Tomas Ganz

Publications of Tomas Ganz

• Iron metabolism: interactions with normal and disordered erythropoiesis.

  Authors: Tomas Ganz, Elizabeta Nemeth

  Cold Spring Harbor perspectives in medicine. 05/2012; 2(5):a011668.

  Hemoglobinopathies and other disorders of erythroid cells are often associated with abnormal iron homeostasis. We review the molecular physiology of intracellular and systemic iron regulation, andHemoglobinopathies and other disorders of erythroid cells are often associated with abnormal iron homeostasis. We review the molecular physiology of intracellular and systemic iron regulation, and the interactions between erythropoiesis and iron homeostasis. Finally, we discuss iron disorders that affect erythropoiesis as well as erythroid disorders that cause iron dysregulation.

• Hepcidin and iron homeostasis.

  Authors: Tomas Ganz, Elizabeta Nemeth

  Biochimica et biophysica acta. 01/2012;

  Despite fluctuations in dietary iron intake and intermittent losses through bleeding, the plasma iron concentrations in humans remain stable at 10-30μM. While most of the iron entering blood plasmaDespite fluctuations in dietary iron intake and intermittent losses through bleeding, the plasma iron concentrations in humans remain stable at 10-30μM. While most of the iron entering blood plasma comes from recycling, appropriate amount of iron is absorbed from the diet to compensate for losses and maintain nontoxic amounts in stores. Plasma iron concentration and iron distribution are similarly regulated in laboratory rodents. The hepatic peptide hepcidin was identified as the systemic iron-regulatory hormone. In the efferent arc, hepcidin regulates intestinal iron absorption, plasma iron concentrations, and tissue iron distribution by inducing degradation of its receptor, the cellular iron exporter ferroportin. Ferroportin exports iron into plasma from absorptive enterocytes, from macrophages that recycle the iron of senescent erythrocytes, and from hepatocytes that store iron. In the more complex and less well understood afferent arc, hepatic hepcidin synthesis is transcriptionally regulated by extracellular and intracellular iron concentrations through a molecular complex of bone morphogenetic protein receptors and their iron-specific ligands, modulators and iron sensors. Through as yet undefined pathways, hepcidin is also homeostatically regulated by the iron requirements of erythroid precursors for hemoglobin synthesis. In accordance with the role of hepcidin-mediated iron redistribution in host defense, hepcidin production is regulated by inflammation as well. Increased hepcidin concentrations in plasma are pathogenic in iron-restrictive anemias including anemias associated with inflammation, chronic kidney disease and some cancers. Hepcidin deficiency causes iron overload in hereditary hemochromatosis and ineffective erythropoiesis. Hepcidin, ferroportin and their regulators represent potential targets for the diagnosis and treatment of iron disorders and anemias. This article is part of a Special Issue entitled: Cell Biology of Metals.

• Inhibition of hepcidin transcription by growth factors.

  Authors: Julia B Goodnough, Emilio Ramos, Elizabeta Nemeth, Tomas Ganz

  Hepatology (Baltimore, Md.). 01/2012;

  The hepatic peptide hormone hepcidin controls the duodenal absorption of iron, its storage and its systemic distribution. Hepcidin production is often insufficient in chronic hepatitis C andThe hepatic peptide hormone hepcidin controls the duodenal absorption of iron, its storage and its systemic distribution. Hepcidin production is often insufficient in chronic hepatitis C and alcoholic liver disease, leading to hyperabsorption of iron and its accumulation in the liver. Hepatocyte growth factor (HGF) and epidermal growth factor (EGF) mediate the hepatic regeneration after liver injury. We examined the effect of the growth factors on hepcidin synthesis by hepatocytes. Results: HGF and EGF treatment of primary mouse hepatocytes, as well as EGF administration in mice, suppressed hepcidin mRNA synthesis. The suppression of hepcidin by these growth factors was transcriptional, and was mediated by a direct effect of HGF and EGF on the BMP pathway regulating hepcidin synthesis. We further showed that growth factors interfered with nuclear localization of activated Smads and increased the nuclear pool of the BMP transcriptional co-repressor TG-interacting factor (TGIF). In a kinase screen with small-molecule kinase inhibitors, inhibitors in the PI3 kinase pathway and in the MEK/ERK pathway prevented HGF suppression of hepcidin in primary mouse hepatocytes. CONCLUSION: HGF and EGF suppress hepatic hepcidin synthesis, in part through PI3 kinase MEK/ERK kinase pathways which may be modulating the nuclear localization of BMP pathway transcriptional regulators including activated Smads1/5/8 and the co-repressor TGIF. EGF, HGF and possibly other growth factors that activate similar pathways may contribute to hepcidin suppression in chronic liver diseases, promote iron accumulation in the liver and exacerbate the destructive disease processes. (HEPATOLOGY 2012.).

