Moxibustion inhibits the macrophage M1 polarization toll-like receptor 4/myeloid differentiation factor 88/nuclear factor kappa B signaling pathway by regulating T-cell immunoglobulin and mucin-containing protein-3 in rheumatoid arthritis.

Objective: To explore whether moxibustion exerts therapeutic effects on rheumatoid arthritis (RA) by regulating the expression of T-cell immunoglobulin and mucin-containing protein-3 (TIM-3) and subsequently modulating the macrophage M1 polarization toll-like receptor 4 (TLR4)-myeloid differentiation factor 88 (MyD88)-nuclear factor kappa B (NF-κB) signaling pathway.

Methods: We utilized moxibustion treatment in RA rat models using the Zusanli (ST36) and Shenshu (BL23) acupoints. Hematoxylin and eosin (HE) staining was used to observe the pathological changes of the synovial tissue under a section light microscope, and pathological scoring was performed according to the grading standard of the degree of synovial tissue disease. Enzyme-linked immunosorbent assay (ELISA) was applied to verify the efficacy of moxibustion in reducing inflammation. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of the TIM-3/TLR4-MyD88-NF-κB signaling pathway-related molecules, and Western blot was used to detect the contents of synovial NF-κB.

Results: We established the Freund's complete adjuvant (FCA)-induced RA model in rats. The expression level of M1 polarization signaling pathway TLR4-MyD88-NF-κB and the inflammatory factors interleukin-12(IL-12), tumor necrosis factor alpha (TNF-α), and tumor necrosis factor beta (TNF-β) were significantly increased in the RA model. After moxibustion treatment, the expression level of TLR4-MyD88-NF-κB was significantly decreased, and the inflammatory factors IL-12, TNF-α, and TNF-β were decreased, but the expression level was significantly increased in the RA model. When TIM-3 expression was inhibited, the expression level of TLR4-MyD88-NF-κB, and the inflammatory factors IL-12, TNF-α, and TNF-β were not suppressed, even after moxibustion treatment.

Conclusions: Moxibustion regulates the key target TIM-3 by acting on the Zusanli (ST36) and Shenshu (BL23) points, thereby inhibiting the M1 polarization of macrophages; that is, it inhibits the TLR4-MyD88-NF-κB signaling pathway, and finally achieves alleviation of pathological changes and anti-inflammatory effects.