The Effects of Intestinal LPS Exposure on Inflammatory Responses in a Porcine Enterohepatic Co-culture System

A porcine enterohepatic co-culture system, with primary hepatocytes as bottom layer and IPEC-J2 epithelial cells as upper layer, was developed to study the effects of lipopolysaccharides (LPS) on the gene expression profile of pro-inflammatory cytokines (interleukin-8 (IL-8) and tumor necrosis factor-α) and CYP enzymes (CYP1A1, CYP1A2, CYP3A29). The barrier integrity of IPEC-J2 cells was investigated by transepithelial electrical resistance measurements and by fluorescein isothiocyanate–dextran-based test. Basolateral IL-8 production was significantly elevated in LPS-treated IPEC-J2 and primary hepatocyte mono-cultures as well as in the co-culture system, in a dose-independent manner. The LPS-induced changes in the expression of the CYP1A2 and CYP3A29 genes in hepatocyte mono-cultures differed from those in co-culture after LPS treatment on the apical side of the IPEC-J2 cell layer. CYP1A2 was downregulated by the LPS treatment in mono-cultures but upregulated at 10 μg/ml LPS in co-culture; gene expression of CYP3A29 showed no significant LPS-induced change in the hepatocyte mono-culture but was significantly downregulated in co-culture. The newly established co-culture system capable of mimicking enterohepatic interplay in LPS-induced inflammatory responses in vitro can be used in the future for reliable screening of potential anti-inflammatory compounds.