Non-transferrin bound iron: a key role in iron overload and iron toxicity

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.

Involvement of Fe(III) in the formation of immunoglobulin G-enriched protein aggregates in human plasma

A small fraction of the proteins present in human plasma can be found as circulating protein aggregates. Such aggregates are formed by prone to aggregation proteins and different stimuli promote the aggregation process. Fe(III) is a redox active metal ion which also actively interacts with proteins. The aim of this work is to identify the prone to aggregation plasma proteins in presence of Fe(III) in order to outline potential targets of these circulating protein aggregates. Here we show that Fe(III) induces the formation of protein aggregates from human plasma proteins. A concentration of 100 μM Fe(III) aggregates roughly 5 % of the total plasma protein assayed. When assayed by SDS-PAGE/silver-staining, a rather homogeneous aggregate can be observed with one major protein with a molecular weight matching that of immunoglobulin G (IgG) (150k Da). Additionally, the band corresponding to albumin (66 kDa) which is the main plasma protein was absent. The identity of IgG within the aggregate and albumin depletion was corroborated by liquid chromatography-mass spectrometry. Additionally, some other proteins could be identified within the aggregate such as fibrinogen, fibronectin and Apo-B. Then, the identity of the IgG and depletion of albumin was corroborated by Western blot. It should be noted that aggregated IgGs are strong activators of inflammatory pathways involving neutrophil oxidative burst, complement cascade activation and platelet release of active amines. Therefore, the existence of a potential link between the formation of Fe(III)-induced protein aggregates and inflammation should be further explored.

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.

Pancreatic Volume in Thalassemia: Determinants and Association with Alterations of Glucose Metabolism

Objectives: This study aimed to compare the pancreatic volume between beta-thalassemia major (β-TM) and beta-thalassemia intermedia (β-TI) patients and between thalassemia patients and healthy subjects and to determine the predictors of pancreatic volume and its association with glucose metabolism in β-TM and β-TI patients. Methods: We considered 145 β-TM patients and 19 β-TI patients enrolled in the E-MIOT project and 20 healthy subjects. The pancreatic volume and pancreatic and hepatic iron levels were quantified by magnetic resonance imaging. Results: The pancreatic volume indexed by body surface area (PVI) was significantly lower in both β-TI and β-TM patients compared to healthy subjects and in β-TM patients compared to β-TI patients. The only independent determinants of PVI were pancreatic iron in β-TM and hepatic iron in β-TI. In β-TM, there was an association between alterations of glucose metabolism and PVI, and PVI was a comparable predictor of altered glucose metabolism compared to pancreatic iron. Only one β-TI patient had an altered glucose metabolism and showed a reduced PVI and pancreatic iron overload. Conclusions: Thalassemia syndromes are characterized by a reduced pancreatic volume, associated with iron levels. In β-TM, the pancreatic volume and iron deposition are associated with the development and progression of alterations of glucose metabolism.

Copper strontium phosphate glasses with high antimicrobial efficacy

The emergence of antibiotic-resistant strains caused by the extensive use of antibiotics in the world requires a preventive approach to stop the infection spread, especially in a hospital setting. So, there is a growing demand for materials that can inhibit bacteria growth or have bactericidal effects. In this paper, an inexpensive and durable Cu-containing strontium-modified phosphate glass with a considerable antimicrobial effect is proposed. The basic physical properties of the material are studied, and its antimicrobial effect is evaluated on Staphylococcus aureus bacteria, known to be the most common problem in hospital environments because of healthcare-associated infections. The glass powders demonstrate strong antibacterial efficacy with a concentration of only a few mg/mL, sufficient to eradicate the entire bacterial colonies within 24 h. Bulk surfaces of these glasses inhibit bacterial growth and release low, non-toxic levels of their constituent elements into simulated body fluid. On the basis of the obtained results, it is shown that the proposed glass can be used as a structural material for various medical equipment and/or components of antimicrobial coating/paint not only in medicine but also for high touch point articles in public places like schools, gyms, public offices and similar.

Mesenchymal Stem Cells Prevent SLC39A14-Dependent Hepatocyte Ferroptosis through Exosomal miR-16-5p in Liver Graft

Ischemia-reperfusion injury (IRI) is the leading cause of hepatic graft dysfunction, resulting from hepatocyte damage. Nevertheless, given the few specialized therapeutics available in hepatic IRI, additional mechanistic insights into hepatocyte damage are required. Here, the protein solute carrier family 39 member 14 (SLC39A14) is identified as a pro-ferroptosis target in hepatocytes of human liver allografts through single-cell RNA sequencing analysis. SLC39A14 knockdown significantly mitigated hepatic IRI by preventing hepatocyte ferroptosis in vivo and in vitro. Mechanistically, the inhibition of SLC39A14 suppressed non-transferrin-bound iron (NTBI) uptake by hepatocytes, thereby reducing iron overload and cell ferroptosis. Moreover, human bone marrow-derived mesenchymal stem cells (hBMSCs) are found to exhibit a notable therapeutic effect on hepatic IRI by downregulating SLC39A14 expression. Exosomes derived from hBMSCs delivered abundant miR-16-5p into hepatocytes, which post-transcriptionally suppressed the expression of SLC39A14 and reduced cell ferroptosis induced by hepatic IRI. In conclusion, SLC39A14 triggers hepatic IRI by mediating NTBI uptake into hepatocytes and inducing hepatocyte ferroptosis. Moreover, hBMSC-based therapy is promising to reverse this progression of hepatic IRI.

First report of iron-overload myopathy due to secondary hemochromatosis in a dog

IMPORTANCE

Hemochromatosis is rare in domestic animals, and iron-induced myopathy has not been reported in veterinary medicine. This case is the first report of iron-overload myopathy owing to hemochromatosis in a dog.

CASE PRESENTATION

A 9-year-old spayed female Donggyeong dog presented with severe forelimb lameness. Necropsy revealed an enlarged liver and hemorrhagic lesions in the forelimb muscle. Microscopy showed iron components accumulation in multiple organs, including the liver, forelimb skeletal muscle, spleen, lymph node, and kidney. Prussian blue staining identified iron deposits in both macrophages and parenchymal cells, indicating that the iron accumulation was acquired rather than hereditary. Furthermore, iron components were observed within muscle fibers, accompanied by severe atrophy and myositis.

CONCLUSIONS AND RELEVANCE

Severe necrosis and mild fibrosis were observed in the liver and forelimb skeletal muscles. Based on histological analysis, we diagnosed iron overload myopathy by secondary hemochromatosis. Secondary hemochromatosis with severe muscle atrophy and myositis is very rare, and this is the first report of iron-overload myopathy in a dog.

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.

Quantitative MRI evaluation of iron deposition in patients with transfusion-dependent thalassemia: clinical management insights

BACKGROUND

In patients with thalassemia, different organs are affected differently by iron overload. Nevertheless, the reasons for this could be the same key transporters. This study investigated the iron deposition in different organs of transfusion-dependent thalassemia (TDT) patients and its correlation.

