MITE-ANTIGEN AVOIDANCE CAN REDUCE BRONCHIAL EPITHELIAL SHEDDING IN ALLERGIC ASTHMATIC-CHILDREN

Background Asthma is characterized by bronchial hyperresponsiveness (B HR), bronchial mucosa inflammation and airway epithelial damage. Objec tive This study was designed to evaluate the effect of mite avoidance on bronchial epithelial shedding in asthmatic children sensitized to D ermatophagoides. Methods The percentages of airway epithelial cells an d eosinophil have been counted in samples obtained by hypertonic salin e-induced sputum before and after a period of antigen avoidance in an Alpine environment (1756 m). The degree of bronchial hyperresponsivene ss to methacholine was also evaluated. Results After avoidance the med ian (lower, Q1, and upper, Q3, quartile) percentage of epithelial cell s in the sputum decreased significantly from 3.50 [0.50;6.98] to 0 [0; 0.5] (P=0.012) and eosinophil percentage decreased from 1 [0;5.25] to 0 [0,1.5] (P<0.05). Median (Q1,Q3) PC20 increased significantly from 2 .75 [1.53;7.5] to 3.25 [1.65;15.25] mg/mL (P=0.038). After 3 weeks of re-exposure to mite the epithelial median (Q1,Q3) percentage raised to 3.90 [1.5;6] (P = 0.027), eosinophils to 1.5 [0;3.00] (NS) and PC20 w as 5.25 [1.68;14.50] (NS). Conclusion Exposure to house dust mite anti gen can induce airway epithelial shedding even in subjects with low eo sinophil airway infiltration, thus supporting the idea that epithelial damage in asthmatics sensitized to Dermatophagoides may be due to a p roteolytic activity of the mite major antigens.