Abstract
Ischemic heart disease in children may be induced by varied factors, and there is no corresponding systematic treatment up to now. This study aims to investigate the effects of microRNA (miR)-148 on myocardial injury in immature rats with myocardial ischemia-reperfusion (MI/R) injury. In this study, MI/R model was established by ligating the coronary artery of heart. The results showed that miR-148 alleviated myocardial injury and rescued relevant parameters (mean ventricular systolic blood pressure (MAP), left ventricular systolic blood pressure (LVSP), heart rate (HR), creatine kinase-MB (CK-MB), cTn1 and Mb in immature rats with MI/R injury. Besides, miR-148 improved the immune dysfunction induced by MI/R through increasing the number of interleukin (IL)-10+ cells and reducing the number of inducible nitric oxide synthase (iNOS)+ cells. In addition, miR-148 relieved the apoptosis of cardiomyocytes induced by MI/R through inhibiting the expression of Bax and elevating the expression of Bcl-2. Further molecular mechanism indicated that pyruvate dehydrogenase kinase 4 (PDK4) was the downstream target of miR-148, which was further confirmed by dual luciferase reporter assay and related expression detection. Accordingly, silenced PDK4 attenuated cardiac dysfunction, immune disorder and myocardial apoptosis in immature rats and enhanced the ability of antioxidant enzymes. What is more, activated SMAD pathway induced by MI/R injury was then blocked by silenced PDK4. Taken together, our study demonstrated that overexpressed miR-148 relieved cardiac dysfunction, immune disorder and cardiomyocyte apoptosis in immature MI/R rats by PDK4 inhibition, which provided novel targets for MI/R injury treatment.