CRTH2/PI3K通路介导嗜酸性粒细胞PGD2反应性增强——嗜酸性粒细胞性哮喘表型“易感性”新探索

Eosinophilic asthma is characterized by persistent eosinophilic airway inflammation. Our preliminary study first discovered that shapes of peripheral blood eosinophils from eosinophilic asthma patients changed more obviously in response to prostaglandin (PG) D2, compared with that in healthy controls. Based on the results, we would propose a hypothesis that the responses of eosinophils to chemoattractants and activators from the extracellular environment were increased in eosinophilic asthma phenotype, compared with that in healthy controls and non-eosinophilic asthma phenotype. The enhanced responses of eosinophils enable the cells to be easily accumulated to and activated in airways, leading to the development and persistence of airway eosinophilia, which may contribute to the “susceptibility” to eosinophilic phenotype in the certain group of patients. PGD2 works as one of the key stimulators for eosinophil recruitment and activity by specifically binding to its receptor, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) and then activating phosphatidylinositide 3-kinases (PI3Ks). We will start the current study from the observations on eosinophil migration and activation induced by PGD2 between different asthma phenotypes and healthy controls, and expect increased cells responses in eosinophilic asthma. Besides, we would discuss the relationships between eosinophil shape change response and airway inflammation and lung function. Finally, we will discover the underlying mechanism of the response discrepancies by studying CRTH2/PI3K pathway. This study is designed to explore the “susceptibility” to eosinophilic asthma phenotype and aims to provide new insights for pathogenesis research and therapeutic strategy for this disease.

嗜酸性粒细胞型哮喘（EA）以持续存在的嗜酸性粒细胞性气道炎症为特征。我们的前期研究首次发现，EA患者外周血嗜酸性粒细胞（EOs）对前列腺素（PG）D2诱导细胞形态改变的刺激作用反应性增强。由此，我们猜想EA患者外周血EOs对趋化／活化因子反应性增强，更容易发生气道迁移和活化，介导嗜酸性粒细胞性气道炎症的发生和发展，并提出EOs反应性增强可能导致EA表型形成的“易感性”。PGD2通过与细胞表面CRTH2受体特异性结合，激活磷酸肌醇3激酶（PI3Ks）家族，实现EOs的趋化和活化作用。因此，本项目拟以PGD2诱导的EOs迁移和活化为切入点，观察EA患者外周血EOs对PGD2刺激的反应性，探讨EOs反应性与气道炎症以及肺功能的相关性，并从CRTH2／PI3K通路着手探索细胞反应性增强的分子机制，揭示EA表型形成的“易感性”，为哮喘的机制研究和治疗提供新思路。

项目背景：嗜酸性粒细胞哮喘（EA/T2）以持续存在的气道EO增多为特征。PGD2能通过EO表面CRTH2受体及下游激活磷酸肌醇3激酶（PI3K）家族等信号通路促进EO趋化和活化，但不同哮喘表型外周血EO对PGD2的干预效应是否存在异质性尚不明确。.研究内容：纳入稳定期哮喘患者并根据诱导痰/外周血EO比例将其分为NEA(NT2)表型和EA(T2)表型，以健康受试者作为对照。采集受试者人口学信息及临床特征信息。分离提取受试者外周血EO，检测PGD2诱导的细胞形态改变、细胞趋化、CRTH2/CD11b表达水平、嗜酸性粒细胞炎症因子，包括ECP、EDN和ROS表达水平以及PI3K等信号通路蛋白表达水平。.结果及数据：PGD2/CRTH2信号能够诱导外周血EO形态改变、趋化（P＜0.0001）以及炎症因子产生和释放；PGD2能够强烈诱导外周血EO增殖（P=0.0238）、CRTH2蛋白内化（P=0.0411）以及mRNA表达升高（P<0.0001）；EA组外周血EO对PGD2/CRTH2信号诱导的细胞效应反应性增强，表现为PGD2干预后外周血EO比例（P=0.0410），CRTH2总蛋白（P=0.0060）及mRNA表达水平（P=0.0189）、细胞形态改变比例（P＜0.0001）、细胞趋化比例（P=0.0019）以及炎症因子产生水平显著升高，但CD11b 蛋白（P=0.8562）及mRNA（P=0.1466）表达水平无统计学差异；此外，PGD2干预后EA组外周血EO信号通路蛋白PI3K、AKT、ERK、p38 MAPK活化水平亦显著升高。.科学意义：研究提示EA表型患者外周血EO对PGD2诱导的细胞效应反应性增强，与CRTH2/PI3K信号通路上调有关，提示CRTH2/PI3K信号通路活化可能介导EA表型“易感性”，从全新角度揭示了哮喘异质性形成的分子机制，为EA哮喘表型的精准化治疗提供全新的治疗靶点。