Autoimmunity in the Mediation of Infectious Myocarditis

描述（由申请人提供）：心脏病是人类死亡的主要原因，心肌炎是青少年心力衰竭的主要原因。患有心肌炎的患者可发展为扩张性心肌病（DCM），这是心脏移植的常见原因，也是迄今为止对抗DCM的唯一可行选择。心肌炎/DCM患者显示柯萨奇病毒B3 （CVB）和心脏抗原抗体，提示CVB介导的自身免疫在疾病发病机制中的作用，但直接因果关系仍有待临床确定。长期目标是确定通常感染心血管系统并启动心脏自身免疫的病原体的自身免疫机制。本应用的目的是确定慢性心肌炎发生在CVB感染由于自身免疫反应心脏抗原。核心假设是，由分子模拟和表位扩散机制产生的心脏特异性CD4 T细胞介导CVB诱导的感染后心肌炎。这一假设将在对自身免疫性和病毒性心肌炎高度敏感的A/J小鼠中进行测试，其组织学特征与人类疾病相似。该项目的两个具体目标是：1)描述交叉反应性CD4 T细胞在CVB心肌炎介导中的作用。通过T细胞增殖试验和细胞因子反应评估，从CVB蛋白质组中鉴定出的一组模仿表位能够诱导三种心脏抗原的致病性交叉反应T细胞。[2]探讨表位扩散作为CVB感染后心肌炎的自身免疫机制。使用心肌肌球蛋白重链(Myhc)- 334-352的主要组织相容性复合体（MHC） II类右旋聚体，研究小组已经证明心肌炎易感的A/J小鼠，显示Myhc-¿特异性T细胞的产生，将疾病转移给未成熟的小鼠。这些观察结果为验证CVB感染通过表位扩散诱导产生具有多种抗原特异性的心脏反应性T细胞的假设提供了令人信服的理论依据。具体目标将通过测量T细胞反应、MHC II类右旋糖聚体染色、细胞因子分析、磁共振显微镜成像、主动免疫和过继转移实验以及组织学来实现。提出的方法是创新的，因为它解决了自身免疫反应是否在抗原特异性水平上促进CVB诱导的感染后心肌炎的基本问题。这项研究具有重要意义，因为它可以为未来研究暴露于CVB的心肌病患者可能产生的心脏反应性T细胞的作用提供基础。这些研究可能会创造机会，以改变肽配体和耐受性原的形式获得免疫疗法，作为抗原特异性治疗方式，包括个性化治疗，用于DCM患者。

DESCRIPTION (provided by applicant): Heart disease is the leading cause of death in humans, and myocarditis is a predominant cause of heart failure in young adolescents. Patients affected with myocarditis can develop dilated cardiomyopathy (DCM), a common reason for heart transplantation, which to date is the only viable option for combating DCM. Myocarditis/DCM patients show antibodies to coxsackievirus B3 (CVB) and cardiac antigens, suggesting a role for CVB-mediated autoimmunity in the disease pathogenesis, but a direct causal link remains to be determined clinically. The long-term goal is to determine the autoimmune mechanisms of pathogens that commonly infect the cardiovascular system and initiate heart autoimmunity. The objective of this application is to determine whether chronic myocarditis that occurs in CVB infection due to an autoimmune response to cardiac antigens. The central hypothesis is that cardiac-specific CD4 T cells generated by mechanisms that involve molecular mimicry and epitope spreading mediate postinfectious myocarditis induced by CVB. This hypothesis will be tested in A/J mice that are highly susceptible to both autoimmune and viral myocarditis, the histologic features of which resemble those in human disease. The project's two specific aims are to: 1) Delineate the role of cross-reactive CD4 T cells in the mediation of CVB myocarditis. Panel of mimicry epitopes identified from the CVB proteome are capable of inducing pathogenic cross-reactive T cells for three cardiac antigens as evaluated by T cell proliferation assay and cytokine responses. [2) Investigate epitope spreading as an autoimmune mechanism of postinfectious myocarditis induced by CVB. Using major histocompatibility complex (MHC) class II dextramers for cardiac myosin heavy chain (Myhc)-¿ 334-352, the team has demonstrated that myocarditis-susceptible A/J mice, show the generation of Myhc-¿-specific T cells that transfer disease to naive mice. These observations provide a compelling rationale to test the hypothesis that CVB infection induces the generation of cardiac-reactive T cells with multiple antigen specificities through epitope spreading. The specific aims will be achieved by measurement of T cell responses, MHC class II dextramer staining, cytokine analysis, magnetic resonance microscopy imaging, active immunization and adoptive transfer experiments, and histology. The proposed approach is innovative, as it addresses the fundamental question of whether autoimmune response contributes to postinfectious myocarditis induced by CVB at the level of antigen specificity. The proposed research is significant, as it may provide a basis for future investigations into the role of cardic-reactive T cells that might be generated in cardiomyopathy patients as a result of exposure to CVB. These studies may then create opportunities to derive immunotherapies in the form of altered peptide ligands and tolerogens as antigen-specific treatment modalities, including personalized therapies, for DCM patients.]