In a human gastric biopsy specimen, 30% of adhering Helicobacter pylori strain AF4 (cagA and VacA positive) was associated with adhesion pedestals. In an AGS cell assay, only a few percent of this type I strain was found to be associated with adhesion pedestals. Nevertheless, a larger proportion of the type I strain was found to invade AGS cells (P < 0.03) and to attach with depressions in the AGS cell membrane (P < 0.03) than a type II strain (cagA and VacA negative). Incubation of AGS cells and H. pylori without adding fetal calf serum (FCS) to the culture medium increased actin accumulations (FITC-phalloidin stained) beneath adhering H. pylori, and decreased H. pylori invasion of AGS cells significantly (P < 0.01). However, no increase in the number of adhesion pedestals was observed by electron microscopy. Proteinase K treatment of FCS eliminated the H. pylori invasion promoting effect (P < 0.01). Our results suggest differences in the ability of H. pylori to induce adhesion pedestals in human gastric epithelial cells and in AGS cells, but a correlation between adhesion pedestal formation in vivo and H. pylori invasion in vitro can be speculated. In addition, H. pylori invasion into AGS cells was found to be mediated by proteins in FCS. (C) 2000 Federation of European Microbiological Societies.
Bibliografisk noteFunding Information:
The authors thank Vibeke Binder, DMSci, and Ole Østergaard Thomsen, DMSci for critical revision of the manuscript and Ditte Tornehave, Ph.D for formating the immunofluorescence pictures. This research was supported by grants from the Jacob Madsen and Olga Madsens Foundation, Novo Nordisk Foundation, the Danish National Research Foundation and the Danish Medical Association’s Research Foundation.