Simultaneous liver iron and fat measures by magnetic resonance imaging in patients with hyperferritinemia.

OBJECTIVE: Hyperferritinemia is frequent in chronic liver diseases of any cause, but the extent to which ferritin truly reflects iron stores is variable. In these patients, both liver iron and fat are found in variable amount and association. Liver biopsy is often required to quantify liver fat and iron, but sampling variability and invasiveness limit its use. We aimed to assess single breath-hold multiecho magnetic resonance imaging (MRI) for the simultaneous lipid and iron quantification in patients with hyperferritinemia. MATERIAL AND METHODS: We compared MRI results for both iron and fat with their respective gold standards - liver iron concentration and computer-assisted image analysis for steatosis on biopsy. We prospectively studied 67 patients with hyperferritinemia and other 10 consecutive patients were used for validation. We estimated two linear calibration equations for the prediction of iron and fat based on MRI. The agreement between MRI and biopsy was evaluated. RESULTS: MRI showed good performances in both the training and validation samples. MRI information was almost completely in line with that obtained from liver biopsy. CONCLUSION: Single breath-hold multiecho MRI is an accurate method to obtain a valuable measure of both liver iron and steatosis in patients with hyperferritinemia.

CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients.

BACKGROUND: Most patients with hereditary hemochromatosis in the Caucasian population are homozygous for the p.C282Y mutation in the HFE gene. The penetrance and expression of hereditary hemochromatosis differ largely among cases of homozygous p.C282Y. Genetic factors might be involved in addition to environmental factors. DESIGN AND METHODS: In the present study, we analyzed 50 candidate genes involved in iron metabolism and evaluated the association between 214 single nucleotide polymorphisms in these genes and three phenotypic outcomes of iron overload (serum ferritin, iron removed and transferrin saturation) in a large group of 296 p.C282Y homozygous Italians. Polymorphisms were tested for genetic association with each single outcome using linear regression models adjusted for age, sex and alcohol consumption. RESULTS: We found a series of 17 genetic variants located in different genes with possible additive effects on the studied outcomes. In order to evaluate whether the selected polymorphisms could provide a predictive signature for adverse phenotype, we re-evaluated data by dividing patients in two extreme phenotype classes based on the three phenotypic outcomes. We found that only a small improvement in prediction could be achieved by adding genetic information to clinical data. Among the selected polymorphisms, a significant association was observed between rs3806562, located in the 5'UTR of CYBRD1, and transferrin saturation. This variant belongs to the same haplotype block that contains the CYBRD1 polymorphism rs884409, found to be associated with serum ferritin in another population of p.C282Y homozygotes, and able to modulate promoter activity. A luciferase assay indicated that rs3806562 does not have a significant functional role, suggesting that it is a genetic marker linked to the putative genetic modifier rs884409. CONCLUSIONS: While our results support the hypothesis that polymorphisms in genes regulating iron metabolism may modulate penetrance of HFE-hereditary hemochromatosis, with emphasis on CYBRD1, they strengthen the notion that none of these polymorphisms alone is a major modifier of the phenotype of hereditary hemochromatosis.

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

Hepcidin 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.

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

BACKGROUND: 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. AIM: To investigate hepcidin regulation by iron in DIOS. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

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

BACKGROUND: 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, 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. DESIGN AND METHODS: 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. RESULTS: 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.

Hepcidin modulation in human diseases: from research to clinic.

By modulating hepcidin production, an organism controls intestinal iron absorption, iron uptake and mobilization from stores to meet body iron need. In recent years there has been important advancement in our knowledge of hepcidin regulation that also has implications for understanding the physiopathology of some human disorders. Since the discovery of hepcidin and the demonstration of its pivotal role in iron homeostasis, there has been a substantial interest in developing a reliable assay of the hormone in biological fluids. Measurement of hepcidin in biological fluids can improve our understanding of iron diseases and be a useful tool for diagnosis and clinical management of these disorders. We reviewed the literature and our own research on hepcidin to give an updated status of the situation in this rapidly evolving field.

Expression of hepcidin and other iron-related genes in type 3 hemochromatosis due to a novel mutation in transferrin receptor-2.

