IL-25/IL-33/TSLP应答轴在调节Th2型免疫应答和哮喘发生与转归过程中的作用研究

Asthma is a common disease seriously threatening public health, characterized with chronic airways inflammation and airways remodeling. Based on preliminary findings, we propose that after antigen stimulation, patient's airway epithelial cells are able to produce cytokines IL-25, IL-33 and TSLP. These cytokines act on the feedback not only epithelial cells to promote the production of other active mediators, but also act on other effector cells to enlarge Th2 type immune response, which form an axis response based on IL-25/IL-33/TSLP actions, resulting in the development of asthma. Thus, this responsive axis may be a novel target for further studying intervention strategies in asthma therapy. In the present study, we plan to use multiple antigens to stimulate airway epithelial cell, analyze initiative factors, productive phases and regulative targets involved in triggering the production/secretion of IL-25, IL-33 and TSLP; to investigate the roles of such epithelial-derived cytokines in Th2 -type immune response, primarily through their effects on major target cells including ILC2 and T cells; to employ antibody blocking experiments in vivo in a IL-25-induced murine asthma model to further understand the roles of IL-25, IL-33 and TSLP in the pathogenesis and outcome of asthma. This study will improve the theoretical foundation of Th2 -type immune diseases, clarify the mechanisms of chronic inflammation and airway remodeling in asthma and provide a good foundation for screening potential drug targets in the therapeutics of asthma.

哮喘是严重威胁社会公众健康的常见疾病，以慢性气道炎症和气道重塑为特征。基于前期研究结果，课题组提出：机体接受抗原刺激后，气道上皮细胞产生IL-25、IL-33和TSLP，这些细胞因子不仅反馈作用于上皮细胞促进其他活性介质的产生，还能作用于其它效应细胞而放大Th2型免疫应答，形成IL-25/IL-33/TSLP应答轴，最终导致哮喘的发生发展，该应答轴可能是进一步研究哮喘干预策略的新靶点。本研究拟采用多种抗原刺激气道上皮细胞，分析诱导其分泌IL-25、IL-33和TSLP的始动因素、时相和调控靶点；通过它们对主要靶细胞ILC2细胞和T细胞的效应，探讨上皮源性细胞因子在Th2型免疫应答中的作用；利用小鼠体内抗体阻断实验，了解IL-25、IL-33和TSLP在哮喘疾病转归中的作用。本研究将为完善Th2型免疫性疾病的理论基础，阐明哮喘慢性炎症和气道重塑的发生机制以及筛选药物靶标奠定良好基础。

本课题对IL-25/IL-33/TSLP在哮喘发病和转归中的作用进行研究。课题组获得的重要结果如下：1. 细胞因子IL-33和TSLP是哮喘尤其是难治性哮喘发生发展的重要靶分子。课题组收集哮喘患者70例和健康志愿者30例的支气管肺泡灌洗液，检测发现哮喘患者支气管肺泡灌洗液中IL-33和TSLP的浓度明显高于对照组，而且其浓度与哮喘患者肺功能呈显著负相关。同时哮喘患者支气管肺泡灌洗液中IL-33与TSLP浓度呈显著正相关，但只有IL-33的浓度与Th2型细胞因子IL-13呈显著正相关，而TSLP的浓度与支气管肺泡灌洗液中中性粒细胞数呈显著相关性。此外，哮喘患者和健康志愿者的支气管肺泡灌洗液中IL-25的浓度均处在基线下。2. 首次平行观察了过敏原攻击前后，过敏性哮喘患者支气管黏膜中IL-25、IL-33和TSLP三种细胞因子的表达情况和主要细胞来源，及与过敏原暴露所诱导的肺功能变化的相关性。3. PI3K信号通路有望成为哮喘干预治疗的分子靶标。该通路抑制剂在短期内可有效减轻IL-25诱导的小鼠气道炎症，长期可显著减轻IL-25诱导的气道重塑。四，采用模型小鼠阐明IL-33、IL-25和TSLP在哮喘发生发展中的作用机制及其相互关系。五，采用体外和小鼠体内实验证实IL-33而非IL-25能直接诱导ILC2细胞向肺组织聚集。上述研究表明IL-33，IL-25及TSLP在哮喘发病过程中可能通过自己特有的途径发挥作用。相比之下，IL-33和TSLP与哮喘尤其是难治性哮喘的关系更密切，两者很可能是哮喘内表型分类的潜在靶标，也是哮喘个体化靶向治疗的方向。