Acamprosate modulates experimental autoimmune encephalomyelitis.

OBJECTIVE: This pilot study aimed to determine the efficacy of acamprosate (N-acetyl homotaurine) in reducing the pathological features of experimental autoimmune encephalomyelitis (EAE) which is an animal model for multiple sclerosis (MS). BACKGROUND: The amino acid taurine has multiple biological activities including immunomodulation and neuromodulation. The synthetic acetylated taurine derivative, acamprosate, which crosses the blood-brain barrier more readily compared to taurine, is currently being used for the prevention of alcohol withdrawal symptoms associated with enhanced glutamatergic receptor function and GABA receptor hypofunction. METHODS: EAE was induced in C57BL/6 female mice with myelin oligodendrocyte glyocoprotein, amino acid 35-55. Mice were treated with 20, 100 and 500 mg/kg acamprosate for 21 days. RESULTS: Neurological scores at disease peak were reduced by 21, 64 and 9% in the 20, 100 and 500 mg/kg groups, respectively. Neurological improvement in the 100 mg/kg group correlated with a reduction in numbers of inflammatory lesions and the extent of CNS demyelination. Blood TNF-α levels were significantly reduced in the 500 mg/kg group. DISCUSSION: Acamprosate and other taurine analogs have a potential for future MS therapy.

Studies in B7-deficient mice reveal a critical role for B7 costimulation in both induction and effector phases of experimental autoimmune encephalomyelitis.

The importance of B7 costimulation in regulating T cell expansion and peripheral tolerance suggests that it may also play a significant regulatory role in the development of autoimmune disease. It is unclear whether B7 costimulation is involved only in the expansion of autoreactive T cells in the periphery, or if it is also required for effector activation of autoreactive T cells in the target organ for mediating tissue injury and propagating autoimmune disease. In this study, the role of B7-CD28 costimulation and the relative importance of B7 costimulators for the induction and effector phases of experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein (MOG) peptide were examined. Wild-type, B7-1/B7-2-deficient mice, or CD28-deficient C57BL/6 mice were immunized with MOG 35-55 peptide. Mice lacking both B7-1 and B7-2 or CD28 showed no or minimal clinical signs of EAE and markedly reduced inflammatory infiltrates in the brain and spinal cord. However, mice lacking either B7-1 or B7-2 alone developed clinical and pathologic EAE that was comparable to EAE in wild-type mice, indicating overlapping functions for B7-1 and B7-2. Resistance to EAE was not due to a lack of induction of T helper type 1 (Th1) cytokines, since T cells from B7-1/B7-2(-/-) mice show reduced proliferative responses, but greater interferon gamma production compared with T cells from wild-type mice. To study the role of B7 molecules in the effector phase of the disease, MOG 35-55-specific T lines were adoptively transferred into the B7-1/B7-2(-/-) and wild-type mice. Clinical and histologic EAE were markedly reduced in B7-1/B7-2(-/-) compared with wild-type recipient mice. These results demonstrate that B7 costimulation has critical roles not only in the initial activation and expansion of MOG-reactive T cells, but also in the effector phase of encephalitogenic T cell activation within the central nervous system.

T cell receptor (TCR) usage determines disease susceptibility in experimental autoimmune encephalomyelitis: studies with TCR V beta 8.2 transgenic mice.

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease that can be induced in laboratory animals by immunization with the major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP). We analyzed the role of the T cell receptor (TCR) repertoire in susceptibility to EAE induced by these two autoantigens. Autoreactive T cells induced after immunization with MBP use a limited set of TCR. In contrast, we demonstrate that T cell clones that recognize the encephalitogenic PLP epitope (PLP 139-151) use diverse TCR genes. When the TCR repertoire is limited by introduction of a novel rearranged TCR V beta 8.2 chain in transgenic SJL mice, EAE could be induced in the transgenic mice by immunization with the encephalitogenic epitopes of PLP, but not with the encephalitogenic epitope of MBP. Thus, skewing the TCR repertoire affects the susceptibility to EAE by immunization with MBP but not with PLP. These data demonstrate the biological consequences of the usage of a more diverse T cell repertoire in the development of an autoimmune disease.

