Glycoprotein Remodeling in the Vasculopathy and Coagulopathy of Sepsis

描述（由申请人提供）：败血症的凝血功能障碍和血管病变仍然是常见的致残和危及生命的感染并发症，随着感染生物体的流行和毒力的增加，其发病率正在增加。由于缺乏对败血症病理生理的充分认识，目前的治疗方法缺乏且无效。我们最近的发现揭示了肺炎球菌脓毒症中宿主和病原体之间的一种新的相互作用，在这种相互作用中，血液和血管中的宿主糖蛋白经历了翻译后重塑，改变了它们的稳态和功能。这种重塑导致唾液酸连接中的唾液糖蛋白缺乏，然后被内吞Ashwell-Morell受体（AMR）选择性地识别。唾液糖蛋白是由水解唾液酸键的神经氨酸酶或缺乏一种或多种唾液转移酶形成的。AMR对亚洲糖蛋白的调节对凝血功能障碍、血管病变和肺炎球菌脓毒症的死亡率有深远的缓解作用。目前的应用代表了糖蛋白重塑在脓毒症期间凝血功能障碍和内皮功能障碍发病机制中的作用的扩展研究。该项目继续利用糖生物学、分子和细胞生物学与微生物学、免疫学和传染病建模的独特协同和富有成效的跨学科整合，迄今为止已经产生了意想不到的和改变范式的观察结果——这些观察结果对新疗法具有很强的转化意义。正如我们最近发表的那样，糖蛋白重塑将在小鼠中通过靶向负责涉及末端唾液化的重要生物学修饰的生化途径（宿主唾液转移酶ST3Gal-I和ST3Gal-IV）以及通过调节肝脏AMR的快速和强大的唾液糖蛋白清除功能来进行遗传调节。从微生物学的角度来看，我们将扩大我们的研究，超越我们已发表的关于肺炎链球菌（SPN）的工作，包括与侵袭性血流感染和败血症相关的另外两种主要人类病原体，金黄色葡萄球菌（SA）和A群链球菌（GAS）。通过分析这些引起致病性凝血和微血管功能障碍的细菌表达的毒力因子（凝血酶，M蛋白），包括使用等基因细菌突变体，将提供额外的机制见解。人体组织培养研究将探讨糖蛋白重塑对细菌性败血症病原体、凝血蛋白、中性粒细胞和内皮细胞之间相互作用的影响。野生型和基因工程小鼠的体内活感染模型将指导糖蛋白重塑的治疗操作，以确定改善凝血参数、内皮功能、细菌清除和败血症临床结果的工具。

DESCRIPTION (provided by applicant): The coagulopathy and vasculopathy of sepsis remain common disabling and life-threatening complications of infection that are increasing in incidence as human populations escalate with the prevalence and virulence of infectious organisms. Lack of sufficient knowledge of the pathophysiology of sepsis is represented by the paucity and ineffectiveness of current treatments. We have recently made discoveries that reveal a novel interaction between the host and pathogen in pneumococcal sepsis during which host glycoproteins in the blood and vasculature undergo a post-translational remodeling that alters their homeostasis and function. This remodeling results in asialoglycoproteins deficient in sialic acid linkages that are then selectively recognized by the endocytic Ashwell-Morell receptor (AMR). Asialoglycoproteins are formed by neuraminidases that hydrolyze sialic acid linkages or by a deficiency of one or more sialyltransferases. Asialoglycoprotein modulation by the AMR results in a profound mitigation of coagulopathy, vasculopathy, and mortality in pneumococcal sepsis. The present application represents an expanded investigation of the role of glycoprotein remodeling in the pathogenesis of coagulopathy and endothelial dysfunction during sepsis. The project takes continued advantage of a unique synergistic and productive interdisciplinary integration of glycobiology, molecular and cell biology with microbiology, immunology and infectious disease modeling that has to date produced unexpected and paradigm changing observations -- ones that carry strong translational implications for novel therapeutics. Glycoprotein remodeling will be modulated genetically in the mouse by targeting the biochemical pathways responsible for biologically important modifications involving terminal sialylation (host sialyltransferases ST3Gal-I and ST3Gal-IV) and by modulating the rapid and powerful asialoglycoprotein clearance function of the hepatic AMR - as we have recently published. From the microbiology perspective, we will expand our studies beyond our published work on Streptococcus pneumoniae (SPN) to include two other major human pathogens associated with invasive bloodstream infections and sepsis, Staphylococcus aureus (SA) and group A Streptococcus (GAS). Additional mechanistic insight will be provided through analysis of virulence factors express by these bacteria that provoke pathogenic coagulation and microvascular dysfunction (coagulases, M protein), including the use of isogenic bacterial mutants. Human tissue culture studies will explore the effects of glycoprotein remodeling on interactions between bacterial sepsis pathogens, coagulation proteins, neutrophils and endothelium. In vivo live infection models with wild-type and genetically engineered mice will guide therapeutic manipulation of glycoprotein remodeling, to identify tools to improve coagulation parameters, endothelial function, bacterial clearance and clinical outcomes in sepsis.