Microthrombus Formation Triggers Lung Injury in Sepsis

脓毒症中微血栓形成引发肺损伤

• 批准号: 7680461
• 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/7680461
• 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：脓毒症肺损伤通常是众多临床状况的致命并发症，并影响了VA患者人群的很大一部分。这种损伤的特征是细胞对肺肺泡的严重损害，这使红细胞和血浆可以进入肺泡空气空间。这种急性损伤通常会导致肺部永久性疤痕。人们普遍认为，嗜中性粒细胞释放的细胞毒性剂是败血症期间侵袭肺部的白细胞，导致初始肺泡损伤。但是，导致这种中性粒细胞侵袭的触发因素尚不清楚。我们假设触发是败血症早期肺泡毛细血管内的微隆形成，并进一步假设预防微瘤形成的药物可以防止中性粒细胞侵袭并最大程度地减少损伤。具体目的：1）测量败血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：我们将使用临床上相关的活细菌模型在大鼠中诱导脓毒症，并使用免疫荧光来测量肺泡在肺泡形成中毛细血管。在败血症发育过程中的不同时间，我们将将微雄肉地的位置与注入肺毛细血管中的小直径荧光乳胶颗粒的捕获模式相关联，以确定微骨形成与肺泡灌注之间的关联，我们已经显示出这些相关性在SEPSI中明显地分布在脓毒症中。 2）表明，嗜中性粒细胞螯合仅在微肉汤形成后发生：我们将在脓毒症诱导后的不同时间使用免疫荧光在肺组织中标记微纤维状和嗜中性粒细胞，以表明微肉汤形成在中性粒细胞增多症之前。 3）表明预防血栓形成可防止嗜中性粒细胞搁置，并防止肺损伤：低分子量肝素，重组息肉和重组活化蛋白C具有防止微骨形成的抗凝血性特性。因此，我们旨在证明败血症中这些药物的给药是否阻止了微树形成，并防止了随后的中性粒细胞侵袭肺。 4）确定血栓烷在败血症过程中控制毛细血管灌注方面的作用：血栓烷以类似于败血症的方式改变肺微血管灌注，并被嗜中性粒细胞分泌。我们将使用免疫荧光来标记败血大鼠肺中的血栓烷和嗜中性粒细胞，然后测量中性粒细胞和血栓烷阳性区域中的灌注分布，以确定中性粒细胞和血栓烷阳性的区域是否比中性粒细胞更少的区域灌注较小。对退伍军人的医疗保健的潜在影响：败血症可能是由于腹部战斗损伤，穿孔性肠，炎症性肠病或其他手术并发症而发生的。由此产生的肺损伤通常会导致这些患者的死亡率很高。因此，我们提出的研究解决了一个高度以资深的临床问题的问题，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）识别败血症发起肺损伤的初始事件可能是解决这种毁灭性疾病和经常致命疾病的方法的最佳方法。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败血症的反应的这一基本方面提供新的见解。我们认为，这对于VA患者的成功治疗策略至关重要。 VA数据显示，整个VA系统中，每年大约有10,000名患者每年遭受ARDS，呼吸衰竭和肺水肿。这些疾病通常是由败血症相关的肺损伤引起的。这些通常致命的条件以允许血浆和全血进入肺泡空气空间的方式影响肺内皮和上皮屏障功能。如果我们可以确定开始败血症中肺损伤的级联事件的初始事件，那么我们就有更好的机会为这些通常的致命状况开发有效的治疗方法。这是我们提出的研究的目标。