Haptoglobin 2 variant and endothelial glycocalyx shedding in sepsis-induced ARDS

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。脓毒症相关性ARDS的特征是肺组织病理退化。 内皮糖萼--肺血管所必需的富含糖胺聚糖的血管内层 动态平衡。在脓毒症中，迫切需要确定内皮细胞糖萼降解的早期触发因素， 既是为了加强我们对病理生理学的了解，更重要的是为了确定新的治疗靶点 脓毒症所致ARDS的预防和早期治疗。我们公布的和初步的数据表明：(1) 在脓毒症中，游离血红蛋白(CFH)被释放到循环中，并参与氧化剂介导的器官 功能障碍和死亡；(2)CFH可直接损伤肺内皮细胞糖基化，导致降解和死亡 脱落；(3)结合珠蛋白，一种内源性的无细胞血红蛋白清除剂，限制其引起 氧化损伤有一种常见的基因变异HP-2，它会增加人类和小鼠患ARDS的风险 患有脓毒症的患者和小鼠以及HP-2变异体增加了对 内皮细胞糖基化和氧化应激增加的证据。这项建议中的研究将建立在 这些初步的发现表征了CFH介导的内皮糖基化的机制 降解受HP-2基因的影响。我们的主要目标是将这些发现转化为新的目标 将在我们的新型隔离人肺模型中进行测试的治疗方法，为快速转化为 败血症的靶向临床试验。在目标1中，我们将使用最先进的循环中的质谱分析 用糖胺多聚糖片段确定血管内皮细胞糖萼脱落的程度和特征 Hp-2变异患者，研究与ARDS的关联并确定Hp-2变异的下游机制 血管内皮损伤。在目标2中，我们将使用基因操纵的小鼠模型来确定 Hp-2基因突变小鼠肝素酶和氧化损伤对糖萼降解的影响。在《目标3》中，我们将 检测HP-2基因型靶向氧化剂介导的损伤的治疗潜力，以保存 作为未来患者研究的翻译桥梁，隔离灌流的人肺中内皮细胞糖基化反应。 这些目标中提出的研究有可能产生重大和持久的科学影响。由于HP-2是 HP基因最常见的等位基因和超过40%的欧洲或非洲血统的人是 该等位基因纯合，针对HP2基因的患者进行预防内皮细胞的治疗 糖萼降解是一种新的方法，可能会对临床结果产生重大影响。

ABSTRACT 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. Sepsis-associated ARDS is characterized by pathologic degradation of the pulmonary endothelial glycocalyx—a glycosaminoglycan-enriched endovascular layer necessary for pulmonary vascular homeostasis. There is a vital need to identify early triggers of endothelial glycocalyx degradation 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 published and preliminary data suggest that (1) cell-free hemoglobin (CFH) is released into the circulation in sepsis and contributes to oxidant-mediated organ dysfunction and death; (2) CFH can directly injure the lung endothelial glycocalyx, causing degradation and shedding; (3) haptoglobin, an endogenous scavenger for cell-free hemoglobin that limits its ability to cause oxidative injury has a common genetic variant, HP-2, that increases the risk of ARDS in both humans and mice with sepsis; and (4) patients and mice with sepsis and the HP-2 variant have increased degradation of the endothelial glycocalyx and evidence of increased oxidative stress. The studies in this proposal will build on these preliminary findings to characterize the mechanisms by which CFH-mediated endothelial glycocalyx degradation is modified by the HP-2 genotype. Our primary goal is to translate these findings to new targeted therapies that will be tested in our novel isolated human lung model as preparation for rapid translation to targeted clinical trials in sepsis. In Aim 1, we will use state-of-the-art mass spectrometry analyses of circulating glycosaminoglycan fragments to determine the extent and signature of endothelial glycocalyx shedding in patients with the HP-2 variant, study the association with ARDS and determine downstream mechanisms of endothelial injury. In Aim 2 we will use genetically manipulated mouse models to determine the contribution of heparanase and oxidative injury to glycocalyx degradation in mice with the HP-2 genotype. In Aim 3, we will test the therapeutic potential of targeting oxidant mediated injury in the HP-2 genotype to preserve the endothelial glycocalyx in the isolated perfused human lung as a translational bridge to future patient studies. The studies proposed in these aims have the potential for major and sustained scientific impact. Since HP-2 is the most common allele of the HP gene and over 40% of people of European or African ancestry are homozygous for this allele, targeting patients with the HP2 genotype with therapies to prevent endothelial glycocalyx degradation is a new approach that could have a major impact on clinical outcomes.