This study was designed to evaluate the levels of hepcidin in the serum of patients with chronic obstructive pulmonary disease (COPD).
In the study, 74 male patients (ages 45-75) in a stable period for COPD were grouped as Group I: Mild COPD (n:25), Group II: Moderate COPD (n:24), and Group III: Severe COPD (n:25). Healthy non-smoker males were included in Group IV (n:35) as a control group. The differences of hepcidin level among all the groups were examined. Also, in the patient groups with COPD, hepcidin level was compared with age, body mass index, cigarette (package/year), blood parameters (iron, total iron binding capacity, ferritin, hemoglobin, hematocrit [hct]), respiratory function tests, and arterial blood gas results.
Although there was no difference between the healthy control group and the mild COPD patient group (P=0.781) in terms of hepcidin level, there was a difference between the moderate (P=0.004) and the severe COPD patient groups (P=0.002). The hepcidin level of the control group was found to be higher than the moderate and severe COPD patient groups. In the severe COPD patients, hepcidin level increased with the increase in serum iron (P=0.000), hct (P=0.009), ferritin levels (P=0.012), and arterial oxygen saturation (SaO2, P=0.000).
The serum hepcidin level that is decreased in severe COPD brings into mind that it may play a role in the mechanism to prevent hypoxemia. The results suggest that serum hepcidin level may be a useful marker in COPD. Larger prospective studies are needed to confirm our findings between hepcidin and COPD.
Chronic obstructive pulmonary disease; hepcidin; hypoxemia
Hepcidin is a central regulator of iron metabolism. Serum hepcidin levels are increased in patients with renal insufficiency, which may contribute to anemia. Urine hepcidin was found to be increased in some patients after cardiac surgery, and these patients were less likely to develop acute kidney injury. It has been suggested that urine hepcidin may protect by attenuating heme-mediated injury, but processes involved in urine hepcidin excretion are unknown.
To assess the role of tubular reabsorption we compared fractional excretion (FE) of hepcidin-25 with FE of β2-microglobulin (β2m) in 30 patients with various degrees of tubular impairment due to chronic renal disease. To prove that hepcidin is reabsorbed by the tubules in a megalin-dependent manner, we measured urine hepcidin-1 in wild-type and kidney specific megalin-deficient mice. Lastly, we evaluated FE of hepcidin-25 and β2m in 19 patients who underwent cardiopulmonary bypass surgery. Hepcidin was measured by a mass spectrometry assay (MS), whereas β2m was measured by ELISA.
In patients with chronic renal disease, FE of hepcidin-25 was strongly correlated with FE of β2m (r = 0.93, P <0.01). In megalin-deficient mice, urine hepcidin-1 was 7-fold increased compared to wild-type mice (p < 0.01) indicating that proximal tubular reabsorption occurs in a megalin- dependent manner. Following cardiac surgery, FE of hepcidin-25 increased despite a decline in FE of β2m, potentially indicating local production at 12–24 hours.
Hepcidin-25 is reabsorbed by the renal tubules and increased urine hepcidin-25 levels may reflect a reduction in tubular uptake. Uncoupling of FE of hepcidin-25 and β2m in cardiac surgery patients suggests local production.
AKI; β2-microglobulin; Hepcidin; Megalin; Kidney tubules
Hepcidin is a 25-aminoacid cysteine-rich iron regulating peptide. Increased hepcidin concentrations lead to iron sequestration in macrophages, contributing to the pathogenesis of anaemia of chronic disease whereas decreased hepcidin is observed in iron deficiency and primary iron overload diseases such as hereditary hemochromatosis. Hepcidin quantification in human blood or urine may provide further insights for the pathogenesis of disorders of iron homeostasis and might prove a valuable tool for clinicians for the differential diagnosis of anaemia. This study describes a specific and non-operator demanding immunoassay for hepcidin quantification in human sera.
