Journal of Hepatology
Volume 48, Supplement 1 , Pages S113-S123, 2008

Iron and the liver: Update 2008☆

  • Yves Deugnier

      Affiliations

    • Service des maladies du Foie, INSERM CIC 0203, Université de Rennes 1 and IFR 140, CHU Pontchaillou, 35033 Rennes, France
    • Corresponding Author InformationCorresponding author.
    • ,
  • Pierre Brissot

      Affiliations

    • Service des maladies du Foie, INSERM U 522, Université de Rennes 1 and IFR 140, CHU Pontchaillou, 35033 Rennes, France
    • ,
  • Olivier Loréal

      Affiliations

    • INSERM U 522, Université de Rennes 1 and IFR 140, CHU Pontchaillou, 35033 Rennes, France

published online 13 February 2008.

Article Outline

The cross-talk which has taken place in recent years between clinicians and scientists has resulted in a greater understanding of iron metabolism with the discovery of new iron-related genes including the hepcidin gene which plays a critical role in regulating systemic iron homeostasis. Consequently, the distinction between (a) genetic iron-overload disorders including haemochromatosis related to mutations in the HFE, hemojuvelin, transferrin receptor 2 and hepcidin genes and (b) non-haemochromatotic conditions related to mutations in the ferroportin, ceruloplasmin, transferrin and di-metal transporter 1 genes, and (c) acquired iron-overload syndromes has become easier. However, major challenges still remain which include our understanding of the regulation of hepcidin production, the identification of environmental and genetic modifiers of iron burden and organ damage in iron-overload syndromes, especially HFE haemochromatosis, indications regarding the new oral chelator, deferasirox, and the development of new therapeutic tools interacting with the regulation of iron metabolism.

Abbreviations: AST, aspartate amino transferase, BMP, bone morphogenic protein, BMPR, bone morphogenic protein receptor, C/EBP, CCAAT/enhancer binding protein, DIOS, dysmetabolic iron-overload syndrome, DMT, divalent metal transporter, ERK, extracellular regulated MAP kinase, GDF, growth differentiation factor, Hamp, hepcidin anti-microbial peptide, HAS, Haute Autorité de Santé, HCC, hepatocellular carcinoma, HCV, hepatitis C virus, HIF, hypoxia-inducible factor, HJV, hemojuvelin, IL, interleukin, INSERM, Institut National de la Santéet de la RechercheMédicale, JAK, Janus kinase, LIC, liver iron concentration, MAP, mitogen activated protein, MRI, magnetic resonance imaging, NTBI, nontransferrin bound iron, ROS, reactive oxygen species, STAT, signal transducer and activator of transcription, TfR, transferrin receptor, TGF, transforming growth factor

Keywords: Haemochromatosis, Hepatic iron-overload, Iron metabolism

 

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1. Introduction 

Since the discovery of the HFE gene in 1996 [1], cross-talk between clinicians and scientists has been tremendously fruitful, resulting in a better understanding of iron metabolism with the discovery of new iron-related genes including the hepcidin gene which plays a critical role in regulating systemic iron homeostasis. Consequently, the classification and management of human disorders in this area have been greatly clarified.

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2. Iron metabolism: the central role of the liver through hepcidin production 

Once iron has entered the body, it is reutilized in a closed circuit, since daily iron loss is limited and not regulated according to iron stores. The only regulatory target of iron balance is intestinal iron absorption. Hepcidin – a 25-amino-acid peptide initially identified in human plasma and urine as an anti-microbial molecule [2], [3] and later found to be over-expressed in iron-overloaded mice [4] and in experimental inflammation [4], [5] was recently demonstrated to be the major regulator of intestinal iron absorption, and, more precisely, of iron delivery to the plasma through the modulation of iron egress from cells, especially enterocytes, macrophages and placenta cells [6], [7], [8] (Fig. 1).

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  • Fig. 1. 

    Hepcidin is synthesized by hepatocytes. Hepcidin binding to ferroportin, an iron transporter located at the basolateral part of enterocyte and macrophage membranes, results in internalization and degradation of ferroportin, and then in decreasing cellular iron egress which, in turn, leads to decrease systemic iron bioavailability and, then, to decreased parenchymal iron stores and to increased macrophagic iron stores. Tf, transferrin.

Hepcidin interacts directly with the iron export molecule, ferroportin, causing its internalization and subsequent degradation, blocking iron release from cells to plasma [9]. Hepcidin is mainly produced by hepatocytes making the liver the conductor of the regulation of systemic iron homeostasis, although there is some evidence that adipocytes [10] and macrophages [11] can also synthetize hepcidin, but at a lower level.

Hepcidin production is up-regulated by body iron excess and inflammation [4], [5], [12] and downregulated by anemia and hypoxia [12]. Such a regulation occurs mainly at the transcriptional level through several regulatory pathways (Fig. 2) [13]:

–The bone morphogenic protein (BMP) pathway has emerged as an important piece of the puzzle [14]. As members of the TGFβ superfamily, plasmatic BMPs are involved in a number of important biological processes including cell proliferation, differentiation and apoptosis. Their binding to the BMP 1 and 2 receptors activates the phosphorylation of SMADs 1, 5 and 8 (R-SMAD), which then interact with SMAD 4. The complex migrates into the nucleus and, by binding to specific DNA motifs in the hepcidin promoter, regulates hepcidin gene transcription [15]. BMPs 2, 4 and 9 have a strong stimulatory effect on hepcidin synthesis [16]. The hemojuvelin (HJV), HFE and transferrin receptor 2 (TfR2) proteins – whose mutation results in human haemochromatosis – may modulate hepcidin expression likely by interacting along the BMP pathway. HJV, a member of the repulsive guidance molecule family proteins, is a glycosylphosphatidylinositol (GPI)-linked membrane protein mainly expressed in the liver and skeletal muscle [17]. The BMP pathway is activated by the interaction of GPI-anchored HJV with the type 1 BMP receptor. This activation is counteracted by the soluble form of HJV. Mechanisms involved in the modulation of hepcidin expression related to TfR2 and HFE are not fully understood. It is likely that HFE acts through its binding to TFR1 and TfR2 [18]. The role of ERK1/ERK2 and p38 MAP kinases in the signal transduction related to TfR2 has also been suggested [19].

