Regulation of ferritin genes and protein

Iron Deficiency: A New Target for Patients With Heart Failure

Iron deficiency (ID) is one of the most frequent comorbidities in patients with heart failure (HF). ID is estimated to be present in up to 50% of outpatients and is a strong independent predictor of HF outcomes. ID has been shown to reduce quality of life, exercise capacity and survival, in both the presence and absence of anemia. The most recent 2016 guidelines recommend starting replacement treatment at ferritin cutoff value <100 mcg/l or between 100 and 299 mcg/l when the transferrin saturation is <20%. Beyond its effect on hemoglobin, iron plays an important role in oxygen transport and in the metabolism of cardiac and skeletal muscles. Mitochondria are the most important sites of iron utilization and energy production. These factors clearly have roles in the diminished exercise capacity in HF. Oral iron administration is usually the first route used for iron repletion in patients. However, the data from the IRONOUT HF study do not support the use of oral iron supplementation in patients with HF and a reduced ejection fraction, because this treatment does not affect peak VO₂ (the primary endpoint of the study) or increase serum ferritin levels. The FAIR-HF and CONFIRM-HF studies have shown improvements in symptoms, quality of life and functional capacity in patients with stable, symptomatic, iron-deficient HF after the administration of intravenous iron (i.e., FCM). Moreover, they have shown a decreased risk of first hospitalization for worsening of HF, as later confirmed in a subsequent meta-analysis. In addition, the EFFECT-HF study has shown an improvement in peak oxygen consumption at CPET (a parameter generally considered the gold standard of exercise capacity and a predictor of outcome in HF) in patients randomized to receive ferric carboxymaltose. Finally, the AFFIRM AHF trial evaluating the effects of FCM administration on the outcomes of patients hospitalized for acute HF has found significantly fewer hospital readmissions due to HF among patients treated with FCM rather than placebo.

Liver Sinusoidal Endothelial Cells at the Crossroad of Iron Overload and Liver Fibrosis

Significance: Liver fibrosis results from different etiologies and represents one of the most serious health issues worldwide. Fibrosis is the outcome of chronic insults on the liver and is associated with several factors, including abnormal iron metabolism. Recent Advances: Multiple mechanisms underlying the profibrogenic role of iron have been proposed. The pivotal role of liver sinusoidal endothelial cells (LSECs) in iron-level regulation, as well as their morphological and molecular dedifferentiation occurring in liver fibrosis, has encouraged research on LSECs as prime regulators of very early fibrotic events. Importantly, normal differentiated LSECs may act as gatekeepers of fibrogenesis by maintaining the quiescence of hepatic stellate cells, while LSECs capillarization precedes the onset of liver fibrosis. Critical Issues: In the present review, the morphological and molecular alterations occurring in LSECs after liver injury are addressed in an attempt to highlight how vascular dysfunction promotes fibrogenesis. In particular, we discuss in depth how a vicious loop can be established in which iron dysregulation and LSEC dedifferentiation synergize to exacerbate and promote the progression of liver fibrosis. Future Directions: LSECs, due to their pivotal role in early liver fibrosis and iron homeostasis, show great promises as a therapeutic target. In particular, new strategies can be devised for restoring LSECs differentiation and thus their role as regulators of iron homeostasis, hence preventing the progression of liver fibrosis or, even better, promoting its regression. Antioxid. Redox Signal. 35, 474-486.

A double-blind, controlled, crossover trial of amlodipine on iron overload status in transfusion dependent β-thalassemia patients

BACKGROUND AND AIM

This study examined whether administration of amlodipine could improve myocardial iron loading status in patients with transfusion dependent β-thalassemia (TDT), through a placebo-controlled, crossover study.

METHODS

Amlodipine (5 mg, daily) or placebo were prescribed to all patients (n = 19) for 6 months, and after a 2-week washout period, patients were crossed over to the other group. The efficacy of amlodipine on iron loading was assessed by measuring myocardial T2*-weighted magnetic resonance imaging (MRI T2*, millisecond [ms]) and serum ferritin (ng/mL).

RESULTS

Seventeen patients completed the study. The mean ± standard deviation [SD] of myocardial MRI T2* at baseline was 9.83 ± 2.67 ms Myocardial MRI T2* value rose to 11.44 ± 4.14 ms post amlodipine treatment in all patients. After placebo, myocardial MRI T2* value reached 10.29 ± 4.01 ms After controlling the baseline measures, Hedges's g for ferritin and myocardial MRI T2* outcomes were estimated 3.84 (95% confidence interval [CI] 2.68 to 4.97) and -1.80 (95% CI -2.58 to -0.10), respectively.

CONCLUSION

Amlodipine might improve myocardial MRI T2* and serum ferritin level compared to placebo. However, larger clinical studies are needed to confirm the results.

Iron metabolism in infections: Focus on COVID-19

Iron is a micronutrient essential for a wide range of metabolic processes in virtually all living organisms. During infections, a battle for iron takes place between the human host and the invading pathogens. The liver peptide hepcidin, which is phylogenetically and structurally linked to defensins (antimicrobial peptides of the innate immunity), plays a pivotal role by subtracting iron to pathogens through its sequestration into host cells, mainly macrophages. While this phenomenon is well studied in certain bacterial infections, much less is known regarding viral infections. Iron metabolism also has implications on the functionality of cells of the immune system. Once primed by the contact with antigen presenting cells, lymphocytes need iron to sustain the metabolic burst required for mounting an effective cellular and humoral response. The COVID-19 pandemic has boosted an amount of clinical and translational research over the possible influences of nutrients on SARS-CoV-2 infection, in terms of either susceptibility or clinical course. Here we review the intersections between iron metabolism and COVID-19, belonging to the wider domain of the so-called “nutritional immunity”. A better understanding of such connections has potential broad implications, either from a mechanistic standpoint, or for the development of more effective strategies for managing COVID-19 and possible future pandemics.

Macrophage activation syndrome in COVID-19

The novel coronavirus epidemic is characterized by high rates of morbidity and relatively high mortality. Laboratory test results in patients include leukopenia, an increase in liver function tests and ferritin levels reaching hundreds, and sometimes thousands of units. These data remind us about the macrophage activation syndrome (MAC). Secondary hemophagocytic lymphohistiocytosis syndrome, MAC, which pathogenesis is based on a defect in the mechanisms of T-cell cytotoxicity and decreased level of natural killer cells associated with the defect in the perforin-encoding gene as well as hyperproduction of a number of cytokines – interleukin (IL)-1â, tumor necrosis factor-á, etc. by T-lymphocytes and histiocytes, indirectly leading to the activation of macrophages and production of proinflammatory cytokines, in particular IL-6 hyperproduction. MAC is one of "hyperferritinemic syndromes". These disorders have similar clinical and laboratory manifestations, and they also respond to similar treatments, suggesting that hyperferritinemia may be involved in the overall pathogenesis and is characterized by elevated ferritin level and cytokine storm. Despite the fact that data on the immune and inflammatory status in patients with COVID-19 have only started to appear, it is already clear that hyperinflammation and coagulopathy affect the disease severity and increase the risk of death in patients infected with SARS-CoV-2. Hence, understanding the pathogenesis of the novel coronavirus infection can help in its early diagnostics and treatment.

