Integrated molecular, microRNA, and biochemical profiling reveals oxidative stress–driven degeneration of the ligamentum flavum in lumbar spinal stenosis

Degenerative lumbar spinal stenosis (LSS) is driven by fibrosis and hypertrophy of the ligamentum flavum (LF). Oxidative stress-an excess of reactive oxygen species (ROS) over antioxidant defenses-may underlie LF remodeling, but tissue-level evidence is limited. LF from patients with LSS (n = 180) and controls (n = 102) underwent transcriptomic microarray and microRNA (miRNA) profiling, reverse-transcription quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and biochemical assays of thiobarbituric acid-reactive substances (TBARS), total glutathione (GSH), and glutathione peroxidase (GPx) activity. Protein-protein interaction (PPI) and functional enrichment analyses were performed. Among 14,130 oxidative-stress-related transcripts, 8,197 were differentially expressed (p < 0.05). Redox-sensitive inflammatory mediators were upregulated, including tumor necrosis factor (TNF), interleukin-1β (IL-1B), interleukin-6 (IL-6), and C-X-C motif chemokine ligand 8 (CXCL8), alongside mitogen-activated protein kinases (MAPK8/JNK1, MAPK14/p38α, MAPK1/ERK2) and superoxide dismutase 2 (SOD2) and peroxiredoxin-1 (PRDX1). Antioxidant defenses-catalase (CAT), superoxide dismutases SOD1/SOD3, glutathione peroxidase-1 (GPX1), and sirtuin-3 (SIRT3)-were downregulated. RT-qPCR confirmed these trends. ELISA demonstrated higher MAPK8 and IL-6 and lower SIRT3 and GPX1 in hypertrophic LF (all p < 0.05). Biochemically, LSS tissue showed increased TBARS and GPx activity and decreased GSH versus controls; oxidative imbalance intensified with greater pain and higher body mass index. Selected miRNAs (e.g., hsa-miR-3163→MAPK8, hsa-miR-4291→SIRT3) were reduced. PPI networks were highly enriched (p < 1 × 10⁻¹⁶). Notably, MAPK8, SIRT3, GPX1, and IL-6 dysregulation was independent of pain category. LF in LSS exhibits a persistent ROS-driven, MAPK-amplified inflammatory program with mitochondrial vulnerability (SIRT3 loss) and impaired peroxide detoxification (GPX1 decline). This oxidative signature likely sustains fibrosis and LF thickening and nominates MAPK8-SIRT3-GPX1-IL-6 as candidate biomarkers and therapeutic targets.