Obesogenic diet leads to luminal overproduction of the complex IV inhibitor H2 S and mitochondrial dysfunction in mouse colonocytes.

Obesity is characterized by systemic low-grade inflammation associated with disturbances of intestinal homeostasis and microbiota dysbiosis. Mitochondrial metabolism sustains epithelial homeostasis by providing energy to colonic epithelial cells (CEC) but can be altered by dietary modulations of the luminal environment. Our study aimed at evaluating whether the consumption of an obesogenic diet alters the mitochondrial function of CEC in mice. Mice were fed for 22 weeks with a 58% kcal fat diet (diet-induced obesity [DIO] group) or a 10% kcal fat diet (control diet, CTRL). Colonic crypts were isolated to assess mitochondrial function while colonic content was collected to characterize microbiota and metabolites. DIO mice developed obesity, intestinal hyperpermeability, and increased endotoxemia. Analysis of isolated colonic crypt bioenergetics revealed a mitochondrial dysfunction marked by decreased basal and maximal respirations and lower respiration linked to ATP production in DIO mice. Yet, CEC gene expression of mitochondrial respiration chain complexes and mitochondrial dynamics were not altered in DIO mice. In parallel, DIO mice displayed increased colonic bile acid concentrations, associated with higher abundance of Desulfovibrionaceae. Sulfide concentration was markedly increased in the colon content of DIO mice. Hence, chronic treatment of CTRL mouse colon organoids with sodium sulfide provoked mitochondrial dysfunction similar to that observed in vivo in DIO mice while acute exposure of isolated mitochondria from CEC of CTRL mice to sodium sulfide diminished complex IV activity. Our study provides new insights into colon mitochondrial dysfunction in obesity by revealing that increased sulfide production by DIO-induced dysbiosis impairs complex IV activity in mouse CEC.

Differences in bone microarchitecture between genetic and secondary iron-overload mouse models suggest a role for hepcidin deficiency in iron-related osteoporosis.

Iron overload is one of the secondary osteoporosis etiologies. Cellular and molecular mechanisms involved in iron-related osteoporosis are not fully understood. AIM: The aim of the study was to investigate the respective roles of iron excess and hepcidin, the systemic iron regulator, in the development of iron-related osteoporosis. MATERIAL AND METHODS: We used mice models with genetic iron overload (GIO) related to hepcidin deficiency (Hfe-/- and Bmp6-/- ) and secondary iron overload (SIO) exhibiting a hepcidin increase secondary to iron excess. Iron concentration and transferrin saturation levels were evaluated in serum and hepatic, spleen, and bone iron concentrations were assessed by ICP-MS and Perl's staining. Gene expression was evaluated by quantitative RT-PCR. Bone micro-architecture was evaluated by micro-CT. The osteoblastic MC3T3 murine cells that are able to mineralize were exposed to iron and/or hepcidin. RESULTS: Despite an increase of bone iron concentration in all overloaded mice models, bone volume/total volume (BV/TV) and trabecular thickness (Tb.Th) only decreased significantly in GIO, at 12 months for Hfe-/- and from 6 months for Bmp6-/- . Alterations in bone microarchitecture in the Bmp6-/- model were positively correlated with hepcidin levels (BV/TV (ρ = +.481, p < .05) and Tb.Th (ρ = +.690, p < .05). Iron deposits were detected in the bone trabeculae of Hfe-/- and Bmp6-/- mice, while iron deposits were mainly visible in bone marrow macrophages in secondary iron overload. In cell cultures, ferric ammonium citrate exposure abolished the mineralization process for concentrations above 5 µM, with a parallel decrease in osteocalcin, collagen 1, and alkaline phosphatase mRNA levels. Hepcidin supplementation of cells had a rescue effect on the collagen 1 and alkaline phosphatase expression level decrease. CONCLUSION: Together, these data suggest that iron in excess alone is not sufficient to induce osteoporosis and that low hepcidin levels also contribute to the development of osteoporosis.

A simple clinical score to promote and enhance ferroportin disease screening.

