Cardiomyocyte Enhancing Cardiac Fibroblast Collagen Production In The Pathogenesis Of Diabetic Cardiomyopathy

Objective:To determine whether cardiomyocytes paticipate in the pathogenesis of diabetic cardiomyopathy by affecting the function of cardiac fibroblast.To explore the molecular mechanism of the role of extracellular HMGB1/TLR4/IL-33 signal axis in myocardial fibrosis formation in diabetes.Methods:(1)Setting up in vivo STZ model of diabetes;(2)Isolating cardiac myocytes(CM) and cardiac fibroblasts(CF), and setting up CF and CM co-culture system;(3)Using imunofluorescence staining and irius red staining to detect the expression of HMGB1 and IL-33, and the degree of fibrosis in the STZ model of diabetes;(4)Using Western blotting and ELISA kit to detect the effect and molecular mechanisms of cardiomyocyte-induced enhancement of collagen production of cardiac fibroblast in the pathogenesis of diabetic cardiomyopathy. Results:(1)In STZ mice, HMGB1 expression in cardiomyocyte was increased while IL-33 expression was decreased. HMGB1 inhibitor A-box or exogenous IL-33 prevented the myocardial collagen deposition and dysfunction of the cells.(2)In the cardiomyocyte/fibroblast co-culture model, HG increased cardiomyocyte HMGB1 secretion, decreased fibroblast IL-33 expression,and increased fibroblast collagen I production.(3)In the cardiomyocyte/fibroblast co-culture model, cardiomyocyte-derived HMGB1 dramatically potentiated the HG-induced down regulation of IL-33 and the increase of collagen I expression in the fibroblasts treated with A-Box.(4)The potentiating effects of the cardiomyocytes was diminished when toll-like receptor 4 deficient(TLR4-/-) fibroblasts were co-cultured with wild-type myocytes. Conclusions:The results suggest that in both STZ model of diabetes and in vitro simulated diabetes, diabetic high glucose induces cardiomyocytes to express and release HMGB1 and to promote myocardial fibrosis and pathgenesis of diabetic crdimyopthy through extracellular HMGB1/TLR4/IL-33 sinaling axis.