S-NITROSOTHIOL BREAKDOWN BY AIRWAY EPITHELIAL CELLS

S-亚硝硫醇(SNO)和S-亚硝基谷胱甘肽(GSNO) 特别是稳定、有效的支气管扩张剂，它也有免疫力 其调节功能存在于正常人体呼吸道中。 哮喘支气管痉挛与反常的低气道SNO相关 水平-以及无法检测到的GSNO水平-尽管相对较高 呼气末空气中一氧化氮(NO)浓度及升压 诱导型一氧化氮合酶。这一悖论最好的解释可能是 考虑将GSNO作为生物活性氮氧化物的储存库 呼吸道--就像它在大脑和其他组织中一样--其分解 在哮喘中加速。从这个意义上讲，呼吸道SNO分解代谢可能 导致过高的过期一氧化氮浓度和支气管痉挛 在哮喘患者中。本项目将检验假设1) 呼吸道上皮细胞分解SNO；2)SNO分解代谢活性 与哮喘相关的兴奋剂改变了呼吸道上皮细胞的数量 病理生理学；3)呼吸道上皮细胞介导的SNO分解代谢 抑制呼吸道平滑肌松弛。一种新的方法将是 用于研究有呼吸道存在时SNO向NO的转化 细胞。使用该系统的初步数据表明，有 催化GSNO分解的上皮细胞蛋白。这些蛋白质 将根据大小、顺序、反应物和 产品化学计量学和动力学。此外，白介素2的作用 血管活性肠肽、地塞米松、阿昔维辛、 硫代葡萄糖苷和血红蛋白对上皮细胞GSNO分解代谢的影响 将对氮氧化物的运输进行调查。最后，相关性 上皮细胞GSNO的分解将在豚鼠的生物试验中进行研究 气道平滑肌松弛。总而言之，这个项目将测试 GSNO介导的气道平滑肌松弛的总体假说 在呼吸道上皮细胞存在的情况下被抑制，受调节的 催化GSNO分解代谢的蛋白质。如果这一假设得到证实， 防止GSNO分解代谢可能定义新的哮喘治疗方法。

S-Nitrosothiols (SNOs) in general - and S-nitrosoglutathione (GSNO) in particular - are stable, potent bronchodilators which also have immune regulatory functions and are present in the normal human airway. Asthmatic bronchospasm is associated with paradoxically low airway SNO levels - and undetectable GSNO levels - despite relatively high concentrations of nitric oxide ( NO) in expired air and upregulation of inducible-nitric oxide synthase. This paradox may be best explained by considering GSNO to be a reservoir of bioactive nitrogen oxides in the airway - as it is in brain and other tissues - the breakdown of which is accelerated in asthma. In this sense, airway SNO catabolism may contribute both to high expired NO concentrations and to bronchospasm in asthmatic patients. This project will test the hypotheses that 1) airway epithelial cells catabolize SNO; 2) the SNO catabolic activity of airway epithelial cells is altered by stimulants relevant to asthma pathophysiology; and 3) airway epithelial cell-mediated SNO catabolism inhibits airway smooth muscle relaxation. A new methodology will be used to study the conversion of SNO to NO in the presence of airway cells. Preliminary data using this system suggest that there are epithelial cell proteins which catalyze GSNO breakdown. These proteins will be characterized with regard to size, sequence, reactant and product stoichiometry and kinetics. Further, the effects of interleukin 4, vasoactive intestinal peptide, dexamethasone, acivicin, aurothioglucose and hemoglobin on epithelial GSNO catabolism and nitrogen oxide transport will be investigated. Finally, the relevance of epithelial GSNO breakdown will be studied in a bioassay of guinea-pig airway smooth muscle relaxation. In summary, this project will test the overall hypothesis that GSNO-mediated relaxation of airway smooth muscle is inhibited in the presence of airway epithelial cells by a regulated protein which catalyzes GSNO catabolism. If this hypothesis is proven, prevention of GSNO catabolism may define new asthma therapies.