Dysmetabolic iron overload syndrome (DIOS)

Iron overload is closely associated with metabolic dysfunction-associated fatty liver disease in type 2 diabetes

OBJECTIVE

The relationship between iron metabolism disturbances and metabolic dysfunction-associated fatty liver disease (MAFLD) remains controversial. This study aimed to investigate the association of iron overload with MAFLD in patients with type 2 diabetes mellitus (T2DM).

METHODS

This study included 155 Chinese inpatients with T2DM. MAFLD was diagnosed and grouped using magnetic resonance imaging (MRI). MRI biomarkers such as proton density fat fraction and iron accumulation (R 2 * ) were measured. Their clinical characteristics were compared, and the association of iron metabolism markers with MAFLD in patients with T2DM was analyzed.

RESULTS

Iron metabolism markers, including MRI-R 2 * , ferritin, serum iron, hepcidin, and total iron-binding capacity, were overloaded in groups with MAFLD (p < 0.001 for trend). They were positively correlated with MAFLD and reflected the severity of MAFLD. The five markers of logistic regression analysis revealed an increased MAFLD risk (p < 0.001 for trend). The areas under the curve of five markers all exceeded 0.5, indicating certain predictive values for MAFLD.

CONCLUSIONS

MAFLD is associated with significant iron overload in Chinese patients with T2DM. Serum iron, ferritin, total iron-binding capacity, hepcidin, andR 2 * value are essential iron metabolism markers to evaluate and predict the progression of MAFLD in patients with T2DM.

Exploring the Role of Metabolic Hyperferritinaemia (MHF) in Steatotic Liver Disease (SLD) and Hepatocellular Carcinoma (HCC)

The increasing prevalence of the spectrum of Steatotic Liver Disease (SLD), including Metabolic-Associated Steatotic Liver Disease (MASLD), Metabolic-Associated Steatohepatitis (MASH), and progression to Cirrhosis and Hepatocellular Carcinoma (HCC) has led to intense research in disease pathophysiology, with many studies focusing on the role of iron. Iron overload, which is often observed in patients with SLD as a part of metabolic hyperferritinaemia (MHF), particularly in the reticuloendothelial system (RES), can exacerbate steatosis. This imbalance in iron distribution, coupled with a high-fat diet, can further promote the progression of SLD by means of oxidative stress triggering inflammation and activating hepatic stellate cells (HSCs), therefore leading to fibrosis and progression of simple steatosis to the more severe MASH. The influence of iron overload in disease progression has also been shown by the complex role of ferroptosis, a type of cell death driven by iron-dependent lipid peroxidation. Ferroptosis depletes the liver's antioxidant capacity, further contributing to the development of MASH, while its role in MASH-related HCC is potentially linked to alternations in the tumour microenvironment, as well as ferroptosis resistance. The iron-rich steatotic hepatic environment becomes prone to hepatocarcinogenesis by activation of several pro-carcinogenic mechanisms including epithelial-to-mesenchymal transition and deactivation of DNA damage repair. Biochemical markers of iron overload and deranged metabolism have been linked to all stages of SLD and its associated HCC in multiple patient cohorts of diverse genetic backgrounds, enhancing our daily clinical understanding of this interaction. Further understanding could lead to enhanced therapies for SLD management and prevention.

Weight loss induced by a hypocaloric diet with or without fish oil supplementation re-established iron and omega-3 fatty acid homeostasis in middle-aged women with obesity: A post-hoc analysis of a randomized controlled trial

OBJECTIVE

Middle-aged women with obesity are at increased risk of iron overload and iron disorder is known to disrupt n-3 polyunsaturated fatty acid homeostasis. We evaluated relationships between pretreatment hemoglobin and n-3 polyunsaturated fatty acid levels, and tested whether pretreatment hemoglobin contributed to inter-individual variability in weight loss with special focus on changes in body weight, iron and n-3 polyunsaturated fatty acid profiles.

STUDY DESIGN

117 middle and older aged women with obesity and more than two metabolic abnormalities were randomized to a 12-week hypocaloric diet without or with fish oil supplementation. Blood iron biomarker and erythrocyte membrane phospholipid profiles were evaluated.

MAIN OUTCOME

The absolute change from baseline to week 12 in serum iron and erythrocyte n-3 polyunsaturated fatty acid levels according to pretreatment hemoglobin tertiles and fish oil supplementation.

RESULTS

A Pearson correlation analysis showed that pretreatment hemoglobin levels were negatively correlated with linoleic acid (r = -0.231), α-linoleic acid (r = -0.279), and n-3 polyunsaturated fatty acid (r = -0.217) (all p < 0.05). Dietary weight loss markedly enhanced erythrocyte membrane lipids of linoleic acid, α-linoleic acid, and n-6 and n-3 polyunsaturated fatty acid only in those women with the highest pretreatment hemoglobin levels (tertile 3) (all p < 0.05). Fish oil supplementation increased bioavailable iron in women with moderate pretreatment hemoglobin levels (tertile 2) (p < 0.05) and, to a lesser extent, prevented a reduction in circulating iron in those with the lowest hemoglobin levels (tertile 1).

CONCLUSION

Dietary weight loss is an effective treatment program to manage obesity-related iron and n-3 polyunsaturated fatty acid disorders, particularly for middle-aged women with obesity and iron overload.

Liver steatosis in patients with transfusion-dependent thalassaemia

We evaluated the prevalence and the clinical associations of liver steatosis (LS) in patients with transfusion-dependent thalassaemia (TDT). We considered 301 TDT patients (177 females, median age = 40.61 years) enrolled in the Extension-Myocardial Iron Overload in Thalassaemia Network, and 25 healthy subjects. Magnetic resonance imaging was used to quantify iron overload and hepatic fat fraction (FF) by T2* technique and cardiac function by cine images. The glucose metabolism was assessed by the oral glucose tolerance test (OGTT). Hepatic FF was significantly higher in TDT patients than in healthy subjects (median value: 1.48% vs. 0.55%; p = 0.013). In TDT, hepatic FF was not associated with age, gender, serum ferritin levels or liver function parameters, but showed a weak inverse correlation with high-density lipoprotein cholesterol. The 36.4% of TDT patients showed LS (FF >3.7%). Active hepatitis C virus (HCV) infection, increased body mass index and hepatic iron were independent determinants of LS. A hepatic FF >3.53% predicted the presence of an abnormal OGTT. Hepatic FF was not correlated with cardiac iron, biventricular volumes or ejection fractions, but was correlated with left ventricular mass index. In TDT, LS is a frequent finding, associated with iron overload, increased weight and HCV, and conveying an increased risk for the alterations of glucose metabolism.

Prevalence and Characteristics of Metabolic Hyperferritinemia in a Population-Based Central-European Cohort

BACKGROUND

Hyperferritinemia (HF) is a common finding and can be considered as metabolic HF (MHF) in combination with metabolic diseases. The definition of MHF was heterogenous until a consensus statement was published recently. Our aim was to apply the definition of MHF to provide data on the prevalence and characteristics of MHF in a Central-European cohort.

METHODS

This study was a retrospective analysis of the Paracelsus 10,000 study, a population-based cohort study from the region of Salzburg, Austria. We included 8408 participants, aged 40-77. Participants with HF were divided into three categories according to their level of HF and evaluated for metabolic co-morbidities defined by the proposed criteria for MHF.

