Non transferrin bound iron: nature, manifestations and analytical approaches for estimation

Essential and Non-Essential Metals and Metalloids and Their Role in Atherosclerosis

Peripheral arterial disease (PAD) is becoming more prevalent in the aging developed world and can have significant functional impacts on patients. There is a recent recognition that environmental toxicants such as circulating metals and metalloids may contribute to the pathogenesis of atherosclerotic disease, but the mechanisms are complex. While the broad toxic biologic effects of metals in human systems have been extensively reviewed, the role of non-essential exposure and essential metal aberrancy in PAD specifically is less frequently discussed. This review of the literature describes current scientific knowledge regarding the individual roles several major metals and metalloids play in atherogenesis and highlights areas where a dearth of data exist. The roles of lead (Pb), arsenic (As), cadmium (Cd), iron (Fe), copper (Cu), selenium (Se) are included. Contemporary outcomes of therapeutic trials aimed at chelation therapy of circulating metals to impact cardiovascular outcomes are also discussed. This review highlights the supported notion of differential metal presence within peripheral plaques themselves, although distinguishing their roles within these plaques requires further illumination.

Oxidative stress in patients with nasal respiratory impairment and OSAS

BACKGROUND

This study focused on evaluating the clinical significance of oxidative stress biomarkers in patients with OSAS. We investigated how nasal respiratory obstruction in OSAS patients might affect the oxidative balance.

METHODS

Sixty patients were divided into three groups (n = 20 each): severe OSAS (AHI > 30), snoring with AHI < 15 (mild OSAS), and nasal respiratory impairment with AHI < 5. All subjects underwent ENT examination, rhinomanometry, polysomnography, and oxidative stress biomarker analysis.

RESULTS

From the measurements of biomarkers associated with oxidative stress, specifically NPBI (non-protein bound iron), AOPP (Advanced Oxidation Protein Products), Isoprostanes (both plasmatic ad urinary), and Thiols, no statistically significant differences emerged among the subjects belonging to the three groups (patients with OSAS, subjects with snoring and AHI < 15, subjects with nasal respiratory impairment only and AHI < 5).

CONCLUSIONS

The presence of oxidative stress markers in patients with nasal obstruction, even in the absence of severe OSAS, highlights the potential role of nasal airflow limitation as a contributing factor in the pathogenesis of sleep-disordered breathing. A better understanding of the oxidative stress profile in these conditions might contribute to refining diagnostic and therapeutic approaches, and potentially reduce the reliance on polysomnography in selected cases.

The interplay between the myeloperoxidase-hypochlorous acid system, heme oxygenase, and free iron in inflammatory diseases

Accumulated unbound free iron (Fe(II or III)) is a redox engine generating reactive oxygen species (ROS) that promote oxidative stress and inflammation. Iron is implicated in diseases with free radical pathology including cardiovascular, neurodegenerative, reproductive disorders, and some types of cancer. While many studies focus on iron overload disorders, few explore the potential link between the myeloperoxidase-hypochlorous acid (MPO-HOCl) system and localized iron accumulation through heme and iron‑sulfur (FeS) cluster protein destruction. Although inducible heme oxygenase (HO-1), the rate-limiting enzyme in heme catabolism, is frequently associated with these diseases, we hypothesize that HOCl also contributes to the generation of free iron and heme degradation products. Furthermore, HO-1 and HOCl may play a dual role in free iron accumulation by regulating the activity of key iron metabolism proteins. Enzymatic and non-enzymatic modulators, as well as scavengers of HOCl, can help prevent heme destruction and reduce the accumulation of free iron. Given iron's role in disease progression and severity, identifying the primary sources, mechanisms, and mediators involved in free iron generation is crucial for developing effective pharmacological treatments. Further investigation focusing on the specific contributions of the MPO-HOCl system and free iron is necessary to explore novel strategies to mitigate its harmful effects in biological systems.

Lactoferrin-A Regulator of Iron Homeostasis and Its Implications in Cancer

Cancer is a global health challenge, and its development is closely linked to iron metabolism. Cancer cells have an increased demand for this element, which promotes their proliferation, invasion, and metastasis. Excess iron catalyzes the formation of reactive oxygen species (ROS), which can both induce ferroptosis and initiate oncogenic signaling pathways. The deregulation of iron metabolism in cancer patients leads to anemia or toxic iron overload and also affects the gut microbiota. Lactoferrin (LF), a glycoprotein with strong iron chelating properties, can regulate its availability to cancer cells, thereby limiting their growth and progression. By chelating free Fe ions, LF reduces oxidative stress and inhibits the mechanisms that promote carcinogenesis. Additionally, it exhibits immunomodulatory and anti-inflammatory effects and may enhance the body's anti-tumor response. This review analyses the mechanisms of action of lactoferrin in the context of cancer, with a particular focus on its chelating, antioxidant, and immunomodulatory properties. The multidirectional effects of LF make it a promising component of preventive and therapeutic strategies, requiring further clinical studies.

The Role of Iron in Atherosclerosis and its Association with Related Diseases

PURPOSE OF REVIEW

This review aims to elucidate the multifaceted role of iron in the pathogenesis of atherosclerosis. The primary objective is to summarize recent advances in understanding how iron contributes to atherosclerosis through various cellular mechanisms. Additionally, the review explores the therapeutic implications of targeting iron metabolism in the prevention and treatment of cardiovascular diseases.

RECENT FINDINGS

A growing body of literature suggests that excess iron accelerates the progression of atherosclerosis, with the deleterious form of iron, non-transferrin-bound iron (NTBI), particularly exacerbating this process. Furthermore, iron overload has been demonstrated to play a pivotal role in endothelial cells, vascular smooth muscle cells, and macrophages, contributing to plaque instability and disease progression by promoting lipid peroxidation, oxidative stress, inflammatory responses, and ferroptosis. Iron plays a complex role in atherosclerosis, influencing multiple cellular processes and promoting disease progression. By promoting oxidative stress, inflammation, and ferroptosis, iron exacerbates endothelial dysfunction, smooth muscle cell calcification, and the formation of macrophage-derived foam cells. Targeted therapies focusing on iron metabolism have proven effective in treating atherosclerosis and other cardiovascular diseases.

Deciphering the iron enigma: Navigating the complexities of iron metabolism in critical illness

Iron is a double-edged sword! Despite being essential for numerous physiological processes of the body, a dysregulated iron metabolism can result in tissue damage, exaggerated inflammatory response, and increased susceptibility to infection with certain pathogens that thrive in iron-rich environment. During sepsis, there is an alteration of iron metabolism, leading to increased transport and uptake into cells. This increase in labile iron may cause oxidative damage and cellular injury (ferroptosis) which progresses as the disease worsens. Critically ill patients are often complicated with systemic inflammation which may contribute to multiple organ dysfunction syndrome or sepsis, a common cause of mortality in intensive care unit. Originally, ferritin was known to play an important role in the hematopoietic system for its iron storage capacity. Recently, its role has emerged as a predictor of poor prognosis in chronic inflammation and critical illnesses. Apart from predicting the disease outcome, serum ferritin can potentially reflect disease activity as well.

