A global view of oat immunogenicity for celiac disease, from genes to cellular response

Celiac disease is an autoimmune disease triggered by the ingestion of gluten proteins and manifested in the small intestine. Celiac patients must keep a strict gluten-free diet. Although pure oats technically fulfil the criteria set for gluten-free products, the safety of oats in general or of distinct cultivars has been questioned. In this study we investigated 23 oat cultivars and lines that are commercially relevant, or have been suggested to induce adverse activity, or both. The oat seeds were investigated systematically for celiac epitope gene expression by RNA sequencing, peptide detection and quantification by mass spectrometry, and patient-derived T-cell activation to increase the knowledge on their risks. The RNA expression data showed three known avenin-specific T-cell epitopes to be expressed in low abundance in all cultivars with some degree of variation. Two of the three epitopes were also detectable in comparable amounts at the protein level in all cultivars, but their amounts were quite low, together averaging 2.6 mg/kg. Avenin preparations did not induce comprehensive IFN-γ secretion in celiac patients' peripheral blood cells. Any particularly ‘toxic’ cultivar and all commercial oat cultivars presented generally very low abundances of celiac epitopes on both gene and protein levels and are considered safe for consumption.