GSNO Reductase, S-Nitrosothiols, and Asthma

描述(申请人提供)：在人体内，内源性支气管扩张剂S-亚硝基谷胱甘肽(GSNO)在哮喘患者的呼吸道中被耗尽。GSNO还原酶(GSNOR)是一种广泛表达于包括肺在内的组织中的酶，调节肺中GSNO的水平。野生型小鼠在过敏原攻击后出现GSNOR活性增加和肺组织S-亚硝硫醇(SNO)浓度下降，并患有增加的呼吸道超敏反应。相反，GSNOR基因缺失的小鼠在过敏原攻击后肺SNO水平升高，并受到保护，免受呼吸道高反应性的影响。GSNOR缺陷小鼠的基础支气管张力也低于正常动物，并且在重复使用(2)激动剂治疗后不脱敏，这表明内源性SNO调节平滑肌张力。这些结果在小鼠身上提供了遗传证据，表明动态SNO代谢是NO在健康和疾病中发挥作用的关键机制。在这项赠款申请中，我们将检验一种假设，即从呼吸道中耗尽内源性支气管扩张剂GSNO会增加对乙酰甲胆碱的气道高反应性，并降低对吸入(2)激动剂在人类哮喘中的反应。我们将首先确定GSNOR活性在人类哮喘中是否增加，并与气道SNO表达相关(目标1)。接下来，我们将确定GSNOR活性是否可以预测吸入(2)激动剂治疗的反应性，以及与对照组(目标2)相比，GSNOR基因多态性的存在是否可以预测酶活性、气道SNO浓度以及对(2)激动剂的反应。最后，我们计划确定在轻度哮喘患者中补充SNO是否对乙酰甲胆碱引起的支气管收缩和吸入(2)激动剂(目标3)的脱敏具有保护作用。这一建议将加深我们对GSNOR和SNO在哮喘中的作用的理解，它们如何在哮喘中作为动态平衡药物发挥作用，以及SNO的再补充如何提供新的治疗靶点。

DESCRIPTION (provided by applicant): In humans, S-nitrosoglutathione (GSNO), an endogenous bronchodilator, is depleted in the airway of asthmatics. GSNO reductase (GSNOR), an enzyme widely expressed across tissues including lung, regulates levels of lung GSNO levels. Wild-type mice develop increased GSNOR activity and decreased lung S-nitrosothiol (SNO) concentration following allergen challenge and suffer from increased airway hypersensitivity. In contrast, mice with a genetic deletion of GSNOR have increased lung SNO levels after allergen challenge and are protected from airway hyperreactivity. GSNOR deficient mice also have lower basal bronchial tone than normal animals and do not desensitize after repeated stimulation with (2 agonist therapy suggesting that endogenous SNOs regulate smooth muscle tone. These results provide genetic evidence in mice that dynamic SNO turnover is a critical mechanism of NO function in health and disease. In this grant application, we will test the hypothesis that depletion of the endogenous bronchodilator, GSNO, from the airway increases airway hyperresponsiveness to methacholine and decreases response to inhaled (2 agonists in human asthma. We will first determine if GSNOR activity is increased in human asthma and correlates with airway SNO expression (Aim 1). We will next determine if GSNOR activity predicts responsiveness to inhaled ((2 agonist therapy and if the presence of polymorphisms of GSNOR predicts enzyme activity, airway SNO concentration, and response to (2 agonists in asthmatic as compared to control subjects (Aim 2). Finally, we plan to determine whether repletion of SNO in subjects with mild asthma confers protection against methacholine induced bronchoconstriction and desensitization to an inhaled (2 agonist (Aim 3). This proposal will further our understanding of GSNOR and SNOs in asthma, how they function as homeostatic agents in asthma, and how repletion of SNO provides a novel therapeutic target.