Curcumin Alleviates Ochratoxin A-Induced Oxidative Injury in Porcine Kidney Epithelial Cells in Association with Restored Nrf2/NQO1/HO-1-Related Antioxidant Expression

Ochratoxin A (OTA) damages renal epithelial cells and disrupts redox homeostasis. We examined whether curcumin (Cur) reduces OTA-induced injury in porcine kidney epithelial PK-15 cells and whether protection accompanies changes in antioxidant expression. Preliminary concentration screening gave an OTA half-maximal inhibitory concentration (IC50) of 10.83 μg/mL. Cells received OTA (8 μg/mL), Cur (10 μmol/L), their combination, or control treatment. Cell viability, apoptosis, oxidant burden, mitochondrial membrane potential, and biochemical markers were assessed alongside quantitative reverse-transcription PCR (qRT-PCR) and Western blotting. A previously published RNA-sequencing dataset was reanalyzed to examine redox-related responses. OTA reduced viability and mitochondrial membrane potential, increased apoptosis, and impaired antioxidant defenses. Cur attenuated these changes, lowered oxidant-associated fluorescence, malondialdehyde, and lactate dehydrogenase release, and improved glutathione status. The shared RNA-sequencing dataset contained 11,707 differentially expressed genes in OTA versus control and 498 in OTA+Cur versus OTA, with 380 genes common to both comparisons. Targeted assays showed higher Nrf2, NQO1, and HO-1 mRNA and total-protein abundance with Cur than with OTA alone. These results associate Cur-mediated protection with recovery of antioxidant expression in PK-15 cells. They do not establish Nrf2 activation or a causal requirement for this pathway.