Hepcidin and iron metabolism: From laboratory to clinical implications

Right-Ventricle Heart Failure in PAH vs. HFrEF with Secondary PH: Hemodynamic, Ergospirometric, and Organ Function Correlations

PURPOSE

The goal of the study was to identify markers of organ function used in daily routines that could potentially aid in the overall evaluation of the cardiovascular system in patients with right-ventricle heart failure due to pulmonary arterial hypertension (PAH) and left-ventricle heart failure. We analyzed correlations between parameters from right heart catheterization (RHC), cardiopulmonary exercise test (CPET), and selected laboratory parameters of thyroid, liver, kidneys function and iron homeostasis.

PATIENTS AND METHODS

A retrospective analysis included 107 patients (mean age 57.6±16.2; 34.6% women), comprising 57 patients with PAH (mean age 54.0±18.2; 49.1% women) and 50 patients with heart failure with reduced ejection fraction (HFrEF) <40% (mean age 61.6±12.7; 18% women). All patients underwent CPET. Each patient in the PAH group had RHC performed. Fifteen patients from the HFrEF group underwent RHC, which confirmed the suspicion of pulmonary hypertension (HFrEF-SPH).

RESULTS

CPET and laboratory parameters' analysis showed strong correlations between ventilation/carbon dioxide production (VE/VCO2) slope and NT-proBNP in HFrEF without secondary PH and HFrEF-SPH groups. In the PAH group, VE/VCO2 slope correlated with liver and thyroid function but also with morphological parameters of red-cell system. Analysis of correlations between laboratory and hemodynamic parameters revealed significant correlations between pulmonary arterial pressure, pulmonary vascular resistance (PVR) and red-cell parameters, especially strong with fT4 in the PAH group.

CONCLUSIONS

In HFrEF-SPH patients, laboratory parameters strongly correlated with pulmonary pressures and pulmonary capillary wedge pressure (PCWP).

Iron accumulation induced by hepcidin1 knockout accelerates the progression of aging osteoporosis

OBJECTIVE

Iron accumulation is associated with osteoporosis. This study aims to explore the effect of chronic iron accumulation induced by hepcidin1 deficiency on aging osteoporosis.

METHODS

Iron accumulation in hepcidin1 knockout aging mice was assessed by atomic absorption spectroscopy and Perl's staining. Bone microarchitecture was observed using Micro-CT. Hepcidin, ferritin, oxidative stress, and markers of bone turnover in serum were detected by enzyme-linked immunosorbent assay. Bone formation and resorption markers were measured by real-time quantitative PCR. Cell aging was induced by D-galactose treatment. CCK-8, flow cytometry, EdU assays, and Alizarin red staining were performed to reveal the role of hepcidin1 knockout in cell model. Iron Colorimetric Assay Kit and western blot were applied to detect iron and ferritin levels in cells, respectively.

RESULTS

In hepcidin1-knockout mice, the ferritin and iron contents in liver and tibia were significantly increased. Iron accumulation induced by hepcidin1 knockout caused a phenotype of low bone mass and deteriorated bone microarchitecture. Osteogenic marker was decreased and osteoclast marker was increased in mice, accompanied by increased oxidative stress level. The mRNA expression levels of osteoclast differentiation markers (RANKL, Mmp9, OPG, Trap, and CTSK) were up-regulated, while bone formation markers (OCN, ALP, Runx2, SP7, and Col-1) were down-regulated in model group, compared to wild type mice. In vitro, hepcidin1 knockdown inhibited proliferation and osteogenic differentiation, while promoted apoptosis, with increased levels of iron and ferritin.

CONCLUSION

Iron accumulation induced by hepcidin1 deficiency aggravates the progression of aging osteoporosis via inhibiting osteogenesis and promoting osteoclast genesis.

Iron Deficiency in Heart Failure: A Scientific Statement from the Heart Failure Society of America

Iron deficiency is present in approximately 50% of patients with symptomatic heart failure and is independently associated with worse functional capacity, lower quality of, life and increased mortality. The purpose of this document is to summarize current knowledge of how iron deficiency is defined in heart failure and its epidemiology and pathophysiology, as well as pharmacological considerations for repletion strategies. This document also summarizes the rapidly expanding array of clinical trial evidence informing when, how, and in whom to consider iron repletion.

Emerging role of ferroptosis in breast cancer: New dawn for overcoming tumor progression

Breast cancer has become a serious threat to women's health. Cancer progression is mainly derived from resistance to apoptosis induced by procedures or therapies. Therefore, new drugs or models that can overcome apoptosis resistance should be identified. Ferroptosis is a recently identified mode of cell death characterized by excess reactive oxygen species-induced lipid peroxidation. Since ferroptosis is distinct from apoptosis, necrosis and autophagy, its induction successfully eliminates cancer cells that are resistant to other modes of cell death. Therefore, ferroptosis may become a new direction around which to design breast cancer treatment. Unfortunately, the complete appearance of ferroptosis in breast cancer has not yet been fully elucidated. Furthermore, whether ferroptosis inducers can be used in combination with traditional anti- breast cancer drugs is still unknown. Moreover, a summary of ferroptosis in breast cancer progression and therapy is currently not available. In this review, we discuss the roles of ferroptosis-associated modulators glutathione, glutathione peroxidase 4, iron, nuclear factor erythroid-2 related factor-2, superoxide dismutases, lipoxygenase and coenzyme Q in breast cancer. Furthermore, we provide evidence that traditional drugs against breast cancer induce ferroptosis, and that ferroptosis inducers eliminate breast cancer cells. Finally, we put forward prospect of using ferroptosis inducers in breast cancer therapy, and predict possible obstacles and corresponding solutions. This review will deepen our understanding of the relationship between ferroptosis and breast cancer, and provide new insights into breast cancer-related therapeutic strategies.