Methods and Findings
An ELISA assay was developed for measuring hepcidin serum concentration using a recombinant hepcidin25-His peptide and a polyclonal antibody against this peptide, which was able to identify native hepcidin. The ELISA assay had a detection range of 10–1500 µg/L and a detection limit of 5.4 µg/L. The intra- and interassay coefficients of variance ranged from 8–15% and 5–16%, respectively. Mean linearity and recovery were 101% and 107%, respectively. Mean hepcidin levels were significantly lower in 7 patients with juvenile hemochromatosis (12.8 µg/L) and 10 patients with iron deficiency anemia (15.7 µg/L) and higher in 7 patients with Hodgkin lymphoma (116.7 µg/L) compared to 32 age-matched healthy controls (42.7 µg/L).
We describe a new simple ELISA assay for measuring hepcidin in human serum with sufficient accuracy and reproducibility.
Systemic iron balance is regulated by hepcidin, a peptide hormone secreted by the liver. By decreasing cell surface expression of the iron exporter ferroportin, hepcidin decreases iron absorption from the intestine and iron release from reticuloendothelial stores. Hepcidin excess has been implicated in the pathogenesis of anemia of chronic disease, while hepcidin deficiency has a key role in the pathogenesis of the iron overload disorder hemochromatosis. We have recently shown that hemojuvelin is a coreceptor for bone morphogenetic protein (BMP) signaling and that BMP signaling positively regulates hepcidin expression in liver cells in vitro. Here we show that BMP-2 administration increases hepcidin expression and decreases serum iron levels in vivo. We also show that soluble hemojuvelin (HJV.Fc) selectively inhibits BMP induction of hepcidin expression in vitro and that administration of HJV.Fc decreases hepcidin expression, increases ferroportin expression, mobilizes splenic iron stores, and increases serum iron levels in vivo. These data support a role for modulators of the BMP signaling pathway in treating diseases of iron overload and anemia of chronic disease.
Introduction. Anemia is a frequent problem in hospitalized geriatric patients, and the anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are the 2 most prevalent causes. The aim of the study was to assess the possible role of serum hepcidin in the differential diagnosis between ACD and IDA. Methods. We investigated serum hepcidin, iron status, anemia, and C-reactive protein in 39 consecutive geriatric patients with ACD and IDA. Serum hepcidin levels were determined using a commercial ELISA kit (DRG Instruments, Marburg, Germany). We also measured hepcidin in 26 healthy controls. Results. The serum hepcidin levels were not significantly higher in the 28 patients with ACD as compared to the 11 patients with IDA. Conclusions. The serum hepcidin levels measured using the commercial ELISA kit (DRG) do not appear to increase in older patients with ACD. It should be noted that an assay-specific problem could explain our results.
Patients with chronic hepatitis C frequently have serum and hepatic iron overload, but the mechanism is unknown. Recently identified hepcidin, exclusively synthesized in the liver, is thought to be a key regulator for iron homeostasis and is induced by infection and inflammation. This study was conducted to determine the hepatic hepcidin expression levels in patients with various liver diseases. We investigated hepcidin mRNA levels of liver samples by real-time detection-polymerase chain reaction; 56 were hepatitis C virus (HCV) positive, 34 were hepatitis B virus (HBV) positive, and 42 were negative for HCV and HBV (3 cases of auto-immune hepatitis, 7 alcoholic liver disease, 13 primary biliary cirrhosis, 9 nonalcoholic fatty liver disease, and 10 normal liver). We analyzed the relation of hepcidin to clinical, hematological, histological, and etiological findings. Hepcidin expression levels were strongly correlated with serum ferritin (P < 0.0001) and the degree of iron deposit in liver tissues (P < 0.0001). Hepcidin was also correlated with hematological parameters (vs. hemoglobin, P = 0.0073; vs. serum iron, P = 0.0012; vs. transferrin saturation, P < 0.0001) and transaminase levels (P = 0.0013). The hepcidin-to-ferritin ratio was significantly lower in HCV+ patients than in HBV+ patients (P = 0.0129) or control subjects (P = 0.0080). In conclusion, hepcidin expression levels in chronic liver diseases were strongly correlated with either the serum ferritin concentration or degree of iron deposits in the liver. When adjusted by either serum ferritin values or hepatic iron scores, hepcidin indices were significantly lower in HCV+ patients than in HBV+ patients, suggesting that hepcidin may play a pivotal role in the pathogenesis of iron overload in patients with chronic hepatitis C.
