Copper deficiency leads to anemia, duodenal hypoxia, upregulation of HIF-2α and altered expression of iron absorption genes in mice

CA9 knockdown enhanced ionizing radiation-induced ferroptosis and radiosensitivity of hypoxic glioma cells

PURPOSE

Ferroptosis is a type of regulatory cell death, caused by excessive lipid peroxidation This study aimed to explore whether ionizing radiation could induce ferroptosis in glioma cells and whether carbonic anhydrase 9 (CA9) knockdown could enhance the killing effect of ionizing radiation on hypoxic glioma cells through ferroptosis.

MATERIALS AND METHODS

The protein levels of Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4) were detected by Western blot in glioma cells irradiated by different doses of X-ray. The relative mRNA levels of ferroptosis markers and intracellular iron-associated proteins were detected by Real-time qPCR. Lipid peroxidation of glioma cells was detected by oxidation-sensitive probe C11-BODIPY581/591 staining. CCK-8 Assay was used to detect cell viability after X-ray irradiation. Cloning formation assay was used to assess the radiosensitivity of glioma cells. The exposure of cell surface calreticulin was measured by immunofluorescence staining.

RESULTS

X-ray induced lipid peroxidation and ferroptosis markers expression in U251 and GL261 glioma cells. Knockdown of CA9 in hypoxic glioma cells significantly altered the expression of iron regulation-related proteins and enhanced X-ray-induced ferroptosis and radiosensitivity. The ferroptosis inhibitor significantly improved the survival of cells irradiated by X-ray, while ferroptosis inducers (FINs) enhanced the lethal effect of X-ray on cells. Enhancing ferroptosis in glioma cells promoted the exposure and release of damage-associated molecular patterns (DAMPs).

CONCLUSIONS

Ionizing radiation can induce ferroptosis in glioma cells. CA9 knockdown can enhance the radiosensitivity of hypoxic glioma cells and overcome the resistance of ferroptosis under hypoxia. Enhancing ferroptosis will become a new idea to improve the efficacy of radiotherapy for glioma.

Therapeutics of managing reduced red cell mass associated with chronic kidney disease - Is there a case for earlier intervention?

Reduced red cell mass is a poor prognostic indicator in chronic kidney disease (CKD) patients. Whilst overt anaemia impacts on the quality of life of patients with CKD, lowered red cell mass may also compromise oxygen delivery to proximal tubular cells and contribute to progressive kidney injury. Epidemiological data from cats with CKD support this hypothesis although controlled interventional studies involving drugs that raise red cell mass in trials designed to test this hypothesis are lacking in both human and veterinary medicine. Recombinant analogues of erythropoietin (EPO) are currently standard of care for human CKD patients where low red cell mass impacts on their quality of life. Resistance to EPO is encountered in 20% to 40% of patients treated, probably due to functional iron deficiency, reflecting the difficulties of managing iron deficiency associated with the chronic inflammation of CKD. Similar issues are likely faced in managing anaemia in feline CKD although published data on the use of human EPO analogues are limited as such treatment in cats risks antibody formation resulting in red cell aplasia and transfusion dependency and so is reserved for late stage cases only. This article reviews the recent alternative therapeutic approach to increase red cell mass using HIF-prolyl hydroxylase inhibitors and explains their mode of action and theoretical advantages over EPO analogues in the context of iron metabolism. The results of human clinical trials and the potential benefit of adopting this approach in feline CKD patients are discussed.

Structural and functional characterisation of HepTH1-5 peptide as a potential hepcidin replacement

Hepcidin is a principal regulator of iron homeostasis and its dysregulation has been recognised as a causative factor in cancers and iron disorders. The strategy of manipulating the presence of hepcidin peptide has been used for cancer treatment. However, this has demonstrated poor efficiency and has been short-lived in patients. Many studies reported using minihepcidin therapy as an alternative way to treat hepcidin dysregulation, but this was only applied to non-cancer patients. Highly conserved fish hepcidin protein, HepTH1-5, was investigated to determine its potential use in developing a hepcidin replacement for human hepcidin (Hepc25) and as a therapeutic agent by targeting the tumour suppressor protein, p53, through structure-function analysis. The authors found that HepTH1-5 is stably bound to ferroportin, compared to Hepc25, by triggering the ferroportin internalisation via Lys42 and Lys270 ubiquitination, in a similar manner to the Hepc25 activity. Moreover, the residues Ile24 and Gly24, along with copper and zinc ligands, interacted with similar residues, Lys24 and Asp1 of Hepc25, respectively, showing that those molecules are crucial to the hepcidin replacement strategy. HepTH1-5 interacts with p53 and activates its function through phosphorylation. This finding shows that HepTH1-5 might be involved in the apoptosis signalling pathway upon a DNA damage response. This study will be very helpful for understanding the mechanism of the hepcidin replacement and providing insights into the HepTH1-5 peptide as a new target for hepcidin and cancer therapeutics.Communicated by Ramaswamy H. Sarma.

Molybdenum-Induced Apoptosis of Splenocytes and Thymocytes and Changes of Peripheral Blood in Sheep

To investigate the effects of molybdenum (Mo) on apoptosis of lymphocytes and changes of peripheral blood in sheep, a total of 20 5-month-old healthy female sheep were randomly divided into five groups of 4 and orally administered with water containing Na₂MoO₄·2H₂O (0, 5, 10, 20, and 50 mg/kg BW/day) for 28 days. Jugular vein blood was taken on the 0th, 7th, 14th, 21st, and 28th day of Mo treatment, respectively. On the 28th day, the spleen and thymus were removed for observing histopathology and apoptosis-related DNA damage by hematoxylin and eosin (HE) staining and TdT‑mediated dUTP Nick-End Labeling (TUNEL) staining, respectively. The blood routine indexes were determined by an automatic blood analyzer. Further, the apoptosis of lymphocytes and changes in mitochondrial membrane potential (MMP) of peripheral blood were analyzed by flow cytometry. Results showed that excessive Mo induced apoptosis-related DNA damage in the splenocytes and thymocytes and significantly increased the apoptosis indexes of the splenocytes and thymocytes (P < 0.01). Furthermore, the treatment with excessive Mo significantly decreased the MMP (P < 0.01) and promoted apoptosis in peripheral blood lymphocytes (P < 0.01). And the number of WBC, Lymph, Gran, and RBC and the indexes of HGB and HCT were also significantly decreased (P < 0.05 or P < 0.01), while RDW was significantly increased by excessive Mo (P < 0.05 or P < 0.01). In conclusion, excessive Mo-induced DNA damage and apoptosis of the lymphocytes changed the RBC-related indexes of the peripheral blood in sheep.

Mitochondrial ferritin expression in human macrophages is facilitated by thrombin-mediated cleavage under hypoxia

Ferritins are iron storage proteins, which maintain cellular iron homeostasis. Among these proteins, the ferritin heavy chain is well characterized, but the regulatory principles of mitochondrial ferritin (FTMT) remain elusive. FTMT appears to be cleaved from a 27 kDa to a 22 kDa form. In human macrophages, FTMT increased under hypoxia in a hypoxia-inducible factor 2-dependent manner. Occurrence of FTMT resulted from cleavage by thrombin, which was supplied by serum. Inhibition of thrombin as well as serum removal decreased FTMT, while supplementation of thrombin under serum-deprived conditions restored its expression. Besides hypoxia, thrombin facilitated FTMT expression after treatment with the ferroptosis inducer RSL3 and the pro-inflammatory stimulus lipopolysaccharide. This study provides insights into the regulation of FTMT under hypoxia and identifies thrombin as a FTMT maturation-associated peptidase.