Anaemia and iron deficiency in patients with rheumatoid arthritis and other chronic diseases

Anaemia is one of the most common symptoms accompanying many chronic diseases, e.g. collagenases, neoplasms, and chronic inflammations (inflammatory bowel disease, chronic kidney disease and heart failure). Iron deficiency anaemia is the most common type of anaemia (80%). It affects 1% to 2% of the population. Iron deficiency (ID) – absolute or functional – is characterised by reduced ferritin levels and transferrin saturation (TSAT) of less than 20%. Iron deficiency is the most common dietary deficiency. However, iron deficiency might be one of the common causes of anaemia of chronic disease (ACD). Anaemia affects 33% to 60% of patients with RA. Rheumatoid arthritis (RA) is a chronic immune-mediated systemic connective tissue disease, in which chronic inflammation of the synovial tissue of the joints damages articular cartilages, bones and other joint structures. The prevalence of RA is approximately 0.3% to 2%. Low haemoglobin levels in RA patients are significantly correlated with disability, activity and duration of the disease as well as damage to joints and joint pain. Treatment of anaemia in RA patients includes iron supplementation, blood transfusions, the use of erythropoiesis-stimulating agents, and treatment of the underlying condition. Biological treatments used in RA patients, such as e.g. infliximab, tocilizumab and anakinra, not only slow the progression of joint involvement but also prevent anaemia.

Monitoring of iron status in patients with heart failure

The 2016 ESC/HFA heart failure (HF) guidelines emphasize the importance of identifying and treating iron deficiency (ID) in patients with HF. Iron deficiency can occur in half or more of HF sufferers, depending on age and the phase of the disease. Iron deficiency can be a cause of anaemia, but it is also common even without anaemia, meaning that ID is a separate entity, which should be screened for within the HF population. Although assessment of iron stores in bone marrow samples is the most accurate method to investigate iron status, it is not practical in most HF patients. Levels of circulating iron biomarkers are an easily available alternative; especially, ferritin and transferrin saturation (Tsat). In patients with HF serum ferritin level <100 µg/L (regardless of Tsat value) or between 100 and 299 µg/L with Tsat <20% are considered as recommended criteria for the diagnosis of ID, criteria which have been used in the clinical trials in HF that have led to a recommendation to treat ID with intravenous iron. We discuss the optimal measures of iron biomarkers in patients with HF in order to screen and monitor iron status and introduce some novel ways to assess iron status.

Menstrual blood losses and body mass index are associated with serum ferritin concentrations among female varsity athletes

Preventing and treating iron deficiency are important components in the nutritional care of female varsity athletes, as these interventions may improve aerobic endurance and athletic performance. We examined the factors associated with ferritin concentration in 30 female varsity athletes (18-30 years) at the University of British Columbia in Vancouver, Canada. Biochemical indicators of iron and inflammation status, dietary intake, supplementation practices, weight, height, and menstrual blood losses were assessed. Iron deficiency prevalence was 20% (n = 6/30; inflammation-adjusted ferritin <15 μg/L). Multiple linear regression was used to assess the associations of a number of independent explanatory variables with log-transformed serum ferritin (μg/L) as the continuous outcome variable. A 1-unit increase in body mass index (BMI; kg/m²) was associated with 22% (95% CI: 9%-37%) higher mean ferritin concentrations, and a 1-point increase in menstrual loss score was associated with 1% (95% CI: 1%-2%) lower ferritin concentrations. Hemoglobin and hepcidin concentrations, inflammation biomarkers, consumption of iron supplements in any form or dose for ≥3 days/week, and age were not significantly associated with ferritin concentrations in the final adjusted model. Novelty Estimated monthly menstrual losses and BMI were associated with serum ferritin concentrations in female athletes in our study. These are easy-to-measure, noninvasive measurements that should be considered in the assessment of risk of iron deficiency in female athletes.

Role of Dietary Flavonoids in Iron Homeostasis

Balancing systemic iron levels within narrow limits is critical for human health, as both iron deficiency and overload lead to serious disorders. There are no known physiologically controlled pathways to eliminate iron from the body and therefore iron homeostasis is maintained by modifying dietary iron absorption. Several dietary factors, such as flavonoids, are known to greatly affect iron absorption. Recent evidence suggests that flavonoids can affect iron status by regulating expression and activity of proteins involved the systemic regulation of iron metabolism and iron absorption. We provide an overview of the links between different dietary flavonoids and iron homeostasis together with the mechanism of flavonoids effect on iron metabolism. In addition, we also discuss the clinical relevance of state-of-the-art knowledge regarding therapeutic potential that flavonoids may have for conditions that are low in iron such as anaemia or iron overload diseases.

Efficacy and safety of iron supplementation in patients with heart failure and iron deficiency: a meta-analysis

Fe therapy can be effective in heart failure patients both with and without anaemia. However, the role of Fe therapy in such patients is still uncertain. In this review, the aim was to evaluate the efficacy and safety of Fe therapy in adult patients with heart failure who have reduced ejection fraction (HFrEF). Multiple databases (PubMed, Medline, EMBASE, the Cochrane Library and Clinical Trials) were searched up to December 2017 and the reference lists of relevant articles obtained from the search were reviewed. Data extracted from randomised control trials (RCT) selected for the review were pooled using a fixed effects model or a random effects model, according to heterogeneity between trials. Nine RCT were included in this meta-analysis which included a total of 789 patients who received Fe therapy and who in turn were compared with 585 controls. There was significant improvement in the 6-min walk test (19·05 m, 95 % CI 10·48, 27·62) and peak VO2/kg (0·93 ml/kg per min, 95 % CI 0·16, 1·69) in the Fe supplementation arm. With Fe therapy, fewer patients were hospitalised for heart failure (OR: 0·42, 95 % CI 0·27, 0·65), but no relationship was found for total re-hospitalisation (OR: 0·70, 95 % CI 0·32, 1·51) or mortality (OR: 0·70, 95 % CI 0·38, 1·28). Fe therapy has the potential to improve exercise tolerance, reduce re-hospitalisations for patients with HFrEF having Fe deficiency. In addition, Fe supplementation was found to be safe, with no increased rate of adverse events.

