The Effect of Short-Term Systemic and Long-Term Topical Steroid Treatment on Nitric Oxide Synthases in Nasal Polyp / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Nitric oxide (NO) is an endogenous free radical gas mediator, synthesized by a family of nitric oxide synthases (NOS). Established properties of NO of potential relevance to the formation of nasal polyps include vasodilatation, direct regulation of eosinophil and neutrophil function, and potentiation of histamine-induced plasma exudation. Steroids are currently the most potent medication available for the treatment of nasal polyposis, but the exact mechanisms are uncertain. The purpose of this study was to evaluate the response of three NOS isoenzymes to short-term systemic and long-term topical steroid in nasal polyps. MATERIALS AND METHOD: Steroid-untreated nasal polyp patients (n=10), oral steroid-treated nasal polyp patients (n=10, prednisolone 30 mg per day for 7days) and topical steroid-treated nasal polyp patients (n=10, Fluticasone 100 microgram per day for more than 1 month) underwent nasal endoscopy and biopsy of the polyps. The protein expressions of NOS in nasal polyp tissues were evaluated by immunohistochemistry. RESULTS: Immunohistochemical studies revealed that expression levels of proteins produced by three NOS isoenzymes were significantly decreased in steroid-treated nasal polyps when compared with steroid-untreated nasal polyps, and there was no difference in the effects between short-term systemic and long-term topical steroid treatment on nasal polyps. CONCLUSION: These results show that the expressions of constitutive NOS as well as inducible NOS in nasal polyp tissue were suppressed by steroid therapy. There was no difference in the NOS isoenzymes expression between short-term systemic and long-term topical steroid-treated polyps.