ObjectiveTo investigate the role of interleukin-25 (IL-25) and its receptor during allergen challenge test in allergic asthmatics as well as its underlining mechanism.MethodsFifteen allergic asthmatic patients with dual response in allergen challenge test were enrolled and blood samples were collected before and after challenge test. The expression levels of IL-25 receptor on the surface of eosinophils, plasma and intracellular IL-25 levels were measured by flow cytometry and enzyme-linked immunosorbent assay. Besides, the function of eosinophils from these patients was evaluated through the expression of type 2 cytokines, degranulation and chemotaxis after stimulation with IL-25.ResultsUpon allergen challenge, the expression of IL-17RB on the surface of eosinophils were increased from (7 426±2 824)/106 white blood cells to (19 446±5 593)/106 white blood cells (P<0.001). The expression of IL-17RA/RB on eosinophils were significantly increased from (4 508±1 360)/106 white blood cells to (9 025±3 166)/106 white blood cells (P<0.001). The plasma level of IL-25 increased from (650±45) pg/ml to (851±43) pg/ml (7 hours after allergen challenge) and (813±56) pg/ml (24 hours after allergen challenge) (P<0.001). The intracellular IL-25 expression of eosinophils was also upregulated from (10 398±1 909)/106 white blood cells to (147 684±46 222)/106 white blood cells (P<0.05). In vitro study, IL-25 (1 ng/ml) stimulated eosinophils for 2 hours promoted its expression of peroxidase [(12.5±4.2) ng/ml compared to control (1.26±0.4) ng/ml, P<0.05). The intracellular expression of IL-5 and IL-13 in eosinophils were also increased after stimulated by IL-25. IL-25 (1 pg/ml) stimulation compared to control could increase eosinophil migration in eotaxin [(36±3) vs. (69±5), P<0.05).ConclusionIL-25 and its receptor play a critical role in eosinophilic aggregation, activation and mobilization during allergic inflammation in allergic asthmatics.