–Another pathway whose activation leads to increased hepcidin production independently of HJV corresponds to the STAT3 pathway which is activated by interleukin 6 (IL-6) through JAK1/2 [20], [21] and results in hepcidin transcription either directly or through the interaction between STAT 3 and SMAD [15].

–The hepatic-enriched transcriptional factor C/EBPα involved in the hepatic differentiation process has also been demonstrated to be active in the control of hepcidin transcription [22].

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  • Fig. 2. 

    Schematic presentation of pathways regulating transcription of the hepcidin gene [1]. The bone morphogenic protein (BMP) pathway involves a complex consisting of BMP receptors I and II (BMPR-I and BMPR-II), GPI-anchored hemojuvelin (HJV) and BMPs which activate SMAD 1, 5 and 8 phosphorylation. Phosphorylated SMADs 1, 5 and 8 bind to SMAD 4 and then migrate into the nucleus where they activate hepcidin transcription [2]. The STAT 3 pathway is activated through JAK1/2 by the binding of IL-6 to its receptor at cell surface. Whether STAT 3 acts on hepcidin transcription only directly or also through the SMAD complex remains to be elucidated [3]. The complex associating transferrin (Tf), transferrin receptor 1 (TfR-1) and HFE as well as the binding of holotransferrin to transferrin receptor 2 (TfR-2) could also lead to hepcidin transcription by several putative mechanisms. Solid lines: known pathways – dotted lines: hypothetic pathways. From Anderson et al. [13].

Although huge advances have been made in our understanding of iron metabolism and its regulation, much remains to be learned. How the liver is informed about body iron requirements is still unknown. Diferric transferrin has emerged as the potential signaling molecule related to iron stores [23] whilst hypoxia-inducible factor (HIF), transcriptional factor and the plasmatic growth differentiation factor 15 (GDF15), a member of the TGFβ superfamily, have been proposed as signaling hypoxia and erythroid activity, respectively [24].

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3. Classification of hepatic iron storage disorders: a new vision 

Thanks to molecular genetics tools, a distinction between genetic and acquired hepatic iron-overload can be currently more easily made, even if environmental factors may be involved in hereditary iron storage disorders and genetic factors are likely to modulate iron burden in acquired iron-overload diseases.

Genetic iron-overload disorders may be divided into haemochromatotic and non-haemochromatotic forms according to patho-physiological and phenotypic criteria (Table 1).

Table 1. Main characteristics of genetic iron overload disorders
Genetic iron-overload diseaseGeneChromosomeTransmissionOnsetClinical expression
Haemochromatotic
HFEHFE6p21.3RecessiveLateArticular and hepatic
HemojuvelinHJV1p21RecessiveEarlyCardiac and endocrine
HepcidinHAMP19q13.1RecessiveEarlyCardiac and endocrine
Transferrin receptor 2TfR27q22RecessiveLateHepatic
Ferroportin disease type BSLC40A12q32DominantLateArticular and hepatic
Nonhaemochromatotic
Ferroportin disease type ASLC40A12q32DominantLateRare
A(hypo)ceruloplasminemiaCeruloplasmin3q23-q25RecessiveLateNeurological
A(hypo)transferrinemiaTransferrin3q21RecessiveEarlyHematological

Haemochromatosis should currently refer to hereditary iron-overload disorders presenting with a definite and common phenotype characterized by normal erythropoiesis, increased transferrin saturation and parenchymal distribution of iron deposition, and related to an inaccurate production and/or regulation and/or activity of hepcidin [25] (Fig. 3, Fig. 4). Based upon such a definition, haemochromatosis consists of five different genetic disorders.

–By far, the most common is HFE haemochromatosis (type 1 haemochromatosis) that represents more than 90% of iron-overload syndromes of genetic origin. It corresponds to the classical HLA-linked haemochromatosis and is transmitted as an autosomal recessive trait.

–The other forms are much less frequent. Some may cause early and severe iron burden. The discovery of their causal mutations has played a crucial role in furthering our understanding of iron metabolism:
∘Juvenile haemochromatosis (type 2 haemochromatosis) is related to mutations on either the hemojuvelin (HJV) gene (type 2A) [17] or the hepcidin (HAMP) gene (type 2B) [17] and usually results in a severe autosomal recessive disorder of early onset,

∘Transferrin receptor 2 (TFR2) haemochromatosis (type 3 haemochromatosis) is related to mutations in the TFR2 gene [26] and is responsible for an autosomal recessive disorder very similar to HFE haemochromatosis,

∘Finally, type B ferroportin disease (see below) may rarely result in a typical haemochromatotic phenotype [27].


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  • Fig. 3. 

    Schematical patho-physiology of parenchymal iron-overload in haemochromatosis. Defective production, regulation or effect of hepcidin related to mutations in the HFE, hemojuvelin, transferrin receptor 2 or hepcidin gene (as roughly indicated by a cross) opens iron egress from intestinal and macrophagic cells. This results in increased iron influx into plasma and, then, in increased transferrin (Tf) saturation and in the production of a special form of iron, non-transferrin-bound iron (NTBI), which is avidly taken up by parenchymas.

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  • Fig. 4. 

    Natural course, phenotype and penetrance of C282Y homozygosity. A 5-stage classification was recently proposed by the French Haute Autorité de Santé (HAS) [84] as the basis for its clinical recommendations on the management of HFE haemochromatosis: stage 0 corresponds to unexpressed genetic predisposition, stage 1 to increased transferrin saturation (>45%) only, stage 2 to increase in both transferrin saturation and serum ferritin (>200μg/L in women and >300μg/L in men), stage 3 to symptoms resulting in impaired functional prognosis (chronic fatigue and arthralgias) and stage 4 to organ damage with life-threatening disorders, especially diabetes, cardiomyopathy, liver cirrhosis and hepatocellular carcinoma (HCC). The approximate percentage of patients at each stage (%) clearly indicates incomplete penetrance of C282Y homozygosity.