The influence of the proinflammatory cytokine, osteopontin, on autoimmune demyelinating disease.

Multiple sclerosis is a demyelinating disease, characterized by inflammation in the brain and spinal cord, possibly due to autoimmunity. Large-scale sequencing of cDNA libraries, derived from plaques dissected from brains of patients with multiple sclerosis (MS), indicated an abundance of transcripts for osteopontin (OPN). Microarray analysis of spinal cords from rats paralyzed by experimental autoimmune encephalomyelitis (EAE), a model of MS, also revealed increased OPN transcripts. Osteopontin-deficient mice were resistant to progressive EAE and had frequent remissions, and myelin-reactive T cells in OPN-/- mice produced more interleukin 10 and less interferon-gamma than in OPN+/+ mice. Osteopontin thus appears to regulate T helper cell-1 (TH1)-mediated demyelinating disease, and it may offer a potential target in blocking development of progressive MS.

Vestibular (acoustic) schwannomas: histologic features in neurofibromatosis 2 and in unilateral cases.

Unilateral vestibular schwannomas (VS) differ from those in patients with neurofibromatosis 2 (NF-2) clinically and by in situ appearance. To determine whether there are histopathologic differences, the presence of each of 16 histologic features was compared in first surgical resection specimens of 48 VS from 39 NF-2 patients and 293 unilateral VS. Antoni A and B areas, nuclear atypia, whorls, scarring, chronic inflammation, and sheets of macrophages were found equally in both groups. Vestibular schwannomas in NF-2 had more Verocay bodies, foci of high cellularity, and lobular growth patterns, the latter possibly correlating with in situ appearance. Ten NF-2 VS specimens had either meningiomas or microscopic meningeal cell proliferations removed with the VS from the same area, whereas none of the patients with a unilateral VS had these findings. Unilateral VS had more hyalinized and malformed vessels, recent and old thromboses and hemosiderin deposits. The differences could not be attributed to patient ages because there were similar differences between the VS in NF-2 and the unilateral VS of 40 patients age-matched to the NF-2 patients. There were more female patients in both groups, but gender did not influence the occurrence of any histologic features. There were nine additional patients with apparently unilateral VS but in whom the diagnosis of NF-2 was suggested by additional findings; six of the VS from these patients had lobular patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

The extracellular matrix in multiple sclerosis lesions.

Receptor-mediated recognition of extracellular matrix (ECM) molecules transduces intracellular signals that determine many cellular behaviors under normal and pathological conditions. This review briefly describes the major central nervous system (CNS) white matter ECM molecules and their receptors, the mechanisms by which the ECM may be altered in multiple sclerosis (MS) lesions, and potential roles for inflammatory and CNS resident cell interactions with specific ECM molecules in these lesions. In acute lesions, ECM recognition and cell signaling contribute to leukocyte migration through blood vessel walls, and within the CNS, through leukocyte and CNS resident cell immune activation and demyelination. An abnormal ECM in chronic MS lesions may preclude ECM-dependent developmental processes that lead to remyelination and axon regeneration. Thus, the composition of the ECM and the cellular recognition of its individual components may be critical to the pathogenesis of all stages of MS. An understanding of these complex interactions may lead to additional strategies for intervention and the promotion of reparative processes in MS patients.

Major histocompatibility complex molecule expression in the human central nervous system: immunohistochemical analysis of 40 patients.

