IL-6受体拮抗剂改善心肌梗死后室性心律失常的作用及机制初探

Preliminary study on the role and mechanism of IL-6 receptor antagonists in improving post-infarction ventricular arrhythmia

目的:探讨白细胞介素-6(IL-6)受体拮抗剂托珠单抗(TCZ)对Sprague-Dawley大鼠心肌梗死(MI)后室性心律失常的改善作用及潜在机制。方法:选取成年雄性Sprague-Dawley大鼠32只,按照随机数表法分为4组:假手术组、TCZ组、MI组和MI+TCZ组,每组8只。MI组和MI+TCZ组大鼠通过结扎冠状动脉左前降支建立MI模型,假手术组和TCZ组大鼠仅穿线不结扎。TCZ组和MI+TCZ组大鼠于建模成功或假手术后在左侧颈上神经节注射TCZ,假手术组和MI组给予等量生理盐水注射。建模后24 h,记录各组大鼠心电图,计算心率变异性(包括低频功率、高频功率、低频功率/高频功率比值)和QT间期、QTc间期,并测量左心室有效不应期和室性心律失常诱发数。通过2,3,5-氯代三苯基四氮唑染色和HE染色观察各组大鼠心肌梗死面积及组织改变。通过实时荧光定量聚合酶链反应检测大鼠颈上神经节中IL-6、信号转导子和转录激活子(STAT)3的信使RNA(mRNA)及MI周边区组织钾电压门控通道亚家族D成员2(potassium voltage-gated channel subfamily D member 2,Kcnd2)的mRNA表达水平。采用免疫荧光染色检测大鼠颈上神经节的即刻早期基因的表达。结果:与假手术组和MI+TCZ组大鼠相比,MI组大鼠低频功率和低频功率/高频功率比值较高、QT间期与QTc间期较长、室性心律失常诱发数较多,而高频功率较低、左心室有效不应期较短( P均<0.05)。2,3,5-氯代三苯基四氮唑染色和HE染色显示,假手术组和TCZ组大鼠心肌组织结构正常,MI组大鼠心肌损伤严重,MI+TCZ组与MI组相比心肌损伤较轻。实时荧光定量聚合酶链反应显示,与假手术组和MI+TCZ组相比,MI组大鼠颈上神经节中 IL-6、STAT3的mRNA表达水平较高,心肌Kcnd2的mRNA表达水平较低( P均<0.05)。免疫荧光染色显示,MI组大鼠颈上神经节中即刻早期基因含量比假手术组和MI+TCZ组大鼠高( P均<0.05)。 结论:IL-6受体拮抗剂可能通过抑制IL-6/STAT3信号通路降低MI后颈上神经节的神经活性,减轻心肌损伤,抑制室性心律失常发生。

ObjectiveTo investigate the effect of tocilizumab(TCZ)on ventricular arrhythmias(VAs)after myocardial infarction(MI)in Sprague-Dawley rats and explore its potential mechanism.MethodsThe random number table method was used to divide 32 adult male Sprague-Dawley rats into 4 groups:Sham group,TCZ group,MI group and MI+TCZ group,with 8 rats in each group.The MI model was established by ligation of the left anterior descending branch of the coronary artery in the MI and MI+TCZ groups,and only sutured without ligation in the Sham and TCZ groups.TCZ was injected into the left superior cervical ganglion(SCG)of rats in the TCZ and MI+TCZ groups after successful modeling or sham operation,and the same amount of normal saline was injected in the Sham and MI groups.24 h after successful modeling,ECG of rats in each group was recorded,heart rate variability(HRV,including low frequency power(LF),high frequency power(HF),LF/HF ratio),QT interval,QTc interval were calculated,and left ventricular effective refractory period(ERP)and VA inducibility were measured.Myocardial infarct size and tissue changes were observed with triphenyl tetrazolium chloride staining and HE staining.Real-time PCR analysis was used to detect the messager RNA(mRNA)expression of interleukin-6(IL-6)and signal transducer and activator of transcription(STAT)3 in SCG and potassium voltage-gated channel subfamily D member 2(Kcnd2)in myocardial infarction periphery.The expression of c-fos in SCG was detected by immunofluorescence staining.ResultsCompared with Sham group and MI+TCZ group,rats in MI group had higher LF and LF/HF ratio,longer QT interval and QTc interval,more VAs induced,lower HF and shorter ERP(P all<0.05).Triphenyl tetrazolium chloride staining and HE staining showed that rats in the Sham and TCZ groups had normal myocardial tissue structure,those in the MI group had severe myocardial injury,and those in the MI+TCZ group had less myocardial injury than those in the MI group.Real-ime PCR analysis showed that compared with Sham group and MI+TCZ group,mRNA expression levels of IL-6 and STAT3 in SCG of rats in MI group were higher,and mRNA expression level of myocardial Kcnd2 was lower(P all<0.05).Immunofluorescence staining showed that the content of c-fos in SCG of rats in MI group was higher than that of Sham group and MI+TCZ group(P all<0.05).ConclusionsTCZ may reduce neural activity of the SCG after MI by inhibiting the IL-6/STAT3 signaling pathway,thereby alleviating myocardial injury and inhibiting VAs.