哮喘小鼠嗜铬细胞nAchR亚型再分布对肾上腺素释放的影响及其机制

We have proposed that the insufficiency of epinephrine level under the condition of asthma was due to neuronal conversion of adrenal medulla chromaffin cells induced by elevated nerve growth factor (NGF) level. The release of epinephrine is decided by the intracellular calcium concentration ([Ca2+]i) in chromaffin cells in a concentration-dependent manner. And the degree of [Ca2+]i activation is controlled by the different subtypes of nicotinic acetylcholine receptors (nAChR).α7nAChR has the highest calcium permeability. Researches have demonstrated that NGF could upregulate the expression of α7nAChR in nerve cells, which tend to activate calcium channel and thereby make [Ca2+]i increased. Basing on above observations, we hypothesized that the release obstacle of epinephrine were presence in asthma because of imbalance of [Ca2+]i induced by the redistribution of nAChR subtypes, specifically, the increase of nAChR subtypes like α7nAChR could promote [Ca2+]i. Accordingly, this study intends to figure out that whether the redistribution of nAChR subtypes excites in the pathogenesis of asthma and the effect of nAChR subtypes redistribution on the regulation of [Ca2+]i as well as the release of epinephrine in chromaffin cells.

我们发现哮喘时肾上腺素分泌不足是因神经生长因子(nerve growth factor, NGF)增高使肾上腺髓质嗜铬细胞向神经元转变。肾上腺素释放取决于嗜铬细胞内钙离子浓度(intracellular calcium concentration, [Ca2+]i)并呈浓度依赖性。而[Ca2+]i由烟碱样乙酰胆碱受体(nicotinic acetylcholine receptor，nAChR)激活钙通道来调控，其激活程度与nAChR的亚型构成有关，α7nAChR对钙离子通透性最高。NGF可上调α7nAChR表达而使[Ca2+]i升高。我们推测哮喘中嗜铬细胞可能出现nAChR亚型再分布(α7nAChR等亚型增多)引起[Ca2+]i失衡并使肾上腺素释放功能障碍。本项目拟研究：哮喘中嗜铬细胞是否有nAChR亚型再分布；nAChR亚型再分布对[Ca2+]i调控及其对嗜铬细胞释放肾上腺素功能的影响

根据本课题组提出的哮喘发病过程中烟碱型乙酰胆碱受体亚型存在再分布.并这一现象对哮喘的发病起着重要的新假说: 哮喘发病过程中是否存在烟碱型 乙酰胆碱受体亚型的再分布成为实验的关键环节。本课题组先以 C57BL 小鼠为研究对象。分别哮喘造模并予以 NGF 抗体、methyllycaconitine、PNU-282987 干预。.随后在前期实验的基础上。本课题组针对研究对象进行哮喘造模后分别对气 道高反应性，血清 OVA 特异性 IgE，血清肾上腺素水平进行测定。然后对小鼠肾上腺素嗜铬细胞(AMCCs)分离纯化。并观察其对肾上腺素嗜铬细胞释放肾上腺 素的影响。.在本项目本课题组围绕乙酰胆碱受体亚型进行了一系列研究，并验证了前期 提出的哮喘发病过程中烟碱型乙酰胆碱受体亚型存在再分布并且对哮喘的发病 起着重要的新假说。本课题组接着研究了乙酰胆碱受体亚型和细胞外诱捕网之间 紧密的关系和重要的调节作用。实验以 C57BL 小鼠为研究对象，予以 PNU-282987 干预小鼠，通过减少细胞外诱捕网的形成，缓解小鼠哮喘症状。.最后本课题组成功验证了哮喘小鼠发病过程中存在细胞外诱捕网的形成，并且细胞外诱捕网能够加重哮喘症状，我们发现细胞外诱捕网能影响 Th17 的分化， 促进 IL17 的分泌。进一步研究发现细胞外诱捕网的并非直接调控 Th 细胞的平衡，而是细胞外诱捕网可以促进激活巨噬细胞的成熟。针对细胞外诱捕网的特异性成分染色质和瓜氨酸化组蛋白的治疗能有效改善哮喘。