Effects of Heating and Glycation of β-Lactoglobulin on Its Recognition by IgE of Sera from Cow Milk Allergy Patients

Abstract

beta-Lactoglobulin (beta-LG) is one of the cow's major milk proteins and the most abundant whey protein. This globular protein of about 18 kDa is folded, forming a beta-barrel (or calyx) structure. This structure is stabilized by two disulfide bonds and can be altered by heating above 65 degrees C. beta-LG is also one of the major allergens in milk. Heating is one of the most common technologic treatments applied during many milk transformations. During heating in the presence of reducing sugars, beta-LG is also submitted to the Maillard reaction, which at the first stage consists of the covalent fixation of sugars on the epsilon-amino groups of lysyl residues. The following steps are condensation and polymerization reactions leading to the formation of melanoidins (brown pigments). Despite the frequency of use of heating during milk transformation, the effects of heat-induced denaturation and of glycation of beta-LG on its recognition by IgE from cow's milk allergy (CMA) patients are not fully understood. The objectives of our work were to evaluate the effect of heat-induced denaturation of bovine beta-LG on binding of IgE from CMA patients and to determine the effect of moderate glycation on the degree of recognition by IgE. We showed that heat-induced denaturation (loss of tertiary and secondary structures) of beta-LG is associated with weaker binding of IgE from CMA patients. It was also shown that moderate glycation of beta-LG in early stages of Maillard reaction has only a small effect on its recognition by IgE, whereas a high degree of glycation has a clear "masking" effect on the recognition of epitopes. This demonstrates the importance of epsilon-amino groups of lysines in the definition of epitopes recognized by IgE.

Effects of heating, autoclaving and ultra-high pressure on the solubility, immunoreactivity and structure of major allergens in egg

“…Among all of these strategies, thermal processing has been verified to be a promising tool that can lead to the destruction of the secondary and tertiary structures of proteins, along with disulfide bond cleavage and new disulfide bond formation, thereby masking protein epitomes and reducing the allergenicity of the allergen (Rao et al, 2016). Therefore, many studies have investigated the thermal effects on common allergens, primarily the allergens in peanut (Rao et al, 2016), soybean protein (Li, Zhu, Zhou, Peng, & Guo, 2016), milk (Sampson, 2004;Xu, Shi, Yao, Jiang, & Luo, 2015), wheat, and almond (Taheri-Kafrani et al, 2009), as well as egg OVT (Fu et al, 2010;Tong, Gao, Chen, & Li, 2012), at different temperatures. Due to their complex conformational structure, different allergens exhibit different changes in their characteristics.…”

Predicting Food Challenge Outcomes for Baked Milk: Role of Specific IgE and Skin Prick Testing

“…8 Exposing milk proteins to high temperatures through baking reduces allergenicity by destroying the conformational epitopes. 9,10 Analysis of serum samples of children with persistent cow's milk allergy demonstrates significantly higher ratio of sIgE to linear versus conformational epitopes compared to children who have achieved tolerance. 11 In addition to heating, milk protein allergenicity may also be decreased through interaction with other food proteins in a complex food, such as in a wheat matrix in a baked muffin or cupcake.…”

Ovalbumin Modified with Pyrraline, a Maillard Reaction Product, shows Enhanced T-cell Immunogenicity

“…The MR reportedly alters IgE binding and mediator release capacities of some food allergens by glycations (3)(4)(5)(6)(7). Evidence has also accumulated to show that some glycation structures of AGEs could function as immune epitopes for dendritic cells (DCs) (8 -11).…”