On the Role of Dipeptidyl Peptidase IV in the Digestion of an Immunodominant Epitope in Celiac Disease
An immunodominant gliadin epitope provoking celiac disease seems to be notably resistant to digestion with pepsin and pancreatic endopeptidases. This means that the capacity of the intestinal mucosa to digest it will be critical to the disease provoking capability of the peptide. We have shown that a peptide containing the immunodominant epitope is efficiently digested from the N-terminal end by dipeptidyl peptidase IV. Similar results have been obtained in a parallel work by Hausch et al.12, who in addition demonstrated that dipeptidyl carboxypeptidase I is of importance for digestion of the epitope from the C-terminal end. We have earlier demonstrated that dipeptidyl peptidase IV is low in celiac disease and also that it shows a substantial depression in patients in remission13. Even if a variation of the enzyme level is not of primary importance in the pathogenesis of the disease, it may that the relative capacity for the digestion of the peptide can be exceeded after a meal rich in wheat proteins, and thereby contribute to the development of the disease.
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