Hepcidin acts as the main regulator of iron homeostasis through regulation of intestinal absorption and macrophage release. Hepcidin deficiency causes iron overload whereas its overproduction is associated with anaemia of chronic diseases. The aims of the study were: to identify genetic variants in the hepcidin gene (HAMP) promoter, to asses the associations between the variants found and iron status parameters, and to functionally study the role on HAMP expression of the most frequent variant.
The sequencing of HAMP promoter from 103 healthy individuals revealed two genetic variants: The c.-153C > T with a frequency of 0.014 for allele T, which is known to reduce hepcidin expression and the c.-582A > G with a 0.218 frequency for allele G. In an additional group of 224 individuals, the c.-582A > G variant genotype showed no association with serum iron, transferrin or ferritin levels.
The c.-582G HAMP promoter variant decreased the transcriptional activity by 20% compared to c.-582A variant in cells from the human hepatoma cell line HepG2 when cotransfected with luciferase reporter constructs and plasmid expressing upstream stimulatory factor 1 (USF1) and by 12-14% when cotransfected with plasmid expressing upstream stimulatory factor 2 (USF2).
The c.-582A > G HAMP promoter variant is not associated with serum iron, transferrin or ferritin levels in the healthy population. The in vitro effect of the c.-582A > G variant resulted in a small reduction of the gene transactivation by allele G compared to allele A. Therefore the effect of the variant on the hepcidin levels in vivo would be likely negligible. Finally, the c.-153C > T variant showed a frequency high enough to be considered when a genetic analysis is done in iron overload patients.
In this case report we describe the relationship between ferritin levels and hepcidin in a patient with alcohol-related spur cell anemia who underwent liver transplantation. We demonstrate a reciprocal relationship between serum or urinary hepcidin and serum ferritin, which indicates that inadequate hepcidin production by the diseased liver is associated with elevated serum ferritin. The ferritin level falls with increasing hepcidin production after transplantation. Neither inflammatory indices (IL6) nor erythropoietin appear to be related to hepcidin expression in this case. We suggest that inappropriately low hepcidin production by the cirrhotic liver may contribute substantially to elevated tissue iron stores in cirrhosis and speculate that hepcidin replacement in these patients may be of therapeutic benefit in the future.
Alcohol; Iron; Anaemia; Hepcidin; Cirrhosis
The hepatic peptide hormone hepcidin regulates dietary iron absorption, plasma iron concentrations, and tissue iron distribution. Hepcidin acts by causing the degradation of its receptor, the cellular iron exporter ferroportin. The loss of ferroportin decreases iron flow into plasma from absorptive enterocytes, from macrophages that recycle the iron of senescent erythrocytes, and from hepatocytes that store iron, thereby lowering plasma iron concentrations. Malfunctions of the hepcidin-ferroportin axis contribute to the pathogenesis of different anemias. Deficient production of hepcidin causes systemic iron overload in iron-loading anemias such as beta-thalassemia; whereas hepcidin excess contributes to the development of anemia in inflammatory disorders and chronic kidney disease, and may cause erythropoietin resistance. The diagnosis of different forms of anemia will be facilitated by improved hepcidin assays, and the treatment will be enhanced by the development of hepcidin agonists and antagonists.
Recent research evidence suggests a central role for hepcidin in iron homeostasis. Hepcidin is a hormone synthesized in the liver. Hepcidin is also thought to play a vital role in the pathogenic mechanism of anaemia in patients with inflammation or chronic disease. A 38-year-old female who presented with recurrent abdominal pain was found to have raised urinary porphyrins and a blood lead level of 779 μg/l. Her haemoglobin level was 8.3 g/dl. Her MCV was normal. Serum ferritin, B12 and folate were normal. Her serum prohepcidin level was 2,489 ng/ml (normal <450 ng/ml). To our knowledge, this is the first report of raised prohepcidin levels in a patient with anaemia of chronic disease resulting from lead poisoning.
Hepcidin; Prohepcidin; Lead poisoning; Porphyrins; Abdominal pain; Sideroblastic anaemia
AIM: To assess the correlation between the serum hepcidin-25 level and left ventricular mass index.
