Intestinal Reg3g as a mediator of dietary, pharmacological and surgical therapies for obesity and diabetes

胃肠道(GI)已经成为我们管理肥胖和2型糖尿病最有效的治疗方法的重要来源。这既包括手术干预，如垂直袖状胃切除术(VSG)，也包括模拟一种或多种胃肠激素作用的药理药物。尽管如此，关于胃肠道对全身新陈代谢的影响和能量平衡的调节，仍有许多未知之处。 胃肠道位置独特，因为它必须在排除毒素和细菌之间做出妥协，同时吸收必要的卡路里和营养。肠道屏障使用紧密连接和粘液产生等物理成分以及抗微生物多肽等分泌因子使宿主和细菌保持适当的隔离。其中一种抗菌肽是Reg3g(再生胰岛衍生蛋白3伽马)，由小肠中的Paneth细胞大量分泌。在过去的4年里，我们一直在仔细地记录Reg3g如何调节肠道功能、能量平衡和血糖水平，以应对VSG。 像VSG这样的减肥手术极大地增加了胃的排空率，给肠道带来了巨大的负担。这导致了许多肠道适应，包括增加乳杆菌的流行率和丰度，以及增加Reg3g的表达和循环水平。我们发现，Reg3g基因敲除(KO)小鼠未能安装许多这些重要的适应，包括增加肠道屏障的完整性。重要的是，这些小鼠在服用VSG后也没有失去显著的体脂，改善了它们的葡萄糖耐量，增加了它们的胰岛素分泌。此外，在外周给予Reg3g可以改善糖耐量，在中枢神经系统(CNS)直接给予Reg3g可以减少食物摄入量。这些结果支持我们的总体假设，即Reg3g在管腔内发挥作用，并作为一种循环肠道激素，在有效的饮食、手术和药物治疗中调节能量平衡和葡萄糖水平。我们将在三个目标中检验这一重要假设： 具体目标1：验证改善血糖调节和增加乳杆菌的饮食和药物治疗通过增加肠道Reg3g的表达和/或循环水平而发挥关键益处的假说。我们的数据显示，VSG增加了乳杆菌以及肠道中Reg3g的表达和循环水平。此外，我们还发现，许多VSG的积极代谢结果都需要Reg3g。口服二甲双胍和高可溶性纤维菊粉的饮食也可以增加小肠中乳杆菌的数量，改善血糖调节，就像VSG所发生的那样。我们推测，这些干预措施还将增加肠道和循环中的Reg3g，并且Reg3g对于二甲双胍和菊糖改善肠道功能、体重和血糖调节至关重要。我们将在WT和Reg3g KO小鼠身上使用这些干预措施来验证这一假设。 具体目的2：检测肠道微生物区系及其产物是否能通过增加肠道Reg3g对胃肠功能和代谢功能产生有益的影响。首先，我们将给小鼠注射各种益生菌，并测试它们增加Reg3g肠道表达和循环水平的能力。这些益生菌将包括各种乳杆菌或前和益生菌的组合，也可以产生乳酸。然后，我们将在WT和Reg3g KO小鼠身上确定它们对肠道功能、能量平衡和血糖调节的影响是否依赖于Reg3g。 尽管肠道在肥胖症和糖尿病的治疗中起着中心作用，但肠道微生物群、肠道健康和代谢调节之间的关系仍充满未解的问题。这一提议假设了Reg3g的一个新角色，即作为一个信号，传达肠道细菌的状态和肠道屏障，以调节系统代谢的多个方面。因此，拟议的工作为了解肠道如何影响代谢性疾病提供了一个新的框架，并开辟了新的治疗方法，范围可能从膳食补充剂和药理学到可以利用Reg3g生物学来预防和/或治疗胃肠道和代谢性疾病的外科手术。

The gastrointestinal (GI) tract has become an important source for our most effective therapies to manage obesity and type 2 diabetes. This includes both surgical interventions, such as vertical sleeve gastrectomy (VSG), as well as pharmacological agents that mimic the effects of one or more GI hormones. Despite this, there remains a great deal unknown about the impact of the GI tract on systemic metabolism and the regulation of energy balance. The GI tract is uniquely situated because it must compromise between keeping out toxins and bacteria while simultaneously absorbing necessary calories and nutrients. The gut-barrier keeps host and bacteria appropriately segregated using both physical components such as tight junctions and mucus production, as well as secreted factors such as anti-microbial peptides. One such anti-microbial peptide is Reg3g (regenerating islet-derived protein 3 gamma) is abundantly secreted by paneth cells in the small intestine. We have spent the last 4 years carefully documenting how Reg3g regulates gut function, energy balance and glucose levels in response to VSG. Bariatric surgeries such as VSG greatly increase gastric emptying rates, placing an enormous burden on the intestine. This results in many intestinal adaptations, which includes increasing the prevalence and abundance of Lactobacillus as well as increasing both expression and circulating levels of Reg3g. We found that Reg3g knockout (KO) mice fail to mount many of these important adaptations, including an increase in the integrity of the gut-barrier. Importantly, these mice also fail to lose significant body fat, improve their glucose tolerance and increase their insulin secretion after VSG. Moreover, pharmacological administration of Reg3g in the periphery improved glucose tolerance, and direct administration of Reg3g in the central nervous system (CNS) reduced food intake. These results support our overarching hypothesis that Reg3g acts both within the lumen and as a circulating gut hormone to regulate energy balance and glucose levels in effective dietary, surgical and pharmacological therapies. We will test this overarching hypothesis in 3 aims: Specific Aim 1: To test the hypothesis that dietary and pharmacological treatments that improve glucose regulation and increase Lactobacillus exert key beneficial effects by increasing the expression and/or circulating levels of intestinal Reg3g. Our data show that VSG increases Lactobacillus and both intestinal expression and circulating levels of Reg3g. In addition, we found that Reg3g is required for many of the positive metabolic outcomes of VSG. Both oral administration of metformin and diets high in the soluble fiber inulin also increase the abundance of Lactobacilli in the small intestine and improve glucose regulation, such as occurs with VSG. We hypothesize that these interventions will also increase Reg3g in the intestine and in circulation and that Reg3g will be essential for metformin and inulin to improve gut function, body weight and glucose regulation. We will use these interventions in WT and Reg3g KO mice to test this hypothesis. Specific Aim 2: To test whether intestinal microbiota and its products can produce beneficial effects on GI and metabolic function by increasing intestinal Reg3g. First, we will administer a variety of probiotics to mice and test their ability to increase Reg3g intestinal expression and circulating levels. These probiotics will include various species of Lactobacillus or a pre and probiotic combination that can also produce lactate. Then, we will determine whether their effects on gut function, energy balance and glucose regulation are dependent on Reg3g using WT and Reg3g KO mice. Despite the centrality of the gut for treatments of obesity and diabetes, the relationship between the intestinal microbiome, gut health and metabolic regulation is fraught with unanswered questions. This proposal hypothesizes a novel role for Reg3g as a signal that communicates the status of intestinal bacteria and the gut barrier to regulate multiple aspects of systemic metabolism. As such, the proposed work provides a new framework for understanding how the gut affects metabolic disease and opens new therapeutic approaches that might range from dietary supplements and pharmacology to surgical procedures that can harness Reg3g biology to prevent and/or treat GI and metabolic disease.