Cutting edge: CD4+CD25+ regulatory T cells suppress antigen-specific autoreactive immune responses and central nervous system inflammation during active experimental autoimmune encephalomyelitis

Autoreactive CD4(+) T cells exist in normal individuals and retain the capacity to initiate autoimmune disease. The current study investigates the role of CD4(+)CD25(+) T-regulatory (T(R)) cells during autoimmune disease using the CD4(+) T cell-dependent myelin oligodendrocyte glycoprotein (MOG)-specific experimental autoimmune encephalomyelitis model of multiple sclerosis. In vitro, T(R) cells effectively inhibited both the proliferation of and cytokine production by MOG(35-55)-specific Th1 cells. In vivo, adoptive transfer of T(R) cells conferred significant protection from clinical experimental autoimmune encephalomyelitis which was associated with normal activation of autoreactive Th1 cells, but an increased frequency of MOG(35-55)-specific Th2 cells and decreased CNS infiltration. Lastly, transferred T(R) cells displayed an enhanced ability to traffic to the peripheral lymph nodes and expressed increased levels of the adhesion molecules ICAM-1 and P-selectin that may promote functional interactions with target T cells. Collectively, these findings suggest that T(R) cells contribute notably to the endogenous mechanisms that regulate actively induced autoimmune disease.     

Divergent roles for p55 and p75 tumor necrosis factor receptors in the pathogenesis of MOG(35-55)-induced experimental autoimmune encephalomyelitis

To clarify the role of tumor necrosis factor (TNF) in the inflammatory aspects of autoimmunity vs its potential role in the apoptotic elimination of autoreactive effector cells, we assessed the roles of the p55 (TNFR1/Tnfrsf1a/CD120a) and p75 (TNFR2/Tnfrsf1b/CD120b) TNF receptors in the pathogenesis of MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE). TNFR p55/p75(-/-) double knockout mice were completely resistant to clinical disease. TNFR p55(-/-) single knockout mice were also totally resistant to EAE, exhibiting reduced MOG(35-55)- specific proliferative responses and Th1 cytokine production, despite displaying equivalent DTH responses. Importantly, IL-5 was significantly increased in p55(-/-) mice. In contrast, p75(-/-) knockout mice exhibited exacerbated EAE, enhanced Th1 cytokine production, and enhanced CD4(+) and F4/80(+) CNS infiltration. Thus, p55/TNFR1 is required for the initiation of pathologic disease, whereas p75/TNFR2 may be important in regulating the immune response. These results have important implications for therapies targeting p55 and p75 receptors for treating autoimmune diseases.     

Soluble MOG35-55/I-Ab Dimers Ameliorate Experimental Autoimmune Encephalomyelitis by Reducing Encephalitogenic T Cells

The MOG35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice is a useful animal model to explore therapeutic approaches to T cell-mediated autoimmune diseases because the dominant T-cell epitope(s) have been defined. It is rational that antigen-specific immunosuppression can be induced by using MHC-peptide complexes as specific TCR ligand(s) that interact with autoreactive T cells in the absence of co-stimulation. In this study, a soluble divalent MOG35-55/I-A^b fusion protein (MOG35-55/I-A^b dimer) was constructed to specifically target the autoreactive CD4⁺ T cells in the EAE mouse. Intraperitoneal administration of the MOG35-55/I-A^b dimer significantly delayed and ameliorated EAE symptoms by reducing EAE-related inflammation in the mouse CNS and reducing encephalitogenic Th1 and Th17 cells in the peripheral lymphoid organs. We observed that dimer intervention at a concentration of 1.2 nM suppressed MOG35-55 peptide-specific 2D2 transgenic T cells (2D2 T cells) proliferation by over 90% after in vitro activation with MOG35-55 peptide. The mechanisms involved in this antigen-specific dimer-mediated suppression were found to be downregulated TCR-CD3 expression as well as upregulated expression of membrane-bound TGF-β (mTGF-β) and IL-10 suppressive cytokines by the autoreactive CD4⁺ T cells. Collectively, our data demonstrates that soluble divalent MHC class II molecules can abrogate pathogenic T cells in EAE. Furthermore, our data suggests that this strategy may provide an efficient and clinically useful option to treat autoimmune diseases.     

