低氧诱导大鼠肺动脉重塑对肺动脉平滑肌锌指蛋白转录因子5表达的影响

Hypoxia induced the remodeling of pulmonary arterial smooth muscles and increased the pulmonary artery smooth muscle Kr＆#252;ppel-like zinc-finger transcription factor 5 expression

目的 探讨慢性低氧性肺动脉高压（CHPH）大鼠模型肺动脉重塑与肺动脉平滑肌锌指蛋白转录因子5（KLF5）蛋白表达的关系.方法 雄性SD大鼠20只按随机数字表法分为常氧组和低氧组,每组10只,低氧组放入全自动低氧箱饲养,21 d后用右心室测压法测量右心室收缩压（RVSP）及平均右心室压（mRVP）;计算右心肥厚指数RV/（LV＋S）;取右肺组织包埋切片行HE染色测量肺小动脉血管管腔面积,计算血管中膜厚度百分比（WT％）;并取切片行免疫荧光检测KLF5的表达;荧光PCR和Western blot法分别检测远端肺动脉平滑肌组织中KLF5 mRNA、蛋白的表达.显微镜下分离大鼠（6只）远端肺动脉平滑肌组织,胶原酶消化法培养大鼠原代肺动脉平滑肌细胞（PASMCs）,随后置于低氧环境（4％ O2,60 h）培养并获取细胞蛋白检测KLF5的表达.结果 低氧组大鼠RVSP和mRVP与常氧组（28.3±0.4）、（11.3±1.0） mmHg（1 mmHg =0.133 kPa）比较,分别升高至（43.9±1.3）、（26.5±2.3）mmHg（P ＜0.05）;低氧组RV/（LV ＋S）为（0.48±0.03）,明显高于常氧组（0.27±0.01,P＜0.05）;低氧组血管腔占血管区域的比值（WT％）为（46.1±6.6）％,与常氧组（68.7±3.1）％相比显著降低（P＜0.05）;而低氧组WT％（5.6±0.3）％与常氧组（3.7±0.4）％相比显著增加（P＜0.05）;低氧组大鼠肺动脉平滑肌组织KLF5蛋白表达量为常氧组的（22±7）倍,差异有统计学意义（P＜0.05）.结论 CHPH大鼠模型RVSP、mRVP、右心室肥厚指数均升高,同时伴有肺小动脉重塑,这可能与低氧诱导PASMCs中KLF5的表达升高有关.

Objective To study the effect of chronic hypoxia on pulmonary arterial remodeling and Kruppel-like zinc-finger transcription factor 5 （KLF5） protein expression in pulmonary artery smooth muscles in a hypoxia-induced pulmonary hypertension model.Methods Totally 20 adult SD rats （200-250 g） were divided into a normoxia group and a chronic hypoxia group by the random number table.Rats in the chronic hypoxia group were put in an automatic hypoxia box for 21 days.After that,right ventricular systolic pressure （RVSP）,mean right ventricular pressure （mRVP） and RV/（LV ＋ S） were measured.Lung tissue sections were made.The lumen area,ratio of wall thickness to radius of pulmonary artery were gauged by using the Image Pro Plus software.Primary PASMCs were cultured in oxygen-deficient environment （4% O2） or normal oxygen environment （21% O2）for 60 hours respectively,and then total protein or RNA were extracted for Western blotting and Q-PCR analysis.KLF5 protein expression in rat pulmonary arterial smooth muscle and pulmonary arterial smooth muscle cells was detected by Western blot.Results Compared with the normoxia group （28.3 ± 0.4）,（11.3 ± 1.0）mmHg （1 mmHg =0.133 kPa）,the RVSP and mRVP in the chronic hypoxia group [（43.9 ± 1.3）,（26.5 ±2.3） mmHg] were significantly increased （P 〈 0.05）.The Rv/ （LV ＋ S） of the chronic hypoxia group was （0.48 ± 0.03）,markedly higher than that of the normoxia group（0.27 ±0.01,P 〈0.05）.The luminal area/total area of artery in the chronic hypoxia group decreased to （46.1 ± 6.6）% compared with that in the normoxia group [（68.73 ± 3.06）%,P 〈 0.05].The wall thickness/arterial radius （WT%）of the chronic hypoxia group increased up to （5.64 ± 0.32） % as compared with （3.7 ± 0.4） % of the normoxia group （P 〈 0.05）.The level of KLF5 protein in pulmonary arterial smooth muscles of the chronic hypoxia group was （21.6 ± 7.2） times that of the normoxia group （P 〈 0.05）.Conclusion Hypoxia induced the increase of RVSP,mRVP,RV/（LV ＋ S）,accompanied with pulmonary arterial remodeling.The underlying mechanism of the artery change may be related to up-regulated expression of KLF5.