Regulation of iron metabolism by hepcidin

The role of iron in obesity and diabetes

Iron is an essential trace metal for all life, but excess iron causes oxidative stress through catalyzing the toxic hydroxy-radical production via the Fenton reaction. The number of patients with obesity and diabetes has been increasing worldwide, and their onset and development are affected by diet. In both clinical and experimental studies, a high body iron content was associated with obesity and diabetes, and the reduction of body iron content to an appropriate level can ameliorate the status and development of obesity and diabetes. Macrophages play an essential role in the pathophysiology of obesity and diabetes, and in the metabolism and homeostasis of iron in the body. Recent studies demonstrated that macrophage polarization is related to adipocyte hypertrophy and insulin resistance through their capabilities of iron handling. Control of iron in macrophages is a potential therapeutic strategy for obesity and diabetes. J. Med. Invest. 69 : 1-7, February, 2022.

Iron serum levels and iron homeostasis parameters in patients with nosocomial pneumonia treated with cefiderocol: post hoc analysis of the APEKS-NP study

Critically ill patients often present with low serum iron levels or anemia. We evaluated the impact of iron levels and iron homeostasis on the efficacy and safety of cefiderocol, an iron-chelator siderophore cephalosporin, in patients with nosocomial pneumonia in a post hoc analysis of the randomized, double-blind, Phase 3 APEKS-NP study (NCT03032380). Patients with Gram-negative nosocomial pneumonia received cefiderocol 2 g, 3-h infusion, q8h, or high-dose, extended-infusion meropenem 2 g, 3-h infusion, q8h, for 7-14 days. Efficacy and safety parameters, including specific iron homeostasis parameters (i.e., hepcidin, iron, total iron binding capacity, transferrin saturation), were analyzed according to baseline iron levels. In the cefiderocol and meropenem arms, 79.1% (117/148) and 83.3% (125/150) randomized patients, respectively, had low baseline serum iron levels. Rates of 14-day (12.3% [14/114] vs 11.6% [14/121]) and 28-day all-cause mortality (20.5% [23/112] vs 19.0% [23/121]), clinical cure (63.2% [72/114] vs 67.2% [82/122]), and microbiological eradication (43.6% [41/94] vs 48.1% [51/106]) at test of cure were similar in cefiderocol vs meropenem arms, respectively. In the overall safety population, rates of anemia-related adverse events were similar (cefiderocol arm 18.2% [27/148], meropenem arm 18.7% [28/150]). Changes from baseline to test of cure in hepcidin, iron, total iron binding capacity, and transferrin saturation were similar between treatment arms. Cefiderocol treatment did not affect iron homeostasis, and its efficacy and safety were not influenced by baseline serum iron levels. Clinicaltrials.gov registration: NCT03032380. Date of registration: 26 January 2017.

Signaling Integration of Hydrogen Sulfide and Iron on Cellular Functions

Significance: Hydrogen sulfide (H₂S) is an endogenous signaling molecule, regulating numerous physiological functions from vasorelaxation to neuromodulation. Iron is a well-known bioactive metal ion, being the central component of hemoglobin for oxygen transportation and participating in biomolecule degradation, redox balance, and enzymatic actions. The interplay between H₂S and iron metabolisms and functions impacts significantly on the fate and wellness of different types of cells. Recent Advances: Iron level in vivo affects the production of H₂S via nonenzymatic reactions. On the contrary, H₂S quenches excessive iron inside the cells and regulates the redox status of iron. Critical Issues: Abnormal metabolisms of both iron and H₂S are associated with various conditions and diseases such as iron overload, anemia, oxidative stress, and cardiovascular and neurodegenerative diseases. The molecular mechanisms for the interactions between H₂S and iron are unsettled yet. Here we review signaling links of the production, metabolism, and their respective and integrative functions of H₂S and iron in normalcy and diseases. Future Directions: Physiological and pathophysiological importance of H₂S and iron as well as their therapeutic applications should be evaluated jointly, not separately. Future investigation should expand from iron-rich cells and tissues to the others, in which H₂S and iron interaction has not received due attention. Antioxid. Redox Signal. 36, 275-293.

Role of Hepcidin in Anemia of Chronic Disease in Rheumatoid Arthritis

Objective Anemia of chronic disease is a frequent consequence in rheumatoid arthritis and is associated with major clinical and patient outcomes. The present cross-sectional study explored the role of hepcidin (HEP) in anemia of chronic disease in rheumatoid arthritis by studying its relationships with markers of anemia, iron metabolism, inflammation, and erythropoiesis. Methods Blood samples from anemic ( n = 43) and nonanemic ( n = 43) rheumatoid arthritis patients were analyzed for markers of anemia (hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red cells distribution width, and reticulocyte hemoglobin), iron metabolism (iron, total iron binding capacity, ferritin, transferrin saturation, soluble transferrin receptor), inflammation (erythrocyte sedimentation rate, C-reactive protein, and interleukin 6), and erythropoiesis (erythropoietin and HEP). Correlation analysis was used to identify relationships between HEP and all other variables. Principal component analysis was used to identify common underlying dimensions representing linear combinations of all variables. Results HEP had statistically significant mostly moderate-to-large correlations with markers of anemia (0.30-0.70, all p < 0.01), small correlation with markers of iron metabolism and markers of inflammation ( r = 0.20-0.40, all p < 0.01), and moderate correlations with markers of erythropoiesis. Principal component analysis revealed two underlying components (factors) capturing approximately 50% of total variability. Factor 1 comprised mainly of markers of anemia, iron metabolism, and erythropoiesis and was related to "erythrocyte health status," while factor 2 comprised mainly markers of inflammation and iron metabolism and was related to "acute phase reactants." HEP was the only variable demonstrating substantial loadings on both factors. Conclusions HEP is related to markers of anemia, iron metabolism, inflammation, and erythropoiesis. In addition, when all variables are "reduced" to a minimum number of two "latent" factors, HEP is loaded on both, thus underlying its pivotal role in the complex interaction of the erythropoietic response in inflammation-induced anemia and/or functional iron deficiency.

Hypoxia-Inducible Factor Stabilizers in End Stage Kidney Disease: "Can the Promise Be Kept?"

Anemia is a common complication of chronic kidney disease (CKD). The prevalence of anemia in CKD strongly increases as the estimated Glomerular Filtration Rate (eGFR) decreases. The pathophysiology of anemia in CKD is complex. The main causes are erythropoietin (EPO) deficiency and functional iron deficiency (FID). The administration of injectable preparations of recombinant erythropoiesis-stimulating agents (ESAs), especially epoetin and darbepoetin, coupled with oral or intravenous(iv) iron supplementation, is the current treatment for anemia in CKD for both dialysis and non-dialysis patients. This approach reduces patients’ dependence on transfusion, ensuring the achievement of optimal hemoglobin target levels. However, there is still no evidence that treating anemia with ESAs can significantly reduce the risk of cardiovascular events. Meanwhile, iv iron supplementation causes an increased risk of allergic reactions, gastrointestinal side effects, infection, and cardiovascular events. Currently, there are no studies defining the best strategy for using ESAs to minimize possible risks. One class of agents under evaluation, known as prolyl hydroxylase inhibitors (PHIs), acts to stabilize hypoxia-inducible factor (HIF) by inhibiting prolyl hydroxylase (PH) enzymes. Several randomized controlled trials showed that HIF-PHIs are almost comparable to ESAs. In the era of personalized medicine, it is possible to envisage and investigate specific contexts of the application of HIF stabilizers based on the individual risk profile and mechanism of action.

Child, caretaker, and community: Testing predictors of anemia and response to iron supplementation in Peruvian preschool-aged children

OBJECTIVES

Despite repeated governmental and nongovernmental interventions, anemia remains a widespread public health concern in Peru. This article examines nutritional and disease factors associated with the prevalence of anemia and response to iron supplementation in Peruvian children, with the aim of understanding the lack of success of national programs.

METHODS

Data come from children, aged 2-5 years (n = 102), living in peri-urban Lima. Predictors of anemia and response to iron supplementation were explored at the individual, maternal, household, and environmental levels using logistic regression models, adjusted for clustering by household.

RESULTS

Half of the children in this sample were anemic and 50% of the anemic children responded to iron supplementation. We identified several factors that were associated with child anemia status and response to iron supplementation. Lower weight-for-age z-scores and the winter season were strong predictors of child anemia status and nonresponse to iron supplementation. Living with paternal grandparents was protective against anemia and elevated C-reactive protein at the time of the final interview was associated with a lack of response to iron supplementation.

CONCLUSIONS

The findings of this study document an association between children's anemia status and their nutritional and ecological environment, highlighting the importance of examining anemia within a specific context to better understand the factors driving this important health problem.