RESULTS

HF was present in 13% (n = 1111) with a clear male preponderance (n = 771, 69% of HF). Within the HF group, 81% (n = 901) of subjects fulfilled the metabolic criteria and were defined as MHF, of which 75% (n = 674) were characterized by a major criterion. In the remaining HF cohort, 52% (n = 227 of 437) of subjects were classified as MHF after application of the minor criteria.

CONCLUSION

HF is a common finding in the general middle-aged population and the majority of cases are classified as MHF. The new classification provides useful criteria for defining MHF.

[Diagnosis and treatment of iron overload]

Etiological investigation of hyperferritinemia includes a full clinical examination, with the measurement of waist circumference, and simple biological tests including transferrin saturation. The classification between hyperferritinemia without iron overload (inflammation, excessive alcohol intake, cytolysis, L-ferritin mutation) or with iron overload is then relatively easy. Dysmetabolic iron overload syndrome is the most common iron overload disease and is defined by an unexplained serum ferritin level elevation associated with various metabolic syndrome criteria and mild hepatic iron content increase assessed by magnetic resonance imaging. Bloodlettings are often poorly tolerated without clear benefit. Type 1 genetic hemochromatosis (homozygous C282Y mutation on the HFE gene) leads to iron accumulation through an increase of dietary iron absorption due to hypohepcidinemia. More than 95% of hemochromatosis are type 1 hemochromatosis but the phenotypic expression is highly variable. Elastography is recommended to identify advanced hepatic fibrosis when serum ferritin exceeds 1000μg/L. Life expectancy is normal when bloodlettings are started early. Ferroportin gene mutation is an autosomal dominant disease with generally moderate iron overload. Chelators are used in iron overload associated with anaemia (myelodysplastic syndromes or transfusion-dependent thalassemia). Chelation is initiated when hepatic iron content exceeds 120μmol/g. Deferasirox is often used as first-line therapy, but deferiprone may be of interest despite haematological toxicity (neutropenia). Deferoxamine (parenteral route) is the treatment of choice for severe iron overload or emergency conditions.

Djulis Hull Enhances the Efficacy of Ferric Citrate Supplementation via Restoring Normal Iron Efflux through the IL-6-Hepcidin-Ferroportin Pathway in High-Fat-Diet-Induced Obese Rats

Obesity-related functional iron disorder remains a major nutritional challenge. We evaluated the effects of djulis hull (DH) on iron metabolism in 50% high-fat-diet-induced obese rats supplemented with ferric citrate (2 g iron/kg diet) for 12 weeks. DH supplementation (5, 10, 15% dry weight/kg diet) significantly increased serum and hepatic iron but decreased appetite hormones, body weight, hepcidin, and liver inflammation (all p < 0.05). The Spearman correlation showed that appetite hormones were negatively associated with iron but positively correlated with liver hepcidin (all p < 0.05). A Western blot analysis showed that DH significantly downregulated hepatic hepcidin through the IL-6-JAK-STAT3 and enhanced ferroportin (Fpn) via the Keap1-Nrf2 and PHD2-HIF-2α. An in vitro study revealed that major bioactive compounds of DH, hexacosanol, and squalene suppressed LPS-induced IL-6 and hepcidin but enhanced Fpn expression in activated THP-1 cells. In conclusion, DH may exert nutraceutical properties for the treatment of functional iron disorder and restoration of iron efflux may have beneficial effects on weight control.

Consensus Statement on the definition and classification of metabolic hyperferritinaemia

Hyperferritinaemia is a common laboratory finding that is often associated with metabolic dysfunction and fatty liver. Metabolic hyperferritinaemia reflects alterations in iron metabolism that facilitate iron accumulation in the body and is associated with an increased risk of cardiometabolic and liver diseases. Genetic variants that modulate iron homeostasis and tissue levels of iron are the main determinants of serum levels of ferritin in individuals with metabolic dysfunction, raising the hypothesis that iron accumulation might be implicated in the pathogenesis of insulin resistance and the related organ damage. However, validated criteria for the non-invasive diagnosis of metabolic hyperferritinaemia and the staging of iron overload are still lacking, and there is no clear evidence of a benefit for iron depletion therapy. Here, we provide an overview of the literature on the relationship between hyperferritinaemia and iron accumulation in individuals with metabolic dysfunction, and on the associated clinical outcomes. We propose an updated definition and a provisional staging system for metabolic hyperferritinaemia, which has been agreed on by a multidisciplinary global panel of expert researchers. The goal is to foster studies into the epidemiology, genetics, pathophysiology, clinical relevance and treatment of metabolic hyperferritinaemia, for which we provide suggestions on the main unmet needs, optimal design and clinically relevant outcomes.

Magnetic Resonance Liver Iron Concentration Can Guide Venesection Decision-Making in Hyperferritinemia

BACKGROUND

The clinical benefit of venesection in suspected iron overload can be unclear and serum ferritin may overestimate the degree of iron overload.

AIMS

To help inform practice, we examined magnetic resonance liver iron concentration (MRLIC) in a cohort investigated for haemochromatosis.

METHODS

One hundred and six subjects with suspected haemochromatosis underwent HFE genotyping and MRLIC with time-matched serum ferritin and transferrin saturation values. For those treated with venesection, volume of blood removed was calculated as a measure of iron overload.

RESULTS

Forty-seven C282Y homozygotes had median ferritin 937 µg/l and MRLIC 4.83 mg/g; MRLIC was significantly higher vs non-homozygotes for any given ferritin concentration. No significant difference in MRLIC was observed between homozygotes with and without additional risk factors for hyperferritinemia. Thirty-three compound heterozygotes (C282Y/H63D) had median ferritin 767 µg/l and MRLIC 2.58 mg/g; ferritin < 750 µg/l showed 100% specificity for lack of significant iron overload (< 3.2 mg/g). 79% of C282Y/H63D had additional risk factors-mean MRLIC was significantly lower in this sub-group (2.4 mg/g vs 3.23 mg/g). 26 C282Y heterozygous or wild-type had median ferritin 1226 µg/l and MRLIC 2.13 mg/g; 69% with additional risk factors had significantly higher ferritin concentrations (with comparable MRLIC) and ferritin < 1000 µg/l showed 100% specificity for lack of significant iron overload. In 31 patients (26 homozygotes, 5 C282Y/H63D) venesected to ferritin < 100 µg/l, MRLIC and total venesection volume correlated strongly (r = 0.749), unlike MRLIC and serum ferritin.

CONCLUSION

MRLIC is an accurate marker of iron overload in haemochromatosis. We propose serum ferritin thresholds in non-homozygotes which, if validated, could tailor cost-effective use of MRLIC in venesection decision-making.

Relationship between iron overload caused by abnormal hepcidin expression and liver disease: A review

Iron is essential to organisms, the liver plays a vital role in its storage. Under pathological conditions, iron uptake by the intestine or hepatocytes increases, allowing excess iron to accumulate in liver cells. When the expression of hepcidin is abnormal, iron homeostasis in humans cannot be regulated, and resulting in iron overload. Hepcidin also regulates the release of iron from siderophores, thereby regulating the concentration of iron in plasma. Important factors related to hepcidin and systemic iron homeostasis include plasma iron concentration, body iron storage, infection, inflammation, and erythropoietin. This review summarizes the mechanism and regulation of iron overload caused by hepcidin, as well as related liver diseases caused by iron overload and treatment.

