Interleukin-31 promotes helper T cell type-2 inflammation in children with allergic rhinitis

Background: Interleukin-31 (IL-31) is a recently described cytokine that is involved in helper T cell type-2 (Th2)-mediated diseases. However, its regulatory effect in the pathogenesis of children allergic rhinitis (AR) needs to be further characterized. This study sought to evaluate the expression and role of IL-31 in children with AR. Methods: Sixty children with AR and 20 normal controls were included. IL-31 and Th2 cytokines production in tissue, serum, and nasal lavage was examined by immunohistochemistry, quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay, respectively. Peripheral blood mononuclear cells (PBMCs) were purified for in vitro regulation experiment of IL-31. Nasal epithelial cells (NECs) were cultured and stimulated by recombinant IL-31. Results: The IL-31 mRNA and protein levels in both serum and nasal lavage were significantly enhanced in AR compared with normal controls, especially in children with asthma. The nasal IL-31 was associated with enhanced local Th2 cytokines and mucin 5AC (MUC5AC) expression. In vitro study showed that IL-31 promotes Th2 cytokines expression and MUC5AC upregulation and thus amplified Th2 inflammation. Conclusion: Our results demonstrate that IL-31 expression in AR aggravated and amplified Th2 inflammation as well as mucin production, and provide a possible explanation for IL-31’s regulatory role in the pathogenesis of AR.