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

The mammalian carbohydrate galactose-α1,3-galactose (α-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 α-Gal glycoproteins using an in vitro model. Bovine thyroglobulin (BTG), a typical α-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 α-Gal epitope on the obtained peptides was demonstrated by an anti-α-Gal antibody and IgE from red meat allergic patients. The α-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 α-Gal residues were identified at Asn1756, Asn1850 and Asn2231. Thus allergenic α-Gal epitopes are stable to pepsinolysis, reinforcing their role as clinically relevant food allergens.

In:Scientific reports: Springer Science and Business Media LLC7:1, s. 5201-2045-2322

By the author/editor: Apostolovic, D; Krstic, M; Mihailovic, J; Starkhammar, M; Velickovic, TC; Hamsten, C; show more...; van Hage, M; show less...

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