Microbiome and Nutrition in Severe PARDS

项目总结 严重儿科急性呼吸窘迫综合征(PARDS)是一种危及生命的疾病，具有高度的 死亡率(33%)。在这种情况下，提高死亡率的新疗法至关重要。多项回顾研究 已经证明早期肠内营养(EEN)和 PARDS儿童死亡率降低，但这种联系的机制尚不清楚。串扰 肺脏和肠道微生物群之间是EEN降低Pards死亡率的一个潜在机制。 饮食可以迅速改变有益的丁酸共生肠道细菌的相对丰度 增加粪便丁酸盐。在ARDS动物模型中，丁酸盐预治疗可减少肺部炎症和 受伤。我们假设，在重症PARDS中，EEN增加了产生丁酸盐的肠道的相对丰富程度 从而提高丁酸水平，减少急性肺部炎症和损伤。En是一种 改善这些儿童预后的新途径。由美国国立卫生研究院资助的多中心展望研究 临床试验，将随机选择1000名患有严重皮肤病的儿童，以比较体位和呼吸策略 以改善患者的预后。这项临床试验提供了一个独特的机会来研究潜在的 EEN作为改善重症儿童预后的有针对性的方法的机械性基础 扑克牌。我们将进行这项研究，作为前景研究的辅助研究。我们的具体目标是 研究内容为：目的1：验证丁酸产生粪便细菌的相对丰度假设， 严重PARDS患者的粪便丁酸盐和患者预后因EEN暴露而不同。我们会拿到粪便 180例患者在机械通气0-7天的标本，以评估EEN的效果和类型 En(±益生元)对肠道微生物组的签名用16S rRNA基因测序。我们将评估 EEN和EEN类型测定的粪丁酸和其他短链脂肪酸(SCFA)的差异。vt.在.上 粪便样本的子集，我们将使用全基因组鸟枪式元基因组测序(WGS)来鉴定 产丁酸共生菌的种类和菌株对PARDS患者很重要。目标2：实现 检验下呼吸道炎症、急性肺损伤和先天免疫细胞 严重PARDS患者的基因表达模式因粪便中SCFA浓度的不同而不同。我们将获得 在PARDS的第0天和第3天，从AIM 1患者的气管内抽吸样本来测试 粪便SCFA和关键细胞因子与PARDS肺病理生理学和PARDS关键生物标志物的关系 急性肺损伤。我们将利用全气管抽吸单核RNAseq(SnRNASeq)进行基因比对 丁酸粪便患者气管吸液免疫细胞群的表达模式。这项研究将 提高我们对EEN如何改善临床预后的机制基础的理解 扑克牌。产生丁酸盐的共生菌的丢失可能被证明是风险的关键诊断读数 评估或确定潜在的基于微生物的治疗方法，以改善患有PARDS的儿童的预后。

PROJECT SUMMARY Severe Pediatric Acute Respiratory Distress Syndrome (PARDS) is a life-threatening condition with high mortality (33%). Novel therapies to improve mortality in this condition are critical. Multiple retrospective studies from our group and others have demonstrated an association between early enteral nutrition (EEN) and decreased mortality in children with PARDS, but mechanisms for this association are unclear. Crosstalk between the lung and gut microbiome is a potential mechanism by which EEN may reduce PARDS mortality. Diet can rapidly alter the relative abundance of beneficial butyrate-producing commensal gut bacteria to increase fecal butyrate. In animal models of ARDS, butyrate pre-treatment decreases lung inflammation and injury. We hypothesize, that in severe PARDS, EEN increases relative abundance of butyrate producing gut commensals, thereby increasing butyrate levels and reducing acute lung inflammation and injury. EEN is a novel pathway to improve outcomes in these children. The PROSpect study, a multi-center, NIH-funded clinical trial, will randomize 1000 children with severe PARDS to compare positioning and ventilation strategies to improve patient outcomes. This clinical trial presents a unique opportunity to investigate potential mechanistic underpinnings of EEN as a targeted approach to improve outcomes for children with severe PARDS. We will conduct our study as an ancillary study to the PROSpect study. The specific aims of our study are: Aim 1:To test the hypothesis that relative abundance of butyrate producing fecal bacteria, fecal butyrate, and patient outcomes differ by EEN exposure in severe PARDS. We will obtain fecal specimens from 180 patients on days 0-7 of mechanical ventilation to assess the effect of EEN and type of EEN ( ± prebiotics) on the gut microbiome signature with 16S rRNA gene sequencing. We will assess differences in measured fecal butyrate and other short chain fatty acids (SCFA) by EEN and type of EEN. On a subset of fecal samples, we will use whole genome shotgun metagenomics sequencing (WGS) to identify species and strains of butyrate-producing commensal bacteria important in patients with PARDS. Aim 2: To test the hypothesis that lower respiratory tract inflammation, acute lung injury, and innate immune cell gene expression patterns differ by fecal SCFA concentration in severe PARDS. We will obtain endotracheal aspirate specimens from patients in Aim 1 on PARDS days 0 and 3 to test associations between fecal SCFA and critical cytokines implicated in PARDS lung pathophysiology, and key biomarkers of PARDS acute lung injury. We will utilize whole tracheal aspirate single nuclei RNASeq (snRNASeq) to compare gene expression patterns for tracheal aspirate immune cell populations in patients by fecal butyrate. This study will improve our understanding of the mechanistic underpinnings for how EEN may improve clinical outcomes of PARDS. Loss of butyrate producing commensal bacteria may prove to be a critical diagnostic readout for risk assessment or to identify potential microbial-based treatment to improve outcomes for children with PARDS.