Modest supplemental oxygen worsens lung injury in a murine model of sepsis

描述（由申请人提供）：急性肺损伤（ALI）和急性呼吸窘迫综合征（ARDS）与高发病率和死亡率相关，给医疗保健系统带来了巨大负担。脓毒症是ALI的常见原因，因此脓毒症引起的肺损伤的研究至关重要。使用全身性脂多糖（LPS），我们观察到主要是间质性肺损伤，伴有肺泡中性粒细胞缺乏和损伤，这与直接肺损伤中观察到的明显肺泡损伤和中性粒细胞内流有显着不同。沿着理解小鼠中直接和间接损伤之间的差异的方式，我们假设与单独的LPS或50%氧气相比，50%氧气在全身性损伤后会增加小鼠的肺损伤。我们的损伤模型包括LPS，12小时后暴露于50%或21%的氧气60小时。在第3天，与其他组相比，暴露于LPS加氧的小鼠显示出协同增加的肺损伤，具有突出的肺泡成分。我们假设，添加50%的氧气LPS增加氧化应激和炎症细胞因子的产生，从而增加肺损伤，损伤可以减轻抗氧化治疗。我们计划研究这个假设的各个方面，有以下两个目标：1。研究LPS和补充氧气联合暴露导致肺损伤加重的潜在机制。将评估暴露于LPS、50%氧气或LPS加氧气的小鼠的死亡率、体重减轻; BAL细胞计数、分类、总蛋白、肺湿重;和组织学。此外，我们将测量：细胞内和细胞外ROS的产生;肺抗氧化酶水平; BAL/肺细胞因子;和肺泡细胞凋亡在规定的时间间隔。在体外，我们将孵育幼稚肺泡巨噬细胞（AM）和树突状细胞（DC）与LPS，50%的氧气，或组合，并测量ROS的生产和关键炎症介质先前确定。2.确定NAc治疗同时补充氧气是否能消除肺损伤，并检查该作用的潜在机制。将按照目标1对各组给予NAc或对照，并评估对损伤模式的影响。此外，我们还将研究Aim 1研究结果所指示的细胞因子和抗氧化剂潜在途径，以及时间和细胞特异性ROS和凋亡活性。公共卫生相关性：系统性疾病可能导致需要住院治疗的肺部严重损伤和死亡。我们将在动物模型中研究适度氧气作为损伤的潜在放大器的作用。这项工作有可能改善人类的结果，减轻这种毁灭性疾病对医疗保健系统的负担。

DESCRIPTION (provided by applicant): Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are associated with high levels of morbidity and mortality, imposing a substantial burden on the health care system. Sepsis is a frequent cause of ALI making the study of sepsis-induced lung injury crucial. Using systemic lipopolysaccharide (LPS) we observed predominantly interstitial lung injury with a paucity of alveolar neutrophils and damage, dramatically different from the prominent alveolar injury and neutrophil influx seen with direct lung injury. Along the way to understanding the difference between direct and indirect injury in mice, we postulated that 50% oxygen would augment lung injury in mice after systemic insult compared to LPS or 50% oxygen alone. Our injury model consists of LPS followed 12 hrs later by exposure to 50% or 21% oxygen for 60 hrs. At day 3, mice exposed to LPS plus oxygen showed a synergistically increase lung injury, with a prominent alveolar component, compare to other groups. We hypothesize that the addition of 50% oxygen to LPS increases oxidative stress and inflammatory cytokine production, thereby augmenting lung injury, and that injury can be mitigated with antioxidant therapy. We plan to examine aspects of this hypothesis with following 2 aims: 1. To examine potential mechanisms driving the augmentation of lung injury by combined exposure to LPS and supplemental oxygen. Mice exposed to LPS, 50% oxygen, or LPS plus oxygen, will be assessed for mortality, weight loss; BAL cell counts, differentials, total protein, wet lung weight; and histology. In addition, we will measure: intracellular and extracellular ROS generation; lung anti-oxidant enzyme levels; BAL/Lung cytokines; and alveolar cell apoptosis at defined intervals. In vitro, we will incubate naive alveolar macrophages (AMs) and dendritic cells (DCs) with LPS, 50% oxygen, or in combination, and measure ROS production and key inflammatory mediators previously identified. 2. To determine if NAc therapy concurrent with supplemental oxygen abrogates lung injury, and examine potential mechanisms of that effect. NAc or control will be given to groups as in Aim 1, and the effect on injury patterns will be assessed. In addition, we will examine cytokine and anti-oxidant potential pathways indicated by Aim 1 findings, as well as time- and cell-specific ROS and apoptosis activity. Public Health Relevance: Significant injury to the lungs requiring hospitalization and death can occur from systemic illness. We will examine the role of moderate oxygen as a potential amplifier of that injury in an animal model. This work has the potential to improve human outcomes and decrease burden on the health care system from this devastating illness.