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.     

CD43 regulates Th2 differentiation and inflammation

CD43 is a highly glycosylated transmembrane protein that regulates T cell activation. CD43(-/-) T cells are hyperproliferative and the cytoplasmic tail of CD43 has been found to be sufficient to reconstitute wild-type proliferation levels, suggesting an intracellular mechanism. In this study, we report that upon TCR ligation CD43(-/-) T cells demonstrated no increase in tyrosine phosphorylation but a decreased calcium flux. Interestingly, CD43(-/-) T cells preferentially differentiated into Th2 cells in vitro, and CD43(-/-) T cells show increased GATA-3 translocation into the nucleus. In vivo, CD43(-/-) mice exhibited increased inflammation in two separate models of Th2-mediated allergic airway disease. In contrast, in Th1-mediated diabetes, nonobese diabetic CD43(-/-) mice did not significantly differ from wild-type mice in disease onset or progression. Th1-induced experimental autoimmune encephalomyelitis to MOG(35-55) was also normal in the CD43(-/-) mice. Nonetheless, the CD43(-/-) mice produced more IL-5 when restimulated with MOG(35-55) in vitro and demonstrated decreased delayed-type hypersensitivity responses. Together, these data demonstrate that although CD43(-/-) T cells preferentially differentiate into Th2 cells, this response is not sufficient to protect against Th1-mediated autoimmune responses.     

CD43 modulates severity and onset of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a mouse model of multiple sclerosis characterized by infiltration of activated CD4(+) T lymphocytes into tissues of the CNS. This study investigated the role of CD43 in the induction and progression of EAE. Results demonstrate that CD43-deficient mice have reduced and delayed clinical and histological disease severity relative to CD43(+/+) mice. This reduction was characterized by decreased CD4(+) T cell infiltration of the CNS of CD43(-/-) mice but similar numbers of Ag-specific T cells in the periphery, suggesting a defect in T cell trafficking to the CNS. The absence of CD43 also affected cytokine production, as myelin oligodendrocyte glycoprotein (MOG) 35-55-specific CD43(-/-) CD4(+) T cells exhibited reduced IFN-gamma and increased IL-4 production. CD43(-/-) CD4(+) MOG-primed T cells exhibited reduced encephalitogenicity relative to CD43(+/+) cells upon adoptive transfer into naive recipients. These results suggest a role for CD43 in the differentiation and migration of MOG(35-55)-specific T cells in EAE, and identify it as a potential target for therapeutic intervention.     

De novo central nervous system processing of myelin antigen is required for the initiation of experimental autoimmune encephalomyelitis

We demonstrate the absolute requirement for a functioning class II-restricted Ag processing pathway in the CNS for the initiation of experimental autoimmune encephalomyelitis (EAE). C57BL/6 (B6) mice deficient for the class II transactivator, which have defects in MHC class II, invariant chain (Ii), and H-2M (DM) expression, are resistant to initiation of myelin oligodendrocyte protein (MOG) peptide, MOG(35-55)-specific EAE by both priming and adoptive transfer of encephalitogenic T cells. However, class II transactivator-deficient mice can prime a suboptimal myelin-specific CD4(+) Th1 response. Further, B6 mice individually deficient for Ii and DM are also resistant to initiation of both active and adoptive EAE. Although both Ii-deficient and DM-deficient APCs can present MOG peptide to CD4(+) T cells, neither is capable of processing and presenting the encephalitogenic peptide of intact MOG protein. This phenotype is not Ag-specific, as DM- and Ii-deficient mice are also resistant to initiation of EAE by proteolipid protein peptide PLP(178-191). Remarkably, DM-deficient mice can prime a potent peripheral Th1 response to MOG(35-55), comparable to the response seen in wild-type mice, yet maintain resistance to EAE initiation. Most striking is the demonstration that T cells from MOG(35-55)-primed DM knockout mice can adoptively transfer EAE to wild-type, but not DM-deficient, mice. Together, these data demonstrate that the inability to process antigenic peptide from intact myelin protein results in resistance to EAE and that de novo processing and presentation of myelin Ags in the CNS is absolutely required for the initiation of autoimmune demyelinating disease.     

