Histamine-Releasing Factor Oligomers in Food Allergy

项目总结 在过去的几十年里，食物过敏的流行率一直在急剧上升。虽然研究 利用小鼠食物过敏模型极大地促进了我们对其发病机制的理解，有 仍然存在巨大的知识差距。组胺释放因子(HRF)激活IgE中的肥大细胞和嗜碱性粒细胞 依赖的态度。由于它的分泌物是在晚期过敏反应的体液中发现的，HRF已经 与过敏性疾病有关。然而，hrf是否与过敏性疾病有关仍然存在。 这是一个谜，尽管它的分子身份在1995年被揭示。我们2012年的研究通过以下方式改变了这种情况 鉴定部分IgE和Ig G分子为HRF受体：免疫球蛋白Fab-1的定位 HRF分子内的结合位点导致了基于HRF序列的抑制剂N19和H3的发现 多肽以及单体突变体hrf-2ca，所有这些都阻断了hrf-Ig相互作用；预防性 给予这些以肥大细胞为靶点的抑制剂可显著降低过敏性腹泻的发生率。 和过敏反应，以及肠道炎症的严重程度在免疫球蛋白/FcεRI(高亲和力免疫球蛋白 受体)/肥大细胞依赖的食物过敏小鼠模型。HRF以单体形式存在，并以二硫键连接 包括二聚体在内的低聚物。HRF二聚体，而不是单体，具有激活IgE诱导的肥大细胞的能力，并 嗜碱性细胞和增强过敏原触发的这些细胞的激活。HRF低聚体在小范围内增加 食物过敏性动物的肠道。我们的结果共同表明，HRF寡聚体与IgE结合 FcεRI对肠道肥大细胞的作用，导致其激活，这是变应原诱导的最大 肠2型炎症。基于这些新的数据，我们假设HRF齐聚和 HRF-IgE相互作用是启动和放大食物过敏中肠道炎症的两个关键事件。至 为了验证这一假设，我们将用缺乏正常HRF的新突变小鼠进行食物过敏实验 二聚体(目标1)，并试图确定催化HRF齐聚的酶系统(目标2)。我们会 HRF寡聚和N-糖基化对HRF-IgE的影响 在食物过敏过程中，在原子水平上对HRF-IgE相互作用的潜在调节(目标3)。 因此，本研究可能建立一种新的范式，即FcεRI介导的肥大细胞激活由 抗原被HRF寡聚体放大，导致食物过敏中的炎症加剧。

PROJECT SUMMARY The prevalence of food allergy has been dramatically increasing for the last few decades. Although studies using murine models of food allergy have greatly advanced our understanding of its pathogenesis, there are still significant knowledge gaps. Histamine-releasing factor (HRF) activate mast cells and basophils in an IgE- dependent manner. As its secretion was found in body fluids during late-phase allergic reactions, HRF has been implicated in allergic diseases. However, whether HRF is involved in allergic diseases had remained enigmatic, although its molecular identity was revealed in 1995. Our 2012 study changed this situation by identifying a subset of IgE and IgG molecules as HRF receptors: mapping of the immunoglobulin (Ig) Fab- binding sites within the HRF molecule led to the discovery of HRF sequence-based inhibitors, N19 and H3 peptides, as well as a monomeric mutant HRF-2CA, all of which blocked HRF-Ig interactions; prophylactic administration of these inhibitors, which targeted mast cells, strongly reduced the incidence of allergic diarrhea and anaphylaxis, as well as the severity of intestinal inflammation in an IgE/FcεRI (high-affinity IgE receptor)/mast cell-dependent mouse model of food allergy. HRF is present as a monomer and disulfide-linked oligomers including a dimer. HRF dimer, but not monomer, has an ability to activate IgE-primed mast cells and basophils and to enhance allergen-triggered activation of these cells. HRF oligomers increased in the small intestine of food allergic animals. Our results collectively suggest that HRF oligomers crosslink IgE-bound FcεRI on intestinal mast cells, leading to their activation, which is required for allergen-induced maximal intestinal type 2 inflammation. Based upon these novel data, we hypothesize that HRF oligomerization and HRF-IgE interactions are two critical events to initiate and amplify intestinal inflammation in food allergy. To test this hypothesis, we will conduct food allergy experiments with novel mutant mice lacking normal HRF dimer (Aim 1), and seek to identify the enzyme system that catalyzes oligomerization of HRF (Aim 2). We will also investigate the effects of HRF oligomerization and N-glycosylation of HRF and IgEs on HRF-IgE interactions, and potential regulation of HRF-IgE interactions at the atomic level during food allergy (Aim 3). Therefore, this study will likely establish a novel paradigm that FcεRI-mediated mast cell activation triggered by antigen is amplified by HRF oligomers that cause a heightened inflammation in food allergy.