转化生长因子β1与诱导型一氧化氮合酶相互调控对大鼠低氧性肺动脉高压的作用

目的观察转化生长因子β1(TGF-β1)与诱导型一氧化氮合酶(iNOS)基因在低氧性肺动脉高压(HPH)大鼠肺动脉的动态表达变化.方法 40只成年雄性Wistar大鼠随机分成对照组(C组)、缺氧3、7、14和21 d组(H3、H7、H14和H21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TGF-β1、iNOS基因表达.结果 H7组大鼠mPAP(18.41±0.37)mm Hg,1 mm Hg=0.133 kPa]显著高于C组(P<0.05),H14组达高峰(21.17±0.23)mm Hg]并维持于高水平.肺血管重塑、右心室肥大缺氧14 d后出现.C组大鼠肺动脉中膜iNOS蛋白弱阳性(0.109±0.021),H3组增高(0.225±0.030,P<0.01),H7组(0.312±0.036)稳定于高水平.C组大鼠肺动脉壁iNOS mRNA弱阳性(0.112±0.030),H3组表达增强(0.245±0.036),H7组达高峰(0.318±0.034,P<0.01)并维持于高水平.TGF-β1蛋白在C组呈弱阳性(0.042±0.012),H3组表达增强(0.198±0.031),H7组达高峰(0.267±0.035,P<0.01),随着缺氧时间延长,TGF-β1逐渐向基线水平回降;C组TGF-β1 mRNA呈弱阳性表达(0.145±0.018),H3、H7组表达增高不明显(0.163±0.021、0.176±0.026),H14组增高(0.385±0.028,P<0.01),并维持于高水平,TGF-β1 mRNA、蛋白于肺动脉中膜和外膜表达.相关分析表明,TGF-β1、iNOS均与mPAP和血管重塑呈正相关(r=0.843～0.937,P均＜0.01);TGF-β1蛋白(外膜)与iNOS mRNA、蛋白均呈负相关(r分别为-0.856、-0.835,P均＜0.01).结论 TGF-β1和iNOS均参与大鼠HPH的发病,iNOS可能通过NO上调TGF-β1表达,TGF-β1可能通过降低mRNA的稳定性、减慢翻译速率和加快酶蛋白降解抑制iNOS表达.

Transforming growth factor β1 correlates inducible nitric oxide synthase in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension

OBJECTIVE: To investigate the dynamic expression of transforming growth factor beta(1)(TGF-beta(1)) and inducible nitric oxide synthase (iNOS) in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension (HPH). METHODS: Forty adult male Wistar rats were randomly divided into five groups: a control group (C group) and groups with hypoxia for 3, 7, 14 and 21 days (H(3), H(7), H(14), H(21) group), eight rats per group. Mean pulmonary arterial pressure (mPAP), vessel morphometry and right ventricle hypertrophy index (RVHI) were measured. Lungs were inflation fixed for in situ hybridization and immunohistochemistry. RESULTS: mPAP increased significantly in H(7) group (18.41 +/- 0.37) mm Hg, 1 mm Hg = 0.133 kPa, P < 0.05], reaching its peak in H(14) group (21.17 +/- 0.23) mm Hg], then remained at the high level. Hypoxia induced pulmonary artery remodeling and right ventricle hypertrophy index became evident in H(14) group. Expression of iNOS protein in control group (0.109 +/- 0.021) was weakly positive in pulmonary arterial tunica media, while the level of iNOS protein was markedly up-regulated in H(3) group (0.225 +/- 0.030, P < 0.01), reaching its peak in H(7) group (0.312 +/- 0.036), then remained at the high level. Expression of iNOS mRNA in C group (0.112 +/- 0.030) was weakly positive in pulmonary arterial wall, while the level of iNOS mRNA was markedly up-regulated in H(3) group (0.245 +/- 0.036), reaching its peak in H(7) group (0.318 +/- 0.034, P < 0.01), then remained at the high level. Expression of TGF-beta(1) protein in C group (0.042 +/- 0.012) was weakly positive, but the level of TGF-beta(1) protein was markedly up-regulated in H(3) group (0.198 +/- 0.031), reaching its peak in H(7) group (0.267 +/- 0.035, P < 0.01), and then tended to decline in H(14) and H(21) group. TGF-beta(1) mRNA staining was weakly positive in C group (0.145 +/- 0.018), H(3) group (0.163 +/- 0.021) and H(7) group (0.176 +/- 0.026), but began to increase significantly in H(14) group (0.385 +/- 0.028, P < 0.01), and then remained stable. TGF-beta(1) protein and mRNA were located predominantly in tunica adventitia and tunica media. Linear correlation analysis showed that TGF-beta(1) mRNA, iNOS mRNA and protein were positively correlated with mPAP, vessel morphometry and RVHI (r = 0.843 - 0.937, all P < 0.01). TGF-beta(1) protein (tunica adventitia) was negatively correlated with iNOS mRNA and protein (r = -0.856, -0.835, all P < 0.01). CONCLUSIONS: Interaction of TGF-beta(1) and iNOS plays a role in the pathogenesis of HPH in rats. iNOS can regulate the expression of TGF-beta(1) gene by NO. TGF-beta(1) can regulate the expression of iNOS gene by decreased stability and translation of iNOS mRNA and increased degradation of iNOS protein.