Arcobacter butzleri Induces Barrier Dysfunction in Intestinal HT-29/B6 Cells

Background. Arcobacter butzleri causes watery diarrhea and bacteremia. Although, recently, more cases of diarrhea have been caused by Arcobacter species, very little is known about its pathogenesis, the identification of which is the aim of this study. Methods. Human HT-29/B6 colonic epithelial monolayers were apically inoculated with A. butzleri. Transepithelial resistance and macromolecule fluxes were measured in Ussing chambers. Tight junction protein expression was analyzed by Western blotting, and subcellular distribution was analyzed by confocal laser-scanning microscopy. Results. Infection of HT-29/B6 caused a decrease in transepithelial resistance to 30% and an increase in paracellular permeability to fluorescein (10.8 +/- 3.5 10(-6) cm/s vs. 1.8 +/- 0.6 10(-6) cm/s in control; P < .05) and dextran-4 kDa (0.036 +/- 0.005 10(-6) cm/s vs. 0.015 +/- 0.002 10(-6) cm/s in control; P < .01). This effect was time and dose dependent and was also caused by bacterial lysates showing heat and proteinase-K sensitivity. As structural correlate, expression of the tight junctional proteins claudin-1, -5, and -8 was reduced, and claudin-1 and -8 were redistributed off the tight junctional strands forming intracellular aggregates. Furthermore, A. butzleri induced epithelial apoptosis (3-fold). Conclusions. A. butzleri induces epithelial barrier dysfunction by changes in tight junction proteins and induction of epithelial apoptosis, which are mechanisms that are consistent with a leak flux type of diarrhea in A. butzleri infection.