inhibited interleukin 2 secretion by two transfectants that expressed human MBP-specific T cell receptors. Analysis of the structural requirement for MK16 binding demonstrated that the two major HLA-DR2 anchor residues of MBP 85-99 and the COOH-terminal part of the peptide, in particular residues Val-96, Pro-98, and Arg-99, were important for binding. Based on these results, the antibody was used to determine if the HLA-DR2-MBP peptide complex is presented in MS lesions. The antibody stained APCs in MS lesions, in particular Microglia/macrophages but also in some cases hypertrophic astrocytes. Staining of APCs was only observed in MS cases with the HLA-DR2 haplotype but not in cases that carried other haplotypes. These results demonstrate that HLA-DR2 molecules in MS lesions present a myelin-derived self-peptide and suggest that Microglia/macrophages rather than astrocytes are the predominant APCs in these lesions

  180. Lane TE, Liu MT, Chen BP, Asensio VC, Samawi RM, Paoletti AD, Campbell IL, Kunkel SL, Fox HS, Buchmeier MJ (2000) A central role for CD4(+) T cells and RANTES in virus-induced central nervous system inflammation and demyelination. J.Virol. 74:1415-1424
    Abstract: Infection of C57BL/6 mice with mouse hepatitis virus (MHV) results in a demyelinating encephalomyelitis characterized by mononuclear cell infiltration and white matter destruction similar to the pathology of the human demyelinating disease multiple sclerosis. The contributions of CD4(+) and CD8(+) T cells in the pathogenesis of the disease were investigated. Significantly less severe inflammation and demyelination were observed in CD4(-/-) mice than in CD8(-/-) and C57BL/6 mice (P < or = 0.002 and P < or = 0.001, respectively). Immunophenotyping of central nervous system (CNS) infiltrates revealed that CD4(-/-) mice had a significant reduction in numbers of activated macrophages/Microglial cells in the brain compared to the numbers in CD8(-/-) and C57BL/6 mice, indicating a role for these cells in myelin destruction. Furthermore, CD4(-/-) mice displayed lower levels of RANTES (a C-C chemokine) mRNA transcripts and protein, suggesting a role for this molecule in the pathogenesis of MHV-induced neurologic disease. Administration of RANTES antisera to MHV-infected C57BL/6 mice resulted in a significant reduction in macrophage infiltration and demyelination (P < or = 0.001) compared to those in control mice. These data indicate that CD4(+) T cells have a pivotal role in accelerating CNS inflammation and demyelination within infected mice, possibly by regulating RANTES expression, which in turn coordinates the trafficking of macrophages into the CNS, leading to myelin destruction

  181. Luo Y, Fischer FR, Hancock WW, Dorf ME (2000) Macrophage inflammatory protein-2 and KC induce chemokine production by mouse astrocytes. J.Immunol. 165:4015-4023
    Abstract: Astrocytes are specialized cells of the CNS that are implicated in the pathogenesis of multiple sclerosis and experimental allergic encephalomyelitis. In acute and relapsing-remitting experimental allergic encephalomyelitis, the neutrophil chemoattractant CXC chemokines macrophage-inflammatory protein (MIP)-2 and KC are associated with reactive astrocytes in the parenchyma. In vitro treatment of primary astrocyte cultures with nanomolar concentrations of MIP-2 or KC markedly up-regulated expression of the monocyte/T cell chemoattractants monocyte chemoattractant protein-1, inflammatory protein-10, and RANTES by a mechanism that includes stabilization of mRNA. Production of TNF-alpha and IL-6 transcripts were also noted, as was autocrine induction of MIP-2 and KC message. In addition, low levels of MIP-1alpha and MIP-1beta were induced following treatment with MIP-2 or KC. These effects are specific to astrocytes as MIP-2 treatment of Microglial cells failed to elicit chemokine production. The astrocyte chemokine receptor for MIP-2 has 2.5 nM affinity for ligand. Astrocytes from CXCR2-deficient mice still respond to KC and MIP-2, indicating the presence of an alternative or novel high affinity receptor for these ligands. We propose that this KC/MIP-2 chemokine cascade may contribute to the persistence of mononuclear cell infiltration in demyelinating autoimmune diseases

  182. McManus CM, Liu JS, Hahn MT, Hua LL, Brosnan CF, Berman JW, Lee SC (2000) Differential induction of chemokines in human Microglia by type I and II interferons. Glia 29:273-280
    Abstract: Chemokines are secreted proteins that function as chemoattractants, mediating the recruitment of specific subsets of leukocytes to sites of tissue damage and immunological reactions. Chemokines may also function as antiviral agents, since viruses such as human immunodeficiency virus type 1 (HIV-1) use chemokine receptors as co-receptors for viral entry. This study examines whether virus-induced interferon, IFNbeta, or immune-related interferon, IFNgamma, affects the production of beta-chemokines by CNS Microglia and peripheral monocytes. When IFNbeta was used as the stimulus, induction of MIP-1alpha, MIP-1beta, MCP-1, and RANTES mRNA and protein was observed within 12 h of stimulation in Microglia. By contrast, when IFNgamma was used as the stimulus, only MCP-1 was induced. IFNbeta stimulation of blood monocytes resulted in upregulation of MIP-1alpha, MIP-1beta, and MCP-1. Thus, type I and II interferons differentially regulate beta-chemokines in human fetal Microglia and peripheral blood monocytes. These observations may have relevance for the therapeutic activity of IFNbeta in multiple sclerosis and for the antiviral effects of IFNbeta for HIV-1 infection of monocytes and Microglia

  183. Merodio M, Irache JM, Eclancher F, Mirshahi M, Villarroya H (2000) Distribution of albumin nanoparticles in animals induced with the experimental allergic encephalomyelitis. J.Drug Target 8:289-303
    Abstract: Experimental allergic encephalomyelitis (EAE) is an autoimmune disease characterised by a disruption of the blood-brain barrier (BBB), demyelination and a relevant inflammatory reaction with an intense infiltration of macrophages. These neurological disorders are similar to those observed in the multiple sclerosis (MS) disease. The use of different liposomes and adeno-associated virus has been proposed for improving the treatment of this pathogenesis. The aim of this work was to evaluate the potential and capacity of albumin nanoparticles to reach the central nervous system (CNS) in EAE-induced rats. For this purpose, the distribution of biotinylated nanoparticles within the CNS was studied. Albumin carriers were mainly found in the lumbar portion of the spinal cord, overlying the meningeal and perivascular areas. The optic chiasma, iris and the area of the Purkinje cells of the cerebellum revealed also an intense presence of these carriers. Finally, immunohistochemical studies also revealed that circulating macrophages (ED1), which migrate to damaged sites, and resident activated Microglial cells (OX42) were involved in the distribution of albumin nanoparticles. In summary, the use of nanoparticles may be useful for the design of new pharmaceutical dosage forms able to target the lesions associated with alterations of the BBB

  184. Minami M, Satoh M (2000) [Chemokines as mediators for intercellular communication in the brain]. Nippon Yakurigaku Zasshi 115:193-200
    Abstract: Chemokines constitute a large and still growing family of structurally-related small (8-10 kDa) cytokines that have chemotactic activity for leukocytes. Recently, some receptors for chemokines were reported to be used as a co-receptor by HIV at infection. In addition to their well-established role in inflammatory response and recently-reported role as a co-receptor for HIV, recent data suggest that chemokines and their receptors physiologically and pathologically play crucial roles as the mediators for intercellular communication among the cells intrinsic to and recruited into the brain; i.e., neurons, astrocytes, Microglia, endothelial cells and leukocytes. Some chemokines such as SDF-1 and fractalkine are constitutively produced in the brain, implicating that they have an important role in maintenance of CNS homeostasis or determination of the patterning of neurons and/or glial cells in developing brain and normal adult brain. Chemokines such as MCP-1, MIP-1 alpha and CINC were shown to be induced by various neuroinflammatory stimuli, suggesting that they are involved in various neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, stroke and AIDS dementia syndrome. Chemokines and their receptors are potential targets for therapeutic intervention in neurodegenerative diseases

  185. Olsson T, Lundberg C, Lidman O, Piehl F (2000) Genetic regulation of nerve avulsion-induced spinal cord inflammation. Ann.N.Y.Acad.Sci. 917:186-196
    Abstract: In the animal model for multiple sclerosis (MS), experimental autoimmune encephalitis (EAE), genetic loci correlating with incidence or severity of disease are located both within and outside of the major histocompatibility complex (MHC). Whereas polymorphisms within MHC class I and II molecules are likely to be a major determinant of MHC gene influence in rat EAE, it is still unclear how non-MHC gene regions influence disease. Genetic control of inflammation can hypothetically be either general or specific for a particular target tissue. For the latter, gene regulation of pathomechanisms in the CNS could affect reactivity of Microglia or astrocytes, local cytokine/chemokine production, or even neuronal vulnerability. We have obtained strong support for this notion by observations of rat strain-dependent variation in the inflammatory response after ventral root avulsion, a model in which mainly non-antigen-specific elements of the immune system promote inflammation. A comparison of strains with similar MHC haplotypes on different backgrounds and strains with different MHC haplotypes on the same background, respectively, demonstrates that the inflammatory phenotype is regulated mainly by non-MHC genes. Interestingly, different features of the inflammatory response, such as induction of MHC class II expression, glial activation, cytokine expression, and neuronal vulnerability, varied between rat strains and were largely independent of each other. The genetic control of several basic features of inflammation in the CNS is of great relevance not only for MS/EAE, but also for several other neurological conditions with inflammatory components such as cerebrovascular and neurogenerative dieases and trauma

  186. Penkowa M, Hidalgo J (2000) Metallothionein I+II expression and their role in experimental autoimmune encephalomyelitis. Glia 32:247-263
    Abstract: We examined the expression and roles of neuroprotective metallothionein-I+II (MT-I+II) in the rat CNS in experimental autoimmune encephalomyelitis (EAE), an animal model for the human autoimmune disease, multiple sclerosis (MS). EAE caused significant macrophage activation, T-lymphocyte infiltration, and astrogliosis in spinal cord, brain stem, and cerebellum, which peaked 14-18 days after immunization. The remission of symptoms and histopathological changes began at days 19-21 and were completed by days 30-40. MT-I+II expression was increased significantly in EAE infiltrates. In order to study the effects of increased MT levels, we administered Zn-MT-II intraperitoneally (i.p.) to rats during EAE. Clinically, Zn-MT-II treatment reduced the severity of EAE symptoms and mortality in a time- and dose-dependent manner. Histopathologically, Zn-MT-II increased reactive astrogliosis and decreased macrophages and T lymphocytes significantly in the CNS. In spleen sections, the number of macrophages both in control and EAE-sensitized rats was reduced by Zn-MT-II, while the number of lymphocytes remained unaltered by Zn-MT-II. Therefore, we suggest that MT-II has peripheral mechanisms of action on macrophages, while T lymphocytes are affected locally in the CNS. During EAE, oxidative stress was decreased by Zn-MT-II, which could contribute to the diminished clinical scores observed. None of the effects caused by Zn-MT-II could be attributable to the zinc content. These results suggest MT-I+II as potentially useful factors for the treatment of EAE/MS

  187. Pouly S, Antel JP, Ladiwala U, Nalbantoglu J, Becher B (2000) Mechanisms of tissue injury in multiple sclerosis: opportunities for neuroprotective therapy. J.Neural Transm.Suppl193-203
    Abstract: Development of neuroprotective therapies for multiple sclerosis is dependent on defining the precise mechanisms whereby immune effector cells and molecules are able to induce relatively selective injury of oligodendrocytes (OLs) and their myelin membranes. The selectivity of this injury could be conferred either by the properties of the effectors or the targets. The former would involve antigen specific recognition by either antibody or T cell receptor of the adaptive immune system. OLs are also susceptible to non antigen restricted injury mediated by components of the innate immune system including macrophages/Microglia and NK cells. Target related selectivity could reflect the expression of death inducing surface receptors (such as Fas or TNFR-1) required for interaction with effector mediators and subsequent intracellular signaling pathways, including the caspase cascade. Development of therapeutic delivery systems, which would reach the site of disease activity within the CNS, will permit the administration of inhibitors either of the cell death pathway or of effector target interaction and opens new avenues to neuroprotection approach

  188. Rottman JB, Slavin AJ, Silva R, Weiner HL, Gerard CG, Hancock WW (2000) Leukocyte recruitment during onset of experimental allergic encephalomyelitis is CCR1 dependent. Eur.J.Immunol. 30:2372-2377
    Abstract: We have shown that macrophages and Microglia present within demyelinating plaques of patients with multiple sclerosis (MS) are immunoreactive for the chemokine receptor CCR1 and its ligand, macrophage inflammatory protein-1alpha. To test the importance of CCR1 to the pathogenesis of MS, we studied the progression of experimental allergic encephalomyelitis (EAE) in CCR1(+/+) vs. CCR1(-/-) mice. After immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide, nearly all CCR1(+/+) mice developed EAE (95% incidence, severity 2.5+/-0.1), whereas CCR1(-/-) mice had less severe disease (55% incidence, p<0.001; severity 1. 2+/-0.2, p<0.001). CCR1(+/+) mice showed elevated brain mRNA for the chemokines immune protein (IP)-10, RANTES and monocyte chemoattractant protein-1 prior to disease onset, whereas only IP-10 mRNA was elevated in CCR1(-/-) mice. Both groups of mice had comparable in vitro lymphocyte proliferation and cytokine production upon stimulation with MOG peptide, and similar cutaneous hypersensitivity responses to 2,4-dinitrofluorobenzene, suggesting that CCR1(-/-) mice were not systemically immunosuppressed. These data demonstrate that deletion of a chemokine receptor is at least partially protective in EAE, and suggest that targeting of CCR1 may be of therapeutic significance clinically

  189. Shoham S, Youdim MB (2000) Iron involvement in neural damage and microgliosis in models of neurodegenerative diseases. Cell Mol.Biol.(Noisy.-le-grand) 46:743-760
    Abstract: In several neurodegenerative diseases, iron accumulates at sites of brain pathology. Since post-mortem examination cannot distinguish whether iron accumulation caused the damage or resulted from damage, it is necessary to manipulate iron in animal and tissue culture models to assess its causal role(s). However, only in models of Parkinson's disease and of global ischemia, iron deprivation (ID) or iron-chelators have been used to protect from damage. In these studies, documentation of microgliosis was not performed even though several lines of evidence converge to suggest that activation of Microglia is an important source of oxidative stress. In the kainate model of epilepsy, we found that ID protected the olfactory cortex, thalamus and hippocampus and attenuated microgliosis, whereas iron supplementation to ID rats increased damage and microgliosis in the above regions. In the hilus of the hippocampal dentate gyrus, even though no cell loss was observed, ID attenuated microgliosis and iron-supplementation increased it. Thus there is a tight relationship between iron and microgliosis. In addition, iron+zinc supplementation dramatically increased damage to hippocampal CA1 whereas zinc supplementation alone had no effect. This study demonstrates an anatomically unique interaction of iron and zinc, which may lead to new insights to neurodegeneration in epilepsy

  190. Simpson J, Rezaie P, Newcombe J, Cuzner ML, Male D, Woodroofe MN (2000) Expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in multiple sclerosis central nervous system tissue. J.Neuroimmunol. 108:192-200
    Abstract: multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) characterised by perivascular inflammatory cell infiltrates and plaques of demyelination. Chemokines have been shown to play an important role in the activation and directional migration of cells to sites of CNS inflammation. The action of chemokines requires the expression of their complementary chemokine receptors by their target cells. We have examined the expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in post-mortem MS CNS tissue using single- and double-labelling immunocytochemistry techniques. Low levels of CCR2, CCR3 and CCR5 were expressed by Microglial cells throughout control CNS tissue. In chronic active MS lesions CCR2, CCR3 and CCR5 were associated with foamy macrophages and activated Microglia. CCR2 and CCR5 were also present on large numbers of infiltrating lymphocytes. A smaller number of CCR3-positive lymphocytes were present, but we also noted CCR3 and CCR5 on astrocytes in five of the 14 cases of MS investigated, particularly associated with processes around vessels and at the glia limitans. Ligands for CCR2 and CCR3 include MCP-1 and MCP-3 which were co-localised around vessels with the infiltrating leukocytes, but were also present in unaffected areas of cortex. The elevated expression of CCR2, CCR3 and CCR5 in the CNS in MS suggests these beta-chemokine receptors and their ligands play a role in the pathogenesis of MS

  191. Stangel M, Joly E, Scolding NJ, Compston DA (2000) Normal polyclonal immunoglobulins ('IVIg') inhibit Microglial phagocytosis in vitro. J.Neuroimmunol. 106:137-144
    Abstract: Phagocytosis removes pathogens and tissue debris during inflammatory reactions, but also plays an important role in autoimmune reactions. The main phagocytes in the central nervous system (CNS) are Microglial cells that are activated during CNS inflammation. In the treatment of inflammatory demyelinating diseases like multiple sclerosis (MS), administration of intravenous immunoglobulins (IVIg) has become a promising immunomodulatory therapy. Although a large number of potential mechanisms for the effects of IVIg has been suggested, the precise mode of action in CNS inflammation is unknown. We assessed the influence of IVIg on phagocytosis and endocytosis in Microglia in vitro. IVIg had little effect on non-specific phagocytosis of latex particles in untreated Microglia, while there was a dose-dependent inhibition in Microglia activated with LPS and IFNgamma. Endocytosis of soluble myelin basic protein (MBP) was downregulated by IVIg in both untreated and activated Microglia. The effect was mediated by an F(ab')(2) preparation of immunoglobulins, suggesting that Fc receptor-mediated phagocytosis is not involved. Intact IVIg, but not F(ab')(2) fragments also suppressed Fc receptor-mediated phagocytosis of opsonised erythrocytes in both untreated and activated Microglia. These results show that IVIg can inhibit the phagocytic activity of Microglia via different mechanisms. Such an effect could contribute to the immunomodulatory capacity of IVIg in inflammatory CNS diseases

  192. Sun D, Tani M, Newman TA, Krivacic K, Phillips M, Chernosky A, Gill P, Wei T, Griswold KJ, Ransohoff RM, Weller RO (2000) Role of chemokines, neuronal projections, and the blood-brain barrier in the enhancement of cerebral EAE following focal brain damage. J.Neuropathol.Exp.Neurol. 59:1031-1043
    Abstract: The role of focal brain damage as a trigger for autoimmune inflammation in multiple sclerosis (MS) is unclear. In this study we examine mechanisms by which experimental autoimmune encephalomyelitis (EAE) is enhanced by focal brain damage. EAE was produced in Lewis rats by footpad inoculation; focal brain damage, in the form of a cortical cryolesion (cryolesion-EAE), was induced 8 days post-inoculation (d.p.i.). The distribution of inflammation and chemokine production in cryolesion-EAE and EAE-only were compared. Inflammation in the brain, measured by immunocytochemistry for T lymphocytes (W3/13) and Microglial activation (MHC class II -OX6), was significantly enhanced in cryolesion-EAE 11-15 d.p.i. (p < 0.01-0.05) but by 20-40 d.p.i., equated with EAE-only. Inflammation in cryolesion-EAE related to breakdown of the blood-brain barrier (BBB) at the site of the cryolesion and also to the corticospinal tracts and thalamus, reflecting the afferent and efferent neuronal connections with the cryolesioned cortex. Semiquantitative RT/PCR dot-blot hybridization assay showed a 6-fold increase in mRNA for specific chemokines in the brain in cryolesion-EAE at 9 d.p.i. (MCP-1) and 11 d.p.i. (MCP-1 and MCP-5) with no significant increase in RANTES, GRO-alpha, or MIP-1alpha. By 14 d.p.i., the levels of MCP-1 and MCP-5 mRNA equated with EAE-only animals. These results suggest that enhancement and location of autoimmune inflammation in the brain following focal cortical injury initially involve chemokines such as the macrophage chemoattractants MCP-1 and MCP-5, and the activities of afferent and efferent neuronal connections with the site of damage. By analogy, similar factors may modulate or reactivate autoimmune inflammation in MS

  193. Tan J, Town T, Mullan M (2000) CD45 inhibits CD40L-induced Microglial activation via negative regulation of the Src/p44/42 MAPK pathway. J.Biol.Chem. 275:37224-37231
    Abstract: It has been reported that ligation of CD40 with CD40 ligand (CD40L) results in Microglial activation as evidenced by p44/42 mitogen-activated protein kinase (MAPK) dependent tumor necrosis factor alpha (TNF-alpha) production. Previous studies have shown that CD45, a functional transmembrane protein-tyrosine phosphatase, is constitutively expressed at moderate levels on Microglial cells and this expression is greatly elevated on activated Microglia. To investigate the possibility that CD45 might modulate CD40L-induced Microglial activation, we treated primary cultured Microglial cells with CD40L and anti-CD45 antibody. Data show that cross-linking of CD45 markedly inhibits CD40L-induced activity of the Src family kinases Lck and Lyn. Further, co-treatment of Microglia with CD40L and anti-CD45 antibody results in significant inhibition of Microglial TNF-alpha production through inhibition of p44/42 MAPK activity, a downstream signaling event resulting from Src activation. Accordingly, primary cultured Microglial cells from mice deficient in CD45 demonstrate hyper-responsiveness to ligation of CD40, as evidenced by increased p44/42 MAPK activation and TNF-alpha production. Taken together, these results show that CD45 plays a novel role in suppressing CD40L-induced Microglial activation via negative regulation of the Src/p44/42 MAPK cascade

  194. Williams KC, Zhao W, Politopoulou G, Male D, Hickey WF (2000) Inhibition of experimental allergic encephalomyelitis with an antibody that recognizes a novel antigen expressed on lymphocytes, endothelial cells, and Microglia. Lab Invest 80:313-326
    Abstract: Experimental allergic encephalomyelitis (EAE) is a frequently employed animal model of the human disease multiple sclerosis. EAE can be induced by adoptive transfer of CD4+ T cells that are specific for central nervous system (CNS) antigens, typically myelin proteins. Although the pathogenic mechanism or mechanisms responsible for the clinical signs and histological changes in EAE and multiple sclerosis are not fully defined, the entry of T lymphocytes and antigen recognition within the CNS are required. The present study describes the participation of a novel cell surface molecule with properties suggesting a role in cell-cell adhesion or co-stimulation, or both, in the development of EAE in the rat. The molecule is defined by the unique monoclonal antibody (mAb) TLD-4A2. The TLD-4A2 antigen is present on resting and activated T lymphocytes, activated CNS endothelial cells, and Microglia. The antigen is normally distributed in many tissues including lymph node, thymus, and spleen, as well as in the inflamed CNS. Both its pattern of tissue distribution and immunoprecipitation and immunoblotting studies suggest that the TLD-4A2 antigen is a novel molecule. Treatment of rats with the purified 4A2 mAb resulted in the inhibition of the clinical signs of EAE and also decreased the number T cells and macrophages accumulating in the CNS parenchyma. TLD-4A2 antibody did not seem to directly interfere with T cell viability in vivo, as demonstrated by the ability to recover and stimulate CD4+ encephalitogenic T cells from cervical lymph nodes of 4A2-treated animals. In vitro, the antibody partially blocked T cell proliferation assays. These data suggest that the TLD-4A2 mAb recognizes a novel molecule expressed on lymphocytes, endothelial cells, and macrophages that may play a role in hematogenous cell traffic and the initiation of CNS inflammation

  195. Zhang GX, Baker CM, Kolson DL, Rostami AM (2000) Chemokines and chemokine receptors in the pathogenesis of multiple sclerosis. Mult.Scler. 6:3-13
    Abstract: In recent years we have seen growing evidence for the role of chemokines in the pathogenesis of several infectious and non-infectious inflammatory CNS disease states, including multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE). An increase in proinflammatory chemokines has been associated with demyelinating lesions and clinical neurological dysfunction in patients with MS; these chemokines could be potential targets for MS therapy. Besides a clearly defined role in mediating leukocyte migration, these and other chemokines may act as immunoregulatory molecules in the driving to Th1/Th2 responses, switch of cytokine profiles, and the induction of tolerance. Since chemokine receptors have now been identified on macrophages, Microglia, astrocytes, and endothelial cells as well as neurons in the CNS, chemokine/receptor interactions may mediate functional responses in a variety of CNS cell types during the course of inflammatory disease states. Therefore, clarification of the roles of chemokines and their receptors in the pathogenesis of EAE and MS will be useful in establishing immunotherapeutic strategies for these neurological autoimmune disorders

  196. Zujovic V, Benavides J, Vige X, Carter C, Taupin V (2000) Fractalkine modulates TNF-alpha secretion and neurotoxicity induced by Microglial activation. Glia 29:305-315
    Abstract: Among the chemokine family, fractalkine shows unusual properties: it exists as a membrane-bound and soluble protein, and both fractalkine and its receptor CX(3)CR1 are expressed predominantly in the central nervous system. In rat cell culture models, the chemokine fractalkine was expressed in neurons and Microglia, but not in astrocytes and its receptor exclusively localized to Microglial cells, where its expression was downregulated by treatment with the bacterial endotoxin (LPS). In Microglial cultures, LPS (10 ng/ml) induced a marked increase in the release of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). The effects of LPS on TNF-alpha secretion were partially blocked (30%) by fractalkine and the effects of fractalkine were reversed by a polyclonal anti-fractalkine antibody. When Microglial-associated fractalkine was neutralized by anti-fractalkine antibody, the LPS response was increased by 80%, suggesting tonic activation of Microglial fractalkine receptors by endogenous fractalkine. The effects of the antibody were antagonized by the addition of fractalkine. LPS-activated Microglia were neurotoxic when added to neuronal hippocampal culture, producing 20% neuronal death, as measured by NeuN-positive cell counting. An anti-fractalkine antibody produced neurotoxic effects of similar magnitude in this co-culture system and also markedly potentiated the neurotoxic effects of LPS-activated Microglia (40% neuronal death). These results suggest that endogenous fractalkine might act tonically as an anti-inflammatory chemokine in cerebral tissue through its ability to control and suppress certain aspects of Microglial activation. These data may have relevance to degenerative conditions such as multiple sclerosis, in which cerebral inflammatory processes may be activated

  197. Balashov KE, Rottman JB, Weiner HL, Hancock WW (1999) CCR5(+) and CXCR3(+) T cells are increased in multiple sclerosis and their ligands MIP-1alpha and IP-10 are expressed in demyelinating brain lesions. Proc.Natl.Acad.Sci.U.S.A 96:6873-6878
    Abstract: multiple sclerosis (MS) is a T cell-dependent chronic inflammatory disease of the central nervous system. The role of chemokines in MS and its different stages is uncertain. Recent data suggest a bias in expression of chemokine receptors by Th1 vs. Th2 cells; human Th1 clones express CXCR3 and CCR5 and Th2 clones express CCR3 and CCR4. Chemokine receptors expressed by Th1 cells may be important in MS, as increased interferon-gamma (IFN-gamma) precedes clinical attacks, and IFN-gamma injection induces disease exacerbations. We found CXCR3(+) T cells increased in blood of relapsing-remitting MS, and both CCR5(+) and CXCR3(+) T cells increased in progressive MS compared with controls. Furthermore, peripheral blood CCR5(+) T cells secreted high levels of IFN-gamma. In the brain, the CCR5 ligand, MIP-1alpha, was strongly associated with Microglia/macrophages, and the CXCR3 ligand, IP-10, was expressed by astrocytes in MS lesions but not unaffected white matter of control or MS subjects. Areas of plaque formation were infiltrated by CCR5-expressing and, to a lesser extent, CXCR3-expressing cells; Interleukin (IL)-18 and IFN-gamma were expressed in demyelinating lesions. No leukocyte expression of CCR3, CCR4, or six other chemokines, or anti-inflammatory cytokines IL-5, IL-10, IL-13, and transforming growth factor-beta was observed. Thus, chemokine receptor expression may be used for immunologic staging of MS and potentially for other chronic autoimmune/inflammatory processes such as rheumatoid arthritis, autoimmune diabetes, or chronic transplant rejection. Furthermore, these results provide a rationale for the use of agents that block CCR5 and/or CXCR3 as a therapeutic approach in the treatment of MS

  198. Becher B, Blain M, Giacomini PS, Antel JP (1999) Inhibition of Th1 polarization by soluble TNF receptor is dependent on antigen-presenting cell-derived IL-12. J.Immunol. 162:684-688
    Abstract: Th1-polarized CD4+ T cells are considered central to the development of a number of target-directed autoimmune disorders including multiple sclerosis. The APC-derived cytokine IL-12 is a potent inducer of Th1 polarization in T cells. Inhibition of IL-12 in vivo blocks the development of experimental allergic encephalomyelitis, the animal model for multiple sclerosis. Based on previous work that suggests that the production of IL-12 by activated human central nervous system-derived Microglia is regulated by autocrine TNF-alpha, we wanted to determine whether inhibition of TNF could induce a reduction of Th1 responses by its impact on systemic APCs. We found that soluble TNFR p75-IgG fusion protein (TNFR:Fc) inhibited production of IFN-gamma by allo-Ag-activated blood-derived human CD4 T cells. We documented reduced IL-12 p70 production by APCs in the MLR. By adding back recombinant IL-12, we could rescue IFN-gamma production, indicating that TNFR:Fc acts on APC-derived IL-12. Consistent with an inhibition of the Th1 polarization, we found a decreased expression of IL-12R-beta2 subunit on the T cells. Furthermore, the capacity of T cells to secrete IFN-gamma upon restimulation when previously treated with TNFR:Fc is impaired, whereas IL-2 secretion was not altered. Our results define a TNF-dependent cytokine network that favors development of Th1 immune responses

  199. Bonetti B, Stegagno C, Cannella B, Rizzuto N, Moretto G, Raine CS (1999) Activation of NF-kappaB and c-jun transcription factors in multiple sclerosis lesions. Implications for oligodendrocyte pathology. Am.J.Pathol. 155:1433-1438
    Abstract: Oligodendrocytes are a major target of the purported autoimmune response in multiple sclerosis (MS) lesions, but little is known about the mechanisms underlying their demise. Despite the expression of proapoptotic receptors, these cells are rarely seen to undergo apoptosis in situ. On the other hand, cytotoxic mediators present in MS lesions, such as tumor necrosis factor-alpha, are known to generate survival signals through the activation of the transcription factors NF-kappaB and c-jun. The aim of this study was to investigate in chronic active and silent MS lesions and control white matter the expression of c-jun, its activating molecule, JNK, as well as NF-kappaB complex and its inhibitor, IkappaB. By immunohistochemistry we found negligible reactivity for these molecules in control white matter and silent MS plaques. In active MS lesions, double-label immunohistochemistry with oligodendrocyte markers showed up-regulation of the nuclear staining for both NF-kappaB and JNK on a large proportion of oligodendrocytes located at the edge of active lesions and on Microglia/macrophages throughout plaques. Oligodendrocytes showed no reactivity for IkappaB, which was predominantly confined to the cytoplasm of Microglia/macrophages. We hypothesize that activation of these transcriptional pathways may be one mechanism accounting for the paucity of oligodendrocyte apoptosis reported in MS

  200. Cannella B, Pitt D, Marchionni M, Raine CS (1999) Neuregulin and erbB receptor expression in normal and diseased human white matter. J.Neuroimmunol. 100:233-242
    Abstract: Human white matter from non-neurologic cases, multiple sclerosis (MS) and other neurologic diseases (OND, inflammatory and non-inflammatory), was subjected to immunocytochemistry and Western blotting for expression of the neuregulin, glial growth factor-2 (GGF2), and its receptors, erbB2, erbB3 and erbB4. GGF2 has previously been shown to have mitogenic effects upon oligodendrocytes in vitro and an enhancing effect upon remyelination in animals with autoimmune demyelination. In all types of human white matter examined, expression of the ligand GGF2 and its three receptors was consistently found on oligodendrocytes, with higher levels being seen in cases of MS. Expression was also seen, albeit at lower levels, on astrocytes and Microglial cells, the latter most commonly in MS and OND. In human lymph node tissue, some lymphocytes were positive for erbB2, erbB3 and erbB4. Western blots confirmed the presence of all three receptors in normal, MS and OND white matter. GGF2 and erbB receptor expression did not correlate with areas of remyelination and reactivity occurred throughout the tissue, with some increase in intensity at the edge of MS lesions. Examination of precursor oligodendrocyte immunoreactivity (with anti-PDGF-Ralpha and NG2), revealed widespread expression throughout both normal and diseased white matter. The presence of GGF2 and its receptors on oligodendrocytes and lymphocytes render this cell type a candidate for functional signaling via this pathway, perhaps in relationship to myelinating activity

  201. Carson MJ, Sutcliffe JG, Campbell IL (1999) Microglia stimulate naive T-cell differentiation without stimulating T-cell proliferation. J.Neurosci.Res. 55:127-134
    Abstract: A major question relevant to the initiation and progression of inflammation and autoimmune processes within the central nervous system (CNS) is whether resident Microglia or only infiltrating macrophage can productively interact with T-cells that enter the CNS either actively through extravasation or passively through defects in the blood brain barrier (BBB). We isolated Microglia and macrophage from the brains of healthy adult mice and transgenic mice that displayed many features of multiple sclerosis and HIV leukoencephalopathy due to the astrocytic expression of interleukin (IL)-3 and compared their antigen-presenting cell (APC) functions. We found that unactivated Microglia isolated from healthy nontransgenic mice and activated Microglia isolated from transgenic siblings are relatively weak stimulators of naive T-cell proliferation compared to macrophage populations. The APC function of activated, but not unactivated, Microglia could be increased by treatment acutely with lipopolysaccharide (LPS)/interferon gamma (IFN-gamma). However, this treatment also induced the apparent production of prostaglandins, which reduced T-cell proliferation when indomethacin was absent from the assay cultures. Strikingly, even in the absence of stimulated T-cell proliferation, both unactivated and activated Microglia stimulated the differentiation of naive T-cells into Th1 effector cells, although neither Microglial population was a more effective inducer than macrophages or splenic APCs. Thus, while Microglia are clearly capable of productively interacting with naive T-cells, macrophages have a more robust APC function

  202. Cross AK, Woodroofe MN (1999) Chemokines induce migration and changes in actin polymerization in adult rat brain Microglia and a human fetal Microglial cell line in vitro. J.Neurosci.Res. 55:17-23
    Abstract: Microglia, the resident macrophages of the central nervous system, are the primary cells to respond to injury in the brain, both in inflammation, e.g., in multiple sclerosis, and trauma. Chemokines are potential mediators of Microglial cell recruitment to sites of injury; thus, the ability of Microglia to migrate in response to a number of chemokines was assessed. The chemokines monocyte chemoattractant protein 1, macrophage inflammatory protein 1alpha, macrophage inflammatory protein 1beta, RANTES (regulated upon activation normal T cell expressed and secreted), interleukin 8, and IP-10 (interferon gamma inducible protein-10), induce migration and changes in the distribution of f-actin in adult rat Microglia and a human Microglial cell line, CHME3, in vitro. Both cell types show a significant migration response, above control levels, to all the chemokines tested in a typical dose-dependent manner. These chemokines also induced a reorganization of the actin cytoskeleton of the cells. This study indicates that chemokines play an important role in the recruitment of Microglia to areas of central nervous system inflammation

  203. Cross AK, Woodroofe MN (1999) Chemokine modulation of matrix metalloproteinase and TIMP production in adult rat brain Microglia and a human Microglial cell line in vitro. Glia 28:183-189
    Abstract: Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes, capable of degrading proteins found in the extracellular matrix. MMPs 2 and 9 are known to be produced by Microglia, the resident macrophages of the central nervous system. The control of the secretion of these proteases and the activation of proenzymes by other proteases such as plasmin, as well as the balance between MMP secretion and the secretion of their natural inhibitors (TIMPs), have an important relevance in the pathogenesis of multiple sclerosis (MS). The in vitro control of MMPs 2 and 9, TIMPs 1 and 2, and urokinase-type plasminogen activator by Microglia was examined in response to a panel of chemokines (chemotactic cytokines), using ELISA and zymography techniques. The chemokines MCP1, MIP1beta, RANTES, IL-8, and Fractalkine were all found significantly to increase the secretion of MMPs and TIMPs by a human foetal Microglial cell line, CHME3, after 24 h stimulation. The chemokines tested, MCP1, MIP1beta, and Fractalkine, were also shown to increase MMP9 secretion by primary isolated rat brain Microglia in vitro. MCP1, MIP1alpha/beta, and RANTES significantly decreased the secretion of uPA into culture supernatants in ELISA experiments. These findings suggest an important potential role for the involvement of chemokines in the breakdown of the blood-brain barrier and also the destruction of myelin basic protein in MS

  204. De Groot CJ, Montagne L, Barten AD, Sminia P, van d, V (1999) Expression of transforming growth factor (TGF)-beta1, -beta2, and -beta3 isoforms and TGF-beta type I and type II receptors in multiple sclerosis lesions and human adult astrocyte cultures. J.Neuropathol.Exp.Neurol. 58:174-187
    Abstract: It is known that the pleiotropic cytokine transforming growth factor beta (TGF-beta) has a regulatory role in the process of tissue repair and remodelling following injury. As reports on these molecules in multiple sclerosis (MS) lesion with different lesional activity are rare, we studied the cellular localization of TGF-beta1, -beta2, and -beta3 isoforms, and TGF-beta receptor type I (TGF-betaR-I) and TGF-betaR-II expression by immunohistochemistry on postmortem brain tissue from MS and normal control cases. To validate the TGF-beta staining results we demonstrated that cultured human adult astrocytes that produce biological active TGF-beta2, and to a lesser extent TGF-beta1, were immunoreactive for all 3 TGF-beta isoforms. Moreover, at mRNA level TGF-beta1 was detected in MS and normal control brain tissue. In normal control brain tissue, TGF-beta isoforms were expressed in ramified Microglia and TGF-beta2, and -beta3 on neuronal cells in the gray matter TGF-betaR-I and TGF-betaR-II expression was found on endothelial cells, astrocytes, Microglia, and neurons. In active demyelinating MS lesions a strong to intense immunoreactivity was detected for all 3 TGF-beta isoforms in perivascular and parenchymal (foamy) macrophages and in hypertrophic astrocytes. Strong immunoreactivity for TGF-betaR-I and TGF-betaR-II was found on macrophages in both parenchymal and perivascular areas and on hypertrophic astrocytes and endothelial cells in active demyelinating MS lesions. In chronic active and inactive MS lesions, all 3 TGF-beta isoforms and their receptors were strongly expressed in hypertrophic astrocytes. Our findings strongly suggest that the expression of the various TGF-beta isoforms and their receptor types found in MS lesions with different cellular activity participate in reactive processes leading to the formation of chronic MS lesions

  205. De Keyser J, Wilczak N, Leta R, Streetland C (1999) Astrocytes in multiple sclerosis lack beta-2 adrenergic receptors. Neurology 53:1628-1633
    Abstract: BACKGROUND: In MS, T cells reactive to myelin proteins can cross the blood-brain barrier and release proinflammatory cytokines, such as interferon gamma. These can induce glial cells to express class II major histocompatibility complex (MHC) molecules, which are required to present myelin antigens to the T cells in order to mount a proper autoimmune response. Both Microglia and astrocytes can function as antigen-presenting cells. In contrast to Microglia, endogenous suppressors, including norepinephrine, regulate astrocytic class II MHC expression. The effects of norepinephrine are mediated through activation of P2 adrenergic receptors. OBJECTIVE: To investigate P, adrenergic receptors in astrocytes in MS. METHODS: Immunocytochemical techniques were applied in postmortem brain tissue from 10 patients with MS, three patients with a cerebral infarction, and six controls, and in spinal cord from three patients with ALS. RESULTS: beta2 adrenergic receptors were visualized on astrocytes in white matter of controls, and they were prominently expressed in reactive astrocytes at the boundary of cerebral infarctions and in the lateral corticospinal tract in ALS. In MS, beta2 adrenergic receptors could neither be visualized on astrocytes in normal-appearing white matter nor in reactive astrocytes in chronic active and inactive plaques, whereas they were normally present on neurons. MHC class II-positive astrocytes were only visualized in chronic active plaques. CONCLUSIONS: Because astrocytic beta2 adrenergic receptors are involved in suppressing inducibility of MHC class II molecules, we suggest that their lack of expression may play an important role in the induction or perpetuation of autoimmune reactions in MS

  206. Di Bello IC, Dawson MR, Levine JM, Reynolds R (1999) Generation of oligodendroglial progenitors in acute inflammatory demyelinating lesions of the rat brain stem is associated with demyelination rather than inflammation. J.Neurocytol. 28:365-381
    Abstract: Remyelination is an extremely efficient process in the adult rodent central nervous system yet the source of new oligodendroglia that appear following primary demyelination is still subject to much debate. Using a reliable marker for oligodendroglial progenitor cells in vivo, the NG2 chondroitin sulphate proteoglycan, we have evaluated the response of endogenous NG2(+) cells in the adult rat brain stem and cerebellum to inflammatory demyelinating lesions in an experimentally induced animal model of multiple sclerosis (MS), antibody augmented experimental allergic encephalomyelitis (ADEAE). We have manipulated T-cell mediated EAE in Lewis rats by injecting in addition, either anti-myelin/oligodendroglial glycoprotein (MOG) antibodies to induce inflammatory demyelination, or non-specific mouse immunoglobulins to induce an inflammatory response without demyelination. We have examined the relationship of NG2(+) progenitor cells to Microglia (OX-42(+)), astrocytes (GFAP(+)) and mature oligodendroglia (CNP(+)), in the normal and demyelinated CNS. In the normal CNS NG2-expressing cells are closely intermingled with other glia but represent a distinct cell population. A prominent inflammatory response, identified by the presence of large perivascular and periventricular accumulations of reactive OX42(+) macrophages/Microglia, occurred in animals with ADEAE at 7-9 days post injection (DPI), coinciding with severe clinical symptoms. In animals injected with anti-MOG antibodies inflammation was followed by the appearance of large areas of demyelination at 11-14 DPI, at which point the animals had recovered clinically. The response of NG2(+) cells was different depending on whether the inflammation was accompanied by demyelination. In the presence of inflammation, NG2(+) cells responded by an increase in immunoreactivity and an alteration in their morphology, exhibiting enlarged cell bodies and an increased number of intensely stained processes. In areas of demyelination NG2(+) cells had fewer intensely stained processes reminiscent of progenitor cells seen during development. Quantitative analysis revealed a 3-fold increase in the number of NG2(+) cells in demyelinated lesions at 11 DPI, whereas no change was observed in areas of inflammation in the absence of demyelination. Mitotic figures were only seen in NG2(+) cells in areas of demyelination. NG2(+) cell numbers appeared to return to control levels following remyelination. These results suggest that endogenous oligodendroglial progenitors divide and/or migrate, in response to signals triggered by demyelinating rather than inflammatory events, to generate a large progenitor population sufficient to promote the rapid and successful remyelination observed in this model

  207. Dowling P, Ming X, Raval S, Husar W, Casaccia-Bonnefil P, Chao M, Cook S, Blumberg B (1999) Up-regulated p75NTR neurotrophin receptor on glial cells in MS plaques. Neurology 53:1676-1682
    Abstract: OBJECTIVE: To investigate the expression of the neurotrophin receptor p75NTR on glial cells within MS plaques. BACKGROUND: In recent studies on the pathogenesis of MS white matter plaques, we found large populations of inflammatory and resident glial cells, including oligodendrocytes undergoing cell death, and identified increased expression of Fas receptor and ligand death pathway signaling molecules on the same glial cell types. In another study, the p75NTR was shown to induce apoptotic death of maturing oligodendrocytes when exposed to NGF in vitro. METHODS: We used immunohistochemistry and in situ reverse-transcription PCR to detect p75NTR expression on inflammatory and resident glial cells in MS plaques and used TUNEL staining for fragmented DNA to detect cell death. RESULTS: Up-regulated p75NTR messenger RNA and protein were demonstrated in both oligodendrocytes and Microglia/macrophages in MS plaques but not in control white matter. However, only a fraction of p75NTR expressing oligodendrocytes was also stained by TUNEL. CONCLUSIONS: Glial cell expression of p75NTR receptor is up-regulated during MS plaque formation. The exact role of this receptor in glial cell death and/or survival in MS remains to be elucidated

  208. Fawcett JW, Asher RA (1999) The glial scar and central nervous system repair. Brain Res.Bull. 49:377-391
    Abstract: Damage to the central nervous system (CNS) results in a glial reaction, leading eventually to the formation of a glial scar. In this environment, axon regeneration fails, and remyelination may also be unsuccessful. The glial reaction to injury recruits Microglia, oligodendrocyte precursors, meningeal cells, astrocytes and stem cells. Damaged CNS also contains oligodendrocytes and myelin debris. Most of these cell types produce molecules that have been shown to be inhibitory to axon regeneration. Oligodendrocytes produce NI250, myelin-associated glycoprotein (MAG), and tenascin-R, oligodendrocyte precursors produce NG2 DSD-1/phosphacan and versican, astrocytes produce tenascin, brevican, and neurocan, and can be stimulated to produce NG2, meningeal cells produce NG2 and other proteoglycans, and activated Microglia produce free radicals, nitric oxide, and arachidonic acid derivatives. Many of these molecules must participate in rendering the damaged CNS inhibitory for axon regeneration. Demyelinated plaques in multiple sclerosis consists mostly of scar-type astrocytes and naked axons. The extent to which the astrocytosis is responsible for blocking remyelination is not established, but astrocytes inhibit the migration of both oligodendrocyte precursors and Schwann cells which must restrict their access to demyelinated axons

