Anemia of inflammation

Performance and comparability of laboratory methods for measuring ferritin concentrations in human serum or plasma: A systematic review and meta-analysis

BACKGROUND

Different laboratory methods are used to quantify ferritin concentrations as a marker of iron status. A systematic review was undertaken to assess the accuracy and comparability of the most used methods for ferritin detection.

METHODS AND FINDINGS

National and regional databases were searched for prospective, retrospective, sectional, longitudinal and case-control studies containing the characteristics and performance of at least one method for serum/plasma ferritin determinations in humans published to date. The analysis included the comparison between at least 2 methods detailing: sensitivity, precision, accuracy, predictive values, inter-methods adjustment, and use of international reference materials. Pooled method performance was analyzed for each method and across methods.

OUTCOMES

Search strategy identified 11893 records. After de-duplication and screening 252 studies were assessed, including 187 studies in the qualitative analysis and 148 in the meta-analysis. The most used methods included radiometric, nonradiometric and agglutination assays. The overall within-run imprecision for the most reported ferritin methods was 6.2±3.4% (CI 5.69-6.70%; n = 171), between-run imprecision 8.9±8.7% (CI 7.44-10.35%; n = 136), and recovery rate 95.6% (CI 91.5-99.7%; n = 94). The pooled regression coefficient was 0.985 among all methods analyzed, and 0.984 when comparing nonradiometric and radiometric methods, without statistical differences in ferritin concentration ranging from 2.3 to 1454 μμg/L.

CONCLUSION

The laboratory methods most used to determine ferritin concentrations have comparable accuracy and performance. Registered in PROSPERO CRD42016036222.

The effect of vitamin B12 and folic acid supplementation on routine haematological parameters in older people: an individual participant data meta-analysis

BACKGROUND/OBJECTIVES

Low vitamin B12 and folate levels in community-dwelling older people are usually corrected with supplements. However, the effect of this supplementation on haematological parameters in older persons is not known. Therefore, we executed a systematic review and individual participant data meta-analysis of randomised placebo-controlled trials (RCTs).

SUBJECTS/METHODS

We performed a systematic search in PubMed, EMBASE, Web of Science, Cochrane and CENTRAL for RCTs published between January 1950 and April 2016, where community-dwelling elderly (60+ years) who were treated with vitamin B12 or folic acid or placebo. The presence of anaemia was not required. We analysed the data on haematological parameters with a two-stage IPD meta-analysis.

RESULTS

We found 494 full papers covering 14 studies. Data were shared by the authors of four RCTs comparing vitamin B12 with placebo (n = 343) and of three RCTs comparing folic acid with placebo (n = 929). We found no effect of vitamin B12 supplementation on haemoglobin (change 0.00 g/dL, 95% CI: -0.19;0.18), and no effect of folic acid supplementation (change -0.09 g/dL, 95% CI: -0.19;0.01). The effects of supplementation on other haematological parameters were similar. The effects did not differ by sex or by age group. Also, no effect was found in a subgroup of patients with anaemia and a subgroup of patients who were treated >4 weeks.

CONCLUSIONS

Evidence on the effects of supplementation of low concentrations of vitamin B12 and folate on haematological parameters in community-dwelling older people is inconclusive. Further research is needed before firm recommendations can be made concerning the supplementation of vitamin B12 and folate.

HAMP promoter hypomethylation and increased hepcidin levels as biomarkers for Kawasaki disease

Kawasaki disease (KD) is the most common coronary vasculitis to appear in children with anemia and has been associated with elevated plasma hepcidin levels. We recruited a total of 241 cases, including 18 KD patients, who were tested both prior to receiving intravenous immunoglobulin (IVIG) and at least 3 weeks after IVIG treatment, and 18 febrile controls, who were observed in the Illumina HumanMethylation450 BeadChip study for their CpG markers. The remaining cases consisted of another 92 KD patients and 113 controls that were used for validation by pyrosequencing. We performed a genetic functional study using Luciferase assays. A support vector machine (SVM) classification model was adopted to identify KD patients and control subjects. In this study, KD patients clearly demonstrated a significantly epigenetic hypomethylation of HAMP promoter compared to controls. After receiving IVIG treatment, the hypomethylation status in KD patients was restored, and we observed a significant opposite tendency between the DNA methylation of target CpG sites (cg23677000 and cg04085447) and the hepcidin level. Furthermore, reporter gene assays were used to detect target CpG sites, the methylation of which displayed decreased levels of HAMP gene expression. Of particular note, we developed a SVM classification model with a 90.9% sensitivity, a 91.9% specificity, and 0.94 auROC in the training set. An independent blind cohort also had good performance (96.1% sensitivity and 89.7% specificity). In this study, we demonstrate HAMP promoter hypomethylation, which upregulates hepcidin expression in KD patients. Furthermore, the reliability and robustness of our SVM classification model can accurately serve as KD biomarkers.

Population snapshots predict early haematopoietic and erythroid hierarchies

The formation of red blood cells begins with the differentiation of multipotent haematopoietic progenitors. Reconstructing the steps of this differentiation represents a general challenge in stem-cell biology. Here we used single-cell transcriptomics, fate assays and a theory that allows the prediction of cell fates from population snapshots to demonstrate that mouse haematopoietic progenitors differentiate through a continuous, hierarchical structure into seven blood lineages. We uncovered coupling between the erythroid and the basophil or mast cell fates, a global haematopoietic response to erythroid stress and novel growth factor receptors that regulate erythropoiesis. We defined a flow cytometry sorting strategy to purify early stages of erythroid differentiation, completely isolating classically defined burst-forming and colony-forming progenitors. We also found that the cell cycle is progressively remodelled during erythroid development and during a sharp transcriptional switch that ends the colony-forming progenitor stage and activates terminal differentiation. Our work showcases the utility of linking transcriptomic data to predictive fate models, and provides insights into lineage development in vivo.

Deficiency of the BMP Type I receptor ALK3 partly protects mice from anemia of inflammation

Background

Inflammatory stimuli induce the hepatic iron regulatory hormone hepcidin, which contributes to anaemia of inflammation (AI). Hepcidin expression is regulated by the bone morphogenetic protein (BMP) and the interleukin-6 (IL-6) signalling pathways. Prior results indicate that the BMP type I receptor ALK3 is mainly involved in the acute inflammatory hepcidin induction four and 72 h after IL-6 administration. In this study, the role of ALK3 in a chronic model of inflammation was investigated. The intact, heat-killed bacterium Brucella abortus (BA) was used to analyse its effect on the development of inflammation and hypoferremia in mice with hepatocyte-specific Alk3-deficiency (Alk3^fl/fl; Alb-Cre) compared to control (Alk3^fl/fl) mice.

Results

An iron restricted diet prevented development of the iron overload phenotype in mice with hepatocyte-specific Alk3 deficiency. Regular diet leads to iron overload and increased haemoglobin levels in these mice, which protects from the development of AI per se. Fourteen days after BA injection Alk3^fl/fl; Alb-Cre mice presented milder anaemia (Hb 16.7 g/dl to 11.6 g/dl) compared to Alk3^fl/fl control mice (Hb 14.9 g/dl to 8.6 g/dl). BA injection led to an intact inflammatory response in all groups of mice. In Alk3^fl/fl; Alb-Cre mice, SMAD1/5/8 phosphorylation was reduced after BA as well as after infection with Staphylococcus aureus. The reduction of the SMAD1/5/8 signalling pathway due to hepatocyte-specific Alk3 deficiency partly suppressed the induction of STAT3 signalling.

Conclusion

The results reveal in vivo, that 1) hepatocyte-specific Alk3 deficiency partly protects from AI, 2) the development of hypoferremia is partly dependent on ALK3, and 3) the ALK3/BMP/hepcidin axis may serve as a possible therapeutic target to attenuate AI.

Electronic supplementary material

The online version of this article (10.1186/s12899-018-0037-z) contains supplementary material, which is available to authorized users.

