Role of Extracellular MicroRNAs in Myocardial Ischemia-Reperfusion Injury

项目摘要 包括缺血性心肌梗死（MI）在内的心脏病仍然是20世纪90年代死亡的主要原因。 美国而再灌注治疗如经皮冠状动脉介入治疗仍然是最有效的策略 为了限制梗死面积和保护心脏功能，再灌注本身可对心肌造成致命损伤。在 心肌对缺血再灌注（I/R）的反应是释放各种危险分子，这些分子被证明是 对心脏有害。我们最近发现，细胞RNA，包括许多microRNA（miRNAs）， 在I/R期间从心脏释放细胞外RNA，并且细胞外RNA有助于心肌炎症和损伤。 我们的初步研究表明，从心脏中分离的RNA或单链miRNA模拟物 （miR-34，-122，-133a，-142，146 a，-208a）在心肌细胞、嗜中性粒细胞和巨噬细胞中诱导稳健的细胞因子应答。 巨噬细胞使用遗传缺失模型和药理学抑制剂，我们证明，在基于细胞的 实验表明，心脏RNA或microRNA模拟物特异性地通过先天性巨噬细胞诱导细胞因子产生。 免疫Toll样受体7（TLR 7）信号传导。该提案的总体目标是确定 本研究旨在探讨细胞外miRNAs在心肌I/R损伤中的作用及其分子机制。 该建议基于以下三个假设：1）miRNAs从损伤的心肌中释放 在I/R过程中发挥作用，并在心肌炎症和损伤中发挥作用，2）miRNA通过TLR 7信号传导发挥作用 在心肌细胞和嗜中性粒细胞中，3）在心肌细胞和嗜中性粒细胞中， 缺血性损伤将提供针对I/R损伤心脏保护。在具体目标1中，我们将确定 细胞外miRNAs在I/R期间心肌炎症和损伤中的作用在具体目标2中， 将测试TLR 7信号传导在I/R中miRNA介导的心肌炎症和损伤中的作用。在特定 目的3，我们将探索miRNA-TLR 7信号通路作为治疗糖尿病的潜在治疗靶点。 心肌I/R损伤。这些研究提出了细胞外miRNAs的一种独特的新功能， 心肌炎症和损伤，在缺血性心脏病的发病机制和治疗中具有重要意义。 心肌梗死

Project Summary Heart diseases including ischemic myocardial infarction (MI) continue to be the leading cause of mortality in the U.S. While reperfusion therapy such as percutaneous coronary intervention remains the most effective strategy to limit infarct size and preserve cardiac function, reperfusion itself can cause lethal injury to myocardium. In response to ischemia-reperfusion (I/R), myocardium releases various danger molecules that are proven to be harmful to the heart. We have recently identified that cellular RNAs including many microRNAs (miRNAs) are released from the heart during I/R and that extracellular RNA contributes to myocardial inflammation and injury. Our preliminary investigations demonstrate that RNA isolated from the heart or single-stranded miRNA mimics (miR-34, -122, -133a, -142, 146a, -208a) induce a robust cytokine response in cardiomyocytes, neutrophils, and macrophages. Using genetic deletion models and pharmacological inhibitors, we demonstrate, in cell-based assays, that cardiac RNAs or microRNA mimics induce cytokine production specifically through the innate immune Toll-like receptor 7 (TLR7) signaling. The over goals of this proposal are to determine the role of extracellular miRNAs in myocardial I/R injury and explore the underlying molecular mechanisms. The proposal is based on the following three hypotheses: 1) that miRNAs are released from injured myocardium during I/R and play a role in myocardial inflammation and injury, 2) that miRNAs act through TLR7 signaling in cardiomyocytes and neutrophils, 3) that pharmacological inhibition of miRNAs and TLR7 signaling after ischemic insult will offer cardio-protection against I/R injury. In Specific Aim 1, we will determine the contribution of extracellular miRNAs to myocardial inflammation and injury during I/R. In Specific Aim 2, we will test the role of TLR7 signaling in miRNA-mediated myocardial inflammation and injury in I/R. In Specific Aim 3, we will explore the miRNA-TLR7 signaling as a potential therapeutic target for the treatment of myocardial I/R injury. The proposed studies address a unique and novel function of extracellular miRNAs in myocardial inflammation and injury, with significant implications in pathogenesis and treatment of ischemic myocardial infarction.