miR-342-3p靶向Dectin-1调控巨噬细胞极化参与心肌缺血再灌注损伤的作用及其机制研究

Mounting evidence suggested that inflammation and immune response play an important role in myocardial ischemia reperfusion (IR) injury. Pro-inflammatory M1 macrophages and neutrophils accumulated early and contributed to myocardial IR injury. Our previous studies have shown that: Dectin-1 was highly expressed in the macrophage but not neutrophil in the heart, leading to macrophage polarization towards M1 phenotype and chemokines expression associated with neutrophil recruitment, resulting in myocardial IR injury. Therefore, Dectin-1 may be the novel therapeutic target against myocardial IR injury. By software prediction and validation study, we demonstrated that miR-342-3p negatively regulated Dectin-1 expression, and infarct size (Evans blue/TTC staining) and cardiac function (assessed by echocardiography) were significantly improved in miR-342 transgenic mice after myocardial IR, compared with wild type mice, suggesting that miR-342-3p critically involved in myocardial IR injury by targeting Dectin-1 expression and regulating macrophage polarization. Thus, based on these findings, the present study aimed to further explored: 1) The molecular mechanisms for inflammatory cytokines in regulating miR-342-3p expression; 2) Whether miR-342-3p regulates macrophage polarization through targeting Dectin-1, does it contribute to myocardial IR injury, and the underlying molecular mechanisms. 3) The clinical relevance of plasma miR342-3p in patients with acute myocardial infarction. Lastly, we will examine plasma levels of miR342-3p in patients with acute myocardial infarction, and further explore the relationship between miR342-3p and infarct size assessed by magnetic resonance image (MRI). Our findings will provide new therapeutic target for ischemic heart disease.

炎症免疫反应在心肌缺血再灌注（IR）损伤中起到重要作用。缺血早期心脏聚集的促炎性M1巨噬细胞和中性粒细胞参与心肌IR损伤。我们研究发现：心肌IR早期巨噬细胞表达Dectin-1，促进其向M1极化和表达中性粒细胞趋化因子，促进中性粒细胞向心脏聚集，共同介导心肌IR损伤。因此，Dectin-1有望成为心肌IR损伤新的治疗靶点。进一步靶点预测和验证发现miR-342-3p负向调控Dectin-1表达，且miR-342转基因小鼠心肌IR后心功能较野生型显著改善，提示miR-342-3p靶向Dectin-1调控巨噬细胞极化参与心肌IR损伤。因此，本课题将继续探索：1）炎症因子调控miR-342-3p表达及其分子机制；2）miR-342-3p靶向Dectin-1调控巨噬细胞极化参与心肌IR损伤及其机制；3）血浆miR-342-3p水平与临床急性心梗相关性。为防治缺血性心脏病提供新的治疗策略和干预靶点。

模式识别受体Dectin-1可影响巨噬细胞极化和中性粒细胞聚集，加重心肌缺血再灌注（IR）损伤。我们通过靶点预测和验证发现，微小RNA miR-342-3p可负向调控Dectin-1表达，然而其具体作用尚不明确。本研究旨在探索miR-342-3p在心肌IR损伤过程中的表达和作用机制。.研究建立小鼠IR损伤模型，通过流式细胞术、Langendorff技术和siRNA手段，明确miR-342-3p的表达和调控机制。而后运用miR-342转基因小鼠、腺病毒转染、特异性抑制剂，以及骨髓移植手段，通过细胞培养、流式细胞学技术、小动物心超、荧光定量PCR及免疫印迹等方法探究miR-342-3p靶向巨噬细胞Dectin-1对机体炎症状态、心肌损伤和心功能的影响。.研究结果显示，miR-342-3p主要表达于巨噬细胞，心肌IR损伤后心脏及外周血中miR-342-3p表达水平降低，炎症因子可通过IKKα/IKKβ/NEMO经NF-κB抑制miRNA-342-3p表达。而miRNA-342-3p可靶向巨噬细胞Dectin-1，影响巨噬细胞向M1极化和中性粒细胞聚集，减少促炎细胞因子和趋化因子的产生，从而使IR损伤后梗死面积减小、心功能改善。.miRNA-342-3p靶向模式识别受体Dectin-1，在心肌IR损伤中发挥了重要的保护性功能，为急性心肌梗死和缺血性心肌病提供了新的治疗策略，具有重要的转化医学价值。