The Era of Antimicrobial Peptides: Use of Hepcidins to Prevent or Treat Bacterial Infections and Iron Disorders

The current treatments applied in aquaculture to limit disease dissemination are mostly based on the use of antibiotics, either as prophylactic or therapeutic agents, with vaccines being available for a limited number of fish species and pathogens. Antimicrobial peptides are considered as promising novel substances to be used in aquaculture, due to their antimicrobial and immunomodulatory activities. Hepcidin, the major iron metabolism regulator, is found as a single gene in most mammals, but in certain fish species, including the European sea bass (Dicentrarchus labrax), two different hepcidin types are found, with specialized roles: the single type 1 hepcidin is involved in iron homeostasis trough the regulation of ferroportin, the only known iron exporter; and the various type 2 hepcidins present antimicrobial activity against a number of different pathogens. In this study, we tested the administration of sea bass derived hepcidins in models of infection and iron overload. Administration with hamp2 substantially reduced fish mortalities and bacterial loads, presenting itself as a viable alternative to the use of antibiotics. On the other hand, hamp1 seems to attenuate the effects of iron overload. Further studies are necessary to test the potential protective effects of hamp2 against other pathogens, as well as to understand how hamp2 stimulate the inflammatory responses, leading to an increased fish survival upon infection.

Factors Affecting Doses of Roxadustat Versus Darbepoetin Alfa for Anemia in Nondialysis Patients

INTRODUCTION

Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor for treating anemia of chronic kidney disease (CKD). This post hoc analysis of a Japanese, open-label, partially randomized, phase 3 study in nondialysis-dependent (NDD) CKD patients treated with traditional erythropoiesis-stimulating agents (ESAs) evaluated dosing trends of roxadustat and darbepoetin alfa (DA) required to maintain target hemoglobin concentrations in patients with risk factors associated with ESA hyporesponsiveness.

METHODS

Patients enrolled in the 1517-CL-0310 study (NCT02988973) that demonstrated noninferiority of roxadustat to DA for change in average hemoglobin levels of week 18-24 from baseline who had used human recombinant erythropoietin or DA before conversion and who were randomized to either roxadustat or DA were included. The endpoints were the average allocated dose of roxadustat and DA per administration in the last 6 weeks (AAD/6W), assessed by subgroups known to be associated with ESA hyporesponsiveness. The analysis of variance was performed by the treatment group to test the influence of subgroup factors on the AAD/6W of study drug. The ratios between the mean AAD/6W in each subgroup category and the within-arm mean AAD/6W were calculated.

RESULTS

Two hundred and sixty-two patients were randomized to either the roxadustat or DA comparative group and received treatment (roxadustat, n = 131; DA, n = 131). Higher mean (standard deviation) doses of both roxadustat (63.15 [24.84] mg) and DA (47.33 [29.79] μg) were required in the highest ESA resistance index (≥6.8) quartile (p = 0.003 and p < 0.001, respectively). Patients with adequate iron repletion had the lowest doses for both roxadustat (45.54 [18.01] mg) and DA (28.13 [20.98] μg). High-sensitivity C-reactive protein ≥28.57 nmol/L and the estimated glomerular filtration rate <15 mL/min/1.73 m2 were associated with requiring higher DA but not roxadustat doses.

DISCUSSION/CONCLUSION

The roxadustat dose required to maintain target hemoglobin in NDD patients in Japan with anemia of CKD relative to DA dose may not be impacted by low-grade inflammation. Roxadustat may be beneficial for ESA-hyporesponsive NDD CKD patients.

Assessment of baseline rates of functional and absolute iron deficiency in bariatric surgery candidates: a retrospective study

BACKGROUND

Preoperative optimization of iron status is a priority in candidates for bariatric surgery. Inflammation is strongly associated with obesity, and as a consequence, functional iron deficiency (ID) is potentially an underreported issue in surgical candidates.

OBJECTIVES

In light of updated practice guidelines, to retrospectively review preoperative iron status in an Irish cohort of bariatric surgery candidates, taking account of the relative incidence rate of functional ID.

SETTING

A tertiary care obesity service with bariatric surgery referral in Ireland.

METHODS

Baseline nutritional biochemistry records were reviewed between February 2017 and February 2020 in a hospital, Dublin, Ireland. Absolute ID was defined as serum ferritin <30 μg/L; functional ID was defined as ferritin, 30 to 100 μg/L, in the presence of C-reactive protein >5 mg/L. Anemia was indexed with reference to hemoglobin and qualified by vitamin B12 and folate status to rule out anemia unrelated to primary ID.

RESULTS

The analysis included 120 patients, 68% female, 49.6 ± 9.3 years, and body mass index, 52.0 ± 9.6 kg/m². The prevalence of absolute and functional ID was 11.7% and 30.8%, respectively (P = .0003). Anemia was associated with absolute ID and functional ID in 14.3% and 10.8% of patients (P = .29). Folate and vitamin B12 deficiency occurred in <5% of patients.

CONCLUSION

In patients seeking bariatric surgery for severe obesity, the prevalence of baseline functional ID is substantial and can be associated with anemia. These findings raise queries with regard to how best to optimize preoperative iron status in the context of ongoing inflammation.

Iron distribution in different tissues of homozygous Mask (msk/msk) mice and the effects of oral iron treatments

Iron-refractory iron deficiency anemia (IRIDA) is an autosomal recessive disorder caused by genetic mutations on TMPRSS6 gene which encodes Matriptase2 (MT2). An altered MT2 cannot appropriately suppress hepatic BMP6/SMAD signaling in case of low iron, hence hepcidin excess blocks dietary iron absorption, leading to a form of anemia resistant to oral iron supplementation. In this study, using the IRIDA mouse model Mask, we characterized homozygous (msk/msk) compared to asymptomatic heterozygous (msk/wt) mice, assessing the major parameters of iron status in different organs, at different ages in both sexes. The effect of carbonyl iron diet was analyzed as control iron supplementation being used for many studies in mice. It resulted effective in both anemic control and msk/msk mice, as expected, even if there is no information about its mechanism of absorption. Then, we mainly compared two forms of oral iron supplement, largely used for humans: ferrous sulfate and Sucrosomial iron. In anemic control mice, the two oral formulations corrected hemoglobin levels from 11.40 ± 0.60 to 15.38 ± 1.71 g/dl in 2-4 weeks. Interestingly, in msk/msk mice, ferrous sulfate did not increase hemoglobin likely due to ferroportin/hepcidin-dependent absorption, whereas Sucrosomial iron increased it from 11.50 ± 0.60 to 13.53 ± 0.64 g/dl mainly in the first week followed by a minor increase at 4 weeks with a stable level of 13.30 ± 0.80 g/dl, probably because of alternative absorption. Thus, Sucrosomial iron, already used in other conditions of iron deficiency, may represent a promising option for oral iron supplementation in IRIDA patients.

Integrated analysis of lncRNA and mRNA in liver of Megalobrama amblycephala post Aeromonas hydrophila infection

Background

As non-coding RNA molecules of more than 200 bp in length, long non-coding RNAs (lncRNAs) play a variety of roles in biological processes, including regulating the immune responses to bacterial infections. In recent years, there have been many in-depth studies on mammalian lncRNAs, but the relevant studies in fish are very limited. Meanwhile, since lncRNAs are not conserved among species, it is difficult to apply the existing results directly to unstudied species.

Results

To obtain the information of lncRNAs in Megalobrama amblycephala, one of the most economically important freshwater fish in China, also to better understand the biological significance of lncRNAs in the immunity system, the fish liver at 0, 4, 12, 24, and 72 h post Aeromonas hydrophila infection (hpi) were obtained for lncRNA-sequencing (lncRNA-seq). A total of 14,849 lncRNAs were identified, and 2196 lncRNAs showed significant differences at different time points post A. hydrophila infection. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the target genes of the differentially expressed lncRNAs were enriched in several pathways related to immune such as apoptosis, inflammation, and immune response. Time-specific modules were then identified, using weighted correlation network analysis (WGCNA), and 28 modules significantly correlated with different time point after infection were found. Furthermore, four immune-related genes and six lncRNAs in the time-specific modules were subsequently verified by RT-qPCR.

Conclusions

The above findings reveal the discovery of widespread differentially expressed lncRNAs in the M. amblycephala liver post A. hydrophila infection, suggesting that lncRNAs might participate in the regulation of host response to bacterial infection, enriching the information of lncRNAs in teleost and providing a resources basis for further studies on the immune function of lncRNAs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07969-5.

Therapeutic Response Assessment of High-Grade Gliomas During Early-Phase Drug Development in the Era of Molecular and Immunotherapies

ABSTRACT

Several new therapeutic strategies have emerged over the past decades to address unmet clinical needs in high-grade gliomas, including targeted molecular agents and various forms of immunotherapy. Each of these strategies requires addressing fundamental questions, depending on the stage of drug development, including ensuring drug penetration into the brain, engagement of the drug with the desired target, biologic effects downstream from the target including metabolic and/or physiologic changes, and identifying evidence of clinical activity that could be expanded upon to increase the likelihood of a meaningful survival benefit. The current review article highlights these strategies and outlines how imaging technology can be used for therapeutic response evaluation in both targeted and immunotherapies in early phases of drug development in high-grade gliomas.

Adiposity and pathogen exposure: An investigation of response to iron supplementation and hypothesized predictors in anemic pre-school-aged children living in a dual burden environment

OBJECTIVES

Peruvians are experiencing rapid dietary and lifestyle changes, resulting in a phenomenon known as the "dual burden of disease." A common manifestation of the dual burden in individuals is the co-occurrence of overweight and anemia. Despite recent initiatives introduced to address these concerns, rates continue to be public health concerns. This study investigates the relationship between immune activation and lack of response to iron supplementation after 1 month of treatment and explores variation in body fat stores as a potential moderator between immune function and response to treatment.

