Total glucosides of paeony improve complete freund’s adjuvant-induced rheumatoid arthritis in rats by inhibiting toll-like receptor 2-mediated tumor necrosis factor receptor-associated factor 6/nuclear factor-kappa B pathway activation

OBJECTIVE: To investigate the mechanism underlying anti-inflammatory and immunoregulatory effect of total glucosides of paeony(TGP) based on toll-like receptor 2(TLR2) mediated tumor necrosis factor(TNF) receptor-associated factor 6(TRAF6)/nuclear factor-kappa B(NF-κB) pathway activation in rats with rheumatoid arthritis.METHODS: Adjuvant arthritis(AA) model was developed by complete freund’s adjuvant(CFA) immunization. TGP(100, 50, 25 mg/kg) and celecoxib(2.8 mg/kg) were administered by intragastric administration for 21 d. Right hind paw swelling was assessed every 2 d. After 21 d, synovial changes of the ankle were detected by histopathology. CD4+and CD8+ T cell amounts in peripheral blood were measured by flow-cytometrically. Gene and protein levels of toll-like receptor(TLR)2, TRAF6, tumor necrosis factor ligand superfamily member 6(FASLG)in the spleen were assessed by RT-qPCR and Western Bolt, respectively. Nuclear expression of NF-κB p65 was detected by NF-κB p65 Assay Kit.RESULTS: Paw swelling and synovium lesions were obviously aggravated in AA rats. These symptoms were significantly relieved by TGP.The ratio of CD4+/CD8+ T cell was increased in AA rats, while TGP reduced this increased ratio.Gene and protein levels of splenic TLR2, TFAR6 and FASLG, and nuclear NF-κB p65 in AA rats were significantly increased, but overtly inhibited by TGP.CONCLUSION: These findings suggest that TGP’s anti-inflammatory effect onRA in rats with CFA may be related to the downregulation of TLR2/TRAF6/NF-κB pathway and the regulation of T cell subsets.