Expression of Inducible Nitric Oxide Synthase and Its Steroid Effect in TDI-Induced Nasal Hyperreactive Guinea Pigs / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Nitric oxide (NO) in exhaled air is elevated in allergy. Topical corticosteroid therapy which has been shown to reduce airway inflammation is associated with reduction in exhaled levels of NO in allergy. The aim of this study is to investigate the induction of inducible nitric oxide synthase (iNOS) and the effect of steroid on the expression of iNOS in the nasal mucosa of TDI (toluene diisecyanate)-induced nasal hyperreactive guinea pig. MATERIALS AND METHODS: We developed an allergy model in guinea pigs using the intranasal application of TDI, We evaluated the iNOS expression and in vivo effects of triamcinolone on the expression of iNOS and infiltration of eosinophil in TDI-sensitized guinea pigs by immunohistochemical stain. RESULTS: Nasal symptoms were significantly suppressed and the number of eosinophils in the nasal mucosa were significantly inhibited by the treatment of triamcinolone. Immunoreactivity to iNOS was localized to ciliated cells of epithelium, vascular endothelial cells, secretory cells of nasal glands and some inflammatory cells in the mucosa of the control group. High expression of iNOS in the nasal mucosa of the TDI-sensitized group was demonstrated, and it was suppressed by triamcinolone therapy. CONCLUSION: These results show that increased expression of iNOS may contribute to allergic inflammation and the antiinflammatory effect of steroid in allergy is partly mediated by the reduction of iNOS expression.