Iron metabolism and ferroptosis in type 2 diabetes mellitus and complications: mechanisms and therapeutic opportunities

The maintenance of iron homeostasis is essential for proper endocrine function. A growing body of evidence suggests that iron imbalance is a key factor in the development of several endocrine diseases. Nowadays, ferroptosis, an iron-dependent form of regulated cell death, has become increasingly recognized as an important process to mediate the pathogenesis and progression of type 2 diabetes mellitus (T2DM). It has been shown that ferroptosis in pancreas β cells leads to decreased insulin secretion; and ferroptosis in the liver, fat, and muscle induces insulin resistance. Understanding the mechanisms concerning the regulation of iron metabolism and ferroptosis in T2DM may lead to improved disease management. In this review, we summarized the connection between the metabolic pathways and molecular mechanisms of iron metabolism and ferroptosis in T2DM. Additionally, we discuss the potential targets and pathways concerning ferroptosis in treating T2DM and analysis the current limitations and future directions concerning these novel T2DM treatment targets.

Discovery-Based Proteomics Identify Skeletal Muscle Mitochondrial Alterations as an Early Metabolic Defect in a Mouse Model of β-Thalassemia

Although metabolic complications are common in thalassemia patients, there is still an unmet need to better understand underlying mechanisms. We used unbiased global proteomics to reveal molecular differences between the th^3/+ mouse model of thalassemia and wild-type control animals focusing on skeletal muscles at 8 weeks of age. Our data point toward a significantly impaired mitochondrial oxidative phosphorylation. Furthermore, we observed a shift from oxidative fibre types toward more glycolytic fibre types in these animals, which was further supported by larger fibre-type cross-sectional areas in the more oxidative type fibres (type I/type IIa/type IIax hybrid). We also observed an increase in capillary density in th^3/+ mice, indicative of a compensatory response. Western blotting for mitochondrial oxidative phosphorylation complex proteins and PCR analysis of mitochondrial genes indicated reduced mitochondrial content in the skeletal muscle but not the hearts of th^3/+ mice. The phenotypic manifestation of these alterations was a small but significant reduction in glucose handling capacity. Overall, this study identified many important alterations in the proteome of th^3/+ mice, amongst which mitochondrial defects leading to skeletal muscle remodelling and metabolic dysfunction were paramount.

Iron and the Pathophysiology of Diabetes

High iron is a risk factor for type 2 diabetes mellitus (T2DM) and affects most of its cardinal features: decreased insulin secretion, insulin resistance, and increased hepatic gluconeogenesis. This is true across the normal range of tissue iron levels and in pathologic iron overload. Because of iron's central role in metabolic processes (e.g., fuel oxidation) and metabolic regulation (e.g., hypoxia sensing), iron levels participate in determining metabolic rates, gluconeogenesis, fuel choice, insulin action, and adipocyte phenotype. The risk of diabetes related to iron is evident in most or all tissues that determine diabetes phenotypes, with the adipocyte, beta cell, and liver playing central roles. Molecular mechanisms for these effects are diverse, although there may be integrative pathways at play. Elucidating these pathways has implications not only for diabetes prevention and treatment, but also for the pathogenesis of other diseases that are, like T2DM, associated with aging, nutrition, and iron.

Hereditary Hyperferritinemia

Ferritin is a ubiquitous protein that is present in most tissues as a cytosolic protein. The major and common role of ferritin is to bind Fe²⁺, oxidize it and sequester it in a safe form in the cell, and to release iron according to cellular needs. Ferritin is also present at a considerably low proportion in normal mammalian sera and is relatively iron poor compared to tissues. Serum ferritin might provide a useful and convenient method of assessing the status of iron storage, and its measurement has become a routine laboratory test. However, many additional factors, including inflammation, infection, metabolic abnormalities, and malignancy-all of which may elevate serum ferritin-complicate interpretation of this value. Despite this long history of clinical use, fundamental aspects of the biology of serum ferritin are still unclear. According to the high number of factors involved in regulation of ferritin synthesis, secretion, and uptake, and in its central role in iron metabolism, hyperferritinemia is a relatively common finding in clinical practice and is found in a large spectrum of conditions, both genetic and acquired, associated or not with iron overload. The diagnostic strategy to reveal the cause of hyperferritinemia includes family and personal medical history, biochemical and genetic tests, and evaluation of liver iron by direct or indirect methods. This review is focused on the forms of inherited hyperferritinemia with or without iron overload presenting with normal transferrin saturation, as well as a step-by-step approach to distinguish these forms to the acquired forms, common and rare, of isolated hyperferritinemia.

Dysmetabolic Iron Overload Syndrome: Going beyond the Traditional Risk Factors Associated with Metabolic Syndrome

Dysmetabolic iron overload syndrome (DIOS) corresponds to the increase in iron stores associated with components of metabolic syndrome (MtS) and in the absence of an identifiable cause of iron excess. The objective of this work was to review the main aspects of DIOS. PUBMED and EMBASE were consulted, and PRISMA guidelines were followed. DIOS is usually asymptomatic and can be diagnosed by investigating MtS and steatosis. About 50% of the patients present altered hepatic biochemical tests (increased levels of γ-glutamyl transpeptidase itself or associated with increased levels of alanine aminotransferase). The liver may present parenchymal and mesenchymal iron overload, but the excess of iron is commonly mild. Steatosis or steatohepatitis is observed in half of the patients. Fibrosis is observed in about 15% of patients. Hyperferritinemia may damage the myocardium, liver, and several other tissues, increasing morbidity and mortality. Furthermore, DIOS is closely related to oxidative stress, which is closely associated with several pathological conditions such as inflammatory diseases, hypertension, diabetes, heart failure, and cancer. DIOS is becoming a relevant finding in the general population and can be associated with high morbidity/mortality. For these reasons, investigation of this condition could be an additional requirement for the early prevention of cardiovascular diseases.

Role of Mitochondrial Iron Overload in Mediating Cell Death in H9c2 Cells

Iron overload (IO) is associated with cardiovascular diseases, including heart failure. Our study's aim was to examine the mechanism by which IO triggers cell death in H9c2 cells. IO caused accumulation of intracellular and mitochondrial iron as shown by the use of iron-binding fluorescent reporters, FerroOrange and MitoFerroFluor. Expression of cytosolic and mitochondrial isoforms of Ferritin was also induced by IO. IO-induced iron accumulation and cellular ROS was rapid and temporally linked. ROS accumulation was detected in the cytosol and mitochondrial compartments with CellROX, DCF-DA and MitoSOX fluorescent dyes and partly reversed by the general antioxidant N-acetyl cysteine or the mitochondrial antioxidant SkQ1. Antioxidants also reduced the downstream activation of apoptosis and lytic cell death quantified by Caspase 3 cleavage/activation, mitochondrial Cytochrome c release, Annexin V/Propidium iodide staining and LDH release of IO-treated cells. Finally, overexpression of MitoNEET, an outer mitochondrial membrane protein involved in the transfer of Fe-S clusters between mitochondrial and cytosol, was observed to lower iron and ROS accumulation in the mitochondria. These alterations were correlated with reduced IO-induced cell death by apoptosis in MitoNEET-overexpressing cells. In conclusion, IO mediates H9c2 cell death by causing mitochondrial iron accumulation and subsequent general and mitochondrial ROS upregulation.

