Protective effect of a synapsin peptide genetically fused to the B subunit of Escherichia coli heat‐labile enterotoxin in rat autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease with similarities to multiple sclerosis that requires the activation of auto reactive T cells that infiltrate the central nervous system. In previous studies we have shown that intraperitoneal administration of synaptosomal antigens could suppress EAE. Herein we examined the effect in this animal model of a fusion protein comprising the C domain of synapsin Ia and the B subunit of Escherichia coli heat‐labile enterotoxin (LTBSC). Oral administration to rats of low amounts of LTBSC induced immunological systemic tolerance to the encephalitogenic myelin basic protein. Treatment with LTBSC prior to EAE induction diminished disease incidence, DTH reaction to myelin basic protein, and central nervous system inflammation. LTBSC treatment also reduced the specific T‐cell proliferative response to myelin basic protein, decreased nitric oxide production, and augmented arginase activity by peritoneal macrophages. All animals challenged for EAE developed antibody response specific for myelin basic protein, but rats treated with LTBSC showed a lower IgG2b/IgG1 ratio, indicating a shift to a Th2‐type milieu. The data presented here suggest that well‐conserved synapsin peptides conjugated to the B subunit of enterotoxins from the cholera toxin family have a protective role and provide a potential therapeutic tool for intervention in EAE as well as in multiple sclerosis. © 2009 Wiley‐Liss, Inc.     

Antigen therapy of experimental autoimmune encephalomyelitis selectively induces apoptosis of pathogenic T cells

Administration of high-dose myelin antigen induces massive T cell apoptosis in experimental autoimmune encephalomyelitis (EAE) but the nature of the target cells remains elusive. Here we have used a cell line established in eGFP-transgenic Lewis rats to distinguish between pathogenic and bystander T cells in adoptive transfer EAE. Intravenous application of gpMBP strongly reduced the amount of encephalitogenic cells in spinal cord and spleen while the number of the other T cells remained constant. This could be attributed to their differential sensitivity to apoptosis. Thus, antigen therapy selectively targets pathogenic T cells and should therefore limit potential adverse effects.     

Estrogen treatment induces a novel population of regulatory cells, which suppresses experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a debilitating neurological disease characterized by a progressive loss of motor and sensory function, eventually leading to paralysis and death. The primary cause of neurological impairment is demyelination of the central nervous system (CNS) caused by an inflammatory autoimmune response. Previous studies have shown that the severity of MS is reduced during pregnancy, suggesting that the increased level of sex hormones may reduce the autoimmune response. Recently, we have shown that estrogen treatment confers protection from experimental autoimmune encephalomyelitis (EAE), which is an animal model for MS. However, the cellular basis of estrogen's action remains unknown. In the current study, we demonstrate that estrogen treatment led to the induction of a novel subpopulation of regulatory cells in spleen and CNS, which also occurs naturally in pregnant mice. These previously uncharacterized cells display a low level expression of CD45 (CD45(dim)) and no detectable expression of many cell surface markers related to TCR signaling, including CD3 and TCR. However, these cells retained expression of VLA-4, an extracellular protein involved in cellular migration. Several lines of evidence suggest that these novel cells, defined as CD45(dim)VLA-4(+) cells, may play a role in the protective effects of estrogen in EAE. Injection of purified CD45(dim)VLA-4(+) cells conferred protection from spontaneous EAE (Sp-EAE). In contrast, injection of CD45(high)VLA-4(+) cells exacerbated the disease course. CD45(dim)VLA-4(+) cells also suppressed antigen-specific proliferation of primed lymphocytes in coculture. A better understanding of how CD45(dim)VLA-4(+) cells suppress the harmful immune response of EAE may help in explaining the induction of immune tolerance during pregnancy and lead to novel therapeutic approaches to combat MS and other autoimmune diseases.     

Studies of V beta 8 T cell receptor peptide treatment in experimental autoimmune encephalomyelitis.

Lewis rats immunized with T cell receptor (TCR) variable region peptide V beta 8 in complete Freund's adjuvant (CFA) were protected against experimental autoimmune encephalomyelitis (EAE) induced with myelin basic protein in CFA, although variable protection was also observed in rats injected with control peptide in CFA, or CFA alone. However, this adjuvant-mediated protection could be avoided by immunizing with TCR peptide in incomplete adjuvant (IFA). Clinical, but not histologic EAE was suppressed in rats given V beta 8 peptide in IFA, whereas control animals injected with V beta 14 peptide in IFA, or IFA alone developed severe clinical EAE. Anti-V beta 8 antibodies were present in the sera of all V beta 8-treated rats. These findings lend support to the hypothesis that autoimmune disease can be suppressed by inducing an immune response against the TCR-idiotope of autoreactive T cells.     

