Effect of live Lactobacillus plantarum L2 on TNF-α-induced MCP-1 production in Caco-2 cells

Lactobacillus plantarum is a commensal bacterium that is known to ameliorate intestinal injury and inflammation caused by a wide variety of enteric pathogens. We hypothesized that L. plantarum may exert its probiotic effects by attenuation of pro-inflammatory signaling induced by TNF-α. Caco-2 cells were stimulated with TNF-α in the presence of L. plantarum L2 and Lactobacillus acidophilus LA. The protein and mRNA levels of the pro-inflammatory cytokine, MCP-1, were measured by ELISA and RT-PCR, respectively. The effect of Lactobacillus bacteria on IκBα degradation was further studied by western blotting. L. plantarum L2 and L. acidophilus LA had no effect on mRNA expression and production of MCP-1 in Caco-2 cells. A significant elevation in MCP-1 mRNA and protein expression in Caco-2 cells was detected after a 4 h exposure to TNF-α. Pre-incubation of Caco-2 cells with L. plantarum L2 for 2 h resulted in an attenuation of both MCP-1 protein production and mRNA expression in TNF-α-stimulated cells. L. plantarum L2 also prevented IκBα degradation in TNF-α-stimulated Caco-2 cells. L. plantarum L2 inhibited MCP-1 secretion and mRNA expression via a NF-κB dependent pathway by interfering with IκBα degradation in TNF-α-stimulated Caco-2 cells.