Dietary iron overload enhances Western diet induced hepatic inflammation and alters lipid metabolism in rats sharing similarity with human DIOS

Hepatic iron overload is often concurrent with nonalcoholic fatty liver disease (NAFLD). Dysmetabolic iron overload syndrome (DIOS) is characterized by an increase in the liver and body iron stores and metabolic syndrome components. Increasing evidences suggest an overlap between NAFLD with iron overload and DIOS; however, the mechanism how iron is involved in their pathogenesis remains unclear. Here we investigated the role of iron in the pathology of a rat model of NAFLD with iron overload. Rats fed a Western (high-fat and high-fructose) diet for 26 weeks represented hepatic steatosis with an increased body weight and dyslipidemia. Addition of dietary iron overload to the Western diet feeding further increased serum triglyceride and cholesterol, and enhanced hepatic inflammation; the affected liver had intense iron deposition in the sinusoidal macrophages/Kupffer cells, associated with nuclear translocation of NFκB and upregulation of Th1/M1-related cytokines. The present model would be useful to investigate the mechanism underlying the development and progression of NAFLD as well as DIOS, and to elucidate an important role of iron as one of the "multiple hits" factors.

The role of iron metabolism in chronic diseases related to obesity

Obesity is one of the major public health problems threatening the world, as well as a potential risk factor for chronic metabolic diseases. There is growing evidence that iron metabolism is altered in obese people, however, the highly refined regulation of iron metabolism in obesity and obesity-related complications is still being investigated. Iron accumulation can affect the body’s sensitivity to insulin, Type 2 diabetes, liver disease and cardiovascular disease. This review summarized the changes and potential mechanisms of iron metabolism in several chronic diseases related to obesity, providing new clues for future research.

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.

EASL Clinical Practice Guidelines on haemochromatosis

Haemochromatosis is characterised by elevated transferrin saturation (TSAT) and progressive iron loading that mainly affects the liver. Early diagnosis and treatment by phlebotomy can prevent cirrhosis, hepatocellular carcinoma, diabetes, arthropathy and other complications. In patients homozygous for p.Cys282Tyr in HFE, provisional iron overload based on serum iron parameters (TSAT >45% and ferritin >200 μg/L in females and TSAT >50% and ferritin >300 μg/L in males and postmenopausal women) is sufficient to diagnose haemochromatosis. In patients with high TSAT and elevated ferritin but other HFE genotypes, diagnosis requires the presence of hepatic iron overload on MRI or liver biopsy. The stage of liver fibrosis and other end-organ damage should be carefully assessed at diagnosis because they determine disease management. Patients with advanced fibrosis should be included in a screening programme for hepatocellular carcinoma. Treatment targets for phlebotomy are ferritin <50 μg/L during the induction phase and <100 μg/L during the maintenance phase.

Non-invasive methods for iron overload evaluation in dysmetabolic patients

INTRODUCTION

Although hyperferritinemia may reflect the inflammatory status of patients with non-alcoholic fatty liver disease (NAFLD), approximately 33% of hyperferritinemia cases reflect real hepatic iron overload.

AIM

To evaluate a non-invasive method for assessing mild iron overload in patients with NAFLD using 3T magnetic resonance imaging (MRI) relaxometry, serum hepcidin, and the expression of ferritin subunits.

METHODS

This cross-sectional study assessed patients with biopsy-proven NAFLD. MRI relaxometry was performed using a 3T scanner in all patients, and the results were compared with iron content determined by liver biopsy. Ferritin, hepcidin, and ferritin subunits were assessed and classified according to ferritin levels and to siderosis identified by liver biopsy.

RESULTS

A total of 67 patients with NAFLD were included in the study. MRI revealed mild iron overload in all patients (sensitivity, 73.5%; specificity, 70%). For mild (grade 1) siderosis, the transverse relaxation rate (R2*) threshold was 58.9 s-1 and the mean value was 72.5 s-1 (SD, 33.9), while for grades 2/3 it was 88.2 s-1 (SD, 31.9) (p < 0.001). The hepcidin threshold for siderosis was > 30.2 ng/mL (sensitivity, 87%; specificity, 82%). Ferritin H and ferritin L subunits were expressed similarly in patients with NAFLD, regardless of siderosis. There were no significant differences in laboratory test results between the groups, including glucose parameters and liver function tests.

CONCLUSIONS

MRI relaxometry and serum hepcidin accurately assessed mild iron overload in patients with dysmetabolic iron overload syndrome.

Paying the Iron Price: Liver Iron Homeostasis and Metabolic Disease

Iron is an essential metal element whose bioavailability is tightly regulated. Under normal conditions, systemic and cellular iron homeostases are synchronized for optimal function, based on the needs of each system. During metabolic dysfunction, this synchrony is lost, and markers of systemic iron homeostasis are no longer coupled to the iron status of key metabolic organs such as the liver and adipose tissue. The effects of dysmetabolic iron overload syndrome in the liver have been tied to hepatic insulin resistance, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. While the existence of a relationship between iron dysregulation and metabolic dysfunction has long been acknowledged, identifying correlative relationships is complicated by the prognostic reliance on systemic measures of iron homeostasis. What is lacking and perhaps more informative is an understanding of how cellular iron homeostasis changes with metabolic dysfunction. This article explores bidirectional relationships between different proteins involved in iron homeostasis and metabolic dysfunction in the liver. © 2022 American Physiological Society. Compr Physiol 12:3641-3663, 2022.

Nonalcoholic Fatty Liver Disease and the Gut-Liver Axis: Exploring an Undernutrition Perspective

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition affecting one quarter of the global population. Although primarily linked to obesity and metabolic syndrome, undernutrition and the altered (dysbiotic) gut microbiome influence NAFLD progression. Both undernutrition and NAFLD prevalence are predicted to considerably increase, but how the undernourished gut microbiome contributes to hepatic pathophysiology remains far less studied. Here, we present undernutrition conditions with fatty liver features, including kwashiorkor and micronutrient deficiency. We then review the gut microbiota-liver axis, highlighting key pathways linked to NAFLD progression within both overnutrition and undernutrition. To conclude, we identify challenges and collaborative possibilities of emerging multiomic research addressing the pathology and treatment of undernourished NAFLD.

DNA methylation plays an important role in iron-overloaded Tibetans

The prevalence of iron overload in Tibetans in Tibet is higher than that in Han. DNA methylation (DNAm) is closely related to iron metabolism and iron level. Nevertheless, the epigenetic status of Tibetans with iron overload is unknown, and we therefore aimed to explore whether the phenomenon observed in the Tibetan population is regulated by epigenetics. The results showed that 2.26% of cytosine was methylated in the whole genome, and that the rate of CG cytosine methylation was higher in individuals in the iron overload (TH) group than in those in the iron normal (TL) group. We analyzed differentially methylated genes (DMGs) in whole-genome bisulfite sequencing data from the TH and TL groups of high-altitude Tibetans. Protein-protein interaction and pathway analyses of candidate DMGs related to iron uptake and transport showed that epigenetic changes in 10 candidate genes (ACO1, CYBRD1, FLVCR1, HFE, HMOX2, IREB2, NEDD8, SLC11A2, SLC40A1 and TFRC) are likely to relate to iron overload. This work reveals, for the first time, changes of DNAm in Tibetan people with iron overload, which suggest that DNAm is a mechanism underlying differences in iron content between individuals in the high-altitude Tibetan population. Our findings should contribute to the study of iron metabolism and the overall health status of Tibetans.

