差异表达微小核糖核酸-142-3p介导TLR4/NF-κB通路在冠状动脉微栓塞致心肌损伤中机制的研究

Coronary microembolism (CME) is an intractable complication in the treatment of PCI of coronary disease patients. Studies have proved that myocardial inflammation induced by CME is the main cause of myocardial damage. Recent studies have demonstrated the role of miRNA in the pathophysiological process of cardiovascular diseases, characterised by immune and inflammatory reactions. In our previous study we investigated the changes in global miRNA expression in response to CME using pig's heart, and found out that intracoronary injection of miR-142-3p with transfection reagent showed significantly improvement in cardiac function compared to CME group; Further onwards bioinformatics method was used to predict the potential target genes for miR-142-3p. The results showed that IRAK-1、TRAF-6 and MyD88, which were the key molecules among Toll-like receptor-4 (TLR4) signaling molecules, were the potential target genes for miR-142-3p, and suggested that miR-142-3p may be associated with the myocardial dysfunction resulting from CME by regulating TLR4 signaling pathway. However, the detailed mechanism involved still remains unclear. In the present study, with the method of intervention, we established an animal model of CME by using pig's heart. miR-142-3p analogue was synthesized and transfected to cardiomyocytes, then the activation of signaling pathway "miR-142-3p/TLR4/NF-κB/TNF-alpha" was detected to clarify the mechanism of differentially expressed miRNA-142-3p in myocardial injury resulting from coronary microembolism.

冠状动脉微栓塞(CME)是冠心病介入治疗中棘手并发症。研究表明，CME所致心肌炎症反应是引起心肌损伤的主要原因。新近研究证实微小核糖核酸(miRNAs)参与多种心血管免疫炎性疾病的病理生理过程。我们前期已筛选出CME猪心肌组织差异表达的miRNAs并发现，CME前将miR-142-3p转染心肌可明显改善心功能；进一步应用生物信息学方法分析，结果提示Toll样受体4(TLR4)信号通路中的关键分子IRAK-1、TRAF-6及MyD88为其潜在靶基因，说明miR-142-3p可能通过调控TLR4信号通路在CME致心肌损伤中发挥重要作用，但具体机制尚不清楚。因此，本项目拟经导管建立CME猪的动物模型，合成miR-142-3p模拟物并转染心肌组织，检测CME后“miR-142-3p/TLR4/NF-κB/TNF-α”信号通路的激活情况，以深入阐明miR-142-3p在CME致心肌损伤中的效应机制。

冠状动脉微栓塞（coronary microembolization，CME）是急诊经皮冠状动脉介入（primary percutaneous coronary intervention，pPCI）治疗过程中常见的并发症，其导致的心肌炎症是引起心肌损伤的主要原因。失调的microRNA（miR）-miR-142-3p与多种心血管疾病有关，我们前期测序发现miR-142-3p在CME引起的心肌损伤中显着下降。然而miR-142-3p在CME导致的心肌损伤中的作用和机制尚不清楚。本研究我们经微导管左前降支注入微栓塞球构建CME猪的动物模型，发现miR-142-3p在CME猪心肌组织中表达降低；miR-142-3p激动剂可以改善心功能并减轻CME引起的心肌炎症反应；miR-142-3p抑制剂加重CME导致的心肌损伤和CME引起的心肌炎症反应；双荧光素酶实验报告IRAK-1可能是miR-142-3p的直接靶基因；上调miR-142-3p和沉默IRAK-1可以降低心肌细胞NF-κB p65、TNF-α、IL-1β和IL-6水平。表明IRAK1是miR-142-3p下游的靶基因并且参与了CME致心肌炎症反应的过程，miR-142-3p可以通过调控其靶基因IRAK-1参与冠状动脉微塞致心肌损伤。此外，我们还研究了循环miR-142-3p水平与急性ST段抬高型心肌梗死（ST-segment elevation myocardial infarction, STEMI）患者pPCI中无复流的关系。通过Real-time PCR测量血浆miR-142-3p的水平。结果发现较低水平的miR-142-3p与接受pPCI的STEMI患者的无复流现象有关，miR-142-3p可能在无复流的发病机制中起重要作用。血浆miR-142-3p水平是STEMI患者pPCI术中无复流的独立预测因素，早期检测血浆miR-142-3p水平可以初步评估pPCI术中无复流的发生风险。我们的研究成果为临床开发miR-142-3p药物治疗和预防CME致心肌损伤提供了重要的理论依据。