Changes in different parameters,lymphocyte proliferation and hematopoietic progenitor colony formation in EAE mice treated with myelin oligodendrocyte glycoprotein

Myelin oligodendrocyte glycoprotein (MOG) is an antigen of the myelin sheath, which may trigger immune cell responses and the production of auto‐antibodies in multiple sclerosis (MS). In this study, we used MOG_35‐55‐induced experimental autoimmune encephalomyelitis (EAE), a model of human MS, to assess the production of catalytically active immunoglobulin G (IgG) antibodies or abzymes which have been shown to be present in sera of patients with several autoimmune diseases. Here, we show that IgGs from the sera of control C57BL/6 mice are catalytically inactive. During development of EAE, a specific reorganization of the immune system of mice occurred leading to a condition which was associated with the generation of catalytically active IgGs hydrolysing DNA, myelin basic protein (MBP) and MOG which was associated with increased proteinuria, changes in differentiation of mice bone marrow hematopoietic stem cells (HSCs) and an increase in proliferation of lymphocytes in bone marrow, spleen and thymus as well as a significant suppression of cell apoptosis in these organs. The strongest alterations were found in the early disease phase (18–24 days after immunization) and were less pronounced in later EAE stages (40 days after EAE induction). We conclude that a significant increase in DNase and proteolytic activities of antibodies may be considered the earliest statistically significant marker of MOG‐induced EAE in mice. The possible differences in immune system reorganizations during preclinical phases of the disease, acute and late EAE, leading to production of different auto‐antibodies and abzymes as well other changes are discussed.     

Changes in haematopoietic progenitor colony differentiation and proliferation and the production of different abzymes in EAE mice treated with DNA

Immunization of experimental autoimmune encephalomyelitis (EAE)‐prone C57BL/6 mice with MOG_35‐55 (a model used to study aspects of human multiple sclerosis) is known to lead to the production of various abzymes. The production of catalytic IgGs that can efficiently hydrolyse myelin basic protein (MBP), MOG and DNA is associated with changes in the profile of differentiation and level of proliferation of mice bone marrow haematopoietic stem cells (HSCs). As MOG simulates the production of abzymes with high DNase activity, we compared the effects of DNA and MOG immunization on EAE‐prone mice. In contrast to MOG, immunization with DNA leads to a suppression of proteinuria, a decrease in the concentrations of antibodies to MOG and DNA and a reduction in abzyme production. Immunization with DNA only resulted in a significant increase in DNase activity over 40 days where it became 122‐fold higher than before immunization, and fivefold higher when comparing to the maximal activity obtained after MOG treatment. DNA and MOG immunization had different effects on the differentiation profiles of HSCs, lymphocyte proliferation, and the level of apoptosis in bone marrow and other organs of mice. The data indicate that for C57BL/6 mice, DNA may have antagonistic effects with respect to MOG immunization. The usually fast immune response following MOG injection in C57BL/6 mice is strongly delayed after immunization with DNA, which is probably due to a rearrangement of the immune system following the response to DNA.     

Influenza vaccine and learning in C57BL mice with an acute experimental autoimmune encephalomyelitis

Literature data suggest possible link between influenza vaccination and development of autoimmune processes. Therefore, the aim of the study was to investigate the effect of influenza vaccination on spatial learning in mice with experimental autoimmune encephalomyelitis (EAE). EAE was induced in eight-week-old C57BL/6J female mice by subcutaneous immunization (MOG_35–55 in complete Freund’s adjuvant) and Pertussis vaccine injected intraperitoneally. Mice were vaccinated with influenza vaccine three days before MOG immunization. The hippocampal-dependent spatial learning test, Morris Water Maze test (MWM), was performed before and after EAE induction. Significant difference (P < 0.05) in the time for completing the Morris Water Maze task was found between mice with mild clinical signs of EAE when compared to other mice. However no significant difference was observed between mice with EAE and mice with EAE that were vaccinated with influenza vaccine. Hippocampal tissue lesions in EAE mice are in correlation with memory impairment. Study shows no influence of influenza vaccine on progression of clinical signs of EAE, spatial learning and memory impairment.     

