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 这项提案的长期目标是详细了解横隔膜-主要肌肉 呼吸-迅速减弱，以响应机械卸载，和机制， 巨大的弹性蛋白肌联蛋白影响这种反应。 横膈膜是一种独特的肌肉，因为它不断受到机械负荷。最近的工作 表明，隔膜强度是非常敏感的机械卸载，如发生在 重症监护室的机械通气卸载如何影响隔膜强度知之甚少。增加 这一理解至关重要：在数小时内，机械通气期间隔膜卸载 导致重症患者膈肌无力，导致脱机失败。的搜寻工作 引发横膈膜无力的分子因素仍在继续的潜在作用 机械传感器蛋白质，连接卸载蛋白质周转，是一个令人兴奋的概念，但尚未开发 这需要研究。一个候选的机械传感器是肌联蛋白，一种巨大的弹性蛋白， 来感知机械压力并将其与营养信号通路联系起来。这项提案的目的是了解 在健康和疾病中横膈膜中的机械感测，以及肌联蛋白在其中的作用。 目的1将严格测试肌联蛋白如何影响肌肉营养。我们将采用单侧膈肌去神经术 （UDD）。在UDD过程中可以观察到的一个特性是初始肥大反应，我们已经证明， 这种去神经支配的半侧膈肌的肥大是由膈肌纤维的周期性被动拉伸引起的， 肌联蛋白的弹性决定了反应的大小。在这个目标中，我们将确定基于肌联蛋白的 参与的信号通路。目的2确定肌联蛋白弹性在PEEP通气诱导中的作用 纵膈萎缩这项工作建立在我们最近的发现，机械通气与 呼气末正压（PEEP）使横膈膜的负荷减少，导致纤维的纵向萎缩。导频数据 提示基于肌联蛋白的机械感测调节这种反应。为了严格测试肌联蛋白的作用，我们将 在两种titin KO小鼠模型中研究PEEP通气对纵向萎缩的影响：一种是增加 titin刚度和一个降低。在目标3中，我们将使用独特的重症膈肌活检， 患者验证aim 1&2的发现，并研究基于肌联蛋白的机械传感是否有助于 横膈膜无力将确定上调/下调的肌联蛋白结合蛋白，其意义在于 在小鼠模型中通过基因删除进行测试。 该方案的创新之处在于研究重点新颖，指导假设创新， 小鼠模型，从机械通气的重症患者独特的横膈膜活检，及其新的 实验工具该提案的综合办法预计将导致在以下方面向前迈出重要一步： 我们对横膈膜功能和肌联蛋白在其中的作用的理解。