Iron homeostasis in host defence and inflammation

Exploring the gut microbiome’s influence on cancer-associated anemia: Mechanisms, clinical challenges, and innovative therapies

BACKGROUND

Anemia is a prevalent and challenging complication in patients with hematologic and solid malignancies, which stems from the direct effects of malignancy, treatment-induced toxicities, and systemic inflammation. It affects patients’ survival, functional status, and quality of life profoundly. Recent literature has highlighted the emerging role of the gut microbiome in the pathogenesis of cancer-associated anemia. The gut microbiota, through its intricate interplay with iron metabolism, inflammatory pathways, and immune modulation, may either exacerbate or ameliorate anemia depending on its composition, and functional integrity. Dysbiosis, characterized by disruption in the gut microbial ecosystem, is very common in cancer patients. This microbial imbalance is implicated in anemia causation through diminished iron absorption, persistent low-grade inflammation, and suppression of erythropoiesis.

AIM

To consolidate current evidence regarding the interplay between gut microbiome and anemia in the setting of malignancies. It aims to provide a detailed exploration of the mechanistic links between dysbiosis and anemia, identifies unique challenges associated with various cancer types, and evaluates the efficacy of microbiome-focused therapies. Through this integrative approach, the review seeks to establish a foundation for innovative clinical strategies aimed at mitigating anemia and improving patient outcomes in oncology.

METHODS

A literature search was performed using multiple databases, including Google Scholar, PubMed, Scopus, and Web of Science, using a combination of keywords and Boolean operators to refine results. Keywords included “cancer-associated anemia”, “gut microbiome”, “intestinal microbiota”, “iron metabolism”, “gut dysbiosis”, “short-chain fatty acids”, “hematopoiesis”, “probiotics”, “prebiotics”, and “fecal microbiota transplantation”. Articles published in English between 2000 and December 2024 were included, with a focus on contemporary and relevant findings.

RESULTS

Therapeutic strategies aimed at restoration of gut microbial homeostasis, such as probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation (FMT), can inhibit anemia-causing pathways by enhancing microbial diversity, suppressing detrimental flora, reducing systemic inflammation and optimizing nutrient absorption.

CONCLUSION

Gut dysbiosis causes anemia and impairs response to chemotherapy in cancer patients. Microbiome-centered interventions, such as probiotics, prebiotics, dietary modifications, and FMT, have shown efficacy in restoring microbial balance, reducing inflammation, and enhancing nutrient bioavailability. Emerging approaches, including engineered probiotics and bacteriophage therapies, are promising precision-based, customizable solutions for various microbiome compositions and imbalances. Future research should focus on integrating microbiome-targeted strategies with established anemia therapies.

Simultaneous functional disruption of the iron acquisition system and type VI secretion system results in complete suppression of virulence in Acinetobacter baumannii

Acinetobacter baumannii (Ab) is one of the most significant bacterial pathogens inducing hospital-acquired infections worldwide, with a high mortality rate. The continuous emergence of multidrug-resistant (MDR) phenotypes presents a significant challenge in combating Ab infections with antimicrobial drugs. In this study, we found that the type VI secretion system and the iron transportation system synergistically enhance siderophore production and further contribute to the virulence of Ab. The double knockout mutant strain, ΔhcpΔbasE, exhibited further reductions in growth rate, siderophore production under iron-deficient conditions, biofilm formation, serum resistance, cell adhesion and invasion, and cytotoxicity compared to the single knockout strains, knockout of T6SS, Δhcp or iron transportation system, ΔbasE. In vitro experiments demonstrated that these two systems work synergistically to enhance virulence, with their combined effect exceeding the additive contributions of each individual system. Consistently, the ΔhcpΔbasE strain failed to cause mortality in the mouse model, even at very high inoculum levels. Further studies revealed that, compared to ATCC17978, ΔhcpΔbasE strain infection resulted in lower levels of extracellular hepcidin and intracellular iron in host cells, which correlate well with the significantly reduced ability to produce siderophores in the double knockout strain. Due to impaired iron acquisition, ΔhcpΔbasE strain became more susceptible to macrophage phagocytosis and exhibited lower survival rates in the host, leading to an inability to trigger a cytokine storm and subsequent host death. The findings of this study provide insights into the Ab pathogenesis and contribute to the development of intervention measures to control clinical Ab infections and mortality.

Iron metabolism in rheumatic diseases

Iron is a crucial element for living organism in terms of oxygen transport, hematopoiesis, enzymatic activity, mitochondrial respiratory chain function and also immune system function. The human being has evolved a mechanism to regulate body iron. In some rheumatic diseases such as rheumatoid arthritis (RA), systemic lupus erythematous (SLE), systemic sclerosis (SSc), ankylosing spondylitis (AS), and gout, this balanced iron regulation is impaired. Altered iron homeostasis can contribute to disease progression through ROS production, fibrosis, inflammation, abnormal bone homeostasis, NETosis and cell senescence. In this review, we have focused on the iron metabolism in rheumatic disease and its role in disease progression.

Heme and immunity: The heme oxygenase dichotomy

Heme, an iron containing organic ring, is required for a diverse range of biological processes across all forms of life. Although this nutrient is essential, its pro-inflammatory and cytotoxic properties can lead to cellular damage. Heme oxygenase 1 (HO-1) is an endoplasmic reticulum (ER)-anchored enzyme that degrades heme, releasing equimolar amounts of carbon monoxide (CO), biliverdin (BV), and iron. The induction of HO-1 by heme presents an interesting dichotomy in the cell: CO and BV possess anti-inflammatory and antioxidant properties while free iron can be detrimental as it can generate hydroxyl radicals through the Fenton reaction. The heme/HO-1 axis is tightly regulated, and can influence cell fate, local tissue environments, and disease outcomes during pathogen infection. In this review we explore the role of heme during macrophage polarization and its ability to act as an immune activator while also examining the contribution of HO-1 and heme during infections with intracellular and extracellular pathogens. We highlight work from the emerging field of nutritional immunity of heme and iron, and how the substrates and byproducts of heme metabolism via HO-1 can be beneficial to the host or the pathogen depending on the context.

Iron acquisition strategies in pathogenic fungi

Iron plays a crucial role in various biological processes, including enzyme function, DNA replication, energy production, oxygen transport, lipid, and carbon metabolism. Although it is abundant in the Earth's crust, its bioavailability is restricted by the insolubility of ferric iron (Fe³+) and the auto-oxidation of ferrous iron (Fe²+) in oxygen-rich environments. This limitation poses significant challenges for all organisms, including fungi, which have developed intricate mechanisms for iron acquisition and utilization. These mechanisms include reductive iron uptake, siderophore production/transport, and heme utilization. Fungi employ a variety of enzymes-such as ferric reductases, ferroxidases, permeases, and transporters-to regulate intracellular iron levels effectively. The challenge is heightened for pathogenic fungi during infection, as they must compete with the host's iron-binding proteins like transferrin and lactoferrin, which sequester iron to restrict pathogen growth. This review delves into the iron acquisition strategies of medically important fungi, emphasizing the roles of reductive iron uptake and siderophore pathways. Understanding these mechanisms is vital for enhancing our knowledge of fungal pathogenesis and developing effective treatments. By targeting these iron acquisition processes, new antifungal therapies can be formulated more effectively to combat fungal infections.

McFerritin cooperates with McNrf2 to attenuate benzo[a]pyrene-induced oxidative stress in the thick-shell mussel Mytilus coruscus

Benzo[a]pyrene (B[a]P), a pervasive polycyclic aromatic hydrocarbon (PAH), induces oxidative stress and cellular damage in marine organisms, posing significant ecological risks. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of antioxidant defenses, yet its interaction with ferritin-a critical iron storage protein-remains poorly understood in mollusks. Here, we identified a novel ferritin homolog, McFerritin, in the thick-shelled mussel Mytilus coruscus and investigated its role in B[a]P-induced oxidative stress. Quantitative PCR revealed that McFerritin expression in the adductor muscle was 4.37-fold higher than in the gills, with 5.58 to 9.11-fold upregulation observed in the digestive glands and mantles post-B[a]P exposure. GST pull-down assays confirmed the direct interaction of McFerritin with McNrf2. RNAi experiments demonstrated reciprocal regulation: knockdown of McFerritin increased McNrf2 expression by 1.55-fold and 1.70-fold, while silencing McNrf2 elevated McFerritin levels by 1.30-fold and 1.34-fold in DMSO-treated samples. Silencing either gene resulted in increased apoptosis rates (5.1 % and 13.2 %), enhanced reactive oxygen species (ROS) accumulation (1.26- and 1.79-fold), and decreased activities of antioxidant enzymes (T-AOC, SOD, CAT), underscoring their synergistic role in oxidative stress mitigation. This study elucidates the protective role of Ferritin in M. coruscus, confirming the interaction between McFerritin and McNrf2 in mediating defense mechanisms against oxidative stress, thereby advancing understanding of oxidative stress regulation in marine invertebrates and emphasizing their potential as biomarkers for assessing PAH toxicity in coastal ecosystems.