To determine factors affecting major histocompatibility complex (MHC) molecule expression in situ in the human central nervous system (CNS) cryostat tissue sections from 36 autopsies and four biopsies were stained by immunoperoxidase with antibodies to class I (HLA-alpha chain, beta-2 microglobulin), class II (HLA-DR, HLA-DQ) MHC, lymphocyte, and macrophage antigens and Factor VIII-related antigen (VIII-RA). Stained cells and vessels/mm2 were counted in gray and white matter of four CNS anatomic levels. Class I molecules were found on parenchymal and endothelial cells (approximately 50% of VIII-RA + vessels) but not neurons, and were more abundant in gray than white matter (p less than 0.02). Class I molecules were absent in infants, but in adults expression was unaffected by age, sex, postmortem interval, presence of CNS lesions, or systemic illnesses. Expression of HLA-alpha chain and beta-2 microglobulin were the same. Class II molecules were usually absent but were found on parenchymal and endothelial cells in older adults, most frequently in association with macrophage infiltrates and spinal cord tract degenerations, but not with systemic illnesses. Expression of HLA-DR was greater than that of HLA-DQ. In the human CNS, regulation regulation of expression of MHC molecules is complex, can be affected by age, regional anatomy, and by local or remote CNS lesions, and may influence patterns and degrees of T cell immune responses.

White matter extracellular matrix chondroitin sulfate/dermatan sulfate proteoglycans in multiple sclerosis.

Extracellular matrix (ECM) alterations in the central nervous system (CNS) of multiple sclerosis (MS) patients result from blood-brain barrier breakdown, release and activation of proteases, and synthesis of ECM components. To elucidate their potential pathophysiologic roles, we analyzed expression of major CNS ECM proteoglycans (PGs) in MS and control CNS tissues. In active MS plaque edges, 3 CNS lecticans (versican, aggrecan, and neurocan) and dermatan sulfate PG were increased in association with astrocytosis; in active plaque centers they were decreased in the ECM and accumulated in foamy macrophages, suggesting that these ECM PGs are injured and phagocytosed along with myelin. In inactive lesions they were diminished and in normal-appearing white matter they showed heretofore-unappreciated abnormal heterogeneous aggregation. Phosphacan, an ECM PG abundant in both gray and white matter, was less markedly altered. Since in development the spaciotemporal expression of ECM PGs influences neurite outgrowth, cell migration, axon guidance, and myelination, these data suggest that 1) enhanced white matter lectican and dermatan sulfate PG expression in the pro-inflammatory milieu of expanding lesion edges contributes to their sharp boundaries and the failure of neuronal ingrowth; 2) decreases in plaque centers may preclude regeneration and repair; and 3) diffuse ECM PG damage relates to axon degeneration outside of overt lesions. Thus, ECM PG alterations are specific, temporally dynamic, and widespread in MS patients and may play critical roles in lesion pathogenesis and CNS dysfunction.

Matrix metalloproteinases in the normal human central nervous system, microglial nodules, and multiple sclerosis lesions.

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.

Vitronectin and integrin vitronectin receptor localization in multiple sclerosis lesions.

Vitronectin (Vn) is a multifunctional plasma and extracellular matrix glycoprotein involved in cell attachment, coagulation, phagocytosis, and the protection of bystander cells from complement- and T cell-mediated lysis. To determine where Vn is localized and where cells expressing integrin Vn receptors may recognize it in central nervous system (CNS) lesions of multiple sclerosis (MS), CNS tissue samples were immunostained for Vn and the alphav, beta 1, and beta 3 integrin Vn receptor subunits. By light and electron microscopy, Vn was localized within dystrophic, demyelinated axons in active but not chronic lesions, normal or other neurologic disease controls. This localization is distinct from that of other plasma proteins in MS lesions and it differs from the pattern of neuron cell body localization found in other conditions. Microvascular Vn was increased and small numbers of reactive astrocytes were also Vn-positive in active plaques. Endothelial cell expression of the alpha v subunit was increased over controls and that of the beta 1 subunit was decreased whereas both the alpha v and beta 1 subunits were prominently expressed on macrophages and glia in active lesions. The beta 3 integrin subunit was expressed on platelets within and around vessels and was more prominent on endothelial cells in active plaques. The precise functions of Vn in situ are not presently known. These results indicate, however, that the regulation of expression of integrin Vn receptors is complex and that Vn may be recognized and have multiple functions in different microanatomic sites as MS lesions evolve. Intravascular Vn could participate in clotting, thereby contributing to leukocyte extravasation.(ABSTRACT TRUNCATED AT 250 WORDS)

The immunopathology of acute experimental allergic encephalomyelitis. IV. An ultrastructural immunocytochemical study of class II major histocompatibility complex molecule (Ia) expression.