• Hepcidin expression in iron overload diseases is variably modulated by circulating factors.

  Authors: Giulia Ravasi, Sara Pelucchi, Paola Trombini, Raffaella Mariani, Naohisa Tomosugi, Giulia Litta Modignani, Matteo Pozzi, Elizabeth Nemeth, Tomas Ganz, Hisao Hayashi, Donatella Barisani, Alberto Piperno

  PloS one. 01/2012; 7(5):e36425.

  Hepcidin is a regulatory hormone that plays a major role in controlling body iron homeostasis. Circulating factors (holotransferrin, cytokines, erythroid regulators) might variably contribute toHepcidin is a regulatory hormone that plays a major role in controlling body iron homeostasis. Circulating factors (holotransferrin, cytokines, erythroid regulators) might variably contribute to hepcidin modulation in different pathological conditions. There are few studies analysing the relationship between hepcidin transcript and related protein expression profiles in humans. Our aims were: a. to measure hepcidin expression at either hepatic, serum and urinary level in three paradigmatic iron overload conditions (hemochromatosis, thalassemia and dysmetabolic iron overload syndrome) and in controls; b. to measure mRNA hepcidin expression in two different hepatic cell lines (HepG2 and Huh-7) exposed to patients and controls sera to assess whether circulating factors could influence hepcidin transcription in different pathological conditions. Our findings suggest that hepcidin assays reflect hepatic hepcidin production, but also indicate that correlation is not ideal, likely due to methodological limits and to several post-trascriptional events. In vitro study showed that THAL sera down-regulated, HFE-HH and C-NAFLD sera up-regulated hepcidin synthesis. HAMP mRNA expression in Huh-7 cells exposed to sera form C-Donors, HFE-HH and THAL reproduced, at lower level, the results observed in HepG2, suggesting the important but not critical role of HFE in hepcidin regulation.

• Minihepcidins are rationally designed small peptides that mimic hepcidin activity in mice and may be useful for the treatment of iron overload.

  Authors: Gloria C Preza, Piotr Ruchala, Rogelio Pinon, Emilio Ramos, Bo Qiao, Michael A Peralta, Shantanu Sharma, Alan Waring, Tomas Ganz, Elizabeta Nemeth

  The Journal of clinical investigation. 11/2011; 121(12):4880-8.

  Iron overload is the hallmark of hereditary hemochromatosis and a complication of iron-loading anemias such as β-thalassemia. Treatment can be burdensome and have significant side effects, and newIron overload is the hallmark of hereditary hemochromatosis and a complication of iron-loading anemias such as β-thalassemia. Treatment can be burdensome and have significant side effects, and new therapeutic options are needed. Iron overload in hereditary hemochromatosis and β-thalassemia intermedia is caused by hepcidin deficiency. Although transgenic hepcidin replacement in mouse models of these diseases prevents iron overload or decreases its potential toxicity, natural hepcidin is prohibitively expensive for human application and has unfavorable pharmacologic properties. Here, we report the rational design of hepcidin agonists based on the mutagenesis of hepcidin and the hepcidin-binding region of ferroportin and computer modeling of their docking. We identified specific hydrophobic/aromatic residues required for hepcidin-ferroportin binding and obtained evidence in vitro that a thiol-disulfide interaction between ferroportin C326 and the hepcidin disulfide cage may stabilize binding. Guided by this model, we showed that 7–9 N-terminal amino acids of hepcidin, including a single thiol cysteine, comprised the minimal structure that retained hepcidin activity, as shown by the induction of ferroportin degradation in reporter cells. Further modifications to increase resistance to proteolysis and oral bioavailability yielded minihepcidins that, after parenteral or oral administration to mice, lowered serum iron levels comparably to those after parenteral native hepcidin. Moreover, liver iron concentrations were lower in mice chronically treated with minihepcidins than those in mice treated with solvent alone. Minihepcidins may be useful for the treatment of iron overload disorders.

