Wild-type rats and mast cell-deficient rats were sensitised and challenged with oxazolone, then treated with tranilast after challenge. Controls were treated with saline.
Mast cell-deficient rats presented a weak response to oxazolone, while wild-type rats showed severe ulcerative colitis after stimulation with oxazolone. The mast cell-deficient rats model had a significantly lower disease activity index score than wild-type rats model (1.8 ± 1.64 vs 8.3 ± 0.58 respectively; P < 0.01). Tranilast could reduce the secretion of cytokines, immunoglobulins and myeloperoxidase activity in tranilast treatment groups compared with the model group. The number of mast cells in the wild-type model was higher than in the other groups. There was no significant change in mast cell-deficient rats.
Mast cells play an important role in oxazolone-induced colitis. The mast cell membrane stabiliser tranilast can ameliorate oxazolone-induced colitis via a mast cell-dependent pathway.