Mechanisms of Cell-Free Hemoglobin-Mediated Injury to the Pulmonary Endothelial Glycocalyx in Sepsis

脓毒症中无细胞血红蛋白介导的肺内皮糖萼损伤机制

• 批准号: 10748825
• 负责人: Avery May Bogart
• 金额: $ 3.29万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10748825
• 关键词: Acute Respiratory Distress Syndrome; Affect; Automobile Driving; Biological; Blood Vessels; Cause of Death; Cells; Cessation of life; Circulation; Clinical; Communication; Complex; Critical Illness; Critical Thinking; Development; Endothelium; Enzymes; Erythrocytes; Experimental Designs; Functional disorder; Future; Genetic Transcription; Glycocalyx; Glycoproteins; Hemoglobin; Human; Immune response; Impairment; Infection; Injury; Investigation; Life; Link; Lung; Maintenance; Mediating; Mediator; Messenger RNA; Methods; Microvascular Permeability; Modeling; Molecular; Molecular Target; Morbidity - disease rate; Mus; Organ; Outcome; Oxidants; Oxidation-Reduction; Pathogenesis; Pathway interactions; Patients; Permeability; Persons; Physicians; Plasma Cells; Problem Solving; Process; Production; Proteoglycan; Public Health; Reactive Oxygen Species; Research Personnel; Role; Scientist; Sepsis; Severities; Superoxide Dismutase; Superoxides; Testing; Tissues; Training; Up-Regulation; Vascular Permeabilities; career; cost; endothelial dysfunction; experimental study; extracellular; heparanase; improved; inflammatory milieu; insight; knockout animal; lung injury; lung microvascular endothelial cells; mortality; mouse model; novel strategies; organ injury; overexpression; oxidation; polymicrobial sepsis; septic; septic patients; skills; success; syndecan; therapeutic development; transcription factor

PROJECT SUMMARY Sepsis, or life-threatening organ dysfunction due to a dysregulated host response to infection, is a critical public health issue. Affecting nearly 50 million people annually, sepsis is a leading cause of death worldwide, and significantly impacts the global economy. A major reason for the substantial burden of sepsis is an insufficient understanding of the biologic mechanisms that potentiate its pathogenesis. One of the hallmarks of sepsis is endothelial injury, which manifests as endothelial barrier hyperpermeability and results in organ dysfunction including acute respiratory distress syndrome (ARDS). A known contributor to the disruption of endothelial barrier integrity in sepsis is cell-free hemoglobin (CFH), hemoglobin released into the circulation from lysed red blood cells. CFH is elevated in the majority of patients with sepsis and is associated with higher rates of organ dysfunction, such as ARDS, and death. This proposal seeks to define the pathophysiologic role of CFH in endothelial hyperpermeability in sepsis. A primary regulator of endothelial permeability is the endothelial glycocalyx, a matrix of glycoproteins and proteoglycans that lines the vascular lumen. In sepsis, this function is impaired due to increased activity of heparanase, an enzyme that degrades the endothelial glycocalyx. Importantly, greater glycocalyx breakdown correlates with worse sepsis outcomes. Given that heparanase expression is, in part, modulated by transcription factors that are stimulated by reactive oxygen species (ROS), and that CFH undergoes oxidation in the inflammatory environment of sepsis, producing ROS including superoxide in the process, I hypothesize that CFH-generated superoxide triggers glycocalyx cleavage via induction of heparanase expression, thereby serving as a critical mediator of endothelial hyperpermeability and consequent organ injury in sepsis. I will test the effect of CFH on the pulmonary endothelial glycocalyx using mechanistic approaches in both cultured primary human lung microvascular endothelial cells and murine polymicrobial sepsis. Both models will be used to accomplish each Aim. In Aim 1, I will determine the impact of superoxide and CFH on glycocalyx degradation, endothelial barrier function, and sepsis-associated lung injury, severity, and mortality. Aim 2 will define the role of CFH in the modulation of heparanase expression and activity. I will also interrogate whether alterations in heparanase expression and activity affect endothelial barrier permeability and sepsis outcomes. Finally, I will delineate the impact of CFH- generated superoxide on heparanase expression and activity to complete my investigation of this proposed pathway. In resolving the role of CFH in glycocalyx degradation and endothelial dysfunction, I will deliver unprecedented insights into the consequences of elevated circulating CFH during sepsis, with potential to unveil new approaches to the development of therapeutics for the treatment of sepsis-associated lung injury. Furthermore, the completion of this project will facilitate the development of my technical, critical thinking, and communication skills that will be crucial to my success as an independent physician-scientist.

项目摘要 败血症或由于宿主对感染的失调反应而导致的器官功能障碍是关键 公共卫生问题。每年影响近5000万人，败血症是全球死亡的主要原因， 并显着影响全球经济。重大败血症负担的主要原因是 对增强其发病机理的生物学机制的了解不足。的标志之一 败血症是内皮损伤，表现为内皮屏障超透明度，并导致器官 功能障碍，包括急性呼吸窘迫综合征（ARDS）。造成破坏的已知贡献者 败血症中的内皮屏障完整性是无细胞的血红蛋白（CFH），血红蛋白释放到循环中 来自裂解的红细胞。大多数败血症患者的CFH升高，与较高 器官功能障碍（例如ARDS和死亡）的发生率。该建议旨在定义病理生理角色 败血症内皮过度过敏性的CFH的CFH。内皮通透性的主要调节剂是 内皮糖脂，是糖蛋白和蛋白聚糖的基质，该基质在血管腔中排成。在败血症中 该功能由于肝素酶的活性增加而受到损害，乙酰肝素的活性是一种降解内皮的酶 糖脂。重要的是，较大的糖脂分解与败血症结果较差有关。鉴于 肝素酶表达部分由被活性氧刺激的转录因子调节 物种（ROS），CFH在败血症的炎症环境中经历氧化，产生ROS 在此过程中包括超氧化物，我假设CFH生成的超氧化物触发糖蛋白 通过诱导肝素酶表达裂解，从而充当内皮的关键介体 败血症中的过敏性和随之而来的器官损伤。我将测试CFH对肺部的影响 两种培养的原发性人肺微血管中使用机械方法的内皮糖蛋白 内皮细胞和鼠多菌血性败血症。两种模型都将用于实现每个目标。在AIM 1中， 我将确定超氧化物和CFH对糖脂降解，内皮屏障功能和 败血症相关的肺损伤，严重程度和死亡率。 AIM 2将定义CFH在调制中的作用 肝素酶的表达和活性。我还将询问肝素酶表达的改变和 活动会影响内皮屏障的渗透性和败血症。最后，我将描述CFH-的影响 在肝素酶表达和活性上产生超氧化物，以完成我对此提出的研究 路径。在解决CFH在糖脂降解和内皮功能障碍中的作用时，我将交付 对败血症期间循环CFH升高的后果的前所未有的见解，有可能 揭示了针对治疗败血症相关肺损伤的治疗疗法的新方法。 此外，该项目的完成将有助于发展我的技术，批判性思维和 对于我作为独立医师科学家的成功至关重要的沟通技巧。