Quantifying non-transferrin-bound iron (NTBI) in human plasma: incorporating BODIPY-pyridylhydrazone (BODIPY-PH) within a thin green film linked to a portable fluorescence-based device

Free iron in human serum or non-transferrin-bound iron (NTBI) can generate free radicals and lead to oxidative damage. Moreover, it is highly toxic to various tissues and a vital biomarker related to the iron-loading status of thalassemia and Alzheimer's patients. In NTBI in healthy individuals, NTBI levels are typically less than 1 µM; current NTBI analysis usually requires advanced instrumentation and many-step sample pretreatment. To address this issue, we employed our invented BODIPY derivative, BODIPY-PH, as a fluorescence probe and trapped it onto the microcentrifuge tube lid using tapioca starch. The fluorescence intensity of BODIPY-PH increased with increasing NTBI concentration (turn-on). The developed portable reaction chamber facilitates rapid analysis (∼5 min) using small sample volumes (10 μL sample in a total volume of 600 μL). Under optimum conditions, using the sample-developed portable fluorescence device and fluorescence spectrometer, we achieved impressive limits of detection (LOD) of 0.003 and 0.0015 μM, respectively. Furthermore, the developed sensors show relatively high selectivity toward Fe3+ over other metal ions and biomolecules (i.e., Fe2+, Cr3+, Cu2+, and glucose). The sensor performance in serum samples of thalassemia patients exhibited no significant difference compared to the labeled value (obtained from standard methods). Overall, the developed fluorescence sensor is suitable for determining NTBI and offers high sensitivity, high selectivity, and a short incubation time (5 min). Moreover, the method requires a limited number of reagents, is simple to use, and uses low-cost equipment to determine NTBI in human serum samples.

Iron Reduces the Trafficking of Fatty Acids from Human Immortalised Brain Microvascular Endothelial Cells Through Modulation of Fatty Acid Transport Protein 1 (FATP1/SLC27A1)

PURPOSE

Alzheimer's disease (AD) is associated with brain accumulation of amyloid-beta (Aβ) and neurofibrillary tangle formation, in addition to reduced brain docosahexaenoic acid (DHA) and increased brain iron levels. DHA requires access across the blood-brain barrier (BBB) to enter the brain, and iron has been shown to affect the expression and function of a number of BBB transporters. Therefore, this study aimed to assess the effect of iron on the expression and function of fatty acid binding protein 5 (FABP5) and fatty acid transport protein 1 (FATP1), both which mediate brain endothelial cell trafficking of DHA.

METHODS

The mRNA and protein levels of FABP5 and FATP1 in human cerebral microvascular endothelial (hCMEC/D3) cells was assessed by RT-qPCR and Western blot, respectively following ferric ammonium citrate (FAC) treatment (up to 750 µM, 72 h). The function of FABP5 and FATP1 was assessed via uptake and efflux of radiolabelled 3H-oleic acid and 14C-DHA.

RESULTS

FAC (500 µM, 72 h) had no impact on the expression of FABP5 at the protein and mRNA level in hCMEC/D3 cells, which was associated with a lack of effect on the uptake of 14C-DHA. FAC led to a 19.7% reduction in FATP1 protein abundance in hCMEC/D3 cells with no impact on mRNA levels, and this was associated with up to a 32.6% reduction in efflux of 14C-DHA.

CONCLUSIONS

These studies demonstrate a role of iron in down-regulating FATP1 protein abundance and function at the BBB, which may have implications on fatty acid access to the brain.

Micronutrient Changes in Critically Ill: Elusive Answers for Evaluation and Management

How to cite this article: Ajith Kumar AK, Gopaldas JA. Micronutrient Changes in Critically Ill: Elusive Answers for Evaluation and Management. Indian J Crit Care Med 2024;28(6):526-528.

LDH-Based Voltammetric Sensors

Layered double hydroxides (LDHs), also named hydrotalcite-like compounds, are anionic clays with a lamellar structure which have been extensively used in the last two decades as electrode modifiers for the design of electrochemical sensors. These materials can be classified into LDHs containing or not containing redox-active centers. In the former case, a transition metal cation undergoing a reversible redox reaction within a proper potential window is present in the layers, and, therefore, it can act as electron transfer mediator, and electrocatalyze the oxidation of an analyte for which the required overpotential is too high. In the latter case, a negatively charged species acting as a redox mediator can be introduced into the interlayer spaces after exchanging the anion coming from the synthesis, and, again, the material can display electrocatalytic properties. Alternatively, due to the large specific surface area of LDHs, molecules with electroactivity can be adsorbed on their surface. In this review, the most significant electroanalytical applications of LDHs as electrode modifiers for the development of voltammetric sensors are presented, grouping them based on the two types of materials.

Potential involvement of ferroptosis in BPA-induced neurotoxicity: An in vitro study

BACKGROUND

Ferroptosis is a newly recognized cell death pathway having distinct characteristics compared to traditional cell death pathways such as apoptosis, necroptosis, or autophagy. However, the potential involvement of ferroptosis in bisphenol A (BPA)-induced neurotoxicity has not been well explored so far. In present study, we analyzed the relationship between ferroptosis and BPA-induced neurotoxicity.

METHODS

In this study, a human neuroblastoma cell line, SH-SY5Y, was treated with BPA, ferrostatin-1 (FS-1, ferroptosis inhibitor) and RSL-3 (ferroptosis inducer). The cell viability was measured using MTT assay. Additionally, the levels of lipid peroxidation, total iron content, reactive oxygen species (ROS) generation, and nitrite content were measured to evaluate the key markers of ferroptosis. To further confirm the involvement of ferroptosis in BPA-induced neurotoxicity, other ferroptosis markers such as glutathione peroxidase (GPx) activity, total glutathione contents and antioxidant parameters were also evaluated.

RESULTS

The cell viability of SH-SY5Y cells was down-regulated by BPA treatment in a concentration-dependent manner, the cell viability at 0.1 µM concentration was 97.63% whereas at highest BPA concentration i.e. 10 µM, the cell viability was 86.05% (p < 0.0001). Also the antioxidant parameters including catalase and superoxide dismutase activity of neuronal cells were down-regulated upon BPA exposure. However, the levels of lipid peroxidation, total iron, reactive oxygen species, and nitrite contents were increased in a concentration-dependent manner which could be rescued by FS-1 and exacerbated by RSL-3. The total iron in SH-SY5Y cells at 0.1 µM concentration was found to be 1.2 fold (p < 0.05) of control and at highest BPA concentration total iron was about 1.41 fold (p < 0.001) of control.

CONCLUSIONS

The present study indicated that, ferroptosis plays an important role in the progression of BPA-induced neurotoxicity, and ferroptosis may become a novel target in the treatment of various neurological disorders.

Iron homeostasis and post-hemorrhagic hydrocephalus: a review

Iron physiology is regulated by a complex interplay of extracellular transport systems, coordinated transcriptional responses, and iron efflux mechanisms. Dysregulation of iron metabolism can result in defects in myelination, neurotransmitter synthesis, and neuronal maturation. In neonates, germinal matrix-intraventricular hemorrhage (GMH-IVH) causes iron overload as a result of blood breakdown in the ventricles and brain parenchyma which can lead to post-hemorrhagic hydrocephalus (PHH). However, the precise mechanisms by which GMH-IVH results in PHH remain elusive. Understanding the molecular determinants of iron homeostasis in the developing brain may lead to improved therapies. This manuscript reviews the various roles iron has in brain development, characterizes our understanding of iron transport in the developing brain, and describes potential mechanisms by which iron overload may cause PHH and brain injury. We also review novel preclinical treatments for IVH that specifically target iron. Understanding iron handling within the brain and central nervous system may provide a basis for preventative, targeted treatments for iron-mediated pathogenesis of GMH-IVH and PHH.

Difference in the Mechanism of Iron Overload-Enhanced Acute Hepatotoxicity Induced by Thioacetamide and Carbon Tetrachloride in Rats

Iron overload has been recognized as a risk factor for liver disease; however, little is known about its pathological role in the modification of liver injury. The purpose of this study is to investigate the influence of iron overload on liver injury induced by two hepatotoxicants with different pathogenesis in rats. Rats were fed a control (Cont), 0.8% high-iron (0.8% Fe), or 1% high-iron diet (1% Fe) for 4 weeks and were then administered with saline, thioacetamide (TAA), or carbon tetrachloride (CCl4). Hepatic and systemic iron overload were seen in the 0.8% and 1% Fe groups. Twenty-four hours after administration, hepatocellular necrosis induced by TAA and hepatocellular necrosis, degeneration, and vacuolation induced by CCl4, as well as serum transaminase values, were exacerbated in the 0.8% and 1% Fe groups compared to the Cont group. On the other hand, microvesicular vacuolation induced by CCl4 was decreased in 0.8% and 1% Fe groups. Hepatocellular DNA damage was increased by iron overload in both models, whereas a synergistic effect of oxidative stress by excess iron and hepatotoxicant was only present in the CCl4 model. The data showed that dietary iron overload exacerbates TAA- and CCl4-induced acute liver injury with different mechanisms.