Down‐modulation of programmed death 1 alters regulatory T cells and promotes experimental autoimmune encephalomyelitis

The regulatory role of programmed death 1 (PD‐1) was investigated in the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Typical EAE could be induced by immunization without pertussis toxin (PTX) in PD‐1‐null but not in wild‐type (WT) mice. However, both strains developed a similar EAE phenotype when immunized with PTX or by adoptive transfer of pathogenic T cells. In WT mice that did not develop EAE after immunization without PTX, the frequency of CD4⁺FoxP3⁺ Treg cells was boosted in the periphery but not in the thymus. This increase in Treg frequency was abrogated by PD‐1 deficiency or inclusion of PTX. In addition, PD‐1 expression was critical to in vitro conversion of naïve myelin‐specific CD4 T cells into Treg cells and was directly related to Treg suppressive activity. Finally, PD‐1 was markedly down‐modulated in the periphery of WT mice after administration of PTX. Therefore, down‐modulation of PD‐1 in Treg cells may abrogate Treg‐mediated immune suppression, permitting the activation of myelin‐reactive T cells and induction of EAE. © 2009 Wiley‐Liss, Inc.     

Protection against experimental autoimmune encephalomyelitis requires both CD4 T suppressor cells and myelin basic protein-primed B cells

Suppressor cells that regulate experimental autoimmune encephalomyelitis (EAE) are present in rats that recover from the disease and can protect against the development of active EAE when transferred to normal recipients. Both CD4+ T suppressor cells, known to regulate EAE effector cell lymphokine production, and myelin basic protein (MBP)-primed B cells are required to transfer protection against EAE to normal recipients. Neither CD4+ T suppressor cells nor MBP-primed B cells alone could transfer protection. Moreover, the co-transfer of normal B cells with CD4+ T suppressor cells did not provide protection against EAE. These results suggest that the regulation of EAE and perhaps the recovery from acute clinical disease requires the interaction of two specific subpopulations of regulatory lymphocytes.     

马索罗酚对实验性自身免疫性脑脊髓炎小鼠Th1/Th2细胞炎症因子平衡的影响

目的探讨马索罗酚对实验性自身免疫性脑脊髓炎(EAE)小鼠白细胞介素-4(IL-4)、IL-12、干扰素-γ(IFN-γ)表达的调节作用。方法将8~10周雌性C57BL/6小鼠54只随机分成对照组、模型组、治疗组。每组再随机均分为发病后10d及20d亚组,每亚组9只。采用皮下注射髓鞘少突胶质细胞糖蛋白35-55(MOG35-55)多肽0.1mL诱导EAE模型。自发病当天起,治疗组小鼠给予马索罗酚10mg/(kg·d)治疗,模型组及对照组给予等量5%二甲基亚砜(DMSO)10mL/(kg·d)处理。比较3组小鼠临床症状评分。应用实时定量PCR检测小鼠脊髓和脾组织中IL-4、IL-12、IFN-γmRNA表达水平。应用ELISA检测脑组织中IL-4、IL-12、IFN-γ蛋白表达水平。结果与模型组比较,治疗组小鼠临床症状较减轻(P0.05)。与模型组相比,治疗组小鼠10d时脊髓和脾组织IL-12、IFN-γmRNA表达水平降低(P0.05),IL-4mRNA水平增高(P0.05),脑组织IL-12、IFN-γ蛋白水平降低(P0.05),IL-4蛋白水平增高(P0.05);与模型组相比,治疗组20d时脊髓组织IL-12、IFN-γmRNA表达水平降低(P0.05),脑组织IFN-γ含量降低(P0.05)。结论马索罗酚可能通过降低脑、脊髓及脾组织中IL-12、IFN-γ表达,增加IL-4表达,调节Th1/Th2细胞炎症因子平衡,进而改善EAE小鼠疾病严重程度。     

A case for regulatory B cells in controlling the severity of autoimmune-mediated inflammation in experimental autoimmune encephalomyelitis and multiple sclerosis