Extracellular HMGB1 as a therapeutic target in inflammatory diseases

INTRODUCTION

High-mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that promotes inflammation when released extracellularly after cellular activation, stress, damage or death. HMGB1 operates as one of the most intriguing molecules in inflammatory disorders via recently elucidated signal and molecular transport mechanisms. Treatments based on antagonists specifically targeting extracellular HMGB1 have generated encouraging results in a wide number of experimental models of infectious and sterile inflammation. Clinical studies are still to come. Areas covered: We here summarize recent advances regarding pathways for extracellular HMGB1 release, receptor usage, and functional consequences of post-translational modifications. The review also addresses results of preclinical HMGB1-targeted therapy studies in multiple inflammatory conditions and outlines the current status of emerging clinical HMGB1-specific antagonists. Expert opinion: Blocking excessive amounts of extracellular HMGB1, particularly the disulfide isoform, offers an attractive clinical opportunity to ameliorate systemic inflammatory diseases. Therapeutic interventions to regulate intracellular HMGB1 biology must still await a deeper understanding of intracellular HMGB1 functions. Future work is needed to create more robust assays to evaluate functional bioactivity of HMGB1 antagonists. Forthcoming clinical studies would also greatly benefit from a development of antibody-based assays to quantify HMGB1 redox isoforms, presently assessed by mass spectrometry methods.

African Trypanosomiasis-Associated Anemia: The Contribution of the Interplay between Parasites and the Mononuclear Phagocyte System

African trypanosomosis (AT) is a chronically debilitating parasitic disease of medical and economic importance for the development of sub-Saharan Africa. The trypanosomes that cause this disease are extracellular protozoan parasites that have developed efficient immune escape mechanisms to manipulate the entire host immune response to allow parasite survival and transmission. During the early stage of infection, a profound pro-inflammatory type 1 activation of the mononuclear phagocyte system (MPS), involving classically activated macrophages (i.e., M1), is required for initial parasite control. Yet, the persistence of this M1-type MPS activation in trypanosusceptible animals causes immunopathology with anemia as the most prominent pathological feature. By contrast, in trypanotolerant animals, there is an induction of IL-10 that promotes the induction of alternatively activated macrophages (M2) and collectively dampens tissue damage. A comparative gene expression analysis between M1 and M2 cells identified galectin-3 (Gal-3) and macrophage migration inhibitory factor (MIF) as novel M1-promoting factors, possibly acting synergistically and in concert with TNF-α during anemia development. While Gal-3 enhances erythrophagocytosis, MIF promotes both myeloid cell recruitment and iron retention within the MPS, thereby depriving iron for erythropoiesis. Hence, the enhanced erythrophagocytosis and suppressed erythropoiesis lead to anemia. Moreover, a thorough investigation using MIF-deficient mice revealed that the underlying mechanisms in AT-associated anemia development in trypanosusceptible and tolerant animals are quite distinct. In trypanosusceptible animals, anemia resembles anemia of inflammation, while in trypanotolerant animals’ hemodilution, mainly caused by hepatosplenomegaly, is an additional factor contributing to anemia. In this review, we give an overview of how trypanosome- and host-derived factors can contribute to trypanosomosis-associated anemia development with a focus on the MPS system. Finally, we will discuss potential intervention strategies to alleviate AT-associated anemia that might also have therapeutic potential.

Anemia at older age: etiologies, clinical implications, and management

Anemia is quite frequently diagnosed in older individuals and is a key indicator of various reactive and clonal conditions. Many underlying diseases, like myelodysplastic syndrome (MDS), develop preferentially in elderly individuals. The prevalence of anemia at older age is increasing, and this is mainly attributable to more frequently applied diagnostics and demographic changes in our societies. The etiology of anemia at older age is complex and ranges from bone marrow failure syndromes to chronic kidney disease, and from nutritional deficiencies to inflammatory processes including inflammaging in immunosenescence. In a smaller number of cases, no clear-cut etiology is identified. These patients are referred to as unexplained anemia or idiopathic cytopenia of unknown significance. In others, somatic mutations in leukocytes are found, but diagnostic criteria for MDS or other hematologic diseases are not fulfilled, a condition termed clonal cytopenia of undetermined significance. Management of anemias at older age depends on (1) the severity of the anemia, (2) underlying condition(s), and (3) patient-related factors, including comorbidities. Even a mild anemia may substantially affect physical and cognitive capacities and quality of life. An underestimated aspect is that because of age-related changes, organ function such as erythropoietin production in the kidney may become suboptimal. Management and treatment of anemia in older patients often require a multidisciplinary approach and detailed investigations of organ function. In this article, we review current concepts around anemias at older age, with special emphasis on etiologies, clinical implications, and innovative concepts in the management of these patients.

Inflammation regulates fibroblast growth factor 23 production

PURPOSE OF REVIEW

Fibroblast growth factor 23 (FGF23) is a hormone secreted by osteocytes and osteoblasts that regulates phosphorus and vitamin D homeostasis. FGF23 levels increase progressively in chronic kidney disease (CKD), and FGF23 excess might be a causal factor of left ventricular hypertrophy, CKD progression and death. Therefore, understanding the molecular mechanisms that control FGF23 production is critical to design therapies to lower FGF23 levels. The present review focuses on the role of inflammatory stimuli on FGF23 regulation and summarizes recent studies that support a novel framework linking inflammation to FGF23 regulation.

RECENT FINDINGS

Inflammation and iron deficiency, which are common occurrences in CKD, have emerged as novel FGF23 regulators. Recent findings show that inflammation increases FGF23 production in bone through direct and iron-related indirect mechanisms. In these settings, hypoxia-inducible factor (HIF)-1α orchestrates FGF23 transcription in response to inflammation and is primarily responsible for coordinating FGF23 production and cleavage.

SUMMARY

We demonstrate that inflammation increases FGF23 production and may contribute to elevated FGF23 levels in CKD. Osseous HIF-1α may represent a therapeutic target to lower FGF23 levels in CKD patients and minimize the negative consequences associated with FGF23 excess.

The Relationship between Anaemia and Frailty: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

There is increasing evidence that frailty may play a role in chronic diseases, but the associations with specific chronic disorders are still unclear.

OBJECTIVES

To conduct a systematic review and meta-analysis assessing the association of anaemia and frailty in observational studies.

METHODS

The review was performed according to PRISMA guidelines. We searched PubMed, Web of Science, and Embase from 01/01/2002-10/09/2017. Pooled estimates were obtained through random effect models and Mantel-Haenszel weighting. Homogeneity was assessed with the I2 statistic. Publication bias was assessed with Egger's and Begg's tests.

RESULTS

Nineteen studies were included; two longitudinal, seventeen cross-sectional. All studies except three reported an association between anaemia and frailty. The pooled prevalence of prefrailty in individuals with anaemia was 49% (95% CI=38-59%; I2=89.96%) and 24% (95% CI=17-31%; I2= 94.78%) for frailty. Persons with anaemia had more than a twofold odds of frailty (pooled OR=2.24 95% CI=1.53-3.30; I2=91.8%). Only two studies longitudinally examined the association between anaemia and frailty, producing conflicting results.

CONCLUSIONS

Frailty and prefrailty are common in anaemic persons. Older persons with anaemia have more than a two-fold increased odds of frailty. These results may have clinical implications, as they identify the need to assess frailty in anaemic people and investigate any potential negative effects associated with the co-occurrence of both conditions. Longitudinal research that examines temporal changes in anaemia and effect of treatment are needed to further clarify the relationship between anaemia and frailty.

Laboratory Markers in Incomplete Kawasaki Disease according to Coronary Artery Outcome

Background and Objectives

We defined laboratory marker profiles typical of incomplete Kawasaki disease (iKD) during illness, especially with respect to the presence of a coronary artery abnormality such as coronary artery dilation or aneurysm.

Methods

This retrospective study examined the clinical and laboratory markers of patients with iKD over time, along with those of patients with complete KD (cKD) and febrile controls.