Transferrin receptor-2 (TFR2) regulates hepatic hepcidin secretion and when mutated causes type-3 hemochromatosis. No functional study is available in humans. We studied a 47 year-old woman with hemochromatosis. TFR2 DNA and its hepatic transcript were directly sequenced. Hepatic expression of hepcidin and other iron-related genes were measured by qRT-PCR. Urinary hepcidin was measured at baseline and after an oral iron challenge (ferrous sulfate, 65 mg) by SELDI-TOF-MS. A novel homozygous TFR2 mutation was identified in the splicing donor site of intron 4 (c.614+4 A>G) causing exon 4 skipping. Hepcidin and hemojuvelin expression were markedly reduced. Urinary hepcidin was lower than normal and further decreased after iron challenge. This is the first description of iron-related gene expression profiles in a TFR2 mutated patient. The decreased hepatic and urinary expression of hepcidin and lack of acute response to iron challenge confirms the primary role of TFR2 in iron homeostasis.

Iron metabolism in thalassemia and sickle cell disease.

THERE ARE TWO MAIN MECHANISMS BY WHICH IRON OVERLOAD DEVELOPS IN THALASSEMIAS: increased iron absorption due to ineffective erythropoiesis and blood transfusions. In nontransfused patients with severe thalassemia, abnormal dietary iron absorption increases body iron burden between 2 and 5 g per year. If regular transfusions are required, this doubles the rate of iron accumulation leading to earlier massive iron overload and iron-related damage. Iron metabolism largely differs between thalassemias and sickle cell disease, but chronic transfusion therapy partially normalize many of the disparities between the diseases, making iron overload an important issue to be considered in the management of patients with sickle cell disease too. The present review summarizes the actual knowledge on the regulatory pathways of iron homeostasis. In particular, the data presented indicate the inextricably link between erythropoiesis and iron metabolism and the key role of hepcidin in coordinating iron procurement according to erythropoietic requirement. The role of erythropoietin, hypoxia, erythroid-dependent soluble factors and iron in regulating hepcidin transcription are discussed as well as differences and similarities in iron homeostasis between thalassemia syndromes and sickle cell disease.

Revaluation of clinical and histological criteria for diagnosis of dysmetabolic iron overload syndrome.

AIM: To re-evaluate the diagnostic criteria of insulin resistance hepatic iron overload based on clinical, biochemical and histopathological findings. METHODS: We studied 81 patients with hepatic iron overload not explained by known genetic and acquired causes. The metabolic syndrome (MS) was defined according to ATPIII criteria. Iron overload was assessed by liver biopsy. Liver histology was evaluated by Ishak's score and iron accumulation by Deugnier's score; steatosis was diagnosed when present in >or=5% of hepatocytes. RESULTS: According to transferrin saturation levels, we observed significant differences in the amount of hepatic iron overload and iron distribution, as well as the number of metabolic abnormalities. Using Receiving Operating Curve analysis, we found that the presence of two components of the MS differentiated two groups with a statistically significant different hepatic iron overload (P<0.0001). Patients with >or=2 metabolic alterations and steatosis had lower amount of hepatic iron, lower transferrin saturation and higher sinusoidal iron than patients with <2 MS components and absence of steatosis. CONCLUSION: In our patients, the presence of >or2 alterations of the MS and hepatic steatosis was associated with a moderate form of iron overload with a prevalent sinusoidal distribution and a normal transferrin saturation, suggesting the existence of a peculiar pathogenetic mechanism of iron accumulation. These patients may have the typical dysmetabolic iron overload syndrome. By contrast, patients with transferrin saturation>or=60% had more severe iron overload, few or no metabolic abnormalities and a hemochromatosis-like pattern of iron overload.

Hepcidin and iron-related gene expression in subjects with Dysmetabolic Hepatic Iron Overload.

BACKGROUND/AIMS: Many patients with hepatic iron overload do not have identifiable mutations and often present with metabolic disorders and hepatic steatosis. Since the pathophysiology of Dysmetabolic Hepatic Iron Overload (DHIO) is still obscure, the aim of this study was to evaluate, in these patients, possible alterations in iron-related molecule expression. METHODS: Iron-related gene mRNA levels were determined by quantitative-PCR in liver biopsies of subjects with NAFLD without iron overload and patients with HFE-hemochromatosis, beta-thalassemia major and DHIO. Urinary hepcidin was measured by immunoblotting. RESULTS: No alterations in mRNA expression of either iron transporters or exporters were found in DHIO. mRNA and urinary hepcidin levels normalized for the amount of iron overload showed a significantly lower ratio than in controls, although not as low as in hemochromatosis or beta-thalassemia. Differently from what observed in hemochromatosis, hepcidin mRNA did not correlate with urinary hepcidin. CONCLUSIONS: Patients with DHIO show appropriate regulation of mRNAs encoding proteins involved in iron uptake and efflux but dysregulation of hepcidin production. The relatively elevated urinary hepcidin can explain the iron phenotype in DHIO (more macrophage iron retention and low/normal transferrin saturation).

