Objective To investigate the effect of SIRT3 deficiency on myocardiac injury induced by lipopolysaccharide(LPS)in sepsis and its mechanism.Methods SIRT3gene knockout(SIRT3-/-)mice and wild-type(WT)mice were intraperitoneally injected with LPS(10mg/kg)for 24h to prepare myocardial injury model of sepsis,and equal volume normal saline(NS)was injected intraperito-neally as control,WT-NS group,WT-LPS group,SIRT3-/--LPS group and SIRT3-/--NS group were set up.Human heart micro-vascular endothelial cells were stimulated with LPS(10μg/ml)for 24h to prepare cell damage models.Normal culture was used as con-trol,SIRT3 overexpressing lentivirus and negative control virus were used for cell transfection.Control group,LPS group,LPS+SIRT3 overexpressing group and negative control virus group were set up.The left ventricular posterior wall thickness at the end of systole and di-astole and the left ventricular end-diastolic volume were measured by cardiac ultrasound.Sirius red staining was used to detect collagen content in heart tissue of each group.The expression of endothelial-to-mesenchymal transition(EndMT)markers in cardiac microves-sels,which involved platelet-endothelial cell adhesion molecule(CD31)and α-smooth muscle actin(α-SMA)was observed by im-munofluorescence method.Western blot was used to detect the expression of CD31,α-SMA and SIRT3 proteins and autophagy related proteins LC3 and p62.Results Cardiac ultrasound showed that the left ventricular end-diastolic volume,end-systolic and end-dias-tolic posterior wall thickness increased in the SIRT3-/--LPS group(P＜0.001).The results of sirius red staining showed that SIRT3 defi-ciency significantly increased the collagen content of LPS-induced heart tissue of mice(P＜0.001).LPS could induce EndMT in cardiac microvascular endothelial cells of mice,which was aggravated by SIRT3deficiency(P＜0.05).The level of autophagy in heart tissue of mice was stress increased,which was induced by LPS treatment.However,SIRT3deficiency could reduce autophagy level(P＜0.05).In vitro experiments also confirmed that LPS induced increased autophagy stress in human heart microvascular endothelial cells(P＜0.001),and decreased SIRT3 protein expression was accompanied by the occurrence of EndMT(P＜0.05).The overexpression of SIRT3 significantly re-duced the degree of EndMT(P＜0.001),and the autophagy level was further increased(P＜0.05).Conclusion SIRT3 deficiency can aggravate the degree of cardiac diastolic dysfunction and fibrosis in LPS-induced sepsis mice,and the mechanism may be related to inhibi-ting the autophagy level of heart tissue and promoting the development of EndMT in cardiac microvascular endothelial cells.
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