Results

Of 795 patients, 178 had iKD, 504 had cKD and 113 were febrile controls. During the transition from the acute to subacute phase, the age-adjusted hemoglobin levels and platelet counts were significantly lower and higher, respectively, in the subacute phase than in the acute phase in both iKD and cKD patients, which differed from those of febrile controls. Lower levels of acute and subacute age-adjusted hemoglobin levels in iKD patients (odds ratio [OR], 0.538 and 0.583; p=0.006 and 0.018, respectively) and higher subacute platelet counts in cKD patients (OR, 1.004; p=0.014) were correlated with the risk of coronary dilation. A higher acute neutrophil-to-lymphocyte ratio was associated with aneurysm only in cKD patients (OR, 1.059; p=0.044).

Conclusions

The iKD patients share KD-specific laboratory marker profiles in terms of complete blood cell counts and acute phase reactant levels with cKD patients. However, the factors predicting coronary dilation differ according to the phenotype; lower acute and subacute age-adjusted hemoglobin levels predict coronary dilation only in iKD patients.

High-Dose Vitamin D3 Administration Is Associated With Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Anemia and vitamin D deficiency are highly prevalent in critical illness, and vitamin D status has been associated with hemoglobin concentrations in epidemiologic studies. We examined the effect of high-dose vitamin D therapy on hemoglobin and hepcidin concentrations in critically ill adults.

MATERIALS AND METHODS

Mechanically ventilated critically ill adults (N = 30) enrolled in a pilot double-blind, randomized, placebo-controlled trial of high-dose vitamin D3 (D3 ) were included in this analysis. Participants were randomized to receive placebo, 50,000 IU D3 , or 100,000 IU D3 daily for 5 days (totaling 250,000 IU D3 and 500,000 IU D3 , respectively). Blood was drawn weekly throughout hospitalization for up to 4 weeks. Linear mixed-effects models were used to assess change in hemoglobin and hepcidin concentrations by treatment group over time.

RESULTS

At enrollment, >75% of participants in all groups had plasma 25-hydroxyvitamin D (25(OH)D) concentrations <30 ng/mL, and >85% of participants across groups were anemic. In the 500,000-IU D3 group, hemoglobin concentrations increased significantly over time (Pgroup × time = .01) compared with placebo but did not change in the 250,000-IU D3 group (Pgroup × time = 0.59). Hepcidin concentrations decreased acutely in the 500,000-IU D3 group relative to placebo after 1 week (P = .007). Hepcidin did not change significantly in the 250,000-IU D3 group.

CONCLUSION

In these critically ill adults, treatment with 500,000 IU D3 was associated with increased hemoglobin concentrations over time and acutely reduced serum hepcidin concentrations. These findings suggest that high-dose vitamin D may improve iron metabolism in critical illness and should be confirmed in larger studies.

Impact of chronic and acute inflammation on extra- and intracellular iron homeostasis

Inflammation has a major impact on iron homeostasis. This review focuses on acute and chronic inflammation as it affects iron trafficking and, as a result, the availability of this essential micronutrient to the host. In situations of microbial infection, not only the host is affected but also the offending microorganisms, which, in general, not only require iron for their own growth but have evolved mechanisms to obtain it from the infected host. Key players in mammalian iron trafficking include several types of cells important to iron acquisition, homeostasis, and hematopoiesis (enterocytes, hepatocytes, macrophages, hematopoietic cells, and in the case of pregnancy, placental syncytiotrophoblast cells) and several forms of chaperone proteins, including, for nonheme iron, the transport protein transferrin and the intracellular iron-storage protein ferritin, and for heme iron, the chaperone proteins haptoglobin and hemopexin. Additional key players are the cell membrane-associated iron transporters, particularly ferroportin (FPN), the only protein known to modulate iron export from cells, and finally, the iron-regulatory hormone hepcidin, which, in addition to having antibacterial activity, regulates the functions of FPN. Interestingly, the impact of infection on iron homeostasis differs among pathogens whose mode of infection is mainly intracellular or extracellular. Understanding how inflammation affects each of these processes may be crucial for understanding how inflammation affects iron status, indicators of iron sufficiency, and iron supplementation during inflammation and how it may potentially result in a beneficial or detrimental impact on the host.

An Update on AMPK in Hydrogen Sulfide Pharmacology

Hydrogen sulfide (H₂S), the third bio-active gasotransmitter, is produced endogenously and tightly involved in the pathogenesis and treatment for various diseases. Adenosine 5′-monophosphate-activated protein kinase (AMPK) plays a paramount role in maintaining cellular energetic balance. Increasing evidences have also suggested AMPK as a novel modulator in multiple pathological conditions. In this paper, we will review the biological principles of H₂S and AMPK, and most importantly, the recent discoveries regarding AMPK-mediated pharmacological actions of H₂S. Emphasis will be laid on AMPK/H₂S interactions in the cardiovascular system, autophagy, diabetic complications, and inflammation. In most cases described in this article, by promoting AMPK activation, H₂S exerts cytoprotective effects or therapeutic potentials, though there remain some controversies before we can fully understand the involved mechanisms. Further researches are in need to investigate more closely any relationship between H₂S and AMPK, and to put forward the development of H₂S donors for clinical application.

Management of inflammatory bowel disease-related anemia and iron deficiency with specific reference to the role of intravenous iron in current practice

INTRODUCTION

Anemia is a common extraintestinal manifestation in patients with inflammatory bowel disease, impacting disease prognosis, morbidity, hospitalization rates and time lost from work. While iron deficiency anemia and anemia of chronic inflammation predominate, combinations of hematimetric and biochemical markers facilitate the diagnosis and targeted therapy of other etiologies according to their underlying pathophysiological causes. Intravenous iron replacement is currently recommended in IBD patients with moderate to severe anemia or intolerance to oral iron. Areas covered: This review examines the impact, pathophysiology and diagnostics of iron deficiency and anemia, compares the characteristics and safety profiles of available oral and intravenous iron preparations, and highlights issues which require consideration in decision making for therapy administration and monitoring. Expert opinion: Modern intravenous iron formulations have been shown to be safe and effective in IBD patients, allowing rapid anemia correction and repletion of iron stores. While traditional oral iron preparations are associated with increased inflammation, negative effects on the microbiome, and poor tolerance and compliance, first clinical trial data indicate that newer oral compounds such as ferric maltol and sucrosomial iron offer improved tolerability and may thus offer a viable alternative for the future.

Exhaled breath condensate methods adapted from human studies using longitudinal metabolomics for predicting early health alterations in dolphins

Monitoring health conditions is essential to detect early asymptomatic stages of a disease. To achieve this, blood, urine and breath samples are commonly used as a routine clinical diagnostic. These samples offer the opportunity to detect specific metabolites related to diseases and provide a better understanding of their development. Although blood samples are commonly used routinely to monitor health, the implementation of a relatively noninvasive technique, such as exhaled breath condensate (EBC) analysis, may further benefit the well-being of both humans and other animals. EBC analysis can be used to track possible physical or biochemical alterations caused by common diseases of the bottlenose dolphin (Tursiops truncatus), such as infections or inflammatory-mediated processes. We have used an untargeted metabolomic method with liquid chromatography-mass spectrometry analysis of EBC samples to determine biomarkers related to disease development. In this study, five dolphins under human care were followed up for 1 year. We collected paired blood, physical examination information, and EBC samples. We then statistically correlated this information to predict specific health alterations. Three dolphins provided promising case study information about biomarkers related to cutaneous infections, respiratory infections, dental disease, or hormonal changes (pregnancy). The use of complementary liquid chromatography platforms, with hydrophilic interaction chromatography and reverse-phased columns, allowed us to detect a wide spectrum of EBC biomarker compounds that could be related to these health alterations. Moreover, these two analytical techniques not only provided complementary metabolite information but in both cases they also provided promising diagnostic information for these health conditions. Graphical abstract Collection of the exhaled condensed breath from a bottlenose dolphin from U.S. Navy Marine Mammal Program (MMP).

Vitamin D Status Is Associated with Hepcidin and Hemoglobin Concentrations in Children with Inflammatory Bowel Disease

BACKGROUND

Anemia, iron deficiency, and hypovitaminosis D are well-known comorbidities in inflammatory bowel disease (IBD). Epidemiologic studies have linked vitamin D deficiency with increased risk of anemia, and in vitro studies suggest that vitamin D may improve iron recycling through downregulatory effects on hepcidin and proinflammatory cytokines.

