Moxibustion of Zusanli (ST36) and Shenshu (BL23) alleviates the inflammation of rheumatoid arthritis in rats through regulating macrophage migration inhibitory factor/glucocorticoids signaling

OBJECTIVE: To test the hypothesis that moxibustion may inhibit rheumatoid arthritis (RA) synovial inflammation by regulating the expression of macrophage migration inhibitory factor (MIF)/glucocorticoids (GCs). METHODS: Fifty male Sprague-Dawley rats were randomly divided into five groups (n = 10 each): blank Control (CON) group, RA Model (RA) group, Moxibustion (MOX) group, MIF inhibitor (S,R)-3-(4-hydroxyphenyl)4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO -1) group, and Moxibustion + MIF inhibitor ISO -1 (MOX + ISO -1) group. Rats in the ISO -1 group and ISO -1 + MOX group were intraperitoneally injected with the inhibitor ISO -1. The rats in the RA group, ISO -1 group, MOX group, and ISO -1 + MOX group were injected with Freund's complete adjuvant (FCA) in the right hind footpad to establish an experimental RA rat model. In the MOX group and MOX + ISO -1 group, rats were treated with Moxa. The thickness of the footpads of the rats in each group was measured at three-time points before, after modeling and after moxibustion treatment. The contents of serum MIF, corticosterone (CORT), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) were detected by enzyme-linked immunosorbent assay; and the contents of synovial MIF were detected by Western blot. Hematoxylin-eosin (HE) staining method was used to observe the pathological changes of synovial tissue under a section light microscope, and pathological scoring was performed according to the grading standard of the degree of synovial tissue disease. RESULTS: Moxibustion was found to reduce the level of MIF and alleviate inflammation in RA rats in this study. In addition, after inhibiting the expression of MIF, the level of CORT increased, and the level of TNF-alpha decreased. Treating RA rats with inhibited MIF by moxibustion, the level of CORT was almost unchanged, but the level of TNF-alpha further decreased. The correlation analysis data suggested that MIF was positively related to the expression of TNF-alpha and negatively correlated with the expression of CORT. CONCLUSION: Reducing MIF to increase CORT and decrease TNF-alpha by moxibustion treatment in RA. MIF may be a factor for moxibustion to regulate the expression of CORT, but the expression of TNF-alpha is due to the incomplete regulation of the MIF. This study added to the body of evidence pointing to moxibustion's antiinflammatory mechanism in the treatment of RA.