Regulation of Intestinal Epithelial Barrier Function by Different Microorganisms: the Role of Zonulin

Abstract: In this research， we investigated the effect of four intestinal microorganisms on Caco-2 monolayers and the role of zonulin in this process. This experiment was divided into five groups: control group， Escherichia coli group (Eco)， Klebsiella pneumoniae group (Kpn)， Enterococcus faecalis group (Efa) and Lactobacilli (Lac) group. After co-culturing with the four bacterias， Escherichia coli， Klebsiella pneumoniae and Enterococcus faecalis impaired Caco-2 epithelial barrier function in a time-dependent manner with a decrease in TEER. Escherichia coli and Klebsiella pneumoniae induced higher level of zonulin release (P<0.01) compared with that of control group. The expressions of tight junction proteins occludin， claudin-1 and zonula occluden-1 (ZO-1) were diminished and tight junction was destroyed and redistributed in Escherichia coli group and Klebsiella pneumoniae group. Escherichia coli， Klebsiella pneumoniae and Enterococcus faecalis caused different degrees of barrier function loss， and barrier dysfunction was probably associated with elevated zonulin level， diminished and redistributed tight junction proteins.

CSTR: 32200.14.cjcb.2014.10.0006