Mechanisms of L. reuteri in regulating intestinal inflammation

描述(由申请人提供)：鲁氏乳杆菌(LR)对几种人类疾病有有益的作用。坏死性小肠结肠炎(NEC)是最常见的严重胃肠道疾病，影响7%的早产儿。我们的初步研究表明，在患有实验性NEC的新生小鼠中，LR喂养降低了死亡率和肠道炎症，同时增加了肠道粘膜调节性T细胞(Tregs)， 抗炎特性。具体目的：1.确定LR是否通过细菌识别树突状细胞(DC)上的Toll样受体(TLRs)促进耐受树突状细胞(DC)的产生。肠道炎症被认为是通过DC与粘膜辅助T细胞(Th1和Th17)的相互作用来维持的，并被Tregs减轻。我们将测量TLRs基因缺陷小鼠的NEC严重性、对LR的反应、Tregs、Th1和Th17效应的百分比。2.为了阐明LR条件下的Tregs是否能更有效地抑制炎症肠道中的Th1/Th17效应，我们将从LR喂养的小鼠中过继地将带有同源标记的Tregs转移到接受NEC的新生小鼠中，以确定外源Tregs是否具有保护作用。3.为了确定当天然Tregs(NTreg)耗尽时，LR是否能够在肠粘膜中诱导Tregs(ITregs)，我们将用抗CD25抗体来耗尽nTregs，并确定LR是否促进iTreg的发育并保持减轻肠道炎症的能力。这些目的将为研究reuri乳杆菌调节新生儿肠道炎症的机制提供新的见解。结果将有助于选择生物标记物来跟踪NEC的演变，并比较不同益生菌在人类婴儿中的效力。

DESCRIPTION (provided by applicant): Lactobacillus reuteri (LR) has beneficial effects in several human diseases. Necrotizing enterocolitis (NEC) is the most common severe gastrointestinal condition affecting 7% of premature infants. Our preliminary studies demonstrated in neonatal mice with experimental NEC that LR feeding reduces mortality and intestinal inflammation, while increasing intestinal mucosal regulatory T cells (Tregs), cells with anti-inflammatory properties. Specific Aims: 1. To determine whether LR facilitates the generation of tolerogenic dendritic cells (DCs) via bacterial recognition receptors on DC ("sentinel cells") called Toll like receptors (TLRs). Gut inflammation is believed to be sustained by DC interaction with mucosal helper T cells (Th1 and Th17) and reduced by Tregs. We will measure NEC severity, response to LR, percentage of Tregs, Th1, and Th17 effectors in mice genetically deficient in TLRs. 2. To elucidate if LR-conditioned Tregs will be more efficient to suppress Th1/Th17 effectors in the inflamed gut, we will adoptively transfer Tregs bearing congenic markers from LR-fed mice to newborn mice undergoing NEC to determine if exogenous Tregs protect. 3. To determine whether LR is capable of inducing Tregs (iTregs) in the intestinal mucosa when natural Tregs (nTreg) are depleted, we will deplete nTregs by anti-CD25 antibody and determine if LR enhances iTreg development and remains capable of reducing intestinal inflammation. These aims will provide novel insights into mechanisms of Lactobacillus reuteri regulation of neonatal intestinal inflammation. Results will facilitate the selection of biomarkers to follow the evolution of NEC and to compare the potency of different probiotics in the human infant.