Stress Induced Inflammation and Dysbiosis in a Mouse Model of Crohn's Disease

项目摘要 心理危险因素已被反复确认为炎症性肠病的组成部分 （IBD）。特别是压力，一再被证明是爆发的有力预测因素。虽然一些研究 试图在压力和微生物组-肠道-大脑轴之间建立一种机械关系 （MGBA），还没有得到令人满意的解释。在某种程度上，这是由于依赖于化学诱导的 IBD模型，特别是葡聚糖硫酸钠（DSS）结肠炎。很少有文献研究 克罗恩病和回肠炎的心理压力。在这里，我们提出了一系列的研究来调查压力 以及我们的CD样回肠炎小鼠模型中的MGBA，SAMP 1/YitFc（SAMP 1）。 为了引起心理压力，我们使用约束压力（RS）。我们小组的初步数据表明 RS除了能提高血清皮质酮水平外，还能诱导抑郁样表型。 暴露于急性RS导致肠系膜淋巴结中树突状细胞水平升高， 回肠固有层细胞因子表达。根据以前的文献和我们的初步数据，我们假设 心理压力会引起肠道微生物组的变化，这反过来又会促进促炎症反应， 反应 为了解决我们的假设，我们提出了以下三个目标。我们的第一个目标是验证压力的能力， 在我们的CD样回肠炎小鼠模型中，为了实现这一目标，我们将 小鼠急性和慢性应激，并观察由此产生的炎症变化。此外，我们将测量 应激通过诱导缓解并随后使SAMP 1小鼠暴露于应激而引起复发的能力。 我们的第二个目标将描述应激后免疫反应及其改变微生物组的能力。我们 将利用我们的SAMP 1 Δ CD 1-DTR小鼠，一种选择性诱导的树突状细胞敲除模型， 树突状细胞对压力的反应。随后，我们将使用收获的骨髓产生骨髓嵌合体。 来自应激和非应激小鼠的骨髓。在我们的第三个目标中，我们将确定压力是否改变了 微生物组是诱导免疫应答所必需的和/或足够的。无菌（GF）和特定病原体 自由（SPF）小鼠将通过经口管饲法接受来自应激或应激小鼠的粪便微生物组移植（FMT）。 无压力的捐赠者随后，将评估受体小鼠的炎症反应，并将免疫组化。 将确定微生物组的代谢组。 虽然压力可能是每个CD患者生活中不可避免的一个方面，但我们相信我们的工作可以导致 减轻压力有害影响的疗法。具体来说，使用我们独特的CD样回肠炎小鼠模型， 我们希望发现新的治疗策略，如益生菌或益生元，以防止炎症反应， 压力该项目的未来目标包括研究具有感知压力的人类患者的微生物组 并使用我们验证的人FMT模型移植到无菌（GF）小鼠中。

PROJECT SUMMARY Psychological risk factors have repeatedly been recognized as integral facets of inflammatory bowel disease (IBD). Stress, in particular, has been repeatedly shown as a strong predictor of flare-ups. Though several studies have attempted to establish a mechanistic relationship between stress and the microbiome-gut-brain axis (MGBA), a satisfying explanation has not been reached. In part, this is due to the reliance on chemically induced models of IBD, particularly Dextran Sodium Sulfate (DSS) colitis. Very little literature exists studying the effect of psychological stress on Crohn’s disease and ileitis. Here, we propose a series of studies to investigate stress and the MGBA in our mouse model of CD-like ileitis, the SAMP1/YitFc (SAMP1). To induce psychological stress, we use restraint stress (RS). Preliminary data from our group has demonstrated that RS is capable of inducing a depressive-like phenotype in addition to raising serum corticosterone levels. Exposure to acute RS resulted in elevated levels of dendritic cells in the mesenteric lymph node and altered cytokine expression in ileal lamina propria. Based on previous literature and our preliminary data, we hypothesize that psychological stress induces a change in the gut microbiome which, in turn, promotes a pro-inflammatory response. To address our hypothesis, we propose the following three aims. Our first aim will validate the ability of stress to worsen intestinal inflammation in our mouse model of CD-like ileitis. To accomplish this aim, we will subject our mice to acute and chronic stress and observe resultant inflammatory changes. Furthermore, we will measure the ability of stress to provoke relapse by inducing remission and subsequently exposing SAMP1 mice to stress. Our second aim will characterize the post-stress immune response and its ability to alter the microbiome. We will make use of our SAMP1ΔCD1-DTR mouse, a selectively inducible dendritic cell knock-out model, to characterize the dendritic cell response to stress. Subsequently, we will generate a bone marrow chimera using harvested marrow from stressed and unstressed mice. In our third aim, we will determine whether the stress-altered microbiome is necessary and/or sufficient to induce an immune response. Germ-free (GF) and specific pathogen free (SPF) mice will receive a fecal microbiome transplantation (FMT) via oral gavage from stressed or unstressed donors. Subsequently, the inflammatory response of the recipient mice will be assessed and the metabolome of the microbiome will be determined. Though stress may be an unavoidable aspect of every CD patient’s life, we believe that our work can lead to therapies that mitigate the harmful effects of stress. Specifically, using our unique mouse model of CD-like ileitis, we hope to discover novel therapeutic strategies, such as pro- or prebiotics, to prevent the inflammatory effects of stress. Future goals of this project include studying the microbiomes of human patients with perceived stress and transplanting into germ-free (GF) mice using our validated human FMT model.