烟雾暴露对支气管哮喘大鼠CCR7和Th1／Th2细胞因子表达的影响

Effect of cigarette smoke exposure on the expression of CCR7 and levels of Th1/Th2 cytokines inasthmatic rats

目的观察烟雾暴露对支气管哮喘（简称哮喘）大鼠肺组织CC趋化因子受体7（CCR7）和辅助性T细胞（Th1/Th2）细胞因子表达的影响。方法40只雄性Wistar大鼠按随机数字表法随机分为对照组、哮喘组、烟雾暴露组和哮喘＋烟雾暴露组各10只。哮喘组用卵清白蛋白（OVA）和氢氧化铝在第1、8天致敏，并于第15天雾化激发，持续8周，对照组以生理盐水代替OVA，烟雾暴露组以生理盐水代替OVA并给予8周香烟烟雾吸入处理，哮喘＋烟雾暴露组每次先给予烟雾吸入再用OVA激发。HE染色观察其肺组织病理变化，免疫组织化学法测定肺组织CCR7表达（以阳性颗粒平均光密度表示），酶联免疫吸附试验（ELISA）检测支气管肺泡灌洗液（BALF）中CC趋化因子配体（CCL）19和CCL21以及血浆中CCL19、CCL21、干扰素（IFN）－γ和白细胞介素（IL）－4的含量变化。结果哮喘组、烟雾暴露组、哮喘＋烟雾暴露组肺组织发生不同程度的炎症反应，其中哮喘＋烟雾暴露组炎症反应最明显；哮喘组、烟雾暴露组、哮喘＋烟雾暴露组肺组织CCR7表达均显著高于对照组（0.350±0.023、0.252±0.022、0.400±0.029比0.180±0.020），哮喘＋烟雾暴露组CCR7表达均显著高于哮喘组和烟雾暴露组（均P〈0.01）；哮喘组、烟雾暴露组、哮喘＋烟雾暴露组BALF和血浆中CCL19和CCL21含量均显著高于对照组，哮喘＋烟雾暴露组CCL19和CCL21含量均显著高于哮喘组和烟雾暴露组（均P〈0.01）；哮喘组、哮喘＋烟雾暴露组大鼠血浆中IFN－γ含量均显著低于对照组[（33±3）、（17±3）比（70±4）pg/ml]，但哮喘＋烟雾暴露组IFN－γ含量低于哮喘组，烟雾暴露组大鼠血浆中IFN－γ含量[（100±5）pg/ml]均显著高于对照组和哮喘＋烟雾暴露组（均P〈0.01）；哮喘组、烟雾暴露组、哮喘＋烟雾暴露组大鼠血浆中IL－4含量均显著高于对照组[（54±4）、（42±4）、（76±4）比（30±4）pg/ml]，哮喘＋烟雾暴露组IL－4含量均显著高于哮喘组和烟雾暴露组（均P〈0.01）。结论烟雾暴露可增加CCR7及其配体CCL19和CCL21的表达，降低Th1细胞因子IFN－γ表达，增加Th2细胞因子IL－4表达，进一步加重哮喘。

ObjectiveTo investigate the effect of cigarette smoke exposure on the expression of CC Chemokine receptor 7 （CCR7） and levels of Th1/Th2 cytokines in asthmatic rats.MethodsForty Wistar rats were randomly divided into four groups： control group, asthma group, smoke exposure group, asthma-smoke exposure group. The asthma group were sensitized with ovalbumin （OVA） and Aluminum hydroxide at day 1, 8 and challenged with OVA at day 15 by atomization for 8 weeks.While control group was sensitized and challenged with normal saline instead of OVA.The smoke exposure group was sensitized and challenged with normal saline instead of OVA followed passive smoking for 8 weeks. The asthma-smoke exposure group was challenged with OVA followed passive smoking. The pathological changes of different groups were observed by HE-staining. CCR7 was semiquantitatively analyzed in lungs by immunohistochemistry.The concentration of CC chemokine ligand （CCL）19, CCL21, interferon （IFN）-γ and interleukin （IL）-4 in peripheral blood and CCL19 and CCL21 in bronchoalveolar lavage fluid （BALF） were measured by enzyme-linked immunosorbent （ELESA） assay.ResultsIn asthma group, smoke exposure group and asthma-smoke exposure group, the various degrees of inflammatory reaction appeared in lung tissue and the asthma-smoke exposure group was with the most significant reaction. In the lung tissues of the rats from asthma group, smoke exposure group and asthma-smoke exposure group, the average optical density （AOD） of CCR7 were significantly higher than those in control group （0.350±0.023, 0.252±0.022, 0.400±0.029 vs 0.180±0.020, all P〈0.01）. The AOD of CCR7 of asthma-smoke exposure group was much higher than both that in asthma group and in smoke exposure group （both P〈0.01）. In asthma group, smoke exposure group and asthma-smoke exposure group, the concentrations of both CCL19 and CCL21 in peripheral blood and BALF were significantly higher than that in control group （all P〈0.01）. The concentrations of both CCL19 and CCL21 in peripheral blood and BALF of asthma-smoke exposure group were significantly higher than the results in asthma group and in smoke exposure group （all P〈0.01）. The concentrations of IFN-γ in peripheral blood of asthma group and asthma-smoke exposure group were lower than those in control group [（33±3）, （17±3） vs （70±4） pg/ml], but asthma-smoke exposure group was much lower than the results in asthma group （all P〈0.01）. The concentration of IFN-γ in peripheral blood of smoke exposure group[（100±5）pg/ml]was higher than that in control group and asthma-smoke exposure group （both P〈0.01）. In asthma group, smoke exposure group, asthma-smoke exposure group, the concentrations of IL-4 in peripheral blood were significantly higher than those in control group [（54±4）, （42±4）, （76±4） vs （30±4） pg/ml, all P〈0.01]. The concentrations of IL-4 in peripheral blood of asthma-smoke exposure group was significantly higher than those in asthma group and in smoke exposure group （both P〈0.01）.ConclusionCigarette smoke could enhance the expression of CCR7 and its ligand, and it can also result in exacerbations of asthma by reducing the expression level of IFN-γ （the representative of Th1 cytokine） and increasing the expression level of IL-4 （the representative of Th2 cytokine）.