Innate and Adaptive Immune Responses in the Virus-Infected Heart

描述(申请人提供)：柯萨奇病毒是急性心肌炎最常见的感染原因，这种疾病会导致大量人类发病率和死亡率。即使在病毒(显然)被清除后，低度炎症仍可能继续，最终导致扩张型心肌病的严重后果。人们普遍认为，先天性和获得性宿主免疫反应对病毒控制和(免疫病理)心脏病都有贡献。然而，我们对柯萨奇病毒诱导的免疫反应的了解还很初级。在这项建议中，使用现有的和新的柯萨奇病毒B3(CVB3)感染的小鼠模型，我们将评估I型干扰素(T1干扰素)对急性和持续CVB3感染的心脏内效应，我们将使用我实验室开发的一套独特的试剂来评估感染小鼠心脏中CVB特异性T细胞反应。有3个具体目的：1.T1干扰素在心脏中的作用存在争议。一些已发表的研究表明，这些与生俱来的细胞因子可能会清除心脏中的病毒，但其他研究表明，它们在受感染的心脏中没有任何作用。我们将杂交两个现有的小鼠品系，以开发一种新的小鼠模型，在该模型中，心肌细胞上的T1干扰素受体的表达可以随意消融。这些小鼠将使我们能够解决上述争议，并确定T1干扰素是否负责抑制病毒在急性感染心脏中的传播。此外，通过在持续感染期间移除这种受体，我们将能够确定是否需要T1干扰素来维持持续状态。2.尽管进行了多年的研究，但我们对CVB特异性T细胞反应的了解仍然很少。为了解决这一不足，我的实验室开发了各种独特的试剂，包括表达具有良好特征的CD4+和CD8+T细胞表位的重组CVB，以及针对这些表位的基因标记T细胞。我们将利用我们的试剂来研究CVB特异性的CD4+和CD8+T细胞在急性心肌炎过程中在心脏中的渗入动力学，并将确定这种T细胞渗入受T1干扰素调节的程度。3.我们还将使用上述试剂来定位急性和持续感染期间心脏内CVB3抗原的表达。哪些心脏细胞表达抗原？在感染后的不同时间，抗原特异性的CD4+和CD8+T细胞以多快的速度回到受感染的心脏？病毒清除后，心脏中能检测到多长时间的表位？病毒特异性的CD4+和CD8+T细胞如何促进病毒清除和免疫病理心脏病的发展？

DESCRIPTION (provided by applicant): Coxsackieviruses are the commonest infectious cause of acute myocarditis, a disease that causes substantial human morbidity and mortality. Even after the virus has (apparently) been cleared, low- grade inflammation may continue, eventually leading to the serious outcome of dilated cardiomyopathy. There is general agreement that the innate and adaptive host immune responses contribute both to virus control, and to (immunopathological) heart disease. However, our knowledge of coxsackievirus-induced immune responses is rudimentary. In this proposal, using existing and new mouse models of coxsackievirus B3 (CVB3) infection, we shall evaluate the intracardiac effects of type I interferons (T1IFN) on acute and persistent CVB3 infection, and we shall use a unique set of reagents, developed in my laboratory, to assess CVB-specific T cell responses in the hearts of infected mice. There are 3 Specific Aims : 1. The effects of T1IFN in the heart are controversial. Some published work suggests that these innate cytokines may clear virus from the heart, but other work has suggested that they play no role whatsoever within the infected heart. We shall cross two existing mouse strains to develop a new mouse model in which the expression of T1IFN receptor on cardiomyocytes can be ablated at will. These mice will allow us to resolve the above controversy, and to determine if T1IFN is responsible for constraining viral spread in the acutely-infected heart. In addition, by removing this receptor during persistent infection, we shall be able to determine if T1IFN is required for the maintenance of the persistent state. 2. Despite many years of study, our understanding of CVB-specific T cell responses remains minimal. To address this deficiency, my lab has generated a variety of unique reagents including recombinant CVB that expressed well-characterized CD4+ and CD8+ T cell epitopes, and genetically-marked T cells specific for those epitopes. We shall exploit our reagents to investigate the kinetics of CVB- specific CD4+ & CD8+ T cell infiltration in the heart over the course of acute myocarditis, and will determine the extent to which this T cell infiltration is regulated by T1IFN. 3. We also shall use the above reagents to map CVB3 antigen expression within the heart during acute and persistent infection. In which heart cells are antigens expressed? How quickly do antigen- specific CD4+ and CD8+ T cells home to the infected heart at various times after infection? For how long after viral clearance do epitopes remain detectable in the heart? How do virus-specific CD4+ and CD8+ T cells contribute to virus clearance, and to the development of immunopathological heart disease?