RESEARCH DESIGN AND METHODS

This cross-sectional study involved 54 TDT patients who underwent MRI T2* examinations of the heart, liver, pancreas, spleen, kidneys, and pituitary. The study analyzed the iron deposition in each organ and evaluated the correlation of iron deposition using Spearman's test.

RESULTS

Among the 54 patients with TDT, liver iron overload was found in 49/54 (90.7%) cases, pancreas iron overload in 43/54 (79.6%) cases, spleen iron overload in 18/26 (69.2%) patients, heart iron overload in 20/54 (37.0%) cases, and kidney iron overload in 8/54 (14.8%) patients. Most patients (66.7%) with iron overload in the liver but not in the heart exhibited spleen iron abnormalities. Pituitary T2* and pancreas T2* (r = 0.790), pituitary T2* and kidney T2* (r = 0.692), kidney T2* and pancreas T2* (r = 0.672) showed positive correlation (all p < 0.05).

CONCLUSIONS

Patients with TDT exhibited significant organ-specific iron overload. These findings highlight the importance of routine MRI screening for monitoring and managing iron overload in patients with TDT. Pituitary, pancreas, and kidney may have similar iron-loading mechanisms.

Mitigating hemoglobin-induced nephropathy: ApoHb-hp protection of podocytes

This study investigates hemoglobin (Hb)-induced kidney injury and the protective role of the ApoHemoglobin-Haptoglobin (ApoHb-Hp) complex against heme and Hb damage. Hb facilitates oxygen (O2) delivery but poses challenges outside red blood cells (RBCs) due to toxic Hb and heme mechanisms. These are managed by binding to serum proteins like Haptoglobin (Hp) and Hemopexin (Hpx). During hemolysis, depletion of Hp and Hpx leaves tissues vulnerable to Hb and heme. To address this, we developed the ApoHb-Hp complex, based on Apohemoglobin, which is produced by removing heme from Hb, conjugated with Hp. This complex acts as a dual scavenger for Hb and heme, preventing tissue damage. Our findings demonstrate that ApoHb-Hp significantly protects MPC5 podocytes from Hb-induced damage. Fluorescent staining showed a higher percentage of nephrin-positive cells in the ApoHb-Hp group, and MTT assays revealed enhanced cell viability compared to Hb alone. Additionally, ApoHb-Hp reduced reactive oxygen species (ROS) production, with the Hb group exhibiting significantly elevated ROS levels. The ApoHb-Hp complex mitigated the depletion of protective mechanisms, as shown by significant increases in superoxide dismutase (SOD) and glutathione (GSH). Moreover, ApoHb-Hp treatment reduced the activation of the NLRP3 inflammasome signaling pathway and inflammatory cytokines IL-1β and IL-18. These findings underscore the therapeutic potential of ApoHb-Hp in mitigating Hb-induced renal damage by preserving podocyte viability and reducing oxidative stress. Overall, ApoHb-Hp maintained protective mechanisms depleted otherwise by Hb. These findings highlight ApoHb-Hp's potential as a therapeutic agent against Hb-induced renal damage, offering insights into its mechanisms and implications for treating conditions involving hemolysis.

Exploring alterations of gut/blood microbes in addressing iron overload-induced gut dysbiosis and cognitive impairment in thalassemia patients

Iron overload causes cognitive impairment in thalassemia patients. The gut-brain axis plays an important role in cognitive function. However, the association between gut/blood microbiome, cognition, and iron burden in thalassemia patients has not been thoroughly investigated. We aimed to determine those associations in thalassemia patients with different blood-transfusion regimens. Sixty participants: healthy controls, transfusion-dependent thalassemia (TDT) patients, and non-transfusion-dependent (NTDT) patients, were recruited to evaluate iron overload, cognition, and gut/blood microbiome. TDT patients exhibited greater iron overload than NTDT patients. Most thalassemia patients developed gut dysbiosis, and approximately 25% of the patients developed minor cognitive impairment. Increased Fusobacteriota and Verrucomicrobiota with decreased Fibrobacterota were observed in both TDT and NTDT groups. TDT patients showed more abundant beneficial bacteria: Verrucomicrobia. Iron overload was correlated with cognitive impairment. Increased Butyricimonas and decreased Paraclostridium were associated with higher cognitive function. No trace of blood microbiota was observed. Differences in blood bacterial profiles of thalassemia patients and controls were insignificant. These findings suggest iron overload plays a role in the imbalance of gut microbiota and impaired cognitive function in thalassemia patients. Harnessing probiotic potential from those microbes could prevent the gut-brain disturbance in thalassemia patients.

The dual loss and gain of function of the FPN1 iron exporter results in the ferroportin disease phenotype

Heterozygous mutations in SLC40A1, encoding a multi-pass membrane protein of the major facilitator superfamily known as ferroportin 1 (FPN1), are responsible for two distinct hereditary iron-overload diseases: ferroportin disease, which is associated with reduced FPN1 activity (i.e., decrease in cellular iron export), and SLC40A1-related hemochromatosis, which is associated with abnormally high FPN1 activity (i.e., resistance to hepcidin). Here, we report three SLC40A1 missense variants with opposite functional consequences. In cultured cells, the p.Arg40Gln and p.Ser47Phe substitutions partially reduced the ability of FPN1 to export iron and also partially reduced its sensitivity to hepcidin. The p.Ala350Val substitution had more profound effects, resulting in low FPN1 iron egress and weak FPN1/hepcidin interaction. Structural analyses helped to differentiate the first two substitutions, which are predicted to cause local instabilities, and the third, which is thought to prevent critical rigid-body movements that are essential to the iron transport cycle. The phenotypic traits observed in a total of 12 affected individuals are highly suggestive of ferroportin disease. Our findings dismantle the classical dualism of FPN1 loss versus gain of function, highlight some specific and unexpected functions of FPN1 transmembrane helices in the molecular mechanism of iron export and its regulation by hepcidin, and extend the spectrum of rare genetic variants that may cause ferroportin disease.

Antioxidative effects of N-acetylcysteine in patients with β-thalassemia: A quick review on clinical trials

Background and Aims

Several studies have highlighted the potent antioxidant properties of N-acetyl cysteine (NAC). This review aimed to assess the impact of NAC on oxidative stress biomarkers in patients with β-thalassemia.

Methods

The review included articles published before 2024 that investigated the effects of NAC on oxidative stress in individuals with β-thalassemia. A comprehensive search was conducted across various databases, including Scopus, PubMed, Web of Science, Trip, and CENTRAL. Only English-language clinical trials were considered for inclusion in this review. Besides, the number needed to treat (NNT) was calculated based on the included studies.

Results

Ninety-nine articles were retrieved from electronic databases, and after a thorough review, eight articles were selected for comprehensive text analysis. The highest dose of NAC administered was 10 mg/kg/day (equivalent to 600 mg/day) over a period of 3-6 months. All the studies assessing the impact of NAC on oxidative stress indicators in β-thalassemia patients demonstrated positive effects during the 3-month follow-up period. Most estimated NNTs fell into 1-5, suggesting significant clinical therapeutic value in this context.