• Chuvash polycythemia VHLR200W mutation is associated with down-regulation of hepcidin expression.

  Authors: Victor R Gordeuk, Galina Y Miasnikova, Adelina I Sergueeva, Xiaomei Niu, Mehdi Nouraie, Daniel J Okhotin, Lydia A Polyakova, Tatiana Ammosova, Sergei Nekhai, Tomas Ganz, Josef T Prchal

  Blood. 08/2011; 118(19):5278-82.

  Hypoxia is known to reduce the expression of hepcidin, the master regulator of iron metabolism. However, it is not clear whether this response is primarily related to increased erythropoiesis drivenHypoxia is known to reduce the expression of hepcidin, the master regulator of iron metabolism. However, it is not clear whether this response is primarily related to increased erythropoiesis driven by hypoxically stimulated erythropoietin or to a more direct effect of hypoxia on hepcidin expression. The germline loss-of-function VHL(R200W) mutation is common in Chuvashia, Russia, and also occurs elsewhere. VHL(R200W) homozygotes have elevated hypoxia-inducible factor 1α (HIF-1α) and HIF-2α levels, increased red cell mass, propensity to thrombosis, and early mortality. Ninety VHL(R200W) homozygotes and 52 controls with normal VHL alleles from Chuvashia, Russia, were studied under basal circumstances. In univariate analyses, serum hepcidin concentration was correlated positively with serum ferritin concentration and negatively with homozygosity for VHL(R200W). After adjustment for serum erythropoietin and ferritin concentrations by multiple linear regression, the geometric mean (95% confidence interval of mean) hepcidin concentration was 8.1 (6.3-10.5) ng/mL in VHL(R200W) homozygotes versus 26.9 (18.6-38.0) ng/mL in controls (P < .001). In contrast, a significant independent relationship of serum erythropoietin, hemoglobin, or RBC count with hepcidin was not observed. In conclusion, up-regulation of the hypoxic response leads to decreased expression of hepcidin that may be independent of increased erythropoietin levels and increased RBC counts.

• Hepcidin response to acute iron intake and chronic iron loading in dysmetabolic iron overload syndrome.

  Authors: Paola Trombini, Valentina Paolini, Sara Pelucchi, Raffaella Mariani, Elizabeta Nemeth, Tomas Ganz, Alberto Piperno

  Liver international : official journal of the International Association for the Study of the Liver. 08/2011; 31(7):994-1000.

  The pathogenesis of dysmetabolic iron overload syndrome (DIOS) is still unclear. Hepcidin is the key regulator of iron homeostasis controlling iron absorption and macrophage release. To investigateThe pathogenesis of dysmetabolic iron overload syndrome (DIOS) is still unclear. Hepcidin is the key regulator of iron homeostasis controlling iron absorption and macrophage release. To investigate hepcidin regulation by iron in DIOS. We analysed urinary hepcidin at baseline and 24 h after a 65 mg oral iron dose in 24 patients at diagnosis and after iron depletion (n = 13) and compared data with those previously observed in 23 healthy controls. Serum iron indices, liver histology and metabolic data were available for all patients. At diagnosis, hepcidin values were significantly higher than in controls (P < 0.001). After iron depletion, hepcidin levels decreased to normal values in all patients. At baseline, a significant response of hepcidin to iron challenge was observed only in the subgroup with lower basal hepcidin concentration (P = 0.007). In iron-depleted patients, urinary hepcidin significantly increased after oral iron test (P = 0 .006). Ours findings suggest that in DIOS, the progression of iron accumulation is counteracted by the increase in hepcidin production and progressive reduction of iron absorption, explaining why these patients develop a mild-moderate iron overload that tends to a plateau.

• The heterozygote advantage of the Chuvash polycythemia VHLR200W mutation may be protection against anemia.

  Authors: Galina Y Miasnikova, Adelina I Sergueeva, Mehdi Nouraie, Xiaomei Niu, Daniel J Okhotin, Lydia A Polyakova, Tomas Ganz, Josef T Prchal, Victor R Gordeuk

  Haematologica. 05/2011; 96(9):1371-4.

