The Role And Mechanism Of Asprosin In Myocardial Injury Induced By T2DM

Background and ObjectiveAt present,cardiovascular diseases have become the leading cause of death in China.In addition,with the development of society,the incidence rate and mortality rate of cardiovascular diseases are still increasing.Cardiovascular complications caused by diabetes are considered to be an important cause of this social crisis.Diabetes mellitus is mainly divided into type 1 diabetes mellitus(T1DM),type 2 diabetes mellitus(T2DM),gestational diabetes mellitus(GDM)and other special types,which are characterized by abnormal increase level of blood glucose.China is the world’s largest country of diabetes,a large number of patients cause serious harm and heavy economic burden on individuals and society.The main harm of diabetes is that it can lead to a variety of acute and chronic complications in multiple organs.Among them,diabetic cardiomyopathy(DCM)is one of the main cardiac complications and the main cause of death in diabetics.However,the current status of clinical treatment of DCM is not ideal,mainly because its pathogenesis is still not fully understood.Therefore,it is necessary to study the pathogenesis of myocardial injury caused by diabetes and find the appropriate therapeutic target.At present,it is believed that white adipose tissue can not only store energy,but also secrete a variety of adipose factors,participate in the physiological process of the body,and is closely related to the pathogenesis of various diseases included DCM.Therefore,it is of great significance for the prevention and treatment of DCM to explore the mechanism of regulating DCM by fat factors.Asprosin is a newly discovered adipose factor in recent years which is mainly produced by white adipose tissue of the body.Asprosin can be transported to the whole body through the blood,exert various effects such as regulating blood sugar,regulating insulin resistance,promoting appetite and increasing body fat content.In addition,it is closely related to the pathogenesis of various metabolic diseases and cardiovascular diseases,however,its role in DCM is not clear.Our previous studies confirmed that the plasma level of asprosin increased significantly in T2DM mice.In view of this,we speculate that asprosin may be involved in the pathogenesis of DCM,but whether it can be used as a regulatory target of DCM needs further study.Previous studies suggested that oxidative stress injury caused by high glucose has played an important role in the process of DCM.Hyperglycemia in diabetic patients can increase ROS(reactive oxygen species)production in cardiomyocyte through various channels,and later may cause mitochondrial oxidative stress injuries.Besides,MDA(malondialdehyde)is a lipid peroxidation product,and it’s generated after ROS triggers fatty acids on cell membranes.Therefore,it can be used as a signal of the speed and activity of lipid oxidation metabolism in vivo,and indirectly indicated the concentration of ROS in the cells.Thus,the higher the MDA content,the higher the ROS content,and the more serious the damage to the body.For reasons given above,oxidative stress is an important pathological basis of T2DM,but it is not clear whether asprosin can regulate oxidative stress injury of cardiomyocytes induced by high glucose.Therefore,this topic is mainly to discuss whether asprosin can play a role in the pathogenesis of DCM via affecting oxidative stress.The above research suggest that both asprosin and oxidative stress injury may play an important role in the pathogenesis of DCM.So what signaling pathway does asprosin in plasma regulate mitochondrial oxidative stress injury in high glucose environment? The cAMP(cyclic adenosine monophosphate)/PKA(Protein kinase A)signal transduction pathway,as a classical signal transduction pathway in cells,involved in the pathogenesis of cardiac hypertrophy,heart failure,diabetic myocardial damage and other diseases by regulating oxidative stress injury.Not only that,the cAMP/PKA signal transduction pathway also participates in the regulation of asprosin on glucose metabolism in liver cells.However,whether the regulation of asprosin on cardiomyocytes in high glucose environment is via cAMP/PKA signal transduction pathway has not been reported.Therefore,making further study of this problem,not only helps to reveal the cardiovascular effect of asprosin,but also provides a new theoretical support for the prevention and treatment of DCM.This research is mainly divided into four steps.First,to establish the T2DM model of mice,and to detect the level of asprosin in mouse plasma.Next,to observe whether asprosin can mediate the damage of MCMs caused by high glucose.Thirdly,to explore whether the effect of asprosin on MCMs in high glucose environment is through the classic way of oxidative stress.Finally,to observe whether asprosin in plasma play a role in cardiomyocytes through cAMP/PKA pathway.Methods1.The mice model of T2DM was established by high fat diet combined with small dose intraperitoneal injection of streptozotocin.In order to confirm whether T2DM mouse model was successfully constructed,the glucose tolerance and insulin sensitivity in mice were tested,and serum biochemical indexes were detected by automatic biochemical analyzer.Then the heart function of mice in each group was detected by small animal ultrasound,and myocardial fibrosis was detected by Masson staining.Finally,the level of asprosin in plasma was detected by ELISA kit.2.The neonatal mouse was used to culture primary cardiomyocytes,and its purity were identified by α-actinin immunofluorescence staining.Then,the cell model of T2DM was established by the intervention of high glucose.In order to confirm whether MCMs model of T2DM was successfully constructed,MCMs apoptosis was detected by flow cytometry,and the cell viability was measured by CCK-8 kit.After that,the effect of asprosin on MCMs under high glucose condition was studied.3.Further more,asprosin was used to intervene on MCMs in high glucose condition.Then the level of ROS was detected by DHE staining and ELISA kit,and MDA concentration was detected by MDA detection kit.The effect of asprosin on hydrogen peroxide(H2O2)-induced cell damage was further studied to explore whether the effects of asprosin on MCMs play a role by regulating oxidative stress pathway.4.The concentration of cAMP and PKA was detected by ELISA kit after asprosin intervention on MCMs in high glucose environment.The effect of H89 intervention on asprosin was further tested to determine whether asprosin plays a role in regulation of MCMs through cAMP/PKA signal transduction pathway.Results1.The mice model of T2DM was successfully constructed by high fat diet combined with streptozotocin injection.Compared with control group,T2DM group had significantly higher blood glucose,more myocardial fibrosis,and diastolic dysfunction,but normal systolic function;Compared with normal mice,the content of asprosin in plasma of T2DM mice increased significantly.2.The primary cardiomyocytes was successfully constructed by neonatal mouse,and the cell model of T2DM was successfully established.Compared with the control group(NG group),the activity of MCMs in high glucose group(Hg group)decreased significantly,and apoptosis increased significantly;The apoptosis rate of MCMs induced by high glucose was reduced by asprosin and the cell viability was increased.What’s more,with the increase of asprosin intervention concentration,the protective effect was increasing.3.The level of MDA and ROS in MCMs in high glucose environment could be reduced by asprosin,and the injury of cardiomyocytes induced by hydrogen peroxide was improved by asprosin.4.Asprosin can increase the content of cAMP and PKA;PKA specific inhibitor H89 can increase the damage of cardiomyocytes caused by high glucose and reverse the protective effect of white fat on MCMs in high glucose environment.ConclusionT2DM can damage cardiomyocytes,lead to myocardial fibrosis and diastolic dysfunction,and the plasma asprosin concentration of T2DM mice increased significantly;The activity of MCMs decreased and apoptosis increased under the condition of high glucose,while asprosin could play a protective role by inhibiting oxidative stress induced by high glucose,and the protective effect of asprosin depended on cAMP/PKA pathway.