Yang Hai-Tao, Li Li-Li, Li Song-Nan, Wu Jin-Tao, Chen Ke, Song Wei-Feng, Zhang Guo-Bao, Ma Ji-Fang, Fu Hai-Xia, Cao Sheng, Gao Chuan-Yu, Hu Juan
Heart Center of Henan Provincial People's Hospital, Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, China.
Central Laboratory, Renmin Hospital of Wuhan University, Wuhan, China.
Cardiovasc Diagn Ther. 2022 Jun;12(3):325-339. doi: 10.21037/cdt-21-743.
Degradation of pro-inflammatory macrophage-mediated connexin 43 (Cx43) plays an important role in post-myocardial infarction (MI) arrhythmogenesis, microRNA (miR)-155 produced by macrophages has been shown to mediate post-MI effects. We hypothesized that miR-155 inhibition attenuated MI-induced Cx43 degradation by reducing pro-inflammatory macrophage activation.
MI was induced by permanent ligation of the left anterior descending coronary artery in male C57BL/6 mice. Lipopolysaccharide (LPS)-stimulated mice bone marrow-derived macrophages (BMDMs) and hypoxia-induced neonatal rat cardiomyocytes (NRCMs) were used models. qRT-PCR, Western-blot and immunofluorescence were used to analyze relevant indicators.
The expression levels of miR-155, interleukin-1 beta (IL-1β), and matrix metalloproteinase (MMP)7 were higher in MI mice and LPS-treated BMDMs than in the sham/control groups, treatment with a miR-155 antagomir reversed these effects. Moreover, miR-155 inhibition reduced ventricular arrhythmias incidence and improved cardiac function in MI mice. Cx43 expression was decreased in MI mice and hypoxia-exposed NRCMs, and hypoxia-induced Cx43 degradation in NRCMs was reduced by application of conditioned medium from LPS-induced BMDMs treated with the miR-155 antagomir, but increased by conditioned medium from BMDMs treated with a miR-155 agomir. Importantly, NRCMs cultured in conditioned medium from LPS-induced BMDMs transfected with small interfering RNA against IL-1β and MMP7 showed decreased hypoxia-mediated Cx43 degradation, and this effect also was diminished by BMDM treatment with the miR-155 agomir. Additionally, siRNA-mediated suppressor of cytokine signaling 1 (SOCS1) knockdown in LPS-induced BMDMs promoted Cx43 degradation in hypoxia-exposed NRCMs, and the effect was reduced by the miR-155 inhibition.
MiR-155 inhibition attenuated post-MI Cx43 degradation by reducing macrophage-mediated IL-1β and MMP7 expression through the SOCS1/nuclear factor-κB pathway.
促炎性巨噬细胞介导的连接蛋白43（Cx43）降解在心肌梗死后（MI）心律失常的发生中起重要作用，巨噬细胞产生的微小RNA（miR）-155已被证明可介导心肌梗死后的效应。我们假设miR-155抑制通过减少促炎性巨噬细胞活化来减轻MI诱导的Cx43降解。
通过永久性结扎雄性C57BL/6小鼠的左冠状动脉前降支诱导MI。使用脂多糖（LPS）刺激的小鼠骨髓来源的巨噬细胞（BMDM）和缺氧诱导的新生大鼠心肌细胞（NRCM）作为模型。采用qRT-PCR、蛋白质免疫印迹和免疫荧光分析相关指标。
MI小鼠和LPS处理的BMDM中miR-155、白细胞介素-1β（IL-1β）和基质金属蛋白酶（MMP）7的表达水平高于假手术/对照组，用miR-155拮抗剂处理可逆转这些效应。此外，miR-155抑制降低了MI小鼠室性心律失常的发生率并改善了心脏功能。MI小鼠和缺氧暴露的NRCM中Cx43表达降低，用miR-155拮抗剂处理的LPS诱导的BMDM的条件培养基可减少缺氧诱导的NRCM中Cx43的降解，但用miR-155激动剂处理的BMDM的条件培养基可增加其降解。重要的是，在转染了针对IL-1β和MMP7的小干扰RNA的LPS诱导的BMDM的条件培养基中培养的NRCM显示缺氧介导的Cx43降解减少，并且用miR-155激动剂处理BMDM也会减弱这种效应。此外，在LPS诱导的BMDM中，siRNA介导的细胞因子信号传导抑制因子1（SOCS1）敲低促进了缺氧暴露的NRCM中Cx43的降解，而miR-155抑制可降低这种效应。
miR-155抑制通过SOCS1/核因子-κB途径减少巨噬细胞介导的IL-1β和MMP7表达，从而减轻MI后Cx43的降解。
