Altered Cytokine Expression and Barrier Properties after In Vitro Infection of Porcine Epithelial Cells with EnterotoxigenicEscherichia coliand ProbioticEnterococcus faecium

Abstract

The aim of the present study was to elucidate the effects of the probiotic feed additiveEnterococcus faeciumNCIMB 10415 (E. faecium) on porcine jejunal epithelial cells (IPEC-J2) during an in vitro challenge with enterotoxigenicEscherichia coli(ETEC). Cells were incubated withE. faecium, ETEC, or both, and the effects on barrier function and structure and intra- and intercellular signaling were determined. Coincubation withE. faeciumabolished the ETEC-induced decrease in transepithelial resistance (Rt) (p≤0.05). No differences were seen in the expression levels of the intercellular connecting tight junction proteins examined. However, for the first time, a reorganization of the monolayer was observed in ETEC-infected cells but not in coincubated cells. ETEC induced an increase in cytotoxicity that was prevented by coincubation (p≤0.05), whereas apoptosis rates were not affected by bacterial treatment. ETEC increased the mRNA expression and release of proinflammatory cytokines TNF-α, IL-1α, and IL-6 which could be prevented by coincubation for TNF-αmRNA expression and IL-6 protein (p≤0.05). Likewise, cAMP concentrations elevated by ETEC were reduced in coincubated cells (p≤0.05). These findings indicate a protective effect of the probioticE. faeciumon inflammatory responses during infection with ETEC.