The Role And Mechanism Of RELMβ In Diabetic Cardiomyopathy

Objective:Diabetic cardiomyopathy(DCM)is a diabetic-induced cardiomyopathy.Diabetes mellitus leads to abnormal metabolism in vivo,which leads to abnormal changes in myocardial structure and function.Diabetic cardiomyopathy is one of the main causes of death in diabetic patients.RELM beta belongs to resistin-like molecular family proteins.Recent studies have found that RELM beta plays an important role in diabetic cardiovascular disease.This study will first explore the changes of RELM beta expression in cardiac tissue of diabetic cardiomyopathy rats.Methods:100 male Sprague-Dawley(SD)rats weighing 120 g(+20 g)were divided into four groups:A:control group;B:high-fat group;C:normal diet+STZ injection group(STZ group);D:high-fat group+STZ injection group(and diabetic model group).Rats in the control group were fed with normal diet and only injected with nonnal saline;rats in the high-fat group were fed with high-sugar,high-fat and high-calorie diet and injected with normal saline after 4 weeks;rats in the STZ group were fed with normal diet and injected with 27.5 mg/kg STZ after 4 weeks;rats in the diabetic model group were fed with high-sugar,high-fat and high-calorie diet and injected with 27.5 mg/kg STZ after 4 weeks.After 12 weeks,the animals were executed and their hearts were taken out for subsequent testing.The dynamic changes of body weight,blood pressure,blood sugar,blood lipids,glucose tolerance test and insulin tolerance test were monitored,and the occurrence and development of diabetic cardiomyopathy were monitored by high-resolution microsonography.The expression of RELM beta in myocardium was detected by PCR and Western blot.Results:Compared with the control group,the weight/weight of heart,water intake,food intake and urine volume of DM group rats increased significantly;the weight of heart and water intake of high fat group rats increased significantly;compared with the control group,the weight of heart,weight/weight of heart,water intake,food intake,urine volume and urine volume of diabetic rats increased significantly.Left ventricular end-diastolic pressure increased significantly.Compared with the control group,the blood glucose values and the area under the blood glucose curve of diabetic rats at different time points in IPGTT and IPITT tests were significantly increased;compared with STZ rats on normal diet,the blood glucose of diabetic rats increased significantly at 60、90 minutes and 120 minutes.Compared with the control group,the blood sugar of rats in the high-fat group increased significantly.Compared with the control group,the left ventricular end-diastolic diameter(LVEDd),interventricular septal thickness(IVSs),left ventricular posterior wall thickness(LVPWs),left ventricular mass(LVmass)and left ventricular volume(LVvol)were significantly increased in STZ group,and the isovolumetric diastolic time(IVRT),isovolumetric systolic time(IVCT)and Tei index were significantly prolonged,while EF,FS and E’/A’were all decreased.Compared with the control group,LVPWs and LVmass increased,IVRT,IVCT and Tei index prolonged and E’/A’decreased in the hyperlipidemia group,and left ventricular end-diastolic diameter(LVEDd)and left ventricular mass decreased in the diabetic group.The interventricular septal thickness(IVSs),left ventricular posterior wall thickness(LVPWs),left ventricular mass(LVmass)and left ventricular volume(LVvol)were significantly increased,isovolumetric diastolic time,isovolumetric systolic time and Tei index were significantly prolonged,EF,FS and E’/A’were significantly decreased,and left ventricular mass and isovolumetric diastolic volume were significantly increased in diabetic rats compared with those in hyperlipidemia rats.Time and isovolumetric contraction time prolonged significantly.The results of integrated backscatter ultrasonography showed that the IB%of ventricular septum(IVSs),left ventricular posterior wall(LVPWs)and left ventricular lateral wall(LVL)in diabetic rats were significantly increased and CVIB was significantly decreased compared with control rats;compared with control rats,the IB%of ventricular septum and left ventricular lateral wall in STZ group was significantly increased,and the IB%of ventricular septum and left ventricular posterior wall was significantly increased.Compared with the high fat group,the IB%of the interventricular septum,the posterior wall and the lateral wall of the left ventricle in the diabetic group increased significantly,and the CVIB decreased significantly。