MiR-330-5p inhibits NLRP3 inflammasome-mediated myocardial ischaemia-reperfusion injury by targeting TIM3.

Abstract

The Nod-like receptor protein-3 (NLRP3) inflammasome signalling pathway is involved in the inflammatory reaction of myocardial ischaemia-reperfusion (I/R) injury. Our previous study showed that miR-330-5p was differentially expressed in both cerebral and myocardial I/R injury, and thus might be a biomarker for I/R injury-related diseases. Another study also indicated that miR-330-5p could promote NLRP3 inflammasome activation in renal IRI. However, the role of miR-330-5p in myocardial I/R injury-induced inflammatory responses is unknown. This study aimed to investigate the role of miR-330-5p in NLRP3 inflammasome-mediated myocardial I/R injury. Myocardial I/R injury was induced in mice by occlusion of the left anterior descending coronary artery for 45min followed by reperfusion. For NLRP3 inflammasome stimulation in vitro, cardiomyocytes were treated with 2h of oxygen and glucose deprivation (OGD) or LPS (100ng/ml). Myocardial miR-330-5p expression was examined by PCR at different treatment times. A miR-330-5p antagomir and an agomir were used to regulate miR-330-5p expression. To evaluate the role of miR-330-5p in myocardial I/R injury, 2,3,5-triphenyltetrazolium chloride (TTC) staining, echocardiography, and immunoblotting were used to assess infarct volume, cardiac function, and NLRP3 inflammasome activation respectively. A luciferase binding assay was used to examine whether miR-330-5p could directly bind to the T cell immunoglobulin domain and mucin domain-containing molecule-3 (TIM3). Finally, the role of the miR-330-5p/TIM3 axis in regulating apoptosis and NLRP3 inflammasome formation was evaluated with flow cytometry assays and immunofluorescence staining. Compared to that in the model group, the inhibition of miR-330-5p significantly aggravated myocardial I/R injury, resulting in increased infarct volume and more severe cardiac dysfunction. Moreover, inhibition of miR-330-5p significantly increased the levels of NLRP3 inflammasome-related proteins, including caspase-1, IL-1β, IL-18 and TNF-α, in both in-vivo and in-vitro models. Furthermore, TIM3 was confirmed as a potential target of miR-330-5p. As predicted, suppression of TIM3 by siRNA ameliorated the anti-miR-330-5p-mediated activation of the NLRP3 inflammasome induced by OGD and LPS, thus decreasing cardiomyocyte apoptosis. Our study indicated that the miR-330-5p/TIM3 axis was involved in the regulatory mechanism of NLRP3 inflammasome-mediated myocardial inflammation.