Iron overload, oxidative stress and vascular dysfunction: Evidences from clinical studies and animal models

Although iron is a metal involved in many in vital processes due to its redox capacity, body iron overloads lead to tissue damage, including the cardiovascular system. While cardiomyopathy was the focus since the 1960s, the impact on the vasculature was comparatively neglected for about 40 years, when clinical studies correlating iron overload, oxidative stress, endothelial dysfunction, arterial stiffness and atherosclerosis reinforced an "iron hypothesis". Due to controversial results from some epidemiological studies investigating atherosclerotic events and iron levels, well-controlled trials and animal studies provided essential data about the influence of iron, per se, on the vasculature. As a result, the pathophysiology of vascular dysfunction in iron overload have been revisited. This review summarizes the knowledge obtained from epidemiological studies, animal models and "in vitro" cellular systems in recent decades, highlighting a more harmful than innocent role of iron excess for the vascular homeostasis, which supports our proposal to hereafter denominate "iron overload vasculopathy". Additionally, evidence-based therapeutic targets are pointed out to be tested in pre-clinical research that may be useful in cardiovascular protection for patients with iron overload syndromes.

Roux-en-Y Gastric Bypass as a Treatment for Hepatic Iron Overload: An Exploratory Study

BACKGROUND

Excess bodily iron content is commonly associated with obesity and metabolic associated medical conditions and is thought to lead to cardiovascular disease. The effect of Roux-en-Y gastric bypass (RYGB) on hepatic iron overload remains to be determined.

OBJECTIVE

To assess the evolution of histologically proven hepatic iron overload after RYGB.

METHODS

This is an exploratory historical cohort study in which 42 individuals who underwent RYGB, and then a second surgical procedure had paired liver biopsies collected. Hepatic iron overload and NAFLD features were assessed through histopathological examination. Biochemical iron metabolism parameters were also assessed.

RESULTS

The mean age at RYGB was 47 ± 10.2 years and 92.9% were female. The average time elapsed between RYGB and the second surgical procedure was 20.6 ± 15.4 months. The mean percentage of total weight loss between the two procedures was 26.7 ± 9.4%. Significant reductions in ferritin (220.8 ± 202.9 vs. 101.6 ± 116.7 ng/mL; p = 0.006), hemoglobin (13.7 ± 1.8 vs. 12.1 ± 2.6 g/dL; p = 0.01), and red blood cell count (4.7 ± 0.7 vs. 4.3 ± 0.5 10⁶/mm³; p = 0.003) were observed, as well as reductions in the frequencies of steatosis (83.3% vs. 23.8%; p < 0.0001) and steatohepatitis (52.4% vs. 11.9%; p < 0.0001). The frequency of hepatic iron overload significantly decreased from 16.7 to 2.4% (p = 0.03).

CONCLUSION

RYGB led to a significant decrease in hepatic iron overload, emerging as a possible therapeutical tool for this condition in individuals with obesity and dysmetabolic iron overload syndrome.

A simple clinical score to promote and enhance ferroportin disease screening

BACKGROUND & AIMS

Ferroportin disease is a rare genetic iron overload disorder which may be underdiagnosed, with recent data suggesting it occurs at a higher prevalence than suspected. Costs and the lack of defined criteria to prompt genetic testing preclude large-scale molecular screening. Hence, we aimed to develop a readily available scoring system to promote and enhance ferroportin disease screening.

METHODS

Our derivation cohort included probands tested for ferroportin disease from 2008 to 2016 in our rare disease network. Data were prospectively recorded. Univariate and multivariate logistic regression were used to determine significant criteria, and odds ratios were used to build a weighted score. A cut-off value was defined using a ROC curve with a predefined aim of 90% sensitivity. An independent cohort was used for cross validation.

RESULTS

Our derivation cohort included 1,306 patients. Mean age was 55±14 years, ferritin 1,351±1,357 μg/L, and liver iron concentration (LIC) 166±77 μmol/g. Pathogenic variants (n = 32) were identified in 71 patients. In multivariate analysis: female sex, younger age, higher ferritin, higher LIC and the absence of hypertension or diabetes were significantly associated with the diagnosis of ferroportin disease (AUROC in whole derivation cohort 0.83 [0.78-0.88]). The weighted score was based on sex, age, the presence of hypertension or diabetes, ferritin level and LIC. An AUROC of 0.83 (0.77-0.88) was obtained in the derivation cohort without missing values. Using 9.5 as a cut-off, sensitivity was 93.6 (91.7-98.3) %, specificity 49.5 (45.5-53.6) %, positive likelihood ratio 1.8 (1.6-2.0) and negative likelihood ratio 0.17 (0.04-0.37).

CONCLUSION

We describe a readily available score with simple criteria and good diagnostic performance that could be used to screen patients for ferroportin disease in routine clinical practice.

LAY SUMMARY

Increased iron burden associated with metabolic syndrome is a very common condition. Ferroportin disease is a dominant genetic iron overload disorder whose prevalence is higher than initially thought. They can be difficult to distinguish from each other, but the limited availability of genetic testing and the lack of definitive guidelines prevent adequate screening. We herein describe a simple and definitive clinical score to help clinicians decide whether to perform genetic testing.

Increased hepcidin levels and non-alcoholic fatty liver disease in obese prepubertal children: a further piece to the complex puzzle of metabolic derangements

INTRODUCTION

Several studies on obese youths and adults have reported increased hepcidin levels, which seems to be related to metabolic and iron metabolism alterations. The complete mechanisms involved in hepcidin increase remain to be elucidated, and particularly its role in the development of other known complications such as Nonalcoholic Fatty Liver Disease (NAFLD). NAFLD in prepubertal children might be of special interest in understanding the underlying mechanisms.

METHODS

Anthropometric measurements, liver ultrasonography, lipid profile, liver function, oxidative stress, inflammatory state, and iron metabolism were studied in 42 obese prepubertal children and 33 healthy controls. We, therefore, evaluated the presence of possible correlations between Hepcidin and the other metabolic variables, and the possible association between NAFLD and iron metabolism.

RESULTS

Hepcidin levels were significantly increased in the obese prepubertal children (p=0.001) with significant differences between obese children with and without NAFLD (p=0.01). Blood iron was lower in obese children (p=0.009). In the obese group, a negative correlation between hepcidin and both blood iron levels (p=0.01) and LagPHASE (p=0.02) was found. In addition, a positive association between hepcidin and NAFLD (p=0.03) was detected.

CONCLUSIONS

We suggest that an increase in hepcidin levels may represent an early step in iron metabolism derangements and metabolic alterations, including NAFLD, in prepubertal obese children.

Non-invasive diagnosis and follow-up of hyperferritinaemia

Increased serum ferritin is a very frequent cause of referral for which thorough evaluation is required to avoid unnecessary exploration and inaccurate diagnosis. Clinicians must thus know factors and tools that are relevant in this setting. Several biochemical and radiological tools drastically improved the diagnosis work-up of increased serum ferritin. Because serum ferritin value can be altered by many cofounding factors, scrutiny in the initial clinical evaluation is crucial. Alcohol consumption, and the metabolic syndrome are the most frequent causes of secondary increased ferritin. Serum transferrin saturation level is a pivotal test, and if increased prompt testing for HFE C282Y patients in Caucasian population. In most cases further tests are require to establish whether increased ferritin is associated or not to iron overload. Magnetic resonance imaging is the reference method allowing to accurately establish liver iron content which indirectly reflect body iron load. Second line genetic testing for rare forms of iron overload or increased serum ferritin are available in reference center and should be discussed if diagnosis is equivocal or remain uncertain after careful evaluation. Definite genetic diagnosis is worthwhile as it allows family screening and refining long term management of the patient. Liver biopsy remains seldom useful to assess liver fibrosis, mostly in patients with severe iron overload.

