Leonurine Ameliorates Diabetic Nephropathy through GPX4-Mediated Ferroptosis of Endothelial Cells

Background: Diabetic nephropathy (DN) is a common microvascular complication of diabetes mellitus (DM). Ferroptosis is an atypical form of iron-dependent, modulated cell death that has been shown to occur in human umbilical vein endothelial cells (HUVECs). Leonurine (LEO) is a single active ingredient extracted from Leonurus japonicus Houtt. It has various biological activities, including anti-inflammatory and anti-cancer effects. However, whether LEO affects ferroptosis in DN has yet to be investigated. Methods: An animal model of DN was established by subjecting C57/BL6 mice to a high-fat diet (HFD) while being induced with Streptozotocin (STZ). A cellular model of DN was established by exposing HUVECs to a high glucose (HG) concentration of 30 mM. Results: LEO was found to improve DN and to attenuate the degree of glomerulosclerosis and tubular atrophy in the mouse model. Additionally, it markedly decreased the levels of ferroptosis markers. Molecular analyses revealed that LEO inhibited HG-induced oxidative stress in HUVECs, thereby decreasing endothelial cell (EC) dysfunction. Furthermore, LEO was found to reduce ferroptosis and reverse EC dysfunction by increasing the expression of glutathione peroxidase 4 (GPX4) and nuclear factor erythroid 2-related factor 2 (Nrf2). The suppression of Nrf2 in HG-induced HUVECs inhibited LEO-GPX4 axis-mediated ferroptosis and increased EC dysfunction. Conclusions: LEO exerts anti-DN effects both in vivo and in vitro by suppressing GPX4-mediated EC ferroptosis. Mechanistically, LEO appears to induce Nrf2-mediated GPX4 expression to inhibit ferroptosis, thereby reducing EC dysfunction. This study provides a new perspective on the treatment of diseases using natural medicines. It involves a novel form of cell death that could potentially lead to better treatment of DN.