microRNA-146a在动脉粥样硬化易损斑块中的作用及机制研究

Inflammation and apoptosis of macrophage foam cells are important mechanisms for the vulnerability of atherosclerotic plaques. We have found that miR-146a level was increased in peripheral blood mononuclear cells,plasma，atherosclerotic plaque and infarcted myocardial tissue of patients with coronary artery disease, and miR-146a level was positively correlated with the severity of coronary artery lesions, which indicates that miR-146a is closely related to atherosclerosis (AS). TRAF6/ and IRAK-1 plays an important role in the development of AS, while miR-146a can inhibit inflammation and apoptosis by TRAF6 and IRAK-1 pathway. Accordingly, we analyzed that miR-146a may affect the vulnerability of atherosclerotic plaques, and can be used as a new target for the detection and treatment of vulnerable plaque. First, we detect the plaque properties by IVUS in patients with coronary heart disease, and analyze the relationship between miR-146a level in the peripheral blood and and plaque vulnerability. Second, we treat APOE deficient mice model of AS with miR-146a overexpression, plaque vulnerability will be analyzed. At last, we explore the effects of miR-146a overexpression in reducing the plaque vulnerability from pathways of TRAF6 and IRAK-1 and downstream inflammation and macrophage apoptosis,which reveals the biological role of miR-146a in the atherosclerotic process.

炎症反应及巨噬泡沫细胞凋亡是影响动脉粥样硬化（AS）斑块易损性的重要机制。我们前期研究发现miR-146a在冠心病患者外周血单个核细胞、血浆、斑块及梗死心肌组织中表达均升高,且与冠脉病变严重程度呈正相关，提示miR-146a与AS密切相关。miR-146a能直接负性调控在AS发展过程中发挥重要作用的炎症调控因子-TRAF6及IRAK-1，从而抑制炎症反应及细胞凋亡。据此，我们分析miR-146a可影响斑块的易损性，能作为易损斑块检测和治疗的新靶标。本项目拟首先收集临床病例行IVUS检测AS斑块易损性，明确外周血miR-146a水平与斑块易损性的关系；继而采用miR-146a过表达处理APOE缺陷小鼠AS模型，分析斑块易损性的变化；最后在体外从TRAF6/IRAK-1途径及下游炎症反应、巨噬泡沫细胞凋亡两个方面探讨miR-146a过表达减少斑块易损性的机制，为AS治疗提供新的方向和靶点。

背景：动脉粥样硬化是一种慢性炎症性疾病。动脉粥样硬化的易损斑块可导致许多疾病的发展，包括急性冠状动脉综合征和冠心病。众所周知，miR-146a是免疫信号转导途径的关键制动miRNA。然而，miR-146a对动脉粥样硬化斑块稳定性的影响的仍有待阐明。.方法和结果：我们构建了动脉粥样硬化动物模型和泡沫细胞模型，并在模型中过度表达和敲除miR-146a。通过苏木精-曙红（HE）、油红O、免疫细胞化学（IHC）和天狼星染色，我们使用（脂质面积+巨噬细胞面积）和（SMC面积+胶原面积）的比例来评估动脉粥样硬化斑块稳定性。TUNEL和流式细胞术检测巨噬细胞的凋亡水平。通过ELISA检测炎症因子的水平。结果表明，miR-146a、IRAK1和TRAF6在动脉粥样硬化动物的斑块中异常表达。miR-146a的过度表达通过抑制斑块形成、巨噬细胞凋亡和促炎症因子水平导致斑块更加稳定。双荧光素酶报告基因、ELISA、IF和FISH被用来证实miR-146a对IRAK1和TRAF6的调节机制。我们发现IRAK1和TRAF6促进RAW264.7巨噬细胞的脂质摄取、凋亡和促炎因子的释放，而miR-146a通过抑制IRAK1和TRAF6表达恢复RAW264.7巨噬细胞表型。.结论：我们首次显示miR-146a通过负调节IRAK1和TRAF6的表达，抑制泡沫细胞的形成、RAW264.7巨噬细胞凋亡和促炎症反应，从而增强动脉粥样硬化斑块的稳定性。