Pulmonary endothelial glycocalyx degradation causes ARDS during sepsis

7.项目总结/摘要 急性呼吸窘迫综合征（ARDS）是一种严重的（死亡率> 30%）危重病， 在美国每年有超过19万的患者受到影响。尽管研究了40多年， 关于这种疾病是如何发展的，并且没有具体的治疗方法。虽然败血症是一个众所周知的原因， 脓毒性ARDS的发病机制尚不清楚。 肺内皮屏障功能障碍是ARDS发展的关键步骤， 从肺结核中分离血液对全身（非肺）血管系统的研究表明， 正确的内皮屏障功能依赖于完整的糖萼-蛋白聚糖的薄层， 糖蛋白和糖胺聚糖排列在血管腔中。新的数据表明， 脓毒症的介质降解全身性内皮糖萼，引起屏障功能障碍。的作用 然而，肺内皮糖萼在脓毒症和ARDS中的作用尚未被研究。 我们假设脓毒症诱导肺内皮糖萼降解，导致肺屏障 功能障碍和ARDS。由于糖萼结构在体外通常是异常的，因此将使用 离体和体内模型：离体灌注小鼠肺和闭胸活体小鼠肺 显微镜脂多糖（LPS）诱导的脓毒症模型的剂量-反应和时间过程 将测定肺糖萼降解。血管节段性（动脉与微血管与 静脉）模式的糖萼损失将映射使用多光子活体显微镜和比较， 脓毒症时内皮细胞通透性增高的节段性模式。肿瘤坏死因子的作用 乙酰肝素酶将作为LPS诱导的糖萼损失的介质进行探索，使用药理学抑制剂， 转基因小鼠模型。将探讨肝素酶抑制剂肝素的治疗益处。 总之，这项研究有望更好地了解一个不太了解的结构（ 肺内皮糖萼）与常见临床状况（脓毒症相关的ARDS）相关， 结合生理学（分离的灌注小鼠肺）和专门的显微镜（多光子活体 显微镜）方法。此外，这项调查确定乙酰肝素酶作为一个有吸引力的治疗 这是一种缺乏特异性治疗疾病的靶点。

7. PROJECT SUMMARY/ABSTRACT The acute respiratory distress syndrome (ARDS) is a severe (> 30% mortality) critical illness that affects over 190,000 patients in the United States each year. Despite over 40 years of study, little is known about how this disease develops, and no specific treatment exists. While sepsis is a well-known cause of ARDS, the mechanisms underlying the development of septic ARDS are uncertain. A key step in the development of ARDS is dysfunction of the pulmonary endothelial barrier, which separates blood from the lung interstitium. Studies of the systemic (non-pulmonary) vasculature have revealed that proper endothelial barrier function is dependent on an intact glycocalyx-a thin layer of proteoglycans, glycoproteins, and glycosaminoglycans lining the vascular lumen. Emerging data suggest that inflammatory mediators of sepsis degrade the systemic endothelial glycocalyx, causing barrier dysfunction. The role of the pulmonary endothelial glycocalyx in sepsis and ARDS, however, has been unexplored. We hypothesize that sepsis induces pulmonary endothelial glycocalyx degradation, leading to barrier dysfunction and ARDS. As glycocalyx structure is often aberrant in-vitro, this hypothesis will be explored using ex-vivo and in-vivo models: the isolated, perfused mouse lung and closed-chest, intravital mouse lung microscopy. The dose-response and time course of lipopolysaccharide (LPS, a model of sepsis) induced pulmonary glycocalyx degradation will be determined. The vascular segmental (arterial vs. microvascular vs. venous) pattern of glycocalyx loss will be mapped using multiphoton intravital microscopy and compared to the segmental pattern of endothelial hyperpermeability during sepsis. The role of tumor necrosis factor ¿ and heparanase will be explored as mediators of LPS-induced glycocalyx loss, using pharmacologic inhibitors and transgenic mouse models. The therapeutic benefit of heparin, an inhibitor of heparanase, will be explored. In summary, this investigation promises a better understanding of a poorly-understood structure (the pulmonary endothelial glycocalyx) with relevance to a common clinical condition (sepsis-associated ARDS) via a combined physiologic (isolated, perfused mouse lung) and specialized microscopic (multiphoton intravital microscopy) approach. Furthermore, this investigation identifies heparanase as an attractive therapeutic target in a disease that yet lacks specific treatment.