Abstract: BACKGROUND: It has been shown that acupotomy therapy can improve the symptoms of rheumatoid arthritis, reduce the swelling of the joints, and improve the function of the damaged joints in clinical practice. However, the specific mechanism has not been reported in animal experiments. 
OBJECTIVE: To observe the effect of acupotomy therapy on the expression of Bcl-2 and Bax in synovial tissue of collagen-induced arthritis rats. 
METHODS: Forty rats were prepared for the experiment. Ten of them were randomly selected as normal controls, and the other 30 rats were used to manufacture collagen-induced arthritis models via secondary immunization. After the modeling, 20 successful models were randomly selected for subsequent experiments and randomly divided into a model group and an acupotomy group, with 10 in each group. Normal group and model group remain untreated. The medial and lateral patellofemoral ligament, the tibial and fibular collateral ligament, the midpoint of the upper margin of the patella and the midpoint of the patellar ligament around the left knee joint were selected as points of acupotomy treatment, two of which were selected for each acupotomy session. Rats in the acupotomy group were treated once a week for 3 continuous weeks. The general condition of experimental rats was monitored daily, thickness of the left posterior toe was measured and arthritis index was evaluated. Hematoxylin-eosin staining was executed to observe the pathological morphology of the synovial tissue. Real-time quantitative PCR and immunofluorescence staining were implemented to measure gene expression and immunofluorescence intensity of Bcl-2 and Bax in synovial tissue, respectively. The study protocol was approved by the Animal Ethic Committee of Hubei University of Traditional Chinese Medicine with an approval No. 00127518.
RESULTS AND CONCLUSION: Compared with the normal group, the thickness of the left posterior toe and arthritis index score of the model group were significantly increased (P < 0.01, P < 0.01). Compared with the model group, the left hind toe thickness and arthritis index score of the acupotomy group were decreased (P < 0.05, P < 0.05). Hematoxylin-eosin staining showed that: pathologically, the synovial layers of the model group were thicker, with infiltration of a large number of inflammatory cells. However, the synovial layers of the acupotomy group were fewer with less infiltration of inflammatory cells. RT-PCR showed that there was no significant difference in the expression of Bax mRNA in the synovial tissue between all the groups (P > 0.05). The expressions of Bcl-2 mRNA and Bcl-2/Bax mRNA were significantly reduced in the acupotomy group compared with the model group (P < 0.01, P < 0.01). Immunofluorescence detection indicated that the fluorescence intensity of Bcl-2/Bax in the acupotomy group was significantly reduced compared with the model group (P < 0.01). To conclude, the down-regulation of Bcl-2 expression and Bcl-2/Bax ratio in the synovial tissue may be one of its mechanisms for improving rheumatoid arthritis.

Key words: acupotomy, arthritis, rheumatoid arthritis, synovium, apoptosis, animal, rat