Oxidative Stress and Cardiovascular Complications in Chronic Kidney Disease, the Impact of Anaemia

Patients with chronic kidney disease (CKD) have significant cardiovascular morbidity and mortality as a result of risk factors such as left ventricular hypertrophy (LVH), oxidative stress, and inflammation. The presence of anaemia in CKD further increases the risk of LVH and oxidative stress, thereby magnifying the deleterious consequence in uraemic cardiomyopathy (UCM), and aggravating progression to failure and increasing the risk of sudden cardiac death. This short review highlights the specific cardio-renal oxidative stress in CKD and provides an understanding of the pathophysiology and impact of uraemic toxins, inflammation, and anaemia on oxidative stress.

Prevalence of anemia in hospitalized internal medicine patients: Correlations with comorbidities and length of hospital stay

BACKGROUND

Several studies have documented a linear growth of the prevalence of anemia with aging. Especially in hospitalized elderly patients, anemia can aggravate the course of chronic disorders, and ultimately get worse the clinical outcomes.

METHODS

To evaluate the distribution, the main causes, and the possible correlations of anemia with comorbidities and length of hospitalization in a population of internal medicine inpatients, we carried out an observational study on a cohort of 923 consecutive admissions relative to 856 subjects.

RESULTS

Anemia was observed in 58.4% of patients, with an increase of the prevalence with increasing age regardless gender difference. In more than one-half of anemic patients, anemia was mild. Chronic inflammation and chronic renal failure were the most frequent causes of anemia in our population, and in >35% of patients a multifactorial anemia was diagnosed. Age, chronic renal failure, chronic liver disease, hematological malignancies, solid tumors, and antiplatelet therapy showed a significantly independent association with the presence of anemia. Hemoglobin levels were influenced by the presence of chronic lung disease, chronic renal failure, hematological malignancies, solid tumors, and antiplatelet therapy. The presence and the degree of anemia also correlated with a significantly longer hospital stay.

CONCLUSIONS

Our data confirm the high prevalence of anemia in patients hospitalized in an Internal Medicine Department, with a remarkable burden of mild forms, and of chronic inflammation's pathogenic mechanism. Correlations with comorbidities and duration of hospital stay highlight the crucial part played by anemia in determining the clinical complexity of such patients.

Association of iron metabolic enzyme hepcidin expression levels with the prognosis of patients with pancreatic cancer

Hepcidin and ferroportin, which are known as key iron regulators, may be used in future treatments of pancreatic ductal adenocarcinoma. Iron is essential for life support; it helps oxygen molecules bind to hemoglobin and acts as an important catalytic enzyme center. However, iron overload is a risk factor for cancer, possibly through the generation of reactive oxygen species (ROS). Hepcidin, which is a peptide hormone mainly generated by the liver, inhibits iron absorption via enterocytes and iron release from macrophages. Notably, hepcidin regulates iron homeostasis in the body by regulating the iron transporter ferroportin. In the present study, it was assumed that high hepcidin expression and low ferroportin expression result in malignancy. Therefore, it was examined whether hepcidin and ferroportin expression levels were correlated with the prognosis of pancreatic cancer in patients. Results revealed that high hepcidin expression levels and low ferroportin expression levels in pancreatic cancer tissue were significantly associated with poor prognosis in the analyses of overall survival (P=0.0140 and 0.0478, respectively). Additionally, there was no significant difference in disease-free survival in the hepcidin- and ferroportin-staining groups. Hepcidin expression correlated with the pathological stage and vascular invasion (P=0.0493 and 0.0400, respectively), and ferroportin expression was correlated with age (P=0.0372). Multivariate analysis of overall survival in the hepcidin-staining group revealed that pathological N factor (pN), adjuvant chemotherapy, and hepcidin expression were independent prognostic factors (P=0.0450, 0.0002, and 0.0049, respectively). Similarly, multivariate analysis of overall survival in the ferroportin-staining group revealed that vascular invasion, and ferroportin expression were independent prognostic factors (P=0.0028, P<0.0001, and P=0.0056, respectively). Thus, hepcidin and ferroportin expressions might be novel prognostic indicators for pancreatic cancer.

Impact of iron deficiency on long-term clinical outcomes of hospitalized patients with heart failure

BACKGROUND

Iron deficiency (ID) is commonly observed in chronic heart failure (HF) patients and is associated with worse clinical outcomes. While ID is frequent finding in hospitalized heart failure (HHF), its impact on long-term outcome in HHF patients remains unclear.

METHODS

We evaluated iron status at discharge in 578 HHF patients. Absolute ID was defined as serum ferritin <100 μg/L, and functional ID (FID) was defined as serum ferritin of 100-299 μg/L with transferrin saturation <20%. The primary outcome of interest was the composite of all-cause mortality and HF admission at one year.

RESULTS

Among the study population, 185 had absolute ID, 88 had FID and 305 had no evidence of ID. At one-year post-discharge, 64 patients had died and 112 had been readmitted with HF. Patients with absolute ID had more adverse events than those with FID or no ID (p = 0.021). In multivariate Cox regression analyses, absolute ID was significantly associated with increased risk of adverse events at one year (HR 1.50, 95% CI 1.02-2.21, p = 0.040) compared with the remaining patients. Sensitivity analysis revealed that its prognostic effect did not differ across anemic status, or between HF with reduced and preserved ejection fraction (p for interaction = 0.17, 0.68, respectively).

CONCLUSION

Absolute ID, but not FID, at discharge was associated with increased risk of one-year mortality or HF admission in patients with HHF. Further studies are required to evaluate the role of repleting iron stores and its impact on clinical outcomes in patients with HHF.

