Abstract：
Casein (CN) is the primary allergenic protein in cow\'s milk, contributing to the worldwide escalating prevalence of food allergies. However, there remains limited knowledge regarding the effect of structural modifications on CN allergenicity. Herein, we prepared three modified CNs (mCN), including sodium dodecyl sulfate and dithiothreitol-induced linear CN (LCN), transglutaminase-cross-linked CN (TCN), and glucose-glycated CN (GCN). The electrophoresis results indicated widespread protein aggregation among mCN, causing variations in their molecular weights. The unique internal and external structural characteristics of mCN were substantiated by disparities in surface microstructure, alterations in the secondary structure, variations in free amino acid contents, and modifications in functional molecular groups. Despite the lower digestibility of TCN and GCN compared to LCN, they significantly suppressed IL-8 production in Caco-2 cells without significantly promoting their proliferation. Moreover, GCN showed the weakest capacity to induce LAD2 cell degranulation. Despite the therapeutic effect of TCN, GCN-treated mice displayed the most prominent attenuation of allergic reactions and a remarkably restored Th1/Th2 imbalance, while LCN administration resulted in severe allergic phenotypes and endotypes in both cellular and murine models. This study highlighted the detrimental effect of linear modifications and underscored the significance of glycation in relation to CN allergenicity.
摘要：
酪蛋白(CN)是牛奶中的主要致敏蛋白,导致食物过敏在全球范围内流行。然而,关于结构修饰对CN变应原性的影响的知识仍然有限。在这里，我们制备了三种修饰的CN(mCN)，包括十二烷基硫酸钠和二硫苏糖醇诱导的线性CN（LCN），转谷氨酰胺酶交联的CN（TCN），和葡萄糖糖化的CN(GCN)。电泳结果表明mCN之间广泛的蛋白质聚集，导致它们分子量的变化。表面微观结构差异证实了mCN独特的内部和外部结构特征，二级结构的改变，游离氨基酸含量的变化，和功能分子基团的修饰。尽管与LCN相比，TCN和GCN的消化率较低，它们显著抑制Caco-2细胞中IL-8的产生而不显著促进其增殖。此外，GCN显示最弱的诱导LAD2细胞脱粒的能力。尽管TCN的治疗效果，GCN处理的小鼠表现出最显著的过敏反应减弱和显著恢复的Th1/Th2失衡,而LCN给药在细胞和小鼠模型中都会导致严重的过敏性表型和基因型。这项研究强调了线性修饰的有害作用，并强调了糖基化与CN变应原性有关的重要性。
