Lactic Acid Bacteria Strains Used as Starters for Kimchi Fermentation Protect the Disruption of Tight Junctions in the Caco-2 Cell Monolayer Model.

In this study, we investigated the effect of lactic acid bacteria (LAB) strains used as starters for kimchi fermentation, namely WiKim0124, WiKim39, WiKim0121 WiKim33, and WiKim32, on the intestinal epithelial tight junctions (TJs). These LAB strains were not cytotoxic to Caco-2 cells at 500 μg/ml concentration. In addition, hydrogen peroxide (HO) decreased Caco-2 viability, but the LAB strains protected the cells against HO-induced cytotoxicity. We also found that lipopolysaccharide (LPS) promoted Caco-2 proliferation; however, no specific changes were observed upon treatment with LAB strains and LPS. Our evaluation of the permeability in the Caco-2 monolayer model confirmed its increase by both LPS and HO. The LAB strains inhibited the increase in permeability by protecting TJs, which we evaluated by measuring TJ proteins such as zonula occludens-1 and occludin, and analyzing them by western blotting and immunofluorescence staining. Our findings show that LAB strains used for kimchi fermentation can suppress the increase in intestinal permeability due to LPS and HO by protecting TJs. Therefore, these results suggest the possibility of enhancing the functionality of kimchi through its fermentation using functional LAB strains.