Update on Hepcidin Regulation in Different Disorders Pierre Brissot, MD Professor of Medicine
 Liver Disease Department University Hospital Pontchaillou Rennes, France

Outline Part 1: Hepcidin as the key hormone of iron regulation Part 2: Hepcidin in different human disorders Iron disorders related to hepcidin deficiency Iron disorders related to hepcidin overproduction Other disorders associated with hepcidin imbalance I will mention orally the issues of monitoring an side effects. I do not think that 282 should be in bold

Hepcidin General Features “Hep” for hepatic and “cidin” for antimicrobial activity1 25-amino-acid protein (derived from an 84-amino-acid precursor)2,3 Coded by the HAMP gene (chromosome 19)3,4 Mainly produced by hepatocytes4,5 I will mention orally the issues of monitoring an side effects. I do not think that 282 should be in bold 1. Park CH, et al. J Biol Chem. 2001;276:7806-7810. 2. Piperno A, et al. World J Gastroenterol. 2009;15:538-551. 3. Lee PL, et al. Annu Rev Pathol. 2009;4:489-515. 4. Andrews NC. Blood. 2008;112:219-230. 5. Pigeon C, et al. J Biol Chem. 2001;276:7811-7819.

Body Iron Regulation by Hepcidin Iron Deficiency 1 Hepcidin 1 Body iron decrease lowers hepcidin synthesis in the liver Hepcidin deficiency targets the duodenum and spleen 2 2 3 Duodenal absorption of iron increases 4 Splenic iron is released into the circulation Iron 4 5 Iron concentration in plasma increases, leading to restoration of iron balance 5 3 Ganz T, et al. Am J Physiol Gastrointest Liver Physiol. 2006;290:G199-G203.

Hepcidin–Cellular Targets and Mechanism of Action Ferroportin exports iron from cell to plasma 1 Cell (enterocyte and macrophage) Hepcidin circulates in plasma 2 F F 3 Hepcidin binds to ferroportin on the cell’s surface 5 H 4 4 Internalization 1 F Ferroportin degradation 5 F F 6 H H Decreased ferroportin exports less iron to plasma 6 3 Plasma 2 Brissot P, et al. Blood Rev. 2008;22:195-210.

Ferroportin HEPCIDIN

Regulation of Hepcidin Transcription1-3 Plasma Tf Sat 4 BMPR HJV BMP6 TfR2 1 TfR1 HFE 2 Membrane 5 MAPK/ERK SMADs Cytosol Hepcidin-mRNA 3 Abbreviations: BMP, bone morphogenic protein; BMPR, bone morphogenic protein receptor; ERK, extracellular signal regulated kinase; HJV, haemojuvelin; MAPK, mitogen activated protein kinase; TF sat, transferrin saturation; TfR1, transferrin receptor 1; TfR2, transferrin receptor 2. Hepatocyte Nucleus 1. Piperno A, et al. World J Gastroenterol. 2009;15:538-551. 2. Lee PL, et al. Annu Rev Pathol. 2009;4:489-515. 3. Calzolari A, et al. J Cell Sci. 2006;119:4486-4498. Graphic courtesy of Dr. P. Brissot.

Regulation of Hepcidin Transcription–Hypothetical1-3 Tf Sat Plasma BMPR BMPR HJV HJV 2 BMP6 BMP TfR2 TfR2 TfR1 HFE HFE TfR1 Membrane MAPK/ERK SMADs SMAD Cytosol Hepcidin-mRNA Hepatocyte Nucleus 1. Piperno A, et al. World J Gastroenterol. 2009;15:538-551. 2. Lee PL, et al. Annu Rev Pathol. 2009;4:489-515. 3. Calzolari A, et al. J Cell Sci. 2006;119:4486-4498. Graphic courtesy of Dr. P. Brissot.