BACKGROUND & AIMS: Ferroportin disease is a rare genetic iron overload disorder which may be underdiagnosed, with recent data suggesting it occurs at a higher prevalence than suspected. Costs and the lack of defined criteria to prompt genetic testing preclude large-scale molecular screening. Hence, we aimed to develop a readily available scoring system to promote and enhance ferroportin disease screening. METHODS: Our derivation cohort included probands tested for ferroportin disease from 2008 to 2016 in our rare disease network. Data were prospectively recorded. Univariate and multivariate logistic regression were used to determine significant criteria, and odds ratios were used to build a weighted score. A cut-off value was defined using a ROC curve with a predefined aim of 90% sensitivity. An independent cohort was used for cross validation. RESULTS: Our derivation cohort included 1,306 patients. Mean age was 55±14 years, ferritin 1,351±1,357 µg/L, and liver iron concentration (LIC) 166±77 µmol/g. Pathogenic variants (n = 32) were identified in 71 patients. In multivariate analysis: female sex, younger age, higher ferritin, higher LIC and the absence of hypertension or diabetes were significantly associated with the diagnosis of ferroportin disease (AUROC in whole derivation cohort 0.83 [0.78-0.88]). The weighted score was based on sex, age, the presence of hypertension or diabetes, ferritin level and LIC. An AUROC of 0.83 (0.77-0.88) was obtained in the derivation cohort without missing values. Using 9.5 as a cut-off, sensitivity was 93.6 (91.7-98.3) %, specificity 49.5 (45.5-53.6) %, positive likelihood ratio 1.8 (1.6-2.0) and negative likelihood ratio 0.17 (0.04-0.37). CONCLUSION: We describe a readily available score with simple criteria and good diagnostic performance that could be used to screen patients for ferroportin disease in routine clinical practice. LAY SUMMARY: Increased iron burden associated with metabolic syndrome is a very common condition. Ferroportin disease is a dominant genetic iron overload disorder whose prevalence is higher than initially thought. They can be difficult to distinguish from each other, but the limited availability of genetic testing and the lack of definitive guidelines prevent adequate screening. We herein describe a simple and definitive clinical score to help clinicians decide whether to perform genetic testing.

Relevance of using both aerobic and anaerobic enrichment vials for optimizing rapid diagnosis of osteoarticular infections.

The performance of a pair of blood culture vials (BACTEC® Plus Aerobic/F, and Anaerobic Lytic/F) were analyzed in 496 osteoarticular specimens (246 synovial fluids and 250 crushed bone samples), obtained in patients during routine diagnostic procedure at the Teaching Hospital of Rennes (France). The positive detection times were recorded for a 14 day-incubation period, and compared between both vials and with agar cultures. For samples from infected patients, the positive detection time was significantly shortened when vials were used compared to agar plates (p < 0.001). Median positive detection time was later with the Anaerobic Lytic/F vials (15.0 h) compared to the Plus Aerobic/F (13.0 h). Positivity rate was similar for Anaerobic Lytic/F vials (80.4%) and Plus Aerobic/F vials (83.2%) (p = 0.25). Some microorganisms were only identified from aerobic vials (15.5%) or from anaerobic vials (12.7%). The use of both atmosphere conditions for optimal positive detection time is therefore critical.

Investigating the Molecular Mechanisms of Renal Hepcidin Induction and Protection upon Hemoglobin-Induced Acute Kidney Injury.

Hemolysis is known to cause acute kidney injury (AKI). The iron regulatory hormone hepcidin, produced by renal distal tubules, is suggested to exert a renoprotective role during this pathology. We aimed to elucidate the molecular mechanisms of renal hepcidin synthesis and its protection against hemoglobin-induced AKI. In contrast to known hepatic hepcidin induction, incubation of mouse cortical collecting duct (mCCDcl1) cells with IL-6 or LPS did not induce Hamp1 mRNA expression, whereas iron (FeS) and hemin significantly induced hepcidin synthesis (p < 0.05). Moreover, iron/heme-mediated hepcidin induction in mCCDcl1 cells was caused by the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, as indicated by increased nuclear Nrf2 translocation and induced expression of Nrf2 downstream targets GCLM (p < 0.001), NQO1 (p < 0.001), and TXNRD1 (p < 0.005), which could be prevented by the known Nrf2 inhibitor trigonelline. Newly created inducible kidney-specific hepcidin KO mice demonstrated a significant reduction in renal Hamp1 mRNA expression. Phenylhydrazine (PHZ)-induced hemolysis caused renal iron loading and oxidative stress in both wildtype (Wt) and KO mice. PHZ treatment in Wt induced inflammatory markers (IL-6, TNFα) but not Hamp1. However, since PHZ treatment also significantly reduced systemic hepcidin levels in both Wt and KO mice (both p < 0.001), a dissection between the roles of systemic and renal hepcidin could not be made. Combined, the results of our study indicate that there are kidney-specific mechanisms in hepcidin regulation, as indicated by the dominant role of iron and not inflammation as an inducer of renal hepcidin, but also emphasize the complex interplay of various iron regulatory mechanisms during AKI on a local and systemic level.

