Optimizing Beta-Adrenoceptor Signaling Bias in Asthma

描述(由申请人提供)：β-2-肾上腺素能受体激动剂，通常被称为-激动剂，近半个世纪以来一直是哮喘治疗的基石。然而，尽管它们有效，但用于哮喘治疗的？激动剂存在问题，包括功能性快速反应、哮喘控制恶化和死亡率问题。20多年来，美国国立卫生研究院计划宣布需要更安全、更有效的哮喘治疗替代品，这反映了人们无法理解为什么会存在这样的问题，也无法显著改善ç2AR的药理学。我们最近发表和未发表的研究提供了令人信服的洞察力，为什么？激动剂是有问题的，同时为它们的临床应用提供了解决方案。我们的数据有力地表明，ü2AR激动剂在过敏性肺部炎症和相关的气道高反应性(AHR)的发展中起着允许的作用，内源性(肾上腺素)以及外源性ç-激动剂激活了促进哮喘表型的致病机制。新的数据表明，？2ARs在呼吸道细胞中有两种不同的信号转导途径：由？-arrestin2介导的促炎信号通路，以及由Gs蛋白介导的抗炎和支气管保护信号通路。我们建议开展研究以解决哮喘的“？2AR悖论”，方法是建立这些？2AR信号通路在调节哮喘表型中的细胞特异性作用，并从现有的和新产生的？2AR配体或调节剂中确定那些具有偏向信号特性的配体或调节剂，这些特性在通过阻滞素拮抗致病的？2AR信号，同时促进有益的G蛋白信号的能力方面是最佳的。我们将使用多种系统，包括细胞、组织和活体模型，来检验这一中心假设，即通过呼吸道上皮细胞中的ü-arrestin2信号对过敏原诱导的哮喘表型至关重要，而在启用Gs蛋白信号的同时拮抗？-arrestin2信号的偏向2AR配体或调节剂在哮喘的治疗中更有效。目的1将采用基因策略，使细胞特异性的？2AR基因消融或表达，以确定呼吸道上皮和平滑肌细胞中？2AR激动剂在介导变态反应性肺部炎症、粘蛋白产生和AHR中的必要性和充分性。目的2将采用类似的遗传学方法，在活体内建立由2AR介导的PKA和arrestin依赖的信号在调节哮喘表型中的作用，以及分子生物学方法来表征PKA和arrestin对人和小鼠呼吸道上皮细胞粘蛋白产生和炎症介质的依赖调节。目的3将利用药理学和遗传学方法，并确定已批准的和新的ç2AR配体的有偏信号特性，以最终确定PKA和arrestin信号在调节哮喘表型中的作用。总而言之，这些研究将通过确定与过敏性肺部炎症有关的基本致病信号机制，以及通过表征用于治疗哮喘患者的最佳配体，显著推动哮喘生物学和哮喘药理学领域的发展。

DESCRIPTION (provided by applicant): Agonists of the beta-2-adrenoceptor (ß2AR), commonly referred to as ß-agonists, have been a cornerstone of asthma treatment for nearly half a century. Despite their utility, however, ß-agonists used in asthma management have problems, including functional tachyphylaxis, deterioration of asthma control, and mortality concerns. The inability to understand why such problems exist and the failure to significantly improve ß2AR pharmacology is reflected by over 2 decades of NIH Program announcements declaring the need for safer, more efficacious alternatives to asthma treatment. Our recent published and unpublished studies provide compelling insight into why ß-agonists are problematic while offering a solution to their clinical application. Our data strongly suggest that ß2AR agonism plays a permissive role in the development of allergic lung inflammation and associated airway hyperresponsiveness (AHR), and that endogenous (epinephrine) as well as exogenous ß-agonists invoke pathogenic mechanisms promoting the asthma phenotype. New data suggest that ß2ARs transduce 2 qualitatively distinct signaling pathways in airway cells: pro-inflammatory signaling mediated by ß-arrestin2, and anti-inflammatory and bronchoprotective signaling mediated by Gs proteins. We propose studies to solve the asthma "ß2AR paradox" by establishing the cell-specific role of these ß2AR signaling pathways in regulating the asthma phenotype, and identifying from among current and newly generated ß2AR ligands or modulators those with biased signaling properties that are optimal in their ability to antagonize pathogenic ß2AR signaling via arrestins, yet promote beneficial G protein signaling. We will employ many systems, including cell, tissue, and in vivo models, to test the central hypothesis that ß2AR signaling via ß-arrestin2 in airway epithelia is critical to the allergen-induced asthma phenotype, and biased ß2AR ligands or modulators that antagonize ß-arrestin2 signaling while enabling Gs protein signaling are more efficacious in the treatment of asthma. Aim 1 will employ genetic strategies enabling cell-specific ß2AR gene ablation or expression to establish the requirement and sufficiency of ß2AR agonism in airway epithelial and smooth muscle cells in mediating allergic lung inflammation, mucin production, and AHR. Aim 2 will employ similar genetic approaches to establish the roles of ß2AR-mediated PKA- and arrestin-dependent signaling in regulating the asthma phenotype in vivo, as well as molecular biology approaches to characterize PKA- and arrestin-dependent regulation of mucin production and inflammatory agents in both human and murine airway epithelial cells. Aim 3 will utilize pharmacological and genetic approaches, and determine the biased signaling properties of approved and new ß2AR ligands to conclusively establish the roles for PKA and arrestin signaling in regulating the asthma phenotype. Collectively, these studies will significantly advance the fields of asthma biology and asthma pharmacology by identifying a fundamental pathogenic signaling mechanism involved in allergic lung inflammation, and by characterizing the optimal ß2AR ligands used to manage asthmatics.