The Journal of Medical Microbiology, Vol 37, Issue 2 118-122, Copyright © 1992 by Society for General Microbiology
Cytopathic effects of Helicobacter pylori on cultured mammalian cells
H. Konishi, M. Ishibashi, M. G. Morshed and T. Nakazawa
Department of Microbiology, Yamaguchi University School of Medicine, Japan.
Cytopathic effects of broth-culture filtrates from eight clinical isolates
and one reference strain of Helicobacter pylori on three cultured mammalian
cell lines were investigated. All the strains, including NCTC 11637,
produced cytotoxic factors that caused intracellular vacuolation on these
cell lines. AGS and SflEp cells were more sensitive than HEp-2 cells. To
examine the role of urease in the cytotoxic effect, a urease-negative
mutant was produced. Filtrates from both wild-type and mutant strains
produced similar vacuolation on SflEp cells in the absence of urea,
suggesting that H. pylori produces a cytotoxic substance other than urease.
In contrast, ammonia alone, or jack bean urease with urea, also induced
rounding and detachment of SflEp cells, whereas ammonium salts induced the
production of small vacuoles. The combination of the broth filtrate of the
wild-type strain and urea induced vacuolation followed by rounding and
detachment of SflEp cells. Evidence is presented that the latter changes
are due to ammonia produced during incubation. Nevertheless, the amounts
produced were less than that needed to induce cytopathic effects by itself.
These results suggest that the cytotoxic substance induces intracellular
vacuolation, and that the vacuolated cells are more susceptible to killing
by ammonia. Thus both the cytotoxic substance and urease may contribute to
the lethal cytotoxicity of H. pylori in vitro.
