Persistence of Smoking-induced Dysregulation of Small Airway Epithelium miRNA Expression Despite Smoking Cessation. Homo sapiens

Rationale: Even after quitting smoking, the risk of the development of chronic obstructive pulmonary disease (COPD) and lung cancer remains significantly higher compared to never-smokers. Objectives: Based on the knowledge that COPD and most lung cancers start in the small airway epithelium (SAE), we hypothesized that smoking modulates miRNA expression in the SAE linked to the pathogenesis of smoking-induced airway disease, and that some of these changes persist after smoking cessation. Methods: SAE was collected from 10th to 12th order bronchi using fiberoptic bronchoscopy. Affymetrix miRNA 2.0 arrays were used to assess miRNA expression in the SAE from 10 healthy never-smokers and 10 healthy smokers, before and after they quit for 3 months. Smoking status was determined by urine nicotine and cotinine measurement. Results: There were significant differences in the expression of 34 miRNAs between healthy smokers and healthy never-smokers (p1.5), with functions associated with lung development, airway epithelium differentiation, inflammation and cancer. After quitting smoking for 3 months, 12 out of the 34 miRNAs did not return to normal levels, with Wnt/β-catenin signaling pathway the top enriched pathway of the target genes of the persistent deregulated miRNAs. Conclusions: In the context that many of these persistent smoking-dependent miRNAs are associated with differentiation, inflammation diseases or lung cancer, it is likely that persistent smoking-related changes in small airway epithelium miRNAs play a role in the subsequent development of these disorders. Overall design: MicroRNA profiling identified 34 miRNAs up-regulated by cigarette smoking in human small airway epithelium. Even after quitting smoking for 3 months, 12 miRNAs didn’t return to normal level.

研究背景：即便停止吸烟，慢性阻塞性肺疾病（chronic obstructive pulmonary disease, COPD）与肺癌的发病风险仍显著高于从未吸烟者。
研究目标：鉴于COPD与多数肺癌均起源于小气道上皮（small airway epithelium, SAE），本研究提出如下假说：吸烟可调控SAE中与吸烟诱导性气道疾病发病机制相关的microRNA (miRNA)表达，且部分此类表达改变会在戒烟后持续存在。
研究方法：通过纤维支气管镜（fiberoptic bronchoscopy）从第10至12级支气管采集SAE样本。采用Affymetrix miRNA 2.0芯片检测10名健康从未吸烟者与10名健康吸烟者的SAE miRNA表达水平，检测分别在戒烟前及戒烟3个月后完成。吸烟状态通过尿液尼古丁与可替宁检测予以确认。
研究结果：健康吸烟者与健康从未吸烟者的SAE中，共有34种miRNA的表达存在显著差异（P<0.05且表达倍数变化≥1.5），这些miRNA的功能涉及肺发育、气道上皮分化、炎症反应与癌症发生。戒烟3个月后，34种差异表达miRNA中有12种未能恢复至正常水平；对持续失调miRNA的靶基因进行富集分析显示，Wnt/β-连环蛋白信号通路（Wnt/β-catenin signaling pathway）为最显著富集的通路。
研究结论：鉴于此类持续存在的吸烟相关性miRNA大多与细胞分化、炎症性疾病或肺癌相关，小气道上皮中持续存在的吸烟相关miRNA改变，可能在上述疾病的后续发生发展中发挥重要作用。
整体实验设计：通过microRNA表达谱分析，鉴定出人类小气道上皮中受香烟吸烟调控的34种miRNA。即便戒烟3个月后，仍有12种miRNA未能恢复至正常水平。