Helicobacter pylori (H. pylori) causes pathological changes of gastric epithelial cells induced
by pathogenic factors such as CagA and VacA, namely hummingbird cells (HBC) formation and
vacuolization, respectively, in cultured cell lines. Cytopathic effects of other pathogenic factors
produced by H. pylori have not been reported. In this study, we examined whether H. pylori
induces unique morphological changes other than HBC formation and vacuolization, and we
established a new marker of the bacterial infection in vitro. The cytotoxicity of H. pylori was
examined in the AGS cell line, and a new morphological change, namely multinuclear giant cells
(MNGC) formation, was observed in this cell line. The enhancement of MNGC formation was
observed following H. pylori infection but was not associated with CagA, which causes HBC
formation. We characterized the factor causing MNGC formation enhancement as heat-stable and
water-soluble, and finally considered the factor to be H. pylori lipopolysaccharide (LPS). We
considered that H. pylori LPS enhances MNGC formation in vitro. The cytopathic effect may
provide an important marker that may clarify the mechanism of H. pylori pathogenesis in human
gastric epithelial cells
