Linking diet, gut microbiota and autoimmune disease: Bacteria induced phytoestrogen metabolites impact immune function in Experimental Autoimmune Encephalitis

尽管免疫系统和肠道微生物组之间的联系越来越受到重视， 微生物组与炎症性自身免疫性疾病（如多发性硬化症）之间的机制联系 (MS)不清楚。因此，迫切需要确定肠道细菌维持免疫的机制， 稳态，从而影响神经炎症。我们最近报道MS患者已经改变了 与健康对照组相比，某些人类肠道细菌的丰度降低 （Parabacteroides、Adlercreutzia和Prevotella）具有代谢植物雌激素的能力。肠道细菌 将植物雌激素代谢为雌马酚，雌马酚与雌激素结构相似，具有免疫调节作用， 通过雌激素受体和AMP激活的蛋白激酶（AMPK）的反应。我们的初步数据 显示与那些相比，在食用含有植物雌激素（异黄酮）的饮食的小鼠中EAE显著较轻， 无植物雌激素的饮食提示植物雌激素在调节EAE中的关键作用。此外，本发明还 组织普雷沃氏菌是普雷沃氏菌属的一种，在实验性自身免疫性疾病中具有抑制疾病的作用， 脑脊髓炎（EAE），MS的临床前小鼠模型。 在P. histicola介导的疾病抑制中的代谢是未知的。提出的中心假设 研究表明，人类肠道寄生虫通过代谢介导其疾病保护作用 植物雌激素和随后的免疫调节细胞的激活。我们将检验我们的中心假设 使用动物模型、转基因小鼠和细胞培养方法，有以下两个具体目的。在 首先，我们将利用P. histicola作为代表性的植物雌激素代谢肠道细菌， 确定植物雌激素的代谢是否是毛癣菌抑制疾病的能力所必需的， 诱导T细胞和/或CD 103+致耐受性树突细胞（DC）。我们将确定AMPK的重要性 在植物雌激素中的信号传导诱导了TdR和/或致耐受性DC的活化。第二个目标，我们将 确定植物雌激素加细菌是否介导免疫调节细胞的诱导， 肠上皮细胞和/或免疫细胞中的雌激素受体（ER）依赖性途径。我们的书房很适合 “优先免疫学拨款（R 01）”机制，因为我们建议 微生物对全身免疫力影响的潜在机制，可用于设计 潜在的单一以及联合治疗，因为药物具有不同的非重叠机制 可能为MS患者提供最大益处。我们将确定植物雌激素代谢细菌 通过其相互作用使Tcl 3向Th 1/Th 17平衡向Tcl 3倾斜，维持无病状态 与雌激素受体和AMPK通路有关。我们希望我们的研究结果会有积极的意义。 对开发基于肠道微生物菌群/饮食的MS和其他炎症治疗的影响 自身免疫性疾病

Although the link between the immune system and the gut microbiome is being increasingly appreciated, the mechanistic links between the microbiome and inflammatory autoimmune diseases such as multiple sclerosis (MS) are unclear. Thus, there is a critical need to define mechanisms by which gut bacteria maintain immune homeostasis and thereby affect neuroinflammation. We have recently reported that MS patients have altered gut microbiota compared to healthy controls, with a reduced abundance of certain human gut bacteria (Parabacteroides, Adlercreutzia, and Prevotella) with the ability to metabolize phytoestrogen. Gut bacteria metabolize phytoestrogen into equol which has structural similarity with estrogen, and can regulate immune responses through estrogen receptors and AMP-activated protein kinase (AMPK). Our preliminary data showing significantly milder EAE in mice on a phytoestrogen (Isoflavones) containing diet compared to those on a phytoestrogen free diet suggest a critical role of phytoestrogen in modulation of EAE. Additionally, Prevotella histicola, a member of the Prevotella genus, can suppress disease in experimental autoimmune encephalomyelitis (EAE), a preclinical murine model of MS. However, the importance of phyoestrogen metabolism in P. histicola–mediated disease suppression is unknown. The central hypothesis of the proposed studies is that the human gut commensal P. histicola mediate its disease-protective effect through metabolism of phytoestrogen and subsequent activation of immunoregulatory cells. We will test our central hypothesis using animal model, genetically modified mice, and a cell culture approach in the following two specific aims. In first aim, we will utilize P. histicola as a representative phytoestrogen-metabolizing gut commensal bacteria to determine whether metabolism of phytoestrogen is required for ability of P. histicola to suppress disease and induce Tregs and/or CD103+ Tolerogenic dendritic cells (DCs). We will determine the importance of AMPK signaling in the phytoestrogen induced activation of Tregs and/or tolerogenic DCs. In second aim, we will determine whether the phytoestrogen plus bacteria mediate the induction of immunoregulatory cells via estrogen receptor (ER)-dependent pathways in intestinal epithelial cells and/or immune cells. Our study is fit for the “High Priority Immunology Grant (R01) mechanism because we are proposing to determine the mechanisms underlying the microbial impact on systemic immunity which can be harnessed in designing potential mono as well as combination therapies because drugs with diverse non-overlapping mechanisms might provide maximal benefit to MS patients. We will determine whether phytoestrogen-metabolizing bacteria maintain a disease-free state by tilting the Tregs to Th1/Th17 balance towards Tregs through its interaction with estrogen receptors and the AMPK pathway. We expect the outcome of our study will have a positive impact on development of gut microbial-flora/diet-based therapies for MS as well as other inflammatory autoimmune diseases.