Helicobacter pylori potentiates histamine release from rat serosal mast cells induced by bile acids

In the present study we have experimentally addressed the effects of Helicobacter pylori on the bile acid capability of histamine release. Bile acids alone were confirmed to be able to induce in vitro histamine release from rat serosal and mucosal mast cells. On the contrary, no significant histamine release was obtained when incubating any Helicobacter pylori preparations alone with mast cells. However, histamine release induced by bile acids was significantly enhanced, without any significant increase in lactate dehydrogenase activity, when whole washed or formalin-killed bacterial cells or crude cell walls were incubated with mast cells in the presence of cholic (0.3 mM), deoxycholic (0.3 mM), or lithocholic (0.3 mM) acids, chenodeoxycholylglycine (0.3 mM), and deoxycholyltaurine (3 mM). The electron microscopic features of mast cells incubated with Helicobacter pylori were consistent with an exocytotic secretion. The release of histamine induced by 0.3 mM deoxycholic acid in the presence of Helicobacter pylori was inhibited by the preincubation of the cells with dimaprit (an H2 agonist) and potentiated by the H2 antagonist, ranitidine. The current results suggest a link between human Helicobacter pylori infection and histamine release and a possible involvement of gastric mucosal mast cells in the pathogenesis of Helicobacter pylori-associated gastritis.