Comparison of apical and basolateral Cu treatment for iron-related gene regulation during deferoxamine induced iron deficiency

BACKGROUND

Intestinal copper transporter (Atp7a) mutant-brindled mice with systemic Cu deficiency had elevated Cu levels in enterocyte cells without any perturbation of iron-regulating genes, suggesting that blood Cu level might be important for intestinal iron homeostasis during iron deficiency (ID). We hypothesized that the blood Cu level and polarization (apical and basolateral) of enterocyte cells might be important regulators for the compensatory response on the regulation of genes in enterocyte cells during iron deficiency.

METHODS

We grew Caco-2 cells on a bicameral cell culture plate to mimic the human intestine system and on a regular tissue culture plate. Iron deficiency was induced by deferoxamine (DFO). The cells were treated with Cu and Cu with Fe following mRNA expressions of DMT1, FPN, TFR, and ANKRD37 were analyzed.

RESULTS

Our main finding was that basolateral treatment of Cu significantly reduced mRNA expressions of iron-regulated genes, including DMT1, FPN, TFR, and ANKRD37, compared to DFO-treated and DFO with apical Cu-treated groups in both bicameral and regular tissue culture plates.

CONCLUSIONS

Cu level in the basolateral side of Caco-2 cells significantly influenced the intracellular gene regulation in DFO-induced iron-deficient condition, and polarization of the cells might be important factor gene regulation in enterocyte cells.

Copper deficiency, a rare but correctable cause of pancytopenia: a review of literature

INTRODUCTION

Copper is increasingly being recognized as a vital mineral required by both animals and humans. It plays a vital role in many metabolic processes such as cellular respiration, iron oxidation, and hemoglobin synthesis. Copper deficiency, which can be hereditary or acquired, can lead to a wide spectrum of disease processes such as ringed sideroblastic anemia, myelodysplasia, and pancytopenia. Timely identification and management of copper deficiency is necessary to prevent irreversible complications.

AREAS COVERED

Our study focuses on prevalence, etiology, pathophysiology, complications, and treatment of copper deficiency.

EXPERT OPINION

Copper deficiency is frequently underrecognized as the cause of anemia, neutropenia, and bone marrow dysplasia. As it is potentially treatable, it should always be kept in the differentials when patients present with neurological and hematological abnormalities.

Relationship between Down-Regulation of Copper-Related Genes and Decreased Ferroportin Protein Level in the Duodenum of Iron-Deficient Piglets

In mammals, 2 × 10¹² red blood cells (RBCs) are produced every day in the bone marrow to ensure a constant supply of iron to maintain effective erythropoiesis. Impaired iron absorption in the duodenum and inefficient iron reutilization from senescent RBCs by macrophages contribute to the development of anemia. Ferroportin (Fpn), the only known cellular iron exporter, as well as hephaestin (Heph) and ceruloplasmin, two copper-dependent ferroxidases involved in the above-mentioned processes, are key elements of the interaction between copper and iron metabolisms. Crosslinks between these metals have been known for many years, but metabolic effects of one on the other have not been elucidated to date. Neonatal iron deficiency anemia in piglets provides an interesting model for studying this interplay. In duodenal enterocytes of young anemic piglets, we identified iron deposits and demonstrated increased expression of ferritin with a concomitant decline in both Fpn and Heph expression. We postulated that the underlying mechanism involves changes in copper distribution within enterocytes as a result of decreased expression of the copper transporter—Atp7b. Obtained results strongly suggest that regulation of iron absorption within enterocytes is based on the interaction between proteins of copper and iron metabolisms and outcompetes systemic regulation.

Clinical Manifestations of Copper Deficiency: A Case Report and Review of the Literature

BACKGROUND

Copper is a mineral that is absorbed in the stomach, duodenum, and jejunum. Gastric bypass surgery, gastrectomy, and short-bowel syndrome commonly lead to copper malabsorption. Copper deficiency primarily presents with hematological and neurological sequelae, including macrocytic anemia and myelopathy. Although hematological disturbances often correct with copper supplementation, neurological manifestations of copper deficiency may be irreversible. We present the case of copper deficiency secondary to malabsorption and management strategies to prevent irreversible neurological sequelae.

PRESENTATION

A 48-year-old female with a history of hypothyroidism, ischemic stroke, and Crohn's disease, complicated by subtotal colectomy and small-bowel resections, was admitted for fatigue and progressive neurological deficiencies. Her vital signs were stable, and physical examination was remarkable for weakness of both upper and lower extremities, ataxia, and upper extremities paresthesia. Computed tomography scan of the head without contrast was unremarkable. Magnetic resonance imaging enterography revealed a focal area of narrowing of the remaining small bowel. Copper level was low at 39 µg/dL. After 5 days of intravenous replacement using trace element within parenteral nutrition, her copper level corrected to 81 µg/dL. Her ataxia improved after intravenous copper supplementation and did not recur.

CONCLUSIONS

Our patient presented with copper deficiency secondary to malabsoprtion. This case highlights the importance of copper testing in the bariatric surgery population and in patients with short-bowel syndrome. Given the irreversible nature of neurological symptoms when compared with the expense of nutrition supplements, routine copper testing should be considered in patients with malabsorptive states or altered anatomy, regardless of initial presentation.

Fish-Based Baby Food Concern-From Species Authentication to Exposure Risk Assessment

In this work, two different but complementary approaches were used to evaluate the reliability of fish-based baby foods as a source of safe nourishment for babies. More specifically, barcoding analysis based on the Cytochrome Oxidase I sequences was used for fish species authentication and an analysis of metal/metalloid levels was performed to estimate the exposure risk assessment derived from consumption of selected fish-based baby food in infants and toddlers. COI DNA barcoding revealed that in three samples the species detected did not match the common name of the species shown on the label. In particular, G. chalcogrammus and M. australis were found in place of M. merluccius and O. mykiss was found in place of S. salar. The analysis of exposure risk assessment indicated a low risk for developing chronic systemic and carcinogenic effects in infants and toddler, under an exposure scenario based on daily consumption of a single box of fish-based baby food. However, it is important to highlight that in order to provide a comprehensive risk assessment it would be important to supplement the levels of exposure resulting from the total diet. Overall, our results suggest that more attention should be paid by authorities to ensure the safety of food for infants and toddlers.

