Neural sensing of gut bacteria

摘要 肠道不断地感知细菌，但大脑如何识别这些微生物仍然存在 不清楚。微生物相关的分子模式，如鞭毛蛋白，由肠道检测 通过模式识别受体如Toll样受体5。最近的报道显示 敲除肠道中的这种受体会导致新陈代谢综合症。模式识别受体 也已知优先在肠内分泌细胞上表达，或电兴奋 通常被认为是荷尔蒙信号的上皮细胞。赞助商的实验室最近 发现其中一些细胞，现在被称为神经足细胞，与突触相连 迷走神经和骨盆神经。我的初步数据显示，神经足细胞优先表达 Toll样受体5，并有条件地敲除神经足细胞中的受体导致体重增加 在小白鼠身上增加。这些数据表明，神经足细胞是细菌信号转导的关键中介。 从内脏到大脑。因此，该研究项目的中心假设是神经足细胞 通过突触将结肠管腔中的鞭毛蛋白转导到骶神经上。为了测试这一点， 提出了两个目标：(1)确定神经足细胞是否释放谷氨酸作为对 (2)在体内测试神经足细胞对鞭毛蛋白到骶神经的转导作用。至 为了达到这些目标，肠上皮生物学和神经生物学的最新技术将 由实习生进行组合。在目标1中，急性分离的神经足细胞和三维有机体 将对培养物进行钙活性和谷氨酸释放成像，以响应鞭毛蛋白。在目标2中， 将使用光遗传学和药物沉默的方法记录骶神经记录中的神经足细胞 以测试该电路是否传递细菌信号。这些研究有望揭示一种 微生物与中枢神经系统通讯的新机制，可用于 开发胃肠道疾病患者的治疗方法。这项提议最终将支持 对双学位医学博士研究生的培训，为他的独立职业生涯做准备 临床胃肠病学实践和神经科学的交汇处的内科医生-科学家 实验室。培训计划还将包括参加会议和参与组织 这是一个由他的赞助人创建的国际肠脑科学家协会，该协会的发起人是盖斯特罗茨。与 在F30的支持下，学员将发展过渡到博士后临床所需的技能 以及在成为独立内科科学家的道路上进行研究培训。

ABSTRACT The gut continuously senses resident bacteria, but how the brain recognizes these microbes remains unclear. Microbe-associated molecular patterns such as flagellin are detected by the intestinal epithelium by pattern recognition receptors such as Toll-like receptor 5. Recent reports have shown that knocking out this receptor in the gut leads to metabolic syndrome. Pattern recognition receptors are also known to be preferentially expressed on enteroendocrine cells, or electrically excitable epithelial cells traditionally thought to signal hormonally. The sponsor’s laboratory has recently discovered that some of these cells, now known as neuropod cells, are synaptically connected with vagal and pelvic nerves. My preliminary data show that the neuropod cells preferentially express Toll-like receptor 5, and that conditionally knocking out the receptor in neuropod cells leads to weight gain in mice. These data suggest that neuropod cells are critical intermediaries in bacterial signaling from gut to brain. Therefore, the central hypothesis of the research project is that neuropod cells transduce flagellin in the lumen of the colon onto the sacral nerve through a synapse. To test this, two aims are proposed: (1) to determine whether neuropod cells release glutamate in response to flagellin in vitro, and (2) to test neuropod cell transduction of flagellin onto the sacral nerve in vivo. To address these aims, state-of-the-art techniques from intestinal epithelial biology and neurobiology will be combined by the trainee. In Aim 1, acutely dissociated neuropod cells and 3-dimensional organoid cultures will be imaged for calcium activity and glutamate release in response to flagellin. In Aim 2, optogenetic and pharmacological silencing of neuropod cells in sacral nerve recordings will be used to test whether the circuit transduces bacterial signals. These studies are expected to uncover a novel mechanism for microbes to communicate with the central nervous system that can be used to develop therapeutics for patients with gastrointestinal disease. This proposal will ultimately support the training of a dual-degree MD/PhD student, in preparation for his career as an independent physician-scientist at the intersection of a clinical gastroenterology practice and a neuroscience laboratory. The training plan will also include attending conferences and participating in organizing an international society of gut-brain scientists started by his sponsor named Gastronauts. With the support of this F30, the trainee will develop the requisite skill set to transition into post-doctoral clinical and research training on the path to becoming an independent physician scientist.