Protective effects of Wang-Bi tablet on bone destruction in collagen-induced arthritis by regulating osteoclast-osteoblast functions

Abstract Ethnopharmacological relevance Wang-bi tablet (WB) consists of 17 traditional Chinese medicines and has been used for treating rheumatoid arthritis (RA) in China for many years, however, its pharmacologic mechanism is not clear. Aim of study The aim of this study was to investigate the therapeutic effect of WB on collagen-induced mouse arthritis and explored the underlying mechanism. Materials and methods DBA/1 mice were used to establish a type II collagen-induced arthritis (CIA) model. From the day of arthritis onset, mice were treated daily by gavage with either total glucosides of paeony (TGP, 0.37  g/kg/d) or WB at a lower (1.11  g/kg/d, WBL) or higher dose of (3.33  g/kg/d, WBH) for 8 weeks. The severity of arthritis, levels of cytokines and the activation of signaling pathways were determined. Results Our results revealed that WB treatment effectively alleviated inflammatory symptoms and prevented bone erosions and joint destructions. It obviously decreased the serum concentration of pro-inflammatory cytokines TNF-α, IL-6 and IL-17α, while increased the concentration of anti-inflammatory cytokine IL-10. Interestingly, the proportion of splenic Treg cells were increased significantly. In vitro experiments showed that WB inhibited the differentiation of osteoclasts. Consistently, the mRNA levels of tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CtsK), and the activation of NF-κB and JAK-STAT3 signaling pathways in the paws of CIA mice were inhibited by WB treatment. On the other hand, up-regulation of osteogenic genes Runx2, Osterix mRNA, and activation of Wnt/β-catenin signaling pathway along with a decreased receptor activator of nuclear factor κB ligand (RANKL) expression were found in WB treated mice. Conclusion Our results suggest that the therapeutic effect of Wang-bi tablet could be attributed to its inhibitory activity on NF-κB and STAT3 signaling pathway-mediated osteoclast differentiation, and its enhancement on Wnt/β-catenin signaling pathway-mediated osteoblast functions.