Smoking cessation and bronchial epithelial remodelling in COPD:a cross-sectional study

Background: Chronic Obstructive Pulmonary Disease ( COPD) is associated with bronchial epithelial changes, including squamous cell metaplasia and goblet cell hyperplasia. These features are partially attributed to activation of the epidermal growth factor receptor ( EGFR). Whereas smoking cessation reduces respiratory symptoms and lung function decline in COPD, inflammation persists. We determined epithelial proliferation and composition in bronchial biopsies from current and ex-smokers with COPD, and its relation to duration of smoking cessation.Methods: 114 COPD patients were studied cross-sectionally: 99 males/15 females, age 62 +/- 8 years, median 42 pack-years, no corticosteroids, current (n = 72) or ex-smokers ( n = 42, median cessation duration 3.5 years), postbronchodilator FEV 63 +/- 9% predicted. Squamous cell metaplasia (%), goblet cell ( PAS/Alcian Blue(+)) area (%), proliferating (Ki- 67(+)) cell numbers (/mm basement membrane), and EGFR expression (%) were measured in intact epithelium of bronchial biopsies.Results: Ex-smokers with COPD had significantly less epithelial squamous cell metaplasia, proliferating cell numbers, and a trend towards reduced goblet cell area than current smokers with COPD ( p = 0.025, p = 0.001, p = 0.081, respectively), but no significant difference in EGFR expression. Epithelial features were not different between short-term quitters (Conclusion: Ex-smokers with COPD had less bronchial epithelial remodelling than current smokers, which was only observed after long-term smoking cessation (>3.5 years).