低温联合PM2.5对小鼠哮喘气道炎症的影响

为研究低温联合PM_2.5加重哮喘气道炎症的机制，将哮喘模型小鼠随机分为对照组、低温组、PM_2.5组和低温联合PM_2.5暴露组（n=8），饲养于相应环境（4周）.检测细胞因子（IL-4、IL-6、IL-13、IL-17、转化生长因子TGF-β）、氧化应激指标（丙二醛MDA、谷胱甘肽GSH、超氧化物歧化酶SOD、过氧化氢酶CAT）及转录因子（相关孤核受体RORγt、叉头蛋白Foxp3）水平，流式检测Th17和Treg细胞数量差异.结果表明，联合暴露组小鼠支气管炎症细胞浸润最为明显.与对照组相比，其余3组IL-6、IL-17和TGF-β水平均较高，CAT水平较低，以联合暴露组影响最显著.联合暴露组Th17细胞比例最高，Treg细胞比例最低，RORγt水平显著高于低温组和PM_2.5组.方差分析发现联合暴露对IL-4、IL-13、IL-17、MDA及RORγt的升高有交互作用.低温联合PM_2.5可能通过促进RORγt表达，使Th17/Treg极化而加剧肺部炎症.

Effect of hypothermia combined with PM2.5 on airway inflammation in asthmatic mice

To explore the mechanism of cold stress and PM_2.5 exposure exacerbating airway inflammation of asthma. Asthma model mice were randomly divided into control group, cold stress group, PM_2.5 group and combined exposure group (n=8), and treated with the corresponding exposure environment for 4weeks. The concentration of inflammatory factors Interleukin (IL)-4, IL-6, IL-13, IL-17, transforming growth factor-β (TGF-β), and oxidation indexes such as malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were detected. The relative expressions of retinoid-related orphan nuclear receptor (RORγt) and fork-head box protein (Foxp3) were detected by PCR. The changes of T helper-17cells (Th17) and regulatory cells (Treg) were analyzed by flow cytometry. The infiltration of inflammatory cells in the bronchi in the combined exposure group was the most obvious. Compared with control group, the levels of IL-6, IL-17 and TGF-β in other three groups were higher, while the level of CAT was lower, and the combined exposure group had the most significant effect. The proportion of Th17 cells was the highest and the proportion of Treg cells was the lowest in combined exposure group. The level of RORγt in combined exposure group was significantly higher than that in cold stress group and PM_2.5 group. The interaction test showed that cold stress and PM_2.5 had significant interactive effects on the increase of IL-4, IL-13, IL-17, MDA and RORγt. Co-exposure of cold stress plus PM_2.5 may exacerbate pulmonary inflammation by promoting the expression of RORγt and polarizing Th17/Treg.