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

基本信息

批准号：
10252782
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
项目类别：
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/10252782
关键词：
Affect Animal Model Atrophic Attenuated Autopsy Back Binding Proteins Biomechanics Biopsy C10 Critical Illness Data Denervation Development Disease Elasticity 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 ventilation

项目摘要

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.总结。该提案的长期目标是详细了解隔膜（主要肌肉）如何呼吸作用——对机械卸载的反应迅速减弱，以及呼吸作用的机制巨大的弹性蛋白肌联蛋白影响这种反应。隔膜是一种独特的肌肉，因为它不断承受机械负荷。表明隔膜强度对机械卸载异常敏感，如在 ICU 中的机械通气如何影响膈肌强度尚不清楚。这种理解至关重要：在机械通气过程中，数小时内隔膜就会卸载导致危重患者膈肌无力，导致脱机失败。分子触发因素对膈肌无力发展的潜在作用正在进行中。将卸载与蛋白质周转联系起来的机械传感器蛋白质尚未得到充分探索，但却是一个令人兴奋的概念需要研究的候选机械传感器是肌联蛋白，这是一种巨大的弹性蛋白。感知机械压力并将其与营养信号传导途径联系起来。膈肌在健康和疾病中的机械传感，以及肌动蛋白在其中的作用。目标 1 将严格测试肌动蛋白如何影响肌肉营养性，我们将使用单侧膈肌去神经术。 (UDD) 在 UDD 期间可以观察到的一个特性是初始肥大反应，我们已经证明了这一点。这种去神经支配的半膈肌肥大是由膈肌纤维的周期性被动拉伸引起的，并且肌动蛋白的弹性特性决定了响应的大小。在这个目标中，我们将识别基于肌动蛋白的结构。目标 2 确定肌动蛋白弹性在 PEEP 通气诱导中的作用。这项工作建立在我们最近发现机械通气与纵向膈肌萎缩的基础上。 PEEP 以缩短的长度卸载隔膜，导致导频数据纵向萎缩。建议基于肌动蛋白的机械传感调节这种反应，为了严格测试肌动蛋白的作用，我们将研究 PEEP 通气对两种 titin KO 小鼠模型纵向萎缩的影响：其中一种小鼠模型的纵向萎缩增加在目标 3 中，我们将使用危重患者的独特隔膜活检。患者验证目标 1 和 2 的结果并研究基于 titin 的机械传感是否有助于将确定上调/下调的肌动蛋白结合蛋白，其意义在于通过基因删除在小鼠模型中进行测试。本提案的创新点在于研究重点新颖、指导假设新颖、创新性强。小鼠模型、来自机械通气危重患者的独特隔膜活检及其新颖该提案的综合方法预计将在以下方面取得重大进展。我们对膈肌功能和肌联蛋白在其中的作用的理解。