SANDIA: Supplementing L-citrulline to overweight late Asthma oNset phenotypes to increase airway L-arginine/ADMA ratio and Improve Asthma control

摘要 在美国，肥胖影响大约40%的成人哮喘患者。 儿童期（晚发），尽管呼出的一氧化氮较低，但可能具有高度症状且控制不良 （FeNO）水平。这种类型的迟发性哮喘是成人中常见的表型，特别是在 肥胖女性由于这些哮喘患者主要患有非T2型气道炎症，因此他们通常不能通过治疗来缓解哮喘。 对常规治疗有反应，并受到不受控制的症状的困扰， 针对这种主要哮喘表型的精确治疗方法。 几个关键的临床观察导致我们确定了一个潜在的机制途径，在晚期 肥胖型哮喘患者的发病可能导致他们的FeNO减少和呼吸道症状恶化。之间 在这些受试者中，BMI增加与NO的生物利用度降低相关，NO是一种重要的内源性 支气管扩张剂NO的减少通过NO合酶（NOS）的解偶联， 不对称二甲基精氨酸（ADMA）。这优先促进活性氧（ROS）的形成， NO产生的消耗，这也可以导致S-亚硝基谷胱甘肽（GSNO）的损失，S-亚硝基谷胱甘肽是一种有效的内源性谷胱甘肽， 支气管扩张剂，进一步促进支气管收缩。在这些哮喘患者中，较低的血浆L-精氨酸/ADMA比值， 与FeNO降低、肺功能降低和哮喘相关的生活质量相关， 呼吸道症状频率此外，在原代人气道上皮细胞中，低L-精氨酸解偶联 诱导型NOS（iNOS），降低NO生物利用度，增加ROS。L-精氨酸缺乏也可能导致 通过损害线粒体功能增加自由基形成和气道炎症。在我们的试点研究中， 晚发性哮喘患者给予L-瓜氨酸可增加痰液中L-精氨酸和L- 精氨酸/ADMA比值，增加FEV 1和FeNO，同时改善哮喘控制。此外，在哮喘气道中， 在上皮细胞中，L-瓜氨酸逆转ADMA介导的NOS解偶联，并减少硝基酪氨酸的形成。我们 假设补充L-瓜氨酸是一种安全、新型药物策略，通过以下方式治疗肥胖迟发性哮喘： 恢复L-精氨酸/ADMA比率，降低氧化和亚硝化应激，并最终减少支气管炎。 高反应性和改善哮喘控制。 为了验证这一假设，我们将在概念验证中使用L-瓜氨酸治疗晚发性肥胖哮喘患者 (POC)研究（目标1）。盲法治疗前后，支气管镜灌洗和上皮刷检分析 将在研究参与者的子集中进行，以确定细胞（目标2）和 亚细胞水平（Aim 3）。 由于目前的药物对肥胖迟发性哮喘的疗效有限，因此需要新的治疗方法。这 这项研究使我们有独特的机会来测试一种治疗肥胖性哮喘的新疗法，并专注于一种成分， 也可能与非T2表型有关，这占哮喘人群的大约一半。

ABSTRACT Obesity affects approximately 40% of adult asthmatics in the U.S. Obese patients who develop asthma after childhood (Late onset), can be highly symptomatic and poorly controlled despite having lower exhaled nitric oxide (FeNO) levels. This type of late onset asthma is a frequent phenotype encountered in adults, particularly among obese females. Because these asthmatics have predominantly non-T2 type airway inflammation, they often fail to respond to conventional therapy and are burdened by uncontrolled symptoms imploring the identification of novel precision therapeutic approaches for this predominant asthma phenotype. Several key clinical observations have led to our identification of a potential mechanistic pathway in late onset obese asthmatics that can account for their reduced FeNO and worsening respiratory symptoms. Among these subjects, increasing BMI associates with reduced bioavailability of NO, an important endogenous bronchodilator. The reduction of NO occurs through uncoupling of NO synthase (NOS), by accumulation of asymmetric di-methyl arginine (ADMA). This preferentially promotes reactive oxygen species (ROS) formation at the expense of NO production, which can also result in loss of S-nitrosoglutathione (GSNO), a potent endogenous bronchodilator, further promoting bronchoconstriction. In these asthmatics, lower plasma L-arginine/ADMA ratios, are associated with lower FeNO, reduced lung function and asthma related quality of life, as well as increased respiratory symptom frequency. Moreover, in primary human airway epithelial cells low L-arginine uncouples inducible NOS (iNOS), reducing NO bioavailability, and increasing ROS. L-arginine deficiency can also contribute to increased free radical formation and airway inflammation by impairing mitochondrial function. In our pilot studies, the administration of L-citrulline to patients with late onset asthma augments sputum L-arginine and the L- arginine/ADMA ratio, increasing FEV1 and FeNO, while improving asthma control. Further, in asthmatic airway epithelial cells, L-citrulline reverses ADMA-mediated NOS uncoupling and decreases nitrotyrosine formation. We hypothesize that L-citrulline supplementation is a safe, novel drug strategy to treat obese late onset asthma by restoring L-arginine/ADMA ratio, decreasing oxidative and nitrosative stress, and ultimately reducing bronchial hyperresponsiveness and improving asthma control. To test this hypothesis, we will treat late onset obese asthmatics with L-citrulline in a proof of concept (POC) study (Aim 1). Before and after blinded treatment, bronchoscopic lavage and epithelial brushing analyses will be performed in a subset of study participants to identify underlying mechanisms at the cellular (Aim 2) and subcellular levels (Aim 3). As current medications have limited efficacy in obese late onset asthma, new therapeutics are needed. This study allows us the unique opportunity to test a novel therapy for obese asthma and focus on a component that could also be relevant for non T2 phenotypes, which accounts for roughly half of the asthmatic population.