Genetic profile of ferroptosis in non-small cell lung carcinoma and pharmaceutical options for ferroptosis induction

Lung cancer (LC) is the leading cause of cancer-related deaths and the second most commonly diagnosed malignancy worldwide. Lung adenocarcinoma (LUAD) and lung squamous cell LC (LUSCC) are the most common subtypes of non-small cell LC (NSCLC). Early diagnosis of LC can be challenging due to a lack of biomarkers. The overall survival (OS) of patients with NSCLC is still poor despite the enormous efforts that have been made to develop novel treatments. Understanding fundamental molecular and genetic mechanisms is necessary to develop new therapeutic approaches for NSCLC. A recently identified type of programmed cell death known as ferroptosis is one potential approach. Ferroptosis causes oxidative damage and the death of cancerous cells by peroxidizing unsaturated phospholipids and accumulating reactive oxygen species (ROS) in an iron-dependent manner. Ferroptosis-related gene (FRG) signatures have recently been evaluated for their ability to predict patient OS and prognosis. These analyses show FRGs are involved in cancer progression, and may serve as promising biomarkers for tumor diagnosis and therapy. Moreover, we summarize the current pharmaceutical options of ferroptosis induction and their underlying molecular mechanism in LC. Therefore, this review aims to provide a comprehensive summary of FRG-based prognostic models, their associated metabolic and signaling pathways, and promising therapeutic options for ferroptosis induction in NSCLC.

Salivary iron and Candida colonization in oral lichen planus patients undergoing topical steroid therapy

BACKGROUND

The most common adverse event in oral lichen planus (OLP) patients undergoing topical corticosteroid therapy is opportunistic infection with oral Candida. Oral candidiasis superimposed on OLP can worsen the patient's symptoms and obscure the true clinical appearance making the treatment of OLP more complex and difficult. The aim of this study was to investigate the salivary iron level in OLP patients undergoing topical steroid therapy with a history of oral candidiasis compared with OLP patients undergoing topical steroid therapy without a history of oral candidiasis and healthy individuals.

MATERIALS AND METHODS

The 68 OLP patients treated with a topical steroid were divided into 34 OLP patients with a history of oral candidiasis, 34 OLP patients without a history of oral candidiasis and 34 healthy individuals were enrolled in the study. Unstimulated whole saliva was collected from the participants to determine the salivary iron level and to investigate the presence of oral Candida colonization.

RESULTS

The salivary iron level was significantly higher in OLP patients undergoing topical steroid therapy with a history of oral candidiasis compared with OLP patients undergoing topical steroid therapy without a history of oral candidiasis and healthy individuals (P = 0.04 and P < 0.001, respectively). Moreover, the Candida colony count in OLP patients undergoing topical steroid therapy with a history of oral candidiasis was significantly higher compared with OLP patients undergoing topical steroid therapy without a history of oral candidiasis and healthy Individuals (P < 0.001 and P < 0.001, respectively).

CONCLUSION

High salivary iron level associates with a high amount of oral Candida colonization in OLP patients undergoing topical steroid therapy with a history of oral candidiasis.

TRIAL REGISTRATION

This study was registered at the Thai Clinical Trials Registry on 2nd June 2022 (TCTR identifier: TCTR20220602006).

Targeting the epigenetic regulation of ferroptosis: a potential therapeutic approach for sepsis-associated acute kidney injury

Sepsis is a syndrome of organ dysfunction caused by the invasion of pathogenic microorganisms. In clinical practice, patients with sepsis are prone to concurrent acute kidney injury, which has high morbidity and mortality rates. Thus, understanding the pathogenesis of sepsis-associated acute kidney injury is of significant clinical importance. Ferroptosis is an iron-dependent programmed cell death pathway, which is proved to play a critical role in the process of sepsis-associated acute kidney injury through various mechanisms. Epigenetic regulation modulates the content and function of nucleic acids and proteins within cells through various modifications. Its impact on ferroptosis has garnered increasing attention; however, the role of epigenetic regulation targeting ferroptosis in sepsis-associated acute kidney injury has not been fully elucidated. Growing evidence suggests that epigenetic regulation can modulate ferroptosis through complex pathway networks, thereby affecting the development and prognosis of sepsis-associated acute kidney injury. This paper summarizes the impact of ferroptosis on sepsis-associated acute kidney injury and the regulatory mechanisms of epigenetic regulation on ferroptosis, providing new insights for the targeted therapy of sepsis-associated acute kidney injury.

Transferrin from obscure puffer Takifugu obscurus promotes antimicrobial immune response

Transferrin (TF) is an iron-binding glycoprotein that plays a crucial role in host defense by restricting iron availability to pathogens and activating antimicrobial immune responses. However, its antimicrobial role in fish remains largely unexplored. In this study, we identified and characterized transferrin from obscure puffer Takifugu obscurus, named ToTF, and investigated its functions in bacterial infections. The coding region of the ToTF gene consists of 2295 bp, encoding a polypeptide of 764 amino acids. Tissue distribution analysis revealed that ToTF is primarily expressed in the liver. The mRNA expression of ToTF was significantly upregulated in both the liver and kidney following challenge with Staphylococcus aureus and Vibrio harveyi. Moreover, recombinant ToTF (rToTF) markedly inhibits iron-dependent bacteria growth, including S. aureus and V. harveyi. The iron-binding capacity of rToTF peaked at pH 8 and decreased significantly under acidic conditions. Furthermore, the antibacterial activity of rToTF peaked at near-neutral pH but decreased significantly at pH below 5. This dual mechanism deprives bacteria of essential iron through high-affinity binding and directly inhibits their growth under optimal conditions. These findings highlight the dual role of ToTF in the antibacterial immunity of T. obscurus, mediated by iron sequestration and direct bacteriostatic effects. This study supports the development of TF-based antibacterial agents and enhances strategies for aquatic disease prevention and fish disease resistance.

The role of monocytes and macrophages in idiopathic inflammatory myopathies: insights into pathogenesis and potential targets

Idiopathic inflammatory myopathies (IIMs) are heterogeneous autoimmune disorders characterized by muscle inflammation, weakness, and extramuscular manifestations such as interstitial lung disease, skin rash, arthritis, dysphagia, myocarditis and other systemic organ involvement. Although T and B cells have historically been central to the understanding of IIM immunopathology, monocytes and their differentiated progenitor cells, macrophages, are increasingly being recognized as critical mediators of both tissue damage and repair. In subtypes such as dermatomyositis, immune-mediated necrotizing myopathy and antisynthetase syndrome, macrophages infiltrate skeletal muscle and other affected tissues, contributing to inflammation via production of pro-inflammatory cytokines, chemokines, and reactive oxygen species. Dysregulated interferon signaling, mitochondrial stress, and aberrant metabolic states in these cells further perpetuate tissue injury in IIMs. Conversely, certain macrophage subsets can support muscle fiber regeneration and dampen inflammation, underscoring the dual roles these cells can play. Future research into the heterogeneity of monocytes and macrophages, including single-cell transcriptomic and metabolomic approaches, will help clarify disease mechanisms, identify biomarkers of disease activity and prognosis, and guide novel therapeutic strategies targeting these innate immune cells in IIM.

The interaction of nutrient uptake with biotic and abiotic stresses in plants

Plants depend heavily on efficient nutrient uptake and utilization for optimal growth and development. However, plants are constantly subjected to a diverse array of biotic stresses, such as pathogen infections, insect pests, and herbivory, as well as abiotic stress like drought, salinity, extreme temperatures, and nutrient imbalances. These stresses significantly impact the plant's ability to take up nutrient and use it efficiency. Understanding how plants maintain nutrient uptake and use efficiency under biotic and abiotic stress conditions is crucial for improving crop resilience and sustainability. This review explores the recent advancements in elucidating the mechanisms underlying nutrient uptake and utilization efficiency in plants under such stress conditions. Our aim is to offer a comprehensive perspective that can guide the breeding of stress-tolerant and nutrition-efficient crop varieties, ultimately contributing to the advancement of sustainable agriculture.

The BRUTUS iron sensor and E3 ligase facilitates soybean root nodulation by monoubiquitination of NSP1

Legumes form root nodules with symbiotic nitrogen-fixing rhizobacteria, which require ample iron to ensure symbiosis establishment and efficient nitrogen fixation. The functions and mechanisms of iron in nitrogen-fixing nodules are well established. However, the role of iron and the mechanisms by which legumes sense iron and incorporate this cue into nodulation signalling pathways remain unclear. Here we show that iron is a key driver of nodulation because symbiotic nodules cannot form without iron, even under conditions of sufficient light and low nitrogen. We further identify an iron optimum for soybean nodulation and the iron sensor BRUTUS A (BTSa) which acts as a hub for integrating iron and nodulation cues. BTSa is induced by rhizobia, binds to and is stabilized by iron. In turn, BTSa stabilizes and enhances the transcriptional activation activity of pro-nodulation transcription factor NSP1a by monoubiquitination from its RING domain and consequently activates nodulation signalling. Monoubiquitination of NSP1 by BTS is conserved in legumes to trigger nodulation under iron sufficiency. Thus, iron status is an essential cue to trigger nodulation and BTSa integrates cues from rhizobial infection and iron status to orchestrate host responses towards establishing symbiotic nitrogen fixation.