INFERR-Iron infusion in haemodialysis study: INtravenous iron polymaltose for First Nations Australian patients with high FERRitin levels on haemodialysis-a protocol for a prospective open-label blinded endpoint randomised controlled trial

BACKGROUND

The effectiveness of erythropoiesis-stimulating agents, which are the main stay of managing anaemia of chronic kidney disease (CKD), is largely dependent on adequate body iron stores. The iron stores are determined by the levels of serum ferritin concentration and transferrin saturation. These two surrogate markers of iron stores are used to guide iron replacement therapy. Most Aboriginal and/or Torres Islander Australians of the Northern Territory (herein respectfully referred to as First Nations Australians) with end-stage kidney disease have ferritin levels higher than current guideline recommendations for iron therapy. There is no clear evidence to guide safe and effective treatment with iron in these patients. We aim to assess the impact of intravenous iron treatment on all-cause death and hospitalisation with a principal diagnosis of all-cause infection in First Nations patients on haemodialysis with anaemia, high ferritin levels and low transferrin saturation METHODS: In a prospective open-label blinded endpoint randomised controlled trial, a total of 576 participants on maintenance haemodialysis with high ferritin (> 700 μg/L and ≤ 2000 μg/L) and low transferrin saturation (< 40%) from all the 7 renal units across the Northern Territory of Australia will be randomised 1:1 to receive intravenous iron polymaltose 400 mg once monthly (200 mg during 2 consecutive haemodialysis sessions) (Arm A) or no IV iron treatment (standard treatment) (Arm B). Rescue therapy will be administered when the ferritin levels fall below 700 μg/L or when clinically indicated. The primary outcome will be the differences between the two study arms in the risk of hospitalisation with all-cause infection or death. An economic analysis and several secondary and tertiary outcomes analyses will also be performed.

DISCUSSION

The INFERR clinical trial will address significant uncertainty on the safety and efficacy of iron therapy in First Nations Australians with CKD with hyperferritinaemia and evidence of iron deficiency. This will hopefully lead to the development of evidence-based guidelines. It will also provide the opportunity to explore the causes of hyperferritinaemia in First Nations Australians from the Northern Territory.

TRIAL REGISTRATION

This trial is registered with The Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000705987 . Registered 29 June 2020.

Albuminuria Is Associated with Hepatic Iron Load in Patients with Non-Alcoholic Fatty Liver Disease and Metabolic Syndrome

Background: Increased albuminuria is associated with increased serum ferritin, insulin resistance, and non-alcoholic fatty liver disease (NAFLD). Liver iron accumulation is also related to hyperferritinemia, insulin resistance, and NAFLD; however, there is no evidence on its relationship with albuminuria. Aims: To assess the relationship between hepatic iron load and urine albumin-to-creatinine ratio (UACR) in patients with metabolic syndrome (MetS) and NAFLD. Methods: In total, 75 MetS and NAFLD patients (aged 40–60 years, BMI 27–40 kg/m²) were selected from a cohort according to available data on hepatic iron load (HepFe) by magnetic resonance imaging (MRI). Subjects underwent anthropometric measurements, biochemistry testing, and liver MRI. Increased albuminuria was defined by UACR. Results: UACR correlated with NAFLD, HepFe, triglycerides, serum ferritin, fasting insulin, insulin resistance (calculated using the homeostatic model assessment for insulin resistance—HOMA-IR- formula), and platelets (p < 0.05). Multiple regression analysis adjusted for gender, age, eGFR, HbA1c, T2DM, and stages of NAFLD, found that HepFe (p = 0.02), serum ferritin (p = 0.04), fasting insulin (p = 0.049), and platelets (p = 0.009) were associated with UACR (R² = 0.370; p = 0.007). UACR, liver fat accumulation, serum ferritin, and HOMA-IR increased across stages of HepFe (p < 0.05). Patients with severe NAFLD presented higher HepFe, fasting insulin, HOMA-IR, and systolic blood pressure as compared to patients in NAFLD stage 1 (p < 0.05). Conclusion: Hepatic iron load, serum ferritin, fasting insulin, and platelets were independently associated with albuminuria. In the context of MetS, increased stages of NAFLD presented higher levels of HepFe. Higher levels of HepFe were accompanied by increased serum ferritin, insulin resistance, and UACR. The association between iron accumulation, MetS, and NAFLD may represent a risk factor for the development of increased albuminuria.

Iron Reshapes the Gut Microbiome and Host Metabolism

Compelling studies have established that the gut microbiome is a modifier of metabolic health. Changes in the composition of the gut microbiome are influenced by genetics and the environment, including diet. Iron is a potential node of crosstalk between the host-microbe relationship and metabolic disease. Although iron is well characterized as a frequent traveling companion of metabolic disease, the role of iron is underappreciated because the mechanisms of iron's influence on host metabolism are poorly characterized. Both iron deficiency and excessive amounts leading to iron overload can have detrimental effects on cardiometabolic health. Optimal iron homeostasis is critical for regulation of host immunity and metabolism in addition to regulation of commensal and pathogenic enteric bacteria. In this article we review evidence to support the notion that altering composition of the gut microbiome may be an important route via which iron impacts cardiometabolic health. We discuss reshaping of the microbiome by iron, the physiological significance and the potential for therapeutic interventions.

Iron aggravates hepatic insulin resistance in the absence of inflammation in a novel db/db mouse model with iron overload

OBJECTIVE

The molecular pathogenesis of late complications associated with type 2 diabetes mellitus (T2DM) is not yet fully understood. While high glucose levels indicated by increased HbA1c only poorly explain disease progression and late complications, a pro-inflammatory status, oxidative stress, and reactive metabolites generated by metabolic processes were postulated to be involved. Individuals with metabolic syndrome (MetS) frequently progress to T2DM, whereby 70% of patients with T2DM show non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of MetS, and insulin resistance (IR). Epidemiological studies have shown that T2DM and steatosis are associated with alterations in iron metabolism and hepatic iron accumulation. Excess free iron triggers oxidative stress and a switch towards a macrophage pro-inflammatory status. However, so far it remains unclear whether hepatic iron accumulation plays a causative role in the generation of IR and T2DM or whether it is merely a manifestation of altered hepatic metabolism. To address this open question, we generated and characterized a mouse model of T2DM with IR, steatosis, and iron overload.

METHODS

Lepr^db/db mice hallmarked by T2DM, IR and steatosis were crossed with Fpn^wt/C326S mice with systemic iron overload to generate Lepr^db/db/Fpn^wt/C326S mice. The resulting progeny was characterized for major diabetic and iron-related parameters.

