Partially-degraded gluten peptides from cereals trigger celiac disease (CeD), an autoimmune enteropathy occuring in genetically susceptible persons. Susceptibility genes are necessary but not sufficient to induce CeD and additional environmental factors related to unfavorable alterations in the microbiota have been proposed. We investigated gluten metabolism by opportunistic pathogens and commensal duodenal bacteria and characterized the capacity of the produced peptides to activate gluten-specific T-cells from CeD patients.