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

描述（由申请人提供）：脑内接种泰勒氏小鼠脑脊髓炎病毒（TMEV）可导致易感小鼠慢性炎症性脱髓鞘，导致临床症状。鉴于潜在的病毒病因以及免疫介导的慢性脱髓鞘病理和进展的相似性，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。该领域先前的研究主要基于CD4+ T细胞对外周TMEV衣壳表位的反应。我们最近的研究重点是分析耐药和易感小鼠在tmev感染过程中浸润中枢神经系统的T细胞。令人惊讶的是，在易感的SJL小鼠中，CNS浸润的CD4+ T细胞对衣壳表位有反应的不到5%，而在耐药的C57BL/6小鼠中，这一比例为45%。目前尚不清楚CNS中其余CD4+ T细胞的类型、性质和反应性。我们的初步研究表明，在病毒感染的易感SJL小鼠中，主要的cns浸润CD4+ T细胞识别驻留在病毒RNA聚合酶（3D）上的非衣壳表位。此外，我们还成功培育了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TCR转基因小鼠。因此，进一步评估易感SJL小鼠中Th细胞的反应性对了解脱髓鞘的潜在致病机制非常重要，这些研究现在是可行的。我们推测，在病毒感染后，中枢神经系统中特异性非衣壳病毒抗原的T细胞可能在保护或发病中起关键作用。拟开展研究的具体目的包括：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) tmev感染过程中非衣壳病毒表位反应性T细胞浸润中枢神经系统的特异性和性质鉴定；3)评估TMEV衣壳特异性和非衣壳特异性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为病毒诱导的免疫介导脱髓鞘的潜在控制和致病机制提供重要信息，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.