IL-18 directs autoreactive T cells and promotes autodestruction in the central nervous system via induction of IFN-gamma by NK cells

IL-18 promotes NK cell and Th1 cell activity and may bridge innate and adaptive immune responses. Myelin oligodendrocyte glycoprotein (MOG) is a myelin component of the CNS and is a candidate autoantigen in multiple sclerosis. In the present study we show that IL-18-deficient (IL-18-/-) mice are defective in mounting autoreactive Th1 and autoantibody responses and are resistant to MOG35-55 peptide-induced autoimmune encephalomyelitis. IL-18 administration enhances the disease severity in wild-type mice and restores the ability to generate Th1 response in the IL-18-/- mice. This restoration was abrogated in NK cell-depleted mice, indicating that the action of IL-18 in promoting the generation of MOG-specific Th cells was dependent on NK cells. Furthermore, transfer of NK cells from recombinase-activating gene 1-/- mice, but not from recombinase-activating gene 1/IFN-gamma-/- mice, rescued the defective Th1 responses in IL-18-/- mice and rendered IL-18-/- mice susceptible to the induction of autoimmune encephalomyelitis. Thus, IL-18 can direct autoreactive T cells and promote autodestruction in the CNS at least in part via induction of IFN-gamma by NK cells.     

A transgenic model of central nervous system autoimmunity mediated by CD4+ and CD8+ T and B cells

Experimental autoimmune encephalomyelitis (EAE) is a widely used model of multiple sclerosis. In NOD mice, EAE develops as a relapsing-remitting disease that transitions to a chronic progressive disease, making the NOD model the only mouse model that recapitulates the full clinical disease course observed in most multiple sclerosis patients. We have generated a TCR transgenic mouse that expresses the α- and β-chains of a myelin oligodendrocyte glycoprotein (MOG) 35-55-reactive TCR (1C6) on the NOD background. 1C6 TCR transgenic mice spontaneously generate both CD4(+) and CD8(+) T cells that recognize MOG and produce proinflammatory cytokines, allowing for the first time to our knowledge the simultaneous examination of myelin-reactive CD4(+) and CD8(+) T cells in the same host. 1C6 CD8(+) T cells alone can induce optic neuritis and mild EAE with delayed onset; however, 1C6 CD4(+) T cells alone induce severe EAE and predominate in driving disease when both cell types are present. When 1C6 mice are crossed with mice bearing an IgH specific for MOG, the mice develop spontaneous EAE with high incidence, but surprisingly the disease pattern does not resemble the neuromyelitis optica-like disease observed in mice bearing CD4(+) T cells and B cells reactive to MOG on the C57BL/6 background. Collectively, our data show that although myelin-reactive CD8(+) T cells contribute to disease, disease is primarily driven by myelin-reactive CD4(+) T cells and that the coexistence of myelin-reactive T and B cells does not necessarily result in a distinct pathological phenotype.     

IL-13-mediated gender difference in susceptibility to autoimmune encephalomyelitis

