AIMS: The present study examined the effect of the antimicrobial peptide cathelicidin-BF (CBF) on LPS-induced mucosal injury and intestinal epithelial barrier dysfunction in a rat model and in the porcine intestinal epithelial cell line.
MAIN METHODS: Changes in barrier integrity were assessed in intestinal epithelium and IPEC-J2 monolayers by measuring nutrient absorption and transepithelial electrical resistance (TER), and the permeability of intestinal epithelium was examined by measuring plasma d-lactate and diamine oxidase levels. The expression levels of tight junction (TJ) proteins were quantified by real-time PCR, and immunofluorescence was used to analyse the location and distribution of TJs in cells.
KEY FINDINGS: In vivo, CBF improved epithelial barrier function through attenuating the alterations of the mucosal structure, nutrient absorption and TER in the jejunum, and preventing the down-regulation of TJ proteins in LPS-induced rat intestinal epithelium. In vitro, CBF prevented the disruption and the re-distribution of ZO-1 and occludin, and suppressed the increase in inflammatory cytokine levels in LPS-induced IPEC-J2. The CBF-induced upregulation of zonula occludens-1 and occludin was prevented by U0126 or SB203580, suggesting the involvement of the MEK and p38 MAPK pathways in the CBF-induced changes in tight junctions.
SIGNIFICANCE: Our results showed that CBF prevents LPS-induced intestinal epithelial barrier dysfunction, suggesting its potential as a therapeutic agent for the prevention of LPS-mediated intestinal diseases. We found that exogenous CBF had protective effects on LPS-induced intestinal epithelial barrier disruption in rats and on epithelial damage in IPEC-J2 cells.