Relationship between Airway Basement Membrane Thickness and Lung Function Tests in Patients with Asthma

Introduction: Airway remodeling is a characteristic feature of asthma. It is believed that airway remodeling affects lung function and bronchial hyper-responsiveness. Therefore, the relationship between remodeling and lung function is still a matter of extensive research. However, the results of many studies are inconsistent. The aim of the study was to assess the relationship between lung function parameters and basement membrane (BM) thickness in patients with asthma. Material and Methods: Twenty asthma patients were chosen for the study (ten male, ten female, mean age 37 ± 15 yrs). Ten were newly diagnosed, steroid-naive patients and the other ten were patients known to have asthma who had not been treated with steroids for at least three months. The study group was selected based on the results of: clinical assessment, allergic skin-prick tests, lung function testing and bronchial challenge with methacholine. Nine (45%) patients had chronic mild, nine (45%) had moderate and two (10%) had intermittent asthma. Mean FEV₁% pred. was 83 ± 18, mean FEV₁%VC 69 ± 9, mean FVC% pred. 101 ± 14. All patients underwent research fiberoptic bronchoscopy with BAL and bronchial mucosal biopsies. Light-microscopic measurements of BM thickness were performed in hematoxylin-eosin stained slides of bronchial wall specimens with semi-automatic software analysis MultiScan Base 08.98. Results: Mean BM thickness was 12.8 ± 2.8 μm (range: 8.5–20.7 μm). No significant correlations between BM thickness and FEV₁% pred., FEV₁%VC, FVC% pred., RV% pred., TLC% pred., Raw (pre- and post-bronchodilator) and PC₂₀ were observed. Conclusions: In our group of asthma patients, mean BM was significantly thickened. No relationship between BM thickness and lung function tests, including hyper-responsiveness, was found.