A Non-targeted Metabolomics Reveals Therapeutical Effect and Mechanism ofSanmiao Pill on Adjuvant-induced Arthritis Rats

Background and Objective: Rheumatoid arthritis (RA) is an increasingly serious disease worldwide that can damage the joints and bones of sufferers. Sanmiao Pill (SMP), a classical traditional Chinese medicine (TCM) prescription, has been used for effective treatments for RA in the clinic. To comprehensively illuminate the therapeutic mechanism of SMP in the treatment of RA, the effects of SMP on biomarkers and metabolic pathways in rats with adjuvant-induced arthritis (AIA) were examined. Methods: Sprague Dawley rats were randomly divided into two control (CC, Control) groups, two model (MM, Model) groups, a methotrexate group (MTX, 7.6 mg/kg body weight per week), and two SMP groups (San-L, 28.7 mg/kg body weight per day and San-H, 57.4 mg/kg body weight per day). Rats' body weight, paw swelling, arthritis scores, biochemical parameters, histopathology, and so on were used to evaluate the success of the model and the therapeutic effects of SMP. The metabolic techniques were used to characterize the metabolic profile and biomarkers of the serum and urine samples of rats to reveal the metabolic changes that occurred after SMP treatment. Results: After 21 days of treatment, SMP improved weight gain, reduced the severity of paw swelling, lowered the levels of biochemical indicators (CCP-Ab, IL-6, TNF-α, RF), decreased destruction of articular cartilage and bone erosion, and protected the affected joints.Additionally, 17 and 19 potential biomarkers associated with RA were identified in the serum and urine, respectively. SMP significantly reversed 14 potential biomarkers, such as arachidonic acid, lysoPC(20:4(5Z,8Z,11Z,14Z)), L-tryptophan, 9-cis-Retinoic acid, hippuric acid, pyridoxine, and pantothenic acid. These metabolites are associated with arachidonic acid metabolism, glycerophospholipid catabolism, tryptophan metabolism, phenylalanine metabolism, vitamin B6 metabolism, etc. Conclusion: These results indicated that RA-related biomarkers reflected the metabolic profile of AIA rats. Meanwhile, SMP could effectively treat RA mainly by reducing inflammation and regulating abnormal lipid metabolic pathways and amino acid metabolisms. It showed that metabolomics could be used to analyze the metabolic profiles involved in RA and reveal the mechanism of SMP treatment of RA.