Identification of core genes and natural immune cells in diabetic retinopathy by integrated bioinformatics analysis

Diabetic retinopathy (DR) is the most frequently occurring complication of diabetes mellitus and remains a leading cause of vision loss globally. The target of this study was to investigate the changes in immune cell infiltration and core gene expression associated with the progression of DR. Integrated bioinformatics analysis was performed using R software to handle microarray data from gene expression omnibus datasets. In the study, a total of 22 types of both adaptive and innate immune infiltrate cells were evaluated for their association with DR. Our results indicated that specific immune infiltrate cells have close connections with DR, such as monocytes, macrophages M1, activated mast cells, and neutrophils. Furthermore, a total of 66 differentially expressed genes (DEGs) were identified using the limma package. Gene set enrichment analysis (GSEA) demonstrated that the "Citrate cycle (TCA cycle)," "Oxidative Phosphorylation" and "Purine metabolism" pathways were significantly enriched in DR. Gene Ontology (GO) annotations of DEGs mostly included "Cofactor binding," "Coenzyme binding" and "Oxidoreductase activity." Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that DEGs were enriched in "Carbon metabolism," "Oxidative phosphorylation" and "Butanoate metabolism." Protein-protein interaction (PPI) network analysis showed that OTC, ACSM3, PDPR, and MARS2 were vital genes associated with DR progression. These results indicate that a host of core genes and immune cells possibly play an important role in DR progression.