Diet-microbe interactions modulating host energy balance

项目总结/摘要 在美国，肥胖影响大约35%的成年人和17%的儿童，增加了 心脏病中风和2型糖尿病人类肠道微生物群，数万亿的微生物居住在 胃肠道，已经被认为是与肥胖和能量平衡有关的环境因素; 然而，其机制尚未完全了解。饮食仍然是诱导体重的第一线干预措施 减肥，但它对微生物群的影响，以及这可能如何影响减肥和恢复仍然不清楚。我 对人类受试者进行极低热量饮食干预的初步结果显示， 诱导微生物群组成和功能的类寄生虫干扰。饮食后粪便移植 人类到无菌小鼠的基因突变诱导体重减轻。对人类和小鼠微生物的分析表明， 饮食诱导的微生物群重构允许艰难梭菌的扩增， 最为人所知的是与腹泻相关的腹泻及其严重并发症的主要原因。在一个殖民地 model，C. difficile足以推动体重减轻，减少体脂，并增加葡萄糖耐量， 引起急性疾病。这些观察导致了这样的假设，即饮食与肠道的相互作用 microbiota和C. difficile破坏营养吸收，导致能量不平衡。第一个目标是 研究的重点是C.难以影响宿主能量平衡，同时表征机制 通过它发生。初步数据强烈暗示C。艰难梭菌毒素TcdA和/或TcdB。使用 组合和单独敲除，将鉴定致病毒素及其对宿主能量的影响 平衡将被广泛表征。明确C.艰难的行为在水平 亚毒性纯化毒素对营养吸收和细胞生理学的影响将 在人类和小鼠肠道的类器官模型中进行检查。最后，无症状的能力 将检查对抗饮食诱导的肥胖症的定殖。这项工作的第二个目标将审查 热量限制影响C.难以容忍。具体而言，这一目标将考验 热量限制会耗尽产生C.艰难梭菌抑制次级胆汁酸。 通过热量限制的人源化小鼠模型，以及序列引导的分离和代谢， 表征，合成社区将被设计为复制对饮食敏感的微生物， 测试次级胆汁酸生物合成的作用，并可能确定新的拮抗相互作用， 与C有很大关系。艰难的治疗和预防。为实现这些目标而提出的实验将 利用我在微生物组领域的专业知识，在肥胖和代谢疾病研究方面进行新的培训。一个 专家跨学科咨询委员会，以及对微生物组和代谢研究的机构重点， 将为拟议的科学和专业发展提供理想的环境， 建立独立的研究计划。

PROJECT SUMMARY/ABSTRACT Obesity affects approximately 35% of adults and 17% of children in the United States increasing the risks of heart disease, stroke and type 2 diabetes. The human gut microbiota, the trillions of microbes that inhabit the gastrointestinal tract, have been implicated as an environmental factor linked to obesity and energy balance; however, the mechanisms are not fully understood. Diet remains the first line intervention to induce weight loss, but its impact on the microbiota, and how this may affect weight loss and regain remain unclear. My preliminary results from a very-low calorie diet intervention in human subjects reveal that caloric restriction induces antibiotic-like disturbances in microbiota composition and function. Fecal transplant from post-diet humans to germ-free mice induces weight loss. Analysis of both human and mouse microbiotas revealed that the diet-induced reconfiguration of the microbiota allowed for expansion of Clostridioides [Clostridium] difficile, best known as a major cause of antibiotic-associated diarrhea and its severe complications. In a colonization model, C. difficile was sufficient to drive weight loss, reduce body fat, and increase glucose tolerance without causing acute disease. These observations have led to the hypothesis that diet interactions with the gut microbiota and C. difficile disrupt nutrient uptake contributing to energy imbalance. The first aim of these studies will focus on the ability of C. difficile to affect host energy balance while characterizing the mechanisms through which it occurs. Preliminary data strongly implicates the C. difficile toxins TcdA and/or TcdB. Using combinatorial and individual knockouts, the causative toxin will be identified and its effects on host energy balance will be extensively characterized. To define the mechanisms through which C. difficile acts at the level of the intestinal epithelium, the effect of sub-toxic purified toxin(s) on nutrient absorption and cell physiology will be examined in organoid models of both the human and mouse intestine. Finally, the ability of asymptomatic colonization to counter diet-induced obesity will be examined. The second aim of this work will examine the mechanism through which caloric restriction affects C. difficile permissibility. Specifically, this aim will test the hypothesis that caloric restriction depletes microbes that produce C. difficile-inhibitory secondary bile acids. Through a humanized mouse model of caloric restriction, and sequence-guided isolation and metabolic characterization, synthetic communities will be designed replicating diet-responsive microbes to specifically test the role of secondary bile acid biosynthesis, and potentially identify new antagonistic interactions which are of great relevance to C. difficile treatment and prevention. The proposed experiments in these aims will leverage my expertise in the microbiome field with new training in obesity and metabolic disease research. An expert interdisciplinary advisory committee, and an institutional focus on microbiome and metabolism research, will provide the ideal environment for the proposed scientific and professional development leading to the creation of an independent research program.