Hepcidin, a candidate modifier of the hemochromatosis phenotype in mice

Blood ◽  
2004 ◽  
Vol 103 (7) ◽  
pp. 2841-2843 ◽  
Author(s):  
Gaël Nicolas ◽  
Nancy C. Andrews ◽  
Axel Kahn ◽  
Sophie Vaulont
Keyword(s):  
Iron Overload ◽  
Iron Metabolism ◽  
Genetic Modifier ◽  
Hereditary Hemochromatosis ◽  
Iron Accumulation ◽  
Hfe Gene ◽  
Type I ◽  
Regulatory Peptide ◽  
Liver Iron ◽  
Very High

Abstract Hereditary hemochromatosis (HH) type I is a disorder of iron metabolism caused by a mutation in the HFE gene. Whereas the prevalence of the mutation is very high, its penetrance seems very low. The goal of our study was to determine whether hepcidin, a recently identified iron-regulatory peptide, could be a genetic modifier contributing to the HH phenotype. In mice, deficiency of either HFE (Hfe-/-) or hepcidin (Usf2-/-) is associated with the same pattern of iron overload observed in patients with HH. We intercrossed Hfe-/- and Usf2+/- mice and asked whether hepcidin deficiency increased the iron burden in Hfe-/- mice. Our results showed that, indeed, liver iron accumulation was greater in the Hfe-/-Usf2+/- mice than in mice lacking Hfe alone. This result, in agreement with recent findings in humans, provides a genetic explanation for some variability of the HH phenotype. (Blood. 2004;103: 2841-2843)

Hfe Acts in Hepatocytes To Prevent Hemochromatosis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 703-703
Author(s):  
Martina U. Muckenthaler ◽  
Maja Vujic-Spasic ◽  
Judit Kiss ◽  
Thomas Herrmann ◽  
Bruno Galy ◽  
...  
Keyword(s):  
Iron Overload ◽  
Hereditary Hemochromatosis ◽  
Hfe Gene ◽  
Hepatic Iron ◽  
Type I ◽  
Cell Type ◽  
Severe Liver ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Hepatic Iron Overload

Abstract Hereditary hemochromatosis (HH) is a prevalent, potentially fatal disorder hallmarked by intestinal iron hyperabsorption, hyperferremia and hepatic iron overload. In both humans and mice, type I HH is associated with mutations in the ubiquitously expressed HFE/Hfe gene. To understand the molecular mechanism(s) underlying HH and to identify the cell type in which Hfe acts to prevent HH we generated mice with tissue-specific Hfe ablations. We demonstrate that hepatocyte-specific Hfe deficiency fully recapitulates the phenotype observed in Hfe−/− mice with severe liver iron accumulation, reduced splenic iron content, increased Tf saturation, hyperferremia and reduced hepcidin expression. These findings unambiguously and directly show that Hfe acts in hepatocytes to prevent hemochromatosis.

scholarly journals Discrepancy between Serum Ferritin and Liver Iron Concentration in a Patient with Hereditary Hemochromatosis – The Value of T2* MRI

2020 ◽  
Vol 13 (2) ◽  
pp. 712-715
Author(s):  
Mustafa A. Al-Tikrity ◽  
Mohamed A. Yassin
Keyword(s):  
Iron Overload ◽  
Serum Ferritin ◽  
Ferritin Level ◽  
Hereditary Hemochromatosis ◽  
Iron Concentration ◽  
Hfe Gene ◽  
Liver Iron Concentration ◽  
C282y Mutation ◽  
Liver Iron ◽  
T2 Mri

Primary hemochromatosis is an inherited disorder, and the homeostatic iron regulator (HFE) gene C282Y mutation is a common cause of hemochromatosis in Europe. We are reporting a case of a 56-year-old female known to have hemochromatosis with the HFE gene C282Y mutation with a serum ferritin level of 482 μg/L who underwent heart and liver T2* MRI which showed no evidence of iron overload – neither in the heart nor in the liver. This indicates that there is a discrepancy between serum ferritin and liver iron concentration by MRI and the superiority of T2* MRI in diagnosis and follow-up of iron overload in patients with hereditary hemochromatosis.

scholarly journals Hemochromatosis: one form of iron-overload diseases

2013 ◽  
Vol 154 (29) ◽  
pp. 1156-1164 ◽  
Author(s):  
Ferenc Szalay
Keyword(s):  
Iron Overload ◽  
Iron Metabolism ◽  
Clinical Symptoms ◽  
Fetal Liver ◽  
Hereditary Hemochromatosis ◽  
Gene Mutations ◽  
Organ Injury ◽  
Beta Thalassemia ◽  
Hfe Gene ◽  
Kinase Gene

