氧化三甲胺促进M1型巨噬细胞极化加剧心肌梗死后心室重构

Trimethylamine oxide promotes polarization of M1 macrophages and exacerbates ventricular remodeling after myocardial infarction

目的观察氧化三甲胺(TMAO)对心肌梗死(MI)小鼠心功能及巨噬细胞极化的影响。方法将雄性C57BL/6小鼠随机分为Sham、MI和MI+TMAO组。采用左前降支结扎法建立MI模型,MI+TMAO组小鼠术后喂食高胆碱饮食。术后21 d,检测血清TMAO的变化,应用Masson染色检测心肌梗死面积、TUNEL染色检测凋亡细胞,并检测CK⁃MB、cTnT的水平。通过心脏超声检测心功能、WGA染色分析心肌肥大程度,检测NT⁃proBNP和血清炎症因子IL⁃6、TNF⁃α的水平,荧光染色检测心肌细胞缝隙连接蛋白Cx43的表达,并通过RT⁃qPCR检测梗死周边区M1型巨噬细胞标志物(IL⁃6、TNF⁃α和INOS)及M2型巨噬细胞标志物(CD206、IL⁃10和TGF⁃β)的表达水平。结果(1)高胆碱饮食使MI小鼠血浆TMAO水平显著升高,TMAO增加MI小鼠心梗面积,促进心肌坏死标志物CK⁃MB和cTnT释放,促进心肌细胞凋亡。(2)TMAO促进MI小鼠心功能下降、心肌肥大。(3)TMAO显著减少心肌细胞之间的连接完整性。(4)TMAO显著增加M1型巨噬细胞标志物的表达。结论TMAO通过促进M1型巨噬细胞极化加剧MI小鼠心肌损伤及心室重构。

Objective This study was to investigate the effects of trimethylamine N⁃oxide(TMAO)on cardiac function and macrophage polarization in mice with myocardial infarction(MI).Methods Male C57BL/6 mice were randomly divided into the Sham,MI,and MI+TMAO groups.For the MI model,mice were subjected to permanent left anterior descending ligation.After the surgery,mice in the MI+TMAO group were fed high choline diet,while those in the Sham and MI groups were fed chow diet.Twenty⁃one days later,serum TMAO levels and the levels of CK⁃MB and cTnT were detected.The infarct size of myocardial tissue was detected by Masson staining,and the expression of apoptotic cells was detected by TUNEL staining.Echocardiography,WGA staining and NT⁃proBNP were used to analyze the degree of cardiac function and hypertrophy.Immunofluorescence staining was used to detect the expression of Cx43.Furthermore,the expressions of serum inflammatory factors(IL⁃6,TNF⁃α)were detected by Elisa.RT⁃qPCR was used to detect M1 macrophage markers(IL⁃6,TNF⁃αand INOS)and M2 macrophage markers(CD206,IL⁃10 and TGF⁃β)in myocardial tissues,respectively.Results(1)High choline diet significantly increased plasma TMAO levels in MI mice,and TMAO promoted infarction size and myocardial enzymes as well as apoptosis in MI mice.(2)TMAO limited cardiac function and promoted ventricular hypertrophy in MI mice.(3)The results of Cx43 immunofluorescence staining indicated that TMAO significantly reduced the connection integrity between cardiomyocytes.(4)The mRNA levels of M1 macrophage markers in MI+TMAO group were significantly higher than those in MI group.On the contrary,the mRNA levels of M2 macrophage markers CD206,IL⁃10 and TGF⁃βwere significantly reduced in MI+TMAO group compared with MI group.Conclusion TMAO aggravated myocardial tissue injury and ventricular remodeling in MI mice by promoting M1⁃type macrophage polarization.