Conclusion

The current potency of NAC alone appears to be effective in ameliorating oxidative stress in patients with β-thalassemia major. While a 3-month duration seems adequate to demonstrate the antioxidant properties of NAC in this population, larger and well-designed clinical trials are warranted. Current clinical evidence possesses a high risk of bias.

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.

Magnetic Resonance Evaluation of Tissue Iron Deposition and Cardiac Function in Adult Regularly Transfused Thalassemia Intermedia Compared with Thalassemia Major Patients

Objectives: This multicenter, retrospective, population-based, matched-cohort study compared clinical characteristics and magnetic resonance imaging (MRI) findings, including hepatic, pancreatic, and cardiac iron levels and cardiac function, between 135 adult regularly transfused thalassemia intermedia (TI) patients (44.73 ± 12.16 years, 77 females) and 135 age- and sex-matched thalassemia major (TM) patients (43.35 ± 9.83 years, 77 females), enrolled in the Extension-Myocardial Iron Overload in Thalassemia Network. Methods: The MRI protocol included the quantification of hepatic, pancreatic, and cardiac iron levels (R2* technique), the assessment of biventricular function parameters (cine images), and the detection of replacement myocardial fibrosis (late gadolinium enhancement technique). Results: Age, sex, frequency of splenectomy and chelation, and serum ferritin levels were not significantly different (p > 0.05) between the two groups, but TI patients started regular transfusions significantly later (p < 0.0001) and showed significantly lower pre-transfusion hemoglobin levels (p = 0.005). No difference was found in hepatic iron levels (p = 0.853). TI patients exhibited significantly lower pancreatic R2* values (p < 0.0001), also correcting for the duration of regular transfusions, and significantly lower cardiac R2* values (p < 0.0001). In the receiver operating characteristic analysis, pancreatic iron was the strongest discriminator between the two diseases. Left and right ventricular end-diastolic volume indexes were significantly higher in TI than in TM patients (p = 0.003 and p = 0.046, respectively), but the correction for the duration of regular transfusions removed the disease-specific differences (p > 0.05). Left ventricular (LV) mass index was significantly higher in TI (p = 0.049), while no difference (p > 0.05) was found in biventricular ejection fractions and replacement myocardial fibrosis. Conclusions: TI patients showed lower pancreatic and cardiac iron burden and more pronounced LV hypertrophy. These differences could not be explained by the different duration of the transfusional regimen.

Chronic dietary iron overload affects hepatic iron metabolism and cognitive behavior in Wistar rats

BACKGROUND

Iron accumulation in organs affects iron metabolism, leading to deleterious effects on the body. Previously, it was studied that high dietary iron in various forms and concentrations influences iron metabolism, resulting in iron accumulation in the liver and spleen and cognitive impairment. However, the actual mechanism and impact of long-term exposure to high dietary iron remain unknown. As a result, we postulated that iron overload caused by chronic exposure to excessive dietary iron supplementation would play a role in iron dyshomeostasis and inflammation in the liver and brain of Wistar rats.

METHODS

Animals were segregated into control, low iron (FAC-Ferric Ammonium Citrate 5000 ppm), and high iron dose group (FAC 20,000 ppm). The outcome of dietary iron overload on Wistar rats was evaluated in terms of body weight, biochemical markers, histological examination of liver and brain tissue, and cognitive-behavioral studies. Also, gene expression of rat brain tissue involving iron transporters Dmt1, TfR1, iron storage protein Fpn1, inflammatory markers Nf-kB, Tnf-α, Il-6, and hepcidin was performed.

RESULTS

Our data indicate that excess iron supplementation for 30 weeks leads to decreased body weight, increased serum iron levels, and decreased RBC levels in iron fed Wistar rats. Morris water maze (MWM) studies after 30 weeks showed increased escape latency in the high iron dose group compared with the control group. Histological studies of the high iron dose group showed an iron accumulation in the liver and brain loss of cellular architecture, and cellular degeneration was observed. Excess iron treatment showed upregulation of the Dmt1 gene in iron metabolism and a remarkable increase in the Nf-kB gene in rat brain tissue.

CONCLUSION

The results show chronic excess iron supplementation leads to iron accumulation in the liver, leading to inflammation in Wistar rats.

Intravenous Iron Repletion for Patients With Heart Failure and Iron Deficiency: JACC State-of-the-Art Review

Iron deficiency and heart failure frequently co-occur, sparking clinical research into the role of iron repletion in this condition over the last 20 years. Although early nonrandomized studies and subsequent moderate-sized randomized controlled trials showed an improvement in symptoms and functional metrics with the use of intravenous iron, 3 recent larger trials powered to detect a difference in hard cardiovascular outcomes failed to meet their primary endpoints. Additionally, there are potential concerns related to side effects from intravenous iron, both in the short and long term. This review discusses the basics of iron biology and regulation, the diagnostic criteria for iron deficiency and the clinical evidence for intravenous iron in heart failure, safety concerns, and alternative therapies. We also make practical suggestions for the management of patients with iron deficiency and heart failure and outline key areas in need of future research.

C-type lectin-like receptor-2 in platelets mediates ferric chloride-induced platelet activation and attenuates ferroptosis of endothelial cells

BACKGROUND

An iron overload status induces ferroptosis, an iron-dependent nonapoptotic cell death, in various pathological conditions. We previously reported that hemin (heme), protoporphyrin-IX with ferric iron, activates platelets via C-type lectin-like receptor-2 (CLEC-2) and glycoprotein VI/FcRγ, but protoporphyrin-IX alone blocks CLEC-2-dependent platelet activation. Therefore, we hypothesized that free iron has the ability to activate platelets.

OBJECTIVES

This study aimed to elucidate platelet activation mechanisms of iron (ferric chloride), including the identification of signaling pathways and receptors, and to examine whether platelets regulate ferroptosis.

METHODS

Platelet aggregometry, platelet activation marker expression, and protein phosphorylation were examined in ferric chloride-stimulated human and murine platelets. Inhibitors of platelet activation signaling pathways and receptor-deleted platelets were utilized to identify the responsible signaling pathway and receptor. The effect of platelets on ferroptosis of endothelial cells was investigated in vitro.

RESULTS

Ferric chloride induced platelet activation dependent on Src family kinase pathways in humans and mice. Ferric chloride-induced platelet aggregation was almost lost in CLEC-2-depleted murine platelets and wild-type platelets preincubated with recombinant CLEC-2 proteins. Furthermore, coculture of wild-type platelets, but not CLEC-2-deficient platelets, attenuated ferroptosis of endothelial cells in vitro.

CONCLUSION

Ferric chloride activates platelets via CLEC-2 and Src family kinase pathways, and platelets have a protective role in the ferroptosis of endothelial cells dependent on CLEC-2.

