Novel determinants of fibrinogen pro-repair activity in acetaminophen-induced liver toxicity

对乙酰氨基酚诱导的肝毒性中纤维蛋白原修复活性的新决定因素

• 批准号: 10585920
• 负责人: James P Luyendyk
• 金额: $ 41.72万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10585920
• 关键词: Acetaminophen; Acetylcysteine; Acute; Acute Liver Failure; Afibrinogenemia; Air; Analgesics; Biochemistry; Blood coagulation; Cell Culture System; Chemicals; Coagulation Process; Complex; Custom; Data; Defect; Deposition; Enzymes; Exposure to; Factor XIII; Fibrin; Fibrinogen; Gene Expression; Glutaminase; Goals; Health; Hemorrhage; Hemostatic function; Hepatic; Hepatotoxicity; Hospital Costs; Human; In Vitro; Injury; Integrin Binding; Integrins; Ligands; Link; Liver; Liver Failure; Liver diseases; Macrophage; Macrophage Activation; Mediating; Modification; Molecular; Mus; Mutation; Outcome; Overdose; Pathway interactions; Patient-Focused Outcomes; Patients; Phagocytes; Pharmaceutical Preparations; Polymers; Process; Property; Proteins; Research; Risk; Role; Structure; Testing; Therapeutic; Thrombin; Tissues; Toxic Hepatitis; Toxicant exposure; United States; Variant; acetaminophen overdose; acetaminophen-induced liver injury; acute liver injury; acute toxicity; clotting enzyme; crosslink; design; gene repair; improved; in vitro activity; in vivo; injured; injury and repair; intrahepatic; liver injury; liver repair; mouse model; novel; novel therapeutics; programs; repair function; repaired; response; therapeutic target; thrombotic; thrombotic complications; toxicant; transglutaminase 2

PROJECT SUMMARY The leading cause of acute liver injury and acute liver failure in the United States is hepatotoxicity caused by overdose of the pain medication acetaminophen (APAP). Nearly 50% of patients presenting with APAP- induced liver injury require costly hospitalization, and the efficacy of available treatments (i.e., N- acetylcysteine) is very limited for patients presenting well after APAP overdose. APAP overdose patients would benefit most from treatments that maximize liver repair pathways, such as proe-pr air macrophage activation. We recently discovered a remarkable pathway of liver repair following APAP hepatotoxicity whereby the clotting protein fibrin(ogen), deposited in the injured liver of both humans and mice, engages β2 integrins and directs local pro-repair macrophage activity. The fibrin(ogen)-β2 integrin interaction is carefully regulated and acquired by modifications of fibrin(ogen) structure. Defining the mechanisms whereby fibrin(ogen) is converted to a β2 integrin ligand that elicits pro-repair macrophage activity in liver injury is critical, as this could uncover novel putative therapeutic targets to improve liver repair pathways in patients with severe hepatotoxicity or acute liver failure. Our strong preliminary studies suggest that, in contrast to the current paradigm, hepatic fibrin(ogen) accumulation caused by acute toxicity is independent of blood coagulation activity. The central hypothesis framing these studies is that liver injury stimulates coagulation-independent cross-linking of fibrin(ogen) by tissue transglutaminase-2 (TGM2) to form a novel fibrin(ogen) complex that drives macrophage- mediated liver repair. Our approach includes genetically-modified mice lacking specific fibrin(ogen) cross- linking enzymes, mice expressing fibrin(ogen) proteins with specific functional mutations, application of a coagulation-insensitive fibrin(ogen) as a putative pro-repair therapeutic, a unique cell culture system to examine primary macrophage activation by unique molecular forms of fibrin(ogen), and analysis of fibrin(ogen) deposits in livers of human patients with acute liver failure. The investigative team comprises experts in toxic liver injury and repair, coagulation and fibrin(ogen) biochemistry/function, and mouse modeling of liver disease. In our proposed studies we will: (Aim 1) Identify the mechanism whereby APAP-induced liver injury stimulates hepatic deposition of repair-promoting cross-linked fibrin(ogen); (Aim 2) Determine the role of fibrin(ogen) hemostatic function in repair of the APAP-injured liver; and (Aim 3) Determine the mechanism whereby fibrin(ogen) cross-linking drives pro-repair macrophage activity in vitro. The expected outcome of these Specific Aims is discovery of entirely novel mechanisms linking unique structural modification of the clotting protein fibrin(ogen) with macrophage-mediated liver repair. Identifying these mechanisms could pinpoint putative targets (e.g., TGM2, β2 integrin-fibrin(ogen) interaction), and novel agents, such as fibrinogen tailored to be pro-repair and free of thrombotic risk. Indeed, such major advances would provide entirely novel specific therapies to improve liver repair that would greatly improve patient outcomes.

