Arcobacter butzleri isolates exhibit pathogenic potential in intestinal epithelial cell models.

AIMS: The pathogenic potential of Arcobacter butzleri isolates on human (HT-29/B6) and porcine epithelial (IPEC-J2) cells was investigated by in vitro assays. METHODS AND RESULTS: Five of six A. butzleri isolates were able to adhere and invade HT-29/B6 cells while only four isolates adhered and two invaded IPEC-J2 cells. Two non- or poorly invasive A. butzleri isolates were highly cytotoxic to differentiated HT-29/B6 cells but none to IPEC-J2 cells as determined by WST-assays. Epithelial integrity of cell monolayers, monitored by measurement of the transepithelial electrical resistance (TER), was decreased by all A. butzleri isolates in HT-29/B6 and IPEC-J2 cells to 30-15% and 90-50% respectively. CONCLUSION: The A. butzleri strain-specific pathomechanisms observed with the human colon cell line HT-29/B6, like adhesion, invasion and cytotoxicity might all contribute to epithelial barrier dysfunction, which could explain a leak-flux type of diarrhoea in humans. In contrast, porcine cells seem to be less susceptible to A. butzleri. SIGNIFICANCE AND IMPACT OF THE STUDY: Arcobacter butzleri has enteric pathogenic potential, characterized by defined interactions with human epithelial cells and strain-specific pathomechanisms.

Presence of virulence genes, adhesion and invasion of Arcobacter butzleri.

AIMS: The pathogenic potential of Arcobacter butzleri isolates was investigated by detecting the presence of putative virulence genes and analysing the adhesive and invasive capabilities in cell cultures of human cell lines. METHODS AND RESULTS: The presence of ten putative virulence genes in 52 A. butzleri isolates was determined by PCR. The genes ciaB, mviN, pldA, tlyA, cj1349 and cadF were detected in all, whilst irgA (15%), iroE (60%), hecB (44%) and hecA (13%) were detected only in few A. butzleri isolates. On HT-29 cells, four of six isolates adhered to and three of them were able to invade, whilst all six isolates adhered to and invaded Caco-2 cells with higher degrees. The genes ciaB, cadF and cj1349 of all six isolates were sequenced, but no considerable changes of the amino acids in putative functional domains were observed. CONCLUSION: Selected A. butzleri isolates adhere to and invade HT-29 and Caco-2 cells, which emphasize their human pathogenic potential. The efficiency of invasion depends on the eukaryotic cell line and individual bacterial strain used. We could not show any functional correlation between the amino acid sequence of CadF, CiaB or Cj1349 and the adhesive and invasive phenotype. SIGNIFICANCE AND IMPACT OF THE STUDY: We have shown that some A. butzleri strains invade various cell lines. This underlines their pathogenic potential and hints at their relevance in human disease.