  209. Gonzalez-Scarano F, Baltuch G (1999) Microglia as mediators of inflammatory and degenerative diseases. Annu.Rev.Neurosci. 22:219-240
    Abstract: Microglia are the principal immune cells in the central nervous system (CNS) and have a critical role in host defense against invading microorganisms and neoplastic cells. However, as with immune cells in other organs, Microglia may play a dual role, amplifying the effects of inflammation and mediating cellular degeneration as well as protecting the CNS. In entities like human immunodeficiency virus (HIV) infection of the nervous system, Microglia are also critical to viral persistence. In this review we discuss the role of Microglia in three diseases in which their activity is at least partially deleterious: HIV, multiple sclerosis, and Alzheimer's disease

  210. Gveric D, Cuzner ML, Newcombe J (1999) Insulin-like growth factors and binding proteins in multiple sclerosis plaques. Neuropathol.Appl.Neurobiol. 25:215-225
    Abstract: Insulin-like growth factors (IGFs) play an important role in development and myelination in the central nervous system (CNS) as well as in the proliferation and differentiation of cells of the immune system. To assess the influence of this growth factor family on demyelination and repair in multiple sclerosis (MS), the expression of IGF-I, IGF-II, insulin, IGF binding proteins (IGFBP) 1-3 and IGF-I receptor (IGF-IR) in CNS tissue from MS and normal control cases was studied by immunocytochemistry. In active MS lesions, the expression of IGF-I, insulin and IGFBP1 was detected in hypertrophic astrocytes while that of IGF-II and IGFBP2 and 3 was confined to foamy macrophages within lesions and activated Microglia in adjacent white matter. IGF-IR, the major IGF receptor, was immunolocalized in macrophages and an astrocyte subpopulation in plaques. Oligodendrocytes in normal-appearing white matter expressed only IGFBP1, not IGFs or IGF-IR. As the remyelinating capacity of oligodendrocytes could be impaired owing to the absence of IGF-IR, the prevailing role of IGFs in inflammatory demyelination may be to promote phagocytosis of myelin and astrogliosis

  211. Hafler DA (1999) The distinction blurs between an autoimmune versus microbial hypothesis in multiple sclerosis. J.Clin.Invest 104:527-529

  212. Hesselgesser J, Horuk R (1999) Chemokine and chemokine receptor expression in the central nervous system. J.Neurovirol. 5:13-26
    Abstract: A decade ago several new cytokines were described that orchestrated the activation and migration of immune cells. These newly described cytokines, of which interleukin-8 (IL-8) was a representative member, defined a novel group of molecules called chemokines (chemotactic cytokines). Chemokines are low molecular weight, 8-12 kDa, basic proteins that have been classified into four distinct families, CXC, CC, C and CX3C, based on the position of their first two conserved cysteine residues. The expression and biological function of chemokines along with their cognate receptors have been well described on various subsets of leukocytes. Only more recently have these molecules been described on various cells within the central nervous system. These pro-inflammatory proteins have been implicated in a variety of diseases within the central nervous system from multiple sclerosis to AIDS dementia. While chemokines are likely to enhance the evolution of central nervous system inflammatory disorders they also have other roles in normal brain function and development. This review summarizes the role of chemokines and their receptors in the normal and pathophysiological brain

  213. Hickey WF (1999) The pathology of multiple sclerosis: a historical perspective. J.Neuroimmunol. 98:37-44
    Abstract: In the century and a half since multiple sclerosis (MS) was first recognized, the pathology of the condition has been defined with increasing detail. From the recognition and definition of MS as a clinical phenomenon, studies of the diseased brain tissue have progressed in a manner dependent on the science of the time. Through multiple generations, the increasingly detailed analysis of the MS lesion itself has lead to an increasingly sophisticated understanding of a complex, apparently diverse, immunopathological process. During this evolution, many hypotheses concerning the pathogenesis of MS have been overturned, and the interpretation of some clearly delineated gross and histological findings have been reversed. This review plots the progress and highlights current theories and emerging concepts regarding one of the most enigmatic of neurological diseases

  214. Howard LM, Miga AJ, Vanderlugt CL, Dal Canto MC, Laman JD, Noelle RJ, Miller SD (1999) Mechanisms of immunotherapeutic intervention by anti-CD40L (CD154) antibody in an animal model of multiple sclerosis. J.Clin.Invest 103:281-290
    Abstract: Relapsing experimental autoimmune encephalomyelitis (R-EAE) in the SJL mouse is a Th1-mediated autoimmune demyelinating disease model for human multiple sclerosis and is characterized by infiltration of the central nervous system (CNS) by Th1 cells and macrophages. Disease relapses are mediated by T cells specific for endogenous myelin epitopes released during acute disease, reflecting a critical role for epitope spreading in the perpetuation of chronic central CNS pathology. We asked whether blockade of the CD40-CD154 (CD40L) costimulatory pathway could suppress relapses in mice with established R-EAE. Anti-CD154 antibody treatment at either the peak of acute disease or during remission effectively blocked clinical disease progression and CNS inflammation. This treatment blocked Th1 differentiation and effector function rather than expansion of myelin-specific T cells. Although T-cell proliferation and production of interleukin (IL)-2, IL-4, IL-5, and IL-10 were normal, antibody treatment severely inhibited interferon-gamma production, myelin peptide-specific delayed-type hypersensitivity responses, and induction of encephalitogenic effector cells. Anti-CD154 antibody treatment also impaired the expression of clinical disease in adoptive recipients of encephalitogenic T cells, suggesting that CD40-CD154 interactions may be involved in directing the CNS migration of these cells and/or in their effector ability to activate CNS macrophages/Microglia. Thus, blockade of CD154-CD40 interactions is a promising immunotherapeutic strategy for treatment of ongoing T cell-mediated autoimmune diseases

  215. Jiang H, Bielekova B, Okazaki H, Clarence-Smith K, Johnson KP, Bergey G, Martin R, Dhib-Jalbut S (1999) The effect of vesnarinone on TNF alpha production in human peripheral blood mononuclear cells and Microglia: a preclinical study for the treatment of multiple sclerosis. J.Neuroimmunol. 97:134-145
    Abstract: Vesnarinone (OPC-8212) is a synthetic quinolinone derivative with inotropic and immunomodulatory effects. Vesnarinone has been shown to inhibit tumor necrosis factor-alpha (TNF alpha) produced by mitogen stimulated macrophages, and to inhibit phosphodiesterase (PDE) type III in cardiac muscle. TNF alpha and interferon-gamma (IFNgamma) have been implicated in the pathogenesis of autoimmune diseases, and both cytokines are targets for therapeutic intervention. IFNgamma can enhance autoimmune disease through direct effects, and indirectly by priming macrophages to produce TNF alpha. In this study, we demonstrate that while vesnarinone enhances basal TNF alpha levels, it inhibits TNF alpha production in peripheral blood mononuclear cells from multiple sclerosis (MS) patients and healthy donors stimulated with lipopolysaccharide (LPS) or primed with IFNgamma and stimulated with suboptimal doses of LPS. In addition, vesnarinone inhibited TNF alpha production in primary adult human Microglial cultures. However, in contrast to rolipram, another TNF alpha inhibiting agent, vesnarinone failed to inhibit TNF alpha production by myelin basic protein specific T-cell lines. As oral TNF inhibitors are currently being considered in the USA for clinical application in MS, the implications of our findings on the development of vesnarinone for treatment of MS are discussed

  216. Katz-Levy Y, Neville KL, Girvin AM, Vanderlugt CL, Pope JG, Tan LJ, Miller SD (1999) Endogenous presentation of self myelin epitopes by CNS-resident APCs in Theiler's virus-infected mice. J.Clin.Invest 104:599-610
    Abstract: The mechanisms underlying the initiation of virus-induced autoimmune disease are not well understood. Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), a mouse model of multiple sclerosis, is initiated by TMEV-specific CD4(+) T cells targeting virally infected central nervous system-resident (CNS-resident) antigen-presenting cells (APCs), leading to chronic activation of myelin epitope-specific CD4(+) T cells via epitope spreading. Here we show that F4/80(+), I-A(s+), CD45(+) macrophages/Microglia isolated from the CNS of TMEV-infected SJL mice have the ability to endogenously process and present virus epitopes at both acute and chronic stages of the disease. Relevant to the initiation of virus-induced autoimmune disease, only CNS APCs isolated from TMEV-infected mice with preexisting myelin damage, not those isolated from naive mice or mice with acute disease, were able to endogenously present a variety of proteolipid protein epitopes to specific Th1 lines. These results offer a mechanism by which localized virus-induced, T cell-mediated inflammatory myelin destruction leads to the recruitment/activation of CNS-resident APCs that can process and present endogenous self epitopes to autoantigen-specific T cells, and thus provide a mechanistic basis by which epitope spreading occurs

  217. Lake J, Weller RO, Phillips MJ, Needham M (1999) Lymphocyte targeting of the brain in adoptive transfer cryolesion-EAE. J.Pathol. 187:259-265
    Abstract: Lymphocyte infiltration and Microglial activation in experimental autoimmune encephalomyelitis (EAE) are mainly centred on the spinal cord. However, a cryolesion to one cerebral hemisphere (cryolesion-EAE) induces six-fold enhancement of EAE in the cerebral hemispheres and removal of the cervical lymph nodes reduces such enhancement by 40 per cent. This study tests the hypothesis that lymphocytes from donor rats with cryolesion-EAE will selectively target the brain rather than the spinal cord when transferred to naive recipients. Acute EAE was induced in 15 Lewis rats (donors); ten donors received a cryolesion to the left cerebral hemisphere 8 days post-inoculation of antigen and adjuvant. Five rats with EAE received no cryolesion. Lymphocytes from cryolesion-EAE donors or from EAE-only donors were cultured for 72 h in medium containing myelin basic protein and then injected into a total of 21 naive recipients, which were killed 8 days later. The severity of EAE in brains and spinal cords was assessed in immunocytochemically stained sections by quantifying the number of vessels showing lymphocyte cuffs (W3/13 antibody) and the level of MHC class II antigen expression by Microglia (OX6 antibody). When compared with recipients of EAE-only donor lymphocytes, the severity of cerebral EAE was increased 2- to 2.6-fold in the recipients of crylesion-EAE donor lymphocytes (p < 0.01); EAE in the spinal cord was reduced. These results suggest that lymphocytes from cryolesion-EAE donors preferentially target the brain in recipient animals in preference to the spinal cord. By analogy with cryolesion-EAE, focal central nervous system (CNS) damage with drainage of auto-antigens to regional lymph nodes in man may play a role in determining the site and timing of initial and recurrent multiple sclerosis lesions

  218. Lavi E, Das SJ, Weiss SR (1999) Cellular reservoirs for coronavirus infection of the brain in beta2-microglobulin knockout mice. Pathobiology 67:75-83
    Abstract: Mouse hepatitis virus (MHV) A59 infection which causes acute encephalitis, hepatitis, and chronic demyelination, is one of the experimental models for multiple sclerosis. Previous studies showed that lethal infection of beta2-microglobulin 'knockout' (beta2M(-/-)) mice required 500-fold less virus and viral clearance was delayed as compared to infection of immunocompetent C57Bl/6 (B6) mice. To investigate the mechanism of the increased susceptibility of beta2M(-/-) mice to MHV-A59, we studied organ pathology and the distribution of viral antigen and RNA during acute and chronic infection. A59-infected beta2M(-/-) mice were more susceptible to acute encephalitis and hepatitis, but did not have increased susceptibility to demyelination. Viral antigen and RNA distribution in the brain was increased in Microglia, lymphocytes, and small vessel endothelial cells while the distribution in neurons and glia was similar in beta2M(-/-) mice and B6 mice. Acute hepatitis and thymus cortical hypoplasia in beta2M(-/-) mice were delayed in onset but pathologic changes in these organs were similar to those in B6 mice. The low rate of demyelination in beta2M(-/-) mice was consistent with the low dose of the virus given. A less neurotropic virus MHV-2, caused increased parenchymal inflammation in beta2M(-/-) mice, but without demyelination. Thus, CD8+ cells were important for viral clearance from endothelial cells, Microglia and inflammatory cells, but not from neuronal and glial cells. In addition, CD8+ cells played a role in preventing the spread of encephalitis

  219. Lee SJ, Benveniste EN (1999) Adhesion molecule expression and regulation on cells of the central nervous system. J.Neuroimmunol. 98:77-88
    Abstract: Cellular adhesion molecules were initially defined as cell surface structures mediating cell-cell and cell-extracellular matrix (ECM) interactions. Adhesion molecules involved in immune responses have been classified into three families according to their structure: selectins, immunoglobulin (Ig) superfamily, and integrins. It has been well documented that adhesion molecules of these family members (E-selectin, ICAM-1, and VCAM-1) are expressed on brain microvessel endothelial cells in active lesions of multiple sclerosis (MS) brain. In addition, accumulating data show that glial cells can express some of these adhesion molecules upon activation: astrocytes can express ICAM-1, VCAM-1, and E-selectin, and Microglia express ICAM-1 and VCAM-1. In vitro studies show that these adhesion molecules are actively regulated by several cytokines which have relevance to MS or experimental autoimmune encephalomyelitis (EAE). In addition, soluble forms of adhesion molecules have been found in the serum and cerebrospinal fluid (CSF) of MS patients, and may be useful diagnostically. Experimental therapy of EAE using antibodies against several adhesion molecules clearly shows that adhesion molecules are critical for the pathogenesis of EAE. Thus far, the function of adhesion molecule expression on brain endothelial and glial cells has not been clearly elucidated. Studies on the possible role of adhesion molecules on brain endothelial and glial cells will be helpful in understanding their involvement in immune responses in the central nervous system (CNS)

  220. Parra B, Hinton DR, Marten NW, Bergmann CC, Lin MT, Yang CS, Stohlman SA (1999) IFN-gamma is required for viral clearance from central nervous system oligodendroglia. J.Immunol. 162:1641-1647
    Abstract: Infection of the central nervous system (CNS) by the JHM strain of mouse hepatitis virus (JHMV) is a rodent model of the human demyelinating disease multiple sclerosis. The inability of effective host immune responses to eliminate virus from the CNS results in a chronic infection associated with ongoing recurrent demyelination. JHMV infects a variety of CNS cell types during the acute phase of infection including ependymal cells, astrocytes, Microglia, oligodendroglia, and rarely in neurons. Replication within the majority of CNS cell types is controlled by perforin-dependent virus-specific CTL. However, inhibition of viral replication in oligodendroglia occurs via a perforin-independent mechanism(s). The potential role for IFN-gamma as mediator controlling JHMV replication in oligodendroglia was examined in mice deficient in IFN-gamma secretion (IFN-gamma0/0 mice). IFN-gamma0/0 mice exhibited increased clinical symptoms and mortality associated with persistent virus, demonstrating an inability to control replication. Neither antiviral Ab nor CTL responses were diminished in the absence of IFN-gamma, although increased IgG1 was detected in IFN-gamma0/0 mice. Increased virus Ag in the absence of IFN-gamma localized almost exclusively to oligodendroglia and was associated with increased CD8+ T cells localized within white matter. These data suggest that although perforin-dependent CTL control virus replication within astrocytes and Microglia, which constitute the majority of infected CNS cells, IFN-gamma is critical for control of viral replication in oligodendroglia. Therefore, different mechanisms are used by the host defenses to control virus replication within the CNS, dependent upon the phenotype of the targets of virus replication

  221. Persidsky Y (1999) Model systems for studies of leukocyte migration across the blood - brain barrier. J.Neurovirol. 5:579-590
    Abstract: The blood - brain barrier (BBB) plays a crucial role in central nervous system (CNS) homeostasis. Serving as the brain's protective shield it regulates soluble factor and cellular exchanges from blood to brain. Critical to its function, the BBB is composed of brain microvascular endothelial cells (BMVEC), a collagen matrix, and astrocytes. Astrocytic endfeet surround the BMVEC abluminal surface and influence the 'tightness' and trafficking role of the barrier. In neurodegenerative disorders (for example stroke, multiple sclerosis and HIV encephalitis) the BBB becomes compromised. This is, in part, immune mediated. An accumulating body of evidence demonstrates that the cellular components of the BBB are themselves immunocompetent. Perivascular cells (astrocytes, macrophages and Microglial cells) and BMVEC produce inflammatory factors that affect BBB permeability and expression of adhesion molecules. These affect cell trafficking into the CNS. Leukocyte BBB migration can be influenced by cytokines and chemokines produced by glia. Astrocytes and macrophages secrete a multitude of factors that affect brain immune responses. Interactions between BMVEC, leukocytes and/or glia, immunological activation and noxious (infectious, toxic and immune-mediated) brain insults all appear to play important roles in this BBB cell trafficking. New information gained into the mechanisms of leukocyte-brain penetration may provide novel insights in the pathogenesis and treatment strategies of neurodegenerative disorders

  222. Phillips LM, Simon PJ, Lampson LA (1999) Site-specific immune regulation in the brain: differential modulation of major histocompatibility complex (MHC) proteins in brainstem vs. hippocampus. J.Comp Neurol. 405:322-333
    Abstract: Although neurotransmitters and neuropeptides are known to affect immune function in vitro and in non-neural tissues, little is known about how the local mix of neurochemicals affects immune function in the brain. Here, we study local modulation of the class II major histocompatibility complex (MHC) proteins, which present antigen to T cells in a key pathway for cell-mediated immune activity. Two sites that are well-separated anatomically and have very different neuroregulatory environments, the brainstem and hippocampus, were compared. The class II-upregulating cytokine, gamma interferon (IFN-gamma, 0.1 to 10,000 U/site), was injected stereotaxically into the hippocampus and contralateral brainstem of adult Charles-derived Fischer rats. Four days later, monoclonal antibody staining was used to detect class II MHC proteins on cryostat sections, followed by computer-assisted image analysis. As compared to hippocampus, the brainstem showed enhanced class II expression at lower IFN-gamma doses, and reached a higher plateau. Site-specific class II modulation was also seen within the layers of the hippocampus, and among other brain sites. Injection of marker protein to visualize the spread of injected protein, plus injection of IFN-gamma into alternative sites, suggested that preferential flow cannot explain all of the site-specific effects. We suggest that the local neuroregulatory environment and/or intrinsic differences among target Microglia are likely to play a role. Implications for the distribution of pathological changes, such as multiple sclerosis plaques, and for local immunotherapy are discussed

  223. Popko B, Baerwald KD (1999) Oligodendroglial response to the immune cytokine interferon gamma. Neurochem.Res. 24:331-338
    Abstract: In the human demyelinating disorder multiple sclerosis, and its animal model experimental allergic encephalomyelitis, there is a breakdown of the blood-brain barrier and an infiltration of immune cells into the CNS. Infiltrating T lymphocytes and macrophages are believed to be key mediators of the disease process. Considerable circumstantial and experimental evidence has suggested that the pleiotropic cytokine interferon gamma (IFN-gamma), which is exclusively expressed by T cells and natural killer cells, is a deleterious component of the immune response in these disorders. When experimentally introduced into the CNS IFN-gamma promotes many of the pathological changes that occur in immune-mediated demyelinating disorders. In vitro, this cytokine elicits a number of effects on oligodendrocytes, including cell death. The harmful actions of IFN-gamma on CNS myelin are likely mediated through direct effects on the myelinating cells, as well as through the activation of macrophages and Microglia. In this review we summarize relevant studies concerning the action of IFN-gamma in demyelinating disorders and discuss possible mechanisms for the observed effects

  224. Reynolds WF, Rhees J, Maciejewski D, Paladino T, Sieburg H, Maki RA, Masliah E (1999) Myeloperoxidase polymorphism is associated with gender specific risk for Alzheimer's disease. Exp.Neurol. 155:31-41
    Abstract: Myeloperoxidase (MPO) is a myeloid-specific enzyme that generates hypochlorous acid and other reactive oxygen species. MPO is present at high levels in circulating neutrophils and monocytes but is not detectable in Microglia, brain-specific macrophages, in normal brain tissue. However, an earlier study indicated that MPO is present in macrophage-Microglia at multiple sclerosis lesions, suggesting that reactivation of MPO gene expression may play a role in neurodegenerative diseases involving macrophage-Microglia. In the present study, MPO is shown to colocalize with amyloid beta (Abeta) in senile plaques in cerebral cortex sections from Alzheimer's disease (AD) brain tissue. Microglia costaining for MPO and CD68 are closely associated with plaques, suggesting that plaque components induce MPO expression in Microglia. In support of this interpretation, treatment of rodent Microglia with aggregated Abeta(1-42) was shown to induce MPO mRNA expression. Also, the ApoE4 allele, the major AD risk factor associated with increased Abeta deposition, was shown to correlate with increased MPO deposition in plaques (P = 0.01, ANOVA). Finally, a genetic polymorphism links MPO expression to Alzheimer's risk, in that a higher expressing SpSp MPO genotype was associated with increased incidence of AD in females, and decreased incidence in males (P = 0.006). These findings suggest that the MPO polymorphism is a gender-specific risk factor for Alzheimer's disease

  225. Satoh J, Kurohara K, Yukitake M, Kuroda Y (1999) The 14-3-3 protein detectable in the cerebrospinal fluid of patients with prion-unrelated neurological diseases is expressed constitutively in neurons and glial cells in culture. Eur.Neurol. 41:216-225
    Abstract: The 14-3-3 protein belongs to a family of 30-kD proteins originally identified by two-dimensional analysis of brain protein extracts. Recently, the detection of the 14-3-3 protein in the cerebrospinal fluid (CSF) is utilized as a highly reliable test for the premortem diagnosis of prion diseases such as Creutzfeldt-Jakob disease. For the initial step, to clarify the biological implication of the CSF 14-3-3 protein in these diseases, its expression was investigated in neural tissues and cultures and CSF samples from patients with a variety of neurological diseases by Western blot analysis and immunocytochemistry. The constitutive expression of the 14-3-3 protein was identified in all neural and nonneural tissues examined. It was expressed in all neurons, astrocytes, oligodendrocytes, and Microglia in culture with its location in both cytoplasmic and nuclear regions. The 14-3-3 protein was detected in the CSF of 8 out of 71 patients, including 1 Gerstmann-Straussler-Scheinker disease patient and 7 patients with prion-unrelated neurological diseases, such as meningoencephalitis of viral, bacterial, or tuberculous origin, multiple sclerosis, and mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. These results suggest that the 14-3-3 protein expressed constitutively at substantial levels in both neurons and glial cells might be released into the CSF as a disease-nonspecific consequence of the extensive brain damage and indicate that the analysis of the 14-3-3 protein in the CSF is not useful as a screening test for prion diseases

  226. Smith KJ, Kapoor R, Felts PA (1999) Demyelination: the role of reactive oxygen and nitrogen species. Brain Pathol. 9:69-92
    Abstract: This review summarises the role that reactive oxygen and nitrogen species play in demyelination, such as that occurring in the inflammatory demyelinating disorders multiple sclerosis and Guillain-Barre syndrome. The concentrations of reactive oxygen and nitrogen species (e.g. superoxide, nitric oxide and peroxynitrite) can increase dramatically under conditions such as inflammation, and this can overwhelm the inherent antioxidant defences within lesions. Such oxidative and/or nitrative stress can damage the lipids, proteins and nucleic acids of cells and mitochondria, potentially causing cell death. Oligodendrocytes are more sensitive to oxidative and nitrative stress in vitro than are astrocytes and Microglia, seemingly due to a diminished capacity for antioxidant defence, and the presence of raised risk factors, including a high iron content. Oxidative and nitrative stress might therefore result in vivo in selective oligodendrocyte death, and thereby demyelination. The reactive species may also damage the myelin sheath, promoting its attack by macrophages. Damage can occur directly by lipid peroxidation, and indirectly by the activation of proteases and phospholipase A2. Evidence for the existence of oxidative and nitrative stress within inflammatory demyelinating lesions includes the presence of both lipid and protein peroxides, and nitrotyrosine (a marker for peroxynitrite formation). The neurological deficit resulting from experimental autoimmune demyelinating disease has generally been reduced by trial therapies intended to diminish the concentration of reactive oxygen species. However, therapies aimed at diminishing reactive nitrogen species have had a more variable outcome, sometimes exacerbating disease

  227. Smith ME (1999) Phagocytosis of myelin in demyelinative disease: a review. Neurochem.Res. 24:261-268
    Abstract: In the cell-mediated demyelinating diseases such as experimental allergic encephalomyelitis and multiple sclerosis, as well as their peripheral nerve counterparts, the phagocytic cells are the agent of myelin destruction. Both resident Microglia and peripheral macrophages invading the nervous system have been shown to phagocytize myelin, although Microglia appear to be more active, especially at early stages of disease. Several different receptors on these cells have been implicated as myelin receptors, with the Fc- and complement receptors receiving the most attention. Other receptors, especially the macrophage scavenger receptor with its broad specificity deserves further exploration, especially in view of its affinity for phosphatidylserine, which becomes externalized with membrane disruption. Evidence is shown for cytokine regulation of phagocytic activity in both macrophages and Microglia. Further investigation of the pathways of cytokine action on myelin phagocytosis through signal transduction molecules will be important for a further understanding of the events leading to myelin destruction in demyelinating diseases

  228. Sorensen TL, Tani M, Jensen J, Pierce V, Lucchinetti C, Folcik VA, Qin S, Rottman J, Sellebjerg F, Strieter RM, Frederiksen JL, Ransohoff RM (1999) Expression of specific chemokines and chemokine receptors in the central nervous system of multiple sclerosis patients. J.Clin.Invest 103:807-815
    Abstract: Chemokines direct tissue invasion by specific leukocyte populations. Thus, chemokines may play a role in multiple sclerosis (MS), an idiopathic disorder in which the central nervous system (CNS) inflammatory reaction is largely restricted to mononuclear phagocytes and T cells. We asked whether specific chemokines were expressed in the CNS during acute demyelinating events by analyzing cerebrospinal fluid (CSF), whose composition reflects the CNS extracellular space. During MS attacks, we found elevated CSF levels of three chemokines that act toward T cells and mononuclear phagocytes: interferon-gamma-inducible protein of 10 kDa (IP-10); monokine induced by interferon-gamma (Mig); and regulated on activation, normal T-cell expressed and secreted (RANTES). We then investigated whether specific chemokine receptors were expressed by infiltrating cells in demyelinating MS brain lesions and in CSF. CXCR3, an IP-10/Mig receptor, was expressed on lymphocytic cells in virtually every perivascular inflammatory infiltrate in active MS lesions. CCR5, a RANTES receptor, was detected on lymphocytic cells, macrophages, and Microglia in actively demyelinating MS brain lesions. Compared with circulating T cells, CSF T cells were significantly enriched for cells expressing CXCR3 or CCR5. Our results imply pathogenic roles for specific chemokine-chemokine receptor interactions in MS and suggest new molecular targets for therapeutic intervention

  229. Stanislaus R, Pahan K, Singh AK, Singh I (1999) Amelioration of experimental allergic encephalomyelitis in Lewis rats by lovastatin. Neurosci.Lett. 269:71-74
    Abstract: Proinflammatory cytokines and inducible nitric oxide synthase (iNOS) are involved in the pathogenesis of experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). We have previously reported that lovastatin (Pahan, K., Sheikh., F.G., Namboodiri, A. and Singh, I., Lovastatin and Phenylacetate inhibit the induction of nitric oxide synthase and cytokines in rat primary astrocytes, Microglia and macrophages. J. Clin. Invest., 100 (1997) 2671-2679.), an inhibitor of the mevalonate pathway, inhibits the expression of iNOS and proinflammatory cytokines in rat primary glial cells (astroglia and Microglia) and macrophages. The present study underlines the therapeutic importance of lovastatin in ameliorating the neuroinflammatory disease process in the central nervous system of EAE rats. Immunohistochemical results show a higher degree of expression of iNOS, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in brains of rats with acute monophasic EAE relative to the control animals. Administration of lovastatin inhibited the expression of iNOS, TNF-alpha and IFN-gamma in the CNS of EAE rats and improved the clinical signs of EAE suggesting that this compound may have therapeutic potential in the treatment of neuroinflammatory diseases like MS

  230. Suzumura A, Sawada M (1999) Effects of vesnarinone on cytokine production and activation of murine Microglia. Life Sci. 64:1197-1203
    Abstract: Tumor necrosis factor alpha (TNF alpha) is considered to play a critical role in the development of various pathological processes in the central nervous system (CNS), such as neuronal degeneration, demyelination and gliosis. In order to search for agents which suppress TNF alpha production in the CNS for future treatment of these pathological conditions, the effects of a synthetic oral inotropic agent, vesnarinone, on murine Microglia were examined. Vesnarinone significantly suppressed TNF alpha production by Microglia in a dose-dependent manner, without affecting their viability, enzyme activity or expression of the major histocompatibility complex. Since the reported maximum serum concentration is high enough to suppress TNF alpha production in vitro (about 20 microM) after oral administration of the therapeutic dose of vesnarinone, this drug will be useful to treat intractable neurological diseases such as neurodegenerative disorders, multiple sclerosis or HIV-related neurological disorders

  231. Tan J, Town T, Paris D, Placzek A, Parker T, Crawford F, Yu H, Humphrey J, Mullan M (1999) Activation of Microglial cells by the CD40 pathway: relevance to multiple sclerosis. J.Neuroimmunol. 97:77-85
    Abstract: It is well known that Microglial cells perform a key role in mediating inflammatory processes, which are associated with neurodegenerative diseases such as multiple sclerosis (MS). In this study, we report that CD40 expression on Microglia is greatly enhanced by a low dose (10 U/ml) of IFN-gamma. We also find that ligation of Microglial CD40 by CD40L triggers a significant production of TNF-alpha. Activation of Microglia by ligation of CD40 in the presence of IFN-gamma results in cultured cortical neuronal injury, which is markedly attenuated by blockade of the CD40 pathway or neutralization of TNF-alpha. Finally, we find significant levels of IFN-gamma and TNF-alpha in the medium of co-cultured activated CD4+ T cells and Microglial cells, showing that Microglia can supply the CD40 receptor to activated CD4+ T cells and suggesting that this cellular interaction is a key event in MS pathophysiology

  232. Torreilles F, Salman-Tabcheh S, Guerin M, Torreilles J (1999) Neurodegenerative disorders: the role of peroxynitrite. Brain Res.Brain Res.Rev. 30:153-163
    Abstract: Inflammatory reaction is thought to be an important contributor to neuronal damage in neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and the parkinsonism dementia complex of Guam. Among the toxic agents released in brain tissues by activated cells, we focus attention in this review on peroxynitrite, the product of the reaction between nitric oxide (NO) and superoxide. Peroxynitrite is a strong oxidizing and nitrating agent which can react with all classes of biomolecules. In the CNS it can be generated by Microglial cells activated by pro-inflammatory cytokines or beta-amyloid peptide (beta-A) and by neurons in three different situations: hyperactivity of glutamate neurotransmission, mitochondrial dysfunction and depletion of L-arginine or tetrahydrobiopterin. The first two situations correspond to cellular responses to an initial neuronal injury and the peroxynitrite formed only exacerbates the inflammatory process, whereas in the third situation the peroxynitrite generated directly contributes to the initiation of the neurodegenerative process

  233. Trapp BD, Bo L, Mork S, Chang A (1999) Pathogenesis of tissue injury in MS lesions. J.Neuroimmunol. 98:49-56
    Abstract: multiple sclerosis (MS) is an inflammatory disease of the central nervous system. The primary pathological target in multiple sclerosis is myelin. Most MS patients follow a relapsing-remitting (RR-MS) course for 10 to 15 years that transforms into a chronic or secondary progressive disease (SP-MS). This review summarizes studies from our laboratory that implicate activated Microglia and astrocytes in early stages of myelin destruction in MS brain. In addition, we review evidence that indicates that axonal transection is a major pathological process in multiple sclerosis. Our data support the hypothesis that neurological disability in RR-MS is due to inflammatory demyelination while axonal loss plays a significant role in the irreversible neurological decline in SP-MS. Further elucidation of the pathological targets and pathological mechanisms of tissue destruction in MS brain will help identify new therapeutics

  234. van der MK, Hinojoza JR, Sobel RA (1999) Endothelial cell class II major histocompatibility complex molecule expression in stereotactic brain biopsies of patients with acute inflammatory/demyelinating conditions. J.Neuropathol.Exp.Neurol. 58:346-358
    Abstract: To determine if central nervous system (CNS) microvessel endothelial cells express class II major histocompatibility complex (MHC) molecules in early demyelinating lesions in humans, cerebral white matter (WM) biopsies from patients with acute inflammatory/demyelinating conditions, including 4 with multiple sclerosis (MS), were immunostained for class II MHC and other antigens. Eight of 9 biopsies showed focal MHC class II-positive endothelial cells; there were none in the CNS of 1 of the MS patients at autopsy. There were more vessels with class II-positive endothelial cells in areas with intact WM and gliosis than in areas with active demyelination or control WM; class II-positive endothelial cells in small venules and capillaries were adjacent to transmigrating and perivascular CD4-positive cells. By immunoelectron microscopy, class II molecules were localized to vesicles in endothelial cell cytoplasm, suggesting the potential for antigen processing. Perivascular cells, parenchymal Microglia, mononuclear cells and the perinuclear cytoplasm but not the processes of astrocytes were also class II-positive. These data indicate that in acute CNS inflammatory/demyelinating lesions, endothelial cells focally and apparently transiently express class II MHC molecules. This expression implies potential antigen-specific interactions, immunoregulatory or signalling functions in endothelial cells, or it may render them susceptible to CD4-positive cell-mediated cytotoxicity. Thus, class II-positive endothelial cells may have pivotal immunologic roles in initial stages of T cell responses in human CNS WM, particularly in acute MS lesions

  235. Woodroofe N, Cross AK, Harkness K, Simpson JE (1999) The role of chemokines in the pathogenesis of multiple sclerosis. Adv.Exp.Med.Biol. 468:135-150

  236. Yoshikawa M, Suzumura A, Tamaru T, Takayanagi T, Sawada M (1999) Effects of phosphodiesterase inhibitors on cytokine production by Microglia. Mult.Scler. 5:126-133
    Abstract: Type III and IV phosphodiesterase inhibitors (PDEIs) have recently been shown to suppress the production of TNF-alpha in several types of cells. In the present study, we have shown that all the types of PDEIs, from type I- to V-specific and non-specific, suppress the production of TNF-alpha by mouse Microglia stimulated with lipopolysaccharide (LPS) in a dose-dependent manner. Certain combinations of three different types of PDEIs synergistically suppressed TNF-alpha production by Microglia at a very low concentration (1 microM). Since some PDEIs reportedly pass through the blood-brain barrier (BBB), the combination of three PDEIs may be worth trying in neurological diseases, such as multiple sclerosis and HIV-related neurological diseases in which TNF-alpha may play a critical role. Some PDEIs also suppressed interleukin-I (IL-I) and IL-6 production by mouse Microglia stimulated with LPS. In contrast, the production of IL-10, which is known to be an inhibitory cytokine, was upregulated by certain PDEIs. The suppression of TNF-alpha and induction of IL-10 were confirmed at the mRNA level by RT-PCR. PDEIs may be useful anti-inflammatory agents by downregulating inflammatory cytokines and upregulating inhibitory cytokines in the central nervous system. (CNS)

  237. Zipp F, Krammer PH, Weller M (1999) Immune (dys)regulation in multiple sclerosis: role of the CD95-CD95 ligand system. Immunol.Today 20:550-554

  238. Aikawa Y, Tanuma N, Shin T, Makino S, Tanaka K, Matsumoto Y (1998) A new anti-rheumatic drug, T-614, effectively suppresses the development of autoimmune encephalomyelitis. J.Neuroimmunol. 89:35-42
    Abstract: In the present study, we examined the therapeutic effects of T-614 (3-formylamino-7-methylsulfonylaminoxy-4H-1-benzopyran-4-one), a new anti-rheumatic drug, on a T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis (EAE). T-614 dose-dependently suppressed the development of active EAE induced in Lewis rats by immunization with myelin basic protein (MBP) when administered for 2 weeks starting on the day of immunization (day 0 to 14). Amelioration of clinical signs was also obtained by the treatment at the effector phase (day 7 to 14) of the disease. Furthermore, T-614 treatment of recipient rats that had received MBP-sensitized lymphoid cells resulted in suppression of the clinical severity of EAE. Immunohistological examination revealed that the number of TCR alpha beta-expressing T cells and the extent of MHC class II expression in the spinal cord of rats treated with T-614 was markedly reduced. In vitro study using MBP-specific T cells showed that the addition of T-614 inhibited the proliferative responses of T cells and the production of pro-inflammatory cytokines such as IFN-gamma, IL-6 and TNF produced by T and accessory cells. Taken together, these findings imply that T-614 suppresses the development of EAE by inhibiting the proliferation of autoreactive T cells and pro-inflammatory cytokine production not only by T cells but also by macrophages/Microglia. This may be attributable to the result that T-614 is more effective at the effector phase rather than the induction phase. Thus, this drug has a potential value for the treatment of various T cell-mediated autoimmune diseases including multiple sclerosis (MS) as well as rheumatoid arthritis

  239. Albright AV, Lavi E, Black JB, Goldberg S, O'Connor MJ, Gonzalez-Scarano F (1998) The effect of human herpesvirus-6 (HHV-6) on cultured human neural cells: oligodendrocytes and Microglia. J.Neurovirol. 4:486-494
    Abstract: Human herpesvirus-6 (HHV-6) is a betaherpesvirus that has been frequently associated with pediatric encephalitis. In 1995 Challoner et al reported that HHV-6 variant B (HHV-6B) was linked to multiple sclerosis (MS) due to the presence of viral DNA and antigen in the oligodendrocytes surrounding MS plaques. These findings led us to examine HHV-6B's in vitro tropism for primary neural cells. HIV-6B mediated cell-to-cell fusion in cultured adult oligodendroglia. Infection of oligodendrocytes was further confirmed by transmission electron microscopy (EM), which showed the presence of intracellular HHV-6 particles, and by PCR for HHV-6 DNA. However, the release of infectious virus was low or undetectable in multiple experiments. Microglia were also susceptible to infection by HHV-6B, as demonstrated by an antigen capture assay. We did not detect infection of a differentiated neuronal cell line (NT2D). Our findings suggest that HHV-6B infection of oligodendrocytes and/or Microglia could potentially play a role in neuropathogenesis

  240. Cotman CW, Hailer NP, Pfister KK, Soltesz I, Schachner M (1998) Cell adhesion molecules in neural plasticity and pathology: similar mechanisms, distinct organizations? Prog.Neurobiol. 55:659-669
    Abstract: Brain plasticity and the mechanisms controlling plasticity are central to learning and memory as well as the recovery of function after brain injury. While it is clear that neurotrophic factors are one of the molecular classes that continue to regulate brain plasticity in the adult central nervous system (CNS), less appreciated but equally profound is the role of cell adhesion molecules (CAMs) in plasticity mechanisms such as long term potentiation, preservation of neurons and regeneration. Ironically, however, CAMs can also reorganize the extra-cellular space and cause disturbances that drive the development of brain pathology in conditions such as Alzheimer's disease and multiple sclerosis. Candidate molecules include the amyloid precursor protein which shares many properties of a classical CAM and beta-amyloid which can masquerade as a pseudo CAM. Beta-Amyloid serves as a nidus for the formation of senile plaques in Alzheimer's disease and like CAMs provides an environment for organizing neurotrophic factors and other CAMs. Inflammatory responses evolve in this environment and can initiate a vicious cycle of perpetuated neuronal damage that is medicated by Microglia, complement and other factors. Certain CAMs may converge on common signal transduction pathways involving focal adhesion kinases. Thus a breakdown in the organization of key CAMs and activation of their signal transduction mechanisms may serve as a new principle for the generation of brain pathology

  241. Couraud PO (1998) Infiltration of inflammatory cells through brain endothelium. Pathol.Biol.(Paris) 46:176-180
    Abstract: The blood-brain barrier (BBB) restricts exchanges of soluble factors and cells between the blood and the brain, thus playing a crucial role in maintenance of cerebral homeostasis. It is composed of the endothelial cells that line the cerebral capillaries. Cerebral capillaries have a number of distinctive morphological characteristics, including the presence of tight intercellular junctions. Also, the cerebral capillaries are surrounded by astrocytic projections that exert a positive regulatory effect on BBB tightness. One effect of the BBB is that the number of leukocytes that patrol the central nervous system is far lower than in peripheral organs. Nevertheless, massive leukocyte infiltration occurs in some disease states: for instance, numerous activated leukocytes are found in the cerebral parenchyma in patients with multiple sclerosis, and HIV encephalitis is probably due to passage of HIV-infected monocytes through the BBB. Compelling evidence has been obtained that the perivascular astrocytes and Microglial cells, as well as the cerebral endothelial cells, locally produce inflammatory cytokines that increase BBB permeability. Advances have also been made in the identification of leukocyte adhesion molecules expressed at the surface of cerebral endothelial cells. Expression of these molecules is induced by inflammatory cytokines. Interactions between these adhesion molecules and their leukocyte ligands may induce modifications within endothelial cells, including cytoskeleton reorganization and opening of intercellular junctions, which may allow leukocytes to cross the BBB. It is to be hoped that the new insights gained into the mechanisms of leukocyte penetration through the BBB may help to develop novel treatment strategies for neuroinflammatory disorders

  242. Diemel LT, Copelman CA, Cuzner ML (1998) Macrophages in CNS remyelination: friend or foe? Neurochem.Res. 23:341-347
    Abstract: Hematogenous macrophages and resident brain Microglia are agents of demyelination in multiple sclerosis (MS) and paradoxically may also participate in remyelination. In vitro studies have shown that macrophage enrichment of aggregate brain cultures promotes myelination per se and enhances the capacity to remyelinate following a demyelinating episode. It has been hypothesized that remyelination in MS is implemented by surviving dedifferentiated oligodendrocytes or by newly recruited progenitors that migrate, proliferate and synthesize myelin in response to signalling molecules in the local environment. We postulate that macrophage-derived cytokines or growth factors may directly or indirectly promote oligodendroglial proliferation and differentiation, contributing to myelin repair in inflammatory demyelinating disease

  243. Gasque P, Singhrao SK, Neal JW, Wang P, Sayah S, Fontaine M, Morgan BP (1998) The receptor for complement anaphylatoxin C3a is expressed by myeloid cells and nonmyeloid cells in inflamed human central nervous system: analysis in multiple sclerosis and bacterial meningitis. J.Immunol. 160:3543-3554
    Abstract: The complement anaphylatoxins C5a and C3a are released at the inflammatory site, where they contribute to the recruitment and activation of leukocytes and the activation of resident cells. The distribution of the receptor for C5a (C5aR) has been well studied; however, the receptor for C3a (C3aR) has only recently been cloned, and its distribution is uncharacterized. Using a specific affinity-purified anti-C3aR peptide Ab and oligonucleotides for reverse transcriptase-PCR analysis, C3aR expression was characterized in vitro on myeloid and nonmyeloid cells and in vivo in the brain. C3aR was expressed by adult astrocytes, astrocyte cell lines, monocyte lines THP1 and U937, neutrophils, and monocytes, but not by K562 or Ramos. C3aR staining was confirmed by flow cytometry, confocal imaging, and electron microscopy analysis. A 65-kDa protein was immunoprecipitated by the anti-C3aR from astrocyte and monocyte cell lysates. Our results at the protein level were confirmed at the mRNA level. Using reverse transcriptase-PCR, Southern blot, and sequencing we found that C3aR mRNA was expressed by fetal astrocytes, astrocyte cell lines, and THP1, but not by K562 or Ramos. The astrocyte C3aR cDNA was identical with the reported C3aR cDNA. C3aR expression was not detected in normal brain sections. However, a strong C3aR staining was evident in areas of inflammation in multiple sclerosis and bacterial meningitis. In meningitis, C3aR was abundantly expressed by reactive astrocytes, Microglia, and infiltrating cells (macrophages and neutrophils). In multiple sclerosis, infiltrating lymphocytes did not express C3aR, but a strong staining was detected on smooth muscle cells (pericytes) surrounding blood vessels

  244. Gasque P, Jones J, Singhrao SK, Morgan B (1998) Identification of an astrocyte cell population from human brain that expresses perforin, a cytotoxic protein implicated in immune defense. J.Exp.Med. 187:451-460
    Abstract: The brain is an immunoprivileged organ isolated from the peripheral immune system. However, it has been shown that resident cells, notably astrocytes and Microglia, can express numerous innate immune molecules, providing the capacity to generate a local antipathogen system. Perforin is a cytolytic protein present in the granules of cytotoxic T lymphocytes and natural killer cells. Expression in cells other than those of the hemopoetic lineage has not been described. We report here that fetal astrocytes in culture (passages 2 to 15), astrocytoma, and adult astrocytes expressed perforin. Reverse transcriptase polymerase chain reaction followed by Southern blot was carried out using multiple specific primers and all cDNAs were cloned and sequenced. Human fetal astrocyte perforin cDNA sequence was approximately 100% identical to the reported perforin cDNA cloned from T cells. Western blot analysis using monoclonal and polyclonal antiperforin peptide antibodies revealed a protein of 65 kD in both human fetal astrocyte and rat natural killer cell lysates (n = 4). Immunostaining followed by FACS(R) and confocal and electron microscopy analysis revealed that perforin was expressed by 40-50% of glial fibrillary acidic protein positive cells present in the fetal brain culture (n = 11). Perforin was not localized to granules in astrocytes but was present throughout the cytoplasm, probably in association with the endoplasmic reticulum. Perforin was not detected in normal adult brain tissue but was present in and around areas of inflammation (white and grey matter) in multiple sclerosis and neurodegenerative brains. Perforin-positive cells were identified as reactive astrocytes. These findings demonstrate that perforin expression is not unique to lymphoid cells and suggest that perforin produced by a subpopulation of astrocytes plays a role in inflammation in the brain

