In vitro cytotoxic effects of vacuolating cytotoxin produced by clinical isolates of Helicobacter pylori.

The vacuolating cytotoxin produced by Helicobacter pylori is considered to be one virulence factor causing peptic ulceration. In this study, we examined the activity of vacuolating cytotoxin in induction of intracellular vacuolation of rabbit gastric epithelial cells (RGECs). We used culture supernatants of H. pylori as a source of vacuolating cytotoxin and quantitated cytotoxic activity by the MTT method. Intracellular vacuolation of RGECs was observed in the presence of 36 of 57 (63%) clinically isolated H. pylori strains. However, there were no differences in the incidence of H. pylori strains with positive vacuolating cytotoxin (Tox+) among patients with gastritis, gastric ulcers or duodenal ulcers. The MTT assay showed that the cytotoxic activity of H. pylori supernatants obtained from patients with gastric ulcers was significantly higher than in patients with gastritis (p < 0.01), but was not different to duodenal ulcer patient supernatants. Similar results were also observed in Tox+ isolates, however, there were no significant differences between patients with regard to the incidence of vacuolating cytotoxin-negative isolates. Although our data may not indicate a clear correlation between prevalence of vacuolating cytotoxin and clinical manifestations, they suggest that H. pylori harboring vacuolating cytotoxin may particularly induce damage to the gastric epithelium in patients with gastric ulcers.