Females tend to have stronger Th1-mediated immune responses and are more prone to develop autoimmune diseases, including multiple sclerosis. Macrophages are major effector cells capable of mediating or modulating immune responses in experimental autoimmune encephalomyelitis (EAE). IL-13 and estrogen have opposing roles on macrophages (the former enhancing and the latter inhibiting) in terms of MHC class II (MHC II) up-regulation and, thus, these factors might influence susceptibility to EAE differently in females vs males. In accordance with this hypothesis, females lacking IL-13 displayed lower incidence and milder EAE disease severity than males after immunization with myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide/CFA/pertussis toxin. Female IL-13 knockout (KO) mice with EAE consistently had reduced infiltration of CD11b(+) macrophages in the CNS along with significantly reduced expression of MHC II on these cells. Impaired MHC II expression was further corroborated upon LPS stimulation of female but not male bone marrow-derived CD11b(+) macrophages from IL-13KO mice, with restored expression after IL-13 pretreatment of female but not male macrophages. APCs from IL-13KO females induced less proliferation by MOG-35-55-reactive T cells, and splenocytes from MOG peptide-immunized females had lower expression of IL-12, IFN-gamma, MIP-2, and IFN-gamma-inducible protein 10 than males. In contrast, these splenocytes had higher expression of anti-inflammatory factors, IL-10, TGF-beta1, and FoxP3, a cytokine pattern typical of regulatory type II monocytes. These data suggest that the difference in EAE susceptibility in females is strongly influenced by gender-specific proinflammatory effects of IL-13, mediated in part through up-regulation of Th1-inducing cytokines and MHC II on CD11b(+) macrophages.     

Resistance to experimental autoimmune encephalomyelitis and impaired IL-17 production in protein kinase C theta-deficient mice

The protein kinase C theta (PKC theta) serine/threonine kinase has been implicated in signaling of T cell activation, proliferation, and cytokine production. However, the in vivo consequences of ablation of PKC theta on T cell function in inflammatory autoimmune disease have not been thoroughly examined. In this study we used PKC theta-deficient mice to investigate the potential involvement of PKC theta in the development of experimental autoimmune encephalomyelitis, a prototypic T cell-mediated autoimmune disease model of the CNS. We found that PKC theta-/- mice immunized with the myelin oligodendrocyte glycoprotein (MOG) peptide MOG(35-55) were completely resistant to the development of clinical experimental autoimmune encephalomyelitis compared with wild-type control mice. Flow cytometric and histopathological analysis of the CNS revealed profound reduction of both T cell and macrophage infiltration and demyelination. Ex vivo MOG(35-55) stimulation of splenic T lymphocytes from immunized PKC theta-/- mice revealed significantly reduced production of the Th1 cytokine IFN-gamma as well as the T cell effector cytokine IL-17 despite comparable levels of IL-2 and IL-4 and similar cell proliferative responses. Furthermore, IL-17 expression was dramatically reduced in the CNS of PKC theta-/- mice compared with wild-type mice during the disease course. In addition, PKC theta-/- T cells failed to up-regulate LFA-1 expression in response to TCR activation, and LFA-1 expression was also significantly reduced in the spleens of MOG(35-55)-immunized PKC theta-/- mice as well as in in vitro-stimulated CD4+ T cells compared with wild-type mice. These results underscore the importance of PKC theta in the regulation of multiple T cell functions necessary for the development of autoimmune disease.     

MHC variant peptide-mediated anergy of encephalitogenic T cells requires SHP-1

Our lab has demonstrated that encephalitogenic T cells can be effectively anergized by treatment with MHC variant peptides, which are analogues of immunogenic peptides containing an amino acid substitution at an MHC anchor residue. The MHC variant peptide of myelin oligodendrocyte glycoprotein (MOG)(35-55) proves an effective treatment as it does not induce symptoms of experimental autoimmune encephalomyelitis and fails to recruit macrophages or MOG(35-55)-specific T cells to the CNS. In this study, we sought to characterize the signaling pathways required for the induction of anergy by building upon the observations identifying the tyrosine phosphatase SHP-1 as a critical regulator of T cell responsiveness. Motheaten viable heterozygous mice, which contain a mutation in the SHP-1 gene resulting in a reduction in functional SHP-1, were challenged with MOG(35-55) or the MOG(35-55) MHC variant 45D. These mice display symptoms of experimental autoimmune encephalomyelitis upon immunization with MHC variant peptide and have significant CNS infiltration of tetramer-positive CD4(+) cells and macrophages, unlike B6 mice challenged with the variant peptide. The effects of SHP-1 are directly on the T cell as Motheaten viable heterozygous mice autoreactive T cells are not anergized in vitro. Lastly, we demonstrate no distinguishable difference in the initial interaction between the TCR and agonist or MHC variant. Rather, an unstable interaction between peptide and MHC attenuates the T cell response, seen in a decreased half-life relative to MOG(35-55). These results identify SHP-1 as a mediator of T cell anergy induced by destabilized peptide:MHC complexes.     