Reinforcing Protein Biochemistry: A Two-Week Experiment Studying Iron(III) Binding by the Transferrin Protein through Stoichiometric Determination, Stability Analysis, and Visualization of the Binding Site

The two-week protein biochemistry experience described herein focuses on reinforcing key biochemical concepts and achieving significant learning domain accomplishments for students (Content Knowledge, Logical Mathematical Reasoning, Visualization, Information Literacy, and Knowledge Integration) and valuable teaching opportunities for instructors. The experience encompasses an exploration of the transport protein serum transferrin as an important regulator of Fe(III) biochemistry and incorporates techniques to assess protein-metal stoichiometry and protein stability and to perform molecular visualization. Students gain practical experience in utilizing spectrophotometric analysis for constructing stoichiometric curves, in performing urea-PAGE, and in applying the PyMOL program to evaluate metal coordination at a protein binding site and the associated protein structural change. The learning and teaching accomplishments provide valuable skills that can be extended into research and translated to other teaching formats.

Iron, Copper, and Selenium: Cancer's Thing for Redox Bling

Cells require micronutrients for numerous basic functions. Among these, iron, copper, and selenium are particularly critical for redox metabolism, and their importance is heightened during oncogene-driven perturbations in cancer. In this review, which particularly focuses on iron, we describe how these micronutrients are carefully chaperoned about the body and made available to tissues, a process that is designed to limit the toxicity of free iron and copper or by-products of selenium metabolism. We delineate perturbations in iron metabolism and iron-dependent proteins that are observed in cancer, and describe the current approaches being used to target iron metabolism and iron-dependent processes.

Exploring the Specific Role of Iron Center in the Catalytic Activity of Human Serum Transferrin: CTAB-Induced Conformational Changes and Sequestration by Mixed Micelles

Conformational changes play a seminal role in modulating the activity of proteins. This concept becomes all the more relevant in the context of metalloproteins, owing to the formation of specific conformation(s) induced by internal perturbations (like a change in pH, ligand binding, or receptor binding), which may carry out the binding and release of the metal ion/ions from the metal binding center of the protein. Herein, we investigated the conformational changes of an iron-binding protein, monoferric human serum transferrin (Fe-hTF), using several spectroscopic approaches. We could reversibly tune the cetyltrimethylammonium bromide (CTAB)-induced conformation of the protein, exploiting the concept of mixed micelles formed by three sequestrating agents: (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) hydrate (CHAPS) and two bile salts, namely, sodium cholate (NaC) and sodium deoxycholate (NaDC). The formation of mixed micelles between CTAB and these reagents (CHAPS/NaC/NaDC) results in the sequestration of CTAB molecules from the protein environment and aids the protein in reattaining its native-like structure. However, the guanidinium hydrochloride-induced denatured Fe-hTF did not acquire its native-like structure using these sequestrating agents, which substantiates the exclusive role of mixed micelles in the present study. Apart from this, we found that the conformation of transferrin (adopted in the presence of CTAB) displays pronounced esterase-like activity toward the para-nitrophenyl acetate (PNPA) substrate as compared to native transferrin. We also outlined the impact of the iron center and amino acids surrounding the iron center on the effective catalytic activity in the CTAB medium. We estimated ∼3 times higher specific catalytic efficiency for the iron-depleted Apo-hTF compared to the fully iron-saturated Fe2-hTF in the presence of CTAB.

Iron homeostasis alterations and erectile dysfunction: A new issue in erectile disfunction treatment?

To the Editor, Erectile dysfunction (ED) is one of the most prevalent conditions affecting men globally, with significant psychological and social consequences. The prevalence varies across different populations, and it is estimated around 50% in men aged between 40 to 70. The etiology of ED is multifactorial, involving a complex crosstalk between psychological, hormonal, neurogenic, vascular, and structural factors [...].

Iron status and non-alcoholic fatty liver disease: A Mendelian randomization study

OBJECTIVES

The aim of this study was to assess the association of genetically determined iron status with the risk for non-alcoholic fatty liver disease (NAFLD) using two-sample Mendelian randomization (MR) analysis.

METHODS

We applied single nucleotide polymorphisms (SNPs) associated at genome-wide significance with iron status proxied by serum iron, ferritin, transferrin, and transferrin saturation from the Genetics of Iron status Consortium (N = 48 793), in a genome-wide association study of 1664 NAFLD cases and 400 055 controls from the United Kingdom Biobank. A SNP associated with multiple markers of iron status was only applied to one marker with the strongest association in the main analysis. Their effects on NAFLD were calculated using inverse variance weighting after excluding SNPs associated with alkaline phosphatase and lipid metabolism.

RESULTS

The risk for NAFLD is negatively associated with genetically predicted serum transferrin level with a 20% reduction in NAFLD risk per SD (0.65g/L) increase in transferrin (95% confidence interval [CI], 0.66-0.97), and trending positive association with transferrin saturation (odds ratio [OR], 1.50; 95% CI, 0.96-2.35) but it was not associated with serum iron (OR, 0.90; 95% CI, 0.63-1.29) and ferritin (OR, 1.33; 95% CI, 0.54-3.30).

CONCLUSIONS

MR analysis provided evidence that genetically predicted higher serum transferrin, indicating lower iron status, may be protective against NAFLD, whereas higher transferrin saturation, indicating higher iron status, might increase the risk for NAFLD and its pathogenesis.

CD4 + T cells ferroptosis is associated with the development of sepsis in severe polytrauma patients

BACKGROUND

Immunological disorder remains a great challenge in severe poly-trauma, in which lymphopenia is an important contributor. The purpose of present study is to explore whether ferroptosis, a new manner of programmed cell death (PCD), is involved in the lymphocyte depletion and predictive to the adverse prognosis of severe injuries.

PATIENTS AND METHODS

Severe polytrauma patients admitted from January 2022 to December 2022 in our trauma center were prospectively investigated. Peripheral blood samples were collected at admission (day 1), day 3 and day 7 from them. Included patients were classified based on whether they developed sepsis or not. Clinical outcomes, systematic inflammatory response, lymphocyte subpopulation, CD4 + T cell ferroptosis were collected, detected and analyzed.

RESULTS

Notable lymphopenia was observed on the first day after severe trauma and failed to normalize on the 7th day if patients were complicated with sepsis, in which CD4 + T cell was the subset of lymphocyte that depleted most pronouncedly. Lymphocyte loss was significantly correlated with the acute and biphasic systemic inflammatory response. Ferroptosis participated in the death of CD4 + T cells, potentially mediated by the downregulation of xCT-GSH-GPX4 pathway. CD4 + T cells ferroptosis had a conducive predicting value for the development of sepsis following severe trauma.

CONCLUSIONS

CD4 + T cells ferroptosis occurs early in the acute stage of severe polytrauma, which may become a promising biomarker and therapeutic target for post-traumatic sepsis.

[Oral microbiota and liver]

The liver has many important biological functions for the body, as it is involved in the storage and distribution of nutrients (carbohydrates to glycogen, lipids to triglycerides), the digestion of fats, the synthesis of blood proteins, and the detoxification of alcohol and drugs. The liver can be affected by various diseases such as viral or drug-induced hepatitis, fibrosis and cirrhosis, in which damaged hepatocytes are progressively replaced by scar tissue.

