血管紧张素转化酶2过表达对大鼠心肌梗死后心室重构的影响

Effect of angiotensin-converting enzyme 2 over-expression on ventricular remodeling in rat model of myocardial infarction

目的观察血管紧张素转化酶2(ACE2)过表达对大鼠急性心肌梗死(AMI)后心室重构的影响,并探讨其可能的分子机制。方法 75只SD大鼠随机分为假手术组(Sham组)、AMI组、生理盐水组(AMI+NS组)、报告基因组(AMI+AdEGFP组)和重组腺病毒AdACE2组(AMI+AdACE2组),每组15只。结扎大鼠冠状动脉左前降支建立AMI模型,AMI+NS、AMI+AdEGFP、AMI+AdACE2组于心肌梗死周边区各选取5个点分别注射生理盐水、AdEGFP和AdACE2,Sham组与AMI组不予注射。建模4周后测量血流动力学指标和心室质量;用组织学方法评价心肌组织结构变化与胶原沉积;用免疫组化染色检测心肌组织血管紧张素(Ang)Ⅱ(AngⅡ)、Ang-(1-7)及α-平滑肌肌动蛋白(α-SMA)表达,蛋白质印迹法检测心肌组织ACE2、Src同源结构域2蛋白酪氨酸磷酸酶1(SHP-1)、ERK1/2、p-ERK1/2、p38、p-p38、α-SMA及转化生长因子β1(TGF-β1)蛋白的表达。结果 (1)与其他4组相比,AMI+AdACE2组ACE2表达水平升高(P<0.05),同时Ang-(1-7)表达也升高(P<0.05)。(2)与Sham组相比,AMI、AMI+NS及AMI+AdEGFP组左室舒张末压,心室质量/体质量比值,胶原沉积,梗死周边区AngⅡ、Ang-(1-7)、SHP-1、p-ERK1/2/ERK1/2、p-p38/p38、α-SMA、TGF-β1表达均升高(P<0.05)。(3)与AMI、AMI+NS及AMI+AdEGFP组相比,AMI+AdACE2组Ang-(1-7)、SHP-1表达升高(P<0.05),p-ERK1/2/ERK1/2、p-p38/p38、α-SMA及TGF-β1表达降低(P<0.05)。结论过表达ACE2可明显改善大鼠心肌纤维化进程,缓解心室重构,其机制可能与ACE2激活酪氨酸磷酸酶SHP-1,负性调节肾素-血管紧张素系统(RAS)下游丝裂原活化蛋白激酶(MAKPs)活性有关。

Objective To investigate the effect of angiotensin-converting enzyme 2 （ACE2） over-expression on ventricular remodeling in rat model of acute myocardial infarction （AMI） and the related mechanisms. Methods Totally 75 male Sprague- Dawley rats were randomly divided into five groups （n： 15）： Sham group, AMI group, AMid-normal saline （AMId-NS） group, AMI ＋ adenovirus-EGFP （AMI ＋ AdEGFP） group, and AMI ＋ adenovirus-ACE2 （AMI ＋ AdACE2） group. AMI models were established by ligating the left anterior descending coronary artery of rats. Rats in the AMI＋ NS, AMI4-AdEGFP and AMI＋AdACE2 groups received intramyocardial injection of NS, AdEGFP and AdACE2 in five different infarction border zones, respectively. Rats in the Sham and AMI groups received no injection intervention. Four weeks later, left ventricular end-diastolic pressure （LVEDP） and heart weight/body weight （HW/BW） were examined. Myocardial structure changes and collagen deposition were evaluated histopathologically. The expression of angiotensin （Ang） Ⅱ （Ang Ⅱ ）, Ang-（1-7） and a-smooth muscle actin （α-SMA） proteins was assessed by immunohistochemical staining. The relative protein expression of ACE2, Src homology 2 domain-containing protein tyrosine phosphatase 1 （SHP-1）, ERK1/2, p-ERK1/2, p38, p-p38,α-SMA and transforming growth factor 131 （TGF-131） was measured by Western blotting analysis. Results （1） Compared with the otherfour groups, the protein expression levels of ACE2 and Ang-（ 1 7） were significantly increased in myocardial tissues in AMIα-AdACE2 group （P〈0.05）. （2） Compared with the Sham group, LVEDP, the values of HW/BW, collagen deposition, and the expression levels of AnglI, Ang （1-7）, SHP1, p-ERK1/2/ERK1/2, l〉p38/p38, α-SMA and TGFβ1 were all signficantly upgraded in AMI, AMI＋ NS and AM1 ＋ AdEGFP groups （ P〈0.05 ）. （3） Compared with AMI, AMI ＋ NS and AMI ＋ AdEGFP groups, the expression levels of Ang-（1-7） and SHP-1 were significantly increased in AMI ＋AdACE2 group （P〈 0. 05）; while α-ERK1/2/ERK1/2, ＋p38/p38, α-SMA and TGF-β protein expression levels were significantly decreased in AMI＋AdACE2 group （P〈0.05）. Conclusion This study suggests that over-expression of ACE2 can improve ventricular fibrosis and ameliorate ventricular remodeling after myocardial infarction in rats, which may be due to that ACE2 increases SHP-1 protein expression, and the latter negatively regulates renin-angiotensin system （RAS） and mitogen activated protein kinases （MAKPs） pathway.