Renal transporter OAT1 and PPAR-alpha pathway co-contribute to icaritin-induced nephrotoxicity

This study aimed to investigate the potential nephrotoxicity of icaritin arid the underlying mechanism by in vitro-in vivo experiment technology combined with proteomics technology. First, icaritin showed a significant cytotoxic effect on HK-2 cells, which was accompanied by increased LDH and TNF-alpha in the supernatant, decreased protein expressions of Bcl-2 and increased Bax and enhanced apoptosis of HK-2 cells as measured by TUNEL staining. Moreover, icaritin induced obvious tubular damage and up-regulation of BUN and CRE levels in plasma in mice. Second, intracellular uptake of icaritin was considerably higher in hOAT1-HEK293 cells than in mockHEK293 cells, suggesting that icaritin might accumulate in renal cells via OAT1 uptake. Importantly, icaritin caused significant changes in the PPAR signaling pathway in HK2 cells through proteomic analysis. Then, in vitro and in vivo results verified that icaritin significantly downregulated the protein expression of PPAR-alpha as well as downregulated APOB, ACSL3, ACSL4, and upregulated 5/12/15-HETE, implying that a lipid metabolism disorder was involved in the icaritin-induced nephrotoxicity. Finally, icaritin was found to increase the accumulation of iron and LPO levels while reducing the activity of GPX4, suggesting that ferroptosis was involved in the nephrotoxicity induced by icaritin.