Mechanism of peroxidasin inactivation in hyperglycemia: Heme damage by reactive oxygen species

Diabetic complications present a serious health problem. Functional damage to proteins due to post-translational modifications by glycoxidation reactions is a known factor contributing to pathology. Extracellular proteins are especially vulnerable to diabetic damage because robust antioxidant defenses are lacking outside the cell. We investigated glucose-induced inactivation of peroxidasin (PXDN), a heme protein catalyzing sulfilimine crosslinking of collagen IV that reinforce the basement membranes (BM). Experiments using physiological diabetic glucose levels were carried out to exclude several potential mechanisms of PXDN inactivation i.e., direct adduction of glucose, reactive carbonyl damage, steric hindrance, and osmotic stress. Further experiments established that PXDN activity was inhibited via heme degradation by reactive oxygen species. Activity of another extracellular heme protein, myeloperoxidase, was unaffected by glucose because its heme was resistant to glucose-induced oxidative degradation. Our findings point to specific mechanisms which may compromise BM structure and stability in diabetes and suggest potential modes of protection.

A closer look at the role of iron in glioblastoma

Glioblastoma (GBM) is among the deadliest malignancies facing modern oncology. While our understanding of certain aspects of GBM biology has significantly increased over the last decade, other aspects, such as the role of bioactive metals in GBM progression, remain understudied. Iron is the most abundant transition metal found within the earth's crust and plays an intricate role in human physiology owing to its ability to participate in oxidation-reduction reactions. The importance of iron homeostasis in human physiology is apparent when examining the clinical consequences of iron deficiency or iron overload. Despite this, the role of iron in GBM progression has not been well described. Here, we review and synthesize the existing literature examining iron's role in GBM progression and patient outcomes, as well as provide a survey of iron's effects on the major cell types found within the GBM microenvironment at the molecular and cellular level. Iron represents an accessible target given the availability of already approved iron supplements and chelators. Improving our understanding of iron's role in GBM biology may pave the way for iron-modulating approaches to improve patient outcomes.

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.

Perturbations in lipid metabolism and gut microbiota composition precede cardiac dysfunction in a mouse model of thalassemia

Cardiomyopathy is a major complication of thalassemia, yet the precise underlying molecular mechanisms remain unclear. We examined whether altered lipid metabolism is an early driving factor in the development of cardiomyopathy using the Th3/+ mouse model of thalassemia. At age 20 weeks, male and female Th3/+ mice manifested anemia and iron overload; however, only males displayed metabolic defects and altered cardiac function. Untargeted lipidomics indicated that the circulating levels of 35 lipid species were significantly altered in Th3/+ mice compared to wild-type controls: triglycerides (TGs) with saturated fatty acids (FAs; TG42:0 and TG44:0) were elevated, while TGs with unsaturated FAs (TG(18:2_20:5_18:2 and TG54:8)) were reduced. Similarly, phosphatidylcholines (PCs) with long chain FAs (palmitic (16:0) or oleic (18:1)) were increased, while PCs with polyunsaturated FAs decreased. Circulating PC(16:0_14:0), GlcCer(d18:1/24:0) correlated significantly with iron overload and cardiac hypertrophy. 16S rRNA gene profiling revealed alterations in the intestinal microbiota of Th3/+ mice. Differentially abundant bacterial genera correlated with PC(39:6), PC(18:1_22:6), GlcCer(d18:1/24:1) and CE(14:0). These results provide new knowledge on perturbations in lipid metabolism and the gut microbiota of Th3/+ mice and identify specific factors which may represent early biomarkers or therapeutic targets to prevent development of cardiomyopathy in β-thalassemia.

Iron and atherosclerosis: Lessons learned from rabbits relevant to human disease

The role of iron in promoting atherosclerosis, and hence the cardiovascular, neurodegenerative and other diseases that result from atherosclerosis, has been fiercely controversial. Many studies have been carried out on various rodent models of atherosclerosis, especially on apoE-knockout (apoE-/-) mice, which develop atherosclerosis more readily than normal mice. These apoE-/- mouse studies generally support a role for iron in atherosclerosis development, although there are conflicting results. The purpose of the current article is to describe studies on another animal model that is not genetically manipulated; New Zealand White (NZW) rabbits fed a high-cholesterol diet. This may be a better model than the apoE-/- mice for human atherosclerosis, although it has been given much less attention. Studies on NZW rabbits support the view that iron promotes atherosclerosis, although some uncertainties remain, which need to be resolved by further experimentation.

Iron Homeostasis in Azotobacter vinelandii

Iron is an essential nutrient for all life forms. Specialized mechanisms exist in bacteria to ensure iron uptake and its delivery to key enzymes within the cell, while preventing toxicity. Iron uptake and exchange networks must adapt to the different environmental conditions, particularly those that require the biosynthesis of multiple iron proteins, such as nitrogen fixation. In this review, we outline the mechanisms that the model diazotrophic bacterium Azotobacter vinelandii uses to ensure iron nutrition and how it adapts Fe metabolism to diazotrophic growth.

Role of the SLC22A17/lipocalin-2 receptor in renal endocytosis of proteins/metalloproteins: a focus on iron- and cadmium-binding proteins

The transmembrane protein SLC22A17 [or the neutrophil gelatinase-associated lipocalin/lipocalin-2 (LCN2)/24p3 receptor] is an atypical member of the SLC22 family of organic anion and cation transporters: it does not carry typical substrates of SLC22 transporters but mediates receptor-mediated endocytosis (RME) of LCN2. One important task of the kidney is the prevention of urinary loss of proteins filtered by the glomerulus by bulk reabsorption of multiple ligands via megalin:cubilin:amnionless-mediated endocytosis in the proximal tubule (PT). Accordingly, overflow, glomerular, or PT damage, as in Fanconi syndrome, results in proteinuria. Strikingly, up to 20% of filtered proteins escape the PT under physiological conditions and are reabsorbed by the distal nephron. The renal distal tubule and collecting duct express SLC22A17, which mediates RME of filtered proteins that evade the PT but with limited capacity to prevent proteinuria under pathological conditions. The kidney also prevents excretion of filtered essential and nonessential transition metals, such as iron or cadmium, respectively, that are largely bound to proteins with high affinity, e.g., LCN2, transferrin, or metallothionein, or low affinity, e.g., microglobulins or albumin. Hence, increased uptake of transition metals may cause nephrotoxicity. Here, we assess the literature on SLC22A17 structure, topology, tissue distribution, regulation, and assumed functions, emphasizing renal SLC22A17, which has relevance for physiology, pathology, and nephrotoxicity due to the accumulation of proteins complexed with transition metals, e.g., cadmium or iron. Other putative renal functions of SLC22A17, such as its contribution to osmotic stress adaptation, protection against urinary tract infection, or renal carcinogenesis, are discussed.

