Commentary: Sorting the wheat from the chaff: identifying demyelinating components of the myelin oligodendrocyte glycoprotein (MOG)-specific autoantibody repertoire

Myelin oligodendrocyte glycoprotein (MOG) is the only myelin protein known to initiate a demyelinating autoantibody response in EAE, an animal model for multiple sclerosis (MS). The pathophysiological significance of MOG-specific autoantibodies in MS is, however, controversial, as high titer antibody responses to MOG are also found in many patients with non-demyelinating neurological diseases. In this issue of the European Journal of Immunology, von Büdingen et al. demonstrate that demyelination in a primate model of MOG-induced EAE is mediated by MOG-specific antibodies directed against discontinuous, rather than linear, MOG epitopes. This functional segregation of pathogenic vs. non-pathogenic autoantibodies in terms of epitope specificity may be crucial to understand the relevance of MOG-specific responses in human disease. This commentary discusses these findings in the context of the structure and immunobiology of MOG, and their implications with respect to antibody-mediated demyelination in MS.     

Methylprednisolone induces reversible clinical and pathological remission and loss of lymphocyte reactivity to myelin oligodendrocyte glycoprotein in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model of human multiple sclerosis (MS). EAE, induced by immunisation with myelin-associated autoantigens, is characterised by an inflammatory infiltrate in the central nervous system (CNS) associated with axonal degeneration, demyelination and damage. We have recently shown in an experimental mouse model of autoimmune gastritis that methylprednisolone treatment induces a reversible remission of gastritis with regeneration of the gastric mucosa. Here, we examined the effect of oral methylprednisolone on the mouse EAE model of human MS induced by immunisation with myelin oligodendrocyte glycoprotein peptide (MOG_35–55). We examined the clinical scores, CNS pathology and lymphocyte reactivity to MOG_35–55 following treatment and withdrawal of the steroid. Methylprednisolone remitted the clinical signs of EAE and the inflammatory infiltrate in the CNS, accompanied by loss of lymphocyte reactivity to MOG_35–55 peptide. Methylprednisolone withdrawal initiated relapse of the clinical features, a return of the CNS inflammatory infiltrate and lymphocyte reactivity to MOG_35–55 peptide. This is the first study to show that methylprednisolone induced a reversible remission in the clinical and pathological features of EAE in mice accompanied by loss of lymphocyte reactivity to the encephalitogen. This model will be useful for studies directed at a better understanding of mechanisms associated with steroid-induced disease remission, relapse and remyelination and also as an essential adjunct to an overall curative strategy.     

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.     

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.     

Non‐invasive visual evoked potentials to assess optic nerve involvement in the dark agouti rat model of experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein

Experimental autoimmune encephalomyelitis (EAE) is the primary disease model of multiple sclerosis (MS), one of the most diffused neurological diseases characterized by fatigue, muscle weakness, vision loss, anxiety and depression. EAE can be induced through injection of myelin peptides to susceptible mouse or rat strains. In particular, EAE elicited by the autoimmune reaction against myelin oligodendrocyte glycoprotein (MOG) presents the common features of human MS: inflammation, demyelination and axonal loss. Optic neuritis affects visual pathways in both MS and in several EAE models. Neurophysiological evaluation through visual evoked potential (VEP) recording is useful to check visual pathway dysfunctions and to test the efficacy of innovative treatments against optic neuritis. For this purpose, we investigate the extent of VEP abnormalities in the dark agouti (DA) rat immunized with MOG, which develops a relapsing–remitting disease course. Together with the detection of motor signs, we acquired VEPs during both early and late stages of EAE, taking advantage of a non‐invasive recording procedure that allows long follow‐up studies. The validation of VEP outcomes was determined by comparison with ON histopathology, aimed at revealing inflammation, demyelination and nerve fiber loss. Our results indicate that the first VEP latency delay in MOG‐EAE DA rats appeared before motor deficits and were mainly related to an inflammatory state. Subsequent VEP delays, detected during relapsing EAE phases, were associated with a combination of inflammation, demyelination and axonal loss. Moreover, DA rats with atypical EAE clinical course tested at extremely late time points, manifested abnormal VEPs although motor signs were mild. Overall, our data demonstrated that non‐invasive VEPs are a powerful tool to detect visual involvement at different stages of EAE, prompting their validation as biomarkers to test novel treatments against MS optic neuritis.     

