Study On The Role And Mechanism Of Caspase-1-mediated Pyroptosis In Sepsis-induced Myocardial Injury

Objective:To investigate the role of caspase-1-mediated pyroptosis in sepsis-induced myocardial injury and its possible mechanism Methods:1.Male C57BL/6 mice,6-8w,the cecum ligation of puncture(Cecal ligation and puncture,CLP)was used to build model of sepsis,samples were collected at 0h,8h,16 h and 24 h after modeling,and the degree of myocardial injury was assessed by pathological examination.2.6-8w male C57BL/6 mice were divided into three groups: control group,model group,and intervention group.The cecal puncture and ligation(CLP)was used to construct a sepsis model in model group;in the control group,only laparotomy was performed,and cecal ligation was not performed;in the intervention group,an inhibitor of caspase-1(Ac-YVAD-cmk)was intraperitoneally injected 1 hour before CLP.Samples were collected at 24 h after modeling,Hematoxylin-eosin staining(HE)and scanning electron microscopy were performed.Enzyme linked immunosorbent assay(ELISA)was used to compare the levels of IL-6 ?CK-MB and cTn-I in the homogenized myocardium of the three groups,and the expression levels of IL-1??Caspase-1 and GSDMD in the myocardium of the three groups were detected by Western Blot(WB).Results: 1.After CLP operation,the mice showed lethargy,lack of luster in hair,significantly reduced activity,and increased eye secretions accompanied by diarrhea2.Hematoxylin-eosin staining results showed that at 8h after CLP,the myocardial tissue of mice presented slight edema,complete myocardial cell structure,and no obvious inflammatory cell infiltration.At 16 h after CLP operation,the myocardial tissue edema in mice aggravated the tissue gap widening,and a small amount of myocardial cells were damaged and asmall amount of inflammatory cells were infiltrated.At 24 h after CLP operation,the myocardial tissue of the mice was seriously edema,and the tissue space was significantly widened.A large number of myocardial cells were damaged,and a large number of inflammatory cells were infiltrated3.Hematoxylin-eosin staining results showed that the myocardial tissue of the control group was normal,without edema and inflammatory cell infiltration,the cells were closely arranged,and the tissue space was normal.In the model group,there was severe edema in the myocardial tissue,and the interstitial space was obviously widened.In the intervention group,the degree of myocardial tissue edema was less,the tissue gap was wider,and a small number of myocardial cells were injured and a small number of inflammatory cells were infiltrated4.Transmission electron microscopy showed that the mitochondrial membrane structure of cardiomyocytes in the model group was largely destroyed,the mitochondrial crest disappeared,and a large number of floating lipid droplets were observed in the cells.In the control group,the mitochondrial structure of the cardiomyocytes was intact,and the mitochondrial intima showed obvious ridge structure.The degree of myocardial cell damage in the intervention group was between that of the control group and that of the model group.In the control group,the myocardial membrane was relatively flat and the membrane structure was intact.The degree of myocardial cell damage in the intervention group was between that of the control group and that of the model group.5.Enzyme linked immunosorbent assay results showed that,compared with the control group,the contents of IL-6?CK-MB and cTn-I in the myocardial tissue homogenate of the model group were significantly increased(P<0.05).The contents of IL-6?CK-MB and cTnI in the myocardial tissue homogenate of the intervention group were between the control group and the model group(all P<0.05).6.Western Blot results showed that,compared with the control group,the expression levels of il-1 caspase-1 and GSDMD in the model group were significantly increased(P<0.05),while the expression levels of il-1 caspase-1 and GSDMD in the intervention group were between the control group and the model group(all P<0.05).Conclusion:Pyroptosis mediated by Caspase-1 is involved in the occurrence and development of CLP-induced myocardial injury in mice,and blocking the Caspase-1 pathway can alleviatemyocardial injury...