哮喘气道重塑与氧化应激的实验研究

摘要

目的 探讨大鼠支气管哮喘模型的慢性气道炎症、气道重塑特征以及与氧化应激的关系.方法 以卵蛋白为过敏原致敏,反复多次激发以模拟临床反复发作过程,建立大鼠慢性哮喘模型.64只SD大鼠随机分为正常对照组和哮喘组,每组再进一步划分4、8、12、16 周4个时间段.观察指标:①肺泡灌洗液(bronchoalveolar lavage fluid,BALF)细胞计数与分类;②肺组织病理观察:进行支气管周围炎性细胞浸润及杯状细胞增殖评分,测定支气管壁的平滑肌面积、胶原沉积面积,及肺组织TGF-β1的积分光密度值(IOD值);③测定12周大鼠肺组织匀浆MDA含量、SOD活性及肺组织TGF-β1蛋白含量.结果 ①各时间段哮喘组的BALF细胞计数与正常对照组相比,差异均有统计学意义(均P＜0.01).其中中性粒细胞百分比、黏液指数随时间推移呈增加趋势.②4周哮喘组即有气道管壁增厚、平滑肌增生、胶原沉积增多、管腔变小、TGF-β1的表达增多等气道重塑的特征,与对照组比较差异均有统计学意义(均P＜0.01),并随时间推移呈增加趋势,以16周哮喘组最明显.③与对照组比较,哮喘组的MDA含量、TGF-β1含量均明显升高(均P＜0.01),SOD活性明显降低(P＜0.01).结论 通过延长卵蛋白激发时间可以成功制备SD大鼠慢性哮喘气道重塑模型;哮喘气道重塑在早期即出现,中性粒细胞及氧化应激可能参与哮喘的气道重塑.%Objective To approach the effect of prolonged allergen on airway remodeling and to understand the correlation between the chronic airway inflammation, airway remodeling and oxidative stress in rat asthmatic model. Methods Sixty-four female SD rats were randomly divided into 2 groups : control group and asthmatic group. The rats were sensitized with ovalbumin,and repeatedly exposed to aerosolized ovalbumin for 4 , 8 , 12,16 weeks. Inflammation cell count and classification in bronchoalveolar lavage fluid ( BALF) in the airways were assessed. The scores of inflammatory cell infiltration and goblet cell proliferation around the bronchia,the smooth muscle area and collagen deposition area in bronchial wall,and the integral optical density (IOD) of TGF-β1 in the pulmonary tissue were measured histopathologically. The levels of TGF-β1 protein, MDA content and SOD activity in pulmonary tissue of rats were measured at 12th week. Results ①As compared with the same periods in control group , BALF cell counts were significantly increased , the percentage of neutrophils and mucus index were especially increased over time in the asthmatic groups; ② The characteristics of airway remodeling such as asthma airway wall thickening, smooth muscle hyperplasia, and collagen deposition were increased, lumen shrinked, TGF-β1 expression increased at 4th week after ovalbumin challenge as compared with control group( all P＜0. 01). At 16th week after ovalbumin challenge , the airway remodeling was aggravated most significantly;③As compared with control group,MDA content and TGF-β1 level in pulmonary tissue were increased(all P＜0. 01) ,and SOD activity was decreased in asthmatic group(P＜0. 01). Conclusion The model of chronic airway remodeling is induced successfully by prolonged ovalbumin exposure in sensitized SD rats. The airway remodeling is emerged in an early stage in asthmatic rats. Oxidative stress and neutrophils may play a role in asthmatic airwav remodeling.