Effect of tea polyphenols on expression of nuclear factor kappa B

OBJECTIVE: To investigate the effect of tea polyphenols (TP) on expression of nuclear factor kappa B (NF-kB) in rats with alcoholic liver diseases and in cells treated with alcohol. METHODS: 22 female Wistar rats were randomly divided into three groups: a control group, an alcohol model group and a TP plus alcohol group. All treatments were injected into stomach through intragastric tube. L02 cells were divided into five groups: a control group, an alcohol treated group, a prevention group (cells were treated with TP for 3 days, and then treated with alcohol), an intervention group (cells treated with TP and alcohol), and a therapeutic group (cells were treated with alcohol for 3 days, and then treated with TP). Histopathology was observed under light microscope (LM); serum MDA, ROS in cells were quantified by optical density measurement; the expression of NF-kB and IkB was determined by RT-PCR; and the activity of NF-kB was checked with Electrophoretic Mobility Shift Assay (EMSA). RESULTS: LM indicated hepatocytes were injured obviously in the model group. Serum MDA and cells ROS in TP treated groups were significantly lower than the alcohol treated group. The level of NF-kB mRNA expression in TP treated groups(rats: 0.58+/-0.16, cells: 0.60+/-0.03, 0.59+/-0.01, 0.59+/-0.01) were significantly lower than the alcohol treated group (rats: 1.15+/-0.03, cells: 0.76+/-0.03) (P<0.01), the level of IkB mRNA expression in the prevention group, intervention group, and therapeutic group (0.51+/-0.01, 0.50+/-0.01, 0.50+/-0.12) were significantly higher than the alcohol treated group (0.61+/-0.03) (P<0.05), the difference among the three groups was not significant (P>0.05). The activity of NF-kB in TP treated rats(DNA stain: 669.85+/-41.34, Protein stain: 675.35+/-18.27) was significantly lower than the alcohol treated rats(DNA stain: 1410.78+/-22.19, Protein stain:1426.08+/-33.15) (P<0.01); NF-kB activity in cells of the prevention, intervention, therapeutic groups (DNA stain: 713.07+/-11.91, 710.79+/-14.99, 693.45+/-71.69; Protein stain: 758.88+/-34.65, 753.07+/-76.78, 725.77+/-36.09) was significantly lower than the alcohol treated cells (DNA stain: 849.94+/-12.45, Protein stain: 925.96+/-5.78) (P<0.01), the difference among the three TP treated groups was not significant (P>0.01). CONCLUSION: TP can alleviate and prevent alcohol-induced liver injury via inhibiting NF-kB activation.