Lactobacillus Zeae (LB1), originally isolated from chicken, has been shown to have a high protective effect against infection of enterotoxigenic Escherichia coli (ETEC) in an in vivo C. elegan model. However, the underlying molecular mechanism is still unclear. In the present study, IPEC-J2 was used as an in vitro epithelial cell model and the protective effects of LB1 against ETEC F4 infection were investigated. The results showed that the pretreatment of IPEC-J2 cells with LB1 significantly alleviated the cytotoxicity and inhibited gene expression of inflammatory cytokines (interleukin IL-8 and IL-6) induced by the ETEC F4 challenge. The LB1 pretreatment maintained a significantly higher value of trans-epithelial electrical resistance (TEER) when challenged with ETEC F4 and a concomitant lower fluorescein isothiocyanate-dextran (FITCdextran, MW 4,000) fluxes from apical side to the basolateral side compared with that challenged with ETEC F4 alone, which indicated that LB1 pretreatment protected barrier integrity. Results from ZO-1 and beta-actin staining showed that LB1 pretreatment could prevent tight junction and cytoskeleton damage caused by the ETEC F4 challenge, indicating that LB could keep tight junction structural integrity. However, LB1 inclusion did not show significant protection on tight junction protein ZO-1 and occludin expression at both gene and protein levels from the ETEC F4 challenge. These results suggested that probiotics LB1 could effectively protect epithelial cells against the ETEC F4 infection by inhibition of inflammation and maintaining barrier integrity. Our work allows gaining insight into the mechanisms that probiotics could exert to improve the host gut health.
Keywords: probiotic, ETEC F4, intestinal epithelial cell, tight junction, cytokines.
Published in the proceedings of the Animal Nutrition Conference of Canada 2020. For information on the event, past and future editions, check out https://animalnutritionconference.ca/.