Bacteria-associated VB12 regulates neonatal ileal epithelium homeostasis

项目摘要/摘要 儿科炎症性肠病(IBD)的发病率在全球范围内呈上升趋势。致病机制 目前，该病的发病机制尚不清楚。然而，由于引起的致病性炎症 营养不良影响回肠上皮的动态平衡，可能导致疾病的表现。因此， 了解儿童IBD所涉及的饮食危险因素是当务之急。含有微量营养素的饮食(例如， 维生素)在功能上控制新生儿肠道细胞的基因组机制。宿主缺乏症 营养回路，特别是在怀孕前和出生后，不仅可能损害宿主- 细菌的相互作用控制着肠道内环境的稳定，但也会恶化所需的代谢网络 细菌合养生长。维生素B12(VB12)是由肠道细菌合成的。维生素B12缺乏可能 功能障碍的回肠上皮细胞(IECs)表达VB12受体(如Cubilin，megalin)与严重肠病 产后精神障碍。我们最近报道，新发现的丙酸杆菌菌株P.UF1调节 新生和成年小鼠对肠道病原体感染的吞噬和保护性T细胞反应。此外， P.UF1产生VB12，并通过一种新的假定的核糖开关关键地控制这种维生素的生物合成， CbiMCbl.我们现在证明VB12关键控制回肠上皮细胞(IEC)的分子和代谢 动态平衡，特别是线粒体呼吸，潜在地限制好氧沙门氏菌(STM)的感染 新生的小鼠。这项研究方案的目的是进一步阐明：(A)VB12在功能上维持 IEC在STM感染过程中的作用，(B)VB12调节IEC中的氧气水平，导致管腔缺氧，从而 控制需氧STM感染和(C)VB12加强回肠上皮完整性并支持效应T辅助细胞(Th) 细胞对STM挑战的反应。最重要的假设是：(1)VB12对分子结构重新编程 STM感染对IECs的影响：(2)VB12对回肠氧合的调节导致限制肠腔缺氧 好氧性STM感染和(3)VB12对IEC功能的调控有助于上皮的完整性和 Th细胞对需氧STM感染的保护性反应。以下具体目标将检验这些假设：1. 阐明VB12在STM感染过程中支持IEC功能的分子机制。2.详细说明 VB12控制好氧性STM感染对IECS线粒体氧的调节作用3.排查障碍 VB12对STM感染的完整性调节和保护性Th细胞应答调查结果如下： 拟议的机制研究将是第一份强调VB12在调节IEC方面的效力的深入报告 这是一种可持续的治疗策略，有可能改善新生儿的健康。

Project Summary/Abstract Incidence of pediatric inflammatory bowel disease (IBD) is increasing worldwide. The causative mechanisms involved in the disease pathogenesis are currently elusive. However, induced pathogenic inflammation due to malnutrition, impacting the ileal epithelium homeostasis, may contribute to disease manifestation. Thus, understanding the dietary risk factors involved in pediatric IBD is urgent. Diet containing micronutrients (e.g., vitamins) functionally controls the genomic mechanisms of the neonatal intestinal cells. Deficiency in host nutritional circuitry, notably during the pre and postnatal periods of pregnancy may not only impair the host- bacteria interaction controlling the gut homeostasis but also deteriorate the metabolic networks required for bacterial syntrophic growth. Vitamin B12 (VB12) is synthesized by some intestinal bacteria. VB12 deficiency may dysfunction ileal epithelial cells (iECs) expressing VB12 receptors (e.g., cubilin, megalin) with severe intestinal disorders post-birth. We recently reported that the newly discovered Propionibacterium strain, P. UF1, regulates phagocytic and protective T cell responses to intestinal pathogen infection in newborn and adult mice. Further, P. UF1 produces VB12 and crucially controls the biosynthesis of this vitamin through a novel putative riboswitch, cbiMCbl. We now demonstrate that VB12 critically controls ileal epithelial cell (iEC) molecular and metabolic homeostasis, particularly the mitochondrial respiration, to potentially limit aerobic Salmonella (STm) infection in newborn mice. The objectives of this research proposal are to further elucidate that (a) VB12 functionally sustains iEC function during STm infection, (b) VB12 regulates oxygen levels in iECs resulting in luminal hypoxia that controls aerobic STm infection and (c) VB12 fortifies ileal epithelium integrity and supports effector T helper (Th) cell response to STm challenge. The overarching hypotheses are: (1) VB12 reprograms the molecular machinery of iECs during STm infection, (2) regulation of ileal oxygenation by VB12 induces the luminal hypoxia that limits the aerobic STm infection and (3) controlling iEC-function by VB12 contributes to epithelial integrity and protective Th cell response to aerobic STm infection. The following Specific Aims will test these hypotheses: 1. Elucidate the molecular mechanisms sustaining iEC function by VB12 during STm infection. 2. Elaborate on the mitochondrial oxygen regulation in iECs by VB12 controlling aerobic STm infection. And 3. Investigate barrier integrity regulation by VB12 and protective Th cell response to STm infection. Results obtained from the proposed mechanistic studies will be the first in-depth report underscoring VB12 potency in regulating iEC function for a sustainable therapeutic strategy that could potentially improve neonatal health.