Leaky gut drives autoimmunity via bacterial flagellin-mediated activation of TLR5

肠漏通过细菌鞭毛蛋白介导的TLR5激活来驱动自身免疫 项目摘要 肠道上皮层和从中分泌的因子形成一道屏障，将宿主与宿主隔开。 环境。在病理条件下，上皮衬里的渗透性可能会受到损害，从而 肠腔内容物进入血流的通道造成“肠道渗漏”。在有基因缺陷的个体中 易感性，肠漏可能会使共生细菌和/或细菌成分进入人体，并 触发自身免疫性疾病的发生和发展。系统性红斑狼疮(SLE)是一种 表现在多个器官的自身免疫性疾病。尽管经过几十年的研究，系统性红斑狼疮的发病机制 目前仍不清楚。近年来，我们和其他人假设系统性红斑狼疮存在肠道渗漏， 肠道渗漏可能是这种疾病的发病机制之一。细菌脂多糖水平升高 在SLE患者和狼疮易感小鼠的血液中都观察到了内毒素，这支持了这一点 假设。然而，目前尚不清楚肠漏如何促进系统性红斑狼疮的发生和/或发展。而当 外源性内毒素被证明可以促进小鼠狼疮，令人惊讶的是，Toll样受体4(TLR4，即 脂多糖受体)并不能减轻狼疮倾向的MRL/LPR小鼠的疾病。在这个高风险、高回报的提案中， 我们试图研究其他可能触发全身自身免疫的细菌成分的作用。 在遗传上易患狼疮的小鼠身上。在初步研究中，我们发现显著更高水平的 抗鞭毛抗体存在于SLE患者和MRL/LPR小鼠的循环中。这表明， 泄漏的肠道可能允许鞭毛细菌和/或鞭毛蛋白在肠道中转移 上皮细胞进入血液循环。循环鞭毛蛋白以及抗鞭毛蛋白免疫复合体(由 抗原及其特异性抗体)可以潜在地激活鞭毛蛋白的受体TLR5来驱动 炎症导致系统性自身免疫，见于SLE。因此，我们假设肠子漏水会导致 通过细菌鞭毛蛋白介导的TLR5活化来实现系统性红斑狼疮样自身免疫。我们提出了两个具体目标 为了在遗传性SLE小鼠模型MRL/LPR中验证这一假设。目标1是确定能力 外源性鞭毛蛋白促进全身自身免疫。目标2是证明缺乏系统性红斑狼疮的发展 TLR5缺失。使用尖端的CRISPR/Cas9技术，我们的目标是揭示一种通过 肠道渗漏导致自身免疫，为设计新的治疗方法提供科学依据 针对以恢复肠道屏障功能为目标的SLE。

Leaky gut drives autoimmunity via bacterial flagellin-mediated activation of TLR5 Project Summary The intestinal epithelial lining, together with factors secreted from it, forms a barrier that separates the host from the environment. In pathologic conditions, the permeability of the epithelial lining may be compromised allowing the passage of lumen contents to enter the blood stream creating a “leaky gut.” In individuals with a genetic predisposition, a leaky gut may allow commensal bacteria and/or bacterial components to enter the body and trigger the initiation and development of autoimmune disease. Systemic lupus erythematosus (SLE) is a complex autoimmune disease manifested in multiple organs. Albeit decades of investigation, the pathogenesis of SLE remains unclear. In recent years, we and others have hypothesized the presence of a leaky gut in SLE and that the leaky gut can contribute to the pathogenesis of the disease. Increased levels of bacterial lipopolysaccharide (LPS) endotoxin have been observed in the blood of both SLE patients and lupus-prone mice, supporting this hypothesis. However, it is unknown how a leaky gut can contribute to SLE initiation and/or development. While exogenous LPS has been shown to facilitate murine lupus, surprisingly, deletion of toll-like receptor 4 (TLR4, the receptor of LPS) did not attenuate disease in lupus-prone MRL/lpr mice. In this high risk-high reward proposal, we seek to investigate the role of other bacterial components that could potentially trigger systemic autoimmunity in mice genetically prone to develop lupus. In preliminary studies we discovered that significant higher levels of anti-flagellin antibodies are present in the circulation of both SLE patients and MRL/lpr mice. This indicates that the leaky gut may have allowed for translocation of flagellated bacteria and/or flagellin across the intestinal epithelium and into the circulation. Circulating flagellin as well as anti-flagellin immune complexes (formed by the antigen and its specific antibody) could potentially activate TLR5, the receptor of flagellin, to drive inflammation leading to systemic autoimmunity seen in SLE. Therefore, we hypothesize that a leaky gut leads to SLE-like autoimmunity through bacterial flagellin-mediated activation of TLR5. We propose two specific aims to test this hypothesis in MRL/lpr, a mouse model of genetically prone SLE. Aim 1 is to determine the capability of exogenous flagellin to facilitate systemic autoimmunity. Aim 2 is to demonstrate the lack of SLE development with Tlr5 deletion. Using the cutting-edge CRISPR/Cas9 technology, we aim to reveal a mechanism by which a leaky gut drives autoimmunity, and provide the scientific basis for the design of novel therapeutic approaches against SLE that target restoration of the intestinal barrier function.