Ancestral Wheat Types Release Fewer Celiac Disease Related T Cell Epitopes than Common Wheat upon Ex Vivo Human Gastrointestinal Digestion

Celiac disease (CeD) is an autoimmune enteropathy triggered by immunogenic gluten peptides released during the gastrointestinal digestion of wheat. Our aim was to identify T cell epitope-containing peptides after ex vivo digestion of ancestral (einkorn, spelt and emmer) and common (hexaploid) wheat (Fram, Bastian, Borsum and Mirakel) using human gastrointestinal juices. Wheat porridge was digested using a static ex vivo model. Peptides released after 240 min of digestion were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ESI MS/MS). Ex vivo digestion released fewer T cell epitope-containing peptides from the ancestral wheat varieties (einkorn (n = 38), spelt (n = 45) and emmer (n = 68)) compared to the common wheat varieties (Fram (n = 72), Borsum (n = 99), Bastian (n = 155) and Mirakel (n = 144)). Neither the immunodominant 33mer and 25mer alpha-gliadin peptides, nor the 26mer gamma-gliadin peptide, were found in any of the digested wheat types. In conclusion, human digestive juice was able to digest the 33mer and 25mer alpha-gliadin, and the 26mer gamma-gliadin derived peptides, while their fragments still contained naive T cell reactive epitopes. Although ancestral wheat released fewer immunogenic peptides after human digestion ex vivo, they are still highly toxic to celiac patients. More general use of these ancient wheat variants may, nevertheless, reduce CeD incidence.