The expression of RELM beta in myocardium of high fat group(P<0.01),STZ group(P<0.01)and diabetic model group(P<0.001)were significantly increased by PCR and Western blot,especially in diabetic model group.Conclusions:(1)Glucose metabolism and cardiac function of diabetic rats were impaired in varying degrees.(2)The expression of RELM beta in myocardium of diabetic rats increased significantly.Background: The results of Chapter 1 showed that the expression of RELM beta in cardiac tissue of diabetic cardiomyopathy rats increased significantly.In order to clarify whether RELM beta mediates the pathogenesis of diabetic cardiomyopathy,we will silence RELM beta gene in the animal model of DCM,investigate its effects on apoptosis,myocardial fibrosis,collagen synthesis and degradation,and inflammatory response,and explore key signal transduction pathways and key proteins to clarify the effect of RELM beta on myocardium.Molecular mechanism of action of cells and cardiac fibroblasts.Combined with in vivo and in vitro experiments,the mechanism of RELM beta gene silencing improving DCM was further explored from the aspects of overall functional level and graded biology.Methods: 100 male SD rats weighing 120 g(+20 g)were divided into four groups: A: control group;B: high fat group + STZ injection group(and diabetes model group);C: diabetic model group + empty vector group(jugular vein injection empty virus vector);D: diabetic model group + RELM beta gene silencing group(jugular vein injection slow silencing of RELM beta gene)Two weeks later,group C and group D were injected again.The myocardial tissue was stained with Masson and Sirius red.Immunohistochemistry,PCR and Western blot were used to detect the expression of fibroblast,inflammatory,apoptotic and TGF-beta signal-related factors.Results: Compared with diabetic group,the heart weight/weight,water intake,food intake and urine volume of diabetic + RELM beta silence group decreased significantly,while the heart weight and water intake of hyperlipidemia group decreased significantly.Compared with diabetic rats,diabetes + RELM beta silence group significantly decreased the blood glucose value and the area under the blood glucose curve at different time points in IPGTT and IPITT tests.Compared with diabetic rats,E’/A’in diabetes + RELM beta silence group began to rise,LVEF and FS were improved,and left ventricular diameter,interventricular septum thickness,left ventricular posterior wall thickness,left ventricular mass and left ventricular volume were significantly reduced,isovolumetric diastolic time,isovolumic systolic time and Tei index were significantly decreased-Shorten.Masson and Sirius red staining showed that type I and type III collagen fibers increased significantly in myocardium of diabetic rats,but RELM beta silence inhibited the increase of collagen fibers.Immunohistochemistry,PCR and Western blot showed that the levels of type I collagen(P < 0.001),type III collagen(P < 0.001),IL-lbeta(P < 0.001),TNF-alpha(P < 0.001),Bax(P < 0.01)? brain natriuretic peptide(P < 0.01),TGF-beta(P < 0.01)and p-Smad3(P < 0.01)in the myocardium of diabetic rats increased significantly,while the levels of Bcl-2(P < 0.01)protein increased significantly.White level decreased significantly.The transfection empty vector had no significant effect on these indicators.However,compared with the diabetic model group,silence of RELM beta gene inhibited the levels of type I collagen(P < 0.01),type III collagen(P < 0.001),IL-lbeta(P < 0.001),TNF-alpha(P< 0.001),Bax(P < 0.01),brain natriuretic peptide(P < 0.01),TGF-beta(P <0.01)and p-Smad3(P < 0.01)in the myocardium of diabetic rats,and increased the levels of Bcl-2(P < 0.01).Protein water.ConcIusions:(l)RELMbeta silence can effectively improve glycometabolism and cardiac function in diabetic rats;(2)Type I and III collagen fibers in myocardium of diabetic rats increased significantly,indicating that diabetes contributes to myocardial fibrosis;(3)RELM beta silence inhibits fibrogenesis,inflammation and apoptosis in myocardium of diabetic rats.(4)RELM beta may regulate myocardial fibrosis in diabetic rats by activating TGF-beta signal.