Role of titin in the pathophysiology of diaphragm weakness during mechanical ventilation

肌联蛋白在机械通气期间膈肌无力病理生理学中的作用

• 批准号: 9816870
• 负责人: Coen Ottenheijm
• 金额: $ 50.69万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9816870
• 关键词: Affect; Animal Model; Atrophic; Attenuated; Autopsy; Back; Binding Proteins; Biomechanics; Biopsy; C10; Critical Illness; Data; Denervation; Development; Disease; Elasticity; Environmental air flow; Failure; Fiber; Financial Hardship; Functional disorder; Genetic; Genetic Engineering; Goals; Growth; Harvest; Health; Hot Spot; Hour; Hypertrophy; Individual; Knockout Mice; Laboratories; Laparotomy; Lead; Length; Link; Longitudinal Studies; Lung; Mechanical Stress; Mechanical ventilation; Mechanics; Microscopy; Modeling; Molecular; Morbidity - disease rate; Muscle; Muscle Proteins; Oxygen; Pathway interactions; Patients; Periodicity; Positive-Pressure Respiration; Progress Reports; Property; Proteins; Proteomics; RNA Recognition Motif; RNA Splicing; Research; Resolution; Respiration; Respiratory Diaphragm; Respiratory Muscles; Role; Sarcomeres; Series; Signal Pathway; Signal Transduction; Signaling Protein; Stretching; Testing; Therapeutic; Vision; Weaning; Work; absorption; base; clinically relevant; connectin; cost; in vivo; innovation; insight; interdisciplinary approach; mechanical load; mechanotransduction; mortality; mouse model; novel; programs; protein degradation; response; tool; transcriptome sequencing; transcriptomics; uptake

7. SUMMARY. The long-term goal of this proposal is to gain detailed understanding of how the diaphragm – the main muscle of respiration – rapidly weakens in response to mechanical unloading, and of the mechanisms whereby the giant elastic protein titin influences this response. The diaphragm is a unique muscle in that it is constantly subjected to mechanical loading. Recent work suggests that diaphragm strength is remarkably sensitive to mechanical unloading, as occurs during mechanical ventilation in the ICU. How unloading affects diaphragm strength is poorly understood. Increasing this understanding is critically important: within hours, diaphragm unloading during mechanical ventilation causes diaphragm weakness in critically ill patients, contributing to weaning failure. The search for the molecular triggers for the development of diaphragm weakness is ongoing. The potential role of mechanosensor proteins, that link unloading to protein turnover, is under-explored but an exciting concept that needs to be studied. A candidate mechanosensor is titin, a giant elastic protein that has been suggested to sense mechanical stress and link this to trophic signalling pathways. This proposal’s aims to understand mechanosensing in the diaphragm in health and disease, and the role of titin therein. Aim 1 will critically test how titin affects muscle trophicity. We will use unilateral diaphragm denervation (UDD). A property that can be observed during UDD is an initial hypertrophy response and we have shown that this hypertrophy of the denervated hemidiaphragm is caused by cyclic passive stretch of diaphragm fibers, and that titin’s elastic properties dictate the magnitude of the response. In this Aim we will identify the titin-based signalling pathways involved. Aim 2 determines the role of titin’s elasticity in PEEP ventilation-induced longitudinal diaphragm atrophy. This work builds on our recent finding that mechanical ventilation with PEEP, which unloads the diaphragm at a shortened length, causes longitudinal atrophy of fibers. Pilot data suggest that titin-based mechanosensing modulates this response. To critically test the role of titin, we will study the effect of PEEP ventilation on longitudinal atrophy in two titin KO mouse models: one with increased titin stiffness and one with lowered. In Aim 3 we will use unique diaphragm biopsies of critically ill patients to validate the findings from aim 1&2 and study whether titin-based mechanosensing contributes to diaphragm weakness. Up/downregulated titin binding proteins will be determined, the significance of which is tested in mouse models through genetic deletion. The innovation of this proposal lies in the novel research foci with innovative guiding hypotheses, its innovative mouse models, unique diaphragm biopsies from mechanically ventilated critically ill patients, and its novel experimental tools. The proposal’s integrative approach is expected to lead to a significant step forward in our understanding of diaphragm function and the role of titin therein.

7。摘要。 该提议的长期目标是详细了解隔膜如何 - 主要肌肉 呼吸 - 响应机械卸载和机制而迅速削弱 巨型弹性蛋白滴定会影响这种反应。 隔膜是一种独特的肌肉，因为它不断受到机械负荷的影响。最近的工作 表明隔膜强度对机械卸载非常敏感，就像在 ICU中的机械通气。卸载如何影响隔膜强度的理解很少。增加 这种理解至关重要：在数小时内，机械通气过程中的隔膜卸载 导致重症患者的隔膜无力，导致断奶衰竭。搜索 分子触发因膜片弱点而发展。潜在的作用 机械传感器蛋白（将链接到蛋白质转换的链接链接）的探索不足，但令人兴奋的概念 需要研究。候选机械方法是Titin，这是一种巨大的弹性蛋白 感知机械应力并将其与营养信号通路联系起来。该提议的目的是了解 隔膜的机械感应在健康和疾病中以及其中的Titin的作用。 AIM 1将严格测试钛对肌肉营养的影响。我们将使用单侧隔膜神经支配 （UDD）。在UDD期间可以观察到的特性是最初的肥大反应，我们已经表明 永无止境的半脑肥大是由隔膜纤维的循环被动拉伸引起的，而是引起的 Titin的弹性特性决定了响应的幅度。在此目标中，我们将确定基于滴定的 信号通路涉及。 AIM 2确定Titin在窥视通风引起的弹性中的作用 纵向隔膜萎缩。这项工作以我们最近的发现为基础 PEEP以缩短的长度卸下膜片，会导致纤维的纵向萎缩。试点数据 表明基于TITIN的机制是这种反应。为了批判性测试钛的作用，我们将 研究窥视通风对两种Titin KO小鼠模型中纵向萎缩的影响：一种 滴定刚度，一个刚度降低。在AIM 3中，我们将使用独特的膜片活检 患者验证AIM 1和2的发现，并研究基于TITIN的机制是否有助于 膜片无力。将确定向上/下调的滴定蛋白结合蛋白，其意义是 通过遗传缺失在小鼠模型中测试。 该提案的创新在于新颖的研究重点，并具有创新的指导假设，其创新性 小鼠模型，来自机械通风病重病患者的独特隔膜活检及其新颖 实验工具。该提案的综合方法有望导致迈出的重要一步 我们对隔膜功能的理解及其在其中的作用。