  245. Gebicke-Haerter PJ, Lieb K, Illes P, Berger M (1998) [Microglia: mechanisms of activation and significance in pathogenesis of neuropsychiatric illnesses]. Nervenarzt 69:752-762
    Abstract: Microglia are the resident macrophages of the brain. They are the central cellular element to initiate defense mechanisms against destructive environmental influences and to facilitate regenerative processes. No other cell type of the brain is endowed with a comparably comprehensive, immunocompetent machinery like Microglia. It encompasses cell proliferation, migration and differentiation into full-blown macrophages able to present antigen and to phagocytose cell debris. Relatively little is known about these stages of Microglia activation on the cellular and molecular level, although Microglia have been described as a separate cell type of the brain as early as in the 30ies of this century by P.del Rio Hortega. This review summarizes the data that have accumulated until now in this respect and tries to embed them into a clinical framework. Special focus has been given to the role of this cell type in the development and progression of multiple sclerosis, HIV-associated dementia and Alzheimer's disease

  246. Gveric D, Kaltschmidt C, Cuzner ML, Newcombe J (1998) Transcription factor NF-kappaB and inhibitor I kappaBalpha are localized in macrophages in active multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 57:168-178
    Abstract: NF-kappaB is a transcription factor family which on translocation to the nucleus regulates gene expression during cell activation. As such, NF-kappaB may play a role in the Microglial response to myelin damage in multiple sclerosis (MS) lesions. Here the cellular localization of NF-kappaB and expression of the inhibitory I kappaBalpha were examined by immunocytochemistry on central nervous system (CNS) tissue from MS and control cases. In normal control white matter, the active form of the NF-kappaB subunit RelA (p65) was localized in Microglial nuclei, while the c-Rel and p50 subunits and the inhibitory I kappaBalpha were restricted to the cytoplasm. In contrast, in actively demyelinating plaques, the RelA, c-Rel, and p50 subunits of NF-kappaB and I kappaBalpha were all present in macrophage nuclei in both parenchymal and perivascular areas. RelA was also found in the nuclei of a subset of hypertrophic astrocytes. Only c-Rel had a nuclear localization in lymphocytes in perivascular inflammatory cuffs. Our results suggest that constitutive activation of the RelA subunit in the nuclei of resting Microglia may facilitate a rapid response to pathological stimuli in the CNS. Activation of the inducible NF-kappaB pool in macrophages in MS lesions could amplify the inflammatory reaction through upregulation of NF-kappaB-controlled adhesion molecules and cytokines

  247. Hays SJ (1998) Therapeutic approaches to the treatment of neuroinflammatory diseases. Curr.Pharm.Des 4:335-348
    Abstract: Microglia cells are present in the central nervous system and respond quickly to pathogenic stimuli in order to protect the brain. When these immunological responses activate inappropriately or are prolonged, they can contribute to the neuronal damage observed in many neurodegenerative diseases. A variety of immune system modulators including complement proteins, inflammatory cytokines such IL-1 alpha, IL-1 beta, IL-3, IL-6, TNF-alpha, and S100 beta, colony-stimulating factor-1, coagulation proteins and matrix metalloproteases are made by both Microglia and astrocytes. Additionally astrocytes, the predominant glial component of the brain, express cell-adhesion molecules, cytokine receptors and induce nitric oxide synthease. The pathophysiology of Alzheimer's disease, stroke, traumatic brain injury, and multiple sclerosis suggest that a large portion of the irreversible damage observed can be attributed to a neuroinflammatory mechanism. The immunomodulators of these diseases are reviewed and new agents within specific molecular mechanisms are presented and discussed

  248. Hu P, Pollard J, Hunt N, Taylor J, Chan-Ling T (1998) Microvascular and cellular responses in the optic nerve of rats with acute experimental allergic encephalomyelitis (EAE). Brain Pathol. 8:475-486
    Abstract: The optic nerve of rats with EAE was examined at various times to determine the integrity of the blood-brain barrier (BBB) and to assess monocyte-macrophage, T cell, and Microglial responses. In naive control animals, leakage of horseradish peroxidase (HRP) and the presence of cells expressing major histocompatibility complex (MHC) class II antigen were evident in the meninges of the retrobulbar optic nerve. In rats with EAE, Microglia in the region of the lamina cribrosa and in the regions adjacent to the meninges became activated from day 7 to 8 postinduction (pi). HRP leakage was also evident in the region of the lamina cribrosa from day 7 to 8 pi. On day 8 pi, infiltration of inflammatory cells and Monastral blue leakage were apparent in the myelinated region of the optic nerve. The intensity of these cellular and vascular changes peaked at day 12 pi, when signs of clinical disease became manifest. Monocytes-macrophages expressing MHC class II and the ED1 antigen, together with lymphocytes expressing the alphabetaT cell receptor, constituted the major proportion of cells associated with inflammatory lesions. Thus: (i) the inherent weakness of the BBB as well as the presence of both antigen (myelin) and MHC class II+ cells in the retrobulbar optic nerve are likely susceptibility factors for the frequent involvement of this region in EAE and multiple sclerosis; and (ii) activation of Microglia occurs early in the pathogenesis of experimental optic neuritis

  249. Khan OA, Jiang H, Subramaniam PS, Johnson HM, Dhib-Jalbut SS (1998) Immunomodulating functions of recombinant ovine interferon tau: potential for therapy in multiple sclerosis and autoimmune disorders. Mult.Scler. 4:63-69
    Abstract: The interferons (IFN) are a family of complex proteins possessing antiviral, antiproliferative, and immunomodulatory activities. Two type I recombinant human IFN have been recently approved for the treatment of multiple sclerosis (MS). However, use of high dose type I IFN treatment in MS patients has been limited by dose-related toxicity. Ovine IFN tau is a unique type I interferon discovered for its role in the animal reproductive cycle. It differs from other type I IFNs in that it is remarkably less toxic even at high concentrations, is able to cross species barriers, and is not inducible by viral infection. Ovine IFN tau has been shown to be very effective in the treatment of animal models of MS. In this study, we examined the toxicity of OvIFN tau on human T-cells at high doses and its immunregulatory properties at equivalent doses. Our experiments confirmed the remarkably non-toxic nature of OvIFN tau on human cells at high concentrations as well as immunomodulating properties consistent with other type I IFNs including an antilymphoproliferative effect and inhibition of IFN gamma-induced HLA class II expression. These results suggest that OvIFN tau could be developed into a potentially less toxic therapeutic option for immune-mediated disorders including MS

  250. Kiefer R, Schweitzer T, Jung S, Toyka KV, Hartung HP (1998) Sequential expression of transforming growth factor-beta1 by T-cells, macrophages, and Microglia in rat spinal cord during autoimmune inflammation. J.Neuropathol.Exp.Neurol. 57:385-395
    Abstract: Transforming growth factor-beta1 (TGF-beta1) is crucially involved in regulating inflammatory events during experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. Despite accumulating evidence for local expression of TGF-beta1 in the inflamed nervous system, uncertainty remains regarding its cellular source. We have investigated the temporospatial distribution of TGF-beta1 gene expression in rat spinal cord during EAE. In actively induced EAE, in situ hybridization revealed strong expression of TGF-beta1 in meningeal and perivascular mononuclear infiltrates at onset of the disease, continued expression in perivascular infiltrates and scattered mononuclear cells at maximal disease severity, and expression in scattered parenchymal cells during recovery. Double labeling studies revealed subpopulations of infiltrating T-cells to be the major source of TGF-beta1 early in the disease, followed by macrophages at peak severity and Microglial cells during the recovery phase of EAE. Astrocytes and neurons did not express TGF-beta1. Quantification of mRNA by Northern blot analysis revealed that cellular expression of TGF-beta1 by T-cells, macrophages, and Microglia sums up to a long-lasting elevation of TGF-beta1 mRNA extending well into the recovery phase. Our data indicate cellular diversity and suggest functional diversity of TGF-beta1 gene expression during EAE. While TGF-beta1 expressed early in the disease by T-cells may contribute to inflammatory lesion development, Microglial cells may potentially contribute to recovery by expressing immunosuppressive TGF-beta1 during remission

  251. Liedtke W, Cannella B, Mazzaccaro RJ, Clements JM, Miller KM, Wucherpfennig KW, Gearing AJ, Raine CS (1998) Effective treatment of models of multiple sclerosis by matrix metalloproteinase inhibitors. Ann.Neurol. 44:35-46
    Abstract: The proinflammatory Th1 cytokine, tumor necrosis factor-alpha (TNF alpha), the cell death signaling molecule FasL, and several extracellular matrix degrading metalloproteinases have been implicated in the pathogenesis of multiple sclerosis (MS). The latter enzymes, as well as TNF alpha-converting enzyme and FasL-converting enzyme, can be blocked by matrix metalloproteinase inhibitors (MMPIs). In this study, we show that a potent MMPI was clinically effective in an animal model for MS, experimental autoimmune encephalomyelitis (EAE) in the SJL/J mouse. Efficacy was remarkable, as indicated by blocking and reversal of acute disease and reduced number of relapses and diminished mean cumulative disease score in chronic relapsing animals. Also, demyelination and glial scarring were significantly decreased in MMPI-treated mice with chronic relapsing EAE, as was central nervous system gene expression for TNF alpha and fasL. It is interesting that expression of the beneficial cytokine interleukin-4 (IL-4) was increased, and IL-4 was expressed on glial cells. The relevance of these compounds for MS was underscored by their ability to specifically inhibit TNF alpha shedding and cytotoxicity of myelin-autoreactive human cytotoxic CD4+ T-cell clones. This is the first report to show a positive effect by MMPIs on chronic relapsing EAE, its central nervous system cytokine profile, and on TNF alpha shedding by human myelin-autoreactive T cells

  252. Link H (1998) The cytokine storm in multiple sclerosis. Mult.Scler. 4:12-15
    Abstract: MS is associated with a cytokine storm characterized by the parallel upregulation of proinflammatory (IFN-gamma, TNF-alpha, and beta, and IL-12) and immune response-down-regulating (TGF-beta, IL-10) cytokines. Also IL-6 and the cytolytic molecule perforin are upregulated. Even when evaluated in individual MS patients over the disease course, no Th1/Th2 dichotomy is obvious but, instead, upregulation of Th1 + Th2 + Th3 cytokines simultaneously, probably reflecting the complex pathology of MS in lesion size, time and distribution in the individual patient. Few correlations have been observed between cytokines and clinical MS variables, though upregulation of TGF-beta seems to correlate with benign course and minor disability. Both pro- and antiinflammatory cytokines are also produced by Microglia and astrocytes, constituting a CNS-cytokine network that interacts with the cytokine network of the immune system. This complexity is to be kept in mind when searching for cytokine abnormalities in MS

  253. Liu JS, Amaral TD, Brosnan CF, Lee SC (1998) IFNs are critical regulators of IL-1 receptor antagonist and IL-1 expression in human Microglia. J.Immunol. 161:1989-1996
    Abstract: Because IL-1 is implicated in the pathogenesis of multiple sclerosis, and IFNs are known to alter disease course, we sought to determine whether IFNs can regulate the expression of IL-1 and IL-1R antagonist (IL-1Ra) in primary cultures of human Microglia and astrocytes. We found that IL-1 and IL-1Ra are products of Microglia but not astrocytes, and IFN-beta and IFN-gamma differentially modulate LPS- and cytokine-induced IL-1 and IL-1Ra. IFN-beta induces IL-1Ra and augments LPS- and IL-4-induced IL-1Ra, but suppresses LPS- and IL-1-induced IL-1, shifting the balance toward the expression of the IL-1Ra. Like IFN-beta, IFN-gamma suppresses the expression of both LPS and IL-1-induced IL-1beta. However, IFN-gamma also suppresses the expression of IFN-beta- and IL-4-induced IL-1Ra so that IFN-gamma may enhance or suppress IL-1 activity depending on the other cytokines present. IL-4 has similar effects to IFN-beta; however, other anti-inflammatory cytokines, did not regulate IL-1 or IL-1Ra in human Microglia. Our data demonstrate a novel suppressive effect of IFN-beta and IL-4 on IL-1 activity in human Microglia, suggesting that IFN-beta, a therapeutic agent used for multiple sclerosis, could have wider applications in the treatment of other central nervous system disorders in which IL-1 activity has been implicated in the pathogenesis

  254. Liu X, Mashour GA, Webster HF, Kurtz A (1998) Basic FGF and FGF receptor 1 are expressed in Microglia during experimental autoimmune encephalomyelitis: temporally distinct expression of midkine and pleiotrophin. Glia 24:390-397
    Abstract: Heparin-binding growth factors have been implicated in central nervous system development, regeneration and pathology. To assess the expression pattern and possible function in multiple sclerosis, the heparin-binding growth factors pleiotrophin (PTN), midkine (MK), basic fibroblast growth factor (FGF-2) and one of its receptors (FGFR1/flg) mRNA and protein levels were examined in an experimental autoimmune encephalomyelitis (EAE) model in the Lewis rat. We assessed the time course of expression of PTN, MK and FGF-2 during EAE and determined the cellular origin of FGF-2 and FGFR1 in normal spinal cord and during inflammatory demyelination. Basal expression of PTN and MK mRNAs in normal spinal cords was significantly upregulated after induction of EAE. MK expression was upregulated two to threefold correlating with disease progression, whereas PTN expression reached peak levels threefold above basal levels during the clinical recovery period. FGF-2 mRNA expression was low in normal spinal cord and dramatically increased in correlation with progressive demyelination. FGF-2 was confined to neurons in normal tissue and shifted dramatically to Microglia, paralleling their activation during EAE. Double immunohistochemistry revealed colocalization of FGF-2 to activated Microglia/macrophages with strongest expression in the macrophage-rich perivascular core area and Microglial expression at the edges of white and gray matter perivascular regions. FGFR1, like its ligand, was induced in activated macrophages/Microglia. Growth factor expression in demyelinating diseases could serve several functions, e.g., to modulate the activity of Microglia/macrophage in an autocrine fashion, to induce the expression of other factors like insulin-like growth factor 1 or plasminogen activator, which can effect regeneration or degeneration, respectively, and finally to stimulate directly localized proliferation and/or regeneration of oligodendrocytes within the lesion area

  255. Maatta JA, Sjoholm UR, Nygardas PT, Salmi AA, Hinkkanen AE (1998) Neutrophils secreting tumor necrosis factor alpha infiltrate the central nervous system of BALB/c mice with experimental autoimmune encephalomyelitis. J.Neuroimmunol. 90:162-175
    Abstract: Experimental autoimmune encephalomyelitis (EAE) can be induced in resistant BALB/c mice by ultrasound-formed adjuvant emulsion. In contrast to susceptible mouse strains large numbers of neutrophils secreting TNF-alpha occupied the central nervous system (CNS) of BALB/c mice with severe EAE, whereas only small numbers of macrophages and CD4+ T-cells could be detected. CNS infiltration was preceded with activation of Microglial cells. Ultrasound formed adjuvant induced early IFN-gamma expression in popliteal lymph nodes of BALB/c mice, whereas conventional adjuvant induced delayed IFN-gamma production. Although the clinical outcome of EAE was similar to that seen in susceptible mice, the pathogenesis was distinct having possible implications on the different forms seen in multiple sclerosis

  256. Matyszak MK (1998) Inflammation in the CNS: balance between immunological privilege and immune responses. Prog.Neurobiol. 56:19-35
    Abstract: Inflammatory components play an important part in many diseases of the central nervous system (CNS). Recent evidence suggests that this may also be true of diseases which were previously considered as purely neuro-degenerative. However, it is also clear that inflammatory responses in the CNS differ in many ways from responses in non-CNS tissues. Some of these differences have been demonstrated by the use of animal models. For example, when bacteria are injected into the brain parenchyma, they induce a typical acute inflammatory response. However, unlike in other tissues, bacteria which are not cleared from the brain parenchyma remain undetected by the immune system. Some bacteria, such as bacillus Calmette-Guerin, can persist in the brain parenchyma for months sequestered in Microglia and perivascular macrophages. When an animal with an intraparenchymal bacteria deposit is later sensitised peripherally, an immune response is evoked at the site of the deposits. The lesions induced in the CNS parenchyma are T-cell mediated and show characteristics typical of a delayed-type hypersensitivity response. The lesions produce a breakdown of the blood-brain barrier and demyelination. These immune responses are similar to those described for multiple sclerosis lesions. The responses to bacteria are unique to the brain parenchyma. Pathogens injected into the ventricles induce inflammatory responses similar to those in other non-CNS tissues: there is an acute inflammatory response which develops spontaneously into an immune mediated response within the first week

  257. Mayer AM (1998) Therapeutic implications of Microglia activation by lipopolysaccharide and reactive oxygen species generation in septic shock and central nervous system pathologies: a review. Medicina (B Aires) 58:377-385
    Abstract: The pathophysiology of organ system failure in sepsis, in particular the effects of septic shock on the central nervous system, are still incompletely understood. Lipopolysaccharide (LPS) from Gram-negative bacteria affects the permeability of the blood-brain barrier and causes the activation of brain Microglia. A growing body of research supports involvement of activated brain Microglia in brain pathologies caused by infectious diseases, trauma, tumors, ischemia, Alzheimer's disease, Parkinson's disease, Down's syndrome, multiple sclerosis and AIDS. Those seminal studies that have contributed to the characterization of the in vivo and in vitro effects of LPS on Microglia function, mediator generation and receptor expression are presented within a historical perspective. In particular, all those in vitro studies on O2-, H2O2 and NO. generation by either unprimed or primed Microglia have been extensively reviewed. The apparent controversial effect of LPS on Microglia O2- is discussed. Because treatment modalities for septic shock have not significantly affected the current high mortality, alternative strategies with antioxidants are currently being investigated. Reduction of Microglia O2- generation is proposed as a possible complementary strategy to antioxidative therapy for septic shock and CNS pathologies that involve activated Microglia

  258. McManus CM, Brosnan CF, Berman JW (1998) Cytokine induction of MIP-1 alpha and MIP-1 beta in human fetal Microglia. J.Immunol. 160:1449-1455
    Abstract: Leukocyte infiltration into the central nervous system (CNS) is a key event in the inflammatory processes of neuroimmunologic diseases. Microglia, resident macrophages of the CNS, may contribute to this process by elaborating chemoattractants that are capable of recruiting leukocytes across the blood-brain barrier. Such factors have been detected in the CNS of animal models of multiple sclerosis and in the brains of human and nonhuman primates with AIDS encephalitis. As the expression of these chemoattractants may play an important role in the initiation and progression of neuroimmunologic diseases, we analyzed expression of the chemokines MIP-1 alpha, MIP-1 beta, MCP-1, and RANTES in human fetal Microglial cultures. Unstimulated Microglia expressed minimal levels of MIP-1 alpha, MIP-1 beta, and MCP-1, while RANTES was undetectable. In response to LPS, TNF-alpha, or IL-1 beta, both MIP-1 alpha and MIP-1 beta were induced at the mRNA and protein levels in a dose- and time-dependent manner. IFN-gamma did not significantly induce chemokine expression. MCP-1 was detectable in LPS- and cytokine-treated Microglia. TGF-beta, a cytokine with down-modulatory effects on other cell types, had little effect on chemokine expression in Microglia when used concomitantly before or during treatment with LPS. These results illustrate the ability of certain inflammatory stimuli to induce expression of MIP-1 alpha, MIP-1 beta, and MCP-1 by human fetal Microglia. The expression of these chemoattractants may function to recruit inflammatory cells into the CNS during the course of neuroimmunologic diseases and may modulate the ability of HIV to infect the CNS

  259. Minghetti L, Polazzi E, Nicolini A, Levi G (1998) Opposite regulation of prostaglandin E2 synthesis by transforming growth factor-beta1 and interleukin 10 in activated Microglial cultures. J.Neuroimmunol. 82:31-39
    Abstract: We have recently shown that prostaglandin E2 (PGE2) synthesis in activated Microglia is tightly regulated by several substances (NO, neurotransmitters, pro-inflammatory cytokines), that might originate from intrinsic brain cells or from hematogenous cells infiltrating the brain in the course of inflammatory diseases. In view of the important immunoregulatory and neuroprotective functions recently attributed to PGE2, in the present study we extended our analysis of factors regulating PGE2 synthesis in rat Microglial cultures to two anti-inflammatory and immunosuppressive cytokines, transforming growth factor beta1 (TGF-beta1) and interleukin 10 (IL-10), which share with PGE2 the ability to strongly deactivate peripheral macrophages and Microglial cells. Moreover, we looked at the effect of the two cytokines on nitric oxide (NO) synthesis, another important Microglial effector, whose synthesis is linked to that of PGE2 by complex feed-back mechanisms. We found that while both cytokines inhibited LPS-induced NO release, they had distinct and opposite regulatory activities on PGE2 production. In fact, while TGF-beta1 enhanced LPS-induced PGE2 synthesis, IL-10 showed an inhibitory effect. The two cytokines acted mainly by regulating the LPS-induced expression of the rate limiting enzymes of the two metabolic pathways, cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS). Moreover, TGF-beta1 counteracted the effect of the pro-inflammatory cytokine interferon-gamma, which in the same cultures has been shown to downregulate PGE2 and to upregulate NO synthesis. Although the present in vitro observations cannot be directly extrapolated to the in vivo situation, they may provide a novel clue for understanding the specific role of TGF-beta1 and IL-10 in several neurological diseases such as multiple sclerosis, in which their cerebral level was found to be elevated

  260. Morris CS, Esiri MM (1998) The expression of cytokines and their receptors in normal and mildly reactive human brain. J.Neuroimmunol. 92:85-97
    Abstract: There are many inflammatory diseases of the brain such as AIDS, other viral encephalitides and multiple sclerosis all of which are probably influenced by both systemic and focal CNS cytokine release. We have studied the expression of a wide range of pro- and anti-inflammatory cytokines and their receptors, beta2-microglobulin, and MHC Class II, using immunocytochemistry on cryostat sections of normal and mildly reactive human brain. The aim was to try to determine the cytokine 'baseline' expression in normal human brain and the results obtained indicated very low expression of various cytokines and their receptors, mainly by Microglia and macrophages with some endothelial expression

  261. Mujtaba MG, Streit WJ, Johnson HM (1998) IFN-tau suppresses both the autoreactive humoral and cellular immune responses and induces stable remission in mice with chronic experimental allergic encephalomyelitis. Cell Immunol. 186:94-102
    Abstract: We have previously shown that interferon-tau (IFN-tau) pretreatment inhibits the development of both acute and chronic mouse experimental allergic encephalomyelitis (EAE), an animal model for the human demyelinating disease multiple sclerosis (MS). IFN-tau is a type I IFN that has pregnancy recognition hormone activity in ruminants. Here we show that IFN-tau induced remission in SJL/J mice that had ongoing chronic active EAE disease and protected mice against secondary relapses. IFN-tau treatment reversed lymphocyte infiltration and Microglial activation in the central nervous system. Mice that were treated with IFN-tau had lower levels of anti-MBP antibodies than untreated mice in both chronic and acute forms of EAE. MBP induced proliferation in B cells from EAE mice, but treatment with IFN-tau either in vivo or in vitro blocked activation. Furthermore, IFN-tau inhibited MBP activation of T cells from EAE mice. Thus, IFN-tau inhibits the humoral arm as well as the cellular arm of the autoimmune disease EAE. The data presented here show that IFN-tau inhibits both B cell and T cell responses in EAE as well as active, chronic EAE, and this may help explain the effectiveness of type I IFNs in treatment of MS

  262. Nakajima K, Kohsaka S (1998) [Microglia: function in the pathological state]. No To Shinkei 50:5-16

  263. Nataf S, Davoust N, Barnum SR (1998) Kinetics of anaphylatoxin C5a receptor expression during experimental allergic encephalomyelitis. J.Neuroimmunol. 91:147-155
    Abstract: In this study, we investigated the expression of the C5aR in spinal cords of Lewis rats with experimental allergic encephalomyelitis (EAE). Using in situ hybridization (ISH) we analyzed the kinetics of C5aR at different time points of EAE (preclinical stage, clinical peak, remission phase). We observed that C5aR mRNA was readily detected in the CNS of EAE rats at all the stages of the disease. Using a combination of ISH and immunohistochemistry, we formally demonstrated that C5aR is strongly expressed on Microglial cells and hypertrophic astrocytes during EAE. The potential involvement of C5a receptor in EAE physiopathology is discussed

  264. Raine CS, Bonetti B, Cannella B (1998) multiple sclerosis: expression of molecules of the tumor necrosis factor ligand and receptor families in relationship to the demyelinated plaque. Rev.Neurol.(Paris) 154:577-585
    Abstract: The molecules that comprise the tumor necrosis factor ligand and receptor (TNF-L and TNF-R) families play important roles in tissue homeostasis and in multiple sclerosis (MS). For example, levels of the TNF ligand (TNF alpha; cachectin) correlate with disease progression and lymphotoxin (LT, TNF beta) has been localized in MS lesions. Members of the TNF-R family are typical signal sensors which upon binding with ligand aggregate and recruit signal transducers. To date, no TNF-R molecules have been reported in MS although TNF-RI and RII have been localized to oligodendrocytes in culture. In the present study, the expression of TNF, LT alpha (the soluble form of LT), LT beta (the beta chain of LT alpha beta, the membrane-bound form of LT), TNF-RI, TNF-RII, LT beta-R, FasL, and Fas receptor in MS lesions has been examined by immunohistochemistry for protein and by RT-PCR for mRNA. In addition, the TUNEL technique for DNA fragmentation was applied to detect apoptosis. The results have shown that contrarily to predictions, oligodendrocytes around active MS lesions frequently expressed TNF-R molecules belonging to the apoptotic cascade. However, these cells did not undergo apoptosis, as judged by TUNEL. On the other hand, lymphocytes (and a few Microglial cells) in the same tissue displayed apoptosis. Microglial cells were the major effector cells in the CNS and expressed TNF, LT alpha and FasL. LT beta expression was seen on astrocytes and oligodendrocytes, and LT beta-R on astrocytes. We conclude that TNF-L and TNF-R molecules are extensively expressed in MS, that their expression occurs at high levels but is not specific for MS, and that oligodendrocytes are depleted by a cytolytic mechanism, not by apoptosis

  265. Reder AT, Genc K, Byskosh PV, Porrini AM (1998) Monocyte activation in multiple sclerosis. Mult.Scler. 4:162-168
    Abstract: Monocytes, macrophages, and Microglia have a central role in the CNS inflammation of MS. Monocytes are important in the earliest events in MS. Peripheral blood monocytes secrete prostaglandins before MS attacks. During clinical activity monocyte activation markers increase and IL-1 and TNF-alpha levels are elevated. Other monocyte products such as IL-10 reduce inflammation. IL-10 mRNA in MNC is increased during stable disease. Manipulation of monokine secretion and expression of monocyte surface proteins are reasonable approaches for immune therapy of MS

  266. Schonrock LM, Kuhlmann T, Adler S, Bitsch A, Bruck W (1998) Identification of glial cell proliferation in early multiple sclerosis lesions. Neuropathol.Appl.Neurobiol. 24:320-330
    Abstract: multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system which leads to destruction of myelin sheaths. The patterns of cell proliferation in the early course of the disease are largely unknown. The present study used immunohistochemical identification of proliferating glial cells in stereotactic brain biopsy material of eight patients with early chronic MS. Double-labelling with the proliferation marker MIB-1 detected proliferating oligodendrocytes (MOG), astrocytes (GFAP) and Microglia/macrophages (Ki-M1P). The majority of proliferating cells were macrophages/Microglia when compared with oligodendrocytes (P > 0.005) or astrocytes (P > 0.0005); only a minor proportion of Microglia/macrophages, however, proliferated in situ. Astrocytic and oligodendroglial proliferation was sparse to absent and showed significant variations between different patients. There were statistically significant differences when comparing the amount of proliferation between lesions of different demyelinating activity: highest numbers of proliferating cells were found in early active lesions compared with demyelinated and early remyelinated lesions (P > 0.05) or the periplaque white matter (P > 0.01). MOG-positive oligodendrocytes proliferated occasionally in the early stages of lesion formation; this proliferation occurred in four cases but was independent of the stage of the disease. Since MOG is expressed by mature oligodendrocytes, and not by immature precursors, this might suggest a potential role for the proliferation of mature surviving oligodendrocytes with subsequent remyelination

  267. Scolding NJ, Morgan BP, Compston DA (1998) The expression of complement regulatory proteins by adult human oligodendrocytes. J.Neuroimmunol. 84:69-75
    Abstract: In multiple sclerosis, infiltrating T lymphocytes and perivascular Microglia may initiate demyelinating lesions, but a role for antibody and complement in the ensuing inflammatory damage to myelin and oligodendrocytes is likely. In most tissues, ubiquitously expressed complement regulatory proteins prevent autologous destruction, protecting host cells from the powerful cytolytic activity of activated complement. We have studied the surface expression of a comprehensive range of complement regulatory proteins by live adult human oligodendrocytes in vitro. Only DAF of the activation pathway regulators was expressed, not CR1 or MCP. Of the membrane attack pathway regulatory proteins, HRF was not expressed, while substantial heterogeneity of CD59 expression by oligodendrocytes was found. Clusterin expression was not found. A relative deficiency of protective complement regulatory proteins on human oligodendrocytes may contribute to their selective damage in multiple sclerosis

  268. Shields DC, Tyor WR, Deibler GE, Banik NL (1998) Increased calpain expression in experimental demyelinating optic neuritis: an immunocytochemical study. Brain Res. 784:299-304
    Abstract: Since calcium activated neutral proteinase (calpain) is present in the central nervous system (CNS) and degrades myelin proteins, this endopeptidase has been suggested to play a role in myelin destruction in demyelinating diseases such as multiple sclerosis (MS). In the present study, calpain immunocytochemical expression was examined in Lewis rats with acute experimental allergic encephalomyelitis (EAE), an animal model for MS and optic neuritis. To identify cells expressing calpain, we labeled rat optic nerve sections for calpain with a polyclonal myelin calpain antibody and with monoclonal antibodies for glial (GFAP, OX42) and inflammatory (CD2, ED2, ED1, IFN-gamma) cell-specific markers. The results showed increased calpain expression in Microglia (OX42) and infiltrating macrophages (ED1,2) in EAE compared to normal controls. Astrocytes constitutively expressed calpain in controls and acute EAE. Reactive astrocytes in EAE located in or near inflammatory foci, exhibited markedly increased calpain expression. Most T cells in acute EAE showed low level calpain expression while activated IFN-gamma-producing lymphocytes in inflammatory foci exhibited elevated levels of calpain expression. Thus, our results demonstrate increased calpain expression (at transcriptional and/or translational levels) in a rat model of optic neuritis. A role for calpain in myelin destruction during optic neuritis may be relevant to the pathogenesis of this disorder

  269. Shields DC, Tyor WR, Deibler GE, Hogan EL, Banik NL (1998) Increased calpain expression in activated glial and inflammatory cells in experimental allergic encephalomyelitis. Proc.Natl.Acad.Sci.U.S.A 95:5768-5772
    Abstract: In demyelinating diseases such as multiple sclerosis (MS), myelin membrane structure is destabilized as myelin proteins are lost. Calcium-activated neutral proteinase (calpain) is believed to participate in myelin protein degradation because known calpain substrates [myelin basic protein (MBP); myelin-associated glycoprotein] are degraded in this disease. In exploring the role of calpain in demyelinating diseases, we examined calpain expression in Lewis rats with acute experimental allergic encephalomyelitis (EAE), an animal model for MS. Using double-immunofluorescence labeling to identify cells expressing calpain, we labeled rat spinal cord sections for calpain with a polyclonal millicalpain antibody and with mAbs for glial (GFAP, OX42, GalC) and inflammatory (CD2, ED2, interferon gamma) cell-specific markers. Calpain expression was increased in activated Microglia (OX42) and infiltrating macrophages (ED2) compared with controls. Oligodendrocytes (galactocerebroside) and astrocytes (GFAP) had constitutive calpain expression in normal spinal cords whereas reactive astrocytes in spinal cords from animals with EAE exhibited markedly increased calpain levels compared with astrocytes in adjuvant controls. Oligodendrocytes in spinal cords from rats with EAE expressed increased calpain levels in some areas, but overall the increases in calpain expression were small. Most T cells in grade 4 EAE expressed low levels of calpain, but interferon gamma-positive cells demonstrated markedly increased calpain expression. These findings suggest that increased levels of calpain in activated glial and inflammatory cells in EAE may contribute to myelin destruction in demyelinating diseases such as MS

  270. Simpson JE, Newcombe J, Cuzner ML, Woodroofe MN (1998) Expression of monocyte chemoattractant protein-1 and other beta-chemokines by resident glia and inflammatory cells in multiple sclerosis lesions. J.Neuroimmunol. 84:238-249
    Abstract: Beta-chemokines induce the directional migration of monocytes and T lymphocytes and are thus associated with chronic inflammation. Using immunocytochemistry and in situ hybridisation (ISH) techniques, we have examined the expression of the beta-chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated upon activation, normal T cell expressed and secreted) in post-mortem human brain from multiple sclerosis (MS) cases, at different stages of lesion development. In actively demyelinating MS plaques RANTES expression was restricted to the blood vessel endothelium, perivascular cells and surrounding astrocytes, suggesting a role in the recruitment of inflammatory cells from the circulation. MCP-1 was expressed by astrocytes and macrophages within acute MS lesions, but was restricted to reactive astrocytes in the parenchyma surrounding the lesion. MIP-1alpha was expressed by astrocytes and macrophages within the plaque, while MIP-1beta was expressed by macrophages and Microglia within the lesion, and by Microglia in surrounding white matter. Glial cells may be stimulated to produce chemokines and continue the local inflammatory response by forming chemotactic gradients to attract T cells and mononuclear phagocytes from the circulation and surrounding tissue

  271. Singh I, Pahan K, Khan M, Singh AK (1998) Cytokine-mediated induction of ceramide production is redox-sensitive. Implications to proinflammatory cytokine-mediated apoptosis in demyelinating diseases. J.Biol.Chem. 273:20354-20362
    Abstract: The present study underlines the importance of reactive oxygen species in cytokine-mediated degradation of sphingomyelin (SM) to ceramide. Treatment of rat primary astrocytes with tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta led to marked alteration in cellular redox (decrease in intracellular GSH) and rapid degradation of SM to ceramide. Interestingly, pretreatment of astrocytes with N-acetylcysteine (NAC), an antioxidant and efficient thiol source for glutathione, prevented cytokine-induced decrease in GSH and degradation of sphingomyelin to ceramide, whereas treatment of astrocytes with diamide, a thiol-depleting agent, alone caused degradation of SM to ceramide. Moreover, potent activation of SM hydrolysis and ceramide generation were observed by direct addition of an oxidant like hydrogen peroxide or a prooxidant like aminotriazole. Similar to NAC, pyrrolidinedithiocarbamate, another antioxidant, was also found to be a potent inhibitor of cytokine-induced degradation of SM to ceramide indicating that cytokine-induced hydrolysis of sphingomyelin is redox-sensitive. Besides astrocytes, NAC also blocked cytokine-mediated ceramide production in rat primary oligodendrocytes, Microglia, and C6 glial cells. Inhibition of TNF-alpha- and diamide-mediated depletion of GSH, elevation of ceramide level, and DNA fragmentation (apoptosis) in primary oligodendrocytes by NAC, and observed depletion of GSH, elevation of ceramide level, and apoptosis in banked human brains from patients with neuroinflammatory diseases (e.g. X-adrenoleukodystrophy and multiple sclerosis) suggest that the intracellular level of GSH may play a critical role in the regulation of cytokine-induced generation of ceramide leading to apoptosis of brain cells in these diseases

  272. Smith ME, van der MK, Somera FP, Sobel RA (1998) Effects of phorbol myristate acetate (PMA) on functions of macrophages and Microglia in vitro. Neurochem.Res. 23:427-434
    Abstract: Peripheral macrophages infiltrating the central nervous system and resident Microglia phagocytize myelin in cell-mediated demyelinating diseases, including experimental autoimmune encephalomyelitis and multiple sclerosis. A cascade of cytokines is believed to modulate the immunological sequence of events occurring in these conditions, and several of these mediate their effects through the protein kinase C pathway. Therefore, we compared the effects of phorbol myristate acetate (PMA), an activator of protein kinase C, on various functions of cultured macrophages and Microglia. PMA at moderate concentrations induced apoptosis in macrophages, and this process appeared to be increased in the presence of myelin. In contrast, Microglia were activated by PMA, and greatly increased their phagocytosis of myelin. Control macrophages released a considerable amount of proteolytic activity into the medium, as measured by the breakdown of myelin basic protein, and in the process of undergoing apoptosis from PMA-treatment, even higher amounts were released. The enzyme activity in control macrophage medium was inhibited mainly by PMSF and calpain inhibitors, while that from PMA-treated macrophages was inhibited by calpain inhibitors only. An ICE inhibitor was ineffective in inhibiting activity in medium from PMA-treated cells undergoing apoptosis. Medium from Microglia contained very little proteolytic activity, and this was not increased by PMA. Cultured macrophages showed little evidence of oxygen free radical release as measured by the TBARS procedure, and PMA had no effect. Microglia, on the other hand, produced higher levels of reactive oxygen species, with a further increase of 18% by PMA. Thus major functions of these phagocytic cells appear to be modulated by the protein kinase C pathway, although the two cell types show very different responses to an activator of this signal

  273. Suzumura A, Sawada M, Makino M, Takayanagi T (1998) Propentofylline inhibits production of TNFalpha and infection of LP-BM5 murine leukemia virus in glial cells. J.Neurovirol. 4:553-559
    Abstract: We examined the effects of a xanthine derivative, propentofylline, on TNFalpha production by glial cells and on infection ofglial cells with a murine leukemia virus, LP-BM5, which induces murine AIDS in susceptible mice. Propentofylline suppressed TNFalpha production in glial cells and also effectively suppressed infection ofglial cells with LP-BM5 in vitro. Addition ofTNFalpha, but not IL-1 or IL-6, abolished the suppressive effects ofpropentofylline. Anti-TNFalpha antibody also suppressed infection of LP-BM5 in these cells. These findings suggest that propentofylline suppressed LP-BM5 infection in glial cells by suppressing TNFalpha production by these cells. Because propentofylline reportedly passes through the blood-brain barrier, it may be useful in the treatment of central nervous system involvement by HIV infection or neurological diseases in which TNFalpha plays a causative role, such as multiple sclerosis

  274. Tan L, Gordon KB, Mueller JP, Matis LA, Miller SD (1998) Presentation of proteolipid protein epitopes and B7-1-dependent activation of encephalitogenic T cells by IFN-gamma-activated SJL/J astrocytes. J.Immunol. 160:4271-4279
    Abstract: There is controversy regarding the possible role of glial cells as APCs in the pathogenesis of central nervous system (CNS) demyelinating diseases such as multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Microglia have been clearly shown to present Ag in the CNS, and due to the proximity of activated astroglial cells to infiltrating T cells and macrophages in demyelinating lesions, it is also possible that astrocytes positively or negatively regulate disease initiation and/or progression. We examined the capacity of IFN-gamma-treated astrocytes from EAE-susceptible SJL/J mice to process and present myelin epitopes. IFN-gamma activation up-regulated ICAM-1, VCAM-1, MHC class II, invariant chain, H2-M, CD40, and B7-1 as determined by FACS and/or RT-PCR analyses. B7-2 expression was only marginally enhanced on SJL/J astrocytes. Consistent with the expression of these accessory molecules, IFN-gamma-treated SJL/J astrocytes induced the B7-1-dependent activation of Th1 lines and lymph node T cells specific for the immunodominant encephalitogenic proteolipid protein (PLP) epitope (PLP139-151) as assessed by proliferation and activation for the adoptive transfer of EAE. Interestingly, IFN-gamma-activated astrocytes efficiently processed and presented PLP139-151, but not the subdominant PLP178-191, PLP56-70, or PLP104-117 epitopes, from intact PLP and a recombinant variant fusion protein of PLP (MP4). The data are consistent with the hypothesis that astrocytes in the proinflammatory CNS environment have the capability of activating CNS-infiltrating encephalitogenic T cells specific for immunodominant epitopes on various myelin proteins that may be involved in either the initial or the relapsing stages of EAE

  275. Taylor RS (1998) Immunologic aspects of multiple sclerosis. Phys.Med.Rehabil.Clin.N.Am. 9:525-36, v
    Abstract: multiple sclerosis (MS) is the most common autoimmune disease involving the central nervous system. Knowledge of the basic autoimmunologic properties related to MS is critical to formulating a logical treatment approach to the patient. A review of immunologic systems and their specific applicability to MS is included in this article

  276. Tran EH, Hoekstra K, van Rooijen N, Dijkstra CD, Owens T (1998) Immune invasion of the central nervous system parenchyma and experimental allergic encephalomyelitis, but not leukocyte extravasation from blood, are prevented in macrophage-depleted mice. J.Immunol. 161:3767-3775
    Abstract: Organ-specific autoimmune diseases are characterized by infiltrates, including T lymphocytes and activated macrophages. Macrophages and secondarily activated tissue resident counterparts can both present Ag to and contribute to cytokine secretion by T lymphocytes. We have previously shown a crucial role of peripheral macrophages in experimental allergic encephalomyelitis (EAE), a Th1-mediated demyelinating disease that serves as a an animal model for multiple sclerosis (MS), by their depletion using mannosylated liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP). Here we describe studies to investigate the mechanisms by which macrophages contribute to the lesion formation in EAE, by studying the effect of Cl2MDP-containing mannosylated liposomes (Cl2MDP-mnL) on adoptively transferred EAE in SJL/J mice. Adoptive transfer of EAE with myelin basic protein-reactive CD4+ T cells to SJL/J mice was abrogated by Cl2MDP-mnL treatment. CD4+ T cell and MHC II+ B220+ B cell extravasation from blood vessels and Th1 cytokine production were not inhibited. However, invasion of the central nervous system intraparenchymal tissues by lymphocytes, F4/80+, Mac-1+, and MOMA-1+ macrophages was almost completely blocked after treatment with Cl2MDP-mnL. Furthermore, in Cl2MDP-mnL-treated mice, the myelin sheaths appeared completely normal, whereas, in the control groups, marked demyelination occurred. Production of TNF-alpha and inducible nitric oxide synthase, both associated with macrophage/Microglial activation, was inhibited. This intervention reveals a role for macrophages in regulating the invasion of autoreactive T cells and secondary glial recruitment that ordinarily lead to demyelinating pathology in EAE and multiple sclerosis

  277. Walsh MJ, Murray JM (1998) Dual implication of 2',3'-cyclic nucleotide 3' phosphodiesterase as major autoantigen and C3 complement-binding protein in the pathogenesis of multiple sclerosis. J.Clin.Invest 101:1923-1931
    Abstract: multiple sclerosis (MS) is characterized by intra-blood-brain barrier immunoglobulin synthesis that persists lifelong. Subcellular fractionation and two-dimensional electrophoresis were used in conjunction with immune precipitation and immunoblotting to identify antigenic determinants for this immunoglobulin. We report that 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a protein associated with oligodendrocyte/myelin membranes, also present in lymphocytes and retina, is one major target for the humoral response. Antibodies to CNP are detected in sera of 74% of MS patients. The antibodies are IgM and are present in serum in high titer as well as in cerebrospinal fluid. The antibody response is temporally persistent, consistent with systemic immune activation and persistent antigenic stimulation. Moreover, CNP is isolated as an immune complex from MS brain. CNP is expressed as two isoforms, with CNPII identical to CNPI but with a 20-amino acid extension at the amino terminus of CNPII; however, the antibody response is exclusively restricted to CNPI. In contrast, both isoforms bind the C3 complement, providing a plausible mechanism in MS central nervous system (CNS) for opsonization of myelin membrane CNP, mediated via the C3 receptor, and phagocytosis of CNP-Ig immune complexes, mediated by membrane Ig Fc receptors of macrophages and CNS Microglia

