Immunologic Basis of Cow's Milk-Induced Hypersensitivities

描述（由申请人提供）：食物过敏已成为西方化国家的主要健康问题，目前影响3.5% - 4%的美国人口，牛奶过敏影响2.5%的幼儿。CMA为研究过敏性疾病和耐受性诱导的免疫机制提供了理想的模型。这是一种常见的食物过敏障碍，既反映了“长大后”的“短暂”食物过敏，如许多其他儿童食物过敏（如鸡蛋、大豆、小麦），也反映了“持续的”更严重的形式，类似于终身的花生、树坚果和海鲜过敏。通过盲法食物挑战，诊断是明确的，负责的过敏原[牛奶蛋白]被很好地表征，包括它们的三维结构，并且已经建立了良好的动物模型，可以在分子水平上解剖免疫和系统机制。在过去的批准期间，我们证明了大多数患有ige介导的CMA的儿童可以安全地摄入烘焙[热变性]乳制品而不会产生不良反应，并确定了各种免疫标记物（体液和细胞），将他们与少数无法耐受任何形式的牛奶蛋白的持续性CMA儿童区分开来。通过动物模型和上皮细胞系，研究表明IgE和CD23是小肠增强过敏原摄取所必需的，并且在食物过敏而非食物过敏儿童的粪便中发现，支持它们在过敏素质中的作用以及它们作为临床食物过敏生物标志物的潜力。小鼠CMA模型的研究也表明，特异性乳蛋白在Gl粘膜中的运输方式可能在宿主的最终反应中起关键作用；即免疫耐受vs.过敏原致敏，临床耐受vs.过敏反应。基于我们在之前的中心资助中获得的知识，我们将在一项临床试验中进一步探索临床和潜在的免疫反应，该临床试验检查了分级暴露于热变性乳制品的影响，并在第二项牛奶口服免疫疗法[OIT]加omalizumab的临床试验中，我们假设这将诱导“耐受性”，而不是标准牛奶OIT所见的“脱敏”。我们还将使用新的模型来描述使某些牛奶蛋白致敏的特性，探索它们在细胞水平上是如何加工的，并定义促进CD23转运在食物过敏性疾病中的作用。通过本中心申请中概述的独特资源和合作项目，成功完成这些目标可能会导致食物过敏管理和治疗的新范式，并为患者的诊断和管理提供新的生物标志物。

DESCRIPTION (provided by applicant): Food allergy has become a major health problem in westernized countries and now affects 3.5% - 4% of the U.S. population with cow's milk allergy [CMA] affecting 2.5% of young children. CMA provides an ideal model to study immunologic mechanisms responsible for allergic disease and tolerance induction. It is a common food allergic disorder that reflects both the "transient" form of food allergy that is "outgrown," as seen in many other childhood food allergies [e.g. egg, soy, wheat], and the "persistent," more severe form, similar to life-long peanut, tree nut and seafood allergies. Diagnosis is definitive with the blinded food challenge, the responsible allergens [milk proteins] are well characterized including their 3-dimensional structures, and good animal models have been established that enable dissection of immunologic and systemic mechanisms at the molecular level. Over the past granting period, we demonstrated that the majority of children with IgE-mediated CMA can safely ingest baked [heat-denatured] milk products without adverse effects and identified a variety of immunologic markers [humoral and cellular] that distinguish them from the minority of children with persistent CMA who cannot tolerate any form of milk protein. Using animal models and epithelial cell lines, it was shown that IgE and CD23 are required for enhanced allergen uptake in the small intestine and are found in the stool of food-allergic but not non-allergic children, supporting their role in the allergic diathesis as well as their potential for use as a biomarker of clinical food allergy. Studies in a murine model of CMA also showed that the way specific milk proteins traffick in the Gl mucosa may play a critical role in the ultimate response of the host; i.e. immunologic tolerance vs. allergen sensitization and clinical tolerance vs. allergic reaction. Based on knowledge acquired in our previous Center grant, we will further explore clinical and underlying immunologic responses in one clinical trial examining the effects of graded exposure to heat-denatured milk products, and in a second clinical trial of milk oral immunotherapy [OIT] plus omalizumab, which we hypothesize will induce "tolerance," as opposed to "desensitization" seen with standard milk OIT. We also will use novel models to delineate properties that make certain milk proteins allergenic, explore how they are processed at the cellular level, and define the role of facilitated CD23 transport in food allergic disease. Through the unique resources and collaborative projects outlined in this Center application, successful completion of the aims may lead to new paradigms in the management and treatment of food allergies and provide novel biomarkers for the diagnosis and management of patients. PROJECT 1: Immunologic Responses to Cow's Milk Proteins in IgE-mediated Cow's Milk Allergy (Sampson, H) PROJECT 1 DESCRIPTION (provided by applicant): Cow's milk is the most common cause of food allergy in children, with approximately 1.8% of American infants developing IgE-mediated allergic reactions to cow's milk [~74,000 cases/year]. While ~80% "outgrow" their milk allergy by the 6th birthday, 35% will develop other food allergies and about 60% develop respiratory allergy and asthma. Milk allergy provides an ideal "experiment of nature" to study immunologic mechanisms associated with oral tolerance induction to food and allergic disease. It is the most common food allergy in American children and reflects both the "transient" form of food allergy that is "outgrown," similar to many other childhood food allergies [e.g. egg, soy, wheat], and the "persistent," more severe form, similar to peanut, nuts and seafood allergies. It can be definitively diagnosed with the blinded food challenge and the responsible allergens, milk proteins, are well characterized, including their 3-dimensional structures. Although strict milk avoidance diets have been the "standard of care" for milk-allergic patients, our recent data suggest that the majority of children will tolerate heat-denatured products without deleterious effects. In addition, preliminary studies with oral immunotherapy [OIT] have reported effective "desensitization" of milk-allergic patients, but whether true "tolerance" can be induced with this therapy remains to be demonstrated. In Aim #1 of this project, we will delineate clinical phenotypes of milk-allergic patients based upon their response to various forms of heat-denatured milk proteins, identify novel biomarkers differentiating the subgroups, and elucidate immunologic changes that accompany acquisition of tolerance. Furthermore, we hypothesize that progression toward immunological tolerance will occur more rapidly in children who are actively ingesting milk protein, and that tolerance will be associated with distinct changes in humoral and cellular function. In Aim #2 we will determine whether the combination of anti-lgE and milk OIT will induce clinical "tolerance" compared to the "desensitization" seen with OIT alone, and monitor associated immunologic changes. In conjunction with the other projects in this Center application, successful completion of these Aims will provide new insight into the immunologic changes associated with the development of oral tolerance to food, delineate phenotypic and immunologic differences in milk-allergic individuals, and possibly lead to a new paradigm in the medical management and treatment of milk-allergic individuals.