基于Notch信号通路研究Th17对肥胖哮喘气道高反应性的调控作用及机制

Airway hyperresponsiveness (AHR) is the typical characteristics of asthma. Obesity increases the severity of AHR in individuals with asthma, however the mechanism has not been elucidated. T helper cells (Th) 17 are involved in the development of AHR. Th17-assosiated cytokine interleukin (IL)-17A can promote the contraction and proliferation of airway smooth muscle cells (ASMC) which are closely related with AHR. Notch signal pathway is involved in the regulation of asthma, obesity and Th17 cells. Our previous studies have shown that Th17 cells in obese asthma are associated with AHR. γ-secretase inhibitors (GSI) which has been used as an effective blockage of Notch signal pathway and Notch ligand D114 regulate the differentiation of Th17 cells. Therefore, we propose the hypothesis that Th17 cells play an important role in the pathogenesis of AHR in obese asthma through Notch signal pathway. To verify this hypothesis, the construction of obese asthma mice, IL-17A-/- mice and obese asthma mice treated with GSI or anti-Dll4 antibody, the combined detection of AHR in both mouse lung function instrument and tracheal rings, as well as ASMC culture and intervention trials are used to explore the role of Th17 cells in obese asthma, demonstrate whether Th17 cells in regulation of AHR via Notch signal pathway is an important mechanism of AHR in obese asthma or not, and it will be crucial for us to understand the pathogenesis of obese asthma.

气道高反应性（AHR）是哮喘的基本特征，肥胖哮喘AHR更为严重，其机制尚未阐明。辅助性T细胞（Th）17参与AHR的发生，Th17相关因子白介素（IL）-17A促进气道平滑肌细胞（ASMC）收缩和增殖，与AHR存在关联。Notch信号通路参与哮喘、肥胖和Th17的调控。前期研究表明，肥胖哮喘Th17细胞与AHR关系密切，Notch信号通路阻滞剂GSI和配体Dll4调控Th17的分化。因此，我们提出假设：基于Notch信号通路对Th17的调控是肥胖哮喘AHR产生的重要机制。为验证该假设，构建肥胖哮喘小鼠、IL-17A基因敲除小鼠、GSI干预动物模型和抗Dll4抗体干预动物模型，小鼠肺功能仪整体检测和气管环离体检测AHR，开展ASMC培养和干预试验，探讨Th17对肥胖哮喘AHR的影响，阐明基于Notch信号通路对Th17的调控是否为肥胖哮喘AHR产生的重要机制，将深化肥胖哮喘AHR的发病机制。

气道高反应性（AHR）是哮喘的基本特征。当前，肥胖是世界上严重的健康挑战之一。许多研究表明，肥胖与哮喘的发病存在显著相关性，儿童哮喘国际共识（ICON）将肥胖哮喘列为哮喘的一种特殊表型。辅助性T细胞（Th）17参与AHR的发生，Th17相关因子白介素（IL）-17A促进气道平滑肌细胞（ASMC）收缩和增殖，与AHR存在关联。Notch信号通路参与哮喘、肥胖和Th17的调控。前期研究表明，肥胖哮喘Th17细胞与AHR关系密切，Notch信号通路阻断剂γ-分泌酶抑制剂(GSI)和抗Notch配体（Dll4）调控Th17的分化。因此，本研究探讨Notch信号通路对Th17的调控是肥胖哮喘AHR产生的重要机制。课题组研究发现IL-17A基因敲除组小鼠的气道阻力（Rn）升幅较肥胖哮喘组和重组IL-17A组小鼠的Rn升幅明显降低。IL-17A基因敲除组小鼠肺组织RAS同源基因家族成员A（RhoA）等收缩相关蛋白和IL-17A表达均较肥胖哮喘模型组和重组IL-17A组小鼠显著降低。Th17相关因子IL-17A参与肥胖哮喘AHR的发生，影响气道平滑肌的收缩敏感性。GSI和Dll4抗体抑制肥胖哮喘小鼠的AHR，减少脾脏中Th17/CD4+T细胞比例和血清中IL-17细胞因子的分泌水平，降低肺组织RhoA和Rock等收缩相关蛋白的表达。同时GSI和抗Dll4抗体干预处理能明显抑制Th17细胞分化。研究表明，肥胖哮喘模型Dll4-Notch1信号通路参与肥胖哮喘Th17相关AHR的发生以及气道平滑肌收缩的调控，为今后精准治疗肥胖哮喘提供了理论基础。