GLP-1经GLP-1R/cAMP/PKA通路负向调节嗜酸性粒细胞活化抑制过敏性哮喘的作用及机制研究

The incidence of allergic asthma has risen dramatically in recent years, and the pathogenesis of allergic asthma mainly depends on Th2 cellular immune. Moreover, eosinophils play a key role in generation and activation of Th2 cells. It has been reported that glucagon-like peptide-1 (GLP-1) analogues can improve isolated human bronchial hyperreactivity induced by high concentration of glucose. In the early stage, we found that exendin-4, a GLP-1 analogue, can improve the pathological structure of lung tissue of mice, reduce Th2- type cytokines and down-regulate MHC- II and costimulatory molecules expression in eosinophil with a mouse model of allergic asthma induced by house dust mite. Activation of cAMP/PKA pathway can inhibit eosinophil activation and promote it apoptosis. Moreover, activation of GLP-1R/cAMP/PKA pathway can promote amylase secretion. We assume that GLP-1 analogue can specifically bind to GLP-1R in eosinophils, and inhibit eosinophil activation by activating GLP-1R/cAMP/PKA pathway, and further negatively regulate Th2 cell differentiation and activation, thereby, resulting in inhibiting allergic asthma. We aim to explore the inhibited effect and the mechanism of GLP-1 analogue on allergic asthma. It will provide new ideas and strategies for the prevention and treatment of allergic asthma by clarifying the problems above.

过敏性哮喘近年发病率急剧上升，其发病机制主要以Th2细胞免疫为主，嗜酸性粒细胞对Th2细胞的生成、活化等起重要作用。研究表明胰高血糖素样肽-1（GLP-1）类似物可改善高糖诱导的离体人细支气管高反应性，我们前期发现GLP-1类似物Exendin-4可以改善过敏性哮喘小鼠肺组织病理结构，降低Th2型细胞因子水平，下调嗜酸性粒细胞MHC-Ⅱ及表面共刺激分子的表达。激活cAMP/PKA通路可抑制嗜酸性粒细胞活化，并促进其凋亡；激活GLP-1R/cAMP/PKA通路可促进淀粉酶分泌。我们设想：GLP-1类似物可能特异性地结合于嗜酸性粒细胞上的GLP-1R，激活GLP-1R/cAMP/PKA通路抑制嗜酸性粒细胞活化，从而负向调节Th2细胞分化及活化，进而抑制过敏性哮喘。本课题拟明确GLP-1类似物抑制过敏性哮喘的作用及具体机制。阐明上述问题将为防治过敏性哮喘提供新的思路及策略。

过敏性哮喘主要是以Th2介导的气道慢性炎症性疾病，嗜酸性粒细胞对Th2细胞分化起重要作用。GLP-1可改善高糖诱导的离体人细支气管高反应性，由此GLP-1类似物可能通过结合于嗜酸性粒细胞上的GLP-1R，从而负向调节Th2细胞分化，进而抑制过敏性哮喘。.本研究分为三个部分：<1> 利用HDM建立小鼠过敏性哮喘模型，给予GLP-1R激动剂干预，证实了GLP-1对小鼠过敏性哮喘的抑制作用；HDM诱导的小鼠过敏性哮喘模型中，CD4+/CD8+IL-4+细胞均明显增高；GLP-1干预组，小鼠支气管肺门淋巴结中CD4+/CD8+IL-4+细胞比例降低，而CD4+/CD8+IFN-γ+细胞比例升高，调整了Th1/Th2细胞平衡；哮喘小鼠BALF中嗜酸性粒细胞CD101表达增强，即促炎性嗜酸性粒细胞增多，而GLP-1干预的哮喘小鼠BALF中嗜酸性粒细胞CD101表达较对模型组减低，进一步揭示GLP-1抑制小鼠过敏性哮喘的作用机制，Th2细胞增多很可能与促炎性嗜酸性粒细胞有关。 .<2> 探讨GLP-1对人嗜酸性粒细胞的影响，发现嗜酸性粒细胞表面共刺激分子及MHC-II高表达的这部分细胞其GLP-1R水平显著升高。同时利拉鲁肽促进表面共刺激分子CD80、CD86及MHC-II表达，而抑制活化分子CD69和CD11b表达。因此为GLP-1抑制嗜酸性粒细胞活化而进一步负向调节嗜酸性粒细胞诱导T细胞向Th2细胞分化提供支持。.<3> GLP-1R激动剂利拉鲁肽在5例过敏性哮喘合并T2DM患者利拉鲁肽治疗过程中， 初步证实GLP-1R激动剂利拉鲁肽对人过敏性哮喘的有改善作用，由此虽然样本量少，但为 GLP-1将在临床上应用于过敏性哮喘治疗的可能性大大增加。.通过上述探讨，明确GLP-1R激动剂可以负向调节嗜酸性粒细胞活化，抑制Th2细胞分化，减轻过敏性哮喘；同时过对敏性哮喘合并T2DM患者有一定治疗作用，因此，GLP-1R激动剂对过敏性哮喘有重要改善，为将来GLP-1R激动剂应用于临床治疗过敏性哮喘提供支持。