Targeting metabolic dysfunction of CD8 T cells and natural killer cells in cancer

The importance of metabolic pathways in regulating immune responses is now well established, and a mapping of the bioenergetic metabolism of different immune cell types is under way. CD8 T cells and natural killer (NK) cells contribute to cancer immunosurveillance through their cytotoxic functions and secretion of cytokines and chemokines, complementing each other in target recognition mechanisms. Several immunotherapies leverage these cell types by either stimulating their activity or redirecting their specificity against tumour cells. However, the anticancer activity of CD8 T cells and NK cells is rapidly diminished in the tumour microenvironment, closely linked to a decline in their metabolic capacities. Various strategies have been developed to restore cancer immunosurveillance, including targeting bioenergetic metabolism or genetic engineering. This Review provides an overview of metabolic dysfunction in CD8 T cells and NK cells within the tumour microenvironment, highlighting current therapies aiming to overcome these issues.

Iron metabolism dysfunction in neuropsychiatric disorders: Implications for therapeutic intervention

Iron is a trace metal that takes part in the maintenance of body homeostasis by, for instance, aiding in energy production and immunity. A body of evidence now demonstrates that dysfunction in iron metabolism can have detrimental effects and is intricately associated with the development of neuropsychiatric disorders, including Major Depressive Disorder (MDD), anxiety, and schizophrenia. For instance, changes in serum and central nervous system (CNS) levels of iron and in proteins mediating iron metabolism have been documented in patients grappling with the aforementioned diseases. By contrast, targeting iron metabolism by using iron chelators, for instance, has proven to be effective in alleviating disease burden. Therefore, here we review the state-of-the-art regarding the role of iron metabolism and its dysfunction in the context of neuropsychiatric disorders. Furthermore, we discuss how targeting iron metabolism can be an effective therapeutic option to tackle this class of diseases. Finally, we discuss the mechanisms linking this dysfunction to behavioral changes in these disorders. Harnessing the knowledge of iron metabolism is not only key to the characterization of novel molecular targets and disease biomarkers but also crucial to drug repurposing and drug design.

Identification of a protective antigen reveals the trade-off between iron acquisition and antigen exposure in a global fungal pathogen

Systemic infections caused by Cryptococcus claim over 161,000 lives annually, with global mortality rate close to 70% despite antifungal therapies. Currently, no vaccine is available. To develop an effective multivalent vaccine against this free-living opportunistic eukaryotic pathogen, it is critical to identify protective antigens. We previously discovered ZNF2oe strains elicit protective host immune responses and increase the abundance of antigens present in the capsule, which is required for its immunoprotection. Capsule is a defining feature of Cryptococcus species and composed of polysaccharides and mannoproteins. Here, we found increased levels of exposed mannoproteins in ZNF2oe cells. As mannoproteins are the primary components recognized by anticryptococcal cell-mediated immune responses and few have been characterized, we systemically screened all 49 predicted GPI-mannoproteins in Cryptococcus neoformans for enhanced host recognition. We identified those highly present in ZNF2oe cells and found Cig1 to be a protective antigen against cryptococcosis either as a recombinant protein vaccine or an mRNA vaccine. Cig1 is induced by iron limitation and is highly expressed by this fungus in infected mice and in patients with cryptococcal meningitis. Remarkably, iron restriction by the host induces cryptococcal cells to express iron-uptake proteins including Cig1, which act as cryptococcal antigens and in turn enhance host detection. Our results highlight an arms race between the pathogen and the host centered on iron competition, and the trade-off between cryptococcal iron acquisition and antigen exposure. These findings demonstrate the potential of leveraging this host-pathogen interaction for vaccine development.

Barriers and carriers for transition metal homeostasis in plants

Transition metals are types of metals with high chemical activity. They play critical roles in plant growth, development, reproduction, and environmental adaptation, as well as in human health. However, the acquisition, transport, and storage of these metals pose specific challenges due to their high reactivity and poor solubility. In addition, distinct yet interconnected apoplastic and symplastic diffusion barriers impede their movement throughout plants. To overcome these obstacles, plants have evolved sophisticated carrier systems to facilitate metal transport, relying on the tight coordination of vesicles, enzymes, metallochaperones, low-molecular-weight metal ligands, and membrane transporters for metals, ligands, and metal-ligand complexes. This review highlights recent advances in the homeostasis of transition metals in plants, focusing on the barriers to transition metal transport and the carriers that facilitate their passage through these barriers.

Transferrin promotes fatty acid oxidation and liver tumor growth through PHD2-mediated PPARα hydroxylation in an iron-dependent manner

Tumor cells reshape iron and lipid metabolism for their rapid proliferation. However, how tumor cells coordinate the interplay between tumor cell-specific iron homeostasis and lipid metabolism reprogramming to counteract energy shortages remains unclear. Here, we demonstrated that glucose deprivation in hepatocellular carcinoma (HCC) cells induced AMPK-dependent Transferrin S685 phosphorylation, which exposed Transferrin nuclear localization signal (NLS) for binding to importin α7 and subsequent nuclear translocation. Nucleus-translocated Transferrin interacts with PPARα and enhance its protein stability to increase fatty acid oxidation (FAO) upon glucose deprivation. Mechanistically, PPARα-associated Transferrin upregulates iron-dependent PHD2-mediated PPARα P87 hydroxylation and subsequently disrupts the binding of MDM2 to PPARα, therefore inhibiting MDM2-mediated PPARα ubiquitination and degradation. Reconstitution of Transferrin S685A and NLS mutation or knock-in expression of PPARα P87A inhibited PPARα-mediated FAO upon energy stress, enhanced HCC cell apoptosis, and impeded liver tumor growth in mice. Importantly, combined treatment with Transferrin pS685 blocking peptide suppressing AMPK-Transferrin-PPARα axis could synergize with a well-established AMPK activator Metformin to inhibit tumor growth. Additionally, Transferrin pS685-mediated PPARα P87 hydroxylation is positively correlated with PPARα expression levels in human HCC specimens and poor patient prognosis. These findings revealed a mechanism by which Transferrin can sense energy stress to promote the hydroxylation and protein stability of PPARα through iron-dependent activation of PHD2 and underscore the moonlighting function of Transferrin in lipid catabolism and liver tumor development.

Iron Deficiency and All-Cause Hospitalization Risk in a Clinical Cohort of COPD

Background

The impact of iron deficiency on COPD morbidity independent of anemia status is unknown. Understanding the association between iron deficiency, anemia status, and risk of hospitalization in COPD may inform an approach to these comorbidities.

Study Design and Methods

Adults ≥40 years from the Johns Hopkins COPD Precision Medicine Center of Excellence data repository with an outpatient iron profile and 1 year of subsequent follow-up time were included in the study. Baseline characteristics were compared across iron status, defined by transferrin saturation (TSAT), using t-tests and Chi-squared tests. The association between continuous TSAT and all-cause hospitalization over the 1-year follow-up period was assessed by logistic regression. Models were adjusted by covariates with an interaction term for anemia and stratified by sex.

Results

There were 6532 individuals included with an average age of 65±12 years, 59% were female, and 56% White. Fifty-two percent of the cohort were iron deficient (TSAT≤20%), among whom 27% were non-anemic. Iron-deficient individuals had lower lung function and a higher prevalence of heart failure and diabetes. Iron deficiency was more prevalent among females (57%) compared to males (44%). In adjusted models, a decrease in TSAT by 10% was associated with 14.3% higher odds of all-cause hospitalization for females (95%CI:1.0-1.3), but not among males (OR:1.08, 95%CI:0.9-1.3). There was effect modification by anemia such that the association between TSAT and all-cause hospitalization was greater in non-anemic women (p-value interaction=0.08).

Interpretation

Iron deficiency may be associated with adverse outcomes in the absence of anemia, with non-anemic women being a COPD sub-population particularly sensitive to iron deficiency.

IRG1/Itaconate inhibits hepatic stellate cells ferroptosis and attenuates TAA-induced liver fibrosis by regulating SLC39A14 expression

This study aimed to elucidate the protective roles of Immune Response Gene-1 (IRG1) and exogenous itaconate in murine models of hepatic fibrosis and to delineate the underlying mechanistic pathways using both wild-type and IRG1-deficient (IRG1-/-) mice. Primary murine stellate cells (mHSC) and bone marrow-derived macrophages (BMDM) were isolated and cocultured. Hepatocellular fibrosis was induced in vitro using Transforming Growth Factor-beta (TGF-β) to evaluate the protective efficacy of IRG1/itaconate. Histopathological damage in the hepatic tissues was assessed using Hematoxylin and Eosin (H&E), Masson's trichrome, and Sirius red staining, followed by hepatic fibrosis scoring. The levels of released inflammatory cytokines were quantified using enzyme-linked immunosorbent assay (ELISA) kits. Immunohistochemistry was used to detect 4-Hydroxynonenal (4-HNE) levels and Perls staining was used to assess ferroptosis. RNA sequencing and gene enrichment analyses were performed to identify implicated molecular entities and signaling pathways. IRG1 and SLC39A14 knockdown and overexpression cell lines were generated. Quantitative real-time PCR (qRT-PCR) and western blotting (WB) were used to measure the mRNA and protein expression levels in hepatic tissues and cells. Kits were used to assess reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and the concentrations of liver enzymes, iron, GSH, and GSSG within hepatic tissues and cells.4-octyl itaconate (4-OI) significantly attenuated the histopathological damage in hepatic tissues, preserved the normal hepatic function, effectively reduced the release of inflammatory cytokines, and mitigated oxidative stress markers such as ROS and MDA in Thioacetamide (TAA)-induced fibrotic mice. Notably, this study is the first to reveal the pivotal role of SLC39A14 in the pathogenesis of hepatic fibrosis in murine models and elucidate how IRG1/itaconate mediates downstream ferroptosis-related signaling pathways by targeting SLC39A14, thereby inhibiting ferroptosis-induced hepatic fibrosis. IRG1/itaconate can alleviate the TAA-induced hepatic fibrosis in mice by regulating the expression of SLC39A14, consequently suppressing hepatic stellate cell ferroptosis.