Iron as an emerging therapeutic target in critically ill patients

The multiple roles of iron in the body have been known for decades, particularly its involvement in iron overload diseases such as hemochromatosis. More recently, compelling evidence has emerged regarding the critical role of non-transferrin bound iron (NTBI), also known as catalytic iron, in the care of critically ill patients in intensive care units (ICUs). These trace amounts of iron constitute a small percentage of the serum iron, yet they are heavily implicated in the exacerbation of diseases, primarily by catalyzing the formation of reactive oxygen species, which promote oxidative stress. Additionally, catalytic iron activates macrophages and facilitates the growth of pathogens. This review aims to shed light on this underappreciated phenomenon and explore the various common sources of NTBI in ICU patients, which lead to transient iron dysregulation during acute phases of disease. Iron serves as the linchpin of a vicious cycle in many ICU pathologies that are often multifactorial. The clinical evidence showing its detrimental impact on patient outcomes will be outlined in the major ICU pathologies. Finally, different therapeutic strategies will be reviewed, including the targeting of proteins involved in iron metabolism, conventional chelation therapy, and the combination of renal replacement therapy with chelation therapy.

One advantageous reflection of iron metabolism in context of normal physiology and pathological phases

PURPOSE (BACKGROUND)

The presented review is an updating of Iron metabolism in context of normal physiology and pathological phases. Iron is one of the vital elements in humans and associated into proteins as a component of heme (e.g. hemoglobin, myoglobin, cytochromes proteins, myeloperoxidase, nitric oxide synthetases), iron sulfur clusters (e.g. respiratory complexes I-III, coenzyme Q10, mitochondrial aconitase, DNA primase), or other functional groups (e.g. hypoxia inducible factor prolyl hydroxylases). All these entire iron-containing proteins ar e needed for vital cellular and organismal functions together with oxygen transport, mitochondrial respiration, intermediary and xenobiotic metabolism, nucleic acid replication and repair, host defense, and cell signaling.

METHODS (METABOLIC STRATEGIES)

Cells have developed metabolic strategies to import and employ iron safely. Regulatory process of iron uptake, storage, intracellular trafficking and utilization is vital for the maintenance of cellular iron homeostasis. Cellular iron utilization and intracellular iron trafficking pathways are not well established and very little knowledge about this. The predominant organs, which are associated in the metabolism of iron, are intestine, liver, bone marrow and spleen. Iron is conserved, recycled and stored. The reduced bioavailability of iron in humans has developed extremely efficient mechanisms for iron conservation. Prominently, the losses of iron cannot considerably enhance through physiologic mechanisms, even if iron intake and stores become excessive. Loss of iron is balanced or maintained from dietary sources.

RESULTS (OUTCOMES)

Numerous physiological abnormalities are associated with impaired iron metabolism. These abnormalities are appeared in the form of several diseases. There are duodenal ulcer, inflammatory bowel disease, sideroblastic anaemia, congenital dyserythropoietic anemias and low-grade myelodysplastic syndromes. Hereditary hemochromatosis and anaemia are two chronic diseases, which are responsible for disturbing the iron metabolism in various tissues, including the spleen and the intestine. Impairment in hepatic hepcidin synthesis is responsible for chronic liver disease, which is grounding from alcoholism or viral hepatitis. This condition directs to iron overload that can cause further hepatic damage. Iron has important role in several infectious diseases are tuberculosis, malaria trypanosomatid diseases and acquired immunodeficiency syndrome (AIDS). Iron is also associated with Systemic lupus erythematosus [SLE], cancer, Alzheimer's disease (AD) and post-traumatic epilepsy.

CONCLUSION

Recently, numerous research studies are gradually more dedicated in the field of iron metabolism, but a number of burning questions are still waiting for answer. Cellular iron utilization and intracellular iron trafficking pathways are not well established and very little knowledge about this. Increased information of the physiology of iron homeostasis will support considerate of the pathology of iron disorders and also make available the support to advance treatment.

The clinical relevance of detectable plasma iron species in iron overload states and subsequent to intravenous iron-carbohydrate administration

Many disorders of iron homeostasis (e.g., iron overload) are associated with the dynamic kinetic profiles of multiple non-transferrin bound iron (NTBI) species, chronic exposure to which is associated with deleterious end-organ effects. Here we discuss the chemical nature of NTBI species, challenges with measuring NTBI in plasma, and the clinical relevance of NTBI exposure based on source (iron overload disorder vs. intravenous iron-carbohydrate complex administration). NTBI is not a single entity but consists of multiple, often poorly characterized species, some of which are kinetically non-exchangeable while others are relatively exchangeable. Prolonged presence of plasma NTBI is associated with excessive tissue iron accumulation in susceptible tissues, with consequences, such as endocrinopathy and heart failure. In contrast, intravenous iron-carbohydrate nanomedicines administration leads only to transient NTBI appearance and lacks evidence for association with adverse clinical outcomes. Assays to measure plasma NTBI are typically technically complex and remain chiefly a research tool. There have been two general approaches to estimating NTBI: capture assays and redox-activity assays. Early assays could not avoid capturing some iron from transferrin, thus overestimating NTBI. By contrast, some later assays may have promoted the donation of NTBI species to transferrin during the assay procedure, potentially underestimating NTBI levels. The levels of transferrin saturation at which NTBI species have been detectable have varied between different methodologies and between patient populations studied.

Increased Levels of Circulating Iron-Albumin Complexes in Peripheral Arterial Disease Patients

Under physiological conditions, extracellular iron circulates in the blood bound to transferrin. As a consequence of several pathologies, the circulating level of a Non-Transferrin Bound pool of Iron (NTBI) increases. The NTBI pool is biologically heterogeneous and represented by iron chelated either by small metabolites (citrate, amino acids, or cofactors) or by serum proteins. By promoting reactive oxygen species (ROS) and reactive nitrogen species (RNS) formation, NTBI causes oxidative stress and alteration of membrane lipids, seriously compromising the healthy state of organs and tissues. While NTBI involvement in several pathologies has been clarified, its contribution to vascular diseases remains to be investigated. Here we measure and analyze the pool of NTBI in the serum of a small group of peripheral arterial disease (PAD) patients. We show that: (i) the NTBI pool shifts from low molecular complexes to high-molecular ones in PAD patients compared to healthy controls; (ii) most of this NTBI is bound to the serum protein Albumin; (iii) this NTBI-Albumin complex can be isolated and quantitated following a simple immunoisolation procedure amenable to automation and suitable for clinical screening purposes.

Severe anaemia, iron deficiency, and susceptibility to invasive bacterial infections

Severe anaemia and invasive bacterial infections remain important causes of hospitalization and death among young African children. The emergence and spread of antimicrobial resistance demand better understanding of bacteraemia risk factors to inform prevention strategies. Epidemiological studies have reported an association between severe anaemia and bacteraemia. In this review, we explore evidence that severe anaemia is associated with increased risk of invasive bacterial infections in young children. We describe mechanisms of iron dysregulation in severe anaemia that might contribute to increased risk and pathogenesis of invasive bacteria, recent advances in knowledge of how iron deficiency and severe anaemia impair immune responses to bacterial infections and vaccines, and the gaps in our understanding of mechanisms underlying severe anaemia, iron deficiency, and the risk of invasive bacterial infections.

