Inhibitory Effects of IL-6-Mediated Matrix Metalloproteinase-3 and -13 by Achyranthes japonica Nakai Root in Osteoarthritis and Rheumatoid Arthritis Mice Models

Achyranthes japonica Nakai root (AJNR) is used to treat osteoarthritis (OA) and rheumatoid arthritis (RA) owing to its anti-inflammatory and antioxidant effects. This study investigated the inhibitory effects of AJNR on arthritis. AJNR was extracted using supercritical carbon dioxide (CO2), and its main compounds, pimaric and kaurenoic acid, were identified. ANJR's inhibitory effects against arthritis were evaluated using primary cultures of articular chondrocytes and two in vivo arthritis models: destabilization of the medial meniscus (DMM) as an OA model, and collagenase-induced arthritis (CIA) as an RA model. AJNR did not affect pro-inflammatory cytokine (IL-1 beta, TNF-alpha, IL-6)-mediated cytotoxicity, but attenuated pro-inflammatory cytokine-mediated increases in catabolic factors, and recovered pro-inflammatory cytokine-mediated decreases in related anabolic factors related to in vitro. The effect of AJNR is particularly specific to IL-6-mediated catabolic or anabolic alteration. In a DMM model, AJNR decreased cartilage erosion, subchondral plate thickness, osteophyte size, and osteophyte maturity. In a 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. Therefore, AJNR is a potential therapeutic agent for relieving arthritis symptoms.

Automated summary

AJNR, extracted from Achyranthes japonica Nakai root, demonstrated inhibitory effects against arthritis by attenuating IL-6-mediated catabolic or anabolic alterations, reducing cartilage erosion, inflammation, and pannus formation in arthritis models.