Background: Interleukin (IL)-17F is a recently discovered cytokine and is derived from a panel of limited cell types, such as activated CD4+ T cells, basophils, and mast cells. IL-17F is known to induce several cytokines and chemokines. However, its involvement in airway inflammation has not been well understood. To this end, the expression of IL-17F and the inhibitory effects of glucocorticoids on its expression in a mouse model of asthma were examined. Methods: Five-week-old BALB/c male mice were sensitized by intraperitoneal injection (i.p.) of ovalbumin (OVA) with alum, and challenged by daily inhalation of aerosolized 1% OVA. 24 h after last challenge (OVA/OVA), the expression of IL-17F was examined in lung tissues by immunohistochemistry and reverse-transcription polymerase chain reaction. Control mice were sensitized and challenged with saline (Sham/Sham). In addition, a group of OVA-sensitized mice received i.p. injection of water-soluble dexamethasone (DEX) in saline 1 h before OVA challenge (OVA/DEX). Results: In sham-challenged mice, IL-17F was not expressed in the lungs, while, in contrast, IL-17F was predominantly expressed in bronchial epithelial cells in addition to the infiltrating inflammatory cells in OVA/OVA mice. Further, the expression of IL-17 F was significantly attenuated by the treatment of mice with DEX. Conclusion: These results suggest that bronchial epithelium-derived IL-17F may represent a new pharmacological target for glucocorticoids and may play a role in allergic asthma.
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