Iron supplementation and the risk of bronchopulmonary dysplasia in extremely low gestational age newborns

BACKGROUND

The aim of this study was to determine the relationship between iron exposure and the development of bronchopulmonary dysplasia (BPD).

METHODS

A secondary analysis of the PENUT Trial dataset was conducted. The primary outcome was BPD at 36 weeks gestational age and primary exposures of interest were cumulative iron exposures in the first 28 days and through 36 weeks' gestation. Descriptive statistics were calculated for study cohort characteristics with analysis adjusted for the factors used to stratify randomization.

RESULTS

Of the 941 patients, 821 (87.2%) survived to BPD evaluation at 36 weeks, with 332 (40.4%) diagnosed with BPD. The median cohort gestational age was 26 weeks and birth weight 810 g. In the first 28 days, 76% of infants received enteral iron and 55% parenteral iron. The median supplemental cumulative enteral and parenteral iron intakes at 28 days were 58.5 and 3.1 mg/kg, respectively, and through 36 weeks' 235.8 and 3.56 mg/kg, respectively. We found lower volume of red blood cell transfusions in the first 28 days after birth and higher enteral iron exposure in the first 28 days after birth to be associated with lower rates of BPD.

CONCLUSIONS

We find no support for an increased risk of BPD with iron supplementation.

TRIAL REGISTRATION NUMBER

NCT01378273. https://clinicaltrials.gov/ct2/show/NCT01378273 IMPACT: Prior studies and biologic plausibility raise the possibility that iron administration could contribute to the pathophysiology of oxidant-induced lung injury and thus bronchopulmonary dysplasia in preterm infants. For 24-27-week premature infants, this study finds no association between total cumulative enteral iron supplementation at either 28-day or 36-week postmenstrual age and the risk for developing bronchopulmonary dysplasia.

Ferric citrate-induced colonic mucosal damage associated with oxidative stress, inflammation responses, apoptosis, and the changes of gut microbial composition

Ferric citrate (FC) has been used as an iron fortifier and nutritional supplement, which is reported to induce colitis in rats, however the underlying mechanism remains to be elucidated. We performed a 16-week study of FC in male healthy C57BL/6 mice (nine-month-old) with oral administration of Ctr (0.9 % NaCl), 1.25 % FC (71 mg/kg/bw), 2.5 % FC (143 mg/kg/bw) and 5 % FC (286 mg/kg/bw). FC-exposure resulted in colon iron accumulation, histological alteration and reduce antioxidant enzyme activities, such as glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC), together with enhanced lipid peroxidation level, including malondialdehyde (MDA) level and 4-Hydroxynonenal (4-HNE) protein expression. Exposure to FC was associated with upregulated levels of the interleukin (IL)- 6, IL-1β, IL-18, IL-8 and tumor necrosis factor α (TNF-α), while down-regulated levels of IL-4 and IL-10. Exposure to FC was positively associated with the mRNA and protein expressions of cysteine-aspartic proteases (Caspase)- 9, Caspase-3, Bcl-2-associated X protein (Bax), while negatively associated with B-cell lymphoma 2 (Bcl2) in mitochondrial apoptosis signaling pathway. FC-exposure changed the diversity and composition of gut microbes. Additionally, the serum lipopolysaccharide (LPS) contents increased in FC-exposed groups when compared with the control group, while the expression of colonic tight junction proteins (TJPs), such as Claudin-1 and Occludin were decreased. These findings indicate that the colonic mucosal injury induced by FC-exposure are associated with oxidative stress generation, inflammation response and cell apoptosis, as well as the changes in gut microbes diversity and composition.

Hematologic evaluation of peripheral blood in Sprague Dawley rats by chronic exposure to aluminum chloride (AlCl3)

This study aimed to evaluate whether aluminum chloride (AlCl3) causes hematological changes in the peripheral blood of Sprague-Dawley (SD) rats. Five groups of female SD rats were intragastrically administered with 4 different concentrations of AlCl3 for 5 days a week for a total of 90 days. The aluminum concentration was determined via graphite furnace atomic absorption spectroscopy. Analysis of serum iron-kinetic profiles, blood cytometry outcomes, and blood smears of the blood samples. Scanning electron microscopy (SEM) and Raman spectroscopy were used to search for structural and ultrastructural changes, respectively. Blood aluminum concentration ranged 12.38-16.24 μg/L with no significant difference between experimental treatments. At the AlCl3 concentration of 40 mg Al/kg bw of rats/day, the mean ferritin value in the serum iron kinetic profile was 29.81±6.1 ng/mL, and this value showed a significant difference between experimental treatments. Blood cytometry revealed that there were 6.45-7.11×106 cells/μL erythrocytes, 8.91-9.32×103 cells/μL leukocytes, and 477.2-736.3×103 cells/μL platelets along with a hemoglobin of 37.38-41.93 g/dL and hematocrit level of 37.38-41.93%; the experimental treatments showed no significant differences. Erythrocyte structural analysis using SEM showed no differences between experimental treatments, whereas ultrastructural evaluation using Raman spectroscopy made it possible to identify the following bands: 741, 1123, 1350, 1578, and 1618 cm-1, which were respectively associated with the following vibrational modes and compounds: vibration of the tryptophan ring, asymmetric C-O-C stretching of glucose, C-H curve of tryptophan, C=C stretching of the heme group, and C-N stretching of the heme group, with no significant differences between experimental treatments. Therefore, AlCl3 administration does not induce ultrastructural changes in the erythrocyte membrane. This study revealed that serum ferritin concentration was the only parameter affected by AlCl3 exposure at 40 mg of Al/kg bw of rats/day.

Transferrin saturation as a surrogate marker for assessment of labile nontransferrin bound iron in chronic liver disease

BACKGROUND

Increased transferrin saturation (TS) and ferritin are common in hereditary hemochromatosis (HH) but also in chronic liver diseases (CLD). Nontransferrin bound iron (NTBI) is believed to be associated with iron-induced cell damage. We aimed to evaluate NTBI in CLD and their relationship with liver damage.

METHODS

Two groups of patients were studied. Group 1 (G1): 94 CLD patients from an Outpatient Hepatology Unit. Group 2 (G2): 36 healthy individuals form a Medical Checkup Clinic. Transferrin iron-binding capacity, TS, ferritin, AST, ALT, and red cell count were performed using standard tests. NTBI was assessed as enhanced labile plasma iron (eLPi). Levels of eLPi less than 0.4 µmol/l were considered within the normal range.

RESULTS

Prevalence of increased iron tests (elevated TS and ferritin) was 14% in G1 and 5.5% in G2 ( P = 0.19). Positive NTBI was found in 12 patients (11 in G1 and 1 in G2). Positivity to NTBI was associated with increased iron tests ( P = 0.03), cirrhosis ( P = 0.03) and AST index (ASTI) ( P = 0.03). NTBI was associated with TS of more than 70% ( P = 0.002) but not to elevated ferritin ( P = 0.74). Variables strongly associated with a positive NTBI in univariate analysis (TS > 70%, cirrhosis and ASTI) were submitted to binary regression analysis. TS of more than 70% was the only independent predictive factor ( P = 0.049; odds ratio, 6.8).

CONCLUSION

NTBI was associated with TS in CLD, but not with ferritin. NTBI testing could be useful for CLD patients with increased iron tests. Alternatively, a TS of more than 70% can be used as a surrogate marker.

