实验性肺动脉高压大鼠肺组织中HOXB7基因表达水平的变化

Expression of HOXB7 in the lung of rat with experimental pulmonary hypertension

目的探讨同源盒基因HOXB7在大鼠肺动脉高压(PH)模型肺组织中表达水平的变化。方法SD大鼠左肺切除,术后第7天项背部皮下注射野百合碱(MCT,60mg/kg),建立PH模型,于术后第1、21和35天分别检测平均肺动脉压力(mPAP)、RV/(LV+S)比值和肺小动脉中膜厚度百分比(WT%);弹力纤维染色观察肺小血管新生内膜形成情况;应用Western blot和免疫组织化学技术检测HOXB7在大鼠肺组织中的表达水平。结果在大鼠肺切除术后第35天,右肺腺泡内小血管出现了新生内膜病变,对照组没有形成新生内膜。与对照组比较,PH模型组第21、35天mPAP、RV/(LV+S)、WT%均显著增加(P<0.0001)。两组第1天mPAP、RV/(LV+S)、WT%比较,差异无统计学意义(P>0.05)。Westernblot和免疫组织化学技术检测结果显示PH模型组在第21天HOXB7表达开始上调,在第35天表达增高趋势更明显;PCNA染色结果显示阳性细胞主要分布在肺血管平滑肌细胞。结论肺切除+MCT诱导的PH模型能较好地模拟人类严重PH肺血管重构模式。HOXB7蛋白表达水平变化可能在PH肺血管重构中起着重要作用。

[ Objective ] To investigate the expression of HOXB7 in vascular remodeling in rat with pulmonary hypertension established by left lung resection in combination with monoerotaline （MCT）. [ Methods ] Male Sprague- Dawley rats （350 to 400 g） were received MCT （60 mg/kg） subcutaneous injection on Day 7 after left lung resection. Mean pulmonary artery pressure（mPAD, fight ventricle （RV）/[left ventricle （LV）＋ interventricular septum （S）] ratio and percent pulmonary artery wall thickness（WT%） were detected on Day 1, 21, 35 after left lung resection, respec- tively. Neointimal formation in small pulmonary vessels was observed by Van Gieson stain. The expression of HOXB7 in lung tissue was detected by western blot and immunohistochemistry. [ Results ] Neointimal changes developed in fight lung intra-aeinar vessels on Day 35 after left lung resection. Neointimal lesions did not develop in control animals. Animals treated with left lung resection plus MCT had significantly increased mPAP values on Day 21 （27.10 ± 2.02） mmHg, with a further increase on Day 35 （39.75 ±3.62） mmHg, as compared with control animals [（16.80 ± 1.03） mmHg, Day 21; （17.10 ±1.20） mmHg, Day 35] （P 〈0.0001）. This was also true for fight ventricular hypertrophy and media hypertrophy： The RV/（LV＋S） ratio increased from （0.266 ± 0.015） （Day1） to （0.456 ± 0.025）（Day 21） and （0.627 ±0.040） （Day 35）, as compared with those in control animals[（0.267 ± 0.016） （Day1）, （0.272 ± 0.015） （Day 21） and （0.257 ± 0.019） （Day 35）] （P 〈0.0001）. Compared with normal pulmonary arteries, MCT injection after left lung resection resulted in severe media hypertrophy after 35 days. The level of HOXB7 protein expression in rats received left lung resection plus MCT was significantly upregulation on Day 35, compared with that in control animals, and these tendency was observed on Day 21 after left lung resection. [ Conclusion ] The neointimal model established by left lung resection plus MCT could stimulate the pattern of vascular remodeling in pulmonary hypertension. The upregulation of HOXB7 may play a key role in pulmonary vascular remodeling.