IL-6-deficient mice resist myelin oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is induced by immunization with myelin components including myelin oligodendrocyte glycoprotein (MOG). Myelin-specific Th1 cells enter the central nervous system (CNS) via binding of very late antigen 4 (VLA-4) to the endothelial vascular cell adhesion molecule 1 (VCAM-1). In the present study, mice with a homologous disruption of the gene encoding IL-6 are found to be resistant to MOG-induced EAE as evidenced by absence of clinical symptoms, minimal infiltration of CD3⁺ T cells and monocytes into the CNS and lack of demyelination. The failure to induce EAE in IL-6^{− / −} mice is not due to the absence of priming, since lymphocytes of immunized IL-6^{− / −} mice proliferate in response to MOG and produce pro-inflammatory cytokines including IL-2 and IFN-γ. However, in MOG-immunized IL-6^{− / −} mice, serum anti-MOG antibody titers were found to be drastically reduced. This observation is unlikely to be responsible for resistance to EAE, because B cell-deficient (μMT) mice proved to be fully susceptible to the disease. A striking difference between MOG-immunized wild-type (wt) and IL-6^{− / −} mice was the expression of endothelial VCAM-1 and ICAM-1, which were dramatically up-regulated in the CNS in wt but not in IL-6^{− / −} mice. Taking into account recent studies on the role of VCAM-1 in the entry of Th1 cells into the CNS, the absence of VCAM-1 on endothelial cells in IL-6^{− / −} mice may explain their resistance to EAE.     

Chronic relapsing experimental autoimmune encephalomyelitis with a delayed onset and an atypical clinical course,induced in PL/J mice by myelin oligodendrocyte glycoprotein (MOG)-derived peptide: Preliminary analysis of MOG T cell epitopes

Myelin basic protein (MBP) and proteolipid protein (PLP), the most abundant proteins of central nervous system (CNS) myelin, have been extensively studied as possible primary target antigens in multiple sclerosis (MS), a primary demyelinating autoimmune disease of the CNS. However, there is increasing evidence to suggest that autoimmune reactivity against the quantitatively minor myelin component, myelin oligodendrocyte glycoprotein (MOG), can also play a role in the pathogenicity of MS. We recently demonstrated a predominant response to MOG by peripheral blood lymphocytes from patients with MS tested for their reactivity against various myelin antigens, including MBP and PLP. To ascertain whether or not T cell reactivity to MOG in MS is a potentially pathogenic response, we have tested the ability of synthetic MOG peptides (pMOG) representing potential T cell epitopes, to induce neurological disease in mice. Both strains of mice tested (SJL/J and PL/J mice) were able to mount a primary T cell response to some of the five MOG peptides synthesized, pMOG 1–21, 35–55, 67–87, 104–117 and 202–218. T cell lines could be raised in both strains to pMOG 35–55 and 67–87, but epitope definition revealed that each strain recognized a different minimal epitope within these two peptides. T cell lines to pMOG 1–21 and 202–218 could also be raised in SJL/J and PL/J mice, respectively. T cell reactivity to pMOG 104–117 was not observed in either mouse strain. None of the peptides tested induced detectable clinical signs in SJL/J mice. In contrast, an MS-like chronic relasping-remitting disease could be induced in PL/J mice with pMOG 35–55. The disease presented with a delayed onset and with clinical signs which differed significantly in their progression and expression from the typical ascending paralysis of experimental autoimmune encephalomyelitis induced with other myelin components, such as MBP and PLP. Histological examination of CNS tissue from mice injected with pMOG 35–55 revealed only mild neuropathological signs with few inflammatory foci in brain and spinal cord. Some myelin splitting and edema were detected upon electron microscopic examination in the spinal cord and cerebellum. Transfer of pMOG 35–55 reactive T cells into naive PL/J mice resulted in pathological changes characterized by inflammatory foci in the brain and spinal cord. This passively induced disease was clinically silent, as was also reported for Lewis rats injected with T cells specific for the same MOG peptide. These data, which demonstrate unequivocally the encephalitogenic activity of MOG, support our contention that MOG may be as important as MBP or PLP in disease pathogenesis and could be a primary target antigen in autoimmune diseases of the CNS.     

