miRNA-19a/744通过调控炎性反应影响冠状动脉微栓塞后心肌重构的机制研究

Coronary microembolization, a critical pathophysiological phenomenon post percutaneous coronary intervention, leads to cardiac remodeling through stimulating inflammatory responses within the injured myocardium. Previous researches indicated that miRNAs (miRs) were involved in the development of cardiac remodeling and the regulation of inflammatory responses in coronary heart diseases. However, the role of miRs in the development of cardiac remodeling induced by coronary microembolization remains unclear. In previous study we had constructed a model of coronary microembolization in swine, had verified the dose-effect relationship of the inflammatory responses with cardiac remodeling, and had performed the microarrays to scan the profile of miRNAs. We had further observed that miR-19a and miR-744 (miR-19a/744), the potentially regulating factors of inflammatory responses, significantly changed in the coronary microembolization region compared with those in baselines, suggesting that miR-19a/744 might regulate cardiac remodeling induced by coronary microembolization through inflammatory responses modulation. Based on this assumption, we will develop the gain-of-function and loss-of-function models of miR-19a/744 via viral transfection in vitro to investigate the effect of miR-19a/744 on the inflammatory reactions induced by hypoxic pretreatment and the potential mechanisms as well. Meanwhile, we will testify the modulative relationship between the miR-19a/744 and the potential target protein, tumor necrosis factor-α and transforming growth factor-β1 respectively, by a luciferase assay, followed by performing a catheter-based antegrade intracoronary viral gene delivery in vivo in a coronary microembolization model of swine. In parallel, we will evaluate the long-term cardiac remodeling by cardiac magnetic resonance imaging to elucidate the role of miR-19a/744 in the prevention of cardiac remodeling resulting from coronary microembolization. The present study will be expected to provide the novel targets for prevention and treatment of cardiac remodeling induced by coronary microembolization as well as to offer an experimental evidence for establishing effective therapeutic strategies.

冠状动脉微栓塞是冠心病介入治疗的重要病理现象，炎性反应参与介导由此导致的心肌重构；既往研究证实miRNAs（miRs）调控冠心病发生发展中的炎性反应及心肌重构，然而miRs在冠状动脉微栓塞防治中的作用尚不明确。我们前期研究借助冠脉微栓塞后心肌重构的家猪模型，揭示了部分炎性因子在其中的变化规律及作用，同时筛查出微栓塞区域部分炎性相关的miRs差异表达，从而推论该miRs通过调控炎性反应影响心肌重构。本项目将进一步构建高低表达miR-19a/744的细胞模型，体外缺氧培养探究各组细胞炎性因子表达的差异；分别检测miR-19a/744对肿瘤坏死因子-α/转化生长因子-β1的靶向调控作用及信号通路；同时利用家猪冠脉微栓塞模型，经导管冠脉内实施病毒输注转染，探讨miR-19a/744对心肌局部炎性反应和心肌重构的影响。本项目将从miRs靶向调控的角度，为制定冠脉微栓塞后心肌重构防治策略提供新靶点。

冠状动脉微栓塞是影响心肌功能和后期心血管事件的重要因素，既往研究发现miRs参与多种炎症和组织重构反应，但具体机制在冠状动脉微栓塞中的研究较少。本课题组通过结合动物模型和细胞培养的方式，发现，miR-19a可抑制心肌细胞内凋亡相关蛋白Bim实现抗凋亡的心肌保护作用；同时，过表达miR-19a抑制Bim表达后，自噬活化水平显著增加，而抑制自噬后miR-19a的抗凋亡心肌保护作用消失，说明miR-19a通过抑制Bim表达，进一步活化自噬实现心肌保护作用，提示自噬通路可能为防治微栓塞后持续缺氧微环境下心肌细胞凋亡的潜在靶点。同时，我们还发现缺氧刺激不仅诱导miR-19a下调，还导致其另一个相关靶蛋白NHE-1的表达升高，进一步引起钙负荷增加，加重凋亡，损伤心肌。这些分子机制研究将对冠状动脉微栓塞的临床防治提供新的思路。通过本次基金的资助，课题组顺利完成工作，发表SCI论文10篇（标注课题号），培养博士7名，其中两名参与者2015年在课题执行期间获得国家自然基金的资助。