地塞米松对哮喘小鼠肺液清除功能障碍的作用

目的：研究支气管哮喘（以下简称哮喘）小鼠肺液清除功能的变化及地塞米松的作用，并探讨其可能机制。方法：雌性C57／BL6小鼠48只，随机分为对照组、哮喘组和地塞米松干预组。以卵蛋白（OVA）联合佐剂腹腔注射（第1、15天）加雾化吸入（第25～29天）方法复制小鼠哮喘模型。分别在末次激发后2h及24h测定各组小鼠肺组织病理变化及湿干重比值（W／D），应用免疫组化法测定各组水通道蛋白5（AQP5）在肺组织中的分布，分别采用实时PCR和蛋白质印迹法测定各组小鼠肺组织中AQP5mRNA和蛋白质的变化。ELISA法测定各组小鼠支气管肺泡灌洗液中细胞数和细胞因子IFN-γ及IL-13的水平。结果：哮喘组小鼠肺组织W／D较对照组明显升高，末次激发后2h和24h分别为4．98±0．46和4．81±0．33，分别升高22．9％和18．7％（P〈0．05），且激发后2h哮喘组小鼠肺组织W／D升高更明显。地塞米松干预组小鼠2h和24h肺组织W／D分别为4．01±0．11和4．21±0．14，与哮喘组小鼠相比显著降低（P〈0．05）；与对照组无显著性差异（P〉0．05）。HE染色可见哮喘组小鼠肺组织支气管周围大量以嗜酸性粒细胞和淋巴细胞为主的炎细胞浸润；地塞米松干预组小鼠气道炎症程度减轻，支气管肺泡灌洗液中嗜酸性粒细胞、单核细胞和淋巴细胞比哮喘组明显减少，IFN-γ和IL-13分别为（89．25±9．71）和（52．37±8．69）pg／mL，与哮喘组EIFN-γ和IL-13分别为（66．71±7．51）和（85．49±9．23）pg／mL]相比明显改善（P〈0．05）。免疫组化分析表明，AQP5主要表达于Ⅰ型肺泡上皮细胞和气道上皮细胞的腔膜面。哮喘小鼠肺组织中AQP5的表达均较对照组明显减少（mRNA减少约42％，蛋白质减少约64％）。地塞米松上调其表达（与模型组比较，P〈0．05）。结论：哮喘小鼠存在肺液清除功能障碍，肺液含量增?

Effects of dexamethasone on alveolar fluid clearance in mouse asthma models

Objective： To study the effects of dexamethasone （Dex） on alveolar fluid clearance （AFC） in mouse asthma models and explore the possible mechanism. Methods： Forty-eight female C57/BL6 mice were randomly divided into 3 groups （control group, asthma group and Dex group）. The asthma models were established by sensitization with 20 μg of ovalbumin （OVA） and 2.6 mg of aluminum hydroxide on the 1st day, 15th day and challenged with 1% OVA on the 25th to 29th days. The wet/dry,ratio of lung at 2 h and 24 h after the last challenge was measured. The distribution and expression of aquaporin- 5（AQP5） in lung were detected by immunohistochemistry, real-time PCR and Western blotting method. Bronchoalveolar lavage was performed at 24 h after the last challenge and cell counts and the levels of cytokines were examined. Results： The wet/ dry ratio of lung in asthma group was increased significantly at 2 h （4.98±0.46） and 24 h （4.81±0.33） after the last challenge as compared with the control group （P〈0.05）. The wet/dry ratio in Dex group was （4.01±0. 11） at 2 h and （4.21± 0.14） at 24 h,which were obviously decreased as compared with asthma group（P〈0. 05） and had no significant difference from control group（P〉0. 05）. Total cell count, eosinophils and lymphocytes in bronchoalveolar lavage and lung tissue of asthma group were increased significantly while Dex decreased them. The levels of IFN-γ/and IL-13 were downregulated in Dex group E（89. 25±9. 71） and （52.37±8.69） pg/mL] and had significant difference with asthma group（66, 71±7.51） and （85.49±9.23） pg/mL]（P〈0.05）. The expression of AQP5 was mainly located in alveolar type Ⅰ cells and epithelial cells of trachea. The expression of AQP5 in lung tissue of asthma group was obviously downregulated at mRNA level （decreased by about 42 %） and protein level （decreased by about 64 % ）. The expression of AQP5 was upregulated by Dex as compared with asthma group （P〈0.05）. Conclusio