Viral-induced Adaptation of Neutrophil Response in ARDS

描述（由申请人提供）： 急性呼吸窘迫综合征（ARDS）是一种对广泛的感染性损伤的失调反应。然而，在具有明显相似风险因素的个体之间，疾病发生和严重程度存在巨大差异。在ARDS的发病机制中，中性粒细胞快速和大量积聚到空气中是最先确定的事件之一，并且可能随之发生对细菌感染的过度兴奋、无效和/或不适当的反应。我们假设病毒感染可间接引起中性粒细胞对病原菌反应的短暂损伤，导致嗜中性粒细胞介导的肺部炎症和损伤增强。病毒诱导I型干扰素（IFN α/γ）的释放，其反过来上调被称为干扰素刺激基因（ISG）的基因家族的表达。在初步研究中，我们发现大约四分之一的有ARDS风险的患者在其循环中性粒细胞中表现出显著升高的ISG表达，并且ISG上调与离体中性粒细胞应答表型受损和患者更严重的临床结果相关。这一假设将在对ARDS患者的分离中性粒细胞和全血的研究中进行测试，这些研究将参加由NHLBI ARDS临床网络赞助的两项即将进行的治疗试验。具体目的是：1）在ARDS患者中检测中性粒细胞干扰素刺激基因（ISG）上调对疾病严重程度和结果的临床参数的影响。2)在从ARDS患者分离的中性粒细胞中进行的促炎试验，ISG上调对促炎刺激和活细菌的细胞应答的影响。3)在ARDS患者中进行的蛋白酶试验：全血中ISG上调作为病毒感染和更严重临床过程的生物标志物的预测价值。分离的中性粒细胞和全血中的ISG上调将通过原型ISG的真实的时间PCR定量以及中性粒细胞信号传导和对细菌感染的有效先天应答至关重要的功能性质的分析来确定。该建议是“时间敏感的”，因为中性粒细胞反应必须在分离时用活细胞进行分析。长期以来，人们一直观察到正在进行的、正在消退的或未确诊的病毒感染使患者易患严重且往往致命的细菌感染的能力，但这些事件的机制在很大程度上尚不清楚。如果成功的话，这个建议将确定一种机制，通过这种机制，病毒可以介导更严重的结果在ARDS，并将测试的效用升高ISG表达作为一个标志物的预后不良。确定病毒诱导的早期免疫失调发生的机制对于设计ARDS的治疗策略和解释在这种非常复杂的情况下对治疗的反应都是至关重要的。(End摘要）

DESCRIPTION (provided by applicant): The Acute Respiratory Distress Syndrome (ARDS) is a dysregulated response to a broad range of infectious insults. However, tremendous variability in disease occurrence and severity is seen between individuals with apparently similar risk factors. Rapid and massive accumulation of neutrophils to the airspace is one of the first identifiable events in the pathogenesis of ARDS, and overexuberant, ineffective, and/or inappropriate responses to a bacterial infection may ensue. We hypothesize that viral infections can indirectly evoke a transient impairment of the neutrophil response to pathogenic bacteria, resulting in enhanced neutrophil-mediated lung inflammation and injury. Viruses induce the release of Type I Interferons (IFNa/¿), which in turn upregulate expression of a family of genes referred to as the Interferon Stimulated Genes (ISG). In preliminary studies, we have found approximately one quarter of patients at risk for ARDS demonstrate significantly elevated ISG expression in their circulating neutrophils, and that ISG upregulation is associated with an impaired neutrophil response phenotype ex vivo and a more severe clinical outcome in patients. This hypothesis will be tested in studies of isolated neutrophils and whole blood from ARDS patients that will be enrolled in two upcoming therapeutic trials sponsored by the NHLBI ARDS Clinical Network. The specific aims are to 1) Prospectively test in ARDS patients the effect of neutrophil Interferon Stimulated Gene (ISG) upregulation on clinical parameters of disease severity and outcome. 2) Prospectively test in neutrophils isolated from ARDS patients the effect of ISG upregulation on cellular response to pro-inflammatory stimuli and live bacteria. 3) Prospectively test in ARDS patients the predictive value of ISG upregulation in whole blood as a biomarker of viral infection and a more severe clinical course. ISG upregulation in isolated neutrophils and whole blood will be determined by real time PCR quantification of prototypical ISG, and analysis of neutrophil signaling and functional properties central to an effective innate response to bacterial infection. The proposal is "time sensitive", as neutrophil response must be analyzed with viable cells at the time of isolation. The capacity of ongoing, resolving or undiagnosed viral infections to predispose patients to severe and often lethal bacterial infections has long been observed, but the mechanisms of these events are largely unknown. If successful, this proposal will identify a mechanism by which viruses can mediate a more severe outcome in ARDS, and will test the utility of elevated ISG expression as a marker of worse prognosis. Identifying mechanisms by which viral-induced dysregulation of early immunity occurs is essential both to designing therapeutic strategies for ARDS, and to interpret response to treatment in this remarkably complex condition. (End of Abstract)