GSNO Reductase, S-Nitrosothiols, and Asthma

描述（由申请人提供）：在人类中，s -亚硝基谷胱甘肽（GSNO）是一种内源性支气管扩张剂，在哮喘患者的气道中耗尽。GSNO还原酶（GSNOR）是一种在包括肺在内的组织中广泛表达的酶，可调节肺GSNO水平。野生型小鼠在过敏原刺激后GSNOR活性增加，肺s -亚硝基硫醇（SNO）浓度降低，气道超敏反应增加。相比之下，GSNOR基因缺失的小鼠在过敏原攻击后肺部SNO水平增加，并保护气道不发生过度反应。GSNOR缺陷小鼠的基础支气管张力也低于正常动物，并且在(2)激动剂治疗反复刺激后不会脱敏，这表明内源性SNOs调节平滑肌张力。这些结果为小鼠提供了遗传学证据，表明动态SNO转换是NO功能在健康和疾病中的关键机制。在这项拨款申请中，我们将验证一个假设，即从气道中消耗内源性支气管扩张剂GSNO会增加气道对甲胆碱的高反应性，并降低对吸入(2)激动剂的反应。我们将首先确定GSNOR活性是否在人类哮喘中增加并与气道SNO表达相关（目的1）。接下来，我们将确定GSNOR活性是否预测吸入(2)激动剂治疗的反应性，以及GSNOR多态性的存在是否预测哮喘患者与对照组相比对(2)激动剂的酶活性、气道SNO浓度和反应(2)。最后，我们计划确定轻度哮喘患者的SNO充血是否能保护其免受甲胆碱诱导的支气管收缩和对吸入(2)激动剂的脱敏（Aim 3）。这一建议将进一步加深我们对哮喘中GSNOR和SNOs的理解，它们如何在哮喘中作为体内平衡剂发挥作用，以及SNO的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.