Trefoil peptides: what are they and what do they do?

The trefoil peptides help to protect the lining of the gastrointestinal tract. They have two beneficial roles in the gastrointestinal tract: 1. In basal circumstances, they may play a role in mucus stabilisation. 2. When an acute injury occurs, their rapid upregulation is important in stimulating the repair process, particularly that of epithelial restitution. The trefoil peptide motif consists of a unique 'three-loop' structure formed by intrachain disulphide bonds. Three members of this family have been identified in humans; spasmolytic polypeptide, intestinal trefoil factor and pS2. The trefoil peptides are expressed by mucus-producing cells throughout the normal gastrointestinal tract in a site-specific manner. In addition, the production of all three trefoil peptides is ectopically expressed in cells surrounding areas of damage in conditions such as peptic ulceration and inflammatory bowel disease.