Fig. 4
From: The pathology of small airways disease in COPD: historical aspects and future directions
The mechanism of small airways disease onset and progression in COPD. Cigarette smoking causes injury to the small airways. In response, aberrant repair processes result in excessive airway remodelling, mucous plugging and immune cell infiltration. These contribute to the onset and progression of small airways disease, which precedes emphysema. These changes may lead to increased COPD exacerbations and bacterial colonization, which, in turn, may contribute to small airways disease progression and emphysema development