Resistance to myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis by death receptor 6-deficient mice

Genetic disruption of death receptor 6 (DR6) results in enhanced CD4+ T cell expansion, Th2 differentiation, and humoral responses after stimulation. However, the in vivo consequences of DR6 targeting (DR6-/-) during the initiation and progression of inflammatory autoimmune disease are unclear. Using a myelin oligodendrocyte glycoprotein (MOG(35-55))-induced model of experimental autoimmune encephalomyelitis, DR6-/- mice were found to be highly resistant to both the onset and the progression of CNS disease compared with wild-type (WT) littermates. DR6-/- mice exhibited fewer inflammatory foci along with minimal demyelination and perivascular cuffing of inflammatory cells. Consistent with these observations, mononuclear cell infiltration, including CD4+ T cells and macrophages, in the spinal cord of DR6-/- mice was dramatically reduced. Furthermore, CD4+ T cells from DR6-/- mice exhibited profoundly reduced cell surface expression of VLA-4 before and after stimulation. Compared with WT mice, DR6-/- mice exhibited significantly increased autoantigen-induced T cell proliferative responses along with greater numbers of IL-4-producing and similar or slightly higher numbers of IFN-gamma-producing CD4+ T cells. DR6-/- CD4+ T cells secreted higher levels of the Th2 cytokine, IL-4, and similar levels of the Th1 cytokine, IFN-gamma, compared with WT cells. Taken together, our data demonstrate that DR6 plays an important role in regulating leukocyte infiltration and function in the induction and progression of experimental autoimmune encephalomyelitis.     

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.     

Cutting edge: the silent chemokine receptor D6 is required for generating T cell responses that mediate experimental autoimmune encephalomyelitis

D6, a promiscuous nonsignaling chemokine binding molecule expressed on the lymphatic endothelium, internalizes and degrades CC chemokines, and D6(-/-) mice demonstrated increased cutaneous inflammation following topical phorbol ester or CFA injection. We report that D6(-/-) mice were unexpectedly resistant to the induction of experimental autoimmune encephalomyelitis due to impaired encephalitogenic responses. Following induction with myelin oligodendroglial glycoprotein (MOG) peptide 35-55 in CFA, D6(-/-) mice showed reduced spinal cord inflammation and demyelination with lower incidence and severity of experimental autoimmune encephalomyelitis attacks as compared with D6(+/+) littermates. In adoptive transfer studies, MOG-primed D6(+/-) T cells equally mediated disease in D6(+/+) or D6(-/-) mice, whereas cells from D6(-/-) mice transferred disease poorly to D6(+/-) recipients. Lymph node cells from MOG-primed D6(-/-) mice showed weak proliferative responses and made reduced IFN-gamma but normal IL-5. CD11c(+) dendritic cells accumulated abnormally in cutaneous immunization sites of D6(-/-) mice. Surprisingly, D6, a "silent" chemokine receptor, supports immune response generation.     