Effect of Oral Iron Repletion on Exercise Capacity in Patients With Heart Failure With Reduced Ejection Fraction and Iron Deficiency: The IRONOUT HF Randomized Clinical Trial

IMPORTANCE

Iron deficiency is present in approximately 50% of patients with heart failure with reduced left ventricular ejection fraction (HFrEF) and is an independent predictor of reduced functional capacity and mortality. However, the efficacy of inexpensive readily available oral iron supplementation in heart failure is unknown.

OBJECTIVE

To test whether therapy with oral iron improves peak exercise capacity in patients with HFrEF and iron deficiency.

DESIGN, SETTING, AND PARTICIPANTS

Phase 2, double-blind, placebo-controlled randomized clinical trial of patients with HFrEF (<40%) and iron deficiency, defined as a serum ferritin level of 15 to 100 ng/mL or a serum ferritin level of 101 to 299 ng/mL with transferrin saturation of less than 20%. Participants were enrolled between September 2014 and November 2015 at 23 US sites.

INTERVENTIONS

Oral iron polysaccharide (n = 111) or placebo (n = 114), 150 mg twice daily for 16 weeks.

MAIN OUTCOMES AND MEASURES

The primary end point was a change in peak oxygen uptake (V̇o2) from baseline to 16 weeks. Secondary end points were change in 6-minute walk distance, plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, and health status as assessed by Kansas City Cardiomyopathy Questionnaire (KCCQ, range 0-100, higher scores reflect better quality of life).

RESULTS

Among 225 randomized participants (median age, 63 years; 36% women) 203 completed the study. The median baseline peak V̇o2 was 1196 mL/min (interquartile range [IQR], 887-1448 mL/min) in the oral iron group and 1167 mL/min (IQR, 887-1449 mL/min) in the placebo group. The primary end point, change in peak V̇o2 at 16 weeks, did not significantly differ between the oral iron and placebo groups (+23 mL/min vs -2 mL/min; difference, 21 mL/min [95% CI, -34 to +76 mL/min]; P = .46). Similarly, at 16 weeks, there were no significant differences between treatment groups in changes in 6-minute walk distance (-13 m; 95% CI, -32 to 6 m), NT-proBNP levels (159; 95% CI, -280 to 599 pg/mL), or KCCQ score (1; 95% CI, -2.4 to 4.4), all P > .05.

CONCLUSIONS AND RELEVANCE

Among participants with HFrEF with iron deficiency, high-dose oral iron did not improve exercise capacity over 16 weeks. These results do not support use of oral iron supplementation in patients with HFrEF.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02188784.

Iron Deficiency Treatment in Patients with Heart Failure

Iron deficiency (ID) is one of the major risk factors for disability and mortality worldwide, and it was identified as a common and ominous comorbidity in patients with heart failure (HF), both with and without anaemia. Based on two clinical trials (FAIR-HF and CONFIRM-HF) and other epidemiological evidence, ID has been recognized as an important therapeutic target in symptomatic patients with HF and LVEF ≤45%.Intravenous iron supplementation has been demonstrated to be safe and effective for iron repletion and related with an improvement in clinical status, exercise capacity, and quality of life. Ongoing trials are testing the hypothesis that such a therapy may also reduce the risk of HF hospitalizations and cardiovascular death.

Hepcidin Plays a Key Role in 6-OHDA Induced Iron Overload and Apoptotic Cell Death in a Cell Culture Model of Parkinson's Disease

Background. Elevated brain iron levels have been implicated in the pathogenesis of Parkinson's disease (PD). However, the precise mechanism underlying abnormal iron accumulation in PD is not clear. Hepcidin, a hormone primarily produced by hepatocytes, acts as a key regulator in both systemic and cellular iron homeostasis. Objective. We investigated the role of hepcidin in 6-hydroxydopamine (6-OHDA) induced apoptosis in a cell culture model of PD. Methods. We downregulated hepcidin using siRNA interference in N27 dopaminergic neuronal cells and made a comparison with control siRNA transfected cells to investigate the role of hepcidin in 6-OHDA induced neurodegeneration. Results. Hepcidin knockdown (32.3%, P < 0.0001) upregulated ferroportin 1 expression and significantly (P < 0.05) decreased intracellular iron by 25%. Hepcidin knockdown also reduced 6-OHDA induced caspase-3 activity by 42% (P < 0.05) and DNA fragmentation by 29% (P = 0.086) and increased cell viability by 22% (P < 0.05). In addition, hepcidin knockdown significantly attenuated 6-OHDA induced protein carbonyls by 52% (P < 0.05) and intracellular iron by 28% (P < 0.01), indicating the role of hepcidin in oxidative stress. Conclusions. Our results demonstrate that hepcidin knockdown protected N27 cells from 6-OHDA induced apoptosis and that hepcidin plays a major role in reducing cellular iron burden and oxidative damage by possibly regulating cellular iron export mediated by ferroportin 1.

Total Iron Bioavailability from the US Diet Is Lower Than the Current Estimate

BACKGROUND

Total (heme and nonheme) iron bioavailability from the US diet has been estimated to be 18% based on a single human absorption study. New data, however, suggest that it may be time to revisit this estimate.

OBJECTIVE

We estimated total iron bioavailability from the US diet with the use of our recently reported algorithm that estimates nonheme iron absorption and a conservative value for heme iron absorption.

METHODS

We used dietary intake and biomarker information from the NHANES 2001-2002, MyPyramid Equivalents Database, and Food and Nutrient Database for Dietary Studies. The survey package in R software was used to estimate means and CIs, taking into account the strata, primary sampling units, and appropriate survey weight. We implemented 2 different approaches to estimate total iron absorption. In the first approach, we included all survey participants but adjusted the geometric mean of nonheme iron absorption to 15 μg ferritin/L serum to mimic values of individuals with no iron stores; in the second approach, absorption was estimated for only nonanemic subjects with no iron stores. A total sample size of 6631 was used based on availability of dietary and iron status biomarker data and C-reactive protein concentration ≤ 6 mg/L.

