[Songjie Formula alleviates rheumatoid arthritis in rats with wind-cold-dampness syndrome by regulating Th17/Treg immune balance].

OBJECTIVES

To investigate the therapeutic mechanism of Songjie Formula (SJF) for alleviating rheumatoid arthritis (RA) with wind-cold-dampness arthralgia syndrome (WCDA) from the perspective of Th17/Treg immune balance.

METHODS

Twenty male SD rat models of RA with WCDA were randomized into two equal groups for daily gavage with saline (model group) or SJF for 14 consecutive days, with 10 normal rats serving as the normal control group. The changes in body weight, general condition, and plantar swelling of the rats were monitored. Serum levels of interleukin-10 (IL-10), IL-17, IL-21, and tumor necrosis factor alpha (TNF-α) were measured using ELISA, and Th17 and Treg cell percentages in peripheral blood and splenic T cell subsets were analyzed by flow cytometry. RT-qPCR and Western blotting were used to detect the mRNA and protein expression levels of retinoic acid-related orphan receptor γt (RORγt) and forkhead box P3 (Foxp3) in the ankle joint synovial tissue.

RESULTS

In the rats models of RA with WCDA, SJF gavage significantly improved the general condition, reduced foot swelling, downregulated serum levels of IL-17, IL-21, and TNF-α, upregulated IL-10 level, and obviously increased Treg cell percentage while decreasing Th17 cell percentage. SJF treatment also significantly suppressed the expressions of RORγt mRNA and protein, promoted Foxp3 mRNA and protein expressions, and alleviated synovial inflammatory cell infiltration in the rat models.

CONCLUSIONS

SJF regulates inflammatory cytokine levels, Th17/Treg ratio, and RORγt/Foxp3 expressions in RA rat model with WCDA, suggesting that its therapeutic efficacy for RA is mediated primarily by ameliorating joint inflammation and pathologies via modulating the Th17/Treg balance.