Autoimmunity in the Mediation of Infectious Myocarditis

描述(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。受心肌炎影响的患者可能发展为扩张型心肌病(DCM)，这是心脏移植的常见原因，到目前为止，这是对抗DCM的唯一可行选择。心肌炎/DCM患者表现出抗柯萨奇病毒B3(CVB)和心脏抗原的抗体，提示CVB介导的自身免疫在疾病发病机制中发挥了作用，但直接原因联系仍有待临床确定。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。这项应用的目的是确定慢性心肌炎是否发生在CVB感染中，这是由于对心脏抗原的自身免疫反应所致。中心假设是心脏特异的CD4T细胞通过分子模拟和表位扩散机制产生，介导了CVB诱导的感染后心肌炎。这一假设将在A/J小鼠身上进行验证，这些小鼠对自身免疫性心肌炎和病毒性心肌炎高度敏感，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)阐明交叉反应的CD4T细胞在柯萨奇病毒心肌炎的调节中的作用。通过T细胞增殖试验和细胞因子反应评价，从CVB蛋白质组鉴定出的一组模拟表位能够诱导致病T细胞对三种心脏抗原产生交叉反应。[2]探讨表位扩散作为柯萨奇病毒感染后心肌炎的自身免疫机制。使用针对心肌肌球蛋白重链的主要组织相容性复合体II类葡聚体-�334-352，研究小组已经证明，心肌炎易感的A/J小鼠可以产生MyHC-�特异性T细胞，将疾病传播给幼小鼠。这些观察结果提供了一个令人信服的理由来检验这一假设，即CVB感染通过表位扩散诱导具有多种抗原特异性的心脏反应性T细胞的产生。具体的目标将通过T细胞反应的测量、MHC II类葡聚体染色、细胞因子分析、磁共振成像、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对CVB诱导的感染后心肌炎起作用这一根本问题。这项拟议的研究意义重大，因为它可能为未来研究心肌病患者暴露于CVB后可能产生的心脏反应性T细胞的作用提供基础。然后，这些研究可能创造机会，以改变的多肽配体和耐受原的形式衍生免疫疗法，作为DCM患者的抗原特异性治疗方式，包括个性化治疗。]

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.]