Treatment with Vitamin D/MOG Association Suppresses Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model to study multiple sclerosis (MS). Considering the tolerogenic effects of active vitamin D, we evaluated the therapeutic effect of myelin oligodendrocyte glycoprotein (MOG) associated with active vitamin D in EAE development. EAE was induced in female C57BL/6 mice by immunization with MOG emulsified with Complete Freund’s Adjuvant plus Mycobacterium tuberculosis. Animals also received two intraperitoneal doses of Bordetella pertussis toxin. One day after immunization, mice were treated with 0,1μg of 1α,25-dihydroxyvitamin D3 (1,25(OH)₂D₃) every other day during 15 days (on days 1, 3, 5, 7, 9, 11, 13 and 15). MOG (150μg) was co-administered on days 3 and 11. The administration of 1,25(OH) ₂D₃ or MOG determined significant reduction in EAE incidence and in clinical scores. When MOG was associated with 1,25(OH) ₂D₃ the animals did not develop EAE. Spleen and central nervous system (CNS) cell cultures from this group produced less IL-6 and IL-17 upon stimulation with MOG in comparison to the EAE control group. In addition, this treatment inhibited dendritic cells maturation in the spleen and reduced inflammatory infiltration in the CNS. The association of MOG with 1,25(OH) ₂D₃ was able to control EAE development.     

Protein Tyrosine Phosphatase Receptor Type Z Negatively Regulates Oligodendrocyte Differentiation and Myelination

Background

Fyn tyrosine kinase-mediated down-regulation of Rho activity through activation of p190RhoGAP is crucial for oligodendrocyte differentiation and myelination. Therefore, the loss of function of its counterpart protein tyrosine phosphatase (PTP) may enhance myelination during development and remyelination in demyelinating diseases. To test this hypothesis, we investigated whether Ptprz, a receptor-like PTP (RPTP) expressed abuntantly in oligodendrocyte lineage cells, is involved in this process, because we recently revealed that p190RhoGAP is a physiological substrate for Ptprz.

Methodology/Principal Findings

We found an early onset of the expression of myelin basic protein (MBP), a major protein of the myelin sheath, and early initiation of myelination in vivo during development of the Ptprz-deficient mouse, as compared with the wild-type. In addition, oligodendrocytes appeared earlier in primary cultures from Ptprz-deficient mice than wild-type mice. Furthermore, adult Ptprz-deficient mice were less susceptible to experimental autoimmune encephalomyelitis (EAE) induced by active immunization with myelin/oligodendrocyte glycoprotein (MOG) peptide than were wild-type mice. After EAE was induced, the tyrosine phosphorylation of p190RhoGAP increased significantly, and the EAE-induced loss of MBP was markedly suppressed in the white matter of the spinal cord in Ptprz-deficient mice. Here, the number of T-cells and macrophages/microglia infiltrating into the spinal cord did not differ between the two genotypes after MOG immunization. All these findings strongly support the validity of our hypothesis.

Conclusions/Significance

Ptprz plays a negative role in oligodendrocyte differentiation in early central nervous system (CNS) development and remyelination in demyelinating CNS diseases, through the dephosphorylation of substrates such as p190RhoGAP.     

Increased severity of experimental allergic encephalomyelitis in lyn-/- mice in the absence of elevated proinflammatory cytokine response in the central nervous system

lyn, a member of the src kinase family, is an important signaling molecule in B cells. lyn(-/-) mice display hyperactive B-1 cells and IgM hyperglobulinemia. The role of lyn on T cell function and development of Th1-mediated inflammatory disease is not known. Therefore, we examined the effect of disruption of the lyn gene on the development of experimental allergic encephalomyelitis (EAE), a well-established Th1-mediated autoimmune disease. Following immunization with myelin oligodendrocyte protein (MOG) p35-55, lyn(-/-) mice had higher clinical and pathological severity scores of EAE when compared with wild type (WT). The increase in the severity of EAE in lyn(-/-) mice was not associated with a commensurate increase in the production of proinflammatory cytokines in the CNS. lyn(-/-) mice with EAE showed elevation in serum anti-IgM MOG Ab levels over that seen in WT mice, along with a modest increase in the mRNA levels of complement C5 and its receptor, C5aR, in the spinal cord. Transfer of serum from MOG-immunized lyn(-/-) mice worsened EAE in WT mice, suggesting a pathogenic role for anti-MOG IgM Abs in EAE. These observations underscore the potential role of lyn in regulation of Th1-mediated disease and the role of autoantibodies and complement in the development of EAE.     

Analysis of TCR V beta gene usage and encephalitogenicity of myelin basic protein peptide p91-103 reactive T cell clones in SJL mice: lack of evidence for V gene hypothesis.