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.     

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.     

Paradoxical effects of arthritis-regulating chromosome 4 regions on myelin oligodendrocyte glycoprotein-induced encephalomyelitis in congenic rats

Immunoregulatory gene loci in different organ-specific inflammatory diseases often co-localize. We here studied myelin oligodendrocyte glycoprotein (MOG)-induced EAE in rat strains congenic for arthritis-regulating genome regions on chromosome 4. We used congenic rats with a 70-centimorgan (cM) fragment from the EAE- and arthritis-resistant PVG.1AV1 rat strain on the arthritis- and EAE-permissive Dark Agouti (DA) rat background. In addition, we evaluated three recombinant strains, C4R1-C4R3, which overlap with arthritis-linked loci. PVG.1AV1 alleles in the C4R1 recombinant did not affect arthritis, but conferred protection against MOG-EAE. PVG.1AV1 alleles in the C4R2 recombinant down-regulated arthritis but had no effect in MOG-EAE. Paradoxically, PVG.1AV1 alleles in the C4R3 recombinant down-regulated arthritis, but the same fragment increased serum levels of anti-MOG Ab and aggravated clinical MOG-EAE. Thus, we provide original evidence that the same genome regions can have opposite effects in different organ-specific inflammatory diseases. Interestingly, no apparent difference in the MOG-EAE phenotype was observed in full-length congenic rats and parental DA rats, suggesting that the disease amelioration in C4R1 and aggravation in C4R3 functionally counteract each other. The data set the stage for definition of the mechanisms and positioning of the genes regulating two organ-specific inflammatory diseases differently.     

MRI in experimental inflammatory and mitochondrial optic neuropathies

MRI is a powerful tool for evaluating structural and functional alterations in the optic nerve in experimental animal models of human disease. MRI-histopathological correlations have provided important insights into the pathogenesis of disease. Paramagnetic contrast agents have been used to serially visualize the foci and severity of disruption of the blood-optic nerve barrier and physiological neuronal alterations in living animals. Here I review the experience of our group in optic nerve imaging of experimental autoimmune encephalomyelitis and neurodegeneration induced by genetic manipulation of respiratory chain enzymes.     

Predominance of the autoimmune response to myelin oligodendrocyte glycoprotein (MOG) in multiple sclerosis: Reactivity to the extracellular domain of MOG is directed against three main regions

Our previous analysis of the T cell reactivity to myelin antigens in a group of 24 patients with multiple sclerosis (MS) and 16 control individuals revealed that the autoimmune response to myelin oligodendrocyte glycoprotein (MOG) predominates in MS over that to myelin basic protein (MBP), proteolipid protein or myelin-associated glycoprotein, suggesting a prevalent role for the autoimmune response to MOG in the pathogenesis of MS. Using a recombinant human MOG (rhMOG) preparation corresponding to the extracellular immunoglobulin-like domain of the MOG molecule, we have now analyzed another group of 52 MS patients and 49 control individuals for reactivity of their peripheral blood lymphocytes (PBL) to rhMOG and to MBP concomitantly. Of the 52 MS patients tested 24 responded to MOG and 10 out of 49 responded to MBP, whereas only 5 MOG-reactive and 4 MBP-reactive control individuals were detected out of the 49 tested. These results are therefore highly confirmatory of the predominant reactivity to MOG in MS. The analysis of the primary proliferative response to 11 synthetic overlapping peptides (phMOG) spanning the extracellular domain of human MOG by PBL from 9 MS patients and 15 control individuals (9 healthy controls and 6 patients with neurological diseases other than MS) further supports a prevalent role for the autoimmune response to MOG in MS, as only 1 of the 15 controls tested showed reactivity to any of the phMOG, whilst 5 out of the 9 patients studied reacted to at least 1 of the phMOG. PBL from 10 MS patients, and from 4 controls, were selected in vitro with each of the phMOG. Of the 10 patients studied 7 reacted to at least 1 phMOG upon secondary stimulation and the reactivity was mostly directed to epitopes localized within three main regions (amino acids 1–22, 34–56 and 64–96), as was observed for the primary response of PBL. The predominant response to MOG of PBL from MS patients as demonstrated in two separate studies using native MOG and rhMOG as antigens, and the high incidence of reactivity of these PBL compared to the lack of response to phMOG by control PBL, emphasize the relevance of MOG in MS pathogenesis and support a primary role for the autoimmune T cell response to MOG in disease development.     

