Objective: To investigate whether activation of mitochondrial acetal dehydrogenase 2 (ALDH2) alleviates hypoxic pulmonary hypertension by regulating the SIRT1/PGC-1α signaling pathway.
Methods: Thirty 8-week-old C57 BL/6 mice were randomized into control, hypoxia, and hypoxia +Alda-1 (an ALDH2 activator) group (n=10), and the mice in the latter two groups, along with 10 ALDH2 knockout (ALDH2-/-) mice, were exposed to hypoxia (10% O2, 90% N2) with or without daily intraperitoneal injection of Alda-1 for 4 weeks. The changes in right ventricular function and pressure (RVSP) of the mice were evaluated by echocardiography and right ventricular catheter test, and pulmonary artery pressure was estimated based on RVSP. Pulmonary vascular remodeling, right ventricular injury, myocardial α -SMA expression, distal pulmonary arteriole muscle normalization, right ventricular cross-sectional area, myocardial cell hypertrophy, and right cardiac hypertrophy index were assessed with HE staining, immunofluorescence staining and WGA staining, and the expressions of ALDH2, SIRT1, PGC-1α, P16INK4A and P21CIP1 were detected. In pulmonary artery smooth muscle cells with hypoxic exposure, the effect of Alda-1 and EX527 on cell senescence and protein expressions was evaluated using β-galactose staining and Western blotting.
Results: The wild-type mice with hypoxic exposure showed significantly increased RVSP, right ventricular free wall thickness and myocardial expressions of P16INK4A and P21CIP1, which were effectively lowered by treatment with Alda-1 but further increased in ALDH2-/- mice. In cultured pulmonary artery smooth muscle cells, hypoxic exposure significantly increased senescent cell percentage and cellular expressions of P16INK4A and P21CIP1, which were all lowered by treatment with Alda-1, but its effect was obviously attenuated by EX527 treatment.
Conclusion: ALDH2 alleviates hypoxiainduced senescence of pulmonary artery smooth muscle cells by upregulating the SIRT1/PGC-1α signaling pathway to alleviate pulmonary hypertension in mice.
目的: 探讨激活线粒体乙醛脱氢酶2（ALDH2）是否可以通过SIRT1/PGC-1α信号通路减轻缺氧性肺动脉高压。
方法: 在体水平：选取8周龄C57 BL/6小鼠40只，随机分成Control组、Hypoxia组、Hypoxia +Alda-1灌胃组及ALDH2特异性敲除组（Hypoxia +ALDH2-/-），10只/组，Hypoxia组小鼠暴露于缺氧条件下（10%O2，90%N2），维持每日12 h/12 h的暗/光循环4周，Hypoxia+Alda-1组同时予以Alda-1腹腔注射处理４周，Control组予以常氧环境并给与同等量的溶剂（DMSO+PBS）干预４周。利用超声心动图、右心室导管实验评估右心功能及压力，以右心室压代替肺动脉压；HE评估肺血管重构及右心室损伤情况，免疫荧光检测α-SMA表达，评估肺远端小动脉肌化情况，WGA染色检测右心室横截面积，评估心肌细胞肥大程度，测量右心肥厚指数。检测ALDH2、SIRT1、PGC-1α、P16INK4A、P21CIP1蛋白表达。体外水平：分别设置Control组、Hypoxia组上、Hypoxia+Alda-1组上、Hypoxia+Alda-1+EX527组。利用β半乳糖染色评估各分组小鼠肺动脉平滑肌细胞衰老情况，Western blotting评估各分组蛋白表达情况。
结果: 与Control组相比，Hypoxia组右心室收缩压（RVSP）增高、右室游离壁厚度（RVFWT）增厚、P16INK4A、P21CIP1表达增加（P<0.05）。与Hypoxia组相比，Hypoxia+Alda-1组RVSP降低、RVFWT变薄、P16INK4A、P21CIP1表达降低（P<0.05）。与Hypoxia组相比，Hypoxia+ALDH2 -/-组RVSP增高、RVFWT增厚、P16INK4A、P21CIP1蛋白表达增加（P<0.01）。与Control组相比，Hypoxia组细胞衰老比例增加、P16INK4A、P21CIP1表达增加（P<0.01）。与Hypoxia组相比，Hypoxia+Alda-1组细胞衰老比例降低（P<0.01），P16INK4A、P21CIP1（P<0.05）表达降低。与Hypoxia+Alda-1组相比，Hypoxia+Alda-1+EX527组细胞衰老比例增加（P<0.01），P16INK4A、P21CIP1表达增高（P<0.05）。
结论: ALDH2通过调控SIRT1/PGC-1α信号通路，减轻小鼠肺动脉平滑肌细胞衰老，从而减轻缺氧型肺动脉高压。
Keywords: ALDH2; PGC-1α; SIRT1; pulmonary hypertension; smooth muscle cell senescence.