Iron homeostasis governs erythroid phenotype in polycythemia vera.

Polycythemia vera (PV) is a myeloproliferative neoplasm driven by activating mutations in JAK2 that result in unrestrained erythrocyte production, increasing patients' hematocrit and hemoglobin concentrations, placing them at risk of life-threatening thrombotic events. Our genome-wide association study of 440 PV cases and 403 351 controls using UK Biobank data showed that single nucleotide polymorphisms in HFE known to cause hemochromatosis are highly associated with PV diagnosis, linking iron regulation to PV. Analysis of the FinnGen dataset independently confirmed overrepresentation of homozygous HFE variants in patients with PV. HFE influences the expression of hepcidin, the master regulator of systemic iron homeostasis. Through genetic dissection of mouse models of PV, we show that the PV erythroid phenotype is directly linked to hepcidin expression: endogenous hepcidin upregulation alleviates erythroid disease whereas hepcidin ablation worsens it. Furthermore, we demonstrate that in PV, hepcidin is not regulated by expanded erythropoiesis but is likely governed by inflammatory cytokines signaling via GP130-coupled receptors. These findings have important implications for understanding the pathophysiology of PV and offer new therapeutic strategies for this disease.

Ferric carboxymaltose versus standard-of-care oral iron to treat second-trimester anaemia in Malawian pregnant women: a randomised controlled trial.

BACKGROUND: Anaemia affects 46% of pregnancies in Africa; oral iron is recommended by WHO but uptake and adherence are suboptimal. We tested a single dose of a modern intravenous iron formulation, ferric carboxymaltose, for anaemia treatment in Malawian pregnant women. METHODS: In this open-label, individually randomised controlled trial, we enrolled women with a singleton pregnancy of 13-26 weeks' gestation in primary care and outpatient settings across two regions in southern Malawi. Women were eligible if they had capillary haemoglobin of less than 10·0 g/dL and negative malaria rapid diagnostic test. Participants were randomised by sealed envelope 1:1. Assessors for efficacy outcomes (laboratory parameters and birthweight) were masked to intervention; participants and study nurses were not masked. Participants were given ferric carboxymaltose up to 1000 mg (given once at enrolment in an outpatient primary care setting), or standard of care (60 mg elemental iron twice daily for 90 days), along with intermittent preventive malaria treatment. The primary maternal outcome was anaemia at 36 weeks' gestation. The primary neonatal outcome was birthweight. Analyses were performed in the intention-to-treat population for mothers and liveborn neonates, according to their randomisation group. Safety outcomes included incidence of adverse events during infusion and all adverse events from randomisation to 4 weeks' post partum. The trial is registered with ANZCTR, ACTRN12618001268235. The trial has completed follow-up. FINDINGS: Between Nov 12, 2018, and March 2, 2021, 21 258 women were screened, and 862 randomly assigned to ferric carboxymaltose (n=430) or standard of care (n=432). Ferric carboxymaltose did not reduce anaemia prevalence at 36 weeks' gestation compared with standard of care (179 [52%] of 341 in the ferric carboxymaltose group vs 189 [57%] of 333 in the standard of care group; prevalence ratio [PR] 0·92, 95% CI 0·81 to 1·06; p=0·27). Anaemia prevalence was numerically lower in mothers randomly assigned to ferric carboxymaltose compared with standard of care at all timepoints, although significance was only observed at 4 weeks' post-treatment (PR 0·91 [0·85 to 0·97]). Birthweight did not differ between groups (mean difference -3·1 g [-75·0 to 68·9, p=0·93). There were no infusion-related serious adverse events or differences in adverse events by any organ class (including malaria; ≥1 adverse event: ferric carboxymaltose 183 [43%] of 430 vs standard of care 170 [39%] of 432; risk ratio 1·08 [0·92 to 1·27]; p=0·34). INTERPRETATION: In this malaria-endemic sub-Saharan African setting, treatment of anaemic pregnant women with ferric carboxymaltose was safe but did not reduce anaemia prevalence at 36 weeks' gestation or increase birthweight. FUNDING: Bill & Melinda Gates Foundation (INV-010612).

Benefits and Risks of Iron Interventions in Infants in Rural Bangladesh.