Circadian metabolic adaptations to infections

Circadian clocks are biological oscillators that evolved to coordinate rhythms in behaviour and physiology around the 24-hour day. In mammalian tissues, circadian rhythms and metabolism are highly intertwined. The clock machinery controls rhythmic levels of circulating hormones and metabolites, as well as rate-limiting enzymes catalysing biosynthesis or degradation of macromolecules in metabolic tissues, such control being exerted both at the transcriptional and post-transcriptional level. During infections, major metabolic adaptation occurs in mammalian hosts, at the level of both the single immune cell and the whole organism. Under these circumstances, the rhythmic metabolic needs of the host intersect with those of two other players: the pathogen and the microbiota. These three components cooperate or compete to meet their own metabolic demands across the 24 hours. Here, we review findings describing the circadian regulation of the host response to infection, the circadian metabolic adaptations occurring during host-microbiota-pathogen interactions and how such regulation can influence the immune response of the host and, ultimately, its own survival.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

What do we know about micronutrients in critically ill patients? A narrative review

Micronutrient (MN) status alterations (both depletion and deficiency) are associated with several complications and worse outcomes in critically ill patients. On the other side of the spectrum, improving MN status has been shown to be a potential co-adjuvant therapy. This review aims to collect existing data to better guide research in the critical care setting. This narrative review was conducted by the European Society of Intensive Care Medicine Feeding, Rehabilitation, Endocrinology, and Metabolism MN group. The primary objective was to identify studies focusing on individual MNs in critically ill patients, selecting the MNs that appear to be most relevant and most frequently investigated in the last decade: A, B1, B2, B3, B6, folate, C, D, E, copper, iron, selenium, zinc, and carnitine. Given the limited number of interventional studies for most MNs, observational studies were included. For each selected MN, the review summarizes the main form and functions, special needs and risk factors, optimal treatment strategies, pharmacological dosing, and clinical implications all specific to critically ill patients. A rigorous rebalancing of research strategies and priorities is needed to improve clinical practice. An important finding is that high-dose monotherapy of MNs is not recommended. Basal daily needs must be provided, with higher doses in diseases with known higher needs, and identified deficiencies treated. Finally, the review provides a list of ongoing trials on MNs in critically ill patients and identifies a priority list of future research topics.

Cefiderocol Resistance Conferred by Plasmid-Located Ferric Citrate Transport System in KPC-Producing Klebsiella pneumoniae

Cefiderocol (FDC), a siderophore-cephalosporin conjugate, is the newest option for treating infection with carbapenem-resistant gram-negative bacteria. We identified a novel mechanism contributing to decreased FDC susceptibility in Klebsiella pneumoniae clinical isolates. The mechanism involves 2 coresident plasmids: pKpQIL, carrying variants of blaKPC carbapenemase gene, and pKPN, carrying the ferric citrate transport (FEC) system. We observed increasing FDC MICs in an Escherichia coli model system carrying different natural pKpQIL plasmids, encoding different K. pneumoniae carbapenemase (KPC) variants, in combination with a conjugative low copy number vector carrying the fec gene cluster from pKPN. We observed transcriptional repression of fiu, cirA, fepA, and fhuA siderophore receptor genes in blaKPC-fec-E. coli cells treated with ferric citrate. Screening of 27,793 K. pneumoniae whole-genome sequences revealed that the fec cluster occurs frequently in some globally distributed different KPC-producing K. pneumoniae clones (sequence types 258, 14, 45, and 512), contributing to reduced FDC susceptibility.

A ferrous fluorescence lifetime response probe for monitoring changes in lipid droplets during ferroptosis and imaging in liver disease model

Ferrous ions (Fe2⁺) accumulation and abnormal alterations in lipid droplets (LDs) are closely associated with ferroptosis. In the liver, excessive iron accumulation promotes oxidative stress and exacerbates lipid droplet accumulation, while the disruption of iron homeostasis may also affect the formation and size of lipid droplets, their increased number and size can exacerbate the severity of disease under fatty liver conditions. The leads to hepatocyte damage, further triggering liver inflammation, fibrosis, and ultimately resulting in cirrhosis and hepatocellular carcinoma. Therefore, real-time monitoring of iron ion and lipid droplet changes is crucial for assessing the severity of liver disease, disease progression, and understanding the mechanisms of ferroptosis. We have developed a fluorescent probe, NRFep, for real-time monitoring of iron ion fluctuations and visualization of lipid droplet changes in ferroptosis and liver disease models. NRFep is specific and sensitive to iron ions and exhibits excellent stability in both cells and animal models. In addition, NRFep can be used to monitor changes in iron ions and lipid droplets in mouse liver injury and fatty liver models. Through fluorescence lifetime imaging technology, NRFep can also study the dynamic changes of intracellular iron ion content. NRFep provides a powerful tool for studying ferroptosis and related diseases, and its unique dual-monitoring function opens up new possibilities for developing new diagnostic and therapeutic strategies.

Translating evidence into practice: Managing electrolyte imbalances and iron deficiency in heart failure

Mineral abnormalities are a common complication of heart failure (HF). In particular, dyskalaemia, hyponatraemia, and hypomagnesaemia are prevalent, with hypo- and hyperkalaemia observed in over 40 % of HF patients, hyponatraemia in 18-27 %, hypomagnesaemia in 7-52 %, and phosphate imbalance in 13 %. These abnormalities serve as indicators of the severity of HF and are strongly associated with an increased risk of morbidity and mortality. The neurohumoral activation, including the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system, and vasopressin, HF medications such as diuretics and RAAS inhibitors, amd concomitant diseases such as chronic kidney disease, can disrupt mineral homeostasis. Iron deficiency (ID) is another of the most common mineral abnormalities, affecting up to 60 % of HF patients. ID is significantly associated with adverse clinical outcomes such as reduced quality of life and exercise capacity, HF re-hospitalization, and all-cause mortality. Various pathways contribute to the development of ID in HF, including reduced iron intake due to anorexia, increased hepcidin levels associated with chronic inflammation and hepatic congestion, and occult gastrointestinal bleeding due to the concomitant use of antithrombotic agents. The efficacy of iron replacement therapy has been demonstrated in clinical trials, particularly in heart failure with reduced ejection fraction (HFrEF), whilst more recently, it has also been shown to improve exercise capacity in patients with heart failure with preserved ejection fraction (HFpEF). This review focuses on potassium and phosphate abnormalities, hyponatraemia, hypomagnesaemia, and ID in HF, providing a comprehensive overview of the mechanisms, clinical significance, and intervention strategies with the latest findings.

Ferritinophagy mediated by the AMPK/ULK1 pathway is involved in ferroptosis subsequent to ventilator-induced lung injury

Mechanical ventilation (MV) remains a cornerstone of critical care; however, its prolonged application can exacerbate lung injury, leading to ventilator-induced lung injury (VILI). Although previous studies have implicated ferroptosis in the pathogenesis of VILI, the underlying mechanisms remain unclear. This study investigated the roles of ferritinophagy in ferroptosis subsequent to VILI. Using C57BL/6J mice and MLE-12 cells, we established both in vivo and in vitro models of VILI and cyclic stretching (CS)-induced cellular injury. We assessed lung injury and the biomarkers of ferroptosis and ferritinophagy, after appropriate pretreatments. This study demonstrated that high tidal volumes (HTV) for 4 h enhanced the sensitivity to ferroptosis in both models, evidenced by increased intracellular iron levels, lipid peroxidation and cell death, which can be mitigated by ferrostatin-1 treatment. Notably, nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy contributed to ferroptosis in VILI. Inhibition of autophagy with 3-methyladenine or NCOA4 knockdown decreased intracellular Fe2+ levels and inhibited lipid peroxidation, thereby attenuating CS-induced lung injury. Furthermore, it has also been observed that the AMPK/ULK1 axis can trigger ferritinophagy in VILI. Collectively, our study indicated that MV can induce ferroptosis by promoting NCOA4-dependent ferritinophagy, which could be a novel therapeutic target for the prevention and treatment of VILI.

