左西孟旦调控LOX-1/p38 MAPK通路减轻冠状动脉微栓塞后心肌损伤

目的:探讨左西孟旦（levosimendan，Levo）对冠状动脉微栓塞（coronary microembolization, CME）后心肌损伤和LOX-1/p38 MAPK信号通路的影响。方法:采用随机数字表法将24只巴马小型猪随机分为假手术组（Sham组）、CME组、CME+左西孟旦预治疗+对照腺相关病毒转染组（CME+Levo+NC组）及CME+左西孟旦预治疗+ LOX-1过表达腺相关病毒转染组（CME+Levo+LOX-1组），每组6只。经冠脉介入法于前降支注射栓塞微球构建CME模型；Sham组则注射等量生理盐水代替。CME+Levo+NC组和CME+Levo+LOX-1组于造模前2周分别转染对照病毒和LOX-1过表达病毒，并均于造模前24 h开始持续静滴左西孟旦。心脏超声检测心功能指标；苏木精-伊红（HE）染色和苏木精碱性复红-苦味酸（HBFP）染色分别用于观察心肌组织病理改变和心肌微梗死区域；酶联免疫吸附测定（ELISA）用于检测血清肌钙蛋白I（cTnI）；脱氧核糖核苷酸末端转移酶介导的缺口末端标记法（TUNLE）检测心肌细胞凋亡率；免疫荧光观察心肌组织LOX-1、Bcl-2、Bax、Caspase-3 p12和p-p38 MAPK蛋白表达情况。多组间比较采用单因素方差分析，组间两两比较采用LSD- t检验。以 P<0.05为差异有统计学意义。 结果:⑴与Sham组比较，CME组小型猪左心室射血分数（LVEF） [（69.73±4.79）% vs （47.18±2.33）%， P<0.05]、左心室短轴缩短率（LVFS） [（42.47±2.54）% vs （21.43±1.76）%， P<0.05]、心输出量（CO）[（4.42±0.27）L/min vs （2.57±0.17）L/min， P<0.05]均显著下降，而左心室舒张期末径（LVEDd）[（32.37±1.33）mm vs （41.21±1.86）mm， P<0.05]显著增加，心肌微梗死面积占比[（3.73±0.87）% vs （20.72±2.49）%， P<0.05]显著增加，血清cTnI水平[（51.92±16.62）pg/mL vs （236.80±19.56）pg/mL， P<0.05]显著升高，心肌细胞凋亡率[（1.15±0.47）% vs （14.15±3.24）%， P<0.05]显著升高，心肌组织Bax、Caspase-3 p12、LOX-1和p-p38 MAPK蛋白表达明显上调（均 P<0.05），Bcl-2蛋白表达明显下调（ P<0.05）。⑵与CME组比较，CME+Levo+NC组小型猪LVEF[（47.18±2.33）% vs （55.48±3.92）%， P<0.05]、LVFS[（21.43±1.76）% vs （32.02±1.75）%， P<0.05]、CO[（2.57±0.17）L/min vs （3.45±0.25）L/min， P<0.05]均显著升高，而LVEDd[（41.21±1.86）mm vs （36.78±1.56）mm， P<0.05]显著下降，心肌微梗死面积占比[（20.72±2.49）% vs（11.63±3.12）%， P<0.05]显著减小，血清cTnI水平[（236.80±19.56）pg/mL vs （157.40±15.13）pg/mL， P<0.05]显著降低，心肌细胞凋亡率[（14.15±3.24）% vs （8.33±1.28）%， P<0.05]显著下降，心肌组织Bax、Caspase-3 p12、LOX-1和p-p38 MAPK蛋白表达明显下调（均 P<0.05），Bcl-2蛋白表达明显上调（ P<0.05）。⑶与CME+Levo+NC组比较，CME+Levo+LOX-1组小型猪LVEF[（55.48±3.92）% vs（48.52±1.69）%， P<0.05]、LVFS[（32.02±1.75）% vs （23.80±2.51）%， P<0.05]、CO[（3.45±0.25）L/min vs （4.25±0.23）L/min， P<0.05]均显著降低，而LVEDd[（36.78±1.56）mm vs （41.12±1.57）mm， P<0.05]显著增加，心肌微梗死面积占比[（11.63±3.12）% vs （18.93±1.58）%， P<0.05]显著增加，血清cTnI水平[（157.40±15.13）pg/mL vs （244.40±15.97）pg/mL， P<0.05]显著升高，心肌细胞凋亡率[（8.33±1.28）% vs （12.28±1.93）%， P<0.05]显著增加，心肌组织Bax、Caspase-3 p12、LOX-1和p-p38 MAPK蛋白表达明显上调（均 P<0.05），Bcl-2蛋白表达明显下调（ P<0.05）。 结论:左西孟旦可通过抑制LOX-1/p38 MAPK信号通路介导的心肌细胞凋亡而减轻CME后心肌损伤。

Levosimendan alleviates coronary microembolization-induced myocardial injury through LOX-1/p38 MAPK pathway

Objective:To study the effect of levosimendan on coronary microembolization (CME)-induced myocardial injury and LOX-1/p38MAPK pathway.Methods:Microspheres were injected into coronary anterior descending branch to construct swine CME model, swine was given levosimendan by continuous intravenous drip for 24 h before modeling, and myocardial-specific overexpression of lectin-like oxidized low density lipoprotein receptor 1 (LOX-1) was achieved through coronary artery injection of adeno-associated virus (AAVs) at 2 weeks before modeling. Then, echocardiography was used to measure cardiac function; HE staining and HBFP staining were used to observe the pathological changes of myocardium and myocardial microinfarction area, respectively; ELISA was used to detect the serum level of cTnI; TUNLE staining was used to detect cardiomyocyte apoptotic index; the LOX-1, Bax, caspase-3 p12, Bcl-2, and p-p38 MAPK protein in myocardial tissue was observed by immunofluorescence method.Results:Compared to the sham group, the LVEF, LVFS, and CO value in the CME group were decreased, while the LVEDd value was increased significantly (all P<0.05); the area of myocardial micro-infarction, serum cTnI level and cardiomyocyte apoptotic rate in the CME group were increased significantly (all P<0.05); the protein levels of Bax, caspase-3 p12, LOX-1, and p-p38 MAPK were increased significantly, while the Bcl-2 level was decreased significantly ( P<0.05). Levosimendan pretreatment significantly improved cardiac dysfunction, reduced the area of myocardial micro-infarction and serum cTnI level, alleviated cardiomyocyte apoptosis, and significantly reduced the LOX-1 and p-p38 MAPK protein expression levels following CME (all P<0.05); while pretreatment with levosimendan and LOX-1 overexpression AAVs simultaneously abolished the effects of pretreatment with levosimendan alone (all P<0.05). Conclusion:Levosimendan alleviates CME-induced myocardial injury through inhibiting cardiomyocyte apoptosis mediated by LOX-1/p38 MAPK signaling pathway.