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.
Keywords: Arthritis, experimental; Arthritis, rheumatoid; CD4-CD8 ratio; Fas ligand protein; TNF receptor-associated factor 6; Toll-like receptor 2; Total glucosides of paeony; Transcription factor RelA.