Coumarin-Based Dual Chemosensor for Colorimetric and Fluorescent Detection of Cu2+ in Water Media

A novel coumarin derivative (5) was synthesized and used as a colorimetric and fluorescent probe for selective detection of Cu²⁺ ions in the presence of other metal ions, with the detection limits of 5.7 and 4.0 ppb, respectively. Cu²⁺ ion reacts with probe 5 to form a 1:1 stoichiometry complex, resulting in a remarkable redshift of absorption maximum from 460 to 510 nm, as well as almost completely quenching fluorescence intensity of probe 5 at the wavelength of 536 nm. These changes can be distinctly observed by naked eyes. In addition, the working pH range of probe 5 is wide and suitable for physiological conditions, thus probe 5 may be used for detection of Cu²⁺ ions in living cells. The stable structures of probe 5 and its 1:1 complex with Cu²⁺ ion were optimized at the PBE0/6-31+G(d) level of theory. The presence and characteristics of bonds in compounds were studied through atoms in a molecule and natural bond orbital analysis. The formation of the complex led to a strong transfer of electron density from probe 5 as a ligand to Cu²⁺ ion, resulting in breaking the π-electron conjugated system, which is the cause of fluorescence quenching and color change of 5-Cu²⁺ complex.

Pharmacological treatment of eating disorders, comorbid mental health problems, malnutrition and physical health consequences

The pharmacological treatment of patients with an eating disorder (ED) often includes medications to treat their ED, comorbid mental health problems, malnutrition and the physical health problems resulting from it. The currently approved pharmacological treatment options for EDs are limited to fluoxetine for bulimia nervosa (BN) and - in some countries - lisdexamfetamine for binge eating disorder (BED). Thus, there are no approved pharmacological options for anorexia nervosa (AN), even though study results for olanzapine and dronabinol are promising. Topiramate might be an additional future option for the treatment of BN and BED. Selective serotonin reuptake inhibitors (SSRI), mirtazapine and bupropion could be considered for the treatment of comorbid unipolar depression. However, AN and BN are contraindications for bupropion. For ED patients with a manic episode, we recommend olanzapine in AN and risperidone in BN and BED; whereas for bipolar depression, olanzapine (plus fluoxetine) seems appropriate in AN and lamotrigine in BN and BED. Acute anxiety or suicidality may warrant benzodiazepine treatment with lorazepam. Proton-pump inhibitors, gastroprokinetic drugs, laxatives and hormones can alleviate certain physical health problems caused by EDs. Therapeutic drug monitoring, pharmacogenomic testing, a more restrictive use of "pro re nata" (PRN) medication, an interdisciplinary treatment approach, shared decision making (SDM) and the formulation of common treatment goals by the patients, their family or carers and clinicians could improve treatment success and safety. Novel genetic, immunological, microbiome and brain imaging research as well as new pharmacological developments like the use of psychedelics, stimulants, novel monoaminergic drugs, hormone analogues and drugs which enhance the effects of psychotherapy may extend our therapeutic options in the near future.

Hypoxia inhibits ferritinophagy, increases mitochondrial ferritin, and protects from ferroptosis

Cellular iron, at the physiological level, is essential to maintain several metabolic pathways, while an excess of free iron may cause oxidative damage and/or provoke cell death. Consequently, iron homeostasis has to be tightly controlled. Under hypoxia these regulatory mechanisms for human macrophages are not well understood. Hypoxic primary human macrophages reduced intracellular free iron and increased ferritin expression, including mitochondrial ferritin (FTMT), to store iron. In parallel, nuclear receptor coactivator 4 (NCOA4), a master regulator of ferritinophagy, decreased and was proven to directly regulate FTMT expression. Reduced NCOA4 expression resulted from a lower rate of hypoxic NCOA4 transcription combined with a micro RNA 6862-5p-dependent degradation of NCOA4 mRNA, the latter being regulated by c-jun N-terminal kinase (JNK). Pharmacological inhibition of JNK under hypoxia increased NCOA4 and prevented FTMT induction. FTMT and ferritin heavy chain (FTH) cooperated to protect macrophages from RSL-3-induced ferroptosis under hypoxia as this form of cell death is linked to iron metabolism. In contrast, in HT1080 fibrosarcome cells, which are sensitive to ferroptosis, NCOA4 and FTMT are not regulated. Our study helps to understand mechanisms of hypoxic FTMT regulation and to link ferritinophagy and macrophage sensitivity to ferroptosis.

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Hypoxia decreases NCOA4 transcription in primary human macrophages.

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NCOA4 mRNA is a target of miR-6862-5p.

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Lowering NCOA4 increases FTMT abundance under hypoxia.

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FTMT and FTH protect from ferroptosis.

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Tumor cells lack the hypoxic decrease of NCOA4 and fail to stabilize FTMT.

Effects of a Cumulative, Suboptimal Supply of Multiple Trace Elements in Mice: Trace Element Status, Genomic Stability, Inflammation, and Epigenetics

SCOPE

Trace element (TE) deficiencies often occur accumulated, as nutritional intake is inadequate for several TEs, concurrently. Therefore, the impact of a suboptimal supply of iron, zinc, copper, iodine, and selenium on the TE status, health parameters, epigenetics, and genomic stability in mice are studied.

METHODS AND RESULTS

Male mice receive reduced or adequate amounts of TEs for 9 weeks. The TE status is analyzed mass-spectrometrically in serum and different tissues. Furthermore, gene and protein expression of TE biomarkers are assessed with focus on liver. Iron concentrations are most sensitive toward a reduced supply indicated by increased serum transferrin levels and altered hepatic expression of iron-related genes. Reduced TE supply results in smaller weight gain but higher spleen and heart weights. Additionally, inflammatory mediators in serum and liver are increased together with hepatic genomic instability. However, global DNA (hydroxy)methylation is unaffected by the TE modulation.

CONCLUSION

Despite homeostatic regulation of most TEs in response to a low intake, this condition still has substantial effects on health parameters. It appears that the liver and immune system react particularly sensitive toward changes in TE intake. The reduced Fe status might be the primary driver for the observed effects.

Copper affects steroidogenesis and viability of human adrenocortical carcinoma (NCI-H295R) cell line in vitro

Copper is an environmental risk factor, which has various effects on reproductive endocrinology. In this study human adrenocortical carcinoma (NCI-H295R) cell line was used as an in vitro biological model to study the effect of copper sulfate (CuSO₄.5H₂O) on steroidogenesis and cytotoxicity. The cell cultures were exposed to different concentrations (3.90, 62.50, 250, 500, 1000 µM) of CuSO₄.5H₂O and compared to control group (medium without CuSO₄.5H₂O). Cell viability was measured by the metabolic activity assay. Quantification of sexual steroid production directly from the medium was performed by ELISA assay. Following 48 h culture of NCI-H295R cell line in the presence of CuSO₄.5H₂O a dose-dependent depletion of progesterone release was observed even at the lower concentrations of CuSO₄.5H₂O. The lowest levels of progesterone were detected in groups with the higher doses (≥ 250 µM) of CuSO₄.5H₂O, which elicited significant cytotoxic action. Testosterone production decreased significantly, and this decline was more prominent in comparison to that of progesterone. The lowest release of testosterone was recorded at 1000 µM of CuSO₄.5H₂O. The cytotoxic effect of CuSO₄.5H₂O was evident at all concentrations used in the study. The presented data suggest that copper has detrimental effects on sexual steroid hormones and consecutively on reproductive physiology.

