目的 探讨沉默信息调节因子 2 相关酶 3（SIRT3）调控自噬在 H2O2诱导的肺泡Ⅱ型上皮细 胞凋亡中的作用。方法 使用对数生长期的小鼠Ⅱ型肺泡上皮细胞株（MLE⁃12），利用 0.5 mmol/L H2O2建 立 MLE⁃12 细胞凋亡模型，分为：正常对照组、H2O2损伤组、H2O2 + SIRT3 组、H2O2 + SIRT3 沉默组。CCK8 法 检测各组细胞增殖活力；SOD、MDA 及T⁃AOC 试剂盒检测SOD、MDA 及T⁃AOC 水平；构建mRFP⁃GFP⁃LC3自 噬双标体系，激光共聚焦显微镜观察自噬水平；激光共聚焦显微镜观察线粒体膜电位变化及 ROS 水平；蛋 白免疫印迹实验检测 SIRT3、Bcl2、Bax 及 LC3B 表达水平。结果 与正常对照组比较，H2O2损伤组、H2O2+ SIRT3 组和 H2O2+SIRT3 沉默组 MDA、ROS 水平及自噬小体、自噬溶酶体点数升高（P < 0.05），细胞活力、 SOD、T⁃AOC 水平和线粒体膜电位降低（P < 0.05），SIRT3 及 Bcl2 蛋白表达降低（P < 0.05），Bax 及 LC2Ⅱ蛋 白表达升高（P < 0.05），以 H2O2+SIRT3 沉默组最为显著；与 H2O2损伤组比较，MDA、ROS 水平及自噬小体、 自噬溶酶体点数下降（P < 0.05），细胞活力、SOD、T⁃AOC 水平和线粒体膜电位升高（P < 0.05），SIRT3 及 Bcl2 蛋白表达升高（P < 0.05），Bax 及 LC2Ⅱ蛋白表达降低（P < 0.05）。结论 SIRT3 可以通过抑制自噬、氧 化应激及凋亡减轻H2O2诱导的肺泡Ⅱ型上皮细胞损伤。 

Objective To investigate the role of sirtuin 2⁃related enzyme 3（SIRT3）regulating mitophagy in H2O2⁃induced apoptosis of alveolar type Ⅱ epithelial cells. Methods The mouse type Ⅱ alveolar epithelial cell line（MLE ⁃12）in logarithmic growth period was used to establish MLE ⁃ 12 cell apoptosis model with 0.5 mmol/L H2O2. The model was divided into normal control group，H2O2 injury group，H2O2+SIRT3 group，and H2O2+SIRT3 silence group. CCK8 was used to detect the proliferative activity of cells in each group；SOD，MDA and T⁃AOC kit were used to detect the level of SOD，MDA and T⁃AOC；The mRFP⁃GFP⁃LC3 autophagy double label system was constructed，and the autophagy level was observed by laser confocal microscopy；The changes of mitochondrial membrane potential and ROS level were observed by laser confocal microscopy；Western blot was used to detect the expression level of SIRT3，Bcl⁃2，Bax and LC3B. Results Compared with those in the normal controls，the level of MDA and ROS and autophagosome and autolysosomes were increased in the H2O2 injury，H2O2 + SIRT3 and H2O2 + SIRT3 silencing group（P < 0.05）. Reduced cell viability，SOD，T ⁃AOC levels，and mitochondrial membrane potential（P < 0.05），reduced protein expression of SIRT3 and Bcl2（P < 0.05），and increased Bax and LC2Ⅱ protein expression（P < 0.05）were observed，particularly significantly in the H2O2 + SIRT3 silencing group. Compared with those in the H2O2 injury group，the level of MDA and ROS and the number of autophagosome and autolysosome points were decreased in the H2O2 + SIRT3 and H2O2 + SIRT3 silencing group（P < 0.05）； increased cell viability，the level of SOD and T⁃AOC，and mitochondrial membrane potential（P < 0.05），elevated expression of SIRT3 and Bcl2 protein（P < 0.05），reduced expression of Bax and LC2Ⅱ proteins were observed （P < 0.05）. Conclusion SIRT3 can alleviate H2O2⁃induced alveolar type Ⅱ epithelial cell damage by inhibiting autophagy，oxidative stress and apoptosis.