5-Lipoxygenase Inhibition Ameliorates Diabetic Kidney Disease by Attenuating Renal Tubular Epithelial Cell Ferroptosis

Background: The enzyme 5-lipoxygenase plays a pivotal role in the conversion of arachidonic acid into 5-hydroperoxyeicosatetraenoic acid (5-HPETE), which is a key source of lipid peroxides and leukotrienes. This study aims to elucidate the pathophysiological implications of 5-lipoxygenase in diabetic kidney disease (DKD), focusing on its impacts on lipid peroxidation and tubular cell ferroptosis. Methods: HKC-8 cells, a human-derived renal proximal tubular cell line, was used to perform in vitro experiments. Diabetes induction in male C57BL/6J mice was achieved through streptozotocin injection. Zileuton was used to inhibit 5-lipoxygenase activity. Results: Hyperglycemic stimuli upregulated the expression of 5-lipoxygenase both in HKC-8 cells. The overexpression of 5-lipoxygenase aggravated hyperglycemia-induced increases in the expression of profibrotic cytokines and reactive oxygen species (ROS) production, while its suppression mitigated these detrimental effects. High glucose also led to downregulations of glutathione peroxidase 4 (GPX4) and upregulations of Acyl-CoA synthetase long chain family member 4 (ACSL4), ferritin heavy chain 1 (FTH-1), and malondialdehyde (MDA), indicating the activation of pro-ferroptotic pathways. The overexpression of 5-lipoxygenase exaggerated hyperglycemia-induced ferroptotic cell death, which is attenuated by the inhibition of 5-lipoxygenase or ferrostatin-1 treatment . Additionally, streptozotocin-induced diabetic mice exhibited worse kidney function and interstitial fibrosis in association with decreased GPX4 and increased ACSL4 and FTH-1 levels compared to normoglycemic mice. Zileuton administration significantly ameliorated these hyperglycemia-induced kidney dysfunction and ferroptosis activation. Conclusion: These findings demonstrate the central role of 5-lipoxygenase in intracellular lipid peroxidation and subsequent tubular cell ferroptosis under sustained hyperglycemic conditions. Inhibition of 5-lipoxygenase not only mitigates ferroptotic tubular cell death but also alleviates hyperglycemia-induced renal dysfunction. This suggests that 5-lipoxygenase could serve as a potential therapeutic target for the treatment of DKD.