The Dark Side of Iron: The Relationship between Iron, Inflammation and Gut Microbiota in Selected Diseases Associated with Iron Deficiency Anaemia—A Narrative Review

Iron is an indispensable nutrient for life. A lack of it leads to iron deficiency anaemia (IDA), which currently affects about 1.2 billion people worldwide. The primary means of IDA treatment is oral or parenteral iron supplementation. This can be burdened with numerous side effects such as oxidative stress, systemic and local-intestinal inflammation, dysbiosis, carcinogenic processes and gastrointestinal adverse events. Therefore, this review aimed to provide insight into the physiological mechanisms of iron management and investigate the state of knowledge of the relationship between iron supplementation, inflammatory status and changes in gut microbiota milieu in diseases typically complicated with IDA and considered as having an inflammatory background such as in inflammatory bowel disease, colorectal cancer or obesity. Understanding the precise mechanisms critical to iron metabolism and the awareness of serious adverse effects associated with iron supplementation may lead to the provision of better IDA treatment. Well-planned research, specific to each patient category and disease, is needed to find measures and methods to optimise iron treatment and reduce adverse effects.

Bioactive nutraceutical ligands and their efficiency to chelate elemental iron of varying dynamic oxidation states to mitigate associated clinical conditions

The natural bioactive or nutraceuticals exhibit several health benefits, including anti-inflammatory, anti-cancer, metal chelation, antiviral, and antimicrobial activity. The inherent limitation of nutraceuticals or bioactive ligand(s) in terms of poor pharmacokinetic and other physicochemical properties affects their overall therapeutic efficiency. The excess of iron in the physiological compartments and its varying dynamic oxidation state [Fe(II) and Fe(III)] precipitates various clinical conditions such as non-transferrin bound iron (NTBI), labile iron pool (LIP), ferroptosis, cancer, etc. Though several natural bioactive ligands are proposed to chelate iron, the efficiency of bioactive ligands is limited due to poor bioavailability, denticity, and other related physicochemical properties. The present review provides insight into the relevance of studying the dynamic oxidation state of iron(II) and iron(III) in the physiological compartments and its clinical significance for selecting diagnostics and therapeutic regimes. We suggested a three-pronged approach, i.e., diagnosis, selection of therapeutic regime (natural bioactive), and integration of novel drug delivery systems (NDDS) or nanotechnology-based principles. This systematic approach improves the overall therapeutic efficiency of natural iron chelators to manage iron overload-related clinical conditions.

Iron commensalism of mesenchymal glioblastoma promotes ferroptosis susceptibility upon dopamine treatment

The heterogeneity of glioblastoma multiforme (GBM) leads to poor patient prognosis. Here, we aim to investigate the mechanism through which GBM heterogeneity is coordinated to promote tumor progression. We find that proneural (PN)-GBM stem cells (GSCs) secreted dopamine (DA) and transferrin (TF), inducing the proliferation of mesenchymal (MES)-GSCs and enhancing their susceptibility toward ferroptosis. PN-GSC-derived TF stimulates MES-GSC proliferation in an iron-dependent manner. DA acts in an autocrine on PN-GSC growth in a DA receptor D1-dependent manner, while in a paracrine it induces TF receptor 1 expression in MES-GSCs to assist iron uptake and thus enhance ferroptotic vulnerability. Analysis of public datasets reveals worse prognosis of patients with heterogeneous GBM with high iron uptake than those with other GBM subtypes. Collectively, the findings here provide evidence of commensalism symbiosis that causes MES-GSCs to become iron-addicted, which in turn provides a rationale for targeting ferroptosis to treat resistant MES GBM.

Glioblastoma stem-cell derived mesenchymal cells become reliant on iron but vulnerable to ferroptosis and within patients of heterogeneous glioblastoma multiforme prognosis for those with high iron uptake is poorer than other subtypes.

Iron Chelation Remits Memory Deficits Caused by the High-Fat Diet in a Mouse Model of Alzheimer’s Disease

Background: Obesity is a worldwide health problem that has been implicated in many diseases, including Alzheimer’s disease (AD). AD is one of the most common neurodegenerative disorders and is characterized by two pathologies, including extracellular senior plaques composed of amyloid-β (Aβ) and intracellular neurofibrillary tangles (NFTs) consisting of abnormally hyperphosphorylated tau. According to current research, a high-fat diet (HFD) could exacerbate Aβ accumulation, oxidative damage, and cognitive defects in AD mice. However, the accurate role of HFD in the pathogenesis of AD is far more unclear. Objective: To explore the accurate role of HFD in the pathogenesis of AD. Methods: Open Field, Barns Maze, Elevated zero-maze, Contextual fear condition, Tail suspension test, western blotting, immunofluorescence, Fluoro-Jade C Labeling, Perls’ Prussian blue staining, and ELISA were used. Results: HFD caused nonheme iron overload in the brains of APPswe/PS1dE9 (APP/PS1) mice. Furthermore, the administration of M30 (0.5 mg/kg) for iron chelation once every 2 days per os (p.o.) for 1 month remitted memory deficits caused by HFD in APP/PS1 mice. Notably, a variety of hematological parameters in whole blood had no difference after iron chelation. In addition, iron chelation effectively reduced synaptic impairment in hippocampus and neuronal degeneration in cortex in the HFD-fed APP/PS1 mice. Meanwhile, iron chelation decreased Aβ 1–40 and Aβ 1–42 level as well as neuroinflammation in HFD-fed APP/PS1 mice. Conclusion: These data enhance our understanding of how HFD aggravates AD pathology and cognitive impairments and might shed light on future preclinical studies.

In vitro activity of the novel siderophore cephalosporin, cefiderocol, in Gram-negative pathogens in Europe by site of infection

OBJECTIVES

We assessed the activity of the novel siderophore cephalosporin, cefiderocol and selected other antibacterial agents against Gram-negative bacterial isolates in Europe.

METHODS

Isolates were obtained between 2013 and 2018 from European countries participating in the SIDERO-WT and SIDERO-Proteeae multinational surveillance studies. Isolates were categorised by infection site, focusing on bloodstream infections, hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP), complicated intra-abdominal infections and complicated urinary tract infections. Cefiderocol activity was compared with ceftazidime-avibactam, ceftolozane-tazobactam, colistin and meropenem using standard susceptibility testing methods. European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used to interpret susceptibility data.

RESULTS

Isolates (n = 20 911) were collected from 145 sites in 24 countries in Europe, the highest proportion (34%) being from patients with HABP/VABP. Enterobacterales (66.6% of isolates) were more frequent than glucose non-fermenting species (33.4%) overall, with some differences between infection sites. Across all infection sites, the MIC50/MIC90 for cefiderocol was ≤0.5/≤2 mg/L for Enterobacter spp., ≤0.25/<2 mg/L for Klebsiella spp., 0.12/2 mg/L for Acinetobacter spp., ≤0.25/1 mg/L for Pseudomonas aeruginosa and ≤0.12/≤0.5 mg/L for Stenotrophomonas maltophilia. Across all infection sites, cefiderocol MICs were ≤2 mg/L for ≥96% of Enterobacter spp., ≥95% of Klebsiella spp., ≥90% of Acinetobacter spp. and ≥99% of Pseudomonas aeruginosa and Stenotrophomonas maltophilia isolates. Cefiderocol maintained high activity in carbapenem-resistant isolates, and the difference in activity between carbapenem-resistant (percentage susceptibility at EUCAST breakpoint: E. coli 77.8%, Klebsiella spp. 69.2%, Pseudomonas aeruginosa 97.5%, Acinetobacter spp. 90.7%, Stenotrophomonas maltophilia 99.6%) and carbapenem-susceptible (percentage susceptibility at EUCAST breakpoint: E. coli 99.4%, Klebsiella spp. 98.0%, Pseudomonas aeruginosa 99.7%, Acinetobacter spp. 94.9%) isolates was lower for cefiderocol than other agents.

CONCLUSIONS

Cefiderocol had excellent activity against all Gram-negative species, independent of key infection site and carbapenem MIC. Cefiderocol is a useful addition to the therapeutic options available for these difficult-to-treat infections.

