Kaempferol Improved Rheumatoid Arthritis by Regulating the Immune Imbalance of Treg/Th17.

OBJECTIVE

The objective of this study was to explore the therapeutic effects of kaempferol (Kae) on rheumatoid arthritis (RA) and to elucidate the underlying mechanisms.

METHODS

The collagen-induced arthritis (CIA) model was established using collagen II to induce RA. Mice were treated with Kae at a dose of 25 or 50 mg/kg/day via gavage. Pathological changes in the ankle joint were analyzed. Enzyme-linked immunosorbent assay (ELISA) was employed to measure the levels of inflammatory factors. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to assess the expression of genes associated with the balance of regulatory T (Treg)/T helper 17 (Th17) cells. Flow cytometry was utilized to determine the Treg/Th17 ratio. Furthermore, these techniques were employed to evaluate the impact of miR-34a and Foxp3 dysregulation on cellular functions in RA under the influence of Kae. Dual luciferase reporter assay was conducted to analyze the binding of miR-34a to Foxp3.

RESULTS

Treatment with Kae led to a downregulation of receptor-related orphan receptor gamma t (RORγt) and IL-17 expression, and an upregulation of Foxp3, IL-10, and TGF-β expression in CIA mice. Kae intervention inhibited the production of proinflammatory cytokines and increased the production of anti-inflammatory cytokines. Furthermore, Kae treatment suppressed the expression of miR-34a, which was identified as a target of miR-34a. Finally, Kae regulated Treg/ Th17 balance-related genes and cellular inflammation through the miR-34a/Foxp3 axis.

CONCLUSION

The study demonstrated that Kae effectively ameliorates CIA in mice by modulating the Treg/Th17 balance and related genes via the miR-34a/Foxp3 axis. These findings suggest that Kae may serve as a promising therapeutic agent for the treatment of RA and for restoring immune homeostasis.