RESULTS

The geometric mean (95% CI) of unadjusted nonheme iron absorption for all subjects was 3.7% (3.6%, 3.8%), higher in female subjects [5.6% (5.4%, 5.7%)] than male subjects [2.6% (2.5%, 2.7%)] (P < 0.0001). Nonheme iron absorption was lower in non-Hispanic whites [3.5% (3.4%, 3.6%)] than Mexican Americans [4.5% (4.2%, 4.8%)] and non-Hispanic blacks [4.4% (4.1%, 4.7%)]. Estimated total iron absorption was 15.5% or 15.1%, depending on which approach was used to carry out the calculations.

CONCLUSION

This study provides useful data for evaluating the current value of iron bioavailability from the US diet.

Serum hepcidin concentrations and type 2 diabetes

Hepcidin is a peptide hormone with both paracrine and endocrine functions that help in maintaining body iron stores. Type 2 diabetes (T2D) is one of the sequelae of excess body iron stores; thus, iron regulatory hormone hepcidin may have a direct or at least an indirect role in the aetiopathogenesis of T2D. Both human and animal studies at molecular and genetic levels have attempted to establish a role for hepcidin in the development of T2D, and a few epidemiologic studies have also showed a link between hepcidin and T2D at population level, but the findings are still inconclusive. Recent data have suggested different pathways in which hepcidin could be associated with T2D with much emphasis on its primary or secondary role in insulin resistance. Some of the suggested pathways are via transcription modulator of hepcidin (STAT3); ferroportin 1 expression on the cells involved in iron transport; transmembrane protease 6 enzyme; and pro-inflammatory cytokines, interleukin (IL)-1, IL-6, tumor necrosis factor-α and IL-10. This review briefly reports the existing evidence on the possible links between hepcidin and T2D and concludes that more data are needed to confirm or refute hepcidin’s role in the development of T2D. Examining this role could provide a further evidence base for iron in the aetiopathogenesis of T2D.

Low transferrin saturation is associated with impaired fasting glucose and insulin resistance in the South Korean adults: the 2010 Korean National Health and Nutrition Examination Survey

AIMS

The associations of transferrin saturation with diabetes have not been well evaluated and conflicting results have been reported. The purpose of this study is to examine the association of iron indices (serum ferritin and transferrin saturation) with risk of impaired fasting glucose and insulin resistance.

METHODS

We conducted a cross-sectional study in 2413 individuals (1150 men and 1263 women) aged 20-50 years who participated in the 2010 Korean National Health and Nutrition Examination Survey. Participants were free of diabetes, malignancy, liver cirrhosis, chronic renal failure, anaemia, pregnancy and menopause. Fasting plasma glucose, insulin and the homeostasis model assessment of insulin resistance (HOMA-IR) were measured as the outcomes.

RESULTS

Impaired fasting glucose was more prevalent in the highest compared with the lowest serum ferritin quartile among men (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.20-3.24) after adjustment for multiple covariates. Following the same adjustment, impaired fasting glucose was less prevalent in the highest compared with the lowest transferrin saturation quartile among men (OR, 0.45; 95% CI, 0.25-0.80) and women (OR, 0.33; 95% CI, 0.14-0.77). Moreover, a higher ferritin level was significantly associated with higher HOMA-IR after adjusting for confounders in men. Lower transferrin saturation was also significantly associated with higher insulin levels and HOMA-IR in both sexes.

CONCLUSIONS

Lower transferrin saturations were associated with an increased risk of impaired fasting glucose and insulin resistance among general South Korean population.

Anemia in chronic kidney disease patients: treatment recommendations and emerging therapies

Erythropoiesis-stimulating agents (ESA) and iron have been available since decades to treat anemia of chronic kidney disease (CKD). However, many grey areas surround the field. The optimal hemoglobin (Hb) target to aimed at with ESA, the general safety of ESA and boundaries to not be exceeded with iron supplementation are still to be clearly defined. New strategies to stimulate erythropoiesis and new iron molecules have been developed; the most promising approach is the manipulation of the hypoxia-inducible transcription factor (HIF) system. The regulation of activin A pathway is another option with good potential, also considering the additional advantage of increasing bone mass. New iron molecule for intravenous administration may be useful to reduce the number of doses to be administered.

Hepcidin levels in hyperprolactinemic women monitored by nanopore thin film based assay: correlation with pregnancy-associated hormone prolactin

Hepcidin is a central regulator in human iron metabolism. Although it is often regarded as a promising indicator of iron status, the lack of effective quantification method has impeded the comprehensive assessment of its physiological and clinical significance. Herein we applied a newly established, nanopore film enrichment based hepcidin assay to examine the correlation between hepcidin and prolactin, the hormone with an important role during pregnancy and lactation. Women with pathologically elevated prolactin secretion (hyperprolactinemia) were found to have lower serum hepcidin compared to those with normal prolactin levels, without showing significant difference in other hepcidin-regulating factors. Moreover, prolactin-reducing drug bromocriptine mesylate resulted in elevated expression of the hepcidin in hyperprolactinemia patients. These findings suggest a possible role of prolactin in regulation of hepcidin, and may render hepcidin a useful biomarker for progress monitoring and treatment of iron-related diseases under hyperprolactinemic conditions.

FROM THE CLINICAL EDITOR

The level of hepcidin has been shown to reflect the underlying iron status of the patient. Nonentheless, there is an urgent need of reliable, fast and easy-to-do hepcidin assay in the clinical setting. In this paper, the authors described a further modification of their previously described nanopore silica film-based enrichment approach for quantification of hepcidin and found correlation between hepcidin and prolactin. This new knowledge may add to current understanding of iron homeostasis during pregnancy.

Iron deficiency defined as depleted iron stores accompanied by unmet cellular iron requirements identifies patients at the highest risk of death after an episode of acute heart failure

AIM

Acute heart failure (AHF) critically deranges haemodynamic and metabolic homoeostasis. Iron is a key micronutrient for homoeostasis maintenance. We hypothesized that iron deficiency (ID) defined as depleted iron stores accompanied by unmet cellular iron requirements would in this setting predict the poor outcome.

