Redox-associated gene and microRNA signatures in degenerative intervertebral disc disease

Intervertebral disc degeneration (IVDD) is a major cause of chronic low back pain and disability worldwide. Growing evidence highlights oxidative stress as a key driver of disc degeneration; however, the integrated relationships between gene expression, regulatory microRNAs (miRNAs), and protein-level changes across disease stages remain insufficiently understood. This study aimed to identify oxidative stress-related molecular signatures in IVDD and to explore their miRNA-mediated regulation across degeneration grades. The study included 200 patients with lumbosacral IVDD undergoing microdiscectomy and 100 postmortem control samples without spinal pathology. Degeneration severity was classified using the Pfirrmann scale, and pain intensity was assessed with the Visual Analog Scale (VAS). Gene expression of oxidative stress markers was evaluated using RT-qPCR, while protein levels were quantified by ELISA. Additionally, bioinformatic prediction and RT-qPCR validation were used to analyze mRNA-miRNA interactions. Gene expression analysis revealed progressive downregulation of antioxidant genes CAT (FC ≈ -6.40) and GPX1 (FC ≈ -9.56), alongside upregulation of MAPK8 (FC ≈ 8.18) and IL6 (FC ≈ 8.18), with a moderate increase in NRF1 expression. These values reflect comparisons between advanced degeneration (G5) and controls. In contrast, protein analysis showed an inverse trend, with increasing levels of CAT, GPX1, and NRF1 and decreasing levels of MAPK8 and IL6 as degeneration progressed. miRNA profiling demonstrated significant dysregulation, including downregulation of miR-3163 and miR-196a-1-3p and upregulation of miR-665-3p and miR-4686. Correlation analysis indicated that molecular alterations were more strongly associated with structural degeneration than with pain intensity, as VAS-related differences were generally weak and non-significant. Overall, the results reveal a complex regulatory network in IVDD, characterized by discordant mRNA-protein expression and significant miRNA involvement. Oxidative stress and inflammatory pathways appear tightly regulated at transcriptional and post-transcriptional levels and are more closely linked to structural degeneration than clinical pain.