Urinary metabolomics reveals the therapeutic mechanism of moxibustion on collagen-induced arthritis in rats

Introduction Rheumatoid arthritis (RA) is a global disease with a high disability rate. Moxibustion, a well-known traditional Chinese medicine (TCM) therapy that has a long history in the treatment of RA, has attracted increasing clinical attention. However, little is known about its therapeutic mechanism. This study aimed to investigate the mechanism of moxibustion in the treatment of RA in rats through metabolomics. Methods In this study, rats with collagen-induced arthritis (CIA) were treated with moxibustion daily for three weeks at the Shenshu (BL 23) and the Zusanli acupoints (ST 36). Their weight, swelling of the hind paw, arthritic scores, histopathological parameters, and inflammatory factors were assessed. The urine samples of the rats in each group were collected after each course of moxibustion treatment. Gas chromatography–mass spectrometry was used to explore the changes in the urine metabolism spectrum at different courses of moxibustion treatment and analyze the relevant targeted metabolic pathways. Results Results showed that moxibustion alleviated the severity of arthritis and changed 33 metabolites in the urine of rats. These metabolites are involved in glycolysis/gluconeogenesis; tricarboxylic acid (TCA) cycle; and phenylalanine, tryptophan, butanoate, and purine metabolism. The levels of these metabolites in the moxibustion group showed trends similar to those in the control group. Conclusion Moxibustion treatment effectively inhibited inflammation in rats with CIA by regulating glycolysis/gluconeogenesis; TCA cycle; phenylalanine, tryptophan, purine and butanoate metabolism; and other biological pathways. Metabolomics may be an effective way to explain the mechanisms of moxibustion for RA.