Cannabidiol Is a Potential Inhibitor of Ferroptosis in Human Articular Chondrocytes

The present study investigates the effects of cannabidiol (CBD), the major non-psychoactive compound of Cannabis sativa L. extracts, on ferroptotic cell death in human articular chondrocytes. Exposure to known ferroptosis inducers RSL3, erastin and its analogue IKE, FINO2 and FIN56 led to a varying extent of reduced cell viability in two chondrocyte cell lines (in C-28/I2, T/C-28/A2) and primary chondrocytes, suggesting different sensitivity and defence mechanisms towards the respective substances. The cytotoxic effects were aggravated by additional exposure to iron and inhibited by the specific ferroptosis inhibitor ferrostatin-1 (Fer-1), proving the occurrence of ferroptosis. Strikingly, co-treatment of ferroptosis inducers with CBD clearly restored cell viability in a dose-dependent manner (10 nM to 1 μM CBD) in both cell lines and primary chondrocytes. Moreover, CBD restored the activity of GPX4, a major anti-oxidative enzyme, to varying degrees when combined with IKE or RSL3. Increasing evidence has emerged for an important role of iron dyshomeostasis and ferroptosis in the onset and progression of various orthopaedic diseases, including osteoarthritis. Therefore, the here demonstrated and previously unreported cytoprotective and anti-oxidative effects of CBD in the context of ferroptosis have highly promising therapeutic implications.