Iron nutrition and COVID-19 among Nigerian healthcare workers

Background and objectives

The optimal iron hypothesis (OIH) posits that risk for infection is lowest at a mild level of iron deficiency. The extent to which this protection results from arms race dynamics in the evolution of iron acquisition and sequestration mechanisms is unclear. We evaluated the OIH with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an emerging infectious agent.

Methodology

We tested 304 healthcare workers at baseline for iron deficiency (zinc protoporphyrin:heme), anemia (hemoglobin), and SARS-CoV-2 (salivary PCR), and followed them for ~3 months with biweekly SARS-CoV-2 tests. We fit logistic regression models based on Akaike Information Criterion.

Results

Adequate data were available for 199 participants. Iron replete (OR: 2.87, 95% CI: 0.85, 9.75) and anemia (OR: 2.48; 95% CI: 0.82, 7.85) were associated with higher risk for SARS-CoV-2 infection after control for covariates. Logistic regression and Cox proportional hazards models of the SARS-CoV-2 outcome were similar. Anemia (OR: 1.81; 95% CI: 0.88, 3.71) was associated with respiratory symptoms regardless of SARS-CoV-2 infection.

Conclusions and implications

These findings provide partial support for the OIH: SARS-CoV-2 infection risk was elevated at the high end of the range of iron availability; however, the elevated risk among those with anemia was not, as expected, specific to severe iron deficiency. Narrowly, for COVID-19 epidemiology, these findings accord with evidence that SARS-CoV-2's ability to establish infection is enhanced by access to iron. More broadly, these findings suggest that the OIH does not hinge on a long history of evolutionary arms race dynamics in access to host iron.

Phosphorus-independent role of FGF23 in erythropoiesis and iron homeostasis

A number of studies have reported an association between phosphorus, red blood cell (RBC) production, and iron metabolism. However, it is difficult to distinguish whether the effect of phosphorus is direct or through the actions of FGF23, and it is not clear whether phosphorus is positively or negatively associated with RBC production. In the present study, we investigated the effects of a) increased phosphorus load and b) phosphorus deficiency on erythropoiesis and iron metabolism in association with FGF23. Mice were fed either a 1.2% or 1.65% phosphorus diet and compared to mice fed a control diet containing 0.6% of phosphorus. Moreover, we used two mouse models of hypophosphatemia-induced either by dietary intervention in the form of a low phosphorus (LP) diet (0.02% of Pi) or genetically in a mouse model of X-linked hypophosphatemia (XLH)-that had opposite FGF23 levels. Phosphorus supplementation appropriately increased FGF23 levels leading to excretion of excess phosphorus and normalization of serum phosphorus levels. We also found that a phosphorus-rich diet results in inflammation-induced hypoferremia associated with reduced iron export leading to tissue iron overload. Moreover, high phosphorus intake results in ineffective erythropoiesis caused by decreased production (decreased RBCs, hemoglobin, hematocrit, and erythroid progenitors in the bone marrow) and increased destruction of RBCs, leading to anemia despite increased EPO secretion. These complications occur through the actions of elevated FGF23 in the presence of normophosphatemia. Our data also show that LP diet induces a decrease in the serum concentrations of phosphorus and FGF23, resulting in increased RBC counts, hemoglobin concentration, and hematocrit compared to mice fed normal diet. Moreover, serum iron and transferrin saturation were increased and positively correlated with serum ferritin, liver ferritin protein and mRNA expression in mice fed LP diet. However, hyp mice, the murine model of XLH, exhibit hypophosphatemia and high serum FGF23 levels, along with low number of circulating RBCs, hemoglobin, and hematocrit compared to wild-type mice. In the bone marrow, hyp mice showed reduced number of erythroid progenitors and formed significantly less BFU-E colonies compared to control mice. Serum iron levels and transferrin saturation were also decreased in hyp mice in comparison to control mice. Taken together, our data show that FGF23 acts independent of phosphorus levels to regulate erythropoiesis and iron homeostasis.

Comparative Evaluation of Salivary Ferritin Levels as a Predictor Inflammatory Biomarker Before and After Non Surgical Periodontal Therapy- An Interventional Study

Background

Ferritin plays a crucial role in the host immune response, with elevated serum ferritin levels established in various chronic inflammation-related diseases, including periodontitis. This study aimed to evaluate the efficacy of nonsurgical periodontal treatment on salivary ferritin levels in periodontally healthy and chronic periodontitis patients.

Materials and Methods

Fifty patients were selected and divided into two groups: a control group of healthy individuals and an experimental group of chronic periodontitis patients. Salivary samples were collected using the drooling method to assess ferritin levels. The experimental group underwent nonsurgical periodontal therapy, with clinical parameters [plaque index (PI), gingival index (GI), oral hygiene index-simplified (OHIS), bleeding point index (BPI), probing pocket depth (PPD), and clinical attachment level (CAL)] recorded before and one month after therapy. Salivary samples were analyzed using CLIA, and statistical analysis was performed.

Results

The control group showed significantly lower ferritin levels compared to the periodontitis group. Post-therapy, the periodontitis group exhibited significant improvements in both clinical parameters and ferritin levels.

Conclusion

Salivary ferritin levels effectively predict periodontal disease and the impact of periodontal therapy, demonstrating its potential as a valuable biomarker for diagnosing and monitoring periodontal health.

Synthesis of 3-hydroxy-4-pyridinone hexadentate chelators, and biophysical evaluation of their affinity towards lipid bilayers

Iron is an essential micronutrient for almost every living organism, namely pathogenic bacteria. In an infection scenario, host-pathogen competitive relationships for the element are present and Fe withholding is a well known response of the host. Also, bacterial resistance is a major concern that can compromise public health and the WHO underlines an urgent need to search for new pharmaceutical ingredients or strategies to fight opportunistic bacteria. Iron metabolism, and in particular, deprivation is a strategy that currently constitutes another option to fight bacterial infection. In this work we report the synthesis of a new hexadentate chelator with enhanced hydrophilicity (MRHT) and the improved synthesis of two other chelators. The affinity towards charged and non-charged phospholipid bilayers was evaluated for three hexadentate chelators: MRHT, CP256 and RH8b using NMR and EPR spectroscopies. The results revealed that these structures, bearing 3,4-HPO units have a high affinity towards the hydrophilic region of the phospholipid bilayer. From the three hexadentate chelators, MRHT stood out, especially for liposomes with a charged surface, suggesting that this molecule could more efficiently compete with natural siderophores, creating an iron gradient near bacteria organisms.

Hepcidin as a therapeutic target in iron overload

INTRODUCTION

Dysregulation of the hepcidin-ferroportin axis is a hallmark in the pathogenesis of iron overload, ultimately leading to end-organ injury. Hereditary hemochromatosis and iron-loading anemias are characterized by a hepcidin deficiency, making hepcidin a novel therapeutic target for preventing and managing iron overload.

AREAS COVERED

Modulators of hepcidin expression and molecules mimicking hepcidin are emerging as highly promising therapeutic strategies. We present a summary of results from preclinical and clinical trials of such therapies in models of iron overload.

EXPERT OPINION

Current treatment alternatives in iron overload fail to address the underlying hepcidin deficiency - and may even exacerbate it. Until hepcidin-targeting therapies become available, several challenges remain, including the need to optimize dosing in order to manage the narrow treatment window and improving specificity in targeting iron metabolism pathways exclusively. Long-term studies are crucial to fully assess both the benefits and risks of these therapies and to explore their potential utility in combination with existing treatment guidelines. Furthermore, these therapies are expected to have applications, particularly in addressing other iron-maldistributed disorders, as seen in anemia of chronic disease and inflammation.

Iron homeostasis and neurodegeneration in the ageing brain: Insight into ferroptosis pathways

Ageing is a major risk factor for various chronic diseases and offers a potential target for developing novel and broadly effective preventatives or therapeutics for age-related conditions, including those affecting the brain. Mechanisms contributing to ageing have been summarized as the hallmarks of ageing, with iron imbalance being one of the major factors. Ferroptosis, an iron-mediated lipid peroxidation-induced programmed cell death, has recently been implicated in neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). Addressing ferroptosis offers both opportunities and challenges for treating neurodegenerative diseases, though the specific mechanisms remain unclear. This research explores the key processes behind how ferroptosis contributes to brain ageing, with a focus on the complex signaling networks that are involved. The current article aims to uncover that how ferroptosis, a specific type of cell death, may drive age-related changes in the brain. Additionally, the article also unveils its role in neurodegenerative diseases, discussing how understanding these mechanisms could open up new therapeutic avenues.

Iron Deficiency and Renal Phosphate Handling: The Role of Maximal Tubular Reabsorption of Phosphate Normalized to Glomerular Filtration Rate (TmP/GFR) in Proximal Tubular Dysfunction

BACKGROUND AND AIM

Phosphate dysregulation is often associated with chronic kidney disease (CKD), and recent studies suggest that it may also be present in non-CKD patients with systemic conditions including iron deficiency anemia. This study aimed to evaluate the relationship between iron deficiency parameters (total iron-binding capacity {TIBC}, hemoglobin, and serum ferritin) and markers of proximal tubular dysfunction (the maximal tubular reabsorption of phosphate normalized to glomerular filtration rate {TmP/GFR} and tubular reabsorption of phosphate {TRP}) in non-CKD patients with iron deficiency anemia.