Nonhaemochromatotic iron-overload disorders include:

–The autosomal dominant type A ferroportin disease – ill-named as type 4 haemochromatosis – caused by mutations in the ferroportin (SLC40A1) gene and presenting with mesenchymal iron-overload and low or slightly elevated transferrin saturation [27],

–Two exceptional disorders transmitted as autosomal recessive traits
∘hereditary a(hypo)ceruloplasminemia [28], [29] related to mutations in the ceruloplasmin gene and responsible for haematological (microcytic anemia), neurological (retinal degeneration, extrapyramidal syndrome, cerebellar ataxia, and dementia) and metabolic (diabetes) symptoms and both low-serum iron and transferrin saturation,

∘hereditary a(hypo)transferrinemia [30] related to mutations in the transferrin gene and expressed as severe iron deficiency anemia and parenchymal iron-overload, and


–Some cases of mutations in the DMT1 (divalent metal transporter) gene [31], [32], [33] also resulting in both microcytic anemia and hepatic iron excess.

Acquired iron-overload disorders correspond to a more heterogeneous group of diseases:

–Chronic excessive iron supply may result in a clinically significant increase of hepatic iron stores as recently reported in elite road cyclists [34].

–Haematological disorders including thalassemia, myelodysplastic syndromes, congenital dyserythropoietic anemias, red cell enzyme deficiencies, sickle cell disease and other haemoglobinopathies are responsible for hepatic iron excess through both (i) the downregulation of hepcidin production by an erythroid factor – such as GDF15 – produced in excess [24] and (ii) multiple blood transfusions [35],

–Chronic liver diseases may lead to an increase of hepatic iron stores through both the liver damage itself and its cause.
∘The phagocytic process secondary to chronic necro-inflammatory hepatocytic damage may result in iron redistribution toward Kupffer cells, but hepatic iron excess remains usually slight. In end-stage liver cirrhosis, additional and sometimes massive parenchymal iron-overload may occur [36], [37] in relation to decreased transferrin and hepcidin synthesis secondary to hepatic insufficiency [38]. This leads to a pseudo-haemochromatotic cirrhosis pattern with increased transferrin saturation and ferritin levels whose diagnosis can be made on (i) the absence of haemochromatosis mutation, (ii) the heterogeneous distribution of iron throughout the liver at MRI [39], and (iii) the absence of iron deposits within fibrous septa at liver biopsy [39].

∘More specific mechanisms resulting in the development of hepatic iron excess have been suggested in chronic hepatitis C and in steatohepatitis. It has been proposed that interaction between the hepatitis C virus (HCV) and HFE might explain, at least partly, HCV-associated liver siderosis [40]. Alcohol has been shown to have an inhibitory effect on hepcidin synthesis which could participate in alcohol-related liver siderosis [41]. With respect to non-alcoholic steatohepatitis, data are contradictory. On one hand, an association between unexplained, mixed and mild hepatic iron-overload and various metabolic abnormalities including moderate overweight with visceral distribution of fat, high blood pressure, dyslipidemia and abnormal glucose metabolism, has been described under the name of insulin resistance-associated iron-overload or dysmetabolic iron-overload syndrome (DIOS) [42], [43]. On the other hand, hepcidin synthesis by the visceral adipose tissue resulting in low iron stores has been reported in morbid obesity [10], and hyperhepcidinuria has been documented in patients with DIOS by Loréal et al. quoted in [44]. This could suggest a hepcidin-resistance state in subjects with DIOS.


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4. Expressivity of iron-overload syndromes: the lesson from haemochromatosis 

The discovery of the HFE gene [1] has allowed for large genotypic/phenotypic correlation studies [45], [46], [47], [48]. These studies demonstrated that, contrary to previous thought, C282Y homozygosity, the common genotype associated with more than 90% of HFE haemochromatosis cases in European populations, had lower penetrance than expected (Fig. 4). According to series, gender and disease definition, biochemical expressivity ranged between 50% and 95% whilst clinical penetrance was calculated as 1% when considering the full blown disorder [46], as 11% when considering liver cirrhosis [48], and between 10% and 50% when considering clinical symptoms including fatigue and arthralgias [47]. Moreover, all subjects with biochemical expression were found not to further develop clinical symptoms [49]. Then, the question arose why the penetrance of HFE haemochromatosis had such a large range and was so unforeseeable. Recent studies focusing on environmental and genetic modifiers of HFE haemochromatosis launched the concept that modifying factors could be different according to the criteria used for defining haemochromatosis penetrance, and suggested to distinguish penetrance of iron burden as assessed on serum ferritin levels, liver iron concentration and/or the amount of removed iron and clinical penetrance based upon the type and severity of clinical symptoms (liver damage, arthropathy, abnormalities in glucose metabolism…) [50].

4.1. Modifiers of iron burden 

4.1.1. Environmental modifiers 

Exposure to every factor susceptible to modify iron metabolism should theoretically influence the amount of body iron excess. In fact, there is little evidence for a correlation between such factors and the degree of iron burden probably because (i) iron accumulation is a long process, (ii) factors exerting opposite effects on iron stores often coexist or follow one another over time, and (iii) in vivo methods assess the absorption of non-haem iron and not that of haem iron which is significantly involved in the development of iron excess in haemochromatosis.

4.1.1.1. Diet 

A significant but weak correlation was found between serum ferritin levels and haem dietary intake in haemochromatotic subjects [51], especially in menopausal women [52]. In addition, the amount of iron to be removed annually in order to maintain low body iron stores has been shown to be slightly lower in haemochromatotic patients who regularly drink tea – which decreases iron absorption – than in those who do not [53]. These data suggest that diet has a relatively modest influence on iron stores in the haemochromatotic patient.

4.1.1.2. Alcohol 

Alcohol is responsible for a decrease of hepcidin transcription (i) directly by decreasing the expression and/or activity of the transcriptional factor C/EBPα [54], likely through its effect on ROS production [55], [56], and (ii) indirectly due to hepatic insufficiency secondary to the chronic liver disease it leads to [38]. Then, on the long-term, chronic alcohol consumption should result in aggravating iron burden.

4.1.1.3. Blood donation 

Barton et al. [57] reported that body iron stores as measured by phlebotomies were not different in C282Y homozygotes whether they had been previously blood donors or not. This suggests that post-donation enhancement of intestinal iron absorption could compensate infrequent blood loss.