Ferritin H deficiency deteriorates cellular iron handling and worsens Salmonella typhimurium infection by triggering hyperinflammation

Iron is an essential nutrient for mammals as well as for pathogens. Inflammation-driven changes in systemic and cellular iron homeostasis are central for host-mediated antimicrobial strategies. Here, we studied the role of the iron storage protein ferritin H (FTH) for the control of infections with the intracellular pathogen Salmonella enterica serovar Typhimurium by macrophages. Mice lacking FTH in the myeloid lineage (LysM-Cre+/+Fthfl/fl mice) displayed impaired iron storage capacities in the tissue leukocyte compartment, increased levels of labile iron in macrophages, and an accelerated macrophage-mediated iron turnover. While under steady-state conditions, LysM-Cre+/+Fth+/+ and LysM-Cre+/+Fthfl/fl animals showed comparable susceptibility to Salmonella infection, i.v. iron supplementation drastically shortened survival of LysM-Cre+/+Fthfl/fl mice. Mechanistically, these animals displayed increased bacterial burden, which contributed to uncontrolled triggering of NF-κB and inflammasome signaling and development of cytokine storm and death. Importantly, pharmacologic inhibition of the inflammasome and IL-1β pathways reduced cytokine levels and mortality and partly restored infection control in iron-treated ferritin-deficient mice. These findings uncover incompletely characterized roles of ferritin and cellular iron turnover in myeloid cells in controlling bacterial spread and for modulating NF-κB and inflammasome-mediated cytokine activation, which may be of vital importance in iron-overloaded individuals suffering from severe infections and sepsis.

A unique macrophage subpopulation signals directly to progenitor cells to promote regenerative neurogenesis in the zebrafish spinal cord

Central nervous system injury re-initiates neurogenesis in anamniotes (amphibians and fishes), but not in mammals. Activation of the innate immune system promotes regenerative neurogenesis, but it is fundamentally unknown whether this is indirect through the activation of known developmental signaling pathways or whether immune cells directly signal to progenitor cells using mechanisms that are unique to regeneration. Using single-cell RNA-seq of progenitor cells and macrophages, as well as cell-type-specific manipulations, we provide evidence for a direct signaling axis from specific lesion-activated macrophages to spinal progenitor cells to promote regenerative neurogenesis in zebrafish. Mechanistically, TNFa from pro-regenerative macrophages induces Tnfrsf1a-mediated AP-1 activity in progenitors to increase regeneration-promoting expression of hdac1 and neurogenesis. This establishes the principle that macrophages directly communicate to spinal progenitor cells via non-developmental signals after injury, providing potential targets for future interventions in the regeneration-deficient spinal cord of mammals.

Ferritin, fever, and frequent visits: Hyperferritinemic syndromes in the emergency department

Fever of unknown origin (FUO) is defined as persistent fevers without an identifiable cause despite extensive medical workup. Emergency physicians caring for patients reporting a persistent, nonspecific, febrile illness should carefully consider potentially serious non-infectious causes of FUO. We present a case of a 35-year-old man who presented to the emergency department (ED) three times over a 10-day period for persistent febrile illness and was ultimately diagnosed with Adult-Onset Still's Disease (AOSD) after a serum ferritin level was found to be over 42,000 μg/L. AOSD, along with macrophage activation syndrome, catastrophic antiphospholipid syndrome, and septic shock comprise the four hyperferritinemic syndromes. These are potentially life-threatening febrile illnesses that characteristically present with elevated ferritin levels. In this article, we highlight the value of a serum ferritin level in the workup of a patient with prolonged febrile illness and its utility in facilitating early diagnosis and prompt treatment of hyperferritinemic syndromes in the ED.

Neurohormonal activation induces intracellular iron deficiency and mitochondrial dysfunction in cardiac cells

Background

Iron deficiency (ID) is common in patients with heart failure (HF) and is associated with poor outcomes, yet its role in the pathophysiology of HF is not well-defined. We sought to determine the consequences of HF neurohormonal activation in iron homeostasis and mitochondrial function in cardiac cells.

Methods

HF was induced in C57BL/6 mice by using isoproterenol osmotic pumps and embryonic rat heart-derived H9c2 cells were subsequently challenged with Angiotensin II and/or Norepinephrine. The expression of several genes and proteins related to intracellular iron metabolism were assessed by Real time-PCR and immunoblotting, respectively. The intracellular iron levels were also determined. Mitochondrial function was analyzed by studying the mitochondrial membrane potential, the accumulation of radical oxygen species (ROS) and the adenosine triphosphate (ATP) production.

Results

Hearts from isoproterenol-stimulated mice showed a decreased in both mRNA and protein levels of iron regulatory proteins, transferrin receptor 1, ferroportin 1 and hepcidin compared to control mice. Furthermore, mitoferrin 2 and mitochondrial ferritin were also downregulated in the hearts from HF mice. Similar data regarding these key iron regulatory molecules were found in the H9c2 cells challenged with neurohormonal stimuli. Accordingly, a depletion of intracellular iron levels was found in the stimulated cells compared to non-stimulated cells, as well as in the hearts from the isoproterenol-induced HF mice. Finally, neurohormonal activation impaired mitochondrial function as indicated by the accumulation of ROS, the impaired mitochondrial membrane potential and the decrease in the ATP levels in the cardiac cells.

Conclusions

HF characteristic neurohormonal activation induced changes in the regulation of key molecules involved in iron homeostasis, reduced intracellular iron levels and impaired mitochondrial function. The current results suggest that iron could be involved in the pathophysiology of HF.

Hyperferritinemia-A Clinical Overview

Ferritin is one of the most frequently requested laboratory tests in primary and secondary care, and levels often deviate from reference ranges. Serving as an indirect marker for total body iron stores, low ferritin is highly specific for iron deficiency. Hyperferritinemia is, however, a non-specific finding, which is frequently overlooked in general practice. In routine medical practice, only 10% of cases are related to an iron overload, whilst the rest is seen as a result of acute phase reactions and reactive increases in ferritin due to underlying conditions. Differentiation of the presence or absence of an associated iron overload upon hyperferritinemia is essential, although often proves to be complex. In this review, we have performed a review of a selection of the literature based on the authors’ own experiences and assessments in accordance with international recommendations and guidelines. We address the biology, etiology, and epidemiology of hyperferritinemia. Finally, an algorithm for the diagnostic workup and management of hyperferritinemia is proposed, and general principles regarding the treatment of iron overload are discussed.

Heme Oxygenase-1 Signaling and Redox Homeostasis in Physiopathological Conditions

Heme-oxygenase is the enzyme responsible for degradation of endogenous iron protoporphyirin heme; it catalyzes the reaction’s rate-limiting step, resulting in the release of carbon monoxide (CO), ferrous ions, and biliverdin (BV), which is successively reduced in bilirubin (BR) by biliverdin reductase. Several studies have drawn attention to the controversial role of HO-1, the enzyme inducible isoform, pointing out its implications in cancer and other diseases development, but also underlining the importance of its antioxidant activity. The contribution of HO-1 in redox homeostasis leads to a relevant decrease in cells oxidative damage, which can be reconducted to its cytoprotective effects explicated alongside other endogenous mechanisms involving genes like TIGAR (TP53-induced glycolysis and apoptosis regulator), but also to the therapeutic functions of heme main transformation products, especially carbon monoxide (CO), which has been shown to be effective on GSH levels implementation sustaining body’s antioxidant response to oxidative stress. The aim of this review was to collect most of the knowledge on HO-1 from literature, analyzing different perspectives to try and put forward a hypothesis on revealing yet unknown HO-1-involved pathways that could be useful to promote development of new therapeutical strategies, and lay the foundation for further investigation to fully understand this important antioxidant system.