Iron-overload diseases are typically insidious, causing progressive and irreversible organ injury before clinical symptoms develop. Some iron-overload diseases as HFE-associated hemochromatosis and beta-thalassemia are quite common, whereas others are very rare. Early diagnosis is important since iron toxicity can be attenuated or prevented. Significant progress of our knowledge on iron metabolism developed in the past years. We learned a lot about HFE gene mutations, function of ferroportin and hepcidin, the hypoferremia hormone produced by the liver. However, many questions are still open. Special forms of localized iron overload are the Hallervorden-Spatz syndrome and pantothenate kinase gene mutation associated neurodegeneration causing progressive extrapyramidal movement disorders. Neonatal hemochromatosis is a severe systemic iron-overload disorder due to gestational alloimmune liver disease caused by transplacental maternal IgG directed against the fetal liver. This review article gives an overview on iron metabolism and iron-overload disease. Pathomechanism, diagnosis and treatment of hereditary hemochromatosis are discussed. Orv. Hetil., 2013, 154, 1156–1164.

scholarly journals Contributions of β2-microglobulin–dependent molecules and lymphocytes to iron regulation: insights from HfeRag1-/- and β2mRag1-/- double knock-out mice

Blood ◽  
2004 ◽  
Vol 103 (7) ◽  
pp. 2847-2849 ◽  
Author(s):  
Carlos J. Miranda ◽  
Hortence Makui ◽  
Nancy C. Andrews ◽  
Manuela M. Santos
Keyword(s):  
Iron Overload ◽  
Hereditary Hemochromatosis ◽  
Protein S ◽  
Iron Accumulation ◽  
Iron Regulation ◽  
Hfe Gene ◽  
Knock Out ◽  
Β2 Microglobulin ◽  
Knock Out Mice ◽  
Deficient Mice

Abstract Genetic causes of hereditary hemochromatosis (HH) include mutations in the HFE gene, coding for a β2-microglobulin (β2m)-associated major histocompatibility complex class I-like protein. However, iron accumulation in patients with HH can be highly variable. Previously, analysis of β2mRag1-/- double-deficient mice, lacking all β2m-dependent molecules and lymphocytes, demonstrated increased iron accumulation in the pancreas and heart compared with β2m single knock-out mice. To evaluate whether the observed phenotype in β2mRag1-/- mice was due solely to the absence of Hfe or to other β2m-dependent molecules, we generated HfeRag1-/- double-deficient mice. Our studies revealed that introduction of Rag1 deficiency in Hfe knock-out mice leads to heightened iron overload, mainly in the liver, whereas the heart and pancreas are relatively spared compared with β2mRag1-/- mice. These results suggest that other β2m-interacting protein(s) may be involved in iron regulation and that in the absence of functional Hfe molecules lymphocyte numbers may influence iron overload severity. (Blood. 2004;103: 2847-2849)

scholarly journals Disorders of iron metabolism. Part II: iron deficiency and iron overload

2010 ◽  
Vol 64 (4) ◽  
pp. 287-296 ◽  
Author(s):  
Manuel Muñoz ◽  
José Antonio García-Erce ◽  
Ángel Francisco Remacha
Keyword(s):  
Iron Deficiency ◽  
Iron Overload ◽  
Iron Metabolism ◽  
Laboratory Tests ◽  
Parenchymal Cell ◽  
Transferrin Saturation ◽  
The Body ◽  
Hfe Gene ◽  
Type I ◽  
Iron Deficient

