Mechanism of action and new developments in the study of curcumin in the treatment of osteoarthritis: a narrative review.

Osteoarthritis is a degenerative joint disease that affects the aging population worldwide. It has an underlying inflammatory cause that leads to loss of chondrocytes, reducing the cartilage layer at the affected joints. Compounds with anti-inflammatory properties are potential therapeutic agents for osteoarthritis. Curcumin, derived from species of the Curcuma, is an anti-inflammatory compound. The purpose of this review is to summarize the anti-osteoarthritic effects of curcumin from clinical and preclinical studies. Many clinical trials have been conducted to determine curcumin's effectiveness in osteoarthritis patients. Available studies have shown that curcumin prevents chondrocyte apoptosis and inhibits the release of proteoglycans and metalloproteinases as well as the expression of cyclooxygenase, prostaglandin E-2, and inflammatory cytokines in chondrocytes. The mechanism of action of curcumin also involves multiple cell signaling pathways, including Nuclear factor kappa-B(NF-κB), Mitogen-activated protein kinase (MAPK), Wnt/β-catenin pathway (Wnt/β-catenin), The Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3), Nuclear factor erythroid 2-related factor 2/antioxidant response elements/heme oxygenase-1(Nrf2/ARE/HO-1), and Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathways. Curcumin further reduced the release of inflammatory factors and apoptosis by inhibiting the activation of NF-κB. In addition, curcumin modulates the MAPK, Nrf2/ARE/HO-1, and PI3K/Akt/mTOR signaling pathways and affects cell proliferation and apoptosis processes, a series of effects that together promote the healthy state of chondrocytes. In conclusion, curcumin, as a natural plant compound, exhibits significant anti-inflammatory potential by modulating inflammatory factors associated with articular osteoarthritis through multiple mechanisms. Its protective effects on articular cartilage and synovium make it a promising candidate for the treatment of OA. Future studies should further explore the mechanism of action of curcumin and its optimal dosage and therapeutic regimen in clinical applications, to provide more effective therapeutic options for osteoarthritis patients.