Daphnetin ameliorates intervertebral disc degeneration via the Keap1/Nrf2/NF-κB axis in vitro and in vivo

Intervertebral disc degeneration (IVDD) is the primary cause of low back pain (LBP). Enhanced inflammation and reactive oxygen species (ROS) levels can cause apoptosis, which is one of the initial factors of IVDD. Our previous study showed that daphnetin (DAP) alleviates IVDD; however, the underlying mechanisms remain unknown. An IVDD mouse model was established by lumbar disc puncture to investigate the mechanisms of DAP regulation, and DAP was injected intraperitoneally. Moreover, nucleus pulposus cells (NPCs) were challenged with tumor necrosis factor-alpha (TNF-α)/H₂O₂ to mimic IVDD. Additionally, NPC apoptosis, ROS, and the expression of proinflammatory cytokines were comprehensively assessed. We found that DAP can reverse H₂O₂-induced ROS and play an anti-inflammatory role by inhibiting Nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. Moreover, we found that DAP inhibits the apoptosis of NPCs induced by H₂O₂/TNF-α. DAP may regulate ROS production and apoptosis via the Kelch-like ECH-associated protein 1/NF-E2-related factor 2/heme oxygenase-1 (Keap1/Nrf2/HO-1) pathway. These findings were confirmed by in vivo results. The comprehensive nature of our research provides a strong foundation for the potential use of DAP as a therapeutic agent to alleviate IVDD.