Main disorders of iron metabolismIncreased iron requirements, limited external supply, and increased blood loss may lead to iron deficiency (ID) and iron deficiency anaemia. In chronic inflammation, the excess of hepcidin decreases iron absorption and prevents iron recycling, resulting in hypoferraemia and iron restricted erythropoiesis, despite normal iron stores (functional iron deficiency), and finally anaemia of chronic disease (ACD), which can evolve to ACD plus true ID (ACD+ID). In contrast, low hepcidin expression may lead to hereditary haemochromatosis (HH type I, mutations of the HFE gene) and type II (mutations of the hemojuvelin and hepcidin genes). Mutations of transferrin receptor 2 lead to HH type III, whereas those of the ferroportin gene lead to HH type IV. All these syndromes are characterised by iron overload. As transferrin becomes saturated in iron overload states, non-transferrin bound iron appears. Part of this iron is highly reactive (labile plasma iron), inducing free radical formation. Free radicals are responsible for the parenchymal cell injury associated with iron overload syndromes.Role of laboratory testing in diagnosisIn iron deficiency status, laboratory tests may provide evidence of iron depletion in the body or reflect iron deficient red cell production. Increased transferrin saturation and/or ferritin levels are the main cues for further investigation of iron overload. The appropriate combination of different laboratory tests with an integrated algorithm will help to establish a correct diagnosis of iron overload, iron deficiency and anaemia.Review of treatment optionsIndications, advantages and side effects of the different options for treating iron overload (phlebotomy and iron chelators) and iron deficiency (oral or intravenous iron formulations) will be discussed.

scholarly journals A Novel Rat Model of Hereditary Hemochromatosis Due to a Mutation in Transferrin Receptor 2

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 612-612
Author(s):  
Thomas Benedict Bartnikas ◽  
Sheryl Wildt ◽  
Amy Wineinger ◽  
Klaus Schmitz-Abe ◽  
Kyriacos Markianos ◽  
...  
Keyword(s):  
Iron Overload ◽  
Iron Metabolism ◽  
Rat Model ◽  
Transferrin Receptor ◽  
Molecular Mechanisms ◽  
Hereditary Hemochromatosis ◽  
Male Rats ◽  
Male Rat ◽  
Liver Iron ◽  
Transferrin Receptor 2

Abstract Abstract 612 Sporadic iron overload has been reported previously in rats but the underlying cause has not been ascertained. In this study, phenotypic analysis of a subpopulation of Wistar rats designated Hsd:HHCL revealed a low incidence of histologically detected liver iron overload. One rat out of 132 screened animals exhibited liver iron accumulation in a predominantly periportal, hepatocellular distribution; this male rat expressed low RNA levels of the iron regulatory hormone hepcidin and low protein levels of transferrin receptor 2, a membrane protein essential for hepcidin expression in humans and mice and mutated in forms of hereditary hemochromatosis, a disease of excessive intestinal iron absorption and progressive tissue iron overload. Sequencing of the transferrin receptor 2 gene in the iron-overloaded rat revealed a novel Ala679Gly polymorphism affecting a highly conserved residue. Quantitative trait locus mapping revealed that a transferrin receptor 2 polymorphism correlated strongly with serum iron and transferrin saturations in male rats. Transfection of Tfr2 expression constructs into tissue culture cell lines revealed that the Gly679 Tfr2 variant is expressed at a lower level than the Ala679 variant. Selective breeding of rats carrying this polymorphism and characterization of iron metabolism in the resulting progeny indicated that homozygosity for the Ala679Gly allele leads to a hemochromatosis phenotype. The Hsd:HHCL rat is the first genetic rat model of hereditary hemochromatosis and may prove useful for understanding the molecular mechanisms underlying the regulation of iron metabolism and the pathogenesis of hereditary hemochromatosis. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Hfe Gene Knock-Out in a Mouse Model of Hereditary Hemochromatosis Affects Bodily Iron Isotope Compositions

2021 ◽  
Vol 8 ◽  
Author(s):  
Emmanuelle Albalat ◽  
Thibault Cavey ◽  
Patricia Leroyer ◽  
Martine Ropert ◽  
Vincent Balter ◽  
...  
Keyword(s):  
Iron Overload ◽  
Iron Metabolism ◽  
Whole Blood ◽  
Isotope Composition ◽  
Hereditary Hemochromatosis ◽  
Iron Concentration ◽  
Hfe Gene ◽  
Iron Isotope ◽  
Heavy Isotope ◽  
Knock Out

