Diet-microbe interactions modulating host energy balance

项目摘要/摘要 在美国，肥胖影响着大约35%的成年人和17%的儿童，增加了患肥胖症的风险 心脏病、中风和2型糖尿病。人类肠道微生物区系，栖息在 胃肠道，已被认为是与肥胖和能量平衡有关的环境因素； 然而，其机制尚不完全清楚。饮食仍然是诱发体重的一线干预措施 减少，但其对微生物区系的影响，以及这可能如何影响减肥和恢复仍不清楚。我的 对受试者进行极低卡路里饮食干预的初步结果显示，卡路里限制 在微生物区系的组成和功能上引起抗生素样的紊乱。节食后的粪便移植 人类对无菌小鼠有减肥作用。对人类和小鼠微生物群的分析表明， 食物诱导的微生物区系重组允许艰难梭状芽孢杆菌的扩张， 最广为人知的是抗生素相关性腹泻及其严重并发症的主要原因。在殖民统治下 艰难梭菌足以推动体重减轻、减少体内脂肪和提高葡萄糖耐量，而不需要 引起急性疾病的。这些观察结果导致了饮食与肠道相互作用的假说 微生物群和艰难梭菌扰乱了养分的吸收，导致了能量失衡。这些活动的首要目标是 研究将集中在艰难梭菌影响宿主能量平衡的能力上，同时表征这些机制。 它是通过它发生的。初步数据强烈表明艰难梭菌毒素TcdA和/或TcdB。vbl.使用 组合和单独敲除，将识别致病毒素及其对宿主能量的影响 平衡将被广泛地描述。为了确定艰难梭菌在 对肠上皮细胞，亚毒纯化毒素(S)对养分吸收和细胞生理学的影响 在人体和小鼠肠道的有机模型中进行检测。最后，无症状的能力 为了对抗饮食引起的肥胖症而进行的殖民活动将会被研究。这项工作的第二个目标将检查 卡路里限制影响艰难梭菌耐受性的机制。具体地说，这个目标将考验 卡路里限制会消耗产生艰难梭菌抑制次级胆汁酸的微生物的假说。 通过卡路里限制的人源化小鼠模型，以及顺序引导的分离和代谢 特征，合成群落将被设计成复制饮食反应微生物以特定的 测试次级胆汁酸生物合成的作用，并潜在地确定新的拮抗相互作用 与艰难梭菌的治疗和预防密切相关。在这些目标中拟议的实验将 利用我在微生物组领域的专业知识，在肥胖和代谢性疾病研究方面进行新的培训。一个 专家跨学科咨询委员会，以及微生物组和新陈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，从而导致 创建一个独立的研究项目。

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.