Bile acid metabolomics and metagenomics in short bowel syndrome

由于克罗恩病、缺血、创伤、坏死性手术切除引起的短肠综合征（SBS） 小肠结肠炎或其他疾病是美国发病率、死亡率和高医疗保健费用的主要原因。 短肠患者经常依赖于肠外营养来满足他们的部分或全部营养需求。 要求.在肠切除后，剩余的小肠上皮细胞在小肠上皮细胞中形成了适应性的 增加绒毛高度、隐窝深度并增强营养和电解质吸收的反应。的 拟议研究的最终目标是确定可以增强肠道适应性的干预措施， 减少或消除对肠外营养的依赖。对干细胞的特异性介质知之甚少 细胞/增殖和对肠切除的功能适应性反应。因此，一个未得到满足的关键需求 是了解调节肠道干细胞的信号通路（营养和微生物） 小肠切除术后与局部和管腔环境的相互作用。我们将使用 儿童和成人SBS患者，以测试总体假设，SBS患者， 从TPN中断奶表明与血清和粪便BA改变相关的微生物群落变化 代谢谱和信号传导，以及BA合成速率（C4测定），预测功能 肠道适应目的1将检验不同的微生物组和BA代谢谱以及 补偿性BA合成与成功的肠适应相关，并允许断奶， 独立性（PN）。目的2将检验与细胞凋亡相关的BA信号通路变化的假设。 在Aim 1中发现的肠道微生物组改变促进了肠道干细胞和隐窝细胞增殖（CCP）， 功能和代谢适应。因为成年人的适应持续长达2年， 切除，我们将研究这些代谢和环境信号因素的时间演变， SBS患者因此，我们的首要目标是确定关键的BA代谢组学和宏基因组学。 预测成功适应的变化，并使用信息丰富的临床前模型来识别 BA信号传导和茎/CCP和功能适应的机制。这一目标将得以实现 通过两个目标。目标1。鉴定宏基因组学和BA代谢组学（血液和粪便BA种类标记; 小肠切除术后2年内儿童和成人SBS患者的BA合成率），以及 定义它们与身体组成，肠干细胞/隐窝细胞增殖反应， 和临床结局，包括独立于PN。目标二。确定变化的机制 微生物组和BA信号代谢物的相关转变调节形态和功能 /代谢适应使用体外干/肠样培养物和gnotobiotic小鼠。Gnotobiotic Lgr 5eGFP小鼠 将接受来自PN断奶（适应者）患者的粪便微生物移植物灌胃， 不能断奶的人（非适应者），并评估收获能量的能力。正常和SBS患者股骨柄 细胞培养物将与胆汁酸代谢物的单独和组合以及高亲和力的 FXR配体和评估干细胞存活、肠样生长、出芽和形态分化。 总之，拟议的研究是重要的，因为它们将有助于确定可改变的管腔因子和胆汁 酸代谢途径，可以增强适应性，并导致创新的SBS疗法。

Short bowel syndrome (SBS) due to surgical resection for Crohn's disease, ischemia, trauma, necrotizing enterocolitis or other disorders is a major cause of morbidity, mortality and high health care costs in the U.S. Short bowel patients are frequently dependent on parenteral nutrition to meet some or all of their nutritional requirements. Following intestinal resection, the remaining small bowel epithelium mounts an adaptive response that increases villus height, crypt depth and enhances nutrient and electrolyte absorption. The ultimate goal of the proposed studies is to identify interventions that can enhance intestinal adaptation and thus reduce or eliminate dependence on parenteral nutrition. Little is known about specific mediators of the stem cell/proliferative and the functional adaptive response to intestinal resection. Accordingly, a critical unmet need is to understand the signaling pathways (nutritional and microbial) that modulate intestinal stem cell interactions with the local and luminal environments following small bowel resection. We will use cohorts of both pediatric and adult SBS patients to test the overarching hypothesis that SBS patients who successfully wean from TPN manifest shifts in microbial communities associated with altered serum and fecal BA metabolomic profiles and signaling, as well as BA synthesis rates (C4 determination) that predict functional intestinal adaptation. Aim 1 will test the hypothesis that distinctive microbiome and BA metabolic profiles and compensated BA synthesis are associated with successful intestinal adaptation and permit weaning and independence from (PN). Aim 2 will test the hypothesis that changes in BA signaling pathways associated with altered gut microbiome, identified in Aim 1, promote gut stem and crypt cell proliferation (CCP), as well as functional and metabolic adaptation. Because adaptation in adults continues for up to 2 years following resection, we will examine the temporal evolution of these metabolic and environmental signaling factors in SBS patients. Accordingly, our overarching objective is to identify key BA metabolomic and metagenomic changes that predict successful adaptation and to use informative preclinical models to identify the mechanisms of BA signaling and stem/CCP and functional adaptation. This objective will be accomplished through two aims. Aim 1. Identify metagenomic and BA metabolomic (blood and stool BA species signatures; BA synthesis rates) in pediatric and adult SBS patients for up to two years after small bowel resection, and define their functional relationships with body composition, intestinal stem/crypt cell proliferative responses, and clinical outcomes including independence from PN. Aim 2. Identify the mechanisms by which changes in the microbiome and the associated shift in BA signaling metabolites modulate morphologic and functional /metabolic adaptation using in vitro stem/enteroid cultures and gnotobiotic mice. Gnotobiotic Lgr5eGFP mice will be gavaged with fecal microbial transplants from patients who wean (adapters) from PN compared to those who cannot wean (non-adapters) and assessed for the ability to harvest energy. Normal and SBS patient stem cell cultures will be incubated with individual and combinations of bile acid metabolites as well as high affinity FXR ligands and assessed for stem cell survival, enteroid growth, budding and morphologic differentiation. Together the proposed studies are significant as they will help to identify modifiable luminal factors and bile acid metabolic pathways that may enhance adaptation and lead to innovative therapies for SBS.