Copper deficiency-induced anemia is caused by a mitochondrial metabolic reprograming in erythropoietic cells

The lack of copper has been associated with anemia, myelodysplastic syndromes and leukemia as well as with a loss in complex IV activity and an enlarged mitochondrial morphology. Mitochondria play a key role during the differentiation of hematopoietic stem cells by regulating the passage from a glycolytic to oxidative metabolism. The former is associated with cell proliferation and the latter with cell differentiation. Oxidative metabolism, which occurs inside mitochondria, is sustained by the respiratory chain, where complex IV is copper-dependent. We have hypothesized that a copper deficiency induces a mitochondrial metabolic reprogramming, favoring cell expansion over cell differentiation in erythropoiesis. Erythroid progression analysis of the bone marrow of mice fed with a copper deficient diet and of the in vitro erythropoiesis of human CD34+ cells treated with a bathocuproine - a copper chelator - showed a major expansion of progenitor cells and a decreased differentiation. Under copper deficiency, mitochondria switched to a higher membrane potential, lower oxygen consumption rate and lower ROS levels as compared with control cells. In addition, mitochondrial biomass was increased and an up-regulation of the mitochondrial fusion protein mitofusin 2 was observed. Most copper-deficient phenotypes were mimicked by the pharmacological inhibition of complex IV with azide. We concluded that copper deficiency induced a mitochondrial metabolic reprogramming, making hematopoietic stem cells favor progenitor cell expansion over cell differentiation.

All You Can Feed: Some Comments on Production of Mouse Diets Used in Biomedical Research with Special Emphasis on Non-Alcoholic Fatty Liver Disease Research

The laboratory mouse is the most common used mammalian research model in biomedical research. Usually these animals are maintained in germ-free, gnotobiotic, or specific-pathogen-free facilities. In these facilities, skilled staff takes care of the animals and scientists usually don’t pay much attention about the formulation and quality of diets the animals receive during normal breeding and keeping. However, mice have specific nutritional requirements that must be met to guarantee their potential to grow, reproduce and to respond to pathogens or diverse environmental stress situations evoked by handling and experimental interventions. Nowadays, mouse diets for research purposes are commercially manufactured in an industrial process, in which the safety of food products is addressed through the analysis and control of all biological and chemical materials used for the different diet formulations. Similar to human food, mouse diets must be prepared under good sanitary conditions and truthfully labeled to provide information of all ingredients. This is mandatory to guarantee reproducibility of animal studies. In this review, we summarize some information on mice research diets and general aspects of mouse nutrition including nutrient requirements of mice, leading manufacturers of diets, origin of nutrient compounds, and processing of feedstuffs for mice including dietary coloring, autoclaving and irradiation. Furthermore, we provide some critical views on the potential pitfalls that might result from faulty comparisons of grain-based diets with purified diets in the research data production resulting from confounding nutritional factors.

Animal Models of Normal and Disturbed Iron and Copper Metabolism

Research on the interplay between iron and copper metabolism in humans began to flourish in the mid-20th century, and diseases associated with dysregulated homeostasis of these essential trace minerals are common even today. Iron deficiency is the most frequent cause of anemia worldwide, leading to significant morbidity, particularly in developing countries. Iron overload is also quite common, usually being the result of genetic mutations which lead to inappropriate expression of the iron-regulatory hormone hepcidin. Perturbations of copper homeostasis in humans have also been described, including rare genetic conditions which lead to severe copper deficiency (Menkes disease) or copper overload (Wilson disease). Historically, the common laboratory rat (Rattus norvegicus) was the most frequently utilized species to model human physiology and pathophysiology. Recently, however, the development of genetic-engineering technology combined with the worldwide availability of numerous genetically homogenous (i.e., inbred) mouse strains shifted most research on iron and copper metabolism to laboratory mice. This created new opportunities to understand the function of individual genes in the context of a living animal, but thoughtful consideration of whether mice are the most appropriate models of human pathophysiology was not necessarily involved. Given this background, this review is intended to provide a guide for future research on iron- and copper-related disorders in humans. Generation of complementary experimental models in rats, swine, and other mammals is now facile given the advent of newer genetic technologies, thus providing the opportunity to accelerate the identification of pathogenic mechanisms and expedite the development of new treatments to mitigate these important human disorders.

Antiproliferative and Antitumour Effect of Nongenotoxic Silver Nanoparticles on Melanoma Models

During the last 3 decades, there has been a slow advance to obtain new treatments for malignant melanoma that improve patient survival. In this work, we present a systematic study focused on the antiproliferative and antitumour effect of AgNPs. These nanoparticles are fully characterized, are coated with polyvinylpyrrolidone (PVP), and have an average size of 35 ± 15 nm and a metallic silver content of 1.2% wt. Main changes on cell viability, induction of apoptosis and necrosis, and ROS generation were found on B16-F10 cells after six hours of exposure to AgNPs (IC50 = 4.2 μg/mL) or Cisplatin (IC50 = 2.0 μg/mL). Despite the similar response for both AgNPs and Cisplatin on antiproliferative potency (cellular viability of 53.95 ± 1.88 and 53.62 ± 1.04) and ROS production (20.27 ± 1.09% and 19.50 ± 0.35%), significantly different cell death pathways were triggered. While AgNPs induce only apoptosis (45.98 ± 1.88%), Cisplatin induces apoptosis and necrosis at the same rate (22.31 ± 1.72% and 24.07 ± 1.10%, respectively). In addition to their antiproliferative activity, in vivo experiments showed that treatments of 3, 6, and 12 mg/kg of AgNPs elicit a survival rate almost 4 times higher (P < 0.05) compared with the survival rate obtained with Cisplatin (2 mg/kg). Furthermore, the survivor mice treated with AgNPs do not show genotoxic damage determined by micronuclei frequency quantification on peripheral blood cells. These results exhibit the remarkable antitumour activity of a nongenotoxic AgNP formulation and constitute the first advance toward the application of these AgNPs for melanoma treatment, which could considerably reduce adverse effects provoked by currently applied chemotherapeutics.

Micronutrients Deficiencies in 374 Severely Malnourished Anorexia Nervosa Inpatients

Introduction: Anorexia nervosa (AN) is a complex psychiatric disorder, which can lead to specific somatic complications. Undernutrition is a major diagnostic criteria of AN which can be associated with several micronutrients deficiencies. Objectives: This study aimed to determinate the prevalence of micronutrients deficiencies and to compare the differences between the two subtypes of AN (restricting type (AN-R) and binge-eating/purging type (AN-BP)). Methods: We report a large retrospective, monocentric study of patients hospitalized in a highly specialized nutrition unit between January 2011 and August 2017 for severe malnutrition treatment in the context of anorexia nervosa. Results: Three hundred and seventy-four patients (360 (96%) women, 14 (4%) men), age: 31.3 ± 12.9 years, Body Mass Index (BMI): 12.5 ± 1.7 kg/m² were included; 253 (68%) patients had AN-R subtype while, 121 (32%) had AN-BP. Zinc had the highest deficiency prevalence 64.3%, followed by vitamin D (54.2%), copper (37.1%), selenium (20.5%), vitamin B1 (15%), vitamin B12 (4.7%), and vitamin B9 (8.9%). Patients with AN-BP type had longer disease duration, were older, and had a lower left ventricular ejection fraction (LVEF) (p < 0.001, p = 0.029, p = 0.009), when compared with AN-R type, patients who instead, had significantly higher Alanine Aminotransferase (ALT) and Brain Natriuretic Peptide (BNP) levels (p < 0.001, p < 0.021). In the AN-BP subgroup, as compared to AN-R, lower selenium (p < 0.001) and vitamin B12 plasma concentration (p < 0.036) were observed, whereas lower copper plasma concentration was observed in patients with AN-R type (p < 0.022). No significant differences were observed for zinc, vitamin B9, vitamin D, and vitamin B1 concentrations between the two types of AN patients. Conclusion: Severely malnourished AN patients have many micronutrient deficiencies. Differences between AN subtypes are identified. Micronutrients status of AN patients should be monitored and supplemented to prevent deficiencies related complications and to improve nutritional status. Prospective studies are needed to explore the symptoms and consequences of each deficiency, which can aggravate the prognosis during recovery.

