Liu Xiang, Chen Yijiang, Wu Yanhu, Ha Tuanzhu, Li Chuanfu
Department of Cardiothoracic Surgery, the First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
J Biomed Res. 2010 Jul;24(4):324-31. doi: 10.1016/S1674-8301(10)60045-0.
The mechanisms by which lipopolysaccharide (LPS) pretreatment induces cardioprotection following ischaemia/reperfusion (I/R) have not been fully elucidated. We hypothesized that activation of phosphoinositide 3-kinase (PI3K)/Akt and high mobility group box 1 (HMGBx1) signaling plays an important role in LPS-induced cardioprotection.
In in vivo experiments, age- and weight- matched male C57BL/10Sc wild type mice were pretreated with LPS before ligation of the left anterior descending coronary followed by reperfusion. Infarction size was examined by triphenyltetrazolium chloride (TTC) staining. Akt, phospho-Akt, and HMGBx1 were assessed by immunoblotting with appropriate primary antibodies. In situ cardiac myocyte apoptosis was examined by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. In an in vitro study, rat cardiac myoblasts (H9c2) were subdivided into two groups, and only one was pretreated with LPS. After pretreatment, the cells were transferred into a hypoxic chamber under 0.5% O2. Levels of HMGBx1 were assessed by immunoblot.
In the in vivo experiment, pretreatment with LPS reduced the at risk infarct size by 70.6% and the left ventricle infarct size by 64.93% respectively. Pretreatment with LPS also reduced cardiac myocytes apoptosis by 39.1% after ischemia and reperfusion. The mechanisms of LPS induced cardioprotection involved increasing PI3K/Akt activity and decreasing expression of HMGBx1. In the in vitro study, pretreatment with LPS reduced the level of HMGBx1 in H9c2 cell cytoplasm following hypoxia.
The results suggest that the cardioprotection following I/R induced by LPS pretreatment involves PI3K/Akt and HMGBx1 pathways.
脂多糖（LPS）预处理诱导缺血/再灌注（I/R）后心脏保护的机制尚未完全阐明。我们假设磷酸肌醇3-激酶（PI3K）/蛋白激酶B（Akt）和高迁移率族蛋白B1（HMGBx1）信号通路的激活在LPS诱导的心脏保护中起重要作用。
在体内实验中，将年龄和体重匹配的雄性C57BL/10Sc野生型小鼠在结扎左冠状动脉前降支并再灌注前用LPS预处理。通过氯化三苯基四氮唑（TTC）染色检查梗死面积。用适当的一抗通过免疫印迹法评估Akt、磷酸化Akt和HMGBx1。通过末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）法检测原位心肌细胞凋亡。在体外研究中，将大鼠心肌成肌细胞（H9c2）分为两组，仅一组用LPS预处理。预处理后，将细胞转移到含0.5%氧气的缺氧箱中。通过免疫印迹法评估HMGBx1的水平。
在体内实验中，LPS预处理分别使危险梗死面积减少70.6%，左心室梗死面积减少64.93%。LPS预处理还使缺血再灌注后心肌细胞凋亡减少39.1%。LPS诱导心脏保护的机制包括增加PI3K/Akt活性和降低HMGBx1的表达。在体外研究中，LPS预处理降低了缺氧后H9c2细胞质中HMGBx1的水平。
结果表明，LPS预处理诱导的I/R后心脏保护涉及PI3K/Akt和HMGBx1信号通路。