4.1.1.4. Metabolic syndrome 

In a genotypic/phenotypic correlation study performed in a large French general population, under-expression of C282Y homozygosity – as judged by transferrin saturation – was found to be associated with obesity [58]. This, together with the demonstration that visceral adipose tissue of obese patients was able to produce hepcidin [10], supports that, in haemochromatotic patients with increased fat mass, iron burden could be decreased thanks to extra-hepatic production of hepcidin [44].

4.1.1.5. Inflammation 

Acute inflammation was shown to decrease transferrin saturation in C282Y homozygotes. Whether chronic inflammatory state may result in decreasing iron burden was addressed by Beutler et al. [59]. These authors measured the levels of C-reactive protein and of IL-6 in C282Y homozygotes and failed to find any relationship between iron burden as assessed by phlebotomy and the levels of inflammatory markers.

4.1.1.6. Drugs 

A recent study showed that the administration of a proton-pump inhibitor resulted in decreasing phlebotomy requirements in C282Y homozygous patients, probably by suppressing gastric acidity which is necessary for iron absorption [60]. Otherwise, nifedipine, a L-type calcium channel blocker, has been proposed as a putative pharmacological agent for the treatment of iron-overload because of its effect on DMT1 resulting in modulating iron mobilisation from the liver and increasing urinary iron excretion [61].

4.1.1.7. Helicobacter pylori infection 

Although Helicobacter pylori infection is associated with iron deficiency and impairs response to iron therapy, the level of iron burden was not different in C282Y homozygotes with and without antibodies against helicobater pylori [62].

4.1.2. Genetic modifiers 
4.1.2.1. Gender-associated factors 

It is widely accepted that, in haemochromatosis, iron burden is usually lower in women than in men. This was demonstrated by Moirand et al. [63] who compared age-matched male and female haemochromatotics, and further confirmed by phenotypic/genotypic studies [45], [46], [47], [48]. Whether this protective effect of gender is only related to physiological events remains debated. Indeed, if early menopause and hysterectomy are associated with either earlier or increased iron burden in haemochromatotic women, no significant correlation has been found between the number of pregnancies and body iron stores [63].

4.1.2.2. Iron metabolism-related genes 

By showing correlated serum ferritin levels in fraternal and identical siblings, early family studies have suggested that such modifiers could be involved in the penetrance of HFE haemochromatosis. Recent studies have focused on genes involved in the regulation of hepcidin production and reported that (i) co-inheritance of mutations in the hepcidin gene [64], [65] or in the HJV gene [66] together with C282Y homozygosity was associated with more severe iron burden of earlier onset and (ii) common variants in the BMP pathway were associated with iron burden [67], which suggests that full expression of HFE haemochromatosis is linked to abnormal hepatic expression of hepcidin, through both impairment in HFE function and functional modulation in the BMP pathway. It is likely that forthcoming genotypic studies using high output genotyping will address not only the regulatory pathways of hepcidin synthesis but also all genes involved in cellular iron metabolism, including iron transporter genes.

4.2. Modifiers of organ damage 

Alcohol acts not only on the level of iron burden but also on the severity of liver disease in HFE haemochromatosis, since, for the same level of hepatic iron stores, haemochromatotic patients with excessive alcohol intake are more prone to develop early and severe liver fibrosis than those who are either abstinent or moderate drinkers [68], [69]. Similarly, overweight and steatosis have been reported to be associated with an increased risk of fibrosis in C282Y homozygotes [70] despite obesity that could result in lowering iron burden in these patients [44].

It is likely that, besides these acquired factors, genetic modifiers may modulate the degree of organ damage. Recently, Valenti et al. reported that the superoxide dismutase genotype affected the risk of cardiomyopathy [71] and Osterreicher et al. found that TGFb1 codon 25 gene polymorphism was associated with cirrhosis in patients with haemochromatosis [72]. Candidate genes are not only those involved in regulating oxidative stress and fibrogenesis, but also all those involved in proliferation and apoptosis balances, tissue repair and specific organ metabolisms [50].

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5. Management of hepatic iron-overload disorders: easier and promising 

Advances in imaging – allowing for a non-invasive diagnosis of hepatic iron-overload – and in molecular genetics – allowing for identification of most mutations involved in hereditary iron-overload disorders – have dramatically simplified the diagnostic procedures in front of the suspicion of iron excess, while the availability of new oral chelators, the discovery of hepcidin and our better understanding of iron metabolism are opening up perspectives on future therapies.

5.1. Diagnosis 

The first step consists of (i) evaluating the clinical expression of the putative iron-overload syndrome on the basis of age and of the type (hepatic/extra-hepatic) and severity of symptoms and (ii) assessing serum ferritin, knowing that frequent conditions are susceptible to increase serum ferritin levels in the absence of elevated body iron stores, through either cell necrosis (hepatitis…) or increased ferritin synthesis (acute and chronic inflammation, chronic alcohol consumption, insulin resistance…).

The second step consists of assessing transferrin saturation knowing that (i) normal transferrin saturation allows to rule out haemochromatosis except in case of coexistent inflammatory syndrome [73] or obesity [58], and (ii) increased transferrin saturation is not specific of haemochromatosis, but can be related to laboratory error – which implies having a confirmation of the test at least once –, to excessive iron release from damaged cells (i.e. hepatitis, haemolysis…) or to decreased synthesis of transferrin secondary to hepatocellular insufficiency. Then,

–If transferrin saturation is increased and confirmed as elevated at least once, HFE testing is indicated:
∘The finding of C282Y homozygosity allows to establish the diagnosis of HFE haemochromatosis. Then, disease stage has to be assessed and, according to stage, either follow-up or venesection therapy has to be proposed (Fig. 4).

