Enhanced Type 2 Immune Reactions by Increased IL-22/IL-22Ra1 Signaling in Chronic Rhinosinusitis With Nasal Polyps.

Purpose: Recent studies have revealed the pathogenic role of interleukin (IL)-22 in atopic dermatitis and asthma. However, little is known about the role of IL-22 in the pathophysiology of chronic rhinosinusitis with nasal polyps. We aimed to investigate the expression of IL-22 and its pathogenic function in type 2 immune reactions of nasal polyps (NP).

Methods: Protein levels of inflammatory mediators were determined by multiplex immunoassay, and principal component analysis (PCA) was performed. Immunofluorescence analysis and mast cell culture were used to determine the cellular sources of IL-22. Normal human bronchial epithelial (NHBE) cells were stimulated using IL-22 in combination with diverse cytokines, and thymic stromal lymphopoietin (TSLP) was measured.

Results: IL-22 expression was not up-regulated in NP compared with control tissues, but IL-22-high NP revealed distinct features characterized by type 2 inflammatory cytokines such as chemokine (C-C motif) ligand (CCL)-11, CCL-24, and IL-5 on the PCA. Additionally, IL-22 positively correlated with type 2 immune mediators and the disease severity in NP. For the localization of the cellular sources of IL-22 in eosinophilic NP, it was expressed in cells mostly composed of eosinophil peroxidase-positive cells and partially of tryptase-positive cells. The human mast cell line, LAD2 cells, released IL-22 mediated by immunoglobulin E. Moreover, IL-22 receptor subunit alpha-1 (IL-22Ra1) expression was significantly increased in NP. IL-22Ra1 was up-regulated with poly(I:C) stimulation in NHBE cells. Furthermore, TSLP production was enhanced when stimulated with a combination of IL-13, poly(I:C), and IL-22. Treatment with anti-IL-22Ra1 also inhibited IL-22-induced enhancement of TSLP production.

Conclusion: IL-22 was associated with type 2 inflammatory reactions in NP. The IL-22/IL-22Ra1 axis was enhanced and might be involved in type 2 inflammatory reactions via TSLP production in NP.