Enhanced efficacy with reduced toxicity of tripterygium glycoside tablet by compatibility with total glucosides of paeony for rheumatoid arthritis therapy

Drug-induced liver injury remains a critical issue to hinder clinical application of Tripterygium Glycosides Tablets (TGTs) for rheumatoid arthritis (RA) therapy. Combination of TGTs with Total Glucosides of Peony (TGP) may be the most common therapeutic strategy for enhancing TGTs’ efficacy and reducing its toxicity. Herein, we aimed to investigate the efficacy-enhancing and toxicity-reducing properties and mechanisms of TGT-TGP combination. Both TGT-induced acute and chronic liver injury animal models were established. ELISA, transmission electron microscopy, immunohistochemistry, western blot and quantitative PCR were performed to determine the efficacy, toxicity and regulatory mechanisms of TGT-TGP combination. The compatibility of TGP significantly reduced the abnormal serum ALT and AST levels, and improved liver histopathological changes in both acute and chronic DILI animal models induced by TGTs, with the most effective dosage of TGP-M (medium-dose TGP, 450 mg/kg). Additionally, TGP and TGT synergistically alleviated joint swelling and improved the elevation of serum inflammatory factors, in line with the positive changes in joint histopathological features of collagen induced arthritis mice, with the same effective dosage of TGP-M following 5 weeks’ drug combination treatment. Mechanically, TGT significantly increased the number of autophagosomes and the expression of LC3II protein while reducing p62 protein expression in the liver tissues, which were significantly reversed by the compatibility with TGP, similar to the findings based on the inflamed joint tissues. These findings suggest an enhanced efficacy with reduced toxicity of TGT by the compatibility with TGP for RA therapy, possibly through regulating various autophagy-related proteins.