Measurement of urinary hepcidin levels by SELDI-TOF-MS in HFE-hemochromatosis.

INTRODUCTION: Insufficient production of hepcidin, the master regulator of iron metabolism, is recognized as the key pathogenetic feature of HFE-related hereditary hemochromatosis (HH). There is a growing interest in measuring the hepcidin levels, which may improve the diagnosis, prognostic evaluation and clinical management of HH. Nevertheless, few investigative tools are available: an immunodot method for urinary hepcidin developed by a single centre (UCLA), not yet ready for large-scale diffusion, and mass spectrometry (MS) based assays, such as surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF-MS). The latter is well suited to small peptides like hepcidin, and can rapidly analyze crude samples with high throughput. This study measured urinary hepcidin levels by SELDI-TOF-MS in a large group of HH patients at diagnosis and during treatment, including both C282Y homozygous and C282Y/H63D compound heterozygotes. METHODS: We used a protocol based on PBSIIc mass spectrometer and Normal Phase chips. Urinary samples from 30 control subjects were compared to those obtained from 80 HH patients (57 C282Y homozygotes, 23 C282Y/H63D compound heterozygotes). Eighteen C282Y homozygotes and 11 C282Y/H63D compound heterozygotes were analyzed at diagnosis, the remainder during maintenance phlebotomy. RESULTS: C282Y homozygotes either at diagnosis, or after phlebotomy had significantly lower urinary hepcidin levels than controls (P<0.05). C282Y/H63D compound heterozygotes had hepcidin levels at diagnosis higher than controls, while the hepcidin/ferritin ratio was significantly decreased (P<0.001) suggesting inadequate hepcidin production. After phlebotomy, mean hepcidin levels in the compound heterozygotes were significantly lower than in controls (P<0.001). Samples from 12 randomly selected control subjects were sent to UCLA for duplicate measurement by the immunodot method, yielding a significant correlation (rho=0.64; P=0.024). CONCLUSIONS: This study supports the use of SELDI-TOF-MS for measuring hepcidin levels in research and clinical applications. Our results in phlebotomized patients suggest that the depletion of iron stores may further exacerbate the HFE-related hepcidin defect.

Effects of plasma transfusion on hepcidin production in human congenital hypotransferrinemia.

Hepcidin is the key regulator of systemic iron homeostasis. We describe the modulation of hepcidin production induced by plasma transfusions in a patient with congenital hypotransferrinemia that offers a unique model in which to study the mechanism of hepcidin regulation by iron and erythropoiesis. Urinary hepcidin increased from zero at baseline, when hemoglobin and serum transferrin was low, to a maximum of 98 ng/mg creatinine on day 60, and subsequently decreased. Time-course of urinary hepcidin and serum transferrin concentration suggests that hepcidin production is regulated by the combination of marrow iron requirements and iron supply by transferrin.

Blunted hepcidin response to oral iron challenge in HFE-related hemochromatosis.

Inadequate hepcidin synthesis leads to iron overload in HFE-related hemochromatosis. We explored the regulation of hepcidin by iron in 88 hemochromatosis patients (61 C282Y/C282Y, 27 C282Y/H63D) and 23 healthy controls by analyzing urinary hepcidin before and 24 hours after a 65-mg oral iron dose. Thirty-four patients were studied at diagnosis and had iron overload, and 54 patients were iron depleted. At diagnosis, hepcidin values in C282Y homozygotes were similar to controls, whereas values in C282Y/H63D heterozygotes were higher (P = .02). However, the hepcidin/ferritin ratio was decreased in both homozygotes (P < .001) and heterozygotes (P = .017), confirming the inadequate hepcidin production for the iron load with both genotypes. In iron-depleted patients of both genotypes studied at a time remote from phlebotomy, basal hepcidin was still lower than in controls (P < .001 for C282Y/C282Y and P = .002 for heterozygotes). After an iron challenge, mean urinary hepcidin excretion increased in controls (P = .001) but not patients, irrespective of genotype and iron status. Significant hepcidin increase ( > or = 10 ng/mg creatinine) was observed in 74% of controls, 15% of homozygotes, and 32% of heterozygotes. The hepcidin response to oral iron is blunted in HFE-related hemochromatosis and not improved after iron depletion. The findings support the involvement of HFE in iron sensing and subsequent regulation of hepcidin.

Alpha 1-antitrypsin mutations in NAFLD: high prevalence and association with altered iron metabolism but not with liver damage.