Autoimmune uveitis is an inflammatory disorder of the eye that can lead to pain and vision loss. Steroids and immunosuppressive drugs are currently the only therapeutics for uveitis and have serious ocular and systemic toxicities. Therefore, safer alternative therapeutics are desired. Alpha-melanocyte stimulating hormone (α-MSH) is a neuropeptide that suppresses effector T cell functions, induces regulatory T cells and has beneficial effects in certain autoimmune and transplant models. A novel d-amino acid peptide analog of native α-MSH (dRI-α-MSH) was produced that was protected from protease digestion and had increased selectivity for the melanocortin-1 receptor. Systemic delivery of the dRI-α-MSH analog dramatically suppressed disease progression and retained retinal architecture in the experimental autoimmune uveitis (EAU) model. Local delivery by periorbital injection was equally effective. Importantly, treatment with the novel dRI-α-MSH analog suppressed uveitis with a similar magnitude to the corticosteroid, dexamethasone. Data indicate that the novel dRI-α-MSH analogs show anti-inflammatory activities and have potential therapeutic use in uveitis and other autoimmune diseases.     

Laquinimod modulates B cells and their regulatory effects on T cells in Multiple Sclerosis

Laquinimod is an orally administered drug under development for the treatment of Multiple Sclerosis (MS), lacking a fully elucidated mode of action. We assessed the immunomodulatory effects of laquinimod in vitro on human B cells from healthy or MS patients, cultured alone or with CD4(+) T cells. Laquinimod modulated B cell markers, mainly by increasing the regulatory ones CD25, IL10 and CD86, and decreased IL4, while increasing IL10 and TGFβ in both B and T cells, in a B cell-mediated manner. These findings shed additional light on the mechanisms underlying the effects of laquinimod in MS and potentially other immune-mediated diseases.     

Sulfasalazine aggravates experimental autoimmune encephalomyelitis and causes an increase in the number of autoreactive T cells.

Sulfasalazine (SASP; 5-(p-(2-pyridylsulfamoyl)phenylazo)salicyclic acid) has beneficial effects on certain inflammatory diseases and has been proposed for clinical trials in multiple sclerosis (MS). We have explored the effects of SASP on actively induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats. SASP was given orally at three different doses from the day of immunization to day 40 post-immunization (p.i.). All doses led to a clinically more protracted disease, increased numbers of T cells infiltrating into the central nervous system (CNS) and to increased numbers of interferon-gamma-secreting cells (IFN-gamma-sc) in the CNS. The effects of SASP treatment on T cell-mediated autoimmunity against CNS myelin and peptides of myelin basic protein (MBP) were measured by IFN-gamma secretion and proliferation by lymph node mononuclear cells in response to these antigens. In SASP-treated rats, increased numbers of IFN-gamma-sc appeared in response to myelin antigens, while the proliferative responses were decreased. We suggest that monitoring cell-mediated immunity with the IFN-gamma-sc method may be relevant for the evaluation of new immunotherapeutic strategies in inflammatory demyelinating diseases. Furthermore, our results demand caution as to clinical trials with SASP in MS.     

托法替尼对实验性自身免疫性脑脊髓炎大鼠滤泡调节性T细胞/滤泡辅助性T细胞平衡及CXCL13、转化生长因子-β1表达的影响

目的探讨托法替尼对实验性自身免疫性脑脊髓炎(EAE)大鼠滤泡调节性T细胞(Tfr)/滤泡辅助性T细胞(Tfh)平衡及CXCL13、转化生长因子-β1(TGF-β1)表达的影响。方法选择50只Wistar雌性大鼠,随机分为正常对照组、EAE对照组、托法替尼小、中、大剂量防治组,每组10只。采用髓鞘碱性蛋白及完全弗氏佐剂制造EAE模型。从造模前3 d开始EAE对照组及小、中、大剂量托法替尼防治组分别予以生理盐水和托法替尼1、2、4 mg/kg/d灌胃,连续10 d。观测大鼠发病情况、脾组织中Tfh和Tfr比例、Tfr/Tfh比值变化、脑组织匀浆中CXCL13、TGF-β1含量变化。结果EAE对照组大鼠发病潜伏期(10.20±1.99)d,托法替尼小、中、大剂量防治组发病潜伏期分别为(16.70±1.50)d、(20.20±2.44)d和(22.90±1.79)d,托法替尼各防治组发病潜伏期均较EAE对照组延长(P0.01)。EAE对照组大鼠进展期(10.50±1.84)d,托法替尼小、中、大剂量防治组发病进展期分别为(8.00±2.00)d、(5.60±1.51)d和(3.00±1.16)d,托法替尼各防治组发病进展期均较EAE对照组缩短(P0.01)。EAE对照组大鼠发病高峰期神经功能障碍评分(3.80±1.03)分,托法替尼小、中、大剂量防治组发病高峰期神经功能障碍评分分别为(2.30±1.34)分、(1.20±1.40)分和(0.60±0.84)分,托法替尼各防治组发病高峰期神经功能障碍评分均较EAE对照组降低(P0.01)。托法替尼各防治组与EAE对照组比较,Tfh细胞比例显著降低,Tfr细胞比例及Tfr/Tfh比值显著升高,CXCL13含量明显减少、TGF-β1含量明显增加,且呈剂量依赖关系,剂量越大作用越明显(P0.01;P0.05)。结论托法替尼对EAE大鼠发病具有防治作用,且呈剂量依赖关系。其防治作用机制可能与下调EAE大鼠Tfh比例及CXCL-13的表达,上调Tfr比例及TGF-1的表达,维持Tfr/Tfh平衡,并促使平衡向Tfr偏移有关。     

