Secondary iron overload induces chronic pancreatitis and ferroptosis of acinar cells in mice

Disruption of iron homeostasis is associated with multiple diseases. It has been found that patients with genetic iron overload develop massive iron deposition in the pancreas. However, few studies have focused on the effect of secondary iron overload on the pancreas. The objective of the present study was to investigate the pathogenic consequences of secondary iron overload in mice. An iron overload mouse model was constructed by intraperitoneal injection of 120 mg/kg body weight of iron dextran every other week for 12 weeks. Iron deposition, immunocyte infiltration, fibrosis, oxidative stress and ferroptosis were assessed using Prussian blue staining, immunohistochemical analysis, Masson staining, Sirius red staining, RT-qPCR analysis and western blot analysis. It was found that iron-overloaded mice showed pancreatic iron overload, together with elevated gene expression of the iron storage factor ferritin H, and decreased expression of the iron transportation mediator divalent metal transporter 1, ferroportin 1 and transferrin receptor. Iron-overloaded mice developed mild pancreatitis with increased serum amylase and lipase activities, as well as elevated gene expression levels of pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6 and inducible nitric oxide synthase. Acinar atrophy, massive immunocyte infiltration and pancreatic fibrosis were noted in the iron-overloaded mice. As an underlying mechanism, iron-overloaded mice showed increased pancreatic oxidative stress, with an elevated malondialdehyde level, and decreased SOD and glutathione peroxidase activity. Furthermore, iron overload led to ferroptosis with promoted expression of cytochrome c oxidase subunit II, and decreased transcripts of glutathione peroxidase 4 and solute carrier family 7 member 11. These results provided evidence that multiple intraperitoneal injections of iron dextran in mice lead to iron overload-induced chronic pancreatitis, which suggested that secondary iron overload is a risk factor for pancreatitis and highlights the importance of iron in maintaining the normal functions of the pancreas.