Fig. 1

Effects of L. acidophilus on S. typhimurium-induced NF-κB activation. a Human intestinal Caco-2 cells were transfected with a luciferase reporter vector for NF-κB or CMV (normalization control) overnight and then infected with various concentrations of S. typhimurium as indicated, ranging from 10⁴ to 10¹⁰ CFU/ml in antibiotic-free DMEM for 1 h at 37 °C. The cells were recovered with DMEM media containing gentamicin (50 μg/ml) and NF-κB transcriptional activity was measured at 6 or 24 h post-infection. b For treatment with L. acidophilus, transfected cells were treated with 1 % inulin or L. acidophilus (L. acidophilus:S. typhimurium = 2:1) or synbiotics (L. acidophilus and 1 % inulin) 1 h prior to infection of S. typhimurium as mentioned above. The cells were added with DMEM medium containing D-luciferin and antibiotic at 6 h post-infection to measure NF-κB activity. The data were analyzed with Prism 5, and the results are shown as the means ± SEM from three independent experiments