NOS2 regulates cytokine production and VLA-4 expression in experimental autoimmune encephalomyelitis

Inducible nitric oxide synthase (NOS2) expression in the central nervous system correlates with EAE disease activity. Inhibition of NOS2 ameliorates adoptively transferred EAE, yet exacerbates actively induced EAE. Herein, the encephalitogenicity of T cells induced by immunization in the presence or absence of NOS2 was examined. Upon passive transfer, T cells from myelin oligodendrocyte glycoprotein-immunized NOS2-deficient C57BL/6 mice induced more severe EAE than T cells from wild-type mice. The heightened encephalitogenicity of NOS2-/- T cells correlated with enhanced expression of VLA-4 (CD49d) and increased production of interferon gamma and tumor necrosis factor. NO plays an important regulatory role in autoimmune T cell induction.     

The dynamics of effector T cells and Foxp3+ regulatory T cells in the promotion and regulation of autoimmune encephalomyelitis

The Th1/Th2 paradigm of T helper cell subsets had to be revised when IL-17 producing T cells (Th17) were identified as a distinct T helper cell lineage. Th17 cells are very efficient inducers of tissue inflammation and crucial initiators of organ-specific autoimmunity. Whereas Th17 cells promote autoimmune tissue inflammation, Foxp3+ regulatory T cells (T-reg) are necessary and sufficient to prevent autoimmunity throughout the life span of an individual. Here, we review recent findings of how responses of effector T cells and T-reg cells with a defined antigen-specificity develop in autoimmune encephalomyelitis. Moreover, Th17 cells and Foxp3+ T-reg seem to be dichotomously related in that TGF-beta induces Foxp3 in na?ve T cells, but TGF-beta and IL-6 together drive the generation of Th17 cells. Thus, we give an overview of how Th17 cells, induced Foxp3+ T-reg, as well as how naturally occurring T-reg cells might cooperate to promote and regulate autoimmune inflammation of the central nervous system (CNS). The monitoring of the population dynamics of these T cell subsets in reporter mice in vivo will enable us to revisit the pathogenic concept of autoimmune inflammation in the CNS and design rational and phase-specific therapeutic interventions.     

Therapeutic effect of ghrelin in experimental autoimmune encephalomyelitis by inhibiting antigen-specific Th1/Th17 responses and inducing regulatory T cells

Ghrelin is an important gastrointestinal hormone that regulates feeding and metabolism. Moreover, ghrelin is produced by immune cells and shows potent anti-inflammatory activities. Here, we investigated its effect in two models of experimental autoimmune encephalomyelitis (EAE) that mirror chronic and relapsing-remitting multiple sclerosis. A short systemic treatment with ghrelin after the disease onset reduced clinical severity and incidence of both forms of EAE, which was associated with a decrease in inflammatory infiltrates in spinal cord and in the subsequent demyelination. This therapeutic effect was exerted through the reduction of the autoimmune and inflammatory components of the disease. Ghrelin decreased the presence/activation of encephalitogenic Th1 and Th17 cells in periphery and nervous system, down-regulated various inflammatory mediators, and induced regulatory T cells. In summary, our findings provide a powerful rationale for the assessment of the efficacy of ghrelin as a novel therapeutic approach for treating multiple sclerosis through distinct immunomodulatory mechanisms and further support the concept that the neuroendocrine and immune systems crosstalk to finely tune the final immune response of our body.     

