Additional file 2: Figure S2. of Lactobacillus acidophilus attenuates Salmonella-induced intestinal inflammation via TGF-β signaling

Effect of L. acidophilus on SMAD3/4 transcriptional activity with active or inactive S. typhimurium. Human intestinal Caco-2 cells were transfected with luciferase reporter plasmid containing the promoter of the SMAD-binding site or CMV promoter overnight. The cells were then pretreated with L. acidophilus (MOI: 20) 1 h prior to infection with S. typhimurium (MOI: 10) or UV-inactivated S. typhimurium (MOI: 10) in antibiotic-free DMEM for 1 h at 37 °C. Then, the cells were washed twice with PBS and added to medium containing D-luciferin to monitor SMAD activity. The cells were washed twice with PBS, added to DMEM medium containing D-luciferin and antibiotics for signal measurement with a Luminometer. Data were analyzed with Prism 5, and the results are shown as the means ± SEM from three independent experiments. (TIFF 100 kb