We have analyzed the epitope specificity and encephalitogenicity of peptides that span the C terminus of MBP, p84-103. Our studies show that multiple antigenic epitopes with disease-inducing capacity exist in SJL mice. Three peptides that span this region were examined and found to be immunogenic. However, the mode of immunization (active or passive) determined the incidence and severity of EAE. In our experiments adoptive transfer of p91-103-reactive T cell lines was most consistent in the development of disease. Interestingly, the response to peptides p89-101, p91-103, and p84-102 was absent following immunization with MBP. This suggests that although p91-103 and p89-101 were encephalitogenic they were not the major immunogenic epitopes following immunization with MBP. Analysis of a panel of eight p91-103-reactive T cell clones showed significant heterogeneity in the fine specificity, the TCR V beta gene usage, and in their ability of transfer EAE. These studies suggest that in SJL mice the epitopes involved in the pathogenesis of disease are multiple and there is no clear correlation between encephalitogenicity and TCR V beta gene usage. These observations argue against the presence of a dominant TCR V beta gene in the pathogenesis of EAE in SJL mice.     

Resistance to experimental autoimmune encephalomyelitis and impaired T cell priming by dendritic cells in Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 mutant mice

Src homology 2 domain-containing protein tyrosine phosphatase (SHP) substrate-1 (SHPS-1) is a transmembrane protein that binds the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is expressed on the surface of CD11c(+) dendritic cells (DCs) and macrophages. In this study, we show that mice that express a mutant form of SHPS-1 lacking most of the cytoplasmic region are resistant to experimental autoimmune encephalomyelitis (EAE) in response to immunization with a peptide derived from myelin oligodendrocyte glycoprotein (MOG (35-55)). The MOG (35-55)-induced proliferation of, and production of IFN-gamma, IL-2, and IL-17, by T cells from immunized SHPS-1 mutant mice were reduced compared with those apparent for wild-type cells. The abilities of splenic DCs from mutant mice to stimulate an allogenic MLR and to prime Ag-specific T cells were reduced. Both IL-12-stimulated and TLR-dependent cytokine production by DCs of mutant mice were also impaired. Finally, SHPS-1 mutant mice were resistant to induction of EAE by adoptive transfer of MOG (35-55)-specific T cells. These results show that SHPS-1 on DCs is essential for priming of naive T cells and the development of EAE. SHPS-1 is thus a potential therapeutic target in inflammatory disorders of the CNS and other autoimmune diseases.     

Lithium prevents and ameliorates experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) models, in animals, many characteristics of multiple sclerosis, for which there is no adequate therapy. We investigated whether lithium, an inhibitor of glycogen synthase kinase-3 (GSK3), can ameliorate EAE in mice. Pretreatment with lithium markedly suppressed the clinical symptoms of EAE induced in mice by myelin oligodendrocyte glycoprotein peptide (MOG35-55) immunization and greatly reduced demyelination, microglia activation, and leukocyte infiltration in the spinal cord. Lithium administered postimmunization, after disease onset, reduced disease severity and facilitated partial recovery. Conversely, in knock-in mice expressing constitutively active GSK3, EAE developed more rapidly and was more severe. In vivo lithium therapy suppressed MOG35-55-reactive effector T cell differentiation, greatly reducing in vitro MOG35-55- stimulated proliferation of mononuclear cells from draining lymph nodes and spleens, and MOG35-55-induced IFN-gamma, IL-6, and IL-17 production by splenocytes isolated from MOG35-55-immunized mice. In relapsing/remitting EAE induced with proteolipid protein peptide139-151, lithium administered after the first clinical episode maintained long-term (90 days after immunization) protection, and after lithium withdrawal the disease rapidly relapsed. These results demonstrate that lithium suppresses EAE and identify GSK3 as a new target for inhibition that may be useful for therapeutic intervention of multiple sclerosis and other autoimmune and inflammatory diseases afflicting the CNS.     

Why specific anti‐integrase antibodies from HIV‐infected patients can efficiently hydrolyze 21‐mer oligopeptide corresponding to antigenic determinant of human myelin basic protein