Hereditary hemochromatosis is a genetic iron overload disease related to a mutation within the HFE gene that controls the expression of hepcidin, the master regulator of systemic iron metabolism. The natural stable iron isotope composition in whole blood of control subjects is different from that of hemochromatosis patients and is sensitive to the amount of total iron removed by the phlebotomy treatment. The use of stable isotopes to unravel the pathological mechanisms of iron overload diseases is promising but hampered by the lack of data in organs involved in the iron metabolism. Here, we use Hfe−/− mice, a model of hereditary hemochromatosis, to study the impact of the knock-out on iron isotope compositions of erythrocytes, spleen and liver. Iron concentration increases in liver and red blood cells of Hfe−/− mice compared to controls. The iron stable isotope composition also increases in liver and erythrocytes, consistent with a preferential accumulation of iron heavy isotopes in Hfe−/− mice. In contrast, no difference in the iron concentration nor isotope composition is observed in spleen of Hfe−/− and control mice. Our results in mice suggest that the observed increase of whole blood isotope composition in hemochromatosis human patients does not originate from, but is aggravated by, bloodletting. The subsequent rapid increase of whole blood iron isotope composition of treated hemochromatosis patients is rather due to the release of hepatic heavy isotope-enriched iron than augmented iron dietary absorption. Further research is required to uncover the iron light isotope component that needs to balance the accumulation of hepatic iron heavy isotope, and to better understand the iron isotope fractionation associated to metabolism dysregulation during hereditary hemochromatosis.

scholarly journals Iron age: novel targets for iron overload

Hematology ◽  
2014 ◽  
Vol 2014 (1) ◽  
pp. 216-221 ◽  
Author(s):  
Carla Casu ◽  
Stefano Rivella
Keyword(s):  
Iron Overload ◽  
Iron Age ◽  
Iron Metabolism ◽  
Iron Absorption ◽  
Hereditary Hemochromatosis ◽  
Therapeutic Approaches ◽  
Hepcidin Expression ◽  
Beneficial Effects ◽  
Excess Iron ◽  
Major Factors

Abstract Excess iron deposition in vital organs is the main cause of morbidity and mortality in patients affected by β-thalassemia and hereditary hemochromatosis. In both disorders, inappropriately low levels of the liver hormone hepcidin are responsible for the increased iron absorption, leading to toxic iron accumulation in many organs. Several studies have shown that targeting iron absorption could be beneficial in reducing or preventing iron overload in these 2 disorders, with promising preclinical data. New approaches target Tmprss6, the main suppressor of hepcidin expression, or use minihepcidins, small peptide hepcidin agonists. Additional strategies in β-thalassemia are showing beneficial effects in ameliorating ineffective erythropoiesis and anemia. Due to the suppressive nature of the erythropoiesis on hepcidin expression, these approaches are also showing beneficial effects on iron metabolism. The goal of this review is to discuss the major factors controlling iron metabolism and erythropoiesis and to discuss potential novel therapeutic approaches to reduce or prevent iron overload in these 2 disorders and ameliorate anemia in β-thalassemia.

Physiologic systemic iron metabolism in mice deficient for duodenal Hfe

Blood ◽  
2007 ◽  
Vol 109 (10) ◽  
pp. 4511-4517 ◽  
Author(s):  
Maja Vujic Spasic ◽  
Judit Kiss ◽  
Thomas Herrmann ◽  
Regina Kessler ◽  
Jens Stolte ◽  
...  
Keyword(s):  
Iron Metabolism ◽  
Iron Homeostasis ◽  
Iron Absorption ◽  
Binding Capacity ◽  
Hereditary Hemochromatosis ◽  
Direct Interaction ◽  
Hfe Gene ◽  
Hepatic Iron ◽  
Primary Role ◽  
Genes Encoding

Abstract Mutations in the Hfe gene result in hereditary hemochromatosis (HH), a disorder characterized by increased duodenal iron absorption and tissue iron overload. Identification of a direct interaction between Hfe and transferrin receptor 1 in duodenal cells led to the hypothesis that the lack of functional Hfe in the duodenum affects TfR1-mediated serosal uptake of iron and misprogramming of the iron absorptive cells. Contrasting this view, Hfe deficiency causes inappropriately low expression of the hepatic iron hormone hepcidin, which causes increased duodenal iron absorption. We specifically ablated Hfe expression in mouse enterocytes using Cre/LoxP technology. Mice with efficient deletion of Hfe in crypt- and villi-enterocytes maintain physiologic iron metabolism with wild-type unsaturated iron binding capacity, hepatic iron levels, and hepcidin mRNA expression. Furthermore, the expression of genes encoding the major intestinal iron transporters is unchanged in duodenal Hfe-deficient mice. Our data demonstrate that intestinal Hfe is dispensable for the physiologic control of systemic iron homeostasis under steady state conditions. These findings exclude a primary role for duodenal Hfe in the pathogenesis of HH and support the model according to which Hfe is required for appropriate expression of the “iron hormone” hepcidin which then controls intestinal iron absorption.

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