A myelin oligodendrocyte glycoprotein peptide induces typical chronic experimental autoimmune encephalomyelitis in H-2b mice: Fine specificity and T cell receptor Vβ expression of encephalitogenic T cells

A predominant response to myelin oligodendrocyte glycoprotein (MOG) was recently observed in patients with multiple sclerosis (MS). To study the possible pathogenic role of T cell response to MOG in MS, we have investigated the encephalitogenic potential of MOG. Synthetic MOG peptides, pMOG 1-21, 35–55, 67–87, 104–117 and 202–218, representing predicted T cell epitopes, were injected into C57BL/6J and C3H.SW (H-2^b) mice. The mice developed significant specific T cell responses to pMOG 1–21, pMOG 35–55 and pMOG 104–117. However, pMOG 35–55 was the only MOG peptide which could induce neurological impairment. The highly reproducible disease was chronic, with ascending paralysis and neuropathology comparable with those observed in experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein or proteolipid protein, except that in H-2^b mice the disease was consistently non-remitting. These features differ markedly from those which we recently observed in PL (H-2^u) mice with pMOG 35–55-induced disease. In PL mice, pMOG 35–55-induces atypical chronic relapsing EAE, the expression and progression of which are unpredictable. Hence, in different mouse strains, the same MOG peptide can induce typical EAE characterized by ascending paralysis, or atypical EAE with unpredictable clinical signs. pMOG 35–55-specific T cells from H-2^b mice recognized an epitope within amino acids 40–55 of the MOG molecule, and pMOG 40–55-reactive T cell lines were encephalitogenic upon transfer into syngeneic recipients. The encephalitogenic pMOG 35–55-reactive C57BL/6J T cell lines expressed Vβ1, Vβ6, Vβ8, Vβ14 and Vβ15 gene segments, and the pMOG 35–55-reactive C3H.SW T cell lines expressed Vβ1, Vβ2, Vβ6, Vβ8, Vβ10, Vβ14, and Vβ15 gene segments. However, in both mouse strains, the utilization of the Vβ8 gene product was predominant (40–43 %). The highly reproducible encephalitogenic activity of pMOG 35–55 strongly suggests a pathogenic role for T cell reactivity to MOG in MS and supports the possibility that MOG may also be a primary target antigen in the disease.     

Myelin oligodendrocyte glycoprotein: a novel candidate autoantigen in multiple sclerosis

 Myelin oligodendrocyte glycoprotein (MOG) is a member of the immunoglobulin superfamily expressed exclusively in central nervous system (CNS) myelin. While the function of MOG is unknown, a number of studies have shown that immune responses to MOG contribute to the autoimmune-mediated demyelination seen in animals immunized with whole CNS tissue. This paper summarizes our recent studies, which unequivocally demonstrate that MOG by itself is able to generate both an encephalitogenic T cell response and an autoantibody response in Lewis rats and in several strains of mice. In Lewis rats the injection of both native MOG and MOG_35–55 peptide produces a paralytic relapsing-remitting neurological disease with extensive plaque-like demyelination. The antibody response to MOG_35–55 was highly restricted, as no reactivity to either other MOG peptides or myelin proteins could be detected. Fine epitope mapping showed that antibody from serum and cerebrospinal fluid of injected rats reacted strongly to MOG_37–46, which is contiguous to the dominant T cell epitope contained within MOG_44–55. NOD/Lt and C57BL/6 mice were also susceptible to severe neurological disease following injection with recombinant MOG or MOG_35–55 peptide, indicating that this specific CNS autoantigen, or some of its determinants, can induce a pathogenic response across animal species. Severe paralysis and extensive demyelination were seen in both strains, but NOD/Lt mice experienced a chronic relapsing disease whereas C57BL/6 mice had a chronic non-remitting disease. Moreover, transfer of MOG_35–55 T cells into naive NOD/Lt mice also produced severe neurological impairment as well as histological lesions. These results emphasize that a synergism between a T cell-response and anti-MOG antibodies may be important for the development of severe demyelinating disease. This, together with our demonstration that there is a predominant T cell response to MOG in patients with multiple sclerosis, clearly indicates that MOG is probably an important target autoantigen in this disease. Received: 6 June 1996 / Accepted: 20 August 1996     

