Vascularity in asthmatic airways: relation to inhaled steroid dose

Abstract

BACKGROUND There is an increase in vascularity in the asthmatic airway. Although inhaled corticosteroids (ICS) are an effective anti-inflammatory treatment in asthma, there are few data on any effects on structural changes. METHODS Endobronchial biopsy specimens from seven asthmatic subjects not receiving ICS and 15 receiving 200–1500 μg/day beclomethasone dipropionate (BDP) were immunohistochemically stained with an anti-collagen type IV antibody to outline the endothelial basement membrane of the vessels. These were compared with biopsy tissue from 11 non-asthmatic controls (four atopic and seven non-atopic). RESULTS There was a significant increase in the density of vessels (number of vessels/mm² of lamina propria) in the asthmatic subjects not on ICS compared with non-asthmatic controls (mean 485 (interquartile range (IQR) 390–597) versus 329 (IQR 248–376) vessels/mm², p2 (mean 421 (IQR 281–534)). However, patients who received ⩾800 μg/day BDP tended to have a reduced number of vessels/mm² compared with patients not on ICS and those receiving ⩽500 μg/day BDP (mean 366 (IQR 153–608) versus 494 (IQR 391–583), p = 0.08; 95% CI for the difference –31 to 288). Similarly, there was an increase in the percentage of lamina propria occupied by vessels in asthmatic patients not on ICS compared with controls (mean 15.6% (IQR 13.1–18.0) versus 10.1% (IQR 8.4–13.3), p1) after bronchodilator (r = –0.38 for PD₂₀ methacholine and r = 0.49 for change in percentage FEV₁ after bronchodilator versus number of vessels/mm², pCONCLUSION These findings suggest that ICS, especially at higher doses, may reduce airway wall vascularity in asthmatic subjects but further longitudinal intervention studies are required to confirm this suggestion.