Glycyrrhizin improves cardiac function in rheumatic heart disease by regulating Cx43 through miRNA-223

Abstract

Rheumatic heart disease (RHD) is a typical and relapsing autoimmune disease that damages heart valve. In this study, glycyrrhizin was used to intervene RHD mouse model to explore the role of glycyrrhizin in RHD and underlying mechanism. The RHD mouse model was successfully established and divided into 7 groups as follows: healthy group, RHD group, miR-223 antagonist group, miR-223 agonist group; glycyrrhizin group and glycyrrhizin+agonist group, and glycyrrhizin+miR-223 antagonist group. After treatment, cardiac function was evaluated by weighing the heart, echocardiography, and observing cardiomyocytes with Masson staining and hematoxylin-eosin staining (HE) staining. Real Time Quantitative (RT-qPCR) and Western blot determined miR-223 and Cx43 expressions and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, Thiazolyl Blue Tetrazolium Bromide (MTT) assessed proliferation rate after transfection. The cardiac function, as well as cardiomyocyte morphology of the glycyrrhizin group were significantly improved (P <0.05). Importantly, additional treatment with miR-223 antagonist further improved cardiac function, dramatically decreasing left ventricular end-diastolic dimension (LVEDD) and Left Ventricular End Systolic Diameter (LVESD). Besides, glycyrrhizin treatment decreased miR-223 expression while increasing Cx43 expression, compared with RHD group. Combination of miR-223 antagonist and glycyrrhizin obtained the highest level of Cx43. Anti-miR-223+pcDNA-Cx43 group had the lowest proliferation rate and highest apoptosis rate of mouse RHD cells. Glycyrrhizin inhibited miR-223 and increased Cx43 expression to strengthen cardiac function and restrict progression of RHD mice, which is an intervention target for RHD.