∘The finding of any other HFE genotype must be interpreted with caution since (i) compound C282Y/H63D heterozygosity does not result in clinically relevant iron-overload, even if 20–25% of compound heterozygotes present with mild increase in transferrin saturation and 10% with slight hepatic iron excess [74], and (ii) H63D homozygosity, C282Y heterozygosity and H63D heterozygosity may never explain abnormal serum iron and ferritin levels in the absence of an associated cause of impaired iron metabolism. Then, in case of increased transferrin saturation in a non-C282Y homozygous subject, non-HFE haemochromatosis becomes an option once (i) liver disease and haematological disorders have been ruled out and (ii) iron excess has been proven by direct assessment, i.e. by MRI or liver biopsy. HJV or HAMP juvenile haemochromatosis will be considered first in young patients with severe iron excess resulting in heart and endocrine symptoms whilst type B ferroportin disease, TfR2 haemochromatosis, and rare mutations in the HFE gene will be first sought for in case of mild and late symptoms, mainly related to joints and liver. However, late onset of juvenile haemochromatosis has been reported as well as early and severe disease in transferrin receptor 2 haemochromatosis. In any case, documenting serum iron and ferritin levels in first-degree relatives may be helpful.


–If transferrin saturation is either slightly increased, normal or low, it is mandatory to answer the question whether hyperferritinemia corresponds to iron excess or not. This can be done by either (i) MRI which enables the assessment of liver iron concentration provided the apparatus has been well calibrated and a validated algorithm is used (http://www.radio.univ-rennes1.fr) [39], and allows for evaluation of iron distribution in the liver, spleen, pancreas and bone marrow [75], (ii) liver biopsy which also provides diagnostic information regarding associated liver damage (steatosis or steatohepatitis, degree of fibrosis…) [76], or (iii) retrospectively by phlebotomy. In this setting, the most common diagnosis is that of DIOS. In the absence of metabolic abnormalities and/or confronted with a significant iron-overload (LIC>150μmol/g and/or removed iron >2,5g), rare genetic causes of iron excess may be sought for, especially (i) type A ferroportin disease responsible for mesenchymal iron excess which results in a suggestive low MRI signal in both the liver and spleen [75] and is usually associated with no or mild symptoms, even in the presence of severe iron-overload [77], and (ii) hereditary a(hypo)ceruloplasminemia, the only systemic iron-overload syndrome resulting in neurological symptoms (extrapyramidal syndrome, retinal degeneration, cerebellar ataxia, dementia…), which is easily diagnosed by the finding of either undetectable or low-serum ceruloplasmin levels [28], [29].

Indication for liver biopsy in the management of patients with hepatic iron-overload is currently limited. In C282Y homozygotes, liver biopsy is no longer necessary except for grading hepatic fibrosis and, if necessary, searching for associated lesions. Guyader et al. [78] demonstrated that, in C282Y homozygotes, when the liver was not clinically enlarged AND serum ferritin level was lower than 1000ng/ml AND serum AST level was normal, there was never significant liver fibrosis found. On the contrary, when one, two or all these conditions were not met, there was a significant risk of fibrosis. The question whether fibrosis was susceptible to regress or not with venesection therapy was recently addressed by Falize et al. [79] in 36 C282Y homozygotes presenting with severe fibrosis on their initial liver biopsy. These authors demonstrated that fibrosis regressed in 69% of patients with initial bridging fibrosis and in 35% of patients with initial cirrhosis. In addition, they proposed a predictive index for fibrosis regression based upon gammaglobulins, platelet count and prothrombin activity. When non-invasive predictive tests of liver fibrosis–including biochemical markers and elastometry – are applied and validated in C282Y homozygotes, it is likely that indications for liver biopsy for fibrosis assessment will become anecdotical. In non C282Y homozygotes, indication for liver biopsy may remain for both diagnostic and prognostic purposes, especially in patients with significant (i.e. LIC>150μmol/g – N<36) iron-overload of unknown origin or in those with DIOS presenting with increased serum hyaluronate [80].

5.2. Treatment 

Venesection therapy remains the standard treatment for HFE, non-HFE haemochromatosis and acquired iron-overload conditions unrelated to haematological disorders. Reducing iron intake does not seem to be useful. Nutritional advice can only advocate a balanced diet with low alcohol intake, no excessive vitamin C supplementation and, possibly, consumption of tea. Despite the risk of anemia, venesection therapy remains the usual treatment in type A ferroportin disease. In other forms of iron-overload, phlebotomies are contra-indicated. Subcutaneous infusions of desferrioxamine have been reported to be efficient in individual cases of aceruloplasminemia [81], [82] and, together with deferiprone (CP 20 or Ferriprox™), have been the only means to reduce iron burden in iron-loading anemias. Recently, a new oral chelator, deferasirox (ICL670 or Exjade™), a tridented triazole component, was launched. In thalassemic patients, at a dosage of 20–30mg/kg/day, it was found as efficient as desferrioxamine and well tolerated despite the report of gastro-intestinal symptoms in 25% of patients and a mild increase of serum creatinine in 33% [83]. In most cases, these side-effects were benign and compatible with the continuation of therapy. Deferasirox has become the treatment of choice of iron-loading anemias. If its long-term tolerance is confirmed to be satisfactory, it could be an adjunct therapy to and, even, replace venesection therapy in haemochromatosis.

It is likely that, in the near future, pharmacological agents interacting with hepcidin production will make possible to treat hepcidin deficiency in haemochromatosis and hepcidin excess in inflammatory anemia. Pharmacological manipulation of iron transport molecules using specific (ant)agonists will make it possible to target iron metabolism abnormalities with precision. Besides these therapeutic challenges, there remains a genetic challenge consisting of the identification of genes modulating iron burden and the consequent organ damage, and their application to predictive medicine.

