BACKGROUND Reperfusion may cause injuries to the myocardium in ischemia situation. Emerging studies suggest that exosomes may serve as key mediators in myocardial ischemia/reperfusion (MI/R) injury. OBJECTIVE The study was conducted to figure out the mechanism of M2 macrophage-derived exosomes (M2-exos) in MI/R injury with the involvement of microRNA-148a (miR-148a). METHODS AND RESULTS M2 macrophages were prepared and M2-exos were collected and identified. Neonatal rat cardiomyocytes (NCMs) were extracted for in vitro hypoxia/reoxygenation (H/R) model establishment, while rat cardiac tissues were separated for in vivo MI/R model establishment. Differentially expressed miRNAs in NCMs and H/R-treated NCMs after M2-exos treatment were evaluated using microarray analysis. The target relation between miR-148a and thioredoxin-interacting protein (TXNIP) was identified using dual luciferase reporter gene assay. Gain- and loss- of function studies of miR-148a and TXNIP were performed to figure out their roles in MI/R injury. Meanwhile, the activation of the TLR4/NF-κB/NLRP3 inflammasome signaling pathway and pyroptosis of NCMs were evaluated. M2 macrophages carried miR-148a into NCMs. Over-expression of miR-148a enhanced viability of H/R-treated NCMs, reduced infarct size in vivo, and alleviated dysregulation of cardiac enzymes and Ca2+ overload in both models. miR-148a directly bound to the 3'-untranslated region (3'UTR) of TXNIP. Over-expressed TXNIP triggered the TLR4/NF-κB/NLRP3 signaling pathway activation and induced cell pyroptosis of NCMs, and the results were reproduced in in vivo studies. CONCLUSION This study demonstrated that M2-exos could carry miR-148a to mitigate MI/R injury via down-regulating TXNIP and inactivating the TLR4/NF-κB/NLRP3 inflammasome signaling pathway. This study may offer new insights into MI/R injury treatment.

中文翻译：

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M2巨噬细胞衍生的外来体携带microRNA-148a，通过抑制TXNIP和TLR4 /NF-κB/ NLRP3炎性体信号通路来减轻心肌缺血/再灌注损伤。

背景技术在缺血情况下，再灌注可能导致心肌损伤。新兴研究表明，外泌体可能是心肌缺血/再灌注（MI / R）损伤的关键介质。目的进行研究以找出M2巨噬细胞衍生的外泌体（M2-exos）在microRNA-148a（miR-148a）参与下的MI / R损伤中的机制。方法和结果制备了M2巨噬细胞，并收集和鉴定了M2-外泌体。提取新生大鼠心肌细胞（NCM）用于体外缺氧/复氧（H / R）模型建立，而分离大鼠心脏组织用于体内MI / R模型建立。使用微阵列分析评估了M2-exos处理后NCM和经H / R处理的NCM中差异表达的miRNA。使用双重荧光素酶报告基因检测鉴定了miR-148a与硫氧还蛋白相互作用蛋白（TXNIP）之间的靶标关系。对miR-148a和TXNIP进行了功能获得和丧失研究，以了解它们在MI / R损伤中的作用。同时，评估了TLR4 /NF-κB/ NLRP3炎性小体信号通路的激活和NCM的热解。M2巨噬细胞携带miR-148a进入NCM。在两种模型中，miR-148a的过表达增强了经H / R处理的NCM的生存力，体内的梗死面积减小以及减轻了心脏酶的失调和Ca2 +超负荷。miR-148a直接结合到TXNIP的3'-非翻译区（3'UTR）。过表达的TXNIP触发了TLR4 /NF-κB/ NLRP3信号通路的激活并诱导了NCM的细胞凋亡，其结果在体内研究中得到了再现。结论这项研究表明，M2-exos可以通过下调TXNIP并使TLR4 /NF-κB/ NLRP3炎性体信号通路失活来携带miR-148a减轻MI / R损伤。这项研究可能为MI / R损伤治疗提供新的见解。