A Novel Role Of CCR2 In Diabetic Cardiomyopathy

Part ? The effect of CCR2 knockout on diabetic cardiomyopathyObjective:Diabetes mellitus is a group of chronic metabolic diseases characterized by chronic hyperglycemia.Heart is one of the most common organs involved in diabetes.The incidence of heart failure in diabetic patients is significantly higher than that in non-diabetic patients.An increasing number of studies have indicated that chemokine receptors take part in the pathophysiology of various diseases.However,their role and mechanism in diabetic cardiomyopathy are litter known.Here,we investigated the expression of chemokine receptor 2(CCR2)and its effect on cardiac function in diabetic cardiomyopathy.Methods C57 aged 8-10 weeks were randomly divided into two groups,as is CCR2 knockout mice.The C57 control group was injected with citric acid buffer as the CCR2 knockout control group,and the other two groups were treated with STZ injection for the diabetic group.Body weight and random blood glucose were recorded continuously.Cardiac function was detected by ultrasonography and hemodynamics six months after STZ or citric acid buffer injection.The expression of CCR2 in the hearts of the four groups was detected by real-time quantitative PCR,Western blotting and immunohistochemistry.Total cholesterol and triglyceride in the serum were analyzed by automatic biochemical analyzer.The morphology of myocardial tissue and cells was observed by HE staining and WGA staining,and the collagen content was assessed by Masson staining.Results The mRNA and protein levels of CCR2 were increased in diabetic cardiomyopathy.We found that CCR2 knockout did not affect blood glucose,but improved glucose tolerance,reduced heart body ratio,and improve survival rate in diabetic cardiomyopathy mice.CCR2 knockout had no effects on the size of myocardial cells,but decreased the breaks of myocardial fiber,inhibited the collagen deposition,and improved the cardiac function in diabetic cardiomyopathy.Conclusion:The expression of CCR2 is up-regulated in the heart of diabetic cardiomyopathy,and CCR2 knockout protect the myocardial structure and function of diabetic mice.Part ? Mechanism of CCR2 in diabetic cardiomyopathyObjective:Our investigations of Part ? have demonstrated thatCCR2 knockout improves cardiac dysfunction in diabetic cardiomyopathy,and the underlying mechanisms were further explored in this part.Methods:CCR2 knockout on the expression of myocardial fibrosis markers in diabetic cardiomyopathy were analyzed by real-time quantitative,Western blot and immunohistochemistry.At the same time,the NADPH oxidase activity and the expression of oxidative stress markers were measured.In addition,we investigated the effects of CCR2 knockdown on myocardial apoptosis in diabetic cardiomyopathy by TUNEL staining and the ratio of apoptosis related factors Bax and Bcl-2 and the expression of caspase-3.And we detected the expression of macrophage marker F4/80 by immunofluorescence;we analyzed effect of CCR2 knockout on the number of macrophages in diabetic myocardium and the macrophage polarization using flow cytometry and real-time quantitative PCR.Finally,we studied the upstream regulatory transcription factors of CCR2 and the specific binding sites.Results:Knockdown of CCR2 could inhibit myocardial fibrosis in diabetic cardiomyopathy;at the same time CCR2 knockout reduced myocardial oxidative stress through inhibition of NADPH oxidase activity,contents of 4-HNE and 3-NT;CCR2 knockout reduced the expression of F4/80 and the number of macrophages in diabetic cardiomyopathy,and made the myocardial macrophage polarization to M1;and we found that the transcription factor Nkx2.5 regulated the expression of CCR2,and it can be directly combined with CCR2 promoter.Conclusion:CCR2 knockout mice may improve myocardial function in diabetes by preventing Infiltration of inflammatory cells and inhibition of myocardial fibrosis and oxidative stress,and CCR2 in these processes may be regulated by the transcription factor Nkx2.5.Part ? The changes of CCR2 in in patients with diabetes mellitusObjective:The aim is to investigate the expression of CCR2 in patients with diabetes mellitusMethods:141 patients with diabetes mellitus and 20 healthy controls were enrolled in the present study.We assessed expression of CCR2 on monocytes by Flow cytometry.Results:CCR2%on monocytes is fluctuated around(57.5±9.9)in healthy controls and(62.1±14.6)in patients with diabetes mellitus of HbA1C<8%.And CCR2%on monocytes in patients with diabetes mellitus of HbAiC>8%were significantly higher than in healthy controlsConclusion:The expression of CCR2 on monocytes isolated from diabetic patients was significantly higher than that in healthy controls.