METHODS

Data come from children, aged 2-5 years (n = 50) from a peri-urban community in Lima, Peru. Multivariate logistic regression models were used to explore the associations between response to treatment (Hb > =11.0 g/dl) after 1 month of treatment), markers of immune activation (C-reactive protein [CRP] and reported morbidity symptoms), and measures of body fat (waist-to-height ratio, triceps skinfold thickness, and body mass index [BMI]).

RESULTS

We found that high CRP is associated with a lack of response to iron supplementation after 1 month of treatment and that BMI z-score may moderate this association. Generally, larger body size is associated with response to iron supplementation whether or not the children in this sample have high immune activation. However, the probability of anemic children responding to iron supplementation treatment differed across adiposity measures.

CONCLUSIONS

Our finding suggesting that adiposity and CRP influence response to iron supplementation, furthers our understanding of the relationship between inflammation and anemia treatment in children and has both theoretical and public health implications.

Prevalence of Iron Deficiency and its Sociodemographic Patterning in Indian Children and Adolescents: Findings from the Comprehensive National Nutrition Survey 2016-18

BACKGROUND

Anemia control programs in India focus mainly on the measurement of hemoglobin in response to iron-folic acid supplementation. However, representative national estimates of iron deficiency (ID) are not available.

OBJECTIVES

The objective of the present study was to evaluate ID prevalence among children and adolescents (1-19 y) using nationally representative data and to examine the sociodemographic patterning of ID.

METHODS

Cross-sectional data from the Comprehensive National Nutrition Survey in children (1-4 y: n = 9635; 5-9 y: n = 11,938) and adolescents (10-19 y; n = 11,507) on serum ferritin (SF) and other biomarkers were analyzed to determine inflammation-adjusted ID prevalence [SF (μg/L): <12 in 1-4 y and <15 in 5-19 y] and its relation to sociodemographic indicators. Multiple-regression analyses were conducted to identify the exposure associations of iron status. In addition, the relation between SF and hemoglobin was assessed as an indicator of iron utilization in different wealth quintiles.

RESULTS

ID prevalence was higher in 1- to 4-y-old children (31.9%; 95% CI: 31.0%, 32.8%) and adolescent girls (30.4%; 95% CI: 29.3%, 31.5%) but lower in adolescent boys and 5- to 9-y-old children (11%-15%). In all age groups, ID prevalence was higher in urban than in rural participants (1-4 y: 41% compared with 29%) and in those from richer quintiles (1-4 y: 44% in richest compared with 22% in poorest), despite adjustment for relevant confounders. SF significantly interacted with the wealth index, with declining trends in the strength of association between hemoglobin and SF from the richest to the poorest groups suggesting impaired iron utilization for hemoglobin synthesis in poorer wealth quintiles.

CONCLUSIONS

ID prevalence was indicative of moderate (in preschool children and adolescent girls) or mild (in 5- to 9-y-old children and adolescent boys) public health problem with significant variation by state and age. Focusing on increasing iron intake alone, without addressing the multiple environmental constraints related to poverty, may not result in intended benefits.

Hepcidin Protects Yellow Catfish (Pelteobagrus fulvidraco) against Aeromonas veronii-Induced Ascites Disease by Regulating Iron Metabolism

Aeromonas veronii (A. veronii) is one of the main pathogens causing bacterial diseases in aquaculture. Although previous studies have shown that hepcidin as an antimicrobial peptide can promote fish resistance to pathogenic bacterial infections, but the mechanisms remain unclear. Here, we expressed and purified recombinant yellow catfish (Pelteobagrus fulvidraco) hepcidin protein (rPfHep). rPfHep can up-regulate the expression of ferritin and enhance the antibacterial activity in primary hepatocytes of yellow catfish. We employed berberine hydrochloride (BBR) and Fursultiamine (FSL) as agonists and antagonists for hepcidin, respectively. The results indicated that agonist BBR can inhibit the proliferation of pathogenic bacteria, and the antagonist FSL shows the opposite effect. After gavage administration, rPfHep and the agonist BBR can enhance the accumulation of iron in liver, which may hinder the iron transport and limit the amount of iron available to pathogenic bacteria. Moreover, rPfHep and the agonist BBR can also reduce the mortality rate, bacterial load and histological lesions in yellow catfish infected with A. veronii. Therefore, hepcidin is an important mediator of iron metabolism, and it can be used as a candidate target for prevent bacterial infections in yellow catfish. Hepcidin and BBR have potential application value in preventing anti-bacterial infection.

Distinct iron homeostasis in C57BL/6 and Balb/c mouse strains

C57BL/6 (BL6) and Balb/c mice exhibit prototypical Th1- and Th2-dominant immune predispositions, respectively. Iron is a proinflammatory metal ion; however, limited information is documented on the differences in iron homeostasis between BL6 and Balb/c strains. The objective of this study was to investigate the extent to which strain-level differences in these mice dictates the regulation of iron homeostasis during physiologic and inflammatory conditions. At basal levels, Balb/c mice displayed significantly higher levels of iron in systemic circulation and tissue compared to BL6 mice. Moreover, Balb/c mice had greater iron absorption as indicated by higher gene expressions of duodenal DcytB, DMT1, Fpn, SFT, and Heph. Similarly, hepatic Tf, TfR1, TfR2, and DMT1 expressions were augmented in Balb/c mice. Interestingly, there was no change in hepatic Hamp expression between the two strains, suggesting that the disparity in their maintenance of iron is independent of hepcidin. Additionally, the basal levels of intracellular labile iron pool in Balb/c intestinal epithelial cells, and bone marrow-derived macrophages and neutrophils, were higher compared to BL6 mice. When mice were challenged with lipopolysaccharide, the acute inflammatory response in BL6 mice was more pronounced than in Balb/c mice, as indicated by the more rapid development of hypoferremia and upregulation of serum IL-6 and TNF-α levels in BL6 mice. In conclusion, this study underscores that iron homeostasis is distinct between BL6 and Balb/c strains under both physiologic and inflammatory conditions.

Ironing Out the Details: How Iron Orchestrates Macrophage Polarization

Iron fine-tunes innate immune responses, including macrophage inflammation. In this review, we summarize the current understanding about the iron in dictating macrophage polarization. Mechanistically, iron orchestrates macrophage polarization through several aspects, including cellular signaling, cellular metabolism, and epigenetic regulation. Therefore, iron modulates the development and progression of multiple macrophage-associated diseases, such as cancer, atherosclerosis, and liver diseases. Collectively, this review highlights the crucial role of iron for macrophage polarization, and indicates the potential application of iron supplementation as an adjuvant therapy in different inflammatory disorders relative to the balance of macrophage polarization.

Impact of baseline serum ferritin and supplemental iron on altitude-induced hemoglobin mass response in elite athletes

The present study explored the impact of pre-altitude serum (s)-ferritin and iron supplementation on changes in hemoglobin mass (ΔHbmass) following altitude training. Measures of Hbmass and s-ferritin from 107 altitude sojourns (9-28 days at 1800-2500 m) with world-class endurance athletes (males n = 41, females n = 25) were analyzed together with iron supplementation and self-reported illness. Altitude sojourns with a hypoxic dose [median (range)] of 1169 (912) km·h increased Hbmass (mean ± SD) 36 ± 38 g (3.7 ± 3.7%, p < 0.001) and decreased s-ferritin -11 (190) µg·L^-1 (p = 0.001). Iron supplements [27 (191) mg·day^-1 ] were used at 45 sojourns (42%), while only 11 sojourns (10%) were commenced with s-ferritin <35 µg/L. Hbmass increased by 4.6 ± 3.7%, 3.4 ± 3.3%, 4.2 ± 4.3%, and 2.9 ± 3.4% with pre-altitude s-ferritin ≤35 µg·L^-1 , 36-50 µg·L^-1 , 51-100 µg·L^-1 , and >100 µg·L^-1 , respectively, with no group difference (p = 0.400). Hbmass increased by 4.1 ± 3.9%, 3.0 ± 3.0% and 3.7 ± 4.7% without, ≤50 mg·day^-1 or >50 mg·day^-1 supplemental iron, respectively (p = 0.399). Linear mixed model analysis revealed no interaction between pre-altitude s-ferritin and iron supplementation on ΔHbmass (p = 0.906). However, each 100 km·h increase in hypoxic dose augmented ΔHbmass by an additional 0.4% (95% CI: 0.1-0.7%; p = 0.012), while each 1 g·kg^-1 higher pre-altitude Hbmass reduced ΔHbmass by -1% (-1.6 to -0.5; p < 0.001), and illness lowered ΔHbmass by -5.7% (-8.3 to -3.1%; p < 0.001). In conclusion, pre-altitude s-ferritin or iron supplementation were not related to the altitude-induced increase in Hbmass (3.7%) in world-class endurance athletes with clinically normal iron stores.