Iron Metabolism: An Under Investigated Driver of Renal Pathology in Lupus Nephritis

Nephritis is a common manifestation of systemic lupus erythematosus, a condition associated with inflammation and iron imbalance. Renal tubules are the work horse of the nephron. They contain a large number of mitochondria that require iron for oxidative phosphorylation, and a tight control of intracellular iron prevents excessive generation of reactive oxygen species. Iron supply to the kidney is dependent on systemic iron availability, which is regulated by the hepcidin-ferroportin axis. Most of the filtered plasma iron is reabsorbed in proximal tubules, a process that is controlled in part by iron regulatory proteins. This review summarizes tubulointerstitial injury in lupus nephritis and current understanding of how renal tubular cells regulate intracellular iron levels, highlighting the role of iron imbalance in the proximal tubules as a driver of tubulointerstitial injury in lupus nephritis. We propose a model based on the dynamic ability of iron to catalyze reactive oxygen species, which can lead to an accumulation of lipid hydroperoxides in proximal tubular epithelial cells. These iron-catalyzed oxidative species can also accentuate protein and autoantibody-induced inflammatory transcription factors leading to matrix, cytokine/chemokine production and immune cell infiltration. This could potentially explain the interplay between increased glomerular permeability and the ensuing tubular injury, tubulointerstitial inflammation and progression to renal failure in LN, and open new avenues of research to develop novel therapies targeting iron metabolism.

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.

Expression Patterns in Reductive Iron Assimilation and Functional Consequences during Phagocytosis of Lichtheimia corymbifera, an Emerging Cause of Mucormycosis

Iron is an essential micronutrient for most organisms and fungi are no exception. Iron uptake by fungi is facilitated by receptor-mediated internalization of siderophores, heme and reductive iron assimilation (RIA). The RIA employs three protein groups: (i) the ferric reductases (Fre5 proteins), (ii) the multicopper ferroxidases (Fet3) and (iii) the high-affinity iron permeases (Ftr1). Phenotyping under different iron concentrations revealed detrimental effects on spore swelling and hyphal formation under iron depletion, but yeast-like morphology under iron excess. Since access to iron is limited during pathogenesis, pathogens are placed under stress due to nutrient limitations. To combat this, gene duplication and differential gene expression of key iron uptake genes are utilized to acquire iron against the deleterious effects of iron depletion. In the genome of the human pathogenic fungus L. corymbifera, three, four and three copies were identified for FRE5, FTR1 and FET3 genes, respectively. As in other fungi, FET3 and FTR1 are syntenic and co-expressed in L. corymbifera. Expression of FRE5, FTR1 and FET3 genes is highly up-regulated during iron limitation (Fe-), but lower during iron excess (Fe+). Fe- dependent upregulation of gene expression takes place in LcFRE5 II and III, LcFTR1 I and II, as well as LcFET3 I and II suggesting a functional role in pathogenesis. The syntenic LcFTR1 I–LcFET3 I gene pair is co-expressed during germination, whereas LcFTR1 II- LcFET3 II is co-expressed during hyphal proliferation. LcFTR1 I, II and IV were overexpressed in Saccharomyces cerevisiae to represent high and moderate expression of intracellular transport of Fe3+, respectively. Challenge of macrophages with the yeast mutants revealed no obvious role for LcFTR1 I, but possible functions of LcFTR1 II and IVs in recognition by macrophages. RIA expression pattern was used for a new model of interaction between L. corymbifera and macrophages.

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.

Transcriptional Analyses of Acute Exposure to Methylmercury on Erythrocytes of Loggerhead Sea Turtle

To understand changes in enzyme activity and gene expression as biomarkers of exposure to methylmercury, we exposed loggerhead turtle erythrocytes (RBCs) to concentrations of 0, 1, and 5 mg L-1 of MeHg and de novo transcriptome were assembled using RNA-seq. The analysis of differentially expressed genes (DEGs) indicated that 79 unique genes were dysregulated (39 upregulated and 44 downregulated genes). The results showed that MeHg altered gene expression patterns as a response to the cellular stress produced, reflected in cell cycle regulation, lysosomal activity, autophagy, calcium regulation, mitochondrial regulation, apoptosis, and regulation of transcription and translation. The analysis of DEGs showed a low response of the antioxidant machinery to MeHg, evidenced by the fact that genes of early response to oxidative stress were not dysregulated. The RBCs maintained a constitutive expression of proteins that represented a good part of the defense against reactive oxygen species (ROS) induced by MeHg.

Differentially expressed proteins obtained by label-free quantitative proteomic analysis reveal affected biological processes and functions in Western diet-induced steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a pathological manifestation with a progressive incidence in response to the epidemic of hepatic steatosis caused primarily by excessive energy intake. The present study unravels affected biological processes and functions by the presence of NASH in rats using a label-free quantitative proteomic strategy. NASH was induced by a Western high-sugar and high-fat diet for 20 weeks. The liver tissue was collected for histology and for a mass spectrometry-based proteomic protocol. The NASH group showed severe lipidosis, hepatocyte ballooning, and the presence of collagen deposition. Among upregulated proteins in NASH perilipin-2 (Plin-2; F6QBA3; difference [diff]: 2.29), ferritin heavy (Fth1; Q66HI5; diff: 2.19) and light (Ftl1; P02793; diff: 1.75) chains, macrophage migration inhibitory factor 1 (Mif; P30904; diff: 1.69), and fibronectin (Fn1; F1LST1; diff: 0.35) were observed, whereas among downregulated proteins, plectin (Q6S399; diff: -3.34), some Cyp2 family proteins of the cytochrome P450 complex, glutathione S-transferases, flavin-containing monooxygenase 1 (Fmo1; P36365; diff: -2.08), acetyl-CoA acetyltransferase 2 (Acat2; Q5XI22; diff: -2.25), acyl-CoA oxidase 2 (Acox2; F1LNW3; diff: -1.59), and acyl-CoA oxidase 3 (Acox3; F1M9A7; diff: -2.41) were observed. Also, biological processes and functions such as LPS/IL-1 inhibition of RXR, fatty acid metabolism, Nrf2-mediated oxidative stress response, xenobiotic metabolism, and PXR/RXR and CAR/RXR activations were predicted to be affected. In conclusion, the liver of rats with NASH induced by Western diet shows a decreased capacity of metabolizing lipids, fatty acids, and xenobiotic compounds that predispose fibrosis development.

Serum ferritin at admission in hospitalized COVID-19 patients as a predictor of mortality

Introduction

Some COVID-19 patients have higher mortality and the responsible factors for this unfavorable outcome is still not well understood.

Objective

To study the association between ferritin levels at admission, representing an inflammatory state, and hospital mortality in COVID-19 patients.

Methods

From May through July 2020, SARS-CoV-2 positive patients with moderate to severe clinical symptoms were evaluated at admission, regarding clinical and laboratory data on renal and hepatic function, hematologic parameters, cytomegalovirus co-infection, and acute phase proteins.

Results

A total of 97 patients were included; mean age = 59.9 ± 16.3 years, 58.8% male, 57.7% non-white, in-hospital mortality = 45.4%. Age, ferritin, C-reactive protein, serum albumin and creatinine were significantly associated with mortality. Ferritin showed area under the curve (AUC) of 0.79 (p < 0.001) for the cut-off of 1873.0 ng/mL, sensitivity of 68.4% and specificity of 79.3% in predicting in-hospital mortality. Age ≥60 years had an odds ratio (OR) of 10.5 (95% CI = 1.8–59.5; p = 0.008) and ferritin ≥1873.0 ng/mL had an OR of 6.0 (95% CI = 1.4–26.2; p = 0.016), both independently associated with mortality based on logistic regression analysis.

Conclusion

The magnitude of inflammation present at admission of COVID-19 patients, represented by high ferritin levels, is independently predictive of in-hospital mortality.