Quantitative trait loci disposing for both experimental arthritis and encephalomyelitis in the DA rat; impact on severity of myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis and antibody isotype pattern

Quantitative trait loci (QTL) controlling inflammatory diseases with different organ specificity may hypothetically either be unique for one disease or shared among different diseases. We have investigated whether five non-MHC QTL controlling susceptibility to experimental arthritis in the DA rat also influence myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in an F2 intercross between inbred DA and PVG.RT1^a rats. Two of the five chromosome regions affecting arthritis in the DA rat also regulate phenotypes of EAE. The DA allele at markers in Cia3(collagen-induced arthritis QTL) on chromosome 4 is associated with more severe EAE and high levels of anti-MOG antibodies of the IgG2c subclass. Since production of antibodies of the IgG2c subclass may be stimulated by Th1 cells, and there is previous evidence that such cells promote EAE, it is possible that both of the studied phenotypes are controlled by the same gene or genes regulating Th1/Th2 cell differentiation. Furthermore, we show that Oia2(oil-induced arthritis QTL) on chromosome 4 regulates levels of anti-MOG antibodies of the IgG1 subclass and of anti-MOG IgE, but that this gene region does not affect clinical disease severity in our study. Since production of IgE and IgG1 may be stimulated by Th2 cells, this QTL may also control Th1/Th2 bias. We conclude that Cia3and Oia2regulate MOG-induced EAE in rats. Furthermore, since both EAE and arthritis phenotypes co-localize to these gene regions, they may harbor genes which are key regulators of pathogenic immune responses.     

Mice with an inactivation of the inducible nitric oxide synthase gene are susceptible to experimental autoimmune encephalomyelitis

Nitric oxide (NO) generated by the inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE). In this study mice genetically deficient for iNOS are shown to be susceptible to EAE induced by immunization with myelin oligodendrocyte glycoprotein (MOG). In iNOS (–/–) mice the course of disease was earlier in onset and more aggressive compared to control animals. A disease-relevant compensatory up-regulation of neuronal (n)NOS and endothelial (e)NOS with increased production of NO in iNOS (–/–) mice is excluded by 1) the failure to detect increased nNOS and eNOS mRNA, 2) the absence of detection of nitrosylated tyrosine residues in EAE tissue indicating absence of NO-derived peroxynitrite, and 3) the lack of disease-preventing effects of N^G-nitro-L -arginine methylester. In conclusion, these results do not support the hypothesis that NO is crucial for the development of EAE.     

Myelin oligodendrocyte glycoprotein-35-55 peptide induces severe chronic experimental autoimmune encephalomyelitis in HLA-DR2-transgenic mice

The use of HLA class II-transgenic (Tg) mice has facilitated identification of antigenic T cell epitopes that may contribute to inflammation in T cell-mediated diseases such as rheumatoid arthritis and multiple sclerosis (MS). In this study, we compared the encephalitogenic activity of three DR2-restricted myelin determinants [mouse (m) myelin oligodendrocyte glycoprotein (MOG)-35-55, human (h)MOG-35-55 and myelin basic protein (MBP)-87-99] in Tg mice expressing the MS-associated DR2 allele, DRB1*1501. We found that mMOG-35-55 peptide was strongly immunogenic and induced moderately severe chronic experimental autoimmune encephalomyelitis (EAE) with white matter lesions after a single injection in Freund's complete adjuvant followed by pertussis toxin. hMOG-35-55 peptide,which differs from mMOG-35-55 peptide by a proline for serine substitution at position 42, was also immunogenic, but not encephalitogenic, and was only partially cross-reactive with mMOG-35-55. In contrast, MBP-87-99, which can induce EAE in double-Tg mice expressing both HLA-DR2 and a human MBP-specific TCR, was completely non-encephalitogenic in HLA-DR2-Tg mice lacking the human TCR transgene. These findings demonstrate potent encephalitogenic activity of the mMOG-35-55 peptide in association with HLA-DR2, thus providing a strong rationale for further study of hMOG-35-55 peptide as a potential pathogenic determinant in humans.     