Chimeric Protein IPath® with Chelating Activity Improves Atlantic Salmon's Immunity against Infectious Diseases

Infection processes displayed by pathogens require the acquisition of essential inorganic nutrients and trace elements from the host to survive and proliferate. Without a doubt, iron is a crucial trace metal for all living organisms and also a pivotal component in the host–parasite interactions. In particular, the host reduces the iron available to face the infectious disease, increasing iron transport proteins’ expression and activating the heme synthesis and degradation pathways. Moreover, recent findings have suggested that iron metabolism modulation in fish promotes the immune response by reducing cellular iron toxicity. We hypothesized that recombinant proteins related to iron metabolism could modulate the fish’s immune system through iron metabolism and iron-responsive genes. Here a chimeric iron transport protein (IPath^®) was bioinformatically designed and then expressed in a recombinant bacterial system. The IPath^® protein showed a significant chelating activity under in vitro conditions and biological activity. Taking this evidence, a vaccine candidate based on IPath^® was evaluated in Atlantic salmon challenged with three different fish pathogens. Experimental trials were conducted using two fish groups: one immunized with IPath^® and another injected with adjutant as the control group. After 400 accumulated thermal units (ATUs), two different infection trials were performed. In the first one, fish were infected with the bacterium Aeromonas salmonicida, and in a second trial, fish were exposed to the ectoparasite Caligus rogercresseyi and subsequently infected with the intracellular bacterium Piscirickettsia salmonis. Fish immunized with IPath^® showed a significant delay in the mortality curve in response to A. salmonicida and P. salmonis infections. However, no significant differences between infected and control fish groups were observed at the end of the experiment. Notably, sea lice burden reduction was observed in vaccinated Atlantic salmon. Transcriptional analysis evidenced a high modulation of iron-homeostasis-related genes in fish vaccinated with IPath^® compared to the control group during the infection. Moreover, increasing expression of Atlantic salmon IgT was associated with IPath^® immunization. This study provides evidence that the IPath^® protein could be used as an antigen or booster in commercial fish vaccines, improving the immune response against relevant pathogens for salmon aquaculture.

Hepcidin-induced reduction in iron content and PGC-1β expression negatively regulates osteoclast differentiation to play a protective role in postmenopausal osteoporosis

As a necessary trace element, iron is involved in many physiological processes. Clinical and basic studies have found that disturbances in iron metabolism, especially iron overload, might lead to bone loss and even be involved in postmenopausal osteoporosis. Hepcidin is a key regulator of iron homeostasis. However, the exact role of hepcidin in bone metabolism and the underlying mechanism remain unknown. In this study, we found that in postmenopausal osteoporosis cohort, the concentration of hepcidin in the serum was significantly reduced and positively correlated with bone mineral density. Ovariectomized (OVX) mice were then used to construct an osteoporosis model. Hepcidin overexpression in these mice significantly improved bone mass and rescued the phenotype of bone loss. Additionally, overexpression of hepcidin in OVX mice greatly reduced the number and differentiation of osteoclasts in vivo and in vitro. This study found that overexpression of hepcidin significantly inhibited ROS production, mitochondrial biogenesis, and PGC-1β expression. These data showed that hepcidin protected osteoporosis by reducing iron levels in bone tissue, and in conjunction with PGC-1β, reduced ROS production and the number of mitochondria, thus inhibiting osteoclast differentiation and bone absorption. Hepcidin could provide new targets for the clinical treatment of postmenopausal osteoporosis.

Hepcidin Upregulation in Lung Cancer: A Potential Therapeutic Target Associated With Immune Infiltration

Lung cancer has the highest death rate among cancers globally. Hepcidin is a fascinating regulator of iron metabolism; however, the prognostic value of hepcidin and its correlation with immune cell infiltration in lung cancer remain unclear. Here, we comprehensively clarified the prognostic value and potential function of hepcidin in lung cancer. Hepcidin expression was significantly increased in lung cancer. High hepcidin expression was associated with sex, age, metastasis, and pathological stage and significantly predicted an unfavorable prognosis in lung cancer patients. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) results suggested that hepcidin is involved in the immune response. Furthermore, hepcidin expression was positively correlated with the infiltration levels of immune cells and the expression of diverse immune cell marker sets. Importantly, hepcidin may affect prognosis partially by regulating immune infiltration in lung cancer patients. Hepcidin may serve as a candidate prognostic biomarker for determining prognosis associated with immune infiltration in lung cancer.

Hepatocyte growth factor protects PC12 cells against OGD/R-induced injury by reducing iron

In the light of hepatocyte growth factor (HGF) the inhibiting role on the expression of hepcidin, we hypothesized that HGF might be able to reduce cell and tissue iron by increasing ferroportin 1 (Fpn1) content and Fpn1-mediated iron release from cells and tissues. The hypothesized ability of HGF to reduce iron might be one of the mechanisms associated with its neuroprotective action under the conditions of ischemia/reperfusion (I/R). Here, we investigated the effects of HGF on the expression of hepcidin as well as transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), Fpn1, ferritin and iron regulatory proteins (IRPs) in oxygen-glucose deprivation and reoxygenation (OGD/R)-treated PC12 cells by real-time PCR and Western blot analysis. We demonstrated that HGF could completely reverse the OGD/R-induced reduction in Fpn1 and IRP1 expression and increase in ferritin light chain protein and hepcidin mRNA levels in PC12 cells. It was concluded that HGF protects PC12 cells against OGD/R-induced injury mainly by reducing cell iron contents via the up-regulation of Fpn1 and increased Fpn1-mediated iron export from cells. Our findings suggested that HGF may also be able to ameliorate OGD/R or I/R-induced overloading of brain iron by promoting Fpn1 expression.

Iron Protein Succinylate in the Management of Iron Deficiency Anemia: A Comparative Study with Ferrous Sulphate at Low and High Therapeutic Doses

Oral iron supplementation constitutes the first line treatment for iron deficiency anemia (IDA), with daily doses between 80 mg and 200 mg of elemental iron. Ferrous salts, such as ferrous sulphate (FeSO4), while efficacious, frequently give rise to gastrointestinal side effects. In the present paper we attempted to directly compare the efficacy of an alternative to the FeSO4 formulation, which presents a better tolerability profile, iron protein succinylate (Ferplex®). In a diet-induced anemia model, rats were treated by oral gavage with vehicle, FeSO4, or Ferplex® at a human-dose equivalent of 80 mg and 200 mg of elemental iron. We evaluated the change in anemia-related hematological and biochemical parameters, conducting a histological examination of the intestine at sacrifice. Results indicate that both types of iron supplementation are equally effective in the treatment of IDA, restoring hemoglobin, hematocrit, erythrocytes, free iron and transferrin levels in 15 days, with no statistical differences between treated groups and control. The impact of anemia on body weight was also attenuated following treatment with both iron supplements. Thrombocyte and reticulocyte levels, altered by the anemic condition, returned to homeostasis after 15 days of either FeSO4 or Ferplex® treatment. Importantly, the lower and higher doses of iron were equally effective, thus supporting the current school of thought which states that lower therapeutic doses are sufficient for management of IDA. In addition, the study shows for the first time that oral treatment with Ferplex® does not increase serum hepcidin. Finally, Ferplex® induced minimal iron depositions in the intestinal tissue compared to FeSO4.

The protective effect of the cardiac thioredoxin system on the heart in the case of iron overload in mice

BACKGROUND

Iron, which is essential for many vital biological processes, causes significant clinical pathologies in the case of its deficiency or excess. Cardiovascular protective pathways are activated by iron therapy. However, determining the appropriate iron concentration is essential to protect heart tissue from iron-induced oxidative stress. The thioredoxin system is one of the antioxidant systems that protect cells against oxidative stress. Moreover, it allows the binding of many transcription factors for apoptosis, myocardial protection, the stimulation of cell proliferation, and angiogenesis processes, especially the regulation of the cardiovascular system. This study's goal was to understand how iron overload affects the gene and protein levels of the thioredoxin system in the mouse heart.

METHODS

BALB/c mice were randomly separated into two groups. The iron overload group was administered with intraperitoneal injections of an iron-dextran solution twice a week for three weeks. In parallel, the control group was intraperitoneally given Dextran 5 solution. The total iron content, the total GSH level, the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, and thioredoxin reductase 1 (TXNRD1) activity were demonstrated spectroscopically. Changes in the iron metabolism marker genes and thioredoxin system genes were examined by qPCR. The quantitative protein expression of TXNRD1 and thioredoxin-interacting protein (TXNIP) was examined by western blotting.

RESULTS

The iron content of the heart increased in the iron overload group. The expression of hepcidin (Hamp) and ferroportin (Fpn) increased with iron overload. However, decreased expression was observed for ferritin (Fth). No changes were revealed in the GSH level and GSH/GSSG ratio. The gene expression of thioredoxin 1 (Txn1), Txnrd1, and Txnip did not change. TXNRD1 activity and protein expression increased significantly, while the protein expression of TXNIP decreased significantly.

CONCLUSION

In the case of iron overload, the cardiac thioredoxin system is affected by the protein level rather than the gene level. The amount and duration of iron overload used in this study may be considered as a starting point for further studies to determine appropriate conditions for the iron therapy of cardiovascular diseases.