METHODS AND RESULTS

Among 165 AHF patients (age 65 ± 12 years, 81% men, 31% de novo HF), for ID diagnosis we prospectively applied: low serum hepcidin reflecting depleted iron stores (<14.5 ng/mL, the 5th percentile in healthy peers), and high-serum soluble transferrin receptor (sTfR) reflecting unmet cellular iron requirements (≥1.59 mg/L, the 95th percentile in healthy peers). Concomitance of low hepcidin and high sTfR (the most profound ID) was found in 37%, isolated either high sTfR or low hepcidin was found in 29 and 9% of patients, and 25% of subjects demonstrated preserved iron status. Patients with low hepcidin and high sTfR had peripheral oedema, high NT-proBNP, high uric acid, low haemoglobin (P < 0.05), and 5% in-hospital mortality (0% in remaining patients). During the 12-month follow-up, 33 (20%) patients died. Those with low hepcidin and high sTfR had the highest 12-month mortality [(41% (95% CI: 29-53%)] when compared with those with isolated high sTfR [15% (5-25%)], isolated low hepcidin [7% (0-19%)] and preserved iron status (0%) (P < 0.001). Analogous mortality patterns were seen separately in anaemics and non-anaemics.

CONCLUSION

Iron deficiency defined as depleted body iron stores and unmet cellular iron requirements is common in AHF, and identifies those with the poor outcome. Its correction may be an attractive therapeutic approach.

Hepcidin and the iron enigma in HCV infection

An estimated 30-40% of patients with chronic hepatitis C have elevated serum iron, transferrin saturation, and ferritin levels. Clinical data suggest that iron is a co-morbidity factor for disease progression following HCV infection. Iron is essential for a number of fundamental metabolic processes in cells and organisms. Mammalian iron homeostasis is tightly regulated and this is maintained through the coordinated action of sensory and regulatory networks that modulate the expression of iron-related proteins at the transcriptional and/or posttranscriptional levels. Disturbances of iron homeostasis have been implicated in infectious disease pathogenesis. Viruses, similarly to other pathogens, can escape recognition by the immune system, but they need iron from their host to grow and spread. Hepcidin is a 25-aa peptide, present in human serum and urine and represents the key peptide hormone, which modulates iron homeostasis in the body. It is synthesized predominantly by hepatocytes and its mature form is released in circulation. In this review, we discuss recent advances in the exciting crosstalk of molecular mechanisms and cell signaling pathways by which iron and hepcidin production influences HCV-induced liver disease.

Avian iron storage disease: variations on a common theme?

Many frugivorous avian species kept in captivity develop iron storage disease (ISD) as indicated by high concentrations of hepatic iron and hemosiderin deposits in hepatocytes or phagocytes. In several susceptible species fed diets containing moderate levels of iron, ISD develops because of an inability to match rates of iron absorption to tissue needs. Evidence suggests that the pathophysiologic basis of excess iron absorption is due to high levels of expression of divalent metal transporter-1 that transports iron into enterocytes in the proximal intestine, and ferroportin that exports iron to the circulation. The regulatory basis for this inability to sufficiently down-regulate iron absorption is unknown, but disruptions in the hepcidin-ferroportin axis are likely candidates based on recent research in humans and laboratory rodents. It is likely that ISD-susceptible avian species evolved on foods that were very low in bioavailable iron, so there was strong selection pressure for the efficient capture of the small amount of dietary iron but low selection pressure for preventing iron toxicities. Thus, the transporters and regulatory networks for iron absorption seem to be heavily skewed toward iron storage even when food items that are high in iron are consumed. Infections, trauma and neoplasias that trigger an acute phase response may exacerbate ISD in susceptible species and may be the primary cause in species that are normally resistant to ISD (i.e., those that are normally able to shut down intestinal iron absorption when iron stores are replete). The evolutionary basis that resulted in some avian species to be susceptible to ISD (e.g., dietary cause) seems to differ from many inherited ISD disorders in humans that are thought to have evolved to bolster protection against infectious diseases. However the evolutionary basis of ISD in other mammalian species might be more similar to that in ISD-susceptible avian species.

Iron deficiency and heart failure: diagnostic dilemmas and therapeutic perspectives

Iron is a micronutrient essential for cellular energy and metabolism, necessary for maintaining body homoeostasis. Iron deficiency is an important co-morbidity in patients with heart failure (HF). A major factor in the pathogenesis of anaemia, it is also a separate condition with serious clinical consequences (e.g. impaired exercise capacity) and poor prognosis in HF patients. Experimental evidence suggests that iron therapy in iron-deficient animals may activate molecular pathways that can be cardio-protective. Clinical studies have demonstrated favourable effects of i.v. iron on the functional status, quality of life, and exercise capacity in HF patients. It is hypothesized that i.v. iron supplementation may become a novel therapy in HF patients with iron deficiency.

Diagnostic value of transferrin

Despite the growing interest in hepcidin and other relatively new biomarkers, guidelines and clinical pathways continue to recommend traditional markers, such as serum transferrin (Tf) and ferritin, as laboratory tests for the diagnostic evaluation of iron-related disorders. In this study, we aimed to critically evaluate the diagnostic role of Tf relying on the highest level of available evidence by a comprehensive literature search. The role of Tf in iron deficiency (ID) and iron overload (IO) syndrome as well as a risk marker was evaluated. The low accuracy of Tf and Tf saturation (TS) in the diagnosis and management of ID conditions does not permit definitively recommending their use, even if recently published guidelines still consider the TS investigation as a complementary test for ferritin. If a tissue IO is suspected, TS is often used, even if it may not be the best test for detecting this condition. Nevertheless, clinical guidelines strongly recommend the use of TS as a first-level test for performing genetic diagnosis of hereditary hemochromatosis. Recently reported data indicating elevated TS as a risk factor for diabetes mellitus, cancer, and total mortality, may provide useful additions to the debate over whether or not to screen for IO using TS.

