BETA ADRENERGIC MODULATION OF AIRWAY FUNCTION IN ASTHMA

β 肾上腺素能调节哮喘气道功能

• 批准号: 3365085
• 负责人: CAROL A HIRSHMAN
• 金额: $ 29.66万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-09-30 至 1995-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3365085
• 关键词: DNA; G protein; RNA; adenylate cyclase; asthma; beta adrenergic agent; beta adrenergic receptor; biological signal transduction; corticosteroid receptors; disease /disorder model; dogs; gel electrophoresis; gene deletion mutation; genetic regulation; glucocorticoids; histamine; human subject; human tissue; molecular biology; molecular cloning; muscarinic receptor; nucleic acid hybridization; nucleic acid probes; phospholipase C; point mutation; polymerase chain reaction; protein kinase A; receptor binding; receptor coupling; respiratory function; respiratory muscles; second messengers; smooth muscle

Since Szentivanyi proposed in 1968 that asthma might be due to an inherited or acquired deficit in beta-adrenergic function, much research has focused on the beta adrenergic receptor (beta2AR) and the beta-adrenergic cascade. However, 22 years later the question is still unsettled, as research has focused largely on the leukocyte, which is a poor model of human asthma. Studies of bronchial muscle tissue from animal models of asthma and from human asthmatics obtained either at surgery or at autopsy show a very definite deficit in beta-adrenergic function. However, the intracellular events underlying this beta adrenergic deficit is unknown. We have a well characterized animal model of airway hyperresponsiveness that clearly demonstrates decreased sensitivity to beta adrenergic agonists in vivo and in vitro. We have access to human asthmatic airway tissue which shows a similar defect, and we have access to a population of well characterized human asthmatics. We hypothesize that the decreased sensitivity to beta adrenergic agonists relates to a specific defect either in generation or degradation of intracellular cAMP. To identify directly the intracellular lesion we plan to measure numbers and affinities of beta2AR and muscarinic receptor subtypes, second messengers, adenylyl cyclase and phospholipase C and their regulation by the signal transducing G proteins in the airway smooth muscle of the basenji-greyhound dog, and to understand the mechanism by which glucocorticoids modify the response. We will apply the insights gained in the animal model to similar studies with available human airway tissues. In addition, we will determine whether genetic linkage exists between inheritance of the asthma phenotype and specific beta2AR gene alleles or other genes (e.g. G proteins) involved in beta adrenergic functions, and characterize specific mutations by nucleotide sequencing. The reduced in vitro sensitivity to beta agonists in our animal model provides us with the unique opportunity of easy accessibility to large quantities of airway smooth muscle for our in vitro studies from two allergic lines of animals - one hyperresponsive and one normoresponsive, allowing us to focus on the deficit leading to hyperresponsiveness, not confounded by allergy or drug therapy. We also have the unique ability to control and manipulate environmental and genetic influences. Results from the proposed work will provide new information about the intracellular mechanisms which regulate airway smooth muscle tone in this model. We will apply this information to the limited tissues available in humans and to human asthmatics using a candidate gene approach. We think this three pronged approach, using leukocyte DNA, human airway tissue and tissue from the BG dog model of airway hyperresponsiveness will yield important new insights. Since glucocorticoids and beta agonists remain the mainstay of asthma treatment, it is critical to elucidate the molecular mechanism of reduced beta agonist sensitivity and its modulation by glucocorticoids in patients and animal models of asthma.

自从Szentivanyi于1968年提议哮喘以来 或获得β-肾上腺素能力的赤字，很多研究集中在 在β肾上腺素能受体（beta2AR）和β-肾上腺素能级联反应上。 但是，22年后，由于研究的问题，这个问题仍然没有解决 主要专注于白细胞，这是人类哮喘的贫困模型。 研究哮喘动物模型的支气管肌肉组织 在手术或尸检时获得的人类哮喘患者表明 β-肾上腺素能的明确赤字。 但是，细胞内 这种Beta肾上腺素能赤字为基础的事件尚不清楚。 我们有一个井 气道高反应性的动物模型显然 证明对体内β肾上腺素能激动剂的敏感性降低 体外。 我们可以使用人类哮喘性气道组织 类似的缺陷，我们可以访问特征良好的人群 人类哮喘患者。 我们假设对β的敏感性降低 肾上腺素能激动剂涉及一代中的特定缺陷或 细胞内营地的退化。 直接识别细胞内 病变我们计划测量β2AR和毒蕈碱的数字和亲和力 受体亚型，第二使者，腺苷酸环化酶和磷脂酶C 以及它们通过信号转导G蛋白的调节 Basenji-Greyhound狗的平滑肌，并了解机制 糖皮质激素通过其中改变反应。 我们将应用见解 在动物模型中获得了与可用人类气道的类似研究 组织。 此外，我们将确定是否存在遗传联系 在哮喘表型的遗传和特定β2AR基因之间 等位基因或其他基因（例如G蛋白）参与β肾上腺素能 功能，并通过核苷酸测序表征特定突变。 我们动物模型中对β激动剂的体外敏感性降低 为我们提供了轻松访问大型的独特机会 我们的体外研究的气道平滑肌数量 动物的过敏线 - 一种高反应和一种不良措施， 允许我们专注于导致过度反应性的赤字，而不是 被过敏或药物疗法混淆。 我们也有独特的能力 控制和操纵环境和遗传影响。 结果 拟议的工作将提供有关细胞内的新信息 调节此模型中气道平滑肌音调的机制。 我们将 将此信息应用于人类可用的有限组织和 人类哮喘患者使用候选基因方法。 我们认为这三个 使用白细胞DNA，人类气道组织和组织 BG气道高应答的模型将产生重要的新 见解。 由于糖皮质激素和β激动剂仍然是 哮喘治疗，阐明分子机制至关重要 降低了β激动剂敏感性及其通过糖皮质激素的调节 哮喘的患者和动物模型。