Ruling out septic arthritis risk in a few minutes using mid-infrared spectroscopy in synovial fluids.

OBJECTIVES: The aim of this study was to show the usefulness of a mid-infrared fibre evanescent wave spectroscopy point of care device in the identification of septic arthritis patients in a multicentre cohort, and to apply this technology to clinical practice among physicians. METHODS: SF samples from 402 patients enrolled in a multicentre cohort were frozen for analysis by mid-infrared fibre evanescent wave spectroscopy. The calibration cohort was divided into two groups of patients (septic arthritis and non-septic arthritis) and relevant spectral variables were used for logistic regression model. Model performances were tested on an independent set of 86 freshly obtained SF samples from patients enrolled in a single-centre acute arthritis cohort and spectroscopic analyses performed at the patient's bedside. RESULTS: The model set-up, using frozen-thawed SFs, provided good performances, with area under the curve 0.95, sensitivity 0.90, specificity 0.90, positive predictive value 0.41 and negative predictive value 0.99. Performances obtained in the validation cohort were area under the curve 0.90, sensitivity 0.92, specificity 0.81, positive predictive value 0.46 and negative predictive value 0.98. The septic arthritis probability has been translated into a risk score from 0 to 4 according to septic risk. For a risk score of 0, the probability of identifying a septic patient is very low (negative predictive value of 1), whereas a risk score of 4 indicates very high risk of septic arthritis (positive predictive value of 1). CONCLUSION: Mid-infrared fibre evanescent wave spectroscopy could distinguish septic from non-septic synovial arthritis fluids with good performances, and showed particular usefulness in ruling out septic arthritis. Our data supports the possibility of technology transfer. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT02860871.

Simulated microgravity disturbs iron metabolism and distribution in humans: Lessons from dry immersion, an innovative ground-based human model.

The objective of the present study was to determine the effects of dry immersion, an innovative ground-based human model of simulated microgravity and extreme physical inactivity, on iron homeostasis and distribution. Twenty young healthy men were recruited and submitted to 5 days of dry immersion (DI). Fasting blood samples and MRI were performed before and after DI exposure to assess iron status, as well as hematological responses. DI increased spleen iron concentrations (SIC), whereas hepatic iron store (HIC) was not affected. Spleen iron sequestration could be due to the concomitant increase in serum hepcidin levels (P < .001). Increased serum unconjugated bilirubin, as well as the rise of serum myoglobin levels support that DI may promote hemolysis and myolysis. These phenomena could contribute to the concomitant increase of serum iron and transferrin saturation levels (P < .001). As HIC remained unchanged, increased serum hepcidin levels could be due both to higher transferrin saturation level, and to low-grade pro-inflammatory as suggested by the significant rise of serum ferritin and haptoglobin levels after DI (P = .003 and P = .003, respectively). These observations highlight the need for better assessment of iron metabolism in bedridden patients, and an optimization of the diet currently proposed to astronauts.

Intermittent reloading does not prevent reduction in iron availability and hepcidin upregulation caused by hindlimb unloading.

