Expression of interleukin (IL)-17F in a mouse model of asthma

A novel cytokine, IL-17F is a secreted cytokine expressed in activated CD4+ T cells, monocytes, basophils and mast cells. IL-17F induces inflammatory cell infiltration in human organ through production of several cytokines and chemokines such as IL-6, IL-8, GRO alpha, GM-CSF, ENA-78 and ICAM-1. In vivo, the expression of IL-17F in the allergic airway inflammation has not been unknown yet. BALB/C mice (6 weeks, male) were sensitized with ovalbumin (OVA) by means of intraperitoneal injection (50 μg/body) at day 1, 7, 14 and 28, and nebulization (1% solution) at day 35 to 41. After sensitization, allergen provocation (OVA) was performed at day 43, and mice whole lungs were dissected. Intraperitoneal treatment with Dexamethasone (0.1mg/body) was performed 30 min before OVA nebulization. The expression of IL-17F was analyzed by RT-PCR and Immunohistochemistry. Airway hyperresponsiveness (AHR) to methacholine was assessed by the dimensionless parameter Penh. RT-PCR and Immunohistochemistry showed in vivo expression of IL-17F, in the airway of asthmatic mouse (OVA-sensitized and challenged). IL-17F was expressed in infiltrated inflammatory cells and airway epithelium. Dexamethasone treatment clearly inhibited not only AHR and inflammatory cell recruitment, but also the expression of IL-17F. These findings suggest that IL-17F is involved in the allergic inflammatory airway diseases such as bronchial asthma.