血管生成素-2触发内皮损伤和血管重构在主动脉夹层中的作用及早期预警研究

Aortic dissection (AD) is a common cardiovascular emergency with high mortality and the molecular mechanisms are poorly understood. The literature currently gives a very strong focus on medial degeneration, but few studies specifically paid attention to the role of endothelial dysfunction and the subsequent vascular remodeling in the pathogenesis of AD. Angiopoietin-2 (Angpt 2) is secreted by activated endothelium and plays an important role in pathological vascular remodeling and angiogenesis. In our previous study, we found that the expression of Angpt 2 was up-regulated in aorta tissue in patients with AD and the variance of Angpt 2 promoter was associated with the occurrence of AD by genetic analysis. We subsequently demonstrated that the release of Angpt 2 from endothelial cells was regulated by vascular endothelial growth factor (VEGF) in a positive feedback manner, which triggered endothelial dysfunction, resulting in vascular smooth muscle cell phenotypic switch through a certain unknown molecular. In this study, we will go on to investigate the effect of Angpt 2 on endothelial biology and cross-talk between endothelial and smooth muscle cells in vascular remodeling with RNA interference, recombinant adenovirus transfection, and endothelial cell-vascular smooth muscle cell co-culture model et al. Then tissue-specific Angpt 2 transgenic and knockout mice are constructed to elucidate the influence of overexpression and depletion of Angpt 2 on the susceptibility of AD induced by angiotensin II. Finally, case-control study will be conducted to evaluate the association of Angpt 2 genetic variance with the risk of AD and clinical outcome in patients with hypertension. This study will offer insights into the molecular mechanisms of AD from a new perspective, and provide potential therapeutic targets and risk early-warning for AD.

主动脉夹层（AD）是临床危急重症，发病机制尚未阐明。目前的研究主要集中于中层退行性变，很少关注内皮功能障碍及其介导的血管重构在AD中的作用。血管生成素-2（Angpt 2）由内皮细胞分泌，在血管重构中起重要的调控作用。我们前期研究发现，Angpt 2在AD患者主动脉中表达升高，遗传学分析提示其基因启动子区变异和AD相关，细胞实验证实Angpt 2可通过VEGF正反馈触发内皮损伤并引起血管平滑肌表型转换。本研究拟在前期工作的基础上，利用敲低和过表达、内皮-平滑肌细胞共培养等方法，揭示Angpt 2对内皮生物学功能、内皮-血管平滑肌交互对话及胞外基质重构的影响及机制；运用动物模型探明Angpt 2基因缺失和过表达对AD形成的影响；最后通过病例对照研究明确Angpt 2基因遗传变异对高血压患者发生AD的预警价值。本研究将从新的视角探讨AD的发病机制，为寻找AD防治的干预靶点和早期预警提供新线索。

急性主动脉夹层是临床严重的危急重症，死亡率高，发病机制尚未阐明。本项目通过基因芯片筛选发现血管生成素2（Angpt 2）在主动脉夹层患者中表达升高，进一步围绕Angpt 2通过分子生物学、生物信息学、细胞实验及临床资料分析等进行了一系列研究，主要发现如下：Angpt 2在主动脉夹层患者主动脉组织蛋白的表达水平和外周血循环中均显著升高；Angpt 2通过氧化应激及VEGF正反馈效应造成内皮功能障碍，促发血管重构；Angpt 2受miR-4652-3p的调控，miR-4652-3p/Angpt 2信号通路可能是内皮功能障碍的通路之一；整合素a9是主动脉中层平滑肌粘附斑和细胞骨架调节的重要分子，可调控平滑肌细胞表型转换，整合素a9在主动脉夹层患者中表达显著下调，可能是主动脉夹层发生的机制之一；对主动脉夹层患者血清代谢性学分析，发现了400多个和正常对照有显著表达差异的标志物，深入研究这些差异代谢标志物对于主动脉夹层发生机制及临床诊断标志物具有重要意义；生酮处理的自发性高血压大鼠出现显著的心、肾、血管的重构和代谢紊乱，提示生酮可能是触发心血管重构的机制；临床对我国主动脉夹层患者数据库分析提示，中国主动脉夹层患者平均发病年龄较国外低10岁，高龄患者预后较差，但年轻主动脉夹层患者夹层复发率高，对临床患者的危险分层有一定的价值；病例对照研究发现Angpt 2在主动脉夹层患者中显著升高，且Angpt 2对主动脉夹层的诊断有较高的敏感性和特异性，可能是主动脉夹层新的诊断标志物。本项目围绕Angpt 2探讨了内皮功能障碍、主动脉中层血管平滑肌细胞表型调控、主动脉夹层的代谢组学改变及临床标志物的可行性，为深入研究主动脉夹层的发病机制和探索潜在的诊断标志物及治疗靶点奠定了基础。