Association of TMPRSS6 polymorphisms with ferritin, hemoglobin, and type 2 diabetes risk in a Chinese Han population

BACKGROUND

Transmembrane protease serine 6 (TMPRSS6) regulates iron homeostasis by inhibiting the expression of hepcidin. Multiple common variants in TMPRSS6 were significantly associated with serum iron in recent genome-wide association studies, but their effects in the Chinese remain to be elucidated.

OBJECTIVE

The objective was to determine whether the TMPRSS6 single nucleotide polymorphisms (SNPs) rs855791(V736A) and rs4820268(D521D) were associated with blood hemoglobin and plasma ferritin concentrations and risk of type 2 diabetes in Chinese individuals.

DESIGN

The SNPs rs855791(V736A) and rs4820268(D521D) in the TMPRSS6 gene were genotyped and tested for their associations with plasma iron and type 2 diabetes risk in 1574 unrelated Chinese Hans from Beijing.

RESULTS

The 2 TMPRSS6 SNPs rs855791(V736A) and rs4820268(D521D) were both significantly associated with plasma ferritin (P ≤ 0.0058), hemoglobin (P ≤ 0.0013), iron overload risk (P ≤ 0.0068), and type 2 diabetes risk (P ≤ 0.0314). None of the associations with hemoglobin or plasma ferritin remained significant (P ≥ 0.1229) when the 2 variants were both included in one linear regression model. A haplotype carrying both iron-lowering alleles from the 2 TMPRSS SNPs showed significant associations with lower hemoglobin (P = 0.0014), lower plasma ferritin (P = 0.0027), and a reduced risk of iron overload (P = 0.0017) and of type 2 diabetes (P = 0.0277).

CONCLUSIONS

These findings suggest that TMPRSS6 variants were significantly associated with plasma ferritin, hemoglobin, risk of iron overload, and type 2 diabetes in Chinese Hans. The type 2 diabetes risk conferred by the TMPRSS6 SNPs is possibly mediated by plasma ferritin.

Hepcidin in anemia of chronic kidney disease: review for the pediatric nephrologist

Anemia coincident with hyporesponsiveness to erythropoiesis-stimulating agents is an ongoing and prevalent problem in children with chronic kidney disease (CKD). The recently identified iron-regulatory protein hepcidin appears likely to play a significant role in this problem. Hepcidin up-regulation in the setting of CKD, with subsequent increased serum levels, results in impaired iron absorption from the intestine and decreased iron release from body storage sites. Ultimately, in the setting of such elevated levels, a state of functional iron deficiency may develop and lead to anemia due to iron-restricted erythropoiesis. Elevated hepcidin levels are expected in the face of decreased glomerular filtration rate and inflammation. Based on current evidence, it seems likely that hepcidin represents a potentially modifiable mediator of anemia of CKD and is thus a potential target for future anemia therapy. Currently, increased removal via intensified dialysis and-/or blockade of the inflammatory pathway appear to be two viable generic strategies for reducing hepcidin levels. Goals of directly manipulating the hepcidin pathway should offer the pediatric clinician new options for treating the complex anemia associated with CKD.

Preanalytical factors and reference intervals for serum hepcidin LC-MS/MS method

BACKGROUND

Hepcidin is a potential biomarker for anemia of chronic diseases and disorders of iron metabolism. Thus, data of preanalytical factors, reference values and method characteristics are critical for clinical use of hepcidin determination.

METHODS

We studied the effects of sample storage, sampling device and a meal on hepcidin levels using a liquid-chromatography tandem mass spectrometric (LC-MS/MS) method for serum hepcidin. Age- and gender-dependent reference values were determined using serum samples from healthy volunteers (n=231). The results were also compared with those obtained by a commercial competitive ELISA for hepcidin.

RESULTS

In serum samples, hepcidin is stable for one day at room temperature, six days at +4°C and at least 42 days at -20°C. Breakfast or type of sampling device does not affect hepcidin concentration. Significantly lower hepcidin concentrations were observed in women ≤50 than >50 years of age or in men (p<0.0001 for both). Reference values for females aged 18-50 years were 0.4-9.2 nmol/L, for those >50 years 0.7-16.8 nmol/L and for males ≥18 years 1.1-15.6 nmol/L. Comparison with a competitive ELISA showed poor correlation.

CONCLUSIONS

Fasting before sampling and type of blood collection were not critical. Samples can be transported to laboratory at room temperature if they arrive within a day. Significantly lower concentrations of serum hepcidin were observed in menstruating than in post-menopausal women and in men.

Development of a nano-liquid chromatography on chip tandem mass spectrometry method for high-sensitivity hepcidin quantitation

Microfluidic LC systems present undeniable advantages over classical LC in terms of sensitivity. Hepcidin, a peptide marker of clinical disorders linked to iron metabolism, was used as model to demonstrate peptide quantification potentialities of LC-chip coupled to a nanoelectrospray source ion trap mass spectrometer in an aqueous sample. First, stable isotope labelled hepcidin was chosen as internal standard and gradient as well as sample compositions were optimised using design of experiments as development tool. The method was then prevalidated using accuracy profiles in order to select the most appropriate response function and to confirm the ability of the technique to quantify low hepcidin concentration. A reliable and very sensitive quantitation method was finally obtained using this integrated microfluidic technology. Indeed, good results with respect to accuracy, trueness and precision were achieved, as well as a very low limit of quantitation (0.07 ng/ml). Method suitability of nano-LC on chip tandem mass spectrometry for hepcidin quantitation was also demonstrated in complex media such as human plasma.

Treatment for anemia in people with AIDS

BACKGROUND

Anemia is common in persons with HIV infection and is associated with poor prognosis. There is a need to assess the effects of anemia treatments, and to determine whether these interventions are beneficial.

