Peptidomics of an in vitro digested ?-Gal carrying protein revealed IgE-reactive peptides.

ABSTRACT: The mammalian carbohydrate galactose-?1,3-galactose (?-Gal) causes a novel form of food allergy, red meat allergy, where patients experience severe allergic reactions several hours after red meat consumption. Here we explored gastric digestion of ?-Gal glycoproteins using an in vitro model. Bovine thyroglobulin (BTG), a typical ?-Gal carrying glycoprotein, was digested with pepsin. The resulting peptides were characterised by SDS PAGE, immunoblot and ImmunoCAP using sera from 20 red meat allergic patients. During pepsinolysis of BTG, a wide range of peptide bands was observed of which 14 to 17?kDa peptides remained stable throughout the gastric phase. The presence of the ?-Gal epitope on the obtained peptides was demonstrated by an anti-?-Gal antibody and IgE from red meat allergic patients. The ?-Gal digests were able to inhibit up to 86% of IgE reactivity to BTG. Importantly, basophil activation test demonstrated that the allergenic activity of BTG was retained after digestion in all four tested patients. Mass spectrometry-based peptidomics revealed that these peptides represent mostly internal and C-terminal parts of the protein, where the most potent IgE-binding ?-Gal residues were identified at Asn1756, Asn1850 and Asn2231. Thus allergenic ?-Gal epitopes are stable to pepsinolysis, reinforcing their role as clinically relevant food allergens.

SUBMITTER: Apostolovic D 

PROVIDER: S-EPMC5507865 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature