Role Of Irisin In Inhibiting High Glucose-Induced Endothelial-to-Mesenchymal Transition And Its Dose-Dependent Bidirectional Effect On Diabetic Cardiomyopathy

Aim:Irisin has shown beneficial effects in diabetes and many studies indicates its emerging outcomes..But there is not much work done that explains the correlation of irisin and diabetic cardiomyopathy and the effect of diabetic induced cardiac fibrosis.So in our study we aim to show the relationship and the effect of irisin on diabetic cardiomyopathy and cardiac fibrosis in mice.Methods:We divided our study in to two parts,the in vivo and the in vitro study to see the effect of r-irisin.In the vivo study,we purchased 8 weeks old C57/BL6J mice weighing 25-30 grams from animal center of shandong university.These mice were randomly divided into four groups as;group 1 NG:Normal Glucose,group 2 DM:Diabetes Mellitus,group 3 low dose r-irisin treated,group 4 high dose r-irisin treated group respectively.Diabetes was induced in group 2,3 and 4 by intraperitoneal injection of streptozotocin(STZ).Group 3 was treated with 0.5?g/g per body weight per day and group 4 with 1.5?g/g per body weight per day for 16 weeks and then were sacrificed.Blood analysis was done for measuring total cholesterol,triglycerides,HDL,LDL and FBG.Echocardiography was performed to evaluate the cardiac functions,Manson's Trichrome for the accumulation of total collagen,picosirius red staining for the expression of several proteins,including collagen ? and collagen ?,transforming growth factor ?1 effectors,matrix metallo proteinases(MMPs)2 and 9 respectively,and P38 mitogen-activated protein kinase(MAPK)and ERK which is also known as extracellular-regulated protein kinase,these were all quantified through immuostaining and western blotting.In the vitro study,HUVEC cells were purchased from American Type Culture Collection(ATCC,Manassas,VA,USA)and cultured.It was also divided into four groups as NG:normal glucose(5mmol/l),HG:33 mmol/1 glucose,HG+irisin(20 nmol/1)and HG+irisin(40 nmol/1).Similarly,cardiac fibroblasts(CFs)were isolated from ventricles of 1-3 day old neonatal mice and were incubated with different concentrations of r-irisin and exposed to NG(5mmol/l)and HG(33 mmol/1)for 24-48 hours.Immunoflurescence,flow cytometery,migration and EDU Assay were performed to evaluate the effect of r-irisin on HUVECs and CFs.Results:In vitro the irisin treatment did not alter the plasma glucose concentrations in diabetic mice,but the echocardiography and histopathological results indicated that the low dose irisin alleviated fibrosisin heart and the function of the left ventricle in the diabetic mice.Whereas,high dose irisin treated group failed to mitigate impaired ventricular function and increased collagen acceration.The potential mechanism triggering the effect of low-dose irisin involved irisin-facilitated inhibition of high glucose-induced endothelial-to-mesenchymal transition(EndMT).Conversely,in vivo,high dose irisin treatment resulted in enhanced high glucose-induced MMP expression by stimulating MAPK(P38 and ERK)signaling and cardiac fibroblast proliferation and migration.CONCLUSION:Low-dose irisin alleviatedDCM development by inhibiting high glucose-induced EndMT.By contrast,high-dose irisin disrupteddistinctive MMPexpressionand induced cardiac fibroblast proliferation and migration,which results in excess collagen deposition.Thus,irisin can inhibit high glucose-induced EndMTandexert a dose-dependent bidirectional effect on DCM.