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.     

Antibody response in Lewis rats injected with myelin oligodendrocyte glycoprotein derived peptides

Previous studies from our laboratory have demonstrated a predominantresponse to myelin oligodendrocyte glycoprotein (MOG) in patient6swith multiple scleros(MS) and showed that this molecule is ableto Induce in Lewis rats a chronic relapsingMS-like disease withextensive demyelination. To further study the possibility thatMOG is a primary target antigen in MS, we have begun to Investigatsthe encephallilogenioity and antibody response of differentsequences of the encompassing the MOG amino acid sequences 1-21,67-87,104-117and 202-216 were encaphalltogentic. In contrast, a single injectionof MOG35-55 was able to Induce severe neunogogical signs assiociatedwith inflemmation and demyelellnation. As indicated by theabsence of reactivity to the other MOG peptides tested as wellas other central nervous system mysalin proteins including myallinbasic protein and protalaid protein, the antibody response producedby MOG pepticles is highly restricted.     

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     

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.     

Effect of geranylgeranylacetone on optic neuritis in experimental autoimmune encephalomyelitis

Optic neuritis is an acute inflammatory demyelinating syndrome of the central nervous system (CNS) that often occurs in multiple sclerosis (MS). Since it can cause irreversible visual loss, especially in the optic-spinal form of MS or neuromyelitis optica (NMO), the present study was conducted to assess the effects of geranylgeranylacetone (GGA) on optic neuritis in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Myelin oligodendrocyte glycoprotein-induced EAE mice received oral administration of GGA at 500 mg/kg or vehicle once daily for 22 days. The effects of GGA on the severity of optic neuritis were examined by morphological analysis on day 22. Visual functions were measured by the multifocal electroretinograms (mfERG). In addition, the effects of GGA on severity of myelitis were monitored both on clinical signs and morphological aspects. The visual function, as assessed by the second-kernel of mfERG, was significantly improved in GGA-treated mice compared with vehicle-treated mice. GGA treatment decreased the number of degenerating axons in the optic nerve and prevented cell loss in the retinal ganglion cell layer. However, the severity of demyelination in the spinal cord remained unaffected with the treatment of GGA. These results suggest that oral GGA administration has beneficial effect on the treatment for optic neuritis in the EAE mouse model of MS.     