A review of food contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin and its toxicity associated with metabolic disorders

Dioxins are a group of chemicals not only regarded as highly toxic trace environmental contaminants, but also considered typical contaminants in food. Dioxins spread across the ecosystem after factory manufacture, contaminate the soil and vegetation before either directly or indirectly entering the food chain through meat products, dairy products, and aquatic products. The compound in question poses a challenge for metabolic processes within the human body, due to its intricate mechanism for inducing diseases. Therefore, it presents a significant risk and is largely undisclosed. Dioxins are mainly exposed to humans by water, food, and air, as well as inducing organ failure and metabolic disorders through but not limited to the activation of aryl hydrocarbon receptors (AhR). As a notorious compound in the family of dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibits long-term toxic effects on diverse organs, which induces continuous metabolic disorders. This review discussed the mechanisms of TCDD-associated metabolic syndrome. The expression of the cytochrome P450 subfamily transfers TCDD into liver, promotes its accumulation in fat tissue, and affects cholesterol metabolism. This process also alters the glucose tolerance of the human organism, disrupting glucose metabolism. It can also elicit cardiovascular pathogenesis, exacerbate liver fibrosis and neuronal death. The long-term metabolic impact of this effect is found to be sex-related. This review summarized the toxicity of TCDD on the human metabolism system and discussed the plausible correlation between TCDD and five metabolic disorders, which helped offer novel insights for future research and therapeutic interventions for these ailments.

The effect of circulating iron on barrier integrity of primary human endothelial cells

Iron is hypothesized to be one of the contributors to cardiovascular disease and its levels in the circulation may correlate with cardiovascular risk. The aim of this study is to investigate the mechanisms that underlie the effects of iron on the barrier function of primary human endothelium. We used Human Umbilical Vein Endothelial Cells (HUVEC) to investigate the effects of Fe3+ using electric cell-substrate impedance sensing, microscopy, western blot and immunofluorescence microscopy. Exposure to Fe3+ caused EC elongation and upregulation of stress-induced proteins. Analysis of barrier function showed a dose-dependent drop in endothelial integrity, which was accompanied by Reactive Oxygen Species (ROS) production and could partly be prevented by ROS scavengers. Inhibition of contractility by the ROCK inhibitor Y27632, showed even more effective rescue of barrier integrity. Using western blot, we detected an increase in expression of the small GTPase RhoB, an inducer of EC contraction, and a small decrease in VE-cadherin, suggestive for an iron-induced stress response. Co-stimulation by TNFα and iron, used to investigate the role of low-grade inflammation, revealed an additive, negative effect on barrier integrity, concomitant with an upregulation of pro-inflammatory markers ICAM-1 and RhoB. Iron induces a response in HUVEC that leads to endothelial activation and a pro-inflammatory state measured by loss of barrier integrity which can be reversed by ROS scavengers, combined with inhibition of contractility. These data suggest that ROS-mediated damage of the vascular endothelium could contribute to the increased cardiovascular risk which is associated with elevated levels of circulating iron.

LncRNA SNHG1 upregulates FANCD2 and G6PD to suppress ferroptosis by sponging miR-199a-5p/3p in hepatocellular carcinoma

Ferroptosis is a form of regulated cell death (RCD) triggered by iron-dependent lipid peroxidation and is closely associated with the occurrence and progression of hepatocellular carcinoma (HCC). The lncRNA SNHG1 (small nucleolar RNA host gene 1) has been shown to play an oncogenic role in HCC, but its function in RCD other than autophagy and apoptosis is still unknown. Here, we investigated the correlation between SNHG1 and 156 typical markers of five RCD types based on RNA sequencing data from The Cancer Genome Atlas database and showed the negative regulators of ferroptosis FANCD2 (Fanconi anemia complementation group D2) and G6PD (glucose-6-phosphate dehydrogenase) to be the most highly and fifth most highly correlating factors with SNHG1, respectively. A competitive endogenous RNA network of SNHG1 - miR-199a-5p/3p - FANCD2/G6PD was constructed bioinformatically. In vitro experiments showed that overexpression of the miR-199a precursor led to a decrease in expression of SNHG1, FANCD2, and G6PD, whereas knockdown of SNHG1 decreased expression of FANCD2 and G6PD but increased levels of miR-199a-5p and miR-199a-3p in HCC cells (Huh7 and HepG2). In addition, knockdown of SNHG1 increased erastin-mediated ferroptosis, iron accumulation, and lipid peroxidation. These results suggest that SNHG1 upregulates FANCD2 and G6PD by sponging miR-199a, thereby inhibiting ferroptosis in HCC. Moreover, a signature based on expression of SNHG1, FANCD2, and G6PD was identified as being associated with overall survival and the immunological microenvironment in HCC. Collectively, this study identified the SNHG1-miR-199a-FANCD2/G6PD axis in HCC, which is a potential marker for the prognosis and therapy of this tumor.

The potential impact of hereditary hemochromatosis on the heart considering the disease stage and patient age-the role of echocardiography

Background

Hereditary hemochromatosis (HH) is a genetic disease that leads to increased iron accumulation in several organs. Cardiomyocytes are highly susceptible to this damage owing to their high iron uptake, and cardiovascular complications account for 1/3 of the deaths in the natural course of HH. Additionally, excess iron intake and associated oxidative stress may accelerate the aging of the cardiovascular system, regardless of the age of patients with HH. We aimed to investigate the role of standard and speckle-tracking echocardiography (STE) in revealing heart differences in patients with HH considering the disease stage and the patient age.

Methodology

Consecutive patients with HH (n = 58) without heart pathologies (except hypertension) and 29 age- and sex-matched healthy individuals underwent echocardiography. Patients were compared according to the time since HH diagnosis (the recently diagnosed HH group [31 patients] with diagnosed HH for less than 6 months and had no more than one venesection; the medium group [11 patients] with diagnosed HH between 6 and 24 months; and the long-lasting group [16 patients] with diagnosed HH for more than 2 years) and the quartile contribution of their age.

Results

Standard echocardiography revealed differences in diastolic parameters between patients with HH and controls, which were the most prominent between healthy and long-lasting HH patients. Regarding systolic function, left ventricular ejection fraction was lower in HH patients, with the most evident differences between the healthy and recently diagnosed HH patients. STE revealed additional differences in systolic parameters, with LV rotation the worst in recently diagnosed patients and its increase in patients with medium and long-lasting HH. Significantly worse peak systolic longitudinal strain values were observed in all patients with HH. Analyses of the results according to the age quartiles of patients with HH revealed that some changes ocurred earlier than expected according to age.

Conclusions

Echocardiography can reveal possible heart damage in HH patients at different stages of the disease and highlight potential features of accelerated myocardial aging in these patients.

