Genetic mechanisms of autoimmune myocarditis

自身免疫性心肌炎是由于对心肌细胞表达的心脏特异性抗原的免疫反应而发生的。 心脏MHC在确定自身免疫性心肌炎的易感性方面很重要;然而， 遗传因素也很关键。我们建议使用小鼠模型来研究这些遗传机制， 心肌肌球蛋白诱导的实验性自身免疫性心肌炎（EAM）。本提案的目标是 进一步定位易感和耐药小鼠品系之间的遗传差异， 区分几种细胞谱系在自身免疫性心肌炎遗传易感性中的作用。我们将 研究了两个共刺激候选基因ICOS（Specific aim 1）和CD 27（Specific aim 2）。两 这些基因分别位于1号和6号染色体上的易感区域。此外，双方 在易感的人中，用心肌肌球蛋白免疫后，ICOS和CD 27受到不同的调节。 和耐药小鼠。具体目标1将深入研究我们的初步发现，耐药B 10. S小鼠 肌球蛋白免疫后，CD 4 +T细胞上ICOS表达增加。这一发现表明，至少 部分表达ICOS的CD 4 + T细胞在EAM中是调节性的。因此，我们将评估 ICOS对CD 4 + T细胞亚群的影响，并确定ICOS在效应和调节T细胞中的作用， EAM通过将ICOS缺陷型和/或IL-10缺陷型CD 4 + T细胞过继转移到Rag-/-小鼠中。我们将 还鉴定了ICOS基因的多态性。特异性目的2 CD 27在A.SW中显著下调 而B10.S小鼠在心肌肌球蛋白免疫后则没有，这表明CD 27是一个候选基因 影响Eam 2区域中的EAM敏感性。我们将首先检查CD 27基因的多态性。 接下来，我们将在A.SW和B10.S小鼠中确定EAM期间T细胞上的CD 27的动力学和功能。 并验证我们的假设，即在早期活化阶段下调T细胞上的CD 27对于 它们分化为致病性效应细胞。我们已经确定EAM的遗传控制是 由包括T和/或B细胞的造血谱系细胞介导。具体目标3将审查是否 遗传因子调节Th 17细胞、NK细胞、巨噬细胞、B细胞和调节性T细胞介导 EAM。我们将从易感品系的细胞特异性敲除小鼠中转移骨髓到 辐射抗性菌株我们发现B10.S小鼠产生的IL-23少于AS.W小鼠 这表明B10.S小鼠可能对心肌炎具有抵抗力， 诱导Th 17细胞分化或维持Th 17细胞在心脏中存活的能力。因此，我们将确定 Th 17通路相关细胞因子和趋化因子的多态性及其蛋白表达谱 SW和B10.S小鼠中用心肌肌球蛋白免疫。

Autoimmune myocarditis develops due to an immune response to cardiac-specific antigens expressed in the heart. The MHC is important in determining susceptibility to autoimmune myocarditis; however other genetic factors are also critical. We propose to study these genetic mechanisms using a mouse model, cardiac myosin-induced experimental autoimmune myocarditis (EAM). The goal of the present proposal is to further localize the genetic differences between susceptible and resistant mouse strains, and to distinguish the roles of several cell lineages in genetic susceptibility to autoimmune myocarditis. We will investigate two costimulatory candidate genes, ICOS (Specific aim 1) and CD27 (Specific aim 2). Both of these genes are located in susceptibility regions on chromosomes 1 and 6 respectively. Additionally, both ICOS and CD27 are differentially regulated following immunization with cardiac myosin in the susceptible and resistant mice. Specific aim 1 will examine in depth our preliminary finding that resistant B 10.S mice have higher ICOS expression on CD4+T cells after myosin immunization. This finding suggests that at least part of the ICOS expressing CD4+ T cells are regulatory in EAM. Therefore we will assess the expression of ICOS on subsets of CD4+ T cells and determine the role of ICOS in effector and regulatory T cells during EAM by adoptively transferring ICOS deficient and/or IL-10 deficient CD4+ T cells into Rag-/- mice. We will also identify polymorphism in the ICOS gene. Specific aim 2 CD27 is significantly down regulated in A.SW but not B10.S mice following immunization with cardiac myosin, suggesting that CD27 is a candidate gene influencing EAM susceptibility in the Eam2 region. We will first examine the CD27 gene for polymorphisms. Next, we will determine the kinetics and function of CD27 on T cells during EAM in A.SW and B10.S mice and test our hypothesis that down regulation of CD27 on T cells in early activation phase is essential for their differentiation to pathogenic effector cells. We have established that genetic control of EAM is mediated by cells of the hematopoietic lineage including T and/or B cells. Specific aim 3 will examine if genetic factors modulate Th17 cells, NK cells, macrophages, B cells and T regulatory cells in mediating EAM. We will transfer bone marrow from cell specific knockout mice of the susceptible strain into the irradiated resistant strain. We have found that IL-23 production was less in B10.S mice than AS.W mice during EAM, which suggest that B10.S mice might be resistant to myocarditis due to their decrease and ability to induce differentiation or sustain survival of Th17 cells in heart. Therefore we will identify polymorphisms and the protein expression profile of cytokines and chemokines related to Th17 pathway following immunization with cardiac myosin in A.SW and B10.S mice.