OBJECTIVETo explore the role of mast cells in the pathogenesis of ulcerative colitis in rats with dampness and heat syndrome, and observe the regulatory effect of Huangqin decoction on the mast cells.

METHODSRat models of dampness and heat syndrome were established by feeding with high-fat and-sugar chow, maintenance of a hot and humid environment, and intrarectal administration of 2,4,6-trinitro-benzene-sulfonic acid. The model rats were then randomized into the model group (n=12), Huangqin decoction group (n=13) and mesalazine group (n=12). After a one-week treatment, the inflammatory cell infiltration was observed using HE staining, and the number of mast cells was determined using toluidine blue staining. Immunohistochemistry was used to detect the expression of tryptase, and serum IL-4 and IL-6 levels were measured using ELISA.

RESULTSCompared with the normal control rats (n=15), the rats in the model group showed obvious inflammatory cell infiltration at the lesion site with significantly increased mast cells and serum IL-6 level (P<0.05). Huangqin and mesalazine significantly lessened inflammatory cell infiltration and decreased the mast cell number and serum IL-6 level after a one-week treatment.

CONCLUSIONThe intestinal mucosal immune cells such as the mast cells play an important role in the pathogenesis of ulcerative colitis associated with dampness and heat syndrome. Huangqin decoction can ameliorate the inflammation, decrease mast cell number and tryptase release, and inhibit IL-6 secretion for treatment of ulcerative colitis in rats with dampness and heat syndrome.