Blocking celiac antigenicity of the glutamine-rich gliadin 33-mer peptide by microbial transglutaminase

Celiac disease (CD) is a T cell-mediated enteropathy of the small intestine and caused by the ingestion of wheat gluten and related prolamins in barley and rye. However, there is no effective therapy to alleviate symptoms of celiac disease except for a life-long gluten-free diet. Recent studies showed that modification by microbial transglutaminase (mTG) could reduce the gliadin-specific immune response. In the present study, different acyl-acceptor substrates in combination with mTG were used to modify the model 33-mer peptide (LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF), which is a particular celiac toxic alpha-gliadin peptide. RP-HPLC and LC-ESI-MS were performed to test the extent of the modifications. R5 ELISA and G12 ELISA were used to analyze the antigenicity of the modified peptide. The shifts of retention time and molecular weight showed great modification of 33-mer peptide after 2 h of incubation with mTG. When acyl-acceptor substrates were crosslinked with 33-mer peptide, the antigenicity of modified peptide forms was decreased compared to its initial level. In summary, it is demonstrated that mTG is active on a variety of chemically acyl-acceptor substrates. Transamidation by mTG with an appropriate amine donor can be used to block the antigenicity of gliadin peptide related to celiac disease. These findings highlight a potential strategy to prevent cereal toxicity in celiac disease.