  The germ-line loss-of-function VHL(R200W) mutation is common in Chuvashia, Russia and occurs in other parts of the world. VHL(R200W) homozygotes have elevated hypoxia inducible factor (HIF)-1 andThe germ-line loss-of-function VHL(R200W) mutation is common in Chuvashia, Russia and occurs in other parts of the world. VHL(R200W) homozygotes have elevated hypoxia inducible factor (HIF)-1 and HIF-2 levels, increased hemoglobin concentration, propensity to thrombosis and early mortality. Because the mutation persists from an ancient origin, we hypothesized that there is a heterozygote advantage. Thirty-four VHL(R200W) heterozygotes and 44 controls over 35 years of age from Chuvashia, Russia were studied. Anemia was defined as hemoglobin less than 130 g/L in men and less than 120 g/L in women. Mild anemia was present in 15% of VHL(R200W) heterozygotes and 34% of controls without a mutated VHL allele. By multivariate logistic regression, the odds of anemia were reduced an estimated 5.6-fold in the VHL(R200W) heterozygotes compared to controls (95% confidence interval 1.4-22.7; P=0.017). In conclusion, heterozygosity for VHL(R200W) may provide protection from anemia; such protection could explain the persistence of this mutation.

• Serum hepcidin as a diagnostic test of iron deficiency in premenopausal female blood donors.

  Authors: Sant-Rayn Pasricha, Zoe McQuilten, Mark Westerman, Anthony Keller, Elizabeta Nemeth, Tomas Ganz, Erica Wood

  Haematologica. 04/2011; 96(8):1099-105.

  Currently used indicators of iron status have limitations. Hepcidin, a key regulator of iron metabolism, is reduced in iron deficiency. We sought to determine the properties of hepcidin as aCurrently used indicators of iron status have limitations. Hepcidin, a key regulator of iron metabolism, is reduced in iron deficiency. We sought to determine the properties of hepcidin as a diagnostic test of iron deficiency. Sera from female, non-anemic, whole blood donors were analyzed for hepcidin (enzyme-linked immunosorbent assay), ferritin, soluble transferrin receptor and C-reactive protein. Iron deficiency was defined as (i) serum ferritin less than 15 ng/mL or (ii) soluble transferrin receptor /log(ferritin) index greater than 3.2 if the C-reactive protein concentration was less than 10 mg/L, or greater than 2.2 if the C-reactive protein concentration was greater than 10 mg/L). Receiver operating characteristic curves were plotted to determine the overall utility and identify optimal cut-points of hepcidin as a test of iron deficiency. In 261 blood donors the prevalence of iron deficiency defined by ferritin concentration was 59/261 [22.6% (17.5, 27.7)], whereas defined by soluble transferrin receptor/log(ferritin) index it was 53/261 [20.4% (15.4, 25.2)]. The 95% reference range of hepcidin concentration in the iron-replete population was 8.2-199.7 ng/mL. The area under the receiver operating characteristic curve for hepcidin compared with ferritin concentration less than 15 ng/mL was 0.87 (0.82, 0.92), while that compared with the soluble transferrin receptor /log(ferritin) index was 0.89 (95% CI 0.84, 0.93). For a diagnosis of iron deficiency defined by the soluble transferrin receptor/log(ferritin) index, hepcidin less than 8 ng/mL had a sensitivity of 41.5% and a specificity of 97.6%, while hepcidin less than 18 ng/mL had a sensitivity of 79.2% and a specificity of 85.6%. Serum hepcidin concentration may be a useful indicator of deficient iron stores. Further studies are required to evaluate the role of hepcidin in the diagnosis of iron deficiency in other groups of patients.

• Evidence for distinct pathways of hepcidin regulation by acute and chronic iron loading in mice.

  Authors: Emilio Ramos, Léon Kautz, Richard Rodriguez, Michael Hansen, Victoria Gabayan, Yelena Ginzburg, Marie-Paule Roth, Elizabeta Nemeth, Tomas Ganz

  Hepatology (Baltimore, Md.). 04/2011; 53(4):1333-41.

