Oesophagus and stomach

Study of Helicobacter pullorum proinflammatory properties on human epithelial cells in vitro

C Varon^1,2, A Duriez^1,2,3, P Lehours^1,2,4, A Ménard^1,2, S Layé^2,5, F Zerbib^1,2,3, F Mégraud^1,2,4, D Laharie^1,2,6

¹ INSERM, U853, Bordeaux, France
² Université Victor Segalen Bordeaux 2, Bordeaux, France
³ Gastroenterology Department, CHU Bordeaux, Saint André Hospital, Bordeaux, France
⁴ National Reference Centre for Helicobacters and Campylobacters, CHU Bordeaux, Pellegrin Hospital, Bordeaux, France
⁵ Psynugen, INRA, UMR1286, CNRS, UMR5226, Université Victor Segalen Bordeaux 2, Bordeaux, France
⁶ Gastroenterology Department, CHU Bordeaux, Haut-Lévêque Hospital, Bordeaux, France

Professor F Mégraud, INSERM U853, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, Bat. 2B RDC-Zone Nord, F-33076 Bordeaux cedex, France; francis.megraud{at}chu-bordeaux.fr

Background and aims: Helicobacter pullorum is an enterohepatic Helicobacter species of avian origin detected in patients with acute diarrhoea and inflammatory bowel disease. The aim of the present study 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.

Materials 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-B (NF-B) involvement was determined.

Results: All of the H pullorum strains tested stimulated interleukin 8 (IL8) 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 IL8 secretion. The same observation was made when bacterial adherence was inhibited by Transwell inserts. H pullorum induced NF-B activation and rapid nuclear translocation as demonstrated by immunofluorescent staining and cellular fractionation. NF-B involvement was confirmed by using the specific inhibitor SN50 and small interfering RNA (siRNA) which abolished H pullorum-induced IL8 production.

Conclusions: H pullorum strains stimulate IL8 secretion by human gastric and intestinal epithelial cell lines. This effect requires bacterial adherence and probably lipopolysaccharides, and is mediated by NF-B 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.

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