OBJECTIVES

To determine the efficacy and safety of treatments for anemia in people with HIV infection and AIDS.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 10, 2010), MEDLINE (1980-November 25, 2010), EMBASE (1980-November 25, 2010), LlLACS (1982 to November 25, 2010), Africa Index Medicus (up to November 9, 2010), ISI Web of Knowledge (2005 to October 9, 2010), Scirus (October 9, 2010) reference lists of relevant articles. We asked the Cochrane HIV/AIDS and Pregnancy and Childbirth Groups to check their Specialised Registers. We also checked the reference lists of all trials identified by the above methods.

SELECTION CRITERIA

Randomized trials assessing the effects of treatments for anemia in people diagnosed with HIV infection. There were no age restrictions.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed relevant studies for inclusion. Data extraction and quality assessment of relevant studies was performed by two authors and checked by the other two authors.

MAIN RESULTS

Six trials with a high risk of bias, including 537 patients, met the inclusion criteria. These trials only covered recombinant Human erythropoietin alfa (rHuEPO). Two of them including adult and paediatric participants (84 participants and 4 events) comparing rHuEPO to placebo did not reduce the risk of mortality with a follow up to 12 weeks (pooled RR 0.56, 95% confidence interval (CI) 0.08 to 4.05, I(2) = 0%). Any trials that compared rHuEPO to placebo did not show any benefit on hematological values response, number of patients transfused, or number of packed red cell transfused. Two trial compared the effects of two rHuEPO dosing regimens on hemoglobin value and quality of life, but the effects are unclear. Three RCT reported high risk of attrition bias; therefore, were not included in a meta-analysis.

AUTHORS' CONCLUSIONS

This updated Cochrane review provides evidence that rHuEPO compared with placebo does not reduce mortality, does not reduce transfusion requirements, did not increase hemoglobin levels, and did not improve quality of life in HIV-infected patients with anemia. The results are based on six RCTs with high risk of bias. Therefore prescription of this intervention for treating anemia in patients with AIDS is not justified, unless new evidence from a large high quality trial alters this conclusion.

Effects of a single dose of oral iron on hepcidin concentrations in human urine and serum analyzed by a robust LC-MS/MS method

BACKGROUND

The measurement of serum hepcidin, a peptide hormone that regulates iron metabolism, is clinically important to the understanding of iron homeostasis in health and disease. To date, the quantification of serum hepcidin levels by conventional immunological detection methods has proven problematic due to challenges in obtaining high quality antibodies which demonstrate good reproducibility. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) has been employed recently for more sensitive quantification of hepcidin; however, this method has high background levels and therefore less than optimal specificity.

METHODS

In order to increase the specificity of the mass spectrometry based assay, we developed a robust, ultra-performance liquid-chromatography-tandem mass spectrometry (UPLC-MS/MS) protocol using multiple selected reaction monitoring (mSRM) for quantification of hepcidin levels in urine and serum of human subjects. With this assay, we assessed levels of hepcidin before and for up to 8 h after oral ingestion of ferrous sulfate in ten adult human subjects without known disease.

RESULTS

The linear response of hepcidin quantitation on each instrument was measured, and the correlation coefficients of these calibrations were r(2)=0.9512±0.0202 (n=5) for urine and r(2)=0.9709±0.0291 (n=5) for serum [r(2)=mean±SD]. Compared to baseline, the levels of urinary hepcidin between 2-4 h and 4-8 h of both women and men showed significant increases with p<0.05 and p<0.001, respectively. The levels of serum hepcidin between 4 h and 8 h in both women and men showed significant increases, compared with baseline values, with both p<0.01. Interestingly, we also observed some degree of oscillation of levels, occurring at later time points.

CONCLUSIONS

We have developed and validated a new method for measuring hepcidin concentrations in human serum and urine and used it to demonstrate early increases with iron supplement in both urinary and serum levels of hepcidin, which return to baseline levels, except in urine samples from men.

[Increased hepcidin levels three days after gynecological interventions]

Hepcidin is an endogenous substance that inhibits iron absorption and plasma iron levels. Due to technical reasons its levels are not routinely assessed and data regarding its clinical relevance are limited. We analyzed the alteration of hepcidin levels following gynecological interventions. Hepcidin levels were determined by mass spectrometry, along with the levels of interleukin-6, the main inductor of hepcidin with ELISA in 17 women undergoing gynecological intervention just prior to and three days after the surgery. The results were related to iron homeostasis parameters. A decrease in serum iron (median, interquartile range) (17.85 [15.25-24.9] versus 10.1 [7.6-15.0] μmol/l, p<0.01) and transferrin levels (60.3 [55.93-67.18] versus 53.1 [49.7-60.0], p< 0.01) μmol/l, simultaneously with an increase in hepcidin (2.75 [2.24-3.51] versus 8.01 [6.8-9.67] μg/l, p<0.01) and interleukin-6 levels (ND = not detected) (ND [ND - 2.2] versus 8.15 [2.31-12.86], p<0.01).

CONCLUSION

As with other acute phase proteins postoperative hepcidin levels dramatically increase, simultaneously with other changes in iron homeostasis. These results indicate a possible causative relationship between increased hepcidin and decreased iron levels. In clinical practice, determination of hepcidin levels may be indicated for characterization and, possibly, prediction of postoperative iron homeostasis. However, measurement of hepcidin level in clinical practice is unlikely in the near future due to the lack of available kits for routine clinical laboratories.

Ferroportin and hepcidin: a new hope in diagnosis, prognosis, and therapy for breast cancer

Breast cancer is the most prevalent malignancy in women. The success of breast cancer treatment relies on the ability to detect the disease and correct molecular abnormalities at an early stage of disease development. A recent article describes a marked decrease in the levels of ferroportin in breast cancer. More importantly, the presented results demonstrate convincingly the incredible diagnostic and prognostic value of ferroportin and hepcidin gene expression in breast cancer and suggest that determination of these two molecular markers may be used as guidance toward individualized therapy for breast cancer patients.