Cell surface expression of Class II major histocompatibility complex (Ia) molecules is required for antigen recognition by T cells. To determine the ultrastructural cellular distribution of Ia molecules in the autoimmune disease model acute experimental allergic encephalomyelitis (EAE) we studied central nervous system (CNS) tissues from adult Strain 13 guinea pigs (GP). Experimental allergic encephalomyelitis was induced by sensitization with GP spinal cord homogenate in complete Freund's adjuvant (CFA). Nine of 11 sensitized GP had clinical and histologic EAE whereas unsensitized and CFA-sensitized controls were normal. Central nervous system tissues were reacted with monoclonal antibodies to either GP Ia or T cell surface antigen using an avidin-biotin immunoperoxidase technique and studied by electron microscopy; Ia was found on luminal but not abluminal surfaces of many meningeal and parenchymal vascular endothelial cells in GP with EAE. In EAE perivascular lymphocytes and macrophages and processes of unidentified cells in the parenchyma expressed surface Ia and Ia+ macrophages encircled and phagocytosed myelin. T cells were found predominantly in perivascular inflammatory cuffs. These observations indicate that following immunologic challenge Ia is expressed on luminal surfaces of vascular endothelium and on resident CNS cells, suggesting the possibility that these cells may have active antigen-presenting functions in CNS inflammatory reactions.

Endothelial cell class II major histocompatibility complex molecule expression in stereotactic brain biopsies of patients with acute inflammatory/demyelinating conditions.

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.

Glial fibrillary acidic protein in hepatic encephalopathy. An immunohistochemical study.

Basal ganglia, thalamus, cerebral cortex, and subcortical white matter were studied in ten cases of hepatic encephalopathy (HE), including three cases of acquired hepatocerebral degeneration (HCD), and in thirteen age-matched controls using the peroxidase-antiperoxidase immunohistochemical staining technique for glial fibrillary acidic (GFA) protein. HE cases all had pronounced Alzheimer type II astrocytosis. The perikarya and processes of Alzheimer type II glia did not stain for GFA protein. Staining of perivascular endfeet was evaluated by first selecting blood vessels throughout the gray and white matter in hematoxylin and eosin-stained slides to eliminate bias. The vessels were then identified in sections stained for GFA protein and graded as to complete circumferential, partial circumferential, or absence of staining. Both the degree and frequency of staining in the basal ganglia, thalamus, and cerebral cortex were significantly decreased in cases of HE; no statistically significant differences were found for the white matter. There were no significant differences in staining between HCD and other HE cases. These findings show that the Alzheimer II change is associated with a loss of immunohistochemically detectable GFA protein in cerebral gray matter.

Acute experimental allergic encephalomyelitis in SJL/J mice induced by a synthetic peptide of myelin proteolipid protein.

Clinical, histologic, and ultrastructural characteristics of acute experimental allergic encephalomyelitis (EAE) induced by sensitization with a synthetic peptide corresponding to mouse myelin proteolipid protein (PLP) residues 139-151 HCLGKWLGHPDKF were studied in SJL/J mice. Groups of mice were immunized with 20, 50, or 100 nmol of the peptide and were killed from seven to 28 days after sensitization or when they were moribund. Beginning on Day 9, the mice showed signs of EAE and the disease progressed rapidly to paralysis. Central nervous system (CNS) inflammation, edema, gliosis, and demyelination were found in all mice killed between Days 10 and 28 and white matter lesion areas correlated with clinical score at the time the mice were killed. Peripheral nerve roots and the cauda equina did not have lesions. Within the range studied, the severity of clinical or histologic disease was the same regardless of the PLP peptide dose. Two of ten mice immunized with 100 nmol and none of 14 mice given smaller doses of a synthetic peptide of mouse myelin basic protein (MBP) showed clinical EAE. These mice had small numbers of CNS lesions that were indistinguishable from those in PLP peptide-sensitized mice. These findings demonstrate that immunization of SJL/J mice with PLP peptide 139-151 produces a disease with the clinical and morphologic features of CNS tissue-, whole PLP-, whole MBP-, and MBP peptide-induced acute EAE. Thus, PLP is a major encephalitogen and immune reactions to epitopes of different myelin proteins may induce identical patterns of injury in the CNS.

