Cellular Mechanisms of Cardiac ECM Structure and Function

心脏 ECM 结构和功能的细胞机制

• 批准号: 10585689
• 负责人: Amy D Bradshaw
• 金额: --
• 依托单位: RALPH H JOHNSON VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2026-10-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10585689
• 关键词: Ablation; Address; Age; Animal Model; Aortic Valve Stenosis; Cardiac; Characteristics; Chronic; Clinical; Collagen; Congestive Heart Failure; Data; Deposition; Development; Disease Pathway; Excision; Exhibits; Exposure to; Extracellular Matrix; Fibroblasts; Fibrosis; Healthcare; Heart; Homeostasis; Hypertension; Imaging Techniques; In Vitro; Incidence; Lead; Macrophage; Matrix Metalloproteinases; Measurement; Measures; Mediating; Methods; Modification; Molecular; Mus; Myocardial; Myocardium; Outcome; Patient Care; Patients; Peptide Hydrolases; Phenotype; Physiological; Population; Production; Proteins; Publishing; Reproducibility; Research; Role; Structure; System; Testing; Time; Tissue Inhibitor of Metalloproteinase-1; Transgenic Mice; Veterans; aorta constriction; cardiovascular health; clinically relevant; coronary fibrosis; disease diagnosis; hemodynamics; improved; in vivo; innovation; interstitial; mouse model; novel; pressure; profibrotic fibroblast; programs; response; success

Chronic heart failure (CHF) has a designated Quality Enhancement Research Initiative (QUERI) in the VA system to address ways to improve cardiovascular healthcare for Veteran’s suffering from CHF. Success in treatment of CHF associated with chronic pressure overload (hypertension, aortic valve stenosis) is limited by the presence of persistent interstitial fibrosis despite our ability to normalize hemodynamic load. The proposed studies will define abnormalities in cellular mechanisms that cause this critical clinical unmet need. Filling this need will depend on defining the fundamental causal determinants that control both initial ECM degradation and persistence of interstitial myocardial fibrosis following normalization of hemodynamic load. Primary cellular regulators of ECM homeostasis are postulated to be myocardial macrophages and fibroblasts. Our previous studies and preliminary data have led to our central hypothesis: Chronic hemodynamic overload causes fundamental changes in both macrophage and fibroblast phenotype, the hallmark of which is dysregulated protease homeostasis that in turn impedes cellular response to unloading and limits complete regression of fibrosis even after normalization of hemodynamic load. To test this hypothesis, innovations in in vivo animal models and in vitro fibroblast culture were developed. In vivo, a clinically relevant reversal of LVPO (unloading) was created in mice by surgical removal of the transverse aortic constriction (unTAC). UnTAC was found to initiate but lead to an incomplete regression of cardiac fibrosis. Preliminary data indicate that a significant increase in myocardial macrophages coincides with initiation of collagen degradation following hemodynamic unloading but these increases in macrophages are not sustained at later times after unTAC. To address whether load-dependent changes in fibroblast phenotype were a key factor in this remodeling, a fibroblast culture systems that mimics clinically relevant myocardial stiffness was established. In vivo, measurements of myocardial stiffness demonstrated that fibroblasts are exposed to a force of ~8 kPA in PO myocardium and ~2 kPA in normal myocardium. Physiologically relevant, stiffness-dependent changes in fibroblasts phenotype were observed in fibroblasts from normal myocardium whereas fibroblasts from TAC and unTAC myocardium exhibited a pro-fibrotic non-responsive phenotype to changes in stiffness. Preliminary data indicate that Tissue inhibitor of metalloproteinase (TIMP)-1 was a causal factor in this pro-fibrotic persistent phenotype. Our strong preliminary data gave rise to the following Specific Aims to test our central hypothesis: Aim 1: Test the hypothesis that reversal of sustained hemodynamic overload shifts myocardial macrophage phenotype to a distinct but transient anti-fibrotic (ECM-degradation) phenotype that initiates, but does not complete, a load-dependent regression of accumulated interstitial ECM. Aim 2: Test the hypothesis that sustained in vivo increases in hemodynamic load change myocardial fibroblasts to a profibrotic, TIMP-1 dependent phenotype that remains profibrotic even when hemodynamic load is reversed.

慢性心力衰竭（CHF）在VA中有指定的质量增强研究计划（QUERI） 系统，以解决如何改善退伍军人的心血管保健患有CHF。成功 与慢性压力超负荷（高血压、主动脉瓣狭窄）相关的CHF的治疗受到以下限制： 尽管我们有能力使血流动力学负荷正常化，但仍存在持续性间质纤维化。的 拟议的研究将确定导致这一关键临床未满足需求的细胞机制异常。 满足这一需求将取决于定义控制初始ECM和ECM的基本因果决定因素。 血流动力学负荷正常化后间质性心肌纤维化的降解和持续。 ECM稳态的主要细胞调节因子被假定为心肌巨噬细胞和成纤维细胞。 我们先前的研究和初步数据导致了我们的中心假设：慢性血流动力学 超负荷引起巨噬细胞和成纤维细胞表型的根本变化，其标志是 蛋白酶稳态失调，进而阻碍细胞对卸载的反应，并限制完全的 甚至在血流动力学负荷正常化后纤维化的消退。为了验证这一假设， 建立了体内动物模型和体外成纤维细胞培养。在体内，LVPO的临床相关逆转 通过手术去除横向主动脉缩窄部（unTAC）在小鼠中产生（卸载）。联柬权力机构 发现其启动但导致心脏纤维化的不完全消退。初步数据显示， 心肌巨噬细胞的显著增加与胶原降解的开始一致， 血液动力学卸载，但巨噬细胞中的这些增加在unTAC后的稍后时间不持续。到 解决成纤维细胞表型的负荷依赖性变化是否是这种重塑的关键因素， 建立了模拟临床相关心肌硬度的成纤维细胞培养系统。在体内， 心肌硬度的测量表明，成纤维细胞在PO中暴露于约8 kPA的力， 正常心肌~ 2kPA。生理相关的，僵硬依赖性的变化， 在来自正常心肌的成纤维细胞中观察到成纤维细胞表型，而来自TAC和 unTAC心肌表现出对硬度变化无反应的促纤维化表型。初步数据 表明金属蛋白酶组织抑制剂（TIMP）-1是这种促纤维化持续性 表型我们强大的初步数据产生了以下具体目标来检验我们的中心假设： 目的1：检验持续血流动力学超负荷逆转使心肌细胞 巨噬细胞表型转化为独特但短暂的抗纤维化（ECM-降解）表型， 启动但不完成累积的间质ECM的负荷依赖性消退。 目的2：检验在体内持续增加血流动力学负荷改变心肌的假设 在一些实施方案中，所述成纤维细胞转化为促纤维化的TIMP-1依赖性表型，即使在 血液动力学负荷被逆转。