FACTORS DETERMINING HYPERREPSONSIVENESS FOR INTACT AIRWAYS

决定完整气道高反应性的因素

基本信息

批准号：
8435547
负责人：
KENNETH R LUTCHEN
金额：
$ 44.55万
依托单位：
BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-04-01 至 2016-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8435547
关键词：
Actins Address Affect Agonist Asthma Attenuated Biochemical Biology Biophysics Breathing Bronchodilator Agents Caliber Cell Culture Techniques Cell physiology Characteristics Complex Contracts Data Digestion Dimensions Dose Ensure Equilibrium Extracellular Matrix F-Actin Fiber Frequencies Future G Actin Imaging Techniques In Situ Inflammation Intervention Length Link Lung MYLK gene Measurement Measures Mechanics Microscopic Molecular Molecular Target Muscle Contraction Myosin ATPase Phenotype Physiological Physiology Play Process Property Research Design Role Smooth Muscle Smooth Muscle Myocytes Stretching Structure Symptoms System Testing Thick Time Translating Ultrasonography Variant Work airway hyperresponsiveness asthmatic airway asthmatic patient base constriction extracellular in vivo muscle stress neglect novel polymerization pressure prevent public health relevance respiratory smooth muscle response therapy design

项目摘要

DESCRIPTION (provided by applicant): What role does the airway smooth muscle (ASM) play in producing the asthmatic phenotype of airway hyperresponsiveness (AHR)? A plethora of studies confirm that length oscillations of isolated ASM can modulate and mitigate its net response to an agonist. Two related hypotheses at the molecular level have emerged to explain isolated ASM findings, namely that the normal responses to stretch arise from perturbed equilibrium of actin-myosin crossbridges and/or cytoskeletal fluidization of the ASM cell. However, a gap exists in bridging molecular level hypotheses from isolated ASM studies to actual AHR for an intact airway as it constricts in three-dimensions. Many important interactions occur within an intact airway's extracellular matrix (ECM) that can impact ASM contractility and hence airway constriction in situ. We have developed a unique ultrasound imaging-based system to dynamically probe intact airways. Here, the ASM is in its natural geometric state embedded within the airway wall's ECM, and the airway is exposed to physiologically relevant transmural pressure (Ptm) fluctuations. This system allows for concurrent real-time measurements of luminal diameter and wall thickness over the full length of an intact airway during any physiological Ptm fluctuations and/or induced constriction. These measurements allow us to calculate an extensive set of macroscopic mechanical properties of the intact airway system. We can also apply biochemical and histological approaches to examine the microscopic properties of the ASM cells and ECM fibers. Jointly, these preliminary data suggest in intact airways, Ptm variations may invoke cellular mechanisms of crossbridge detachment and/or actin de-polymerization (perhaps associated with cytoskeletal fluidization) but without necessarily resulting in airway dilation. Based on this, we propose to test the following hypothesis: HYPOTHESIS: In the intact airway system, transmural pressure variations during physiological breathing are insufficient to attenuate responsiveness because the mechanical properties of the airway wall's ECM prevent the effective disruption of ASM crossbridge cycling and actin polymerization. Corollary: In vivo, AHR in asthma cannot be explained simply as the inability to properly strain the ASM. Aim 1: To determine the contribution of dynamic Ptm variations to the responsiveness of intact airways. Aim 2: To determine the intra- and extracellular consequences of dynamic Ptm variations on intact airways. Aim 3: To determine how airway wall structural constituents and ASM cellular processes impact the responsiveness of intact airways exposed to dynamic transmural pressure variations. This proposal will address the crucial questions of if and how mechanisms associated with ASM contraction in isolation are relevant in a dynamic and complex intact airway system and, hence, relevant in modulating airway responsiveness. Our proposal represents an essential step to understand mechanisms relevant to airway hyperresponsiveness.

描述（由申请人提供）：气道平滑肌（ASM）在产生气道高反应性（AHR）的哮喘表型中起什么作用？大量的研究证实，分离的ASM的长度振荡可以调节并减轻其对激动剂的净响应。已经出现了两个相关的假设，以解释分离的ASM发现，即伸展的正常反应是由于肌动蛋白 - 肌球蛋白跨桥的扰动平衡和/或ASM细胞的细胞骨架流体的扰动。然而，在桥接分子水平的假设中存在一个差距，从孤立的ASM研究到实际的AHR，对于完整的气道，它在三维中的收缩。完整气道的细胞外基质（ECM）发生，可能会影响ASM收缩性，从而原位气道收缩。我们已经开发了一种独特的基于超声成像的系统，以动态探测完整的气道。在这里，ASM处于嵌入气道壁ECM中的自然几何状态，气道暴露于生理相关的透射压力（PTM）波动。该系统允许在任何生理PTM波动和/或诱导的收缩期间，在完整气道的整个长度上同时实时测量腔直径和壁厚。这些测量值使我们能够计算完整气道系统的一组宏观机械性能。我们还可以应用生化和组织学方法来检查ASM细胞和ECM纤维的微观特性。共同的这些初步数据表明，在完整的气道中，PTM的变化可能会引起Crossbridge脱离和/或肌动蛋白脱聚合的细胞机制（可能与细胞骨架流体有关），但没有必要导致空中扩张。基于此，我们建议检验以下假设：假设：在完整的气道系统中，生理呼吸过程中的透明压力变化不足以降低反应性，因为气道壁ECM的机械性能有效地破坏了ASM Crossbridge Cyccling和actacin聚合的有效中断。推论：在体内，哮喘中的AHR不能简单地解释为无法正确劳累ASM。目标1：确定动态PTM变化对完整气道响应的贡献。目标2：确定完整气道动态PTM变化的细胞内和细胞外后果。目标3：确定气道壁结构成分和ASM细胞过程如何影响暴露于动态透壁压力变化的完整气道的响应能力。该建议将解决与动态且复杂的完整气道系统相关的与ASM收缩相关的机制的关键问题，因此与调节气道响应能力有关。我们的建议是了解与气道高反应性相关的机制的重要步骤。