Live and Ultraviolet-inactivated Lactobacillus Rhamnosus GG Decrease Flagellin-induced Interleukin-8 Production in Caco-2 Cells

Probiotics are widely used in the treatment and prevention of gastrointestinal problems. However, in some immune-compromised Populations, the administration of live microorganisms may riot be appropriate, A potential alternative to live microorganisms is to inactivate them as long as the beneficial function is retained. We hypothesized that UV-inactivated Lactobacillus rhamnosus GG (LGG) could downregulate interleukin-8 (IL-8) production in intestinal epithelial cells stimulated by the pathogenic ligand, flagellin, using similar mechanisms as live LGG. Caco-2 cells were pretreated with live or UV-inactivated LGG at 10(11) colony-forming units/L and stimulated by flagellin at a dose of 500 mu g/L. IL-8 production was measured by ELISA, inhibitor Of kappa B (I kappa B) and ubiquitinated-I kappa B (Ub-I kappa B) expression by immunoblotting and nuclear factor (NF) kappa B localization by immunofluorescence staining. Flagellin induced a 17-fold increase in IL-8 production compared with control (P < 0.05), whereas pretreatment with either live LGG or UV-inactivated LGG resulted in 66 and 59% decreases, respectively, compared with the flagellin group (P < 0.05). Flagellin-induced NF kappa B nuclear translocation was prevented by both live and UV-inactivated LGG. Flagellin decreased I kappa B, which was reversed by either live or UV-inactivated LGG (P < 0.05). UV-inactivated LGG decreased Ub-I kappa B expression (P < 0.05), although live LGG had no effect. This study supports the concept that UV-inactivated and live LGG are equally effective in decreasing IL-8 production in the intestinal epithelium. Although the mechanism involves different pathways, both alter cytoplasmic I kappa B, thereby inhibiting NF kappa B nuclear translocation. J. Nutr. 138: 2264-2268, 2008.