T cells specific for the myelin oligodendrocyte glycoprotein mediate an unusual autoimmune inflammatory response in the central nervous system

Myelin oligodendrocyte glycoprotein (MOG)-specific T cells mediate an autoimmune inflammatory response in the central nervous system (CNS) that differs radically from conventional models of T cell-mediated experimental allergic encephalomyelitis (EAE). Using synthetic peptides an encephalitogenic T cell epitope of MOG for the Lewis rat was identified within the extracellular IgG V-like domain of the protein, amino acids 44-53 (FSRVVHLYRN).The adoptive transfer of CD4⁺ T cells specific for this epitope induce an intense, dose-dependent inflammatory response in the CNS of naive syngeneic recipients. However, unlike the inflammatory response induced by myelin basic protein (MBP)-specific T cell lines, inflammation mediated by the MOG peptide-specific T cells failed to induce a gross neurological deficit. This unexpected observation was not due to a reduction in the overall inflammatory response in the CNS, but was specifically associated with a decrease in the extent of parenchymal (as opposed to perivascular) inflammation, a selective decrease in the number of ED1⁺ macrophages infiltrating the CNS, and a total lack of peripheral nerve inflammation. The decreased recruitment of macrophages into the CNS could not be ascribed to deficiences in the synthesis of interferon-γ, tumor necrosis factor-a, interleukin (IL)-6 or IL-2 by the T cell line. Moreover, this sub-clinical inflammatory response induced severe blood-brain barrier dysfunction as demonstrated by the induction of severe clinical disease following intravenous injection of a demyelinating MOG-specific monoclonal antibody. The neurological deficit in EAE thus exhibits an unexpected dependence on the identity of the target autoantigen, which determines the extent and nature of the local inflammatory response and ultimately the extent of the neurological deficit.     

Persistence of autoreactive myelin oligodendrocyte glycoprotein (MOG)-specific T cell repertoires in MOG-expressing mice

Experimental autoimmune encephalomyelitis, an experimental murine model for multiple sclerosis, is induced by stimulation of myelin-specific T lymphocytes. Myelin oligodendrocyte glycoprotein (MOG), a minor component of myelin proteins, is a potent autoantigen which contributes extensively to the anti-myelin response. In the present work, immunoscope analyses and sequencing of the oligoclonal expansions revealed anti-MOG Valpha and Vbeta public repertoires in lymphocytes infiltrating the CNS of wild-type (WT) mice. Moreover, a subset of CNS-infiltrating CD4+ T lymphocytes bearing the public Vbeta8.2 segment have an inflammatory phenotype strongly suggesting that it is encephalitogenic. We then observed that, in lymph node cells of MOG-deficient and WT animals, the Valpha and Vbeta public repertoires expressed by MOG-specific T cells are identical in both strains of mice and correspond to those found in the CNS of WT animals. These findings indicate that the MOG immunodominant determinant is unable to induce tolerance by deletion, and public anti-MOG T cell repertoires are selected for, regardless of the presence of MOG in the thymus and peripheral organs.     

不同磷脂肽段诱导的实验性自身免疫性脑脊髓炎模型病理特征多样性的研究

目的:探索是否不同磷脂肽段可以诱导Lewis大鼠产生不同的病理学表现。方法:采用髓鞘碱性蛋白82-99(MBP82-99)、MBP68-86、髓鞘少突胶质细胞糖蛋白35-55(MOG35-55)免疫Lewis大鼠,每天进行神经功能评分。免疫后取各组大鼠大脑、小脑、脑干和脊髓组织,观察炎性细胞浸润部位和浸润程度、有无脱髓鞘和轴索损害。结果:MBP68-86和MBP82-99两组大鼠的大脑、脑干、小脑和脊髓组织均有炎性细胞浸润,脊髓炎症程度重于其他部位;MBP68-86和MBP82-99诱导的脊髓炎症程度无统计学差异;MOG35-55组大鼠仅脊髓组织受累,且炎症程度明显低于MBP组,其余各组未见炎性细胞浸润。各组大鼠神经组织均未见脱髓鞘和轴索受累。结论:不同磷脂肽段诱导Lewis大鼠神经组织炎性细胞浸润的分布和程度不同。     

