OBJECTIVE To investigate the regulatory effects of Qufeng Zhitong formula on the Janus kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3) signaling pathway and oxidative stress in adjuvant-induced arthritis mice, and to analyze its potential mechanisms in the treatment of rheumatoid arthritis.

METHODS Forty SPF-grade male ICR mice were randomly divided using a stratified random method into the following groups(n=10 per group): control group, model group, positive control group(diclofenac diethylamine, DDE), and Qufeng Zhitong formula group. Except for the control group, each mice in all other groups received a subcutaneous injection of 0.1 mL complete Freund's adjuvant into the right hind paw to establish an adjuvant-induced arthritis(AA) mouse model simulating rheumatoid arthritis. Mice in the control group were injected with an equal volume of saline using the same method. Mice in each group began topical administration on day 7 after modeling and continued for 28 d before sample collection. The following analyses were performed: Flow cytometry was used to detect the proportions of CD4⁺ Th17 and CD25⁺ Foxp³⁺ Treg cells in mouse splenocytes. Hematoxylin and eosin(HE) staining was used to observe the pathological morphology of ankle joint tissues. Immunohistochemistry(IHC) was employed to detect the expression and localization of JAK2 and STAT3 proteins in ankle joint tissues. Enzyme-linked immunosorbent assay(ELISA) was used to detect the serum levels of oxidative stress-related indicators; Western blotting was employed to assess the expression levels of proteins related to the JAK2/STAT3 signaling pathway in ankle joint tissues.

RESULTS Compared to the control group, mice in the model group showed a significant decrease in body weight(P<0.05), along with obvious redness, swelling of the paws, and joint deformation. In contrast, both the positive control group and Qufeng Zhitong formula group exhibited a significant increase in body weight(P<0.05), along with reduced paw swelling and joint pathological damage compared to the model group.Flow cytometry results revealed that the proportions of Th17 cells decreased, while the proportions of Treg cells increased in the splenocytes of both the positive control and Qufeng Zhitong formula groups(P<0.05). Immunohistochemistry results demonstrated weakened expression intensity of JAK2 and STAT3 in the ankle joints of these two groups. ELISA assays indicated that the positive control and Qufeng Zhitong formula groups could reduce serum MDA content and enhance the activities of GSH-Px, CAT, and SOD(P<0.05). Western blotting results showed that the Qufeng Zhitong formula group had reduced protein expression of p-JAK2 and p-STAT3, while the expression of SOCS1 and SOCS3 proteins was increased(P<0.05).

CONCLUSION These findings suggest that Qufeng Zhitong formula can inhibit the activation of the JAK2/STAT3 signaling pathway, upregulate the expression of SOCS1/SOCS3, and alleviate oxidative stress, thereby exerting a therapeutic effect on rheumatoid arthritis.