AIM: To determine whether Lactobacillus plantarum can modify the deleterious effects of tumor necrosis factor-α(TNF-α) on intestinal epithelial cells.METHODS: Caco-2 cells were incubated with TNF-α alone or in the presence of L. plantarum. Transepithelial electrical resistance was used to measure epithelial barrier function. Interleukin 8 (IL-8) secretion by intestinal epithelial cells was measured using an ELISA.Cellular lysate proteins were immunoblotted using the anti-extracellular regulated kinase (ERK), anti-phospho-ERK and anti-IκB-α.RESULTS: A TNF-α-induced decrease in transepithelial electrical resistance was inhibited by L. plantarum. TNF-α-induced IL-8 secretion was reduced by L. plantarum.L. plantarum inhibited the activation of ERK and the degradation of IκB-α in TNF-α-treated Caco-2 cells.CONCLUSION: Induction of epithelial barrier dysfunction and IL-8 secretion by TNF-α is inhibited by L. plantarum.Probiotics may preserve epithelial barrier function and inhibit the inflammatory response by altering the signal transduction pathway.