自噬对心肌微血管内皮细胞间质转分化的影响及机制

Recent studies suggest that endothelial to mesenchymal transition (EndMT) contribute to the pathogenesis of cardiac fibrosis. Role of autophagy in the pathogenesis of fibrosis diseases was well studied. Relations between autophagy and EndMT, however, are poorly understood. Our preliminary results revealed that EndMT of cardiac microvascular endothelial cells (CMVE) could be induced by ischemia and hypoxia, and EndMT could be disrupted through interfering of Notch signaling pathway. In this study, autophagy and EndMT of CMVE will be induced by ischemia and hypoxia in vitro. Drugs and gene over-expression or gene silencing will be used to regulate autophagy. The effects of autophagy on EndMT and the signaling pathway of Notch and Wnt will be examined. Finally, the roles of autophagy regulation on EndMT, myocardial fibrosis and cardiac function in acute rat myocardial infarction will be detected. Consequently, a new pathogenesis and a promising therapeutic target of EndMT may be expounded in this study. Inhibition of EndMT by autophagy regulation would be an innovative strategy for the treatment of myocardial fibrosis.

内皮细胞间质转分化（EndMT）在心肌纤维化发病过程中有重要意义，然而目前尚无抑制EndMT的特殊方法。自噬与众多纤维化疾病关系密切，但自噬与EndMT之间关系的研究尚无报道。我们初步研究结果表明，缺血缺氧条件下可诱导心肌微血管内皮细胞（CMVE）发生EndMT，抑制Notch信号系统可抑制EndMT。本课题将通过缺血缺氧条件下诱导CMVE发生自噬及EndMT，通过药物及基因转染、基因沉默方式调控自噬，观察调控自噬对EndMT的影响，并对自噬与EndMT之间Notch、Wnt信号通路做详细研究以确定自噬对EndMT影响机制。制作大鼠心肌梗死模型，研究体内调控自噬对EndMT、心肌纤维化、心功能的影响及其机制。本课题通过研究自噬与EndMT的相互影响及机制，将为EndMT提供新的发病机制及干预靶点，尝试调控自噬干预EndMT，进而为心肌纤维化治疗开辟新的途径。

在多种心脏病中，内皮细胞间质转分化(Endothelial-to-mesenchymal transition, EndMT) 可促进心肌纤维化的进展。同时，有大量研究表明自噬亦参与了心肌纤维化的调控。然而自噬调控心肌纤维化的具体分子机制尚未明确。本研究旨在探究自噬，EndMT及心肌纤维化三者之间的关系及分子机制，并试图找到抗心肌纤维化的有效手段。本研究体内实验证实在缺氧培养下的心肌微血管内皮细胞自噬及EndMT可同时被诱导发生。在缺氧条件下，加入自噬激活剂雷帕霉素可进一步提高细胞自噬水平，有效抑制EndMT；相反，加入自噬抑制剂3-MA或氯喹可抑制自噬水平，加速缺氧诱导的EndMT现象。TGFβ-Snail信号途径是引起EndMT的常见信号通路。通过雷帕霉素、3-MA或氯喹干预自噬并不会缺氧诱导内皮细胞自分泌TGFβ，但会影响下游信号分子Snail的表达。自噬标志蛋白LC3及Snail的双重荧光染色证实，自噬介导了缺氧状态下内皮细胞Snail蛋白的降解，从而影响EndMT。体内实验证实，EndMT参与了SD大鼠心肌梗死后心肌纤维化。通过雷帕霉素处理的心梗大鼠EndMT减弱，纤维化面积减少，心功能改善。而3-MA处理的心梗大鼠EndMT显著，纤维化面积增加，心功能改善不明显。总之，自噬可作为一种细胞自我保护机制对抗缺氧诱导的EndMT，从而抑制心肌纤维化，改善心功能。自噬可能作为一种潜在的治疗心肌梗死心肌纤维化的靶点。