Regulation of Hepcidin by Matriptase-2 Hypothetical Tf Sat 2 Plasma 1 Hepcidin-mRNA BMP BMPR SMAD HJV TfR2 TfR1 HFE BMPR HJV BMP6 TfR2 TfR1 HFE Matriptase-2 Membrane SMADs Cytosol – Hepatocyte Nucleus Ramsay AJ, et al. Haematologica. 2009;94:840-849. Graphic courtesy of Dr. P. Brissot. 9

Outline Part 1: Hepcidin as the key hormone of iron regulation Part 2: Hepcidin in different human disorders Iron disorders related to hepcidin deficiency Iron disorders related to hepcidin overproduction Other disorders associated with hepcidin imbalance I will mention orally the issues of monitoring an side effects. I do not think that 282 should be in bold

Types 1, 2, and 3 Haemochromatosis—Quantitative Hepcidin Defect HFE (type1) or non-HFE (type 2 or 3) mutations 1 HFE or non-HFE mutations decrease hepcidin synthesis in the liver Hepcidin Hepcidin deficiency targets the duodenum and spleen 2 6 2 3 Duodenal absorption of iron increases 4 Splenic iron is released into the circulation 5 Iron concentration in plasma strongly increases Iron 5 4 6 Increased plasma iron produces parenchymal iron deposition 3 Brissot P, et al. Blood Rev. 2008;22:195-210.

Cell (enterocyte and macrophage) Quantitative Defect in Hepcidin-Ferroportin Interaction—Types 1, 2, and 3 Haemochromatosis Ferroportin exports iron from cell to plasma 1 Cell (enterocyte and macrophage) Decreased hepcidin circulates in plasma 2 F 3 Decreased hepcidin binds to ferroportin on the cell’s surface F H 5 4 4 Internalization 1 F Decreased ferroportin degradation 5 F F H Increased ferroportin exports more iron to plasma 6 H 3 6 Plasma 2 Brissot P, et al. Blood Rev. 2008;22:195-210.

Cell (enterocyte and macrophage) Type 4B Haemochromatosis—Qualitative Hepcidin Defect Hepcidin Resistance Mutated ferroportin 1 Cell (enterocyte and macrophage) Normal hepcidin level circulating in plasma 2 3 Defect in hepcidin binding to ferroportin F F 5 4 Decreased ferroportin degradation 4 1 F Increased ferroportin 5 F F H H Increased ferroportin activity exports more iron to plasma 6 3 6 Plasma 2 Brissot P, et al. Blood Rev. 2008;22:195-210.

Outline Part 1: Hepcidin as the key hormone of iron regulation Part 2: Hepcidin in different human disorders Iron disorders related to hepcidin deficiency Iron disorders related to hepcidin overproduction1,2 Other disorders associated with hepcidin imbalance 1. Finberg KE, et al. Nat Genet. 2008;40:569-571. 2. Theurl I, et al. Blood. 2009;113:5277-5286.

Anaemia of Inflammation/Chronic Disease—Hepcidin Overproduction 1 Inflammation Hepcidin 1 Inflammation increases hepcidin synthesis in the liver 5 Hepcidin increase targets the duodenum and spleen 2 2 3 Duodenal absorption of iron decreases 5 4 Splenic iron released into circulation is decreased 5 Overloaded macrophages Iron 6 4 6 Plasma iron concentration decreases, leading to anaemia 3 Brissot P, et al. Blood Rev. 2008;22:195-210.

IL6 Mediation of Hepcidin in Inflammation BMPR BMPR HJV HJV BMP6 BMP TfR2 TfR2 TfR1 IL6 HFE HFE TfR1 Membrane Cytosol MAPK/ERK SMADs SMAD Abbreviations: BMP, bone morphogenic protein; BMPR, bone morphogenic protein receptor; ERK, extracellular signal regulated kinase; IL, interleukin; JAK, Janus kinases; MAPK, mitogen activated protein kinase; STAT, signal transducers and activaters of transcription; TF sat, transferrin saturation; TfR1, transferrin receptor 1; TfR2, transferrin receptor 2. STAT3 /JAK Hepcidin-mRNA + Hepatocyte Nucleus Muckenthaler MU. Cell Metab. 2008;8:1-3. Graphic courtesy of Dr. P. Brissot. 16