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References 

  1. Feder JN, Gnirke A, Thomas W, Tsuchihashi Z, Ruddy DA, Basava A, et al. A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis. Nat Genet. 1996;13:399–408
  2. Krause A, Neitz S, Magert HJ, Schulz A, Forssmann WG, Schulz-Knappe P, et al. LEAP-1, a novel highly disulfide-bonded human peptide, exhibits antimicrobial activity. FEBS Lett. 2000;480:147–150
  3. Park CH, Valore EV, Waring AJ, Ganz T. Hepcidin, a urinary antimicrobial peptide synthesized in the liver. J Biol Chem. 2001;276:7806–7810
  4. Pigeon C, Ilyin G, Courselaud B, Leroyer P, Turlin B, Brissot P, et al. A new mouse liver-specific gene, encoding a protein homologous to human antimicrobial peptide hepcidin, is overexpressed during iron overload. J Biol Chem. 2001;276:7811–7819
  5. Nemeth E, Valore EV, Territo M, Schiller G, Lichtenstein A, Ganz T. Hepcidin, a putative mediator of anemia of inflammation, is a type II acute-phase protein. Blood. 2003;101:2461–2463
  6. Ganz T. Molecular control of iron transport. J Am Soc Nephrol. 2007;18:394–400
  7. Loreal O, Haziza-Pigeon C, Troadec MB, Detivaud L, Turlin B, Courselaud B, et al. Hepcidin in iron metabolism. Curr Protein Pept Sci. 2005;6:279–291
  8. Nicolas G, Bennoun M, Devaux I, Beaumont C, Grandchamp B, Kahn A, et al. Lack of hepcidin gene expression and severe tissue iron overload in upstream stimulatory factor 2 (USF2) knockout mice. Proc Natl Acad Sci USA. 2001;98:8780–8785
  9. Nemeth E, Tuttle MS, Powelson J, Vaughn MB, Donovan A, Ward DM, et al. Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. Science. 2004;306:2090–2093
  10. Bekri S, Gual P, Anty R, Luciani N, Dahman M, Ramesh B, et al. Increased adipose tissue expression of hepcidin in severe obesity is independent from diabetes and NASH. Gastroenterology. 2006;131:788–796
  11. Peyssonnaux C, Zinkernagel AS, Datta V, Lauth X, Johnson RS, Nizet V. TLR4-dependent hepcidin expression by myeloid cells in response to bacterial pathogens. Blood. 2006;107:3727–3732
  12. Nicolas G, Chauvet C, Viatte L, Danan JL, Bigard X, Devaux I, et al. The gene encoding the iron regulatory peptide hepcidin is regulated by anemia, hypoxia, and inflammation. J Clin Invest. 2002;110:1037–1044
  13. Anderson GJ, Darshan D, Wilkins SJ, Frazer DM. Regulation of systemic iron homeostasis: how the body responds to changes in iron demand. Biometals. 2007;20:665–674
  14. Babitt JL, Huang FW, Wrighting DM, Xia Y, Sidis Y, Samad TA, et al. Bone morphogenetic protein signaling by hemojuvelin regulates hepcidin expression. Nat Genet. 2006;38:531–539
  15. Wang RH, Li C, Xu X, Zheng Y, Xiao C, Zerfas P, et al. A role of SMAD4 in iron metabolism through the positive regulation of hepcidin expression. Cell Metab. 2005;2:399–409
  16. Truksa J, Peng H, Lee P, Beutler E. Bone morphogenetic proteins 2, 4, and 9 stimulate murine hepcidin 1 expression independently of Hfe, transferrin receptor 2 (Tfr2), and IL-6. Proc Natl Acad Sci USA. 2006;103:10289–10293
  17. Papanikolaou G, Samuels ME, Ludwig EH, MacDonald ML, Franchini PL, Dube MP, et al. Mutations in HFE2 cause iron overload in chromosome 1q-linked juvenile haemochromatosis. Nat Genet. 2004;36:77–82
  18. Goswami T, Andrews NC. Hereditary haemochromatosis protein, HFE, interaction with transferrin receptor 2 suggests a molecular mechanism for mammalian iron sensing. J Biol Chem. 2006;281:28494–28498
  19. Calzolari A, Raggi C, Deaglio S, Sposi NM, Stafsnes M, Fecchi K, et al. TfR2 localizes in lipid raft domains and is released in exosomes to activate signal transduction along the MAPK pathway. J Cell Sci. 2006;119:4486–4498
  20. Heinrich PC, Behrmann I, Haan S, Hermanns HM, Muller-Newen G, Schaper F. Principles of interleukin (IL)-6-type cytokine signalling and its regulation. Biochem J. 2003;374:1–20
  21. Verga Falzacappa MV, Vujic Spasic M, Kessler R, Stolte J, Hentze MW, Muckenthaler MU. STAT3 mediates hepatic hepcidin expression and its inflammatory stimulation. Blood. 2007;109:353–358
  22. Courselaud B, Pigeon C, Inoue Y, Inoue J, Gonzalez FJ, Leroyer P, et al. C/EBPalpha regulates hepatic transcription of hepcidin, an antimicrobial peptide and regulator of iron metabolism. Cross-talk between C/EBP pathway and iron metabolism. J Biol Chem. 2002;277:41163–41170
  23. Lin L, Valore EV, Nemeth E, Goodnough JB, Gabayan V, Ganz T. Iron transferrin regulates hepcidin synthesis in primary hepatocyte culture through hemojuvelin and BMP2/4. Blood. 2007;110:2182–2189
  24. Tanno T, Bhanu NV, Oneal PA, Goh SH, Staker P, Lee YT, et al. High levels of GDF15 in thalassemia suppress expression of the iron regulatory protein hepcidin. Nat Med. 2007;13:1096–1101
  25. Pietrangelo A. Haemochromatosis: an endocrine liver disease. Hepatology. 2007;46:1291–1301
  26. Camaschella C, Roetto A, Cali A, De Gobbi M, Garozzo G, Carella M, et al. The gene TFR2 is mutated in a new type of haemochromatosis mapping to 7q22. Nat Genet. 2000;25:14–15
  27. Pietrangelo A. Non-HFE haemochromatosis. Hepatology. 2004;39:21–29
  28. Kono S, Suzuki H, Takahashi K, Takahashi Y, Shirakawa K, Murakawa Y, et al. Hepatic iron overload associated with a decreased serum ceruloplasmin level in a novel clinical type of aceruloplasminemia. Gastroenterology. 2006;131:240–245
