Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils

FK506 and dexamethasone were used to investigate whether or not immunosuppr ession affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infect ion, FK506 and dexamethasone or vehicle alone were subcutaneously administe red once daily for the following 2 weeks. FK506 or vehicle alone was admini stered subcutaneously once daily for 5 weeks (1 week before and 4 weeks aft er infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosi ons and inflammatory responses (neutrophil infiltration and lymphoid follic le formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such muco sal changes. In these animals, H. pylori viability in the stomach was signi ficantly elevated. FK506 administered for 5 weeks also significantly inhibi ted the hemorrhagic erosions, edema and neutrophil infiltration in the stom ach. H. pylori viability was slightly elevated as compared with the control . It was concluded that the host immune responses might play dual roles bot h by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage. (C) 2001 Published by Elsevier Sci ence Ltd.