Hepcidin attenuates the iron-mediated secondary neuronal injury after intracerebral hemorrhage in rats

Iron plays a key role in secondary neuronal injury after intracerebral hemorrhage (ICH), and hepcidin is able to reduce brain iron in iron-overloaded rats by down-regulating iron transport proteins including ferroportin 1 and transferrin receptor 1. These led us to hypothesize that hepcidin might reduce iron-mediated neurotoxicity by inhibiting iron accumulation in ICH brain. Here, we examined effects of Ad-hepcidin (hepcidin expression adenovirus) on the nonheme iron contents, expression of hepcidin, ferritin and iron transport proteins, neuronal cell survival, water contents in the brain and/or cerebrospinal fluid (CSF), and ICH-induced apoptosis, neurological deficit by RT-PCR, Western blot analysis, NeuN Immunofluorescence, TUNEL, Fluoro-Jade B staining, behavioral performance and Morris water-maze tests in 510 rats. We demonstrated that hepcidin could significantly suppress the ICH-induced increase in iron and ferritin in brain tissues and CSF by inhibiting expression of iron transport proteins, increase neuronal survival by attenuating ICH-induced apoptosis, reactive oxygen species, neurodegeneration and brain edema, as well as effectively improve ICH-induced behavioral and cognitive deficit in rats. The findings collectively showed that hepcidin could effectively attenuate iron-mediated secondary neuronal injury after ICH in rats. This naturally existing protein can potentially be developed into a therapeutic drug for the treatment of ICH patients.

A role for hepcidin in the anemia caused by Trypanosoma brucei infection

Trypanosomiasis is a parasitic disease affecting both humans and animals in the form of Human African Trypanosomiasis and Nagana disease, respectively. Anemia is one of the most common symptoms of trypanosomiasis, and if left unchecked can cause severe complications and even death. Several factors have been associated with the development of this anemia, including dysregulation of iron homeostasis, but little is known about the molecular mechanisms involved. Here, using murine models, we study the involvement of hepcidin, the key regulator of iron metabolism and an important player in the development of anemia of inflammation. Our data show two stages for the progression of anemia, to which hepcidin contributes a first stage when anemia develops, with a likely cytokine-mediated stimulation of hepcidin and subsequent limitation in iron availability and erythropoiesis, and a second stage of recovery, where the increase in hepcidin then declines due to the reduced inflammatory signal and increased production of erythroid regulators by the kidney, spleen and bone marrow, thus leading to an increase in iron release and availability, and enhanced erythropoiesis. In agreement with this, in hepcidin knockout mice, anemia is much milder and its recovery is complete, in contrast to wild-type animals which have not fully recovered from anemia after 21 days. Besides all other factors known to be involved in the development of anemia during trypanosomiasis, hepcidin clearly makes an important contribution to both its development and recovery.

Metabolic Conversion and Removal of Manganese Ferrite Nanoparticles in RAW264.7 Cells and Induced Alteration of Metal Transporter Gene Expression

Background

Manganese Ferrite Nanoparticles (Mn-IONPs) are widely used in biomedical field and their cytotoxicity has been initially explored, but the mechanism remains obscure. The nano-bio interactions are believed to be crucial for cytotoxicity mechanism, while little data have been acquired.

Methods

Mn-IONPs were synthesized by thermal decomposition of acetylacetonate precursor. After physicochemical characterization, we analyzed the metabolic conversion and removal of Mn-IONPs in RAW264.7 cells by Prussian blue staining, TEM, HRTEM and elemental quantitative analysis, followed by gene expression evaluation using quantitative RT-PCR.

Results

Mn-IONPs were successfully synthesized. Both the uptake and cytotoxicity of Mn-IONPs on RAW264.7 cells were time- and dose-dependent. After internalized, Mn-IONPs were passed to daughter cells with passages on. Meanwhile, Mn-IONPs were exocytosed and digested to metal ions and further excreted out, resulted in the labeling rate and ions contents decreased gradually. As ion influx related genes, the expressions of ZIP14, IRP2, FtH and DMT1 were suppressed within 24 hours but overexpressed to a plateau at the 48th hour in a dose-dependent manner. At the 72nd hour, ZIP14 and DMT1 mRNA levels decreased toward normal, while IRP2 and FtH kept up-regulated. As efflux related genes, FPN, SLC30A10 and Hamp2 genes were up-regulated within 24–72 hours; SPCA1 was suppressed at the 24th and 72nd hour, while overexpressed at the 48th hour. All the efflux related genes’ mRNA had a dose-dependent increasing manner at the corresponding time points.

Conclusion

Mn-IONPs showed time- and dose-dependent cytotoxicity and cell labeling rate in RAW264.7 cells. Accompanying with the intracellular catabolic breakdown and exocytosis of Mn-IONPs, RAW264.7 cells also secreted and re-uptook manganese and iron ions to maintain intracellular homeostasis in the succeeding passages. And the metabolic conversion of Mn-IONPs in RAW264.7 cells can affect the expression of ZIP14, DMT1, FPN, SLC30A10, IRP2, FtH, Hamp2 and SPCA1 genes.

Iron status in athletic females, a shift in perspective on an old paradigm

Iron deficiency is a common nutrient deficiency within athletes, with sport scientists and medical professionals recognizing that athletes require regular monitoring of their iron status during intense training periods. Revised considerations for athlete iron screening and monitoring have suggested that males get screened biannually during heavy training periods and females require screening biannually or quarterly, depending on their previous history of iron deficiency. The prevalence of iron deficiency in female athletes is higher than their male counterparts and is often cited as being a result of the presence of a menstrual cycle in the premenopausal years. This review has sought to revise our current understanding of female physiology and the interaction between primary reproductive hormones (oestrogen and progesterone) and iron homoeostasis in females. The review highlights an apparent symbiotic relationship between iron metabolism and the menstrual cycle that requires additional research as well as identifying areas of the menstrual cycle that may be primed for nutritional iron supplementation.

Oxidative Stress, Plant Natural Antioxidants, and Obesity

Oxidative stress is important in the pathophysiology of obesity, altering regulatory factors of mitochondrial activity, modifying the concentration of inflammation mediators associated with a large number and size of adipocytes, promoting lipogenesis, stimulating differentiation of preadipocytes to mature adipocytes, and regulating the energy balance in hypothalamic neurons that control appetite. This review discusses the participation of oxidative stress in obesity and the important groups of compounds found in plants with antioxidant properties, which include (a) polyphenols such as phenolic acids, stilbenes, flavonoids (flavonols, flavanols, anthocyanins, flavanones, flavones, flavanonols, and isoflavones), and curcuminoids (b) carotenoids, (c) capsaicinoids and casinoids, (d) isothiocyanates, (e) catechins, and (f) vitamins. Examples are analyzed, such as resveratrol, quercetin, curcumin, ferulic acid, phloretin, green tea, Hibiscus Sabdariffa, and garlic. The antioxidant activities of these compounds depend on their activities as reactive oxygen species (ROS) scavengers and on their capacity to prevent the activation of NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells), and reduce the expression of target genes, including those participating in inflammation. We conclude that natural compounds have therapeutic potential for diseases mediated by oxidative stress, particularly obesity. Controlled and well-designed clinical trials are still necessary to better know the effects of these compounds.

Antimicrobial Peptides and Copper(II) Ions: Novel Therapeutic Opportunities

The emergence of new pathogens and multidrug resistant bacteria is an important public health issue that requires the development of novel classes of antibiotics. Antimicrobial peptides (AMPs) are a promising platform with great potential for the identification of new lead compounds that can combat the aforementioned pathogens due to their broad-spectrum antimicrobial activity and relatively low rate of resistance emergence. AMPs of multicellular organisms made their debut four decades ago thanks to ingenious researchers who asked simple questions about the resistance to bacterial infections of insects. Questions such as "Do fruit flies ever get sick?", combined with pioneering studies, have led to an understanding of AMPs as universal weapons of the immune system. This review focuses on a subclass of AMPs that feature a metal binding motif known as the amino terminal copper and nickel (ATCUN) motif. One of the metal-based strategies of hosts facing a pathogen, it includes wielding the inherent toxicity of copper and deliberately trafficking this metal ion into sites of infection. The sudden increase in the concentration of copper ions in the presence of ATCUN-containing AMPs (ATCUN-AMPs) likely results in a synergistic interaction. Herein, we examine common structural features in ATCUN-AMPs that exist across species, and we highlight unique features that deserve additional attention. We also present the current state of knowledge about the molecular mechanisms behind their antimicrobial activity and the methods available to study this promising class of AMPs.

Associations of TMPRSS6 Polymorphisms with Gestational Diabetes Mellitus in Chinese Han Pregnant Women: a Preliminary Cohort Study

Body iron status is likely to be associated with type 2 diabetes (T2DM) and gestational diabetes mellitus (GDM); transmembrane protease serine 6 (TMPRSS6) polymorphisms may be associated with T2DM risk through their effects on body iron status. However, it remains unknown whether the TMPRSS6 single nucleotide polymorphisms (SNPs) affect the risk of GDM development. We aimed to determine whether the TMPRSS6 SNPs rs855791 (V736A) and rs4820268 (D521D) are associated with the risk of GDM in pregnant women. The two SNPs in TMPRSS6 gene were genotyped and examined for their associations with body iron status and GDM risk in 398 unrelated Chinese Han pregnant women. The 2 TMPRSS6 SNPs rs855791 and rs4820268 were both significantly associated with serum iron and transferrin saturation (P < 0.01 for all) rather than ferritin. After adjustment for covariates, the C allele of rs4820268 was nominally and significantly associated with an increased risk of GDM (OR = 2.531; 95%CI = 1.044-6.136, P = 0.040); when concentrations of ferritin were further adjusted, the association was still significant (OR = 2.528; 95%CI = 1.043-6.126, P = 0.040). There was a significant trend (P = 0.065) in the association between the T allele of rs855791 and an increased GDM risk in this study population. The 2 TMPRSS6 SNPs rs855791 and rs4820268 were both significantly associated with serum iron and transferrin saturation, and TMPRSS6 variants might be associated with the risk of GDM. Furthermore, the effects of TMPRSS6 SNPs on the risk of GDM may not be completely explained by the mediation of body iron status. Further studies are warranted.