  278. Walton M, Saura J, Young D, MacGibbon G, Hansen W, Lawlor P, Sirimanne E, Gluckman P, Dragunow M (1998) CCAAT-enhancer binding protein alpha is expressed in activated Microglial cells after brain injury. Brain Res.Mol.Brain Res. 61:11-22
    Abstract: Microglial cells play important roles in brain injury and repair and are implicated in diseases such as Alzheimer's disease, Creutzfeldt-Jacob disease, multiple sclerosis, the Aids Dementia Complex and stroke. Despite their importance in neuropathology, the underlying molecular basis for the activation of Microglia after brain injury is not understood. We show, using RT-PCR, in situ hybridisation, immunocytochemistry, and electrophoretic mobility shift assay, that the CCAAT-enhancer binding protein alpha (C/EBP alpha), a sequence specific DNA-binding protein, is induced in Microglial cells, but not astrocytes or neurons, after hypoxic-ischemic brain injury. These results suggest that C/EBP alpha might regulate gene expression and consequentially have a role in the activation and/or proliferation of Microglia following brain injury

  279. Wege H, Schluesener H, Meyermann R, Barac-Latas V, Suchanek G, Lassmann H (1998) Coronavirus infection and demyelination. Development of inflammatory lesions in Lewis rats. Adv.Exp.Med.Biol. 440:437-444
    Abstract: Coronavirus infections of rodents can cause diseases of the central nervous system characterised by inflammatory demyelination. The lesions mimick in many aspects the pathology of multiple sclerosis in humans and of other neurological diseases. As an animal model for demyelination, we studied the MHV-JHM induced encephalomyelitis of Lewis rats. The pathomorphological analysis revealed patterns of lesions which developed in stages. Infected oligodendrocytes were first destroyed by necrosis. Later stages were characterized by demyelinated plaques. In the center of plaques, no virus antigen was found and oligodendrocytes were mainly destroyed by apoptosis. At the edge of plaques, virus antigen was expressed in parallel to infiltrations consisting of lymphocytes and macrophages. The prevailing mechanisms leading to demyelination may change individually and during defined stages of the disease. The transcriptional expression of chemoattractants and other mediators of inflammation was studied by semiquantitative RT-PCR. Virus induced inflammatory demyelination was accompanied by high expression of a relatively novel cytokine, the endothelial monocyte activating polypeptide II (EMAP II). By immunocytochemistry, EMAP II was detected in parenchymal Microglia located both within the lesions and in unaffected areas. Furthermore, the level of transcriptional expression of the regulatory calcium binding S100 proteins MRP8, MRP14 and CP10 was associated with inflammatory demyelination and expression of IFN gamma, IL-2, TNF alpha, and iNOS

  280. Xiao BG, Diab A, Zhu J, van der MP, Link H (1998) Astrocytes induce hyporesponses of myelin basic protein-reactive T and B cell function. J.Neuroimmunol. 89:113-121
    Abstract: We have isolated infiltrating mononuclear cells (inMNC) and lymph node MNC (lnMNC) from Lewis rats with actively induced experimental allergic encephalomyelitis (EAE), and compared their responses to myelin basic protein (MBP). MBP-induced proliferation and MBP-specific IgG secreting cells were lower in inMNC compared to lnMNC, while MBP-reactive IFN-gamma secreting cells in inMNC were higher. Using an in vitro culture system, we observed that astrocytes derived from newborn Lewis rats not only suppressed T cell proliferation and IFN-gamma production but also reduced MBP-specific IgG production by B cells. Astrocyte-derived soluble factor (s), rather than direct cell-to-cell interactions, seems to be responsible for the inhibitory effect. Supernatants from IFN-gamma-stimulated astrocytes exhibited stronger suppressive effects than supernatants from unstimulated astrocytes, whereas supernatants from Microglia did not cause downregulation of T and B cell functions. These results indicate that astrocytes are major effector cells in inhibiting functions of MBP-reactive T and B cells. Astrocytes down-regulated expression of ICAM-1 and MHC class II in lnMNC, but did not induce apoptosis of lnMNC. The results in the present study do not exclude the possibility that astrocytes induce T cell apoptosis in a cognate fashion. Taken together, the inhibitory properties of astrocytes may contribute to the confinement of inflammatory lesions in multiple sclerosis and EAE. Our report compares immunoreactivities of inMNC and lnMNC in EAE and elucidates the role of astrocytes in the inactivation of MBP-reactive T and B cells

  281. Xiao BG, Bail XF, Zhang GX, Hedlund G, Link H (1998) Linomide-mediated protection of oligodendrocytes is associated with inhibition of nitric oxide production and IL-1beta expression in Lewis rat glial cells. Neurosci.Lett. 249:17-20
    Abstract: Linomide is a synthetic immunomodulator that down-regulates autoimmune response without inducing systemic immunosuppression. Linomide effectively inhibits severe experimental autoimmune diseases, like experimental allergic encephalomyelitis (EAE), a model of multiple sclerosis (MS). Here we report that Linomide suppresses nitric oxide (NO) production by Microglia and astrocytes derived from newborn rats and prevented oligodendrocyte damage. Linomide strongly inhibited interleukin (IL) 1 betamRNA expression on glial cells, suggesting a potential mechanism for inhibition of NO production by Linomide. These results demonstrate that Linomide-mediated inhibition of NO production by glial cells could explain the preventive and therapeutic effects of Linomide in EAE and perhaps also MS. However, Linomide at higher dose [correction of doss] (10(-5) M) resulted in direct oligodendrocyte damage

  282. Zhou L, Trapp BD, Miller RH (1998) Demyelination in the central nervous system mediated by an anti-oligodendrocyte antibody. J.Neurosci.Res. 54:158-168
    Abstract: The factors responsible for the major demyelinating disease of the central nervous system (CNS), multiple sclerosis, are poorly defined. Although T-cell-mediated immune responses play a pivotal role in establishing the inflammatory response, humoral factors also may be critical in disease progress. We have isolated a mouse monoclonal antibody (mAb 2B10) that recognizes a cell-surface molecule expressed exclusively by rat oligodendrocytes, the cells responsible for the formation and maintenance of CNS myelin. In cultures of neonatal rat spinal cord, mAb 2B10 specifically mediated oligodendrocyte cell death in the absence of complement. In the current study, mAb 2B10-producing hybridoma cells were implanted into adult rat brain ventricles, and the effect of mAb 2B10 on CNS cytoarchitecture was examined. In the optic nerves of mAb 2B10-treated animals, there was significant focal myelin degeneration near the optic chiasm. Axons in the myelin degenerate regions were largely healthy. There was no significant infiltration of hematopoietic-derived cells into the affected regions, but Microglia were activated focally and phagocytosed the collapsed myelin. This study demonstrates that an antibody directed against myelin-forming cells induces CNS demyelination and supports the hypothesis that autoantibodies may play a role in CNS demyelinating diseases

  283. Zhou L, Miller RH (1998) Antibody-mediated oligodendrocyte cell death requires an astrocyte-derived cosignal. J.Neurosci.Res. 52:137-148
    Abstract: We have described a monoclonal antibody (mAb), 2B10, that identifies a cell-surface protein expressed only on oligodendrocytes, the myelin-forming cells in the vertebrate central nervous system. To examine the effect of mAb 2B10 on oligodendrocyte development and survival, purified antibody was added to dissociated cultures of neonatal rat spinal cord. Addition of mAb 2B10 induced significant cell death, with a reduction of approximately 70% in the number of differentiated oligodendrocytes. The number of astrocytes was unaltered. Addition of mAb 2B10 did not affect the proliferation or differentiation of oligodendrocyte precursors. MAb 2B10-induced death of differentiated oligodendrocytes was independent of complement but did require an environmental signal. In purified oligodendrocyte cultures, binding of the antibody to oligodendrocytes did not induce cell death. Conditioned medium and transwell coculture experiments indicated that the required environmental signals were not soluble. By contrast, when oligodendrocytes were cocultured with astrocytes, addition of mAb 2B10 specifically induced cell death of differentiated oligodendrocytes, suggesting that a locally acting cosignal from astrocytes was required to facilitate the cell death. This cosignal was provided by live astrocytes but not by fixed astrocytes, Microglia, or fibroblasts. Such antibody-induced oligodendrocyte cell death may explain in part the loss of myelin-forming cells in demyelination conditions, such as multiple sclerosis

  284. Anthony DC, Ferguson B, Matyzak MK, Miller KM, Esiri MM, Perry VH (1997) Differential matrix metalloproteinase expression in cases of multiple sclerosis and stroke. Neuropathol.Appl.Neurobiol. 23:406-415
    Abstract: multiple sclerosis (MS) and stroke pathology are characterized blood-brain barrier breakdown, leucocyte emigration, and tissue destruction. Each process is thought to involve the matrix metalloproteinases (MMP), but little is known of their expression. We undertook to investigate whether MMP expression is dependent on the nature of the CNS lesion and whether expression would coincide with the histopathology. MS or cerebral-infarct tissue was examined for the presence of gelatinase-A, gelatinase-B, matrilysin and stromelysin-1. Gelatinases A and B and matrilysin expression was found to be up-regulated in Microglia/macrophages within acute MS lesions. In active-chronic MS lesions, matrilysin and gelatinase-A expression was pronounced in the active borders. In chronic MS lesions, the expression of matrilysin was confined to macrophages within perivascular cuffs. The pattern of MMP expression in infarct lesions differed considerably. Gelatinase-B was strongly expressed by neutrophils in tissue from patients up to 1 week after an infarct, whereas gelatinase-A and matrilysin staining was much less marked. From 1 week to 5 years, neutrophils were absent and the large number of macrophages present were expressing matrilysin and gelatinase A. Only a low level of gelatinase-A and matrilysin expression was observed in normal brain controls. Thus, MMPs are expressed in inflammatory lesions in the CNS, but their individual expression is dependent on the nature and chronicity of the lesion. However, the general pattern of expression, in perivascular cuffs and in active lesions, supports a role for these enzymes as mediators of blood-brain barrier breakdown and tissue destruction, both in MS and in cerebral ischaemia

  285. Benveniste EN (1997) Role of macrophages/Microglia in multiple sclerosis and experimental allergic encephalomyelitis. J.Mol.Med. 75:165-173
    Abstract: One of the characteristic features of Microglia is their rapid activation in response to injury, inflammation, neurodegeneration, infection, and brain tumors. This review focuses on the role of the Microglia in multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the central nervous system (CNS), and in the animal model of MS, experimental allergic encephalomyelitis (EAE). Microglial activation in MS and EAE is thought to contribute directly to CNS damage through several mechanisms, including production of proinflammatory cytokines, matrix metalloproteinases, and free radicals. In addition, activated Microglia serve as the major antigen-presenting cell in the CNS, likely contributing to aberrant immune reactivity at this site. A mechanistic understanding of the way in which Microglia are activated and ultimately inhibited is crucial for the formulation of therapeutic modalities to treat MS and other CNS autoimmune disease

  286. Bonetti B, Pohl J, Gao YL, Raine CS (1997) Cell death during autoimmune demyelination: effector but not target cells are eliminated by apoptosis. J.Immunol. 159:5733-5741
    Abstract: The Fas and FasL apoptotic pathway was investigated by protein immunohistochemistry, flow cytometry, and reverse transcriptase-PCR analysis to assess whether it is involved in the elimination of target and/or effector cells from the central nervous system (CNS) during adoptively transferred chronic relapsing experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. In addition to Fas and FasL, we studied Bax, an intracellular protein of the apoptotic cascade, the Bax antagonist and anti-apoptotic molecule Bcl-2, and DNA fragmentation, the final step in the apoptotic pathway. Infiltrating CD4+ T cells and parenchymal Microglia expressed Fas, FasL, and Bax, and about half of these cells showed DNA fragmentation, a combination indicative of ongoing apoptosis. Using flow cytometry and reverse transcriptase-PCR, a positive correlation was seen between disease activity and up-regulation of the Fas system; in fact, Fas and FasL were expressed at low levels at the onset of EAE and increased at the height of disease to involve about one-third of all infiltrating lymphocytes. In the normal CNS, Fas immunoreactivity was constitutively present at low levels on oligodendrocytes and was up-regulated in the CNS during the course of EAE. However, oligodendrocytes showed no Bax reactivity or DNA fragmentation and expressed high levels of Bcl-2, as did the majority of infiltrating CD3+ cells, a pattern inconsistent with apoptosis. Thus, while molecules of the apoptotic cascade are well represented in the CNS during EAE, their expression correlates with elimination of infiltrating cells and Microglia, not the myelinating cell, the oligodendrocyte

  287. Bonetti B, Raine CS (1997) multiple sclerosis: oligodendrocytes display cell death-related molecules in situ but do not undergo apoptosis. Ann.Neurol. 42:74-84
    Abstract: To investigate whether apoptosis is involved in the fate of oligodendrocytes in chronic multiple sclerosis lesions, the pro-apoptotic molecules fas and tumor necrosis factor receptors and the anti-apoptotic molecule bcl-2 were examined by immunohistochemistry, and DNA fragmentation was assessed by an end labeling technique. Fas and both tumor necrosis factor receptors were preferentially expressed on oligodendrocytes in multiple sclerosis lesions, this phenotype being more evident at the lesion edge. The ligand for fasL, was constitutively present at high levels on Microglia. The anti-apoptotic molecule bcl-2 was selectively expressed on oligodendrocytes in silent lesions and on astrocytes in active lesions. These molecules were also detected in control material, albeit at lower levels. In chronic active lesions, a few inflammatory cells displayed fas reactivity, whereas the majority expressed bcl-2. DNA fragmentation was found in a number of infiltrating cells and some Microglia, whereas, with one possible exception, oligodendrocytes showed no evidence of apoptosis. Thus, while apoptosis is involved in the elimination of infiltrating cells, it plays little or no role in oligodendrocyte depletion in multiple sclerosis, a process that may be related to a lytic pathway. In addition, Microglia constitutively displayed the ligand for fas, and appeared to be the major effector cell population in the central nervous system

  288. Cannella B, Sizing ID, Benjamin CD, Browning JL, Raine CS (1997) Antibodies to lymphotoxin alpha (LT alpha) and LT beta recognize different glial cell types in the central nervous system. J.Neuroimmunol. 78:172-179
    Abstract: The cytokine lymphotoxin (LT) is known to exist in two forms, secreted LT alpha and a membrane-bound LT alpha/beta complex. LT alpha shares the same receptor as tumor necrosis factor alpha and LT beta is recognized by its receptor, LT betaR. Since LT has been associated with oligodendrocyte pathology, the present study has examined the expression of these molecules by immunocytochemistry in diseased and normal CNS tissue, with a panel of monoclonal antibodies (mAb) to LT alpha, LT beta and LT betaR. Of three mAb to LT beta, two (B27 and C37) gave specific membrane staining on astrocytes, as well as lymphocytes. The third anti-LT beta mAb, B9, was selectively immunoreactive for oligodendrocytes, suggesting specific recognition sites. The reactivity was not specific for multiple sclerosis (MS) since oligodendrocytes in normal and non-MS CNS tissue also displayed positivity. MAb to LT betaR reacted with astrocytes only, giving a punctate membrane staining pattern suggestive of receptor sites. MAb to LT alpha gave strong reactivity on lymphocytes in active MS lesions and weak reactivity on Microglia within lesion areas. These results show that mAb to LT alpha and LT beta recognize different cell types within the CNS. Furthermore, individual mAb against LT beta were capable of distinguishing between astrocytes and oligodendrocytes, perhaps indicative of different epitopes on LT beta. The presence of LT betaR on astrocytes suggests possible interactions between infiltrating lymphocytes and astrocytes via the LT pathway

  289. Chabot S, Williams G, Yong VW (1997) Microglial production of TNF-alpha is induced by activated T lymphocytes. Involvement of VLA-4 and inhibition by interferonbeta-1b. J.Clin.Invest 100:604-612
    Abstract: TNF-alpha is a proinflammatory cytokine involved in many inflammatory conditions such as Crohn's disease, rheumatoid arthritis, cachexia, AIDS, and multiple sclerosis (MS). TNF-alpha is produced mainly by cells of the macrophage lineage, which includes Microglia in the central nervous system. Here, we describe a mechanism through which TNF-alpha is generated by Microglia. We show that activated human T lymphocytes induce the Microglial production of TNF-alpha, and that is attenuated by a functional blocking antibody to CD49d, the alpha chain of the VLA-4 integrin on T cells. We also report that interferonbeta-1b (IFNbeta-1b), a drug that alleviates symptoms in MS, downregulates the expression of CD49d and reduces TNF-alpha production, mechanisms which can help account for its efficacy in MS

  290. Cossins JA, Clements JM, Ford J, Miller KM, Pigott R, Vos W, van d, V, De Groot CJ (1997) Enhanced expression of MMP-7 and MMP-9 in demyelinating multiple sclerosis lesions. Acta Neuropathol.(Berl) 94:590-598
    Abstract: The pathology of multiple sclerosis (MS) is characterised by breakdown of the blood-brain barrier accompanied by infiltration of macrophages and T cells into the central nervous system (CNS). Myelin is degraded and engulfed by the macrophages, producing lesions of demyelination. Some or all of these mechanisms might involve proteinases, and here we have studied the cellular localisation and distribution of two matrix metalloproteinases (MMPs), MMP-7 (matrilysin) and MMP-9 (92-kDa gelatinase), in the normal human CNS and active demyelinating MS lesions. Cryostat sections of CNS samples were immunostained with antisera to MMP-7 and MMP-9. In addition, non-radioactive in situ hybridisation (ISH) was performed using a digoxygenin-labelled riboprobe to detect the expression of MMP-7. MMP-7 immunoreactivity was weakly detected in Microglial-like cells in normal brain tissue sections, and was very strong in parenchymal macrophages in active demyelinating MS lesions. This pattern of expression was confirmed using ISH. MMP-7 immunoreactivity was not detected in macrophages in spleen or tonsil indicating that it is specifically induced in infiltrating macrophages in active demyelinating MS lesions. MMP-9 immunoreactivity was detected in a few small blood vessels in normal brain tissue sections, whereas many blood vessels stained positive in CNS tissue sections of active demyelinating MS lesions. The up-regulation of MMPs in MS may contribute to the pathology of the disease

  291. Cuzner ML (1997) Microglia in health and disease. Biochem.Soc.Trans. 25:671-673

  292. Dangond F, Windhagen A, Groves CJ, Hafler DA (1997) Constitutive expression of costimulatory molecules by human Microglia and its relevance to CNS autoimmunity. J.Neuroimmunol. 76:132-138
    Abstract: Human Microglia constitute the primary residential antigen presenting cells (APCs) in the central nervous system (CNS) and have the capacity of activating myelin reactive T-cells. T-cell activation requires two signals: first is the interaction of the T-cell receptor with the MHC-antigen complex and, secondly, contact of the CD28/CTLA4 T-cell surface molecules with the B7 family of costimulatory molecules on the APCs. We have previously shown high expression of B7.1 in early multiple sclerosis (MS) plaques, suggesting that acute T-cell-mediated CNS inflammation may require local B7.1 upregulation. We have now examined the expression of B7.1 and B7.2 costimulatory molecules on resting ex-vivo human Microglia isolated directly from biopsy specimens. We found constitutive expression of B7.2 but not B7.1 on resting Microglia, suggesting that B7.2 expression may lead to downregulation of pro-inflammatory Th1 T-cell responses in the normal brain

  293. De Groot CJ, Langeveld CH, Jongenelen CA, Montagne L, van d, V, Dijkstra CD (1997) Establishment of human adult astrocyte cultures derived from postmortem multiple sclerosis and control brain and spinal cord regions: immunophenotypical and functional characterization. J.Neurosci.Res. 49:342-354
    Abstract: We have successfully established highly enriched astrocyte cultures upon passaging of primary cultures derived from various regions of postmortem human adult brain and spinal cord. Tissues were collected at autopsies with relatively short postmortem times (3-9 hr) from multiple sclerosis (MS) and (normal) control cases. Immunocytochemical analysis showed that primary cultures were composed of colonies of oligoclonal cells that expressed the intermediate filament proteins glial fibrillary acidic protein (GFAP), vimentin, as well as glutamine synthetase (GS). Passaging the astrocytes did not affect their proliferating capacity as monitored by bromodeoxyuridine (BrdU) incorporation. Astrocyte-specific markers were stably expressed for at least 12 passages per individual tissue sample. Large numbers of GFAP-positive astrocytes were obtained from each sample and could be stored frozen and recultured. Very few macrophages/Microglial cells (1-3%) were present in the human adult astrocyte cultures, using a panel of macrophage-specific markers. However, the monoclonal antibodies (mAbs KP1, EBM1, 25F9) and lysozyme antiserum directed against lysosomal antigens strongly immunostained cultured astrocytes derived from MS and control cases, implicating that expression of these lysosomal antigens is not restricted to macrophages/ Microglial cells in human glial cell cultures. Interestingly, astrocytes derived from active demyelinated MS lesions showed an increased proliferating capacity compared to astrocytes derived from non-lesioned and normal brain and spinal cord regions, as shown with a microculture tetrazolium assay (MTT assay)

  294. Freedman MS, D'Souza S, Antel JP (1997) gamma delta T-cell-human glial cell interactions. I. In vitro induction of gammadelta T-cell expansion by human glial cells. J.Neuroimmunol. 74:135-142
    Abstract: gamma delta T-cells are found in increased proportion in multiple sclerosis (MS) white matter plaque infiltrates compared with peripheral blood or spleen, raising the possibility that they are either specifically attracted to lesion sites or, once present, are stimulated to expand. We have previously shown that human oligodendrocytes (OGC) preferentially express heat shock proteins (hsp), molecules to which gamma delta T-cells have been known to react and that in vitro expanded gamma delta T-cells can lyse OGC. We therefore investigated whether human glial cells, that differentially express hsp, could stimulate gamma delta T-cell expansion from peripheral blood. We compared the glial cell-induced expansion to cell lines which also differentially express hsp and have been shown to selectively stimulate gamma delta T-cell expansion (e.g. RPMI 8226, Daudi). We found that both OGC and human fetal astrocytes (hFA) expressed hsp and stimulated the preferential expansion of gamma delta T-cells to about the same extent as the hsp expressing cell lines RPMI 8226 or Daudi, in the presence of exogenous interleukin-2 (IL-2) but without any T-cell mitogen. Furthermore, the type of gamma delta T-cells expanded were of the V delta 2 subtype known to be particularly reactive to hsp. Microglia, U937 cell lines or purified myelin membranes, which express little or no hsp, did not support gamma delta T-cell growth. These results therefore suggest that OGC may contribute to the local expansion of gamma delta T-cells within MS plaques. Potential harmful effects of gamma delta T-cells on OGC may thereby contribute to the immunopathogenesis of MS demyelination

  295. Freedman MS, Bitar R, Antel JP (1997) gamma delta T-cell-human glial cell interactions. II. Relationship between heat shock protein expression and susceptibility to cytolysis. J.Neuroimmunol. 74:143-148
    Abstract: gamma delta T-cells have been implicated in the immunopathogenesis of multiple sclerosis (MS), possibly through interaction with heat shock proteins (hsp). We have previously demonstrated that human oligodendrocytes (OGC) express hsp on their surface and induce the proliferation and expansion of gamma delta T-cells. We also showed that gamma delta T-cells are highly cytolytic to OGC in vitro. The current study addresses whether gamma delta T-cell-induced cytotoxicity to OGC involves the recognition of hsp on OGC or some other ligand. We first compared the lytic potential for different human glial cells and found that gamma delta T-cells lysed OGC, Microglia and human fetal astrocytes to the same extent, despite the preferential expression of hsp only on OGC. This suggested that either hsp was not involved in cytolytic recognition or that more than one ligand exists. To address this we used cell lines that either shared OGC properties of hsp expression and the ability to stimulate gamma delta T-cells (RPMI 8226, Daudi) or did not (U937) in cold target competition assays with OGC. Results demonstrated that although all the cell lines were effectively killed by gamma delta T-cells, only the RPMI 8226 and Daudi cells were able to effectively compete for lysis with the OGC. These results support the notion that probably more than one ligand for gamma delta T-cell cytotoxic recognition exists but hsp could still be involved in gamma delta T-cell-induced lysis of OGC. Regulating the expression of hsp on OGC might therefore be a way of interfering with potential gamma delta T-cell-induced damage in MS

  296. Gay FW, Drye TJ, Dick GW, Esiri MM (1997) The application of multifactorial cluster analysis in the staging of plaques in early multiple sclerosis. Identification and characterization of the primary demyelinating lesion. Brain 120 ( Pt 8):1461-1483
    Abstract: Tissues from 13 exceptionally early cases of multiple sclerosis were studied to identify and characterize the primary demyelinating lesion, using a variety of histological and immunocytochemical methods. Multifactorial cluster analysis identified five significantly distinct lesion groups, which showed histological progression from simple Microglial lesions, predominating in tissues from the earliest cases, to complex hypercellular fully demyelinated plaques, chiefly associated with cases of intermediate duration. Quiescent lesions showing evidence of remyelination were found at all stages of the disease studied, but hypocellular inactive plaques, were associated with older cases. Evidence is presented that initial demyelination is effected by activated resident Microglia. Undegraded myelin is initially enveloped by membranes bearing fixed complexes of immunoglobulin and complement. In contrast with perivenous encephalomyelitis, in which demyelination was dominated by T-cell infiltration, multiple sclerosis lesions of comparable duration and maturity exhibited humoral immune reactions. Parenchymal CD4+ T-cell infiltration developed in association with subsequent plaque maturation. These results emphasize the need for lesion staging when multiple sclerosis tissues are being used in the investigation of pathogenic mechanisms, and suggest that further analysis of the oligoclonal B-cell response may be productive in the search for primary provoking antigens

  297. Hall GL, Wing MG, Compston DA, Scolding NJ (1997) beta-Interferon regulates the immunomodulatory activity of neonatal rodent Microglia. J.Neuroimmunol. 72:11-19
    Abstract: beta-interferon (beta-IFN) has both pro and anti-inflammatory properties, the balance of which leads to some suppression of disease activity in multiple sclerosis patients. Here, we examine the immunomodulation of neonatal rodent Microglia, the principal CNS accessory cell, by beta-IFN and consider the interaction of beta-IFN and gamma-interferon (gamma-IFN). beta-IFN and gamma-IFN inhibit Microglial proliferation. beta-IFN antagonises both gamma-IFN-induced upregulation of class II expression and the ability of gamma-IFN primed cells to mount a respiratory burst. In contrast, beta-IFN upregulates Microglial Fc receptor expression and augments tumour necrosis factor alpha secretion from suboptimally stimulated Microglia

  298. Hollsberg P (1997) Pathogenesis of chronic progressive myelopathy associated with human T-cell lymphotropic virus type I. Acta Neurol.Scand.Suppl 169:86-93
    Abstract: Human T-cell lymphotropic virus type I (HTLV-I) induces a chronic demyelinating disease known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). While only 0.25% of HTLV-I-infected individuals develop HAM/TSP, the mechanisms responsible for the progression of an HTLV-I carrier state to clinical disease are not clear. In particular, no specific sequence differences have been found between HTLV-I recovered from HAM patients and HTLV-I-infected carriers. Since CD4 T cells are the major reservoir of the virus, at least three hypotheses implicating CD4 T cells directly or indirectly have been proposed: 1) The cytotoxic hypothesis predicts that activated and HTLV-I-infected CD4 T cells migrate to the CNS and infect resident cells. Cytotoxic CD8 T cells may then recognize viral antigens on HTLV-I-infected CNS cells causing a cellularly mediated cytotoxic demyelination. 2) The autoimmune hypothesis predicts that either (a) virally reactive T cells crossreact with a CNS antigen, or (b) random infection of CD4 T cells eventually results in the infection of CNS-autoreactive CD4 T cells that, by virtue of the productive HTLV-I infection, become activated, expand and migrate to the CNS, where they encounter their antigen. This results in a specific immune response and demyelination, as is known to occur in experimental autoimmune encephalomyelitis. 3) The bystander damage hypothesis does not implicate a specific response against CNS cells. Instead this hypothesis suggests that the presence of IFN-gamma-secreting HTLV-I-infected CD4 T cells and their recognition by virally specific CD8 T cells in the CNS induce Microglia to secrete cytokines, such as TNF-alpha, which may be toxic for the myelin

  299. LeVine SM (1997) Iron deposits in multiple sclerosis and Alzheimer's disease brains. Brain Res. 760:298-303
    Abstract: Iron may contribute to the pathogenesis of neurological diseases by promoting oxidative damage. The localization of iron in multiple sclerosis (MS) and Alzheimer's disease (AD) brains was investigated to further the understanding of its pathogenic role in these disease states. Earlier studies, utilizing a standard Perls' stain, yielded conflicting reports regarding the distribution of iron deposits in MS brains, and a previous study on AD brains utilized a diaminobenzidine (DAB) enhanced version of this stain. In the present study, a modified version of the DAB-enhanced stain was used; it utilizes sodium borohydride, proteinase K, Triton X-100 and xylenes to increase the accessibility of tissue iron to histochemical reagents. This modified method can reveal iron deposits that are missed by the Perls' or DAB-enhanced Perls' stains. In addition to its normal deposition in oligodendrocytes and myelin, iron was detected in reactive Microglia, ameboid Microglia and macrophages in MS brains. In AD brains, three types of plaques were stained: dense core, clear core and amorphous plaques. Punctate staining was also observed in neurons in the corticies of AD brains. The structure accounting for punctate labeling may be damaged mitochondria, lipofuscin or amyloid deposits. Dense core plaques, clear plaques and punctate labeling were not detected in the previous AD study which utilized only the DAB-enhanced Perls' stain. The labeling of these additional structures illustrates the benefit of the modified method. In summary, the localization of iron deposition in MS and AD brains indicates potential sites where iron could promote oxidative damage in these disease states

  300. Menendez IB, Cerase J, Ceracchini C, Levi G, Aloisi F (1997) Analysis of B7-1 and B7-2 costimulatory ligands in cultured mouse Microglia: upregulation by interferon-gamma and lipopolysaccharide and downregulation by interleukin-10, prostaglandin E2 and cyclic AMP-elevating agents. J.Neuroimmunol. 72:83-93
    Abstract: Recent evidence indicates that membrane-bound costimulatory molecules of the B7 family are important for T-cell activation and are upregulated in IFN gamma-stimulated human Microglia and in multiple sclerosis active lesions. In this study we have performed a detailed analysis of B7-1 and B7-2 expression and regulation in cultured mouse glial cells using immunocytochemical and semi-quantitative reverse transcriptase-polymerase chain reaction techniques. In an immortalized mouse Microglial cell line (BV-2), expression of B7-1 and B7-2 was enhanced by interferon-gamma (IFN gamma). IFN gamma was a weak inducer of B7-2 mRNA and immunoreactivity in Microglia primary cultures obtained from the neonatal mouse brain, whereas lipopolysaccharide, tumour necrosis factor-alpha, colony-stimulating factors and interleukin-1 beta did not affect Microglial B7-2 expression. Combined IFN gamma and lipopolysaccharide treatment very effectively upregulated the B7-2 gene expression and immunoreactivity in Microglia, but not in astrocytes. In both glial cell types, expression of B7-1 was not induced by any of the above agents. Among known Microglia/macrophage deactivators, interleukin-10, prostaglandin E2 and cAMP-elevating agents, but not transforming growth factor-beta 1 and interleukin-4, inhibited B7-2 transcripts and immunoreactivity in IFN gamma/LPS-stimulated Microglia, thus suggesting possible paracrine and autocrine mechanisms for regulating the expression of this important T-cell costimulatory signal in the brain

  301. Morris MM, Dyson H, Baker D, Harbige LS, Fazakerley JK, Amor S (1997) Characterization of the cellular and cytokine response in the central nervous system following Semliki Forest virus infection. J.Neuroimmunol. 74:185-197
    Abstract: Cytokines are important mediators in the pathogenesis of central nervous system (CNS) inflammatory diseases including multiple sclerosis (MS), experimental allergic encephalomyelitis (EAE), viral encephalitis and virus induced demyelinating diseases. We have used immunohistochemical techniques to characterize the mononuclear cell infiltrate and cytokine profiles in the CNS following infection of mice with the demyelinating A7(74) strain of Semliki Forest virus (SFV), an important viral model of MS. Mononuclear cell infiltrates in the CNS, first observed at 3 days and maximal during clearance of infectious virus, were comprised predominantly of CD8+ lymphocytes. F4/80+ macrophage/Microglia and CD45/B220+ B lymphocytes were most numerous during the subsequent phase of demyelination. CD4+ T-lymphocytes were observed at low levels throughout infection. By immunostaining MHC class I, IL-1beta , IL-3 and TGF beta1 were constitutively expressed in normal mice and were upregulated following infection. MHC class II, IL-1alpha, IL-2, IL-2R, TNF-alpha and IL-6 were strongly upregulated in the CNS of SFV-infected mice and mice with chronic relapsing EAE. The spatial and temporal distribution of these cytokines during the course of disease was analysed. Whereas IL-1alpha, IL-1beta, IL-10, and TGF beta1 were observed on day 3 following infection GMCSF, IL-2 and TNF alpha were first apparent at day 7 when the cellular infiltration in the CNS was most intense. In contrast IFN gamma and IL-6 were first observed on day 10 prior to the demyelination phase of disease. Cytokines in the lesions of demyelination suggest a role in the pathogeneisis of myelin damage. Based on cytokine profiles no clear bias of either a Th1 or Th2 response was observed in the CNS during infection

  302. Nagra RM, Becher B, Tourtellotte WW, Antel JP, Gold D, Paladino T, Smith RA, Nelson JR, Reynolds WF (1997) Immunohistochemical and genetic evidence of myeloperoxidase involvement in multiple sclerosis. J.Neuroimmunol. 78:97-107
    Abstract: The myeloperoxidase enzyme (MPO) is expressed specifically in myeloid cells and catalyzes the formation of hypochlorous acid and other cytotoxic oxidants. We previously reported that two alleles of MPO exist which differ in promoter strength due to a base difference in an Alu-encoded hormone response element. The present study shows that the higher expressing MPO genotype is overrepresented in early onset multiple sclerosis in females, implicating MPO in this demyelinating disease. Contrary to the general conception that macrophages lack MPO, immunohistochemical analysis shows that MPO is present in Microglia/macrophages in and around MS lesions as shown by colocalization with major histocompatibility antigens HLA-DR and phagocytized myelin. Also, MPO mRNA sequences are detected in cDNA derived from isolated human adult Microglia. This is the first evidence that MPO is present in Microglia/macrophages at MS lesions, that MPO gene expression occurs in Microglia and that MPO plays a role in MS pathogenesis as shown by the allelic disequilibrium in early onset disease

  303. Njenga MK, Asakura K, Hunter SF, Wettstein P, Pease LR, Rodriguez M (1997) The immune system preferentially clears Theiler's virus from the gray matter of the central nervous system. J.Virol. 71:8592-8601
    Abstract: Infection of susceptible strains of mice with Daniel's (DA) strains of Theiler's murine encephalomyelitis virus (DAV) results in virus persistence in the central nervous system (CNS) white matter and chronic demyelination similar to that observed in multiple sclerosis. We investigated whether persistence is due to the immune system more efficiently clearing DAV from gray than from white matter of the CNS. Severe combined immunodeficient (SCID) and immunocompetent C.B-17 mice were infected with DAV to determine the kinetics, temporal distribution, and tropism of the virus in CNS. In early disease (6 h to 7 days postinfection), DAV replicated with similar kinetics in the brains and spinal cords of SCID and immunocompetent mice and in gray and white matter. DAV RNA was localized within 48 h in CNS cells of all phenotypes, including neurons, oligodendrocytes, astrocytes, and macrophages/Microglia. In late disease (13 to 17 days postinfection), SCID mice became moribund and permitted higher DAV replication in both gray and white matter. In contrast, immunocompetent mice cleared virus from the gray matter but showed replication in the white matter of their brains and spinal cords. Reconstitution of SCID mice with nonimmune splenocytes or anti-DAV antibodies after establishment of infection demonstrated that both cellular and humoral immune responses decreased virus from the gray matter; however, the cellular responses were more effective. SCID mice reconstituted with splenocytes depleted of CD4+ or CD8+ T lymphocytes cleared virus from the gray matter but allowed replication in the white matter. These studies demonstrate that both neurons and glia are infected early following DAV infection but that virus persistence in the white matter is due to preferential clearance of virus from the gray matter by the immune system

  304. Oleszak EL, Katsetos CD, Kuzmak J, Varadhachary A (1997) Inducible nitric oxide synthase in Theiler's murine encephalomyelitis virus infection. J.Virol. 71:3228-3235
    Abstract: We investigated the role of inducible nitric oxide synthase (iNOS) in Theiler's murine encephalomyelitis virus (TMEV) infection of susceptible (SJL) and resistant (C57BL/6 [B6]) strains of mice. TMEV is an excellent model of virus-induced demyelinating disease, such as multiple sclerosis (MS). Previous studies of others have suggested that NO may play a role in the pathogenesis of demyelinating disease. The presence and level of iNOS were determined in the brains and spinal cords of SJL and B6 TMEV-infected mice by the following methods: (i) PCR amplification of iNOS transcripts, followed by Southern blotting with an iNOS-specific probe, and (ii) immunohistochemical staining with an anti-iNOS-specific affinity-purified rabbit antibody. iNOS-specific transcripts were determined in the brains and spinal cord of both SJL and B6 TMEV-infected mice on days 0 (control), days 3, 6, and 10 (encephalitic stage of disease), and days 39 to 42, 66, and 180 (demyelinating phase) postinfection (p.i.). iNOS-specific transcripts were found in the brains and spinal cords of both SJL and B6 TMEV-infected mice at 6, 10, and 39 (SJL) days p.i., but they were absent in mock-infected mice and in TMEV-infected SJL and B6 mice at 0, 3, 66, and 180 days p.i. Immunohistochemical staining confirmed the presence of iNOS protein in both TMEV-infected SJL and B6 mice at days 6 and 10 p.i., but not at days 0, 3, 66, and 180 days p.i. Weak iNOS staining was also observed in TMEV-infected SJL mice at 42 days p.i. iNOS-positive staining was found in reactive astrocytes surrounding areas of necrotizing inflammation, particularly in the midbrain. Weak iNOS staining was also observed in cells of the monocyte/macrophage lineage in areas of parenchymal inflammation and necrosis (mesencephalon) and in leptomeningeal and white matter perivascular infiltrates of the spinal cord. Rod-shaped Microglia-like cells and foamy macrophages (myelin-laden) were iNOS negative. These results suggest that NO does not play a direct role in the late phase of demyelinating disease in TMEV-infected mice

  305. Parkinson JF, Mitrovic B, Merrill JE (1997) The role of nitric oxide in multiple sclerosis. J.Mol.Med. 75:174-186
    Abstract: During the past decade nitric oxide has emerged as an important mediator of physiological and pathophysiological processes. Elevated nitric oxide bio-synthesis has been associated with nonspecific immune-mediated cellular cytotoxicity and the pathogenesis of chronic, inflammatory autoimmune diseases including rheumatoid arthritis, insulin-dependent diabetes, inflammatory bowel disease, and multiple sclerosis. Recent evidence suggests, however, that nitric oxide is also immunoregulatory and suppresses the function of activated proinflammatory macrophages and T lymphocytes involved in these diseases. This article reviews the role of nitric oxide in the biology of central nervous system glial cells (astrocytes and Microglia) as it pertains to the pathogenesis of multiple sclerosis in humans and experimental allergic encephalitis, the animal model of this disease. Although nitric oxide has been clearly implicated as a potential mediator of Microglia-dependent primary demyelination, a hallmark of multiple sclerosis, studies with nitric oxide synthase inhibitors in the encephalitis model have been equivocal. These data are critically reviewed in the context of what is know from clinical research on the nitric oxide pathway in multiple sclerosis. Specific recommendations for future preclinical animal model research and clinical research on the nitric oxide pathway in patients are suggested. These studies are necessary to further define the role of nitric oxide in the pathology of multiple sclerosis and to fully explore the potential for nitric oxide synthase inhibitors as novel therapeutics for this disease

  306. Phillips MJ, Needham M, Weller RO (1997) Role of cervical lymph nodes in autoimmune encephalomyelitis in the Lewis rat. J.Pathol. 182:457-464
    Abstract: Lymphocytes enter the central nervous system (CNS) in response to virus infections and in autoimmune diseases, such as multiple sclerosis (MS), but the origin of such lymphocytes is unclear. This study investigates the role of the cervical lymph nodes as a source of lymphocytes involved in experimental autoimmune disease of the brain. Acute active experimental autoimmune encephalomyelitis (EAE) is used as a model for the autoimmune aspects of MS and is characterized by lymphocyte and monocyte invasion and Microglial activation, mainly in the spinal cord, 12-15 days post-inoculation (dpi) of antigen. Few lesions occur in the cerebral hemispheres in acute EAE, but a cryolesion to the surface of the brain 8 dpi results in a six-fold enhancement of cerebral EAE. The present study tests the hypothesis that cervical lymphadenectomy will reduce the enhancement of cerebral EAE induced by a cryolesion. Acute EAE was induced in 25 Lewis rats and a cryolesion to the brain, 8 dpi, in 16 rats was immediately followed by either cervical lymphadenectomy (n = 8) or sham lymphadenectomy (n = 8). The severity of EAE at 15 dpi, in the brain and spinal cord, was evaluated using immunocytochemistry for T lymphocytes (W3/13) and MHC class II expression (OX6). The results of the study showed that cervical lymphadenectomy reduced the level of cerebral EAE induced by a cryolesion by 40 per cent when compared with the sham-operated animals (P < 0.01). This suggests that cervical lymph nodes play a pivotal role in the induction of EAE in the brain, possibly as a site for 'priming' T cells to target the brain. Investigation of the interrelationships between cervical lymph nodes and the brain in man may lead to new therapeutic strategies for multiple sclerosis

  307. Pratt BM, McPherson JM (1997) TGF-beta in the central nervous system: potential roles in ischemic injury and neurodegenerative diseases. Cytokine Growth Factor Rev. 8:267-292
    Abstract: The Transforming Growth Factor-betas (TGF-beta) are a group of multifunctional proteins whose cellular sites of production and action are widely distributed throughout the body, including the central nervous system (CNS). Within the CNS, various isoforms of TGF-beta are produced by both glial and neural cells. When evaluated in either cell culture or in vivo models, the various isoforms of TGF-beta have been shown to have potent effects on the proliferation, function, or survival of both neurons and all three glial cell types, astrocytes, Microglia and oligodendrocytes. TGF-beta has also been shown to play a role in several forms of acute CNS pathology including ischemia, excitotoxicity and several forms of neurodegenerative diseases including multiple sclerosis, Parkinson's disease, AIDS dementia and Alzheimer's disease

  308. Sarchielli P, Orlacchio A, Vicinanza F, Pelliccioli GP, Tognoloni M, Saccardi C, Gallai V (1997) Cytokine secretion and nitric oxide production by mononuclear cells of patients with multiple sclerosis. J.Neuroimmunol. 80:76-86
    Abstract: Several experimental findings suggest a potential role of excessive nitric oxide (NO) production by macrophages, Microglia and astrocytes in the pathogenesis of demyelinating lesions in MS. We assessed the production of nitrites by peripheral blood mononuclear cells (PBMCs) of 15 MS patients (10 F and 5 M) with the R-R form (EDSS: 1-3.0) and in 15 age-matched control subjects. 9 out of the 15 MS patients showed active lesions in MRI at the time of examination. 7 patients were also monitored at the onset, during and following a clinical relapse. Secretion of cytokines by PBMCs was assessed at the basal time and after 24 h of incubation with lipopolysaccharide (LPS). The production of nitrites in the supernatants of PBMCs stimulated and not stimulated with lipopolysaccharide was evaluated. The secretion of IL1 beta, IFN-gamma, TNF-alpha, IL-6 IL-10 and TGF-beta by PBMCs was detected using ELISA methods. The production of NO, both basal and stimulated, was significantly higher in the patients with active lesions than in those without active lesions (p < 0.01). No significant difference was evident between the basal and LPS-stimulated production of NO between control subjects and MS patients without active lesions. During relapses there was a significant increase in NO production by PBMCs compared to the clinical stable stage of the disease (p < 0.0001). This increase was significantly greater in the early stage of relapse than in the late stage (p < 0.04). A decline of NO levels was observed during recovery. Steroid treatment induced a significant decrease in the PBMC NO production of MS patients during exacerbations (p < 0.01). The levels of IL-1 beta, IFN-gamma and TNF-alpha are significantly higher in the supernatants of the PBMCs which produced greater amounts of NO (p < 0.02, p < 0.03, p < 0.01, respectively). On the other hand, NO levels were negatively related to IL-10 and TGF-beta production (R = -75, p < 0.0001 and R = -0.79, p < 0.0001, respectively). The increase production of NO by peripheral blood mononuclear cells demonstrated in our study to be associated with increased production of proinflammatory cytokines could therefore be considered to be a marker of mononuclear cell activation in the peripheral blood of MS patients and, indirectly, of disease activity. Its increased secretion during T cell and monocyte homing in the CNF could contribute to the damage to the blood-brain barrier and the subsequent cytokine-mediated cytotoxic effect to myelin and oligodendrocytes in the white matter of MS patients