Characterisation of individual ferritin response in patients receiving chelation therapy

Aims

To develop a drug–disease model describing iron overload and its effect on ferritin response in patients affected by transfusion‐dependent haemoglobinopathies and investigate the contribution of interindividual differences in demographic and clinical factors on chelation therapy with deferiprone or deferasirox.

Methods

Individual and mean serum ferritin data were retrieved from 13 published studies in patients affected by haemoglobinopathies receiving deferiprone or deferasirox. A nonlinear mixed effects modelling approach was used to characterise iron homeostasis and serum ferritin production taking into account annual blood consumption, baseline demographic and clinical characteristics. The effect of chelation therapy was parameterised as an increase in the iron elimination rate. Internal and external validation procedures were used to assess model performance across different study populations.

Results

An indirect response model was identified, including baseline ferritin concentrations and annual blood consumption as covariates. The effect of chelation on iron elimination rate was characterised by a linear function, with different slopes for each drug (0.0109 [90% CI: 0.0079–0.0131] vs. 0.0013 [90% CI: 0.0008–0.0018] L/mg mo). In addition to drug‐specific differences in the magnitude of the ferritin response, simulation scenarios indicate that ferritin elimination rates depend on ferritin concentrations at baseline.

Conclusion

Modelling of serum ferritin following chronic blood transfusion enabled the evaluation of drug‐induced changes in iron elimination rate and ferritin production. The use of a semi‐mechanistic parameterisation allowed us to disentangle disease‐specific factors from drug‐specific properties. Despite comparable chelation mechanisms, deferiprone appears to have a significantly larger effect on the iron elimination rate than deferasirox.

Synthesis of indenophenanthridine via a [4+2] annulation strategy: a “turn-off’’ Fe3+ ion sensor, practical application in live cell imaging and reversible acidochromism studies

An efficient protocol has been developed for the synthesis of a novel fluorescent probe, 1,2-disubstituted-indeno[1,2,3-gh]phenanthridine, derived from a series of α-oxo-ketene dithioacetals (OKDTAs) and indenoquinoline under essential conditions via a [4+2] annulation in excellent yield.

Insight into the bioabsorption of Fe-based materials and their current developments in bone applications

Iron (Fe) and Fe-based materials have been vigorously explored in orthopedic applications in the past decade mainly owing to their promising mechanical properties including high yield strength, elastic modulus and ductility. Nevertheless, their corrosion products and low corrosion kinetics are the major concerns that need to be improved further despite their appealing mechanical strengths. The current studies on porous Fe-based scaffolds show an improved corrosion rate but the in vitro biocompatibility is still problematic in general. Unlike the Mg implants, the biodegradation and bioabsorption of Fe-based implants are still not well described. This vague issue could implicate the development of Fe-based materials as potential medical implants as they have not reached the clinical trial stage yet. Thus, there is a need to understand in-depth the Fe corrosion behavior and its bioabsorption mechanism to facilitate the material design of Fe-based scaffolds and further improve its biocompatibility. This manuscript provides an important insight into the basic bioabsorption of the multi-ranged Fe-based corrosion products with a review of the latest progress on the corrosion & in vitro biocompatibility of porous Fe-based scaffolds together with the remaining challenges and the perspective on the future direction.

Complex Interactions in Regulation of Haematopoiesis-An Unexplored Iron Mine

Iron is one of the most abundant metals on earth and is vital for the growth and survival of life forms. It is crucial for the functioning of plants and animals as it is an integral component of the photosynthetic apparatus and innumerable proteins and enzymes. It plays a pivotal role in haematopoiesis and affects the development and differentiation of different haematopoietic lineages, apart from its obvious necessity in erythropoiesis. A large amount of iron stores in humans is diverted towards the latter process, as iron is an indispensable component of haemoglobin. This review summarises the important players of iron metabolism and homeostasis that have been discovered in recent years and highlights the overall significance of iron in haematopoiesis. Its role in maintenance of haematopoietic stem cells, influence on differentiation of varied haematopoietic lineages and consequences of iron deficiency/overloading on development and maturation of different groups of haematopoietic cells have been discussed.

Non-Transferrin-Bound Iron in the Spotlight: Novel Mechanistic Insights into the Vasculotoxic and Atherosclerotic Effect of Iron

Significance: While atherosclerosis is an almost inevitable consequence of aging, food preferences, lack of exercise, and other aspects of the lifestyle in many countries, the identification of new risk factors is of increasing importance to tackle a disease, which has become a major health burden for billions of people. Iron has long been suspected to promote the development of atherosclerosis, but data have been conflicting, and the contribution of iron is still debated controversially. Recent Advances: Several experimental and clinical studies have been recently published about this longstanding controversial problem, highlighting the critical need to unravel the complexity behind this topic. Critical Issues: The aim of the current review is to provide an overview of the current knowledge about the proatherosclerotic impact of iron, and discuss the emerging role of non-transferrin-bound iron (NTBI) as driver of vasculotoxicity and atherosclerosis. Finally, I will provide detailed mechanistic insights on the cellular processes and molecular pathways underlying iron-exacerbated atherosclerosis. Overall, this review highlights a complex framework where NTBI acts at multiple levels in atherosclerosis by altering the serum and vascular microenvironment in a proatherogenic and proinflammatory manner, affecting the functionality and survival of vascular cells, promoting foam cell formation and inducing angiogenesis, calcification, and plaque destabilization. Future Directions: The use of additional iron markers (e.g., NTBI) may help adequately predict predisposition to cardiovascular disease. Clinical studies are needed in the aging population to address the atherogenic role of iron fluctuations within physiological limits and the therapeutic value of iron restriction approaches. Antioxid. Redox Signal. 35, 387-414.

Ferroptotic Cell Death: New Regulatory Mechanisms for Metabolic Diseases

Background:

Cell death is a fundamental biological phenomenon that contributes to the pathogenesis of various diseases. Regulation of iron and iron metabolism has received considerable research interests especially concerning the progression of metabolic diseases.

Discussion:

Emerging evidence shows that ferroptosis, a non-apoptotic programmed cell death induced by iron-dependent lipid peroxidation, contributes to the development of complex diseases such as non-alcoholic steatohepatitis, cardiomyopathy, renal ischemia-reperfusion, and neurodegenerative diseases. Therefore, inhibiting ferroptosis can improve the pathophysiology of associated metabolic diseases. This review describes the vital role of ferroptosis in mediating the development of certain metabolic diseases. Besides, the potential risk of iron and ferroptosis in atherosclerosis and cardiovascular diseases is also described. Iron overload and ferroptosis are potential secondary causes of death in metabolic diseases. Moreover, this review also provides potential novel approaches against ferroptosis based on recent research advances.

Conclusion:

Several controversies exist concerning mechanisms underlying ferroptotic cell death in metabolic diseases, particularly in atherosclerosis. Since ferroptosis participates in the progression of metabolic diseases such as non-alcoholic steatohepatitis (NASH), there is a need to develop new drugs targeting ferroptosis to alleviate such diseases.

Alteration of Iron Concentration in Alzheimer's Disease as a Possible Diagnostic Biomarker Unveiling Ferroptosis

Proper functioning of all organs, including the brain, requires iron. It is present in different forms in biological fluids, and alterations in its distribution can induce oxidative stress and neurodegeneration. However, the clinical parameters normally used for monitoring iron concentration in biological fluids (i.e., serum and cerebrospinal fluid) can hardly detect the quantity of circulating iron, while indirect measurements, e.g., magnetic resonance imaging, require further validation. This review summarizes the mechanisms involved in brain iron metabolism, homeostasis, and iron imbalance caused by alterations detectable by standard and non-standard indicators of iron status. These indicators for iron transport, storage, and metabolism can help to understand which biomarkers can better detect iron imbalances responsible for neurodegenerative diseases.