A perspective on RNA interference-based therapeutics for metabolic liver diseases

Introduction: Therapeutic oligonucleotides have emerged as a promising new class of drug that could silence undruggable targets; they can potentially treat metabolic liver diseases such as nonalcoholic fatty liver disease (NAFLD), hereditary hemochromatosis and alpha 1 antitrypsin deficiency.Areas covered: This article illuminates the mechanism of action of, and drug delivery approaches for therapeutic oligonucleotides such as antisense oligonucleotides (ASOs), short interfering RNAs (siRNAs), and MicroRNAs (miRs). We reveal why the liver is the ideal organ for therapeutic oligonucleotides, discuss its unique architecture, and shed light on those susceptible molecular targets that can be modulated. We also examine preclinical and clinical data on the utility of oligonucleotides in silencing the expression of genes responsible for metabolic liver diseases.Expert opinion: The liver has numerous susceptible molecular therapeutic targets; hence, metabolic liver diseases can be treated effectively by modulating these targets via novel therapeutic oligonucleotides. Undoubtedly, these exciting developments integrate well with precision medicine progress. Specific therapeutic oligonucleotides can be designed based on the exact underlying molecular mechanism of the disease. So, there is a justification for furthering the development of therapeutic oligonucleotides for metabolic liver diseases. Safety concerns such as immunogenicity and off-target effects will however require careful monitoring.

Recent advances in iron homeostasis and regulation - a focus on epigenetic regulation and stroke

Iron is an element with redox properties. It is active sites of many enzymes and plays an important role in various cellular and biological functions including ATP production and DNA synthesis. However, as a redox element, iron promotes free radical generation and lipid peroxidation, causing oxidative damage and cell death. Iron-mediated oxidation is a central player in ferroptosis, a type of cell death process that is different from apoptosis and necrosis. Thus, iron metabolism and homeostasis are sophisticatedly regulated. There has been exciting progress in understanding iron metabolism and regulation since hepcidin was recognized as the central regulator of iron homeostasis. Hepcidin mainly regulates the iron export function of the ferrous iron permease, ferroportin, which is the only known iron exporter expressed by mammalian cells. Particularly, epigenetic regulation has been a recent focus on iron homeostasis. Epigenetic phenomena have been demonstrated to modulate key proteins including hepcidin in iron metabolism. Here, we review the rapid progress in recent years in understanding molecular mechanisms of iron homeostasis with a focus on epigenetic regulation of hepcidin, ferritin, and ferroptosis. Interactions between methionine oxidation and iron is also discussed. Furthermore, many studies have suggested that the severity of neuronal damage after stroke is proportional to the magnitude of brain iron accumulation. Recent discoveries regarding iron metabolism in stroke is briefly discussed. Understanding the underlying mechanism in iron regulation could provide insight into the treatment of various intractable diseases including stroke.

Coaction of hepatic thioredoxin and glutathione systems in iron overload-induced oxidative stress

In the present study, we demonstrate the coaction of thioredoxin and glutathione (GSH) systems in mouse liver against iron overload-induced oxidative stress (OS). Mice were injected intraperitoneally with an iron dextran solution twice a week for 3 weeks. Iron accumulation in mouse liver was demonstrated spectroscopically. To confirm the iron overload model in the liver, the increased gene expression levels of hepcidin (Hamp), ferroportin (Fpn1), and ferritin (Fth1), which regulate iron trafficking, were observed by a quantitative polymerase chain reaction. In the case of iron overload, the GSH level and the reduced glutathione/oxidized glutathione ratio, which represents a marker of OS, decreased significantly. An increase in the malondialdehyde level, one of the final products of the lipid peroxidation process, was observed. The gene expression of the thioredoxin system, including thioredoxin (Trx1) and thioredoxin reductase (TrxR1), was examined. Though TrxR1 expression decreased, no changes were observed in Trx1. The enzyme activity and semiquantitative protein expression of TRXR1 increased. The activity of GSH reductase and GSH peroxidase increased in the iron overload group. The gene and protein expressions of thioredoxininteracting protein, which is an indicator of the commitment of the cell to apoptosis, were elevated significantly. The increased protein expression of Bcl-2-related X protein and CASPASE-3, which is an indicator of apoptosis, increased significantly. In conclusion, excess iron accumulation in mouse liver tissue causes OS, which affects the redox state of the thioredoxin and GSH systems, inducing cell apoptosis and also ferroptosis due to increased lipid peroxidation and the depletion of GSH level.

Roxadustat for CKD-related Anemia in Non-dialysis Patients

Introduction

Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that stimulates erythropoiesis and improves iron metabolism. We assessed the efficacy and tolerability of roxadustat in patients with chronic kidney disease (CKD)-related anemia not on dialysis.

Methods

ANDES was a global Phase 3 randomized study in which adults with stage 3–5 CKD not on dialysis received roxadustat or placebo. Patients were initially dosed thrice weekly; dose was titrated to achieve a hemoglobin level ≥11.0 g/dl, followed by titration for maintenance. The primary endpoints were change in hemoglobin (weeks 28–52) and proportion of patients achieving a hemoglobin response (hemoglobin ≥11.0 g/dl and increase ≥1.0 g/dl [baseline >8.0 g/dl], or increase ≥2.0 g/dl [baseline ≤8.0 g/dl]) (week 24). Treatment-emergent adverse events (TEAEs) and serious adverse events (TESAEs) were recorded.

Results

In roxadustat (n = 616) and placebo (n = 306) groups, hemoglobin mean (SD) change from baseline over weeks 28–52 was significantly larger for roxadustat (2.00 [0.95]) versus placebo (0.16 [0.90]), corresponding to least-squares mean difference of 1.85 g/dl (95% confidence interval [CI] 1.74–1.97; P < 0.0001). The proportion of patients achieving a response at week 24 was larger for roxadustat (86.0%; 95% CI 83.0%–88.7%) versus placebo (6.6%; 95% CI 4.1%–9.9%; P < 0.0001). The proportion of patients receiving rescue therapy at week 52 was smaller for roxadustat (8.9%) versus placebo (28.9%); hazard ratio, 0.19 (95% CI 0.14–0.28; P < .0001). The incidences of TEAEs and TESAEs were comparable.

Conclusion

This study showed that roxadustat corrected and maintained hemoglobin and was well tolerated in patients with CKD-related anemia not on dialysis (ClinicalTrials.gov NCT01750190).

Hepcidin Decreases Rotenone-Induced α-Synuclein Accumulation via Autophagy in SH-SY5Y Cells

Parkinson’s disease (PD) is a neurodegenerative disorder, and the hallmarks of this disease include iron deposition and α-synuclein (α-syn) aggregation. Hepcidin could reduce iron in the central and peripheral nervous systems. Here, we hypothesized that hepcidin could further decrease α-syn accumulation via reducing iron. Therefore, rotenone or α-syn was introduced into human neuroblastoma SH-SY5Y cells to imitate the pathological progress of PD in vitro. This study investigated the clearance effects of hepcidin on α-syn induced by a relatively low concentration of rotenone exposure or α-syn overexpression to elucidate the potential clearance pathway involved in this process. We demonstrated that SH-SY5Y cell viability was impaired after rotenone treatment in a dose-dependent manner. α-syn expression and iron content increased under a low concentration rotenone (25 nM for 3 days) treatment in SH-SY5Y cells. Pre-treatment with hepcidin peptide suppressed the abovementioned effects of rotenone. However, hepcidin did not affect treatment with rotenone under high iron conditions. Hepcidin also played a role in reducing α-syn accumulation in rotenone and α-syn overexpression conditions. We identified that the probable clearance effect of hepcidin on α-syn was mediated by the autophagy pathway using pretreatment with autophagy inhibitors (3-MA and CQ) and detection of autophagy protein markers (LC3II/I and p62). In conclusion, hepcidin eliminated α-syn expression via the autophagy pathway in rotenone-treated and α-syn overexpression SH-SY5Y cells. This study highlights that hepcidin may offer a potential therapeutic perspective in α-syn accumulation diseases.

Effect of Fe (III) on L-asparagine monohydrate investigated under low- and high-temperature conditions

Raman spectra of Fe-doped L-asparagine monohydrate (LAM:Fe) crystal were studied under several temperatures varying from 17 to 490 K. The effect of Fe (III) ion on the stability of the crystal in changing temperature through the vibrational spectra was discussed. The behavior of inter and intra-molecular vibration modes has indicated two phase transitions and an amorphous transformation. These effects were also clarified by X-ray powder diffraction measurements which corroborate very well the Raman data. In addition, we have determinated the lattice parameters of all phases and verified that under low temperature conditions the crystal undergoes a conformational transition whereas under high temperatures its structure transforms from the orthorhombic (P2₁2₁2₁-space group) to the monoclinic (P2₁-space group) symmetry and, after this process, it goes to an amorphous phase due to the start of the decomposition. Finally, differential scanning calorimetry analysis was utilized as complementary technique to investigate the structural stability of LAM:Fe and results are in a good agreement with the Raman and the X-ray diffraction data.

