Background & aims: Helicobacter pullorum is an entero-hepatic Helicobacter species of avian origin detected in patients with acute diarrhoea and inflammatory bowel disease. Our aim was to determine whether H. pullorum exerts a direct effect on human intestinal epithelial cells in vitro and to characterise the bacterial mechanisms and the signalling pathways involved.
Material and methods: The proinflammatory properties of H. pullorum from human and avian origins were measured on human gastric (AGS) and intestinal (CaCo-2 and HT-29) epithelial cell lines after co-culture with different H. pullorum strains, and the extent of nuclear factor kappa B (NF-κB) involvement was determined.
Results: All of the H. pullorum strains tested stimulated interleukin-8 (IL-8) secretion by the three cell lines. Similar results were obtained with heat-killed H. pullorum. Incubation of cells with filtered-H. pullorum culture supernatants did not stimulate IL-8 secretion. The same observation was made when bacterial adherence was inhibited by Transwell inserts. H. pullorum induced NF-κB activation and rapid nuclear translocation as demonstrated by immunofluorescent staining and cellular fractionation. NF-κB involvement was confirmed by using SN50 specific inhibitor and siRNA which abolished H. pullorum-induced IL-8 production.
Conclusions: H. pullorum strains stimulate IL-8 secretion by human gastric and intestinal epithelial cell lines. This effect requires bacterial adherence and probably lipopolysaccharides and is mediated by NF-κB signalling. The present study strengthens the argument that H. pullorum is a potent human pathogen and highlights its putative role in acute and chronic digestive diseases such as inflammatory bowel disease.