Iron control of erythroid microtubule cytoskeleton as a potential target in treatment of iron-restricted anemia

Anemias of chronic disease and inflammation (ACDI) result from restricted iron delivery to erythroid progenitors. The current studies reveal an organellar response in erythroid iron restriction consisting of disassembly of the microtubule cytoskeleton and associated Golgi disruption. Isocitrate supplementation, known to abrogate the erythroid iron restriction response, induces reassembly of microtubules and Golgi in iron deprived progenitors. Ferritin, based on proteomic profiles, regulation by iron and isocitrate, and putative interaction with microtubules, is assessed as a candidate mediator. Knockdown of ferritin heavy chain (FTH1) in iron replete progenitors induces microtubule collapse and erythropoietic blockade; conversely, enforced ferritin expression rescues erythroid differentiation under conditions of iron restriction. Fumarate, a known ferritin inducer, synergizes with isocitrate in reversing molecular and cellular defects of iron restriction and in oral remediation of murine anemia. These findings identify a cytoskeletal component of erythroid iron restriction and demonstrate potential for its therapeutic targeting in ACDI.

Debilitating anemias in chronic diseases can result from deficient iron delivery to red cell precursors. Here, the authors show how this deficiency damages the cytoskeletal framework of progenitor cells and identify a targeted strategy for cytoskeletal repair, leading to anemia correction.

Transcriptomic and Histopathological Effects of Bifenthrin to the Brain of Juvenile Rainbow Trout (Oncorhynchus mykiss)

The increased global use of pyrethroids raises concern for non-target aquatic species. Bifenthrin, among the most predominantly detected pyrethroids in the environment, is frequently measured in water samples above concentrations reported to induce neuroendocrine and neurotoxic effects to several threatened and endangered fish species, such as the Chinook salmon and steelhead trout. To better characterize the neurotoxic effect of bifenthrin to salmonids, rainbow trout were treated with environmentally relevant concentrations of bifenthrin (15 and 30 ng/L) for two weeks and assessed for changes in transcriptomic profiles and histopathological alterations. The top bioinformatic pathways predicted to be impaired in bifenthrin-exposed trout were involved in gonadotropin releasing hormone signaling, the dysregulation of iron homeostasis, reduced extracellular matrix stability and adhesion, and cell death. Subsequent histopathological analysis showed a significant increase in TUNEL positive cells in the cerebellum and optic tectum of bifenthrin-treated trout, relative to controls (p < 0.05). These findings suggest that low, ng/L concentrations of bifenthrin are capable of dysregulating proper neuroendocrine function, impair the structural integrity of the extracellular matrix and cell signaling pathways in the brain, and induce apoptosis in neurons of juvenile salmonids following bifenthrin treatment, which is consistent with metabolomic profiles demonstrating a common target and mechanism.

Iron homeostasis and disorders revisited in the sepsis

Sepsis is a life-threatening condition caused by a dysregulated host-response to inflammation, although it currently lacks a fully elucidated pathobiology. Iron is a crucial trace element that is essential for fundamental processes in both humans and bacteria. During sepsis, iron metabolism is altered, including increased iron transport and uptake into cells and decreased iron export. The intracellular sequestration of iron limits its availability to circulating pathogens, which serves as a conservative strategy against the pathogens. Although iron retention has been showed to have protective protect effects, an increase in labile iron may cause oxidative injury and cell death (e.g., pyroptosis, ferroptosis) as the condition progresses. Moreover, iron disorders are substantial and correlate with the severity of sepsis. This also suggests that iron may be useful as a diagnostic marker for evaluating the severity and predicting the outcome of the disease. Further knowledge about these disorders could help in evaluating how drugs targeting iron homeostasis can be optimally applied to improve the treatment of patients with sepsis. Here, we present a comprehensive review of recent advances in the understanding of iron metabolism, focusing on the regulatory mechanisms and iron-mediated injury in sepsis.

Human Parainfluenza Virus Type 2 V Protein Modulates Iron Homeostasis

Intracellular iron concentration is tightly controlled for cell viability. It is known to affect the growth of several viruses, but the molecular mechanisms are not well understood. We found that iron chelators inhibit growth of human parainfluenza virus type 2 (hPIV-2). Furthermore, infection with hPIV-2 alters ferritin localization from granules to a homogenous distribution within cytoplasm of iron-stimulated cells. The V protein of hPIV-2 interacts with ferritin heavy chain 1 (FTH1), a ferritin subunit. It also binds to nuclear receptor coactivator 4 (NCOA4), which mediates autophagic degradation of ferritin, so-called ferritinophagy. V protein consequently interferes with interaction between FTH1 and NCOA4. hPIV-2 growth is inhibited in FTH1 knockdown cell line where severe hPIV-2-induced apoptosis is shown. In contrast, NCOA4 knockdown results in the promotion of hPIV-2 growth and limited apoptosis. Our data collectively suggest that hPIV-2 V protein inhibits FTH1-NCOA4 interaction and subsequent ferritinophagy. This iron homeostasis modulation allows infected cells to avoid apoptotic cell death, resulting in effective growth of hPIV-2.IMPORTANCE hPIV-2 V protein interferes with interaction between FTH1 and NCOA4 and inhibits NCOA4-mediated ferritin degradation, leading to the inhibition of iron release to the cytoplasm. This iron homeostasis modulation allows infected cells to avoid apoptotic cell death, resulting in effective growth of hPIV-2.

Exercise training decreases whole-body and tissue iron storage in adults with obesity

NEW FINDINGS

What is the central question of this study? Does exercise training modify tissue iron storage in adults with obesity? What is the main finding and its importance? Twelve weeks of moderate-intensity exercise or high-intensity interval training lowered whole-body iron stores, decreased the abundance of the key iron storage protein in skeletal muscle (ferritin) and tended to lower hepatic iron content. These findings show that exercise training can reduce tissue iron storage in adults with obesity and might have important implications for obese individuals with dysregulated iron homeostasis.

ABSTRACT

The regulation of iron storage is crucial to human health, because both excess and deficient iron storage have adverse consequences. Recent studies suggest altered iron storage in adults with obesity, with increased iron accumulation in their liver and skeletal muscle. Exercise training increases iron use for processes such as red blood cell production and can lower whole-body iron stores in humans. However, the effects of exercise training on liver and muscle iron stores in adults with obesity have not been assessed. The aim of this study was to determine the effects of 12 weeks of exercise training on whole-body iron stores, liver iron content and the abundance of ferritin (the key iron storage protein) in skeletal muscle in adults with obesity. Twenty-two inactive adults (11 women and 11 men; age, 31 ± 6 years; body mass index, 33 ± 3 kg/m² ) completed 12 weeks (four sessions/week) of either moderate-intensity continuous training (MICT; 45 min at 70% of maximal heart rate; n = 11) or high-intensity interval training (HIIT; 10 × 1 min at 90% of maximal heart rate, interspersed with 1 min active recovery; n = 11). Whole-body iron stores were lower after training, as indicated by decreased plasma concentrations of ferritin (P = 3 × 10^-5 ) and hepcidin (P = 0.02), without any change in C-reactive protein. Hepatic R2*, an index of liver iron content, was 6% lower after training (P = 0.06). Training reduced the skeletal muscle abundance of ferritin by 10% (P = 0.03), suggesting lower muscle iron storage. Interestingly, these adaptations were similar in MICT and HIIT groups. Our findings indicate that exercise training decreased iron storage in adults with obesity, which might have important implications for obese individuals with dysregulated iron homeostasis.

Adult-onset Still's disease evolving with multiple organ failure and death: A case report and review of the literature

BACKGROUND

Adult-onset Still’s disease (AOSD) is a rare systemic inflammatory disease, which is characterized by daily fever and arthritis, with an evanescent rash and neutrophilic leukocytosis. To date, there has been no definite laboratory or imaging test available for diagnosing AOSD; the diagnosis is one of exclusion, which can be very challenging. In particular, AOSD patients may experience different complications affecting their clinical picture, management, and prognosis. The treatment of AOSD remains largely empirical and involves therapeutic agents.