重组人髓鞘少突胶质细胞糖蛋白的表达、纯化及免疫原性

目的: 建立人少突胶质细胞糖蛋白细胞外Ig样结构域(MOG^Igd)的硫氧还蛋白(TrxA)融合表达系统,探讨表达产物MOG^Igd-TrxA融合蛋白的免疫原性。方法: (1)应用RT-PCR方法,以人脑组织的总RNA为模板扩增出编码MOG^Igd的cDNA序列,将MOG^Igd cDNA克隆到TrxA融合表达载体pET32a(+)中,重组质粒pET32a-MOG^Igd经表型筛选、酶切鉴定及测序鉴定后,转化至BL21(DEB)trxB^-宿主菌中经异丙硫代钠-β-D-半乳糖苷(IPTG)诱导表达,并通过金属鳌合亲和层析柱进行纯化。(2)C57BL/6小鼠分为MOG^Igd-TrxA组(MOG组)、硫氧还蛋白组(TrxA组)及正常对照组(NC组),12只／组,各组以相应抗原乳剂免疫小鼠制作实验性自身免疫性脑脊髓炎(EAE)模型后观察其临床神经功能和组织病理学改变(HE染色和髓鞘Luxol fast blue染色)评价模型质量。结果: (1)成功获取高产量32 kD MOG^Igd-TrxA融合蛋白,以包涵体形式表达,纯化后纯度达95％左右。(2)MOG组小鼠75％(9/12)发病,于免疫后第(12.14±2.04)d发病,呈慢性非缓解型病程;发病动物组织切片HE染色和髓鞘染色显示不同程度炎性细胞浸润和髓鞘脱失。结论: 成功建立人MOG^Igd的TrxA融合表达系统,表达产物MOG^Igd-TrxA融合蛋白可作为免疫原诱导EAE动物模型。     

Delineation of the minimal encephalitogenic epitope within the immunodominant region of myelin oligodendrocyte glycoprotein: diverse Vβ gene usage by T cells recognizing the core epitope encephalitogenic for T cell receptor Vβb and T cell receptor Vβa H-2b mice

The nature of the autoimmune T cell response to myelin oligodendrocyte glycoprotein (MOG), recently recognized as a potential target antigen in multiple sclerosis (MS), has not yet been characterized, in contrast to the T cell reactivity to other potential target antigens in MS such as myelin basic protein and proteolipid protein. Here, we show that the encephalitogenicity of the recombinant Ig-like domain of human MOG is associated, in H-2^b mice, with an immunodominant T cell reactivity against a single region of MOG spanning amino acids 35–55, accounting for the previously reported strong encephalitogenic activity of pMOG 35–55. A single injection of pMOG 35–55 with or without administration of pertussis toxin was sufficient to induce severe clinical experimental autoimmune encephalomyelitis (EAE) in H-2^b mice. Encephalitogenic pMOG 35–55-specific T cell lines derived from C3H.SW (Vβ^b) mice were diverse in their TCR Vβ gene usage (Vβ1, Vβ6, Vβ8 and Vβ15), although Vβ8.2 was most predominantly expressed (48%). However, Vβ8⁺ T cells may only be part of the encephalitogenic MOG-specific T cell repertoire in H-2^b mice, as demonstrated by the susceptibility of C57L (Vβ^a) mice to disease induced by pMOG 35–55. Encephalitogenic T cell lines from Vβ^a mice were also diverse in their TCR Vβ gene usage (Vβ1, Vβ2, Vβ6, Vβ14 and Vβ16). Such a heterogeneous TCR Vβ gene expression by pMOG 35–55/I-A^b-reactive T cells from both Vβ^a and Vβ^b H-2^b mice suggested multiple epitopes within pMOG 35–55. Analysis of the pattern of reactivity by pMOG 35–55-reactive T cells to a set of truncated peptides was not commensurate with independent nested epitopes, but revealed a requirement for recognition of a core sequence, YRSPFSRVV (pMOG 40–48). However, optimal stimulation was obtained with longer peptides, with each additional amino acid flanking either the N or the C terminus differentially increasing the stimulatory capacity of pMOG 40–48. Nonetheless, pMOG 40–48 was the minimal encephalitogenic epitope for both Vβ^a and Vβ^b mice. Thus, the T cell reactivity against the immunodominant encephalitogenic region of MOG is characterized by a diverse Vβ gene usage and a requirement for the same core epitope. This pattern of reactivity may favor epitope-directed, rather than TCR-targeted, approaches to immunospecific therapy for MOG-related autoimmune disease.     

