Microthrombus Formation Triggers Lung Injury in Sepsis

脓毒症中微血栓形成引发肺损伤

• 批准号: 8258193
• 负责人: BRUCE Allan HARMS
• 金额: --
• 依托单位: WM S. MIDDLETON MEMORIAL VETERANS HOSP
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258193
• 关键词: Abdomen; Acute; Acute Lung Injury; Address; Adult Respiratory Distress Syndrome; Affect; Air; Alveolar; Animals; Anticoagulants; Appearance; Area; Bacteria; Bacterial Translocation; Bacteroides fragilis; Blood; Blood Coagulation Disorders; Blood Vessels; Blood capillaries; Caliber; Cells; Cessation of life; Cicatrix; Clinical; Clinical Trials; Complication; Consumption; Cytotoxic agent; Data; Development; Disease; Epithelial; Erythrocytes; Escherichia coli; Event; FCGR3B gene; Factor Va; Frequencies; Generations; Goals; Healthcare; Hemorrhage; Hour; Immunofluorescence Immunologic; Inflammatory Bowel Diseases; Inflammatory Response; Injury; Intestines; Intra-abdominal; Intravenous infusion procedures; Invaded; Label; Laboratories; Latex Particles; Lead; Lepirudin; Leukocytes; Life; Location; Low-Molecular-Weight Heparin; Lung; Lymph; Manufacturer Name; Measures; Mechanical ventilation; Mediating; Methodology; Methods; Microcirculation; Modeling; Organ failure; Outcome; Pathway interactions; Patients; Pattern; Peptide Hydrolases; Perfusion; Pharmaceutical Preparations; Physiological; Plasma; Prevention; Property; Protein C; Pulmonary Circulation; Pulmonary Edema; Pulmonary alveolar structure; Rat-1; Rattus; Reaction; Recombinants; Reperfusion Injury; Reporting; Resistance; Respiratory Failure; Respiratory distress; Resuscitation; Risk; Risk Factors; Role; Sampling; Sepsis; Solutions; Structure of parenchyma of lung; Surgical complication; System; Testing; Text; Therapeutic; Thrombin; Thromboxane Receptor; Thromboxanes; Thrombus; Time; Tissues; Trauma; United States Food and Drug Administration; Veterans; Vitamin K; Western Blotting; Whole Blood; activated Protein C; analytical method; arteriole; capillary; clinically relevant; combat; drotrecogin alfa; effective therapy; experience; improved; injured; innovation; insight; lung injury; meetings; mortality; neutrophil; particle; patient population; prevent; public health relevance; septic; venule

DESCRIPTION (provided by applicant): PROBLEM: Septic lung injury is an often-fatal complication of numerous clinical conditions, and affects a significant percentage of the VA patient population. This injury is characterized by gross cellular damage to the lung alveoli, which allows red cells and plasma to enter the alveolar air space. This acute injury often leads to permanent scarring of the lung. It is widely believed that cytotoxic agents released by neutrophils, the white blood cells that invade the lung during sepsis, cause the initial alveolar injury. However, the trigger that causes this neutrophil invasion is unknown. We hypothesize that the trigger is microthrombus formation within alveolar capillaries early in sepsis, and further hypothesize that agents that prevent microthrombus formation may prevent the neutrophil invasion and minimize the injury. SPECIFIC AIMS: 1) Measure thrombus formation within lung microvessels early in sepsis, and measure their effects on the distribution of alveolar perfusion: We will use a clinically relevant live bacteria model to induce sepsis in rats, and use immunofluorescence to measure microthrombus formation in alveolar capillaries. At various times during sepsis development, we will correlate microthrombus location with trapping patterns of small-diameter fluorescent latex particles infused into lung capillaries to determine the association between microthrombus formation and alveolar perfusion, which we have shown is markedly mal-distributed in sepsis. 2) Show that neutrophil sequestration into the lung occurs only after microthrombus formation: We will use immunofluorescence to label microthrombi and neutrophils in lung tissue at various times after sepsis induction, to show that microthrombus formation precedes neutrophil invasion. 3) Show that prevention of thrombus formation prevents neutrophil sequestration, and prevents lung injury: low molecular weight heparin, recombinant hirudin, and recombinant activated protein C have anti-thrombotic properties that prevent microthrombus formation. We therefore aim to show if administration of these agents in sepsis prevents microthrombus formation and prevents subsequent neutrophil invasion of the lungs. 4) Determine the role of thromboxane in control of capillary perfusion during sepsis: thromboxane alters lung microvascular perfusion in a manner similar to sepsis, and is known to be secreted by neutrophils. We will use immunofluorescence to label thromboxane and neutrophils in the lungs of septic rats, then measure perfusion distribution in neutrophil- and thromboxane-positive regions to determine if regions positive for neutrophils and thromboxane have less perfusion than regions with fewer neutrophils. POTENTIAL IMPACT ON VETERANS' HEALTH CARE: Sepsis can occur as a result of abdominal combat injuries, a perforated bowel, inflammatory bowel disease, or other surgical complications. The resulting lung injury often causes these patients to experience very high rates of mortality. Our proposed studies therefore address a highly veteran-centric clinical problem, and have great potential to improve veterans' health care. PUBLIC HEALTH RELEVANCE: Narrative (Relevance Statement) Identifying the initial event that initiates lung injury in sepsis may be the best way to address methods to prevent this devastating and often fatal disease. Unfortunately, this is a subject about which little is known. Our studies will provide new insight into this fundamental aspect of the lung's reaction to sepsis. We believe this is crucial to the development of successful therapeutic strategies for VA patients. VA data show that approximately 10,000 patients are stricken annually with ARDS, respiratory failure, and pulmonary edema throughout the VA system. These are conditions that are frequently caused by sepsis-associated lung injury. These often-fatal conditions effect lung endothelial and epithelial barrier function in ways that allow plasma and whole blood to enter the alveolar air space. If we can identify the initial incident that begins the cascade of events that characterize lung injury in sepsis, we have a better chance of developing effective treatments for these often-fatal conditions. This is the goal of our proposed studies.