METHODS: This study was a cross-sectional study conducted between March 2009 and April 2010. Demographic and biochemical data, including the serum hepcidin-25 level, were collected for chronic kidney disease (CKD) patients. Two-dimensional echocardiography was performed to determine the left ventricle mass (LVM), left ventricular mass index (LVMI), interventricular septum thickness (IVSd), left ventricle posterior wall thickness (LVPW), right ventricular dimension (RVD), left atrium (LA) and ejection fraction (EF).
RESULTS: A total of 146 patients with stage 1 to 5 CKD were enrolled. Serum hepcidin-25 levels were 16.51 ± 5.2, 17.59 ± 5.32, 17.38 ± 6.47, 19.98 ± 4.98 and 22.03 ± 4.8 ng/mL for stage 1 to 5 CKD patients, respectively. Hepcidin-25 level was independently predicted by the serum ferritin level (β = 0.6, P = 0.002) and the estimated glomerular filtration rate (β = -0.48, P = 0.04). There were negative correlations between the serum hepcidin level and the LVM and LVMI (P = 0.04 and P = 0.005, respectively). Systolic blood pressure (BP) was positively correlated with the LVMI (P = 0.005). In the multivariate analysis, a decreased serum hepcidin-25 level was independently associated with a higher LVMI (β = -0.28, 95%CI: -0.48 - -0.02, P = 0.006) after adjusting for body mass index, age and systolic BP.
CONCLUSION: A lower serum hepcidin level is associated with a higher LVMI in CKD patients. Low hepcidin levels may be independently correlated with unfavorable cardiovascular outcomes in this population.
Hepcidin-25; Ferritin; Chronic kidney disease; Left ventricular mass; Left ventricular mass index
The aim of this study was to analyze the relationship between serum pro-hepcidin concentration and the anemia profiles of rheumatoid arthritis (RA) and to estimate the pro-hepcidin could reflect the disease activity of RA. RA disease activities were measured using Disease Activity Score 28 (DAS28), tender/swollen joint counts, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). Anemia profiles such as hemoglobin, iron, total iron binding capacity (TIBC), ferritin, and transferrin levels were measured. Serum concentration of pro-hepcidin, the prohormone of hepcidin, was measured using enzyme-linked immunosorbent assay (ELISA). Mean concentration of serum pro-hepcidin was 237.6±67.9 ng/mL in 40 RA patients. The pro-hepcidin concentration was correlated with rheumatoid factor, CRP, ESR, and DAS28. There was a significant correlation between pro-hepcidin with tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. The pro-hepcidin concentration was significantly higher in the patients with active RA (DAS28>5.1) than those with inactive to moderate RA (DAS28≤5.1). However, the pro-hepcidin concentration did not correlate with the anemia profiles except hemoglobin level. There was no difference of pro-hepcidin concentration between the patients with anemia of chronic disease and those without. In conclusion, serum concentration of pro-hepcidin reflects the disease activity, regardless of the anemia states in RA patients, thus it may be another potential marker for disease activity of RA.
Arthritis, Rheumatoid; Anemia; Hepcidin; Prohepcidin
Anemia is a common finding among patients with chronic heart failure. Although co-morbidities, such as kidney failure, might contribute to the pathogenesis of anemia, many patients with heart failure do not have any other obvious etiology for their anemia. We investigated whether anemia in heart failure is associated with an elevation in hepcidin concentration.
We used time-of-flight mass spectrometry to measure hepcidin concentration in urine and serum samples of patients with heart failure and in control subjects. We found that the concentration of hepcidin was lower in urine samples of patients with heart failure compared to those of control subjects. Serum hepcidin was also reduced in heart failure but was not significantly lower than that in controls. There were no significant differences between hepcidin levels in patients with heart failure and anemia compared to patients with heart failure and normal hemoglobin. We concluded that hepcidin probably does not play a major role in pathogenesis of anemia in patients with chronic heart failure.