Synergy between encephalitogenic T cells and myelin basic protein-specific antibodies in the induction of experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an experimentally induced demyelinating disease mediated by CD4+ T cells specific for various myelin proteins including myelin basic protein (MBP) and myelin proteolipid protein (PLP). Although myelin- and other CNS-specific antibodies are produced in EAE, B cells and antibodies are thought by most not to play a decisive role in the induction of EAE. In this report we show that B cells serve as the major antigen-presenting cells (APC) during the T cell activation stage in lymph nodes, and that MBP-specific antibodies can greatly enhance the induction of EAE. The role of B cells as APC is demonstrated in B cell-depleted mice. EAE cannot be induced by antigen/complete Freund's adjuvant immunization unless these mice are locally reconstituted with B cells prior to immunization. The enhancing effect of antibodies is demonstrated in experiments in which EAE is induced by the adoptive transfer of encephalitogenic T cells. The adoptive transfer of large numbers of encephalitogenic T cells induces EAE in 90% of normal recipient mice, but only 33% of B cell-depleted mice get EAE at the same cell dose. The efficiency of EAE induction in B cell-depleted mice can be enhanced if MBP-specific antibodies are simultaneously administered. A similar enhancement is also seen in normal mice when the number of adoptively transferred T cells is limiting. We propose that MBP-specific antibodies enhance the presentation of myelin-derived antigens by APC in the CNS to the adoptively transferred encephalitogenic T cells.     

调节性T细胞在实验性变态反应性脑脊髓炎和多发性硬化发病中的作用

调节性T细胞(regulatory T cells,Treg)是一类具有免疫调节功能的T细胞哑群.近年来,Treg细胞在实验性变态反应性脑脊髓炎(experimental allergical encephalomyelitis,EAE)、多发性硬化(multiple sclerosis,MS)发病中的作用越来越受到关注,小鼠Treg细胞缺失可导致特异性自身免疫性疾病,增加Treg细胞的功能可以减轻或抑制EAE.最近的研究结果表明,MS本身也伴随着成熟Treg细胞的受损或功能障碍.     

Sulfasalizine aggravates experimental autoimmune encephalomyelitis and causes an increase in the number of autoreactive T cells

Sulfasalazine (SASP; 5-(p-(2-pyridylsulfamoyl)phenylazo)salicylic acid) has beneficial effects on certain inflammatory diseases and has been proposed for clinical trials in multiple sclerosis (MS). We have explored the effects of SASP on actively induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats. SASP was given orally at three different doses from the day of immunization to day 40 post-immunization (p.i.). All doses led to a clinically more protracted disease, increased numbers of T cells infiltrating into the central nervous system (CNS) and to increased numbers of interferon-γ-secreting cells (IFN-γ-sc) in the CNS. The effects of SASP treatment on T cell-mediated autoimmunity against CNS myelin and peptides of myelin basic protein (MBP) were measured by IFN-γ secretion and proliferation by lymph node mononuclear cells in response to these antigens. In SASP-treated rats, increased numbers of IFN-γ-sc appeared in response to myelin antigens, while the proliferative responses were decreased. We suggest that monitoring cell-mediated immunity with the IFN-γ-sc method may be relevant for the evaluation of new immunotherapeutic strategies in flammatory demyelinating diseases. Furthermore, our results demand caution as to clinical trials with SASP in MS.     

Rat RT1.B-transfected fibroblast lines process and present myelin antigens and activate T cells to induce experimental autoimmune encephalomyelitis

The genes encoding the Lewis rat RT1.B molecule (MHC Class II I-A equivalent) were transfected and expressed in mouse DAP.3 fibroblast cells together with the gene encoding the mouse ICAM-1 molecule. Both molecules were stably expressed on the cell surface of DAP.3 cells under longterm culture conditions. The RT1.B/mICAM-1 transfectants presented antigen in a specific manner to a RT1. B-restricted rat T cell hybridoma specific for the 69-89 peptide of myelin basic protein (BP). In addition, the transfectants were able to present antigen to a BP69-89-specific rat T cell line. Presentation to a RT1.D (MHC Class II I-E equivalent)-restricted BP87-99-specific T cell line was minimal. Production of the Th1 cytokine IFN-gamma by BP69-89-specific T cells when stimulated by RT1.B/mICAM-1 transfectants correlated very well with proliferation to specific antigen. Moreover, RT1.B-transfected DAP.3 cells sufficiently stimulated BP69-89-specific T cells such that they were able to transfer experimental autoimmune encephalomyelitis (EAE) to Lewis rat recipients. Thus, the RT1.B molecule is functionally expressed on the surface of transfected Dap.3 fibroblasts and is capable of MHC Class II-restricted, antigen-specific presentation to rat T cells.