Innate Immunity in Myocarditis

描述（由申请人提供）：心肌炎是一种心肌炎症，通常由微生物感染引起。肠病毒（小核糖核酸病毒）和腺病毒最常与临床疾病有关。我们建立了柯萨奇病毒B3 （CVB3）心肌炎的小鼠模型。致病性需要病毒诱导强烈的抗原特异性CD4+Th1 （IFN+）细胞反应，而促进CD4+Th2 （IL-4+）反应的条件可预防心肌炎。表达V4 T细胞受体的T细胞对CD4+Th1免疫的产生至关重要。人们普遍认为，先天效应如+细胞调节适应性免疫反应。这种调节的公认机制取决于先天效应因子的细胞因子释放，这提供了一个有利于特定Th反应的环境环境；以及先天效应对抗原提呈细胞的影响，导致抗原提呈细胞改变辅助分子或细胞因子的表达，从而改变CD4+细胞的应答。据我们所知，我们是唯一一个实验室假设+细胞直接结合CD4+细胞调节Th表型。我们已经证明，+细胞选择性地杀死CD4+Th2细胞，使CD4+Th1细胞保持完整。目前，几乎所有的研究都表明CD4+Th1细胞对fas依赖性凋亡具有选择性易感性，而CD4+Th2细胞对fas依赖性凋亡具有显著的抗性。我们的数据与公认的知识截然相反。主要的问题是为什么在我们的CVB3模型中，CD4+Th2细胞对凋亡敏感，以及+细胞对Th2细胞的选择性消除在多大程度上导致了CVB3感染小鼠中CD4+Th1的优势。我们假设CD4+ Th1和Th2细胞之间的CD1d、Fas或抗凋亡因子（如c-FLIPL）存在差异，并且这些差异允许选择性杀死Th2细胞。在抗原刺激结束时消除效应CD4+细胞可以节省造血室的资源和空间，但免疫收缩应该同时适用于CD4+Th1和Th2细胞。仅CD4+Th1细胞的收缩可导致CD4+Th2的进行性积累，最终导致免疫系统失衡。先天效应如+细胞可能在消除活化的CD4+Th2细胞中发挥重要作用。这个提议的核心问题是先天效应如何区分Th1和Th2细胞，杀死后者而不杀死前者。具体目的是：1)确定+细胞是否仅用于激活CD4+细胞或维持体内活化细胞；(2)确定体内CD4+细胞免疫调节CD4+应答是否需要CD4+细胞上CD1d的表达，以及V4+细胞产生IFN的作用；(3)确定CD4+ Th1或Th2细胞克隆中CD1d或Fas的表达是否不同，并解释Th2克隆对V4+细胞诱导的凋亡易感性增加的原因；(4)确定c-FLIPL在CD4+Th1和Th2细胞中的表达是否不同，Th1细胞中c-FLIPL表达水平升高是否能保护它们免受V4+细胞介导的杀伤。公共卫生相关性：该资助将研究Vgamma4+ T细胞在通过fas依赖机制选择性杀死活化CD4+Th2细胞中的作用，作为免疫应答后免疫收缩的一种方法。具体目的是：1)确定+细胞是否仅用于激活CD4+细胞，还是用于维持体内活化的细胞。2)确定体内CD4+细胞免疫调节CD4+应答是否需要CD4+细胞上Fas或CD1d的表达，以及V4+细胞产生IFN的作用。3)确定CD4+ Th1或Th2细胞克隆中CD1d或Fas的表达是否不同，并解释Th2克隆对V4+细胞诱导的凋亡易感性增加的原因。4)确定c-FLIPL在CD4+Th1和Th2细胞中的表达是否不同，以及Th1细胞中c-FLIPL的表达升高是否能保护它们免受V4+细胞介导的杀伤。

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. We have developed a murine model of coxsackievirus B3 (CVB3) myocarditis. Pathogenicity requires virus induction of a strong antigen-specific CD4+Th1 (IFN+) cell response while conditions which promote a CD4+Th2 (IL-4+) response prevent myocarditis. T cells expressing the V4 T cell receptor are crucial to generation of CD4+Th1 immunity. It is well accepted that innate effectors such as + cells modulate adaptive immune responses. The accepted mechanisms for this modulation depend upon cytokine release by the innate effectors which provides an environmental milieu favorable to a specific Th response; and innate effector impact on antigen presenting cells resulting in changes in accessory molecule or cytokine expression by the antigen presenting cells leading to alterations in CD4+ cell responses. To the best of our knowledge, we are the only laboratory hypothesizing that + cells directly bind to CD4+ cells modulating the Th phenotype. We have shown that + cells selectively kill CD4+Th2 cells leaving the CD4+Th1 cells intact. Currently, nearly all studies show that CD4+Th1 cells are selectively susceptible to Fas-dependent apoptosis while CD4+Th2 cells are remarkably resistant. Our data is diametrically opposite of accepted knowledge. The major question is why in our CVB3 model, CD4+Th2 cells are apoptosis susceptible and how much the selective elimination of Th2 cells by + cells contributes to the CD4+Th1 dominance in CVB3 infected mice. We hypothesize that there would be differences in CD1d, Fas or anti-apoptotic factors, such as c-FLIPL, between CD4+ Th1 and Th2 cells and that these differences allow the selective killing of the Th2 cells. Elimination of effector CD4+ cells at the end of antigenic stimulation conserves resources and space in the hemopoietic compartment, but immune contraction should apply to both CD4+Th1 and Th2 cells. Contraction of only CD4+Th1 cells could allow progressive accumulation of CD4+Th2 and ultimate imbalance of the immune system. Innate effectors such as + cells may play an important role in eliminating activated CD4+Th2 cells. The question central to this proposal is how innate effectors distinguish between Th1 and Th2 cells, killing the latter but not the former. The Specific Aims are: 1) Determine if + cells are only required for activating CD4+ cells or for maintaining the activated cells in vivo; (2) Determine if CD1d expression on CD4+ cells is required for + cell immunomodulation of the CD4+ response in vivo and the role of IFN production by V4+ cells; (3) Determine whether CD1d or Fas expression on CD4+ Th1 or Th2 cell clones differs and explains the increased susceptibility of Th2 clones to V4+ cell induced apoptosis.; and (4) Determine if c-FLIPL expression differs between CD4+Th1 and Th2 cells and elevated levels in Th1 cells protects them from V4+ cell mediated killing. . PUBLIC HEALTH RELEVANCE: This grant will investigate the role of Vgamma4+ T cells in selectively killing activated CD4+Th2 cells by Fas-dependent mechanisms, as a method for immune contraction after an immune response. The Specific Aims are to 1) Determine if + cells are only required for activating CD4+ cells or for maintaining the activated cells in vivo. 2) Determine if Fas or CD1d expression on CD4+ cells is required for + cell immunomodulation of the CD4+ response in vivo and the role of IFN production by V4+ cells. 3) Determine whether CD1d or Fas expression on CD4+ Th1 or Th2 cell clones differs and explains the increased susceptibility of Th2 clones to V4+ cell induced apoptosis. 4) Determine if c-FLIPL expression differs between CD4+Th1 and Th2 cells and whether elevated levels in Th1 cells protects them from V4+ cell mediated killing.