Chrysophanol prevents IL-1β-Induced inflammation and ECM degradation in osteoarthritis via the Sirt6/NF-κB and Nrf2/NF-κB axis.

Osteoarthritis (OA) is a common joint illness that negatively impacts people's lives. The main active ingredient of cassia seed or rhubarb is chrysophanol. It has various pharmacological effects including anticancer, anti-diabetes and blood lipid regulation. Previous evidence suggests that chrysophanol has anti-inflammatory properties in various diseases, but its effect on OA has not been investigated yet. In this study, chrysophanol inhibited IL-1β -induced expression of ADAMTS-4, MMP13, COX-2 and iNOS. Meanwhile, it can inhibit aggrecan and collagen degradation in osteoarthritic chondrocytes induced by IL-1β.Further studies depicted that SIRT6 silencing eliminated the chrysophanol effect on IL-1β. The results demonstrated that chrysophanol could stimulate SIRT6 activation and, more importantly, increase SIRT6 levels. We also discovered that chrysophanol might impede the NF-κB pathway of OA mice's chondrocytes induced by IL-1β, which could be because it depends on SIRT6 activation to some extent. It had also been previously covered that chrysophanol could produce a marked effect on Nrf2/NF-κB axis [1]. Therefore, we can infer that chrysophanol may benefit chondrocytes by regulating the SIRT6/NF-κB and Nrf2/NF-κB signaling axis.We examined the anti-inflammatory mechanism and the impact of chrysophanol on mice in vitro and in vivo. In summary, we declare that chrysophanol diminishes the inflammatory reaction of OA in mice in vitro by regulating SIRT6/NF-κB and Nrf2/NF-κB signaling pathway and protects articular cartilage from degradation in vivo. We can infer that chrysophanol could be an efficient therapy for OA.