Molecular Mechanism of Glycation Structure-Mediated Immune Recognition and Sensitization by Typical Milk Allergens

This study examines how α-dicarbonyl compounds─methylglyoxal (MGO) and glyoxal (GO)─affect the structure and allergenicity of β-lactoglobulin (β-LG) and α-casein (α-CN) during thermal processing. Glycation-induced changes were analyzed using SDS-PAGE, circular dichroism, and HPLC-MS/MS, while advanced glycation end-products (AGEs) were quantified via UHPLC-QqQ-MS/MS. Results showed that GO was more reactive than MGO, modifying Lys/Arg residues and increasing AGEs in a temperature- and concentration-dependent manner. Glycation reduced the IgE-binding capacity of β-LG but enhanced that of α-CN. In vitro studies revealed that glycated β-LG disrupted Caco-2 monolayer integrity and was more efficiently internalized by bone marrow-derived dendritic cells (BMDCs), upregulating costimulatory factors including CD80, CD86, and CD103. Transcriptomic analysis of monocyte-derived dendritic cells linked glycated β-LG to IL-17, the Toll-like receptor, and NF-κB pathways. Further pathway inhibition experiments demonstrated that the TLR4/NF-κB axis is an important contributor to BMDC maturation and inflammatory cytokine production induced by glycated β-LG. These findings demonstrate that MGO and GO alter the conformational structures and IgE-binding epitopes of milk allergens during heating, differentially modulating their allergenicity. This study provides mechanistic insights into how thermal processing affects the allergenic properties of food allergens, offering new strategies for food safety evaluation and allergy control.