Anti‐myelin antibodies play an important role in the susceptibility to develop proteolipid protein‐induced experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is an autoimmune disorder in which activated T cells cross the blood–brain barrier (BBB) to initiate an inflammatory response that leads to demyelination and axonal damage. The key mechanisms responsible for disease initiation are still unknown. We addressed this issue in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. It is widely known that EAE manifests only in certain strains when immunized with myelin proteins or peptides. We studied the differential immune responses induced in two mouse strains that are susceptible or resistant to EAE induction when they are immunized with the 139–151 peptide of proteolipid protein, an encephalitogenic peptide capable of inducing EAE in the susceptible strain. The adequate combination of major histocompatibility complex alleles and myelin peptides triggered in susceptible mice a T helper type 17 (Th17) response capable of inducing the production of high‐affinity anti‐myelin immunoglobulin (Ig)G antibodies. These were not detected in resistant mice, despite immunization with the encephalitogenic peptide in junction with complete Freund's adjuvant and pertussis toxin, which mediate BBB disruption. These data show the pivotal role of Th17 responses and of high‐affinity anti‐myelin antibodies in EAE induction and that mechanisms that prevent their appearance can contribute to resistance to EAE.     

St. John’s wort and its component hyperforin alleviate experimental autoimmune encephalomyelitis through expansion of regulatory T-cells

Multiple sclerosis (MS) is a central nervous system disorder mainly characterized by inflammation, demyelination and axonal injury. Anti-inflammatory agents can be used to ameliorate the disease process. Hypericum perforatum L or St. John’s wort is widely used as an anti-depressant and anti-inflammatory remedy in traditional and?herbal medicine. Based on St. John’s wort properties, the therapeutic potentials of an H. perforatum extract (HPE) and a single component,?hyperforin were evaluated for effectiveness against MOG_35–55-induced experimental autoimmune encephalomyelitis (EAE), an animal model for?human multiple sclerosis. Female C57BL/6 mice were immunized with specific antigen MOG_35–55 and then administered different doses of?hyperforin or HPE post-immunization. Clinical symptoms/other relevant parameters were assessed daily. Histological analysis of the spinal cord was performed. T-cell proliferative activity was also evaluated using a BrdU assay. The effect of?hyperforin on regulatory T-cells (T_reg cells) was assessed using flow cytometry. The results indicate?hyperforin and HPE reduced the incidence and severity of EAE, an outcome that closely correlated with an inhibition of pathological features (leukocyte infiltration and demyelination) and antigen-specific T-cell proliferation. The study also showed that?hyperforin caused increased T_reg cell levels in the spleen. These results indicated that?hyperforin and HPE could attenuate EAE autoimmune responses by inhibiting immune cell infiltration and expansion of T_reg cell and could eventually be considered as a potential candidate for use in the treatment of MS.     

地塞米松对实验性自身免疫性脑脊髓炎小鼠髓鞘保护作用的研究

目的:分析地塞米松对实验性自身免疫性脑脊髓炎(EAE)小鼠炎症反应、髓鞘脱失及髓鞘再生的影响,探讨地塞米松治疗多发性硬化的新作用。方法:应用MOG35-55免疫C57BL/6小鼠建立EAE模型。小鼠随机分为正常对照组、EAE组及地塞米松组,观察各组临床症状;采用HE染色、LFB染色、透射电镜扫描及免疫组化染色方法,检测免疫后第13、20、30 d各组小鼠脊髓组织炎症反应、髓鞘脱失及髓鞘再生情况。结果:地塞米松显著降低EAE小鼠发病率、延缓起病时间、减轻疾病严重程度。各个时间点地塞米松组脊髓组织炎性细胞浸润、髓鞘脱失及轴索变性程度较EAE组明显减轻。免疫后第20、30 d,EAE组Olig2阳性细胞数较正常对照组明显增加;免疫后各时间点,地塞米松组Olig2阳性细胞数较正常对照组均明显增加,第13、20 d较EAE组明显增加。结论:地塞米松可增加脊髓组织Olig2表达、促进髓鞘再生,这可能为地塞米松治疗EAE及多发性硬化的效应途径。