Epiregulin Mitigates Type 2 Diabetes-associated Cognitive Dysfunction by Inhibiting Hippocampal Neuronal Ferroptosis via the Nrf2 Pathway.

To investigate whether epiregulin (EREG) mitigates type 2 diabetes-associated cognitive dysfunction (T2DM-ACD) by inhibiting hippocampal ferroptosis via the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. T2DM mice received EREG or vehicle for 4 weeks. Cognitive function was assessed by Morris water maze. Hippocampal neuronal damage was evaluated by Nissl staining, and ferroptosis-related protein expression was assessed by immunofluorescence. Transcriptomic profiling was performed by RNA sequencing in HT22 cells under control, high-glucose, and EREG-treated conditions. HT22 hippocampal neurons were exposed to high glucose with or without EREG, and the Nrf2 inhibitor ML385 was added to verify pathway dependency. Mitochondrial ultrastructure was observed by transmission electron microscopy. Ferroptosis-related indices, including lipid reactive oxygen species (lipid ROS), malondialdehyde (MDA), glutathione (GSH), and intracellular ferrous iron (Fe2⁺) levels, were measured by flow cytometry and biochemical assays. The expression of Nrf2 pathway proteins, including Nrf2, solute carrier family 7 member 11 (SLC7A11), and GPX4, was analyzed by western blotting. In vivo, EREG ameliorated cognitive deficits and hippocampal neuronal damage in T2DM mice, restoring glutathione peroxidase 4 (GPX4) and suppressing cyclooxygenase-2 (COX2) expression. In vitro, EREG reversed high glucose-induced transcriptomic alterations, enriched antioxidant pathways, preserved mitochondrial integrity, reduced lipid ROS, MDA, and Fe2⁺ accumulation, and restored GSH levels. Mechanistically, EREG activated the Nrf2-SLC7A11-GPX4 signaling axis, and these effects were reversed by the Nrf2 inhibitor ML385. EREG protects against T2DM-ACD by inhibiting hippocampal ferroptosis in an Nrf2-dependent manner, representing a potential therapeutic candidate.