大鼠缺氧性肺动脉高压时三种缺氧诱导因子α亚基在肺动脉中的差异表达

目的区分大鼠缺氧性肺动脉高压时肺血管壁3种缺氧诱导因子α(HIFα)亚基(HIF1α、HIF2α、HIF3α)的基因表达特征。方法40只雄性Wistar大鼠按随机数字表法分为常氧0d组(H0组)、缺氧3d组(H3组)、7d组(H7组)、14d组(H14组)和21d组(H21组),每组8只。用(10.0±0.5)%的氧浓度每天间断缺氧8h,测各组大鼠平均肺动脉压(mPAP)、肺动脉管壁面积(WA%)、肺动脉中膜厚度(PAMT)、右室肥厚指数(RVHI%);用原位杂交、免疫印迹和免疫组化法检测HIF1α、HIF2α和HIF3α基因表达。结果H7组mPAP为(18.40±0.40)mmHg(1mmHg=0.133kPa),H0组为(14.40±0.40)mmHg,H14组为(21.20±0.20)mmHg,H7组与H0组、H14组比较差异有统计学意义(P均<0.05);血管形态学显示,H7组WA%、PAMT、RVHI%分别为(47.8±0.8)%、(12.3±0.5)μm、(24.0±1.0)%,H14组分别为(60.3±0.4)%、(15.0±0.3)μm、(25.0±1.8)%,H0组分别为(35.5±1.3)%、(11.9±0.6)μm、(23.6±0.5)%,H21组分别为(65.0±0.7)%、(23.0±0.8)μm、(27.7±1.0)%,WA%H7组与H0组、H14组与H0组、H21组与H14组间比较差异均有统计学意义(P均<0.05)。原位杂交显示,H14组HIF1α、HIF2α、HIF3αmRNA水平的吸光度(A)值分别为0.200±0.020、0.080±0.010、0.170±0.010;H7组分别为0.050±0.020、0.160±0.020、0.160±0.020;H0组分别为0.050±0.010、0.140±0.020、0.060±0.010;H14组与H0组三者、H7组与H0组仅HIF3α比较差异有统计学意义(P均<0.05)。免疫组化表明,H3组HIF1α,HIF2α和HIF3α蛋白表达分别为0.200±0.020、0.020±0.010、0.050±0.010;H14组分别为0.160±0.010、0.100±0.020、0.160±0.010;H7组分别为0.220±0.020、0.030±0.010、0.180±0.020;H0组分别为0.050±0.010、0.020±0.010、0.040±0.010,H3组HIF1α蛋白、H14组HIF2α蛋白、H7组、H3组HIF3α蛋白分别与H0组比较差异有统计学意义(P均<0.05)。H7组免疫印迹显示在肺组织中HIF3α表达较H0组显著减弱,H3组HIF2α、HIF3α蛋白表达较H0组增强,随着缺氧时间延长,H14组较H7组更明显。结论3种HIFα表达差异可能在缺氧性肺动脉高压发病中发挥作用。

Differential expression of the three hypoxia-inducible factor α subunits in pulmonary artery of rats with hypoxia-induced pulmonary hypertension

OBJECTIVE: To differentiate the expression patterns of all hypoxia-inducible factor alpha (HIF-alpha) subunits (HIF-1alpha, HIF-2alpha and HIF-3alpha) in pulmonary artery of rats undergoing systemic hypoxia. METHODS: Forty male healthy wistar rats were assigned randomly to 5 groups, 8 rats per group, then exposed to hypoxia [O2, (10.0 +/- 0.5)%] for 0 d (H(0)), 3 d (H(3)), 7 d (H(7)), 14 d (H(14)) and 21 d (H(21)) respectively, 8 h per day intermittently. Mean pulmonary arterial pressure (mPAP), arterial wall area (WA, microm), pulmonary artery medium thickness (PAMT%) and right ventricle hypertrophy index (RVHI) were measured. HIF-1alpha, HIF-2alpha and HIF-3alpha gene expression were determined by immunohistochemistry, in situ hybridization and Western blot. RESULTS: mPAPs in H(7), H(0) and H(14) groups were [(18.40 +/- 0.40) mm Hg, 1 mm Hg = 0.133 kPa], [(14.40 +/- 0.40) mm Hg] and [(21.20 +/- 0.20) mm Hg], respectively, statistically different when H(7) group was compared with H(0) and H(14) groups (all P < 0.05). Arterial morphology showed that WA%, PAMT and RVHI% in H(7) group were (47.8 +/- 0.8)%, (12.3 +/- 0.5) microm, (24.0 +/- 1.0)%, respectively; in H(0) group were (35.5 +/- 1.3)%, (11.9 +/- 0.6)%, (23.6 +/- 0.5) microm, respectively; in H(21) group were (65.0 +/- 0.7)%, (23.0 +/- 0.8) microm, (27.7 +/- 1.0)%, respectively. When H(7) group was compared with H(0) group, only WA% was statistically different; when H(14) group was compared with H(0) group, all the three parameters were statistically different (P < 0.05). In situ hybridization demonstrated that the mRNA levels (absorbance, A) of HIF-1alpha, HIF-2alpha, and HIF-3alpha in H(14) group were 0.200 +/- 0.020, 0.080 +/- 0.010, 0.170 +/- 0.010, respectively; in H(7) group were 0.050 +/- 0.020, 0.160 +/- 0.020, 0.160 +/- 0.020, respectively; in H(0) group were 0.050 +/- 0.010, 0.140 +/- 0.020, 0.060 +/- 0.010, respectively. When H(7) group was compared with H(0) group, only HIF-3alpha was statistically different; when H(14) group was compared with H(0) group, all the three genes were significantly different (P < 0.05). Immunohistochemistry showed that HIF-1alpha, HIF-2alpha and HIF-3alpha protein levels in H(3) group were 0.200 +/- 0.020, 0.020 +/- 0.010, 0.050 +/- 0.010, respectively; in H(14) group were 0.160 +/- 0.010, 0.100 +/- 0.020, 0.160 +/- 0.010, respectively; in H(7) group were 0.220 +/- 0.020, 0.030 +/- 0.010, 0.180 +/- 0.020, respectively; in H(0) group were 0.050 +/- 0.010, 0.020 +/- 0.010, 0.040 +/- 0.010, respectively. HIF-1alpha in H(3) group, HIF-2alpha in H(14) group, HIF-3alpha in H(7) and H(3) group were statistically different with that of H(0) group (P < 0.05). Protein bands of HIF-alpha subunits in lung tissue, measured by Western blot, showed that HIF-3alpha decreased in H(7) group as compared to H(0) group, but the other two proteins showed a marked increase in H(3) group as compared to H(0) group, and increased further corresponding to the duration of hypoxia and peaked in H(14) group as compared to H(7) group. CONCLUSION: The differential expression of the three HIF-alpha subunits may play a role in the development of hypoxia-induced pulmonary hypertension.