Oxidative stress induces nucleus pulposus cell senescence and metabolic substrate depletion-driven reprogramming: a multi-omics study

Nucleus pulposus cell (NPC) senescence is a core driver of intervertebral disc degeneration (IVDD), but the metabolic mechanisms underlying this process remain poorly understood. We integrated transcriptomics, untargeted metabolomics, and single-cell RNA sequencing to characterize metabolic reprogramming in TBHP-induced senescent rat NPCs, followed by validation in a human disc degeneration dataset. The functional relevance of the identified metabolic nodes was evaluated through exogenous glutamate supplementation in primary rat NPCs and an in vivo rat tail puncture model. Multi-omics integration revealed a critical metabolic bottleneck characterized by glutamate depletion, which impaired antioxidant defense despite transcriptional upregulation of synthesis enzymes. Single-cell analysis confirmed this vulnerability in senescent subpopulations. Functional rescue experiments showed that exogenous glutamate supplementation reduced ROS accumulation and partially alleviated senescence-associated changes in vitro. Furthermore, in vivo administration of glutamate in a rat tail puncture model partially alleviated histological degeneration and reduced senescence-associated markers. These findings suggest that substrate-driven metabolic alterations play a significant role in NPC senescence within our experimental models. Restoring metabolic homeostasis may offer a potential strategy for future therapeutic investigation in IVDD.