  In response to iron loading, hepcidin synthesis is homeostatically increased to limit further absorption of dietary iron and its release from stores. Mutations in HFE, transferrin receptor 2 (Tfr2),In response to iron loading, hepcidin synthesis is homeostatically increased to limit further absorption of dietary iron and its release from stores. Mutations in HFE, transferrin receptor 2 (Tfr2), hemojuvelin (HJV), or bone morphogenetic protein 6 (BMP6) prevent appropriate hepcidin response to iron, allowing increased absorption of dietary iron, and eventually iron overload. To understand the role each of these proteins plays in hepcidin regulation by iron, we analyzed hepcidin messenger RNA (mRNA) responsiveness to short and long-term iron challenge in iron-depleted Hfe, Tfr2, Hjv, and Bmp6 mutant mice. After 1-day (acute) iron challenge, Hfe(-/-) mice showed a smaller hepcidin increase than their wild-type strain-matched controls, Bmp6(-/-) mice showed nearly no increase, and Tfr2 and Hjv mutant mice showed no increase in hepcidin expression, indicating that all four proteins participate in hepcidin regulation by acute iron changes. After a 21-day (chronic) iron challenge, Hfe and Tfr2 mutant mice increased hepcidin expression to nearly wild-type levels, but a blunted increase of hepcidin was seen in Bmp6(-/-) and Hjv(-/-) mice. BMP6, whose expression is also regulated by iron, may mediate hepcidin regulation by iron stores. None of the mutant strains (except Bmp6(-/-) mice) had impaired BMP6 mRNA response to chronic iron loading. CONCLUSION: TfR2, HJV, BMP6, and, to a lesser extent, HFE are required for the hepcidin response to acute iron loading, but are partially redundant for hepcidin regulation during chronic iron loading and are not involved in the regulation of BMP6 expression. Our findings support a model in which acute increases in holotransferrin concentrations transmitted through HFE, TfR2, and HJV augment BMP receptor sensitivity to BMPs. A distinct regulatory mechanism that senses hepatic iron may modulate hepcidin response to chronic iron loading.

• Understanding the structure/activity relationships of the iron regulatory peptide hepcidin.

  Authors: Richard J Clark, Chia Chia Tan, Gloria C Preza, Elizabeta Nemeth, Tomas Ganz, David J Craik

  Chemistry & biology. 03/2011; 18(3):336-43.

  The peptide hormone hepcidin is a key homeostatic regulator of iron metabolism and involved in pathological regulation of iron in response to infection, inflammation, hypoxia, and anemia. It acts byThe peptide hormone hepcidin is a key homeostatic regulator of iron metabolism and involved in pathological regulation of iron in response to infection, inflammation, hypoxia, and anemia. It acts by binding to the iron exporter ferroportin, causing it to be internalized and degraded; however, little is known about the structure/activity relationships of the interaction of hepcidin with ferroportin. We show that there are key residues in the N-terminal region of hepcidin that influence its interaction with ferroportin, and we explore the structure/function relationships at these positions. A series of hepcidin mutants in which disulfide bonds were replaced with diselenide bonds showed no change in activity compared to native hepcidin. These results identify important constraints for the development of hepcidin congeners for the treatment of hereditary iron overload.

• Hepcidin and iron regulation, 10 years later.

  Authors: Tomas Ganz

  Blood. 02/2011; 117(17):4425-33.

  Under evolutionary pressure to counter the toxicity of iron and to maintain adequate iron supply for hemoglobin synthesis and essential metabolic functions, humans and other vertebrates haveUnder evolutionary pressure to counter the toxicity of iron and to maintain adequate iron supply for hemoglobin synthesis and essential metabolic functions, humans and other vertebrates have effective mechanisms to conserve iron and to regulate its concentration, storage, and distribution in tissues. The iron-regulatory hormone hepcidin, first described 10 years ago, and its receptor and iron channel ferroportin control the dietary absorption, storage, and tissue distribution of iron. Hepcidin causes ferroportin internalization and degradation, thereby decreasing iron transfer into blood plasma from the duodenum, from macrophages involved in recycling senescent erythrocytes, and from iron-storing hepatocytes. Hepcidin is feedback regulated by iron concentrations in plasma and the liver and by erythropoietic demand for iron. Genetic malfunctions affecting the hepcidin-ferroportin axis are a main cause of iron overload disorders but can also cause iron-restricted anemias. Modulation of hepcidin and ferroportin expression during infection and inflammation couples iron metabolism to host defense and decreases iron availability to invading pathogens. This response also restricts the iron supply to erythropoietic precursors and may cause or contribute to the anemia associated with infections and inflammatory disorders.

• Increased serum hepcidin levels during treatment with deferasirox in iron-overloaded patients with myelodysplastic syndrome.

  Authors: Hussam Ghoti, Eitan Fibach, Mark Westerman, Olbina Gordana, Tomas Ganz, Eliezer A Rachmilewitz

  British journal of haematology. 02/2011; 153(1):118-20.

