Objective To investigate the ability of proteinase-activated receptor-2 (PAR-2) agonists (tc-LIGRLO- NH 2 and SLIGKV-NH
2) and trypsin to induce
histamine release from human colon mast cells. Methods Mast cells were dispersed from human colon tissue with collagenase and hyaluronidase, and were challenged with stimulus for 15 min at 37 ℃. A glass fibre-based fluorometric assay was used to measure histamine in the supernatants of dispersed mast cells. Results Both PAR-2 agonists tc-LIGRLO-NH 2 and SLIGKV-NH 2 were able to induce dose-dependent release of histamine from colon mast cells, and more than 2.5 and 2.0 fold increases in histamine release were provoked by 100 μmol/mL tc-LIGRLO- NH 2 and SLIGKV-NH 2, respectively. The reverse peptides tc-OLRGIL-NH 2 and VKGILS-NH 2 had no effect on the release of histamine when added at concentrations up to 300 μmol/mL. Trypsin at the concentrations of 1.0～100 μg/mL was capable of provoking a dose-dependent release of histamine. Approximately 70% trypsin induced release of histamine was reduced by soybean trypsin inhibitor (SBTI) when trypsin and SBTI were added at the same time to cells. The release of histamine in response to tc-LIGRLO-NH 2 was completed within 3 min. Histamine induced by tc-LIGRLO-NH 2, SLIGKV-NH 2, and trypsin was abolished by pretreatment of colon mast cells with pertussis toxin or metabolic inhibitors. Conclusion PAR-2 agonists and trypsin are potent secretagogues of human colon
mast cell, which are likely to contribute to the development of inflammatory disorders in human gut.