BACKGROUND: Universal provision of iron supplements (drops or syrup) or multiple micronutrient powders to young children in low-to-middle-income countries where anemia is prevalent is recommended by the World Health Organization and widely implemented. The functional benefits and safety of these interventions are unclear. METHODS: We conducted a three-group, double-blind, double-dummy, individually randomized, placebo-controlled trial to assess the immediate and medium-term benefits and risks of 3 months of daily supplementation with iron syrup or iron-containing multiple micronutrient powders, as compared with placebo, in 8-month-old children in rural Bangladesh. The primary outcome was cognitive development, as assessed by the cognitive composite score on the Bayley Scales of Infant and Toddler Development, third edition, immediately after completion of the assigned 3-month regimen; scores range from 55 to 145, with higher scores indicating better cognitive performance. Secondary outcomes included the cognitive composite score at 9 months after completion of the assigned regimen; behavioral, language, and motor development, as well as growth and hematologic markers, immediately after completion and at 9 months after completion; and safety. RESULTS: We randomly assigned 3300 infants to receive iron syrup (1101 infants), multiple micronutrient powders (1099), or placebo (1100) daily. After completion of the assigned 3-month regimen, no apparent effect on the cognitive composite score was observed with iron syrup as compared with placebo (mean between-group difference in change in score from baseline, -0.30 points; 95% confidence interval [CI], -1.08 to 0.48) or with multiple micronutrient powders as compared with placebo (mean between-group difference in change in score from baseline, 0.23 points; 95% CI, -0.55 to 1.00). No apparent effect on any other developmental or growth outcome was observed immediately after completion of the assigned regimen or at 9 months after completion. At 9 months after completion of the assigned regimen, the prevalences of anemia, iron deficiency, and iron deficiency anemia increased in all three trial groups but remained lower among the children who received iron syrup or multiple micronutrient powders than among those who received placebo. The risk of serious adverse events and incidence of symptoms of infection were similar in the three trial groups. CONCLUSIONS: In this trial involving infants in Bangladesh, 3 months of daily supplementation with iron syrup or multiple micronutrient powders did not appear to have an effect on child development or other functional outcomes as compared with placebo. (Funded by the National Health and Medical Research Council of Australia; BRISC Australian New Zealand Clinical Trials Registry number, ACTRN12617000660381.).

Serum iron and transferrin saturation variation are circadian regulated and linked to the harmonic circadian oscillations of erythropoiesis and hepatic Tfrc expression in mice.

Serum iron has long been thought to exhibit diurnal variation and is subsequently considered an unreliable biomarker of systemic iron status. Circadian regulation (endogenous ~24-h periodic oscillation of a biologic function) governs many critical physiologic processes. It is unknown whether serum iron levels are regulated by circadian machinery; likewise, the circadian nature of key players of iron homeostasis is unstudied. Here we show that serum iron, transferrin saturation (TSAT), hepatic transferrin receptor (TFR1) gene (Tfrc) expression, and erythropoietic activity exhibit circadian rhythms. Daily oscillations of serum iron, TSAT, hepatic Tfrc expression, and erythropoietic activity are maintained in mice housed in constant darkness, where oscillation reflects an endogenous circadian period. Oscillations of serum iron, TSAT, hepatic Tfrc, and erythropoietic activity were ablated when circadian machinery was disrupted in Bmal1 knockout mice. Interestingly, we find that circadian oscillations of erythropoietic activity and hepatic Tfrc expression are maintained in opposing phase, likely allowing for optimized usage and storage of serum iron whilst maintaining adequate serum levels and TSAT. This study provides the first confirmatory evidence that serum iron is circadian regulated, discerns circadian rhythms of TSAT, a widely used clinical marker of iron status, and uncovers liver-specific circadian regulation of TFR1, a major player in cellular iron uptake.

Iron restriction in sickle cell disease: When less is more.

Primum non nocere! Can iron deficiency, an abnormality that causes anemia, benefit people with sickle cell disease (SCD) who already have an anemia? The published literature we review appears to answer this question in the affirmative: basic science considerations, animal model experiments, and noncontrolled clinical observations all suggest a therapeutic potential of iron restriction in SCD. This is because SCD's clinical manifestations are ultimately attributable to the polymerization of hemoglobin S (HbS), a process strongly influenced by intracellular HbS concentration. Even small decrements in HbS concentration greatly reduce polymerization, and iron deficiency lowers erythrocyte hemoglobin concentration. Thus, iron deficiency could improve SCD by changing its clinical features to those of a more benign anemia (i.e., a condition with fewer or no vaso-occlusive events). We propose that well-designed clinical studies be implemented to definitively determine whether iron restriction is a safe and effective option in SCD. These investigations are particularly timely now that pharmacologic agents are being developed, which may directly reduce red cell hemoglobin concentrations without the need for phlebotomies to deplete total body iron.