The battle for iron in enteric infections

Iron is an essential element for almost all living organisms, but can be extremely toxic in high concentrations. All organisms must therefore employ homeostatic mechanisms to finely regulate iron uptake, usage and storage in the face of dynamic environmental conditions. The critical step in mammalian systemic iron homeostasis is the fine regulation of dietary iron absorption. However, as the gastrointestinal system is also home to >1014 bacteria, all of which engage in their own programmes of iron homeostasis, the gut represents an anatomical location where the inter-kingdom fight for iron is never-ending. Here, we explore the molecular mechanisms of, and interactions between, host and bacterial iron homeostasis in the gastrointestinal tract. We first detail how mammalian systemic and cellular iron homeostasis influences gastrointestinal iron availability. We then focus on two important human pathogens, Salmonella and Clostridia; despite their differences, they exemplify how a bacterial pathogen must navigate and exploit this web of iron homeostasis interactions to avoid host nutritional immunity and replicate successfully. We then reciprocally explore how iron availability interacts with the gastrointestinal microbiota, and the consequences of this on mammalian physiology and pathogen iron acquisition. Finally, we address how understanding the battle for iron in the gastrointestinal tract might inform clinical practice and inspire new treatments for important diseases.

Re-examining ferritin-bound iron: current and developing clinical tools

Iron is a highly important metal ion cofactor within the human body, necessary for haemoglobin synthesis, and required by a wide range of enzymes for essential metabolic processes. Iron deficiency and overload both pose significant health concerns and are relatively common world-wide health hazards. Effective measurement of total iron stores is a primary tool for both identifying abnormal iron levels and tracking changes in clinical settings. Population based data is also essential for tracking nutritional trends. This review article provides an overview of the strengths and limitations associated with current techniques for diagnosing iron status, which sets a basis to discuss the potential of a new serum marker - ferritin-bound iron - and the improvement it could offer to iron assessment.

Inflammation Mediated Hepcidin-Ferroportin Pathway and Its Therapeutic Window in Breast Cancer

Experimental and clinical data strongly support that iron is an essential element which plays a big role in cancer biology. Thus, hepcidin (Hp) and ferroportin (Fpn) are molecules that regulate and maintain the metabolism of iron. A peptide hormone hepcidin limits recycled and stored iron fluxes in macrophage and hepatic hepatocyte, respectively, to the blood stream by promoting degradation of the only iron exporter, Fpn, in the target cells. Moreover, the inflammatory microenvironment of breast cancer and altered hepcidin/ferroportin pathway is intimately linked. Breast cancer exhibits an iron seeking phenotype that is accomplished by tumor-associated macrophage (TAM). Because macrophages contribute to breast cancer growth and progression, this review will discuss TAM with an emphasis on describing how TAM (M2Ф phenotypic) interacts with their surrounding microenvironment and results in dysregulated Hp/Fpn and pathologic accumulation of iron as a hallmark of its malignant condition. Moreover, the underlying stroma or tumor microenvironment releases significant inflammatory cytokines like IL-6 and bone morphogenetic proteins like BMP-2 and 6 leading in aberrant Hp/Fpn pathways in breast cancer. Inflammation is primarily associated with the high intracellular iron levels, deregulated hepcidin/ferroportin pathway, and its upstream signaling in breast cancer. Subsequently, scholars have been reported that reducing iron level and manipulating the signaling molecules involved in iron metabolism can be used as a promising strategy of tumor chemotherapy. Here, we review the key molecular aspects of iron metabolism and its regulatory mechanisms of the hepcidin/ferroportin pathways and its current therapeutic strategies in breast cancer.

Refining Treatment Strategies for Iron Deficient Athletes

Iron deficiency (ID) is a prevailing nutritional concern amongst the athletic population due to the increased iron demands of this group. Athletes' ability to replenish taxed iron stores is challenging due to the low bioavailability of dietary sources, and the interaction between exercise and hepcidin, the primary iron-regulatory hormone. To date, copious research has explored the link between exercise and iron regulation, with a more recent focus on optimising iron treatment applications. Currently, oral iron supplementation is typically the first avenue of iron replacement therapy beyond nutritional intervention, for treatment of ID athletes. However, many athletes encounter associated gastrointestinal side-effects which can deter them from fulfilling a full-term oral iron treatment plan, generally resulting in sub-optimal treatment efficacy. Consequently, various strategies (e.g. dosage, composition, timing) of oral iron supplementation have been investigated with the goal of increasing fractional iron absorption, reducing gastric irritation, and ultimately improving the efficacy of oral iron therapy. This review explores the various treatment strategies pertinent to athletes and concludes a contemporary strategy of oral iron therapy entailing morning supplementation, ideally within the 30 min following morning exercise, and in athletes experiencing gut sensitivity, consumed on alternate days or at lower doses.

Pathogen-Associated Molecules from Gut Translocation Enhance Severity of Cecal Ligation and Puncture Sepsis in Iron-Overload β-Thalassemia Mice

Introduction

Systemic inflammation induced by gut translocation of lipopolysaccharide (LPS), a major component of Gram-negative bacteria, in thalassemia with iron-overload worsens sepsis. However, the impact of (1→3)-β-D-glucan (BG), a major fungal molecule, in iron-overload thalassemia is still unclear. Hence, the influence of BG was explored in 1) iron-overload mice with sepsis induced by cecal ligation and puncture (CLP) surgery; and 2) in bone marrow-derived macrophages (BMMs).

Methods

The heterozygous β-globin-deficient mice, Hbb^th3/+ mice, were used as representative thalassemia (TH) mice. Iron overload was generated by 6 months of oral iron administration before CLP surgery- induced sepsis in TH mice and wild-type (WT) mice. Additionally, BMMs from both mouse strains were used to explore the impact of BG.

Results

Without sepsis, iron-overload TH mice demonstrated more severe intestinal mucosal injury (gut leakage) with higher LPS and BG in serum, from gut translocation, when compared with WT mice. With CLP in iron-overload mice, sepsis severity in TH mice was more severe than WT as determined by survival analysis, organ injury (kidney and liver), bacteremia, endotoxemia, gut leakage (FITC-dextran) and serum BG. Activation by LPS plus BG (LPS+BG) in BMMs and in peripheral blood-derived neutrophils (both WT and TH cells) demonstrated more prominent cytokine production when compared with LPS activation alone. In parallel, LPS+BG also prominently induced genes expression of M1 macrophage polarization (iNOS, TNF-α and IL-1β) in both WT and TH cells in comparison with LPS activation alone. In addition, LPS+BG activated macrophage cytokine production was enhanced by a high dose of ferric ion (800 mM), more predominantly in TH macrophages compared with WT cells. Moreover, LPS+BG induced higher glycolysis activity with similar respiratory capacity in RAW264.7 (a macrophage cell line) compared with LPS activation alone. These data support an additive pro-inflammatory effect of BG upon LPS.

Conclusion

The enhanced-severity of sepsis in iron-overload TH mice was due to 1) increased LPS and BG in serum from iron-induced gut-mucosal injury; and 2) the pro-inflammatory amplification by ferric ion on LPS+BG activation.

The efficacy and safety of roxadustat for anemia in patients with chronic kidney disease: a meta-analysis

BACKGROUND

Chronic kidney disease (CKD) is an increasing public health issue. Anemia, which is a complication of CKD, is associated with reduced quality of life and increased morbidity and mortality. Currently quite a few clinical studies have been conducted to compare roxadustat with epoetin alfa [all for dialysis-dependent (DD) patients] or placebo [all for nondialysis-dependent (NDD) patients]. Our meta-analysis aimed to investigate the efficacy and safety of roxadustat for anemia in patients with CKD.

METHODS

We thoroughly searched eight electronic resource databases for randomized controlled trials (RCTs) comparing the efficacy and safety between roxadustat versus epoetin alfa or placebo for the treatment of anemia in patients with CKD.

RESULTS

Four Phase 2 and two Phase 3 studies with 1010 participants were included. Hemoglobin (Hb) and transferrin levels were increased significantly in the roxadustat group versus those in the placebo {standard mean difference [SMD] 1.57 [95% confidence interval (CI) 1.17-1.98]; SMD 1.81 [95% CI 1.53-2.08]; respectively, both low-quality evidence} or epoetin alfa group [SMD 0.47 (95% CI 0.02-0.93), very low-quality evidence; SMD 1.05 (95% CI 0.81-1.29), low-quality evidence; respectively]. Hepcidin levels were reduced significantly in the roxadustat group versus those in the placebo [SMD -1.72 (95% CI -3.03 to -0.41), very low-quality evidence] or epoetin alfa group [SMD -0.23 (95% CI -0.43 to -0.02), low-quality evidence]. Ferritin and serum transferrin saturation (TSAT) levels were reduced significantly in the roxadustat group versus those in the placebo group [SMD -0.82 (95% CI -1.31 to -0.33); SMD -0.54 (95% CI -0.76 to -0.32), respectively; both low-quality evidence] and ferritin and TSAT levels in the roxadustat group were comparable to those in the epoetin alfa group [SMD 0.02 (95% CI -0.18-0.21); SMD 0.15 (95% CI -0.04-0.35), respectively, both low-quality evidence]. As for safety, the incidence of adverse events (AEs) in the roxadustat group was insignificantly different from that of the placebo group [risk ratio (RR) 0.99 (95% CI 0.83-1.18); P = 0.89, very low-quality evidence]. But the incidence of AEs in the roxadustat group was significantly higher than that in the epoetin alfa group [RR 1.25 (95% CI 1.01-1.54); P = 0.04, low-quality evidence]. There was no significant association between roxadustat and the incidence of serious AEs (SAEs) for both NDD and DD patients [RR 1.08 (95% CI 0.51-2.28) and RR 1.43 (95% CI 0.85-2.40), respectively, both very low-quality evidence].

