Corticosteroid treatment selectively decreases mast cells in the smooth muscle and epithelium of asthmatic bronchi
- All authors are associated with the Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
Edited by: Michael Wechsler
Anna James, Experimental Asthma and Allergy Research, Institute of Environmental Medicine, P.O. Box 287, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Mast cells are important in the pathophysiology of airway inflammation and evidence suggests their sub-localisation within the airway is altered in asthma. Little is known about the effect of corticosteroids on mast cell localisation within the bronchi.
We therefore performed an immunohistochemical analysis of mast cell numbers within the smooth muscle, epithelium and submucosa of healthy subjects (n = 10) and well-characterised asthmatic patients, using either β2-agonists alone (n = 10) or β2-agonists and inhaled corticosteroids (n = 10).
Patients using inhaled corticosteroids displayed significantly lower numbers of mast cells within their epithelium and smooth muscle compared to those not treated with inhaled corticosteroids. Submucosal mast cells were not affected by corticosteroid treatment. Numbers of smooth muscle mast cells correlated with bronchial responsiveness and epithelial mast cells with exhaled NO.
We demonstrate that glucocorticosteroids differentially affect mast cell numbers within specific airway sub-locations highlighting the importance of mast cell and smooth muscle/epithelial interactions in asthma pathogenesis.