Anemias; Cytokines; Iron
The results of recent randomized, controlled trials in patients with chronic kidney disease and anemia have suggested that hyporesponsiveness to erythropoiesis stimulating agents (ESA) is a significant predictor of poor patient outcomes. Functional iron deficiency (FID) is the most common cause of suboptimal ESA response, and intravenous iron administration (IVFe) efficiently raises hemoglobin (Hb) concentrations even under the condition of FID. Consequently, renal anemia correction has conceptually shifted from ‘higher Hb values with high ESA doses’ to ‘prevention of ESA hyporesponsiveness with IVFe’. The discovery of hepcidin has profoundly changed our understanding of the place of FID in renal anemia therapy. Hepcidin reduces the abundance of iron transport proteins which facilitate iron absorption from the gut and iron mobilization from macrophages. Serum hepcidin is mainly modulated by iron stores, as is serum ferritin. High hepcidin or ferritin levels block intestinal iron absorption and iron recycling in macrophages and decrease iron availability for erythropoiesis, leading to FID. Iron administration, especially IVFe, increases hepcidin levels and concomitantly inhibits iron supply to erythroid cells. This in turn could lead to a vicious circle, exacerbating FID and increasing iron demand. Therefore, physicians should be cautious with unrestricted IVFe to chronic kidney disease patients with FID.
Hepcidin; Iron; Renal anemia; Erythropoiesis stimulating agents; Ferritin
The hepatic iron regulator hormone hepcidin consists, in its mature form, of 25 amino acids, but two other isoforms, hepcidin-20 and hepcidin-22, have been reported, whose biological meaning remains poorly understood. We evaluated hepcidin isoforms in sera from 57 control and 54 chronic haemodialysis patients using a quantitative proteomic approach based on SELDI-TOF-MS.
Patients had elevated serum levels of both hepcidin-25 and
hepcidin-20 as compared to controls (geometric means: 7.52 versus
4.69 nM, and 4.06 versus 1.76 nM, resp.,
P < .05 for both). The clearance effects of a single dialysis
session by different dialysis techniques and membranes were also
investigated, showing an average reduction by
51.3% ± 29.2% for hepcidin-25 and
34.2% ± 28.4% for hepcidin-20 but only minor differences among the different dialysis modalities. Measurement of hepcidin isoforms through MS-based techniques can be a useful tool for better understanding of their biological role in hemodialysis patients and other clinical conditions.
Hepcidin-25, the bioactive form of hepcidin, is a key regulator of iron homeostasis as it induces internalization and degradation of ferroportin, a cellular iron exporter on enterocytes, macrophages and hepatocytes. Hepcidin levels are increased in chronic hemodialysis (HD) patients, but as of yet, limited information on factors associated with hepcidin-25 in these patients is available. In the current cross-sectional study, potential patient-, laboratory- and treatment-related determinants of serum hepcidin-20 and -25, were assessed in a large cohort of stable, prevalent HD patients. Baseline data from 405 patients (62% male; age 63.7±13.9 [mean SD]) enrolled in the CONvective TRAnsport STudy (CONTRAST; NCT00205556) were studied. Predialysis hepcidin concentrations were measured centrally with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Patient-, laboratory- and treatment related characteristics were entered in a backward multivariable linear regression model. Hepcidin-25 levels were independently and positively associated with ferritin (p<0.001), hsCRP (p<0.001) and the presence of diabetes (p = 0.02) and inversely with the estimated glomerular filtration rate (p = 0.01), absolute reticulocyte count (p = 0.02) and soluble transferrin receptor (p<0.001). Men had lower hepcidin-25 levels as compared to women (p = 0.03). Hepcidin-25 was not associated with the maintenance dose of erythropoiesis stimulating agents (ESA) or iron therapy. In conclusion, in the currently studied cohort of chronic HD patients, hepcidin-25 was a marker for iron stores and erythropoiesis and was associated with inflammation. Furthermore, hepcidin-25 levels were influenced by residual kidney function. Hepcidin-25 did not reflect ESA or iron dose in chronic stable HD patients on maintenance therapy. These results suggest that hepcidin is involved in the pathophysiological pathway of renal anemia and iron availability in these patients, but challenges its function as a clinical parameter for ESA resistance.
Testosterone administration increases hemoglobin levels and has been used to treat anemia of chronic disease. Erythrocytosis is the most frequent adverse event associated with testosterone therapy of hypogonadal men, especially older men. However, the mechanisms by which testosterone increases hemoglobin remain unknown.
