Anti-inflammatory effect of echinacoside in collagen-induced arthritis via Nrf2/Drp1 pathway.

Background: Oxidative damage plays an important role in the progression of rheumatoid arthritis (RA). Emerging research evidence suggests that natural antioxidants may effectively ameliorate this disease.

Objectives: To investigate the therapeutic effect of echinacoside (ECH) in a collagen-induced arthritis (CIA) mouse model and thus elucidate the underlying molecular mechanism in RA.

Material and methods: Collagen-induced arthritis mice were intraperitoneally administered 1% dimethyl sulfoxide (DMSO) (control) or 0.6 mg of ECH every other day for 1 month. Arthritis scores and the number of affected paws were assessed. On day 60, mice were euthanized, synovial tissue specimens were obtained, and serum interleukin (IL)-6 and IL-1â expression levels were measured. Mitochondrial morphologies, reactive oxygen species (ROS) content, expression of dynamin-related protein 1 (Drp1), IL-6, nod-like receptor protein 3 (NLRP3), kelch-like ECH-associated protein 1 (Keap1), and nuclear factor-erythroid-2-related factor 2 (Nrf2) contents in synovium were analyzed and compared between DMSOand ECH-treated CIA mice.

Results: Following ECH treatment, mitochondria of CIA-induced mice were found to be elongated, while their arthritis scores, inflammation and the number of affected paws, and the expression levels of Drp1, NLRP3, IL-6, ROS, and Keap1 were all found to be significantly reduced. Conversely, the level of antioxidant factor Nrf2 was found to be elevated. Further, mitochondrial fission was found to be inhibited in synovial tissues.

Conclusions: Our findings validate the therapeutic efficacy of ECH in the CIA mouse model. Echinacoside may suppress oxidative stress and inhibit inflammation by regulating the Nrf2/Drp1 pathway, thus supporting its utility in the treatment of RA.