  Hepcidin is a major regulator of iron metabolism. We evaluated changes in serum hepcidin during 3 months of therapy with the iron-chelator deferasirox in patients with low-risk myelodysplasticHepcidin is a major regulator of iron metabolism. We evaluated changes in serum hepcidin during 3 months of therapy with the iron-chelator deferasirox in patients with low-risk myelodysplastic syndrome and iron overload. Serum hepcidin was found to be high in these patients, correlated with their iron and oxidative status, and further increased by treatment with deferasirox. These findings support the concept that the hepcidin level represents a balance between the stimulating effect of iron overload and the inhibitory effects of erythropoietic activity and oxidative stress. These preliminary findings favour the rationale for iron chelation therapy in such patients.

• The hepcidin-ferroportin system as a therapeutic target in anemias and iron overload disorders.

  Authors: Tomas Ganz, Elizabeta Nemeth

  Hematology / the Education Program of the American Society of Hematology. American Society of Hematology. Education Program. 01/2011; 2011:538-42.

  The review summarizes the current understanding of the role of hepcidin and ferroportin in normal iron homeostasis and its disorders. The various approaches to therapeutic targeting of hepcidin andThe review summarizes the current understanding of the role of hepcidin and ferroportin in normal iron homeostasis and its disorders. The various approaches to therapeutic targeting of hepcidin and ferroportin in iron-overload disorders (mainly hereditary hemochromatosis and β-thalassemia) and iron-restrictive anemias (anemias associated with infections, inflammatory disorders, and certain malignancies, anemia of chronic kidney diseases, and iron-refractory iron-deficiency anemia) are also discussed.

• Detection, evaluation, and management of iron-restricted erythropoiesis.

  Authors: Lawrence Tim Goodnough, Elizabeta Nemeth, Tomas Ganz

  Blood. 12/2010; 116(23):4754-61.

  Progress in our understanding of iron-restricted erythropoiesis has been made possible by important advances in defining the molecular mechanisms of iron homeostasis. The detection and diagnosticProgress in our understanding of iron-restricted erythropoiesis has been made possible by important advances in defining the molecular mechanisms of iron homeostasis. The detection and diagnostic classification of iron-restricted erythropoiesis can be a challenging process for the clinician. Newer assays for markers of inflammation may allow more targeted management of the anemia in these conditions. The availability of new intravenous iron preparations provides new options for the treatment of iron-restricted erythropoiesis. This review summarizes recent advances regarding the detection, evaluation, and management of iron-restricted erythropoiesis.

• Modulation of hepcidin production during hypoxia-induced erythropoiesis in humans in vivo: data from the HIGHCARE project.

  Authors: Alberto Piperno, Stefania Galimberti, Raffaella Mariani, Sara Pelucchi, Giulia Ravasi, Carolina Lombardi, Grzegorz Bilo, Miriam Revera, Andrea Giuliano, Andrea Faini, Veronica Mainini, Mark Westerman, Tomas Ganz, Maria Grazia Valsecchi, Giuseppe Mancia, Gianfranco Parati

  Blood. 12/2010; 117(10):2953-9.

  Iron is tightly connected to oxygen homeostasis and erythropoiesis. Our aim was to better understand how hypoxia regulates iron acquisition for erythropoiesis in humans, a topic relevant to commonIron is tightly connected to oxygen homeostasis and erythropoiesis. Our aim was to better understand how hypoxia regulates iron acquisition for erythropoiesis in humans, a topic relevant to common hypoxia-related disorders. Forty-seven healthy volunteers participated in the HIGHCARE project. Blood samples were collected at sea level and after acute and chronic exposure to high altitude (3400-5400 m above sea level). We investigated the modifications in hematocrit, serum iron indices, erythropoietin, markers of erythropoietic activity, interleukin-6, and serum hepcidin. Hepcidin decreased within 40 hours after acute hypoxia exposure (P < .05) at 3400 m, reaching the lowest level at 5400 m (80% reduction). Erythropoietin significantly increased (P < .001) within 16 hours after hypoxia exposure followed by a marked erythropoietic response supported by the increased iron supply. Growth differentiation factor-15 progressively increased during the study period. Serum ferritin showed a very rapid decrease, suggesting the existence of hypoxia-dependent mechanism(s) regulating storage iron mobilization. The strong correlation between serum ferritin and hepcidin at each point during the study indicates that iron itself or the kinetics of iron use in response to hypoxia may signal hepcidin down-regulation. The combined and significant changes in other variables probably contribute to the suppression of hepcidin in this setting.

