miR-145-5p attenuates inflammatory response and apoptosis in myocardial ischemia-reperfusion injury by inhibiting (NADPH) oxidase homolog 1.

Myocardial ischemia-reperfusion (I/R) injury is a common complication following reperfusion therapy that involves a series of immune or apoptotic reactions. Studies have revealed the potential roles of miRNAs in I/R injury. Herein, we established a myocardial I/R model in rats and a hypoxia/reoxygenation (H/R) model in H9c2 cells and investigated the effect of miR-145-5p on myocardial I/R injury. After 3 h or 24 h of reperfusion, left ventricular end-systolic pressure (LVESP), ejection fraction (EF), and fractional shortening (FS) were obviously decreased, and left ventricular end-diastolic pressure (LVEDP) was increased. Meanwhile, I/R induced an increase in myocardial infarction area. Moreover, a decrease in miR-145-5p and increase in (NADPH) oxidase homolog 1 (NOH-1) were observed following I/R injury. With this in mind, we performed a luciferase reporter assay and demonstrated that miR-145-5p directly bound to NOH-1 3' untranslated region (UTR). Furthermore, miR-145-5p mimics decreased the levels of tumor necrosis factor (TNF)-α, IL-1β, and IL-6 via oxygen and glucose deprivation/reperfusion (OGD/R) stimulation. Upregulation of miR-145-5p increased cell viability and reduced apoptosis accompanied by downregulation of Bax, cleaved caspase-3, cleaved poly(ADP-ribose) polymerase (PARP) and upregulation of Bcl2. In addition, miR-145-5p overexpression increased superoxide dismutase (SOD) activity and reduced reactive oxygen species (ROS) and malondialdehyde (MDA) content under OGD/R stress. Notably, NOH-1 could significantly abrogate the above effects, suggesting that it is involved in miR-145-5p-regulated I/R injury. In summary, our findings indicated that miR-145-5p/NOH-1 has a protective effect on myocardial I/R injury by inhibiting the inflammatory response and apoptosis.