  309. Smith T, Hewson AK, Kingsley CI, Leonard JP, Cuzner ML (1997) Interleukin-12 induces relapse in experimental allergic encephalomyelitis in the Lewis rat. Am.J.Pathol. 150:1909-1917
    Abstract: Acute, monophasic experimental allergic encephalomyelitis (EAE) in the Lewis rat shows pathological similarities to the human disease multiple sclerosis (MS). Rats that recover from EAE are essentially resistant to disease reinduction, unlike MS in which relapses are frequently associated with common bacterial and viral infections. As macrophage-derived interleukin (IL)-12 is a critical component of innate resistance to bacterial infection and appears to directly activate encephalitogenic T cells in vivo, the ability of this cytokine to reinduce paralysis in EAE was examined. Paralytic disease was exacerbated by intraperitoneal IL-12 administration and could be reinduced up to 1 week after recovery from the primary clinical episode. Concomitant with worsening of initial clinical signs and relapse was an increase in the ratio of macrophages to T cells in brain stem perivascular cuffs and the expression of inducible nitric oxide synthase in cells with both macrophage and Microglial morphology. These findings suggest that IL-12 may contribute to macrophage-mediated disease exacerbation and relapse in patients with MS

  310. Sriram S, Rodriguez M (1997) Indictment of the Microglia as the villain in multiple sclerosis. Neurology 48:464-470

  311. van der Veen RC, Hinton DR, Incardonna F, Hofman FM (1997) Extensive peroxynitrite activity during progressive stages of central nervous system inflammation. J.Neuroimmunol. 77:1-7
    Abstract: Nitric oxide (NO) production has been associated with disease activity in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). This free radical can be transformed by superoxide to peroxynitrite, an extremely toxic oxidant which causes lipid peroxidation. In addition, peroxynitrite nitrates tyrosine residues, resulting in nitrotyrosine, which can be identified immunohistochemically. The results of this study indicate that peroxynitrite is formed very early during EAE development, correlating with clinical disease activity. Nitrotyrosine-positive cells display a widespread distribution in brain and spinal cord during severe disease and are associated with both perivascular infiltrates and parenchymal sites. Double-staining procedures demonstrated that a subpopulation of CD11b-positive cells (macrophages/Microglia) reacted with nitrotyrosine antibodies. Immunostaining for inducible NO synthase demonstrated a similar distribution as nitrotyrosine staining. These experiments indicate that peroxynitrite is formed during progressive stages of disease activity

  312. Vowinckel E, Reutens D, Becher B, Verge G, Evans A, Owens T, Antel JP (1997) PK11195 binding to the peripheral benzodiazepine receptor as a marker of Microglia activation in multiple sclerosis and experimental autoimmune encephalomyelitis. J.Neurosci.Res. 50:345-353
    Abstract: Activated glial cells are implicated in regulating and effecting the immune response that occurs within the CNS as part of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). The peripheral benzodiazepine receptor (PBR) is expressed in glial cells. We examined the utility of using in vitro and in vivo ligand binding to the PBR as a measure of lesion activity in autoimmune CNS demyelinating diseases. Applying a combined autoradiography and immunohistochemical approach to spinal cord and brain tissues from mice with EAE, we found a correlation at sites of inflammatory lesions between [3H]-PK11195 binding and immunoreactivity for the activated Microglial/macrophage marker Mac-1/CD11b. In MS tissues, [3H]-PK11195 binding correlated with sites of immunoreactivity for the Microglial/macrophage marker CD68, at the edges of chronic active plaques. Positron emission tomography (PET) imaging with [11C]-PK11195 showed ligand uptake only at sites of active MS lesions defined by magnetic resonance imaging criteria. Our results indicate the potential to develop markers suitable for both in vitro and in vivo use, which will serve to help correlate phenotypic and functional properties of cells which participate in disease or injury responses within the CNS

  313. Weller RO, Phillips MJ, Kida S, Zhang ET (1997) [Immunologic significance of lymphatic drainage of the brain]. Bull.Acad.Natl.Med. 181:661-667
    Abstract: Despite the evidence for immunological reactions in the human CNS, in viral encephalitis and in multiple sclerosis, connections between the brain and the immune system are poorly understood. In rodents, tracers injected into the interstitial fluid of the brain drain to the cervical lymph nodes by perivascular pathways in the brain and nasal lymphatics. Similar pathways could serve as lymphatics in the human brain. In the present study, we test the hypothesis that lymphatic drainage of the brain and cervical lymph nodes play a key role in T-cell mediated immunity of the brain. Experimental allergic encephalomyelitis (EAE) was induced in Lewis rats by the injection of guinea pig spinal cord homogenate in complete Freund's adjuvant into the foot pads. This resulted in paralysis of the hind limbs and infiltration of lymphocytes and Microglial activation centred mainly on the spinal cord; little inflammation was seen in the cerebrum. When a brain wound, in the form of cryolesion, was inflicted on one cerebral hemisphere, 8 days after the induction of EAE, there was a 6-fold enhancement of EAE lesions in the brain. This enhancement was reduced by 40% cervical lymphadenectomy at the time of the cryolesion. These results suggest that cervical lymph nodes play a pivotal role in cerebral EAE and may be a major source of brain-directed lymphocytes. If similar mechanisms apply in man, study of cervical lymphocytes and their manipulation could open new therapeutic avenues for the treatment of multiple sclerosis

  314. Battistini L, Fischer FR, Raine CS, Brosnan CF (1996) CD1b is expressed in multiple sclerosis lesions. J.Neuroimmunol. 67:145-151
    Abstract: Recent observations have shown that CD1 molecules act as restriction elements in the presentation of antigens to specialized subsets of T cells. To examine the expression of CD1 molecules in multiple sclerosis (MS) lesions, frozen sections of central nervous system (CNS) tissues from nine MS and three other neurological disease (OND) patients, one patient with Wilson's disease, and one non-neurological control were stained by immunocytochemistry. In chronic-active MS lesions, CD1b immunoreactivity was prominent on perivascular inflammatory cells whereas macrophages within the lesion showed little reactivity. At the lesion edge, intense immunoreactivity for CD1b was found on hypertrophic astrocytes. High level expression of CD1b in MS lesions was found to colocalize with the presence of GM-CSF in astrocytes. In chronic-silent lesions, CD1b expression was found on only a few perivascular astrocytic foot processes and the occasional perivascular macrophage. CD1b was not found in the tissues studied for control purposes. In contrast, MHC class II expression was detected on Microglia in all tissues examined. The relatively low level expression of CD1b in normal-appearing tissues, chronic-silent lesions and in the OND controls supports the conclusion that the expression of CD1b in active MS lesions is significantly upregulated and could contribute to lesion development

  315. Bauer J, Ruuls SR, Huitinga I, Dijkstra CD (1996) The role of macrophage subpopulations in autoimmune disease of the central nervous system. Histochem.J. 28:83-97
    Abstract: In this review the role of various subpopulations of macrophages in the pathogenesis of experimental autoimmune encephalomyetitis is discussed. Immunohistochemistry with macrophage markers shows that in this disease different populations of macrophages (i.e. perivascular cells, Microglia and infiltrating blood-borne macrophages) are present in the central nervous system. These subpopulations partially overlap in some functional activity while other activities seem to be restricted to a distinct subpopulation, indicating that these subpopulations have different roles in the pathogenesis of encephalomyelitis. The studies discussed in this review reveal that immunocytochemical and morphological studies, combined with new techniques such as in situ nick translation and experimental approaches like the use of bone marrow chimeras and macrophage depletion techniques, give valuable information about the types and functions of cells involved in central nervous system inflammation. The review is divided in three parts. In the first part the experimental autoimmune encephalomyelitis model is introduced. The second part gives an overview of the origin, morphology and functions of the various subpopulations. In the third part the role of these subpopulations is discussed in relation to the various stages (i.e. preclinical, clinical and recovery) of the experimental disease

  316. Becher B, Dodelet V, Fedorowicz V, Antel JP (1996) Soluble tumor necrosis factor receptor inhibits interleukin 12 production by stimulated human adult Microglial cells in vitro. J.Clin.Invest 98:1539-1543
    Abstract: IL-12 is a cytokine detected in active lesions in multiple sclerosis (MS) and promotes the acquisition of a Th1 cytokine profile by CD4+ T cells. Autoreactive T cells recovered from the central nervous system of animals with experimental autoimmune encephalomyelitis (EAE), a disease model for MS, display this phenotype. We demonstrate that human central nervous system-derived Microglia, but not astroglia, can produce IL-12 in vitro. Under basal culture conditions, human adult Microglia do not express detectable levels of IL-12, although these cells show some degree of activation as assessed by expression of the immunoregulatory surface molecules HLA-DR and B7 as well as low levels of TNF-alpha mRNA. Following activation with LPS, IL-12 p40 mRNA and p70 protein can be readily detected. IL-12 production is preceded by TNF-alpha production and is inhibited by recombinant soluble human TNF receptor (II)-IgG1 fusion protein (shu-TNF-R). These data indicate regulation of IL-12 by an autocrine-dependent feedback loop, providing an additional mechanism whereby shu-TNF-R, now used in clinical trials in MS, may be exerting its effect

  317. Bo L, Peterson JW, Mork S, Hoffman PA, Gallatin WM, Ransohoff RM, Trapp BD (1996) Distribution of immunoglobulin superfamily members ICAM-1, -2, -3, and the beta 2 integrin LFA-1 in multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 55:1060-1072
    Abstract: To identify potential molecular substrates for leukocyte trafficking and activation in multiple sclerosis (MS) brain, we determined the immunocytochemical distribution of the beta, integrin lymphocyte-function-associated antigen-1 (LFA-1) and its major ligands, intercellular adhesion molecule (ICAM)-1, ICAM-2, and ICAM-3 in MS tissue. Colocalization of these adhesion molecules with lineage-specific markers was analyzed by dual-labeling immunocytochemistry and confocal microscopy. ICAM-1 and ICAM-2 were detected on endothelial cells, and ICAM-3 immunoreactivity was restricted to infiltrating leukocytes. In control brain, 10% of glucose transporter-1 positive vessels contained ICAM-1 immunoreactivity on their luminal surface and 21% were ICAM-2-positive. A significant increase in ICAM-1-positive vessels was found in MS brains. This increase was greater in MS lesions (81% of vessels) than in nonlesion areas (37% of vessels). A significant increase in ICAM-1-positive vessels was found in encephalitis (55% of vessels) but not in Parkinson's (17% of vessels) brains. The percentage of vessels expressing ICAM-2 was not increased in MS, encephalitis, or Parkinson's brains. Both ICAM-3 and LFA-1 were detected on the vast majority of infiltrating lymphocytes and monocytes in and near MS lesions, and these cells were often closely apposed to each other. In addition, LFA-1 was detected on activated Microglia located close to the edge of demyelinating lesions. ICAM-3-positive leukocytes were often closely apposed to LFA-1-positive Microglia. These results suggest a role for ICAM-1, -2, and LFA-1 in the transendothelial migration of leukocytes into MS brain and a role for ICAM 3/LFA-1 interactions in the activation of lymphocytes, monocytes, and Microglia in MS lesions

  318. Bradl M, Linington C (1996) Animal models of demyelination. Brain Pathol. 6:303-311
    Abstract: Demyelination is a pathological feature that is characteristic of many diseases of the central nervous system (CNS) including multiple sclerosis (MS), sub-acute sclerosing panencephalomyelitis (SSPE), metachromatic leukodystrophy and Pelizaeus-Merzbacher disease. While demyelination is a pathological end-point that is common to all of these diseases, the cellular and molecular mechanisms responsible for this pathology are very different . These range from genetic defects that affect lipid metabolism in the leukodystrophies, cytopathic effects of viral infection in SSPE to the action of immunological effector mechanisms in MS and the viral encephalopathies. Irrespective of the initial cause of myelin degradation, many of these disorders are associated with some degree of CNS inflammation, as indicated by the local activation of Microglia, recruitment of macrophages or the intrathecal synthesis of immunoglobulin. Many of these phenomena are now being duplicated in animal models, providing not only new insights into the pathogenesis of human demyelinating diseases , but also unexpected interrelationships between the immune response in the CNS and the pathogenesis of diseases such as Alzheimers disease and HIV encephalopathy. Autoimmune mediated models of inflammatory demyelinating CNS disease have proved particularly valuable in this respect as they allow the effects of defined immune effector mechanisms to be studied in the absence of CNS infection

  319. Chiang CS, Powell HC, Gold LH, Samimi A, Campbell IL (1996) Macrophage/Microglial-mediated primary demyelination and motor disease induced by the central nervous system production of interleukin-3 in transgenic mice. J.Clin.Invest 97:1512-1524
    Abstract: Activated macrophage/Microglia may mediate tissue injury in a variety of CNS disorders. To examine this, transgenic mice were developed in which the expression of a macrophage/Microglia activation cytokine, interleukin-3 (IL-3), was targeted to astrocytes using a murine glial fibrillary acidic protein fusion gene. Transgenic mice with low levels of IL-3 expression developed from 5 mo of age, a progressive motor disorder characterized at onset by impaired rota-rod performance. In symptomatic transgenic mice, multi-focal, plaque-like white matter lesions were present in cerebellum and brain stem. Lesions showed extensive primary demyelination and remyelination in association with the accumulation of large numbers of proliferating and activated foamy macrophage/Microglial cells. Many of these cells also contained intracisternal crystalline pole-like inclusions similar to those seen in human patients with multiple sclerosis. Mast cells were also identified while lymphocytes were rarely, if at all present. Thus, chronic CNS production of low levels of IL-3 promotes the recruitment, proliferation and activation of macrophage/Microglial cells in white matter regions with consequent primary demyelination and motor disease. This transgenic model exhibits many of the features of human inflammatory demyelinating diseases including multiple sclerosis and HIV leukoencephalopathy

  320. Corbin JG, Kelly D, Rath EM, Baerwald KD, Suzuki K, Popko B (1996) Targeted CNS expression of interferon-gamma in transgenic mice leads to hypomyelination, reactive gliosis, and abnormal cerebellar development. Mol.Cell Neurosci. 7:354-370
    Abstract: Circumstantial and experimental evidence has implicated the immune cytokine interferon-gamma (IFN-gamma) as a key mediator in the pathological changes that are observed in many demyelinating disorders, including the most common human demyelinating disease, multiple sclerosis. To produce an animal model with which to study the effects of IFN-gamma on the CNS, we have generated transgenic mice in which the expression of IFN-gamma has been placed under the transcriptional control of the myelin basic protein (MBP) gene. Transgenic mice generated with this construct have a shaking/shivering phenotype that is similar to that observed in naturally occurring mouse models of hypomyelination (e.g., shiverer, jimpy, quaking), and these transgenic animals have dramatically less CNS myelin than control animals. Reactive gliosis and increased macrophage/Microglial F4/80 immunostaining were also observed. Additionally, major histocompatibility complex (MHC) class I and class II mRNA levels were increased in the CNS of MBP/IFN-gamma transgenic mice, and the increase in MHC class I mRNA expression was detected in both white and gray matter regions. Furthermore, cerebellar granule cell migration was abnormal in these animals. These results strongly support the hypothesis that IFN-gamma is a key effector molecule in immune-mediated demyelinating disorders and indicate that the presence of this cytokine in the CNS may also disrupt the developing nervous system

  321. Cuzner ML, Gveric D, Strand C, Loughlin AJ, Paemen L, Opdenakker G, Newcombe J (1996) The expression of tissue-type plasminogen activator, matrix metalloproteases and endogenous inhibitors in the central nervous system in multiple sclerosis: comparison of stages in lesion evolution. J.Neuropathol.Exp.Neurol. 55:1194-1204
    Abstract: The expression of tissue-type plasminogen activator (t-PA) and a number of metalloproteases as well as plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metalloproteases-1 (TIMP-1) was analyzed in the central nervous system (CNS) of normal control and multiple sclerosis (MS) cases by immunohistopathology. The expression of t-PA was detectable only in the blood vessel matrix in control white matter, but positive infiltrating mononuclear cells were also observed in MS white matter and primary lesions. In active plaques this pattern converted to strong positivity of foamy macrophages in areas of demyelination, declining in chronic lesions. In general PAI-1 expression paralleled that of t-PA. Gelatinase A and B were detected predominantly in astrocytes and Microglia throughout normal control white matter, with additional positive mononuclear cells in perivascular cuffs in MS white matter. In the demyelinating lesion there is widespread prominent expression of gelatinase B in reactive astrocytes and macrophages, which persists in astrocytes in the chronic lesion. TIMP-1 was also present in the vessel matrix and in lesional macrophages. These observations on the coexpression of enzymes and inhibitors of the matrix degrading cascade in CNS tissue pinpoint t-PA, a rate-limiting enzyme, and gelatinase B as therapeutic targets in MS

  322. D'Souza SD, Bonetti B, Balasingam V, Cashman NR, Barker PA, Troutt AB, Raine CS, Antel JP (1996) multiple sclerosis: Fas signaling in oligodendrocyte cell death. J.Exp.Med. 184:2361-2370
    Abstract: Fas is a cell surface receptor that transduces cell death signals when cross-linked by agonist antibodies or by fas ligand. In this study, we examined the potential of fas to contribute to oligodendrocyte (OL) injury and demyelination as they occur in the human demyelinating disease multiple sclerosis (MS). Immunohistochemical study of central nervous system (CNS) tissue from MS subjects demonstrated elevated fas expression on OLs in chronic active and chronic silent MS lesions compared with OLs in control tissue from subjects with or without other neurologic diseases. In such lesions, Microglia and infiltrating lymphocytes displayed intense immunoreactivity to fas ligand. In dissociated glial cell cultures prepared from human adult CNS tissue, fas expression was restricted to OLs. Fas ligation with the anti-fas monoclonal antibody M3 or with the fas-ligand induced rapid OL cell membrane lysis, assessed by LDH release and trypan blue uptake and subsequent cell death. In contrast to the activity of fas in other cellular systems, dying OLs did not exhibit evidence of apoptosis, assessed morphologically and by terminal transferase-mediated d-uridine triphosphate-biotin nick-end-labeling staining for DNA fragmentation. Other stimuli such as C2-ceramide were capable of inducing rapid apoptosis in OLs. Antibodies directed at other surface molecules expressed on OLs or the M33 non-activating anti-fas monoclonal antibody did not induce cytolysis of OLs. Our results suggest that fas-mediated signaling might contribute in a novel cytolytic manner to immune-mediated OL injury in MS

  323. Eng LF, Ghirnikar RS, Lee YL (1996) Inflammation in EAE: role of chemokine/cytokine expression by resident and infiltrating cells. Neurochem.Res. 21:511-525
    Abstract: Experimental allergic encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) which has many clinical and pathological features in common with multiple sclerosis (MS). Comparison of the histopathology of EAE and MS reveals a close similarity suggesting that these two diseases share common pathogenetic mechanisms. Immunologic processes are widely accepted to contribute to the initiation and continuation of the diseases and recent studies have indicated that Microglia, astrocytes and the infiltrating immune cells have separate roles in the pathogenesis of the MS lesion. The role of cytokines as important regulatory elements in these immune processes has been well established in EAE and the presence of cytokines in cells at the edge of MS lesions has also been observed. However, the role of chemokines in the initial inflammatory process as well as in the unique demyelinating event associated with MS and EAE has only recently been examined. A few studies have detected the transient presence of selected chemokines at the earliest sign of leukocyte infiltration of CNS tissue and have suggested astrocytes as their cellular source. Based on these studies, chemokines have been postulated as a promising target for future therapy of CNS inflammation. This review summarized the events that occur during the inflammatory process in EAE and discusses the roles of cytokine and chemokine expression by the resident and infiltrating cells participating in the process

  324. Ford AL, Foulcher E, Lemckert FA, Sedgwick JD (1996) Microglia induce CD4 T lymphocyte final effector function and death. J.Exp.Med. 184:1737-1745
    Abstract: Microglia, a type of tissue macrophage, are the only cells in the central nervous system (CNS) parenchyma to express some major histocompatibility complex (MHC) class II constitutively or to upregulate expression readily. They are thought to play a role in CD4 T cell activation in autoimmune diseases such as multiple sclerosis, as well as in neurodegenerative conditions, Alzheimer's disease in particular. We show here that highly purified MHC class II+ Microglia when tested directly ex vivo do indeed support an effector response by an encephalitogenic myelin basic protein-reactive CD4 T cell line from which production of the proinflammatory cytokines, interferon gamma and tumor necrosis factor, is elicited, but not interleukin (IL)-2 secretion or proliferation. After this interaction, the T cells die by apoptosis. Other nonMicroglial but CNS-associated macrophages isolated in parallel stimulate full T cell activation, including IL-2 production, proliferation, and support T cell survival. Neither CNS-derived population expresses B7.1/B7.2. Resident macrophages that terminate effector T cells in tissues constitute a novel and broadly applicable regulatory measure of particular relevance to processes of self-tolerance against sequestered antigens

  325. Gebicke-Haerter PJ, van Calker D, Norenberg W, Illes P (1996) Molecular mechanisms of Microglial activation. A. Implications for regeneration and neurodegenerative diseases. Neurochem.Int. 29:1-12
    Abstract: Microglia are the resident immunocompetent cells of the brain, comparable to other tissue macrophages, e.g. Kupffer cells in the liver or Langerhans cells in the skin. In disease, however, the central nervous system appears to be a largely immunosuppressive environment, which previously led to the hypothesis that it is an "immunologically privileged" organ. Nevertheless, Microglia can be activated by various internal and external stimuli, resulting in expression of cytokines and other mediators of inflammation. The molecular mechanisms converting those signals into specific Microglial responses are a field of intensive research efforts. These have been performed both on cultured Microglia and in vivo. Although the situation in vivo is sometimes difficult to interpret, considerable progress on the molecular level has been made using a number of excellent animal model systems combined with advanced detection techniques. Moreover, isolation and culture of Microglia is becoming a standard method in an increasing number of laboratories, which allows a closer look at their reactions towards a variety of test substances. Both aspects have been covered in this paper. It turns out that Microglia are extremely sensitive towards any kind of stimulus. They are probably the first cells in the brain "sensing" changes in the periphery, and the summarized data suggest that Microglia may even react in a specific manner in response to a specific stimulus. Under the notion that not only multiple sclerosis, but also further chronic degenerative diseases of the brain, are based on a common autoimmune mechanism, better insights into Microglial activation and its prolonged maintenance are of outstanding scientific interest

  326. Gerritse K, Laman JD, Noelle RJ, Aruffo A, Ledbetter JA, Boersma WJ, Claassen E (1996) CD40-CD40 ligand interactions in experimental allergic encephalomyelitis and multiple sclerosis. Proc.Natl.Acad.Sci.U.S.A 93:2499-2504
    Abstract: We investigated the role of CD40-CD40 ligand (CD40L) interactions in multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE). Activated helper T cells expressing CD40L (gp39) surface protein were found in MS patient brain sections, but not in brain tissue sections of normal controls or patients with other neurological disease. CD40L-positive cells were co-localized with CD40-bearing cells in active lesions (perivascular infiltrates). Most of these CD40-bearing cells proved to be of the monocytic lineage (macrophages or Microglial cells), and relatively few were B cells. To functionally evaluate CD40-CD40L interactions, EAE was elicited in mice by means of proteolipid-peptide immunization. Treatment with anti-CD40L monoclonal antibody completely prevented the development of disease. Furthermore, administration of anti-CD40L monoclonal antibody, even after disease onset, shortly before maximum disability score was reached led to dramatic disease reduction. The presence of helper T cells expressing CD40L in brain tissue of MS patients and EAE animals, together with the functional evidence provided by successful experimental prevention and therapy in an animal model, indicates that blockade of CD40-CD40L-mediated cellular interactions may be a method for interference in active MS

  327. Hartung HP (1996) [Pathogenesis of multiple sclerosis: status of research]. Wien.Med.Wochenschr. 146:520-527
    Abstract: multiple sclerosis is considered an immune-mediated disease of the CNS white matter. Peripheral blood and CSF contain circulating autoreactive T lymphocytes recognizing a number of myelin antigens. When activated, e.g. through a viral infection, these cells can migrate across the blood-brain-barrier into the CNS. Upon encounter of Microglial cells and local reactivation, they undergo clonal proliferation. Secreted Th1 cytokines (IFN-gamma and TNF-alpha) stimulate macrophages and Microglia to heightened phagocytic activity and the release of proinflammatory mediators. This results in damage to the myelin sheath and oligodendrocytes. Autoantibodies directed to myelin antigens are of key importance in the demyelinative process by initiating the complement cascade. Early in the course of the disease, down-regulatory mechanisms can terminate an acute exacerbation and contain tissue damage. With repeated attacks, these mechanisms get overwhelmed and the reparative capacity of oligodendrocytes exhausted. This marks the transition to the chronic progressive phase of the disease characterized pathologically by demise of oligodendrocytes, secondary loss of axons and astroglial proliferation. A better understanding of the pathogenesis of MS allows to identify strategic targets for more specific and efficacious therapeutic immunointervention

  328. Li H, Cuzner ML, Newcombe J (1996) Microglia-derived macrophages in early multiple sclerosis plaques. Neuropathol.Appl.Neurobiol. 22:207-215
    Abstract: One of the characteristics of ongoing demyelination in multiple sclerosis (MS) is the accumulation of lipid-laden macrophages in active lesions. Little is known about the source of these macrophages in the early stages of plaque evolution as Microglial-derived and haematogenous macrophages share morphological characteristics and most cell surface antigens. A key issue in understanding the pathogenesis of MS is the reliable identification of phagocytes capable of degrading myelin and presenting autoantigen to T cells at the onset of demyelination. Using a combination of histochemistry and immunocytochemistry, an average of 60% of EBM11+ phagocytes (EMBII is a pan-macrophage marker) in early active MS plaques, defined as lesions with myelin-containing phagocytes but no obvious parenchymal myelin loss around these cells, were judged to originate from Microglia as they exhibited nucleoside diphosphatase activity, a Microglial marker. Only 4-15% of EBM11+ phagocytes in these lesions exhibited non-specific esterase activity, an enzyme marker for monocytes and macrophages. In contrast, 30-80% of EBM11+ phagocytes in more advanced active plaques with partial or complete myelin loss in the parenchyma were non-specific esterase+. Lysosomal enzyme acid phosphatase activity was strongly exhibited by 90% of phagocytes in all active plaques and there was a significant correlation between numbers of acid phosphatase+ cells and oil red O+ foamy macrophages. The results indicate that Microglia are the main population of phagocytes in the early stages of demyelination and may play an important role in the pathogenesis of MS

  329. Loughlin AJ, Woodroofe MN (1996) Inhibitory effect of interferon-gamma on LPS-induced interleukin 1 beta production by isolated adult rat brain Microglia. Neurochem.Int. 29:77-82
    Abstract: The effect of interferon-gamma (IFN-gamma) on lipopolysaccharide (LPS)-induced cytokine production has been examined in adult rat brain Microglia. Following treatment of isolated cells in vitro with LPS, interleukin-1 (IL-1) and interleukin-6 (IL-6) levels in culture supernatants, determined by bioassay, were increased in a dose-dependent manner. IL-6 was particularly sensitive to LPS-stimulation. Using in situ hybridisation techniques, the induction by LPS of IL-1 and IL-6 mRNA in cultured Microglia has been demonstrated. When IFN-gamma was included, LPS-induced production of both IL-1 and IL-6 by Microglia was significantly reduced and this effect was particularly marked in the case of IL-1. Comparisons with peritoneal macrophages demonstrate that whilst both cell types produce IL-1 and IL-6 in response to LPS, IFN-gamma had no significant effect on this response in peritoneal macrophages. This suggests potential control mechanisms which may be effective in down-regulating cytokine production by Microglia in vivo

  330. Lue LF, Brachova L, Walker DG, Rogers J (1996) Characterization of glial cultures from rapid autopsies of Alzheimer's and control patients. Neurobiol.Aging 17:421-429
    Abstract: We have developed isolated and mixed cultures of Microglia, astrocytes, and oligodendrocytes from rapid (mean of 2 h 55 min) autopsies of nondemented elderly patients and patients with Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Cultures were derived from both the corpus callosum (CC) and superior frontal gyrus (SFG). Cultured Microglia phagocytosed latex beads, were reactive for Dil-acetylated low density lipoprotein, were immunoreactive for CD68 and major histocompatibility complex II markers, and were not immunoreactive for fibroblast, astrocyte, or oligodendrocyte markers. Cultured astrocytes included fibrous and protoplasmic types, were immunoreactive for GFAP, and were not immunoreactive for fibroblast, Microglia, or oligodendrocyte markers. Cultured oligodendrocytes were poorly adherent, were slow to develop, were immunoreactive for galactocerebroside, and were not immunoreactive for fibroblast, Microglia, or astrocyte markers. Because they are readily manipulated under controlled experimental conditions, and because they permit immediate access to individual cells and sets of cells from patients who have actually suffered the disease, these cultures may provide an important new tool for unravelling the etiology and pathogenesis of human CNS disorders

  331. Maeda A, Sobel RA (1996) Matrix metalloproteinases in the normal human central nervous system, Microglial nodules, and multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 55:300-309
    Abstract: Matrix metalloproteinases (MMPs) comprise a family of proteolytic enzymes that are involved in remodeling of the extracellular matrix (ECM) of many tissues. They have been implicated in degradation of vascular basement membranes thereby facilitating leukocyte migration into inflammatory sites. To determine the cellular localization and levels of MMPs in the normal human central nervous system (CNS), multiple sclerosis (MS) lesions, and other conditions, cryostat sections of CNS samples were immunostained with antisera to MMP-1, -2, -3 and -9. In control white matter the principal cells that express the MMPs were perivascular and parenchymal Microglia. Cellular MMP expression was also found in sporadic Microglial nodules in MS white matter. Most CNS microvessel endothelial cells expressed MMP-3 and -9 but not MMP-1 or -2. The majority of macrophages in active MS and necrotic lesions were MMP-l-, -2-, -3-, and -9-positive whereas chronic MS lesions had fewer MMP-positive macrophages. Small numbers of astrocytes were MMP-2-, -3- and -9-positive in acute and chronic MS lesions. These data suggest that Microglia-derived MMPs may mediate turnover of the CNS ECM under normal conditions and in Microglial nodules. In sites of CNS tissue injury there is complex and dynamic regulation of MMP expression by different cell populations. In MS lesions MMP-mediated proteolysis may contribute to breakdown of the blood-brain barrier and leukocyte migration into the CNS, in situ immune activation, demyelination, metabolism of bioactive peptides, and the formation of an ECM that does not promote remyelination or axonal repair

  332. Miller DJ, Njenga MK, Parisi JE, Rodriguez M (1996) Multi-organ reactivity of a monoclonal natural autoantibody that promotes remyelination in a mouse model of multiple sclerosis. J.Histochem.Cytochem. 44:1005-1011
    Abstract: A contemporary view of autoimmunity suggests that self-reactivity is a normal phenomenon, in contrast to the classical association between autoimmunity and immunopathology. We have previously demonstrated that monoclonal antibody SCH94.03, a natural autoantibody with polyreactivity towards several purified protein and hapten antigens, promotes central nervous system remyelination when passively transferred to SJL/J mice chronically infected with Theiler's murine encephalomyelitis virus, an established experimental model of multiple sclerosis. In this study we characterized the autoreactivity of SCH94.03 with endogenous mouse tissue using immunoperoxide and multiple-color immunofluorescence staining techniques on frozen tissue sections. Within the nervous system, SCH94.03 labeled fibrous astrocytes, ependymal cells, ganglion satellite cells, and a sub-population of Microglia, oligodendrocytes, and peripheral nervous system neurons. Outside the nervous system, SCH94.03 labeled gastrointestinal tract smooth muscle and luminal epithelium, erythrocytes, and interdigitating dendritic cells in peripheral lymphoid organs. These data indicate that SCH94.03 is a multi-organ reactive autoantibody and support the hypothesis that autoantibodies can have a beneficial rather than a pathogenic function in central nervous system demyelinating diseases

  333. Mitrovic B, Parkinson J, Merrill JE (1996) An in Vitro Model of Oligodendrocyte Destruction by Nitric Oxide and Its Relevance to multiple sclerosis. Methods 10:501-513
    Abstract: There is mounting evidence that nitric oxide (NO) is produced in the brains of patients with multiple sclerosis (MS) and in the experimental model of MS, experimental autoimmune encephalomyelitis, after the induction of Type II nitric oxide synthase (iNOS). Because NO can cause a variety of biological insults that compromise or even kill normal cells, we studied the effects of NO on oligodendrocytes since they are a target in MS tissue. In an in vitro model, we have been able to demonstrate that NO causes damage to oligodendrocytes preferentially, sparing Microglia almost completely and affecting some but not all astrocytic functions. This article describes the types of assays used to measure morphological changes, mitochondrial dysfunction, DNA strand breaks, and cell death brought on by NO or peroxynitrite (ONOO-) as well as a comprehensive review of the various techniques and sensitivities of NO and iNOS assays that would be applicable to similar in vitro models

  334. Mosley K, Cuzner ML (1996) Receptor-mediated phagocytosis of myelin by macrophages and Microglia: effect of opsonization and receptor blocking agents. Neurochem.Res. 21:481-487
    Abstract: Myelin is phagocytosed by Microglia (MG) and to a somewhat lesser extent by peritoneal macrophages (M phi) in a dose- and time-dependent manner. In serum-free medium opsonization of rat myelin significantly enhances binding and ingestion, more by rat macrophages than by Microglia. Furthermore the requirement for opsonization is not restricted to anti-myelin antibodies as the difference in the rate of myelin uptake by macrophages is largely eliminated when they are cultured in 10% fetal calf serum. Binding and ingestion of both myelin and opsonized myelin are inhibited to the same dose-dependent extent by zymosan, oxidized LDL, peroxidase-antiperoxidase (PAP), opsonized erythrocytes and the anti-CR3 antibody OX42 implicating lectin, scavenger, Fc and complement receptors in the phagocytosis of myelin. Thus while the differential uptake of myelin and opsonized myelin by macrophages would indicate a central role for the Fc receptor, binding inhibition studies implicate a range of membrane receptors which would obviate the need for antigen-antibody complexing to stimulate phagocytosis. Uptake of both myelin preparations by macrophages or Microglia is stimulated by interferon-gamma and inhibited by TGF-beta, and the process of ingestion results in increased nitric oxide release and decreased superoxide production, the effect being more pronounced when myelin is opsonized

  335. Muller-Ladner U, Jones JL, Wetsel RA, Gay S, Raine CS, Barnum SR (1996) Enhanced expression of chemotactic receptors in multiple sclerosis lesions. J.Neurol.Sci. 144:135-141
    Abstract: We have previously shown that astrocytes and Microglia express the receptors for C5a, interleukin-8 (IL-8) and N-formyl-Met-Leu-Phe (FMLP) in vitro. The expression and function of chemotactic receptors in the central nervous system (CNS) is, however, largely unexplored. In this study, we examined tissue sections from normal human brain and active, chronic active and chronic silent multiple sclerosis (MS) lesions for the expression of the receptors for C5a, IL-8 and FMLP by immunohistochemistry. In normal brain tissue, the expression of all three receptors was seen at low levels on astrocytes and Microglia. In contrast, expression for all three receptors was markedly elevated on foamy macrophages in the acute and chronic active MS lesions. In addition, fibrous astrocytes stained intensely for the C5a receptor in the chronic active disease. Receptor expression in the chronic silent lesion was low and similar to that seen in normal brain, with staining confined to a few hypertrophic astrocytes and foamy macrophages. These are the first studies to demonstrate expression of these receptors in the CNS and elevated receptor expression in inflammatory MS lesions. The data suggest that these chemotactic receptors may play a role in inflammatory responses in MS and possibly in other CNS diseases

  336. Nataf S, Garcion E, Darcy F, Chabannes D, Muller JY, Brachet P (1996) 1,25 Dihydroxyvitamin D3 exerts regional effects in the central nervous system during experimental allergic encephalomyelitis. J.Neuropathol.Exp.Neurol. 55:904-914
    Abstract: 1,25-dihydroxyvitamin D3 (1,25-D3) is already known to prevent clinical signs of experimental allergic encephalomyelitis when animals are treated during the immunization phase. In the present work we have evaluated the ability of 1,25-D3 to inhibit chronic relapsing experimental allergic encephalomylitis (EAE) of the Lewis rat, when administered after the beginning of clinical signs. We observed a significant clinical improvement in 1,25-D3-treated rats. This effect was accompanied by a profound inhibition of CD4 antigen expression by central nervous system (CNS) infiltrating monocytes/macrophages and parenchymal Microglia. In addition, immunohistochemical analysis performed at the time of the second attack evidenced a region-specific distribution of inflammatory cells. In the same way, some aspects of the effects exerted by 1,25-D3 appeared to vary depending on the region considered, namely spinal cord, brainstem, cerebellum, midbrain or anterior brain. Thus, in 1,25-D3-treated rats, we observed an almost complete inhibition of CD4 antigen expression in the granule cell layer and the adjacent white matter of the cerebellum as well as a marked decrease in the number of OX42-positive cells (macrophages and activated Microglia) in anterior brain sections. We conclude that 1,25-D3 can exert immunomodulatory effects inside the CNS during an ongoing immune process and may thus represent a promising therapy for multiple sclerosis

  337. Peress NS, Perillo E, Seidman RJ (1996) Glial transforming growth factor (TGF)-beta isotypes in multiple sclerosis: differential glial expression of TGF-beta 1, 2 and 3 isotypes in multiple sclerosis. J.Neuroimmunol. 71:115-123
    Abstract: We studied glial transforming growth factor (TGF)-beta isotype expression in 14 cases of multiple sclerosis. Acute active lesions exhibited selective TGF-beta 2 immunoreactivity of lesion encircling ramified Microglia. In contrast, astrocytes within chronic active white matter lesions expressed all three isotypes. Chronic active lesions which extended into cortex exhibited selective cortical astrocyte TGF-beta 2 expression. This isotype was also selectively expressed by astrocytes in apparently normal white matter. A similar pattern of glial TGF-beta expression was seen in the pathological control, progressive multifocal leukoencephalopathy. The results suggest that TGF-beta cytokines are locally expressed in demyelination and that the beta 2 isotype may be uniquely regulated

  338. Power C, Kong PA, Trapp BD (1996) Major histocompatibility complex class I expression in oligodendrocytes induces hypomyelination in transgenic mice. J.Neurosci.Res. 44:165-173
    Abstract: Increased expression of MHC Class I occurs in the central nervous system in association with demyelinating diseases such as multiple sclerosis and experimental allergic encephalomyelitis. To determine if MHC Class I expression by oligodendrocytes induces white matter pathology, the MHC Class I gene was expressed in transgenic mice under the control of the myelin basic protein (MBP) promoter. These mice display a neurological phenotype at 21 days-of-age. We examined these mice at 1,3, and 12 weeks-of-age. MHC Class I was detected in the brains and spinal cords of transgenic mice but not in control mice. Class I was located in oligodendrocyte perikarya but not in myelin sheaths. The central nervous system of these transgenic mice was hypomyelinated and contained hypertrophic Microglia and astrocytes. These observations establish that Class I expression by oligodendrocytes delays normal myelination but does not cause inflammatory demyelination. This hypomyelinating animal model is of potential use in studying the interactions between immunologically active molecules and remyelination in disorders of myelin

  339. Schluesener HJ, Seid K, Kretzschmar J, Meyermann R (1996) Leukocyte chemotactic factor, a natural ligand to CD4, is expressed by lymphocytes and Microglial cells of the MS plaque. J.Neurosci.Res. 44:606-611
    Abstract: The leukocyte chemotactic factor (LCF) is a proinflammatory cytokine and natural soluble ligand to the human CD4 molecule. LCF is produced by CD4+ and CD8+ T lymphocytes and is considered essential to the influx of CD4+ T lymphocytes and macrophages into an inflammatory lesion. In order to investigate the role of LCF in the multiple sclerosis (MS) lesion, we have used a synthetic gene to express LCF in E. coli and have produced monoclonal antibodies against LCF. Monoclonal antibodies are suited to demonstrate LCF in ELISAs. Western blots and paraffin-embedded tissue sections. In the MS lesion, immunopositive lymphocytes and Microglial cells, notably, have been found. This is the first demonstration that LCF is present in MS lesions. Immunostaining of Microglial cells is noteworthy, as these cells are strategically placed regulatory elements of CNS immunosurveillance and like other cells of the monocytic lineage express CD4 molecules. Thus, LCF might be a paracrine factor regulating T-lymphocyte chemoattraction and an autocrine molecule regulating Microglial cell immune reactivity

  340. Szczepanik AM, Fishkin RJ, Rush DK, Wilmot CA (1996) Effects of chronic intrahippocampal infusion of lipopolysaccharide in the rat. Neuroscience 70:57-65
    Abstract: Astrogliosis and Microglial activation are associated with many neurodegenerative disorders including multiple sclerosis, its animal model experimental allergic encephalomyelitis, and Alzheimer's disease. To address the hypothesis that chronic astroglial or Microglial activation could be contributing factors to neuronal death or injury, the immunostimulant lipopolysaccharide was infused into the hippocampus for 16 days using Alzet mini-osmotic pumps attached to a cannula. Placement of the cannula and infusion of vehicle for 16 days caused a hippocampal lesion with a volume of 0.5 +/- 0.1 mm3. Infusion of lipopolysaccharide at the dose of 2.0 micrograms/day produced a lesion of 4.9 +/- 1.3 mm3 (P < 0.01, Newman-Keuls), whereas, a lower dose of 0.2 microgram/day caused a lesion of 1.3 +/- 0.3 mm3 (P < 0.05). The lesion was defined as a focal necrotic reaction with fibrin deposits outlining an area at an early stage of encapsulation. No apparent neuronal loss was observed by Cresyl Violet staining outside the encapsulated necrotic area. There was a pronounced astrogliosis and an increase in activated macrophages throughout the lipopolysaccharide-infused hippocampus as determined by glial fibrillary acidic protein and ED-1 immunohistochemistry, respectively. Choline acetyltransferase and glutamic acid decarboxylase enzyme activities, used as functional measures of neuronal viability for cholinergic and GABAergic neurons, respectively, were unaffected in the hippocampus following a 16 day infusion of lipopolysaccharide at the doses of 0.2, 0.6 and 2.0 micrograms/day. In addition, unilateral infusion of lipopolysaccharide into the hippocampus did not affect 24 h locomotion when tested on day 13, body temperature or weight gain. Under the experimental conditions employed in the present study, chronic infusion of lipopolysaccharide into the hippocampus resulted in a dose-dependent focal necrotic lesion at the site of infusion. In tissue surrounding the encapsulated lesion, neurons were present among the reactive astrocytes and increased number of macrophages suggesting that astrocytes and macrophages can be activated without causing neuronal loss

  341. Vanguri P, Cho SY, Chi CM (1996) Role of muIP-10 in interferon-gamma induction of Ia in rat astrocytes. Mol.Immunol. 33:1079-1087
    Abstract: Interferon-gamma, (IFNgamma) is a potent inducer of class II MHC (Ia) in rat astrocytes and Microglia which are immunocompetent cells of the central nervous system (CNS). muIP-10, a member of the alpha-chemokine family, is also induced by IFNgamma in these cells. The induction of muIP-10 mRNA occurred in an immediate early manner, while Ia mRNA-induction was delayed and required new protein synthesis. We studied the possible role of muIP-10 in IFNgamma-mediated induction of Ia in astrocytes. Antibodies to muIP-10 protein significantly inhibited the expression of surface Ia molecules by astrocytes. Incubation of astrocytes with antisense-oligonucleotides against muIP-10 mRNA also reduced the number of Ia positive cells inducible by IFNgamma. Neither the number of IFNgamma-inducible class I MHC positive cells nor the number of class I molecules expressed per cell were affected by antisense-oligonucleotides against muIP-10, indicating the specificity of the oligonucleotide and the selective requirement of muIP-10 for Ia induction by IFNgamma. Transient transfection of astrocytes with plasmids expressing muIP-10 in the antisense orientation also reduced the number of Ia positive astrocytes. These studies suggest a role for muIP-10 protein as an autocrine factor that enhances the expression of IFNgamma-inducible Ia on astrocytes. This could create focal areas rich in Ia expressing cells which could more efficiently present antigens to T cells, leading to immune-mediated inflammation such as in multiple sclerosis

  342. Vilafranca M, Tello M, Pumarola M, Domingo M (1996) Neural cells from dogs with spontaneous distemper encephalitis express class II major histocompatibility complex molecules. J.Comp Pathol. 114:43-50
    Abstract: Expression of class II major histocompatibility complex (MHC) molecules by non-immune cells (e.g., parenchymal cells) leads to the presentation of self-antigens, and may have a role in the pathogenesis of many diseases mediated by autoimmunity. Such diseases, characterized by demyelination of the central nervous system and expression of class II MHC molecules on neural cells, include multiple sclerosis, experimental allergic encephalitis and Theiler's murine encephalomyelitis virus infection. Canine distemper encephalitis probably does not have an autoimmune character, but it shares many similarities with the aforementioned diseases. For this reason, the expression of class II MHC molecules in the brains of dogs with canine distemper encephalitis was investigated immunohistochemically. The results presented here demonstrate that canine Microglia and astrocytes "upregulate" class II MHC expression in cases of encephalitis associated with chronic canine distemper

