神经肽CGRP活化ILC2s在臭氧诱发过敏性哮喘中的作用和机制研究

Aggravated by increased industrialization, urbanization, and global warming, health risks posed by urban ozone pollution in China continue to rise rapidly. As a non-allergen, ozone is a known risk factor for higher incidences of asthma and asthma-related deaths; however, mechanisms of which remain elusive. Our previous study has shown that ozone exposure activates respiratory sensory neurons, leading to excessive expression of neuropeptide calcitonin gene-related peptide (CGRP) in mouse lung. Recent studies have shown that nerve fibers in lung tissues are located at the same site as type II congenital lymphocytes (ILC2s), therefore neuropeptides may trigger ILC2s cells and activate inflammatory response. Based on these observations, we hypothesize that upon binding to the receptor, ozone induced CGRP will cause the activation of GATA3 then activate ILC2s cells, enhance inflammatory responses, and in turn induce or aggravate asthma. To validate our hypothesis, we will use knockout mice and cell models, along with flow cytometry and cell coculture experiments to explore the nociceptive pathways and toxicological effects of CGRP-activated ILC2s cells. We aim validate the roles of neuro-immune pathways in the occurrence of ozone-induced allergic asthma, and in the process, discover novel and promising targets suitable for asthma-related preventative and therapeutic strategies.

在工业化、城市化和全球变暖三重压力下，我国城市臭氧污染风险不断提高。作为非过敏原的臭氧是增加哮喘发病率和死亡率的关键风险因素，但其作用机制仍未明了。申请人前期研究发现，臭氧暴露可激活呼吸系统感觉神经元，引起肺组织神经肽降钙素基因相关肽（CGRP）过量表达。最近研究表明，肺组织中神经纤维与Ⅱ型先天淋巴细胞（ILC2s）位于相同位点，神经肽可能活化ILC2s细胞扩大炎症反应。据此，本项目首次提出，臭氧暴露可引起肺组织神经肽CGRP过量表达，与受体结合后通过激活GATA3活化ILC2s，扩大炎症反应，诱发或加重哮喘。本项目拟在基因敲除小鼠和细胞模型，用流式细胞分选、细胞共培养等技术，探究CGRP激活 ILC2s细胞的伤害性通路以及毒理学效应。以期证明神经-免疫途径在臭氧诱发过敏性哮喘发生中的作用，为早期识别臭氧暴露敏感人群和制定臭氧防治措施提供新思路。

在工业化、城市化和全球变暖三重压力下，我国城市臭氧污染风险不断提高，已取代PM2.5成为城市区域首要空气污染物。流行病学研究表明，包括臭氧在内的强氧化性空气污染物是增加过敏性哮喘发病率和死亡率的关键风险因素；但是，目前针对环境污染物诱发哮喘的防治主要是“对症治疗”控制过敏性炎症反应，但并未“对因治疗”从诱发炎症的始动因素中找到关键靶点。本项目研究发现，臭氧联合过敏原暴露通过瞬时感受器电位香草酸受体1（TRPV1）激活呼吸系统感觉神经元，增加肺组织降钙素基因相关肽（CGRP）和IL-33过量表达和释放，导致血清免疫球蛋白E（IgE）异常升高，并促进ILC2s及其特征性细胞因子IL-5、IL-13和转录因子GATA3的分泌，活化免疫效应细胞（肥大细胞、嗜酸性粒细胞等），形成神经-免疫正反馈恶性循环，进而加重气道粘液增生和气道高反应性，恶化过敏性哮喘样症状。同时，本研究也进一步揭示臭氧通过Nrf2信号通路激活TRPV1参与呼吸系统神经-免疫相互作用的调控机制。此外，本研究还拓展性的发现，与臭氧单独暴露相比，臭氧联合PM2.5暴露或者臭氧联合高温暴露均可通过TRPV1介导的神经-免疫相互作用加重模型小鼠过敏性哮喘样症状。综上，通过本项目的研究，揭示了“神经-神经递质-免疫细胞”为主体的神经-免疫互作机制在臭氧等大气污染物促发过敏性哮喘中的作用，为其防治提供了新策略和精确靶点。