The pathogenic potential of Helicobacter cinaedi isolated from non-human sources: adherence, invasion and translocation ability in polarized intestinal epithelial Caco-2 cells in vitro

Helicobacter cinaedi infection has been recognized as an increasingly important emerging disease in humans. Infection with H. cinaedi causes bacteremia, cellulitis and enteritis. H. cinaedi has been isolated from non-human sources, including dogs, cats and rodents; however, it remains unclear whether animal strains are pathogenic in humans and as zoonotic pathogens. In this study, H. cinaedi isolates were recovered from a dog and a hamster, and the ability of these isolates to adhere to, invade and translocate across polarized human intestinal epithelial Caco-2 cells was examined in vitro. To better understand the pathogenic potential of animal H. cinaedi isolates, these results were compared with those for a human strain that was isolated from a patient with bacteremia. The animal and human strains adhered to and invaded Caco-2 cells, but to a lesser degree than the C. jejuni 81–176 strain, which was used as a control. The integrity of tight junctions was monitored by measuring transepithelial electrical resistance (TER) with a membrane insert system. The TER values for all H. cinaedi strains did not change during the experimental periods compared with those of the controls; however, translocation of H. cinaedi from the apical side to the basolateral side was confirmed by cultivation and H. cinaedi-specific PCR, suggesting that the H. cinaedi strains translocated by transcellular route. This study demonstrated that H. cinaedi strains of animal origin might have a pathogenic potential in human epithelial cells as observed in a translocation assay in vitro with a human isolate.