Pulmonary endothelial glycocalyx degradation causes ARDS during sepsis

7.项目摘要/摘要 急性呼吸窘迫综合征(ARDS)是一种严重(30%死亡率)的危重疾病， 每年影响美国19万多名患者。尽管进行了40多年的研究，但人们对此知之甚少 关于这种疾病是如何发展的，目前还没有具体的治疗方法。而脓毒症是众所周知的 在ARDS中，感染性ARDS的发生机制尚不明确。 ARDS发展过程中的一个关键步骤是肺内皮屏障功能障碍，它 从肺间质中分离出血液。对全身(非肺)血管系统的研究揭示了 正常的内皮屏障功能有赖于完整的糖萼--一层薄薄的蛋白多糖， 糖蛋白和糖胺聚糖排列在血管管腔内。新出现的数据表明，炎症性 脓毒症的介体降解系统内皮细胞的糖基化反应，导致屏障功能障碍。美国政府的角色 然而，脓毒症和ARDS中的肺内皮细胞糖基化反应尚不清楚。 我们假设脓毒症诱导肺内皮细胞糖基化降解，从而导致屏障。 功能障碍和ARDS。由于在体外糖萼结构经常是异常的，这一假说将被用 体外和体内模型：离体鼠肺、灌流小鼠肺和闭胸式活体小鼠肺 显微镜。脓毒症模型脂多糖诱导的剂量-反应和时间过程 将测定肺内糖萼降解率。血管节段性(动脉vs.微血管vs. 静脉)的糖萼丢失模式将使用多光子活体显微镜进行绘制，并与 脓毒症时血管内皮细胞高通透性的节段性模式。肿瘤坏死因子的作用及意义 肝素酶将作为脂多糖诱导的糖萼丢失的媒介进行探索，使用药物抑制剂和 转基因小鼠模型。肝素是一种肝素酶的抑制剂，它的治疗益处将被探索。 总而言之，这项调查有望更好地理解一个鲜为人知的结构( 肺内皮细胞糖基化反应)与常见临床情况(脓毒症相关性ARDS)的相关性 生理学(隔离、灌流的小鼠肺)和特殊显微镜(多光子活体内)相结合的显微镜 显微镜)方法。此外，这项研究发现乙酰肝素酶是一种有吸引力的治疗方法。 针对一种尚无特效治疗的疾病。

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.