Human immunodeficiency virus‐infected patients possess anti‐integrase (IN) catalytic IgGs and IgMs (abzymes), which, unlike canonical proteases, specifically hydrolyze only intact globular IN. Anti‐myelin MBP abzymes from patients with multiple sclerosis and systemic lupus erythematosus efficiently hydrolyze only intact MBP. Anti‐MBP and anti‐IN abzymes do not hydrolyze several other tested control globular proteins. Here, we show that anti‐IN abzymes efficiently hydrolyze a 21‐mer oligopeptide (OP21) corresponding to one antigenic determinant (AGD) of MBP, whereas anti‐MBP abzymes extremely poorly cleave oligopeptides corresponding to AGDs of IN. All sites of IgG‐mediated and IgM‐mediated proteolysis of OP21 by anti‐IN abzymes were found for the first time by a combination of reverse phase and thin layer chromatography and mass spectrometry. Several clustered sites of OP21 cleavage were revealed and compared with the cleavage sites within the complete IN. Several fragments of OP21 had good homology with many fragments of the IN sequence. The active sites of anti‐IN abzymes are known to be located on their light chains, whereas heavy chains are responsible for the affinity for protein substrates. Interactions of intact IN with both light and heavy chains of the abzymes provide high affinity for IN and the specificity of its hydrolysis. Our data suggest that OP21 interacts mainly with the light chains of polyclonal anti‐IN abzymes, which possess lower affinity and specificity for substrate. The hydrolysis of the non‐cognate OP21 oligopeptide may be also less specific than the hydrolysis of the globular IN because in contrast to previously described serine protease‐like abzymes against different proteins, anti‐IN abzymes possess serine, thiol, acidic, and metal‐dependent protease activities. Copyright © 2013 John Wiley & Sons, Ltd.     

t-PA对EAE 病理性淋巴细胞与血脑屏障粘附的影响

目的：研究组织型纤溶酶原激活剂（t-PA）对实验性自身免疫性脑脊髓炎（EAE）小鼠病理性淋巴细胞与血脑屏障粘附的影 响。方法：用MOG35-55 肽段免疫C57BL/6小鼠建立EAE 动物模型,于发病高峰期取淋巴细胞用MOG35-55 肽段进行刺激得到 抗原特异性T淋巴细胞。通过尾静脉给予t-PA 的方法对EAE 小鼠进行干预,临床评分评价小鼠的发病情况。体外培养小鼠血脑 屏障内皮细胞系bEnd.3,应用不同浓度的t-PA 进行处理。用荧光标记MOG35-55 特异性T 细胞进行细胞粘附实验,用Transwell 小室建立体外血脑屏障模型进行细胞迁移实验。用免疫荧光化学方法检测ICAM-1 的表达情况。结果：t-PA处理可以使血脑屏障 内皮细胞与T 淋巴细胞粘附和迁移作用增强。在体外细胞培养模型中检测到t-PA诱导ICAM-1 表达升高。经过t-PA 处理的小 鼠,其血管内皮表面ICAM-1 的表达也有所上升。经t-PA 处理的EAE 小鼠发病高峰提前,症状加重。结论：t-PA 处理可以使EAE 病理性淋巴细胞与血脑屏障内皮的粘附性增加,浸润能力增强;t-PA 所引起的粘附性增加可能与bEnd.3 表面ICAM-1表达升高 有关。     

Rat and human myelin oligodendrocyte glycoproteins induce experimental autoimmune encephalomyelitis by different mechanisms in C57BL/6 mice

C57BL/6 mice immunized with the extracellular Ig-like domain of rat myelin oligodendrocyte glycoprotein (MOG) developed experimental autoimmune encephalomyelitis (EAE) resembling that induced by rodent MOG 35-55 in its B cell independence and predominantly mononuclear CNS infiltrate. In contrast, human MOG protein-induced EAE was B cell dependent with polymorphonuclear leukocytes. Human MOG differs from rat MOG at several residues, including a proline for serine substitution at position 42. Human MOG 35-55 was only weakly encephalitogenic, and a proline substitution in rat MOG at position 42 severely attenuated its encephalitogenicity. However, human MOG 35-55 was immunogenic, inducing proliferation and IFN-gamma and IL-13 to human, but not rodent MOG 35-55 [corrected]. The B cell dependence of EAE induced by human MOG protein was not due to a requirement for Ag presentation by B cells, because spleen cells from B cell-deficient mice processed and presented human and rat MOG proteins to T cells. The different pathogenic mechanisms of human and rat MOG proteins might result from different Abs induced by these proteins. However, rat and human MOG proteins induced Abs to mouse MOG that were equivalent in titer and IgG subclass. These data demonstrate that EAE can be induced in C57BL/6 mice by two mechanisms, depending on the nature of the immunogen: an encephalitogenic T cell response to rat MOG or rodent MOG 35-55, or an encephalitogenic B cell response to epitopes on human MOG protein that most likely cross-react with mouse determinants.     

