Interactions of dietary protein intake and intestinal resident microbiota affecting susceptibility to persistent Giardia infection and Giardia mediated enteropathy

项目摘要 蓝氏贾第鞭毛虫属于一组与儿童发育和肠道功能受损相关的肠道病原体， 尤其是营养不良的儿童。虽然这些儿童中的大多数贾第虫感染在临床上是 安静，贾第虫可能会导致长期腹泻。由于未知的原因，这些孩子中的许多人不能 清除寄生虫此外，受感染的儿童可能因贾第虫感染而面临肠道功能障碍的风险， 即使他们没有症状。我们假设贾第虫的易感性和随后的疾病是由 由于饮食中蛋白质含量低，肠道微生物群落发生变化。动物模型 提供了一个机会来剖析像贾第虫这样的单个病原体如何影响早期肠道健康， 一个模型，以了解机制，使特定的营养支持主机防御和生理。的 本提案的目的是在最先进的环境中使用我们的新的贾第虫感染小鼠模型 在那里我们可以定义和控制肠道中的所有微生物暴露（gnotobiotics）。我们将联合收割机 在微生物宏基因组学和代谢组学方面具有专业知识的gnotobiotics专业知识，可进行严格的检查 饮食影响如何在复杂的群落或常驻肠道微生物中发挥功能变化。在 目的1，我们将确定肠道微生物通常如何保护免受贾第虫持续感染 通过将肠道微生物从营养良好的动物转移到易感宿主，反之亦然 将慢性感染宿主的容许微生物转移到营养小鼠体内。我们将特别 检查微生物代谢胆汁酸的能力是否是防止贾第虫感染的关键， 以及微生物是否是有效免疫所必需的。在目标2中，我们将确定贾第虫和蛋白质 缺乏协同作用导致肠屏障功能障碍。我们的模型具有临床相关的生长结果 限制蛋白质摄入和贾第虫联合损伤期间肠屏障功能的限制和丧失 感染我们将使用我们的gnotobiotic模型来生成宏基因组和代谢组数据， 贾第虫感染期间微生物群落的致病性变化。我们将具体阐明 芳香族氨基酸代谢物和胆汁酸对蛋白质缺乏状态下肠道功能的影响，以及 贾第虫促进致病细菌的功能，导致肠病。我们的gnotobiotic方法是创新的 并将使我们能够描述肠道细菌和贾第虫感染之间的关键相互作用 这是以前没有阐明的。拟议的研究将解决与以下方面有关的长期问题： 贾第虫对肠道功能作用，特别是贾第虫是否通过改变微生物 新陈代谢.除了贾第虫的发病机制，这些结果预计将导致新的考虑如何 健康细菌提供保护，防止肠道感染，以及慢性肠道病原体暴露如何导致肠道 功能障碍无腹泻。我们希望发现新的途径，可能利用新兴的微生物或 以分子为基础的疗法，以改善易受营养不良和肠道感染的儿童的健康。

PROJECT SUMMARY Giardia lamblia belongs to a group of gut pathogens associated with impaired child development and gut function, especially in children with inadequate nutrition. Although most Giardia infections in these children are clinically silent, Giardia may lead to longterm detriments. For reasons that are unknown, many of these children cannot clear the parasite. Further, infected children may be at risk for gut dysfunction as a result of Giardia infection, even if they are asymptomatic. We hypothesize that susceptibility to Giardia and subsequent disease result from a change in the resident intestinal microbial community as a consequence of low dietary protein. Animal models provide an opportunity to dissect how an individual pathogen like Giardia impacts early life intestinal health, and a model to understand mechanisms whereby specific nutrients support host defenses and physiology. The objective of this proposal is to use our novel mouse models of Giardia infection in a state-of-the-art environment where we can define and control for all microbial exposures in the gut (gnotobiotics). We will combine our gnotobiotics expertise with expertise in microbial metagenomics and metabolomics for a rigorous examination of how dietary influences exert a functional change in the complex community or resident intestinal microbes. In Aim 1, we will determine how resident intestinal microbes normally protect against persistent Giardia infection by transferring intestinal microbes from a well-nourished animal into susceptible hosts, and vice versa transferring permissive microbes from hosts with chronic infection into nourished mice. We will specifically examine whether the ability of microbes to metabolize bile acids are key to protection against Giardia infection, and whether microbes are necessary for effective immunity. In Aim 2, we will determine how Giardia and protein deficiency synergize to cause intestinal barrier dysfunction. Our model has a clinically relevant outcome of growth restriction and loss of intestinal barrier function during the combined insult of limited protein intake and Giardia infection. We will use our gnotobiotic model to generate metagenomic and metabolomic data that will identify pathogenic shifts in microbial communities during Giardia infection. We will specifically elucidate the role of aromatic amino acid metabolites and bile acids on gut function in the protein deficient state, as well as whether Giardia promotes pathogenic bacterial functions to cause enteropathy. Our gnotobiotic approach is innovative and will allow us to characterize critical interactions between resident intestinal bacteria and infection with Giardia that have not previously been elucidated. The proposed research will address longstanding questions related to the role of Giardia on gut function, and specifically whether Giardia exerts pathogenesis by altering microbial metabolism. Beyond Giardia pathogenesis, these results are expected to lead to new considerations for how healthy bacteria provide protection against gut infection, and how chronic enteropathogen exposures cause gut dysfunction absent diarrhea. We hope to discover new pathways that might leverage emerging microbial or molecular-based therapeutics to improve health of children vulnerable to malnutrition and intestinal infections.