IL-25 deficiency reduced eosinophil chemotaxis after HDM sensitization in lung and BALF
Previous studies have identified eosinophils process antigen to promote Th2 cells expansion25-27. Since the antigen-presenting role occurs during the sensitization phase, we wondered whether IL-25 affects eosinophils during the sensitization phase. Sensitized dose of HDM was administrated intranasally into WT mice and we explored lung eosinophils chemotaxis from day 0 to day 5 (Figure 5A) and found that on the third day eosinophils were significantly increased after HDM sensitization, suggesting it may exert an antigen-presenting role at this time (Figure 5B,5C). To determine whether IL-25 contributes to the role of eosinophils in sensitization response, we analyzed eosinophils chemotaxis in IL-25-/- mice 3 days after HDM sensitization (Figure 5D). IL-25-/- mice exhibited reduced eosinophils compared with WT mice, both in lung and BALF (Figure 5E~H), which demonstrated the effect of IL-25 in promoting eosinophils chemotaxis to airway to exert its role in the sensitization phase, before the onset of effector stage.