November 1996--premature baby with lethargy and coma.

A premature male baby (28 weeks gestational age) was delivered by Cesarean section and required ventilation for respiratory distress syndrome during the first postnatal week. Four weeks postnatally, he had an episode of transient renal failure followed by lethargy leading to coma. Ultrasound changes were interpreted as intraventricular hemorrhage, grade 2. The baby died 31 days after birth. Autopsy showed bilateral thrombosis of the deep cerebral veins.

Reversal of early diffusion-weighted magnetic resonance imaging abnormalities does not necessarily reflect tissue salvage in experimental cerebral ischemia.

BACKGROUND AND PURPOSE: Diffusion-weighted MRI (DWI) can detect early ischemic changes and is sometimes used as a surrogate neurological end point in clinical trials. Recent experimental stroke studies have shown that with brief periods of ischemia, some DWI lesions transiently reverse, only to recur later. This study examined the histological condition of the tissue during the period of DWI reversal. METHODS: Rats underwent 30 minutes of middle cerebral artery occlusion followed by reperfusion. DWI images were obtained during ischemia and 3 to 5 hours, 1 day, and 7 days later. MRI scans were compared with histology (5 hours, n=5; 7 days, n=5) with the use of neuronal (microtubule-associated protein 2 [MAP2]) and astrocytic (glial fibrillary acidic protein [GFAP]) markers and heat-shock protein 72 (HSP72). RESULTS: DWI abnormalities reversed 3 to 5 hours after ischemia onset but recurred at 1 day. Four animals showed complete reversal of the initial DWI hyperintensity, and 6 showed partial reversal. When the 5-hour DWI was completely normal, there was significant loss of MAP2 immunoreactivity, comprising approximately 30% of the initial DWI lesion. However, GFAP staining revealed morphologically normal astrocytes. HSP72 immunoreactivity at 5 hours was extensive and corresponded to the initial DWI lesion. CONCLUSIONS: After brief ischemic periods, normalization of the DWI does not necessarily imply that the tissue is normal. Neurons already exhibit evidence of structural damage and stress. Normal GFAP staining suggests that other nonneuronal cell populations may partially compensate for altered fluid balances at the time of DWI reversal despite the presence of neuronal injury. These observations suggest that caution is warranted when relying solely on DWI for assessment of ischemic damage.

Experimental histoplasmosis in mice treated with anti-murine interferon-gamma antibody and in interferon-gamma gene knockout mice.

Histoplasma capsulatum is an important fungal pathogen in immunocompromised hosts, including AIDS patients. Experimental evidence suggests interferon-gamma (IFN) plays a role in host defense against H. capsulatum. In these studies we sought to demonstrate the importance of IFN in innate resistance to systemic histoplasmosis. The possible exacerbation of infection in BALB/c mice was assessed by administering 200 microg of hamster anti-IFN antibody prior to infection with H. capsulatum (2 x 10(6) yeasts, i.v.) and by comparing the severity of infection between BALB/c IFN gene knockout mice (GKO) and congenic control animals. In two separate studies, we found that anti-IFN treatment caused a dramatic loss of resistance to lethal infection and resulted in earlier mortality of IFN-depleted animals compared with normal IgG or no treatment (P<0.001). GKO mice were significantly (P<0.001) more susceptible to lethal infection than were control animals, and histological studies corroborated this. These studies clearly demonstrate that IFN is a vital part of the host's innate resistance to systemic infection with H. capsulatum and provide an additional rationale for studying IFN as an immunomodulatory therapeutic for the treatment of this disease.

Genetic and epigenetic influence on EAE phenotypes induced with different encephalitogenic peptides.

