The role of IL-22 in allergic airway disease

The effector cytokine IL-22 produced by Th17 cells acts mainly on epithelial cells. For this cytokine both pro- and anti-inflammatory effects are reported. To assess the role of IL-22 in allergic airway disease C57BL/6 and IL22-deficient (IL-22^–/–) mice were sensitized with ovalbumine (OVA) on days 0 and 14 and challenged with OVA aerosol on days 28–30. 24h after the last challenge inflammation and airway reactivity were analyzed. Treatment of C57BL/6 mice with rIL-22 before each airway challenge was performed to assess therapeutic effects of this cytokine. Following exposure to allergen lungs of sensitized and challenged wild type (WT) mice displayed an increased expression of IL-22, aside from an increased airway hyperresponsiveness (AHR) and airway inflammation, compared to challenged only animals. Interestingly, significantly increased AHR and airway inflammation were observed in animals lacking IL-22 upon sensitization and challenge compared to equally treated WT animals suggesting a protective role of IL-22 in this model. The suppressive efficiency of IL-22 on the development of allergic airway disease was confirmed in WT mice. Treatment with rIL-22 reduced airway inflammation and AHR. In this study we demonstrated the regulative capacity of IL-22 on allergic airway disease in sensitized subjects. Considering the fact that treatment with rIL-22 effectively reduces allergen-induced AHR and airway inflammation suggests IL-22 as a potential therapeutic target for patients with allergic asthma.