腺苷酸环化酶9在支气管哮喘气道平滑肌重建中的作用及其机制研究

Usually, Asthma is manifested as reversible airflow limitation; Once there is airway remodeling, it will be manifested as irreversible airflow limitation which makes patients' living quality worsen. Usually, airway remodeling develops gradually. But, in clinic, some asthma patients are diagnosed as irreversible airflow limitation younger and earlier than usual, the underlying mechanism needs to be explored. In recent years, we recruited and observed dynamically some asthma patients who are less than 40 year old, and asthma duration less than 2 years, recently these patients were diagnosed as asthma with airway remodeling or simple asthma by lung function test et al, and screened several SNPs of asthma related genes, we found there is significant difference of adenylate cyclase 9 gene (ADCY9) SNP between the DNA samples from asthma patients with airway remodeling and simple asthma. Meanwhile, we found ADCY9 protein expression down-regulated in the thickened bronchial smooth muscle of mouse chronic asthma model, asthma sera or cytokines induced ADCY9 protein and mRNA expression down-regulation, and intracellular cAMP level decline as well. Consequently, we hypothesize that ADCY9 gene expression down-regulation and gene polymorphism maybe related with asthma airway remodeling. Therefore, we plan to study further at cell, animal and clinical levels. The results of this project will find biological marker for the prediction of airway remodeling earlier, it can also find new target for airway remodeling treatment at early stage.

哮喘一般表现为可逆性气流受限；一旦发生气道重建，则出现不可逆性气流受限，患者的生活质量必将恶化。气道重建往往是慢性过程，但是在临床工作中发现部分年龄轻、早期病程的哮喘病人出现了不可逆的气流受限，其发生原因非常值得探讨。近几年，我们募集小于40岁、哮喘病程低于2年的患者，经肺功能测定及动态观察诊断为哮喘伴气道重建或单纯哮喘，并筛查多个哮喘相关基因的SNPs，发现腺苷酸环化酶9(ADCY9)的SNP在两种哮喘病人之间存在明显差异。而且，慢性哮喘动物模型气道重建时平滑肌层ADCY9蛋白表达下调，哮喘病人血清或细胞因子长时间处理支气管平滑肌细胞均可引起ADCY9表达下调和cAMP的减少。因此，我们推测ADCY9表达量的变化和基因多态性可能与哮喘的气道重建相关。为此，我们拟从细胞、动物及临床等方面展开进一步的研究，研究结果可为预测哮喘早期发生气道重建提供可能的生物学标志，为早期防治气道重建提供靶点。

哮喘一旦发生气道重建，则出现不可逆性气流受限，患者的生活质量必将恶化。我们预实验发现哮喘早期伴气道重建与单纯哮喘病人腺苷酸环化酶9(ADCY9)的SNP存在明显差异，慢性哮喘动物模型气道重建时平滑肌层ADCY9蛋白表达下调，我们提出“哮喘慢性气道炎症导致ADCY9表达下调，诱导哮喘气道重建；部分哮喘病人ADCY9基因单核苷酸多态性（SNP）差异，导致ADCY9蛋白功能下降，从而早期发生气道重建”的假说。我们的研究目标是：明确哮喘慢性炎症引起的ADCY9表达改变与气道重建的关系；明确ADCY9基因位点的差异性与哮喘早期发生气道重建的关系，以及作为预测哮喘患者发生早期气道重建的生物学标志的可能性。主要研究结果为：1.哮喘病人中发现ADCY9 rs2230739 基因多态性；2. 明确了哮喘病人肺功能和支气管舒张试验与ADCY9基因位点差异的相关性；3. ADCY9基因rs2230739位点的突变可以影响支气管平滑肌重建；4.哮喘炎症可导致ADCY9表达下调以及气道平滑肌重建；5.过表达ADCY9对逆转哮喘气道炎症引起的气道平滑肌重建有作用；6.敲减ADCY9可直接导致气道平滑肌重建。我们的结果证实，ADCY9 rs2230739 基因多态性以及表达量的下调可影响ADCY9的活性，进而导致哮喘气道平滑肌重建。