Quetiapine, an Atypical Antipsychotic, Is Protective against Autoimmune-Mediated Demyelination by Inhibiting Effector T Cell Proliferation

Quetiapine (Que), a commonly used atypical antipsychotic drug (APD), can prevent myelin from breakdown without immune attack. Multiple sclerosisis (MS), an autoimmune reactive inflammation demyelinating disease, is triggered by activated myelin-specific T lymphocytes (T cells). In this study, we investigated the potential efficacy of Que as an immune-modulating therapeutic agent for experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. Que treatment was initiated on the onset of MOG(35-55) peptide induced EAE mice and the efficacy of Que on modulating the immune response was determined by Flow Cytometry through analyzing CD4(+)/CD8(+) populations and the proliferation of effector T cells (CD4(+)CD25(-)) in peripheral immune organs. Our results show that Que dramatically attenuates the severity of EAE symptoms. Que treatment decreases the extent of CD4(+)/CD8(+) T cell infiltration into the spinal cord and suppresses local glial activation, thereby diminishing the loss of mature oligodendrocytes and myelin breakdown in the spinal cord of EAE mice. Our results further demonstrate that Que treatment decreases the CD4(+)/CD8(+) T cell populations in lymph nodes and spleens of EAE mice and inhibits either MOG(35-55) or anti-CD3 induced proliferation as well as IL-2 production of effector T cells (CD4(+)CD25(-)) isolated from EAE mice spleen. Together, these findings suggest that Que displays an immune-modulating role during the course of EAE, and thus may be a promising candidate for treatment of MS.     

SAP suppresses the development of experimental autoimmune encephalomyelitis in C57BL/6 mice

Experimental autoimmune encephalomyelitis (EAE) is a CD4(+) T cell-mediated disease of the central nervous system. Serum amyloid P component (SAP) is a highly conserved plasma protein named for its universal presence in amyloid deposits. Here we report that SAP-transgenic mice had unexpectedly attenuated EAE due to impaired encephalitogenic responses. Following induction with myelin oligodendroglial glycoprotein (MOG) peptide 35-55 in complete Freund's adjuvant, SAP-transgenic mice showed reduced spinal cord inflammation with lower severity of EAE attacks as compared with control C57BL/6 mice. However, in SAP-Knockout mice, the severity of EAE is enhanced. Adoptive transfer of Ag-restimulated T cells from wild type to SAP-transgenic mice, or transfer of SAP-transgenic Ag-restimulated T cells to control mice, induced milder EAE. T cells from MOG-primed SAP-transgenic mice showed weak proliferative responses. Furthermore, in SAP-transgenic mice, there is little infiltration of CD45-positive cells in the spinal cord. In vitro, SAP suppressed the secretion of interleukin-2 stimulated by P-selectin and blocked P-selectin binding to T cells. Moreover, SAP could change the affinity between α4-integrin and T cells. These data suggested that SAP could antagonize the development of the acute phase of inflammation accompanying EAE by modulating the function of P-selectin.     

Role for MyD88, TLR2 and TLR9 but not TLR1, TLR4 or TLR6 in experimental autoimmune encephalomyelitis

The potential roles of TLRs in the cause and pathogenesis of autoimmune CNS inflammation remain contentious. In this study, we examined the effects of targeted deletions of TLR1, TLR2, TLR4, TLR6, TLR9, and MyD88 on the induction of myelin oligodendrocyte glycoprotein 35-55 (MOG(35-55)) peptide/CFA/pertussis toxin-induced autoimmune encephalomyelitis. Although C57BL/6.Tlr1(-/-), C57BL/6.Tlr4(-/-) and C57BL/6.Tlr6(-/-) mice showed normal susceptibility to disease, signs were alleviated in female C57BL/6.Tlr2(-/-) and C57BL/6.Tlr9(-/-) mice and C57BL/6.Tlr2/9(-/-) mice of both sexes. C57BL/6.Myd88(-/-) mice were completely protected. Lower clinical scores were associated with reduced leukocyte infiltrates. These results were confirmed by passive adoptive transfer of disease into female C57BL/6.Tlr2(-/-) and C57BL/6.Tlr9(-/-) mice, where protection in the absence of TLR2 was associated with fewer infiltrating CD4(+) cells in the CNS, reduced prevalence of detectable circulating IL-6, and increased proportions of central (CD62L(+)) CD4(+)CD25(+)Foxp3(+) regulatory T cells. These results provide a potential molecular mechanism for the observed effects of TLR signaling on the severity of autoimmune CNS inflammation.