EFFECT OF INHALED BECLOMETHASONE DIPROPIONATE ON EXPRESSION OF PROINFLAMMATORY CYTOKINES AND ACTIVATED EOSINOPHILS IN THE BRONCHIAL EPITHELIUM OF PATIENTS WITH MILD ASTHMA

Increasing evidence suggests that cytokines play a role in airway infl ammation by attracting and activating inflammatory cells. This may lea d to epithelial cell damage and airway hyperresponsiveness. Bronchial provocative concentration of histamine causing a 20% fall in forced ex piratory volume in 1 second was measured in patients with mild asthma, and bronchial biopsy specimens were stained for granulocyte-macrophag e colony-stimulating factor (GM-CSF, interleukin (IL)-8, and activated eosinophils (EG2) in the bronchial epithelium. The effect of inhaled beclomethasone dipropionate was also assessed in a placebo-controlled double-blind manner. There was a correlation between GM-CSF expression and EG2-staining cells (r = 0.484 p < 0.05) in the epithelium. Provoc ative concentration of histamine causing a 20% fall in forced expirato ry volume in 1 second was correlated with GM-CSF expression (r = -0.46 2, p < 0.05). Treatment with inhaled beclomethasone dipropionate 500 m u g twice a day led to a significant decrease in both the expression o f GM-CSF (p < 0.01) and IL-8 (p < 0.02) and the number of EG2-staining cells (p < 0.01) in the epithelium. The changes in GM-CSF (r = 0.798, p < 0.01) and 11-8 (r = 0.653, p < 0.02) expression were correlated w ith the changes in EG2-staining cells after treatment. These results s uggest that GM-CSF may influence eosinophil activation in the epitheli um in vivo and participate in the etiology of bronchial hyperresponsiv eness in mild asthma. Also, beclomethasone dipropionate may inhibit eo sinophil activation partly by downregulating the expression of GM-CSF and IL-8 in the bronchial epithelium.