Effect of Low-Dose Aspirin Versus Placebo on Incidence of Anemia in the Elderly : A Secondary Analysis of the Aspirin in Reducing Events in the Elderly Trial.

BACKGROUND: Daily low-dose aspirin increases major bleeding; however, few studies have investigated its effect on iron deficiency and anemia. OBJECTIVE: To investigate the effect of low-dose aspirin on incident anemia, hemoglobin, and serum ferritin concentrations. DESIGN: Post hoc analysis of the ASPREE (ASPirin in Reducing Events in the Elderly) randomized controlled trial. (ClinicalTrials.gov: NCT01038583). SETTING: Primary/community care in Australia and the United States. PARTICIPANTS: Community-dwelling persons aged 70 years or older (≥65 years for Black persons and Hispanic persons). INTERVENTION: 100 mg of aspirin daily or placebo. MEASUREMENTS: Hemoglobin concentration was measured annually in all participants. Ferritin was measured at baseline and 3 years after random assignment in a large subset. RESULTS: 19 114 persons were randomly assigned. Anemia incidence in the aspirin and placebo groups was 51.2 events and 42.9 events per 1000 person-years, respectively (hazard ratio, 1.20 [95% CI, 1.12 to 1.29]). Hemoglobin concentrations declined by 3.6 g/L per 5 years in the placebo group and the aspirin group experienced a steeper decline by 0.6 g/L per 5 years (CI, 0.3 to 1.0 g/L). In 7139 participants with ferritin measures at baseline and year 3, the aspirin group had greater prevalence than placebo of ferritin levels less than 45 µg/L at year 3 (465 [13%] vs. 350 [9.8%]) and greater overall decline in ferritin by 11.5% (CI, 9.3% to 13.7%) compared with placebo. A sensitivity analysis quantifying the effect of aspirin in the absence of major bleeding produced similar results. LIMITATIONS: Hemoglobin was measured annually. No data were available on causes of anemia. CONCLUSION: Low-dose aspirin increased incident anemia and decline in ferritin in otherwise healthy older adults, independent of major bleeding. Periodic monitoring of hemoglobin should be considered in older persons on aspirin. PRIMARY FUNDING SOURCE: National Institutes of Health and Australian National Health and Medical Research Council.

Biology of Anemia: A Public Health Perspective.

Our goal is to present recent progress in understanding the biological mechanisms underlying anemia from a public health perspective. We describe important advances in understanding common causes of anemia and their interactions, including iron deficiency (ID), lack of other micronutrients, infection, inflammation, and genetic conditions. ID develops if the iron circulating in the blood cannot provide the amounts required for red blood cell production and tissue needs. ID anemia develops as iron-limited red blood cell production fails to maintain the hemoglobin concentration above the threshold used to define anemia. Globally, absolute ID (absent or reduced body iron stores that do not meet the need for iron of an individual but may respond to iron supplementation) contributes to only a limited proportion of anemia. Functional ID (adequate or increased iron stores that cannot meet the need for iron because of the effects of infection or inflammation and does not respond to iron supplementation) is frequently responsible for anemia in low- and middle-income countries. Absolute and functional ID may coexist. We highlight continued improvement in understanding the roles of infections and inflammation in causing a large proportion of anemia. Deficiencies of nutrients other than iron are less common but important in some settings. The importance of genetic conditions as causes of anemia depends upon the specific inherited red blood cell abnormalities and their prevalence in the settings examined. From a public health perspective, each setting has a distinctive composition of components underlying the common causes of anemia. We emphasize the coincidence between regions with a high prevalence of anemia attributed to ID (both absolute and functional), those with endemic infections, and those with widespread genetic conditions affecting red blood cells, especially in sub-Saharan Africa and regions in Asia and Oceania.

Supplementation With Iron Syrup or Iron-Containing Multiple Micronutrient Powders Alters Resting Brain Activity in Bangladeshi Children.

