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

摘要 肥胖影响了美国大约40%的成年哮喘患者。肥胖患者在 儿童期(晚发)，尽管呼出的一氧化氮较少，但症状严重且控制不佳 (FeNO)水平。这种类型的迟发性哮喘是成人常见的表型，尤其是在 肥胖的女性。由于这些哮喘患者主要患有非T2型呼吸道炎症，他们经常无法 对常规治疗有反应，并承受着无法控制的症状，要求识别新的 这种主要哮喘表型的精确治疗方法。 几个关键的临床观察使我们在晚期发现了一个潜在的机制途径。 起病的肥胖哮喘患者，可以解释他们的FeNO减少和呼吸道症状恶化。其中 这些受试者，增加的BMI与NO的生物利用度降低有关，而NO是一种重要的内源性物质 支气管扩张剂。NO的还原是通过解偶联一氧化氮合酶(NOS)，通过积累 不对称二甲基精氨酸(ADMA)。这优先促进了活性氧物种(ROS)在 NO生产的代价，这也会导致内源强效物质S-亚硝基谷胱甘肽的损失 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比率， 与FeNO降低、肺功能降低和哮喘相关的生活质量有关，以及增加 呼吸道症状频度。此外，在原代人呼吸道上皮细胞中，L-精氨酸解偶联 诱导型一氧化氮合酶(INOS)，降低NO的生物利用度，增加ROS。L-精氨酸缺乏也可能导致 通过损害线粒体功能来增加自由基的形成和呼吸道炎症。在我们的初步研究中， 迟发性哮喘患者应用L-瓜氨酸对痰L-精氨酸和L-精氨酸的影响 精氨酸/ADMA比值，增加FEV1和FeNO，同时改善哮喘控制。此外，在哮喘的呼吸道中 L-瓜氨酸可逆转ADMA介导的一氧化氮合酶解偶联，减少硝基酪氨酸的生成。我们 假设L-瓜氨酸补充剂是一种安全、新颖的药物策略，通过以下方式治疗肥胖型晚发哮喘 恢复L-精氨酸/ADMA比值，减轻氧化和亚硝化应激，最终减少支气管 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性哮喘患者。 (POC)研究(目标1)。盲法治疗前后支气管镜灌洗及上皮刷检分析 将在研究参与者的子集中进行，以确定细胞的潜在机制(目标2)和 亚细胞水平(目标3)。 由于目前的药物对肥胖晚发型哮喘的疗效有限，因此需要新的治疗方法。这 研究使我们有机会测试一种治疗肥胖性哮喘的新疗法，并将重点放在 也可能与非T2表型有关，非T2表型约占哮喘人口的一半。

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.