  343. Washington RA, Becher B, Balabanov R, Antel J, Dore-Duffy P (1996) Expression of the activation marker urokinase plasminogen-activator receptor in cultured human central nervous system Microglia. J.Neurosci.Res. 45:392-399
    Abstract: The ability of Microglia to migrate through central nervous system (CNS) tissue requires proteolytic degradation of components of the extracellular matrix. Urokinase plasminogen activator (uPA), when bound to its cell surface receptor (uPAR), is an active cell surface protease. uPAR expression has been associated with cell activation. Cultured human Microglia express surface uPAR. uPAR expression was found to be associated predominately with spindle- or bipolarshaped Microglia. The addition of lipopolysaccharide (LPS) to Microglial cultures enhanced the proportion of uPAR expression and shifted cell morphology to the elongated spindle or bipolar shape. When Microglia were examined immediately ex vivo, uPAR surface expression could not be detected. Similarly, uPAR transcripts detected by reverse transcription-polymerase chain reaction techniques were found in cultured, but not ex vivo, Microglia. Microglia isolated from a patient with multiple sclerosis (MS) displayed a large amount of uPAR+ cells. These cells were predominantly spindle or bipolar in nature. These findings suggest that uPAR surface expression is associated with Microglial activation. Surface expression of uPAR and associated cell surface protease activity may provide a mechanism for Microglial migration and may be important in the pathophysiology of MS

  344. Xiao BG, Bao WJ, Bai XF, Link H (1996) Induction of cytolysin mRNA in glial cells by IFN-gamma: a possible cytotoxic pathway in the CNS. Neuroreport 8:329-333
    Abstract: We utilized in situ hybridization to detect expression and regulation of cytolysin mRNA in Microglia, astrocytes and oligodendrocytes from newborn rat brains. Expression under natural culture conditions was undetectable or very low, even after 10 days of culture. Cytolysin mRNA expression in Microglia, astrocytes and oligodendrocytes was up-regulated by IFN-gamma. This up-regulation in glial cells was slow, and characterized by a gradually increased expression until day 10 of culture. IFN-gamma-mediated up-regulation of cytolysin mRNA was markedly more prominent in oligodendrocytes than in Microglia and astrocytes. Unexpectedly, a combination of LPS and IFN-gamma did not exhibit a synergistic effect in the induction of cytolysin mRNA expression in the three types of glial cells. On the contrary, LPS strongly inhibited IFN-gamma-mediated cytolysin mRNA expression in Microglia, astrocytes and oligodendrocytes. These results reveal that there may exist a glial cell-dependent cytotoxic pathway within the CNS, and that inducible cytolysin may play an important role in destruction of oligodendrocytes or clearance of infiltrating cells within the CNS in inflammatory diseases such as multiple sclerosis or experimental allergic encephalomyelitis

  345. Zielasek J, Hartung HP (1996) Molecular mechanisms of Microglial activation. Adv.Neuroimmunol. 6:191-22
    Abstract: Microglial cells are brain macrophages which serve specific functions in the defense of the central nervous system (CNS) against microorganisms, the removal of tissue debris in neurodegenerative diseases or during normal development, and in autoimmune inflammatory disorders of the brain. In cultured Microglial cells, several soluble inflammatory mediators such as cytokines and bacterial products like lipopolysaccharide (LPS) were demonstrated to induce a wide range of Microglial activities, e.g. increased phagocytosis, chemotaxis, secretion of cytokines, activation of the respiratory burst and induction of nitric oxide synthase. Since heightened Microglial activation was shown to play a role in the pathogenesis of experimental inflammatory CNS disorders, understanding the molecular mechanisms of Microglial activation may lead to new treatment strategies for neurodegenerative disorders, multiple sclerosis and bacterial or viral infections of the nervous system

  346. Barnum SR (1995) Complement biosynthesis in the central nervous system. Crit Rev.Oral Biol.Med. 6:132-146
    Abstract: Complement is an important effector arm of the human immune response. Binding of proteolytic fragments derived from activation of complement by specific receptors leads to responses as diverse as inflammation, opsonization, and B-cell activation. The importance of characterizing the expression and regulation of complement in the CNS is highlighted by growing evidence that complement plays a significant role in the pathogenesis of a variety of neurological diseases, such as multiple sclerosis and Alzheimer's disease. In vitro studies have demonstrated that astrocytes, the predominant glial cell type in the brain, are capable of expressing or producing a majority of the components of the complement system. Expression of many complement proteins synthesized by astrocytes is regulated by both pro- and anti-inflammatory cytokines, many of which are also produced by several cell types in the CNS. In addition to astrocytes, ependymal cells, endothelial cells, Microglia, and neurons have recently been shown to synthesize various complement proteins or express complement receptors on their cell surfaces. Together, these studies demonstrate that several cell types throughout the brain have the potential to express complement and, in many cases, increase expression in response to mediators of the acute phase response. These studies suggest that complement may play a greater role in CNS immune responses than previously thought, and pave the way for better understanding of the dynamics of complement expression and regulation in vivo. Such understanding may lead to therapeutic manipulation of complement host defense functions in a variety of inflammatory and degenerative diseases in the CNS

  347. Barron KD (1995) The Microglial cell. A historical review. J.Neurol.Sci. 134 Suppl:57-68
    Abstract: Effectively, modern research has confirmed Hortega's view of the origin of the Microgliacyte from circulating monocytes of the monocyte-macrophage series that invade the brain during embryonic and early postnatal life. Their phagocytic capacity is exercised during the brain remodelling that marks brain maturation. They then convert to the ramified resting Microglial cell visualized in the silver carbonate staining technique of Hortega and by modern lectin-binding methods. In response to injury, reactive Microglia exhibit hypertrophy and hyperplasia, and may or may not go on to form typical lipid-laden phagocytes. Activated Microglia show upregulation of the many marker antigens they share with circulating monocytes, including the major histocompatibility class (MHC) class II antigens that bespeak their immunocompetent nature. However, MHC class I and II expression and development of immunohistochemical positivity for cytoplasmic and plasma membrane antigens that characterize the monocyte-macrophage do not necessarily indicate an immunological response though there is ample evidence that Microglia can serve as antigen-presenting cells. Rather, Microglia are extraordinarily sensitive to changes in the brain microenvironment, whatever the nature of the exciting mechanism or substance. They may be considered to serve an ever alert, protective and supportive function that can be assembled rapidly to deal with infections, physical injuries, physiologic changes and systemic influences. In addition to elaboration and secretion of cytokines with varied actions, e.g., suppression of astrogliosis, they secrete factors, including nerve growth factor, which are supportive of neurons. They have an important role in iron metabolism and the storage of iron and ferritin. They may promote central nervous system regeneration. They are prominently involved in such pathologic processes as the acquired immunodeficiency syndrome, multiple sclerosis, prion diseases and the degenerative disorders, e.g., Alzheimer's disease and Parkinson's disease. With aging, they grow more numerous, become richer in iron and ferritin and exhibit phenotypic alteration, e.g., the expression of MHC class II antigens that are not ordinarily demonstrable immunohistochemically in the resting state. The rate of growth of our knowledge of Microglia during the last decade has been exponential and continues

  348. Benveniste EN, Huneycutt BS, Shrikant P, Ballestas ME (1995) Second messenger systems in the regulation of cytokines and adhesion molecules in the central nervous system. Brain Behav.Immun. 9:304-314
    Abstract: Cytokines are a group of secreted proteins that exhibit diverse biological activity and are especially important in immune and inflammatory responses. The inappropriate production of cytokines in the central nervous system (CNS) has been implicated in a number of disease states such as Alzheimer's disease, multiple sclerosis, and AIDS dementia complex. This article focuses on the biological role of three cytokines in the CNS, interleukin-6 (IL-6), tumor necrosis factor alpha, and nerve growth factor, with an emphasis on production by glial cells. We will discuss the diverse intracellular signaling pathways that regulate expression of these cytokines by glial cells and then describe the second messenger systems that mediate cytokine-induced responses in the CNS, with an emphasis on adhesion molecule expression. We conclude by discussing the complexities of signal transduction pathways, particularly "cross-talk" between different intracellular mediators

  349. Cannella B, Raine CS (1995) The adhesion molecule and cytokine profile of multiple sclerosis lesions. Ann.Neurol. 37:424-435
    Abstract: The expression of the adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), and their respective receptors on leukocytes, very late activation antigen-4 (VLA-4) and lymphocyte function-associated antigen-1 (LFA-1), together with a selection of proinflammatory and immunomodulatory cytokines (interleukin [IL]-1, IL-2, IL-4, IL-10, tumor necrosis factor-alpha [TNF-alpha], transforming growth factor-beta [TGF-beta], and interferon-gamma [IFN-gamma] was examined by immunocytochemistry in multiple sclerosis (MS) lesions of different ages and compared with central nervous system (CNS) tissue from other neurological diseases, both inflammatory and noninflammatory, and normal CNS tissue. These molecules play key roles in lymphocytic infiltration and interactions during tissue inflammation and are in large part normally not expressed by CNS cells. High levels of expression of all the molecules tested were found in MS, particularly in chronic active lesions. Positivity for all molecules was also seen in other neurological diseases, even in noninflammatory conditions. There was some suggestion that the VCAM-1/VLA-4 adhesion pathway was expressed at higher levels in chronic MS lesions, while ICAM-1/LEA-1 was used more uniformly in lesions of all ages. Of the cytokines examined, there was increased expression of TNF-alpha and IL-4 in MS; this was found to be statistically significant when compared with noninflammatory neurological diseases. The expression of most adhesion molecules and some cytokines was negligible in normal CNS tissue although low-level reactivity for ICAM-1 TGF-beta, IL-4, TNF-alpha, and IL-10 was detected, perhaps indicative of immunoregulatory mechanisms. Microglial cells and astrocytes were the major CNS cell types expressing cytokines. The results indicate a potential in the CNS for widespread induced expression of molecules involved in the inflammatory cascade. No adhesion or cytokine molecule or pattern of expression unusual for MS was apparent

  350. De Simone R, Giampaolo A, Giometto B, Gallo P, Levi G, Peschle C, Aloisi F (1995) The costimulatory molecule B7 is expressed on human Microglia in culture and in multiple sclerosis acute lesions. J.Neuropathol.Exp.Neurol. 54:175-187
    Abstract: B7 is a costimulatory molecule which is expressed on antigen-presenting cells and which plays a pivotal role in T cell activation and proliferation. To elucidate mechanisms regulating intracerebral immune responses, expression of B7 was examined in cultured Microglial cells and in brain tissue from control and multiple sclerosis patients. Using immunocytochemical and polymerase chain reaction techniques, we show that B7 was expressed in cultured Microglial cells from the human embryonic brain. Microglia also bound the soluble form of the B7 receptor CTLA-4 (CTLA-4-Ig). B7 gene expression and binding of anti-B7 antibodies and CTLA-4-Ig increased after treatment with interferon-gamma. B7 was not inducible in human astrocytes. Human Microglia expressed other costimulatory molecules, such as intercellular adhesion molecule-1, LFA-1 and LFA-3. In sections of multiple sclerosis brains, B7 immunoreactivity was detected on activated Microglia and infiltrating macrophages within active lesions. In chronic lesions, only perivascular cells were stained. B7 immunoreactivity was undetectable in sections from Alzheimer's disease or normal brain tissue. These data suggest that B7 may be involved in T cell activation and lesion development in multiple sclerosis and that the regulated expression of B7 on Microglia may contribute to the local stimulation of T cell proliferation and effector functions

  351. Gehrmann J, Banati RB, Cuzner ML, Kreutzberg GW, Newcombe J (1995) Amyloid precursor protein (APP) expression in multiple sclerosis lesions. Glia 15:141-151
    Abstract: The amyloid precursor protein (APP) is rapidly induced in reactive glial cells in response to several pathological stimuli including inflammation. In the present study, observations previously made in animal models of autoimmune central nervous system inflammation have been extended to the analysis of multiple sclerosis (MS) lesions. A total of thirty fresh-frozen tissue blocks from six histopathologically normal control and six MS cases have been examined immunocytochemically with monoclonal antibodies directed against either C- or N-terminal epitopes of APP. Histopathological evaluation of disease progression was based on hematoxylin-eosin and oil red O staining and immunocytochemistry for T cells, macrophages/Microglia, astrocytes, and oligodendrocytes. In control cases, APP immunoreactivity was generally low and confined to blood vessel walls, oligodendrocytes in white, and neurons in grey matter. In actively demyelinating plaques, however, levels of APP immunoreactivity were high, localised on T lymphocytes, foamy macrophages, activated Microglia, and reactive astrocytes including astrocytic processes. In more chronic lesions, levels of APP immunoreactivity were generally lower than in acute lesions, mainly found on reactive astrocytes, their processes and a few macrophages/Microglia depending on the stage of plaque development. In addition, a few 14E-positive oligodendrocytes and, moreover, numerous axons exhibited APP immunoreactivity, which was particularly pronounced with anti-C-terminal antibodies. These results demonstrate that APP is induced on reactive glial cells but also on T lymphocytes during demyelination. The extent of APP expression appears to be correlated to histopathological lesion development and thus suggests that APP detection serves as a sensitive marker for disease progression in MS

  352. Grimaldi LM, Martino G (1995) Effect of interferon gamma on T lymphocytes from patients with multiple sclerosis. Mult.Scler. 1 Suppl 1:S38-S43
    Abstract: A central role in the complex immunology of MS is played by activated T lymphocytes. Proper antigenic stimulation, adequate major histocompatibility complex (MHC) coactivation and multiple cytokine signals regulate T-cell activation via the generation of intracellular calcium (Ca2+) transients necessary to up-regulate the genes controlling lymphocyte growth and differentiation. Interferon gamma (IFN-gamma) exerts an autocrine/paracrine control of T-lymphocyte activity and is able to co-mediate most demyelinating events occurring in MS patients. The mechanisms by which IFN-gamma exerts its effects include increased expression of MHC class II molecules on the surface of glial cells and stimulation of macrophage/Microglial cell production of molecules toxic to myelin. Most intracellular events regulating these processes in lymphocytes are, however, still unknown. We have reported that in the majority of MS patients T lymphocytes (mainly CD4+) exposed to IFN-gamma show a Ca2+ influx whose ion permeability and pharmacological properties differ from those of all Ca2+ influxes so far described. This IFN-gamma-activated Ca2+ influx, which is probably sustained by a cationic channel, was observed in the majority of patients with MS, but only in a limited number of subjects affected by other neurological, active immune-mediated diseases or healthy control subjects. Moreover, the presence of the influx correlates with clinical and radiological evidence of disease activity and induces T-lymphocyte proliferation even when cells are suboptimally stimulated by activatory stimuli. We conclude that this new IFN-gamma-activated Ca2+ influx seems to be highly specific for MS (especially during its active phase), and could be important for the intracellular regulation of cells involved in demyelination. The presence of the influx in T lymphocytes from MS patients could account for the reported temporal association between infections and clinical relapses

  353. Hartung HP, Archelos JJ, Zielasek J, Gold R, Koltzenburg M, Reiners KH, Toyka KV (1995) Circulating adhesion molecules and inflammatory mediators in demyelination: a review. Neurology 45:S22-S32
    Abstract: Accumulating evidence shows that adhesion molecules are critically involved in inflammatory demyelination in the focusing of systemic immune responses into the target tissue, the nervous system. Adhesion molecules are upregulated through the action of cytokines. Tumor necrosis factor alpha appears to be of prime importance. Circulating adhesion molecules probably reflect acute inflammatory episodes in the central and peripheral nervous system, but may also function to modulate ongoing inflammatory responses. Cytokines released by TH1 cells render resident and immigrant macrophages, as well as Microglia, activated to synthesize and release increased amounts of inflammatory mediators, such as oxygen radicals, nitric oxide metabolites, and components of the complement system. A more detailed understanding of the sequence of immunopathologic events that culminate in myelin damage in the central and peripheral nervous systems has revealed several sites to which more specific and effective immunointervention can be targeted

  354. Jiang H, Milo R, Swoveland P, Johnson KP, Panitch H, Dhib-Jalbut S (1995) Interferon beta-1b reduces interferon gamma-induced antigen-presenting capacity of human glial and B cells. J.Neuroimmunol. 61:17-25
    Abstract: Interferon (IFN) beta-1b has been shown to alter the course of multiple sclerosis and to inhibit MHC class II expression, but its effect on antigen presentation has not been examined in a functional assay (Neurology 43 (1993) 655-661). The effect of IFN beta-1b on alloantigen presentation by human antigen-presenting cells (APC) including human fetal astrocytes (HFA) and Microglia was examined. The effect of IFN beta-1b on the ability of B cells to present tetanus toxoid (TT) to TT-specific T cell lines was also examined. APC were pre-treated with IFN gamma (100 units/ml), IFN beta-1b (10-2000 units/ml), or a combination of IFN gamma and IFN beta-1b for 3 days and washed thoroughly prior to culture with allogeneic peripheral blood lymphocytes (PBL) for a period of 6 days. Lymphocyte proliferation was then measured by tritiated thymidine uptake. Treatment of the APC with IFN beta-1b resulted in a reduction in the IFN gamma-enhanced alloantigen-induced T cell responses. This reduction ranged between 50 and 70%, was associated with a 30-50% reduction in HLA class II (DR) and 35-40% reduction in ICAM-1 expression on the HFA used as APC. IFN beta-1b pretreatment of B cells reduced their constitutive and IFN gamma enhanced capacity to present TT to TT-specific T cell lines by 50-80%. This was associated with a 30 +/- 11% mean reduction in class II (DR) expression and approximately 50 +/- 1% reduction in ICAM-1 expression in IFN beta-1b + IFN gamma-treated B cells compared to IFN gamma-treated B cells (mean of three experiments).(ABSTRACT TRUNCATED AT 250 WORDS)

  355. Liuzzi GM, Riccio P, Dal Canto MC (1995) Release of myelin basic protein-degrading proteolytic activity from Microglia and macrophages after infection with Theiler's murine encephalomyelitis virus: comparison between susceptible and resistant mice. J.Neuroimmunol. 62:91-102
    Abstract: Theiler's murine encephalomyelitis virus (TMEV) produces a chronic inflammatory demyelinating disease in its natural host, the mouse. A delayed-type hypersensitivity (DTH) response to viral antigens generally correlates with susceptibility to the disease and is thought to play an important role in the pathogenesis of demyelination in this model of human multiple sclerosis (MS). The hallmark of DTH responses is the recruitment by activated Th-1 cells of lymphoid cells and especially macrophages in infected areas. It is believed that soluble factors released by these cells would produce tissue damage, particularly myelin breakdown. In the present study, we compared TMEV-infected macrophages and Microglia, isolated from both susceptible SJL/J and resistant C57BL/6 mice, for their ability to secrete proteolytic enzymes capable of degrading myelin basic protein. In addition, we studied whether supernatants from infected Microglia/macrophages were also capable of killing oligodendrocytes in the same in vitro system. As detected by SDS-PAGE, MBP-degrading proteolytic activity was found only in supernatants from infected SJL/J Microglia and macrophages, but not in supernatants collected from infected C57BL/6 Microglia and macrophages, or in supernatants from mock-infected SJL/J and C57BL/6 cells. Similarly, incubation of E20.1 cells, an immortalized line of oligodendrocytes, with infected SJL/J, but not C57BL/6 supernatants, resulted in cytotoxic activity. When cells from resistant C57BL/6 mice were treated with LPS, they became susceptible to infection and also secreted proteolytic enzymes. The proteolytic activity released from infected Microglia and macrophages was found to be dose-dependent, was inactivated by heat, and was inhibited by phenylmethylsulphonyl fluoride (PMSF). These results indicate that a serine protease is released from infected Microglia and macrophages and suggest a role for proteases in TMEV-induced myelin injury

  356. Miller SD, McRae BL, Vanderlugt CL, Nikcevich KM, Pope JG, Pope L, Karpus WJ (1995) Evolution of the T-cell repertoire during the course of experimental immune-mediated demyelinating diseases. Immunol.Rev. 144:225-244
    Abstract: Fig. 6 depicts a model for epitope spreading in T cell-mediated demyelination. The acute phase of disease is due to T cells specific for the initiating epitope, which can be either a determinant on the CNS target organ of the autoimmune response or a determinant on a persisting, CNS-tropic virus. The primary T cell response is responsible for the initial tissue damage by the production of proinflammatory Th1 cytokines which can affect myelination directly (Selmaj et al. 1991) and indirectly by their ability to recruit and activate macrophages to phagocytize myelin (Cammer et al. 1978). As a result of myelin damage and opening of the blood-brain-barrier during acute disease, T cells specific for endogenous epitopes on the same and/or different myelin proteins are primed and expand either in the periphery or locally in the CNS. These secondary T cells initiate an additional round of myelin destruction, leading to a clinical relapse by production of additional pro-inflammatory cytokines, similar to the bystander demyelination operative during acute disease. It will be of great interest to determine the relative contributions of local and systemic immune responses to these endogenous neuroepitopes. It is possible that local CNS presentation of endogenous neuroepitopes following acute CNS damage could be mediated by infiltrating inflammatory macrophages, activated Microglial cells, endothelial cells and/or astrocytes. These tissue resident antigen presenting cells have been shown to upregulate expression of MHC class II (Sakai et al. 1986, Traugott & Lebon 1988), certain adhesion molecules (Cannella et al. 1990), and B7 costimulatory molecules (K. M. Nikcevich, J. A. Bluestone, and S. D. Miller, in preparation) in response to pro-inflammatory cytokines. The data on epitope spreading provided by the murine demyelinating disease models clearly illustrate the dynamic nature of the T cell repertoire during chronic inflammation in a specific target organ. The contribution of epitope spreading to chronic CNS demyelination could be considered to be a special case since tolerance to myelin epitopes would be expected to be inefficient due to their sequestration behind the blood-brain-barrier. However, the recent description of epitope spreading in response to pancreatic antigens in spontaneous diabetes in the NOD mouse may indicate that this phenomenon is operative in a variety of organ-specific experimental and spontaneous autoimmune diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

  357. Morgan TE, Laping NJ, Rozovsky I, Oda T, Hogan TH, Finch CE, Pasinetti GM (1995) Clusterin expression by astrocytes is influenced by transforming growth factor beta 1 and heterotypic cell interactions. J.Neuroimmunol. 58:101-110
    Abstract: This study characterizes the effect of transforming growth factor (TGF) beta 1 on clusterin expression in rat brain cells. 24 h after an acute unilateral intracerebroventricular infusion of TGF-beta 1, clusterin mRNA prevalence was increased in astrocytes that contained immunoreactive (IR) glial fibrillary acidic protein (GFAP). TGF-beta 1 selectively induced clusterin mRNA in astrocytes, as no clusterin mRNA was detected in neurons, oligodendrocytes, or Microglia. TGF-beta 1 induced a bilateral increase in clusterin mRNA per astrocyte. Astrocyte hypertrophy (GFAP-IR area) was only increased on the ipsilateral side. In pure astrocyte cultures, TGF-beta 1 (200 pM) decreased clusterin mRNA levels and the rate of clusterin RNA transcription. However, in cultures of astrocytes that contained Microglia and oligodendrocytes (mixed glia cultures), TGF-beta 1 caused a dose-dependent increase in astrocytic clusterin mRNA levels. The astrocytes that responded to TGF-beta 1 included two GFAP-IR subtypes, type 1 and 2. TGF-beta 1 increased clusterin protein in the conditioned medium from cultured glia, in either monotypic or mixed glial cultures. Thus, TGF-beta 1 and heterotypic cell interactions influence clusterin expression by astrocytes and may be important to the role of clusterin in multiple sclerosis, AIDS, and Alzheimer's disease

  358. Nyland H, Myhr KM (1995) [multiple sclerosis]. Tidsskr.Nor Laegeforen. 115:2072-2077
    Abstract: multiple sclerosis is a chronic inflammatory disease of the central nervous system which affects young and middle-aged adults. The clinical symptoms and course vary considerably; most patients experience a relapsing-remittent course which may become secondary progressive, a benign course with a favourable prognosis is seen in 30-40%. 10-15% experience a primary progressive course, with a less favourable prognosis. Magnetic resonance imaging, MRI, has become the most important paraclinic investigation and MRI with paramagnetic contrast enhancement reveals "subclinical" disease activity. Demyelination is caused by phagocytosis of Microglial cells which appear to be activated by cytokines produced by T helper cells. A delayed type autoimmune response to myelin antigens is probably involved, initiated by a viral infection. Immunosuppressive treatment, corticosteroids and interferons have been shown to affect the MRI behaviour, and reduce the frequency of relapse. The effect on the natural course of the disease has been less convincing and no treatment will reverse long standing neurological dysfunction

  359. Phillips MJ, Weller RO, Kida S, Iannotti F (1995) Focal brain damage enhances experimental allergic encephalomyelitis in brain and spinal cord. Neuropathol.Appl.Neurobiol. 21:189-200
    Abstract: The immunological basis of multiple sclerosis (MS) is well recognized but the factors inducing MS lesions are unclear. In this study, we test the hypothesis that focal brain injury, inflicted during the pre-clinical stages of experimental allergic encephalomyelitis (EAE), will enhance the severity of immunological damage in the cerebral hemispheres and spinal cord. Acute EAE was induced in 30 Lewis rats by the injection of guinea pig spinal cord homogenate in complete Freund's adjuvant. A cryolesion to the surface of the left cerebral hemisphere was induced at 3 days (n = 6) or 8 days (n = 10) postinoculation (p.i.) and animals were killed at 15 days p.i. Control animals were EAE only (n = 9), cryolesion only (n = 4), EAE and sham cryolesion (n = 5) and normal animals (n = 3). Brain and spinal cord were stained by immunocytochemistry using W3/13 (T-lymphocytes) OX6 (MHC Class II) and GFAP (astrocytes) antibodies. The results showed a 2-fold increase in the number of EAE lesions in the brain with significant and widespread increase of MHC Class II antigen expression by Microglia, in the cryolesion EAE 8 days p.i. when compared with EAE only animals. The pattern of enhancement suggests that it is due to (i) local spread of tissue or serum factors from the cryolesion; (ii) neural factors affecting remote regions of the CNS; (iii) stimulation of the immune system which may occur due to products of brain injury draining to regional cervical lymph nodes. Investigation of the mechanisms involved may prove fruitful in establishing factors which initiate, aggravate or ameliorate brain damage in multiple sclerosis

  360. Renno T, Krakowski M, Piccirillo C, Lin JY, Owens T (1995) TNF-alpha expression by resident Microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines. J.Immunol. 154:944-953
    Abstract: The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as Microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult Microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident Microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells

  361. Sedgwick JD (1995) Immune surveillance and autoantigen recognition in the central nervous system. Aust.N.Z.J.Med. 25:784-792
    Abstract: The central nervous system (CNS) is considered to be a severely disadvantaged site for the elicitation of immune responses. First, there is no specialised lymphatic drainage. Second, both glia and neuronal cells normally do not express appreciable levels of major histocompatibility complex molecules. Third, the vasculature of the CNS is, at least in most places, lined by endothelial cells that have tight junctions and form a barrier (the blood-brain barrier) against most molecules and cells present in the circulation. Fourth, the cells most important in the initiation of immune response, the leucocyte dendritic cell, are not present. Nevertheless, the existence of inflammatory diseases of this tissue, occurring naturally as in multiple sclerosis or in animals after peripheral immunisation with CNS autoantigens, indicates that the immune system can access and recognise antigens in this site. How this is achieved has become clearer in recent years and primarily seems to involve extravasation of activated but not resting T cells across the blood-brain barrier, and recognition of antigen on macrophage-like perivascular cells, rather than cells within the CNS parenchyme such as astrocytes or Microglia. The processes involved in immunological patrolling of the CNS and development of autoimmune inflammatory disease are reviewed

  362. Seilhean D, Duyckaerts C, Hauw JJ (1995) [HIV and dementia: neuropathology]. J.Neuroradiol. 22:161-162
    Abstract: Cognitive disorders associated with HIV infection may be due to focal lesions (lymphoma, toxoplasmosis, progressive multifocal leukoencephalitis, etc.), metabolic encephalopathy (e.g. hepatic insufficiency) or psychiatric disorders (depression). In the absence of such causes a "cognitive and motor syndrome associated with HIV infection" has been defined on clinical criteria (Working group of the American Academy of Neurology, 1991). This syndrome is not consistently associated with any specific lesion. Neither the multifocal encephalitis of HIV or CMV infection nor the diffuse leukoencephalopathy associated with HIV are the only causes. The existence of a neocortical neuronal loss has been suggested by several retrospective studies, but our prospective study has not shown cortical or subcortical atrophy. Measurement of neuronal density in Brodmann's areas 4,9 and 40 has not revealed a significant loss either global, by layer, or by column. The only constant lesion was gliosis of the cortex and white matter. Neuronal loss, therefore, is not indispensable to the occurrence of cognitive disorders in AIDS. The mechanism of dementia might be: dysfunction of cortical neurons (dendritic abnormalities, virus/neurotransmitter competition); subcortical dysfunction, as suggested by the high density of Microglial nodules in that region; white matter lesions which could be due to abnormalities in the blood-brain barrier. The expression of cell adhesion molecules (VCAM-1, VLA-4, ICAM-1 and LFA-1) by endothelial cerebral cells is not significantly different in AIDS patients, demented or not, and in patients with multiple sclerosis. In contrast, the expression of VCAM-1 by astrocytes is significantly increased in demented AIDS patients compared with non demented ones.(ABSTRACT TRUNCATED AT 250 WORDS)

  363. Singhrao SK, Morgan BP, Neal JW, Newman GR (1995) A functional role for corpora amylacea based on evidence from complement studies. Neurodegeneration. 4:335-345
    Abstract: Few theories have been advanced for the production of corpora amylacea (CA) by the normal ageing brain and by the CNS under various neurological conditions. Proteins derived from neurons and oligodendrocytes are found in CA and to understand their origins brain tissue from patients with Alzheimer's disease (AD), multiple sclerosis (MS) and Pick's disease (PD) were tested for complement activity. All CA were immunopositive for antisera to classical pathway-specific components, the activation products C3d and the terminal complement complex (TCC), the C3 convertase regulator membrane cofactor protein (MCP) and the fluid phase regulators S-protein and clusterin. CA were immunonegative for the alternative complement pathway proteins and the complement regulators, decay accelerating factor (DAF) and CD59. Western immunoblotting of isolated solubilized CA from the same tissues demonstrated a weak band for MCP but TCC was more easily shown by immunoprecipitation. A filamentous fringe around CA, probably of astrocytic origin, was also immunopositive for complement factors. CA consist of an inert mucopolysaccharide matrix encasing ubiquitinated proteins, resulting from death of and damage to neurons, myelin and oligodendrocytes. A function of CA, therefore, could be to prevent the recognition of these immunogenic proteins by lymphocytes and Microglia and thus protect the CNS from further injury

  364. Sippy BD, Hofman FM, Wallach D, Hinton DR (1995) Increased expression of tumor necrosis factor-alpha receptors in the brains of patients with AIDS. J.Acquir.Immune.Defic.Syndr.Hum.Retrovirol. 10:511-521
    Abstract: Tumor necrosis factor (TNF)-alpha has been shown to be increased in brain tissue of AIDS patients and may function as a mediator of cerebral damage. We initiated a study to determine the cellular localization and degree of protein and mRNA expression of the two specific TNF-alpha receptors (TNF-Rs), p55 and p75, in brain tissues from AIDS patients. Cerebral white matter obtained at autopsy from 13 AIDS patients, 10 unhealthy controls, and 4 healthy controls was evaluated. Double-label immunohistochemistry revealed prominent up-regulation of p55 and p75 TNF-Rs on activated macrophages and Microglial cells in all AIDS patients; no increased staining was found on astrocytes. Staining was most prominent in patients with opportunistic infection of the brain and in Microglial nodules of patients with HIV encephalitis. Brain tissues also showed increased expression of interleukin (IL)-1 beta, IL-6, and TNF-alpha, cytokines known to up-regulate the TNF-Rs. Increased staining for TNF-Rs was also found in patients with multiple sclerosis, chronic cerebral edema, and radiation necrosis but not in an asymptomatic HIV-positive patient without AIDS. Reverse transcriptase polymerase chain reaction performed on adjacent sections from five AIDS patients revealed up-regulation from normal for p55 in all patients and for p75 in three patients. The up-regulation of both TNF-Rs in AIDS suggests that macrophages and Microglial cells may be important in amplifying the TNF-alpha response

  365. Vartanian T, Li Y, Zhao M, Stefansson K (1995) Interferon-gamma-induced oligodendrocyte cell death: implications for the pathogenesis of multiple sclerosis. Mol.Med. 1:732-743
    Abstract: BACKGROUND: The histopathology of multiple sclerosis (MS) is characterized by a loss of myelin and oligodendrocytes, relative preservation of axons, and a modest inflammatory response. The reasons for this selective oligodendrocyte death and demyelination are unknown. MATERIALS AND METHODS: In light of the T lymphocyte and macrophage infiltrates in MS lesions and the numerous cytokines these cells secrete, the direct influence of cytokines on survival of cultured oligodendrocytes and sensory neurons was investigated. Expression of cytokines in vivo was determined by immunolabeling cryostat sections of snap-frozen tissue containing chronic active lesions from four different patients. The samples were also analyzed for the presence of apoptotic nuclei by in situ labeling of 3'-OH ends of degraded nuclear DNA. RESULTS: The results showed: (i) interferon-gamma (IFN gamma) to be a potent inducer of apoptosis among oligodendrocytes in vitro and that this effect can be reversed by leukemia inhibitory factor (LIF); (ii) IFN gamma has a minimal effect on the survival of cultured neurons; (iii) IFN gamma at the margins of active MS plaques but not in unaffected white matter; (iv) evidence for apoptosis of oligodendrocytes at the advancing margins of chronic active MS plaques. CONCLUSIONS: Injury to a substantial number of oligodendrocytes in MS is the results of programmed cell death rather than necrotic cell death mechanisms. We postulate that IFN gamma plays a role in the pathogenesis of MS by activating apoptosis in oligodendrocytes

  366. Amor S, Groome N, Linington C, Morris MM, Dornmair K, Gardinier MV, Matthieu JM, Baker D (1994) Identification of epitopes of myelin oligodendrocyte glycoprotein for the induction of experimental allergic encephalomyelitis in SJL and Biozzi AB/H mice. J.Immunol. 153:4349-4356
    Abstract: A recombinant protein corresponding to the Ig-like domain of myelin oligodendrocyte glycoprotein (MOG) and synthetic 15-mer peptides of the whole MOG molecule with eight amino acid overlaps were screened for their ability to induce experimental allergic encephalomyelitis (EAE) in Biozzi AB/H (H-2dq1) and SJL (H-2S) mice. Clinical and histologic evidence of EAE developed after sensitization with the recombinant MOG protein in both AB/H and SJL mice. In AB/H mice at least three MOG epitopes within residues 1-22, 43-57, and 134-148 induced clinical and histologic EAE, whereas only the sequence 92-106 was encephalitogenic in SJL mice. Histologically, the inflammatory response in the central nervous system consisted of perivascular accumulations of CD5+ T cells and F4/80+ macrophage/Microglia cells equally distributed in the brain and spinal cord. The subpial/meningeal infiltration, characteristic of mouse EAE induced with spinal cord homogenate, was only observed in cases of severe clinical disease in SJL mice in which the cellular infiltrates predominated in the spinal cord. In spite of the presence of histologic lesions in AB/H mice immunized with MOG, clinical disease either rapidly resolved or was clinically silent. In contrast to immunization of SJL mice with recombinant MOG, sensitization to MOG 92-106 induced severe clinical paralysis. After recovery these animals relapsed and exhibited demyelinated lesions. This study is the first to describe encephalitogenic epitopes of MOG that induce both clinical and histologic signs of EAE in mice. These and previous findings implicating MOG as a target Ag for Ab-mediated attack in EAE suggest that such autoreactivity to MOG may be significant in the development of human demyelinating diseases such as multiple sclerosis

  367. Antel JP, Williams K, Blain M, McRea E, McLaurin J (1994) Oligodendrocyte lysis by CD4+ T cells independent of tumor necrosis factor. Ann.Neurol. 35:341-348
    Abstract: The capacity of human CD4+ T cells to lyse heterologous human oligodendrocytes in an 18-hour chromium 51-release assay was compared to that of systemic blood-derived macrophages and central nervous system-derived Microglia. CD4+ T cells, activated with either phytohemagglutinin, anti-CD3 antibody, or antigen (myelin basic protein), could induce lysis of the oligodendrocytes whereas macrophages and Microglia, activated with interferon-gamma and lipopolysaccharide, could not. The CD4+ T-cell effect was not inhibited with an anti-tumor necrosis factor-alpha-neutralizing antibody. Both the CD4+ T cells and the macrophages could induce lysis of tumor necrosis factor-sensitive rodent cell lines, Wehi 164, and L929; these effects were inhibited with anti-tumor necrosis factor antibody. Pretreatment of the CD4+ T cells with cyclosporine or mitomycin C did not inhibit oligodendrocyte lysis. These results indicate that at least in vitro, CD4+ T cells can induce a form of oligodendrocyte injury that is not reproduced by macrophages or Microglia or by tumor necrosis factor. The non-major histocompatibility complex (MHC)-restricted injury of oligodendrocytes induced by both myelin antigen-reactive and mitogen-stimulated T cells may provide a basis whereby cytotoxic CD4+ T cells could interact with a target cell that does not express MHC class II molecules. Our results suggest that immune-mediated oligodendrocyte/myelin injury, as is postulated to occur in the disease multiple sclerosis, may involve multiple effector mechanisms

  368. Banati RB, Graeber MB (1994) Surveillance, intervention and cytotoxicity: is there a protective role of Microglia? Dev.Neurosci. 16:114-127
    Abstract: The study of Microglial cell biology has become the key to understanding the brain's fundamental tissue reactions as well as the cellular mechanisms underlying CNS disease. This article focuses on glial-neuronal interactions with special reference to human pathology. Three important areas of brain pathology are critically reviewed: multiple sclerosis and CNS inflammation, the brain in AIDS and opportunistic infections, and neurodegenerative disorders. Although Microglial cytotoxicity may cause bystander damage, e.g. in ischemia, there is little evidence to support the view that Microglial activation per se is pathogenic. Results suggesting that one important normal function of Microglia is to protect the integrity of the central nervous system are discussed. The concept is proposed that Microglia function as a highly developed guardian to the CNS

  369. Bo L, Mork S, Kong PA, Nyland H, Pardo CA, Trapp BD (1994) Detection of MHC class II-antigens on macrophages and Microglia, but not on astrocytes and endothelia in active multiple sclerosis lesions. J.Neuroimmunol. 51:135-146
    Abstract: Tissue sections of brains from patients with multiple sclerosis (MS) and from control individuals were immunostained with MHC class II and glial or vascular endothelial cell antibodies and analyzed by confocal microscopy. MHC class II was abundant in and around actively demyelinating MS lesions and was detected on Microglia, phagocytic macrophages, and perivascular macrophages. Astrocytes and vascular endothelial cells were MHC class II-negative. Changes in the size and shape of MHC class II-positive cells associated with MS lesions suggest that Microglia transform into phagocytic macrophages, and that they are actively involved in demyelination. Many MHC class II-positive perivascular macrophages within MS lesions contained abundant intracellular MHC class II immunoreactivity; these cells may be involved in antigen presentation and in T cell activation

  370. Brosnan CF, Battistini L, Raine CS, Dickson DW, Casadevall A, Lee SC (1994) Reactive nitrogen intermediates in human neuropathology: an overview. Dev.Neurosci. 16:152-161
    Abstract: Nitric oxide (NO) is a recently recognized messenger molecule that has been shown to possess pleiotropic properties, including vasodilation, neurotransmission, cytotoxicity and antimicrobial activity. Constitutive and inducible forms of NO synthase (NOS) have been identified. Activation of cNOS releases relatively low levels of NO for short periods of time whereas induction of iNOS releases high levels of NO for extended periods of time. In rodents, iNOS is predominantly found in cells of the monocyte/macrophage series, including Microglia, where it is induced by a combination of bacterial products and cytokines. cNOS and iNOS have also been reported in rodent astrocytes. Activation of iNOS in the CNS could be toxic to many different cell types, including neurons and oligodendrocytes. iNOS, however, has been difficult to demonstrate in human peripheral blood cells, suggesting that the regulation of expression of this enzyme in humans is different from that found in rodents. In this overview, we show that in human glial cells cultured in vitro, astrocytes, but not Microglia, can be induced by cytokines to express NO-like activity. Bacterial products are without effect, but a combination of IL-1 and TNF alpha or IFN gamma is a potent stimulus. NO production by astrocytes inhibits Cryptococcus neoformans growth in vitro. In vivo, we show in acute multiple sclerosis lesions, intense NADPH-diaphorase activity is present in hypertrophic astrocytes in the lesion center and at the lesion edge, whereas Microglia are nonreactive. Increased NADPH-diaphorase activity colocalizes with immunoreactivity for IL-1 and TNF. These results suggests that the induction of reactive nitrogen intermediates in humans differs from that found in rodents, and supports the conclusion that hypertrophic astrocytes are the major source of NO-like activity in the inflamed CNS

  371. Claudio L, Martiney JA, Brosnan CF (1994) Ultrastructural studies of the blood-retina barrier after exposure to interleukin-1 beta or tumor necrosis factor-alpha. Lab Invest 70:850-861
    Abstract: BACKGROUND: During inflammatory conditions of the central nervous system (CNS), the protective function of the blood-brain barrier (BBB) may be compromised, resulting in CNS edema. However, it is not well understood how inflammatory cells may increase BBB permeability, since increased transendothelial transport of serum proteins is observed in CNS capillaries that are not directly in contact with inflammatory cells. One possible explanation may be that soluble inflammatory factors may cause BBB changes, since pathologic conditions that increase circulating cytokines produce detectable increases in BBB permeability. EXPERIMENTAL DESIGN: To investigate the role of inflammatory cytokines in induction of endothelial cell changes and inflammation in the CNS, we utilized the rabbit retinal system as a model. This system shows vascularization similar to the BBB, and is termed the blood-retina barrier (BRB). The rabbit visual system allows injection of cytokines, causing minimal trauma, and the contralateral eye serves as an intra-animal control. RESULTS: Ultrastructural morphometric analysis of vesicular content in BRB endothelium showed significant increase at 3 hours postintravitreal injection of interleukin-1 beta (IL-1 beta) or tumor necrosis factor-alpha (TNF-alpha). Increased transport did not correlate with increased vitreal protein. However, intravascular tracer (horseradish peroxidase) revealed that pericytes, Muller cells, and perivascular Microglia accumulate serum proteins, thus acting as sinks for extravasated proteins after BRB disruption. The IL-1 beta-induced inflammatory response was characterized by polymorphonuclear and mononuclear cells, whereas the TNF-alpha-induced response was less intense and comprised monocytes and occasional eosinophils. At the height of inflammation, IL-1 beta produced large gaps between endothelial cells that allowed for extensive cellular inflammation and hemorrhage. TNF-alpha induced necrotic changes on endothelial cells, being most severe at 3 hours postintravitreal injection, revascularization was noted at 24 hours postintravitreal injection. CONCLUSIONS: These results demonstrate that proinflammatory effects of IL-1 beta and TNF-alpha in the BRB initiate many of the changes associated with inflammation of the CNS vasculature, such as those induced during experimental autoimmune encephalitis and multiple sclerosis. Once the permeability of the BRB endothelium is increased, perivascular phagocytic cells such as perivascular, Microglia and Muller cells may act as secondary barriers to extravasated proteins

  372. Couraud PO (1994) Interactions between lymphocytes, macrophages, and central nervous system cells. J.Leukoc.Biol. 56:407-415
    Abstract: Brain has often been considered as an "immunologically privileged organ," not normally accessible to leukocyte traffic, at least in part because of the presence of the blood-brain barrier, constituted by a specialized microvasculature and surrounding astrocytes, which restricts the exchanges between blood and brain. However, more recent studies have revealed that activated leukocytes can cross into the CNS, at very low levels under normal conditions, in much higher numbers during neuropathological disorders like multiple sclerosis or retroviral infection, and, within brain parenchyma, interact with CNS cells. The present review will thus highlight the multidirectional communication network, based on adhesion molecule expression and cytokine production, which appears in such situations between infiltrated leukocytes, brain microvessel endothelial cells, macroglia (including astrocytes and oligodendrocytes), Microglial cells and neurons

  373. D'Souza SD, Antel JP, Freedman MS (1994) Cytokine induction of heat shock protein expression in human oligodendrocytes: an interleukin-1-mediated mechanism. J.Neuroimmunol. 50:17-24
    Abstract: In this study, we examined the role of cytokines, known to be in elevated levels in multiple sclerosis (MS) plaques, in regulating oligodendrocyte (ODC) expression of heat shock protein (hsp) in human brain-derived glial cell cultures. Using dual-stain immunohistochemistry, we initially compared the ability of a mixture of cytokines (IL-1 alpha, IL-1 beta, IL-2, IL-6, IL-8, TNF-alpha, TNF-beta, IFN-beta and IFN-gamma) with that of physical stimuli such as heat shock and peroxide, to increase cellular expression of the mainly inducible hsp72 species in mixed glial cell cultures (containing ODC, astrocytes and Microglia). Similar to heat shock and peroxide, the cytokine mixture induced hsp72 expression only in ODC (70 +/- 5% vs. a baseline of 3 +/- 1% positive cells). When used individually, however, only IL-1 alpha (79 +/- 3%), IFN-gamma (70 +/- 2%) and TNF-alpha (65 +/- 5%) induced ODC hsp72 expression in mixed glial cell cultures. In purified ODC preparations, only IL-1 alpha induced hsp72 expression (84 +/- 4%). An IL-1 receptor antagonist (IL-1ra), abrogated hsp72 induction by IL-1 alpha (16 +/- 3%) as well as that due to IFN-gamma (14 +/- 1%) and TNF-alpha (13 +/- 2%) in mixed glial cell cultures. Furthermore, ODC express IL-1 receptors, detected by confocal laser scanning microscopy. Our data indicate that cytokines mediate hsp induction in ODC possibly via a final common pathway involving IL-1 binding to its receptor on ODC. Such interaction could enhance any putative ODC-immune interactions which are dependent on hsp molecule recognition