Intersection of Iron and Copper Metabolism in the Mammalian Intestine and Liver

Iron and copper have similar physiochemical properties; thus, physiologically relevant interactions seem likely. Indeed, points of intersection between these two essential trace minerals have been recognized for many decades, but mechanistic details have been lacking. Investigations in recent years have revealed that copper may positively influence iron homeostasis, and also that iron may antagonize copper metabolism. For example, when body iron stores are low, copper is apparently redistributed to tissues important for regulating iron balance, including enterocytes of upper small bowel, the liver, and blood. Copper in enterocytes may positively influence iron transport, and hepatic copper may enhance biosynthesis of a circulating ferroxidase, ceruloplasmin, which potentiates iron release from stores. Moreover, many intestinal genes related to iron absorption are transactivated by a hypoxia-inducible transcription factor, hypoxia-inducible factor-2α (HIF2α), during iron deficiency. Interestingly, copper influences the DNA-binding activity of the HIF factors, thus further exemplifying how copper may modulate intestinal iron homeostasis. Copper may also alter the activity of the iron-regulatory hormone hepcidin. Furthermore, copper depletion has been noted in iron-loading disorders, such as hereditary hemochromatosis. Copper depletion may also be caused by high-dose iron supplementation, raising concerns particularly in pregnancy when iron supplementation is widely recommended. This review will cover the basic physiology of intestinal iron and copper absorption as well as the metabolism of these minerals in the liver. Also considered in detail will be current experimental work in this field, with a focus on molecular aspects of intestinal and hepatic iron-copper interplay and how this relates to various disease states. © 2018 American Physiological Society. Compr Physiol 8:1433-1461, 2018.

Disulfiram reduces metastatic osteosarcoma tumor burden in an immunocompetent Balb/c or-thotopic mouse model

Introduction

The overall survival rate of patients with osteosarcoma (OS) and pulmonary metastases has remained stagnant at 15–30% for several decades. Disulfiram (DSF) is an FDA-approved aldehyde dehydrogenase inhibitor that reduces the metastatic phenotype of OS cells in vitro. Here we evaluate its in vivo efficacy, as compared to doxorubicin chemotherapy, in a previously-validated orthotopic model of metastatic OS.

Results

All treatment groups displayed a significantly reduced quantitative OS metastatic burden compared with controls. The metastatic burden of Lo DSF-treated animals was equivalent to the DXR group. Ninety-five percent of control animals displayed evidence of metastatic disease, which was significantly greater than all treatment groups.

Discussion

Disulfiram treatment resulted in a reduced burden of OS metastatic disease compared with controls. This was statistically-equivalent to doxorubicin. No additive effect was observed between these two therapies.

Materials and Methods

One-hundred twenty immunocompetent Balb/c mice received proximal tibia paraphyseal injections of 5 × 10⁵ K7M2 murine OS cells. Therapy began three weeks after injection: saline (control), low-dose disulfiram (Lo DSF), high-dose disulfiram (Hi DSF), doxorubicin (DXR), Lo DSF + DXR, and Hi DSF + DXR. Transfemoral amputations were performed at 4 weeks. Quantitative metastatic tumor burden was measured using near-infrared indocyanine green (ICG) angiography.

Comparison of the effect of dietary copper nanoparticles and one copper (II) salt on the metabolic and immune status in a rat model

The aim of the study was to evaluate the effects of a diet containing different levels of Cu in two different chemical forms (carbonate and nanoparticles) on metabolic, immune and antioxidant status in a rat model. Five experimental treatments (8 rats in each) were used to test different dosages of Cu added to the diet (standard -6.5 mg/kg, half the standard dosage -3.25 mg/kg, and no added Cu as a negative control) and two sources of added copper (standard -CuCO₃ and copper nanoparticles -CuNPs). Blood and urine samples were collected from all the animals after four weeks of treatment. Metabolic and immune parameters were determined in blood and urine samples. The study has shown that a dietary Cu deficiency (negative control) decreases rat's plasma levels of Cu, Fe, CREAT, BIL and IL-6, whereas reducing the level of Cu from the recommended 6.5 mg/kg to 3.25 mg/kg decreases only the plasma concentration of TG, IgE and IL-6. Replacing CuCO₃ with CuNPs in rat diets affects their metabolism, as indicated by decreased Ca, CREAT, BIL, ALB and IL-6 plasma levels. To sum up, CuNP added to a diet of rats have a more beneficial effect on metabolic indices (indicative of kidney and liver function) and inhibit inflammatory processes more effectively than CuCO₃.

Intestinal calcium transport and its regulation in thalassemia: interaction between calcium and iron metabolism

Osteoporosis and derangement of calcium homeostasis are common complications of thalassemia. Despite being an important process for bone and calcium metabolism, little is known about intestinal calcium transport in thalassemia. Recent reports of decreases in both intestinal calcium transport and bone mineral density in thalassemic patients and animal models suggested that defective calcium absorption might be a cause of thalassemic bone disorder. Herein, the possible mechanisms associated with intestinal calcium malabsorption in thalassemia are discussed. This includes alterations in the calcium transporters and hormonal controls of the transcellular and paracellular intestinal transport systems in thalassemia. In addition, the effects of iron overload on intestinal calcium absorption, and the reciprocal interaction between iron and calcium transport in thalassemia are elaborated. Understanding the mechanisms underlining calcium malabsorption in thalassemia would lead to development of therapeutic agents and mineral supplements that restore calcium absorption as well as prevent osteoporosis in thalassemic patients.

Mutations in TMEM260 Cause a Pediatric Neurodevelopmental, Cardiac, and Renal Syndrome

Despite the accelerated discovery of genes associated with syndromic traits, the majority of families affected by such conditions remain undiagnosed. Here, we employed whole-exome sequencing in two unrelated consanguineous kindreds with central nervous system (CNS), cardiac, renal, and digit abnormalities. We identified homozygous truncating mutations in TMEM260, a locus predicted to encode numerous splice isoforms. Systematic expression analyses across tissues and developmental stages validated two such isoforms, which differ in the utilization of an internal exon. The mutations in both families map uniquely to the long isoform, raising the possibility of an isoform-specific disorder. Consistent with this notion, RT-PCR of lymphocyte cell lines from one of the kindreds showed reduced levels of only the long isoform, which could be ameliorated by emetine, suggesting that the mutation induces nonsense-mediated decay. Subsequent in vivo testing supported this hypothesis. First, either transient suppression or CRISPR/Cas9 genome editing of zebrafish tmem260 recapitulated key neurological phenotypes. Second, co-injection of morphants with the long human TMEM260 mRNA rescued CNS pathology, whereas the short isoform was significantly less efficient. Finally, immunocytochemical and biochemical studies showed preferential enrichment of the long TMEM260 isoform to the plasma membrane. Together, our data suggest that there is overall reduced, but not ablated, functionality of TMEM260 and that attenuation of the membrane-associated functions of this protein is a principal driver of pathology. These observations contribute to an appreciation of the roles of splice isoforms in genetic disorders and suggest that dissection of the functions of these transcripts will most likely inform pathomechanism.

