Role of short chain fatty acids in intestinal barrier maturation in preterm infants

项目摘要 坏死性小肠结肠炎（NEC）是一种危及生命的胃肠道（GI）急症， 婴儿死亡率高达30- 50%。“肠漏”，或肠屏障不成熟，伴有肠壁升高 在早产新生儿中，血管通透性（IP）是NEC易感性的近因。泄漏的早期检测 肠道对于识别有NEC风险的婴儿以预防和降低疾病严重程度至关重要。无临床因素， 已经描述了单独或组合的常规实验室测试或生物标志物， 肠屏障功能受损的新生儿NEC风险增加。本研究的目的是 开发一种快速、非侵入性的筛查工具，在NEC发病前识别“高危”早产儿。我们 最近发现肠屏障的快速成熟与临床因素密切相关， 早期母乳喂养，抗生素暴露较少，月经后年龄较晚， 梭菌目和双歧杆菌的丰度和代谢活性。虽然丁酸生产 梭菌目与加强肠上皮屏障和减少肠上皮细胞的增殖有关。 炎症，不知道丁酸和潜在的其他短链脂肪酸（SCFA）是否 与新生儿肠屏障成熟有关。我们的初步数据显示丁酸生产 在低IP受试者中，丙酮酸/乙酰辅酶A途径，特别是丙酮酸/乙酰辅酶A途径显著更丰富。在这 研究中，我们建议验证粪便微生物和/或代谢生物标志物的经证实的措施 结合相关新生儿因素进行快速、非侵入性筛查试验。我们假设， 代谢活动的水平，特别是丁酸盐的产生和可能的其他SCFA，通过增加 梭菌和双歧杆菌的定植与早产儿肠屏障成熟相关 新生儿。为了解决我们的假设，我们将利用从约200人的队列中收集的现有粪便样本， 早产儿（<33周），对于他们来说，微生物群（16 S rRNA基因测序）和IP（尿液非代谢） 糖探针（乳果糖和鼠李糖）是可用，并提出了2个目的：1）确定粪便代谢 与早产新生儿肠屏障成熟相关的活动<33周妊娠;和2） 鉴定和表征与早产儿肠通透性相关丁酸盐产生细菌 新生儿在生命的前7-10天。在研究完成后，我们将确定生物标志物 与健康的肠屏障功能和准确分类的判别方案有关。 高或低IP组。我们的长期目标是进行一项随机临床试验， NEC早期预防干预。筛选工具的完善将识别出异常漏尿的婴儿。 肠道，一个必要的先决条件，为后续的合理设计的新的战略，如临床试验， 益生菌促进健康肠道屏障功能，降低NEC发病率。

PROJECT SUMMARY Necrotizing enterocolitis (NEC) is a life-threatening, gastrointestinal (GI) emergency affecting 7-10% of preterm infants with mortality as high as 30-50%. "Leaky gut", or intestinal barrier immaturity with elevated intestinal permeability (IP), is the proximate cause of susceptibility to NEC in preterm neonates. Early detection of leaky gut is essential to identify infants at risk for NEC to prevent and reduce disease severity. No clinical factor, routine laboratory test or biomarker alone or in combination have been described that identify preterm neonates with impaired intestinal barrier function who at increased risk for NEC. The goal of this study is to develop a rapid, non-invasive screening tool to identify “at-risk" preterm infants prior to the onset of NEC. We recently revealed rapid maturation of the intestinal barrier is strongly associated with clinical factors such as early breastmilk feeding, less antibiotic exposure and later post-menstrual age, and significantly higher abundance and metabolic activities of Clostridiales and Bifidobacterium. Although the butyrate producing Clostridiales have been implicated in strengthening the intestinal epithelial barrier and reducing intestinal inflammation, it is unknown whether butyrate and potentially other short chain fatty acids (SCFAs) are associated with neonatal intestinal barrier maturation. Our preliminary data revealed butyrate production pathways, in particular Pyruvate/Acetyl-CoA pathway are significantly more abundant in low IP subjects. In this study, we propose to validate a substantiated measure of fecal microbial and/or metabolic biomarkers combined with associated neonatal factors for a rapid, non-invasive screening test. We postulate that the level(s) of metabolic activities, particularly butyrate production and potentially other SCFAs via increased colonization of Clostridiales and Bifidobacterium, are associated with intestinal barrier maturation in preterm neonates. To address our hypothesis, we will leverage existed stool samples collected from a cohort of ~200 preterms (<33 weeks), for whom both microbiota (16S rRNA gene sequencing) and IP (urine non-metabolized sugar probes lactulose and rhamnose) are available, and propose 2 aims: 1) to determine fecal metabolic activities associated with intestinal barrier maturation in preterm neonates <33 weeks gestation; and 2) to identify and characterize butyrate-producing bacteria associated with intestinal permeability in preterm neonates during the first 7-10 days of life. At the completion of the study, we will determine the biomarkers associated with healthy intestinal barrier functions and the discriminatory scheme for accurate classification of high or low IP group. Our long-term goal is to conduct a randomize clinical trial of rationally designed intervention for NEC early prevention. Refinement of the screening tool will identify infants with aberrant leaky gut, an essential prerequisite for subsequent rational design of novel strategies such as clinical trials of probiotics to promote healthy intestinal barrier functions to reduce NEC incidence.