Effect of Cigarette Smoke Exposure on the Expression of Aquaporin 5 in Pulmonary Tissues of Bronchial Asthmatic Rats
英文关键字：smoking exposure; bronchial asthma; aquaporin 5; MUC5AC
目的 探讨香烟烟雾暴露对支气管哮喘大鼠肺组织水通道蛋白5(Aquaporin 5，AQP5)和黏蛋白5AC(MUC5AC)表达的影响。方法 将30只雄性SD大鼠随机分为3组(n=10)，对照组雾化生理盐水，哮喘组采用卵清白蛋白(OVA)致敏并吸入激发制备哮喘模型，哮喘+烟雾暴露组于每日雾化激发OVA前给予香烟烟雾吸入。收集支气管肺泡灌洗液(BALF)进行白细胞计数及分类，测定肺组织病理变化及湿干重比值。实时定量PCR (Real-time PCR)测定AQP5和MUC5AC mRNA的表达，免疫组化法测定AQP5蛋白分布情况，免疫印迹法(Western blot)测定AQP5蛋白的表达，酶联免疫吸附试验(ELISA)测定BALF中MUC5AC的含量。结果 ①与对照组相比，哮喘组大鼠BALF中白细胞、淋巴细胞、嗜酸粒细胞、中性粒细胞数量明显增加；与哮喘组相比，暴露组大鼠BALF中白细胞、中性粒细胞数量明显增加，差异均有统计学意义(P＜0.05)。②与对照组相比，哮喘组和暴露组大鼠肺组织中AQP5表达明显减少，而MUC5AC蛋白含量明显增加；与哮喘组相比，暴露组大鼠肺组织中AQP5明显减少，而MUC5AC蛋白含量明显增加，差异均有统计学意义(P＜0.05)。③肺组织中AQP5表达与肺组织BALF中MUC5AC蛋白含量呈负相关(r=-0.852和-0.895，P<0.05)。结论 香烟烟雾暴露可导致哮喘大鼠肺组织AQP5表达减少而MUC5AC含量增加，进一步加重哮喘气道炎症和黏液高分泌反应，这可能为哮喘吸烟患者的早期防治提供新思路。
Objective To investigate the effect of cigarette smoke exposure on the expression of aquaporin 5 (AQP5) and MUC5AC in pulmonary tissues of bronchial asthmatic rats. Methods Thirty male SD rats were randomly divided into three groups (n=10): a control group，an aerosolized ovalbumin (OVA) group and a combined OVA with cigarette smoke exposure group. These rats were exposed to normal saline or OVA aerosol or cigarette smoke, respectively. The total number and classification of white blood cells in bronchoalveolar lavage fluid (BALF) of rats were studied. The pathological changes and wet/dry weight ratio of pulmonary tissues were determined. The expression of AQP5 and MUC5AC mRNA in pulmonary tissues were examined by real-time polymerase chain reaction (Real-time PCR). The distribution and quantity of AQP5 protein in pulmonary tissue were measured by immunohistochemical assay and western blotting, respectively. The content of MUC5AC in BALF was detected by ELISA assay. Results ① The numbers of leukocytes, lymphocytes, neutrophils and eosinophils in BALF of OVA group and exposure group were remarkably increased compared with the control group (P＜0.05), and the numbers of leukocytes and neutrophils in BALF of exposure group were also higher than the OVA group (P＜0.05). ② The expression of AQP5 protein in pulmonary of OVA group and exposure group were significantly decreased, while the content of MUC5AC was increased compared with the control group (P＜0.05); the expression of AQP5 protein in pulmonary of exposure group was obviously decreased，while the content of MUC5AC was increased compared with the OVA group (P＜0.05). ③ The expression of AQP5 was negatively correlated with MUC5AC in pulmonary tissues of bronchial asthmatic rats (P＜0.05). Conclusions Cigarette smoke exposure could inhibit the expression of AQP5 and elevate the content of MUC5AC in pulmonary tissues of bronchial asthmatic rats, and then aggravated the airway inflammation and overproduction of airway mucus in bronchial asthmatic rats. Such findings can be a new thought for early prevention and treatment of bronchial asthmatic patients with smoking.