ABT-737通过上调NIX介导的线粒体自噬缓解大鼠低氧性肺动脉高压

ABT- 737 alleviates hypoxia- induced pulmonary artery hypertension by up -regulating the NIX-mediated mitophagy in rats

目的观察ABT-737对大鼠低氧性肺动脉高压（PAH）肺血管重构的作用，并从NIX介导的线粒体自噬方面探讨其可能的机制。方法采用随机数表法将18只SD大鼠平均分为3组（n=6）：对照组、缺氧组（其中死亡1只）、处理组。后两组大鼠置于低氧环境饲养4周，每天8h。处理组大鼠低氧饲养前，腹腔注射15mg／kgABT-737，另外两组注射等量溶剂。4周后，检测右室收缩压（RVSP）及右室肥厚指数（RVHI），并作肺血管组织学分析，计算中层厚度指数（Wn）。Western blot法检测大鼠肺组织NIX、微管相关蛋白1轻链3（LC3）-Ⅱ／LC3-Ⅰ及外膜转运酶（Tom）20蛋白的表达。结果对照组、缺氧组、处理组大鼠RVSP分别为（15．76±1．27）、（43．16±4．34）、（29．77±2．21）mmHg（1mmHg=0．133kpa），RVH1分别为0．28±0．04、0．37±0．02、0．29±0．03，WT1分别为（6．51±2．46）％、（14．60±2．33）％、（10．20±3．24）％。与对照组比较，缺氧组大鼠RVSP、RVHI及wTI显著增高（P值分别为0．000、0．002和0．000）。处理组较缺氧组大鼠RVSP、RVHI及WTI显著降低（P值均为0．000），但RVSP及WTI仍较对照组增加（P值均为0．000）。缺氧组NIX蛋白表达（0．93±0．11）比对照组（0．60±0．13）上调（P=0．001），而处理组（1．25±0．12）更高（P=0．000）。处理组大鼠LC3-Ⅱ／LC3-Ⅰ（1．59±0．53）较对照组（0．71±0．32）和缺氧组（0．94±0．20）均显著上调（P=0．006，P=0．032）。缺氧组Tom20蛋白表达（1．20±0．23）较对照组（0．84±0．15）显著升高（P=0．009），ABT-737干预能显著降低Tom20蛋白（0．97±0．08，P=0．040）。结论低氧导致大鼠肺循环压力升高、肺血管重构并且Tom20蛋白表达增加，而ABT-737可以通过上调NIX的表达，促进线粒体自噬，降解Tom20，缓解低氧诱导的PAH。

Objective To study the effects of ABT - 737 on rats with hypoxic pulmonary hyperten- sion （PAH）, and investigate the underlying mechanism from the aspect of NIX - mediated mitophagy. Methods According to random number table, 18 SD rats were randomly divided into 3 groups （n = 6 each） ： control group, hypoxic group （including 1 death） and treatment group. The rats in hypoxic group and treatment group were treated with bypoxia for 8 h/day, totally 4 weeks. The treatment group was given intraperitoneal administration of ABT - 737 15 mg/（ kg· day） before hypoxic rearing, while other groups re- ceived the same volume of vehicle. Right ventricular systolic pressure （RVSP）, right ventricular hypertro- phy （RVHI）, and pulmonary artery morphological features as well as wall thickness index （WTI） were as- sessed 4 weeks later. The expression of NIX, microtubule - associated protein 1 light chain 3 （LC3） - Ⅱ / LC3 - Ⅰ and translocase of the outer membrane （Tom） 20 protein was detected by Western blotting. Resuits RVSP in control group, hypoxic group and treatment group was （ 15.76 ± 1.27）, （43. 16 ± 4. 34） and （29. 77 ± 2. 21 ） mmHg respectively. RVHI in control group, hypoxic group and treatment group was 0. 28 ± 0.04, 0. 37 ± 0. 02 and 0. 29 ± 0. 03 respectively. WTI in control group, hypoxic group and treat- ment group was （6. 51 ± 2. 46） %, （ 14. 60 ± 2. 33 ） % and （ 10. 20 ± 3.24） % respectively. As compared with those in control group, RVSP, RVHI and WTI in hypoxic group were significantly increased （P =0. 000, 0. 002 and 0. 000 respectively）. Rats in treatment group showed significantly lower RVSP, RVHI and WTI than in hypoxic group （P values were 0. 000）, but RVSP and WTI in treatment group were still increased as compared with those in control group （ P values were 0. 000）. The expression of NIX in hy- poxic group （0. 93 ± 0. 11 ） was up -regulated as compared with control group （0. 60 ± 0. 13, P= 0. 001 ）, and that in treatment group （1.25 ± 0. 12 ） was even significantly higher （P = 0. 000 ）. LC3 -Ⅱ/LC3 - Ⅰ ratio in treatment group （ 1.59 ± 0. 53 ） was significantly higher than in control group （0. 71 ± 0. 32, P = 0. 006） and hypoxic group （ 0. 94 ± 0. 20, P = 0. 032 ）. The expression of Tom20 in hypoxic group （ 1.20 ± 0. 23 ） was remarkably increased as compared with that in control group （ 0. 84 ± 0. 15, P =0. 009 ）. This increase was suppressed by the ABT - 737 intervention （ 0.97 ± 0. 08, P = 0. 040）. Conclusion Hypoxia induces PAH and pulmonary vascular remodeling and increases the expres- sion of Tom20 in rats. ABT - 737 can alleviate hypoxia - induced PAH by promoting the NIX - mediated mitophagy, which can help Tom20 to be degraded.