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: 7109283
• 负责人: Phillip H Factor
• 金额: $ 35.92万
• 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/7109283
• 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（由申请方提供）：众所周知，气道平滑肌（ASM）细胞上β 2-肾上腺素能受体（（β 2AR））的激活可降低支气管张力。 不太了解的是支气管上皮细胞具有比ASM更高的β 2 AR密度，并且对原代和永生化气道上皮细胞的体外研究已经鉴定了能够引起ASM松弛的cAMP敏感性机制。 相反，使用上皮完整和裸露气管插管的离体研究表明，上皮通过充当限制β-激动剂进入ASM的扩散屏障来阻碍β-激动剂介导的ASM松弛（2AR）。 因此，关于上皮β 2 AR的基于细胞的体外实验的结果尚未转化为动物模型中的生理学相关机制，也没有数据表明上皮β 2 AR参与哮喘患者支气管张力的调节。 对上皮β 2 AR缺乏共识导致哮喘的一种模式，即默认β受体激动剂仅通过激活ASM上的β 2 AR影响支气管扩张。 我们发现令人惊讶的是，哮喘的一种关键治疗方式，吸入性β受体激动剂的作用部位和机制尚不确定。 上皮β 2 AR缺乏明确的作用，这是由于先前的体内研究无法将上皮β 2 AR的生理作用与ASM β 2 AR的直接支气管扩张作用分开。 我们相信，上皮β 2 AR的作用的解决可以提高我们对反应性气道疾病的理解，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的实验，我们观察到，在正常小鼠的气道上皮细胞中的人β 2ARs cDNA的过表达赋予大量的保护，从乙酰甲胆碱诱导的支气管痉挛。 我们还注意到，上皮β 2 AR的缺乏或抑制显著增加小鼠的气道反应性。 这些观察结果使我们假设：支气管上皮β 2 AR参与气道反应性的调节。 关于支气管上皮β 2 AR缺乏共识，我们正在进行的肺泡β 2 AR研究导致我们对气道上皮β 2 AR提出了几个问题：1）气道上皮β 2 AR是否调节正常小鼠的气道反应性？ 2)激动剂诱导的上皮β 2 AR受体脱敏是否影响气道反应性？支气管肺炎是否影响上皮β 2 AR的功能？ 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，以帮助修复关于上皮β 2AR作用的长期知识空白。 这些研究将告诉我们β 2 AR如何与儿茶酚胺相互作用，如果它们影响气道反应性，以及它们是否受到支气管肺炎炎症的影响。 我们认为，上皮β 2 AR的重要作用的确认可以证明上皮细胞特异性的，基于基因的治疗，积极调节上皮β受体功能，产生持续的保护，从支气管痉挛的挑战的发展。 这种疗法可以显着改善哮喘患者的健康状况。