项目总结 在美国，急性肝损伤和急性肝功能衰竭的主要原因是由 过量服用止痛药对乙酰氨基酚(APAP)。近50%的出现APAP的患者- 诱发性肝损伤需要昂贵的住院费用，以及现有治疗方法的疗效(即N- 乙酰半胱氨酸)对APAP过量后症状良好的患者非常有限。APAP过量患者会 从最大化肝脏修复途径的治疗中获益最多，例如Proe-Pr空气巨噬细胞激活。 我们最近发现了APAP肝毒性后一种值得注意的肝修复途径，即 凝血蛋白纤维蛋白(原)沉积在人和小鼠受损的肝脏中，与β2整合素和 引导局部促进修复的巨噬细胞活性。纤维蛋白(原)-β2整合素相互作用受到仔细调节 通过修改纤维蛋白(原)结构获得的。确定纤维蛋白(原)转化的机制 对于β2整合素配体，在肝损伤中诱导促修复巨噬细胞活性是至关重要的，因为这可能揭示 新的假定治疗靶点，以改善严重肝毒性患者的肝修复途径 急性肝功能衰竭。我们强有力的初步研究表明，与当前的范式相反，肝脏 急性毒性引起的纤维蛋白(原)蓄积与凝血活性无关。中环 构成这些研究的假设是，肝损伤刺激凝血不依赖的交联物 纤维蛋白原通过组织转谷氨酰胺酶-2(TGM2)形成一种新的纤维蛋白(原)复合体，推动巨噬细胞- 介导性肝修复。我们的方法包括缺乏特定纤维蛋白(原)的转基因小鼠 连接酶，表达具有特定功能突变的纤维蛋白(原)蛋白的小鼠，应用 凝血不敏感的纤维蛋白(原)作为一种假定的前修复治疗，一种独特的细胞培养系统 用独特的分子形式的纤维蛋白(原)检测原代巨噬细胞的激活，并分析纤维蛋白(原) 急性肝功能衰竭患者肝脏中的沉积物。调查小组由有毒物质专家组成 肝脏损伤和修复、凝血和纤维蛋白(原)生物化学/功能，以及肝脏疾病的小鼠模型。 在我们拟议的研究中，我们将：(目标1)确定APAP诱导的肝损伤刺激的机制 肝沉积促进修复的纤维蛋白(原)；(目标2)确定纤维蛋白(原)的作用 在APAP损伤的肝脏修复中的止血作用；和(目标3)确定其机制 纤维蛋白(原)在体外可促进巨噬细胞的修复活性。这些具体措施的预期结果 AIMS是发现与凝血蛋白的独特结构修饰相联系的全新机制 纤维蛋白(原)与巨噬细胞介导的肝修复。识别这些机制可以准确地确定 靶点(例如，TGM2、β2整合素-纤维蛋白(原)相互作用)，以及新的药物，如为 有利于修复，没有血栓风险。事实上，这样的重大进步将提供完全新颖的具体 改善肝脏修复的治疗方法将极大地改善患者的预后。