Attenuation of cyclosporine A induced nephrotoxicity by schisandrin B through suppression of oxidative stress, apoptosis and autophagy.

Cyclosporine A (CsA) is a potent immunosuppressive agent whose clinical usage is limited by nephrotoxicity. Schisandrin B (SchB), isolated from the fruit of Schisandra chinensis, is a natural compound with multiple pharmacological activities that has been shown to attenuate organ injury caused by CsA. Hence, the primary objective of the current study was to evaluate whether SchB has a cytoprotective effect on CsA-induced nephrotoxicity in human proximal tubular epithelial cell line (HK-2). This study demonstrated that pre-incubation of HK-2 cells with 2.5-10.0μM SchB ameliorated CsA induced cytotoxicity caused by oxidative stress as evidenced by reduced levels of intracellular reactive oxygen species (ROS) and LDH release along with increased levels of mitochondrial membrane potential (ΔΨm) and glutathione (GSH). Also, it was demonstrated that nuclear factor erythroid 2-related factor 2 (Nrf2) activation was involved in modulating cellular oxidative stress, where SchB promoted Nrf2 translocation into the nucleus and downstream target gene expression of heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1) and Glutamate-cysteine ligase modifier subunit (GCLM). Additionally, SchB was found to enhance cell survival via reducing apoptosis rate as well as recover the CsA induced blockade of autophagic flux. Collectively, these findings demonstrated that SchB mediated alleviation of CsA induced nephrotoxicity by preventing the accumulation of ROS by way of suppressing oxidative stress, apoptosis and autophagy.