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能会发展为扩张型心肌病（DCM），这是心脏移植的常见原因，迄今为止，这是对抗扩张型心肌病的唯一可行选择。心肌炎/扩张型心肌病患者表现出针对柯萨奇病毒 B3 (CVB) 和心脏抗原的抗体，表明 CVB 介导的自身免疫在疾病发病机制中发挥作用，但直接的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引发心脏自身免疫的病原体的自身免疫机制。本申请的目的是确定 CVB 感染中发生的慢性心肌炎是否是由于对心脏抗原的自身免疫反应所致。核心假设是，通过涉及分子拟态和表位扩散的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心肌炎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的组织学特征相似。该项目的两个具体目标是： 1) 阐明交叉反应性 CD4 T 细胞在 CVB 心肌炎介导中的作用。通过 T 细胞增殖测定和细胞因子反应评估，从 CVB 蛋白质组中鉴定出的一组拟态表位能够诱导三种心脏抗原的致病性交叉反应性 T 细胞。 [2) 研究表位扩散作为 CVB 诱导的感染后心肌炎的自身免疫机制。使用主要组织相容性复合体 (MHC) II 类右旋聚体进行心肌肌球蛋白重链 (Myhc)-¿ 334-352，研究小组证明心肌炎易感性 A/J 小鼠会产生 Myhc-¿ 特异性 T 细胞，将疾病转移给初始小鼠。这些观察结果为检验 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 细胞的产生这一假设提供了令人信服的理由。具体目标将通过测量 T 细胞反应、MHC II 类右旋聚体染色、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。所提出的方法具有创新性，因为它解决了自身免疫反应是否在抗原特异性水平上导致 CVB 诱导的感染后心肌炎这一基本问题。拟议的研究意义重大，因为它可能为未来研究心脏反应性 T 细胞的作用提供基础，心脏反应性 T 细胞可能因暴露于 CVB 而在心肌病患者中产生。这些研究可能会创造机会，以改变的肽配体和耐受原的形式衍生出免疫疗法，作为 DCM 患者的抗原特异性治疗方式，包括个性化疗法。]

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.]