Metabolomics approach based on LC-HRMS for the fast screening of iron(II)-chelating peptides in protein hydrolysates

Production of iron-chelating peptides from protein hydrolysates requires robust and adequate screening methods to optimize their purification and subsequently valorize their potential antioxidant properties. An original methodology was developed for direct and sensitive screening of iron(II)-chelating peptides based on ion-pair reverse phase liquid chromatography (IP-RPLC) coupled to high-resolution mass spectrometry (HRMS). Peptide mixture was first added to iron(II) solution to form iron(II)-peptide complexes. Then IP-RPLC-HRMS analysis was conducted on this iron-peptide mixture and on the iron-free peptide solution for comparative mass spectra analysis. This protocol, initially applied to a range of low molecular weight standard peptides, allowed detection of [(Peptide-H)+⁵⁶Fe^II]⁺ complex ion for iron(II)-chelating peptides (GGH, EAH, DAH, βAH, DMH, DTH, DSH). GGH was added in complex peptide mixtures and targeted analysis of [(GGH-H)+⁵⁶Fe^II]⁺ complex showed a limit of detection (LOD) below 0.77 mg L^-1 of GGH. This protocol was finally tested in combination with metabolomics software and additional digital processing for non-targeted search for iron(II)-chelating peptides. Applicability of this new screening methodology has been validated by detection of GGH as iron(II)-chelating peptide when added at 0.77 mg L^-1 in casein hydrolysate. Graphical abstract.

Analyses of hemorrhagic diathesis in high-iron diet-fed rats

Iron overload has been well recognized to cause oxidant-mediated cellular/tissue injury; however, little is known about the effects of iron overload on the blood coagulation system. We encountered an unexpected bleeding tendency in rats fed a high-iron diet in a set of studies using iron-modified diets. In this study, we investigated the mechanism of hemorrhagic diathesis induced by dietary iron overload in rats. Six-week-old F344/DuCrlCrlj male rats were fed a standard (containing 0.02% iron) or a high-iron diet (containing 1% iron) for 6 weeks and were then sampled for hematological, blood biochemical, coagulation, and pathological examinations. Serum and liver iron levels increased in rats fed the high-iron diet (Fe group) and serum transferrin was almost saturated with iron. However, serum transaminase levels did not increase. Moreover, plasma prothrombin time and activated partial thromboplastin time were significantly prolonged, regardless of the presence of hemorrhage. The activity of clotting factors II and VII (vitamin K-dependent coagulation factors) decreased significantly, whereas that of factor VIII was unaltered. Blood platelet levels were not influenced by dietary iron overload, suggesting that the bleeding tendency in iron-overloaded rats is caused by secondary hemostasis impairment. In addition, hemorrhage was observed in multiple organs in rats fed diets containing more than 0.8% iron. Our results suggest that iron overload can increase the susceptibility of coagulation abnormalities caused by latent vitamin K insufficiency.

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

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

Iron, ferroptosis, and new insights for prevention in acute kidney injury

Acute kidney injury (AKI) is a very common condition with high morbidity and mortality, which can be seen in 5-7% of all hospitalized patients and in up to 57% of all intensive care unit admissions. Despite recent advances in clinical care, the prevalence of AKI has been shown to increase with virtually no change in mortality. AKI is a complex syndrome occurring in a variety of clinical settings. Early detection is crucial to prevent irreversible loss of renal function. The pathogenesis of AKI is highly multifactorial and complex, including vasoconstriction, reactive oxygen species formation, cell death, abnormal immune modulators and growth factors. Emerging evidence from both human and animal studies suggests that dysregulation of iron metabolism may play a potentially important role in AKI. Therefore, targeting the iron homeostasis may provide a new therapeutic intervention for AKI. New therapeutic strategies including iron chelation therapy, targeting iron metabolism related proteins and direct inhibitors of ferroptosis are imperative to improve the outcomes of patients. Taking into consideration the complexity of AKI, one intervention may not be enough for therapeutic success. Future preclinical studies in animal disease models followed by well-designed clinical trials should be conducted to extend findings from animal AKI models to humans.

Association between Bone Mineral Density and Serum Iron Indices in Premenopausal Women in South Korea

Background

Osteoporosis is characterized by a decrease in bone mineral density (BMD) and increased risk of fragility fractures. Serum iron level may interact with bone health status. This study investigated the correlations of BMD with serum iron level, hemoglobin level, and total iron-binding capacity (TIBC).

Methods

We performed a retrospective analysis of data from the medical records of premenopausal women in South Korea. The women’s BMDs and the Z scores of the BMDs were verified using dual-energy X-ray absorption. The participants were stratified into quartiles for analyses of the associations of BMD with serum iron level, TIBC, and hemoglobin level.

Results

A simple linear regression analysis revealed associations of changes in BMD with iron level (β=-0.001, standard error [SE]=0.001, P<0.001), hemoglobin level (β=0.015, SE=0.003, P<0.001), and TIBC (β=0.001, SE=0.001, P<0.001). This pattern was also observed in a multiple linear regression analysis. A multivariate logistic regression analysis of iron level and TIBC for low BMD revealed odds ratios of 1.005 (P<0.001) and 0.995 (P<0.001), respectively.

Conclusion

This study demonstrated clear relationships of changes in BMD with serum iron level and TIBC, and thus confirms the usefulness of these markers in the clinical evaluation of iron storage and BMD in younger women.

A micellized fluorescence sensor based on amplified quenching for highly sensitive detection of non-transferrin-bound iron in serum

A novel, micelle-based fluorescence system capable of selective and sensitive signal transduction for non-transferrin-bound iron (NTBI) in serum was devised. We demonstrated that an aggregated fluorogenic core in a micelle induces amplified fluorescence quenching, which differentiates this sensing platform from the numerous fluorescence-based tools previously developed for sensitive detection.

Iron Metabolism, Ferroptosis, and the Links With Alzheimer's Disease

Iron is an essential transition metal for numerous biologic processes in mammals. Iron metabolism is regulated via several coordination mechanisms including absorption, utilization, recycling, and storage. Iron dyshomeostasis can result in intracellular iron retention, thereby damaging cells, tissues, and organs through free oxygen radical generation. Numerous studies have shown that brain iron overload is involved in the pathological mechanism of neurodegenerative disease including Alzheimer’s disease (AD). However, the underlying mechanisms have not been fully elucidated. Ferroptosis, a newly defined iron-dependent form of cell death, which is distinct from apoptosis, necrosis, autophagy, and other forms of cell death, may provide us a new viewpoint. Here, we set out to summarize the current knowledge of iron metabolism and ferroptosis, and review the contributions of iron and ferroptosis to AD.

57Fe enrichment in mice for β-thalassaemia studies via Mössbauer spectroscopy of blood samples

In this work, wild-type and heterozygous β-thalassaemic mice were enriched with ⁵⁷Fe via gastrointestinal absorption to characterize in greater detail the iron complexes then identifiable via Mössbauer spectroscopy. The ⁵⁷Fe enrichment method was validated and Mössbauer spectra were obtained at 80 K from blood samples from wild-type and β-thalassaemic mice at 1, 3, 6, and 9 months of age. As expected, the haemoglobin levels of the thalassaemic mice were lower than from normal mice, indicating anaemia. Furthermore, significant amounts of ferritin-like iron were observed in the thalassaemic mice samples, which decreased with mouse age, reflecting the pattern of reticulocyte count reduction reported in the literature.

