Protective role of intestinal microbiota in food allergy

描述（由申请人提供）：在美国和发达国家的其他地区，食物过敏的患病率正在以惊人的速度上升。环境刺激改变了有益的肠道细菌的数量，这与这种增加有关。我们实验室的早期工作表明，无法通过TLR 4发出信号的小鼠对食物的过敏反应增强。我们假设肠道细菌是TLR 4配体的来源，并证明了新生儿给药广谱抗生素（Abx）的鸡尾酒在TLR 4充足的小鼠中诱导的过敏反应与TLR 4突变小鼠中所见的相当。在本修订申请中提供的初步数据中，我们已经建立了一种新的食物过敏的无菌模型，并表明直接来自健康小鼠肠道微生物群的明确细菌聚生体可以防止对食物过敏原的全身性高反应性。我们证明，梭菌类中的细菌选择性地诱导屏障保护性反应，包括IL-23/IL-22轴的激活，抗微生物肽Reg 3 B和Reg 3 g的表达的诱导和肠THP和伊加分泌B细胞的扩增;这种反应的一部分是TLR 4依赖性的。我们假设，含有梭菌的微生物群足以引起屏障保护性反应，以防止对食物的过敏反应。在提出的实验中，我们将研究过敏保护细菌种群如何在细胞和分子水平上向宿主传递信号。提供了七个新的初步数据，以支持本修订申请中概述的两个目标。目的1将确定哪些细胞与肠道细菌的相互作用是必要的，足以诱导屏障保护反应。我们已经使用Cre-Lox技术来产生在CD 11 c+树突细胞（DC）和肠上皮细胞（IEC）中MyD 88信号传导中具有靶向突变的小鼠。我们还将研究TLR 4信号传导是否是由Tactus本身所需要的。肠上皮细胞的微阵列分析突出了在梭菌定殖小鼠的上皮中选择性上调的两个新基因/途径;抗微生物肽Reg 3b和芳烃受体（Ahr）的靶基因。这两种途径都与肠道免疫的调节密切相关。目的2a将研究Ahr介导的信号和IL 22如何促进梭菌诱导的屏障保护性反应，防止对食物的过敏反应。最后，目标2b将研究梭菌介导的先天性和适应性免疫系统的激活如何影响上皮紧密连接蛋白的表达和功能。所提出的目标的成功完成为基于肠道微生物群组成的调节来预防或治疗食物过敏的新方法的开发带来了希望。

DESCRIPTION (provided by applicant): The prevalence of food allergy is rising at an alarming rate in the United States and in other parts of the developed world. Environmental stimuli that alter populations of beneficial commensal bacteria have been implicated in this increase. Earlier work from our laboratory showed that mice unable to signal via TLR4 exhibit enhanced allergic responses to food. We hypothesized that commensal bacteria were the source of the TLR4 ligand and demonstrated that neonatal administration of a cocktail of broad-spectrum antibiotics (Abx) induced an allergic response in TLR4 sufficient mice equivalent to that seen in TLR4 mutant mice. In the preliminary data presented in this revised application we have established a novel gnotobiotic model of food allergy and show that a defined bacterial consortium, derived directly from the intestinal microbiota of healthy mice, protects against systemic hyperreactivity to a food allergen. We demonstrate that bacteria in the Clostridia class selectively induce a barrier protective response that includes activation of the IL-23/IL-22 axis, induction of the expression of the anti-microbial peptides Reg3b and Reg3g and the expansion of intestinal Tregs and IgA secreting B cells; part of this response is TLR4-dependent. We hypothesize that a Clostridia-containing microbiota is sufficient to elicit a barrier protective response that protets against allergic responses to food. In the experiments proposed we will examine how allergy-protective bacterial populations deliver signals to their hosts at both the cellular and molecular level. Seven new figures of preliminary data are provided in support of the two Aims outlined in this revised application. Aim 1 will determine which cellular interactions with commensal bacteria are necessary and sufficient to induce a barrier protective response. We have used Cre- Lox technology to generate mice with targeted mutations in MyD88 signaling in CD11c+ dendritic cells (DC) and in intestinal epithelial cells (IEC). We will also examine whether TLR4 signaling is required by the Tregs themselves. Microarray analysis of intestinal epithelial cells highlighted two novel genes/pathways selectively upregulated in the epithelium of Clostridia colonized mice; the anti-microbial peptide Reg3b and a target gene for the aryl hydrocarbon receptor (Ahr). Both pathways have been intimately linked to the regulation of intestinal immunity. Aim 2a will examine how Ahr-mediated signals and IL22 contribute to a Clostridia induced barrier protective response that prevents against an allergic response to food. Finally, Aim 2b will examine how Clostridia mediated activation of the innate and adaptive immune system impacts epithelial tight junction protein expression and function. The successful completion of the Aims proposed holds promise for the development of novel approaches to prevent or treat food allergy based on modulation of the composition of intestinal microbiota.