Gut Dendritic Cells and Allergic Sensitization

描述(申请人提供)：食物过敏影响高达8%的儿科人口，约2%的成年人口患有食物过敏。对食物蛋白质过敏的机制，而不是耐受性，目前尚不清楚。我们假设胃肠道中的树突状细胞(DC)是致敏的关键介质，通过摄取食物蛋白并将它们呈递给胃肠道有组织的淋巴组织中的T淋巴细胞。我们将使用牛奶过敏原β-乳球蛋白(BLG)的食物过敏小鼠模型来验证这一假设。饲喂BLG和佐剂霍乱毒素(CT)的C3H/HeJ小鼠，而不是单独饲喂BLG的小鼠，产生抗BLG的IgE抗体，并在BLG再次攻击时发生全身过敏反应。我们将跟踪FITC标记的BLG在耐受(单独抗原)或过敏致敏(CT)背景下喂养后在肠粘膜中的摄取情况。我们将确定CT是否改变了胃肠道相关淋巴组织中的抗原呈递。将通过用FltSL扩增树突状细胞或在致敏前用白喉毒素耗竭系统耗尽它们来评估树突状细胞在发展对BLG过敏反应中的作用。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攻击的细胞因子反应的影响将被确定。潜在的诱导部位包括Payer‘s补片(PP)和肠系膜淋巴结(MLN)的作用将通过两种方法来解决。第一种方法将使用外科手术准备有或没有PP的肠环，然后通过环进行致敏，以测试PP是否对过敏致敏是必要的。其次，PP或PP+MLN将通过淋巴毒素-β受体和肿瘤坏死因子受体融合蛋白处理小鼠而被消融。这些实验的结果将提供更好的理解，了解对食物蛋白质的正常耐受性反应是如何偏离过敏敏化的。

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.