RESULTS

We demonstrated that features associated with T2DM in Lepr^db/db mice, such as obesity, steatosis, or IR, reduce the degree of tissue iron overload in Fpn^wt/C326S mice, suggesting an 'iron resistance' phenotype. Conversely, we observed increased serum iron levels that strongly exceeded those in the iron-overloaded Fpn^wt/C326S mice. Increased hepatic iron levels induced oxidative stress and lipid peroxidation and aggravated IR, as indicated by diminished IRS1 phosphorylation and AKT activation. Additionally, in the liver, we observed gene response patterns indicative of de novo lipogenesis and increased gluconeogenesis as well as elevated free glucose levels. Finally, we showed that iron overload in Lepr^db/db/Fpn^wt/C326S mice enhances microvascular complications observed in retinopathy, suggesting that iron accumulation can enhance diabetic late complications associated with the liver and the eye.

CONCLUSION

Taken together, our data show that iron causes the worsening of symptoms associated with the MetS and T2DM. These findings imply that iron depletion strategies together with anti-diabetic drugs may ameliorate IR and diabetic late complications.

Revisiting hemochromatosis: genetic vs. phenotypic manifestations

Iron overload disorders represent an important class of human diseases. Of the primary iron overload conditions, by far the most common and best studied is HFE-related hemochromatosis, which results from homozygosity for a mutation leading to the C282Y substitution in the HFE protein. This disease is characterized by reduced expression of the iron-regulatory hormone hepcidin, leading to increased dietary iron absorption and iron deposition in multiple tissues including the liver, pancreas, joints, heart and pituitary. The phenotype of HFE-related hemochromatosis is quite variable, with some individuals showing little or no evidence of increased body iron, yet others showing severe iron loading, tissue damage and clinical sequelae. The majority of genetically predisposed individuals show at least some evidence of iron loading (increased transferrin saturation and serum ferritin), but a minority show clinical symptoms and severe consequences are rare. Thus, the disorder has a high biochemical penetrance, but a low clinical prevalence. Nevertheless, it is such a common condition in Caucasian populations (1:100–200) that it remains an important clinical entity. The phenotypic variability can largely be explained by a range of environmental, genetic and physiological factors. Men are far more likely to manifest significant disease than women, with the latter losing iron through menstrual blood loss and childbirth. Other forms of blood loss, immune system influences, the amount of bioavailable iron in the diet and lifestyle factors such as high alcohol intake can also contribute to iron loading and disease expression. Polymorphisms in a range of genes have been linked to variations in body iron levels, both in the general population and in hemochromatosis. Some of the genes identified play well known roles in iron homeostasis, yet others are novel. Other factors, including both co-morbidities and genetic polymorphisms, do not affect iron levels per se, but determine the propensity for tissue pathology.

Narrative Review of Hyperferritinemia, Iron Deficiency, and the Challenges of Managing Anemia in Aboriginal and Torres Strait Islander Australians With CKD

Aboriginal and Torres Strait Islander Australians (Indigenous Australians) suffer some of the highest rates of chronic kidney disease (CKD) in the world. Among Indigenous Australians in remote areas of the Northern Territory, prevalence rates for renal replacement therapy (RRT) are up to 30 times higher than national prevalence. Anemia among patients with CKD is a common complication. Iron deficiency is one of the major causes. Iron deficiency is also one of the key causes of poor response to the mainstay of anemia therapy with erythropoiesis-stimulating agents (ESAs). Therefore, the effective management of anemia in people with CKD is largely dependent on effective identification and correction of iron deficiency. The current identification of iron deficiency in routine clinical practice is dependent on 2 surrogate markers of iron status: serum ferritin concentration and transferrin saturation (TSAT). However, questions exist regarding the use of serum ferritin concentration in people with CKD because it is an acute-phase reactant that can be raised in the context of acute and chronic inflammation. Serum ferritin concentration among Indigenous Australians receiving RRT is often markedly elevated and falls outside reference ranges within most national and international guidelines for iron therapy for people with CKD. This review explores published data on the challenges of managing anemia in Indigenous people with CKD and the need for future research on the efficacy and safety of treatment of anemia of CKD in patients with high ferritin and evidence iron deficiency.

Regulatory Connections between Iron and Glucose Metabolism

Iron is essential for energy metabolism, and states of iron deficiency or excess are detrimental for organisms and cells. Therefore, iron and carbohydrate metabolism are tightly regulated. Serum iron and glucose levels are subjected to hormonal regulation by hepcidin and insulin, respectively. Hepcidin is a liver-derived peptide hormone that inactivates the iron exporter ferroportin in target cells, thereby limiting iron efflux to the bloodstream. Insulin is a protein hormone secreted from pancreatic β-cells that stimulates glucose uptake and metabolism via insulin receptor signaling. There is increasing evidence that systemic, but also cellular iron and glucose metabolic pathways are interconnected. This review article presents relevant data derived primarily from mouse models and biochemical studies. In addition, it discusses iron and glucose metabolism in the context of human disease.

Role of microRNA-122 in microcystin-leucine arginine-induced dysregulation of hepatic iron homeostasis in mice

Microcystin-leucine arginine (MC-LR) is a cyclic heptapeptide hepatotoxin produced by cyanobacteria. MicroRNA-122 (miR-122) is specifically expressed in the liver. This study focuses on the role of miR-122 in MC-LR-induced dysregulation of hepatic iron homeostasis in C57BL/6 mice. The thirty mice were randomly divided into five groups (Control, 12.5 μg/kg·BW MC-LR, 25 μg/kg·BW MC-LR, Negative control agomir and 25 μg/kg·BW MC-LR + miR-122 agomir). The results show that MC-LR decreases the expressions of miR-122, Hamp, and its related regulators, while increasing the content of hepatic iron and the expressions of FPN1 and Tmprss6. Furthermore, miR-122 agomir pretreatment improves MC-LR induced dysregulation of hepatic iron homeostasis by arousing the related regulators and reducing the expression of Tmprss6. These results suggest that miR-122 agomir can prevent the accumulation of hepatic iron induced by MC-LR, which may be related to the regulation of hepcidin by BMP/SMAD and IL-6/STAT signaling pathways.

Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death?

Ferroptosis has emerged as a new type of cell death in different pathological conditions, including neurological and kidney diseases and, especially, in different types of cancer. The hallmark of this regulated cell death is the presence of iron-driven lipid peroxidation; the activation of key genes related to this process such as glutathione peroxidase-4 (gpx4), acyl-CoA synthetase long-chain family member-4 (acsl4), carbonyl reductase [NADPH] 3 (cbr3), and prostaglandin peroxidase synthase-2 (ptgs2); and morphological changes including shrunken and electron-dense mitochondria. Iron overload in the liver has long been recognized as both a major trigger of liver damage in different diseases, and it is also associated with liver fibrosis. New evidence suggests that ferroptosis might be a novel type of non-apoptotic cell death in several liver diseases including non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), drug-induced liver injury (DILI), viral hepatitis, and hemochromatosis. The interaction between iron-related lipid peroxidation, cellular stress signals, and antioxidant systems plays a pivotal role in the development of this novel type of cell death. In addition, integrated responses from lipidic mediators together with free iron from iron-containing enzymes are essential to understanding this process. The presence of ferroptosis and the exact mechanisms leading to this non-apoptotic type of cell death in the liver remain scarcely elucidated. Recognizing ferroptosis as a novel type of cell death in the liver could lead to the understanding of the complex interaction between different types of cell death, their role in progression of liver fibrosis, the development of new biomarkers, as well as the use of modulators of ferroptosis, allowing improved theranostic approaches in the clinic.

