Lactobacillus plantarum inhibits epithelial barrier dysfunction and interleukin-8 secretion induced by tumor necrosis factor-alpha

Abstract

Aim: To determine whether Lactobacillus plantarum can modify the deleterious effects of tumor necrosis factor-alpha (TNF-alpha) on intestinal epithelial cells.

Methods: Caco-2 cells were incubated with TNF-alpha 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-IkappaB-alpha.

Results: A TNF-alpha-induced decrease in transepithelial electrical resistance was inhibited by L. plantarum. TNF-alpha-induced IL-8 secretion was reduced by L. plantarum. L. plantarum inhibited the activation of ERK and the degradation of IkappaB-alpha in TNF-alpha-treated Caco-2 cells.

Conclusion: Induction of epithelial barrier dysfunction and IL-8 secretion by TNF-alpha is inhibited by L. plantarum. Probiotics may preserve epithelial barrier function and inhibit the inflammatory response by altering the signal transduction pathway.

Figure 1

Effect of L. plantarum on transepithelial resistance. TNF-α decreased Caco-2 monolayer resistance. L. plantarum reversed TNF-α-induced decreases in transepithelial resistance. ^aP < 0.05, compared with TNF-α. TER: transepithelial electrical resistance; LP: L. plantarum; TNF, TNF-α.

Figure 2

Effect of L. plantarum on TNF-α-induced IL-8 secretion by Caco-2 cells. TNF-α-induced IL-8 secretion was significantly reduced by L. plantarum. ^aP < 0.05, compared with TNF-α. LP: L. plantarum; TNF, TNF-α.

Figure 3

Effect of L. plantarum on the ERK pathway. Caco-2 cells were incubated with L. plantarum, TNF-α or L. plantarum plus TNF-α. Cell lysates were immunoblotted with antibodies against phosphorylated ERK and total ERK. L. plantarum inhibited TNF-α-induced activation of ERK-1 and -2. LP: L. plantarum; TNF, TNF-α.

Figure 4

Effect of L. plantarum on IκB-α degradation. Caco-2 cells were incubated with L. plantarum, TNF-α or L. plantarum plus TNF-α. Cell lysates were immunoblotted with antibodies against IκB-α. TNF-α caused degradation of IκB-α. L. plantarum inhibited TNF-α-induced IκB-α degradation. LP: L. plantarum; TNF, TNF-α.