CPPED1 Links Neutrophil Extracellular Traps to Diabetic Nephropathy: Bioinformatics-Driven Expression Validation

Diabetic nephropathy (DN) begins with diabetes-related disruptions in glucose metabolism, with oxidative stress playing a crucial role. Neutrophil extracellular traps (NETs) are extensive web-like formations composed of cytosolic and granule proteins, which are dependent on oxidative stress for their formation and function. This study aimed to identify potential targets for DN progression, focusing on NETs, using bioinformatic analysis and quantitative Real-Time PCR(qRT-PCR) . We performed differential gene expression (DEG) analysis on two DN-related RNA-seq datasets (GSE142025 and GSE163603) and NETs-related genes. Subsequent analysis included gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), GeneMANIA, and receiver operating characteristic (ROC) curves. Immune cell infiltration levels were assessed via single-sample GSEA, and a regulatory network involving RNA-binding proteins (RBPs) and their associated target mRNA was constructed. qRT-PCR was conducted on high glucose (HG)-treated and control HK-2 cells. Our analysis identified a set of 22 hub genes through the intersection of differentially expressed genes (DEGs) with NETs-related genes. Immune infiltration assessments revealed significant differences across 23 immune cell types among the analyzed groups. Hub genes including calcineurin-like phosphoesterase domain-containing 1 (CPPED1) showed high diagnostic values (AUC over 0.6). qRT-PCR indicated reduced gene expression levels. In summary, this study identified 22 significantly upregulated DEGs that play a vital role in DN by using gene expression omnibus (GEO) database, GSEA, GSVA, immune infiltration analysis and ROC. The expression levels of CPPED1 may serve as novel diagnostic biomarkers and therapeutic targets.