CASE SUMMARY

We report the case of a 36-year-old woman who presented with fever, red rash, arthralgia, and sore throat. Her serum ferritin level and white blood cell count were markedly elevated, and the first diagnosis 22 years prior was "juvenile rheumatoid arthritis of systemic type". The patient was treated with prednisone, sulfasalazine, methotrexate, and leflunomide. After remission of her symptoms, the patient stopped taking the medications, and the disease recurred. Ultimately, the patient was diagnosed with adult-onset Still's disease. Relapse occurred several times due to self-medication withdrawal, and an interleukin-6 antagonist (tocilizumab/Actemra) was administered to control the disease. Recently, she was hospitalized because an incision did not heal, and the patient suddenly developed high fever and diarrhea during hospitalization. The patient's disease progressed violently and quickly developed into macrophage activation syndrome, disseminated intravascular coagulation, shock, and multiple organ failure. The patient had sudden cardiac arrest, and she died despite emergency rescue efforts.

CONCLUSION

AOSD patients need regular follow-up in the long-term treatment process, and must press formulary standard medication, and do not voluntarily withdraw or reduce the dose. Otherwise it may cause disease back-and-forth or serious life-threatening complications. Meanwhile, strict management of trauma, infections, tumors, and other diseases may contribute to improved outcomes in patients with complications.

Anti-phospholipid syndrome and COVID-19 thrombosis: connecting the dots

As the coronavirus disease 2019 (COVID-19) pandemic, which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is spreading rapidly worldwide, it has emerged as a leading cause of mortality, resulting in >1 million deaths over the past 10 months. The pathophysiology of COVID-19 remains unclear, posing a great challenge to the medical management of patients. Recent studies have reported an unusually high prevalence of thromboembolic events in COVID-19 patients, although the mechanism remains elusive. Several studies have reported the presence of aPLs in COVID-19 patients. We have noticed similarities between COVID-19 and APS, which is an autoimmune prothrombotic disease that is often associated with an infective aetiology. Molecular mimicry and endothelial dysfunction could plausibly explain the mechanism of thrombogenesis in acquired APS. In this review, we discuss the clinicopathological similarities between COVID-19 and APS, and the potential role of therapeutic targets based on the anti-phospholipid model for COVID-19 disease.

New Insights into the Role of Ferritin in Iron Homeostasis and Neurodegenerative Diseases

Growing evidence has indicated that iron deposition is one of the key factors leading to neuronal death in the neurodegenerative diseases. Ferritin is a hollow iron storage protein composed of 24 subunits of two types, ferritin heavy chain (FTH) and ferritin light chain (FTL), which plays an important role in maintaining iron homeostasis. Recently, the discovery of extracellular ferritin and ferritin in exosomes indicates that ferritin might be not only an iron storage protein within the cell, but might also be an important factor in the regulation of tissue and body iron homeostasis. In this review, we first described the structural characteristics, regulation and the physiological functions of ferritin. Secondly, we reviewed the current evidence concerning the mechanisms underlying the secretion of ferritin and the possible role of secreted ferritin in the brain. Then, we summarized the relationship between ferritin and the neurodegenerative diseases including Parkinson's disease (PD), Alzheimer's disease (AD) and neuroferritinopathy (NF). Given the importance and relationship between iron and neurodegenerative diseases, understanding the role of ferritin in the brain can be expected to contribute to our knowledge of iron dysfunction and neurodegenerative diseases.

Apolipoprotein E deficiency induces a progressive increase in tissue iron contents with age in mice

Association of both iron/hepcidin and apolipoprotein E (ApoE) with development of Alzheimer disease (AD) and atherosclerosis led us to hypothesize that ApoE might be required for body iron homeostasis. Here, we demonstrated that ApoE knock-out (KO) induced a progressive accumulation of iron with age in the liver and spleen of mice. Subsequent investigations showed that the increased iron in the liver and spleen was due to phosphorylated extracellular regulated protein kinases (pERK) mediated up-regulation of transferrin receptor 1 (TfR1), and nuclear factor erythroid 2-related factor-2 (Nrf2)-dependent down-regulation of ferroportin 1. Furthermore, replenishment of ApoE could partially reverse the iron-related phenotype in ApoE KO mice. The findings imply that ApoE may be essential for body iron homeostasis and also suggest that clinical late-onset diseases with unexplained iron abnormality may partly be related to deficiency or reduced expression of ApoE.

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Apolipoprotein E deficiency induces a progressive increase in tissue iron contents with age in mice.

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ApoE−/− induced a progressive accumulation of iron with age in the liver and spleen of mice.

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The increased iron was due to upregulation of TfR1 and downregulation of Fpn1.

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Replenishment of ApoE could partially reverse the iron-related phenotype in ApoE KO mice.

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ApoE may be essential for body iron homeostasis.

Glycosylated ferritin as an improved marker for post-transfusion iron overload

Red blood cell (RBC) transfusion is an effective therapy for anemia, but repeated transfusions may cause iron overload-related damage to various organs. Iron chelation therapy, now widely available for patients who have received transfusions, is expected to reduce organ damage even in patients who received many transfusions. Therefore, determining when to start iron chelation therapy is important. In guidelines for iron chelation therapy, the serum ferritin level has been widely accepted as a practical marker for estimating iron overload. However, guidelines recommend multiple measurements of serum ferritin, because levels often fluctuate. Here, we investigated the usefulness of glycosylated ferritin as a marker of iron overload using a cohort consisted of 103 patients who had a total ferritin value over 1000 ng/mL. We found that the volume of RBCs transfused was clearly associated with the glycosylated ferritin level. We also found that acute inflammation, as represented by C-reactive protein values, was associated with increased non-glycosylated ferritin and that patients with hematopoietic diseases had higher glycosylated ferritin levels, possibly because of repeated RBC transfusions. We thus conclude that glycosylated ferritin may be an improved marker for predicting iron overload status.

Prepregnancy hemoglobin levels and gestational diabetes mellitus in pregnancy

AIM

To identify the influence of prepregnancy hemoglobin levels on gestational diabetes mellitus.

MATERIALS AND METHODS

Korean women who had given birth between January 1st, 2006 and December 31st, 2015 and who had undergone a biannual national health screening examination within 6 months prior to pregnancy were enrolled. Subjects were divided into three groups according to their hemoglobin levels. Multivariate logistic regression analysis was used to estimate the adjusted odds ratio and 95% confidence interval for GDM.

RESULTS

Of the 366,122 participants, GDM developed in 14,799 (4%) women. More specifically, GDM developed in 3.6% of women with prepregnancy anemia (hemoglobin < 11 g/dL), 3.57% with normal hemoglobin levels, and 4.47% with hemoglobin levels higher than 13 g/dL. We did not find any association between prepregnancy anemia and the risk of developing GDM (OR 1.002 [95% CI 0.90-1.11]). After adjusting for potential confounding factors (adjusted odds ratio 1.41; 95% CI 1.29-1.54), high hemoglobin levels were associated with insulin requiring GDM.

CONCLUSIONS

Our study identified an association between high prepregnancy hemoglobin levels and GDM risk.

Iron Homeostasis and Metabolism: Two Sides of a Coin

Iron is an ancient, essential and versatile transition metal found in almost all living organisms on Earth. This fundamental trace element is used in the synthesis of heme and iron-sulfur (Fe-S) containing proteins and other vital cofactors that are involved in respiration, redox reactions, catalysis, DNA synthesis and transcription. At the same time, the ability of iron to cycle between its oxidized, ferric (Fe³⁺) and its reduced, ferrous (Fe²⁺) state contributes to the production of free radicals that can damage biomolecules, including proteins, lipids and DNA. In particular, the regulated non-apoptotic cell death ferroptosis is driven by Fe²⁺-dependent lipid peroxidation that can be prevented by iron chelation or genetic inhibition of cellular iron uptake. Therefore, iron homeostasis must be tightly regulated to avoid iron toxicity. This review provides an overview of the origin and chemistry of iron that makes it suitable for a variety of biological functions and addresses how organisms evolved various strategies, including their scavenging and antioxidant machinery, to manage redox-associated drawbacks. Finally, key mechanisms of iron metabolism are highlighted in human diseases and model organisms, underlining the perils of dysfunctional iron handlings.

