IRAK-M基因介导巨噬细胞亚群参与心肌梗死后瘢痕修复的机制研究

项目名称： IRAK-M基因介导巨噬细胞亚群参与心肌梗死后瘢痕修复的机制研究

项目编号： No.81470426

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 医药、卫生

项目作者： 陈未

作者单位： 中国医学科学院北京协和医院

项目金额： 73万元

中文摘要： 心肌梗死后过强的炎症反应导致瘢痕形成受阻，造成心脏破裂或心肌重塑。心肌梗死修复期Ly-6Clow细胞高表达白细胞介素相关激酶M（IRAK-M），并具有促胶原形成作用，但机制不清。本研究采用小鼠冠状动脉缺血再灌注模型，分离野生型和IRAK-M基因敲除小鼠心梗修复期心肌组织内Ly6Clow细胞，对TLR/IL1R信号通路的各阶段及其可能调节机制进行系统研究。并将心肌成纤维细胞与Ly6Clow细胞共培养，研究IRAK-M基因缺失对胶原形成、交联的影响。构建小鼠IRAK-M过表达的Ly6Clow细胞系和成纤维细胞系，对比各类细胞抑炎特性及TLR/IL1R信号通路的差异，寻找可能调控炎症向瘢痕转化的关键因子。通过巨噬细胞清除技术，在体研究心梗修复期高表达IRAK-M的Ly6Clow细胞亚群对心脏重塑的影响。本研究的意义在于找到心梗后促瘢痕修复的特异性靶细胞和相应机制，为改善心梗预后提供新的治疗位点。

中文关键词： 急性心肌梗死；心肌重构；瘢痕修复；IRAK-M；巨噬细胞

英文摘要： Exaggerated and prolonged inflammation after myocardial infarction (MI) accelerates cardiac rupture and left ventricular remodeling by impairing scar healing. Inflammatory pathways may present a therapeutic target to prevent post-MI heart failure. Monocytes/macrophages are critical modulating cells in inflammatory responses. Two subpopulations of macrophages, defined as Ly6Chigh and Ly6Clow cells, have been proved to play distinct roles in this pro-and anti-inflammatory processes following cardiac injuries. Ly6Chigh cells exhibit pro-inflammatory properties, while the Ly6Clow subset shows significant activities on inflammatory suppression, angiogenic enhancement and collagen synthesis. However, the mechanisms why Ly6Clow macrophages exert an protective effect on injured tissues are largely unknown.Toll-Like receptor (TLR) and interleukin (IL)-1 signaling has been demonstrated to be critically involved in the post-infarction negative inflammatory responses. Our preliminary data showed that interleukin-1 receptor-associated kinase (IRAK)-M and type II IL1 receptor (IL1RII), both known as endogenous inhibitory moleculars of TLR/IL pathways, were upregulated in Ly6Clow cells after MI. The depletion of IRAK-M gene resulted in a reduced anti-inflammatory function of Ly6Clow cells. Therefore, we hypothesized that the inflammatory suppression of Ly6Clow macrophages may mediated by TLR/IL inhibitory signals. In the present study, IRAK-M gene knockout mice will be used to analyze the TLR/IL1R pathways and possible mechanisms by which Ly6Clow macrophages act as both a negative regulator of inflammation and a positive mediator of scar formation. Collagen formation and cross-linking will be measured by co-culturing ly6Clow macrophages and myo-fibroblasts isolated from infarcts after 7 days of ischemia and reperfusion procedures. Anti-inflammatory properties will be thoroughly investigated in Ly6Clow and myo-fibroblasts cell lines which over-express IRAK-M. Specific and timely clearance of macrophages by clodronate liposomes will be performed to illustrate the modulating effect of IRAK-M in Ly6Clow macrophages for cardiac remodeling after myocardial infarction. Our study will demonstrate for the first time the protective functions of Ly6Clow macrophages through endogenous inflammatory factor IRAK-M in infarcted hearts and may identify specific cellular effectors and mechanisms accelerating cardiac repair.

英文关键词： acute myocardial infarction;cardiac remodeling;scar healing;IRAK-M;macarophages