METHODS

We aimed to investigate the association of vitamin D status with inflammation, iron biomarkers, and anemia in pediatric IBD. Cross-sectional data were obtained from N = 69 patients with IBD aged 5 to <19 years. Iron biomarkers (ferritin, soluble transferrin receptor), and 25-hydroxyvitamin D (25(OH)D), inflammatory biomarkers (C-reactive protein and α-1-acid glycoprotein), hepcidin, and hemoglobin were collected. Iron biomarkers were regression corrected for inflammation. Multivariable logistic/linear models were used to examine the associations of 25(OH)D with inflammation, iron status, hepcidin, and anemia.

RESULTS

Approximately 50% of subjects were inflamed (C-reactive protein >5 mg/L or α-1-acid glycoprotein >1 g/L). Iron deficiency prevalence (inflammation-corrected ferritin <15 μg/L or soluble transferrin receptor >8.3 mg/L) was 67%; anemia was 36%, and vitamin D insufficiency (25(OH)D <30 ng/mL) was 77%. In linear regression models, vitamin D insufficiency was associated with increased hepcidin levels (β [SE] = 0.6 [0.2], P = 0.01) and reduced hemoglobin (β [SE] = -0.9 [0.5], P = 0.046), controlling for age, sex, race, insurance status, body mass index for age, inflammation, disease diagnosis (ulcerative colitis versus Crohn's disease), and disease duration, compared with 25(OH)D ≥30 ng/mL.

CONCLUSIONS

Our results suggest that concentrations of 25(OH)D ≥30 ng/mL are associated with lower hepcidin and higher hemoglobin levels. Further research is needed to clarify the association of vitamin D with inflammation, iron status, and anemia in pediatric IBD.

AMPK Serves as a Therapeutic Target Against Anemia of Inflammation

AIMS

Anemia of inflammation (AI), the second prevalent anemia, is associated with worse prognosis and increased mortality in numerous chronic diseases. We recently reported that the gasotransmitter hydrogen sulfide (H₂S) suppressed the inflammatory activation of signal transducer and activator of transcription 3 (STAT3) and hepcidin, the critical mediators of AI. Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a novel inflammatory regulator and might be activated by H₂S. In this study, we determined whether AMPK played a role in H₂S-mediated anti-inflammatory response in AI and evaluated the therapeutic potential of AMPK against AI by pharmacological and clinical approaches.

RESULTS

We showed that AMPK mediated the inhibition of STAT3, hepcidin, and AI by H₂S during inflammation. Moreover, pharmacological and genetic activation of AMPK ameliorated hepcidin production, corrected iron dysregulation, and relieved hypoferremia and anemia in both acute and chronic inflammation models in mice. Mechanistic studies indicated that AMPK suppressed STAT3/hepcidin activation by promoting proteasome-mediated Janus kinase 2 (JAK2) degradation, which was dependent on the intact function of suppressor of cytokine signaling 1 (SOCS1) and increased interactions between SOCS1 and JAK2. Most importantly, the AMPK activator metformin was associated with decreased serum hepcidin content and anemia morbidity in Chinese type 2 diabetes mellitus patients.

INNOVATION

This is the first study to demonstrate the inhibition of inflammatory hepcidin and AI by AMPK-induced JAK2 degradation. Our work uncovered AMPK as a novel therapeutic target, and metformin as a potential therapy against AI.

CONCLUSION

The present work demonstrated that AMPK mediated the therapeutic effects of H₂S and relieved AI by promoting SOCS1-mediated JAK2 degradation. Antioxid. Redox Signal. 27, 251-268.

The interplay between iron and oxygen homeostasis with a particular focus on the heart

Iron is subject to tight homeostatic control in mammals. At the systemic level, iron homeostasis is controlled by the liver-derived hormone hepcidin acting on its target ferroportin in the gut, spleen, and liver, which form the sites of iron uptake, recycling, and storage, respectively. At the cellular level, iron homeostasis is dependent on the iron regulatory proteins IRP1/IRP2. Unique chemical properties of iron underpin its importance in biochemical reactions involving oxygen. As such, it is not surprising that there are reciprocal regulatory links between iron and oxygen homeostasis, operating both at the systemic and cellular levels. Hypoxia activates the IRP pathway, and in addition suppresses liver hepcidin through endocrine factors that have yet to be fully elucidated. This review summarizes current knowledge on the interplay between oxygen and iron homeostasis and describes recent insights gained into this interaction in the context of the heart. These include the recognition that the hepcidin/ferroportin axis plays a vital role in the regulation of intracellular iron homeostasis as well as regulating systemic iron availability. As is the case for other aspects of iron homeostasis, hypoxia significantly modulates the function of the hepcidin/ferroportin pathway in the heart. Key areas still to understand are the interactions between cardiac iron and diseases of the heart where hypoxia is a recognized component.

Prognostic value of red blood cell distribution width in hepatocellular carcinoma

Red blood cell distribution width (RDW) is a simple, inexpensive, routinely measured and automatically reported blood test parameter, which reflects the degree of anisocytosis of red blood cells in peripheral blood. RDW was found to be associated with and retain clinical significance for assessing disease severity and outcomes in a number of hematological and solid malignancies. Motley of interacting clinical and biochemical factors have an impact on the red cell population biology. Malignancies per se can act as a causative factor, or anisocytosis may develop as a result of chronic inflammation. RDW has also been shown to be affected by nutritional status, which is typically deranged in malignancies. RDW is shown to be a clinically useful marker of disease severity and level of fibrosis in liver cirrhosis of various causes such as hepatitis B, hepatitis C and non-alcoholic fatty liver disease. Whether liver cirrhosis patients with higher RDW are at increased risk of hepatocellular cancer is yet to be determined, but several lines of evidence confirm that RDW has clinical significance in hepatocellular carcinoma (HCC). In this review, we specifically discuss the current literature about the association between RDW and HCC. The available evidences were summarized and the potential underlying mechanisms were analyzed.

Iron transport proteins: Gateways of cellular and systemic iron homeostasis

Cellular iron homeostasis is maintained by iron and heme transport proteins that work in concert with ferrireductases, ferroxidases, and chaperones to direct the movement of iron into, within, and out of cells. Systemic iron homeostasis is regulated by the liver-derived peptide hormone, hepcidin. The interface between cellular and systemic iron homeostasis is readily observed in the highly dynamic iron handling of four main cell types: duodenal enterocytes, erythrocyte precursors, macrophages, and hepatocytes. This review provides an overview of how these cell types handle iron, highlighting how iron and heme transporters mediate the exchange and distribution of body iron in health and disease.

Impact of high iron intake on cognition and neurodegeneration in humans and in animal models: a systematic review

Context

Accumulation of brain iron is linked to aging and protein-misfolding neurodegenerative diseases. High iron intake may influence important brain health outcomes in later life.

Objective

The aim of this systematic review was to examine evidence from animal and human studies of the effects of high iron intake or peripheral iron status on adult cognition, brain aging, and neurodegeneration.

Data Sources

MEDLINE, Scopus, CAB Abstracts, the Cochrane Central Register of Clinical Trials, and OpenGrey databases were searched.

Study Selection

Studies investigating the effect of elevated iron intake at all postnatal life stages in mammalian models and humans on measures of adult brain health were included.

Data Extraction

Data were extracted and evaluated by two authors independently, with discrepancies resolved by discussion. Neurodegenerative disease diagnosis and/or behavioral/cognitive, biochemical, and brain morphologic findings were used to study the effects of iron intake or peripheral iron status on brain health. Risk of bias was assessed for animal and human studies. PRISMA guidelines for reporting systematic reviews were followed.

Results

Thirty-four preclinical and 14 clinical studies were identified from database searches. Thirty-three preclinical studies provided evidence supporting an adverse effect of nutritionally relevant high iron intake in neonates on brain-health-related outcomes in adults. Human studies varied considerably in design, quality, and findings; none investigated the effects of high iron intake in neonates/infants.

