The Role of Bile Salt Hydrolase in Glucose Metabolism

项目概要/摘要 目前，美国有3420万成年人患有糖尿病，约占总人口的10.3%。的 糖尿病的患病率在退伍军人中高两倍（20.5%），并且是肾衰竭的主要原因， 下肢截肢，以及退伍军人和普通人群中的成人失明。在过去 二十年来，多种代谢研究表明，胆汁酸发挥了意想不到的，但重要的， 在葡萄糖稳态和代谢综合征中的作用。相关的16 S和宏基因组研究表明， 肠道微生物区系可通过胆汁酸的修饰影响宿主葡萄糖稳态。这个项目的总体目标是 建议是确定肠道微生物区系影响宿主葡萄糖稳态的机制。有 为了更好地了解这种关系，研究人员需要评估特定细菌的作用， 胆汁酸的生物转化，并研究其对肠腔生态，代谢产物的通量和 营养素，并最终，在常规饲养（而不是微生物耗尽）宿主的生理学。因此，在本发明中， 迫切需要一种有助于将特定细菌功能敲入肠道的工具 微生物组，并研究其对宿主葡萄糖代谢和胰岛素敏感性的影响。 研究人员展示了一种创新的策略，使用工程化的原生 细菌这种新的方法可以快速有效地将有益功能敲入肠道 微生物组该功能是持续的，潜在的永久性，在传统提出的主机与一个单一的 治疗，而不需要微生物耗竭。迄今为止，调查人员已经证明， 可将易处理的天然细菌工程化以离体修饰胆汁酸，重新引入宿主，植入宿主细胞， 整个肠道，提供预期的有益功能，按预期改变管腔和血清代谢物，影响宿主 新陈代谢，甚至逆转疾病。这些功能影响宿主生理学并可能减轻疾病。 使用这种新方法，研究人员将通过解决中心假设来追求总体目标， 肠道微生物组通过胆汁酸去缀合作用影响宿主胰岛素敏感性，这些功能可以 用于治疗2型糖尿病。 在接下来的四年里，研究人员将通过三个具体目标来追求该提案的中心假设。 第一个目标是确定细菌胆汁酸去结合是否影响回肠和肝脏葡萄糖调节转录本 在常规饲养的C57 B16小鼠中。最终，这一目标将确定细菌胆汁 酸修饰和宿主胆汁酸信号传导、肠异生和肠促胰岛素产生。第二个目标将 确定微生物胆汁酸去结合的葡萄糖调节作用是否由法尼醇X介导 受体（FXR），一种主要的胆汁酸受体。这将使用工程改造的天然细菌进行， FXR敲除小鼠中的BSH。最终，这一目标将决定FXR在介导 肠道微生物组的代谢作用。第三个目标将确定饮食如何影响细菌胆汁酸 使用饮食诱导的肥胖模型（其 使用高脂肪饮食）和ob/ob小鼠（使用正常食物饮食）。因为胆汁酸信号在体内 受饮食的影响，这一目标将进一步阐明细菌胆汁酸修饰，营养素 摄入和宿主葡萄糖调节反应。 这些研究的预期结果是更好地理解a）肠道微生物组如何影响宿主 葡萄糖调节和B）是否可以操纵肠道微生物组以改善胰岛素敏感性。的 结果将产生积极的转化影响，因为它将导致T2 D的新治疗靶点， 肠道微生物组的信号通路和功能。

PROJECT SUMMARY/ABSTRACT Currently, 34.2 million US adults, or approximately 10.3% of the total population, have diabetes. The prevalence of diabetes is two-fold higher among Veterans (20.5%) and it is the leading cause of kidney failure, lower-limb amputations, and adult-onset blindness both in Veterans and the general population. Over the last two decades, multiple metabolic studies have demonstrated that bile acids play an unexpected but important role in glucose homeostasis and metabolic syndrome. Correlational 16S and metagenomic studies suggest that gut microflora can affect host glucose homeostasis through modification of bile acids. The overall goal of this proposal is to determine the mechanisms by which the gut microflora affect host glucose homeostasis. To have a better functional understanding of this relationship, investigators need to assess the role of specific bacterial bile acid biotransformations and investigate their effects on the gut luminal ecology, the flux of metabolites and nutrients, and ultimately, physiology in conventionally-raised (as opposed to microbiome-depleted) hosts. Thus, there is a critical need for a tool that will facilitate knocking-in of specific bacterial functions into the gut microbiome and investigate their effects on the host glucose metabolism and insulin sensitivity. The investigators demonstrate an innovative strategy that addresses this need using engineered native bacteria. This novel approach allows quick and effective knocking-in of a beneficial function into the gut microbiome. The function is sustained, potentially for perpetuity, in conventionally-raised hosts with a single treatment and without the need for microbiome depletion. To date, the investigators have demonstrated that tractable native bacteria can be engineered to modify bile acids ex vivo, reintroduced to the host, engraft the entire gut, deliver an intended beneficial function, alter luminal and serum metabolites as intended, affect host metabolism, and even reverse disease. These functions affect host physiology and potentially alleviate disease. Using this new approach, the investigators will pursue the overall goal by addressing the central hypothesis that gut microbiome affects host insulin sensitivity through bile acid deconjugation and that these functions can be used to treat type 2 diabetes. In the next four years, the investigators will pursue the proposal's central hypothesis with three specific aims. The first aim will determine if bacterial bile acid deconjugation affects ileal and hepatic glucoregulatory transcripts in conventionally-raised C57Bl6 mice. Ultimately this aim will determine the relationship between bacterial bile acid modification and host bile acid signaling, gluconeogenesis, and incretin production. The second aim will determine if the glucoregulatory effects of microbial bile acid deconjugation are mediated by the farnesoid X receptor (FXR), a major bile acid receptor. This will be done using engineered native bacteria with and without BSH in FXR knockout mice. In the end, this aim will determine the importance of the role of FXR in mediating the metabolic effects of gut microbiome. The third aim will determine how diet affects the bacterial bile acid deconjugation influence on the host metabolic homeostasis, using both the diet-induced obesity model (which uses a high-fat diet) and ob/ob mice (which uses normal chow diet). Because bile acid signaling is heavily influenced by diet, this aim will further elucidate the relationship between bacterial bile acid modifications, nutrient intake, and host glucoregulatory response. The expected outcome of these studies is a better understanding of a) how the gut microbiome affects host glucose regulation and b) whether the gut microbiome can be manipulated to improve insulin sensitivity. The outcome will have a positive translational impact because it will lead to novel therapeutic targets to T2D using the signaling pathways and functions employed by the gut microbiome.