Targeted bacterial restoration of colonization resistance against C. difficile

项目总结/摘要 艰难梭菌感染（CDI）是结肠炎相关性结肠炎的主要原因， 显著的发病率、死亡率和增加的医疗保健成本。抗生素破坏了固有的肠道 微生物群，降低对C.艰难的殖民我们对机制的了解， 肠道微生物群赋予对CDI的抵抗力是不完全的，这对改善肠道微生物群对CDI的抵抗力是一个重大障碍。 针对这种病原体的预防和治疗方法。我的长期目标是了解 胃肠道微生物群介导针对肠道病原体（包括C. 很难本申请的总体目标是定义能够改变肠道微生物群的成员。 胆汁酸和消耗C.艰难的定植和发病机制。基于 初步研究的中心假设是，生产和消费的特定代谢物 （次级胆汁酸和糖）通过固有的肠道微生物群有助于定植抗性 针对C.很难所提出的研究的基本原理是， 需要C。艰难梭菌定殖有可能改善针对此的治疗方法。 感染在强有力的初步数据的指导下，这一假设将通过探索以下关键问题来检验。 问题：1）恢复大肠中微生物介导的次级胆汁酸代谢是否可以恢复 对C. difficile？和2）能够恢复细菌能够竞争相同的 营养素（糖）作为C.艰难梭菌的生长需要重建对C. difficile？到 回答第一个关键问题，我们将选择和表征能够二次胆汁分泌的细菌， 酸代谢用于向胃肠道有效递送酶的细菌菌株的基因工程 将在CDI的小鼠模型中在体外和体内评价道。在第二个关键问题下，我们将 筛选和鉴定能够与C竞争相同营养素的细菌。很难细菌会 在CDI小鼠模型中，通过体外和体内竞争测定进行评价。这两种方法都将探索 这些菌株是如何改变C.胃肠道中的艰难定植抗性以及如何 它们改变周围环境，包括微生物组、代谢组和宿主反应。的 本申请中提出的研究计划是创新的，因为它代表了对现状的背离。 quo，即在使用靶向细菌疗法来恢复二级胆汁酸的方法中， 竞争，最终恢复对C.很难拟议的研究是 意义重大，因为它将导致细菌的识别和新的靶向方法的使用 预防或治疗CDI和潜在的其他代谢疾病的治疗性干预。

Project Summary/Abstract Clostridium difficile infection (CDI) is the leading cause of antibiotic-associated colitis and is responsible for significant morbidity, mortality and increased healthcare costs. Antibiotics disrupt the indigenous gut microbiota, reducing resistance to C. difficile colonization. Our knowledge of the mechanism(s) by which the gut microbiota confers resistance to CDI is incomplete, presenting a significant roadblock to improving preventative and therapeutic approaches against this pathogen. My long-term goal is to understand how the gastrointestinal tract microbiota mediates colonization resistance against enteric pathogens, including C. difficile. The overall objective of this application is to define members of the gut microbiota that are able to alter bile acids and consume sugars which are required for C. difficile colonization and pathogenesis. Based on preliminary studies the central hypothesis is that the production and consumption of specific metabolites (secondary bile acids and sugars) by the indigenous gut microbiota contribute to colonization resistance against C. difficile. The rationale that underlies the proposed research is that the targeting of metabolites required for C. difficile colonization has the potential to improve directed therapeutic approaches for this infection. Guided by strong preliminary data, this hypothesis will be tested by exploring the following key questions: 1) Can restoring microbial-mediated secondary bile acid metabolism in the large intestine restore colonization resistance against C. difficile? and 2) Can restoring bacteria that are able to compete for the same nutrients (sugars) as C. difficile requires for growth reestablish colonization resistance against C. difficile? To answer the first key question, we will select for and characterize bacteria that are capable of secondary bile acid metabolism. Genetic engineering of bacterial strains for efficient enzyme delivery to the gastrointestinal tract will be evaluated in vitro and in vivo, in a mouse model of CDI. Under the second key question, we will screen and characterize bacteria that are able to compete for the same nutrients as C. difficile. Bacteria will be evaluated by competition assays in vitro and in vivo, in a mouse model of CDI. Both approaches will explore how these bacterial strains alter C. difficile colonization resistance in the gastrointestinal tract as well as how they alter the surrounding environment including the microbiome, metabolome and host response. The proposed research program in this application is innovative because it represents a departure from the status quo, namely in the approach of using a targeted bacterial therapy to restore secondary bile acids and competition, ultimately restoring colonization resistance against C. difficile. The proposed research is significant, because it will lead to the identification of bacteria and new-targeted approaches to be used for therapeutic interventions to prevent or treat CDI, and potentially other metabolic diseases.