Modulation of the Intestinal Microbiome in Obesity by a High Protein Diet

摘要 在临床前啮齿动物模型和临床试验中，高蛋白饮食已被证明是一种有效的肥胖 与以下疗法相比，这种疗法能更大程度地减轻体重和脂肪质量，并增加饱腹感 等卡路里标准蛋白质饮食。然而，这种反应的机制还没有完全阐明。我 最近在啮齿动物模型中证明，高蛋白饮食会导致肠道微生物群的变化 其中包括阿克曼西亚粘液细菌，一种据报道具有抗肥胖效果的微生物。基于 这些初步研究，我假设高蛋白饮食会引起肠道微生物群的改变。 这是它治疗肥胖症的临床疗效的中介。为了测试这一点，我将研究216名超重和肥胖的退伍军人(BMI 27-40)谁将被随机分为等卡高蛋白(30%)或正常蛋白(15%)1500卡路里饮食 在西洛杉矶退伍军人医疗中心利用现有的临床基础设施16周 最近完成的一项高蛋白饮食的临床试验。在目标1中，高蛋白饮食对 肠道微生物组的组成和功能将通过16S rRNA测序进行评估 元基因组学和代谢组学。我预测，在高蛋白饮食之后， 肠道微生物组的组成有利于阿克马尼亚属和其他微生物的定植 与正常的蛋白质饮食相比，促进脂肪的减少。我预计微生物组成的这种变化将 与元基因组的改变有关--包括所涉及的细菌基因丰度降低 碳水化合物的利用--以及代谢组。研究期间共收集了11个粪便样本。 以期确定微生物变化的动力学。在目标2中，粪便微生物、后基因组和 对高蛋白饮食的反应的代谢预测因子将被确定。响应将通过以下方式进行衡量 体重减轻，体脂减少，肝脏脂肪变性减轻，血脂改变，血红蛋白A1c降低， 降低高敏C反应蛋白，增加饱腹感。预测值将使用 基线微生物组数据以及在治疗期间每个时间点收集的样本。我也会评估 特定的微生物、基因和代谢物是否与影响血液循环的激素水平有关 饱腹感(瘦素、生长素、胰升糖素、胰升糖素样肽-1、YY肽和胰多肽)。在《目标3》中， 无菌小鼠将用在基线或饮食16周后获得的新鲜冷冻粪便定居。 干预以确定高蛋白饮食中微生物组的改变与 易患肥胖症。这些人源化的灵知生菌小鼠将被置于西方饮食中以诱导肥胖 并对体重增加、体脂积累、胰岛素敏感性和饱腹感/饥饿激素水平进行比较。在……里面 同时，先前存在饮食诱导肥胖的小鼠将在饮食干预后的人类中定居。 微生物区系，并按标准饮食。减肥、减脂、胰岛素敏感性和荷尔蒙 两组之间的水平将进行比较。拟议研究的结果将使我们深入了解 驱动临床对高蛋白饮食反应的特定微生物，并可能确定候选的抗肥胖药物 可以进一步开发成新的微生物疗法的微生物。

ABSTRACT A high protein diet has been shown in preclinical rodent models and clinical trials to be an effective obesity treatment that is associated with greater loss of body weight and fat mass and increased satiety compared to isocaloric standard protein diets. However, the mechanisms of this response have not been fully elucidated. I recently demonstrated in a rodent model that a high protein diet induces shifts in the intestinal microbiome including a bloom of Akkermansia muciniphila, a microbe reported to have an anti-obesity effect. Based on these preliminary studies, I hypothesize that a high protein diet induces alterations in the intestinal microbiome that mediate its clinical efficacy for obesity. To test this, I will study 216 overweight and obese Veterans (BMI 27-40) who will be randomized 1:1 to isocaloric high protein (30%) or normal protein (15%) 1500 calorie diets for 16 weeks utilizing existing clinical infrastructure at the West Los Angeles VA Medical Center established for a recently completed clinical trial of a high protein diet. In Aim 1, the effect of a high protein diet on the composition and function of the intestinal microbiome will be assessed by 16S rRNA sequencing, shotgun metagenomics, and metabolomics. I predict that following a high protein diet, there will be a major shift in the composition of the intestinal microbiome to favor colonization with Akkermansia and other microbes that promote fat loss compared to the normal protein diet. I anticipate that this change in microbial composition will be associated with alterations in the metagenome – including reduced abundance of bacterial genes involved in carbohydrate utilization – and the metabolome. A total of 11 fecal samples will be collected during the study period to determine the kinetics of microbial changes. In Aim 2, fecal microbial, metagenomic, and metabolomic predictors of response to a high protein diet will be identified. Response will be measured by weight loss, reduced body fat, decreased hepatic steatosis, altered lipid profiles, reduced hemoglobin A1c, decreased high sensitivity C-reactive protein, and increased satiety. Predictors will be generated using the baseline microbiome data as well as samples collected at each time point during treatment. I will also evaluate whether specific microbes, genes, and metabolites are associated with circulating levels of hormones affecting satiety (leptin, ghrelin glucagon, glucagon-like peptide-1, peptide YY, and pancreatic polypeptide). In Aim 3, germ-free mice will be colonized with fresh frozen feces obtained at baseline or after 16 weeks of dietary intervention to establish a causal relationship between alteration of the microbiome on a high protein diet and susceptibility to obesity. These humanized gnotobiotic mice will be placed on a Western diet to induce obesity and compared for weight gain, body fat accumulation, insulin sensitivity, and satiety/hunger hormone levels. In parallel, mice with pre-existing diet-induced obesity will be colonized with post-dietary intervention human microbiota and placed on a standard diet. Weight loss, body fat reduction, insulin sensitivity, and hormone levels will be compared between the two groups. The results of the proposed study will provide insight into the specific microbes that drive the clinical response to a high protein diet and may identify candidate anti-obesity microbes that could be further developed into novel microbial therapeutics.