The role of insufficient copper in lipid synthesis and fatty-liver disease

The essential transition metal copper is important in lipid metabolism, redox balance, iron mobilization, and many other critical processes in eukaryotic organisms. Genetic diseases where copper homeostasis is disrupted, including Menkes disease and Wilson disease, indicate the importance of copper balance to human health. The severe consequences of insufficient copper supply are illustrated by Menkes disease, caused by mutation in the X-linked ATP7A gene encoding a protein that transports copper from intestinal epithelia into the bloodstream and across the blood-brain barrier. Inadequate copper supply to the body due to poor diet quality or malabsorption can disrupt several molecular level pathways and processes. Though much of the copper distribution machinery has been described and consequences of disrupted copper handling have been characterized in human disease as well as animal models, physiological consequences of sub-optimal copper due to poor nutrition or malabsorption have not been extensively studied. Recent work indicates that insufficient copper may be important in a number of common diseases including obesity, ischemic heart disease, and metabolic syndrome. Specifically, marginal copper deficiency (CuD) has been reported as a potential etiologic factor in diseases characterized by disrupted lipid metabolism such as non-alcoholic fatty-liver disease (NAFLD). In this review, we discuss the available data suggesting that a significant portion of the North American population may consume insufficient copper, the potential mechanisms by which CuD may promote lipid biosynthesis, and the interaction between CuD and dietary fructose in the etiology of NAFLD. © 2016 IUBMB Life, 69(4):263-270, 2017.

Trace Mineral Micronutrients and Chronic Periodontitis-a Review

Trace mineral micronutrients are imperative for optimum host response. Populations worldwide are prone to their insufficiency owing to lifestyle changes or poor nutritional intake. Balanced levels of trace minerals like iron (Fe), zinc (Zn), selenium (Se) and copper (Cu) are essential to prevent progression of chronic conditions like periodontitis. Their excess as well as deficiency is detrimental to periodontal health. This is specifically true in relation to Fe. Furthermore, some trace elements, e.g. Se, Zn and Cu are integral components of antioxidant enzymes and prevent reactive oxygen species induced destruction of tissues. Their deficiency can worsen periodontitis associated with systemic conditions like diabetes mellitus. With this background, the present review first focusses on the role of four trace minerals, namely, Fe, Zn, Se and Cu in periodontal health followed by an appraisal of the data from case control studies related to their association with chronic periodontitis.

Copper therapy reduces intravascular hemolysis and derepresses ferroportin in mice with mosaic mutation (Atp7amo-ms): An implication for copper-mediated regulation of the Slc40a1 gene expression

Mosaic mutant mice displaying functional dysfunction of Atp7a copper transporter (the Menkes ATPase) are an established animal model of Menkes disease and constitute a convenient tool for investigating connections between copper and iron metabolisms. This model allows to explore changes in iron metabolism in suckling mutant mice suffering from systemic copper deficiency as well as in young and adult ones undergone copper therapy, which reduces lethal effect of the Atp7a gene mutation. Our recent study demonstrated that 14-day-old mosaic mutant males display blood cell abnormalities associated with intravascular hemolysis, and show disturbances in the functioning of the hepcidin-ferroportin regulatory axis, which controls systemic iron homeostasis. We thus aimed to check whether copper supplementation recovers mutants from hemolytic insult and rebalance systemic iron regulation. Copper supplementation of 14-day-old mosaic mutants resulted in the reestablishment of hematological status, attenuation of hepicidin and concomitant induction of the iron exporter ferroportin/Slc40a1 expression in the liver, down-regulated in untreated mutants. Interestingly, treatment of wild-type males with copper, induced hepcidin-independent up-regulation of ferroportin protein level in hepatic macrophages in both young and adult (6-month-old) animals. Stimulatory effect of copper on ferroportin mRNA and protein levels was confirmed in bone marrow-derived macrophages isolated from both wild-type and mosaic mutant males. Our study indicates that copper is an important player in the regulation of the Slc40a1 gene expression.

Effects of Different Levels of Molybdenum on Rumen Microbiota and Trace Elements Changes in Tissues from Goats

Molybdenum (Mo) is an essential trace element for animals and human beings. However, the negative effects on rumen function and distribution of trace elements in tissues induced by excessive Mo have not been well understood. Therefore, the purpose of present study was to investigate the impact of Mo on rumen microbiota, distribution of trace elements in various organs, and hematological parameters of goats. A total of 36 goats were randomly distributed into three groups with equal number and low-Mo and high-Mo groups were orally administered ammonium molybdate at 15 and 45 mg · Mo · kg^-1 · BW respectively, while the control group received corresponding quantitative deionized water. The results showed that the total number of ciliate and protozoa protein concentration decreased significantly (P < 0.01) on days 25 and 50. Concentrations of ammonia nitrogen and bacterial protein were significantly higher (P < 0.05) in low-Mo group, while they were lower (P < 0.05) in high-Mo group than the control group on days 25 and 50. In addition, Mo accumulated in serum and all detected tissues. Copper (Cu) and zinc (Zn) contents significantly decreased (P < 0.05) in hair and serum on days 25 and 50, while Cu contents increased (P < 0.05) and the change of Zn contents were not obvious (P > 0.05) in other tissues on days 25 and 50. Besides, there was no obvious variation in iron (Fe) contents during whole experiment period (P > 0.05). Furthermore, excessive Mo content had no significant effect on red blood cell (RBC) counts and hemoglobin (HGB) concentration (P > 0.05) on days 25 and 50, while white blood cell (WBC) counts increased significantly (P < 0.05) on day 50. These results indicated that excessive Mo content could impact the balance of ruminal microorganisms and interfere with the absorption and distribution of Mo and Cu mainly.

High-Iron Consumption Impairs Growth and Causes Copper-Deficiency Anemia in Weanling Sprague-Dawley Rats

Iron-copper interactions were described decades ago; however, molecular mechanisms linking the two essential minerals remain largely undefined. Investigations in humans and other mammals noted that copper levels increase in the intestinal mucosa, liver and blood during iron deficiency, tissues all important for iron homeostasis. The current study was undertaken to test the hypothesis that dietary copper influences iron homeostasis during iron deficiency and iron overload. We thus fed weanling, male Sprague-Dawley rats (n = 6-11/group) AIN-93G-based diets containing high (~8800 ppm), adequate (~80) or low (~11) iron in combination with high (~183), adequate (~8) or low (~0.9) copper for 5 weeks. Subsequently, the iron- and copper-related phenotype of the rats was assessed. Rats fed the low-iron diets grew slower than controls, with changes in dietary copper not further influencing growth. Unexpectedly, however, high-iron (HFe) feeding also impaired growth. Furthermore, consumption of the HFe diet caused cardiac hypertrophy, anemia, low serum and tissue copper levels and decreased circulating ceruloplasmin activity. Intriguingly, these physiologic perturbations were prevented by adding extra copper to the HFe diet. Furthermore, higher copper levels in the HFe diet increased serum nonheme iron concentration and transferrin saturation, exacerbated hepatic nonheme iron loading and attenuated splenic nonheme iron accumulation. Moreover, serum erythropoietin levels, and splenic erythroferrone and hepatic hepcidin mRNA levels were altered by the dietary treatments in unanticipated ways, providing insight into how iron and copper influence expression of these hormones. We conclude that high-iron feeding of weanling rats causes systemic copper deficiency, and further, that copper influences the iron-overload phenotype.