NEW FINDINGS: What is the central question of this study? Could skeletal muscle be involved in microgravity-induced iron misdistribution by modulating expression of hepcidin, the master regulator of iron metabolism? What is the main finding and its importance? We demonstrate, in rats, that hepcidin upregulation is not a transient adaptation associated with early exposure to microgravity and that intermittent reloading does not limit microgravity-induced iron misdistribution despite having a beneficial effect on soleus muscle wasting. ABSTRACT: In humans, exposure to microgravity during spaceflight causes muscle atrophy, changes in iron storage and a reduction in iron availability. We previously observed that during 7 days of simulated microgravity in rats, hepcidin plays a key role in iron misdistribution, and we suggested that a crosstalk between skeletal muscle and liver could regulate hepcidin synthesis in this context. In the present study in rats, we investigated the medium-term effects of simulated microgravity on iron metabolism. We also tested whether intermittent reloading (IR) to target skeletal muscle atrophy limits iron misdistribution efficiently. For this purpose, Wistar rats underwent 14 days of hindlimb unloading (HU) combined or not combined with daily IR. At the end of this period, the serum iron concentration and transferrin saturation were significantly reduced, whereas hepatic hepcidin mRNA was upregulated. However, the main signalling pathways involved in hepcidin synthesis in the liver (BMP-small mothers against decapentaplegic (SMAD), interleukin-6-STAT3 and ERK1/2) were unaffected. Unlike what was observed after 7 days of HU, the iron concentration in the spleen, liver and skeletal muscle was comparable between control animals and those that underwent HU or HU plus IR for 14 days. Despite its beneficial effect on soleus muscle atrophy and slow-to-fast myosin heavy chain distribution, IR did not significantly prevent a reduction in iron availability and hepcidin upregulation. Altogether, these results highlight that iron availability is durably reduced during longer exposure to simulated microgravity and that the related hepcidin upregulation is not a transient adaptation to these conditions. The results also suggest that skeletal muscle does not necessarily play a key role in the iron misdistribution that occurs during simulated microgravity.

Iron and platelets: A subtle, under-recognized relationship.

The role of iron in the formation and functioning of erythrocytes, and to a lesser degree of white blood cells, is well established, but the relationship between iron and platelets is less documented. Physiologically, iron plays an important role in hematopoiesis, including thrombopoiesis; iron levels direct, together with genetic factors, the lineage commitment of megakaryocytic/erythroid progenitors toward either megakaryocyte or erythroid progenitors. Megakaryocytic iron contributes to cellular machinery, especially energy production in platelet mitochondria. Thrombocytosis, possibly favoring vascular thrombosis, is a classical feature observed with abnormally low total body iron stores (mainly due to blood losses or decreased duodenal iron intake), but thrombocytopenia can also occur in severe iron deficiency anemia. Iron sequestration, as seen in inflammatory conditions, can be associated with early thrombocytopenia due to platelet consumption and followed by reactive replenishment of the platelet pool with possibility of thrombocytosis. Iron overload of genetic origin (hemochromatosis), despite expected mitochondrial damage related to ferroptosis, has not been reported to cause thrombocytopenia (except in case of high degree of hepatic fibrosis), and iron-related alteration of platelet function is still a matter of debate. In acquired iron overload (of transfusional and/or dyserythropoiesis origin), quantitative or qualitative platelet changes are difficult to attribute to iron alone due to the interference of the underlying hematological conditions; likewise, hematological improvement, including increased blood platelet counts, observed under iron oral chelation is likely to reflect mechanisms other than the sole beneficial impact of iron depletion.

Ceruloplasmin deficiency does not induce macrophagic iron overload: lessons from a new rat model of hereditary aceruloplasminemia.

Hereditary aceruloplasminemia (HA), related to mutations in the ceruloplasmin (Cp) gene, leads to iron accumulation. Ceruloplasmin ferroxidase activity being considered essential for macrophage iron release, macrophage iron overload is expected, but it is not found in hepatic and splenic macrophages in humans. Our objective was to get a better understanding of the mechanisms leading to iron excess in HA. A clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR associated protein 9 (Cas9) knockout of the Cp gene was performed on Sprague-Dawley rats. We evaluated the iron status in plasma, the expression of iron metabolism genes, and the status of other metals whose interactions with iron are increasingly recognized. In Cp-/- rats, plasma ceruloplasmin and ferroxidase activity were absent, together with decreased iron concentration and transferrin saturation. Similarly as in humans, the hepatocytes were iron overloaded conversely to hepatic and splenic macrophages. Despite a relative hepcidin deficiency in Cp-/- rats and the loss of ferroxidase activity, potentially expected to limit the interaction of iron with transferrin, no increase of plasma non-transferrin-bound iron level was found. Copper was decreased in the spleen, whereas manganese was increased in the plasma. These data suggest that the reported role of ceruloplasmin cannot fully explain the iron hepatosplenic phenotype in HA, encouraging the search for additional mechanisms.-Kenawi, M., Rouger, E., Island, M.-L., Leroyer, P., Robin, F., Remy, S., Tesson, L., Anegon, I., Nay, K., Derbré, F., Brissot, P., Ropert, M., Cavey, T., Loréal, O. Ceruloplasmin deficiency does not induce macrophagic iron overload: lessons from a new rat model of hereditary aceruloplasminemia.