Testosterone administration in male and female mice was associated with a greater increase in hemoglobin and hematocrit, reticulocyte count, reticulocyte hemoglobin concentration, and serum iron and transferring saturation than placebo. Testosterone downregulated hepatic hepcidin mRNA expression, upregulated renal erythropoietin mRNA expression, and increased erythropoietin levels. Testosterone-induced suppression of hepcidin expression was independent of its effects on erythropoietin or hypoxia-sensing mechanisms. Transgenic mice with liver-specific constitutive hepcidin over-expression failed to exhibit the expected increase in hemoglobin in response to testosterone administration. Testosterone upregulated splenic ferroportin expression and reduced iron retention in spleen. After intravenous administration of transferrin-bound 58Fe, the amount of 58Fe incorporated into red blood cells was significantly greater in testosterone-treated mice than in placebo-treated mice. Serum from testosterone-treated mice stimulated hemoglobin synthesis in K562 erythroleukemia cells more than that from vehicle-treated mice. Testosterone administration promoted the association of androgen receptor (AR) with Smad1 and Smad4 to reduce their binding to BMP-response elements in hepcidin promoter in the liver. Ectopic expression of AR in hepatocytes suppressed hepcidin transcription; this effect was blocked dose-dependently by AR antagonist flutamide. Testosterone did not affect hepcidin mRNA stability. Conclusion: Testosterone inhibits hepcidin transcription through its interaction with BMP-Smad signaling. Testosterone administration is associated with increased iron incorporation into red blood cells.
Hepcidin is a major regulator of iron metabolism and plays a key role in anemia of chronic disease, reducing intestinal iron uptake and release from body iron stores. Hypoxia and chemical stabilizers of the hypoxia-inducible transcription factor (HIF) have been shown to suppress hepcidin expression. We therefore investigated the role of HIF in hepcidin regulation.
Hepcidin mRNA was down-regulated in hepatoma cells by chemical HIF stabilizers and iron chelators, respectively. In contrast, the response to hypoxia was variable. The decrease in hepcidin mRNA was not reversed by HIF-1α or HIF-2α knock-down or by depletion of the HIF and iron regulatory protein (IRP) target transferrin receptor 1 (TfR1). However, the response of hepcidin to hypoxia and chemical HIF inducers paralleled the regulation of transferrin receptor 2 (TfR2), one of the genes critical to hepcidin expression. Hepcidin expression was also markedly and rapidly decreased by serum deprivation, independent of transferrin-bound iron, and by the phosphatidylinositol 3 (PI3) kinase inhibitor LY294002, indicating that growth factors are required for hepcidin expression in vitro. Hepcidin promoter constructs mirrored the response of mRNA levels to interleukin-6 and bone morphogenetic proteins, but not consistently to hypoxia or HIF stabilizers, and deletion of the putative HIF binding motifs did not alter the response to different hypoxic stimuli. In mice exposed to carbon monoxide, hypoxia or the chemical HIF inducer N-oxalylglycine, liver hepcidin 1 mRNA was elevated rather than decreased.
Taken together, these data indicate that hepcidin is neither a direct target of HIF, nor indirectly regulated by HIF through induction of TfR1 expression. Hepcidin mRNA expression in vitro is highly sensitive to the presence of serum factors and PI3 kinase inhibition and parallels TfR2 expression.
The hepatic peptide hormone hepcidin controls the duodenal absorption of iron, its storage and its systemic distribution. Hepcidin production is often insufficient in chronic hepatitis C and alcoholic liver disease, leading to hyperabsorption of iron and its accumulation in the liver. Hepatocyte growth factor (HGF) and epidermal growth factor (EGF) mediate the hepatic regeneration after liver injury. We examined the effect of the growth factors on hepcidin synthesis by hepatocytes. Results: HGF and EGF treatment of primary mouse hepatocytes, as well as EGF administration in mice, suppressed hepcidin mRNA synthesis. The suppression of hepcidin by these growth factors was transcriptional, and was mediated by a direct effect of HGF and EGF on the BMP pathway regulating hepcidin synthesis. We further showed that growth factors interfered with nuclear localization of activated Smads and increased the nuclear pool of the BMP transcriptional co-repressor TG-interacting factor (TGIF). In a kinase screen with small-molecule kinase inhibitors, inhibitors in the PI3 kinase pathway and in the MEK/ERK pathway prevented HGF suppression of hepcidin in primary mouse hepatocytes. Conclusion: HGF and EGF suppress hepatic hepcidin synthesis, in part through PI3 kinase MEK/ERK kinase pathways which may be modulating the nuclear localization of BMP pathway transcriptional regulators including activated Smads1/5/8 and the co-repressor TGIF. EGF, HGF and possibly other growth factors that activate similar pathways may contribute to hepcidin suppression in chronic liver diseases, promote iron accumulation in the liver and exacerbate the destructive disease processes.
