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Vascularity in asthmatic airways: relation to inhaled steroid dose
1Department of Respiratory Medicine, The Alfred Hospital and Monash Medical School, Melbourne, Victoria 3181, Australia.
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 microg/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, p<0.05; 95% CI for the difference 48 to 286). There was no significant difference between asthmatic subjects on ICS and those not on ICS or control subjects in the number of vessels/mm2 (mean 421 (IQR 281-534)). However, patients who received >/=800 microg/day BDP tended to have a reduced number of vessels/mm2 compared with patients not on ICS and those receiving
Conclusion:
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.