IL-25 was required for induction of allergic airway inflammation
To determine whether IL-25 is essential for induction of allergic airway inflammation, we subjected wild-type and IL-25-deficient mice (Il25-/-) to allergic airway inflammation induced by house-dust mite (HDM), the most common allergen of allergic asthma in Chinese patients24 (Figure 4A). After a sensitization and challenge phase with HDM, wild-type mice developed a severe lung pathology, increased serum IgE, and high Th2-cell-mediated inflammatory responses. We found that Il25-/- mice, compared with WT mice, had an alleviated airway pathology via H&E staining and periodic acid-Schiff (PAS) assay (Figure 4C), decreased IgE production (Figure 4B) and cellular infiltration in the airways (Figure 4D), less eosinophils (Figure 4E) and reduced Th2-cytokines level, including IL-4, IL-5, IL-13 (Figure 4F~H). These data suggest that IL-25 is required to maintain disease severity during allergen-mediated immune responses.