Spermine Guards Diabetic Cardiomyocytes against Ferroptosis by Inhibiting TXNIP

Abstract

Background: Ferroptosis is a novel form of nonapoptotic regulatory cell death that is involved in the pathogenesis of diabetic complications, including diabetic cardiomyopathy (DCM). Recent studies have shown that spermine (SPM) may have a protective effect against hyperglycemia in mammals. However, it is still unclear whether SPM can negatively regulate ferroptosis in diabetic mice. Methods: We investigated the effects of SPM on ferroptosis in diabetic mice induced by streptozotocin (STZ) in vivo, as well as its impact on high glucose (HG)-stimulated HL-1 cardiomyocytes injury in vitro. We used various methods to evaluate cardiomyocyte ferroptosis injury and the effects of SPM, including echocardiographic analysis, electron microscopy, serum-related markers, immunohistochemistry, immunofluorescence, and immunoblotting. We also explored the effect of thioredoxin-interacting protein (TXNIP) on SPM in regulating the ferroptosis in HG-induced HL-1 cells through TXNIP siRNA transfection. Results: Mice induced with STZ showed a significant increase in blood glucose, food, and water intake (p < 0.05), but decreased body weight and weakened cardiac function (p < 0.05). The level changes of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), iron (Fe²⁺), lipid reactive oxygen species (ROS) production as well as the expression of ferroptosis marker proteins (acyl-CoA synthetase long-chain family 4 (ACSL4), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11)) and redox-related protein (TXNIP, nuclear factor erythroid 2-related factor 2 (NRF2), and heme oxygenase 1 (HO-1)) verified that diabetes or HG level aggravated lipid peroxidation, iron overloading and oxidative damage, thereby leading to ferroptosis in cardiomyocytes (p < 0.05). However, SPM treatment or interference with TXNIP expression significantly ameliorated cardiac injury in DCM mice caused by ferroptosis and HG-induced injury in cardiomyocytes. Conclusions: In general, these findings suggest that SPM can be used to prevent DCM by inhibiting the TXNIP-ferroptosis signaling loop. This treatment strategy is brand-new and potentially effective for DCM.