Matriptase-2 (TMPRSS6) mutations Iron-Refractory Iron-Deficiency Anaemia (IRIDA)—Hepcidin Overproduction Matriptase-2 (TMPRSS6) mutations 1 Hepcidin 1 Matriptase-2 mutations increase hepcidin synthesis in the liver 2 Hepcidin increase targets the duodenum and spleen 2 3 Duodenal absorption of iron decreases Iron 4 Splenic iron released into circulation is decreased 4 5 5 Plasma iron concentration decreases, leading to anaemia 3 Finberg KE, et al. Nat Genet. 2008;40:569-571.

Effect of Matriptase-2 Deficiency on Hepcidin Regulation Plasma + Tf Sat Hepcidin-mRNA BMP BMPR SMAD HJV TfR2 TfR1 HFE BMPR HJV BMP6 TfR2 TfR1 HFE Matriptase-2 + Membrane SMADs Cytosol + Hepatocyte Nucleus Ramsay AJ, et al. Haematologica. 2009;94:840-849. Graphic courtesy of Dr. P. Brissot. 18

Outline Part 1: Hepcidin as the key hormone of iron regulation Part 2: Hepcidin in different human disorders Iron disorders related to hepcidin deficiency Iron disorders related to hepcidin overproduction Other disorders associated with hepcidin imbalance1,2 1. Origa R, et al. Haematologica. 2007;92:583-588. 2. Kroot JJ, et al. Haematologica. 2009;94:885-887.

Iron Overload Diseases Sideroblastic anaemias Thalassaemias Sickle cell disease Rare anaemias Anaemia Iron Overload

Iron Overload Diseases Sideroblastic anaemias Thalassaemias Sickle cell disease Rare anaemias Anaemia Dyserythropoiesis Hepcidin Iron Overload Graphic courtesy of Dr. P. Brissot.

Effect of Dyserythropoiesis on Body Iron Regulation Hepcidin GDF15 Iron Abbreviation: GDF, growth differentiation factor. Tanno T, et al. Nat Med. 2007;13:1096-1101.

Effect of Hypoxia on Body Iron Regulation Hepcidin HIF Iron Abbreviation: HIF, hypoxia inducible factor. Peyssonnaux C, et al. J Clin Invest. 2007;117:1926-1932.

Effect of Nonhaematologic Conditions on Body Iron

Effect of Alcohol on Body Iron Regulation Hepcidin ROS Iron Abbreviation: ROS, reactive oxygen species. Harrison-Findik DD. World J Gastroenterol. 2007;13:4925-4930.

Effect of Polymetabolic Syndrome on Body Iron Regulation1,2 Hepcidin ROS Iron 1. Barisani D, et al. J Hepatol. 2008;49:123-133. 2. Ruivard M, et al. J Hepatol. 2009;50:1219-1225.

Effect of Hepatitis C Virus Infection on Body Iron Regulation Hepcidin Hepatitis C Virus ROS Iron Nishina S, et al. Gastroenterology. 2008;134:226-238.

Conclusions Hepcidin is the key hormone regulating iron metabolism Hepatic hepcidin production is regulated by iron load Decreased by iron deficiency Increased by iron excess Plasma hepcidin targets enterocytes and macrophages Increased levels lead to decreased entry of iron into the plasma (and vice versa) Decreased hepcidin can be of genetic or acquired origin Genetic: haemochromatosis type 1, 2, 3 Acquired: dyserythropoiesis, hypoxia, alcoholism, hepatitis C Increased hepcidin can be of genetic or acquired origin Genetic: IRIDA Acquired: inflammation, polymetabolic syndrome

Thank you for participating in this webcast Please remember to take the posttest