Cutting edge: critical role for CD5 in experimental autoimmune encephalomyelitis: inhibition of engagement reverses disease in mice

The induction phase of experimental autoimmune encephalomyelitis (EAE) in mice is T cell dependent and coreceptors that regulate T cell activation modulate disease development. We report here that mice lacking CD5, an important modulator of T cell activation, exhibit significantly delayed onset and decreased severity of EAE. The resistance to EAE in CD5(-/-) mice was not due to the inability of T cells to respond efficiently to stimulation with MOG(35-55) but was associated with the presence of elevated frequency of apoptotic activated T cells in spleens and DLN. We also observed a net decrease in peripheral activated CD4(+) T cells in CD5(-/-) spleens and DLN 10 days after immunization. We further show that in vivo blockade of CD5 engagement after induction of EAE by soluble CD5-Fc, a treatment that induces elimination of activated T cells, promoted recovery from EAE. Our studies indicate that CD5 regulates survival of activated T cells and provides a target for treatment of T cell-dependent autoimmune diseases such as multiple sclerosis.     

Loss of IFN-gamma enables the expansion of autoreactive CD4+ T cells to induce experimental autoimmune encephalomyelitis by a nonencephalitogenic myelin variant antigen

MHC variant peptides are analogues of immunogenic peptides involving alterations of the MHC-binding residues, thereby altering the affinity of the peptide for the MHC molecule. Recently, our laboratory demonstrated that immunization of WT B6 mice with 45D, a low-affinity MHC variant peptide of MOG(35-55), results in significantly attenuated experimental autoimmune encephalomyelitis (EAE), yet IFN-gamma production is comparable to myelin oligodendrocyte glycoprotein (MOG)(35-55)-immunized mice. In light of these findings, we asked whether IFN-gamma was required for the reduced encephalitogenicity of the weak ligand 45D in EAE. In this study, we report that immunization of mice deficient in IFN-gamma or its receptor with 45D exhibit significant EAE signs compared with 45D-immunized wild-type B6 mice. Moreover, 45D-immunized IFN-gamma(-/-) and IFN-gammaR(-/-) mice demonstrate MOG tetramer-positive CD4(+) T cells within the CNS and display substantial numbers of MOG-specific CD4(+) T cells in the periphery. In contrast, wild-type mice immunized with 45D exhibit reduced numbers of MOG-specific CD4(+) T cells in the periphery and lack MOG tetramer- positive CD4(+) T cells in the CNS. Importantly, the increased encephalitogenicity of 45D in mice lacking IFN-gamma or IFN-gammaR was not due to deviation toward an enhanced IL-17-secreting phenotype. These findings demonstrate that IFN-gamma significantly attenuates the encephalitogenicity of 45D and are the first to highlight the importance of IFN-gamma signaling in setting the threshold level of responsiveness of autoreactive CD4(+) T cells to weak ligands.     

Studies of experimental allergic encephalomyelitis by using encephalitogenic T cell lines and clones in euthymic and athymic mice

The role of T-T cell interactions in the clinical course of acute experimental allergic encephalomyelitis (EAE) in mice was investigated. Myelin basic protein (MBP)-reactive and encephalitogenic T cell clones were established from long-term lines derived from susceptible strain SJL/J mice and resistant strain DDD/1 mice. The lines and clones from DDD/1 mice were obtained by immunization of congenitally athymic mice of DDD/1 origin, which had been reconstituted with syngeneic Lyt-2+-depleted splenic T cells. The clones derived from both strains bore surface phenotypes of Lyt-1+, 2- and L3T4+, and proliferated well in response to rat, rabbit, bovine, and guinea pig MBP in the presence of antigen-presenting cells with I-As. Passive EAE could be induced in syngeneic normal recipients by these clones as well as by the lines from which the clones were derived. The clinical features of the clone-induced EAE were essentially the same as those of the line-induced EAE. Furthermore, DDD/1 athymic recipients developed signs of acute EAE by the adoptive transfer of I-A-compatible syngeneic and allogeneic T cell clones, in which there was no significant difference in time of onset, maximum severity, or prognosis. These results indicate that the entire clinical course of acute EAE can be elicited by a single population of MBP-reactive T cells in the absence of the thymus and other populations of primed or unprimed T cells.     

