Purified oat protein can trigger acute symptoms linked to immune activation in coeliac disease patients but not histological deterioration

Background Oat ingestion in coeliac disease (CD) is generally regarded as safe but can trigger enteropathy and T cells specific for oat avenin in the gut and blood of some individuals. Objective To correlate immune and clinical outcomes to oats, purified avenin and oat feeding studies were performed to examine symptoms, T-cell immunity and intestinal histology in CD. Design 33 treated HLA-DQ2.5+ adult CD patients underwent single-bolus or 6-week oat avenin or 3-month whole oats ingestion. T cell activation after avenin ingestion was measured using serum interleukin 2 (IL-2), a sensitive and specific biomarker of gluten-induced T cell activation and symptoms in CD. Symptom measures, intestinal histology, and immune studies on blood and duodenum were undertaken. Results Among 29 CD participants, avenin induced dose-dependent T-cell activation in 11 (38%) and acute symptoms in 17 (59%). Higher IL-2 levels correlated with more severe symptoms. A single highly symptomatic patient vomited in response to avenin (1/29; 3%) and exhibited a striking pro-inflammatory cytokine profile similar to wheat-induced responses. Avenin increased the frequency of CD38-expressing tetramer+integrin β7+ T effector memory CD4+ T cells in the blood, however symptoms, IL-2 release and tetramer frequency fell following 6-week avenin intake and no enteropathy was observed. Conclusion Gluten-contamination-free oats can trigger acute dose-dependent immune and symptom responses but usually at a level insufficient to cause sustained symptoms or enteropathy. In 1 of 29 (3%) participants, oat avenin triggered a pro-inflammatory wheat-like response, highlighting that a minority of CD patients may need to exclude oats. Informed choice regarding oats ingestion in CD is important.