Background: Increased vascularity in airway mucosa is a distinctive feature of airway remodelling in asthma. While corticosteroids have proved most effective in modifying airway inflammation, the effect of inhaled corticosteroids on increased airway mucosal vascularity in asthmatics has been little studied.
Objective: We examined the effect of inhaled corticosteroid on airway vascularity in bronchial biopsy specimens taken from asthmatic patients.
Subjects and methods: We studied bronchial biopsies from 28 asthmatic patients before and after treatment with inhaled beclomethasone dipropionate (BDP) 800 microg/daily, or placebo, for 6 months in a double-blind manner. Biopsy specimens were evaluated for number of vessels and percentage of area occupied by vessels, using computerized image analysis after staining for type IV collagen in vessel walls. Specimens were also examined for extent of collagen III in the subepithelial basement membrane. In addition, we compared asthmatic specimens with biopsy specimens taken from non-asthmatic control subjects.
Results: There was a significant increase in number of vessels (P < 0.01) and percent vascularity (P < 0.001) in the submucosa of asthmatic patients compared with control subjects. After 6 months of treatment, we observed significant improvements in forced expiratory volume in 1 s (FEV1), FEV1% and airway responsiveness (P < 0.05, each) in the BDP treatment group compared with the placebo group. This was accompanied by significant decreases in both vessel number and percent vascularity in the airways of BDP-treated patients (P < 0.05, each). We also observed a significant correlation between change in percent vascularity and change in collagen III thickness in the BDP-treated patients (rs = 0.90, P < 0.001). Furthermore, the change in percent vascularity was inversely correlated with both FEV1 (rs = -0.49, P < 0.05) and airway responsiveness (rs = -0.36, P < 0.05).
Conclusion: These findings suggest that inhaled corticosteroid treatment of asthma reduced airway wall vascularity during airway remodelling.