Identification of AHR, UACA, GCLM, and GSTZ1 as candidate genes associated with metabolic alterations in intervertebral disc degeneration

Abstract

Intervertebral disc degeneration (IVDD) is the leading pathological cause of chronic low back pain, but reliable molecular indicators for grading degeneration severity remain scarce. The interplay between metabolic reprogramming (MR) and the immune microenvironment in IVDD pathogenesis remains poorly characterized. Here, we integrated bioinformatic analyses and experimental validation to investigate MR-related molecular alterations and immune microenvironment changes in IVDD. From the GSE70362 dataset, we identified 553 differentially expressed genes (DEGs), of which 65 were classified as MR-related DEGs by intersection analysis. Weighted gene co-expression network analysis (WGCNA) identified a gene module significantly correlated with IVDD severity. Combining LASSO-penalized regression and random forest algorithms, we selected four core candidate genes associated with IVDD severity: AHR , UACA , GCLM , and GSTZ1 . A nomogram based on these genes showed strong discriminative performance for degeneration severity (apparent AUC = 0.907); nested cross-validation and bootstrap optimism correction confirmed reliable generalizability (corrected AUC = 0.787), and partial external validation was achieved in the independent GSE176205 RNA-seq cohort. Metabolic reprogramming scores were significantly higher in the severe disc degeneration (SDD) group than in the mild-to-moderate disc degeneration (MDD) group, and correlated with enrichment of extracellular matrix metabolism and antioxidant response pathways, as well as suppression of oxidative phosphorylation. Single-cell transcriptomic analysis, with manual marker validation and patient-level pseudobulk statistics, revealed altered immune and stromal cell proportions in degenerative discs; core gene expression patterns in nucleus pulposus cells were consistent with bulk transcriptome findings. We constructed a miRNA–transcription factor–mRNA regulatory network and validated core gene dysregulation via RT-qPCR in primary human nucleus pulposus cells. In conclusion, these four genes are associated with metabolic reprogramming and immune microenvironment alterations in nucleus pulposus cells, providing candidate molecular indicators for IVDD severity assessment and insights for future mechanistic studies.