Contribution of Interleukin-22 Binding Protein to the Development of Allergen-Induced Airway Hyperresponsiveness

Interleukin-22 binding protein (IL-22BP) is a soluble decoy receptor that competitively inhibits IL-22 by preventing its interaction with the IL-22 receptor. Although the IL-22 receptor is primarily expressed on non-hematopoietic cells, such as airway epithelial cells, the role of IL-22BP in the pathogenesis of asthma remains uncertain. We observed that IL-22BP was upregulated in the airways of wild-type (WT) mice intranasally sensitized and challenged with house dust mite (HDM) extract. To directly elucidate the function of IL-22BP in allergic airway responses, IL-22BP-deficient (IL-22BP-/-) and WT mice were sensitized and challenged with HDM, and airway responses were systematically assessed. IL-22BP-/- mice exhibited significantly lower airway hyperresponsiveness (AHR) compared to WT mice following sensitization and challenge with HDM. In contrast, eosinophil counts in bronchoalveolar lavage (BAL) fluid did not differ significantly between the two groups. Similarly, levels of interleukin (IL)-4, IL-5, IL-6, IL-13, IL-17A, and keratinocyte chemoattractant (KC) in BAL fluid were comparable between WT and IL-22BP-/- mice. Notably, IL-22 levels in lung homogenates were significantly higher in IL-22BP-/- mice than in WT mice after sensitization and challenge with HDM. These findings suggest that inhibition of IL-22BP attenuates the development of allergen-induced AHR, an effect likely mediated through enhanced IL-22 activity rather than alterations in airway inflammation or type 2 cytokine production.