PM_(2.5)亚慢性染毒对小鼠肺部炎症及Th17/Treg的影响

Effects of airborne fine particulate matters on pulmonary inflammation injury and Th17/Treg balance of sub-chronic exposure mice

目的研究大气细颗粒物(PM2.5)亚慢性染毒对小鼠肺部炎症的影响,以及Th17/Treg细胞及其相关细胞因子的改变。方法将32只C57BL/6雄性小鼠随机分为4组,每组8只。PM2.5染毒低、中、高剂量组分别为1.5、7.5和15 mg/kg BW,对照组给予相同体积的生理盐水。采用气管滴注的方式进行染毒,每周2次,连续染毒3个月。末次暴露24 h后,麻醉动物,经气管肺泡灌洗收集肺泡灌洗液(BALF),ELISA法测定BALF中细胞因子IL-6、IL-17、IL-10和TGF-β的含量。Real-time PCR法测定肺组织中Th17细胞特异性转录因子ROR-γt及Treg细胞特异性转录因子Foxp3+mRNA的相对表达量。未经灌洗的左肺用4%多聚甲醛固定,进行病理学观察。结果中、高剂量PM2.5暴露引起小鼠BALF中IL-17显著升高,IL-10显著降低(P"0.05)。肺组织中ROR-γt mRNA表达量随染毒剂量的增加而升高,而Foxp3+mRNA表达量则随染毒剂量的增加呈降低趋势。结论大气细颗粒物亚慢性染毒可引起小鼠肺部持续的炎症、免疫损伤,导致Th17/Treg细胞失衡及其相关细胞因子分泌的改变。

Objective To explore effects of fine particulate matters （PM2.5） on pulmonary inflammation, and the changes of Th17/Treg balance as well as related cytokines. Method Thirty-two C57BL/6 male mice were randomly divided into 4 groups including 1 saline control group and 3 PMa5 exposure groups（ 1.5,7.5 and 15 mg/kg BW, respectively）. Each group received intratracheal instillation twice per week for 3 consecutive months. 24 hours after the last exposure, anaesthetize the mice with chloral hydrate, bronehoalveolar lavage fluid （BALF） was collected for inflammatory cells and cytokines analysis. The Th17- and Treg-related cytokines in BALF was measured by enzyme linked immunosorbent assay （ELISA）. The level of the specific transcription factors of Th17 and Treg in lung tissue was determined by real-time PCR. Unlavaged left lung were fixed with 4 % paraformaldehyde for histopathological detection. Result Th17-related cytokine IL-17 increased,but Treg-related cytokine IL-10 decreased significantly in BALF at 7.5 and 15 mg/kg BW PM2.s exposure groups compared with control group（P 〈 0.05）. Consistently, the relative mRNA expression of ROR-γt （specific transcription factors of Th17） increased in a dose-response way,the relative mRNA expression of Foxp3 ＋ （specific transcription factors of Treg） decreased in a dose-response way. Conclusion Sub-chronic PM2.5 exposure caused persistent inflammation,immune injury and disordered the Th17 /Treg imbalance as well as related cytokines.