IL-25 receptor expression on basophil membrane is related to phenotype and severity of asthma

Background: In patients with asthma, basophils, together with mast cells and eosinophils, are the effector cells most often associated with airway inflammation. Basophils can have an important role in promoting Th2 inflammation, as these cells may be activated directly by tissue cytokines (IL25, IL33 and TSLP) released by epithelial cells in response to damage signals from allergens, bacteria, virus or pollutants. We investigated whether the expressions of IL25, IL33 and TSLP receptors (R) on basophil membrane before and after stimuli, are associated with the severity of asthma. Methods: Twenty-two patients with asthma (13 mild/moderate and 9 severe), 9 (36%) treated with oral glucocorticoids, 6 (24%) with early onset, 10 (40%) atopic, 10 (40%) with eosinophilic asthma were enrolled. Basophils membrane expression of IL25 R, TSLP R and IL33 R was analyzed before and after stimulation with IgE, fMLP, LPS, LTA-SA. Results: Before stimulation, no significant difference in basophil R expressions by asthma phenotype and severity was found. The most significant basophil response was obtained with IgE stimulation on IL-25 R. The increase in IL-25 R after IgE (D-IL25 R) was significantly greater in patients with eosinophilic asthma (p=0.04) and with early onset asthma (p=0.015) and was significantly lower in those with severe asthma (p=0.01). D-IL25 R was closely directly related to the blood eosinophils count (r=0.453,p=0.034) . Conclusions: Basophils Th2 signature, as expressed by IL25-R modulation, seems to be related to eosinophilic and early onset asthma . The blunted increase of IL25-R expression in severe asthma deserves further investigation.