Mast cell regulation of food allergen induced malaise through GDF15-GFRAL signaling

食物过敏与超敏的2型免疫反应有关，这种免疫反应发生在 对食物蛋白质的敏化作用。过敏反应引起适应性免疫记忆的发展， 以抗原特异性Th2细胞和B细胞为特征的，它们能产生IgE和IgG1亚型的抗体。 免疫球蛋白E抗体与组织中的肥大细胞结合，这些免疫球蛋白E肥大细胞单位使快速和旺盛的 对少量食物抗原的召回反应。临床前和临床研究强调了 食物过敏的胃肠道表现，如腹痛、恶心和 然而，肥大细胞是如何引发这些症状的，人们对此知之甚少。GDF15是一种压力- 通过其受体诱导介导厌食、条件性味觉厌恶和呕吐的转化生长因子-b细胞因子， GFra，位于最后一区。GDF15可由1型和2型炎症诱导，但其 在食物过敏方面的作用尚不清楚。这项建议的目的是研究GDF15的作用- GFRNAL信号在驱动过敏小鼠对食物过敏原回避行为中的作用。体内的初步数据 食物过敏模型显示，GDF15在过敏原攻击后迅速诱导，在很大程度上 依赖于IgE、FceR1a表达细胞和白三烯。应用qPCR和FISH技术对小肠组织进行检测 而来自食物和结肠的过敏原挑战小鼠，我们发现结肠，而不是小肠，隐窝上皮 细胞富含GDF15转录本。有趣的是，GDF15的急性药理阻断可以改善 两瓶偏好测试行为范式中的食物过敏原厌恶。这一数据表明，IgE- 介导的肥大细胞激活可能通过白三烯诱导结肠上皮细胞产生GDF15，从而 驱使过敏原厌恶。为了验证这一假设，我们将追求两个目标。目标1将考察以下因素的影响 GDF15和GFra基因缺陷对新生KO小鼠体内食物变应原回避的影响 对食物过敏的BALB/CJ背景株。GDF15和GFre缺乏对肥大的影响 还将描述实验性食物过敏中的细胞介导的免疫反应。Aim 2将检查 IgE介导的肥大细胞激活在实验性食物过敏中如何启动GDF15-GFra信号转导 小鼠在基因或药物上缺乏免疫球蛋白E、肥大细胞和白三烯。依赖于肥大细胞 结肠上皮细胞转录组的变化也将被量化。总而言之，这些研究将 加深我们对胃肠道2型免疫反应如何导致过敏原的理解 诱导的不适，并可能揭示预防口服免疫疗法(OIT)并发症的新靶点。 除了这些学习，申请人还将完成一项高级技术和理论课程 课程作业、临床选修课和科学技能培养。本申请中详细说明的研究和培训 将为他从事与临床相关的基础科学职业做好准备，成为一名内科科学家。

Food allergy is associated with a hypersensitive type 2 immune response that develops following sensitization to food proteins. Allergic sensitization elicits the development of adaptive immune memory, characterized by antigen specific Th2 cells and B-cells which produce antibodies of the IgE and IgG1 isotypes. IgE antibodies bind to tissue resident mast cells, and these IgE-mast cell units enable a rapid and exuberant recall response to low quantities of food antigen. Pre-clinical and clinical studies underscore the importance of IgE antibodies in the gastrointestinal manifestation of food allergy, such as abdominal pain, nausea and vomiting, however what mast-cells induce to initiate these symptoms is poorly understood. GDF15 is a stress- induced TGF-b cytokine that mediates anorexia, conditioned taste aversion, and vomiting through its receptor, GFRAL, located on the area postrema. GDF15 can be induced by type 1 and type 2 inflammation, however its role in the context of food allergy is unclear. The objective of this proposal is to study the role of GDF15- GFRAL signaling in driving avoidance behavior to food allergens in allergic mice. Preliminary data in in vivo food allergy models demonstrates GDF15 is rapidly induced upon allergen challenge in a manner largely dependent on IgE, FceR1a expressing cells, and leukotrienes. Using qPCR and FISH of the small intestine and colon from food allergen challenged mice, we find that colonic, but not small intestinal, crypt epithelial cells are enriched in GDF15 transcripts. Interestingly, acute pharmacological blockade of GDF15 ameliorates food allergen aversion in a two-bottle preference test behavioral paradigm. This data suggests that IgE- mediated mast cell activation elicits colonic epithelial GDF15 production, potentially through leukotrienes, to drive allergen aversion. To test this hypothesis two aims will be pursued. Aim 1 will examine the effect of genetic deficiency of GDF15 and GFRAL on food allergen avoidance in vivo using newly generated KO mice on the food allergy susceptible BALB/cJ background strain. GDF15 and GFRAL deficiency’s effect on mast- cell mediated immune responses in experimental food allergy will also be characterized. Aim 2 will examine how IgE mediated mast cell activation initiates GDF15-GFRAL signaling in experimental food allergy using mice genetically or pharmacologically deficient in IgE, mast cells, and leukotrienes. Mast-cell dependent changes in the transcriptome of colonic epithelial cells will too be quantified. Together, these studies will enhance our understanding of how type 2 immune responses in the gastrointestinal tract lead to allergen induced malaise, and may reveal novel targets to prevent complications of oral immunotherapy (OIT). Alongside these studies, the applicant will complete a program of advanced technical and theoretical coursework, clinical electives, and scientific skill building. The research and training detailed in this application will prepare him to pursue a clinically relevant basic science career as a physician scientist.