  29. Miyajima H, Takahashi Y, Kono S. Aceruloplasminemia, an inherited disorder of iron metabolism. Biometals. 2003;16:205–213
  30. Beutler E, Gelbart T, Lee P, Trevino R, Fernandez MA, Fairbanks VF. Molecular characterization of a case of atransferrinemia. Blood. 2000;96:4071–4074
  31. Beaumont C, Delaunay J, Hetet G, Grandchamp B, de Montalembert M, Tchernia G. Two new human DMT1 gene mutations in a patient with microcytic anemia, low ferritinemia, and liver iron overload. Blood. 2006;107:4168–4170
  32. Iolascon A, d’Apolito M, Servedio V, Cimmino F, Piga A, Camaschella C. Microcytic anemia and hepatic iron overload in a child with compound heterozygous mutations in DMT1 (SCL11A2). Blood. 2006;107:349–354
  33. Mims MP, Guan Y, Pospisilova D, Priwitzerova M, Indrak K, Ponka P, et al. Identification of a human mutation of DMT1 in a patient with microcytic anemia and iron overload. Blood. 2005;105:1337–1342
  34. Deugnier Y, Loreal O, Carre F, Duvallet A, Zoulim F, Vinel JP, et al. Increased body iron stores in elite road cyclists. Med Sci Sports Exerc. 2002;34:876–880
  35. Nemeth E, Ganz T. Hepcidin and iron-loading anemias. Haematologica. 2006;91:727–732
  36. Deugnier Y, Turlin B, le Quilleuc D, Moirand R, Loreal O, Messner M, et al. A reappraisal of hepatic siderosis in patients with end-stage cirrhosis: practical implications for the diagnosis of haemochromatosis. Am J Surg Pathol. 1997;21:669–675
  37. Ludwig J, Hashimoto E, Porayko MK, Moyer TP, Baldus WP. Hemosiderosis in cirrhosis: a study of 447 native livers. Gastroenterology. 1997;112:882–888
  38. Detivaud L, Nemeth E, Boudjema K, Turlin B, Troadec MB, Leroyer P, et al. Hepcidin levels in humans are correlated with hepatic iron stores, hemoglobin levels, and hepatic function. Blood. 2005;106:746–748
  39. Gandon Y, Olivie D, Guyader D, Aube C, Oberti F, Sebille V, et al. Non-invasive assessment of hepatic iron stores by MRI. Lancet. 2004;363:357–362
  40. Pietrangelo A. Haemochromatosis gene modifies course of hepatitis C viral infection. Gastroenterology. 2003;124:1509–1523
  41. Harrison-Findik DD. Role of alcohol in the regulation of iron metabolism. World J Gastroenterol. 2007;13:4925–4930
  42. Mendler MH, Turlin B, Moirand R, Jouanolle AM, Sapey T, Guyader D, et al. Insulin resistance-associated hepatic iron overload. Gastroenterology. 1999;117:1155–1163
  43. Moirand R, Mortaji AM, Loreal O, Paillard F, Brissot P, Deugnier Y. A new syndrome of liver iron overload with normal transferrin saturation. Lancet. 1997;349:95–97
  44. Laine F, Deugnier Y. Increased expression of hepcidin in obese patients: impact on phenotypic expression of haemochromatosis and pathophysiology of dysmetabolic iron overload syndrome. Gastroenterology. 2006;131:2028
  45. Adams PC, Reboussin DM, Barton JC, McLaren CE, Eckfeldt JH, McLaren GD, et al. Haemochromatosis and iron-overload screening in a racially diverse population. N Engl J Med. 2005;352:1769–1778
  46. Beutler E, Felitti VJ, Koziol JA, Ho NJ, Gelbart T. Penetrance of 845G–> A (C282Y) HFE hereditary haemochromatosis mutation in the USA. Lancet. 2002;359:211–218
  47. Deugnier Y, Jouanolle AM, Chaperon J, Moirand R, Pithois C, Meyer JF, et al. Gender-specific phenotypic expression and screening strategies in C282Y-linked haemochromatosis: a study of 9396 French people. Br J Haematol. 2002;118:1170–1178
  48. Olynyk JK, Cullen DJ, Aquilia S, Rossi E, Summerville L, Powell LW. A population-based study of the clinical expression of the haemochromatosis gene. N Engl J Med. 1999;341:718–724
  49. Beutler E. Iron storage disease: facts, fiction and progress. Blood Cells Mol Dis. 2007;39:140–147
  50. Pietrangelo A. The penetrance of haemochromatosis: mice to the rescue. Gastroenterology. 2007;132:805–808
  51. van der AD, Peeters PH, Grobbee DE, Roest M, Voorbij HA, van der Schouw YT. HFE genotypes and dietary heme iron: no evidence of strong gene-nutrient interaction on serum ferritin concentrations in middle-aged women. Nutr Metab Cardiovasc Dis. 2006;16:60–68
  52. Cade JE, Moreton JA, O’Hara B, Greenwood DC, Moor J, Burley VJ, et al. Diet and genetic factors associated with iron status in middle-aged women. Am J Clin Nutr. 2005;82:813–820
  53. Kaltwasser JP, Werner E, Schalk K, Hansen C, Gottschalk R, Seidl C. Clinical trial on the effect of regular tea drinking on iron accumulation in genetic haemochromatosis. Gut. 1998;43:699–704
  54. Bridle K, Cheung TK, Murphy T, Walters M, Anderson G, Crawford DG, et al. Hepcidin is down-regulated in alcoholic liver injury: implications for the pathogenesis of alcoholic liver disease. Alcohol Clin Exp Res. 2006;30:106–112
  55. Harrison-Findik DD, Klein E, Crist C, Evans J, Timchenko N, Gollan J. Iron-mediated regulation of liver hepcidin expression in rats and mice is abolished by alcohol. Hepatology. 2007;46:1879–1885
  56. Harrison-Findik DD, Schafer D, Klein E, Timchenko NA, Kulaksiz H, Clemens D, et al. Alcohol metabolism-mediated oxidative stress down-regulates hepcidin transcription and leads to increased duodenal iron transporter expression. J Biol Chem. 2006;281:22974–22982
  57. Barton JC, Preston BL, McDonnell SM, Rothenberg BE. Severity of iron overload in haemochromatosis: effect of volunteer blood donation before diagnosis. Transfusion. 2001;41:123–129
