[Effects of acupuncture on intestinal microbiota in mice with rheumatoid arthritis].

Objectives: To observe the effect of acupuncture on gut microbiota in mice with rheumatoid arthritis (RA), so as to explore its mechanisms underlying improvement of RA.

Methods: Eighteen male C57BL/6J mice were randomly divided into saline, model and acupuncture groups, with 6 mice in each group. The RA model was established by injection of complete Freund's adjuvant (CFA, 50 μL) into the right hind paw. Acupuncture group received manual acupuncture stimulation of the bilateral "Zusanli" (ST36) for 30 min, once daily for 7 days. The paw withdrawal thermal latency (PWTL) was detected by using a thermal pain detector. After the last intervention, the mice's feces were collected for extracting the feces DNA, and 16S RNA sequencing was used to detect and analyze the diversity and structural composition of intestinal flora.

Results: Compared with the saline group, the PWTL from day 0 to 7 after administration of CFA was significantly decreased (P<0.01), and the paw swelling volume from day 0 to 7 significantly increased in the model group (P<0.01). In comparison with the model group, the PWTL from day 1 to 7 was significantly increased (P<0.01), and the paw swelling volume on day 7 was strikingly decreased (P<0.01) in the acupuncture group. The Alpha diversity analysis of intestinal flora showed that the Chao1 index was markedly decreased in the model group compared with the saline group (P<0.05), and markedly increased in the acupuncture group compared with the model group (P<0.05). Beta diversity principal coordinate analysis (PCoA) displayed that the intestinal microbiota community structure of each group was different, and there were some overlapping areas, but they could be distinguished (P<0.01), suggesting that the species richness and diversity of RA mice were changed after acupuncture treatment. Compared with the saline group, the relative abundance of Bacteroidota was decreased (P<0.05), and that of Desulfobacterota and Escherichia-Shigella significantly increased (P<0.05) in the model group. In comparison with the model group, the relative abundance of Actinobacteria and Lactobacillus was considerably increased (P<0.05, P<0.01), while that of Escherichia-Shigella and Faecalibacterium strikingly decreased (P<0.05) in the acupuncture group.

Conclusions: Acupuncture treatment can significantly alleviate joint inflammation in RA mice, which may be related to its function in regulating the diversity and composition of gut microbiota.