Role of mast cells in gastrointestinal mucosal defense.

The purpose of this review, based on studies from our laboratory as well as from others, is to summarize salient features of mast cell immunobiology and to describe their associations with gastrointestinal mucosal defense. Gastrointestinal mast cells are involved in many pathologic effects, such as food hypersensitivity. On the other hand, they also play a protective role in defense against parasitic and microbial infections. Thus, they have both positive and negative effects, but presently the mechanisms that control the balance of these various effects are poorly known. It has been suggested that stabilization of mast cells may be a key mechanism to protect the gastrointestinal tract from injury. Few molecules are known to possess both mast cell stabilizing and gastrointestinal cytoprotective activity. These include zinc compounds, sodium cromoglycate, FPL 52694, ketotifen, aloe vera, certain flavonoids such as quercetin, some sulfated proteoglycans such as chondroitin sulfate and dehydroleucodine. Dehydroleucodine, a sesquiterpene lactone isolated from Artemisia douglasiana Besser, exhibits anti-inflammatory and gastrointestinal cytoprotective action. The lactone stimulates mucus production, and inhibits histamine and serotonin release from intestinal mast cells. The lactone could act as a selective mast cell stabilizer by releasing cytoprotective factors and inhibiting pro-inflammatory mast cell mediators.