Mitochondrial Iron Overload-Mediated Inhibition of Nrf2-HO-1/GPX4 Assisted ALI-Induced Nephrotoxicity

Abstract

Aristolactam I (ALI) is an active component derived from some Traditional Chinese medicines (TCMs), and also the important metabolite of aristolochic acid. Long-term administration of medicine-containing ALI was reported to be related to aristolochic acid nephropathy (AAN), which was attributed to ALI-induced nephrotoxicity. However, the toxic mechanism of action involved is still unclear. Recently, pathogenic ferroptosis mediated lipid peroxidation was demonstrated to cause kidney injury. Therefore, this study explored the role of ferroptosis induced by mitochondrial iron overload in ALI-induced nephrotoxicity, aiming to identify the possible toxic mechanism of ALI-induced chronic nephropathy. Our results showed that ALI inhibited HK-2 cell activity in a dose-dependent manner and significantly suppressed glutathione (GSH) levels, accompanying by significant increases in intracellular 4-hydroxynonenal (4-HNE) and intracellular iron ions. Moreover, the ALI-mediated cytotoxicity could be reversed by deferoxamine mesylate (DFO). Compared with other inhibitors, Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, obviously alleviated ALI-induced cytotoxicity. Furthermore, we have shown that ALI could remarkably increase the levels of superoxide anion and ferrous ions in mitochondria, and induce mitochondrial damage and condensed mitochondrial membrane density, the morphological characteristics of ferroptosis, all of which could be reversed by DFO. Interestingly, ALI dose-dependently inhibited these protein contents of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and glutathione peroxidase 4 (GPX4), which could be partly rescued by Tin-protoporphyrin IX (SnPP) and mitoTEMPO co-treatment. In conclusion, our results demonstrated that mitochondrial iron overload-mediated antioxidant system inhibition would assist ALI-induced ferroptosis in renal tubular epithelial cells, and Nrf2-HO-1/GPX4 antioxidative system could be an important intervention target to prevent medicine containing ALI-induced nephropathy.

Zinc attenuates ferroptosis and promotes functional recovery in contusion spinal cord injury by activating Nrf2/GPX4 defense pathway

“…A large number of blood cells and hemoglobin are destroyed and degraded, resulting in a sharp increase in the level of iron ions in the injured area. Additionally, the tissue at the injured site is necrotic and produces many reactive oxygen species and oxidative stress products 7‐10 . The content of saturated fatty acids is very high.…”

“…Our previous study showed that zinc can regulate NRF2/HO‐1 to a certain extent. This pathway can have a role in the accumulation of oxidative stress products and reactive oxygen species 10,16,17 …”

“…Studies indicate that nuclear factor E2 (NRF2) is one of the most critical factors in regulating the antioxidant response. The GPX4 gene is among the genes regulated by NRF2 10,18–21 . Therefore, GPX4 is also crucial to the regulation of ferroptosis 22 .…”

“…Additionally, the tissue at the injured site is necrotic and produces many reactive oxygen species and oxidative stress products. 7 , 8 , 9 , 10 The content of saturated fatty acids is very high. Finally, due to iron and lipid supersaturation, the production of lipid peroxides suddenly increases, and iron catalyzes enzyme‐mediated programmed cell death.…”

“…This pathway can have a role in the accumulation of oxidative stress products and reactive oxygen species. 10 , 16 , 17 …”