Effects of 1,25-dihydroxyvitamin D3 in an ovalbumin-induced allergic rhinitis model

IL-17-producing Th17 cells play an important role in allergic airway diseases, but their local expression and regulation in allergic rhinitis (AR) is not well understood. This study investigated the effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)₂D₃) on T-bet expression, Th1 cells, Th2 cells, Th17 cells and IL-33-positive epithelial cells in AR. C57BL/6 mice were intranasally sensitized and challenged with ovalbumin (OVA), and 1,25-(OH)₂D₃ was intraperitoneally injected into AR mice. Cytokine levels were measured with enzyme-linked immunosorbent assays, phenotypic analysis of Th1, Th2 and Th17 cells in the spleen was completed with flow cytometry, and the CD4⁺IL-17⁺ cells in the Nasopharynx-associated lymphoid tissue (NALT) and IL-33-positive cells in nasal mucosa was evaluated with immunofluorescence microscopy. AR mice shown significantly increased Th2 and Th17 cell ratio in spleen, IL-17 level in serum, IL-5 and IL-13 levels in NALF but a lower number of IL-33-positive epithelial cells and Th1 response (Th1 and Tbet⁺Th1 cell ratio in the spleen and serum IFN-γ level) than the control mice.1,25-(OH)₂D₃ treatment significantly decreased the number of sneezing, nasal rubbing, OVA-sIgE and IL-17 in serum, IL-5 and IL-13 levels in NALF, Th17 cell ratio in the spleen and the histological of nasal mucosal but increased the number of IL-33-positive epithelial cells in AR mice. However, 1,25-(OH)₂D₃ treatment did not significantly influence IFN-γ level in serum, and Th1, Tbet⁺Th1 and Th2 cell ratio in spleen. Thus, 1,25-(OH)₂D₃ may exert anti-allergic effects by suppressing Th17 responses and local production of IL-5 and IL-13 cytokines.