Chronic liver disease; iron overload; hepatocyte growth factor; epidermal growth factor; bone morphogenetic protein pathway
Anemia of inflammation (AI) is a common complication of rheumatoid arthritis (RA) and has a negative impact on RA symptoms and quality of life. Upregulation of hepcidin by inflammatory cytokines has been implicated in AI. In this study, we evaluated and compared the effects of IL-6 and TNF-α blocking therapies on anemia, disease activity, and iron-related parameters including serum hepcidin in RA patients.
Patients (n = 93) were treated with an anti-IL-6 receptor antibody (tocilizumab) or TNF-α inhibitors for 16 weeks. Major disease activity indicators and iron-related parameters including serum hepcidin-25 were monitored before and 2, 4, 8, and 16 weeks after the initiation of treatment. Effects of tocilizumab and infliximab (anti-TNF-α antibody) on cytokine-induced hepcidin expression in hepatoma cells were analyzed by quantitative real-time PCR.
Anemia at base line was present in 66% of patients. Baseline serum hepcidin-25 levels were correlated positively with serum ferritin, C-reactive protein (CRP), vascular endothelial growth factor (VEGF) levels and Disease Activity Score 28 (DAS28). Significant improvements in anemia and disease activity, and reductions in serum hepcidin-25 levels were observed within 2 weeks in both groups, and these effects were more pronounced in the tocilizumab group than in the TNF-α inhibitors group. Serum hepcidin-25 reduction by the TNF-α inhibitor therapy was accompanied by a decrease in serum IL-6, suggesting that the effect of TNF-α on the induction of hepcidin-25 was indirect. In in vitro experiments, stimulation with the cytokine combination of IL-6+TNF-α induced weaker hepcidin expression than did with IL-6 alone, and this induction was completely suppressed by tocilizumab but not by infliximab.
Hepcidin-mediated iron metabolism may contribute to the pathogenesis of RA-related anemia. In our cohort, tocilizumab was more effective than TNF-α inhibitors for improving anemia and normalizing iron metabolism in RA patients by inhibiting hepcidin production.
Patients with chronic hepatitis C (CHC) often have increased liver iron, a condition associated with reduced sustained response to antiviral therapy, more rapid progression to cirrhosis, and development of hepatocellular carcinoma. The hepatic hormone hepcidin is the major regulator of iron metabolism and inhibits iron absorption and recycling from erythrophagocytosis. Hepcidin decrease is a possible pathophysiological mechanism of iron overload in CHC, but studies in humans have been hampered so far by the lack of reliable quantitative assays for the 25-amino acid bioactive peptide in serum (s-hepcidin).
Using a recently validated immunoassay, we measured s-hepcidin levels in 81 untreated CHC patients and 57 controls with rigorous definition of normal iron status. All CHC patients underwent liver biopsy with histological iron score.
S-hepcidin was significantly lower in CHC patients than in controls (geometric means with 95% confidence intervals: 33.7, 21.5–52.9 vs. 90.9, 76.1–108.4 ng/mL, respectively; p < 0.001). In CHC patients, s-hepcidin significantly correlated with serum ferritin and histological total iron score, but not with s-interleukin-6. After stratification for ferritin quartiles, s-hepcidin increased significantly across quartiles in both controls and CHC patients (chi for trend, p < 0.001). However, in CHC patients, s-hepcidin was significantly lower than in controls for each corresponding quartile (analysis of variance, p < 0.001).
These results, together with very recent studies in animal and cellular models, indicate that although hepcidin regulation by iron stores is maintained in CHC, the suppression of this hormone by hepatitis C virus is likely an important factor in liver iron accumulation in this condition.
