Casticin attenuates rheumatoid arthritis through PKC-NF-κB signaling in vitro and in vivo

Casticin, as a major effective component in Chinese herbal medicine Vitex agnus-castus exhibits an antiinflammatory property to rheumatoid arthritis (RA), while the potential mechanism is unclear. We aim at investigating the mechanism of Casticin on lipopolysaccharides (LPS)-induced fibroblast-like synoviocytes (LiFLSs) inflammation model. Fibroblast-like synoviocytes (FLSs) were treated with 200 mg/ml of LPS for 24 h to establish RA-like model, LiFLSs. FLSs were pretreated with casticin (0.1-1 μM) for 30 min in the treatment groups. Quantitative realtime polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assays (ELISA) were used to detect mRNA and protein level of IL-10 and TNF-α. Signal proteins involved in IL-10 production were analyzed by Western blotting. Casticin significantly reversed the inhibitory effects of LPS on IL-10 expression in FLSs by activating PKCNF-κB pathway. Besides, casticin inhibited TNF-α expression in FLSs which was induced by LPS, and this effect was markedly diminished by IL-10 neutralizing antibody. The IL-10 mediated suppression of TNF-α transcription which was demonstrated by no response to protein synthesis inhibitor cyclohexamide and no mRNA decay. Casticin inhibits TNF-α production induced by LPS in FLSs through PKC-NF-κB-IL-10 pathway, and this study also highlights the potential application of casticin in the treatment of RA.