  58. Laine F, Jouannolle AM, Morcet J, Brigand A, Pouchard M, Lafraise B, et al. Phenotypic expression in detected C282Y homozygous women depends on body mass index. J Hepatol. 2005;43:1055–1059
  59. Beutler E, Waalen J, Gelbart T. Chronic inflammation does not appear to modify the homozygous hereditary haemochromatosis phenotype. Blood Cells Mol Dis. 2005;35:326–327
  60. Hutchinson C, Geissler CA, Powell JJ, Bomford A. Proton pump inhibitors suppress absorption of dietary non-haem iron in hereditary haemochromatosis. Gut. 2007;56:1291–1295
  61. Ludwiczek S, Theurl I, Muckenthaler MU, Jakab M, Mair SM, Theurl M, et al. Ca2+ channel blockers reverse iron overload by a new mechanism via divalent metal transporter-1. Nat Med. 2007;13:448–454
  62. Beutler E, Gelbart T. Helicobacter pylori infection and HFE haemochromatosis. Blood Cells Mol Dis. 2006;37:188–191
  63. Moirand R, Adams PC, Bicheler V, Brissot P, Deugnier Y. Clinical features of genetic haemochromatosis in women compared with men. Ann Intern Med. 1997;127:105–110
  64. Jacolot S, Le Gac G, Scotet V, Quere I, Mura C, Ferec C. HAMP as a modifier gene that increases the phenotypic expression of the HFE pC282Y homozygous genotype. Blood. 2004;103:2835–2840
  65. Merryweather-Clarke AT, Cadet E, Bomford A, Capron D, Viprakasit V, Miller A, et al. Digenic inheritance of mutations in HAMP and HFE results in different types of haemochromatosis. Hum Mol Genet. 2003;12:2241–2247
  66. Le Gac G, Scotet V, Ka C, Gourlaouen I, Bryckaert L, Jacolot S, et al. The recently identified type 2A juvenile haemochromatosis gene (HJV), a second candidate modifier of the C282Y homozygous phenotype. Hum Mol Genet. 2004;13:1913–1918
  67. Milet J, Dehais V, Bourgain C, Jouanolle AM, Mosser A, Perrin M, et al. Common variants in the BMP2, BMP4, and HJV genes of the hepcidin regulation pathway modulate HFE haemochromatosis penetrance. Am J Hum Genet. 2007;81:799–807
  68. Fletcher LM, Bridle KR, Crawford DH. Effect of alcohol on iron storage diseases of the liver. Best Pract Res Clin Gastroenterol. 2003;17:663–677
  69. Loréal O, Deugnier Y, Moirand R, Lauvin L, Guyader D, Jouanolle H, et al. Liver fibrosis in genetic haemochromatosis. Respective roles of iron and non-iron-related factors in 127 homozygous patients. J Hepatol. 1992;16:122–127
  70. Powell EE, Ali A, Clouston AD, Dixon JL, Lincoln DJ, Purdie DM, et al. Steatosis is a cofactor in liver injury in haemochromatosis. Gastroenterology. 2005;129:1937–1943
  71. Valenti L, Conte D, Piperno A, Dongiovanni P, Fracanzani AL, Fraquelli M, et al. The mitochondrial superoxide dismutase A16V polymorphism in the cardiomyopathy associated with hereditary haemochromatosis. J Med Genet. 2004;41:946–950
  72. Osterreicher CH, Datz C, Stickel F, Hellerbrand C, Penz M, Hofer H, et al. TGF-beta1 codon 25 gene polymorphism is associated with cirrhosis in patients with hereditary haemochromatosis. Cytokine. 2005;31:142–148
  73. Distante S, Berg JP, Lande K, Haug E, Bell H. HFE gene mutation (C282Y) and phenotypic expression among a hospitalised population in a high prevalence area of haemochromatosis. Gut. 2000;47:575–579
  74. Walsh A, Dixon JL, Ramm GA, Hewett DG, Lincoln DJ, Anderson GJ, et al. The clinical relevance of compound heterozygosity for the C282Y and H63D substitutions in haemochromatosis. Clin Gastroenterol Hepatol. 2006;4:1403–1410
  75. Pietrangelo A, Corradini E, Ferrara F, Vegetti A, De Jong G, Luca Abbati G, et al. Magnetic resonance imaging to identify classic and nonclassic forms of ferroportin disease. Blood Cells Mol Dis. 2006;37:192–196
  76. Deugnier Y, Turlin B. Pathology of hepatic iron overload. World J Gastroenterol. 2007;13:4755–4760
  77. Pietrangelo A. The ferroportin disease. Blood Cells Mol Dis. 2004;32:131–138
  78. Guyader D, Jacquelinet C, Moirand R, Turlin B, Mendler MH, Chaperon J, et al. Noninvasive prediction of fibrosis in C282Y homozygous haemochromatosis. Gastroenterology. 1998;115:929–936
  79. Falize L, Guillygomarc’h A, Perrin M, Laine F, Guyader D, Brissot P, et al. Reversibility of hepatic fibrosis in treated genetic haemochromatosis: a study of 36 cases. Hepatology. 2006;44:472–477
  80. Laine F, Bendavid C, Moirand R, Tessier S, Perrin M, Guillygomarc’h A, et al. Prediction of liver fibrosis in patients with features of the metabolic syndrome regardless of alcohol consumption. Hepatology. 2004;39:1639–1646
  81. Loréal O, Turlin B, Pigeon C, Moisan A, Ropert M, Morice P, et al. Aceruloplasminemia: new clinical, pathophysiological and therapeutic insights. J Hepatol. 2000;36:851–856
  82. Miyajima H, Takahashi Y, Kamata T, Shimizu H, Sakai N, Gitlin JD. Use of desferrioxamine in the treatment of aceruloplasminemia. Ann Neurol. 1997;41:404–407
  83. Cappellini MD, Cohen A, Piga A, Bejaoui M, Perrotta S, Agaoglu L, et al. A phase 3 study of deferasirox (ICL670), a once-daily oral iron chelator, in patients with beta-thalassemia. Blood. 2006;107:3455–3462
  84. Brissot P, de Bels F. Current approaches to the management of haemochromatosis. Hematology. 2006;36–41

☆ The authors declare that they do not have anything to disclose regarding industry funding or conflict of interest with respect to this manuscript.

PII: S0168-8278(08)00061-5

doi:10.1016/j.jhep.2008.01.014

Journal of Hepatology
Volume 48, Supplement 1 , Pages S113-S123, 2008

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