Snapshots of Iron Speciation: Tracking the Fate of Iron Nanoparticle Drugs via a Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Approach

Nanomedicines are nanoparticle-based therapeutic or diagnostic agents designed for targeted delivery or enhanced stability. Nanotechnology has been successfully employed to develop various drug formulations with improved pharmacokinetic characteristics, and current research efforts are focused on the development of new innovator and generic nanomedicines. Nanomedicines, which are often denoted as complex or nonbiological complex drugs, have inherently different physicochemical and pharmacokinetic properties than conventional small molecule drugs. The tools necessary to fully evaluate nanomedicines in clinical settings are limited, which can hamper their development. One of the most successful families of nanomedicines are iron-carbohydrate nanoparticles, which are administered intravenously (IV) to treat iron-deficiency anemia. In the U.S., the FDA has approved six distinct iron-carbohydrate nanoparticles but only one generic version (sodium ferric gluconate for Ferrlecit). There is significant interest in approving additional generic iron-carbohydrate drugs; however, the lack of a direct method to monitor the fate of the iron nanoparticles in clinical samples has impeded this approval. Herein we report a novel liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) method that allows for the direct quantification of the iron-carbohydrate drugs in clinical samples, while simultaneously measuring the speciation of the iron released from the nanoparticles in biological samples. To our knowledge, this is the first time that iron nanoparticles have been observed in clinical samples, opening the door for direct pharmacokinetic studies of this family of drugs. This method has potential applications not only for iron-nanoparticle drugs but also for any nanomedicine with an inorganic component.

The Effect of Transfusion-Dependent Thalassemia Patient's Serum on Peripheral Blood Mononuclear Cell Viability

Iron overload is a major complication in transfusion-dependent thalassemia (TDT) patients. Chronic oxidative stress from iron overload may lead to cellular damage and viability. This is a cross-sectional study. Transfusion-dependent thalassemia patients aged ⩾18 years old were enrolled. Transfusion-dependent thalassemia patient’s serum and normal volunteer’s serum were separately incubated with healthy peripheral blood mononuclear cells (PBMCs). The cell viability was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay at 24, 48, and 72 hours. Sixty-nine TDT patients and 22 healthy controls were enrolled. The mean of PBMCs viability after incubation with serum from TDT patients was lower than that with the controls (88.65% vs 103.56% at 24 hours, 78.77% vs 112.04%% at 48 hours, and 71.18% vs 132.16%% at 72 hours, respectively). High serum ferritin level (correlation −0.29, P < .05) and white blood cell (WBC) count negatively affected cell viability (correlation −2.86, P = .05). From multivariate analysis, serum ferritin level is the only significant risk factor that is independently associated with cell viability (correlation −11.42, P < .001). Our findings showed that TDT patient’s serum causes decreased cell viability. Serum ferritin level was a significant independent factor influencing cell viability.

Iron-sensing is governed by mitochondrial, not by cytosolic iron-sulfur cluster biogenesis in Aspergillus fumigatus

Microorganisms have to adapt their metabolism to the requirements of their ecological niche to avoid iron shortage as well as iron toxicity. Therefore, mechanisms have been evolved to tightly regulate iron uptake, consumption, and detoxification, which depend on sensing the cellular iron status. In the facultative anaerobic yeast Saccharomyces cerevisiae, iron-sensing depends on mitochondrial (ISC) but not cytosolic iron-sulfur cluster assembly (CIA), while in mammals further processing of an ISC product via CIA is required for sensing of the cellular iron state. To address the question of how the obligatory aerobic mold Aspergillus fumigatus senses the cellular iron state, mutant strains allowing the downregulation of ISC and CIA were generated. These studies revealed that: (i) Nfs1 (Afu3g14240) and Nbp35 (Afu2g15960), which are involved in ISC and CIA, respectively, are essential for growth; (ii) a decrease in ISC (Nfs1 depletion) but not CIA (Nbp35 depletion) results in a transcriptional iron starvation response, (iii) a decrease in, ISC as well as CIA, increases the chelatable iron pool, accompanied by increased iron toxicity and increased susceptibility to oxidative stress and phleomycin. In agreement with ISC being essential for iron-sensing, a decrease in mitochondrial iron import by deletion of the mitochondrial iron importer MrsA resulted in an iron starvation response. Taken together, these data underline that iron-sensing in A. fumigatus depends on ISC but not CIA. Moreover, depletion of the glutathione pool via generating a mutant lacking γ-glutamylcysteine synthase, GshA (Afu3g13900), caused an iron starvation response, underlining a crucial role of glutathione in iron-sensing in A. fumigatus.

An investigation of the effects of curcumin on iron overload, hepcidin level, and liver function in β-thalassemia major patients: A double-blind randomized controlled clinical trial

This study investigated the effects of curcumin, the active polyphenol in turmeric, on iron overload, hepcidin level, and liver function in β-thalassemia major patients. This double-blind randomized controlled clinical trial was conducted on 68 β-thalassemia major patients. The subjects were randomly divided into 2 groups to receive either 500 mg curcumin capsules (total: 1,000 mg) twice daily or placebo for 12 weeks. Dietary intakes and biochemical variables including hemoglobin, transferrin saturation, total iron binding capacity, nontransferrin bound iron (NTBI), ferritin, hepcidin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were assessed at the beginning and end of the trial. Curcumin significantly reduced serum levels of NTBI (2.83 ± 1.08 compared with 2.22 ± 0.97 μmol/L, p = .001), ALT (42.86 ± 11.15 compared with 40.60 ± 9.89 U/L, p = .018), and AST (49.45 ± 12.39 compared with 46.30 ± 10.85 U/L, p = .002) at the end of the study. Based on analysis of covariance, a significant decrease was also observed in levels of NTBI (2.22 ± 0.97 vs. 2.55 ± 0.94 μmol/L, p = .026), ALT (40.60 ± 9.89 vs. 45.01 ± 10.42 U/L, p = .004), and AST (46.30 ± 10.85 vs. 50.99 ± 9.36 U/L, p = .009) in curcumin group in comparison with placebo group. There were no significant changes in hepcidin and other variables in any of the 2 groups. Curcumin administration alleviated iron burden and liver dysfunction by reducing NTBI, ALT, and AST levels in patients with β-thalassemia major.

Antiviral effects of ferric ammonium citrate

Iron is an essential nutrient for cell survival and is crucial for DNA replication, mitochondrial function and erythropoiesis. However, the immunological role of iron in viral infections has not been well defined. Here we found the iron salt ferric ammonium citrate (FAC) inhibited Influenza A virus, HIV virus, Zika virus, and Enterovirus 71 (EV71) infections. Of note, both iron ion and citrate ion were required for the antiviral capability of FAC, as other iron salts and citrates did not exhibit viral inhibition. Mechanistically, FAC inhibited viral infection through inducing viral fusion and blocking endosomal viral release. These were further evidenced by the fact that FAC induced liposome aggregation and intracellular vesicle fusion, which was associated with a unique iron-dependent cell death. Our results demonstrate a novel antiviral function of FAC and suggest a therapeutic potential for iron in the control of viral infections.

Quercetin and iron metabolism: What we know and what we need to know

Iron is a life-supporting micronutrient that is required in the human diet, and is essential for maintaining physiological homeostasis. Properly harnessing a redox-active metal such as iron is a great challenge for cells and organisms because an excess of highly reactive iron catalyzes the formation of reactive oxygen species and can lead to cell and tissue damage. Quercetin is a typical flavonoid that is commonly found in fruits and vegetables and has versatile biological effects. From a classical viewpoint, owing to its unique chemical characteristics, quercetin has long been associated with iron metabolism only in the context of its iron-chelating and ROS-scavenging activities. However, within the field of human iron biology, expanding concepts of the roles of quercetin are flourishing, and great strides are being made in understanding the interactions between quercetin and iron. This progress highlights the varied roles of quercetin in iron metabolism, which involve much more than iron chelation alone. A review of these studies provides an ideal context to summarize recent progress and discuss compelling evidence for therapeutic opportunities that could arise from a better understanding of the underlying mechanisms.