Epithelial cell proliferation contributes to airway remodeling in severe asthma.

Rationale: Despite long-term therapy with corticosteroids, patients with severe asthma develop irreversible airway obstruction.

Objectives: To evaluate if there are structural and functional differences in the airway epithelium in severe asthma associated with airway remodeling.

Methods: In bronchial biopsies from 21 normal subjects, 11 subjects with chronic bronchitis, 9 subjects with mild asthma, and 31 subjects with severe asthma, we evaluated epithelial cell morphology: epithelial thickness, lamina reticularis (LR) thickness, and epithelial desquamation.