• A time course of hepcidin response to iron challenge in patients with HFE and TFR2 hemochromatosis.

  Authors: Domenico Girelli, Paola Trombini, Fabiana Busti, Natascia Campostrini, Marco Sandri, Sara Pelucchi, Mark Westerman, Tomas Ganz, Elizabeta Nemeth, Alberto Piperno, Clara Camaschella

  Haematologica. 12/2010; 96(4):500-6.

  Inadequate hepcidin production leads to iron overload in nearly all types of hemochromatosis. We explored the acute response of hepcidin to iron challenge in 25 patients with HFE-hemochromatosis, inInadequate hepcidin production leads to iron overload in nearly all types of hemochromatosis. We explored the acute response of hepcidin to iron challenge in 25 patients with HFE-hemochromatosis, in two with TFR2-hemochromatosis and in 13 controls. Sixteen patients (10 C282Y/C282Y homozygotes, 6 C282Y/H63D compound heterozygotes) had increased iron stores, while nine (6 C282Y/C282Y homozygotes, 3 C282Y/H63D compound heterozygotes) were studied after phlebotomy-induced normalization of iron stores. We analyzed serum iron, transferrin saturation, and serum hepcidin by both enzyme-linked immunosorbent assay and mass-spectrometry at baseline, and 4, 8, 12 and 24 hours after a single 65-mg dose of oral iron. Serum iron and transferrin saturation significantly increased at 4 hours and returned to baseline values at 8-12 hours in all groups, except in the iron-normalized patients who showed the highest and longest increase of both parameters. The level of hepcidin increased significantly at 4 hours and returned to baseline at 24 hours in controls and in the C282Y/H63D compound heterozygotes at diagnosis. The hepcidin response was smaller in C282Y-homozygotes than in controls, barely detectable in the patients with iron-depleted HFE-hemochromatosis and absent in those with TFR2-hemochromatosis. Conclusions Our results are consistent with a scenario in which TFR2 plays a prominent and HFE a contributory role in the hepcidin response to a dose of oral iron. In iron-normalized patients with HFE hemochromatosis, both the low baseline hepcidin level and the weak response to iron contribute to hyperabsorption of iron.

• In anemia of multiple myeloma, hepcidin is induced by increased bone morphogenetic protein 2.

  Authors: Ken Maes, Elizabeta Nemeth, G David Roodman, Alissa Huston, Flavia Esteve, Cesar Freytes, Natalie Callander, Eirini Katodritou, Lisa Tussing-Humphreys, Seth Rivera, Karin Vanderkerken, Alan Lichtenstein, Tomas Ganz

  Blood. 11/2010; 116(18):3635-44.

  Hepcidin is the principal iron-regulatory hormone and a pathogenic factor in anemia of inflammation. Patients with multiple myeloma (MM) frequently present with anemia. We showed that MM patients hadHepcidin is the principal iron-regulatory hormone and a pathogenic factor in anemia of inflammation. Patients with multiple myeloma (MM) frequently present with anemia. We showed that MM patients had increased serum hepcidin, which inversely correlated with hemoglobin, suggesting that hepcidin contributes to MM-related anemia. Searching for hepcidin-inducing cytokines in MM, we quantified the stimulation of hepcidin promoter-luciferase activity in HuH7 cells by MM sera. MM sera activated the hepcidin promoter significantly more than did normal sera. We then examined the role of bone morphogenetic proteins (BMPs) and interleukin-6 (IL-6), the major transcriptional regulators of hepcidin. Mutations in both BMP-responsive elements abrogated the activation dramatically, while mutations in the IL-6-responsive signal transducer and activator of transcription 3-binding site (STAT3-BS) had only a minor effect. Cotreatment with anti-BMP-2/4 or noggin-Fc blocked the promoter induction with all MM sera, anti-IL-6 blocked it with a minority of sera, whereas anti-BMP-4, -6, or -9 antibodies had no effect. BMP-2-immunodepleted MM sera had decreased promoter stimulatory capacity, and BMP-2 concentrations in MM sera were significantly higher than in normal sera. Our results demonstrate that BMP-2 is a major mediator of the hepcidin stimulatory activity of MM sera.

