Role of airway epithelial Beta2-adrenergic receptors

气道上皮β2-肾上腺素能受体的作用

• 批准号: 6686968
• 负责人: Phillip H Factor
• 金额: $ 36.79万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-18 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6686968
• 关键词: allergens; beta adrenergic receptor; biological models; bronchus; catecholamines; cell membrane; chemosensitizing agent; gene deletion mutation; immunocytochemistry; inflammation; laboratory mouse; lung disorder; model design /development; nitric oxide; phosphorylation; polymerase chain reaction; prostaglandin E; protein structure function; receptor expression; respiratory airway pressure; respiratory epithelium; respiratory function; transfection

DESCRIPTION (provided by applicant): It is well established that activation of beta2-adrenergic receptors ((beta2AR) on airway smooth muscle (ASM) cells decreases bronchomotor tone. Less well appreciated is that bronchial epithelial cells have a higher density of (beta2ARs than do ASM and that in vitro studies of primary and immortalized airway epithelial cells have identified cAMP sensitive mechanisms capable of causing ASM relaxation. Conversely, ex vivo studies using epithelium intact and denuded tracheal tubes suggest that the epithelium impedes beta-agonist mediated ASM relaxation by serving as diffusion barrier that limits access of beta-agonists to ASM (2ARs. Thus, the results of cell-based in vitro experiments regarding epithelial (2ARs have not translated into physiologically relevant mechanisms in animal models nor are there data to suggest that epithelial beta2ARs participate in the regulation of bronchomotor tone in humans with asthma. This lack of consensus about epithelial beta2ARs has resulted in a paradigm of asthma that assumes, by default, that beta-agonists affect bronchodilation solely via activation of beta2ARs on ASM. We find it striking that the location and mechanism of action of a key therapeutic modality for asthma, inhaled beta-agonists, are uncertain. The absence of a defined role for epithelial beta2ARs, stems from the inability of prior in vivo studies to separate the physiologic effects of epithelial (beta2ARs from the direct bronchodilating effects of ASM beta2ARs. We believe that resolution of the role of epithelial beta2ARs could improve our understanding of reactive airway disease and better define how beta-agonists interacts with the airway to reduce airway reactivity. We have conducted preliminary experiments in which we observed that overexpression of a human beta2ARs cDNA in the airway epithelium of normal mice confers substantial protection from methacholine-induced bronchospasm. We also noted that the absence or inhibition of epithelial beta2ARs significantly increases airway reactivity in mice. These observations have caused us to hypothesize that: Bronchial epithelial beta2ARs participate in the regulation of airway reactivity. The lack of consensus regarding bronchial epithelial (2ARs and our ongoing studies of alveolar beta2ARs have led us to several questions regarding airway epithelial beta2ARs: 1) Do airway epithelial (2ARs regulate airway reactivity in normal mice? 2) Does agonist-induced receptor desensitization of epithelial beta2ARs affect airway reactivity? and 3) Does bronchopulmonary inflammation affect epithelial beta2ARs function? To address our hypothesis and questions we have structured 3 inter-related scientific aims that merge molecular tools with in vivo models to help repair the long-standing gap in knowledge regarding the role of epithelial beta2ARs. These studies will tell us how beta2ARs interact with catecholamines, if they affect airway reactivity, and whether they are affected by bronchopulmonary inflammation. We believe that confirmation of an important role for epithelial beta2ARs could justify the development of epithelial cell specific, gene-based, therapies that positively modulate epithelial beta-receptor function to produce sustained protection from bronchospastic challenges. Such therapies could significantly improve the health of patients with asthma.

描述（由申请人提供）：众所周知，气道平滑肌（ASM）细胞上的β2-肾上腺素受体（（β2AR）的激活会降低支气管运动张力。不太为人所知的是，支气管上皮细胞具有比支气管上皮细胞更高的（β2AR）密度。进行 ASM，并且对原代和永生化气道上皮细胞的体外研究已经确定了能够引起 ASM 松弛的 cAMP 敏感机制，相反，使用完整上皮的离体研究。和裸露的气管导管表明上皮通过充当限制 β 激动剂进入 ASM（2AR）的扩散屏障来阻碍 β 激动剂介导的 ASM 松弛。因此，关于上皮（2AR）的基于细胞的体外实验结果尚未翻译目前还没有研究动物模型中的生理相关机制，也没有数据表明上皮 β2AR 参与哮喘患者支气管运动张力的调节。导致了一种哮喘范例，默认情况下，β-受体激动剂仅通过激活 ASM 上的 β2AR 来影响支气管扩张。 令人震惊的是，哮喘关键治疗方式吸入β受体激动剂的作用位置和作用机制尚不确定。 上皮β2AR的作用缺乏明确的原因是之前的体内研究无法将上皮β2AR的生理作用与ASMβ2AR的直接支气管扩张作用分开。我们相信，上皮β2AR的作用的解决可以改善我们的研究。了解反应性气道疾病并更好地定义β受体激动剂如何与气道相互作用以降低气道反应性我们已经进行了初步实验，在这些实验中我们观察到人类的过度表达。正常小鼠气道上皮中的 β2AR cDNA 对乙酰甲胆碱诱导的支气管痉挛具有显着的保护作用。我们还注意到，上皮 β2AR 的缺失或抑制显着增加了小鼠的气道反应性。这些观察结果使我们推测： 支气管上皮 β2AR 参与了支气管痉挛。气道反应性的调节。 关于支气管上皮（2AR）缺乏共识以及我们正在进行的肺泡β2AR研究使我们对气道上皮β2AR的几个问题产生了疑问：1）气道上皮（2AR）是否调节正常小鼠的气道反应性？2）激动剂诱导的受体脱敏是否上皮β2AR影响气道反应性？ 3) 支气管肺炎症是否影响上皮β2AR 功能？ 为了解决我们的假设和问题，我们构建了 3 个相互关联的科学目标，将分子工具与体内模型相结合，以帮助修复有关上皮 β2AR 作用的长期存在的知识空白。 这些研究将告诉我们 beta2AR 如何与儿茶酚胺相互作用，它们是否影响气道反应性，以及它们是否受到支气管肺炎症的影响。 我们相信，确认上皮β2AR的重要作用可以证明开发上皮细胞特异性、基于基因的疗法是合理的，这些疗法可以积极调节上皮β受体功能，从而产生针对支气管痉挛挑战的持续保护。 这种疗法可以显着改善哮喘患者的健康。