Gut Dendritic Cells and Allergic Sensitization

描述（由申请人提供）：食物过敏影响多达8%的儿科人群，大约2%的成年人群患有食物过敏。对食物蛋白质过敏致敏而非耐受的机制尚不清楚。我们假设，在胃肠道中的树突状细胞（DC）是通过摄取食物蛋白质并将其呈递给胃肠道有组织淋巴组织中的T淋巴细胞而致敏的关键介质。我们将使用对牛奶过敏原β-乳球蛋白（BLG）食物过敏的小鼠模型来检验这一假设。喂食BLG加佐剂霍乱毒素（CT）的C3 H/HeJ小鼠，而不是仅喂食BLG的小鼠，产生针对BLG的IgE抗体，并且当用BLG再次激发时经历全身过敏反应。我们将在耐受性（单独抗原）或过敏性致敏（CT）的背景下跟踪喂食后肠粘膜中FITC标记的BLG的摄取。我们将确定CT是否改变胃肠相关淋巴组织内抗原的呈递。将通过用FltSL扩增DC或在致敏前用基于白喉毒素的消耗系统消耗DC来评估DC在对BLG的过敏性致敏发展中的作用。将确定DC操作对BLG特异性抗体水平、过敏反应的严重程度和对抗原激发的细胞因子应答的影响。潜在的诱导位点，包括派伊尔结（PP）和肠系膜淋巴结（MLN）的作用将使用两种方法来解决。第一种方法将使用有或没有PP的肠袢的手术准备，然后通过肠袢致敏，以测试PP是否是过敏致敏所必需的。其次，PP或PP加MLN将通过用光敏素-β-受体和肿瘤坏死因子受体融合蛋白治疗小鼠来消融。从这些实验的结果将提供一个更好的理解如何正常耐受性反应的食物蛋白质偏离变应性致敏。

DESCRIPTION (provided by applicant): Food allergy affects up to 8% of the pediatric population, and approximately 2% of the adult population suffers from food allergy. The mechanisms responsible for allergic sensitization, rather than tolerance, to food proteins is not known. We hypothesize that dendritic cells (DCs) in the gastrointestinal tract are key mediators of sensitization by taking up food proteins and presenting them to T lymphocytes in organized lymphoid tissue of the gastrointestinal tract. We will test this hypothesis using a mouse model of food allergy to the cow's milk allergen beta-lactoglobulin (BLG). C3H/HeJ mice fed BLG plus the adjuvant cholera toxin (CT), but not mice fed BLG alone, develop IgE antibodies against BLG and undergo systemic anaphylaxis when re-challenged with BLG. We will track the uptake of FITC-labelled BLG in the intestinal mucosa after feeding in the context of tolerance (antigen alone) or in the context of allergic sensitization (with CT). We will determine if CT alters the presentation of antigen within the gastrointestinal associated lymphoid tissue. The role of DCs in the development of allergic sensitization to BLG will be assessed by expanding DCs with FltSL, or depleting them with a diptheria toxin-based depletion system prior to sensitization. The effect of DC manipulation on BLG-specific antibody levels, severity of anaphylaxis, and cytokine responses to antigen challenge will be determined. The role of potential inductive sites including Payer's patches (PP) and mesenteric lymph nodes (MLN) will be addressed using two approaches. The first approach will use surgical preparation of intestinal loops with or without a PP, followed by sensitization via the loops to test if PP is necessary for allergic sensitization. Secondly, PP, or PP plus MLN will be ablated by treatment of mice with lymphotoxin-beta-receptor and tumor necrosis factor receptor fusion proteins. The results from these experiments will provide a better understanding of how a normally tolerogenic response to a food protein deviates toward allergic sensitization.