Optimizing Beta-Adrenoceptor Signaling Bias in Asthma

描述（由申请人提供）：β-2-肾上腺素受体（β 2 AR）的激动剂，通常称为β-激动剂，已经成为哮喘治疗的基础将近半个世纪.然而，尽管它们的效用，β-受体激动剂用于哮喘管理具有问题，包括功能性快速耐受、哮喘控制恶化和死亡率问题。无法理解为什么存在这样的问题，以及未能显著改善β 2AR药理学，这反映在20多年来NIH计划宣布需要更安全、更有效的哮喘治疗替代品。我们最近发表和未发表的研究提供了令人信服的见解，为什么β-受体激动剂是有问题的，同时提供了一个解决方案，他们的临床应用。我们的数据有力地表明，β 2 AR激动作用在变应性肺炎和相关气道高反应性（AHR）的发展中起允许作用，并且内源性（肾上腺素）以及外源性β 2 AR激动剂引起促进哮喘表型的致病机制。新的数据表明，β 2 AR β 2在气道细胞中定性地区分信号传导途径：由β-arrestin 2介导的促炎信号传导，以及由Gs蛋白介导的抗炎和支气管保护信号传导。我们建议通过建立这些β 2 AR信号通路在调节哮喘表型中的细胞特异性作用，并从当前和新产生的β 2 AR配体或调节剂中鉴定具有偏置信号特性的那些，这些偏置信号特性在其通过抑制蛋白拮抗致病性β 2 AR信号传导的能力方面是最佳的，但促进有益的G蛋白信号传导，来解决哮喘“β 2 AR悖论”。我们将采用许多系统，包括细胞、组织和体内模型，来检验中心假设，即气道上皮中通过β-arrestin 2的β 2AR信号传导对变应原诱导的哮喘表型至关重要，并且拮抗β-arrestin 2信号传导同时使Gs蛋白信号传导成为可能的偏向β 2AR配体或调节剂在哮喘治疗中更有效。目的1将采用遗传策略，使细胞特异性β 2 AR基因消融或表达，以建立气道上皮和平滑肌细胞中β 2 AR激动作用在介导变应性肺炎、粘蛋白产生和AHR中的需要和充分性。目的2将采用类似的遗传学方法来确定β 2 AR介导的PKA和抑制蛋白依赖性信号在体内调节哮喘表型中的作用，以及分子生物学方法来表征PKA和抑制蛋白依赖性调节人和小鼠气道上皮细胞中粘蛋白产生和炎症因子。目的3将利用药理学和遗传学方法，并确定批准的和新的β 2 AR配体的偏倚信号传导特性，以最终确定PKA和arrestin信号传导在调节哮喘表型中的作用。总的来说，这些研究将通过鉴定参与过敏性肺部炎症的基本致病信号传导机制，以及通过表征用于管理哮喘的最佳β 2 AR配体，显著推进哮喘生物学和哮喘药理学领域。

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 Our recent published and unpublished studies provide compelling insight into why ß-agonists are problematic while offering a solution to their clinical application.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.