大气细颗粒物诱导IL-17A表达增强香烟暴露小鼠气道炎症反应的机制

PM-induced IL-17A expression enhances airway inflammation in cigarette-exposed mice

目的探讨大气细颗粒物(PM)增强香烟暴露小鼠炎症反应的机制。方法用野生型(WT)及IL-17A基因敲除(IL-17A^(-/-))小鼠,按随机数字表法随机分为对照组、熏烟组、PM组、熏烟+PM组,每组6~8只。采用香烟烟雾暴露装置烟熏,气道滴注方法吸入PM,观察气道炎症反应,连续干预3个月后取检。用HE检测肺组织炎症浸润、用ELISA及RT-PCR检测肺组织炎症因子表达、免疫组化检测平滑肌表达、Masson染色观察胶原沉积及细胞流式检测分泌IL-17A的淋巴细胞类型。体外实验,用不同浓度的香烟提取物(CSE)和/或大气细微颗粒(PM)刺激人气道上皮(HBE)细胞,用IL-17A siRNA转染在HBE细胞中敲除IL-17A基因,用RT-PCR检测炎症因子表达。结果与对照组、熏烟组及PM组比较,熏烟联合PM组小鼠肺组织炎症因子(CXCL1、TFG-β1、IL-6及IL-17A)、胶原沉积及平滑肌表达明显增高。相反,IL-17A^(-/-)小鼠能缓解上述指标。流式细胞检测发现PM主要通过调控CD4^(+)细胞促进IL-17A表达,增强熏烟诱导的炎症反应。在体外,CSE、PM分别干预HBE细胞均能诱导IL-6、IL-8表达,而CSE联合PM干预HBE细胞能进一步增加IL-6、IL-8表达。敲除HBE细胞IL-17A基因后,能缓解IL-6、IL-8表达。结论 PM能诱导IL-17A表达,加剧熏烟小鼠肺组织的炎症反应、胶原沉积及平滑肌增生,提示针对IL-17A信号通路靶向治疗可能对缓解PM导致的慢性阻塞性肺疾病急性加重有效。

Objective This study aimed to investigate the mechanisms of atmospheric fine particulate matter(PM),which enhanced the inflammatory response in cigarette-exposed mice.Methods Wild-type and IL-17 A knockout(IL-17 A-/-)mice were randomly divided into the control group,smoked group,PM group and smoked+PM group according to the random number table method(6-8 mice/group).Mice were exposed to smoke using cigarette smoke exposure device.PM was inhaled by airway instillation,and airway inflammation was observed.After continuous intervention for 3 months,mice were sacrificed to measure airway inflammation.HE was used to detect inflammatory infiltration in lung tissue,and ELISA and RT-PCR were used to detect inflammatory cytokines in lung tissue.Smooth muscle expression was detected by immunohistochemistry,and collagen deposition was observed by Masson staining.In addition,IL-17 A-secreting lymphocytes were detected by cell flow cytometry.In in vitro experiments,different concentrations of cigarette smoke extract(CSE)and/or PM were used to stimulate human airway epithelial(HBE)cells,and IL-17 A siRNA was used to knock down IL-17 A gene in HBE cells.RT-PCR detects the expression of inflammatory factors.Results Compared with the control,smoked and PM groups,lung tissue inflammatory factors(CXCL1,TFG-β1,IL-6 and IL-17 A),collagen deposition and smooth muscle expression were significantly increased in the smoked+PM group.By contrast,IL-17 A-/-mice can alleviate the above-mentioned indicators.Flow cytometry found that PM promoted IL-17 A expression by regulating CD4 cells and worsened the inflammatory response induced by smoking.In vitro,CSE or PM intervention in HBE cells can induce the secretion of IL-6 and IL-8,whereas CSE combined with PM can further increase the expression of IL-6 and IL-8.Knockout of IL-17 A gene in HBE cells can alleviate the expression of IL-6 and IL-8.Conclusion PM can induce the expression of IL-17 A and exacerbate the inflammation,collagen deposition and smooth muscle hyperplasia in the lung tissue of cigarette-exposed mice,suggesting that targeted therapy for the IL-17 A signalling pathway may be effective in relieving acute exacerbation of COPD caused by PM.