Electroacupuncture attenuates bone erosion and promotes macrophage polarization in a mouse model of collagen-induced arthritis

Objective: The aim of this study was to investigate the effect of electroacupuncture (EA) on macrophage polarization and bone erosion in a mouse model of collagen-induced arthritis (CIA). Methods: C57BL/B6 mice were used to establish a CIA model and were treated with electroacupuncture (EA) at ST36 and SP6. At the end of the experiment, knee joints were harvested for hematoxylin-eosin (H&E) staining to detect knee synovitis. Immunohistochemistry (IHC) was performed to assess the expression of macrophage markers. The degree of bone destruction was evaluated using micro-computed tomography (CT), tartrate-resistant acid phosphatase (TRAP) staining and safranin-O fast green staining. Peripheral blood transcriptome sequencing was performed using Illumina high-throughput sequencing. Synovial membrane proteins were quantitatively analyzed by mass spectrometry. Differentially expressed genes and proteins were identified and the R software package was used to analyze the data. Results: Compared with the model group, the arthritis index ( P < 0.05) and inflammatory infiltration decreased ( P < 0.05), cartilage destruction was inhibited ( P < 0.01), the number of osteoclasts decreased ( P < 0.05), knee bone erosion was alleviated and the M1/M2 macrophage ratio decreased ( P < 0.01) in the EA group. The results of bioinformatics analysis showed that the differential genes between the EA and model groups were mainly enriched in rheumatoid arthritis (RA) and the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Differentially expressed proteins were mostly enriched in the toll-like receptor (TLR) signaling and autophagy pathways. Conclusions: EA prevents bone erosion, reduces the M1/M2 macrophage ratio in synovial tissue, inhibits the TLR and autophagy pathways and reduces synovial invasion in a mouse model of CIA.