肺γδT细胞通过IL-17/IL-33轴在新生期RSV感染所致哮喘发生以及成年期RSV感染所致哮喘急性发作中的作用及机制研究

RSV重症感染的婴幼儿，成年后哮喘易感性明显升高。RSV常可诱发哮喘急性发作。申请者及其他研究者发现新生鼠感染RSV后，肺组织γδT细胞数量升高，分泌IL-17A, 且IL-33和IL-13水平升高。提示γδT细胞可能通过IL-17A促进IL-33产生，使新生鼠更易致敏。成年鼠感染RSV后，分泌IL-17A 的γδT细胞数量增高，且IL-33和IFN-γ水平升高，伴中性粒细胞趋化。据此提出假说：“γδT细胞通过IL-17A/IL-33在新生期RSV感染所致哮喘发生以及成年期RSV感染所致哮喘急性发作中发挥作用”。本项目拟建立新生期RSV感染/成年期过敏原诱导哮喘模型，及成年期过敏性哮喘/成年期RSV感染模型。利用基因敲除鼠，结合细胞过继转移、细胞因子和抗体干预手段，以呼吸道哮喘反应为主要检测指标，阐明γδT细胞通过IL-17A/IL-33轴诱导哮喘发生以及急性发作的作用机制。

Respiratory syncytial virus (RSV) is a common cause of severe lower respiratory tract diseases (bronchiolitis and pneumonia) during infancy and early childhood. RSV infection in early life is suspected to play a role in the development of asthma. RSV is also among the most frequent airway virus to induced exacerbation of allergic airways disease. The applicant and others found previously that the primary RSV infection in neonatal mice resulted in an elevated number of γδT cells and IL-17A in the lung, associated with higher levels of IL-33 and IL-13. Theses results suggested that γδT cells may be the major cell type in neonatal lung to fight against RSV infection, and the high IL-33 micromilieu may set the a more susceptible stage for these mice to develop allergic asthma upon allergen sensitization and challenge. Similarly, primary RSV infection in adult mice resulted in an elevated number of γδT cells and IL-17A in the lung. However, the adult mice also developed a Th1-biased immune responses with higher levels of IFN-γ and a wave of neutrophils. Based on these observations, the applicant hypothesize that “ γδT cells play an important role in RSV-induced allergic asthma development and exacerbation through the production of IL-17A”. To closely mimic the clinical settings, we first set up models of neonatal RSV infection-induced allergic asthma development and RSV-induced asthma exacerbation in adult mice with OVA or HDM induced allergic asthma. To determine the role of γδT cells, TCRδKO mice or inactivated γδT cells by anti-TCRδ treatment during RSV infection will be used. To further investigate the possible underlying mechanisms, administration of recombinant IL-17 or IL-33, adoptive transfer of γδT cells from wildtype or IL-17A KO mice into TCRδ KO mice during RSV infection will be performed. On the other hand, using anti-IL-17 or anti-IL-33 blocking antibodies during RSV infection will be performed in wild type mice. The effects of these treatment on the allergic airway responsiveness and inflammation will be evaluated. Our investigation will elucidate the role of γδT cells in RSV-induced allergic asthma development and asthma exacerbation.