Secondary B Cell Receptor Diversification Is Necessary for T Cell Mediated Neuro-Inflammation during Experimental Autoimmune Encephalomyelitis

Background

Clinical studies of B cell depletion in Multiple Sclerosis (MS) have revealed that B Lymphocytes are involved in the neuro-inflammatory process, yet it remains unclear how B cells can exert pro- and anti-inflammatory functions during MS. Experimental Autoimmune Encephalomyelitis (EAE) is an animal model of MS whereby myelin-specific T cells become activated and subsequently migrate to the Central Nervous System (CNS) where they perform pro-inflammatory functions such as cytokine secretion. Typically EAE is induced by immunization of mice of a susceptible genetic background with peptide antigen emulsified in Complete Freund''s Adjuvant. However, novel roles for B-lymphocytes in EAE may also be explored by immunization with full-length myelin oligodendrocyte glycoprotein (MOG) that contains the B cell conformational epitope. Here we show that full length MOG immunization promotes a chronic disease in mice that depends on antigen-driven secondary diversification of the B cell receptor.

Methods

Activation-Induced Deaminase (AID) is an enzyme that is essential for antigen-driven secondary diversification of the B cell receptor. We immunized AID^−/− mice with the extracellular domain (amino acids 1–120) of recombinant human MOG protein (rhMOG) and examined the incidence and severity of disease in AID^−/− versus wild type mice. Corresponding with these clinical measurements, we also evaluated parameters of T cell activation in the periphery and the CNS as well as the generation of anti-MOG antibodies (Ab).

Conclusions

AID^−/− mice exhibit reduced severity and incidence of EAE. This suggests that the secondary diversification of the B cell receptor is required for B cells to exert their full encephalogenic potential during rhMOG-induced EAE, and possibly also during MS.     

Intrathecal delivery of IFN-gamma protects C57BL/6 mice from chronic-progressive experimental autoimmune encephalomyelitis by increasing apoptosis of central nervous system-infiltrating lymphocytes

The exclusive detrimental role of proinflammatory cytokines in demyelinating diseases of the CNS, such as multiple sclerosis, is controversial. Here we show that the intrathecal delivery of an HSV-1-derived vector engineered with the mouse IFN-gamma gene leads to persistent (up to 4 wk) CNS production of IFN-gamma and inhibits the course of a chronic-progressive form of experimental autoimmune encephalomyelitis (EAE) induced in C57BL/6 mice by myelin oligodendrocyte glycoprotein (MOG)(35-55). Mice treated with the IFN-gamma-containing vector before EAE onset showed an earlier onset but a milder course of the disease compared with control mice treated with the empty vector. In addition, 83% of IFN-gamma-treated mice completely recovered within 25 days post immunization, whereas control mice did not recover up to 60 days post immunization. Mice treated with the IFN-gamma-containing vector within 1 wk after EAE onset partially recovered from the disease within 25 days after vector injection, whereas control mice worsened. Recovery from EAE in mice treated with IFN-gamma was associated with a significant increase of CNS-infiltrating lymphocytes undergoing apoptosis. During the recovery phase, the mRNA level of TNFR1 was also significantly increased in CNS-infiltrating cells from IFN-gamma-treated mice compared with controls. Our results further challenge the exclusive detrimental role of IFN-gamma in the CNS during EAE/multiple sclerosis, and indicate that CNS-confined inflammation may induce protective immunological countermechanisms leading to a faster clearance of encephalitogenic T cells by apoptosis, thus restoring the immune privilege of the CNS.     

IL-12p35-deficient mice are susceptible to experimental autoimmune encephalomyelitis: evidence for redundancy in the IL-12 system in the induction of central nervous system autoimmune demyelination

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

Relapsing murine experimental allergic encephalomyelitis induced by myelin basic protein

Experimental allergic encephalomyelitis (EAE), an experimental autoimmune disease of the central nervous system (CNS), is readily induced in many mammalian species by immunization with CNS tissue or myelin basic protein (MBP) purified from the CNS. EAE has been frequently used as a model for multiple sclerosis (MS). However, EAE generally presents as an acute monophasic disease in the adult animal after immunization with MBP. After recovery, the animal is resistant to rechallenge with encephalitogen (1). Two exceptions to these observations have been reported. McFarlin et al. (2) reported that a variable number of Lewis rats showed signs of a single, mild relapse about a week after recovery from MBP-induced acute EAE. Panitch and Ciccone (3) have reported induction of recurrent EAE in rats immunized with human MBP. Chronic, relapsing EAE has been induced in the mouse; however, an apparent requirement for CNS tissue had been noted (4, 5). Recently, during the course of a series of experiments on the induction of EAE in SJL/J, PL/J, and (SJL/J X PL/J)F1 (SPL F1) mice, it was observed that the F1 mice frequently had paralytic relapses after recovery from MBP-induced symptoms. Experiments were initiated to examine this phenomenon, and the findings are presented below.