Inhibition of ferroptosis by up-regulating Nrf2 delayed the progression of diabetic nephropathy

Diabetic nephropathy (DN) is now considered the leading cause of end-stage renal disease. In diabetes, the accumulation of reactive oxygen species (ROS) and iron overload are important determinants that promote the occurrence of DN. However, the underlying mechanism of how they cause diabetic kidney damage remains unclear. Ferroptosis, characterized by iron-dependent lipid peroxidation, provided us with a new idea to explore the progression of DN. Iron overload, reduced antioxidant capability, massive ROS and lipid peroxidation were detected in the kidneys of streptozotocin-induced DBA/2J diabetic mice and high-glucose cultured human renal proximal tubular (HK-2) cells, which were the symbolic changes of ferroptosis. Furthermore, the characteristic mitochondrial morphological changes of ferroptosis were observed in high glucose cultured cells. Additional treatment of Ferrostatin-1 (Fer-1) in DN models significantly rescued these changes and alleviated the renal pathological injuries in diabetic mice. Besides, the decreased NFE2-related factor 2 (Nrf2) was observed in DN models. The specific knockdown of Nrf2 increased the sensitivity of cells to ferroptosis in the high glucose condition. In Nrf2 knockdown cells, up-regulating Nrf2 by treating with fenofibrate improved the situation of ferroptosis, which was verified in RSL-3 induced cells. Moreover, the ferroptosis-related changes were inhibited by increasing Nrf2 in fenofibrate treated diabetic mice, which delayed the progression of DN. Collectively, we demonstrated that ferroptosis was involved in the development of DN, and up-regulating Nrf2 by treating with fenofibrate inhibited diabetes-related ferroptosis, delaying the progression of DN. Our research revealed the development mechanism of DN from a new perspective, and provide a new approach delaying the progression of DN.

Outcome Predictive Value of Serum Ferritin in ICU Patients with Long ICU Stay

Background and Objectives: The simplified interpretation of serum ferritin levels, according to which low ferritin levels indicate iron deficiency and high levels indicate hemochromatosis is obsolete, as in the presence of inflammation serum ferritin levels, no longer correlate with iron stores. However, further data are needed to interpret serum ferritin levels correctly in patients with ongoing inflammation. Our study aimed to assess serum iron and ferritin dynamics in patients with long ICU stay and the possible correlations with organ dysfunction progression and outcome. Materials and Methods: We conducted a prospective study in a university hospital intensive care unit (ICU) over six months. All patients with an ICU length-of-stay of more than seven days were enrolled. Collected data included: demographics, Sequential Organ Failure Assessment (SOFA) score, admission, weekly serum iron and ferritin levels, ICU length-of-stay and outcome. Interactions between organ dysfunction progression and serum iron and ferritin levels changes were investigated. Outcome predictive value of serum ferritin was assessed. Results: Seventy-two patients with a mean ICU length-of-stay of 15 (4.4) days were enrolled in the study. The average age of patients was 62 (16.8) years. There were no significant differences between survivors (39 patients, 54%) and nonsurvivors (33 patients, 46%) regarding demographics, serum iron and ferritin levels and SOFA score on ICU admission. Over time, serum iron levels remained normal or low, while serum ferritin levels statedly increased in all patients. Serum ferritin increase was higher in nonsurvivors than survivors. There was a significant positive correlation between SOFA score and serum ferritin (r = 0.7, 95%CI for r = 0.64 to 0.76, p < 0.01). The predictive outcome accuracy of serum ferritin was similar to the SOFA score. Conclusions: In patients with prolonged ICU stay, serum ferritin dynamics reflects organ dysfunction progression and parallels SOFA score in terms of outcome predictive accuracy.

Diagnosis and management of iron deficiency in chronic inflammatory conditions (CIC): is too little iron making your patient sick?

While iron deficiency remains the most common cause of anemia worldwide, low iron stores are associated with symptoms regardless of the presence of typical microcytic, hypochromic anemia and may be hard to recognize in patients with concurrent inflammation. Diagnosing and treating iron deficiency become more of a challenge because markers of iron status are influenced by low-grade inflammation present in common conditions, such as chronic kidney disease, cirrhosis, or heart failure. Here I present a pragmatic way of interpreting diagnostic lab tests to help clinicians recognize patients who are most likely to benefit from iron supplementation, choose between oral and parenteral administration, and make personalized decisions when patients do not fit usual guidelines.

Heme Oxygenase-1 in Gastrointestinal Tract Health and Disease

Heme oxygenase 1 (HO-1) is the rate-limiting enzyme of heme oxidative degradation, generating carbon monoxide (CO), free iron, and biliverdin. HO-1, a stress inducible enzyme, is considered as an anti-oxidative and cytoprotective agent. As many studies suggest, HO-1 is highly expressed in the gastrointestinal tract where it is involved in the response to inflammatory processes, which may lead to several diseases such as pancreatitis, diabetes, fatty liver disease, inflammatory bowel disease, and cancer. In this review, we highlight the pivotal role of HO-1 and its downstream effectors in the development of disorders and their beneficial effects on the maintenance of the gastrointestinal tract health. We also examine clinical trials involving the therapeutic targets derived from HO-1 system for the most common diseases of the digestive system.

Supplementation of a low-energy diet with recombinant ferritin fromPerinereissp. can be beneficial to finishing pigs

A total of 90 finishing pigs [(Yorkshire × Landrace) × Duroc] with an average body weight (BW) of 50.02 ± 1.78 kg were used in a 10 wk experiment. The pigs were distributed into three dietary treatments replicated six times with five pigs (two barrows and three gilts) per pen. The treatment diets were a positive control (PC; high-energy diet), a negative control (NC; low-energy diet), and an NC + 0.05% ferritin diet (TRT1). The supplementation of ferritin in a low-energy diet tended (P = 0.06) to increase the BW at week 5 compared with pigs fed low-energy diets without ferritin. At week 5 and overall period, the gain-to-feed ratio of pigs fed high-energy diets was higher (P < 0.05) compared with pigs fed low-energy diets. The pigs receiving a ferritin-supplemented diet had a comparable growth performance to pigs fed high-energy diets. At week 10, fecal Lactobacilli counts of pigs fed high-energy diets were higher (P < 0.05) compared with pigs fed low-energy diets. The supplementation of low-energy diets with ferritin resulted in comparable growth performance to pigs fed high-energy diets and had no adverse effect on digestibility and fecal gas emissions. Thus, it seems beneficial to include ferritin in low-energy diets of finishing pigs.