Hepatocyte-specific damage in acute toxicity of sodium ferrous citrate: Presentation of a human autopsy case and experimental results in mice

Acute iron overload is known to exert deleterious effects in the liver, but detailed pathology has yet to be documented. Here, we report pathological findings in an autopsy case of acute iron toxicity and validation of the findings in mouse experiments. In a 39-year-old woman who intentionally ingested a large amount of sodium ferrous citrate (equivalent to 7.5 g of iron), severe disturbance of consciousness and fulminant hepatic failure rapidly developed. Liver failure was refractory to treatment and the patient died on Day 13. Autopsy revealed almost complete loss of hepatocytes, while bile ducts were spared. To examine the detailed pathologic processes induced by excessive iron, mice were orally administered equivalent doses of ferrous citrate. Plasma aminotransferase levels markedly increased after 6 h, which was preceded by increased plasma iron levels. Hepatocytes were selectively damaged, with more prominent damage in the periportal area. Phosphorylated c-Jun was detected in hepatocyte nuclei after 3 h, which was followed by the appearance of γ-H2AX expression. Hepatocyte injury in mice was associated with the expression of Myc and p53 after 12 and 24 h, respectively. Even at lethal doses, the bile ducts were morphologically intact and fully viable. Our findings indicate that acute iron overload induces hepatocyte-specific liver injury, most likely through hydroxyl radical-mediated DNA damage and subsequent stress responses.

Haemochromatosis

Haemochromatosis is one of the most common genetic diseases affecting patients of northern European ancestry. It is overdiagnosed in patients without iron overload and is underdiagnosed in many patients. Early diagnosis by genetic testing and therapy by periodic phlebotomy can prevent the most serious complications, which include liver cirrhosis, liver cancer, and death. This Seminar includes an update on the origins of haemochromatosis; and an overview pathophysiology, genetics, natural history, signs and symptoms, differential diagnoses, treatment with phlebotomy, outcomes, and future directions.

Non-transferrin-bound iron determination in blood serum using microsequential injection solid phase spectrometry- proof of concept

Non-transferrin-bound iron (NTBI) is a group of circulating toxic iron forms, which occur in iron overload or health conditions with dysregulation of iron metabolism. NTBI is responsible for increased oxidative stress and tissue iron loading. Despite its relevance as a biochemical marker in several diseases, a standardized assay is still lacking. Several methods were developed to quantify NTBI, but results show high inter-method and even inter-laboratory variability. Thus, the development of a consistent NTBI assay is a major goal in the management of iron overload and related clinical conditions. In this work, a micro sequential injection lab-on-valve (μSI-LOV) method in a solid phase spectrophotometry (SPS) mode was developed for the quantification of NTBI, using a bidentate 3,4-hydroxypyridinone (3,4-HPO) ligand anchored to sepharose beads as a chromogenic reagent. To attain SPS, the functionalized beads were packed into a column in the flow cell, and the analyte, NTBI retained as iron (III), formed a colored complex at the beads while eliminating the sample matrix. The dynamic concentration range was 1.62-7.16 μmol L^-1 of iron (III), with a limit of detection of 0.49 μmol L^-1 and a limit of quantification of 1.62 μmol L^-1. The proposed μSI-LOV-SPS method is a contribution to the development of an automatic method for the quantification of the NTBI in serum samples.

Labile plasma iron and echocardiographic parameters are associated with cardiac events in β-thalassemic patients

BACKGROUND AND AIM

Notwithstanding the improvement in therapies, patients affected by thalassemia major (TM) and intermedia (TI) are still at high risk of cardiac complications. This study aimed at evaluating the incidence and predictive factors for developing cardiac events in adult β-TM and TI patients.

POPULATION AND METHODS

Data on diagnosis and clinical history were collected retrospectively; prospective data on new-onset cardiac failure and arrhythmias, echocardiographic parameters, biochemical variables including non-transferrin-bound iron (NTBI) and labile plasma iron (LPI), magnetic resonance imaging (MRI) T2* measurement of hepatic and cardiac iron deposits, and iron chelation therapy were recorded during a 6-year follow-up.

RESULTS

Thirty-seven patients, 29 TM and 8 TI, were included. At baseline, 8 TM patients and 1 TI patient had previously experienced a cardiac event (mainly heart failure). All patients were on chelation therapy and only 3 TM patients had mild-to-severe cardiac siderosis. During follow-up, 11 patients (29.7%) experienced a new cardiac event. The occurrence of cardiac events was correlated to high LPI levels (OR 12.0, 95% CI 1.56-92.3, p .017), low mean pre-transfusion haemoglobin (OR 0.21, 95% C.I. 0.051-0.761, p .21) and echocardiographic parameters suggestive of myocardial hypertrophy. Multivariate analysis disclosed high LPI and left ventricle mass index (LVMI) as independent variables significantly associated with cardiac events. Cardiac iron deposits measured by MRI T2* failed to predict cardiac events.

CONCLUSION

LPI, Hb levels and echocardiographic parameters assessing cardiac remodelling are associated with cardiac events in adult TM and TI patients. LPI might represent both a prognostic marker and a potential target for novel treatment strategies. Further studies are warranted to confirm our findings on larger populations.

The role of tyrosine hydroxylase as a key player in neuromelanin synthesis and the association of neuromelanin with Parkinson's disease

The dark pigment neuromelanin (NM) is abundant in cell bodies of dopamine (DA) neurons in the substantia nigra (SN) and norepinephrine (NE) neurons in the locus coeruleus (LC) in the human brain. During the progression of Parkinson's disease (PD), together with the degeneration of the respective catecholamine (CA) neurons, the NM levels in the SN and LC markedly decrease. However, questions remain among others on how NM is associated with PD and how it is synthesized. The biosynthesis pathway of NM in the human brain has been controversial because the presence of tyrosinase in CA neurons in the SN and LC has been elusive. We propose the following NM synthesis pathway in these CA neurons: (1) Tyrosine is converted by tyrosine hydroxylase (TH) to L-3,4-dihydroxyphenylalanine (L-DOPA), which is converted by aromatic L-amino acid decarboxylase to DA, which in LC neurons is converted by dopamine β-hydroxylase to NE; (2) DA or NE is autoxidized to dopamine quinone (DAQ) or norepinephrine quinone (NEQ); and (3) DAQ or NEQ is converted to eumelanic NM (euNM) and pheomelanic NM (pheoNM) in the absence and presence of cysteine, respectively. This process involves proteins as cysteine source and iron. We also discuss whether the NM amounts per neuromelanin-positive (NM+) CA neuron are higher in PD brain, whether NM quantitatively correlates with neurodegeneration, and whether an active lifestyle may reduce NM formation.

Iron status among HIV-infected adults during the first year of antiretroviral therapy in Tanzania

BACKGROUND

The influence of inflammation on iron status among people living with HIV (PLWHIV) has not been well explored. We evaluated the trajectory of iron status among PLWHIV during the first year of highly active antiretroviral therapy (HAART), compared alternative approaches for inflammation correction, and assessed the associations of iron status with HIV-1 viral load and anthropometric outcomes.

METHODS

We conducted a secondary analysis of data from a randomized trial among 400 adults initiating HAART in Tanzania. Ferritin and C-reactive protein (CRP) were measured at baseline, 1, 6 or 12 months. Ferritin was considered in four ways: unadjusted, and adjusted for inflammation using higher cut-off (HC), Thurnham-corrected (TC) and regression-corrected (RC) approaches. For unadjusted, TC and RC ferritin, iron deficiency (ID) was defined using ferritin < 15 μg/L and elevated iron status was defined using ferritin > 150 μg/L among females and > 200 μg/L among males. For HC ferritin, elevated iron status was defined based on serum ferritin > 500 μg/L, while ID was defined using ferritin < 70 μg/L in the presence of inflammation and < 15 μg/L in the absence of inflammation. Regression models evaluated the trajectory of ferritin concentration across categories of baseline characteristics, and assessed the association of iron status with viral and anthropometric outcomes.

