Secretion of the trefoil factor TFF3 from the isolated vascularly perfusedrat colon

The trefoil factor TFF3 is a peptide predominantly produced by mucus-secret ing cells in the small and large intestines. It has been implicated in inte stinal protection and repair. The mechanisms that govern TFF3 secretion are poorly understood. The aim of this study was, therefore. to evaluate the i nfluence of neurotransmitters. hormonal peptides and mediators of inflammat ion on the release of TFF3. For this purpose, an isolated vascularly perfus ed rat colon preparation was used. After a bolus administration of 1 ml iso tonic saline into the lumen, TFF3 secretion was induced by a 30-min intra-a rterial infusion of the compounds to be tested. TFF3 was evaluated in the l uminal effluent using a newly developed radioimmunoassav. TFF3 was barely d etected in crude luminal samples. In contrast, dithiothreitol (DTT) treatme nt of the effluent revealed TFF3 immunoreactivity, which amounted to about 0.3 pmol min(-1) cm(-1) in the basal state. Gel chromatography of DTT-treat ed luminal samples revealed a single peak that co-eluted with the monomeric form of TFF3. TFF3 was not detected in the portal effluent. Bethanechol (1 0(-6)-10(-4) M), vasoactive intestinal peptide (VIP, 10(-8)-10(-7) M) or bo mbesin (10(-8)-10(-7) M) induced a dose-dependent release of TFF3. In contr ast, substance P evoked a modest release of TFF3, whereas calcitonin gene-r elated peptide (CGRP). somatostatin, neurotensin or peptide YY (PYY) did no t modify TFF3 secretion. The degranulator compound bromolasalocid, 16,16-di methyl PGE2 (dmPGE2) or interleukin-1-beta (IL-1-beta) also evoked a marked release of TFF3. In conclusion, TFF3 in the colonic effluent is present in a complex. This association presumably involves a disulfide bond. Addition ally, the present results suggest a role for enteric nervous system and res ident immune cells in mediation of colonic TFF3 secretion. (C) 2001 Elsevie r Science B.V. All rights reserved.