Basophils Membrane Expression of Epithelial Cytokines Receptors in Eosinophilic and Non Eosinophilic Asthma

Basophils are effector cells most often associated with airway inflammation in patients with asthma and can have an important role in the initiation of Th2 inflammation, as these cells may be activated directly by tissue cytokines (IL-25, IL-33 and TSLP) released by epithelial cells in response to damage signals from allergens, bacterials, virus or pollutants. We investigated whether IL-25, IL-33 and TSLP receptors expression levels on basophil membrane are associated with asthma phenotype. 24 patients with asthma (12 eosinophilic, 12 non eosinophilic) have been enrolled in the study. Basophils membrane expression of IL25 R, TSLP R and IL33 R was analyzed before and after IgE, fMLP, LPS, LTA-SA (Lipoteicoic Acid from S. Aureus) stimulation and correlated with FEV1 of each patient. Following LPS stimulation a significant increase in IL25 R was observed in eosinophilic (p=0.001) but not in non eosinophilic asthma. IgE stimulation significantly increased IL25 R expression on basophils membrane, in both eosinophilic and non eosinophilic asthma (p= 0.001 and p= 0.001, respectevely), the percentual increase being greater in eosinophilic compared to non-eosinophilic asthma (p=0.007). IL33 R and TSLP R expression on unstimulated basophils were inversely correlated with FEV1 in eosinophilic asthma ( r= -0.45, p = 0.04 and r = -0.70, p = 0.01, respectively). In conclusion, in eosinophilc asthma, airway obstruction is inversely correlated to the membrane expression of TSLP and IL33 receptors on basophils. Whether the expression of epithelial cytokines on basophils membrane may be used as biomarker of severe eosinophilic asthma remains to be investigated.