Role of ferroptosis induced by a high concentration of calcium oxalate in the formation and development of urolithiasis

Ferroptosis is an iron-dependent lipid peroxidation process. Although the involvement of ferroptosis in kidney diseases has recently been reported, the association between ferroptosis and urolithiasis remains unclear. The present study examined the effects of ferroptosis on calcium oxalate (CaOx) crystal-induced renal tubular epithelial cell injury in vivo and in vitro. First, renal tubular epithelial cells were exposed to various concentrations of CaOx. By measuring cell viability, Fe(2+) levels, lipid peroxidation levels and the levels of ferroptosis-related proteins, it was identified that the relative expression of the ferroptosis agonist proteins, p53, long-chain acyl-CoA synthetases (ACSL4), transferrin (TF) and trans-ferrin receptor (TRC), increased, while the relative expression of the ferroptosis inhibitory proteins, solute carrier family 7 member 11 (SLC7A11, XCT) and glutathione peroxidase 4 (GPX4), decreased significantly. Furthermore, the levels of Fe(2+) and lipid peroxidation gradually increased, while cell viability significantly decreased. From these results, it was noted that the extent of CaOx-induced ferroptosis activation and cell injury was dependent on the CaOx concentration. To further investigate the association between ferroptosis and renal tubular epithelial cell injury, the ferroptosis agonist, erastin, and the ferroptosis inhibitor, ferrostatin-1, were used to regulate the degree of ferroptosis at the same CaOx concen-tration in in vivo and in vitro experiments. CaOx-induced ferroptosis and damage to renal tubular epithelial cells and renal tissue were investigated. Finally, it was identified that through the regulation of ferroptosis levels, renal tubular epithelial cell injury increased significantly when the ferrop-tosis level increased, and vice versa. On the whole, the present results indicated that ferroptosis is essential for renal tubular epithelial cell injury induced by CaOx crystals. This finding is highly significant and promotes the further investigation of the association between ferroptosis and urolithiasis.