Adapt, Mitigate, and Target: The Role of Oxidative Stress in Intervertebral Disc Homeostasis and Disc Degeneration.

The intervertebral disc (IVD) is defined by a uniquely avascular niche characterized by constitutive hypoxia, limited nutrient diffusion, acidic pH, hyperosmolarity, and repetitive mechanical loading. These stressors interact with each other rather than acting in isolation. Reduced endplate transport exacerbates hypoxia and glucose deprivation, driving glycolytic lactate accumulation and acidification. In parallel, acid-osmotic stress perturbs ion homeostasis and mitochondrial membrane potential, while mechanical loading promotes microdamage and inflammatory mediator release. Together they converge on common reactive oxygen species (ROS)-generating nodes, including mitochondrial electron transport disruption, membrane oxidase activation, and endoplasmic reticulum stress, while redox-sensitive signaling by nuclear factor erythroid 2-related factor 2, hypoxia-inducible factor 1/2, nuclear factor kappa B, and mitogen-activated protein kinases integrates metabolic rewiring with catabolic and inflammatory programs. In a healthy state, controlled ROS levels participate in healthy cell signaling and are counterbalanced by antioxidant systems; however, when compensatory capacity is exceeded, oxidative stress becomes self-reinforcing through inflammation-ROS feedback, mitochondrial dysfunction, and impaired proteostasis. This shift drives apoptosis and senescence of disc cells, extracellular breakdown, and endplate, thereby promoting IVD degeneration and creating a microenvironment for vascular and nerve ingrowth associated with discogenic low back pain. We propose an "Adapt-Mitigate-Target" framework that maps (1) physiological adaptation, (2) transition to redox breakdown, and (3) therapeutic opportunities to reduce the oxidative stress burden. We also highlight translational constraints imposed by disc transport barriers and discuss stage-appropriate systemic, local/intradiscal, and mitochondria-directed strategies, alongside a roadmap for biomarkers, precision phenotyping, and combination therapies.