Cyclosporine nephrotoxicity: Attenuation by an antioxidant-inhibitor of lipid peroxidation in vitro and in vivo

The exact mechanism by which cyclosporine (CsA) causes renal injury is not known. The possibility that reactive oxygen species (ROS) may play a role, since CsA induces renal microsomal lipid peroxidation and reduces glutathione levels, was investigated by examining whether administration of an antioxidant attenuates CsA-induced nephrotoxicity. One of three groups of uninephrectomized rats received vehicles, another CsA 25 mg/kg/day and the third, CsA plus antioxidant lazaroid (U-74389 G) 20 mg/kg/day, for 8 weeks. CsA-induced functional and structural derangements were accompanied by a significant induction of renal cortical lipid peroxidation (thiobarbitu-ric acid reactive substances and conjugated diene). Administration of lazaroid significantly suppressed CsA-induced lipid peroxidation and provided significant functional and structural protection. That lazaroid affords renal functional protection against CsA in the rat was again demonstrable in a crossover study. To examine the relation between CsA nephrotoxicity and lipid peroxidation, cell culture studies were undertaken. CsA induced renal epithelial (LLC-PKj) cell injury (LDH release) as well as lipid peroxidation and degradation (prelabeled 8H arachidonic acid release). Lazaroid prevented CsA-induced cell injury and limited lipid alterations. These new findings—that an antioxidant inhibitor of lipid peroxidation limits CsA-induced renal toxicity in vitro and in vivo—suggest a pathogenic role for ROS-mediated lipid peroxidation in CsA-induced renal toxicity. Antioxidant therapy may minimize CsA-induced renal toxicity in humans.