衰老心肌缺血/再灌注损伤增加的新机制—程序性坏死的关键作用

Supplemental mechanism of increased reperfusion injury in senescent myocardial ischemia: significant role of necroptosis

目的探讨程序性坏死（necroptosis）在衰老心肌缺血/再灌注（I/R）损伤中的关键作用。 方法成年（ 3-4月龄）和老龄（ 22-24月龄）雄性C57BL/6小鼠20只各随机分为对照组与I/R组，建立小鼠急性心肌I/R模型（缺血30 min再灌注4 h）。再灌注结束后，取心肌组织并分别应用蛋白质免疫印迹法（Western blot）和免疫共沉淀法（Co-Immunoprecipitation;Co-IP）检测necroptosis标志蛋白的表达及其修饰变化。 结果与成年心肌相比，necroptosis的标志蛋白RIP1、RIP3在衰老心肌中的表达均升高（P〈0.05），necroptosis的调节蛋白去乙酰化酶SIRT2的表达及活性也显著升高（P〈0.05），RIP1的去乙酰化水平显著升高（P〈0.05）。给予小剂量necroptosis抑制剂Necrostatin-1（Nec-1）处理，可以显著减少衰老心肌I/R梗死面积（P〈0.05）。结论本研究发现在衰老心肌I/R损伤中necroptosis显著增加，表明necroptosis可能在衰老心肌缺血损伤中有重要作用。

AIM Research shows that aging hearts have less tolerance to myocardial ischemia reperfusion （I/R） injury and this leads to the design of investigating the role of necroptosis in senescent myocardial I/R injury. METHODS Male C57BL/6 mice aged 22 -24 months were randomized into I/R group and vehicle control group. Adult male （3 -4 months） C57BL/6 mice served as control group. The left anterior descending artery was ligated for 30 rain followed by 4 h reperfusion to establish the acute myocardial I/R mouse model. Myocardial tissue was obtained after reperfusion. Western blot was used to detect necroptosis-related protein expression. Co-immunoprecipitation was used to detect the modification of the necroptosis-related protein. RESULTS Necroptosis was commonly increased in hearts of aged mice （P 〈 0. 05）. The expression of necroptosis biomarker, RIP1 and RIP3, is increased （P 〈 0. 05 ）. Expression and activity of the regulator protein deacetylase SIRT2 increased as well as the deacetylation of RIP1 （P 〈 0. 05 ）. Meanwhile, inhibiting necroptosis by using the inhibitor necrostatin-1 （Nec-1） reduced the infarct size in aged hearts （P 〈 0.05）. CONCLUSION Necroptosis displays an increased expression in aged myocardial I/R injury, indicating the important role necroptosis plays in age-related myocardial ischemia injury.