Comparison of airway wall remodeling in asthma and COPD: biopsy findings

Bronchial remodeling is currently known to affect not only patients with asthma, but also COPD patients. Some studies have demonstrated that basement membrane thickening and destruction of the bronchial epithelium are also found in COPD. The aim of the study was to compare the basement membrane thickness (BMT) and epithelial damage in biopsy specimens from patients with asthma and COPD.

The study was performed in 20 subjects with asthma and 12 subjects with COPD, who had not been treated with corticosteroids for at least 3 months before study enrollment. Subjects' characteristics were based on the results of clinical assessment, allergic skin-prick tests, lung function testing, and methacholine bronchial challenge. All subjects underwent bronchoscopy with forceps biopsies of bronchial mucosa. Light-microscope and semi-automatic software were used to measure BMT in hematoxylin-eosin stained sections. Total (denudation) and partial epithelial damage were assessed independently by 2 pathologists.

The mean BMT in subjects with asthma was 12.54 ± 2.8 μm, and only 7.81 ± 2.0 μm in COPD patients (P < .001). Overall percentage of the basement membrane length lined with damaged epithelium was 45 ± 20% in the asthma group and 47 ± 22% in the COPD group (difference not significant). Complete and partial epithelial damage did not differ between the groups.

BMT might be a histopathological parameter helpful in distinguishing asthma and COPD patients, whereas the extent and pattern of epithelial damage is not.