Expression of four new ferritins from grooved carpet shell clam Ruditapes decussatus challenged with Perkinsus olseni and metals (Cd, Cu and Zn)

Iron has a fundamental role in life and in its biochemical reactions but, when in excess, it can promote the formation of free radicals which can lead to cell death. Therefore, managing the levels of iron is essential to regulate the production of oxidative stress related to iron, and ferritins are one of the main protein families involved in this process. Ferritins are ≈480 kDa multimeric proteins composed by 24 subunits, each with 19-26 kDa, which can accumulate up to 4500 iron atoms. Besides their role in managing iron bioavailability, they have also developed a role in organism immunity and defence present throughout evolution. In this work, we identified and characterized, for the first time, four different ferritin subunits in the clam Ruditapes decussatus, a bivalve commercially and ecologically important along the south Atlantic coast and in the Mediterranean basin, which is a major target of the parasitic protozoa Perkinsus olseni, considered one of the main causes of high levels of clam mortality. Following phylogenetic annotation, the four ferritins subunits identified were subdivided into two cytosolic and two secreted forms. All four subunits maintain the canonical ferritin structure with four main helices α (A-D) and a small helix (E), but the secreted ferritins present an additional helix in their N-terminal region (F), located after the signal peptide and with possible antimicrobial properties. Additionally, we identified in ferritin 4 an extra helix α (G) located between helices B and C. These alpha helix domains revealed high degree of similarity with antimicrobial peptides associated with antibacterial and antifungal activities. Analysis of the expression of these subunits showed that ferritins 1 and 2 are ubiquitously expressed while ferritins 3 and 4 are present mainly in visceral mass. Ferritin 1 lacked a putative functional iron response element (IRE) and appeared to be under a tight regulation. Ferritins 2 and 3 showed a strong response to infection by parasite Perkinsus olseni in contrast to ferritin 4, whose main response was related to exposure to a combination of metals. The synergistic effect between metals and infection promoted a general upregulation of the four ferritins. In conclusion, our results suggest that ferritins, besides their function in iron and metals detoxification, may play a determinant role in clam immune response.

Iron Dysregulation in Human Cancer: Altered Metabolism, Biomarkers for Diagnosis, Prognosis, Monitoring and Rationale for Therapy

Simple Summary

Iron is the more abundant metal ion in humans. It is essential for life as it has a role in various cellular processes involved, for instance, in cell metabolism and DNA synthesis. These functions are crucial for cell proliferation, and it is therefore not surprising that iron is accumulated in tumors. In this review, we describe normal and altered iron homeostasis mechanisms. We also provide a vision of iron-related proteins with altered expression in cancers and discuss their potential as diagnostic and/or prognostic biomarkers. Finally, we give an overview of therapeutic strategies acting on iron metabolism to fight against cancers.

Abstract

Iron (Fe) is a trace element that plays essential roles in various biological processes such as DNA synthesis and repair, as well as cellular energy production and oxygen transport, and it is currently widely recognized that iron homeostasis is dysregulated in many cancers. Indeed, several iron homeostasis proteins may be responsible for malignant tumor initiation, proliferation, and for the metastatic spread of tumors. A large number of studies demonstrated the potential clinical value of utilizing these deregulated proteins as prognostic and/or predictive biomarkers of malignancy and/or response to anticancer treatments. Additionally, the iron present in cancer cells and the importance of iron in ferroptosis cell death signaling pathways prompted the development of therapeutic strategies against advanced stage or resistant cancers. In this review, we select relevant and promising studies in the field of iron metabolism in cancer research and clinical oncology. Besides this, we discuss some co-existing discrepant findings. We also present and discuss the latest lines of research related to targeting iron, or its regulatory pathways, as potential promising anticancer strategies for human therapy. Iron chelators, such as deferoxamine or iron-oxide-based nanoparticles, which are already tested in clinical trials, alone or in combination with chemotherapy, are also reported.

In silico Insights on IL-6: A Potential Target for Multicentric Castleman Disease

Background:

Multicentric Castleman Disease (MCD) is a confrontational lymphoproliferative disorder described by symptoms such as lymph node proliferation, unwarranted secretion of inflammatory cytokines, hyperactive immune system, and in severe cases, multiple organ dysfunction. Interleukin-6 (IL-6) is a pleiotropic cytokine which is involved in a large range of physiological processes in our body such as pro-inflammation, anti-inflammation, differentiation of T-cells and is reported to be a key pathological factor in MCD. In the case of MCD, it was observed that IL-6 is overproduced from T-cells and macrophages which disturb Hepcidin, a vital regulator of iron trafficking in macrophage. The present study endeavour to expound the inhibitor which binds to IL-6 protein receptor with high affinity.

Methods:

MolegroVirtual Docker software was employed to find the best-established drug from the list of selected inhibitors of IL-6. This compound was subjected to virtual screening against PubChem database to get inhibitors with a very similar structure. These inhibitors were docked to obtain a compound binding with high affinity to the target protein. The established compound and the virtual screened compound were subjected to relative analysis of interactivity energy variables and ADMET profile studies.

Results:

Among all the selected inhibitors, the virtual screened compound PubChem CID: 101119084 is seen to possess the highest affinity with the target protein. Comparative studies and ADMET analysis further implicate this compound as a better inhibitor of the IL-6 protein.

Conclusion:

Hence, this compound recognized in the study possesses high potential as an IL-6 inhibitor which might assist in the treatment of Multicentric Castleman Disease and should be examined for its efficiency by in vivo studies.

Effect of iron oxide nanoparticles on vascular function and nitric oxide production in acute stress-exposed rats

We investigated whether polyethylene glycol-coated Fe3O4 nanoparticles (IONs), acute stress and their combination modifies vascular functions, nitric oxide synthase (NOS) activity, mean arterial pressure (MAP) as well as hepcidin and ferritin H gene expressions in Wistar-Kyoto rats. Rats were divided into control, ION-treated rats (1 mg Fe/kg i.v.), repeated acute air-jet stress-exposed rats and IONs-and-stress co-exposed rats. Maximal acetylcholine (ACh)-induced and sodium nitroprusside (SNP)-induced relaxations in the femoral arteries did not differ among the groups. IONs alone significantly elevated the N?-nitro-L-arginine methyl ester (L-NAME)-sensitive component of ACh-induced relaxation and reduced the sensitivity of vascular smooth muscle cells to SNP. IONs alone also elevated NOS activity in the brainstem and hypothalamus, reduced NOS activity in the kidneys and had no effect in the liver. Acute stress alone failed to affect vascular function and NOS activities in all the tissues investigated but it elevated ferritin H expression in the liver. In the ION-and-stress group, NOS activity was elevated in the kidneys and liver, but reduced in the brainstem and hypothalamus vs. IONs alone. IONs also accentuated air-jet stress-induced MAP responses vs. stress alone. Interestingly, stress reduced ION-originated iron content in blood and liver while it was elevated in the kidneys. In conclusion, the results showed that 1) acute administration of IONs altered vascular function, increased L-NAME-sensitive component of ACh-induced relaxation and had tissue-dependent effects on NOS activity, 2) ION effects were considerably reduced by co-exposure to repeated acute stress, likely related to decrease of ION-originated iron in blood due to elevated decomposition and/or excretion.

Iron depletion with deferoxamine protects bone marrow-derived mesenchymal stem cells against oxidative stress-induced apoptosis

Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent cells with self-renewal properties, making them an ideal candidate for regenerative medicine. Recently, numerous studies show that about more than 99% of transplanted cells are destroyed because of the stressful microenvironment. Meanwhile, in the target organs, iron overload can produce oxidative stress introducing it as the most important stress factor. The present study was aimed at increasing BM-MSCs' viability against oxidative stress microenvironment using iron depletion by deferoxamine (DFO). Mesenchymal stem cells are isolated and characterized from rat bone marrow. Then, the sensitivity of BM-MSCs against H2O2-induced oxidative stress was evaluated through half of the inhibitory concentration (IC50) estimation by using MTT assay. The maximum non-inhibitory concentration of DFO on BM-MSCs was determined. The next step was the comparison between DFO pre-treated BM-MSCs and untreated cells against H2O2-induced apoptosis. BM-MSCs were identified with morphologic and flow cytometry analysis. IC50 of H2O2 was determined as 0.55 mM at 4 h. Also, the maximum non-inhibitory concentration of DFO was ascertained as 5 μM at 48 h. Our results demonstrated that pretreatment with DFO significantly potentiates BM-MSCs against H2O2-induced oxidative stress which was confirmed by MTT assay, AO/EB double staining, DAPI staining, and activated caspase 3 quantification as well as western blot test. Expression of cleaved caspase 3 and pAKT/AKT ratio obviously demonstrated DFO can resist the cells against cytotoxicity. These findings may help to develop better stem cell culture medium for MSC-based cell therapy. Moreover, regulation of cell stress can be used in practical subjects.

