Microbial transglutaminases generate T cell stimulatory epitopes involved in celiac disease

Celiac disease (CD) is a permanent intolerance to gluten. In CD patients, gluten peptides cause an inflammation in the small intestine leading to tissue damage. Tissue transglutaminase (tTG) is an enzyme involved in the repair of damaged tissue by crosslinking of extracellular matrix proteins. Under certain conditions, tTG can deamidate glutamine into glutamic acid. Compared to native gluten, deamidated gluten elicits a more powerful inflammatory response. To improve the quality and texture of food products microbial transglutaminases (mTG) are used in the food industry.In this study, we investigated whether deamidation of gluten by mTG enhances the immunogenic nature of gluten. We found that mTG have a broader substrate specificity than tTG and deamidate both synthetic and natural gluten peptides which were recognized by gluten-specific T cells.Therefore mTG can enhance the immunogenicity of gluten and should not be used in food products intended for consumption by CD patients.