IL-17A抑制Th2细胞分化减轻哮喘小鼠气道嗜酸性粒细胞炎症

目的 研究IL-17A对哮喘小鼠Th2细胞分化及其相关炎症的作用.方法 24只C57BL/6J小鼠按随机数字表法分为对照组、哮喘组和IL-17A处理组(n=8).哮喘组和IL-17A处理组予以卵清蛋白(ovalbumin,OVA)致敏及激发.每次雾化激发前1h,IL-17A处理组给予重组小鼠IL-17A气道滴入.各步对照均予以生理盐水.末次激发后24h处死小鼠,收集支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)行细胞总数及分类计数.ELISA检测BALF中IL-4、IL-5、IFN-γ、IL-17A的浓度.HE和PAS染色及半定量评分评估小鼠肺部病理变化.流式细胞术检测脾脏和支气管淋巴结Th细胞分化.免疫磁珠分选健康小鼠幼稚CD4+T细胞,用Th2极化培养基体外培养,并给予IL-17A或等量PBS干预,检测Th2细胞的增殖、凋亡和分化.结果 哮喘组较对照组,BALF中细胞总数、嗜酸性粒细胞数及其比例(P＜0.05)、IL-4、IL-5、IL-17A浓度均显著增高(P＜0.05),IFN-γ浓度显著下降(P＜0.05);支气管、血管周围炎症细胞浸润和杯状细胞化生明显加重(P＜0.01);脾脏和淋巴结Th2细胞分化比例显著增高(P＜0.05).IL-17A处理组较哮喘组,BALF中的细胞总数(26.00±5.43)×104/mLvs(58.40 ±26.93)×104/mL,P＜0.05]、嗜酸性粒细胞数(8.04±1.98)×104/mL vs(31.95±12.28)×104/mL,P＜0.05]及其比例(29.93 ±3.03)％ vs(53.47 ±6.62)％,P＜0.01]显著降低,而中性粒细胞数及其比例无明显变化;BALF中Th2相关因子IL-4浓度(9.86 ±2.77) pg/mL vs(28.13 ±4.62) pg/mL,P＜0.01]、IL-5浓度(7.30 ±0.50) pg/mL vs(10.50±1.10) pg/mL,P＜0.01]均显著降低;支气管、血管周围炎症细胞浸润减轻,HE染色半定量评分降低(2.00 ±0.51)vs(3.12 ±0.64),P＜0.05],杯状细胞化生减少(0.80 ±0.45)vs(2.40 ±0.55),P＜0.01];脾脏(2.24±0.44)％vs(4.82±1.83)％,P＜0.01]和淋巴结(7.05±0.58)％vs(10.57±1.35)％,P＜0.05]中Th2细胞分化比例显著减少.极化培养的幼稚CD4+T细胞,予IL-17A干预后,诱导分化的Th2细胞比例显著减少(P＜0.05),而增殖和凋亡无显著变化.结论 IL-17A有抑制Th2细胞分化,减轻哮喘小鼠气道嗜酸性粒细胞炎症的作用.

IL-17A inhibits Th2 cell differentiation and alleviates eosinophilic airway inflammation in a mouse model of asthma

Objective To investigate the effect of IL-17A on the differentiation of Th2 cells and airway inflammation in a mouse model of asthma.Methods Twenty-four C57BL/6J mice were randomly divided into control group,asthmatic group and IL-17A treatment group.The mice in asthmatic group and IL17A treatment group were sensitized and challenged with ovalbumin (OVA),and in the latter group,the mice received intratracheal instillation of IL-17A 1 h before each OVA challenge;normal saline was used for all the control treatments.The mice were sacrificed 24 h after the last challenge,and the bronchoalveolar lavage fluid (BALF) were collected for cytological examination and detection of IL-4,IL-5,IL-17A,and interferon-γ(IFN-γ) using ELISA.The lung pathologies were assessed semi-quantitatively using HE and PAS staining.The differentiation of Th cells in the spleen and tracheobronchial lymph nodes were analyzed with flow cytometry.The effects of IL-17A on cell proliferation,apoptosis,and differentiation were examined in naive CD4 +T cells sorted by immunomagnetic beads from normal mice.Results Compared with the control mice,the asthmatic mice showed significantly increased total cell and eosinophil counts and eosinophil percentage (P ＜ 0.05),elevated IL-4,IL-5,and IL-17A concentrations (P ＜ 0.05),and lowered IFN-γ concentration in the BALF (P ＜ 0.05).The asthmatic mice presented with more obvious inflammatory cell infiltration (P ＜0.01) and goblet cell hyperplasia (P ＜ 0.05) and significantly increased proportion of Th2 cells in the spleen and lymph nodes (P ＜ 0.05).IL-17A treatment of the asthmatic mice significantly reduced the total cell number (26.00 ± 5.43) × 104/mL vs (58.40 ± 26.93) × 104/mL,P ＜ 0.05],eosinophil count (8.04 ±1.98) × 104/mL vs (31.95 ± 12.28) × 104/mL,P ＜ 0.05] and eosinophil percentage (29.93 ± 3.03) ％vs (53.47 ± 6.62)％,P ＜0.01] in the BALF without affecting neutrophil count or percentage.IL-17A treatment also resulted in lowered levels of IL-4 (9.86 ±2.77 pg/mL vs 28.13 ±4.62 pg/mL,P ＜0.01) and IL-5 (7.30 ±0.50 pg/mL vs 10.50 ± 1.10 pg/mL,P ＜ 0.01) in the BALF,alleviated inflammatory cell infiltration (2.00 ±0.51 vs 3.12 ± 0.64,P ＜0.05) and goblet cell hyperplasia (0.80 ±0.45 vs 2.40 ±0.55,P ＜0.01),and reduced the percentages of Th2 cells in the spleen (2.24 ± 0.44)％ vs (4.82 ±1.83)％,P＜0.01] and lymph nodes (7.05 ±0.58)％ vs (10.57±1.35)％,P＜0.05].In naive CD4 + T cells from normal mice,IL-17A treatment obviously inhibited cell differentiation into Th2 cells in vitro (4.15 ± 0.55) ％ vs (2.53 ± 0.47) ％,P ＜ 0.05] without affecting the cell proliferation or apoptosis.Conclusion IL-17A can inhibit the differentiation of Th2 cells and alleviate eosinophilic airway inflammation in mice.