Spleen iron, molybdenum, and manganese concentrations are coregulated in hepcidin-deficient and secondary iron overload models in mice.

Iron excess increases the hepatic expression of hepcidin, the systemic iron metabolism regulator that favors iron sequestration in the spleen. Genetic iron overload related to hepcidin insufficiency decreases the spleen iron concentration and increases hepatic iron concentration, whereas during secondary iron overload, the hepcidin expression increases together with spleen iron concentration in addition to hepatic iron concentrations increase. Links between iron metabolism and other metals being suggested, our aim was to investigate, during iron overload, the relationships between the hepatic hepcidin expression level and the hepatic and splenic concentrations of iron, manganese, copper, zinc, and molybdenum, determined using inductively coupled plasma mass spectrometry. Hepcidin-deficient mice, secondary iron overload mice models, and their respective controls were studied. Spleen molybdenum and manganese concentrations paralleled the modulation of both spleen iron concentrations, increasing in secondary iron overload and decreasing in hepcidin deficiency related iron overload, as well as hepatic hepcidin mRNA expression. Our data suggest that iron, manganese, and molybdenum metabolisms could share mechanisms controlling their distribution that are associated to hepcidin modulation. In diseases with abnormal hepcidin levels, including chronic inflammation, special attention should be paid to those metals that can participate with the phenotype.-Cavey, T., Latour, C., Island, M.-L., Leroyer, P., Guggenbuhl, P., Coppin, H., Roth, M.-P., Bendavid, C., Brissot, P., Ropert, M., Loréal, O. Spleen iron, molybdenum, and manganese concentrations are coregulated in hepcidin-deficient and secondary iron overload models in mice.

Simulated microgravity decreases circulating iron in rats: role of inflammation-induced hepcidin upregulation.

NEW FINDINGS: What is the central question of this study? Although microgravity is well known to reduce circulating iron in astronauts, the underlying mechanism is still unknown. We investigated whether hepcidin, a key hormone regulating iron metabolism, could be involved in this deleterious effect. What is the main finding and its importance? We show that hindlimb suspension, a model of microgravity, stimulates the production of hepcidin in liver of rats. In agreement with the biological role of hepcidin, we found a decrease of circulating iron and an increase of spleen iron content in hindlimb-unloaded rats. Consequently, our study supports the idea that hepcidin could play a role in the alteration of iron metabolism parameters observed during spaceflight. During spaceflight, humans exposed to microgravity exhibit an increase of iron storage and a reduction of circulating iron. Such perturbations could promote oxidative stress and anaemia in astronauts. The mechanism by which microgravity modulates iron metabolism is still unknown. Herein, we hypothesized that microgravity upregulates hepcidin, a hormone produced by the liver that is the main controller of iron homeostasis. To test this hypothesis, rats were submitted to hindlimb unloading (HU), the reference model to mimic the effects of microgravity in rodents. After 7 days, the mRNA level of hepcidin was increased in the liver of HU rats (+74%, P = 0.001). In agreement with the biological role of hepcidin, we found an increase of spleen iron content (+78%, P = 0.030) and a decrease of serum iron concentration (-35%, P = 0.002) and transferrin saturation (-25%, P = 0.011) in HU rats. These findings support a role of hepcidin in microgravity-induced iron metabolism alteration. Furthermore, among the signalling pathways inducing hepcidin mRNA expression, we found that only the interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) axis was activated by HU, as shown by the increase of phospho-STAT3 (+193%, P < 0.001) and of the hepatic mRNA level of haptoglobin (+167%, P < 0.001), a STAT3-inducible gene, in HU rats. Taken together, these data support the idea that microgravity may alter iron metabolism through an inflammatory process upregulating hepcidin.

Iron metabolism and related genetic diseases: A cleared land, keeping mysteries.

