University of Tuscia, Department of Agricultural and Forestry Science, Via S. Camillo de Lellis s.n.c., 01100 Viterbo, Italy; INRA, UR 1268 Biopolymers Interactions Assemblies, 44316 Nantes, France.
INRA, UR 1268 Biopolymers Interactions Assemblies, 44316 Nantes, France.
Food Res Int. 2019 Apr;118:22-31. doi: 10.1016/j.foodres.2018.02.011. Epub 2018 Feb 9.
Wheat is one of the most important crops in the world in terms of human nutrition. With regards to health, some individuals exhibit wheat-related disorders such as food allergy to wheat (FAW). In this disorder, gluten is involved, particularly the gliadins which are among the main proteins responsible for FAW. Food processing, as well as digestibility and intestinal transport are key factors to consider since they may affect the allergenic potential of food allergens. Wheat is always consumed after heat processing and this step may impact epitope accessibility by inducing aggregation and may irreversibly destroy conformational epitopes. Our aim was to investigate the effects of heating and digestion on the structure of well-known allergens (total gliadins and α-gliadins) and their capacity to maintain their allergenic potential after crossing an intestinal barrier. The sizes of the processed (heated and heated/digested) proteins were characterized by laser light scattering and chromatographic reverse phase. The IgE-binding capacities of native and processed proteins were checked using a dot blot with sera from wheat allergenic patients. Furthermore, the abilities of these samples to cross the intestinal barrier and to induce mast cell degranulation were investigated by combining two in vitro cellular models, Caco-2 and RBL-SX38. The heat treatment of total gliadins and α-gliadins induced the production of large aggregates that were hardly recognized by IgE of patients in dot-blot. However, after limited pepsin hydrolysis, the epitopes were unmasked, and they were able to bind IgE again. Native proteins (gliadins and α-type) and processed forms were able to cross the Caco-2 cells in small amount. Permeability studies revealed the capacity of α-gliadins to increase paracellular permeability. In the RBL assay, the total native gliadins were able to trigger cell degranulation, but none of their processed forms. However after crossing the CaCo-2 monolayer, processed gliadins recovered their degranulation capacity to a certain extent. Total native gliadins remained the best allergenic form compared to α-type.
小麦是人类营养方面最重要的作物之一。就健康而言，一些人表现出与小麦有关的疾病，例如对小麦的食物过敏（FAW）。在这种疾病中，谷蛋白起作用，特别是麦醇溶蛋白，它是引起 FAW 的主要蛋白质之一。食品加工、消化率和肠道转运是需要考虑的关键因素，因为它们可能会影响食物过敏原的致敏潜力。小麦总是经过热处理后再食用，这一步骤可能通过诱导聚集来影响表位的可及性，并可能不可逆地破坏构象表位。我们的目的是研究加热和消化对已知过敏原（总麦醇溶蛋白和α-麦醇溶蛋白）结构的影响及其在穿过肠道屏障后保持致敏潜力的能力。处理后的（加热和加热/消化）蛋白质的大小通过激光光散射和色谱反相来表征。使用来自小麦过敏患者的血清进行斑点印迹法检查天然和处理后蛋白质的 IgE 结合能力。此外，通过结合两种体外细胞模型 Caco-2 和 RBL-SX38，研究了这些样品穿过肠道屏障并诱导肥大细胞脱颗粒的能力。总麦醇溶蛋白和α-麦醇溶蛋白的热处理诱导了大聚集体的产生，这些聚集体在斑点印迹中很难被患者的 IgE 识别。然而，经过有限的胃蛋白酶水解后，表位被暴露出来，它们又能够与 IgE 结合。天然蛋白质（麦醇溶蛋白和α型）和处理形式能够以少量穿过 Caco-2 细胞。通透性研究表明α-麦醇溶蛋白能够增加细胞旁通透性。在 RBL 测定中，总天然麦醇溶蛋白能够触发细胞脱颗粒，但它们的任何处理形式都不能。然而，在穿过 CaCo-2 单层后，处理过的麦醇溶蛋白在一定程度上恢复了脱颗粒能力。与α型相比，总天然麦醇溶蛋白仍然是最佳的致敏形式。
