비용조직에서 산화질소합성효소들의 발현

Background and Objective: The pathogenesis of nasal polyp is poorly understood. Nitric oxide (NO) plays a major role in a number of physiologic function and may be cytotoxic in high concentrations. NO is formed by the oxidative deamination of L-arginine by nitric oxide synthases (NOS). Three NOS isoforms have been identified in human. Constitutive forms of NOS are present in vascular endothelial cells (Type III NOS, eNOS) and neurons in the brain and the peripheral nervous system (Type I NOS, nNOS) whereas the inducible form (Type II NOS, iNOS) is transcriptionally induced by cytokines in macrophages, neutrophils, mast cells, smooth-muscle cells, and fibroblasts. The aim of this study was to detect and localize three NOS isoforms expression in nasal polyp tissues, and compare these findings with inferior nasal turbinate tissues. Materials and Methods: The authors examined the expression and localization of three NOS isoforms in nasal mucosal specimens from patients undergone elective nasal turbinectomy (n=10) and nasal polypectomy (n=23). The mRNA expressions of three NOS isoforms were determined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern hybridization. The protein expression of three NOS isoforms were examined by immunohistochemistry. Statistics were analysed using Wilcoxon rank sum test. Results: Semi-quantitative RT-PCR Southern analysis of RNA obtained from 23 surgical specimens of nasal polyps demonstrated that the mRNA expressions of iNOS and eNOS were significantly increased in nasal polyps compared with inferior turbinates. The nNOS mRNA was similarly expressed in nasal polyps and inferior turbinates. The immunohistochemical studies revealed that the immunoreactivity to iNOS protein was mainly localized to epithelium, whereas eNOS protein to vascular endothelium, and nNOS protein to inflammatory cell, epithelium and vascular endothelium in all specimens reviewed. The high level of expression of three NOS isoforms in the nasal polyps were demonstrated in this study. Conclusion: The authors suggest that iNOS mRNA, eNOS mRNA and their product, nitric oxide may play an important role in the formation and growth of nasal polyps. (J Clinical Otolaryngol 2002;13:85-92)