Characterization of ferroptosis in murine models of hemochromatosis

Abstract

Ferroptosis is a recently identified iron‐dependent form of nonapoptotic cell death implicated in brain, kidney, and heart pathology. However, the biological roles of iron and iron metabolism in ferroptosis remain poorly understood. Here, we studied the functional role of iron and iron metabolism in the pathogenesis of ferroptosis. We found that ferric citrate potently induces ferroptosis in murine primary hepatocytes and bone marrow–derived macrophages. Next, we screened for ferroptosis in mice fed a high‐iron diet and in mouse models of hereditary hemochromatosis with iron overload. We found that ferroptosis occurred in mice fed a high‐iron diet and in two knockout mouse lines that develop severe iron overload (Hjv–/– and Smad4Alb/Alb mice) but not in a third line that develops only mild iron overload (Hfe –/– mice). Moreover, we found that iron overload–induced liver damage was rescued by the ferroptosis inhibitor ferrostatin‐1. To identify the genes involved in iron‐induced ferroptosis, we performed microarray analyses of iron‐treated bone marrow–derived macrophages. Interestingly, solute carrier family 7, member 11 (Slc7a11), a known ferroptosis‐related gene, was significantly up‐regulated in iron‐treated cells compared with untreated cells. However, genetically deleting Slc7a11 expression was not sufficient to induce ferroptosis in mice. Next, we studied iron‐treated hepatocytes and bone marrow–derived macrophages isolated from Slc7a11–/– mice fed a high‐iron diet. Conclusion: We found that iron treatment induced ferroptosis in Slc7a11–/– cells, indicating that deleting Slc7a11 facilitates the onset of ferroptosis specifically under high‐iron conditions; these results provide compelling evidence that iron plays a key role in triggering Slc7a11‐mediated ferroptosis and suggest that ferroptosis may be a promising target for treating hemochromatosis‐related tissue damage. (Hepatology 2017;66:449–465).

Adipose‐Specific Lipin‐1 Overexpression Renders Hepatic Ferroptosis and Exacerbates Alcoholic Steatohepatitis in Mice

“…We hypothesized that greater accumulation of iron and altered iron distribution in the livers of ethanol‐fed Lpin1 ‐Tg mice might be involved in inducing ferroptosis, a form of iron‐dependent cell death. Hepatic ferroptosis was assessed by measuring three markers of ferroptosis: lipid peroxidation, GSH, and NADPH …”

“…Ferroptosis is an iron‐dependent form of oxidative programmed cell death featuring glutathione (GSH) depletion, detrimental glutathione peroxidase‐4 (GPX4) redox defense, disrupted glutamate antiporter xCT/SCL7A11 (system Xc ‐ ), and increased levels of lipid hydroperoxides . In recent years, ferroptosis has emerged as a central mediator of cell death, implicated in multiple pathological processes including ischemia/reperfusion‐induced kidney or liver damage, neurotoxicity, and neurodegenerative diseases …”

“…Ethanol‐induced hepatocellular injury is associated with excessive iron accumulation, changes in the level of GSH, generation of reactive oxygen species and local inflammation, all of which can cause structural and functional damage of the liver . Iron overload, GSH depletion, and the consequent lipid peroxidation and inflammation are considered the hallmarks of ferroptosis . Nonetheless, whether and how ferroptosis is involved in the pathogenic mechanisms of alcoholic steatohepatitis is presently unknown.…”

Transferrin as a predictor of survival in cirrhosis

“…Association studies cannot discern if altered serum iron parameters are a mere consequence or a driver of disease progression in patients with cirrhosis. Regardless of the exact hierarchy of events, excess iron will impair different immune effector functions and can induce ferropotosis—a recently identified form of programmed cell death triggered by iron . Toxic nontransferrin‐bound iron species increase when plasma transferrin concentration decreases and are specifically taken up by hepatocytes .…”

Ferroptosis: A Regulated Cell Death Nexus Linking Metabolism, Redox Biology, and Disease

“…These inhibitors are also protective in models of degenerative brain disorders, including Parkinson's, Huntington's, and Alzheimer's Diseases, as well as in other forms of neurodegeneration and traumatic and hemorrhagic brain injury (Chen et al, 2015; Do Van et al, 2016; Gascon et al, 2016; Guiney et al, 2017; Hambright et al, 2017; Li et al, 2017; Skouta et al, 2014; Zille et al, 2017). Ferroptosis in some other tissues and diseases has been examined, including liver hemochromatosis (Wang et al, 2017). A number of clinicopathological features of dementia are consistent with ferroptosis (Table 3).…”