Gut Dendritic Cells and Allergic Sensitization

描述（由申请人提供）：食物过敏影响高达8%的儿科人口，大约2%的成年人患有食物过敏。对食物蛋白质的过敏致敏（而非耐受性）机制尚不清楚。我们假设胃肠道中的树突状细胞（dc）通过摄取食物蛋白并将其呈递给胃肠道有组织淋巴组织中的T淋巴细胞，是致敏的关键介质。我们将使用对牛奶过敏原-乳球蛋白（BLG）食物过敏的小鼠模型来验证这一假设。C3H/HeJ小鼠饲喂BLG加佐剂霍乱毒素（CT），而非单独饲喂BLG的小鼠，在再次饲喂BLG时产生针对BLG的IgE抗体并发生全身过敏反应。我们将在耐受（单独抗原）或过敏致敏（CT）的情况下，追踪进食后肠黏膜中fitc标记的BLG的摄取情况。我们将确定CT是否改变胃肠道相关淋巴组织内抗原的表现。将通过使用FltSL扩展dc或在致敏前使用白喉毒素耗尽系统来评估dc在BLG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、过敏反应严重程度和细胞因子对抗原攻击的反应的影响。潜在的诱导部位，包括支付者补丁（PP）和肠系膜淋巴结（MLN）的作用将通过两种方法来解决。第一种方法将使用手术准备带或不带PP的肠袢，然后通过肠袢进行致敏，以测试PP对过敏致敏是否必要。其次，用淋巴毒素- β受体和肿瘤坏死因子受体融合蛋白治疗小鼠，可使PP或PP + MLN消融。这些实验的结果将更好地理解对食物蛋白质的正常耐受性反应是如何偏离过敏致敏的。

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.