Conclusions

Human studies are needed to verify whether dietary iron intake levels used in neonates/infants to prevent iron deficiency have effects on brain aging and neurodegenerative disease outcomes.

Serum 25-hydroxyvitamin D but not dietary vitamin D intake is associated with hemoglobin in women of reproductive age in rural northern Vietnam

BACKGROUND AND OBJECTIVES

Hypovitaminosis D and anemia are both prevalent in Vietnam, and low vitamin D status may be a risk factor for anemia. This study aimed to 1) describe vitamin D intake and its determinants, and 2) examine the associations of vitamin D intake and serum 25(OH)D concentrations with hemoglobin and anemia.

METHODS AND STUDY DESIGN

We used data from the baseline survey of a pre-conceptual micronutrient supplementation trial in women of reproductive age (WRA) in Thai Nguyen, Vietnam (N = 4961). Vitamin D intake was estimated using a semi-quantitative food frequency questionnaire (FFQ). Multivariable regression models were used for the analyses.

RESULTS

Median vitamin D intake was 0.2 µg/d (8.0 IU) [IQR: 0.4]. Age, being a farmer, food insecurity, and body mass index (BMI) were inversely associated with vitamin D intake, while socioeconomic status (SES), total energy intake, and education were positively associated with vitamin D intake. Vitamin D intake was not associated with hemoglobin concentration or anemia after adjusting for age, BMI, total energy intake, transferrin receptor, C-reactive protein, α1-acid glycoprotein, SES, occupation, education, ethnicity, and food insecurity (P = 0.56 and P = 0.65 for hemoglobin and anemia, respectively). Controlling for the same covariates, 25(OH)D <50 nmol/L (vs. ≥50 nmol/L) was associated with decreased hemoglobin concentrations (β = -0.91 (SE:0.42), P = 0.03), but not with anemia (P = 0.11).

CONCLUSIONS

Low vitamin D status may be linked to reduced hemoglobin concentrations, but the role of diet in this association was not evident in this population of WRA in Vietnam where dietary vitamin D intake was very low.

Vitamin D deficiency and anemia risk in children: a review of emerging evidence

There has been renewed scientific interest in the sequelae of vitamin D deficiency, given the emerging evidence on the diverse biologic functions of vitamin D, besides its fundamental role in bone and mineral metabolism. For the past decade, the evidence in the medical literature pointing to a relationship between anemia risk and vitamin D deficiency has been accumulating. This paper critically reviews the current evidence linking vitamin D deficiency to anemia risk in children. The synthesized evidence indicates that the studies, which were preponderantly conducted among the adult population, not only reported a bidirectional relationship between vitamin D deficiency and anemia but also showed a racial effect. In studies conducted among children, similar results were reported. Although the causal association of vitamin D deficiency with anemia risk (especially iron-deficiency anemia) remains debatable, the noncalcemic actions of the vitamin and its analogs hold prospects for several novel clinical applications. There is, however, unanimity in many reports suggesting that vitamin D deficiency is directly associated with anemia of chronic disease or inflammation. Despite the advances in unraveling the role of vitamin D in iron homeostasis, further research is still required to validate causality in the relationship between vitamin D deficiency and anemia, as well as to determine its optimal dosing, the ideal recipients for therapeutic intervention, and the preferred analogs to administer.

Iron- and Hepcidin-Independent Downregulation of the Iron Exporter Ferroportin in Macrophages during Salmonella Infection

Retention of iron in tissue macrophages via upregulation of hepcidin (HAMP) and downregulation of the iron exporter ferroportin (FPN) is thought to participate in the establishment of anemia of inflammation after infection. However, an upregulation of FPN has been proposed to limit macrophages iron access to intracellular pathogens. Therefore, we studied the iron homeostasis and in particular the regulation of FPN after infection with Salmonella enterica serovar Typhimurium in mice presenting tissue macrophages with high iron (AcB61), basal iron (A/J and wild-type mice), or low iron (Hamp knock out, Hamp^-/-) levels. The presence of iron in AcB61 macrophages due to extravascular hemolysis and strong erythrophagocytosis activity favored the proliferation of Salmonella in the spleen and liver with a concomitant decrease of FPN protein expression. Despite systemic iron overload, no or slight increase in Salmonella burden was observed in Hamp^-/- mice compared to controls. Importantly, FPN expression at both mRNA and protein levels was strongly decreased during Salmonella infection in Hamp^-/- mice. The repression of Fpn mRNA was also observed in Salmonella-infected cultured macrophages. In addition, the downregulation of FPN was associated with decreased iron stores in both the liver and spleen in infected mice. Our findings show that during Salmonella infection, FPN is repressed through an iron and hepcidin-independent mechanism. Such regulation likely provides the cellular iron indispensable for the growth of Salmonella inside the macrophages.

Interleukin-1β (IL-1β) transcriptionally activates hepcidin by inducing CCAAT enhancer-binding protein δ (C/EBPδ) expression in hepatocytes

Hepcidin is a liver-derived hormone that negatively regulates serum iron levels and is mainly regulated at the transcriptional level. Previous studies have clarified that in addition to hepatic iron levels, inflammation also efficiently increases hepatic hepcidin expression. The principle regions responsible for efficient hepcidin transcription are bone morphogenetic protein-responsive elements (BMP-REs) 1 and 2 as well as the signal transducer and activator of transcription 3-binding site (STAT-BS). Here, we show that the proinflammatory cytokine interleukin-1β (IL-1β) efficiently increases hepcidin expression in human HepG2 liver-derived cells and primary mouse hepatocytes. The primary region responsible for IL-1β-mediated hepcidin transcription was the putative CCAAT enhancer-binding protein (C/EBP)-binding site (C/EBP-BS) at the hepcidin promoter spanning nucleotides -329 to -320. IL-1β induces the expression of C/EBPδ but neither C/EBPα nor C/EBPβ in hepatocytes, and C/EBPδ bound to the C/EBP-BS in an IL-1β-dependent manner. Lipopolysaccharide (LPS) induced the expression of IL-1β in Kupffer cells and hepatocytes in the mouse liver; furthermore, the culture supernatants from the macrophage-like cell line RAW264.7 treated with LPS potentiated the stimulation of hepcidin expression in hepatocytes. The present study reveals that: 1) inflammation induces IL-1β production in Kupffer cells and hepatocytes; 2) IL-1β increases C/EBPδ expression in hepatocytes; and 3) induction of C/EBPδ activates hepcidin transcription via the C/EBP-BS that has been uncharacterized yet. In cooperation with the other pathways activated by inflammation, IL-1β pathway stimulation leads to excess production of hepcidin, which could be causative to anemia of inflammation.

Anemia in Kawasaki Disease: Hepcidin as a Potential Biomarker

Kawasaki disease (KD) is an autoimmune-like disease and acute childhood vasculitis syndrome that affects various systems but has unknown etiology. In addition to the standard diagnostic criteria, anemia is among the most common clinical features of KD patients and is thought to have a more prolonged duration of active inflammation. In 2001, the discovery of a liver-derived peptide hormone known as hepcidin began revolutionizing our understanding of anemia’s relation to a number of inflammatory diseases, including KD. This review focuses on hepcidin-induced iron deficiency’s relation to transient hyposideremia, anemia, and disease outcomes in KD patients, and goes on to suggest possible routes of further study.

Oral sucrosomial iron versus intravenous iron in anemic cancer patients without iron deficiency receiving darbepoetin alfa: a pilot study

Purpose

Erythropoiesis-stimulating agents (ESAs) are often used in treatment of patients with chemotherapy-induced anemia. Many studies have demonstrated an improved hemoglobin (Hb) response when ESA is combined with intravenous iron supplementation and a higher effectiveness of intravenous iron over traditional oral iron formulations. A new formulation of oral sucrosomial iron featuring an increased bioavailability compared to traditional oral formulations has recently become available and could provide a valid alternative to those by intravenous (IV) route. Our study evaluated the performance of sucrosomial iron versus intravenous iron in increasing hemoglobin in anemic cancer patients receiving chemotherapy and darbepoetin alfa, as well as safety, need of transfusion, and quality of life (QoL).

