白细胞介素25对过敏性哮喘嗜酸粒细胞祖细胞的影响

The mobilization effect of IL-25 on eosinophil progenitor cells in allergic asthma

目的探讨IL-25在过敏原诱发的支气管哮喘(哮喘)患者中对嗜酸粒细胞系祖细胞(EoP)增殖、迁移反应,并在动物实验中验证敲除IL-25后哮喘小鼠新生嗜酸粒细胞的变化。方法对2017—2018年期间我院门诊14例哮喘患者分别于过敏原激发前和激发后24 h采血,通过流式细胞术检测哮喘患者过敏原激发前后EoP表面IL-17RA和IL-17RB的表达水平,然后分选出造血祖细胞(HPC)和EoP细胞通过迁移小室评估其趋化迁移能力。在动物模型实验中,根据是否敲除IL-25和通过卵清白蛋白(OVA)致敏激发将小鼠分为哮喘组、对照组、敲除后哮喘组和敲除后对照组,采集小鼠肺组织、肺泡灌洗液(BALF)及骨髓组织并评估其气道炎症、新生和成熟嗜酸粒细胞(Eos)数量等。结果过敏性哮喘患者吸入过敏原24 h后,外周血表达IL-25高亲和力受体IL-17RB的EoP数量显著增加[激发前后分别为(514±138)和(1 146±450)/106个白细胞,F=6.819,P=0.022]。IL-25预处理后可增加EoP在祖细胞趋化剂基质细胞衍生因子1α(SDF-1α)的作用下于迁移小室中的迁移细胞比例[SDF-1α组和IL-25组(1 ng/L)分别为(39.0±10.1)%和(73.0±7.9)%,P=0.021]。在OVA致敏和激发小鼠中,敲除IL-25显著减轻了OVA诱导的气道Eos细胞浸润[哮喘组与敲除后哮喘组BALF中Eos细胞比例分别为(7.8±2.0)%和(3.1±0.6)%,P=0.002]和肺内新生的Eos细胞数目[哮喘组与敲除后哮喘组BALF中Brdu阳性Eos细胞分别为(50.0±7.6)%和(8.6±4.3)%,P=0.011]及肺组织炎症[哮喘组与敲除后哮喘组肺组织炎症指数分别为(1.63±0.11)和(0.93±0.10),P=0.000],同时也降低了骨髓新生Eos的数量[哮喘组与敲除后哮喘组骨髓中Brdu阳性Eos细胞分别为(70.8±6.1)%和(1.3±1.3)%,P=0.000]。结论 IL-25在过敏原诱导的EoP气道迁移、局部分化和组织嗜酸性细胞增多中具有重要作用。

Objective Eosinophil progenitor cells (EoP) play a critical role in allergic airway inflammation in asthma. Previous studies have revealed that the expression of IL-25 receptor subunits (IL-17RA and IL-17RB) are increased on eosinophils (Eos) from allergic asthmatics upon allergen inhalation but few study has explored the role of IL-25 on EoP. Thus, in this research we examined the possible role of IL-25 on EoP in allergic asthmatics challenged by allergen, as well as in animal models where we verified the changes of newly produced Eos after IL-25 knockout. Methods Asthmatics (n=14, during 2017-2018) who developed allergen-induced early and late responses were enrolled in this study. Blood was collected at pre-and 24 h post-challenge. Surface expression of IL-17RA and IL-17RB were evaluated by flow cytometry on EoP. In vitro migration assay was used to examine migrational responses of EoP and hematopoietic cells (HPC) from these subjects. In animal models, mice were grouped according to whether IL-25 was knock-out and whether mice were sensitized and challenged by ovalbumin (OVA) into asthmatic, control, knockout asthmatic and knockout control groups. Lung tissues, bronchoalveolar lavage flow (BALF) and bone marrow tissues of these mice were collected in order to evaluate airway inflammation and amount of newly produced (Brdu positive) and mature Eos. Results EoP expressing IL-17RB were significantly increased after allergen inhalation in allergic asthmatics [(514±138) vs.(1146±450)/106 cells, pre-and post-challenge, F=6.819, P=0.022]. Pre-exposure to IL-25 primed the migrational responsiveness of EoP to stromal cell-derived factor (SDF)1α[(39.0±10.1)% vs.(73.0±7.9)%, control and IL-25 exposure groups respectively, P=0.021, 95% CI 5.19%~58.45%]. In OVA sensitized mice, knockout of IL-25 significantly reduced Eos and newly produced Eos percentage in the BALF [Eos,(7.8±2.0)% vs.(3.1±0.6)%, asthmatic and knockout asthmatic group respectively, P=0.002, 95% CI-7.57% to -1.98%;Brdu positive Eos,(50.0±7.6)% vs.(8.6±4.3)%, asthmatic and knockout asthmatic group respectively, P=0.011, 95% CI-72.41% to -10.27%], and newly produced Eos were also reduced in the bone marrow [(70.8±6.1)% vs.(1.3±1.3)%, asthmatic and knockout asthmatic group respectively, P=0.000, 95% CI -94.88% to -44.18%]. Conclusion These results suggest an important role of IL-25 in allergen-induced EoP migration, local differentiation and eosinophilia in the airways.