Identification of Cervical Disc Degeneration and Genes Associated with Immune Infiltration

Abstract Objective: This study aims to identify new diagnostic genetic-biomarkers for early-stage cervical intervertebral disc degeneration (IDD) and analyze the potential association between key genes and infiltrating immune cells. Methods: Cervical disc specimens were collected from anterior cervical discectomy and fusion surgery, which were classified into IDD and controlled group depending on MRI disc degeneration grade. mRNA expression profile data was downloaded from the GEO database. Differentially expressed genes (DEGs) were determined from GEO database profile. Gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis were performed on DEGs. LASSO regression model and Support Vector Machine Recursive Feature Elimination (SVM-RFE) algorithm were employed to screen for potential biomarkers. The composition of 22 immune cell fractions in IDD patients was analyzed using CIBERSORT. Biomarker expression levels in cervical disc specimens were detected through quantitative PCR. Result: 71 DEGs were found, including 50 genes up-regulated and 21 genes down-regulated. KEGG pathway analysis revealed significant enrichment of inflammation-related pathways. Based on the results of two machine learning screening methods and validation in cervical disc specimens, CDKN3, SLC22A4, and SYDE1 were identified as key biomarkers for cervical IDD. Immune cell infiltration analysis showed significant differences, with higher rate of M0 macrophage and mast cell activation ( P =0.004, P =0.004), and lower rate of T-cell CD8 and NK cell activation ( P =0.045, P =0.024). Conclusion: CDKN3, SLC22A4 and SYD1 are associated with the occurrence and progression of cervical IDD through the regulation of certain immune cells. Therefore, they have the potential to be the biomarkers for the diagnosis of cervical IDD and play a role in monitoring the progression of cervical IDD.