Interleukin‐17A potentiates interleukin‐13‒induced eotaxin‐3 production by human nasal epithelial cells from patients with allergic rhinitis.

Background: Interleukin (IL)‐17A is involved in the pathogenesis of allergic rhinitis (AR). Increased expression of IL‐17A is correlated with disease severity and nasal eosinophilia. However, the molecular mechanisms by which IL‐17A contributes to T‐helper 2 cytokine IL‐13‒driven pathology in AR remain unclear. We sought to obtain mechanistic insight into how IL‐17A and IL‐13 regulate the epithelial production of eotaxin‐3 representing eosinophilic inflammation in AR. Methods: Human nasal epithelial cells (HNECs) from AR patients were cultured and stimulated with IL‐17A, IL‐13, or IL‐17A and IL‐13. Phosphorylated signal transducer activator of transcription 6 (p‐STAT6) and suppressor of cytokine signaling 1 (SOCS1) in HNECs were assayed using Western blotting. Immunocytochemistry was used to determine p‐STAT6‒positive expression in the cells. Eotaxin‐3 expression in the cells and culture supernatants was evaluated using real‐time polymerase chain reaction and enzyme‐linked immunosorbent assays. Results: Stimulation with IL‐13 alone induced STAT6 phosphorylation and promoted p‐STAT6 nuclear translocation, leading to eotaxin‐3 production by HNECs. These effects were further enhanced by cotreatment with IL‐13 and IL‐17A, whereas IL‐17A alone had no impact on STAT6 or eotaxin‐3 expression. Incubation with IL‐17A or IL‐13 increased the level of SOCS1 protein in the cells, whereas the addition of IL‐17A attenuated IL‐13‒induced SOCS1 expression. Conclusion: IL‐17A potentiated IL‐13‒driven STAT6 activation through the downregulation of SOCS1 expression, leading to enhancement of eotaxin‐3 production by HNECs. These factors contributed to eosinophilic inflammation in AR. [ABSTRACT FROM AUTHOR]