[Mechanism of Zhuang medicine heat-sensitive acupuncture in treating rheumatoid arthritis based on metabolomics]

To investigate the potential mechanism by which the Zhuang medicine heat-sensitive acupuncture method alleviates symptoms of rheumatoid arthritis (RA), based on metabolomics analysis.

A total of 35 SPF-grade male SD rats were randomly divided into a normal control group (10 rats) and a modeling group (25 rats). RA models were induced in the modeling group by injecting 0.1 mL of complete Freund's adjuvant (1 mg/mL) into the right hind paw. Successfully modeled 25 rats were then randomly divided into a model group (10 rats) and an observation group (15 rats). The rats in the observation group received moxibustion at the right-side "Zhenhan point"; the rats exhibiting heat-sensitive acupoint phenomena were included in the Zhuang medicine heat-sensitive acupuncture group (9 rats). The rats in this group received acupuncture at the right-side "Zhenhan point" with a retention time of 20 minutes, once daily for 21 consecutive days. Ankle joint diameter was measured on days 15, 25, 32, and 39. After the intervention, ELISA was used to detect serum levels of interleukin (IL)-10 and IL-17; hematoxylin-eosin (HE) staining was employed to observe the histomorphology of the ankle joint; fecal samples were analyzed using ultra-high performance liquid chromatography coupled with UHPLC-Q-TOF-MS for metabolomics to identify differential fecal metabolites and metabolic pathways.

Compared with the normal control group, the rats in the model group showed paw hyperthermia and swelling of right paw; right ankle joint diameters were significantly increased on days 15, 25, 32, and 39 (P<0.01); the serum level of IL-10 was decreased and that of IL-17 was increased (P<0.01); significant synovial damage and infiltration of inflammatory cells were observed in the right ankle joint. Compared with the model group, the Zhuang medicine heat-sensitive acupuncture group exhibited reduced paw swelling and decreased ankle joint diameter of right side on days 25 and 39 (P<0.05); the serum level of IL-10 was increased and that of IL-17 was decreased (P<0.05); the damage of synovial tissue in the right ankle joint was improved with reduced inflammatory cell infiltration. A total of 19 potential biomarkers were identified via metabolomics, including deoxyinosine, thiamine, cortisol, riboflavin, and 5-hydroxyindoleacetic acid, involving pathways such as amino acid metabolism, purine metabolism, steroid hormone biosynthesis, and vitamin digestion and absorption.

Zhuang medicine heat-sensitive acupuncture method can effectively alleviate joint swelling in RA model rats. The underlying mechanism may be related to modulation of tryptophan metabolism, vitamin digestion and absorption, and steroid biosynthesis pathways.