Materials and methods

The present study considered a cohort of 64 patients with chemotherapy-related anemia (Hb >8 g/dL <10 g/dL) and no absolute or functional iron deficiency, scheduled to receive chemotherapy and darbepoetin. All patients received darbepoetin alfa 500 mcg once every 3 weeks and were randomly assigned to receive 8 weeks of IV ferric gluconate 125 mg weekly or oral sucrosomial iron 30 mg daily. The primary endpoint was to demonstrate the performance of oral sucrosomial iron in improving Hb response, compared to intravenous iron. The Hb response was defined as the Hb increase ≥2 g/dL from baseline or the attainment Hb ≥ 12 g/dL.

Results

There was no difference in the Hb response rate between the two treatment arms. Seventy one percent of patients treated with IV iron achieved an erythropoietic response, compared to 70% of patients treated with oral iron. By conventional criteria, this difference is considered to be not statistically significant. There were also no differences in the proportion of patients requiring red blood cell transfusions and changes in QoL. Sucrosomial oral iron was better tolerated.

Conclusion

In cancer patients with chemotherapy-related anemia receiving darbepoetin alfa, sucrosomial oral iron provides similar increase in Hb levels and Hb response, with higher tolerability without the risks or side effects of IV iron.

Electronic supplementary material

The online version of this article (doi:10.1007/s00520-017-3690-z) contains supplementary material, which is available to authorized users.

Carbon Nanotubes Disrupt Iron Homeostasis and Induce Anemia of Inflammation through Inflammatory Pathway as a Secondary Effect Distant to Their Portal-of-Entry

Although numerous toxicological studies have been performed on carbon nanotubes (CNTs), a few studies have investigated their secondary and indirect effects beyond the primary target tissues/organs. Here, a cascade of events are investigated: the initiating event and the subsequent key events necessary for the development of phenotypes, namely CNT-induced pro-inflammatory effects on iron homeostasis and red blood cell formation, which are linked to anemia of inflammation (AI). A panel of CNTs are prepared including pristine multiwall CNTs (P-MWCNTs), aminated MWCNTs (MWCNTs-NH₂ ), polyethylene glycol MWCNTs (MWCNTs-PEG), polyethyleneimine MWCNTs (MWCNTs-PEI), and carboxylated MWCNTs (MWCNTs-COOH). It has been demonstrated that all CNT materials provoke inflammatory cytokine interleukin-6 (IL-6) production and stimulate hepcidin induction, associated with disordered iron homeostasis, irrespective of exposure routes including intratracheal, intravenous, and intraperitoneal administration. Meanwhile, PEG and COOH modifications can ameliorate the activation of IL-6-hepcidin signaling. Long-term exposure of MWCNTs results in AI and extramedullary erythropoiesis. Thus, an adverse outcome pathway is identified: MWCNT exposure leads to inflammation, hepatic hepcidin induction, and disordered iron metabolism. Together, the combined data depict the hazardous secondary toxicity of CNTs in incurring anemia through inflammatory pathway. This study will also open a new avenue for future investigations on CNT-induced indirect and secondary adverse effects.

Clinical meaning and implications of serum hemoglobin levels in patients with rheumatoid arthritis

OBJECTIVE

Anemia is a common problem in rheumatoid arthritis (RA), associated with radiographic progression and disability. We explored the association of hemoglobin with a comprehensive set of variables in RA patients.

METHODS

We included RA outpatients in the routine setting. For each patient we performed measurements (clinical measures, blood tests including serology, markers of acute phase response and iron metabolism, including hepcidin, and circulating hematopoietic precursor levels) at baseline and 12 weeks thereafter, and analyzed their changes in patients with a treatment adaptation at baseline. We performed principal component analysis (PCA) to identify thematic groups hemoglobin was related to. Then we constructed multivariable linear models to assess the contribution of individual variables to the variability of hemoglobin.

RESULTS

In total, 88 patients were included (age: 58 ± 12; disease duration: 9.3 ± 9.6 years). Cross-sectionally (at baseline and week 12) hemoglobin levels were tied to iron metabolism and hematopoiesis, but not to clinical activity, based on thematic groups extracted from the PCA. In contrast, longitudinal changes in hemoglobin levels were closely linked to changes in clinical activity. Conversely, hepcidin reflected iron metabolism cross-sectionally, but changes in acute phase response longitudinally. In multivariable analysis variability components of hemoglobin were explainable by ferritin, ESR, evaluator global assessment (EGA), and iron levels, while components of hemoglobin changes were explained by changes in EGA mostly. Hepcidin was not independently associated with hemoglobin.

CONCLUSION

Besides its dependence on body iron status, changes in hemoglobin levels are strongly tied to disease activity, possibly revealing more about disease activity than other laboratory markers.

Anemia of Inflammation: A Review

Impaired iron homeostasis and the suppressive effects of proinflammatory cytokines on erythropoiesis, together with alterations of the erythrocyte membrane that impair its survival, cause anemia of inflammation. Recent epidemiologic studies have connected inflammatory anemia with critical illness, obesity, aging, kidney failure, cancer, chronic infection, and autoimmune disease. The proinflammatory cytokine, interleukin-6, the iron regulatory hormone, hepcidin, and the iron exporter, ferroportin, interact to cause iron sequestration in the setting of inflammation. Although severe anemia is associated with adverse outcomes in critical illness, experimental models suggest that iron sequestration is part of a natural defense against pathogens.

Current evaluation and management of anemia in patients with inflammatory bowel disease

Anemia is a common extraintestinal manifestation in IBD patients and considerably impacts disease prognosis, hospitalization rates and time lost from work. While iron deficiency anemia is predominant, combinations of hematimetric and biochemical markers enable detection and targeted therapy of other etiologies including vitamin B12/folic acid deficiencies, hemolysis, myelosuppression and pharmacotherapies. Areas covered: Current literature was searched for articles focusing on etiology, diagnostics and therapy of anemia in IBD. In the light of their own experience, the authors describe the physiology of anemia in IBD and present current evidence endorsing diagnostic and therapeutic options, focusing particularly on non-iron-related etiologies. Expert commentary: Anemia in IBD is polyetiological, reaching far beyond iron deficiency anemia. While clinicians need to be aware of the increasing pallet of diagnostic tools and therapeutic options, detailed studies are needed to develop more convenient test procedures, long-term treatment and monitoring strategies, and unified guidelines for daily practice.

Perinatal Factors Affecting Serum Hepcidin Levels in Low-Birth-Weight Infants

BACKGROUND

Hepcidin, an iron-regulatory hormone, plays a key role in preventing iron overload. Few studies have investigated the regulation of hepcidin in low-birth-weight (LBW) infants who are vulnerable to iron imbalance.

OBJECTIVES

To identify perinatal factors associated with serum hepcidin levels in LBW infants.

METHODS

Ninety-two LBW infants with a median gestational age (GA) of 32.6 weeks and birth weight of 1,587 g were prospectively enrolled. Serum hepcidin-25 (Hep25) levels were measured from umbilical cord blood using liquid chromatography-tandem mass spectrometry. The relationship between Hep25 levels and prematurity or other possible hepcidin-regulatory factors was evaluated.

RESULTS

The median Hep25 level was 7.3 ng/mL (interquartile range: 2.85-16.38). log(Hep25) correlated with birth weight (r = 0.229, p = 0.028), log(interleukin-6 [IL-6]) (r = 0.408, p < 0.001), log(erythropoietin) (r = -0.302, p = 0.004), transferrin saturation (r = 0.29, p = 0.005), soluble transferrin receptor (r = -0.500, p < 0.001), and log(ferritin) (r = 0.696, p < 0.001). Serum iron and hemoglobin levels did not correlate with log(Hep25). Hep25 levels were higher among infants with chorioamnionitis and infants born vaginally and lower among infants born to mothers with pregnancy-induced hypertension than among infants without the respective characteristics. Stepwise multiple linear regression analysis confirmed the significant association of log(Hep25) with GA, log(IL-6), log(erythropoietin), and soluble transferrin receptor.