METHODS

This was a hospital-based analytical cross-sectional study conducted in the outpatient department and/or inpatient wards of the Department of Internal Medicine, Swaroop Rani Nehru (SRN) Hospital associated with Moti Lal Nehru (MLN) Medical College, Prayagraj, Uttar Pradesh, India, between July 2023 and August 2024.

RESULTS

This study analyzed 40 anemic patients without CKD, with a mean age of 33.9 years. Most participants (n=24, 60%) were aged 18-35 years, and the majority (n=27, 67.5%) were female. Peripheral smear analysis revealed that 72.5% (n=29) had microcytic hypochromic anemia. Hemoglobin levels averaged 7.7 g/dL, serum iron was 91.0 µg/dL, total iron-binding capacity (TIBC) was 316.3 µg/dL, and serum ferritin was 199.7 ng/mL. Phosphate handling was assessed with TmP/GFR and tubular reabsorption of phosphate (TRP) showing mean values of 4.1 mg/dL and 99.2%, respectively. This study found that TmP/GFR had a significant positive correlation with TIBC (r=0.402, p=0.010), but non-significant negative correlations with hemoglobin and serum iron. TRP was negatively correlated with hemoglobin and serum ferritin, but not significantly. Among patients with microcytic hypochromic anemia, 55.2% (n=16) had increased TmP/GFR, and 61.1% (n=20) of patients with iron deficiency anemia exhibited increased TmP/GFR. Regression analysis revealed that TIBC significantly predicted TmP/GFR (p=0.022), indicating that higher TIBC values are associated with increased TmP/GFR, suggesting a potential link between iron metabolism and renal phosphate handling.

CONCLUSION

Higher TIBC levels were associated with increased TmP/GFR, suggesting that iron deficiency anemia may influence proximal tubular function. The findings emphasize the importance of considering renal phosphate handling in patients with iron deficiency anemia.

Multiplexed PCR to measure in situ growth rates of uropathogenic E. coli during experimental urinary tract infection

Measuring bacterial growth rates in vitro is routine, however, determining growth rates during infection in host has been more challenging. Peak-to-trough ratio (PTR) is a technique for studying microbial growth dynamics, calculated using the ratio of replication origin (ori) copies to that of the terminus (ter), as originally defined by whole genome sequencing (WGS). WGS presents significant challenges in terms of expense and data analysis complexity due to the presence of host DNA in the samples. Here, we used multiplexed PCR with fluorescent probes to estimate bacterial growth rates based on the abundance of ori- and ter-adjacent loci, without the need for WGS. We establish the utility of this approach by comparing growth rates of the uropathogenic Escherichia coli (UPEC) strain HM86 by WGS (PTR) and qPCR to measure the equivalent ori:ter (O:TPCR ). We found that PTR and O:TPCR were highly correlated and that O:TPCR reliably predicted growth rates calculated by conventional methods. O:TPCR was then used to calculate the in situ E. coli growth rates in urine, bladder, and kidneys collected over the course of a week from a murine model of urinary tract infection (UTI). These analyses revealed that growth rate of UPEC strains gradually increased during the early stages of infection (0-6h), followed by a slow decrease in growth rates during later time points (1-7 days). This rapid and convenient method provides valuable insights into bacterial growth dynamics during infection and can be applied to other bacterial species in both animal models and clinical infections.

Hepcidin Exacerbates Iron Metabolism Imbalance in Septic Mice

Purpose

Sepsis is a life-threatening condition associated with acute organ dysfunction. Iron is an essential trace element for multicellular organisms and almost all microorganisms, and its role in sepsis has been increasingly recognized. The aim of this study was to investigate the changes in iron metabolism in caecal ligation and puncture solution (CLP) -induced septic mice and the effects of hepcidin pretreatment on serum inflammatory marker levels and liver iron metabolism in CLP-induced septic mice.

Methods

C57BL/6 mice were given normal saline, CLP (peritonitis model) or 100 μg of hepcidin via intraperitoneal injection. The experimental animals were divided into 4 groups: the control group, model group (CLP), hepcidin pretreatment Groups CLP+hepcidin-2h and CLP+hepcidin-24 h. Blood samples were collected at 6, 12 and 24 hours after CLP surgery, and the mice were euthanized and livers were obtained.

Results

ELISA revealed that hepcidin pretreatment, especially 2 hours in advance (p<0.01), increased the serum hepcidin, TNF-a and IL-6 in CLP-induced septic mice; the serum iron content of CLP-related septic mice decreased (P<0.01), while the liver iron content increased (P<0.01); Hepcidin pretreatment reduced the serum iron (P<0.05) at 6 h and 12 h and liver iron concentrations (P<0.01) at 6 h, 12 h and 24 h in CLP-related septic mice. Western blotting revealed that the hepatic iron absorption-related proteins transferrin receptor-2 (TFR2), ZRT/IRT-like protein 14 (ZIP14) and divalent meta lion transporter-1 (DMT1) were elevated (P<0.01); The iron-exporting protein ferroportin (SLC40A1) was decreased (P<0.01) throughout CLP and CLP+hepcidin sepsis. Compared with CLP group, the protein expressions in the CLP+ hepcidin-2 h group were more obvious than that in the CLP+ hepcidin-24 h group.

Conclusion

Hepcidin has proinflammatory effect. Hepcidin exacerbates iron metabolism imbalances in sepsis by influencing the expression of iron absorption-related proteins and iron export-related proteins.

The association between adherence to unhealthy plant-based diet and risk of COVID-19: a cross-sectional study

BACKGROUND

The fast spread of the coronavirus disease 2019 (COVID-19) epidemic and its high mortality were quickly considered by the health community. Dietary patterns play an important role in strengthening or weakening the immune system and thus incidence of diseases.

AIM

The present study can provide a comprehensive picture of the association between adherence to unhealthy plant-based diet (uPDI) and COVID-19 incidence.

METHODS

This study was undertaken on 8157 adults' participants of the Yazd Health Study (YaHS) and Taghzieh Mardom-e-Yazd (TAMIZ) study aged 20 to 70 years. Data on dietary intakes were obtained using a validated food frequency questionnaire (FFQ). Multivariable logistic regression analysis was used to assess the association between uPDI and COVID-19.

RESULTS

We found a significant association between uPDI and the risk of COVID-19 (OR: 1.36; 95% CI: 1.05-1.75) in the crude model. After adjusting potential confounders, a significant increasing trend in the odds of COVID-19 across increasing quintiles of uPDI (OR: 1.58;95% CI: 1.05-2.37; P-value: 0.027) was observed. Stratified analysis based on sex indicated that uPDI significantly increased the risk of COVID-19 only in males (OR: 1.73;95% CI: 1.12-2.67; P-value: 0.012) and had no effect on females.

CONCLUSIONS

Participants in the highest quintiles of the uPDI had 58% higher odds of COVID-19 compared to subjects in the lowest quintile of uPDI. Although our study has promising results, stronger clinical studies are needed.

Association of Plasma Metal Levels with Outcomes of Assisted Reproduction in Polycystic Ovary Syndrome

The objective of this study is to explore the correlation of metal levels with assisted reproductive technology (ART) outcomes in polycystic ovary syndrome (PCOS) patients. The individuals were recruited who met the research criteria, only tubal factor or male infertility served as the control group (n = 40) and patient group was PCOS patients (n = 35). Individuals (n = 75) were divided into PCOS group (n = 35) and control group (n = 40). The normal body mass index (BMI) group (control) includes women with BMI < 25 kg/m2 in PCOS group (n = 24) and control group (n = 33), and BMI ≥ 25 kg/m2 in PCOS group (n = 11) and control group (n = 7). We performed an analysis of insulin resistance (IR) (n = 15) group and without insulin resistance (NIR) group (n = 20) in PCOS patient and control patients. Comparing difference demographic data, ART outcomes and the metal levels in every group respectively, the correlation of metal levels and ART outcomes in control participants and PCOS patients were analyzed by the Spearman correlation analysis, and multiple linear regression model was used to examine the association between the concentration of 19 metals and ART outcomes in PCOS group and control group. Plasma manganese (Mn), titanium (Ti), sodium (Na), magnesium (Mg), copper (Cu), calcium (Ca)/Mg ratio, and Cu/zinc (Zn) ratio levels in PCOS patients were higher than that in control, while Zn and Ca levels were lower in PCOS patients than that in control. The Mg levels had a positive connection with the number of eggs recovered, and the iron (Fe) levels were positively associated with the number of transplanted embryos in PCOS-IR. In PCOS-NIR, Mn levels positively correlated with the number of follicles and the number of good embryos. Silver (Ag) levels were negatively correlated with the number of follicles, and aluminum (Al) levels were negatively related with the normal fertilization and the number of good embryos. The Spearman analysis in PCOS-BMI ≥ 25 group exhibited that nickel (Ni) levels were negatively associated with the number of follicles. The plasma metal levels seem to affect the clinical manifestations and in vitro fertilization outcomes in assisted reproduction.

