Objective        To study the effect of sinomenine (Sin) on IL-8 expression in porphyromonas gingivalis lipopolysaccharide (LPS)-stimulated human gingival fibroblasts (HGF).       Methods       HGF were pretreated with Sin at the concentrations of 25

50 and 100 μmol/L for 24 h and then with 1 μg/ml LPS which was added into Sin. Effect of Sin on LPS-mediated IL-8 expression in HGF was detected by RT-PCR and ELISA

respectively. Effect of Sin on NF-κB translocation and IκB degradation was detected by Western blotting. Effect of NF-κB inhibitors

Bay11-7085 (10 μmol/L) and TPCK (20 μmol/L)

on Sin-mediated IL-8 expression in HGF

was detected by ELISA 24 h after pretreatment followed by 4 h-LPS stimulation.       Results       Sin suppressed the IL-8 mRNA and protein expressions in LPS-mediated HGF in dose-dependent manner (P0.05). SIN could almost keep the NF-κB in the cytoplasm compared with LPS. Most NF-κB was transported in the nuclei 1 h after LPS treatment. The NF-κB level was 2-fold higher than the LPS level in cytoplasm after Sin (100 μmol/L) pretreatment. Fifty percent of IκBα was degraded 1 h after the HGF were pretreated with LPS and Sin inhibited the LPS-mediated degradation of IκBα in a dose-dependent manner after HGF were pretreated (P0.05). Sin (50 μmol/L) pretreatment returned the LPS-mediated IκBα degradation to its normal levels. The IL-8 expression level was 2.4-fold higher in LPS pretreatment group than in control group

and 1.8-fold and 1.6-fold lower in LPS pretreatment group than in control group after pretreatment with NF-κB inhibitors

Bay11-7085 (10 μmol/L) and TPCK (20 μmol/L).       Conclusion       Sin inhibits the porphyromonas gingivalis LPS-mediated IL-8 expression in HGF by blocking the NF-κB translocation and the IκBα degradation.