抗原特异性iTr35细胞在过敏性哮喘免疫耐受中的作用及机制研究

The defect of immune tolerance to inhaled allergens has been described in allergic asthmatics, but the underlying mechanisms remain unclear. Studies demonstrated that the immune response of CD4+ T cells was closely associated with allergic asthma. IL-35 producing allergen-specific induced regulatory T cells (iTr35) can induce immune tolerance of CD4+ T cell. Our previous results showed that IL-35 expression levels and the number of iTr35 in peripheral blood from allergic asthmatics were lower than those in healthy subjects. Accordingly, we hypothesize that an insufficient number or dysfunction of allergen-specific iTr35 may cause the defect of immune tolerance of CD4+ T cells, which is an important pathogenesis of allergic asthma. To verify this hypothesis, we will detect the immune characterization of iTr35 from allergic asthma patients and analyze its correlation with CD4+ T cell immunity. Then we will study the impact of iTr35 from allergic asthma patients on immune response of CD4+ T cells and analyze its underlying mechanisms by direct or mixed cell culture experiment, respectively. Finally, we will establish a mouse model of asthma with wildtype and EBI3-/-, and exogenous allergen-specific iTr35 will be adoptively transferred into these mice. The capacity of iTr35 on immune response of CD4+ T cells of these mice will be evaluated. This project will elucidate the mechanisms of abnormal immune tolerance to inhaled allergens in allergic asthmatics and provide a new idea for the prevention and treatment of asthma.

过敏性哮喘患者对过敏原的免疫耐受存在缺陷，但机制不详。研究证实，CD4+ T细胞免疫反应与过敏性哮喘的发生密切相关，而分泌IL-35的抗原特异性调节性T细胞（iTr35）具有诱导CD4+ T细胞免疫耐受功能。我们前期实验发现：过敏性哮喘患者外周血iTr35比例和IL-35水平低于健康人。据此我们假设：过敏原特异性iTr35数量或功能不足可能导致CD4+ T细胞免疫耐受缺陷，是过敏性哮喘发病的重要机制之一。本项目将分析过敏性哮喘患者iTr35免疫学特征，阐明其与CD4+ T细胞免疫功能的相关性；体外建立细胞培养体系，探讨iTr35对过敏性哮喘患者CD4+ T细胞功能的影响及机制；建立野生型和EB病毒诱导基因3（EBI3）缺陷小鼠哮喘模型，过继转移抗原特异性iTr35，观察iTr35对哮喘小鼠CD4+ T细胞功能的影响。本项目有望阐明哮喘患者对过敏原免疫耐受缺陷的机制，为哮喘的防治提供新思路。

过敏性哮喘是呼吸系统常见的慢性气道炎症性疾病。过敏性哮喘患者对过敏原的免疫耐受存在缺陷，但具体机制不详。CD4+ T细胞免疫反应与过敏性哮喘的发生密切相关，而分泌IL-35的抗原特异性调节性T细胞（iTr35）具有诱导CD4+ T细胞免疫耐受功能。本研究分析过敏性哮喘患者iTr35免疫学特征，阐明其与CD4+ T细胞免疫功能的相关性，探讨iTr35对过敏性哮喘患者CD4+ T细胞功能的影响及机制。我们发现：（1）与无症状过敏个体和健康受试者相比，对Derp1过敏的哮喘患者外周血iTr35细胞数目和IL-35表达水平明显降低；（2）随着哮喘严重程度的加重，哮喘患者外周血iTr35细胞比例和IL-35表达水平逐渐降低；（3）与无症状个体和健康受试者相比，过敏性哮喘患者暴露于过敏原后，naive CD4+ T细胞转化为iTr35细胞和IL-35产生减少；（4）iTr35细胞能够以依赖IL-35的方式抑制抗原驱动的naive CD4+ T细胞向Th2细胞分化；（5）iTr35细胞能够抑制抗原诱导的效应性T细胞增殖和Th2型细胞因子（IL-4，IL-5，IL-13）的产生。我们的研究结果提示iTr35细胞可能通过分泌IL-35在预防过敏原诱导的Th2细胞应答中发挥重要作用，iTr35细胞可能是过敏性哮喘潜在的新型免疫调节剂，为哮喘的防治提供了新思路。