机动车尾气诱发大鼠慢性阻塞性肺疾病并上调气道上皮细胞COX-2/PGE2/EP受体信号通路

目的：探究机动车尾气(MVE)长期暴露引起大鼠慢性阻塞性肺疾病(COPD)发生时，气道上皮细胞中环加氧酶2(COX-2)/前列腺素E₂(PGE₂)/E-前列腺素类激素(EP)受体信号通路成员的表达变化。方法：(1)动物实验：健康雄性SD纯系大鼠(SPF级)16只，随机分为2组：MVE暴露组(n=8)和空白对照(CTL)组(n=8)。采用MVE暴露6个月的方法建立COPD大鼠模型。造模结束后，使用Buxco小动物有创肺功能仪检测大鼠肺功能；肺组织切片行HE染色并评估肺组织病理变化；ELISA法检测大鼠支气管肺泡灌洗液(BALF)中炎症因子白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)和PGE₂的水平，评估大鼠肺部炎症情况；采用免疫荧光及Western blot法检测肺组织COX-2及EP受体蛋白水平；提取肺组织核蛋白，Western blot检测MVE对肺组织NF-κB核转位的影响。(2)细胞实验：采用MVE细颗粒物(PM2.5)标准品刺激人正常支气管上皮细胞BEAS-2B。ELISA法检测细胞培养液中PGE

Activation of COX-2/PGE;/EP receptor pathway in airway epithelial cells from COPD rats induced by exhaust emissions of vehicles

AIM:To study the effects of motor vehicle exhaust(MVE)exposure on the changes of cyclooxygenase-2(COX-2)/prostaglandin E;(PGE;)/E-prostanoid(EP)receptor signaling pathway in airway epithelial cells from chronic obstructive pulmonary disease(COPD)model rats.METHODS:Sixteen male SD rats were randomly divided into MVE inhalation group(n=8)and control(CTL)group(n=8).A COPD rat model was established after a 6-month MVE exposure.Lung functions were assessed using Buxco lung function measurement system.The lung tissue slices were subjected to HE staining for pathological evaluation.The inflammatory cells from bronchoalveolar lavage fluid(BALF)were counted,and the levels of PGE;,interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)in BALF were assayed by ELISA.Furthermore,cultured normal human bronchial epithelial BEAS-2B cells were used to evaluate the effects of PM2.5 on COX-2/PGE;/EP receptor signaling pathway.The PGE;,IL-6 and TNF-αlevels in cell culture medium were assayed by ELISA.The expression levels of COX-2,PGE;,EP1,EP2,EP3 and EP4 in lung tissues and BEAS-2B cells were determined by Western blot.The NF-κB nuclear translocation in lung tissues and BEAS-2B cells was evaluated by Western blot.RESULTS:Long-term MVE exposure resulted in COPD-like symptoms,including lung inflammation,emphysema and lung function decline,accompanied with increased protein levels of COX-2 and EP1/EP4 receptors in lung tissues and airway epithelial cells of the rats(P<0.05).The protein levels of EP2 and EP3 receptors were not changed by MVE exposure(P>0.05).In BEAS-2B cells,PM2.5 stimulated the secretion of PGE;,IL-6 and IL-8,and increased the expression of COX-2,PGE;and EP1/EP4 receptors(P<0.05).The protein levels of EP2 and EP3 receptors remained unchanged(P>0.05).Furthermore,nuclear translocation of NF-κB was observed in both MVE-exposed rat lung tissues and PM2.5-treated BEAS-2B cells(P<0.05).CONCLUSION:Exposure to MVE promotes COPD through COX-2-PGE;-EP1/4 receptor signaling pathway and NF-κB nuclear translocation in airway epithelial cells.