Role of CNS CD4+ T cells in TMEV-induced Demyelination

描述(申请人提供)：脑内接种泰勒氏小鼠脑脊髓炎病毒(TMEV)导致慢性炎症性脱髓鞘，导致易感小鼠出现临床症状。鉴于潜在的病毒病原学和免疫介导的病理以及慢性脱髓鞘进展的相似性，该TMEV系统被认为是研究人类多发性硬化症(MS)的最佳动物模型之一。该领域以前的研究在很大程度上是基于外周的CD4+T细胞对TMEV衣壳表位的反应。我们最近致力于分析耐药和易感小鼠在TMEV感染过程中T细胞渗入中枢神经系统的情况。令人惊讶的是，在易感的SJL小鼠中，5%的中枢神经系统渗透的CD4+T细胞对衣壳表位有反应，而在耐药的C57BL/6小鼠中，这一比例为45%。目前，中枢神经系统中剩余的CD4+T细胞的类型、性质和反应性尚不清楚。我们的初步研究表明，在病毒感染敏感的SJL小鼠中，主要的中枢神经系统渗透的CD4+T细胞识别存在于病毒RNA聚合酶(3D)上的非衣壳表位。此外，我们还成功地产生了I-AS-四聚体、携带病毒衣壳蛋白基因的转基因小鼠和表达TMEV衣壳特异性TCR的转基因小鼠。因此，进一步评估易感SJL小鼠Th细胞的反应性对于了解脱髓鞘的潜在致病机制将是非常重要的，这些研究现在是可行的。我们推测，在病毒感染后，中枢神经系统中针对非衣壳病毒抗原的T细胞可能在保护或致病中发挥关键作用。拟议研究的具体目标包括：1)确定CNS和外周衣壳特异性CD4+T细胞的水平、扩增和性质，包括激活状态和效应功能；2)鉴定TMEV感染期间非衣壳病毒表位反应性T细胞渗入中枢系统的特异性和性质；3)评估TMEV衣壳和非衣壳特异性T细胞在脱髓鞘发病机制中的作用。我们相信，我们的研究将对病毒诱导的免疫介导的脱髓鞘的潜在控制和致病机制(S)提供重要的信息，这是研究人类MS的相关病毒模型。

DESCRIPTION (provided by applicant): Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) results in chronic inflammatory demyelination leading to clinical symptoms in susceptible mice. In light of the potential viral etiology and similarities in the immune-mediated pathology and progression of chronic demyelination, this TMEV system is considered to be one of the best animal models for studying human multiple sclerosis (MS). The previous studies in the field are heavily based on CD4+ T cell responses to TMEV capsid epitopes in the periphery. We have recently focused our efforts on analysis of T cells infiltrating the CNS during the course of TMEV-infection in resistant and susceptible mice. Surprisingly, <5% of the CNS infiltrating CD4+ T cells are reactive to the capsid epitopes in susceptible SJL mice, compared to >45% in resistant C57BL/6 mice. The type, nature and reactivity of the remainder of CD4+ T cells in the CNS are unclear at this time. Our preliminary studies suggest that major CNS-infiltrating CD4+ T cells in virus infected susceptible SJL mice recognize non-capsid epitopes residing on viral RNA polymerase (3D). In addition, we have successfully generated I-AS-tetramers, transgenic mice carrying viral capsid protein genes and TCR transgenic mice expressing TMEV capsid-specific TCRs. Thus, further assessment of the reactivity of the Th cells in susceptible SJL mice will be very important in understanding the potential pathogenic mechanisms of demyelination and these studies are now feasible. We hypothesize that T cells in the CNS specific for non-capsid viral antigens following viral infection may play a critical role in protection or pathogenesis. The specific aims for the proposed studies include: 1) Determination of the level, expansion and nature of capsid-specific CD4+ T cells in the CNS and periphery, including activation states and effector functions; 2) Identification of the specificity and nature of non-capsid viral epitope-reactive T cells infiltrating the CNS during TMEV-infection; 3) Assessment of the role of TMEV capsid- and noncapsid-specific T cells in the pathogenesis of demyelination. We believe that our proposed studies will yield important information on the potential control and pathogenic mechanism(s) against virus-induced immune-mediated demyelination, which is a relevant virus model for studying human MS.