Fermented Goat's Milk Consumption Improves Duodenal Expression of Iron Homeostasis Genes during Anemia Recovery

Despite the crucial roles of duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferritin light chain (Ftl1), ferroportin 1 (FPN1), transferrin receptor 1 (TfR1), and hepcidin antimicrobial peptide (Hamp) in Fe metabolism, no studies have investigated the modulations of these genes during Fe repletion with fermented milks. Analysis included Fe status markers and gene and protein expression in enterocytes of control and anemic animals fed fermented milks. Fermented goat's milk up-regulated enterocyte Dcytb, DMT1, FPN1, and Ftl1 and down-regulated TfR1 and Hamp gene expression in control and anemic animals. Anemia decreased Dcytb, DMT1, and Ftl1 in animals fed fermented cow's milk and up-regulated TfR1 and Hamp expression. Fe overload down-regulated Dcytb and TfR1 in animals fed fermented cow's milk and up-regulated DMT1 and FPN1 gene expression. Fermented goat's milk increased expression of duodenal Dcytb, DMT1, and FPN1 and decreased Hamp and TfR1, improving Fe metabolism during anemia recovery.

Copper-doped mesoporous silica nanospheres, a promising immunomodulatory agent for inducing osteogenesis

The application of mesoporous silica nanospheres (MSNs) loaded with drugs/growth factors to induce osteogenic differentiation of stem cells has been trialed by a number of researchers recently. However, limitations such as high cost, complex fabrication and unintended side effects from supraphysiological concentrations of the drugs/growth factors represent major obstacles to any potential clinical application in the near term. In this study we reported an in situ one-pot synthesis strategy of MSNs doped with hypoxia-inducing copper ions and systematically evaluated the nanospheres by in vitro biological assessments. The Cu-containing mesoporous silica nanospheres (Cu-MSNs) had uniform spherical morphology (∼100nm), ordered mesoporous channels (∼2nm) and homogeneous Cu distribution. Cu-MSNs demonstrated sustained release of both silicon (Si) and Cu ions and controlled degradability. The Cu-MSNs were phagocytized by immune cells and appeared to modulate a favorable immune environment by initiating proper pro-inflammatory cytokines, inducing osteogenic/angiogenic factors and suppressing osteoclastogenic factors by the immune cells. The immune microenvironment induced by the Cu-MSNs led to robust osteogenic differentiation of bone mesenchymal stem cells (BMSCs) via the activation of Oncostation M (OSM) pathway. These results suggest that the novel Cu-MSNs could be used as an immunomodulatory agent with osteostimulatory capacity for bone regeneration/therapy application.

STATEMENT OF SIGNIFICANCE

In order to stimulate both osteogenesis and angiogenesis of stem cells for further bone regeneration, a new kind of hypoxia-inducing copper doped mesoporous silica nanospheres (Cu-MSNs) were prepared via one-pot synthesis. Biological assessments under immune environment which better reflect the in vivo response revealed that the nanospheres possessed osteostimulatory capacity and had potential as immunomodulatory agent for bone regeneration/therapy application. The strategy of introducing controllable amount of therapeutic ions instead of loading expensive drugs/growth factors in mesoporous silica nanosphere provides new options for bioactive nanomaterial functionalization.

Fetal and neonatal iron deficiency but not copper deficiency increases vascular complexity in the developing rat brain

OBJECTIVES

Anemia caused by nutritional deficiencies, such as iron and copper deficiencies, is a global health problem. Iron and copper deficiencies have their most profound effect on the developing fetus/infant, leading to brain development deficits and poor cognitive outcomes. Tissue iron depletion or chronic anemia can induce cellular hypoxic signaling. In mice, chronic hypoxia induces a compensatory increase in brain blood vessel outgrowth. We hypothesized that developmental anemia, due to iron or copper deficiencies, induces angiogenesis/vasculogenesis in the neonatal brain.

METHODS

To test our hypothesis, three independent experiments were performed where pregnant rats were fed iron- or copper-deficient diets from gestational day 2 through mid-lactation. Effects on the neonatal brain vasculature were determined using quantitative real-time polymerase chain reaction to assess mRNA levels of angiogenesis/vasculogenesis-associated genes and GLUT1 immunohistochemistry to assess brain blood vessel density and complexity.

RESULTS

Iron deficiency, but not copper deficiency, increased mRNA expression of brain endothelial cell- and angiogenesis/vasculogenesis-associated genes (i.e. Glut1, Vwf, Vegfa, Ang2, Cxcl12, and Flk1) in the neonatal brain, suggesting increased cerebrovascular density. Iron deficiency also increased hippocampal and cerebral cortical blood vessel branching by 62 and 78%, respectively.

DISCUSSION

This study demonstrates increased blood vessel complexity in the neonatal iron-deficient brain, which is likely due to elevated angiogenic/vasculogenic signaling. At least initially, this is probably an adaptive response to maintain metabolic substrate homeostasis in the developing iron-deficient brain. However, this may also contribute to long-term neurodevelopmental deficits.

Duodenal cytochrome b (DCYTB) in iron metabolism: an update on function and regulation

Iron and ascorbate are vital cellular constituents in mammalian systems. The bulk-requirement for iron is during erythropoiesis leading to the generation of hemoglobin-containing erythrocytes. Additionally, both iron and ascorbate are required as co-factors in numerous metabolic reactions. Iron homeostasis is controlled at the level of uptake, rather than excretion. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance non-heme iron absorption in the gut, ascorbate regulates iron homeostasis. The involvement of ascorbate in dietary iron absorption extends beyond the direct chemical reduction of non-heme iron by dietary ascorbate. Among other activities, intra-enterocyte ascorbate appears to be involved in the provision of electrons to a family of trans-membrane redox enzymes, namely those of the cytochrome b₅₆₁ class. These hemoproteins oxidize a pool of ascorbate on one side of the membrane in order to reduce an electron acceptor (e.g., non-heme iron) on the opposite side of the membrane. One member of this family, duodenal cytochrome b (DCYTB), may play an important role in ascorbate-dependent reduction of non-heme iron in the gut prior to uptake by ferrous-iron transporters. This review discusses the emerging relationship between cellular iron homeostasis, the emergent “IRP1-HIF2α axis”, DCYTB and ascorbate in relation to iron metabolism.

