Curculigoside alleviates ferroptosis in renal interstitial fibrosis by regulating the Nrf2/HO-1 signaling pathway

Renal interstitial fibrosis (RIF) represents the final pathway in most progressive renal diseases. Curculigoside (CCG), derived from Curculigo Pilosa, affects oxidative stress and inflammation. However, the effects of CCG on RIF remain unclear. This study explored the nephroprotective role of CCG in regulating oxidative stress through the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway.

Bioinformatic analysis was employed to identify the targets of CCG, elucidate the underlying pathways, and analyze molecular docking results. C57BL/6 mouse models of unilateral ureteral obstruction (UUO) were established to validate the results. Morphologic changes were assessed by pathologic examination, and the expression of proteins associated with renal ferroptosis and fibrosis was analyzed by western blotting. Additionally, the levels of glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and iron were measured.

In total, 3,532 differentially expressed genes (DEGs) were identified, comprising 2,290 upregulated and 1,242 downregulated genes. We retrieved 484 ferroptosis-related genes from the ferroptosis regulators (FerrDb) database, identifying 143 DEGs after intersecting with those from the Gene Expression Omnibus Series 217654 dataset (GSE217654). The key identified genes included nicotinamide adenine dinucleotide oxidase 4 (NOX4), activating transcription factor 3 (ATF3), mitogen-activated protein kinase 14 (MAPK14), tissue inhibitor metalloproteinase 1 (TIMP1), and early growth response 1 (EGR1). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that these genes were enriched in oxidative signaling pathways. The results exhibited the docking activity of CCG with related targets. CCG significantly alleviated histopathologic damage, reduced MDA and iron levels, and increased GSH and SOD levels. Protein analysis indicated that CCG alleviated fibrosis and enhanced the protein expression of antioxidants in UUO kidney tissues. CCG activated the Nrf2/HO-1 pathway and reduced UUO-induced ferroptosis.

CCG may improve renal fibrosis and mitigate ferroptosis by activating the Nrf2/HO-1 signaling pathway.