支气管上皮在大鼠哮喘模型气道炎症和重塑中的作用

The role of bronchial epithelium in airway inflammation and airway remodeling in rat allergic asthmatic model

目的探讨哮喘时支气管上皮的形态学变化及其在气道炎症和气道重塑中的作用。方法于2003-01—2003-12对北京儿童医院应用卵蛋白(OVA)致敏和激发的方法制作的SD大鼠慢性哮喘模型,采用病理学和免疫组织化学等方法进行研究。观察对照组和OVA激发后24h组、1周组、2周组和4周组,支气管上皮形态学改变以及各组在支气管肺泡灌洗液(BALF)中炎症细胞和上皮细胞数、气道周围浸润的嗜酸细胞数、上皮下纤维连接蛋白(FN)沉积以及支气管上皮细胞间粘附因子1(ICAM-1)和调节激活正常T细胞表达和分泌因子(RAN-TES)以及转化生长因子β1(TGFβ1)表达的不同。结果模型各组支气管上皮在光镜下主要表现为局灶性的破坏和脱落以及杯状细胞增生,电镜下表现为上皮细胞细胞器水肿、胞浆空泡增多和纤毛损害。模型各组BALF中各种白细胞和纤毛上皮细胞的绝对数与对照组相比均显著升高;模型各组气道周围浸润的嗜酸细胞与对照组相比显著增加,其中2周模型组气道周围浸润的嗜酸细胞与BALF中纤毛上皮细胞数成正相关(r=0.782,P=0.022)。2周和4周模型组上皮杯状细胞数、上皮下FN沉积与对照组相比显著增加。模型各组上皮细胞表达ICAM-1和RANTES与对照组相比显著升高。1周、2周和4周模型组上皮TGFβ1的表达与对照组相比显著升高,2周和4周模型组上皮TGF-β1的表达与上皮下FN的沉积呈正相关(r=0.42,P=0.021;r=0.516,P=0.004)。结论在大鼠哮喘模型中支气管上皮的形态和功能发生明显改变,支气管上皮通过分泌ICAM-1和RANTES等促炎因子启动和促进了哮喘的气道炎症;通过分泌TGFβ1等促纤维化因子参与了气道重塑的形成。

Objective To explore the morphologic change and the role of bronchial epithelium in airway inflammation and airway remodeling in asthma. Methods The chronic asthmatic model of SD rats was established with ovalbumin sensitization and challenge method. The morphologic change of bronchial epithelium was observed by light microscopy and electron microscopy in model groups of 24 hour, 1 week ,2 weeks and 4 weeks after ovalbumin challenge. The difference between model groups and control groups was compared in inflammatory cells and ciliated epithelial cell counting in bronchoalveolar fluid lavage（ BALF） ,the number of eosinophils infiltrated around airways, the deposition of fibronectin（ FN） under epithelium and the expression of intercellular adhesion molecule 1 { ICAM1 ） ,regulated on activation normal T cells expressed and secreted （ RANTES） and transforming growth factor-[31 （ TGF[31 ） in bronchial epithelium. Results Local destruction and desquamation and goblet cell hyperplasia of epithelium could be observed under light microscopy. The e- dema of organelles,increased vacuoles in cytoplasm of epithelial cells and cilla damage could be observed in all model groups by electron microscopy. There was significantly higher number of miscellaneous leukocytes and cilia epithelial cells in BALF in all model groups than control groups. The number of eosinophils infiltrated around large and middle airways correlated significantly with the number of cilia epithelial cell in BALF in 2w model group{ r = 0. 782, P = 0. 022）. The number of goblet cells in epithelium and the expression of FN under epithelium in 2w model group were significantly increased compared with the control group. The expression of ICAM-1 and RANTES were significantly increased in all model groups compared with the control group. The expression of TGF- β1 in epithelium was significantly increased in 1w,2w and 4w model group compared with the control group. The expression of TGF-β1 in epithelium in 2w and 4w model group was significantly correlated to the expression of FN under epithelium in 2w and 4w model group. （ r = 0. 42, P = 0. 021 ; r = 0. 516, P = 0. 004）. Conclusion The morphology and function of bronchial epithelium in this asthmatic model of SD rats have greatly changed. Bronchial epithelium involved in airway inflammation and remodelling by releasing cytokines such as ICAM-1, RANTES and TGF-β1.