Cynarin alleviates intervertebral disc degeneration via protecting nucleus pulposus cells from ferroptosis

Intervertebral disc degeneration (IVDD) leads to a series of degenerative spine diseases. Clinical treatment of IVDD is mainly surgery, lacking effective drugs to alleviate intervertebral disc degeneration. In this study, we analysed the mRNA sequencing dataset of human degenerative intervertebral disc tissues and revealed the participation of ferroptosis in IVDD. Furthermore, we confirmed that TNF-α, an important cytokine in IVDD, induces ferroptosis in nucleus pulposus cells. Subsequently, a ferroptosis inhibitors screening strategy using multiple ferroptosis indicators was developed. Through the screen of various natural compounds, cynarin, a natural product enriched in Artichoke, was discovered to inhibit ferroptosis of nucleus pulposus cells. Cynarin can dose-dependently inhibit the catabolism of nucleus pulposus cells, increase the expression of key ferroptosis-inhibiting genes (GPX4 and NRF2), inhibit the increment of cellular Fe2+, lipid peroxides, and reactive oxygen species. It can also prevent mitochondria shrinkage, reduce mitochondria cristae density in ferroptosis, and prevent IVDD in the rat model. In conclusion, cynarin is a potential candidate for the drug development for IVDD.