CONCLUSIONS

Among LBW infants, GA, IL-6, erythropoietin, and soluble transferrin receptor were associated with Hep25 levels. Therefore, prematurity, inflammation, hypoxia, and erythropoietic activity may be important perinatal factors that affect hepcidin levels.

Hepcidin regulation in the anemia of inflammation

PURPOSE OF REVIEW

Anemia is prevalent in patients with infections and other inflammatory conditions. Induction of the iron regulatory hormone hepcidin has been implicated in the pathogenesis of anemia of inflammation. This review outlines recent discoveries in understanding how hepcidin and its receptor ferroportin are regulated, how they contribute to anemia of inflammation, and how this knowledge may help guide new diagnostic and therapeutic strategies for this disease.

RECENT FINDINGS

IL-6 is a primary driver for hepcidin induction in many models of anemia of inflammation, but the SMAD1/5/8 pathway also contributes, likely via Activin B and SMAD-STAT3 interactions at the hepcidin promoter. Hepcidin has an important functional role in many, but not all forms of anemia of inflammation, although hepcidin-independent mechanisms also contribute. In certain populations, hepcidin assays may help target therapy with iron or erythropoiesis-stimulating agents to patients who may benefit most. New therapies targeting the hepcidin-ferroportin axis have shown efficacy in preclinical and early clinical studies.

SUMMARY

Recent studies confirm an important role for the hepcidin-ferroportin axis in the development of anemia of inflammation, but also highlight the diverse and complex pathogenesis of this disorder depending on the underlying disease. Hepcidin-based diagnostic and therapeutic strategies offer promise to improve anemia treatment, but more work is needed in this area.

An essential cell-autonomous role for hepcidin in cardiac iron homeostasis

Hepcidin is the master regulator of systemic iron homeostasis. Derived primarily from the liver, it inhibits the iron exporter ferroportin in the gut and spleen, the sites of iron absorption and recycling respectively. Recently, we demonstrated that ferroportin is also found in cardiomyocytes, and that its cardiac-specific deletion leads to fatal cardiac iron overload. Hepcidin is also expressed in cardiomyocytes, where its function remains unknown. To define the function of cardiomyocyte hepcidin, we generated mice with cardiomyocyte-specific deletion of hepcidin, or knock-in of hepcidin-resistant ferroportin. We find that while both models maintain normal systemic iron homeostasis, they nonetheless develop fatal contractile and metabolic dysfunction as a consequence of cardiomyocyte iron deficiency. These findings are the first demonstration of a cell-autonomous role for hepcidin in iron homeostasis. They raise the possibility that such function may also be important in other tissues that express both hepcidin and ferroportin, such as the kidney and the brain.

DOI:http://dx.doi.org/10.7554/eLife.19804.001

Many proteins inside cells require iron to work properly, and so this mineral is an essential part of the diets of most mammals. However, because too much iron in the body is also bad for health, mammals possess several proteins whose role is to maintain the balance of iron. Two proteins in particular, called hepcidin and ferroportin, are thought to be important in this process. Some ferroportin is found in the cells that line the gut (where iron is absorbed into the body) and is required to release this iron into the bloodstream. It is also found in the spleen, which is where iron is removed from old red blood cells so that it can be recycled. The liver produces hepcidin to control when ferroportin is active in the gut and spleen.

Both hepcidin and ferroportin are also found in heart cells. In 2015, a study reported that that heart ferroportin plays an important role in heart activity. However, it was not clear what role hepcidin plays in this organ.

Now, Lakhal-Littleton et al. – including many of the researchers from the previous work – have genetically engineered mice such that they specifically lacked heart hepcidin, or had a version of ferroportin in their heart that does not respond to hepcidin. The experiments show that these changes caused fatal heart failure in the mice because ferroportin releases iron from heart cells in an uncontrolled manner. Lakhal-Littleton et al. were able to prevent heart failure by injecting the animals with iron directly into the bloodstream. These findings show that hepcidin produced outside the liver has a role in controlling the levels of iron in the body’s organs.

Other organs such as the brain, kidney and placenta all have their own forms of hepcidin and ferroportin; further work could investigate the roles of these proteins. Finally, another challenge for the future will be to test whether new drugs that are being developed to block or mimic hepcidin from the liver have the potential to treat heart conditions in humans.

DOI:http://dx.doi.org/10.7554/eLife.19804.002

Use of routinely available clinical, nutritional, and functional criteria to classify cachexia in advanced cancer patients

BACKGROUND

Cachexia is a highly prevalent syndrome in cancer and chronic diseases. However, due to the heterogeneous features of cancer cachexia, its identification and classification challenge clinical practitioners.

OBJECTIVE

To determine the clinical relevance of a cancer cachexia classification system in advanced cancer patients.

DESIGN

Beginning with the four-stage classification system proposed for cachexia [non-cachexia (NCa), pre-cachexia (PCa), cachexia (Ca) and refractory cachexia (RCa)], we assigned patients to these cachexia stages according to five classification criteria available in clinical practice: 1) biochemistry (high C-reactive protein or leukocytes, or hypoalbuminemia, or anemia), 2) food intake (normal/decreased), weight loss: 3) moderate (≤5%) or 4) significant (>5%/past six months) and 5) performance status (Eastern Cooperative Oncology Group Performance Status ≥ 3). We then determined if symptom severity, body composition changes, functional levels, hospitalizations and survival rates varied significantly across cachexia stages.

RESULTS

Two-hundred and ninety-seven advanced cancer patients with primary gastrointestinal and lung tumors were included. Patients were classified into Ca (36%), PCa and RCa (21%, respectively) and NCa (15%). Significant (p < 0.05) differences were observed among cachexia stages for most of the outcome measures (symptoms, body composition, handgrip strength, emergency room visits and length of hospital stays) according to cachexia severity. Survival also differed between cachexia stages (except between PCa and Ca).

CONCLUSION

Five clinical criteria can be used to stage cancer cachexia patients and predict important clinical, nutritional and functional outcomes. The lack of statistical difference between PCa and Ca in almost all clinical outcomes examined suggests either that the PCa group includes patients already affected by early cachexia or that more precise criteria are needed to differentiate PCa from Ca patients. More studies are required to validate these findings.

The Evidence-Based Evaluation of Iron Deficiency Anemia

Anemia is a prevalent disease with multiple possible etiologies and resultant complications. Iron deficiency anemia is a common cause of anemia and is typically due to insufficient intake, poor absorption, or overt or occult blood loss. Distinguishing iron deficiency from other causes of anemia is integral to initiating the appropriate treatment. In addition, identifying the underlying cause of iron deficiency is also necessary to help guide management of these patients. We review the key components to an evidence-based, cost-conscious evaluation of suspected iron deficiency anemia.

Association between depression and anemia in otherwise healthy adults

OBJECTIVE

It remains debated whether anemia is associated with depression, independently of physical health factors. We report a large-scale cross-sectional study examining this association in adults free of chronic disease and medication from the general population.

METHOD

Hemoglobin levels were measured among 44 173 healthy participants [63% men; mean [standard deviation] age = 38.4 (11.1) years] from the 'Investigations Préventives et Cliniques' (IPC) cohort study. Depression was measured with the Questionnaire of Depression 2nd version, Abridged. Logistic regression analyses were performed to examine the association between anemia and depression, while adjusting for a wide range of sociodemographic characteristics and health-related factors (i.e., sex, age, living status, education level, occupational status, alcohol intake, smoking status, physical activity, and body mass index).

RESULTS

Depressed participants were significantly more likely to have anemia compared to non-depressed participants, even after adjustment for sociodemographic and health-related variables [odds ratio = 1.36; 95% confidence interval = (1.18; 1.57)]. Anemia prevalence increased with depression severity, suggesting a dose-response relationship (P for trend <0.001).