BACKGROUND: Anemia and iron deficiency have been associated with poor child cognitive development. A key rationale for the prevention of anemia using supplementation with iron has been the benefits to neurodevelopment. However, little causal evidence exists for these gains. OBJECTIVES: We aimed to examine effects of supplementation with iron or multiple micronutrient powders (MNPs) on brain activity measures using resting electroencephalography (EEG). METHODS: Children included in this neurocognitive substudy were randomly selected from the Benefits and Risks of Iron Supplementation in Children study, a double-blind, double-dummy, individually randomized, parallel-group trial in Bangladesh, in which children, starting at 8 mo of age, received 3 mo of daily iron syrup, MNPs, or placebo. Resting brain activity was recorded using EEG immediately after intervention (month 3) and after a further 9-month follow-up (month 12). We derived EEG band power measures for delta, theta, alpha, and beta frequency bands. Linear regression models were used to compare the effect of each intervention with that of placebo on the outcomes. RESULTS: Data from 412 children at month 3 and 374 at month 12 were analyzed. At baseline, 43.9% were anemic and 26.7% were iron deficient. Immediately after intervention, iron syrup, but not MNPs, increased the mu alpha-band power, a measure that is associated with maturity and the production of motor actions (iron vs. placebo: mean difference = 0.30; 95% CI: 0.11, 0.50 µV2; P = 0.003; false discovery rate adjusted P = 0.015). Despite effects on hemoglobin and iron status, effects were not observed on the posterior alpha, beta, delta, and theta bands, nor were effects sustained at the 9-month follow-up. CONCLUSIONS: The effect size for immediate effects on the mu alpha-band power is comparable in magnitude with psychosocial stimulation interventions and poverty reduction strategies. However, overall, we did not find evidence for long-lasting changes in resting EEG power spectra from iron interventions in young Bangladeshi children. This trial was registered at www.anzctr.org.au as ACTRN12617000660381.

Iron deficiency.

Iron deficiency is one of the leading contributors to the global burden of disease, and particularly affects children, premenopausal women, and people in low-income and middle-income countries. Anaemia is one of many consequences of iron deficiency, and clinical and functional impairments can occur in the absence of anaemia. Iron deprivation from erythroblasts and other tissues occurs when total body stores of iron are low or when inflammation causes withholding of iron from the plasma, particularly through the action of hepcidin, the main regulator of systemic iron homoeostasis. Oral iron therapy is the first line of treatment in most cases. Hepcidin upregulation by oral iron supplementation limits the absorption efficiency of high-dose oral iron supplementation, and of oral iron during inflammation. Modern parenteral iron formulations have substantially altered iron treatment and enable rapid, safe total-dose iron replacement. An underlying cause should be sought in all patients presenting with iron deficiency: screening for coeliac disease should be considered routinely, and endoscopic investigation to exclude bleeding gastrointestinal lesions is warranted in men and postmenopausal women presenting with iron deficiency anaemia. Iron supplementation programmes in low-income countries comprise part of the solution to meeting WHO Global Nutrition Targets.

Antibodies against the erythroferrone N-terminal domain prevent hepcidin suppression and ameliorate murine thalassemia.

Erythroferrone (ERFE) is produced by erythroblasts in response to erythropoietin (EPO) and acts in the liver to prevent hepcidin stimulation by BMP6. Hepcidin suppression allows for the mobilization of iron to the bone marrow for the production of red blood cells. Aberrantly high circulating ERFE in conditions of stress erythropoiesis, such as in patients with ß-thalassemia, promotes the tissue iron accumulation that substantially contributes to morbidity in these patients. Here we developed antibodies against ERFE to prevent hepcidin suppression and to correct the iron loading phenotype in a mouse model of ß-thalassemia [Hbb(th3/+) mice] and used these antibodies as tools to further characterize ERFE's mechanism of action. We show that ERFE binds to BMP6 with nanomolar affinity and binds BMP2 and BMP4 with somewhat weaker affinities. We found that BMP6 binds the N-terminal domain of ERFE, and a polypeptide derived from the N terminus of ERFE was sufficient to cause hepcidin suppression in Huh7 hepatoma cells and in wild-type mice. Anti-ERFE antibodies targeting the N-terminal domain prevented hepcidin suppression in ERFE-treated Huh7 cells and in EPO-treated mice. Finally, we observed a decrease in splenomegaly and serum and liver iron in anti-ERFE-treated Hbb(th3/+) mice, accompanied by an increase in red blood cells and hemoglobin and a decrease in reticulocyte counts. In summary, we show that ERFE binds BMP6 directly and with high affinity, and that antibodies targeting the N-terminal domain of ERFE that prevent ERFE-BMP6 interactions constitute a potential therapeutic tool for iron loading anemias.