T cell epitope spreading to myelin oligodendrocyte glycoprotein in HLA-DR4 transgenic mice during experimental autoimmune encephalomyelitis

Epitope spreading has been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and human multiple sclerosis (MS). T cell epitope spreading has been demonstrated in rodents for myelin basic protein (MBP) and proteolipid protein (PLP) determinants, but not for myelin oligodendrocyte glycoprotein (MOG), another important myelin antigen. Moreover, the role of human autoimmunity-associated MHC molecules in epitope spreading, including HLA-DR2 and DR4, has not been formally examined. To address these questions, we investigated epitope spreading to MOG determinants in HLA-DR4 (DRB1*0401) transgenic mice during EAE. The data show that upon induction of EAE in HLA-DR4 transgenic mice with the immunodominant HLA-DR4-restricted MOG peptide 97-108 (MOG(97-108); TCFFRDHSYQEE), the T cell response diversifies over time to MOG(181-200) (core: MOG(183-191); FVIVPVLGP) and MBP. The spreading epitope MOG(181-200) binds with high affinity to HLA-DRB1*0401 and is presented by human HLA-DRB1*0401+antigen presenting cells. Moreover, this epitope is encephalitogenic in HLA-DRB1*0401 transgenic mice. This study demonstrates intra- and intermolecular epitope spreading to MOG and MBP in "humanized" HLA-DR4 transgenic mice.     

MOG1-125诱发的实验性自身免疫性脑脊髓炎大鼠模型

目的建立髓鞘少突胶质细胞糖蛋白多肽1-125(MOG1-125)诱发的实验性自身免疫性脑脊髓炎(EAE)大鼠模型。方法采用大鼠MOG1-125和福氏完全佐剂作为抗原。在第1天和第15天分别进行两次皮内注射抗原,免疫SD大鼠建立EAE的动物模型,观察其临床症状,取脊髓组织进行冰冻切片、半薄切片和超薄切片,光镜和电镜观察脊髓组织学改变。结果 SD大鼠在两次免疫后8～10 d发病,其发病率为15%。在快蓝染色和甲苯胺蓝染色后,发现脊髓白质存在广泛的脱髓鞘浅染区。通过透射电镜观察进一步证实脊髓白质存在脱髓鞘现象。结论采用大鼠MOG1-125和完全弗氏佐剂作为抗原对SD大鼠进行两次免疫,能够成功诱发出EAE模型。     

Transplantation of retrovirally transduced bone marrow prevents autoimmune disease in aged mice by peripheral tolerance mechanisms

Transplantation of bone marrow (BM) engineered to express self-antigen has been shown to protect 100% of young mice from myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), with thymic clonal deletion as a tolerance mechanism. Here, we asked whether aged mice can also be tolerised following transplantation with self-antigen-engineered BM and whether castration-induced thymus regrowth can enhance this outcomes. Then, 50% of aged mice were protected from EAE regardless of castration-induced thymus regrowth. EAE-free and diseased mice demonstrated MOG-specific lymphocyte proliferation and antibody production regardless of castration-induced thymus regrowth, consistent with lack of intrathymic deletion of self-antigen-reactive T cells. Although low chimerism levels ( < 4%) were observed, EAE-free mice showed significantly higher chimerism levels in lymphocytes in peripheral lymphoid organs compared with thymus. CD4⁺CD25⁺ regulatory T cells were elevated in lymph nodes of EAE-free mice. We conclude that transplantation of self-antigen expressing BM protects 50% of aged mice and castration-induced thymic regrowth had no effect on outcomes. Peripheral tolerance mechanisms are implicated since protection is associated with higher chimerism levels in peripheral T and B lymphocytes and with elevated regulatory T cells.     

