Structural and functional characterization of protective antibodies induced in peanut oral immunotherapy

食物过敏影响高达10%的美国人口，花生是最常见的食物之一 过敏原，经常导致持续的IgE介导的食物过敏。只有一部分食物过敏的患者 口服免疫疗法（OIT）后出现临床耐受性，而大多数仅具有短暂的益处。我们和 其他研究表明，花生过敏原的血清IgG抗体抑制嗜碱性粒细胞的活化，这是一种免疫抑制剂。 OIT耐受性的生物标志物。为了阐明OIT长期耐受的机制，我们还需要 了解这些花生特异性IgG抗体如何在克隆水平上有助于临床保护。 我们的长期目标是为IgE介导的食物过敏开发新的基于抗体的治疗方法， 阐明OIT诱导的长期耐受的潜在抗体介导机制。期间 OIT，花生特异性IgG抗体被诱导并可抑制效应细胞，如肥大细胞或嗜碱性粒细胞。 在体外，这些IgG抗体可以通过阻断IgE被激活来防止过敏原效应细胞活化。 通过过敏原交联并与抑制性受体结合。我们以前的工作集中在Ara h 2上， 大多数免疫显性和临床相关的花生过敏原。在这项研究中，抑制Ara h 2刺激了 嗜碱性粒细胞是耐受的生物标志物，而Ara h 2特异性IgG浓度不是耐受的生物标志物。所以我们 假设OIT后的耐受性是由于诱导了独特的保护性IgG克隆，而不是由于 过敏原特异性IgG的普遍增加。这些保护性抗体有效地防止IgE介导的 反应. 基于这些发现，我们假设保护性抗体具有独特的结构， 这些特征允许它们以竞争性适合度结合Ara h 2的关键表位，并且该表位- 特异性保护性抗体可以功能性地抑制来自不同患者组的变应原特异性IgE。我们 一种方法涉及使用从分离自人的单个抗原特异性B细胞克隆的重组抗体。 OIT后有或没有耐受性的个体。我们在进行这项研究方面处于独特的地位，因为我们有 在抗原特异性B细胞亲和选择、重组抗体克隆和抗体 来自独特患者队列的表征。我们将在以下具体目标中阐述我们的假设：（1） 确定耐受中保护性变应原特异性IgG抗体的Ara h 2结合特征;和（2） 鉴定功能抑制性过敏原特异性IgG抗体的耐受性。 我们预计，拟议的研究将阐明长期临床 OIT在克隆水平上与保护性抗体的有效性，突出了特定克隆的关键作用， 赋予食物过敏的长期耐受性。这项工作将导致新的战略处理食品 过敏

Food allergy affects up to 10% of the US population, and peanut is one of the most common food allergens, often leading to persistent IgE-mediated food allergy. Only a subset of patients with food allergy develop clinical tolerance after oral immunotherapy (OIT), while most only have transient benefit. We and others have shown that serum IgG antibodies to peanut allergens suppress basophil activation, which is a biomarker of tolerance in OIT. In order to elucidate the mechanisms of long-term tolerance in OIT, we still need to understand how these peanut-specific IgG antibodies contribute to clinical protection on a clonal level. Our long-term goal to develop new antibody-based treatments for IgE-mediated food allergies depend on elucidating the underlying antibody-mediated mechanism of long-term tolerance induced by OIT. During OIT, peanut-specific IgG antibodies are induced and can inhibit effector cells, such as mast cells or basophils. in vitro, these IgG antibodies can prevent allergen effector cell activation by both blocking IgE from being cross-linked by allergen and binding to inhibitory receptors. Our previous work focused on Ara h 2, which is the most immunodominant and clinically relevant peanut allergen. In that study, suppression of Ara h 2 stimulated basophils was a biomarker of tolerance while the concentration of Ara h 2 specific IgG, was not. Therefore, we hypothesize that tolerance after OIT results from the induction of uniquely protective IgG clones rather than the general increase in allergen-specific IgG. These protective antibodies effectively prevent IgE-mediated reactions. Based on these findings, we hypothesize that protective antibodies share unique structural characteristics that allow them to bind to critical epitopes of Ara h 2 with competitive fitness and that epitope- specific protective antibodies can functionally suppress allergen-specific IgE from a diverse set of patients. Our approach involves using recombinant antibodies cloned from single antigen-specific B cells isolated from individuals with or without tolerance after OIT. We are uniquely positioned to conduct this study in that we have expertise in affinity-selection of antigen-specific B cells, recombinant antibody cloning, and antibody characterization from a unique patient cohort. We will address our hypothesis in the following specific aims: (1) Define Ara h 2 binding characteristics of protective allergen-specific IgG antibodies in tolerance; and (2) Identify functionally suppressive allergen-specific IgG antibodies in tolerance. We anticipate that the proposed studies will elucidate the connection between long-lasting clinical efficacy of OIT on a clonal level with protective antibodies, highlighting the critical role of specific clones in conferring long-term tolerance in food allergy. This work will lead to new strategies for the treatment of food allergies.