Hyperferritinemia, a common feature of nonalcoholic fatty liver disease (NAFLD), has been associated with steatohepatitis and fibrosis. Heterozygosity for alpha 1-antitrypsin (AAT) mutations is a cofactor of liver damage, and AAT influences inflammation and iron metabolism. This study evaluated the prevalence of the common AAT PiS/PiZ mutants in 353 patients with NAFLD, 195 of whom had hyperferritinemia, versus 114 matched controls and their influence on iron metabolism and the severity of liver damage in the 212 patients submitted to biopsy. PiS and PiZ alleles were searched for by restriction analysis. Thirty-eight patients (10.8%) carried non-MM genotypes versus 4/114 (3.5%) controls (P = .02). Patients carrying AAT mutations had higher ferritin (573 [454-966] vs. 348 [201-648]; P = .001) with similar transferrin saturation. The difference was more evident in males (P < .0001) and significant in patients not carrying HFE genotypes associated with iron overload (P = .015). The prevalence of non-MM genotypes was higher in patients with hyperferritinemia than in those without (28/195, 14% vs. 10/158, 6%, P = .016), and AAT mutations were associated with higher prevalence of sinusoidal siderosis (17/27, 63% vs. 70/180, 39%; P = .02), and sinusoidal/total iron score (46.3 +/- 38% vs. 25.1 +/- 35%, P = .01). Although ferritin was independently associated with fibrosis (P = .047), AAT mutations favoring sinusoidal iron deposition did not affect liver damage. In conclusion, AAT mutations are associated with hyperferritinemia and sinusoidal iron accumulation, but not with more severe liver damage in NAFLD.

Effects of venesections and restricted diet in patients with the insulin-resistance hepatic iron overload syndrome.

GOAL: We evaluated the effect of venesections and restricted diet on iron and metabolic indices and liver function tests in patients with insulin-resistance hepatic iron overload (IR-HIO). MATERIALS AND METHODS: Patients were divided in three groups: (a) patients without any therapy who were followed-up for 36+28 months; (b) patients venesected; and (c) patients on dietary treatment. In each group baseline and end-point levels of serum iron and metabolic indices, and liver function tests were compared by Student's paired t-test and the relationship between serum ferritin and the other variables during treatment was evaluated by linear regression analysis. FINDINGS AND CONCLUSIONS: In the follow-up group, iron and metabolic indices did not change over time. Serum alanine aminotransferase, gamma-glutamyl transferase, cholesterol and triglycerides significantly decreased after iron depletion. Serum glucose, cholesterol, triglyceride, ferritin and liver function tests significantly decreased after dietary treatment. Transferrin saturation decreased below 20% during phlebotomy treatment in 52% of the patients. In conclusion, our results show that IR-HIO patients had relatively low amount of iron overload that seems not to increase even after a long follow-up period. Both venesections and diet improved iron, metabolic and hepatic indices. Data suggest a relationship between hepatic iron overload and insulin resistance, and a role for both iron overload and insulin resistance in hepatocellular damage. The behaviour of iron indices during venesections suggests an impaired iron release from hepatic cells.

Increased serum ferritin is common in men with essential hypertension.

OBJECTIVES: Insulin-resistance-associated hepatic iron overload syndrome (IRHIO) is characterized by high serum ferritin and presence of metabolic alterations that are part of insulin-resistance syndrome (IRS). Thus, clinical conditions characterized by a high prevalence of IRS may also be characterized by a high prevalence of IRHIO. DESIGN AND METHODS: We studied 88 consecutive patients with essential hypertension, 62 patients with IRHIO and 102 healthy normotensive controls. Hemochromatosis, other conditions able to induce secondary iron overload or serum ferritin increase unrelated to body iron stores were excluded. Iron indices, metabolic profiles and hepatic tests in hypertensive with or without increased serum ferritin and in IRHIO with and without hypertension were studied. Metabolic variables, serum iron indices, liver function tests and hepatic ultrasound data were analysed. Data were compared by non-parametric tests. RESULTS: In men with hypertension, increased serum ferritin was more frequent than in controls (21 versus 0%, P = 0.001). Hypertensive men with increased serum ferritin had more frequent and pronounced metabolic alterations than those with normal serum ferritin, the metabolic abnormalities and serum ferritin being frequently positively correlated. In hypertensive men with increased serum ferritin, metabolic and iron data were similar to those of IRHIO patients with hypertension. CONCLUSIONS: In males, hypertension is characterized by a higher prevalence of increased iron stores and metabolic abnormalities that are part of the IRHIO syndrome. This finding may have clinical implications due to the increased risk of IRHIO patients to develop hepatic cirrhosis and also for the role of iron in early atherogenesis.