  374. Johnson RT (1994) The virology of demyelinating diseases. Ann.Neurol. 36 Suppl:S54-S60
    Abstract: Infectious agents have been postulated as causes of multiple sclerosis for over a century. The possible role of a virus or viruses is supported by data that (1) a childhood exposure is involved and "viral" infections may precipitate exacerbations of disease, (2) experimental infections in animals and natural infections in humans can cause diseases with long incubation periods, remitting and relapsing courses, and demyelination, and (3) patients with multiple sclerosis have abnormal immune responses to viruses. The pathogenesis of three human demyelinating diseases of known viral etiology is discussed. In progressive multifocal leukoencephalopathy, a papovavirus selectively infects oligodendrocytes and causes focal areas of demyelination. In postmeasles encephalomyelitis, the virus is lymphotrophic and disrupts immune regulation that can result in an autoimmune perivenular demyelinating illness without evidence of infection of the central nervous system. In human immunodeficiency virus-encephalopathy and myelopathy virus is present in macrophages and Microglia and the myelin abnormalities apparently are caused by soluble factors such as viral proteins, cytokines, or neurotoxins. These findings may have implications on how, when, and where to seek viruses in multiple sclerosis

  375. Lee SC, Liu W, Brosnan CF, Dickson DW (1994) GM-CSF promotes proliferation of human fetal and adult Microglia in primary cultures. Glia 12:309-318
    Abstract: Proliferation of Microglia/macrophages is a common finding in many central nervous system diseases. To identify mitogenic signals for human Microglia, we examined primary cultures of human fetal and adult Microglia after stimulation with cytokines, colony stimulating factors (CSFs), or LPS, using proliferating cell nuclear antigen (PCNA) expression as an index of cell proliferation. The results showed that both M-CSF and GM-CSF induced Microglial proliferation in fetal and adult human cultures, but that GM-CSF provided a much stronger stimulus. At 96 h post-stimulation, the mean PCNA labeling index was 2.4 for M-CSF and 13.3 for GM-CSF in fetal Microglia; in adult Microglia, the PCNA labeling index was 4.7 for M-CSF and 9.0 for GM-CSF. The effect of GM-CSF on fetal Microglia was dose dependent and synergistic with M-CSF. LPS abolished the basal level of PCNA labeling in adult Microglia, but in fetal Microglia, caused a slight increase in PCNA labeling (1.9) at 96 h and consistently enhanced Microglial cell survival and differentiation into highly branched cells. The production of GM-CSF in purified human fetal astrocyte and Microglial cultures was examined after stimulation with LPS, TNF-alpha, or IL-1 beta. Unlike M-CSF, neither cell type produced GM-CSF in unstimulated cultures; however, when stimulated with IL-1 beta, astrocytes expressed GM-CSF mRNA and protein, which accumulated in the culture through 72 h. In Microglia, LPS was the only effective inducing agent. An immunocytochemical study performed to identify in vivo sources of GM-CSF revealed selective labeling of reactive astrocytes in active lesions of multiple sclerosis and senile plaques of Alzheimer's disease. Our data demonstrate that both fetal and adult human Microglia are capable of proliferation in response to CSFs, GM-CSF being the more effective stimulus

  376. Mitrovic B, Martin FC, Charles AC, Ignarro LJ, Anton PA, Shanahan F, Merrill JE (1994) Neurotransmitters and cytokines in CNS pathology. Prog.Brain Res. 103:319-330
    Abstract: In summary, we have demonstrated an in vitro model for oligodendrocyte cell death that may be relevant to events in formation of lesions in MS. It involves cell contact to oligodendrocytes with activated, viable Microglia (or inflammatory macrophages), surface TNF-alpha, surface adhesion molecules, and production of NO. Precise mechanisms of TNF-alpha and ICAM-1/LFA-1 participation and the nature of the susceptibility of the oligodendrocyte are currently being studied

  377. Muller CD, Bocchini V, Giaimis J, Guerrieri P, Lombard Y, Poindron P (1994) Functional beta-glucan receptor expression by a Microglial cell line. Res.Immunol. 145:267-275
    Abstract: In the central nervous system, the functions of Microglia appear crucial after brain damage, when phagocytes eliminate cell debris, acting as the scavengers of the brain. Diseases where an active role for Microglia has been proposed recently include Alzheimer's disease, the acquired immune deficiency syndrome (AIDS) and multiple sclerosis. Only recently has it been possible to obtain a Microglial cell line retaining morphological and functional aspects of these cells and their secretory products. Sugar receptors are expressed by a variety of phagocytes in primary cultures, but in contrast, are absent on the majority of the described macrophage-like cell lines. We here establish, by 4 degrees C binding experiments, that this murine cell line, called BV-2, expresses a high level (9.86 +/- 0.91 x 10(5); n = 3) of beta-glucan receptors. At 37 degrees C, BV-2 cells show high phagocytic power that can only be inhibited by the free polysugar beta-laminarin (a poly-glucose) and not by mannan (a poly-mannose) as described for macrophages. The beta-glucan receptor expressed by the Microglial cell line BV-2 is fully functional in phagocytosis of unopsonized heat-killed yeast particles

  378. Newcombe J, Li H, Cuzner ML (1994) Low density lipoprotein uptake by macrophages in multiple sclerosis plaques: implications for pathogenesis. Neuropathol.Appl.Neurobiol. 20:152-162
    Abstract: Low density lipoprotein (LDL), the major carrier of plasma cholesterol, may enter the parenchyma of early multiple sclerosis (MS) lesions as a result of blood-brain barrier damage. We have used antibodies against LDL and epitopes found in LDL oxidized by two peroxidative end-products, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), to immunocytochemically stain MS plaques at different stages of pathology. Native LDL, epitopes of MDA-LDL, peptides of myelin basic protein and neutral lipid oil red O (ORO) staining were found to be co-localized within foamy macrophages in early and actively demyelinating MS plaques. Thus cholesterol esters, which are seen as Maltese crosses under polarized light in a proportion of foamy macrophages, appear to be derived from both LDL and myelin. ORO-negative astrocytes were strongly stained with the antibodies against 4-HNE-LDL and MDA-LDL, suggesting uptake of oxidatively modified protein products alone. Our findings suggest that a large proportion of the plasma LDL which enters the parenchyma of MS plaques is oxidatively modified in the lesion. Lipid peroxidation and oxidized LDL uptake by activated Microglia and infiltrating macrophages in the early stages of MS plaque development may play important roles in demyelination

  379. Porrini AM, Reder AT (1994) IFN-gamma, IFN-beta, and PGE1 affect monokine secretion: relevance to monocyte activation in multiple sclerosis. Cell Immunol. 157:428-438
    Abstract: Activated antigen-presenting cells and central nervous system Microglia produce IL-1 beta, TNF-alpha, IL-6, and PGE-1. These monokines participate in the lymphocyte activation, demyelination, and intrathecal immunoglobulin synthesis seen in multiple sclerosis (MS). Exacerbations of MS are ameliorated by IFN-beta, but provoked by IFN-gamma, possibly through an effect on monocytes (Mo). We studied the effects of IFNs and PG on monokine secretion under stringent low-endotoxin conditions. Spontaneous and IFN-gamma-induced IL-1 beta secretion was greater in MS than in NL Mo. IFN-beta did not inhibit IFN-gamma-induced secretion of monokines, which contrasts with IFN-beta's inhibitory effect on IFN-gamma-induced MHC class II expression. PGE1, a cAMP agonist, caused a 30-fold induction of IL-6 secretion. Indomethacin directly inhibited this induction. Low-dose IFN-beta, through effects on T cells, and cAMP agonists, through effects in T cells and Mo, may ameliorate inflammatory diseases characterized by excessive monokine secretion

  380. Raine CS (1994) multiple sclerosis: immune system molecule expression in the central nervous system. J.Neuropathol.Exp.Neurol. 53:328-337
    Abstract: The fundamental message emerging from immunologic and immunopathologic analyses of the brain and spinal cord in multiple sclerosis (MS) is that during inflammation, the central nervous system (CNS) is capable of interactions with the lymphoid system, mainly through induced (as opposed to constitutive) expression of immune system-specific molecules on CNS elements. CNS endothelium, astrocytes and Microglial cells are the main participants, with oligodendrocytes and neurons remaining essentially inert. There appears to be nothing unique about the manner in which the CNS responds to inflammation or in the molecules expressed. The ensuing adhesion molecules, pro-inflammatory and regulatory cytokines, histocompatibility molecules, and T and B cell markers, are difficult to distinguish from those occurring in peripheral lymphoid tissue. However, differences certainly exist in the outcome of an inflammatory insult in the CNS versus other, peripheral tissues, whereby there is generally a poor reparatory response. Reasons for the latter appear to lie in the anatomical complexity of the CNS, its vulnerability to damage by soluble mediators, and in the white matter (the battlefield for the inflammatory attack in MS), the exquisite sensitivity of the oligodendrocyte and its myelin to exogenous factors. With the aid of examples drawn from experimental allergic encephalomyelitis, the prime animal model for MS, a number of approaches to prevent or downregulate CNS inflammation during immune-mediated demyelination are presented as possible therapeutic avenues for MS, some of which are already under investigation

  381. Scolding NJ, Zajicek JP, Wood N, Compston DA (1994) The pathogenesis of demyelinating disease. Prog.Neurobiol. 43:143-173

  382. Ulvestad E, Williams K, Mork S, Antel J, Nyland H (1994) Phenotypic differences between human monocytes/macrophages and Microglial cells studied in situ and in vitro. J.Neuropathol.Exp.Neurol. 53:492-501
    Abstract: This report describes a phenotypic differentiation pattern conceived to distinguish invading monocytes from resident Microglia in frozen and formalin-fixed human CNS. Phagocytic cells in normal and diseased CNS (multiple sclerosis and encephalitis) were studied immunohistochemically with a panel of antibodies, and phenotypic characteristics were compared with cultured monocytes/macrophages and Microglia. Monocytes/macrophages were positive for the markers non-specific esterase, myeloperoxidase, L1, lysozyme, RFD7, and CD14, whereas Microglia were negative for the same markers. Both populations of cells were positive for CD11c and CD68. Our results indicate that invading monocytes/macrophages mainly have a perivascular location in active multiple sclerosis lesions, whereas invading monocytes/macrophages also infiltrate the parenchyma in acute inflammatory CNS diseases such as in encephalitis

  383. Ulvestad E, Williams K, Bjerkvig R, Tiekotter K, Antel J, Matre R (1994) Human Microglial cells have phenotypic and functional characteristics in common with both macrophages and dendritic antigen-presenting cells. J.Leukoc.Biol. 56:732-740
    Abstract: Resting Microglia comprise up to 13% of the cells in human central nervous system (CNS) white matter. Their large number and dendritic morphology make them ideally suited to survey the CNS for noxious stimuli. Upon activation Microglia gradually lose dendritic processes and transform into typical phagocytic macrophages. Microglia have been implicated as the main antigen presenting cell within the CNS, and appear to be of central importance as effectors and regulators of demyelination. To further characterize the capacity for immune reactivity within the human CNS, we have studied several characteristics of Microglia, both in situ and in vitro. We find that human Microglia have ultrastructural, phenotypic (CD11c, CD68, acid phosphatase), and functional (FcR and CR mediated phagocytosis) properties typical for cells of the monocyte lineage. Our data indicate that Microglia also have properties in common with dendritic antigen-presenting cells. Electron microscopy studies show extended dendritic cell processes on cultured Microglia, and Microglia are, like dendritic cells, negative for the monocyte markers nonspecific esterase, endogenous peroxidase, CD14, and RFD7. Microglia constitutively express HLA-DR in situ, and express the dendritic cell marker RFD1 upon activation. Coculturing of Microglia with CD4+ T cells results in clustering of T cells around Microglia and initiation of a mixed lymphocyte reaction, both distinguishing features of dendritic cells. These functional properties of Microglia may be of importance for the maintenance of an immunologic response in the CNS, an organ where dendritic cells, in contrast to other organs, have not previously been identified

  384. Ulvestad E, Williams K, Vedeler C, Antel J, Nyland H, Mork S, Matre R (1994) Reactive Microglia in multiple sclerosis lesions have an increased expression of receptors for the Fc part of IgG. J.Neurol.Sci. 121:125-131
    Abstract: Receptors for the Fc part of IgG, FcRI (CD64), FcRII (CD32), and FcRIII (CD16) were studied by indirect immunoperoxidase staining of cryostat sections from normal and multiple sclerosis (MS) brains. Microglia in the parenchyma of normal white matter had a dendritic morphology, and were weakly stained by monoclonal antibodies (mAbs) to FcRI, FcRII, and FcRIII. In active MS lesions reactive Microglia were strongly stained by the mAbs 32.2 (FcRI), IV-3 (FcRII), and 3G8 (FcRIII). Perivascular macrophages were stained by all anti-FcR mAbs in both normal white matter and in MS lesions, whereas endothelial cells were stained by the anti-FcRIII mAb only. The FcR on Microglia and perivascular macrophages may be of functional importance in antibody-dependent cell-mediated cytotoxicity (ADCC), phagocytosis, and local immunoregulation. FcR on endothelium may be of importance in binding and transportation of immune complexes into the CNS. FcR mediated functions may consequently be highly relevant to the pathogenesis of MS

  385. Ulvestad E, Williams K, Bo L, Trapp B, Antel J, Mork S (1994) HLA class II molecules (HLA-DR, -DP, -DQ) on cells in the human CNS studied in situ and in vitro. Immunology 82:535-541
    Abstract: Human leucocyte antigen (HLA) class II molecules expressed by antigen-presenting cells (APC) are major restriction elements in the interaction between APC and T cells of the CD4+ subtype. To explore the immune accessory function of cells in the central nervous system (CNS), we studied the expression of HLA-DR, -DP, and -DQ molecules on CNS cells in situ and in vitro. Reactive Microglia and perivascular cells in multiple sclerosis lesions expressed all three HLA class II molecules, whereas Microglia in the normal CNS expressed HLA-DR only. All three HLA class II molecules were up-regulated on cultured Microglia after stimulation with interferon-gamma (IFN-gamma). Microglial stimulation of allogeneic CD4+ T cells in a mixed lymphocyte reaction (MLR) was effectively blocked using anti-HLA-DR monoclonal antibodies (mAb) but not using anti-HLA-DQ mAb. HLA class II-positive astrocytes and endothelial cells were not identified in normal or diseased CNS. Cultured astrocytes stimulated with IFN-gamma could, however, be induced to express HLA class II antigens of all subtypes, although great variability was observed between different donors. Our results indicate that although both Microglia and astrocytes are capable of expressing all HLA class II subtypes in vitro, subtype expression differs between normal and pathological states in situ. Such selective expression may be associated with functional properties

  386. Ulvestad E, Williams K, Matre R, Nyland H, Olivier A, Antel J (1994) Fc receptors for IgG on cultured human Microglia mediate cytotoxicity and phagocytosis of antibody-coated targets. J.Neuropathol.Exp.Neurol. 53:27-36
    Abstract: We have utilized surgically resected human central nervous system (CNS) tissue to determine the expression and functions of Fc receptors (Fc gamma R) on individual cell types found within the CNS. We observed all three classes of Fc gamma R on Microglial cells in situ and in vitro, but not on astrocytes or oligodendrocytes. Incubation of cultured Microglia with immune complexes (antibody-coated red blood cells) induced phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC), and oxidative bursts. We also found that Microglia have the capability to produce T cell stimulatory soluble mediators after Fc gamma R crosslinking. These functional responses were enhanced by pretreatment of the Microglia with interferon-gamma (IFN-gamma). Our results implicate Microglial effector responses triggered by interaction of Fc gamma R with opsonized antigens as potential mediators of tissue injury within the CNS. Such injury may be particularly applicable to multiple sclerosis, an inflammatory demyelinating disease characterized by intrathecal production of immunoglobulins and cytokines

  387. Williams K, Ulvestad E, Antel JP (1994) B7/BB-1 antigen expression on adult human Microglia studied in vitro and in situ. Eur.J.Immunol. 24:3031-3037
    Abstract: In this study, we have examined the expression and function of B7/BB-1 on individual glial cells, by utilizing surgically resected adult human central nervous system (CNS) tissues, tissues derived from fetal human CNS, and pathology material from cases of multiple sclerosis (MS). Immunofluorescence analysis using enriched adult human derived cultures of Microglia and oligodendrocytes, and mixed Microglia/astrocyte cultures, demonstrated that B7/BB-1 was expressed on Microglia. Adult human-derived oligodendrocytes and astrocytes, and human fetal astrocytes were B7/BB-1 negative under all culture conditions. Flow cytometry studies demonstrated a low basal level of B7/BB-1 expression on Microglia that was up-regulated following incubation with interferon-gamma (IFN-gamma). Co-culture of purified fresh allogeneic CD4+ T cells with Microglia for 24 h resulted in clustering of T cells around Microglia and Microglial B7/BB-1 expression. Preincubation of Microglia with an anti BB-1 monoclonal antibody (mAb) prior to Microglia: CD4+ T cell co-cultures resulted in partial inhibition of the ability of Microglia both to present recall antigen to autologous CD4+ T cells and to present antigen to allogeneic CD4+ T cells in primary mixed lymphocyte reaction (1 degree MLR). The CTLA-4 Ig fusion protein inhibited the ability of Microglia to present antigen in both antigen presentation assays to an even greater extent than did the anti BB-1 mAb. The BB-1 antibody also inhibited the ability of Microglia to stimulate previously activated T cells in a secondary 2 degrees MLR. In sections of multiple sclerosis brain, B7/BB-1 expression was observed on activated Microglia in select parenchymal lesions, and on perivascular cells and infiltrating monocytes. B7/BB-1 immunoreactivity was not found in normal appearing white matter from MS brain or from non-inflammatory brain specimens. Our results indicate that the B7/BB-1 molecule plays a functional role in the capacity of Microglia to serve as CNS antigen-presenting cells that can both initiate and perpetuate CD4+ T cell activation

  388. Williams KC, Ulvestad E, Hickey WF (1994) Immunology of multiple sclerosis. Clin.Neurosci. 2:229-245
    Abstract: multiple sclerosis (MS), a putative autoimmune disease of unknown etiology, is characterized by CNS perivascular inflammation, foci of demyelination, and elevated intrathecal production of oligoclonal IgG's. T and B cells, macrophages, and Microglia are all implicated in contributing to the initiation and perpetuation of the disease. In this brief review we discuss the possible role of T cells, B cells, macrophages, and Microglia in contributing to the initiation and perpetuation of inflammation and demyelination in MS. Data from the rodent model of MS, experimental allergic encephalomyelitis (EAE) supporting a immunological basis for the pathology of MS is noted. This paper discusses recent data suggesting an interaction of the above-mentioned cells, as well as serum and CSF proteins including complement and anti-myelin/oligodendrocyte antibodies, in the pathogenesis of MS and EAE. Additionally, this review describes each cell type including the clinical and experimental evidence for their contribution to the immunologically mediated pathology of MS. Following the description of the role of individual cells, there is consideration of: the possible interaction of cells with the blood brain barrier (BBB) under normal and pathologic inflammatory conditions; the traffic of cells into the CNS in inflammation; and the role of antigen presentation within the CNS in the initiation, and perpetuation, of the CNS immune response. Finally, the review suggests a role for T cells in the initiation, amplification, and possibly the termination of CNS inflammatory events with particular attention paid to the pattern of T cell activation and T cell cytokine production

  389. Youdim MB, Lavie L (1994) Selective MAO-A and B inhibitors, radical scavengers and nitric oxide synthase inhibitors in Parkinson's disease. Life Sci. 55:2077-2082
    Abstract: In the absence of identification of either an endogenously or an exogenously derived dopaminergic neurotoxin, the most valid hypothesis currently envisaged for etiopathology of Parkinson's disease (PD) is selective oxidative stress (OS) in substantia nigra (SN). Although OS is not proven, a significant body of evidence from studies on animal and Parkinsonian brain neurochemistry supports it. This hypothesis is based on excessive formation of reactive oxygen species (O2 and OH.) and demise of systems involved with scavenging or preventing the formation of such radicals from H2O2, generated as a consequence of dopamine oxidation (autoxidation and deamination). Since MAO (monoamine oxidase A and B are the major H2O2 generating enzymes in the SN much attention has been paid to their selective inhibitors as symptomatic and neuroprotective agents in PD. Attention should also be given to radical scavengers (e.g. iron chelators, lipid peroxidative inhibitors and Vitamin E derivatives) as therapeutic neuroprotective agents in PD. This is considered valid since a significant elevation of iron is known to occur selectively in SN zone compacta and within the remaining melanized dopamine neurons of Parkinsonian brains. Although all the mechanism of iron induced oxygen free radical formation is not fully known there is no doubt that it participates with H2O2 (Fenton chemistry) to generate cytotoxic hydroxyl radical (OH.) and induce tissue OS and neurodegeneration in 6-hydroxydopamine model of PD. The dramatic proliferation of reactive amoeboid macrophages and Microglia seen in SN of PD brains together with OS is highly compatible with an inflammatory process, similar to what has been observed in Alzheimer's disease and multiple sclerosis brains. This has led us to examine the ability of reactive macrophages to produce oxygen free radicals in response to nitric oxide (NO) production. The latter radical has been implicated in the excitotoxicity of glutaminergic neurons innervating the striatum and SN. Indeed we have now observed that in reactive macrophages NO acts as a signal transducer of O2 production which can synergize with dopamine oxidation

  390. Compston A (1993) Inflammation and the brain. Mol.Chem.Neuropathol. 19:47-64
    Abstract: Inflammation in the brain selectively damages the myelin sheath resulting in a variety of clinical syndromes of which the most common is multiple sclerosis. In these disorders, the areas of inflammation and demyelination can be identified in life by magnetic resonance imaging. Events occurring at the blood-brain barrier depend on T-cell activation, which increases immune surveillance within the central nervous system. T-cells activated against brain antigens persist to establish the conditions needed for inflammatory demyelination and this depends on local release of cytokines, culminating in removal of oligodendrocytes and their myelin lamellae by macrophages or Microglia. These interactions involve binding between receptors present on Microglia for the Fc portion of antibody and complement components to corresponding ligands on target cells. Taken together, the evidence from clinical and experimental studies provides a rationale for the issue of immunological treatments in patients with multiple sclerosis

  391. Compston A (1993) Limiting and repairing the damage in multiple sclerosis. Schweiz.Med.Wochenschr. 123:1145-1152
    Abstract: Inflammation of the brain depends upon migration of activated lymphocytes across the blood brain barrier bringing to the abluminal surface of cerebral blood vessels a variety of cellular and soluble immune mediators. Treatments which reduce the availability of circulating lymphocytes or limit their entry into the nervous system influence human and experimental inflammatory brain disease. The knowledge that inflammatory processes in the brain culminate in contact between Microglia and the oligodendrocyte-myelin unit, which is damaged by local release of tumour necrosis factor, provides additional opportunities for treatment. In these diseases, disability results both from the inflammatory process and the failure of precursor cells to enter the lesions, differentiate and remyelinate the naked axons. The probability for the future is that a combination of manoeuvres involving limitation of the inflammatory process, increased availability of glial progenitors and re-establishment of their developmental growth factor environment will be needed to repair demyelinated lesions

  392. Furer M, Hartloper V, Wilkins J, Nath A (1993) Lymphocyte emperipolesis in human glial cells. Cell Adhes.Commun. 1:223-237
    Abstract: Astrocytes have been observed to contain intact, viable lymphocytes within their cytoplasm (emperipolesis) in multiple sclerosis plaques and some brain tumors. This study characterizes the adhesive, emperipoletic and phagocytic properties of glial cells in culture. Human fetal and adult astrocytes engaged in adhesion and emperipolesis of lymphocytes. Emperipolesis, and not adhesion, was temperature- and cation-dependent. The CD8 and MHC Class I antigens played a role in emperipolesis. Lymphocytes most often remained viable within the cytoplasm of astrocytes but occasionally underwent lysis or caused disruption of the astrocyte intermediate filaments. The phenomenon of emperipolesis is distinct from phagocytosis, since Microglia showed prominent phagocytic properties but did not engage in emperipolesis. Conversely, astrocytes were efficient emperipolites and rarely demonstrated phagocytic properties

  393. Graeber MB (1993) Microglia, macrophages and the blood-brain barrier. Clin.Neuropathol. 12:296-297

  394. Hartung HP (1993) Immune-mediated demyelination. Ann.Neurol. 33:563-567
    Abstract: The Guillain-Barre syndrome (GBS) and multiple sclerosis (MS) are thought to result from aberrant immune responses to myelin antigens. Recent evidence to implicate the cytokine tumor necrosis factor-alpha (TNF-alpha) and the intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of these disorders is reviewed. In GBS, elevated serum concentrations of TNF-alpha are detectable in 20 to 50% of patients. TNF-alpha released from autoreactive T cells, macrophages, or Microglia may contribute to inflammatory demyelinative processes by upregulating the expression of recognition molecules on antigen-presenting cells; by cytotoxic damage to endothelium; by stimulating the secretion of inflammatory mediators; by directly injuring the myelin sheath; or by interfering with impulse propagation. Its pathogenic potential in GBS is underscored by findings in experimental autoimmune neuritis. Soluble ICAM-1, originating from T cells, macrophages, endothelium, or glial cells, circulates at increased concentrations in serum and cerebrospinal fluid of patients with active MS. ICAM-1 may be crucially involved in the migration of autoreactive T lymphocytes from blood to brain. Whether ICAM-1 can serve as a marker of acute inflammatory events in MS associated with clinical relapses warrants further investigation. TNF-alpha and ICAM-1 could be targets for antigen nonspecific treatment approaches to the inflammatory demyelinating diseases GBS and MS

  395. Li H, Newcombe J, Groome NP, Cuzner ML (1993) Characterization and distribution of phagocytic macrophages in multiple sclerosis plaques. Neuropathol.Appl.Neurobiol. 19:214-223
    Abstract: Populations of phagocytic cells in multiple sclerosis (MS) plaques were examined by quantitative immunocytochemical analysis of macrophage markers and myelin degradation products in serial cryostat sections from 10 cases of MS. Around lesions with ongoing demyelination expression of the Class II antigen HLA-DQ appeared to be a marker of Microglial activation. Alpha 1-antichymotrypsin+ monocytes and myelin-laden macrophages expressing the later differentiation markers Ber-MAC3 and RFD7 were predominantly perivascular in location. On the basis of the distribution of oil red O (ORO)+ phagocytes and myelin loss, plaques were divided into groups representing different stages in lesion development. In early lesions (group 1), there was no apparent myelin loss around ORO+ macrophages although these cells contained material stained with antibodies against myelin basic protein (MBP) epitopes and neoepitopes. However, patchy myelin loss was detectable around the phagocytic macrophages uniformly distributed throughout group 2 plaques. ORO+ macrophages containing MBP peptides were confined to the hypercellular border of group 4 lesions, in which the demyelinating process may be recurrent

  396. Martin FC, Anton PA, Gornbein JA, Shanahan F, Merrill JE (1993) Production of interleukin-1 by Microglia in response to substance P: role for a non-classical NK-1 receptor. J.Neuroimmunol. 42:53-60
    Abstract: Substance P (SP) is a central and peripheral neurotransmitter which has been found in multiple sclerosis plaques. SP stimulates peripheral immune cells and may play a role in some chronic inflammatory diseases. Human peripheral monocyte/macrophages have been shown to produce the inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) in response to SP. Therefore, in this study we examined rat brain Microglia for the presence of SP receptors and production of IL-1 and TNF alpha in response to SP. Microglia had 4900 +/- 950 (mean +/- SE) receptors per cell fitting a two-site model. Four percent of these were high-affinity receptors with a Kd of 8.2 x 10(-8) M +/- 3.6 x 10(-8) M (mean +/- SE), and 96% of them were low-affinity receptors with a Kd of 2.1 x 10(-6) M +/- 5.2 x 10(-7) M (mean +/- SE). Competitive studies with CP 96,345 and other SP analogs demonstrate these to be non-classical NK-1 receptors. SP alone did not stimulate IL-1 or TNF alpha production. However, SP in synergy with lipopolysaccharide (LPS) quadrupled IL-1 production compared to LPS alone, but did not affect TNF alpha production. These results have implications for certain inflammatory conditions in the central nervous system

  397. McGeer PL, Kawamata T, Walker DG, Akiyama H, Tooyama I, McGeer EG (1993) Microglia in degenerative neurological disease. Glia 7:84-92
    Abstract: Microglia express many leukocyte surface antigens which are upregulated in such chronic degenerative neurological diseases as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). These surface antigens include leukocyte common antigen, immunoglobulin Fc receptors, MHC class I and class II glycoproteins, beta 2-integrins, and the vitronectin receptor. Ligands for these receptors are also found. They include immunoglobulins, complement proteins of the classical pathway, T lymphocytes of the cytotoxic/suppressor and helper/inducer classes, and vitronectin. T lymphocytes marginate along capillary venules, with some penetrating into the tissue matrix. Immunoglobulins and complement proteins are synthesized locally in brain, although they may also come from the bloodstream if the blood-brain barrier is compromised. The membrane attack complex, which is formed from C5b-9, the terminal components of complement, has been identified in AD and multiple sclerosis brain tissue. In addition, proteins designed to defend against bystander lysis caused by the membrane attack complex, including protectin, C8 binding protein, clusterin, and vitronectin, are associated with damaged neuronal processes in AD. Autodestruction may play a prominent part in these 2 diseases

  398. Merrill JE, Ignarro LJ, Sherman MP, Melinek J, Lane TE (1993) Microglial cell cytotoxicity of oligodendrocytes is mediated through nitric oxide. J.Immunol. 151:2132-2141
    Abstract: Rat ameboid Microglia are able to lyse rat oligodendrocytes in vitro. The lysis is inhibited by transforming growth factor-beta, antagonists of nitric oxide (NO) production, as well as antibodies to TNF-alpha, intercellular adhesion molecule-1 (ICAM-1), and leukocyte functional Ag-1. Ameboid Microglial cells spontaneously produce detectable levels of the NO metabolite nitrite (NO2-). Stimuli such as PMA, LPS, and/or IFN-gamma induce micromolar concentrations of NO2- within 24 h. TNF-alpha increases IFN gamma but not LPS-induced NO2- production. Incubation with target oligodendrocytes also increases NO2- production in a contact-dependent manner. NO2- production is inhibited by NO synthase antagonists, transforming growth factor-beta, and anti TNF-alpha. Neither antileukocyte functional Ag-1 nor anti-ICAM-1 inhibit NO2- production by Microglia in the presence or absence of oligodendrocytes. Indeed, anti-ICAM-1 treatment increases NO2- production. There is a correlation between ameboid Microglial cell killing of oligodendrocytes and NO2- production suggesting NO may be a mechanism of death of the oligodendrocyte and possibly play a role in lesion formation in multiple sclerosis

  399. Myers KJ, Dougherty JP, Ron Y (1993) In vivo antigen presentation by both brain parenchymal cells and hematopoietically derived cells during the induction of experimental autoimmune encephalomyelitis. J.Immunol. 151:2252-2260
    Abstract: A fundamental issue in the etiology of autoimmune diseases of the central nervous system such as multiple sclerosis and its animal counterpart experimental autoimmune encephalomyelitis (EAE) concerns the identity of cells capable of presenting autoantigen to the T cells that mediate these diseases. The prevailing dogma is that only bone marrow-derived cells function as APC during EAE induction. We have addressed this issue by studying EAE induction in mouse bone marrow chimeras, and have found that although bone marrow-derived APC such as macrophages and brain Microglial cells are more efficient at presenting autoantigen, brain parenchymal cells such as astrocytes and endothelial cells are also capable of inducing disease. EAE was induced in these chimeras by the adoptive transfer of encephalitogenic T cell lines designed to be MHC-histocompatible with APC contained either within the hematopoietic system of the chimera or with APC resident to the brain of the chimera. The subsequent development of EAE in these chimeras then indicated which population of cells served as in vivo APC during EAE pathogenesis. Possible effects of alloreactivity between the host chimera and the adoptively transferred T cells were eliminated by using encephalitogenic T cell lines made tolerant to the haplotype(s) of the recipient chimera

  400. Nakajima K, Kohsaka S (1993) Functional roles of Microglia in the brain. Neurosci.Res. 17:187-203
    Abstract: It has been suggested that Microglia, a type of glial cells in the central nervous system, play various important roles in normal and pathologic brains. In this article, we discussed the association or roles of Microglia in injury and in brain diseases such as Alzheimer's disease, AIDS dementia complex, multiple sclerosis and ischemia. Furthermore, Microglia-derived cytotoxic products and other secretory factors were summarized. In addition to the pathological aspects, secretory factors that showed neurotrophic effects were described with special reference to their physiological significance in the neuronal growth, neuronal function and regeneration processes. Accumulated evidence suggests that Microglia are associated with not only brain pathology but also normal physiology in the brain

  401. Prayoonwiwat N, Rodriguez M (1993) The potential for oligodendrocyte proliferation during demyelinating disease. J.Neuropathol.Exp.Neurol. 52:55-63
    Abstract: The potential for oligodendrocytes to proliferate in response to central nervous system injury was examined. We used intracerebral infection of Theiler's murine encephalomyelitis virus, a model for multiple sclerosis, which results in chronic demyelinating disease of SJL/J mice. Proliferating cells in spinal cord sections of adult mice were identified using simultaneous immunohistochemistry and in situ autoradiography ([3H]-thymidine incorporation). Seven different cell-specific markers were used to characterize proliferating cells as oligodendrocytes (myelin basic protein, proteolipid protein, galactocerebroside, CNPase), astrocytes (glial fibrillary acidic protein), Microglia/macrophages (Griffonia simplicifolia isolectin B4) or T-lymphocytes (CD3). The average number of proliferating cells per area of spinal cord white matter was 11/mm2 in normal young adult mice compared to 61/mm2 in chronically infected mice. Most proliferating cells in normal spinal cord were not identified with these markers and were presumed to be progenitor glial cells. However, in spinal cord white matter of mice infected with Theiler's virus for approximately 4 months, 88% of proliferating cells were identified. Approximately one-third of all proliferating cells were in the oligodendrocyte lineage and expressed markers observed late in myelin differentiation. In demyelinated areas as compared to normal white matter, there was an 80- to 211-fold increase in the number of proliferating oligodendrocytes expressing myelin basic protein or proteolipid protein, respectively. The remainder of the proliferating cells in areas of demyelination were astrocytes, Microglial cells and T-cells. These experiments support the hypothesis that factors within a demyelinating lesion promote the proliferation and differentiation of cells within the oligodendroglial lineage

  402. Wekerle H (1993) T-cell autoimmunity in the central nervous system. Intervirology 35:95-100
    Abstract: Studies of myelin basic protein (MBP)-specific T lymphocytes have been extraordinarily informative for several distinct aspects of (neuro) immunology. They indicated for the first time that myelin directed central nervous system (CNS) inflammation is mediated by specific autoaggressive T cells. This provided a conceptual basis for understanding the pathogenesis of anti-myelin autoimmunity in general. We assume at present that human multiple sclerosis (MS) is also caused by myelin-specific autoaggressive T cells, and that these T cells create the inflammatory changes typical for the generation of a mature demyelinating plaque. Large scale demyelination seems, however, not to be caused by purely cellular mechanisms. Second, studies using MBP-specific T-cell lines have critically contributed to elucidating the immune status of the CNS. They showed that the CNS is not completely secluded from the circulating immune cells. Activated, though not resting lymphocytes can pass through the endothelial blood-brain barrier and migrate through the brain tissues. There, in the CNS, some glia components, Microglia and astrocytes can be induced by T-cell cytokines to act as efficient antigen-presenting cells. Thus, the CNS is subject to immune surveillance, though to a specialized, adapted variant thereof. Finally, studies using MBP-specific T cells established for the first time the presence of potentially autoaggressive T cells within the normal immune repertoire. This implies counterregulatory regulation required to keep the autoreactive T cells in a safe state of rest. Most recently, the analysis of the intrathymic anti-MBP T-cell repertoire may change our views on the generation of myelin-specific self tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

  403. Woodroofe MN, Cuzner ML (1993) Cytokine mRNA expression in inflammatory multiple sclerosis lesions: detection by non-radioactive in situ hybridization. Cytokine 5:583-588
    Abstract: The predominant pathological features in the central nervous system (CNS) in multiple sclerosis (MS) are perivascular inflammation and demyelination. The cells in the inflammatory cuff consist mainly of T lymphocytes and macrophages. Cytokines produced by inflammatory cells within the CNS have the potential to enhance local inflammation and promote phagocytosis of myelin by macrophages, resulting in demyelination. Resident brain cells, Microglia and astrocytes, also produce cytokines after stimulation in vitro. We have applied the technique of non-radioactive in situ hybridization to examine which cells in the CNS are producing cytokines in MS. Using digoxigenin-labelled oligonucleotide probes we have detected expression of the cytokines IL-1 alpha, IL-2, IL-4, IL-6, IL-10, IFN-gamma, TGF beta 1 & 2 and TNF-alpha in frozen sections of CNS tissue from MS cases. The intensity and distribution of the staining for mRNA is cytokine specific, IL-6, IFN-gamma and TNF-alpha predominating in the perivascular inflammatory cuffs, the others being more weakly expressed. Expression of all cytokine mRNAs is stronger in perivascular cells rather than in parenchymal cells, suggesting that circulating inflammatory cells which have crossed the blood brain barrier are the major source of cytokines in MS tissue

  404. Wu E, Brosnan CF, Raine CS (1993) SP-40,40 immunoreactivity in inflammatory CNS lesions displaying astrocyte/oligodendrocyte interactions. J.Neuropathol.Exp.Neurol. 52:129-134
    Abstract: Immunoreactivity for SP-40,40, a putative complement inhibitor, adhesion or protective molecule, has been examined in a variety of inflammatory CNS lesions that displayed associations between hypertrophic astrocytes and oligodendrocytes, a phenomenon previously suggested to be related to oligodendrocyte phagocytosis or protection. SP-40,40 staining was common and was predominantly limited to hypertrophic astrocytes within lesion areas and diminished beyond the lesion margin. However, there was no consistent relationship between SP-40,40 immunoreactivity and astrocytes associated with oligodendrocytes. Staining for terminal complement complex (C5b-9/SC5b-9) occurred in association with larger vessel walls and Microglial cells in the most active lesions, but was never seen in hypertrophic astrocytes. No association between SP-40,40 and complement deposition could be demonstrated. Staining for tumor necrosis factor-alpha showed a few scattered hypertrophic astrocytes to be positive. The findings confirm the presence of these astrocyte/oligodendrocyte interactions in active CNS lesions of varied etiology (multiple sclerosis, stroke and AIDS encephalitis). SP-40,40 immunoreactivity was common to hypertrophic astrocytes regardless of their associations with oligodendrocytes but showed no colocalization with terminal complement complex. Thus, these glial interactions do not apparently involve protection against complement-mediated lysis. Furthermore, the presence of SP-40,40 in astrocytes lacking association with oligodendrocytes did not support a role for this protein functioning as an adhesion molecule in astrocyte/oligodendrocyte associations

  405. Merrill JE (1992) Proinflammatory and antiinflammatory cytokines in multiple sclerosis and central nervous system acquired immunodeficiency syndrome. J.Immunother. 12:167-170
    Abstract: While certain cytokines such as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), IL-6, and transforming growth factor-beta (TGF-beta) may be involved in pro- and anti-inflammatory events in the central nervous system (CNS) of patients with multiple sclerosis (MS) and CNS acquired immunodeficiency syndrome (AIDS), there is not uniform consensus as to whether they are elevated or even detectable in all compartments of the body such as serum, cerebrospinal fluid (CSF), and tissue. Furthermore, if they are elevated in these diseases, there are no data as to whether they regulate the disease process itself. Myelin damage in MS is a punctate demyelination; in AIDS, it is a diffuse myelin pallor or dysmyelination. Oligodendrocytes are destroyed in MS but not CNS AIDS, suggesting a different mechanism for myelin loss in the two diseases. These different pathologies may provide clues about the role of macrophages, Microglia, and/or the toxic products they produce in putatively giving rise to myelin damage. The stimuli that trigger such a destructive response by macrophages or glial cells and/or the regulation of the toxic events in the two diseases we would predict to be different. In MS, an effector cell-mediated lesion production and oligodendrocyte cell destruction seem to occur. We hypothesize that the effector is the inflammatory blood macrophage and/or Microglial cell induced and promoted to its cytotoxic activity by a collaboration of neurotransmitters and cytokines. In CNS AIDS, virus-induced toxic products of glia and their diffusion through white and gray matter areas of the brain have been suggested. Such soluble mediators would then compromise metabolic processes of neurons and glia without widespread target cell loss

  406. Sherman MP, Griscavage JM, Ignarro LJ (1992) Nitric oxide-mediated neuronal injury in multiple sclerosis. Med.Hypotheses 39:143-146
    Abstract: Although several explanations have been proposed for destruction of myelin and oligodendrocytes in multiple sclerosis, there is no proven mechanism of injury. We postulate that the autoimmune response seen in multiple sclerosis results in a cytokine-mediated increase in nitric oxide production by macrophages/Microglia, smooth muscle cells and/or endothelium of the central nervous system. 3 mechanisms of cellular damage due to nitric oxide are proposed: 1. direct nitric oxide cytotoxicity; 2. injury due to peroxynitrite formation from superoxide anion and nitric oxide; and 3. nitric oxide-mediated elevations of cellular cGMP that enhance tumor necrosis factor-alpha toxicity. In support of these hypotheses, the anti-inflammatory effectors, dexamethasone and transforming growth factor-beta, ameliorate symptoms seen in clinical multiple sclerosis and experimental allergic encephalitis, respectively. These 2 immunomodulators also inhibit induction of cytokine-mediated nitric oxide production by macrophages. An experimental design and therapeutic interventions which will evaluate the role of nitric oxide in the pathophysiology of experimental allergic encephalitis are presented

  407. Thomas WE (1992) Brain macrophages: evaluation of Microglia and their functions. Brain Res.Brain Res.Rev. 17:61-74
    Abstract: There is now evidence approaching, if not having already surpassed, overwhelming in support of Microglial cells as macrophages. Consistent with this cellular identity, they appear to arise from monocytes in developing brain where amoeboid Microglia function in removing cell death-associated debris and in regulating gliogenesis. In normal adult tissue, ramified Microglial cells with down-regulated macrophage functional properties may serve a constitutive role in cleansing the extracellular fluid. Under all conditions of brain injury, Microglia appear to activate and convert into active macrophages. Activated and reactive Microglia participate in inflammation, removal of cellular debris and wound-healing, the latter through regulation of gliosis in scar formation and a potential contribution to neural regeneration and neovascularization. In the activated state, Microglia also express MHC's and, thus, may function in antigen presentation and lymphocyte activation for CNS immune responses. As uniquely adapted tissue resident macrophages within the CNS, Microglia serve a variety of functional roles over the lifespan of this tissue. These cells may therefore be involved in or contribute to some disease states; such has been indicated in multiple sclerosis and AIDS dementia complex

  408. Wiley CA, Johnson RT, Reingold SC (1992) Neurological consequences of immune dysfunction: lessons from HIV infection and multiple sclerosis. J.Neuroimmunol. 40:115-119
    Abstract: In a recent workshop held on Sanibel Island, Florida (18-21 January 1992), the two most common neuroimmunologic diseases of young adults, multiple sclerosis (MS) and HIV encephalopathy, were jointly discussed. The logic of assembling investigators from these two fields was based not on an assumed etiologic connection between MS and retroviral infection of the central nervous system (CNS), but rather in the hope of uncovering potential common pathogenic mechanisms, particularly as might relate to trafficking of mononuclear cells into the central nervous system, the distribution and function of macrophages and Microglia, the structure and function of the blood-brain barrier, and the role of cytokines released by activated cells. multiple sclerosis is a disease without a known etiologic agent or pathogenesis. While the causative agent for HIV leukoencephalopathy is known, the pathogenesis of the disease remains entirely enigmatic (a topic covered by R. Johnson). This meeting brought together two different groups of investigators to compare and contrast the diseases and to share perspectives, paradigms, and data with the aim of cross-fertilizing the disciplines and generating healthy hybrids

