The Underlying Mechanism of Duanteng Yimu Decoction in Inhibiting Synovial Hyperplasia in Rheumatoid Arthritis

Dysregulation of microRNAs (miRNAs) is associated with the pathogenesis of rheumatoid arthritis (RA). Our previous studies confirmed that Duanteng Yimu decoction (DTYMT) effectively inhibits RA fibroblast-like synoviocyte (FLS) proliferation. In this study, we investigated the influence of DTYMT on miR-221 in RA individuals. Hematoxylin-eosin (HE) staining was performed to assess histopathological alterations in collagen-induced arthritis (CIA) mice. The expression of miR-221-3p and TLR4 in PBMC, FLS, and cartilage was measured by RT-qPCR. In the in vitro experiments, DTYMT-containing serum was incubated with FLS-transfected miR-221 mimic or inhibitor. CCK-8 was performed to determine FLS proliferation, and the secretion of IL-1β, IL-6, IL-18, and TNF-α was quantified by ELISA assay. In addition, the regulation of miR-221 expression on FLS apoptosis was assessed using flow cytometry. Finally, western blot was employed to reflect TLR4/MyD88 protein levels. HE results showed that DTYMT effectively reduced synovial hyperplasia in the joints of CIA mice. RT-qPCR assay of FLS and cartilage of the model group showed that miR-221-3p and TLR4 significantly increased compared with those in the normal group. All outcomes were improved by DTYMT. The miR-221 mimic reversed the inhibitory effect of DTYMT-containing serum on FLS proliferation, the release of IL-1β, IL-18, IL-6, and TNF-α, and FLS apoptosis, as well as TLR4/MyD88 protein levels. The results showed that miR-221 promotes the activity of RA-FLS by activating TLR4/MyD88 signaling, and DTYMT treats RA by reducing miR-221 in CIA mice.