Characterization of recombinant protein ferritin from Pyropia yezoensis (rPyFer) and its biological activities

Ferritins are iron-binding proteins that are basically participated in iron storage, detoxification, and immune response. In the present study, ferritin gene from the marine red algae Pyropia yezoensis was cloned into a pET21d expression vector. High-efficiency transformation was performed in Escherichia coli BL21, the recombinant protein was expressed by induction with 0.1 mM isopropyl-β-D-thiogalactoside and purified via ammonium sulfate precipitation, anion exchange and size exclusion chromatography. The purified recombinant ferritin from P. yezoensis (rPyFer) was characterized and analyzed for its antimicrobial activity against both Gram-negative and Gram-positive bacterial cultures and exhibited significant antibacterial activity against Gram-positive cultures. The recombinant protein was also analyzed for its iron-uptake and radical-scavenging activities; rPyFer exhibited significant iron-uptake activity at low concentrations, and its radical-scavenging activity increased in a dose-dependent manner. This research will contribute to the development of new therapeutic proteins from marine algae.

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.

Exacerbation of Neonatal Hemolysis and Impaired Renal Iron Handling in Heme Oxygenase 1-Deficient Mice

In most mammals, neonatal intravascular hemolysis is a benign and moderate disorder that usually does not lead to anemia. During the neonatal period, kidneys play a key role in detoxification and recirculation of iron species released from red blood cells (RBC) and filtered out by glomeruli to the primary urine. Activity of heme oxygenase 1 (HO1), a heme-degrading enzyme localized in epithelial cells of proximal tubules, seems to be of critical importance for both processes. We show that, in HO1 knockout mouse newborns, hemolysis was prolonged despite a transient state and exacerbated, which led to temporal deterioration of RBC status. In neonates lacking HO1, functioning of renal molecular machinery responsible for iron reabsorption from the primary urine (megalin/cubilin complex) and its transfer to the blood (ferroportin) was either shifted in time or impaired, respectively. Those abnormalities resulted in iron loss from the body (excreted in urine) and in iron retention in the renal epithelium. We postulate that, as a consequence of these abnormalities, a tight systemic iron balance of HO1 knockout neonates may be temporarily affected.

Higher iron stores and the HFE 187C>G variant delay onset of peripheral neuropathy during combination antiretroviral therapy

OBJECTIVE

People with HIV (PWH) continue to experience sensory neuropathy and neuropathic pain in the combination antiretroviral therapy (cART) era for unclear reasons. This study evaluated the role of iron in a previously reported association of iron-loading hemochromatosis (HFE) gene variants with reduced risk of neuropathy in PWH who received more neurotoxic cART, since an iron-related mechanism also might be relevant to neuropathic symptoms in PWH living in low-resource settings today.

DESIGN

This time-to-event analysis addressed the impact of systemic iron levels on the rapidity of neuropathy onset in PWH who initiated cART.

METHODS

Soluble transferrin receptor (sTFR), the sTFR-ferritin index of iron stores, and high-sensitivity C-reactive protein (hsCRP) levels were determined in stored baseline sera from participants of known HFE genotype from AIDS Clinical Trials Group (ACTG) Study 384, a multicenter randomized clinical trial that evaluated cART strategies. Associations with incident neuropathy were evaluated in proportional-hazards, time-to-event regression models, adjusting for potential confounders.

RESULTS

Of 151 eligible participants with stored serum who were included in the original genetic study, 43 had cART-associated neuropathy; 108 had sufficient serum for analysis, including 30 neuropathy cases. Carriers of HFE variants had higher systemic iron (lower sTFR and sTFR-ferritin index) and lower hsCRP levels than non-carriers (all p<0.05). Higher sTFR or iron stores, the HFE 187C>G variant, and lower baseline hsCRP were associated with significantly delayed neuropathy in self-reported whites (n = 28; all p-values<0.05), independent of age, CD4+ T-cell count, plasma HIV RNA, and cART regimen.

CONCLUSIONS

Higher iron stores, the HFE 187C>G variant, and lower hsCRP predicted delayed onset of neuropathy among self-reported white individuals initating cART. These findings require confirmation but may have implications for cART in HIV+ populations in areas with high endemic iron deficiency, especially those PWH in whom older, more neurotoxic antiretroviral drugs are occasionally still used.

FTH1 Inhibits Ferroptosis Through Ferritinophagy in the 6-OHDA Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons associated with dysregulation of iron homeostasis in the brain. Ferroptosis is an iron-dependent cell death process that serves as a significant regulatory mechanism in PD. However, its underlying mechanisms are not yet fully understood. By performing RNA sequencing analysis, we found that the main iron storage protein ferritin heavy chain 1 (FTH1) is differentially expressed in the rat 6-hydroyxdopamine (6-OHDA) model of PD compared with control rats. Our present work demonstrates that FTH1 is involved in iron accumulation and the ferroptosis pathway in this model. Knockdown of FTH1 in PC-12 cells significantly inhibited cell viability and caused mitochondrial dysfunction. Moreover, FTH1 was found to be involved in ferritinophagy, a selective form of autophagy involving the degradation of ferritin by ferroptosis. Overexpression of FTH1 in PC-12 cells impaired ferritinophagy and downregulated microtubule-associated protein light chain 3 and nuclear receptor coactivator 4 expression, ultimately suppressing cell death induced by ferroptosis. Consistent with these findings, the ferritinophagy inhibitors chloroquine and bafilomycin A1 inhibited ferritin degradation and ferroptosis in 6-OHDA-treated PC-12 cells. This entire process was mediated by the cyclic regulation of FTH1 and ferritinophagy. Taken together, these results suggest that FTH1 links ferritinophagy and ferroptosis in the 6-OHDA model of PD, and provide a new perspective and potential for a pharmacological target in this disease.

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.

Ferritin in the coronavirus disease 2019 (COVID-19): A systematic review and meta-analysis

OBJECTIVE

The coronavirus disease 2019 (COVID-19) has rapidly developed into a pandemic. Increased levels of ferritin due to cytokine storm and secondary hemophagocytic lymphohistiocytosis were found in severe COVID-19 patients. Therefore, the aim of this study was to determine the role of ferritin in COVID-19.

METHODS

Studies investigating ferritin in COVID-19 were collected from PubMed, EMBASE, CNKI, SinoMed, and WANFANG. A meta-analysis was performed to compare the ferritin level between different patient groups: non-survivors versus survivors; more severe versus less severe; with comorbidity versus without comorbidity; ICU versus non-ICU; with mechanical ventilation versus without mechanical ventilation.

RESULTS

A total of 52 records involving 10 614 COVID-19-confirmed patients between December 25, 2019, and June 1, 2020, were included in this meta-analysis, and 18 studies were included in the qualitative synthesis. The ferritin level was significantly increased in severe patients compared with the level in non-severe patients [WMD 397.77 (95% CI 306.51-489.02), P < .001]. Non-survivors had a significantly higher ferritin level compared with the one in survivors [WMD 677.17 (95% CI 391.01-963.33), P < .001]. Patients with one or more comorbidities including diabetes, thrombotic complication, and cancer had significantly higher levels of ferritin than those without (P < .01). Severe acute liver injury was significantly associated with high levels of ferritin, and its level was associated with intensive supportive care, including ICU transfer and mechanical ventilation.

CONCLUSIONS

Ferritin was associated with poor prognosis and could predict the worsening of COVID-19 patients.