IL-32 up-regulation is associated with inflammatory cytokine production in allergic rhinitis

IL-32 is a described pro-inflammatory cytokine produced by T lymphocytes, natural killer cells, monocytes, and epithelial cells. However, the specific mechanism of IL-32 on allergic rhinitis (AR) has not been elucidated. Here, we report a significant increase of IL-32 protein and mRNA in the nasal mucosa of AR patients. In addition, in nasal mucosa tissue from AR patients, the level of IL-32 production correlated with inflammation, IL-1β, IL-18, and granulocyte-macrophage colony-stimulating factor (GM-CSF). In an AR animal model, IL-32 significantly increased IgE and inflammatory cytokine levels. IL-32 expression was induced by recombinant human GM-CSF via activation of caspase-1 in eosinophils. In addition, depletion of IL-32 prevents the production of inflammatory cytokines in eosinophils. In conclusion, IL-32 is an important cytokine involved in the inflammation of AR. The regulation of IL-32 expression may form the basis of a new strategy for the treatment of AR.