Orally administered myelin basic protein in neonates primes for immune responses and enhances experimental autoimmune encephalomyelitis in adult animals

Antigen-driven tolerance is an effective method for suppression of autoimmune diseases. Adult animals can be tolerized against the induction of experimental autoimmune encephalomyelitis (EAE) by both oral and parenteral administration of myelin basic protein (MBP). We have found that in contrast to previous studies of neonatal tolerance in which parenterally administered autoantigens induced tolerance, the oral administration of MBP in neonatal rats did not result in tolerization to MBP, but instead, primed for immunologic responses. Proliferative responses to MBP and its encephalitogenic epitope were present in animals fed with MBP as neonates and co-culture of encephalitogenic T cells with cells from neonatal rats fed with MBP were associated with enhanced MBP responses rather than the suppression observed with cells from adult rats fed with MBP. Furthermore, neonates fed with MBP and immunized 6–8 weeks later with MBP in adjuvant to induce EAE revealed enhancement of disease severity, and were not protected from a second attack upon active reinduction of EAE. Subcutaneous injection of soluble MBP into neonates had no effect on EAE induction as adults, whereas intraperitoneal injection of MBP in neonates was associated with marked suppression of disease in adults. Suppression of EAE began to appear in animals fed with MBP at 4 weeks of age, and was similar to oral tolerance in adult animals when animals were fed at 6 weeks of age. These results suggest that immaturity of the immunoregulatory network associated with oral tolerance and sensitization to autoantigens via the gut in the neonatal period may contribute to the pathogenesis of autoimmune diseases.     

Frontline: Epitope recognition on the myelin/oligodendrocyte glycoprotein differentially influences disease phenotype and antibody effector functions in autoimmune demyelination

Preliminary observations of humoral immunity against the myelin oligodendrocyte glycoprotein (MOG) in experimental allergic encephalomyelitis (EAE) and human multiple sclerosis (MS) suggest that a subset of anti-MOG autoantibodies directed against conformational epitopes is of pathogenic predominance. Here, we provide proof that in marmoset EAE, autoantibodies reactive against conformational epitopes of MOG are not only responsible for aggravating demyelination, but also an essential factor for disease dissemination in space within the central nervous system, a hallmark for typical forms of human MS. In terms of effector mechanisms, IgG deposition and complement activation occur exclusively in association with presence of these conformational antibodies, while microglial/macrophage activation appears to be a common immunopathological finding regardless of the fine determinant specificity of anti-MOG antibodies. These findings highlight for the first time the complex heterogeneity of function and pathogenicity in the polyclonal anti-MOG antibody repertoire of outbred species. Because the linear and conformational antibody determinants of MOG are shared between marmosets and humans, these results are directly relevant to understanding effector mechanisms of organ damage in MS.     

Complement activation and expression during chronic relapsing experimental autoimmune encephalomyelitis in the Biozzi ABH mouse

Chronic relapsing experimental autoimmune encephalomyelitis (crEAE) in mice recapitulates many of the clinical and histopathological features of human multiple sclerosis (MS), making it a preferred model for the disease. In both, adaptive immunity and anti‐myelin T cells responses are thought to be important, while in MS a role for innate immunity and complement has emerged. Here we sought to test whether complement is activated in crEAE and important for disease. Disease was induced in Biozzi ABH mice that were terminated at different stages of the disease to assess complement activation and local complement expression in the central nervous system. Complement activation products were abundant in all spinal cord areas examined in acute disease during relapse and in the progressive phase, but were absent in early disease remission, despite significant residual clinical disease. Local expression of C1q and C3 was increased at all stages of disease, while C9 expression was increased only in acute disease; expression of the complement regulators CD55, complement receptor 1‐related gene/protein y (Crry) and CD59a was reduced at all stages of the disease compared to naive controls. These data show that complement is activated in the central nervous system in the model and suggest that it is a suitable candidate for exploring whether anti‐complement agents might be of benefit in MS.     

重组腺病毒介导神经生长因子转染实验性自身免疫性脑脊髓炎模型小鼠少突胶质细胞的凋亡及髓鞘化

背景:神经生长因子对正常的神经元凋亡具有抑制效应,能够提高其损伤修复的能力,在一些自身免疫性疾病中发挥治疗作用.目的:观察经外周转染重组腺病毒介导神经生长因子基因对实验性自身免疫性脑脊髓炎小鼠少突胶质细胞凋亡及髓鞘化的影响.方法:将30只雌性健康的C57BL/6小鼠随机分为3组,每组10只:正常组不进行任何处理;对照组...     