CONCLUSION

In healthy adults from the general population, we found a significant and robust association between depression and anemia. Further studies are needed to assess the longitudinal relationship between both conditions and determine the mechanisms underlying this association.

Mast cell activation disease and the modern epidemic of chronic inflammatory disease

A large and growing portion of the human population, especially in developed countries, suffers 1 or more chronic, often quite burdensome ailments which either are overtly inflammatory in nature or are suspected to be of inflammatory origin, but for which investigations to date have failed to identify specific causes, let alone unifying mechanisms underlying the multiple such ailments that often afflict such patients. Relatively recently described as a non-neoplastic cousin of the rare hematologic disease mastocytosis, mast cell (MC) activation syndrome-suspected to be of greatly heterogeneous, complex acquired clonality in many cases-is a potential underlying/unifying explanation for a diverse assortment of inflammatory ailments. A brief review of MC biology and how aberrant primary MC activation might lead to such a vast range of illness is presented.

Intravenous Iron Carboxymaltose as a Potential Therapeutic in Anemia of Inflammation

Intravenous iron supplementation is an effective therapy in iron deficiency anemia (IDA), but controversial in anemia of inflammation (AI). Unbound iron can be used by bacteria and viruses for their replication and enhance the inflammatory response. Nowadays available high molecular weight iron complexes for intravenous iron substitution, such as ferric carboxymaltose, might be useful in AI, as these pharmaceuticals deliver low doses of free iron over a prolonged period of time. We tested the effects of intravenous iron carboxymaltose in murine AI: Wild-type mice were exposed to the heat-killed Brucella abortus (BA) model and treated with or without high molecular weight intravenous iron. 4h after BA injection followed by 2h after intravenous iron treatment, inflammatory cytokines were upregulated by BA, but not enhanced by iron treatment. In long term experiments, mice were fed a regular or an iron deficient diet and then treated with intravenous iron or saline 14 days after BA injection. Iron treatment in mice with BA-induced AI was effective 24h after iron administration. In contrast, mice with IDA (on iron deficiency diet) prior to BA-IA required 7d to recover from AI. In these experiments, inflammatory markers were not further induced in iron-treated compared to vehicle-treated BA-injected mice. These results demonstrate that intravenous iron supplementation effectively treated the murine BA-induced AI without further enhancement of the inflammatory response. Studies in humans have to reveal treatment options for AI in patients.

Effects of Testosterone on Erythropoiesis in a Female Mouse Model of Anemia of Inflammation

The anemia of inflammation is a common problem in inflammatory and autoimmune diseases. We characterized a mouse model of anemia of chronic inflammation induced by repeated injections of low doses of heat-killed Brucella abortus (HKBA), and determined the effects of T administration on erythropoiesis in this model. Female C57BL/6NCrl mice were injected weekly with HKBA for 10 wk. Weekly injections of T or vehicle oil were started 4 wk later. Control mice were injected with saline and vehicle oil in parallel. HKBA-injected mice had significantly lower hemoglobin, hematocrit, mean corpuscular volume, reticulocyte hemoglobin, transferrin saturation (TSAT), and tissue nonheme iron in liver and spleen, enlarged spleen, and up-regulated hepatic expression of inflammatory markers, serum amyloid A1, and TNFα, but down-regulated IL-6, bone morphogenic protein 6, and hepcidin compared with saline controls. HKBA also reduced serum hepcidin and increased serum erythropoietin. Bone marrow erythroid precursors were substantially reduced in HKBA-injected mice. Cotreatment with T increased the percentage of late-stage erythroid precursors in the bone marrow relative to HKBA-injected and saline controls and reversed HKBA-induced suppression of hemoglobin and hematocrit. T also normalized serum erythropoietin, TSAT, and reticulocyte hemoglobin without correcting the expression of the hepatic inflammation markers. Conclusions are that low-dose HKBA induces moderate anemia characterized by chronic inflammation, decreased iron stores, and suppression of erythroid precursors in the bone marrow. T administration reverses HKBA-induced anemia by stimulating erythropoiesis, which is associated with a shift toward accelerated maturation of erythroid precursors in the bone marrow.

High-dose vitamin D3 reduces circulating hepcidin concentrations: A pilot, randomized, double-blind, placebo-controlled trial in healthy adults

BACKGROUND & AIMS

In vitro studies suggest that vitamin D may reduce hepcidin expression and pro-inflammatory cytokine release from monocytes. However, data assessing the vitamin D-mediated effects on iron recycling in healthy individuals are lacking. We aimed to examine the effect of high-dose vitamin D₃ on plasma hepcidin, inflammatory cytokine, and ferritin concentrations in healthy adults.

METHODS

This was a pilot, double-blind, placebo-controlled trial in healthy adults (N = 28) randomized to receive a one-time oral dose of 250,000 IU of vitamin D₃ or placebo. Between- and within-group differences in plasma hepcidin, pro-inflammatory cytokine [interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1)], and ferritin concentrations at baseline and 1 week were determined using two-sample and paired t-tests, respectively.

RESULTS

At baseline, plasma 25-hydroxyvitamin D [25(OH)D], hepcidin, pro-inflammatory cytokine, and ferritin concentrations did not differ between the two groups, and greater than 70% of subjects in both groups were vitamin D deficient (25(OH)D < 20 ng/mL). After 1 week, plasma hepcidin concentrations decreased by 73% from baseline in those who received vitamin D₃ (geometric mean ratio [GMR] = 0.27 (95% CI: 0.11-0.62); P = 0.005); there was no significant change in the placebo group (GMR = 0.73 (95% CI: 0.49-1.09); P = 0.11). Plasma cytokine and ferritin concentrations did not change significantly in either group.

CONCLUSIONS

High-dose vitamin D₃ significantly reduced plasma hepcidin concentrations in healthy adults 1 week post-dosing, without a change in plasma pro-inflammatory cytokine or ferritin concentrations. These data suggest that vitamin D may have a role in regulating iron recycling by acting independently of changes in pro-inflammatory markers.

Hepcidin Response to Iron Therapy in Patients with Non-Dialysis Dependent CKD: An Analysis of the FIND-CKD Trial

Hepcidin is the key regulator of iron homeostasis but data are limited regarding its temporal response to iron therapy, and response to intravenous versus oral iron. In the 56-week, open-label, multicenter, prospective, randomized FIND-CKD study, 626 anemic patients with non-dialysis dependent chronic kidney disease (ND-CKD) and iron deficiency not receiving an erythropoiesis stimulating agent were randomized (1:1:2) to intravenous ferric carboxymaltose (FCM), targeting higher (400-600μg/L) or lower (100-200μg/L) ferritin, or to oral iron. Serum hepcidin levels were measured centrally in a subset of 61 patients. Mean (SD) baseline hepcidin level was 4.0(3.5), 7.3(6.4) and 6.5(5.6) ng/mL in the high ferritin FCM (n = 17), low ferritin FCM (n = 16) and oral iron group (n = 28). The mean (SD) endpoint value (i.e. the last post-baseline value) was 26.0(9.1),15.7(7.7) and 16.3(11.0) ng/mL, respectively. The increase in hepcidin from baseline was significantly smaller with low ferritin FCM or oral iron vs high ferritin FCM at all time points up to week 52. Significant correlations were found between absolute hepcidin and ferritin values (r = 0.65, p<0.001) and between final post-baseline increases in both parameters (r = 0.70, p<0.001). The increase in hepcidin levels over the 12-month study generally mirrored the cumulative iron dose in each group. Hepcidin and transferrin saturation (TSAT) absolute values showed no correlation, although there was an association between final post-baseline increases (r = 0.42, p<0.001). Absolute values (r = 0.36, p = 0.004) and final post-baseline increases of hepcidin and hemoglobin (p = 0.30, p = 0.030) correlated weakly. Baseline hepcidin levels were not predictive of a hematopoietic response to iron therapy. In conclusion, hepcidin levels rose in response to either intravenous or oral iron therapy, but the speed and extent of the rise was greatest with intravenous iron targeting a higher ferritin level. However neither the baseline level nor the change in hepcidin was able to predict response to therapy in this cohort.