Screening Lactobacillus plantarum Strains with Potential to Protect Human Intestinal Epithelium HT-29 Cells against Injury Caused by Escherichia coli or H₂O₂

Probiotic Lactobacillus strains can exert anti-inflammatory or antioxidant activities after colonization in the gut, which is beneficial for the host’s intestinal health. In this study, eight L. plantarum strains isolated from traditional fermented dairy foods in Xinjiang, China, were evaluated for their protective effects on HT-29 human intestinal epithelial cells against injury caused by Escherichia coli or hydrogen peroxide (H₂O₂). Among these strains, L. plantarum 35 showed the highest adhesion capacity to HT-29 cell monolayers, and it reduced E. coli adhesion to HT-29 cells by displacement, competition, and exclusion, with inhibition rates of 42.60%, 59.17%, and 60.19%, respectively. L. plantarum 35 and its crude exopolysaccharide (EPS) inhibited E. coli from stimulating HT-29 cells to produce interleukin-8 (IL-8), protected HT-29 cells against injury induced by H₂O₂, increased the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and decreased malondialdehyde (MDA) content in HT-29 cells. Therefore, L. plantarum 35 and its crude EPS have the potential to inhibit inflammatory bowel disease induced by E. coli O157.