Relationship between the clinical scoring and demyelination in central nervous system with total antioxidant capacity of plasma during experimental autoimmune encephalomyelitis development in mice

Experimental autoimmune encephalomyelitis (EAE) was induced in a mouse model (C57/BL6) to investigate the antioxidant status of animals at various clinical stages of the disease. For this purpose, blood, brain and spinal cord samples from EAE mice were collected and examined at different scores following post-immunization with myelin oligodendrocyte glycoprotein (MOG). The clinical sign of mobility of animals on different days was associated with gradual increase in lipid peroxidation products (malondialdehyde, i.e. MDA) in brain and spinal cord. Changes in lipid peroxidation during EAE progression was inversely related to superoxide dismutase (SOD) activity in erythrocyte preparation. However, suppression of catalase in erythrocytes, tissue glutathione (GSH) and plasma total antioxidant capacity (FRAP assay) were the early events in EAE, occurred during scores 1 and 2. Biochemical alterations were corroborated with histopathological observations showing demyelination and inflammatory foci in central nervous system (CNS) of animals suffering from partial hind limb paralysis (score 3). These data suggest that generation of MDA in CNS is a continuous process during EAE induction and suppression of antioxidant factors are early events of the disease, but crucial in increasing the vulnerability of CNS to demyelinating lesions.     

Novel pathogenic epitopes of myelin oligodendrocyte glycoprotein induce experimental autoimmune encephalomyelitis in C57BL/6 mice

Myelin oligodendrocyte glycoprotein (MOG), a minor protein of the central nervous system myelin, is recognized as a potential target in multiple sclerosis and neuromyelitis optica. The extracellular domain of MOG is commonly used in a wide range of mouse strains and other animals to induce experimental autoimmune encephalomyelitis (EAE), an autoimmune animal model of multiple sclerosis, because it is a target for antibody‐mediated attack. Previous studies, using selected peptides, have indicated that MOG^35–55 peptide is an encephalitogenic epitope in C57BL/6 (H‐2^b) mice. A more systematic analysis of both T‐cell and B‐cell responses following immunization of C57BL/6 mice with either recombinant extracellular mouse MOG protein (1–116) or with overlapping peptides spanning the whole sequence of MOG, before assessment of responses to 15 mer and 23 mer peptides was undertaken. The studies identified T‐cell responses within the MOG^35–55 (extracellular domain) but also two new immunogenic and encephalitogenic T‐cell epitopes within residues MOG^113–127, MOG^120–134 (localized in the transmembrane region) and MOG^183–197 (in the second hydrophobic MOG domain). In addition, residue MOG^113–127 was found to be a B‐cell epitope, suggesting that this may be a useful adjunct for the induction of EAE as well as for immunological studies in C57BL/6 mice, which are increasingly being used to study immune function through the use of transgenic and gene knockout technology.     

PD‐1 expression is upregulated on adapted T cells in experimental autoimmune encephalomyelitis but is not required to maintain a hyporesponsive state

T cell adaptation is an important peripheral tolerogenic process which ensures that the T cell population can respond effectively to pathogens but remains tolerant to self‐antigens. We probed the mechanisms of T cell adaptation using an experimental autoimmune encephalomyelitis (EAE) model in which the fate of autopathogenic T cells could be followed. We demonstrated that immunisation with a high dose of myelin basic protein (MBP) peptide and complete Freund's adjuvant failed to effectively initiate EAE, in contrast to low dose MBP peptide immunisation which readily induced disease. The proportion of autopathogenic CD4⁺ T cells in the central nervous system (CNS) of mice immunised with a high dose of MBP peptide was not significantly different to mice immunised with a low dose. However, autopathogenic T cells in mice immunised with high dose MBP peptide had an unresponsive phenotype in ex vivo recall assays. Importantly, whilst expression of PD‐1 was increased on adapted CD4⁺ T cells within the CNS, loss of PD‐1 function did not prevent the development of the unresponsive state. The lack of a role for PD‐1 in the acquisition of the adapted state stands in striking contrast to the reported functional importance of PD‐1 in T cell unresponsiveness in other disease models.