T reg Cells in Myocarditis

描述(由申请人提供)：心肌炎是一种心肌炎，通常伴随着微生物感染。肠道病毒(微小核糖核酸病毒)和腺病毒最常与临床疾病有关。然而，这两种病毒都非常常见，并不是每个经历肠道病毒/腺病毒感染的人都会患上心肌炎。宿主因素和病毒因素共同决定了病毒的致病性。我们已经建立了柯萨奇病毒B3心肌炎的小鼠模型，其中该病毒的H3变种会引起严重的心肌炎，而H3病毒的一个突变体，命名为H310A1，是非心肌炎的。H3和H310A1变异体的不同之处在于VP2衣壳蛋白中的单个非保守氨基酸突变。H310A1变异体刺激CD4+T调节细胞，主动抑制H3病毒感染诱导的致病免疫。T细胞为CD4+CD25+FoxP3+。H3和H310A1感染的一个主要区别是H3病毒是全身性TNFa的有效诱导者，而H310A1感染几乎不诱导这种细胞因子。其他人和我们的研究表明，外源性给予重组TNFa会加剧正常耐药小鼠的心肌炎易感性。因此，给予H310A1感染的小鼠给予TNFa可恢复心肌炎的易感性，并极大地减少T reg细胞转化生长因子的表达。由于转化生长因子β至少通过Th3细胞介导免疫抑制，因此我们假设TNFa调节Th3细胞的激活或功能。这是令人惊讶的，因为有报道说TNFa促进了TR1类型的T细胞。TnFa可能对不同类型的T-reg细胞有不同的诱导作用，有促进作用，也有抑制作用。在目前的模型中，我们认为TNFa可能通过诱导非经典的MHC I类蛋白CD1d和激活表达V？4T细胞受体的T细胞来消除T细胞。病毒性心肌炎中的V？4+细胞是CDID受限的，将活化的V？4+细胞过继转移到感染H310A1的小鼠体内可恢复心肌炎的易感性。在这个方案中，我们希望：1.确定T reg细胞是TR1、Th3还是自然的T reg细胞，这意味着它们应该通过IL-10、转化生长因子或细胞与细胞的接触来抑制获得性免疫；2.确定感染(TLR)、TNFa、CD1d和V？4+T细胞在T reg细胞产生或消灭中的相对作用；3.确定T reg细胞是抗原特异性的(病毒)、心血管特异性的(自身免疫)还是非抗原特异性的。

DESCRIPTION (provided by applicant): Myocarditis is an inflammation of the myocardium which often follows microbial infections. Enteroviruses (picornaviruses) and adenoviruses are most frequently implicated in clinical disease. However, both types of virus are extremely common and not everyone experiencing an enterovirus/adenovirus infection will develop myocarditis. Both host and viral factors determine viral pathogenicity. We have developed a murine model of coxsackievirus B3 myocarditis where the H3 variant of the virus induces severe myocarditis while a mutant of the H3 virus, designated H310A1, is non-myocarditic. The H3 and H310A1 variants differ by a single non-conserved amino acid mutation in the VP2 capsid protein. The H310A1 variant stimulates CD4+ T regulatory (T reg) cells which actively suppress the pathogenic immunity induced by H3 virus infection. The T reg cells are CD4+CD25+FoxP3+. A major difference in H3 and H310A1 infections is that H3 virus is a potent inducer of systemic TNFa while H310A1 infection induces little of this cytokine. Studies by others and us have shown that exogenous administration of recombinant TNFa exacerbates myocarditis susceptibility in normally resistant mice. Thus, giving TNFa to H310A1 infected mice restores myocarditis susceptibility and greatly reduces TGF¿ expression by T reg cells. Since TGF¿ mediates immunosuppression at least by TH3 cells, we hypothesize that TNFa modulates TH3 cell activation or function. This is surprising since TNFa has been reported to promote the Tr1 type of T reg cell. It is possible that TNFa may have different effects on induction of distinct types of T reg cells, promoting some and inhibiting others. In the current model, we believe that TNFa might abrogate T reg cells through induction of CD1d, a non-classical MHC class I protein, and activation of T cells expressing the V?4 T cell receptor. V?4+ cells in viral myocarditis are CDId-restricted and adoptive transfer of activated V?4+ cells into H310A1 infected mice restores myocarditis susceptibility. In this proposal, we wish to: 1. Determine whether T reg cells are Tr1, Th3 or natural T reg cells which means they should suppress adaptive immunity through IL-10, TGF¿ or cell-cell contact; 2. Determine the relative roles of infection (TLR), TNFa, CD1d and V?4+ T cells in generation or abrogation of T reg cells; and 3. Determine whether the T reg cells are antigen specific (virus), cardiovascular specific (autoimmunity), or non-antigen specific.