Cilastatin Preconditioning Attenuates Renal Ischemia-Reperfusion Injury via Hypoxia Inducible Factor-1 alpha Activation

Abstract

Cilastatin is a specific inhibitor of renal dehydrodipeptidase-1. We investigated whether cilastatin preconditioning attenuates renal ischemia-reperfusion (IR) injury via hypoxia inducible factor-1 alpha (HIF-1 alpha) activation. Human proximal tubular cell line (HK-2) was exposed to ischemia, and male C57BL/6 mice were subjected to bilateral kidney ischemia and reperfusion. The effects of cilastatin preconditioning were investigated both in vitro and in vivo. In HK-2 cells, cilastatin upregulated HIF-1 alpha expression in a time- and dose-dependent manner. Cilastatin enhanced HIF-1 alpha translation via the phosphorylation of Akt and mTOR was followed by the upregulation of erythropoietin (EPO) and vascular endothelial growth factor (VEGF). Cilastatin did not affect the expressions of PHD and VHL. However, HIF-1 alpha ubiquitination was significantly decreased after cilastatin treatment. Cilastatin prevented the IR-induced cell death. These cilastatin effects were reversed by co-treatment of HIF-1 alpha inhibitor or HIF-1 alpha small interfering RNA. Similarly, HIF-1 alpha expression and its upstream and downstream signaling were significantly enhanced in cilastatin-treated kidney. In mouse kidney with IR injury, cilastatin treatment decreased HIF-1 alpha ubiquitination independent of PHD and VHL expression. Serum creatinine level and tubular necrosis, and apoptosis were reduced in cilastatin-treated kidney with IR injury, and co-treatment of cilastatin with an HIF-1 alpha inhibitor reversed these effects. Thus, cilastatin preconditioning attenuated renal IR injury via HIF-1 alpha activation.