GROWTH-FACTORS AND THE GASTROINTESTINAL-TRACT

This paper reviews areas of interest in gut mucosal growth factor phys iology. Several epidermal growth factor (EGF)-like peptides (EGF, tran sforming growth factor [TGF]-alpha, heparin-binding EGF-like peptide, amphiregulin, and betacellulin) have been identified in the gut. EGF i s produced by the salivary glands and is present in milk. It may act o n the mucosa from the lumen as a surveillance peptide promoting mucosa l repair. A stem-cell-derived ''ulcer-associated cell lineage'' develo ps adjacent to ulcers and produces EGF, which may play a role in ulcer healing. TGF-alpha is expressed by villus enterocytes and may have an important role in mucosal healing. The Trefoil peptides (pS2, spasmol ytic polypeptide, intestinal trefoil factor) are protease resistant mo lecules secreted by mucin cells throughout the gut, with a role in muc osal healing. The TGF-beta family inhibit cell proliferation, and prom ote cell differentiation. TGF-beta has a gradient of expression along the crypt villus axis, with maximum production at the villus tip. It i s suspected that it may prevent cell proliferation and support differe ntiation of villus enterocytes. Hepatocyte growth factor is a multifun ctional growth factor expressed in many tissues, including the gastroi ntestinal tract. It has a role in organogenesis. Intestinal adaptation is highly dependent on enteral nutrition, and it is likely that growt h factors are involved in adaptation. Little is known, however, about interactions between nutrients and growth factors. Milk contains a ran ge of potentially important growth factors. Their biological significa nce is uncertain, and this is an area of active research. (C) Elsevier Science Inc. 1998.