Haemolysis and perturbations in the systemic iron metabolism of suckling, copper-deficient mosaic mutant mice - an animal model of Menkes disease

The biological interaction between copper and iron is best exemplified by the decreased activity of multicopper ferroxidases under conditions of copper deficiency that limits the availability of iron for erythropoiesis. However, little is known about how copper deficiency affects iron homeostasis through alteration of the activity of other copper-containing proteins, not directly connected with iron metabolism, such as superoxide dismutase 1 (SOD1). This antioxidant enzyme scavenges the superoxide anion, a reactive oxygen species contributing to the toxicity of iron via the Fenton reaction. Here, we analyzed changes in the systemic iron metabolism using an animal model of Menkes disease: copper-deficient mosaic mutant mice with dysfunction of the ATP7A copper transporter. We found that the erythrocytes of these mutants are copper-deficient, display decreased SOD1 activity/expression and have cell membrane abnormalities. In consequence, the mosaic mice show evidence of haemolysis accompanied by haptoglobin-dependent elimination of haemoglobin (Hb) from the circulation, as well as the induction of haem oxygenase 1 (HO1) in the liver and kidney. Moreover, the hepcidin-ferroportin regulatory axis is strongly affected in mosaic mice. These findings indicate that haemolysis is an additional pathogenic factor in a mouse model of Menkes diseases and provides evidence of a new indirect connection between copper deficiency and iron metabolism.

Obesity as an emerging risk factor for iron deficiency

Iron homeostasis is affected by obesity and obesity-related insulin resistance in a many-facetted fashion. On one hand, iron deficiency and anemia are frequent findings in subjects with progressed stages of obesity. This phenomenon has been well studied in obese adolescents, women and subjects undergoing bariatric surgery. On the other hand, hyperferritinemia with normal or mildly elevated transferrin saturation is observed in approximately one-third of patients with metabolic syndrome (MetS) or nonalcoholic fatty liver disease (NAFLD). This constellation has been named the “dysmetabolic iron overload syndrome (DIOS)”. Both elevated body iron stores and iron deficiency are detrimental to health and to the course of obesity-related conditions. Iron deficiency and anemia may impair mitochondrial and cellular energy homeostasis and further increase inactivity and fatigue of obese subjects. Obesity-associated inflammation is tightly linked to iron deficiency and involves impaired duodenal iron absorption associated with low expression of duodenal ferroportin (FPN) along with elevated hepcidin concentrations. This review summarizes the current understanding of the dysregulation of iron homeostasis in obesity.

Mechanistic and regulatory aspects of intestinal iron absorption

Iron is an essential trace mineral that plays a number of important physiological roles in humans, including oxygen transport, energy metabolism, and neurotransmitter synthesis. Iron absorption by the proximal small bowel is a critical checkpoint in the maintenance of whole-body iron levels since, unlike most other essential nutrients, no regulated excretory systems exist for iron in humans. Maintaining proper iron levels is critical to avoid the adverse physiological consequences of either low or high tissue iron concentrations, as commonly occurs in iron-deficiency anemia and hereditary hemochromatosis, respectively. Exquisite regulatory mechanisms have thus evolved to modulate how much iron is acquired from the diet. Systemic sensing of iron levels is accomplished by a network of molecules that regulate transcription of the HAMP gene in hepatocytes, thus modulating levels of the serum-borne, iron-regulatory hormone hepcidin. Hepcidin decreases intestinal iron absorption by binding to the iron exporter ferroportin 1 on the basolateral surface of duodenal enterocytes, causing its internalization and degradation. Mucosal regulation of iron transport also occurs during low-iron states, via transcriptional (by hypoxia-inducible factor 2α) and posttranscriptional (by the iron-sensing iron-regulatory protein/iron-responsive element system) mechanisms. Recent studies demonstrated that these regulatory loops function in tandem to control expression or activity of key modulators of iron homeostasis. In health, body iron levels are maintained at appropriate levels; however, in several inherited disorders and in other pathophysiological states, iron sensing is perturbed and intestinal iron absorption is dysregulated. The iron-related phenotypes of these diseases exemplify the necessity of precisely regulating iron absorption to meet body demands.

Molecular mediators governing iron-copper interactions

Given their similar physiochemical properties, it is a logical postulate that iron and copper metabolism are intertwined. Indeed, iron-copper interactions were first documented over a century ago, but the homeostatic effects of one on the other has not been elucidated at a molecular level to date. Recent experimental work has, however, begun to provide mechanistic insight into how copper influences iron metabolism. During iron deficiency, elevated copper levels are observed in the intestinal mucosa, liver, and blood. Copper accumulation and/or redistribution within enterocytes may influence iron transport, and high hepatic copper may enhance biosynthesis of a circulating ferroxidase, which potentiates iron release from stores. Moreover, emerging evidence has documented direct effects of copper on the expression and activity of the iron-regulatory hormone hepcidin. This review summarizes current experimental work in this field, with a focus on molecular aspects of iron-copper interplay and how these interactions relate to various disease states.

Curcumin may impair iron status when fed to mice for six months

Curcumin has been shown to have many potentially health beneficial properties in vitro and in animal models with clinical studies on the toxicity of curcumin reporting no major side effects. However, curcumin may chelate dietary trace elements and could thus potentially exert adverse effects. Here, we investigated the effects of a 6 month dietary supplementation with 0.2% curcumin on iron, zinc, and copper status in C57BL/6J mice. Compared to non-supplemented control mice, we observed a significant reduction in iron, but not zinc and copper stores, in the liver and the spleen, as well as strongly suppressed liver hepcidin and ferritin expression in the curcumin-supplemented mice. The expression of the iron-importing transport proteins divalent metal transporter 1 and transferrin receptor 1 was induced, while hepatic and splenic inflammatory markers were not affected in the curcumin-fed mice. The mRNA expression of other putative target genes of curcumin, including the nuclear factor (erythroid-derived 2)-like 2 and haem oxygenase 1 did not differ between the groups. Most of the published animal trials with curcumin-feeding have not reported adverse effects on iron status or the spleen. However, it is possible that long-term curcumin supplementation and a Western-type diet may aggravate iron deficiency. Therefore, our findings show that further studies are needed to evaluate the effect of curcumin supplementation on iron status.

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0.2% dietary curcumin for 6 months reduced iron stores in murine liver and spleen.

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Curcumin chelated iron but not zinc and copper in vivo.

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Liver hepcidin and ferritin expression was strongly suppressed in curcumin-fed mice.

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Curcumin induced expression of hepatic iron transporters DMT1 and TfR1.

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Curcumin did not affect hepatic and splenic inflammatory and oxidative markers.

The gut in iron homeostasis: role of HIF-2 under normal and pathological conditions

Although earlier, seminal studies demonstrated that the gut per se has the intrinsic ability to regulate the rates of iron absorption, the spotlight in the past decade has been placed on the systemic regulation of iron homeostasis by the hepatic hormone hepcidin and the molecular mechanisms that regulate its expression. Recently, however, attention has returned to the gut based on the finding that hypoxia inducible factor-2 (HIF-2α) regulates the expression of key genes that contribute to iron absorption. Here we review the current understanding of the molecular mechanisms that regulate iron homeostasis in the gut by focusing on the role of HIF-2 under physiological steady-state conditions and in the pathogenesis of iron-related diseases. We also discuss implications for adapting HIF-2-based therapeutic strategies in iron-related pathological conditions.