Chronic hepatitis C; Hemochromatosis; Hepcidin; Iron overload; Ferritin
Hepatitis C viral infection affects 170 million people worldwide. It causes serious chronic liver diseases. HCV infection has been implicated in iron accumulation in the liver and iron overload has been shown to be a potential cofactor for HCV associated hepatocellular carcinoma progression. The underlying mechanisms are not understood. Human hepcidin, a 25 amino acid peptide mainly produced by hepatocytes, is a key regulator of iron metabolism. Alteration of hepcidin expression levels has been reported in the setting of chronic HCV infection and hepatocellular carcinoma. In this study, we aim to examine the interactions between HCV infection and hepcidin expression in liver cells. We found that hepcidin expression was suppressed in HCV infected cells. The suppressive effect appears to be regulated by histone acetylation but not DNA methylation. Moreover, we found that hepcidin had a direct antiviral activity against HCV replication in cell culture. The antiviral effect is associated with STAT3 activation. In conclusion, hepcidin can induce intracellular antiviral state while HCV has a strategy to suppress hepcidin expression. This may be a novel mechanism by which HCV circumvents hepatic innate antiviral defense.
Hepcidin is a peptide hormone secreted by the liver that plays a central role in the regulation of iron homeostasis. Increased hepcidin levels result in anemia while decreased expression is the causative feature in most primary iron overload diseases. Mutations in hemochromatosis type 2 (HFE2), which encodes the protein hemojuvelin (HJV), result in the absence of hepcidin and an early-onset form of iron overload disease. HJV is a bone morphogenetic protein (BMP) coreceptor and HJV mutants have impaired BMP signaling. In this issue of the JCI, Babitt and colleagues show that BMPs are autocrine hormones that induce hepcidin expression (see the related article beginning on page 1933). Administration of a recombinant, soluble form of HJV decreased hepcidin expression and increased serum iron levels by mobilizing iron from splenic stores. These results demonstrate that recombinant HJV may be a useful therapeutic agent for treatment of the anemia of chronic disease, a disorder resulting from high levels of hepcidin expression.
A debilitating anemia associated with low serum iron often accompanies inflammatory bowel disease (IBD). Increased production of the iron regulatory hormone hepcidin is implicated in its pathogenesis and may also contribute to the inflammatory process itself. Hepcidin expression is dependent on bone morphogenetic proteins (BMPs) like BMP6, but the mechanisms that increase hepcidin levels during intestinal inflammation are not clear. Here, we test the hypothesis that inhibiting hepcidin expression may have beneficial effects in IBD, and also shed light on the mechanism of colitis-induced hepcidin up-regulation.
Mice with T cell transfer colitis were treated with vehicle or one of three anti-BMP reagents – HJV.Fc, a recombinant protein that prevents binding of BMPs to their receptor, LDN-193189, a small molecule inhibitor of BMP signal transduction, and an anti-BMP6 antibody. The effects of these reagents on colitis severity, liver hepcidin mRNA and serum iron were determined. The mechanism of hepcidin up-regulation was investigated by examining BMP6 expression and activity and the effects of IL-6 deficiency.
All the anti-BMP reagents inhibited hepcidin expression and increased serum iron levels in the colitic mice. They also produced modest reductions in colon inflammatory cytokine expression. Although hepcidin up-regulation during colitis was dependent on BMP6, it was not associated with increased BMP6 expression or activity. IL-6 was required for increased hepcidin expression during colitis.
Inhibiting hepcidin expression may help to correct the anemia of IBD and may also attenuate intestinal inflammation. The mechanism of colitis-induced hepcidin up-regulation involves both BMP6 and IL-6.
Inflammation; iron; bone morphogenetic protein; hepcidin
A decade ago hepcidin, an antimicrobial peptide with iron-regulatory properties, was discovered and proposed as playing a significant role in the pathogenesis of the anemia of chronic disease. Subsequent studies have demonstrated that hepcidin is the keystone of the linked systems of iron balance and iron transport in health and in disease. The definition of the role of hepcidin and of its regulation has permitted the mechanisms of disorders of iron homeostasis to be understood at a molecular level. Future studies may identify roles for hepcidin or hepcidin-related molecules in diagnosis and therapy.
Iron; hepcidin; hemochromatosis; anemia