Fibrinogen and Factor XIII in Venous Thrombosis

静脉血栓形成中的纤维蛋白原和因子 XIII

• 批准号: 9205251
• 负责人: Alisa S. Wolberg
• 金额: $ 37.63万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-15 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9205251
• 关键词: Affect; American; Anticoagulation; Autopsy; Binding; Biochemical Genetics; Biological Assay; Biological Models; Blood coagulation; Characteristics; Clinical; Coagulation Process; Data; Deposition; Development; Edema; Electrons; Erythrocytes; Factor XIII; Factor Xa; Fibrin; Fibrinogen; Functional disorder; Goals; Hemorrhage; Hemostatic function; Human; Image; In Vitro; Left; Leg Ulcer; Mediating; Medical; Mission; Modeling; Molecular; Morbidity - disease rate; Patients; Peptides; Pharmacology; Phase; Plasma; Polymers; Postphlebitic Syndrome; Process; Production; Public Health; Recombinant Proteins; Recurrence; Research; Risk; Role; Testing; Thrombin; Thrombosis; Thrombus; Ulcer; Ultrasonography; United States National Institutes of Health; Venous; Venous Thrombosis; Whole Blood; Work; analytical method; animal imaging; chronic pain; clinically significant; crosslink; human disease; improved; in vivo; in vivo Model; innovation; intravital microscopy; knowledge base; mouse model; new therapeutic target; next generation; novel strategies; prevent; public health relevance; targeted treatment; tool; transmission process

 DESCRIPTION (provided by applicant): Venous thrombosis (VT) affects over 1 million Americans annually. Even with treatment, 30-50% of VT patients develops recurrent VT or suffer debilitating long-term morbidity including chronic pain, edema, and ulcers (so- called "post-thrombotic syndrome"). Current anticoagulation therapies target factor Xa or thrombin and are associated with a significant risk of catastrophic bleeding. The development of next generation agents which reduce thrombosis without increasing the risk of hemorrhage, would have a profound impact on this significant clinical problem. The defining characteristics of venous "red" thrombi are their high red blood cell (RBC) and fibrin content. The existing paradigm suggests RBCs are passively trapped in the clot during fibrin polymer formation. However, we have recently discovered that factor XIII (FXIII) mediates RBC retention in clots and determines clot size. We have also identified fibrinogen residues that promote interactions with FXIII and are required for normal FXIII activation and fibrin crosslinking. Importantly, we have shown that inhibiting FXIIIa activity or blocking FXIII-fibrinogen interactions reduces clot RBC content, and consequently, significantly reduces thrombus size in vitro and in vivo. These exciting discoveries suggest that inhibiting FXIII or blocking FXIII-fibrinogen interactions represent entirely new and novel strategies for reducing VT. The goal of this application is to determine the molecular mechanisms by which FXIII and fibrinogen mediate VT. The overall hypothesis is that FXIII(a) activity mediates RBC retention in clots. Thus, inhibiting FXIII activiy or disrupting the interaction between FXIII and fibrinogen will reduce VT. This hypothesis will be tested in three Specific Aims: 1) Define the fibrinogen residues required for FXIII binding and determine whether peptides that disrupt FXIII interactions with fibrinogen decrease RBC retention in clots, 2) Determine whether FXIIIa promotes RBC retention in clots via fibrin crosslinking, and 3) Determine the role of FXIII and effect of FXIII(a) inhibition in VT and hemostasis. This study will employ biochemical, genetic and pharmacologic tools to define the FXIII- fibrinogen axis and determine the role of FXIII activity and RBC retention during whole blood clot formation. FXIII-fibrinogen interactions and FXIIIa function will be examined using recombinant proteins, solution phase binding assays, and innovative fibrin analytical methods. Clot formation will be studied using in vitro and in vivo models of VT and hemostasis, including live-animal imaging (e.g., ultrasound imaging and intravital microscopy). These studies will significantly expand our understanding of newly-recognized roles for FXIII(a) and fibrinogen in thrombus formation and stability. This study is highly innovative because it challenges the current paradigm that RBCs are passively entangled in thrombi and proposes that thrombus RBC content can be reduced to prevent VT. The proposed research is clinically significant because it may reveal an entirely new strategy to reduce VT.

 描述（由申请人提供）：静脉血栓形成（VT）每年影响超过100万美国人。即使进行治疗，30-50%的VT患者也会发展为复发性VT或遭受使人衰弱的长期发病，包括慢性疼痛、水肿和溃疡（所谓的“血栓形成后综合征”）。目前的抗凝治疗靶向因子Xa或凝血酶，并与灾难性出血的重大风险相关。下一代药物的发展，减少血栓形成，而不增加出血的风险，将有深远的影响，这一重大的临床问题。静脉“红色”血栓的定义特征是其高红细胞（RBC）和纤维蛋白含量。现有的范例表明，在纤维蛋白聚合物形成期间，RBC被动地被困在凝块中。然而，我们最近发现因子XIII（FXIII）介导RBC在凝块中的滞留并决定凝块的大小。我们还鉴定了促进与FXIII相互作用的纤维蛋白原残基，其是正常FXIII活化和纤维蛋白交联所需的。重要的是，我们已经表明，抑制FXIIIa活性或阻断FXIII-纤维蛋白原相互作用可降低血凝块RBC含量，从而显著降低体外和体内血栓大小。这些令人兴奋的发现表明，抑制FXIII或阻断FXIII-纤维蛋白原相互作用代表了减少VT的全新和新颖的策略。本申请的目的是确定FXIII和纤维蛋白原介导VT的分子机制。总体假设是FXIII（a）活性介导血凝块中的RBC滞留。因此，抑制FXIII活性或破坏FXIII与纤维蛋白原之间的相互作用将降低VT。该假设将在三个特定目的中进行检验：1）定义FXIII结合所需的纤维蛋白原残基，并确定破坏FXIII与纤维蛋白原相互作用的肽是否会降低血凝块中的RBC滞留，2）确定FXIIIa是否通过纤维蛋白交联促进血凝块中的RBC滞留，以及3）确定FXIII的作用和FXIII（a）抑制VT和止血的效果。本研究将采用生物化学、遗传学和药理学工具来定义FXIII-纤维蛋白原轴，并确定FXIII活性和RBC保留在全血凝块形成过程中的作用。FXIII-纤维蛋白原相互作用和FXIIIa功能将使用重组蛋白，溶液相结合试验和创新的纤维蛋白分析方法进行检查。将使用VT和止血的体外和体内模型研究凝块形成，包括活体动物成像（例如，超声成像和活体显微术）。这些研究将显著扩展我们对FXIII（a）和纤维蛋白原在血栓形成和稳定性中新认识的作用的理解。这项研究是高度创新的，因为它挑战了目前的范式，即RBC被动地纠缠在血栓中，并提出可以减少血栓RBC含量以预防VT。这项研究具有临床意义，因为它可能揭示一种全新的减少VT的策略。