Fibro-adipogenic remodeling of the diaphragm in obesity-associated respiratory dysfunction

肥胖相关呼吸功能障碍中隔膜的纤维脂肪形成重塑

• 批准号: 10379062
• 负责人: ERIC D BURAS
• 金额: $ 16.96万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10379062
• 关键词: Abdomen; Ablation; Adipocytes; Adipose tissue; American; Anatomy; Animals; Atrophic; Autopsy; Biological Models; Biomechanics; Body mass index; Cardiac; Cardiovascular system; Cells; Chest; Clinical; Clinical Research; Collagen; Data; Defect; Deposition; Diagnosis; Diphtheria Toxin; Dyspnea; Evaluation; Event; Exertion; Experimental Models; Failure; Fibroblasts; Fibrosis; Functional disorder; Gene Expression Profiling; Generations; High Fat Diet; Histology; Human; Hypercapnia; Impairment; Individual; Injury; Intramuscular; Isometric Contraction; Isometric Exercise; Learning; Life; Link; Lung; Measurement; Measures; Mechanics; Mediating; Mediator of activation protein; Mesenchymal Stem Cells; Modeling; Morbid Obesity; Morbidity - disease rate; Motion; Mus; Muscle; Muscle Weakness; Muscle function; Obese Mice; Obesity; Overnutrition; Pathologic; Patients; Phenotype; Physiological; Physiology; Pickwickian Syndrome; Polymers; Property; Protocols documentation; Respiration Disorders; Respiratory Diaphragm; Respiratory Muscles; Sampling; Skeletal Muscle; Structure; Structure-Activity Relationship; Testing; Thinness; Time; Tissue Expansion; Tissue Sample; Tissues; Training; Ultrasonography; Visceral; Weight; Whole Body Plethysmography; Work; base; cardiovascular risk factor; diet-induced obesity; dietary control; feeding; high risk; in vivo; lipid biosynthesis; mdx mouse; mortality; mouse model; muscle regeneration; muscular dystrophy mouse model; novel; obese patients; prevent; progenitor; respiratory; response; stem cell population; transcriptome; transcriptome sequencing; ultrasound; ventilation

Abstract: Obesity-associated respiratory complications range from simple dyspnea on exertion to life-threatening obesity hypoventilation syndrome (OHS). The latter, defined by PaCO2 >45 torr in individuals with body mass index (BMI) >30kg/m2 and no alternative cause of hypercapnia, is associated with severe cardiac complications and increased mortality. While inability of the lungs to expand against abdominal and thoracic adipose tissue is thought to drive this ventilatory compromise, clinical studies have also identified respiratory muscle weakness in obese patients. Moreover, large adipocyte inclusions are seen in diaphragms of subjects with OHS but not in obese/normocapnic or lean individuals. These findings suggest the diaphragm itself may be compromised with obesity; however, impacts of over-nutrition on structure and function of this muscle are not well defined. In mice subjected to a long-term diet-induced obesity (DIO) time course, we observed hypercapnia after 6 months high fat diet (HFD) feeding. This temporally corresponded with impaired diaphragm muscle function—assessed in vivo by ultrasonography and ex vivo by measurement of contractile force. Adipose tissue expansion and collagen deposition within the diaphragm temporally corresponded with hypercapnia and quantitatively correlated with ex vivo contractile deficits. Lineage tracing showed all intra-diaphragmatic adipocytes and many collagen-producing cells to arise from fibro-adipogenic progenitors (FAPs), a skeletal muscle mesenchymal stem cell population. FAP number, proliferation, and collagen deposition increased with obesity. We hypothesize that FAP-mediated, fibro-adipogenic remodeling of the diaphragm impairs ventilatory function in obesity. In Aim 1, we will test whether obesity per se impairs ventilation and diaphragm function by analyzing weight-matched genetically obese and DIO mice. Ex vivo, we will measure contractile function and passive stiffness of large muscle isolates and individual myofibers to determine whether biomechanical defects occur at the tissue or cellular level. Finally, we will determine quantitative correlations of intra-diaphragmatic adipocyte number and polymerized collagen with these physiologic parameters. In Aim 2, we specifically test the hypothesis that FAPs mediate diaphragm fibro-adipogenic remodeling and dysfunction in obesity. We will analyze FAP response to obesity with global gene expression profiling and ex vivo proliferation, adipogenesis and collagen deposition quantification. We will then determine whether (diphtheria toxin-mediated) FAP ablation prevents diaphragm fibro-adipogenic changes and dysfunction in a DIO model. In Aim 3, we will analyze tissue samples and FAPs isolated from human autopsy samples to determine whether similar changes occur in obese humans and associate with clinical OHS diagnosis. The work will define a cellular mechanism of OHS; and completion of the project will provide training in muscle biomechanics, RNA-Seq and human sample analysis.

摘要： 与肥胖相关的呼吸系统并发症包括从简单的运动性呼吸困难到危及生命的肥胖 低通气综合征（OHS）。后者，定义为PaCO 2>45 mmHg，个体体重指数 (BMI)> 30 kg/m2且无其他高碳酸血症原因，与严重心脏并发症相关， 增加死亡率。虽然肺部无法对腹部和胸部脂肪组织进行扩张， 被认为是推动这种解释性妥协的原因，临床研究还发现， 肥胖患者。此外，在OHS受试者的横膈膜中可以看到大的脂肪细胞内含物，而在 肥胖/碳酸正常或瘦的个体。这些发现表明隔膜本身可能受到损害， 肥胖;然而，营养过剩对这种肌肉的结构和功能的影响还没有很好的定义。小鼠 在长期饮食诱导肥胖（DIO）的时间过程中，我们观察到高碳酸血症6个月后， 脂肪饮食（HFD）喂养。这在时间上与隔膜肌功能受损相对应--在 体内通过超声检查和离体通过测量收缩力。脂肪组织扩张和胶原蛋白 膈内沉积在时间上与高碳酸血症相对应，并与前房内沉积在数量上相关联。 体内收缩缺陷。谱系追踪显示，所有的膀胱内脂肪细胞和许多胶原蛋白产生细胞都是胶原蛋白生成细胞。 这些细胞来自纤维脂肪生成祖细胞（FAP），一种骨骼肌间充质干细胞群。 FAP数量、增殖和胶原沉积随肥胖而增加。 我们假设FAP介导的纤维脂肪形成性膈肌重塑损害了膈肌功能， 在肥胖症中的作用在目标1中，我们将测试肥胖本身是否会损害通气和横膈膜功能， 分析体重匹配的遗传性肥胖和DIO小鼠。离体，我们将测量收缩功能， 大肌肉分离物和单个肌纤维的被动刚度，以确定是否存在生物力学缺陷 发生在组织或细胞水平。最后，我们将确定内部的定量相关性， 脂肪细胞数量和聚合胶原与这些生理参数。在目标2中，我们专门测试 FAPs介导肥胖症中横膈膜纤维脂肪形成重塑和功能障碍的假设。我们将 用整体基因表达谱和离体增殖、脂肪形成分析FAP对肥胖的反应 和胶原沉积定量。然后，我们将确定（白喉毒素介导的）FAP消融是否 防止DIO模型中的隔膜纤维脂肪形成变化和功能障碍。在目标3中，我们将分析组织 从人类尸检样本中分离的FAP和FAP，以确定肥胖患者是否发生类似的变化。 并与临床OHS诊断相关。这项工作将确定职业健康安全的细胞机制;以及 该项目完成后将提供肌肉生物力学、RNA测序和人体样本分析方面的培训。