Food allergens, such as the Ara h 1 peanut protein, can be altered non-enzymatically by advanced glycation endproducts (AGEs), and these modifications may affect the pathogenesis of food allergy. Nε-carboxymethyl lysine (CML) is a commonly used marker for non-enzymatic processing induced AGE modification of food allergens. We evaluated the ability of digestive, cytosolic, and endolysosomal proteases to cleave CML modified and unmodified Ara h 1 peptides using in vitro assays. Mass-spectrometric analysis of the digested peptides demonstrated that CML modification renders these peptides refractory to trypsin digestion in simulated intestinal fluid. The Ara h 1 peptides were very stable in simulated gastric fluid, and were at least as stable as several viral peptides in the cytosolic and endlysosomal digestion assays. One of the tested peptides contains a lysine residue previously shown to be CML modified in peanuts and it lies in a previously mapped linear IgE epitope. We did not observe differences in serum IgE binding between the modified and parental peptides. Our findings suggest a molecular mechanism for the increased resistance of thermally processed peanut allergens, such as Ara h 1, to digestion in intestinal fluid after heating. Our results could help explain how food processing-induced modifications may lead to more potent food allergens by acting to protect intact IgE epitopes from digestion by proteases.

Advanced glycation endproducts may affect digestion and antigen processing of food allergens

249th National Meeting (2015)

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