Body iron has a very close relationship with the liver. Physiologically, the liver synthesizes transferrin, in charge of blood iron transport; ceruloplasmin, acting through its ferroxidase activity; and hepcidin, the master regulator of systemic iron. It also stores iron inside ferritin and serves as an iron reservoir, both protecting the cell from free iron toxicity and ensuring iron delivery to the body whenever needed. The liver is first in line for receiving iron from the gut and the spleen, and is, therefore, highly exposed to iron overload when plasma iron is in excess, especially through its high affinity for plasma non-transferrin bound iron. The liver is strongly involved when iron excess is related either to hepcidin deficiency, as in HFE, hemojuvelin, hepcidin, and transferrin receptor 2 related haemochromatosis, or to hepcidin resistance, as in type B ferroportin disease. It is less involved in the usual (type A) form of ferroportin disease which targets primarily the macrophagic system. Hereditary aceruloplasminemia raises important pathophysiological issues in light of its peculiar organ iron distribution.

Rare HFE variants are the most frequent cause of hemochromatosis in non-c282y homozygous patients with hemochromatosis.

p.Cys282Tyr (C282Y) homozygosity explains most cases of HFE-related hemochromatosis, but a significant number of patients presenting with typical type I hemochromatosis phenotype remain unexplained. We sought to describe the clinical relevance of rare HFE variants in non-C282Y homozygotes. Patients referred for hemochromatosis to the National Reference Centre for Rare Iron Overload Diseases from 2004 to 2010 were studied. Sequencing was performed for coding region and intronic flanking sequences of HFE, HAMP, HFE2, TFR2, and SLC40A1. Nine private HFE variants were identified in 13 of 206 unrelated patients. Among those, five have not been previously described: p.Leu270Argfs*4, p.Ala271Valfs*25, p.Tyr52*, p.Lys166Asn, and p.Asp141Tyr. Our results show that rare HFE variants are identified more frequently than variants in the other genes associated with iron overload. Rare HFE variants are therefore the most frequent cause of hemochromatosis in non-C282Y homozygote HFE patients. Am. J. Hematol. 91:1202-1205, 2016. © 2016 Wiley Periodicals, Inc.

Mid-infrared fibre evanescent wave spectroscopy of serum allows fingerprinting of the hepatic metabolic status in mice.

Non-alcoholic fatty liver disease is associated with obesity, diabetes, and metabolic syndrome. The detection of systemic metabolic changes associated with alterations in the liver status during non-alcoholic fatty liver disease could improve patient follow-up. The aim of the present study was to evaluate the potential of mid-infrared fibre evanescent wave spectroscopy as a minimum-invasive method for evaluating the liver status during non-alcoholic fatty liver disease. Seventy-five mice were subjected to a control, high-fat or high-fat-high carbohydrate diets. We analysed the serum biochemical parameters and mRNA levels of hepatic genes by quantitative RT-PCR. Steatosis was quantified by image analysis. The mid-infrared spectra were acquired from serum, and then analysed to develop a predictive model of the steatosis level. Animals subjected to enriched diets were obese. Hepatic steatosis was found in all animals. The relationship between the spectroscopy-predicted and observed levels of steatosis, expressed as percentages of the liver biopsy area, was not linear. A transition around 10% steatosis was observed, leading us to consider two distinct predictive models (<10% and >10%) based on two different sets of discriminative spectral variables. The model performance was evaluated using random cross-validation (10%). The hypothesis that additional metabolic changes occur beyond this transition was supported by the fact that it was associated with increased serum ALT levels, and Col1α1 chain mRNA levels. Our data suggest that mid-infrared spectroscopy combined with statistical analysis allows identifying serum mid-infrared signatures that reflect the liver status during non-alcoholic fatty liver disease.

Hereditary hypotransferrinemia can lead to elevated transferrin saturation and, when associated to HFE or HAMP mutations, to iron overload.

As our understanding of iron metabolism improves through the more accurate description of iron metabolism actors, new causes of iron overload are identified. We, here, report 16 cases of hereditary hypotransferrinemia related to 4 previously undescribed TF (transferrin) mutations (p.Val221Gly, p.Arg609Trp, p.Glu370Lys, p.Tyr533X and p.Cys421Arg). We show that, besides increasing serum transferrin saturation without iron overload, hypotransferrinemia, when associated to mutations in HFE or HAMP or to acquired factors, can lead to clinically relevant iron burden. These cases emphasize the usefulness of serum transferrin determination in the diagnostic evaluation of iron overload and the importance for clinicians to be aware of this syndrome.

Liver transplantation normalizes serum hepcidin level and cures iron metabolism alterations in HFE hemochromatosis.