  409. Yamada T, Kawamata T, Walker DG, McGeer PL (1992) Vimentin immunoreactivity in normal and pathological human brain tissue. Acta Neuropathol.(Berl) 84:157-162
    Abstract: Vimentin immunoreactivity was examined in brain tissues from non-neurological and various human central nervous system disease cases. In all brain tissues examined, vimentin immunoreactivity was intensely positive in ependymal cells and subpial tissues, and weakly positive in some capillaries and some white matter astrocytes. In affected areas of Alzheimer's disease (AD), Pick's disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and cerebral infarction cases, numerous intensely vimentin-immunopositive astrocytes of both protoplasmic and fibrous morphology were demonstrated. A few such astrocytes were also observed in Parkinson's disease and progressive supranuclear palsy. ALS, MS and infarction brains also had numerous, strongly vimentin-positive, round and fat-laden Microglia/macrophages. In AD and ALS, a few reactive Microglia with irregularly enlarged shapes were vimentin positive. In AD, they were almost exclusively related to senile plaques

  410. Yoshioka M, Shapshak P, Sun NC, Nelson SJ, Svenningsson A, Tate LG, Pardo V, Resnick L (1992) Simultaneous detection of ferritin and HIV-1 in reactive Microglia. Acta Neuropathol.(Berl) 84:297-306
    Abstract: Using ferritin as a marker of reactive Microglia, we demonstrated a close association between proliferation of reactive Microglia and expression of human immunodeficiency virus type 1 (HIV-1) in brain tissue from autopsied cases of acquired immunodeficiency syndrome (AIDS). An increased number of ferritin-positive reactive Microglia was observed in formalin-fixed paraffin-embedded brain sections from all 13 AIDS cases examined. Similar findings were observed in brain tissue from other neurological diseases (subacute sclerosing panencephalitis, herpes simplex encephalitis and multiple sclerosis). Multinucleated giant cells were found in 7 of the AIDS cases which were also intensely labeled for ferritin. Dual-label immunohistochemistry using anti-ferritin and cell-specific markers showed that ferritin-positive cells were distinct from astrocytes, neurons and endothelia using anti-glial fibrillary acidic protein (anti-GFAP), anti-neurofilament protein and Ulex europaeus agglutinin 1, respectively. In 5 AIDS brains, only ferritin-positive cells were shown to contain HIV-1 gp41 antigen using dual-label immunohistochemistry. In addition, HIV-1 RNA was localized in ferritin-positive reactive Microglia but not in GFAP-positive astrocytes using immunohistochemistry combined with in situ hybridization. Ferritin-positive reactive Microglia and multinucleated giant cells were co-labeled with the Microglial marker, Ricinus communis agglutinin 1 (RCA-1). However, RCA-1 also extensively stained resting Microglia only a few of which were co-labeled for ferritin. The density of ferritin-positive cells was correlated with the presence of HIV-1 RNA-positive cells in AIDS brain. Thus, ferritin immunoreactivity can be used as an activation marker of Microglia in archival paraffin sections and reflects the extent of inflammation in HIV-1-infected brain

  411. Cacabelos R, Barquero M, Garcia P, Alvarez XA, Varela dS (1991) Cerebrospinal fluid interleukin-1 beta (IL-1 beta) in Alzheimer's disease and neurological disorders. Methods Find.Exp.Clin.Pharmacol. 13:455-458
    Abstract: Recent studies indicate that patients with Alzheimer's disease (AD) exhibit an immune dysfunction at the central and peripheral levels. We have studied the concentration of IL-1 beta in the cerebrospinal fluid (CSF) of patients with AD, multi-infarct dementia (MID), normal pressure hydrocephalus (NPH), and multiple sclerosis (MS). CSF IL-1 beta levels were significantly higher in AD (131 +/- 17.33 pg/ml) than in MID (79.71 +/- 24.37 pg/ml, p less than 0.01), NPH (84.75 +/- 23.17 pg/ml, p less than 0.01), and MS (79.4 +/- 10.23 pg/ml, p less than 0.01). In patients with neurological disorders CSF IL-1 beta levels showed a progressive increase with age (r = +0.49, p less than 0.015). The concentration of IL-1 beta in CSF of demented patients correlated with mental deterioration (r = -0.476). According to these results we postulate that high levels of central IL-1 beta in AD might reflect a reactive neuroimmune response to: (a) abnormal epitopes exposed by lesioned neurons, (b) reactive Microglia activated by exogenous and/or endogenous factors and (c) endogenous neurotrophic activation

  412. Chung IY, Norris JG, Benveniste EN (1991) Differential tumor necrosis factor alpha expression by astrocytes from experimental allergic encephalomyelitis-susceptible and -resistant rat strains. J.Exp.Med. 173:801-811
    Abstract: There is evidence that the cytokine tumor necrosis factor alpha (TNF-alpha) contributes to the pathogenesis of neurological autoimmune diseases such as multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE). TNF-alpha exerts damaging effects on oligodendrocytes, the myelin-producing cell of the central nervous system (CNS), and myelin itself. We have recently demonstrated TNF-alpha expression from astrocytes induced by lipopolysaccharide (LPS), interferon gamma (IFN-gamma), and interleukin 1 beta (IL-1 beta). Astrocytes secrete TNF-alpha in response to LPS alone, and can be primed by IFN-gamma to enhance LPS-induced TNF-alpha production. IFN-gamma and IL-1 beta, cytokines known to be present in the CNS during neurological disease states, do not induce TNF-alpha production alone, but act synergistically to stimulate astrocyte TNF-alpha expression. Inbred Lewis and Brown-Norway (BN) rats differ in genetic susceptibility to EAE, which is controlled in part by major histocompatibility complex (MHC) genes. We examined TNF-alpha gene expression by astrocytes derived from BN rats (resistant to EAE) and Lewis rats (highly susceptible). Astrocytes from BN rats express TNF-alpha mRNA and protein in response to LPS alone, yet IFN-gamma does not significantly enhance LPS-induced TNF-alpha expression, nor do they express appreciable TNF-alpha in response to the combined stimuli of IFN-gamma/IL-1 beta. In contrast, astrocytes from Lewis rats express low levels of TNF-alpha mRNA and protein in response to LPS, and are extremely responsive to the priming effect of IFN-gamma for subsequent TNF-alpha gene expression. Also, Lewis astrocytes produce TNF-alpha in response to IFN-gamma/IL-1 beta. The differential TNF-alpha production by astrocytes from BN and Lewis strains is not due to the suppressive effect of prostaglandins, because the addition of indomethacin does not alter the differential pattern of TNF-alpha expression. Furthermore, Lewis and BN astrocytes produce another cytokine, IL-6, in response to LPS, IFN-gamma, and IL-1 beta in a comparable fashion. Peritoneal macrophages and neonatal Microglia from Lewis and BN rats are responsive to both LPS and IFN-gamma priming signals for subsequent TNF-alpha production, suggesting that differential TNF-alpha expression by the astrocyte is cell type specific. Taken together, these results suggest that differential TNF-alpha gene expression in response to LPS and IFN-gamma is strain and cell specific, and reflects both transcriptional and post-transcriptional control mechanisms.(ABSTRACT TRUNCATED AT 400 WORDS)

  413. Esiri MM, Morris CS (1991) Immunocytochemical study of macrophages and Microglial cells and extracellular matrix components in human CNS disease. 2. Non-neoplastic diseases. J.Neurol.Sci. 101:59-72
    Abstract: For comparison with an earlier paper on gliomas (Morris and Esiri, J. Neurol. Sci., 101 (1991) 47-58), we have used an immunocytochemical approach to examine the reactions of astrocytes, macrophages and Microglia and alterations to the extracellular matrix components fibonectin and laminin in 15 cases of non-neoplastic CNS disease. We compared recently available markers for the detection of macrophages and Microglia (monoclonals Mac387, KP1 and the lectin RCA-1) and also used antisera to GFAP, fibronectin and laminin. RCA-1 was the superior marker for detecting macrophages and Microglia but it also reacted with endothelial cells in normal and reactive brain. The numbers of macrophages and Microglia were highly variable, depending on the type of lesion. Fibronectin and laminin were largely confined to the vasculature and leptomeninges. The relationship between the extracellular matrix and the astrocyte, macrophage and Microglial reactions is discussed

  414. Gray F, Chimelli L, Mohr M, Clavelou P, Scaravilli F, Poirier J (1991) Fulminating multiple sclerosis-like leukoencephalopathy revealing human immunodeficiency virus infection. Neurology 41:105-109
    Abstract: A 66-year-old French homosexual man and a 42-year-old Brazilian man with no known risk factors for HIV infection developed headaches, asthenia, and neurologic episodes of abrupt onset. CT showed multiple hypodense, nonenhancing lesions. Serology for HIV was positive. They died respectively 2 months and 1 month after onset of the illnesses. Autopsy in both cases showed multiple, well-demarcated, demyelinating foci in the white matter of the cerebral hemispheres, brainstem, and cerebellum with histologic features characteristic of recent plaques of multiple sclerosis. There were no multinucleated giant cells or Microglial nodules. Immunostaining for HIV was negative. Although a random coincidence of MS and HIV infection cannot be ruled out, the close temporal relationship between the 2 disorders suggests a possible etiologic association

  415. Hassan NF, Campbell DE, Rifat S, Douglas SD (1991) Isolation and characterization of human fetal brain-derived Microglia in in vitro culture. Neuroscience 41:149-158
    Abstract: Human brain Microglia may play a central role in immunopathogenesis of CNS diseases including HIV infection, multiple sclerosis and Alzheimer's disease. In order to investigate the possible relationship between Microglia and the mononuclear phagocyte system, human brain Microglia were isolated from 14-18-week-old fetal brains, and maintained in in vitro culture. Enriched fetal brain Microglia were stained for different monocyte/macrophage and glial cell markers. Fresh dissociated brain cells lacked macrophage surface markers. Isolated Microglial cells stained positive for complement receptor C3bi, Class II [human leukocyte antigen-DR (HLA-DR)] antigen and with the lectin Ricinus communis. Microglia also share several functional properties with monocyte/macrophages, which include generation of superoxide anion and histochemically demonstrable intracellular acid phosphatase and non-specific esterase. Primary human dissociated brain cultures were maintained in culture for at least 28 weeks. Although Microglia were not observed above the astrocyte cell layer after 5 weeks in culture, Microglia-like cells appear below the astrocyte layer after 12 weeks in culture. These cells stained positive for non-specific esterase and displayed oxidative burst activity upon activation with phorbol myristate acetate. Thus, we have successfully isolated an enriched population of Microglia from human fetal brain and have demonstrated that these cells possess markers and properties which are characteristics of mononuclear phagocytes

  416. Lassmann H, Zimprich F, Rossler K, Vass K (1991) Inflammation in the nervous system. Basic mechanisms and immunological concepts. Rev.Neurol.(Paris) 147:763-781
    Abstract: The basic questions in the pathogenesis of inflammation in the nervous system are how inflammatory cells reach the brain, where they recognize their antigen, how the nervous system interacts with local immune regulation in the lesion, and how inflammatory cells induce irreversible tissue damage. These questions have been addressed by studying the pathogenesis of experimental models of encephalomyelitis. The minimal requirement to start brain inflammation is the presence of activated circulating T-cells directed against a brain antigen and of antigen presenting cells in meninges and perivascular spaces of the nervous system. Such a constellation, however, only results in the disease after hypersensitization, i.e. in the presence of very high numbers of circulating autoreactive T-cells. Other local and systemic immunological factors may profoundly lower the threshold for the induction of brain inflammation. They include antigen recognition on cells in the brain parenchyma (Microglia, astroglia), local upregulation of MHC antigens and possibly adhesion molecules (by cytokines or as a consequence of brain injury) and the presence of additional humoral immune responses against brain antigens (autoantibodies). Focal production of cytokines by inflammatory cells as well as by resident cells of the brain plays an important role in determining the activity of the inflammatory process and in inducing effector cells and inflammatory mediators, responsible for tissue destruction. Whereas in pure T-cell mediated auto-immune encephalomyelitis these activated effector mechanisms have low selectivity and mainly induce a "bystander" damage of CNS tissue, additional presence of autoantibodies may focus the immune reaction to specific targets, thus inducing, in high sensitivity, very selective tissue destruction. The present experimental data suggest that different immunological pathways may finally lead to quite similar inflammatory demyelinating lesions. Thus, brain lesions in individual multiple sclerosis patients may develop on a quite diverse immunological background

  417. Merrill JE (1991) Effects of interleukin-1 and tumor necrosis factor-alpha on astrocytes, Microglia, oligodendrocytes, and glial precursors in vitro. Dev.Neurosci. 13:130-137
    Abstract: Microglia and astrocytes undergo proliferative and differentiative changes in vivo after trauma or diseases such as multiple sclerosis (MS). Oligodendrocytes are destroyed in lesions in MS. Interleukin-1 (IL1) and tumor necrosis factor-alpha (TNF alpha) are involved in inflammation of the central nervous system and are elevated in MS. We have investigated the changes in cell morphology and cell number induced by IL1 and TNF alpha in purified and mixed populations of primary rat brain Microglia, astrocytes, oligodendrocytes, and glial precursors. Depending on the target population, proliferation, differentiation, or inhibition of cultured cells was observed. The data also suggest that interactions among cell populations occur and support the hypothesis that IL1 and TNF alpha effects may be indirect, possibly through induction of other factors

  418. Merrill JE, Zimmerman RP (1991) Natural and induced cytotoxicity of oligodendrocytes by Microglia is inhibitable by TGF beta. Glia 4:327-331
    Abstract: Blood macrophages and brain macrophages (Microglia) have been implicated in demyelination and destruction of the oligodendrocyte in multiple sclerosis (MS), a disease affecting primarily white matter of the central nervous system (CNS). In this study, we demonstrate that at high effector to target cell ratios, normal rat Microglia exhibit a natural cytotoxicity against normal rat oligodendrocytes in vitro. The killing is not mediated by the release of soluble factors. The cytotoxic activity is upregulated by pretreatment of Microglia with interferon gamma (IFN gamma) or phorbol myristate acetate (PMA). Both the natural and induced cytotoxicities are inhibitable by transforming growth factor beta (TGF beta). The increase in numbers and apposition of primed or activated Microglia to oligodendrocytes in MS lesions may give rise to natural or induced killing from which oligodendrocytes may be protected by TGF beta

  419. Selmaj K, Raine CS, Cannella B, Brosnan CF (1991) Identification of lymphotoxin and tumor necrosis factor in multiple sclerosis lesions. J.Clin.Invest 87:949-954
    Abstract: multiple sclerosis (MS) brain tissue, spleen, and PBMC were studied using immunocytochemistry and FACS for immunoreactivity for lymphotoxin (LT) and TNF. Both cytokines were identified in acute and chronic active MS lesions but were absent from chronic silent lesions. LT was associated with CD3+ lymphocytes and Leu-M5+ Microglia cells at the lesion edge and to a lesser extent, in adjacent white matter. TNF was associated with astrocytes in all areas of the lesion, and with foamy macrophages in the center of the active lesion. In acute lesions, immunoreactivity for TNF in endothelial cells was noted at the lesion edge. No LT or TNF reactivity was detected in Alzheimer's or Parkinson's disease brain tissues but was present at lower levels in central nervous system (CNS) tissue from other inflammatory conditions, except for adrenoleucodystrophy which displayed high levels of LT in Microglia. No increase in LT and TNF reactivity was detected in spleen and PBMC of MS patients suggesting specific reactivity within the CNS. These results indicate that LT and TNF may be involved in the immunopathogenesis of MS, and can be detected in both inflammatory cells and cells endogenous to the CNS

  420. Woodroofe MN, Sarna GS, Wadhwa M, Hayes GM, Loughlin AJ, Tinker A, Cuzner ML (1991) Detection of interleukin-1 and interleukin-6 in adult rat brain, following mechanical injury, by in vivo microdialysis: evidence of a role for Microglia in cytokine production. J.Neuroimmunol. 33:227-236
    Abstract: In vivo levels of interleukin-1 (IL-1) and IL-6, present in the interstitial spaces of brain, have been repeatedly monitored up to 7 days after insertion of a microdialysis probe, designed to induce mechanical trauma to the brain. IL-1 is barely detectable immediately after implantation but over a 24-48 h period a 15-fold increase is seen. In contrast IL-6 levels at day 0 are high, increasing slightly (10%) by day 1 but decreasing to 40% by day 2. The temporal pattern of IL-6 recovery in the cerebrospinal fluid was similar to that in the dialysate but the levels were significantly lower and may reflect diffusion from the site of the probe lesion. Cellular sources of these cytokines include macrophages and neutrophils, which have infiltrated the lesion and Microglia resident in the brain, which can be identified at the lesion site within 24 h of probe implantation. The astrocytic response to injury, evidenced by increased glial fibrillary acidic protein staining occurs much later, by day 7, and is unlikely to be responsible for IL-1 and IL-6 production found at 24-48 h. Since upon isolation and stimulation of Microglia in vitro with lipopolysaccharide IL-1 and IL-6 can be measured in the supernatant, it would appear that they have the capacity to produce cytokines in vivo. Localised synthesis of cytokines at sites of brain injury by Microglia would further stimulate Microglia in an autocrine manner and also propagate the astrocytic reaction

  421. Adams CW, Poston RN (1990) Macrophage histology in paraffin-embedded multiple sclerosis plaques is demonstrated by the monoclonal pan-macrophage marker HAM-56: correlation with chronicity of the lesion. Acta Neuropathol.(Berl) 80:208-211
    Abstract: Using the monoclonal antibody HAM-56 with the avidin-biotin method on recent or archival paraffin-embedded tissue from multiple sclerosis brains, we have been able to distinguish between acute, chronic active and inactive lesions. HAM-56 stains all macrophages, monocytes and at least some Microglia; it is the only pan-macrophage marker to our knowledge that can be satisfactorily used on conventional paraffin sections. A much narrower range of mainly perivascular macrophages in acute plaques of multiple sclerosis is stained with MAC-387, anti-muramidase and anti-alpha1-anti-trypsin. The acute plaques show HAM-56-stained macrophages throughout the lesion, and these macrophages exhibit profiles of phospholipid-rich myelinic bodies, which are also usually stainable with Luxol fast blue. Active ongoing lesions show a rim of macrophages at the edge of the lesion. These macrophages show profiles of large vacuoles, thought to represent the sudanophilic esterified cholesterol formed during demyelination. Inactive cases show none of these features; the few perivascular macrophages present often contain the end product of lipid peroxidation, ceroidlipofuscin

  422. Boyle EA, McGeer PL (1990) Cellular immune response in multiple sclerosis plaques. Am.J.Pathol. 137:575-584
    Abstract: multiple sclerosis plaques were immunohistochemically stained to exhibit cells expressing immune-system antigens. Human leukocyte antigen (HLA)-DR-positive cells formed dense rings around all plaque regions. The majority were reactive Microglia/macrophages. Counterstaining with oil red O revealed heavy myelin debris within these cells. They were distinct from astrocytes, which were identified with an antibody to glial fibrillary acidic protein (GFAP) and which did not contain oil red O myelin debris. Numerous leukocytes and Microglia were stained with antibody to leukocyte common antigen (LCA). Lymphocytes in cuffs around vessels, along the margins of capillary walls, and, sparingly, in the tissue matrix of affected areas, were stained with antibodies to CD4 (T-helper/inducer) and CD8 (T-cytotoxic/suppressor). In experimental allergic encephalomyelitis (EAE) induced in Lewis rats, a similar proliferation of Ia-positive (OX6, OX17) cells displaying reactive Microglia/macrophage morphology was observed. These Ia-positive cells also were easily distinguished from GFAP-positive astrocytes. The results suggest that macrophages/reactive Microglia, and not astrocytes, express class II MHC antigens in multiple sclerosis and EAE plaques

  423. Ciardi A, Sinclair E, Scaravilli F, Harcourt-Webster NJ, Lucas S (1990) The involvement of the cerebral cortex in human immunodeficiency virus encephalopathy: a morphological and immunohistochemical study. Acta Neuropathol.(Berl) 81:51-59
    Abstract: The encephalopathy resulting from direct infection of the brain by human immunodeficiency virus (HIV), which correlates clinically with the AIDS dementia complex, has been reported as being localized to the white matter where it induces myelin loss, gliosis and perivascular infiltration by mononuclear macrophages and multinucleated giant cells. Damage to the cortical grey matter in HIV encephalopathy was investigated in nine randomly selected HIV-positive cases with or without clinical or morphological evidence of encephalopathy and in five age-matched controls, using routine histology and immunohistochemical methods [glial fibrillary acidic protein (GFAP), Microglia and HIV antibodies]. Increased numbers of GFAP-expressing astrocytes and Ricinus communis agglutinin 1-120-expressing Microglial cells were found in all the HIV-positive cases (including asymptomatic) and their severity could be correlated with the severity of the encephalopathy in the white matter; the increase in number of cells expressing GFAP was diffuse and the intensity of the staining higher than that of Microglial cells. The subpial region was the most severely involved. It is suggested that involvement of the cortical grey matter is more common in HIV infection than previously suspected and that clinical evidence of a dementing process in AIDS is not necessarily due only to white matter lesions

  424. Kesselring J (1990) [The pathogenesis of multiple sclerosis]. Schweiz.Med.Wochenschr. 120:1083-1090
    Abstract: Genetic factors determine susceptibility to multiple sclerosis (MS), and environmental factors influence the clinical manifestations of the disease. In recently formed plaques the blood-brain barrier is open for about 6 weeks. Water content is increased in white matter appearing normal macroscopically and in cortex of MS patients. Activated T-lymphocytes accumulate and stimulate Microglia and macrophages, which initiate the demyelinating process. In chronic plaques astroglial cells form a scar tissue around axons devoid of myelin. Modern imaging techniques make it possible to differentiate inflammation and demyelination in vivo

  425. Kettenmann H, Hoppe D, Gottmann K, Banati R, Kreutzberg G (1990) Cultured Microglial cells have a distinct pattern of membrane channels different from peritoneal macrophages. J.Neurosci.Res. 26:278-287
    Abstract: Microglia are the source of the resident macrophages of the brain and thus belong to one of the most reactive cell types in cerebral tissue. They are attributed to have an important role in a number of pathological conditions, such as multiple sclerosis, viral infections like AIDS, and in lethal or sublethal injuries of neurons where the blood-brain barrier is left intact (Streit et al., 1988; McGeer et al., 1988; Gendelman et al., 1989). Microglia share a number of macrophage characteristics but so far lack a distinguishing positive marker. In this study it is shown that Microglia are distinguished from other macrophages by a unique pattern of ion channels. We compared membrane currents of Microglial cells with those from peritoneal macrophages cultured under identical conditions. Although in macrophages a delayed outward K+ current was previously described (Randriamampita and Trautmann, 1987), Microglial cells lacked any specific outward current. Instead, these cells were characterized by large inwardly rectifying currents, activated by hyperpolarizing voltage steps. The reversal potential in different K+ gradients and the sensitivity of the current to to Ba2+, TEA, and 4-AP indicates that this current is K+ selective. In single-channel recordings, a 30 pS K+ selective channel similar to the classical inward rectifier K+ channel was observed. Thus, the expression of membrane channels served not only to distinguish Microglia from other cells inside and outside the brain, e.g., blood macrophages, but also suggests a unique functional state of this cell population

  426. Lawrence JM, Morris RJ, Wilson DJ, Raisman G (1990) Mechanisms of allograft rejection in the rat brain. Neuroscience 37:431-462
    Abstract: Embryonic rat hippocampal primordia from class I and class II major histoincompatible donors were transplanted into the hippocampus of adult rat hosts. The allografts were rejected by a specific host immune response, which was identified by reference to events at a histocompatible hippocampal primordial graft (syngeneic to the host) of similar embryonic age placed simultaneously in the contralateral hippocampus of the same hosts. The present combined light immunohistochemical and electron microscopic study was undertaken to elucidate the mechanism of induction of the immune response by a graft of a tissue which does not constitutively express major histocompatibility antigens, to identify which cells are involved, and how they enter the brain and attack the graft, and to look for possible sources of variability in the outcome of such an attack. Our main findings are (1) that host and graft Microglia play a prominent role from the earliest stages, and throughout the evolution of the histological changes, (2) that the later entry of host dendritic cells, lymphocytes, and lymphoblasts (with associated mitoses) into the perivascular cuffs of the graft vasculature ensures that the local immune response becomes self-propagating, (3) that the allografted neurons are killed by host cytotoxic lymphocytes only after a previous encirclement by host macrophage-derived Microglial cells, and (4) that the observed variability (especially within different regions of a single allograft) is associated not with failure of immune induction, but with local failure of the graft tissues to express allotypic major histocompatibility antigens. Our observations confirm that once the host immune system has been primed, local factors leading to the induction of transplant major histocompatibility complex antigens make histoincompatible intracerebral transplants of embryonic into adult brain tissue vulnerable to vigorous and effective immune attack. The histological picture of the immune response observed in our intracerebral allografts resembles that described in intraventricular allografts of embryonic brain, in allografts of other organs and tissues such as skin, kidney, and heart, and also that seen in the response to brain autoantigens in multiple sclerosis and experimental allergic encephalomyelitis. However, the involvement of a special cell type, the perivascular Microglial cell, in the early stages of immune induction in brain raises the possibility of designing future therapeutic approaches which might selectively block this step in conditions such as multiple sclerosis

  427. Lee SC, Moore GR, Golenwsky G, Raine CS (1990) multiple sclerosis: a role for astroglia in active demyelination suggested by class II MHC expression and ultrastructural study. J.Neuropathol.Exp.Neurol. 49:122-136
    Abstract: Central nervous system (CNS) tissue was studied by immunocytochemistry and electron microscopy from three cases of multiple sclerosis (MS) in which evidence of ongoing myelin breakdown could be documented. The study focussed upon the role of glial cells in the pathogenesis of demyelination. In acute MS, demyelination involved the vesicular dissolution of myelin from intact axons and a paucity of fibrillary astrogliosis. Foamy macrophages, many of them probably derived from transformed and recently proliferated Microglia, contained recognizable myelin debris and lipid droplets and were abundant throughout the lesions. These cells formed the major phagocytic population and stained positively for class II major histocompatibility complex antigens (HLA-DR; Ia). In acute MS lesions, rounded astrocytes were encountered which possessed membrane-bound compartments enclosing phagocytosed fragments of myelin basic protein-positive debris. Despite the superficial resemblance of these cells to foamy macrophages, the presence of intermediate filaments, glycogen granules and diffuse glial fibrillary acidic protein positivity supported an astroglial identity. Astrocyte processes were involved in myelin removal and invested recently demyelinated axons. Hypertrophic fibrous astrocytes were common in chronic active lesions, were capable of myelin degradation and on occasion, contained myelin debris attached to clathrin-coated pits. These astrocytes were sometimes Ia+. Oligodendrocytes were depleted from the center of active lesions but were numerous at the lesion margin, suggesting survival and proliferation. They stained positively for myelin-associated glycoprotein, a marker for immature oligodendrocytes. However, they were invariably Ia-. The findings confirm and further support a role for the astrocyte as both an antigen presenting cell and a phagocyte in the CNS during MS

  428. Norton WT, Brosnan CF, Cammer W, Goldmuntz EA (1990) Mechanisms and suppression of inflammatory demyelination. Acta Neurobiol.Exp.(Wars.) 50:225-235
    Abstract: Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system commonly used as a model for multiple sclerosis. In both of these diseases demyelination occurs association with perivascular infiltrates of T-cells and macrophages. The similarities in immunopathology suggest that these two diseases share common mechanisms of tissue destruction. We have proposed a general mechanism to explain the clinical and histopathological features of EAE. T-cells sensitized to the inducing antigen, myelin basic protein (MBP), react with antigen-presenting cells (possibly endothelial cells, Microglia or astrocytes) in the central nervous system. As a consequence of this reaction, T-cells release lymphokines which activate macrophages, stimulate an augmenting inflammatory response, and, through the action of vasoactive amines, induce vasospasm and breakdown of the blood-brain barrier. The activated macrophages secrete inflammatory mediators, including plasminogen activator and other proteinases, which, in concert with serum plasminogen and complement, initiate myelin destruction. The macrophage products also serve to enhance the inflammatory response and vascular permeability. In support of this hypothesis we find that: (1) macrophage-secreted proteinases can degrade MBP in lyophilized myelin and that proteolysis is amplified in the presence of plasminogen; (2) proteolysis of proteins in fresh myelin by macrophage proteinases and plasminogen or by plasmin is potentiated by complement; (3) removal of macrophages from the circulation suppresses EAE; (4) proteinase inhibitors suppress EAE; and (5) prazosin, an alpha 1-adrenergic receptor antagonist, suppresses the clinical signs of EAE and the increased vascular permeability but only delays the inflammatory response. We believe that prazosin acts on the vascular alpha 1-adrenergic receptor to inhibit vasospasm and prevent opening of the blood-brain barrier. Thus it is possible to suppress both clinical signs and pathology by interceding at several steps of the cell-mediated immune reaction

  429. Clanet M, Blancher A, Calvas P, Rascol O (1989) Interferons and multiple sclerosis. Biomed.Pharmacother. 43:355-360
    Abstract: Interferons (IFNs) are a family of proteins with antiviral, antitumoral and immunomodulating properties. multiple sclerosis (MS) is a CNS disease in which the immune reaction (IR) is the cause of the inflammatory demyelinating lesions. IFNs have been demonstrated in active lesions. The location of IFN gamma on astrocytes suggests an enhancing activity on IR by inducing Ia antigen expression on these cells. In contrast, IFN alpha/beta located on Microglial cells and astrocytes might limit the growing lesion. MS patients frequently present a defective response of NK cell activity and an abnormally low production of IFNs reflecting immune dysregulation. The therapeutic trials available to date are discussed: IFN gamma possesses a severe deleterious effect but IFN alpha/beta are still under consideration due to a possible beneficial activity

  430. Lee SC, Raine CS (1989) multiple sclerosis: oligodendrocytes in active lesions do not express class II major histocompatibility complex molecules. J.Neuroimmunol. 25:261-266
    Abstract: The expression of major histocompatibility complex (MHC) molecules by oligodendrocytes has been proposed as evidence for their involvement in the multiple sclerosis (MS) lesion although the literature on the subject is controversial and based largely upon observations in vitro. With a modified immunocytochemical procedure on 1 micron epoxy sections, the present study has examined the expression of class II MHC molecules (Ia) on cells within actively demyelinating lesions in a central nervous system biopsy from a case of acute MS. White Ia was readily demonstrable on Microglial cells and astrocytes, it was never detected on adjacent surviving oligodendrocytes. Unexpectedly, in parallel sections, the oligodendrocytes stained positively for myelin-associated glycoprotein, a marker for immature oligodendrocytes. The unequivocal lack of Ia expression by oligodendrocytes in MS makes it unlikely that they serve as immunomodulators in lesion pathogenesis

  431. Pfister HW, Einhaupl KM, Wick M, Fateh-Moghadam A, Huber M, Schielke E, Goebel FD, Matuschke A, Heinrich B, Bogner JR, . (1989) Myelin basic protein in the cerebrospinal fluid of patients infected with HIV. J.Neurol. 236:288-291
    Abstract: The major pathological abnormalities of HIV encephalopathy are infiltrates of macrophages, multinucleated giant cells, Microglial nodules and demyelination. Elevated myelin basic protein (MBP) levels in the cerebrospinal fluid (CSF) provide a marker for central nervous system demyelination. The purpose of this study was to investigate the possible role of CSF MBP as a useful and early marker for HIV encephalopathy. The CSF of 40 consecutive patients with HIV infection of various clinical stages was investigated, including 13 patients with clinical signs of HIV encephalopathy. CSF MBP was elevated in 2 patients (5.0 and 5.3 ng/ml), both of whom had moderate to severe HIV encephalopathy. The course of the disease was rapid in both patients. In the remaining 38 patients, CSF MBP levels were marginally elevated (n = 12) or normal (n = 26). Our results suggest that CSF MBP is not a sensitive marker for the diagnosis and evaluation of HIV encephalopathy, but may be an indicator of prognosis for the course of the disease. There were only few findings of elevated CSF MBP levels in patients with HIV encephalopathy in the current study, and this may be because the disorder progressed slowly in most patients. It is possible that CSF MBP levels in HIV encephalopathy may only be elevated with acute clinical deterioration but are normal in slowly progressive forms of demyelination, as seen in multiple sclerosis

  432. Cuzner ML, Hayes GM, Newcombe J, Woodroofe MN (1988) The nature of inflammatory components during demyelination in multiple sclerosis. J.Neuroimmunol. 20:203-209
    Abstract: Immune reactivity in the central nervous system (CNS) in multiple sclerosis (MS) can be fuelled by activated T lymphocytes sequestered in the brain and those entering systemically. The perivascular cuff of the inflammatory lesion consists predominantly of T cells and macrophages, while the hypercellular interface between normal and degenerating myelin is comprised mainly of macrophages and activated Microglia. MHC class II+ cells are abundant in the hypercellular zone and expression of both the polymorphic and invariant chains of the molecule are expressed beyond the plaque edge in the white matter where the staining is restricted largely to Microglia. Under carefully controlled staining conditions expression of MHC class II can be demonstrated on Microglia in control white matter. Thus the immunological privilege of the CNS does not appear to preclude constitutive expression of MHC antigens or prevent the traffic of activated lymphocytes into the brain parenchyma. However, the antigens priming the immune reaction in the CNS in MS and the role of antibodies in the demyelinating process remain a matter for speculation and the exact mechanisms of demyelination are as yet unresolved

  433. Hayes GM, Woodroofe MN, Cuzner ML (1988) Microglia express MHC class II in normal and demyelinating human white matter. Ann.N.Y.Acad.Sci. 540:501-503

  434. Hickey WF, Kimura H (1988) Perivascular Microglial cells of the CNS are bone marrow-derived and present antigen in vivo. Science 239:290-292
    Abstract: A crucial question in the study of immunological reactions in the central nervous system (CNS) concerns the identity of the parenchymal cells that function as the antigen-presenting cells in that organ. Rat bone marrow chimeras and encephalitogenic, major histocompatability--restricted T-helper lymphocytes were used to show that a subset of endogenous CNS cells, commonly termed "perivascular Microglial cells," is bone marrow-derived. In addition, these perivascular cells are fully competent to present antigen to lymphocytes in an appropriately restricted manner. These findings are important for bone marrow transplantation and for neuroimmunological diseases such as multiple sclerosis

  435. McGeer PL, Itagaki S, McGeer EG (1988) Expression of the histocompatibility glycoprotein HLA-DR in neurological disease. Acta Neuropathol.(Berl) 76:550-557
    Abstract: Reactive Microglia or macrophages expressing the histocompatibility glycoprotein HLA-DR were detected in many neurological diseases including Alzheimer's, Parkinson's, Pick's and Huntington's diseases, parkinsonism-dementia of Guam, amyotrophic lateral sclerosis, Shy-Drager syndrome, multiple sclerosis and AIDS encephalopathy. Reactive astrocytes, also present in these conditions, were established as a population distinct from the HLA-DR positive Microglia by double immunostaining for glial fibrillary acidic protein and HLA-DR. A distinctive pattern of HLA-DR positive cells was seen in each disease entity. Areas known to contain pathology always stained positively, and, in several cases, reactive Microglia appeared in areas that would otherwise not have been suspected of being involved in the pathological process. HLA-DR staining, which outlines the surface membranes of positive cells, was so strong that lesioned areas could frequently be identified in sections with the naked eye. In adjacent sections stained with H&E or sections destained of HLA-DR and then restained with H&E, gliosis was often hard to identify except on close microscopic inspection. The results suggest that HLA-DR staining may be a valuable addition to standard neuropathological methods and might be useful in investigating diseases where pathology has not yet been identified

  436. Miles JM, Chou SM (1988) A new immunoperoxidase marker for Microglia in paraffin section. J.Neuropathol.Exp.Neurol. 47:579-587
    Abstract: We tested antisera against monocytic and lymphocytic lineages on 27 formalin-fixed, paraffin-embedded brains, obtained at autopsy, using the avidin-biotin-complex immunoperoxidase method. Patients ranged from one day to 69 years with 12 cases under the age of two. LN-1-positive Microglia were present in 22 brains. LN-1 did not stain any other glial or neuronal cells. Five negative brains included two irradiated gliomas, two cases of multiple sclerosis and one normal case. Immunostaining was confined to cells with bipolar processes and rod-shaped nuclei recapitulating the characteristic features of Microglia in silver-impregnated sections. LN-1-positive Microglia were most prominent in the grey matter and in the grey-white junction with fewer positive cells seen in the white matter. Double immunostaining with LN-1 and glial fibrillary acidic protein (GFAP) clearly distinguished LN-1-positive Microglia and GFAP-positive astrocytes. The expression of LN-1, a B-lymphocyte antigen, by Microglia contradicts the macrophage derivation theory and supports data indicating a functional role of Microglia in immune processes. LN-1, while not specific for Microglia, should be considered a useful marker, more reliable than silver impregnation, for detecting Microglia in paraffin section

  437. Hayes GM, Woodroofe MN, Cuzner ML (1987) Microglia are the major cell type expressing MHC class II in human white matter. J.Neurol.Sci. 80:25-37
    Abstract: In normal human white matter the predominant cell type expressing MHC Class II is the Microglia. This population of cells reacts with the pan macrophage marker, EBM/11, and constitutes about 13% of the glial cell population. The intensity of staining was enhanced and the absolute number of Class II+ Microglia increased in normal appearing white matter from multiple sclerosis (MS) brain. As T cell activation in MS may occur in the brain the upregulation of Microglia bearing MHC Class II may reflect their function as antigen presenting cells in the development of inflammatory lesions

  438. Frei K, Bodmer S, Schwerdel C, Fontana A (1986) Astrocyte-derived interleukin 3 as a growth factor for Microglia cells and peritoneal macrophages. J.Immunol. 137:3521-3527
    Abstract: Astrocytes have been shown to release an interleukin 3 (IL 3)-like factor that induces the expression of 20-alpha-hydroxysteroid-dehydrogenase (20-alpha SDH) in nu/nu spleen cells, and the proliferation of the IL 3-dependent cell line 32DCL. We have investigated whether astrocyte-derived IL 3 supports growth of macrophages and their representatives in the brain, the Microglia cells. Evidence for intercellular communication between murine astrocytes and macrophages became already detectable in co-culture experiments: astrocytes activated with endotoxin resulted in an increased growth of peritoneal macrophages on the astrocyte monolayer. Biochemical analysis of supernatants of activated astrocytes revealed that the IL 3-like factor that stimulated 32DCL cells and the expression of 20 alpha SDH also served as a growth factor for cultured peritoneal macrophages. The same results were obtained by using Microglia cells isolated from primary brain cell cultures of newborn mice, which are characterized by their positive reaction for macrophage markers such as Mac-1 and nonspecific esterase. If secreted by reactive astrocytes in vivo, the IL 3-like factor may contribute to the accumulation of macrophages and Microglia cells detected in brain lesions of patients with multiple sclerosis

  439. Woodroofe MN, Bellamy AS, Feldmann M, Davison AN, Cuzner ML (1986) Immunocytochemical characterisation of the immune reaction in the central nervous system in multiple sclerosis. Possible role for Microglia in lesion growth. J.Neurol.Sci. 74:135-152
    Abstract: As there is evidence that in multiple sclerosis T-cell activation occurs in the central nervous system rather than outside, the inflammatory lesion may be extended through antigen presentation by cells at the edge of the plaque. In this study we present an immunocytochemical report on CNS tissue from an active case of MS, with an analysis of the distribution of CD4 and CD8 binding T cells and the expression of class I and II MHC determinants in plaques and white matter. Perivascular cuffs of early lesions, as judged by hypercellularity and minimal demyelination, contained activated T (Tac+) cells, which reacted with an anti-IL-2 monoclonal antibody. Thus sufficient T-cell growth factor would appear to be present to fuel the immune reaction in a growing lesion. The preponderance of T cells of the cytotoxic/suppressor (CD8) phenotype in the CNS parenchyma was found in conjunction with widespread staining of class I MHC antigen, a prerequisite for activity of cytotoxic T cells. Potential antigen presenting cells were demonstrated in MS plaques with a monoclonal antibody against the cytoplasmic, invariant chain of class II MHC. Macrophages and astrocytes, contributed to the staining in the hypercellular plaque border while the distribution of class II+ Microglia in white matter suggest they may also be of importance in local antigen presentation

  440. Esiri MM, Booss J (1984) Comparison of methods to identify Microglial cells and macrophages in the human central nervous system. J.Clin.Pathol. 37:150-156
    Abstract: The macrophage markers non-specific esterase, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and lysozyme were compared with conventional Microglial and macrophage stains in the human central nervous system. In a series of specimens from cases of head trauma, conventionally fixed and embedded, the modified Weil-Davenport stain was unequivocally best for demonstrating reactive Microglia. alpha 1-antichymotrypsin, however, was the most effective for showing macrophages in a series of specimens from patients with other conditions, which included inflammatory, neoplastic, and non-inflammatory diseases. The non-specific esterase reaction was unsatisfactory in tissues fixed in neutral formalin but was successful in fresh frozen tissue. In a series of specimens from cases of multiple sclerosis, non-specific esterase showed demyelination clearly and stained neuronal cytoplasm. It also stained macrophages but was less satisfactory for lipid-bearing phagocytes in multiple sclerosis than oil red 0

  441. Nyland H, Mork S, Matre R (1982) In-situ characterization of mononuclear cell infiltrates in lesions of multiple sclerosis. Neuropathol.Appl.Neurobiol. 8:403-411
    Abstract: The mononuclear cell infiltrates in autopsy material from brains and spinal cords of six patients with multiple sclerosis (MS) were characterized in situ. Receptors for sheep erythrocytes and anti-T lymphocyte serum were used to identify T lymphocytes. Receptors for the activated third components of complement and for the Fc-portion of IgG (Fc gamma receptors) were used as markers for macrophages and lymphocytes. In acute and recent MS lesions, perivascular infiltrates of mononuclear cells were commonly found. Most cells were T lymphocytes. Some B lymphocytes were also demonstrated. The demyelinating lesions contained large numbers of lipid macrophages expressing Fc gamma receptors. The lipid macrophages are probably derived from Microglial cells. The chronic, demyelinated lesions contain a few mononuclear cells, mainly B lymphocytes and plasma cells

  442. Nyland H, Matre R, Mork S (1980) Fc receptors of Microglial lipophages in multiple sclerosis. N.Engl.J.Med. 302:120-121

  443. Prineas JW, Wright RG (1978) Macrophages, lymphocytes, and plasma cells in the perivascular compartment in chronic multiple sclerosis. Lab Invest 38:409-421
    Abstract: Perivascular cells in CNS tissue from six multiple sclerosis (MS) patients and a patient with motor neuron disease were examined by light and electron microscopy. Lymph node tissue from one MS patient was also examined. CNS perivascular macrophages in both MA and motor neuron disease were found to closely resemble free macrophages elsewhere in the body except that they often contained unusually large primary lysosomes. Cytoplasmic inclusions consisting of membrane-bound stacks of curved linear profiles, presumed to be a product of myelin degradation, were constantly observed in Microglia in MS plaques but were rarely observed in perivascular macrophages in the same area. Unidentified cylindrical bodies were observed within cysternae of rough endoplasmic reticulum in some lymph node cells. Quantitative studies of the perivascular cell population in one MS case revealed, in histologically normal white matter 260 lymphocytes and 178 plasma cells per cubic millimeter of fresh tissue. Typical chronic plaque tissue without obvious inflammatory cell cuffing contained 1772 plasma cells per cubic millimeter of fresh tissue. No plasma cells were observed in the CNS in motor neuron disease. The results of this study suggest that perivascular macrophages in the CNS represent a specialized population of monocyte-derived free macrophages, that these cells differ functionally from Microglial cells, and that the digestion of myelin breakdown products in MS requires the participation of both cell types. The results also suggest that in some chronic MS cases there is a large, permanent population of CNS plasma cells that persists, like the elevated cerebrospinal fluid IgG level in this disease, for the life of the patient, that these cells, rather than inflammatory cells in fresh lesions, are the major source of this raised IgG, and that the existence of such a population of cells may indicate the continuing expression of antigens in chronic MS lesions in the absence of fresh lesion formation

  444. Adams CW, Bayliss OB, Turner DR (1975) Phagocytes, lipid-removal and regression of atheroma. J.Pathol. 116:225-238
    Abstract: Reticuloendothelial (RE) phagocytes (macrophages and histiocytes) can be distinguished from locally-derived lipid-containing cells (e.g., arterial smooth muscle) or locally derived phagocytes (e.g., Schwann cells and Microglia) by the demonstration of a diffuse catalase reaction in a proportion of these RE cells with a short incubation modification of the Novikoff-Golfischer diaminobenzidine histochemical methods. Even though only a proportion of an RE population is catalase-positive, the results accord with the majority of current opinion that most of the cells in atherosclerotic lesions are derived locally, whereas the phagocytes in lipid implants and xanthomas are of RE origin. The phagocytes in the peripheral nerve undergoing Wallerian degeneration appear to be of mixed RE and endogenous origin, whereas Microglia around multiple sclerosis plaques seem to be derived locally. Lipid in lesions with RE phagocytes (subcutaneous lipid implants and xanthomas) is relatively rapidly resorbed, whereas lipid in lesions with few RE phagocytes (atherosclerosis) or phagocytes of endogenous origin (CNS degeneration) is more slowly resorbed or partly retained within the tissue. Wallerian degeneration in the peripheral nerve, with its mixed population of RE and endogenous phagocytes, occupies an intermediate position in the speed of lipid removal