Targeting cell-free hemoglobin in sepsis to reduce lung microvascular permeability: mechanistic and translational studies

项目摘要 脓毒症引起的急性呼吸窘迫综合征(ARDS)是导致急性呼吸衰竭的主要原因之一。 得了重病。发病率和死亡率很高，除了药物治疗外，还没有其他有效的药物治疗方法 抗菌剂。肺微血管内皮细胞通透性增加是一种决定性的致病因素 导致败血症相关ARDS的急性肺水肿和肺功能障碍的特征。尽管 调节微血管通透性的机制是一个密集的研究领域，近端 脓毒症相关性ARDS中肺微血管通透性增加的触发因素不是很好 明白了。迫切需要确定这些早期触发微血管通透性增加的因素。 脓毒症，既是为了加强我们对病理生理学的了解，更重要的是，为了寻找新的治疗靶点 用于预防和早期治疗脓毒症引起的ARDS。我们最近对患者进行的翻译研究， 体外灌流的人肺和小鼠脓毒症模型已证实无细胞血红蛋白(CFH)是一种 微血管通透性增加的关键近端介质，(1)被释放到循环中 80%的严重脓毒症患者，(2)与严重脓毒症患者的死亡率独立相关 脓毒症，(3)对我们的模型系统的肺微血管通透性有强大的影响，(4)可以 在临床和实验脓毒症中被氧化为高活性铁基(4+)血红蛋白，一种有效的氧化剂，和(5) 可以被血液蛋白还原剂对乙酰氨基酚机械靶向。此外，初步的 研究表明，氧化剂介导的线粒体损伤和内皮细胞凋亡的激活是 CFH调节微血管通透性的关键机制。这方面的研究 提案将建立在这项初步工作的基础上，以表征CFH触发增加的机制 脓毒症时肺微血管通透性。我们的主要目标是将这些发现转化为新的目标 将在我们的新型人类肺模型中进行测试的治疗方法，为快速转化为临床试验做准备 在败血症中。在目标1中，我们将研究CFH增加的细胞和生理机制 人肺微血管通透性与急性肺损伤及临床相关模型的研究 脓毒症引起的ARDS。在目标2中，我们将研究原代肺微血管内皮细胞以及我们的 体内模型，以确定CFH诱导内皮细胞凋亡的分子机制。在目标3中，我们 将测试对乙酰氨基酚在肺微血管中靶向氧化型CFH的治疗潜力 人和小鼠脓毒症诱导的ARDS的内皮细胞和临床相关模型。这些研究 在这些目标中提出的建议有可能产生重大和持久的科学影响。及早瞄准CFH 脓毒症中ARDS的预防和治疗是一种新的方法，可能对临床产生重大影响 结果。此外，将对乙酰氨基酚作为微血管增加的靶向治疗的重点 氧化CFH的渗透性可以重新用于治疗脓毒症的廉价、安全的化合物。

Project Summary Sepsis-induced acute respiratory distress syndrome (ARDS) is a leading cause of acute respiratory failure in critical illness. Morbidity and mortality are high and there are no proven pharmacologic therapies other than antimicrobials. Increased permeability of the pulmonary microvascular endothelium is a defining pathogenic feature that leads to acute pulmonary edema and lung dysfunction in sepsis-associated ARDS. Although the mechanisms that regulate microvascular permeability are an area of intensive research effort, the proximal triggers of increased pulmonary microvascular permeability in sepsis-associated ARDS are not well understood. There is a vital need to identify these early triggers of increased microvascular permeability in sepsis, both to enhance our understanding of pathophysiology, and critically, to identify new therapeutic targets for prevention and early treatment of sepsis-induced ARDS. Our recent translational studies in patients, the isolated perfused human lung, and mouse models of sepsis have identified cell-free hemoglobin (CFH) as a key proximal mediator of increased microvascular permeability that (1) is released into the circulation in over 80% of patients with severe sepsis, (2) is independently associated with mortality in patients with severe sepsis, (3) has potent effects on pulmonary microvascular permeability across our model systems, (4) can be oxidized in clinical and experimental sepsis to highly reactive ferryl (4+) hemoglobin, a potent oxidant, and (5) can be mechanistically targeted by the hemoprotein reductant acetaminophen. Furthermore, preliminary studies suggest that oxidant-mediated mitochondrial injury and activation of apoptosis in endothelial cells are key mechanisms through which CFH mediates its effects on microvascular permeability. The studies in this proposal will build on this preliminary work to characterize the mechanisms by which CFH triggers increased pulmonary microvascular permeability in sepsis. Our primary goal is to translate these findings to new targeted therapies that will be tested in our novel human lung model as preparation for rapid translation to clinical trials in sepsis. In Aim 1, we will study the cellular and physiologic mechanisms by which CFH increases microvascular permeability and acute lung injury in the isolated human lung and clinically relevant models of sepsis-induced ARDS. In Aim 2 we will study primary pulmonary microvascular endothelial cells along with our in vivo models to define the molecular mechanisms by which CFH induces endothelial apoptosis. In Aim 3, we will test the therapeutic potential of targeting oxidized CFH with acetaminophen in pulmonary microvascular endothelial cells and clinically relevant models of human and murine sepsis-induced ARDS. The studies proposed in these aims have the potential for major and sustained scientific impact. Targeting CFH for early prevention and treatment of ARDS in sepsis is a new approach that could have a major impact on clinical outcomes. Furthermore, the focus on acetaminophen as a targeted therapy for increased microvascular permeability due to oxidized CFH could repurpose an inexpensive, and safe compound for treatment of sepsis.