CONCLUSION

In this meta-analysis of RCTs, we found evidence that after the oral administration of roxadustat, NDD patients' Hb levels were increased effectively and DD patients' Hb levels were maintained effectively. The risk of SAEs was not observed with the short-term use of roxadustat. These findings support roxadustat for the treatment of anemia in patients with CKD.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

The effect of iron dosing schedules on plasma hepcidin and iron absorption in Kenyan infants

BACKGROUND

In adults, oral iron doses increase plasma hepcidin (PHep) for 24 h, but not for 48 h, and there is a circadian increase in PHep over the day. Because high PHep decreases fractional iron absorption (FIA), alternate day iron dosing in the morning may be preferable to consecutive day dosing. Whether these effects occur in infants is uncertain.

OBJECTIVE

Using stable iron isotopes in Kenyan infants, we compared FIA from morning and afternoon doses and from consecutive, alternate (every second day) and every third day iron doses.

METHODS

In prospective studies, we measured and compared FIA and the PHep response from 1) meals fortified with a 12-mg iron micronutrient powder given in the morning or afternoon (n = 22); 2) the same given on consecutive or alternate days (n = 21); and 3) a 12-mg iron supplement given on alternate days or every third day (n = 24).

RESULTS

In total, 65.7% of infants were anemic. In study 1, PHep did not differ between morning and afternoon (P = 0.072), and geometric mean FIA[-SD, +SD](%) did not differ between the morning and afternoon doses [15.9 (8.9, 28.6) and 16.1 (8.7, 29.8), P = 0.877]. In study 2, PHep was increased 24 h after oral iron (P = 0.014), and mean FIA [±SD](%) from the baseline dose [23.3 (10.9)] was greater than that from the consecutive day dose (at 24 h) [20.1 (10.4); P = 0.042] but did not differ from the alternate day dose (at 48 h) [20.9 (13.4); P = 0.145]. In study 3, PHep was not increased 48 and 72 h after oral iron (P = 0.384), and the geometric mean FIA[-SD, +SD](%) from doses given at baseline, alternate days, and every third day did not differ [12.7 (7.3, 21.9), 13.8 (7.8, 24.2), and 14.8 (8.8, 24.8), respectively; P = 0.080].

CONCLUSIONS

In Kenyan infants given 12 mg oral iron, morning and afternoon doses are comparably absorbed, dosing on consecutive days increases PHep and modestly decreases iron absorption compared with alternate day dosing, and dosing on alternate days or every third day does not increase PHep or decrease absorption. This trial was registered at clinicaltrials.gov as NCT02989311 and NCT03617575.

Relationship between Obesity and Iron Deficiency in Healthy Adolescents

The relationship between overweight/obesity (excess of weight [EW]) and iron deficiency (ID) is not well defined. Objective: To analyze the relationship between EW and ID in healthy adolescents, assessing the contribution of new diagnostic measures of iron status and erythropoietic activity. Method: A cross-sectional study was made of 405 healthy adolescents, 12-16 years of age. A total of 289 were normal weight (NW) and 116 were otherwise healthy EW. Epidemiological, socioeconomic, diet, BMI Z-score, CRP (C-reactive protein), hematological, iron status, and erythropoietic activity parameters were measured. Statistical tests were Student's, analysis of variance (ANOVA), Chi-square, Pearson's correlation, and odds ratio. Results: ID prevalence in the EW group was 22.6% vs. 29.5% in the NW group (p: 0.3). Greater body weight was associated with lower reticulocyte hemoglobin content (CHr) (NW: 31.3 ± 1.7 pg vs. OW: 30.2 ± 1.7 pg, p: 0.007) and greater CRP (NW: 0.1 ± 0.2 mg/dL vs. OW: 0.2 ± 0.18 mg/dL, p < 0.001), leukocytes (NW: 6.69 ± 1.57 × 10³/L vs. OW: 7.43 ± 1.63 × 10³/L, p < 0.02), platelets (NW: 265.6 ± 58.9 × 10³/L vs. OW: 291.8 ± 54.4 × 10³/L, p < 0.002), ferritin (NW: 32.1 ± 17.9 ng/mL vs. OW: 42.8 ± 20.3 ng/mL, p: 0.01), serum transferrin receptor (sTfR) (NW: 1.39 ± 0.4 mg/L vs. OW: 1.73 ± 0.45 mg/L, p: 0.008), sTfR-F index (sTfR/log Ferritin) (NW: 1.06 ± 0.7 vs. OW: 1.33 ± 0.85, p: 0.036) and reticulocyte count (NW: 54.2 ± 18 × 10³/L vs. OW: 65.4 ± 24.2 × 10³/L, p: 0.003). A positive correlation was observed between the BMI Z-score and CRP, ferritin, sTfR, leukocytes, platelets, and reticulocyte count, and a negative one between the BMI Z-score and CHr and medium corpuscular volume. Conclusions: The prevalence of ID in otherwise healthy EW adolescents was no higher than in NW. The effect of obesity on iron status was low. The findings reveal the concomitant low-grade inflammation, and probably the effect of adiposity on erythropoietic activity. Specific cutoff values for ID in adolescents with OW need to be defined.

Leishmania infection triggers hepcidin-mediated proteasomal degradation of Nramp1 to increase phagolysosomal iron availability

Natural resistance-associated macrophage protein 1 (Nramp1) was originally discovered as a genetic determinant of resistance against multiple intracellular pathogens, including Leishmania. It encodes a transmembrane protein of the phago-endosomal compartments, where it functions as an iron transporter. But the mechanism by which Nramp1 controls host-pathogen dynamics and determines final outcome of an infection is yet to be fully deciphered. Whether the expression of Nramp1 is altered in response to a pathogen attack is also unknown. To address these, Nramp1 status was examined in Leishmania major-infected murine macrophages. We observed that at 12 hrs post infection, there was drastic lowering of Nramp1 level accompanied by increased phagolysosomal iron content and enhanced intracellular parasite growth. Leishmania infection-induced Nramp1 downregulation was caused by ubiquitin-proteasome degradation pathway, which in turn was found to be mediated by the iron-regulatory peptide hormone hepcidin. Blocking of Nramp1 degradation with proteasome inhibitor or transcriptional agonist of hepcidin resulted in depletion of phagolysosomal iron pool that led to significant reduction of intracellular parasite burden. Interestingly, Nramp1 level was restored to normalcy after 30 hrs of infection with a concomitant drop in phagolysosomal iron, which is suggestive of a host counteractive response to deprive the pathogen of this essential micronutrient. Taken together, our study implicates Nramp1 as a central player in the host-pathogen battle for phagolysosomal iron. We also report Nramp1 as a novel target for hepcidin, and this 'hepcidin-Nramp1' axis may have a broader role in regulating macrophage iron homeostasis.

Antianemic action of the iron (IV) clathrochelate complexes

Anemia is one of the most common non-contagious diseases of pigs. Modern antianemic drugs have several drawbacks, so finding new drugs is a pressing issue. We previously reported the results of preclinical studies of iron in rare high valence IV. This allowed us to determine, supplement, and generalize the data on clinical studies of the new drugs with the active substance iron (IV) clathrochelate. Therefore, we studied its antianemic effect on piglets. Experiments were carried out on piglets-analogues neonates, which were divided into three groups: control and two experimental groups. Piglets were kept with sows on suckling. For the purpose of prevention of iron deficiency anemia, the traditional solution of iron dextran was administered once intramuscularly to piglets of I control group. The aqueous solution of iron (IV) clathrochelate complexes was administered once intramuscularly to piglets of II experimental group. Iron (IV) clathrochelate complexes were dissolved in a solvent of rheopolyglucin and administered once intramuscularly to piglets of III experimental group. 1 mL of test solutions contained 100 mg of active substance. The investigative material were the samples of blood and serum of piglets, their liver and spleen. The experiment lasted during a 30-day period since the birth of the piglets. According to the results of the experiments, iron (IV) clatrochelate complexes which were dissolved in water for injection and rheopolyglucin had higher antianemic activity compared to the control. This is evidenced by the dynamics of probable changes in the number of erythrocytes, hemoglobin content and hematocrit, iron content in serum and its mass fraction in the blood, liver and spleen of piglets. The effectiveness of the action of iron (IV) clatrochelate complexes is demonstrated by the full supply of piglets with iron and its higher bioavailability.