RESULTS

The prevalence of iron deficiency at HAART initiation was 9% for unadjusted, 17% for HC, 12% for TC and 22% for RC ferritin. The prevalence of elevated iron status was 42% for unadjusted, 18% for HC, 31% for TC, and 15% for RC ferritin. The prevalence of iron deficiency for all three methods increased during the first year of HAART, while the prevalence of elevated iron status decreased. Baseline elevated iron status defined using HC ferritin was associated with a greater risk of HIV-1 viral load > 1000 copies/mL [relative risk (RR) = 4.29, 95% CI: 1.38-13.3] and incidence of being underweight [body mass index (BMI) < 18.5 kg/m2 , hazard ratio (HR) = 3.65, 95% confidence interval (CI): 1.38-9.67]. Neither baseline-elevated iron status defined using TC or RC ferritin nor baseline iron deficiency defined using any of the three methods was associated with HIV-1 viral load or anthropometric outcomes.

CONCLUSIONS

Whether and how inflammation correction is done influences findings of studies of iron status among PLWHIV.

Hepcidin and its multiple partners: Complex regulation of iron metabolism in health and disease

The peptide hormone hepcidin is central to the regulation of iron metabolism, influencing the movement of iron into the circulation and determining total body iron stores. Its effect on a cellular level involves binding ferroportin, the main iron export protein, preventing iron egress and leading to iron sequestration within ferroportin-expressing cells. Hepcidin expression is enhanced by iron loading and inflammation and suppressed by erythropoietic stimulation. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis as occurs in anemia of chronic inflammation. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload such as hereditary hemochromatosis and iron loading anemias. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we assess the complex regulation of hepcidin, delineate the many binding partners involved in its regulation, and present an update on the development of hepcidin agonists and antagonists in various clinical scenarios.

Food Consumption of People with Sickle Cell Anemia in a Middle-Income Country

Sickle cell anemia (SCA) is a genetic and hemolytic disease globally characterized by social vulnerability. Food consumption has been insufficiently analyzed in SCA. Secondary iron overload is often observed. This leads to unreliable recommendations for dietary iron restriction. We assessed food consumption and iron intake among adults with SCA. Considering the guidelines for healthy eating, foods were grouped according to the NOVA classification. This transversal study included 74.4% of eligible patients who were registered in the reference center for SCA treatment in Rio de Janeiro, Brazil, in 2019. Data on food consumption were collected through 24 h recall. The monthly household income of 82.3% of patients was less than $770. The consumption of fresh or minimally processed foods was directly associated with monthly household income (p < 0.0001; η₂ = 0.87). Ultra-processed foods provided more than one-third of the total energy intake (35.2%). The prevalence of inadequate iron intake was about 40% among women, while that of iron intake above the tolerable upper limit was 0.8%. People from lower socioeconomic classes had the lowest iron intake. Strategies to encourage the consumption of fresh or minimally processed foods are needed considering the requirement of an antioxidant diet in SCA. These findings highlight the need for health equity to ensure food security and healthy eating in SCA.

Relationship between ferroptosis and mitophagy in cardiac ischemia reperfusion injury: a mini-review

Cardiovascular diseases (CVD), with high morbidity and mortality, seriously affect people's life and social development. Clinically, reperfusion therapy is typically used to treat ischemic cardiomyopathy, such as severe coronary heart disease and acute myocardial infarction. However, reperfusion therapy can lead to myocardial ischemia reperfusion injury (MIRI), which can affect the prognosis of patients. Studying the mechanisms of MIRI can help us improve the treatment of MIRI. The pathological process of MIRI involves many mechanisms such as ferroptosis and mitophagy. Ferroptosis can exacerbate MIRI, and regulation of mitophagy can alleviate MIRI. Both ferroptosis and mitophagy are closely related to ROS, but there is no clear understanding of the relationship between ferroptosis and mitophagy. In this review, we analyzed the relationship between ferroptosis and mitophagy according to the role of mTOR, NLPR3 and HIF. In addition, simultaneous regulation of mitophagy and ferroptosis may be superior to single therapy for MIRI. We summarized potential drugs that can regulate mitophagy and/or ferroptosis, hoping to provide reference for the development of drugs and methods for MIRI treatment.

Tissue iron distribution in patients with anemia of inflammation: Results of a pilot study

Anemia of inflammation (AI) is frequently present in subjects with inflammatory disorders, primarily caused by inflammation-driven iron retention in macrophages. So far, only limited data on qualitative and quantitative estimates of tissue iron retention in AI patients exist. We performed a prospective cohort study analyzing splenic, hepatic, pancreatic, and cardiac iron content with MRI-based R2*-relaxometry in AI patients, including subjects with concomitant true iron deficiency (AI+IDA) hospitalized between 05/2020-01/2022. Control groups were individuals without inflammation. Spleen R2* values in AI patients with ferritin ≤200 μg/L (AI+IDA) were comparable with those found in controls. In AI patients with ferritin >200 μg/L, spleen (47.6 s^-1 vs. 19.3 s^-1 , p < .001) and pancreatic R2* values (32.5 s^-1 vs. 24.9 s^-1 , p = .011) were significantly higher compared with controls, while liver and heart R2*-values did not differ. Higher spleen R2* values were associated with higher ferritin, hepcidin, CRP, and IL-6 concentrations. Spleen R2* values normalized in AI patients after recovery (23.6 s^-1 vs. 47.6 s^-1 , p = .008), while no changes were found in patients with baseline AI+IDA. This is the first study investigating tissue iron distribution in patients with inflammatory anemia and AI with concomitant true iron deficiency. The results support the findings in animal models demonstrating iron retention in macrophages, which are primarily accumulating in the spleen under inflammatory conditions. MRI-related iron measurement may help to better characterize actual iron needs and to define better biomarker thresholds in the diagnosis of true ID in patients with AI. It may qualify as a useful diagnostic method to estimate the need for iron supplementation and to guide therapy.

Interpreting Iron Homeostasis in Congenital and Acquired Disorders

Mammalian cells require iron to satisfy their metabolic needs and to accomplish specialized functions, such as hematopoiesis, mitochondrial biogenesis, energy metabolism, or oxygen transport. Iron homeostasis is balanced by the interplay of proteins responsible for iron import, storage, and export. A misbalance of iron homeostasis may cause either iron deficiencies or iron overload diseases. The clinical work-up of iron dysregulation is highly important, as severe symptoms and pathologies may arise. Treating iron overload or iron deficiency is important to avoid cellular damage and severe symptoms and improve patient outcomes. The impressive progress made in the past years in understanding mechanisms that maintain iron homeostasis has already changed clinical practice for treating iron-related diseases and is expected to improve patient management even further in the future.