MedWire News: Ex-smokers with chronic obstructive pulmonary disease (COPD) show less bronchial epithelial remodeling than current smokers with the lung disorder, study findings reveal.
The change in ex-smokers becomes more pronounced with increasing duration of smoking cessation, and significant 3.5 years after quitting.
COPD is associated with bronchial epithelial changes, including squamous cell metaplasia and goblet cell hyperplasia, which are partly attributed to activation of epithelial epidermal growth factor receptor (EGFR) expression.
Whereas smoking cessation is known to improve respiratory symptoms and slow lung function decline in COPD, so far no studies have looked at its potential to change epithelial features.
Thérèse Lapperre (Leiden University Medical Center, The Netherlands) and team therefore studied bronchial biopsies of 114 patients with moderate-to-severe COPD, 72 of whom were current smokers and 42 of whom were ex-smokers who had given up a median of 3.5 years earlier.
Using immunohistochemistry, they found that the ex-smokers had significantly less epithelial squamous cell metaplasia, proliferating cell numbers, and a trend towards reduced goblet cell area than the current smokers, but similar levels of EGFR expression.
There were no differences in any of the epithelial features between current smokers and those who quit less than 3.5 years ago. In contrast, ex-smokers who quit more than 3.5 years ago had significantly fewer proliferating cells (2.8% vs 18.6%) and less squamous cell metaplasia (19.0% vs 45.7%) than current smokers, and less goblet cell area than both current smokers and short-term quitters (7.9% vs 14.4% and 13.5%, respectively).
Furthermore, there was a significant inverse relationship between duration of smoking cessation and proliferating epithelial cell numbers, squamous cell metaplasia, and goblet cell area.
"Ex-smokers have less bronchial epithelial mucin stores, proliferating cells, and squamous cell metaplasia than current smokers," the authors summarize in the online journal Respiratory Research.
"This suggests that the clinical benefits of smoking cessation in COPD patients may be in part attributable to a restoration of epithelial homeostasis."
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