UNLABELLED: Defects in human hemochromatosis protein (HFE) cause iron overload due to reduced hepatic hepcidin secretion. Liver transplantation (LT) is a key treatment for potential complications from HFE-related hereditary hemochromatosis (HH). This study evaluated hepcidin secretion and iron burden after LT to elucidate HH pathophysiology. Patients (n=18) homozygous for the p.Cys282Tyr mutation in the HFE gene underwent LT between 1999 and 2008. Serum iron, serum hepcidin, and hepatic iron concentrations were determined before LT and at the end of follow-up (median 57 months). Mortality and causes of death were determined. Survival was compared to that of the overall patient population that received LT. Before LT, serum hepcidin levels were low (0.54 ± 2.5 nmol/L; normal range: 4-30 nmol/L). After LT, 11 patients had iron evaluations; none received iron depletion therapy; all had normal transferrin saturation. The mean serum ferritin was 185 (± 99) µg/L. Magnetic resonance imaging showed that iron overload was absent in nine patients, mild in one patient with metabolic syndrome, and high (180 µmol/g) in one patient with hereditary spherocytosis discovered after LT. At the end of follow-up, serum hepcidin was normal in 10 patients (11.12 ± 7.6 nmol/L; P<0.05) and low in one patient with iron deficiency anemia. Survival was 83% and 67% at 1 and 5 years, respectively. Survival was similar for patients with HH and patients that received LT for other causes. CONCLUSION: In HH, LT normalized hepcidin secretion and prevented recurrence of hepatic iron overload. Survival was similar to that of patients who received LTs for other liver diseases.

Testosterone perturbs systemic iron balance through activation of epidermal growth factor receptor signaling in the liver and repression of hepcidin.

UNLABELLED: Gender-related disparities in the regulation of iron metabolism may contribute to the differences exhibited by men and women in the progression of chronic liver diseases associated with reduced hepcidin expression, e.g., chronic hepatitis C, alcoholic liver disease, or hereditary hemochromatosis. However, their mechanisms remain poorly understood. In this study we took advantage of the major differences in hepcidin expression and tissue iron loading observed between Bmp6-deficient male and female mice to investigate the mechanisms underlying this sexual dimorphism. We found that testosterone robustly represses hepcidin transcription by enhancing Egfr signaling in the liver and that selective epidermal growth factor receptor (Egfr) inhibition by gefitinib (Iressa) in males markedly increases hepcidin expression. In males, where the suppressive effects of testosterone and Bmp6-deficiency on hepcidin expression are combined, hepcidin is more strongly repressed than in females and iron accumulates massively not only in the liver but also in the pancreas, heart, and kidneys. CONCLUSION: Testosterone-induced repression of hepcidin expression becomes functionally important during homeostatic stress from disorders that result in iron loading and/or reduced capacity for hepcidin synthesis. These findings suggest that novel therapeutic strategies targeting the testosterone/EGF/EGFR axis may be useful for inducing hepcidin expression in patients with iron overload and/or chronic liver diseases.

Mouse genetic background impacts both on iron and non-iron metals parameters and on their relationships.

Iron is reported to interact with other metals. In addition, it has been shown that genetic background may impact iron metabolism. Our objective was to characterize, in mice of three genetic backgrounds, the links between iron and several non-iron metals. Thirty normal mice (C57BL/6, Balb/c and DBA/2; n = 10 for each group), fed with the same diet, were studied. Quantification of iron, zinc, cobalt, copper, manganese, magnesium and rubidium was performed by ICP/MS in plasma, erythrocytes, liver and spleen. Transferrin saturation was determined. Hepatic hepcidin1 mRNA level was evaluated by quantitative RT-PCR. As previously reported, iron parameters were modulated by genetic background with significantly higher values for plasma iron parameters and liver iron concentration in DBA/2 and Balb/c strains. Hepatic hepcidin1 mRNA level was lower in DBA/2 mice. No iron parameter was correlated with hepcidin1 mRNA levels. Principal component analysis of the data obtained for non-iron metals indicated that metals parameters stratified the mice according to their genetic background. Plasma and tissue metals parameters that are dependent or independent of genetic background were identified. Moreover, relationships were found between plasma and tissue content of iron and some other metals parameters. Our data: (i) confirms the impact of the genetic background on iron parameters, (ii) shows that genetic background may also play a role in the metabolism of non-iron metals, (iii) identifies links between iron and other metals parameters which may have implications in the understanding and, potentially, the modulation of iron metabolism.