Immunomodulatory effects of Lactobacillus plantarum and Lactobacillus acidophilus strains on a rat intestinal epithelial cell line (137.21)

Abstract Lactobacillus plantarum and Lactobacillus acidophilus have the potential to be immunomodulatory probiotics. An experiment was conducted to determine the effects of three L. plantarum and three L. acidophilus strains on the expression of five inflammatory cytokine genes (TNF-α, MIP-2, IL-1β, IL-6, and IL-18) by the IEC-6 rat intestinal epithelial cell line. The Lactobacillus strains had unique genotypic profiles based on RAPD PCR. IEC-6 cells were exposed to 107 cfu viable bacterial cells for one hour with and without lipopolysaccharide (LPS) stimulation. Expression of inflammatory cytokines was analyzed by quantitative PCR. L. plantarum 7-12 and L. acidophilus La-11 had an inflammatory effect on unstimulated cells as indicated by up-regulation of IL-18 by 7-12, and up-regulation of MIP-2 and IL-6 by La-11. L. plantarum 5-39 and L. acidophilus NCFM had an anti-inflammatory effect as indicated by down-regulation of IL-1β. L. plantarum CI15 and L. acidophilus La1 did not affect cytokine expression. LPS increased the expression of TNF-α and MIP-2 in IEC-6 cells > 60 fold. All strains except L. plantarum 7-12 down-regulated expression of TNF-α in cells stimulated with LPS. L. plantarum CI15 and 5-39, as well as L. acidophilus NCFM and La1 down-regulated MIP-2 expression in LPS-stimulated cells. These results indicate that L. plantarum and L. acidophilus have immunomodulatory properties, and the effects on cytokine expression are strain specific.