Supercritical CO2 extracts of Achyranthes japonica Nakai root inhibits arthritis pathogenesis in mice in vitro and in vivo

Abstract

Achyranthes japonica Nakai root (AJNR) is used to treat osteoarthritis (OA) and rheumatoid arthritis (RA) because of its anti-inflammatory and antioxidant effects. The present study investigated the inhibitory effects of AJNR on arthritis. AJNR was extracted using supercritical CO2. The inhibitory effects of ANJR against arthritis were evaluated using primary cultures of articular chondrocytes and two in vivo arthritis models: destabilization of the medial meniscus (DMM) for the OA model and collagenase-induced arthritis (CIA) for the RA model. AJNR did not affect pro-inflammatory cytokine (IL-1a, TNF-b, and IL-6)-mediated cytotoxicity, but attenuated pro-inflammatory cytokine-mediated increases in catabolic factors and recovered pro-inflammatory cytokine-mediated decreases in anabolic factors in the in vitro model. The effect of AJNR is particularly specific for IL-6-mediated catabolic or anabolic alteration. In the DMM model, AJNR decreased cartilage erosion, subchondral plate thickness, osteophyte size, and osteophyte maturity. In the CIA model, AJNR effectively inhibited cartilage degeneration and synovium inflammation in either the ankle or knee and reduced pannus formation in both the knee and ankle. Immunohistochemistry analysis revealed that AJNR mainly acted via the inhibitory effects of IL-6-mediated matrix metalloproteinase-3 and -13 in both arthritis models. AJNR is a potential therapeutic agent for relieving arthritis symptoms.