Rat model of platelet-activating factor-induced rhinosinusitis.

Platelet-activating factor (PAF) is known to be a potent inflammatory mediator, especially in allergic inflammation. However, the exact role of PAF in the pathogenesis of rhinosinusitis has not been clearly established. To understand the role of PAF in the pathogenesis of rhinosinusitis, it is necessary to develop an animal model of PAF-induced rhinosinusitis. The aim of this study was to develop a rat model of rhinosinusitis induced by intranasally applied PAF. Fifty microliters of 16 microg/mL PAF was applied intranasally through each naris in 4-week-old Sprague-Dawley rats, and the same amount of vehicle was applied in control rats. At 1, 3, or 5 days, the animals were painlessly sacrificed, and the nasal cavity and sinuses were prepared for histologic investigation. The histologic sections were examined in a blind manner for the appearance of neutrophil clusters in the sinonasal air space, and the numbers of eosinophils, areas of epithelial loss, goblet cells, and inducible nitric oxide synthase (iNOS)-positive inflammatory cells in the mucosa. Neutrophil clusters were observed in the air space, and the number of eosinophils, areas of epithelial loss, goblet cells, and iNOS-positive inflammatory cells in the mucosa were increased significantly in the PAF-applied rats. The amount of inflammation varied according to the time interval, showing a peak at day 3. We conclude that intranasally applied PAF induces rhinosinusitis in rats. The histologic evidence of rhinosinusitis revealed the appearance of neutrophil clusters in the sinonasal air space, infiltration of eosinophils and iNOS-positive inflammatory cells in the mucosa, areas of epithelial loss, and goblet cell hyperplasia in the epithelium. This rat model of PAF-induced rhinosinusitis may be applied for better understanding of the role of PAF in the pathogenesis of rhinosinusitis.