Role of Macrophage Efferocytosis in Ozone-Induced ARDS

项目总结/摘要 急性呼吸窘迫综合征（ARDS）是间接应激的后遗症 全身感染（败血症/内毒素血症）对肺部的影响。然而，目前尚不清楚为什么只有一些患者 败血症发展为ARDS。脓毒症患者发生ARDS的一个可能危险因素是暴露于空气中 臭氧等污染物。最近，FDA可接受的臭氧暴露的环境水平已经被确定。 与急性呼吸窘迫综合征的发展有直接关系。我们的总体目标是阐明 暴露于氧化剂如臭氧后发生ARDS的风险增加。在某种程度上， 由于死亡和垂死的中性粒细胞和嗜中性粒细胞衍生的促炎性凋亡小体的积累， 在肺部。在体内平衡条件下，巨噬细胞通过称为 红细胞增多症。我们假设臭氧暴露后ARDS的风险增加是由于受损 红细胞增多症。此外，这在具有肺聚集蛋白遗传缺陷的个体中加剧， 表面活性剂蛋白D（SPD），其控制巨噬细胞吞噬。为了验证这一点，我们开发了一种新的 实验模型，其中小鼠暴露于吸入的臭氧，随后静脉内（i. v.） 脂多糖（LPS），一种在脓毒症（内毒素血症）期间释放到血液中的细菌来源的毒素。我们 目的是（1）确定臭氧暴露和SPD活性降低是否会加剧炎症和急性 肺损伤（ALI）通过损害巨噬细胞吞噬细胞和（2）确定是否降低SPD活性 加剧臭氧诱导的人类巨噬细胞巨噬细胞增多症的损害。野生型和肺特异性 条件性SPD敲除小鼠将用臭氧随后用LPS处理。巨噬细胞增多症 通过流式细胞术测量。与氧化应激相关的机制途径，这在 臭氧毒性，将使用RNA测序（RNAseq）进行鉴定。我们将分析肺部炎症， 根据人类受试者中的单核苷酸多态性分层， SPD基因，控制臭氧暴露后。这些实验的结果将提供新的 对臭氧暴露、巨噬细胞功能、SPD变化和 易患ARDS。这些研究意义重大，因为臭氧等氧化剂被认为是 ARDS的危险因素。实验，课程，和结构化的指导建议， 该申请将为NIH R 01拨款提供基础，并启动PI的独立职业生涯。 翻译研究

Project Summary/Abstract Acute respiratory distress syndrome (ARDS) develops in some individuals as a sequela to indirect stress on the lung from systemic infection (sepsis/endotoxemia). However, it is unclear why only some patients with sepsis develop ARDS. One possible risk factor leading to ARDS in patients with sepsis is exposure to air pollutants such as ozone. Recently, FDA acceptable environmental levels of ozone exposure have been directly linked to the development of ARDS. Our overall goal is to elucidate the mechanisms underlying the increased risk of developing ARDS following exposure to oxidants such as ozone. ARDS develops, in part, due to an accumulation of dead and dying neutrophils and neutrophil-derived proinflammatory apoptotic bodies in the lung. Under homeostatic conditions, these are removed by macrophages via a process known as efferocytosis. We hypothesize that the increased risk of ARDS following ozone exposure is due impaired efferocytosis. Moreover, this is exacerbated in individuals with genetic deficits in the pulmonary collectin, surfactant protein D (SPD), which controls macrophage efferocytosis. To test this, we developed a novel experimental model in which mice are exposed to inhaled ozone followed by intravenous (i.v.) lipopolysaccharide (LPS), a bacterial-derived toxin released into the blood during sepsis (endotoxemia). Our aims are to (1) Determine if ozone exposure and decreased SPD activity exacerbate inflammation and acute lung injury (ALI) by impairing macrophage efferocytosis and (2) Determine if decreased SPD activity exacerbates ozone-induced impairment of macrophage efferocytosis in humans. Wild type and lung-specific conditional SPD knock out mice will be treated with ozone followed by LPS. Macrophage efferocytosis will be measured by flow cytometry. The mechanistic pathways associated with oxidative stress, which is important in ozone toxicity, will be identified using RNA sequencing (RNAseq). We will analyze lung inflammation and macrophage efferocytosis in human subjects, stratified according to single nucleotide polymorphisms within the SPD gene, following controlled ozone exposure. The results of these experiments will provide novel mechanistic insights into the relationship between ozone exposure, macrophage function, SPD variation, and susceptibility to ARDS. These studies are significant, as oxidants such as ozone have been implicated as a risk factor the development of ARDS. The experiments, coursework, and structured mentorship proposed in this application will provide the basis for an NIH R01 grant and initiate the PI's career in independent translational research.