Integrative bioinformatic discovery and in vivo validation of immune-related hub genes in renal interstitial fibrosis.

Nearly all progressive renal disorders emerge through the renal interstitial fibrosis (RIF) pathway, yet its underlying mechanisms remain unclear. This study employed bioinformatics approaches to identify crucial targets and immune-infiltrating patterns in RIF. By screening the microarray datasets GSE22459 and GSE76882, we identified 163 and 418 differentially expressed genes (DEGs), respectively, with 80 core genes in common between RIF and healthy specimens. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) network analyses identified five hub genes-G protein-coupled receptor 18 (GPR18), chemokine ligand 5 (CCL5), chemokine receptor type 5 (CCR5), chemokine ligand 19 (CCL19), and Chemokine (C-X-C motif) ligand 9 (CXCL9). These were clustered into a functional group related to chemokine signaling, lymphocyte activation modulation, and leukocyte activation modulation. Immune cell infiltration analysis further revealed that the enrichment levels of 13 immune cell subtypes were significantly different in RIF samples, with Th1 cell enrichment being notably downregulated. To validate these computational findings, a unilateral ureteral obstruction (UUO)-induced renal fibrosis model was established in mice. Immunohistochemical (IHC) staining revealed that in UUO-induced mouse kidneys, the protein levels of GPR18, CCL5, CCR5, CCL19, and CXCL9 were remarkably elevated compared with the normal control. These results confirm the potential of these 5 hub genes as therapeutic targets in RIF. This study helps reveal the underlying mechanisms of RIF.