Absolute and functional iron deficiency: Biomarkers, impact on immune system, and therapy

Iron is essential for numerous physiological processes and its deficiency often leads to anemia. Iron deficiency (ID) is a global problem, primarily affecting reproductive-age women and children, especially in developing countries. Diagnosis uses classical biomarkers like ferritin or transferrin saturation. Recent advancements include using soluble transferrin receptor (sTfR) or hepcidin for improved detection and classification of absolute and functional iron deficiencies, though mostly used in research. ID without anemia may present symptoms like asthenia and fatigue, even without relevant clinical consequences. ID impacts not only red-blood cells but also immune system cells, highlighting its importance in global health and immune-related comorbidities. Managing ID, requires addressing its cause and selecting appropriate iron supplementation. Various improved oral and intravenous products are available, but further research is needed to refine treatment strategies. This review updates on absolute and functional iron deficiencies, their relationships with the immune system and advancements in diagnosis and therapies.

The Role of Iron in Intestinal Mucus: Perspectives from Both the Host and Gut Microbiota

Although research on the role of iron in host immunity has a history spanning decades, it is only relatively recently that attention has been directed toward the biological effects of iron on the intestinal mucus layer, prompted by an evolving understanding of the role of this material in immune defense. The mucus layer, secreted by intestinal goblet cells, covers the intestinal epithelium, and given its unique location, interactions between the host and gut microbiota, as well as among constituent microbiota, occur frequently within the mucus layer. Iron, as an essential nutrient for the vast majority of life forms, regulates immune responses from both the host and microbial perspectives. In this review, we summarize the iron metabolism of both the host and gut microbiota and describe how iron contributes to intestinal mucosal homeostasis via the intestinal mucus layer with respect to both host and constituent gut microbiota. The findings described herein offer a new perspective on iron-mediated intestinal mucosal barrier function.

The causal relationship between trace element status and upper gastrointestinal ulcers: a Mendelian randomization study

Background

This study aimed to investigate the bidirectional causal relationships between trace elements (such as zinc, magnesium, phosphate, and folate) and upper gastrointestinal ulcers (including gastric and duodenal ulcers). We utilized a two-sample Mendelian randomization (MR) analysis to achieve this.

Methods

We conducted a two-sample MR analysis using summary-level data from genome-wide association studies (GWAS) obtained from public genomics repositories. We utilized a range of MR methods, including inverse-variance weighted (IVW), MR-Egger, and weighted median methods, and conducted a meta-analysis to synthesize results across different datasets. To ensure the robustness of our findings, we performed extensive sensitivity analyses, including pleiotropy assessment, heterogeneity tests, and leave-one-out analysis.

Results

Our findings are significant, indicating a positive causal relationship between increased zinc levels and the risk of gastric ulcers. Moreover, magnesium and folate appear to offer potential protective effects against gastroduodenal ulcers (p < 0.05). The meta-analysis further supports the causal relationship between zinc and gastric ulcers (p < 0.05), confirming zinc's significant causal impact on this condition.

Conclusion

The study confirms a positive causal relationship between zinc and gastric ulcers and highlights the complexity of how trace elements regulate the progression of upper gastrointestinal ulcers. These results provide a scientific basis for dietary recommendations regarding trace element intake in clinical and public health practices. They also offer new insights into effective prevention and treatment strategies for gastric and duodenal ulcers.

Iron homeostasis and ferroptosis in human diseases: mechanisms and therapeutic prospects

Iron, an essential mineral in the body, is involved in numerous physiological processes, making the maintenance of iron homeostasis crucial for overall health. Both iron overload and deficiency can cause various disorders and human diseases. Ferroptosis, a form of cell death dependent on iron, is characterized by the extensive peroxidation of lipids. Unlike other kinds of classical unprogrammed cell death, ferroptosis is primarily linked to disruptions in iron metabolism, lipid peroxidation, and antioxidant system imbalance. Ferroptosis is regulated through transcription, translation, and post-translational modifications, which affect cellular sensitivity to ferroptosis. Over the past decade or so, numerous diseases have been linked to ferroptosis as part of their etiology, including cancers, metabolic disorders, autoimmune diseases, central nervous system diseases, cardiovascular diseases, and musculoskeletal diseases. Ferroptosis-related proteins have become attractive targets for many major human diseases that are currently incurable, and some ferroptosis regulators have shown therapeutic effects in clinical trials although further validation of their clinical potential is needed. Therefore, in-depth analysis of ferroptosis and its potential molecular mechanisms in human diseases may offer additional strategies for clinical prevention and treatment. In this review, we discuss the physiological significance of iron homeostasis in the body, the potential contribution of ferroptosis to the etiology and development of human diseases, along with the evidence supporting targeting ferroptosis as a therapeutic approach. Importantly, we evaluate recent potential therapeutic targets and promising interventions, providing guidance for future targeted treatment therapies against human diseases.

Differential gut microbiota composition in β-Thalassemia patients and its correlation with iron overload

Recent research highlights the significant impact of the gut microbiota on health and disease. Thalassemia, a hereditary blood disorder, requires regular blood transfusions, leading to an accumulation of iron in the body. Such changes could potentially alter the intestinal microbiota, thereby increasing the susceptibility of thalassemic patients to infection. In this study, we analyzed the fecal microbiota of 70 non-transfusion-dependent (NTDT) β-thalassemia/HbE patients and 30 healthy controls. Our findings indicate that iron chelation intervention had no detectable effect on the microbiome profile of thalassemic patients. However, the cross-sectional analysis revealed that the bacterial diversity and community structure in patients were significantly less diverse and distinct compared to those of healthy subjects. Using reference frames, we were also able to demonstrate that bacterial taxa that are known to produce short chain fatty acids, from the genera Alistipes, Coprococcus, and Oscillospira, and those from the family Ruminococcaceae, were less prevalent in the patients. In contrast, bacterial taxa associated with an unhealthy gut, including the genus Clostridium and those from the families Fusobacteriaceae, Enterobacteriaceae, and Peptostrptococcaceae, were more prevalent in patients and found to be correlated with higher levels of ferritin. Collectively, these changes in the microbiota could be regarded as markers of raised ferritin levels, and therefore, awareness should be exercised as they could interfere, albeit indirectly, with the treatment of the co-morbidities of thalassemia.

Hepatocyte activation and liver injury following cerebral ischemia promote HMGB1-mediated hepcidin upregulation in hepatocytes and regulation of systemic iron levels

We previously reported that high mobility group box 1 (HMGB1), a danger-associated molecular pattern (DAMP), increases intracellular iron levels in the postischemic brain by upregulating hepcidin, a key regulator of iron homeostasis, triggering ferroptosis. Since hepatocytes are the primary cells that produce hepcidin and control systemic iron levels, we investigated whether cerebral ischemia induces hepcidin upregulation in hepatocytes. Following middle cerebral artery occlusion (MCAO) in a rodent model, significant liver injury was observed. This injury was evidenced by significantly elevated Eckhoff's scores and increased serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Additionally, total iron levels were significantly elevated in the liver, with intracellular iron accumulation detected in hepatocytes. Hepcidin expression in the liver, which is primarily localized in hepatocytes, increased significantly starting at 3 h after MCAO and continued to increase rapidly, reaching a peak at 24 h. Interestingly, HMGB1 levels in the liver were also significantly elevated after MCAO, with the disulfide form of HMGB1 being the major subtype. In vitro experiments using AML12 hepatocytes showed that recombinant disulfide HMGB1 significantly upregulated hepcidin expression in a Toll-like receptor 4 (TLR4)- and RAGE-dependent manner. Furthermore, treatment with a ROS scavenger and a peptide HMGB1 antagonist revealed that both ROS generation and HMGB1 induction contributed to hepatocyte activation and liver damage following MCAO-reperfusion. In conclusion, this study revealed that cerebral ischemia triggers hepatocyte activation and liver injury. HMGB1 potently induces hepcidin not only in the brain but also in the liver, thereby influencing systemic iron homeostasis following ischemic stroke.

Early life stress and iron metabolism in developmental psychoneuroimmunology

An estimated 250 million children face adverse health outcomes from early life exposure to severe or chronic social, economic, and nutritional adversity, highlighting/emphasizing the pressing concern about the link between ELS and long-term implications on mental and physical health. There is significant overlap between populations experiencing high levels of chronic stress and those experiencing iron deficiency, spotlighting the potential role of iron as a key mediator in this association. Iron, an essential micronutrient for brain development and immune function, is often depleted in stress conditions. Iron deficiency among the most common nutrient deficiencies in the world. Fetal and infant iron status may thus serve as a crucial intermediary between early chronic psychological stress and subsequent immune system changes to impact neurodevelopment. The review presents a hypothesized pathway between early life stress (ELS), iron deficiency, and neurodevelopment through the hypothalamic-pituitary-adrenocortical (HPA) axis and the IL-6-hepcidin axis. This hypothesis is derived from (1) evidence that stress impacts iron status (2) long-term neurodevelopmental outcomes that are shared by ELS and iron deficiency exposure, and (3) possible mechanisms for how iron may mediate the relation between ELS and iron deficiency through alterations in the developing immune system. The article concludes by proposing future research directions, emphasizing the need for rigorous studies to elucidate how stress and iron metabolism interact to modify the developing immune system. Understanding these mechanisms could open new avenues for improving human health and neurodevelopment for women and children globally, making it a timely and vital area of study in psychoneuroimmunology research.

