Mechanisms of Anesthetic Effects on Tachykinin Induced Airway Tone

 描述(由申请人提供)：哮喘是一种慢性呼吸道炎症性疾病，存在于8%的美国人口中。这与数十亿美元的医疗车费用有关，而哮喘控制不力是导致旷课的主要医疗原因。尽管研究在阐明哮喘的潜在机制方面取得了很大进展，但几十年来一直没有新的治疗方法，导致高达40%的哮喘患者出现不完全控制的症状。最广泛使用的哮喘药物的成分，长效吸入型β-激动剂，与哮喘死亡率的增加有关，目前正在接受FDA授权的长期安全性审查。本实验室发现了GABAA受体在气道平滑肌上的表达，并证实激活这些经典的神经元受体可以起到松弛气道的作用。然后，我们证明了多个肺细胞中存在一个完整的GABA能系统，包括离子型GABAA受体、代谢型GABAB受体、合成GABA(谷氨酸脱羧酶)的酶和GABA转运体。松弛气道平滑肌的GABA A受体含有α4或α5亚单位。值得注意的是，我们现在已经发现，介导过敏性肺部炎症的关键炎症细胞也表达含有α4亚单位的GABA通道。在目前的提案中，我们继续与一位领先的GABA AA配体药物化学家合作，以确定能够激活含有α4或α5亚单位的GABA AA通道的新型配体，这种通道既可以松弛气道平滑肌，又可以抑制肺部炎症--哮喘的两个关键病理成分。我们寻求合成新型配体的衍生物，通过吸入不会渗透到中枢神经系统的方式将其输送到小鼠哮喘模型中，以避免不良影响。在目标1中，我们将GABAAα4或α5配体的气雾剂输送给哮喘小鼠，同时用收缩介质挑战它们的呼吸道，并测量由此产生的血浆、肺、肝脏和脑中的组织浓度。在目标2中，我们将测试 这些GABAA配体能够松弛分离的人体呼吸道平滑肌条，并确定它们对膜电位的控制与控制收缩的细胞内信号事件之间的联系。在目标3中，我们将利用缺乏GABAAα4亚单位的小鼠来证明GABAAα4受体在过敏性肺部炎症中的关键作用。我们将展示GAAAα4受体在调节膜电位和淋巴细胞激活和增殖中的作用。这些方法提供了一种根本性的新疗法、一种转化性治疗方法和一种针对哮喘两个关键成分的新范式：炎症和气道平滑肌高反应性。

 DESCRIPTION (provided by applicant): Asthma is a chronic inflammatory disease of the airways present in 8% of the US population. It is associated with billions of dollars in health car costs and poorly controlled asthma is the leading medical cause of school absenteeism. Although research has made great strides in elucidating the underlying mechanisms involved in asthma, there have been no new classes of therapeutics for many decades resulting in up to 40% of asthmatics having incompletely controlled symptoms. Components of the most widely used asthma medications, long acting inhaled beta agonists, are associated with an increased death rate from asthma and are currently under FDA-mandated review for long term safety. Our laboratory discovered the expression of GABAA receptors on airway smooth muscle and demonstrated that activation of these classic neuronal receptors could relax airway smooth muscle. We then demonstrated that a complete GABAergic system existed in multiple lung cells including ionotropic GABAA receptors, metabotropic GABAB receptors, the enzymes that synthesize GABA (glutamic acid decarboxylase) and GABA transporters. The GABAA receptors that relax airway smooth muscle contain either an α4 or α5 subunit. Remarkably we have now discovered that key inflammatory cells that mediate allergic lung inflammation also express α4 subunit-containing GABAA channels. In the current proposal we continue our collaboration with a leading GABAA ligand medicinal chemist to identify novel ligands that activate α4 or α5 subunit-containing GABAA channels that will both relax airway smooth muscle and inhibit lung inflammation-the two key pathologic components of asthma. We seek to synthesize derivatives of novel ligands that will be delivered to a murine asthma model by inhalation that would not penetrate the CNS to avoid undesired effects. In aim 1 we will deliver aerosols of GABAA α4 or α5 ligands to asthmatic mice while challenging their airways with a contractile mediator and measure resulting tissue concentrations in plasma, lung, liver and brain. In aim 2 we will test the ability of these GABAA ligands to relax isolated human airway smooth muscle strips and determine the link between their control of membrane potential and intracellular signaling events that control contraction. In aim 3 we will utilize mice lacking GABAA α4 subunits to demonstrate the critical role of GABAA α4 receptors in allergic lung inflammation. We will demonstrate the role of GABAA α4 receptors in regulating membrane potential and lymphocyte activation and proliferation. These approaches offer a radical new therapy, a translational therapeutic approach and a novel paradigm for targeting two key components of asthma; inflammation and airway smooth muscle hyperresponsiveness.