GSNO Reductase, S-Nitrosothiols, and Asthma

描述（由申请方提供）：在人体中，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，其调节肺GSNO水平的水平。野生型小鼠在过敏原激发后GSNOR活性增加，肺S-亚硝基硫醇（SNO）浓度降低，并患有气道超敏反应增加。相比之下，GSNOR基因缺失的小鼠在过敏原攻击后肺SNO水平增加，并受到保护，免于气道高反应性。GSNOR缺陷小鼠的基础支气管张力也低于正常动物，并且在用β 2激动剂治疗重复刺激后不脱敏，表明内源性SNO调节平滑肌张力。这些结果在小鼠中提供了遗传证据，即动态SNO周转是NO在健康和疾病中发挥作用的关键机制。在本基金申请中，我们将检验以下假设：气道内源性支气管扩张剂GSNO的耗竭增加了气道对乙酰甲胆碱的高反应性，并降低了对吸入性β 2激动剂的反应。我们将首先确定GSNOR活性在人类哮喘中是否增加以及是否与气道SNO表达相关（目的1）。我们接下来将确定GSNOR活性是否预测对吸入β 2激动剂治疗的反应性，以及与对照受试者相比，GSNOR多态性的存在是否预测哮喘患者的酶活性、气道SNO浓度和对β 2激动剂的反应性（目的2）。最后，我们计划确定在轻度哮喘受试者中补充SNO是否对乙酰甲胆碱诱导的支气管收缩和对吸入β 2激动剂的脱敏具有保护作用（目的3）。这一提议将进一步加深我们对GSNOR和SNO在哮喘中的理解，它们如何在哮喘中作为稳态剂发挥作用，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.