转化生长因子β_1与一氧化氮合酶及成肌纤维细胞参与大鼠缺氧性肺血管重塑

The role of expression of transforming growth factor-β_1 and inducible nitric oxide synthase and pulmonary vascular myofibroblast formation in the hypoxic pulmonary vascular remodeling of rats

目的观察转化生长因子β1(TGFβ1)与诱导型一氧化氮合酶(iNOS)基因动态表达变化及成肌纤维细胞形成在大鼠缺氧性肺血管重塑中的作用。方法40只成年雄性Wistar大鼠分成常氧组、缺氧3、7、14d和21d组,每组8只,测各组大鼠平均肺动脉压(mPAP)、血管形态学指标、右室肥大指数(RVHI);原位杂交和免疫组化检测TGFβ1、iNOS基因表达,透射电镜观察腺泡内血管壁细胞表型。结果缺氧7d后大鼠mPAP升高〔(18.41±0.37)mmHg,P<0.05〕。缺氧性肺血管重塑、右心室肥大于缺氧14d后出现。透射电镜证实成肌纤维细胞含有特异性的微丝和丰富的粗面内质网。TGFβ1mRNA于缺氧3d、7d表达增高不明显,缺氧14d增高(0.385±0.028,P<0.01);TGFβ1蛋白在常氧组呈弱阳性,缺氧3d表达增强(0.198±0.031,P<0.01),缺氧7d组达高峰(0.267±0.035,P<0.01)。对照组大鼠肺动脉壁iNOSmRNA弱阳性,缺氧3d后表达增强(0.245±0.036,P<0.01),缺氧7d达高峰水平(0.318±0.034,P<0.01),以后维持于高峰水平;iNOS蛋白在常氧组大鼠肺动脉中膜iNOS弱阳性,缺氧3d始增高(0.225±0.030,P<0.01),缺氧7d起稳定于高水平。结论缺氧诱导TGFβ1和iNOS动态表达变化及肺血管成肌纤维细胞的形成参与大鼠缺氧性肺血管重塑。

Objective To investigate the role o（ dynamic expression o（ trans（orrning growth factor-β1 （TGF-β1） and inducible nitric oxide synthase（iNOS） and rnyofibroblast formation in hypoxic pulmonary vascular remodeling o（ rats. Methods Forty male Wistar rats were exposed to hypoxia （or 0, 3, 7, 14 days or 21 days. Mean pulmonary arterial pressure （rnPAP）, vessel rnorphornetry, right ventricle hypertrophy index （RVHI） were measured. Lungs were fixed （or in situ hybridization and irnrnunohistochernistry. Ultrastructural characteristics of cell phenotype in alveolar wall vessels were observed by electron microscopy. Results rnPAP increased by （ 18.41 ± 0.37） turn Hg after 7-day o（ hypoxia, （P〈0.05）. Pulnaonary artery remodeling index and right ventricle hypertrophy became evident after 14-day o（ hypoxia. The rnyofibroblast phenotype was confirmed by electron microscopy, which revealed rnierofilarnents and a well-developed rough endoplasrnic reticulurn in rnyofibroblast. TGF-β1 rnRNA expression in pulmonary arterial walls was increased by （0. 385 ± 0.028, P〈0.01） after 14 days of hypoxia, but showed no obvious changes after 3 or 7 days of hypoxia. In pulmonary tunica adventitia and tunica media, TGF-β1 staining was poorly positive in control rats, but was markedly enhanced after 3 days of hypoxia（0. 198±0.031,P〈0.01）, reaching its peak a（ter 7 days of hypoxia（0.267±0.035,P〈0.01）. Expression of iNOS rnRNA in control group was poorly positive in pulmonary arterial wall, the level of iNOS rnRNA was markedly up -regulated after 3 days of hypoxia（0. 245±0. 036, P〈0.01 ）, reaching its peak Mter 7 days of hypoxia （0.318±0.034, P〈0.01）, then remained on the high level. Expression of iNOS protein in control group was poorly positive in pulmonary arterial tuniea media, the level of iNOS protein was markedly up regulated after 3 days （0. 223±0. 030, P〈70.01 ）, reaching its peak after 7 days of hypoxia, then remained on the high level. Conclusions Induction of TGF-β1 and iNOS expression after hypoxia and myofibrohlasts formation may play a important role in hypoxic pulmonary vascular remodeling of rats.