Erythroferrone in focus: emerging perspectives in iron metabolism and hematopathologies

Beyond its core role in iron metabolism, erythroferrone (ERFE) has emerged as a key player with far-reaching implications in various hematologic disorders. Its regulatory effect on hepcidin underlines its significance in conditions characterized by disrupted iron homeostasis. In β-thalassemia and myelodysplastic syndromes, its dysregulation intricately contributes to the clinical challenges of anemia and iron overload which highlights its potential as a therapeutic target. In anemia of chronic disease and iron deficiency anemia, ERFE presents a unique profile. In chronic kidney disease (CKD), the intricate interplay between ERFE, erythropoietin, and hepcidin undergoes dysregulation, contributing to the complex iron imbalance characteristic of this condition. Recent research suggests that ERFE plays a multifaceted role in restoring iron balance in CKD, beyond simply suppressing hepcidin production. The potential to modulate ERFE activity offers a novel approach to treating a spectrum of disorders associated with iron dysregulation. As our understanding of ERFE continues to evolve, it is poised to become a key focus in the development of targeted treatments, making it an exciting and dynamic area of ongoing research. Modulating ERFE activity presents a groundbreaking approach to treat iron dysregulation in conditions like iron deficiency anemia, thalassemia, and hemochromatosis. As new research unveils its intricate roles, ERFE has rapidly emerged as a key target for developing targeted therapies like ERFE agonists and antagonists. With promising studies underway, this dynamic field holds immense potential to improve patient outcomes, reduce complications, and offer personalized treatment options in hematology research. This comprehensive overview of ERFE's role across various conditions underscores its pivotal function in iron metabolism and associated pathologies.

Signal-sensing triggers the shutdown of HemKR, regulating heme and iron metabolism in the spirochete Leptospira biflexa

Heme and iron metabolic pathways are highly intertwined, both compounds being essential for key biological processes, yet becoming toxic if overabundant. Their concentrations are exquisitely regulated, including via dedicated two-component systems (TCSs) that sense signals and regulate adaptive responses. HemKR is a TCS present in both saprophytic and pathogenic Leptospira species, involved in the control of heme metabolism. However, the molecular means by which HemKR is switched on/off in a signal-dependent way, are still unknown. Moreover, a comprehensive list of HemKR-regulated genes, potentially overlapped with iron-responsive targets, is also missing. Using the saprophytic species Leptospira biflexa as a model, we now show that 5-aminolevulinic acid (ALA) triggers the shutdown of the HemKR pathway in live cells, and does so by stimulating the phosphatase activity of HemK towards phosphorylated HemR. Phospho~HemR dephosphorylation leads to differential expression of multiple genes, including of heme metabolism and transport systems. Besides the heme-biosynthetic genes hemA and the catabolic hmuO, which we had previously reported as phospho~HemR targets, we now extend the regulon identifying additional genes. Finally, we discover that HemR inactivation brings about an iron-deficit tolerant phenotype, synergistically with iron-responsive signaling systems. Future studies with pathogenic Leptospira will be able to confirm whether such tolerance to iron deprivation is conserved among Leptospira spp., in which case HemKR could play a vital role during infection where available iron is scarce. In sum, HemKR responds to abundance of porphyrin metabolites by shutting down and controlling heme homeostasis, while also contributing to integrate the regulation of heme and iron metabolism in the L. biflexa spirochete model.

Postencephalitic Parkinsonism: Unique Pathological and Clinical Features-Preliminary Data

Postencephalitic parkinsonism (PEP) is suggested to show a virus-induced pathology, which is different from classical idiopathic Parkinson's disease (PD) as there is no α-synuclein/Lewy body pathology. However, PEP shows a typical clinical representation of motor disturbances. In addition, compared to PD, there is no iron-induced pathology. The aim of this preliminary study was to compare PEP with PD regarding iron-induced pathology, using histochemistry methods on paraffin-embedded post-mortem brain tissue. In the PEP group, iron was not seen, except for one case with sparse perivascular depositions. Rather, PEP offers a pathology related to tau-protein/neurofibrillary tangles, with mild to moderate memory deficits only. It is assumed that this virus-induced pathology is due to immunological dysfunctions causing (neuro)inflammation-induced neuronal network disturbances as events that trigger clinical parkinsonism. The absence of iron deposits implies that PEP cannot be treated with iron chelators. The therapy with L-Dopa is also not an option, as L-Dopa only leads to an initial slight improvement in symptoms in isolated cases.

Iron-depleting nutritional immunity controls extracellular bacterial replication in Legionella pneumophila infections

The accidental human pathogen Legionella pneumophila (Lp) is the etiological agent for a severe atypical pneumonia known as Legionnaires' disease. In human infections and animal models of disease alveolar macrophages are the primary cellular niche that supports bacterial replication within a unique intracellular membrane-bound organelle. The Dot/Icm apparatus-a type IV secretion system that translocates ~300 bacterial proteins within the cytosol of the infected cell-is a central virulence factor required for intracellular growth. Mutant strains lacking functional Dot/Icm apparatus are transported to and degraded within the lysosomes of infected macrophages. The early foundational work from Dr. Horwitz's group unequivocally established that Legionella does not replicate extracellularly during infection-a phenomenon well supported by experimental evidence for four decades. Our data challenges this paradigm by demonstrating that macrophages and monocytes provide the necessary nutrients and support robust Legionella extracellular replication. We show that the previously reported lack of Lp extracellular replication is not a bacteria intrinsic feature but rather a result of robust restriction by serum-derived nutritional immunity factors. Specifically, the host iron-sequestering protein Transferrin is identified here as a critical suppressor of Lp extracellular replication in an iron-dependent manner. In iron-overload conditions or in the absence of Transferrin, Lp bypasses growth restriction by IFNγ-primed macrophages though extracellular replication. It is well established that certain risk factors associated with development of Legionnaires' disease, such as smoking, produce a chronic pulmonary environment of iron-overload. Our work indicates that iron-overload could be an important determinant of severe infection by allowing Lp to overcome nutritional immunity and replicate extracellularly, which in turn would circumvent intracellular cell intrinsic host defenses. Thus, we provide evidence for nutritional immunity as a key underappreciated host defense mechanism in Legionella pathogenesis.

Mössbauer and EPR detection of iron trafficking kinetics and possibly labile iron pools in whole Saccharomyces cerevisiae cells

The kinetics of iron trafficking in whole respiring Saccharomyces cerevisiae cells were investigated using Mössbauer and EPR spectroscopies. The Mössbauer-active isotope 57Fe was added to cells growing under iron-limited conditions; cells were analyzed at different times post iron addition. Spectroscopic changes suggested that the added 57Fe initially entered the labile iron pool, and then distributed to vacuoles and mitochondria. The first spectroscopic feature observed, ∼ 3 min after adding 57Fe plus a 5 to 15 min processing dead time, was a quadrupole doublet typical of nonheme high-spin FeII. This feature likely arose from labile FeII pools in the cell. At later times (15-150 min), magnetic features due to S = 5/2 FeIII developed; these likely arose from FeIII in vacuoles. Corresponding EPR spectra were dominated by a g = 4.3 signal from the S = 5/2 FeIII ions that increased in intensity over time. Developing at a similar rate was a quadrupole doublet typical of S = 0 [Fe4S4]2+ clusters and low-spin FeII hemes; such centers are mainly in mitochondria, cytosol, and nuclei. Development of these features was simulated using a published mathematical model, and simulations compared qualitatively well with observations. In the five sets of experiments presented, all spectroscopic features developed within the doubling time of the cells, implying that the detected iron trafficking species are physiologically relevant. These spectroscopy-based experiments allow the endogenous labile iron pool within growing cells to be detected without damaging or altering the pool, as definitely occurs using chelator-probe detection and possibly occurs using chromatographic separations.

Drivers of diversification in fungal pathogen populations

To manage and treat chronic fungal diseases effectively, we require an improved understanding of their complexity. There is an increasing appreciation that chronic infection populations are often heterogeneous due to diversification and drift, even within a single microbial species. Genetically diverse populations can contribute to persistence and resistance to treatment by maintaining cells with different phenotypes capable of thriving in these dynamic environments. In chronic infections, fungal pathogens undergo prolonged challenges that can drive trait selection to convergent adapted states through restricted access to critical nutrients, assault by immune effectors, competition with other species, and antifungal drugs. This review first highlights the various genetic and epigenetic mechanisms that promote diversity in pathogenic fungal populations and provide an additional barrier to assessing the actual heterogeneity of fungal infections. We then review existing studies of evolution and genetic heterogeneity in fungal populations from lung infections associated with the genetic disease cystic fibrosis. We conclude with a discussion of open research questions that, once answered, may aid in diagnosing and treating chronic fungal infections.