Grape Seed Procyanidin Extract Inhibited High Glucose and High Fat-Induced Ferroptosis through the Nrf2 Signaling Pathway in MIN6 Cells

Objective: Ferroptosis may be an important mechanism of high glucose and high fat-induced pancreatic β cell death. This study investigated the effect and mechanism of grape seed procyanidin extract (GSPE) on ferroptosis in pancreatic β cells induced by high glucose and high fat. Methods: An islet β cell injury model was established by treating MIN6 cells with 25 mmol/L glucose and 200 μmol/L sodium palmitate. Then, the cells were transfected with nuclear factor erythroid 2-related factor 2 small-interfering RNA (Nrf2 siRNA) and treated with 10, 20, 30, 40, 50, 75 and 100 mg/L GSPE. The cell activity was detected by the cell counting kit-8 (CCK8) assay, and the levels of intracellular glutathione (GSH), malonaldehyde (MDA) and reactive oxygen species (ROS) were detected by commercial kits. The protein expression of Nrf2, heme oxygenase-1 (HO-1), NADPH:quinone oxidoreductase-1 (NQO1), iron metabolism indicator transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), ferritin, solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4) and acyl-CoA synthetase long-chain family member 4 (ACSL4) were measured by Western blot. Results: Compared with the control group, high glucose and high fat caused intracellular iron deposition, up-regulated the protein expression levels of TfR1, DMT1 and ferritin, increased the levels of MDA, ROS and ACSL4, decreased the level of GSH and down-regulated the protein expression levels of GPX4 and SLC7A11. Intervention with GSPE could activate the Nrf2 signaling pathway to up-regulate GPX4 and SLC7A11 protein expression and increase the level of GSH. GSPE could also decrease the levels of MDA, ROS and ACSL4 and iron metabolism indices (TfR1, DMT1 and ferritin protein expression), thereby preventing ferroptosis in MIN6 cells induced by high glucose and high fat. After?inhibition of the Nrf2 signaling pathway?by?Nrf2-siRNA?transfection, the protective effect of GSPE was inhibited and the expression of the antioxidant enzymes HO-1, GPX4 and SLC7A11 was decreased. Conclusion: GSPE reduces ferroptosis induced by high glucose and high fat possibly by activating the Nrf2 signaling pathway and up-regulating antioxidant enzymes, consequently improving the cell viability of MIN6 cells.