描述（由申请人提供）： 问题：化脓性肺损伤是多种临床病症中常见的致命并发症，影响很大一部分 VA 患者群体。这种损伤的特点是肺泡细胞受到严重损伤，导致红细胞和血浆进入肺泡气隙。这种急性损伤通常会导致肺部永久性疤痕。人们普遍认为，中性粒细胞（脓毒症期间侵入肺部的白细胞）释放的细胞毒性剂导致最初的肺泡损伤。然而，导致中性粒细胞入侵的触发因素尚不清楚。我们假设触发因素是脓毒症早期肺泡毛细血管内的微血栓形成，并进一步假设防止微血栓形成的药物可以阻止中性粒细胞入侵并最大程度地减少损伤。具体目标： 1) 测量脓毒症早期肺微血管内的血栓形成，并测量其对肺泡灌注分布的影响：我们将使用临床相关的活细菌模型诱导大鼠脓毒症，并使用免疫荧光测量肺泡内的微血栓形成毛细血管。在脓毒症发展过程中的不同时间，我们将微血栓位置与注入肺毛细血管的小直径荧光乳胶颗粒的捕获模式相关联，以确定微血栓形成与肺泡灌注之间的关联，我们已经证明微血栓在脓毒症中分布明显不均匀。 2）证明中性粒细胞仅在微血栓形成后才进入肺部：我们将在脓毒症诱导后的不同时间使用免疫荧光标记肺组织中的微血栓和中性粒细胞，以表明微血栓形成先于中性粒细胞侵袭。 3) 表明预防血栓形成可防止中性粒细胞隔离，并预防肺损伤：低分子肝素、重组水蛭素和重组活化蛋白C具有抗血栓特性，可防止微血栓形成。因此，我们的目的是证明在脓毒症中使用这些药物是否可以防止微血栓形成并防止随后的中性粒细胞侵入肺部。 4）确定血栓素在脓毒症期间控制毛细血管灌注中的作用：血栓素以与脓毒症类似的方式改变肺微血管灌注，并且已知由中性粒细胞分泌。我们将使用免疫荧光标记脓毒症大鼠肺部的血栓素和中性粒细胞，然后测量中性粒细胞和血栓素阳性区域的灌注分布，以确定中性粒细胞和血栓素阳性区域的灌注是否比中性粒细胞较少的区域少。对退伍军人医疗保健的潜在影响：腹部战斗损伤、肠穿孔、炎症性肠病或其他手术并发症可能导致脓毒症。由此产生的肺损伤通常会导致这些患者的死亡率非常高。因此，我们提出的研究解决了一个高度以退伍军人为中心的临床问题，并且具有改善退伍军人医疗保健的巨大潜力。 公共卫生相关性： 叙述（相关性陈述） 确定引发败血症肺损伤的初始事件可能是解决预防这种破坏性且往往致命的疾病的最佳方法。不幸的是，这是一个鲜为人知的主题。我们的研究将为肺部对脓毒症反应的这一基本方面提供新的见解。我们相信这对于为 VA 患者制定成功的治疗策略至关重要。 VA 数据显示，整个 VA 系统每年约有 10,000 名患者患有 ARDS、呼吸衰竭和肺水肿。这些是脓毒症相关肺损伤经常引起的病症。这些通常是致命的疾病会影响肺内皮和上皮屏障功能，使血浆和全血进入肺泡气隙。如果我们能够确定引发脓毒症肺损伤一系列事件的最初事件，我们就有更好的机会为这些往往致命的疾病开发有效的治疗方法。这是我们提出的研究的目标。