Different encephalitogenic peptides can induce two distinct experimental autoimmune encephalomyelitis (EAE) phenotypes in different mouse strains. To determine whether different peptides induce distinct phenotypes in genetically identical mice, parental strain and (SJLXC3H/HeJ)F1 mice were sensitized with myelin proteolipid protein peptide p139-151 or p215-232. p139-151 was non-encephalitogenic in C3H/HeJ mice and p215-232 was non-encephalitogenic in SJL mice. p139-151 induced typical acute EAE in SJL and F1 mice with most CNS inflammatory/demyelinating lesions located in the spinal cord. p215-232 induced mild clinical disease in only two of 10 C3H/HeJ mice; in 11 of 13 F1 mice (85%) it induced a disease spectrum that included typical paralytic acute EAE with a predominance of spinal cord lesions and later-onset mild EAE with predominance of brain stem/cerebellar lesions. Thus, the EAE phenotype induced in F1 mice by one encephalitogen, e.g. p139-151, can be the same as that induced in the susceptible parent. However, other encephalitogenic peptides, e.g. p215-232, may induce a broad range of heterogeneous EAE phenotypes in syngeneic mice. These data indicate that in some encephalitogenic responses, epigenetic factors influence EAE incidence, time of onset, severity, neurological signs and CNS lesion distribution.

Altered peptide ligand modulation of experimental allergic encephalomyelitis: immune responses within the CNS.

An altered peptide ligand (analog) of the encephalitogenic epitope of proteolipid protein residues 139-151 (p139-151) in which residues 144 and 147 are substituted with leucine and arginine, respectively (LR), protects from clinical but not histological experimental allergic encephalomyelitis (EAE). To understand in situ events associated with this protection, T cells from brains of mice immunized with either native p139-151, the analog LR or a combination of the two were isolated and characterized. High proportions of cells from co-immunized mice (38%) and LR-immunized mice (58%) reacted to both p139-151 and LR, whereas fewer cells from p139-151 immunized mice (7%) were cross-reactive. T cell clones derived from brains of LR- and co-immunized mice were also cross-reactive in vitro. By reverse transcriptase-based polymerase chain reaction, higher levels of TGF-beta mRNA, and lower levels of TNF-alpha and IFN-gamma mRNA were found in the central nervous system (CNS) tissue of LR and co-immunized mice. Immunohistochemistry demonstrated greater TGF-beta immunoreactivity in CNS inflammatory foci in co-immunized and LR-immunized mice. There were no significant differences in CD4+ or CD8+ cell infiltrates among the groups and differences in other cytokines were not identified by immunocytochemistry. Protection from clinical EAE in LR and co-immunized mice was partially abolished by anti-TGF-beta antibody treatment. Thus, protection from clinical disease following immunization with the analog LR is associated with infiltration into the CNS of a T cell population that could potentially recognize the native PLP peptide and with enhanced TGF-beta production by cells within CNS inflammatory foci.

Molecular mimicry between a viral peptide and a myelin oligodendrocyte glycoprotein peptide induces autoimmune demyelinating disease in mice.

Semliki Forest Virus (SFV) induces an encephalomyelitis followed by demyelination in the brains of C57Bl6/J (B6) mice. To investigate the role of molecular mimicry in the pathogenesis of postviral demyelination, alignment algorithms were used and amino acid homologies between immunogenic epitopes of SFV and myelin autoantigens, myelin basic protein (MBP), myelin proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) were identified. Immunization of B6 mice with SFV proteins induced significant lymphocyte proliferation to SFV E2 peptides and to MOG peptide, 18-32 (which had molecular mimicry with E2 115-129), but not to MBP or PLP peptides. Both MOG 18-32 and E2 115-129, induced a later-onset chronic EAE-like disease that correlated with the presence of multifocal vacuolation in the CNS white matter. This histopathology was reminiscent of the secondary demyelination seen following SFV infection. Serum antibody responses to the peptides appeared late after immunizations and some samples cross-reacted with other myelin peptides, as well as with the mimicked MOG peptides. These findings suggest that following a CNS viral infection, antibody response to an epitope of virus that exhibits molecular mimicry with a peptide of MOG may contribute to autoimmune mediated injury to CNS myelin.