This study investigated the impact of L. animalis 506 on gut barrier integrity and regulation of inflammation in vitro using intestinal epithelial cell lines. Caco-2 or HT29 cell monolayers were challenged with enterotoxigenic E. coli (ETEC) or a ruminant isolate of Salmonella Heidelberg in the presence or absence of one of six probiotic Lactobacillus spp. strains. Among these, L. animalis 506 excelled at exerting protective effects by significantly mitigating the decreased transepithelial electrical resistance (TEER) as assessed using area under the curve (AUC) (p < 0.0001) and increased apical-to-basolateral fluorescein isothiocyanate (FITC) dextran translocation (p < 0.0001) across Caco-2 cell monolayers caused by S. Heidelberg or ETEC, respectively. Similarly, L. animalis 506 and other probiotic strains significantly attenuated the S. Heidelberg- and ETEC-induced increase in IL-8 from HT29 cells (p < 0.0001). Moreover, L. animalis 506 significantly counteracted the TEER decrease (p < 0.0001) and FITC dextran translocation (p < 0.0001) upon challenge with Clostridium perfringens. Finally, L. animalis 506 significantly attenuated DON-induced TEER decrease (p < 0.01) and FITC dextran translocation (p < 0.05) and mitigated occludin and zona occludens (ZO)-1 redistribution in Caco-2 cells caused by the mycotoxin. Collectively, these results demonstrate the ability of L. animalis 506 to confer protective effects on the intestinal epithelium in vitro upon challenge with enteric pathogens and DON known to be of particular concern in farm animals.
Keywords: enteric pathogens; gut barrier integrity; inflammation; probiotics.