• Testosterone suppresses hepcidin in men: a potential mechanism for testosterone-induced erythrocytosis.

  Authors: Eric Bachman, Rui Feng, Thomas Travison, Michelle Li, Gordana Olbina, Vaughn Ostland, Jagadish Ulloor, Anqi Zhang, Shehzad Basaria, Tomas Ganz, Mark Westerman, Shalender Bhasin

  The Journal of clinical endocrinology and metabolism. 10/2010; 95(10):4743-7.

  The mechanisms by which testosterone increases hemoglobin and hematocrit are unknown. The aim was to test the hypothesis that testosterone-induced increase in hematocrit is associated withThe mechanisms by which testosterone increases hemoglobin and hematocrit are unknown. The aim was to test the hypothesis that testosterone-induced increase in hematocrit is associated with suppression of the iron regulatory peptide hepcidin. Healthy younger men (ages 19-35 yr; n = 53) and older men (ages 59-75 yr; n = 56) were studied. Weekly doses of testosterone enanthate (25, 50, 125, 300, and 600 mg) were administered over 20 wk, whereas endogenous testosterone was suppressed by monthly GnRH agonist administration. Blood and serum parameters from each individual were measured at wk 0, 1, 2, 4, 8, and 20. Longitudinal analyses were performed to examine the relationship between hepcidin, hemoglobin, hematocrit, and testosterone while controlling for potential confounders. High levels of testosterone markedly suppressed serum hepcidin within 1 wk. Hepcidin suppression in response to testosterone administration was dose-dependent in older men and more pronounced than in young men, and this corresponded to a greater rise in hemoglobin in older men. Serum hepcidin levels at 4 and 8 wk were predictive of change in hematocrit from baseline to peak levels. Testosterone administration is associated with suppression of serum hepcidin. Greater increases in hematocrit in older men during testosterone therapy are related to greater suppression of hepcidin.

• Alpha 1-acid glycoprotein, hepcidin, C-reactive protein, and serum ferritin are correlated in anemic schoolchildren with Schistosoma haematobium.

  Authors: Mohamed A Ayoya, Gerburg M Spiekermann-Brouwer, Rebecca J Stoltzfus, Elizabeta Nemeth, Jean-Pierre Habicht, Tomas Ganz, Rahul Rawat, Abdel K Traoré, Cutberto Garza

  The American journal of clinical nutrition. 06/2010; 91(6):1784-90.

  The World Health Organization and Centers for Disease Control and Prevention recommend the inclusion of indicators of iron status and inflammation in surveys assessing iron deficiency and/orThe World Health Organization and Centers for Disease Control and Prevention recommend the inclusion of indicators of iron status and inflammation in surveys assessing iron deficiency and/or anemia. We examined the associations between serum alpha(1)-acid glycoprotein (AGP), serum C-reactive protein (CRP), and urinary hepcidin and their relations with serum ferritin (SF), serum transferrin receptor (sTfR), and hemoglobin. At enrollment, the measurements were made in randomly selected 7-12-y-old anemic children with documented Schistosoma haematobium infection (n = 224 for AGP, CRP, SF, sTfR, and hemoglobin; n = 61 for urinary hepcidin). The correlation between the conventional markers of inflammation, AGP and CRP, was positive (r = 0.40, P < 0.01), and the correlation between the unambiguous markers of iron nutrition, hemoglobin and s-TfR, was negative (r = -0.36, P < 0.01). None of the correlations (r < 0.08) between the above markers was statistically significant. Urinary hepcidin correlated positively with the 2 measured indicators of inflammation (r > or = 0.42, P < 0.01) but not with the 2 indicators of iron nutrition (r < 0.07). SF correlated positively with the 2 measured inflammation markers (r > or = 0.25, P < 0.01) and the 2 iron-nutrition indicators (r > 0.26, P < 0.01). Urinary hepcidin correlated positively with SF (r = 0.39, P < 0.01). Regression analyses suggested that CRP and AGP were significant predictors of SF (P < 0.001); however, CRP (R(2) = 0.38) explained more of SF's variance than did AGP (R(2) = 0.17). Correlations between AGP, CRP, urinary hepcidin, and SF were statistically significant. CRP values explained SF's variance better than did the other markers of inflammation studied. We therefore recommend the measurement of both AGP and CRP in population surveys that include an assessment of iron deficiency in developing countries.