The Other Obesity Epidemic-Of Drugs and Bugs

Chronic psychiatric patients with schizophrenia and related disorders are frequently treatment-resistant and may require higher doses of psychotropic drugs to remain stable. Prolonged exposure to these agents increases the risk of weight gain and cardiometabolic disorders, leading to poorer outcomes and higher medical cost. It is well-established that obesity has reached epidemic proportions throughout the world, however it is less known that its rates are two to three times higher in mentally ill patients compared to the general population. Psychotropic drugs have emerged as a major cause of weight gain, pointing to an urgent need for novel interventions to attenuate this unintended consequence. Recently, the gut microbial community has been linked to psychotropic drugs-induced obesity as these agents were found to possess antimicrobial properties and trigger intestinal dysbiosis, depleting Bacteroidetes phylum. Since germ-free animals exposed to psychotropics have not demonstrated weight gain, altered commensal flora composition is believed to be necessary and sufficient to induce dysmetabolism. Conversely, not only do psychotropics disrupt the composition of gut microbiota but the later alter the metabolism of the former. Here we review the role of gut bacterial community in psychotropic drugs metabolism and dysbiosis. We discuss potential biomarkers reflecting the status of Bacteroidetes phylum and take a closer look at nutritional interventions, fecal microbiota transplantation, and transcranial magnetic stimulation, strategies that may lower obesity rates in chronic psychiatric patients.

Serum Ferritin Independently Predicts the Incidence of Chronic Kidney Disease in Patients with Type 2 Diabetes Mellitus

AIM

This study aimed to determine whether serum ferritin (SF) is an independent risk factor of the incidence of chronic kidney disease (CKD) and rapid renal function decline (RFD) in male Tibetan patients with type 2 diabetes mellitus (T2DM).

METHODS

We performed a retrospective cohort study that included 191 male Tibetan patients with T2DM without CKD. Patients were divided into three groups according to the level of SF. The following outcomes were measured: cumulative incidence of chronic kidney disease [i.e. estimated glomerular filtration rate (eGFR) <60 mL/min per 1.73 m² and/or urinary albumin/creatine ratio (ACR) ≥30 mg/g] and RFD (i.e. decrease in eGFR of ≥25% from baseline or a decline rate of ≥3 mL/min per 1.73 m² annually).

RESULTS

In total, over a median follow-up period of 23 months, 30 (15.7%) and 89 patients (46.6%) developed CKD and RFD. In multivariable Cox models, a 100 ng/mL increment in SF was associated with a 1.12-fold (95% CI: 1.02-1.24) higher adjusted risk for incidence of CKD. The adjusted-HR of CKD was 1.31 (95% CI: 0.38-4.53) and 2.92 (95% CI: 0.87-9.77) for those in tertile 2 and tertile 3, respectively, compared with the patients in tertile 1. However, SF was not significantly associated with RFD (adjusted-HR: 1.06, 95% CI: 0.99-1.14).

CONCLUSION

Serum ferritin independently predicts the incidence of CKD in male Tibetan patients with T2DM. High levels of serum ferritin may play a role in the pathogenesis leading to the development of CKD in T2DM.

Association of Metabolic Syndrome and Hyperferritinemia in Patients at Cardiovascular Risk

AIM

To evaluate the association between parameters of hyperferritinemia (HF) and metabolic syndrome (MS) in patients at cardiovascular risk.

PATIENTS AND METHODS

This is a cross-sectional analytical observational study that included 269 patients who attended a cardiology unit. Biochemical and anthropometric parameters were evaluated to identify the presence of HF and MS. The presence of MS was evaluated according to NCEP ATP III. Biochemical parameters (glycemia, triglycerides, HDL-c) were assessed according to the manufacturer's protocols. Anthropometric measurements and blood pressure measurements were made by a trained professional. The chi-square (X ²) test, odds ratio, normality distribution (verified by the Kolmogorov-Smirnov test), and Levene's test were used to analyze the variables. To evaluate the effect of MS, HF, and the interaction between MS and HF, two-way analysis of variance (ANOVA) was performed based on the homogeneity of the variances, followed by Bonferroni's post hoc comparisons. Spearman correlation analysis was performed to evaluate the relationship between quantitative variables. A multiple linear regression model was used to analyze the effect of covariables. A logistic regression model was built to analyze the variables that contribute significantly to predict the outcome (HF) using the backward method.

RESULTS

Our results showed that 57% of men and 49.5% of women presented with MS; 44% of men and 11% of women presented with HF. The presence of MS and hypertriglyceridemia increase the probability of having HF by up to 2.1 and 1.88 times, respectively, while for male sex it is increased by 6.2 times. Patients with HF have higher values of C-reactive protein, ferritin, and transferrin saturation, regardless of the presence of MS. The linear regression analysis model indicated that the variables considered in this study explain less than 30% of the variation in ferritin and that the presence of MS in men is responsible for 22% of the variation in the probability of the occurrence of HF.

CONCLUSION

Our results show that hyperferritinemia is closely associated with the components of MS (positive correlation with glycemia, triglycerides levels, blood pressure, and waist circumference, and negative correlation with HDL-c values) in the studied population.

Dysregulated Iron Metabolism-Associated Dietary Pattern Predicts an Altered Body Composition and Metabolic Syndrome

Diet plays an important role in the development of obesity and may contribute to dysregulated iron metabolism (DIM). A cross-sectional survey of 208 adults was conducted in Taipei Medical University Hospital (Taipei, Taiwan). A reduced-rank regression from 31 food groups was used for a dietary pattern analysis. DIM was defined as at least four of the following criteria: serum hepcidin (men >200 ng/mL and women >140 ng/mL), hyperferritinemia (serum ferritin of >300 ng/mL in men and >200 ng/mL in women), central obesity, non-alcoholic fatty liver disease, and two or more abnormal metabolic profiles. Compared to non-DIM patients, DIM patients were associated with an altered body composition and had a 4.52-fold (95% confidence interval (CI): (1.95–10.49); p < 0.001) greater risk of metabolic syndrome (MetS) after adjusting for covariates. A DIM-associated dietary pattern (high intake of deep-fried food, processed meats, chicken, pork, eating out, coffee, and animal fat/skin but low intake of steamed/boiled/raw foods and dairy products) independently predicted central obesity (odds ratio (OR): 1.57; 95% CI: 1.05–2.34; p < 0.05) and MetS (OR: 1.89; 95% CI: 1.07–3.35; p < 0.05). Individuals with the highest DIM pattern scores (tertile 3) had a higher visceral fat mass (%) (β = 0.232; 95% CI: 0.011–0.453; p < 0.05) but lower skeletal muscle mass (%) (β = −1.208; 95% CI: −2.177–−0.239; p < 0.05) compared to those with the lowest DIM pattern scores (tertile 1). In conclusion, a high score for the identified DIM-associated dietary pattern was associated with an unhealthier body composition and a higher risk of MetS.

Genetic studies of abdominal MRI data identify genes regulating hepcidin as major determinants of liver iron concentration

BACKGROUND & AIMS

Excess liver iron content is common and is linked to the risk of hepatic and extrahepatic diseases. We aimed to identify genetic variants influencing liver iron content and use genetics to understand its link to other traits and diseases.

METHODS

First, we performed a genome-wide association study (GWAS) in 8,289 individuals from UK Biobank, whose liver iron level had been quantified by magnetic resonance imaging, before validating our findings in an independent cohort (n = 1,513 from IMI DIRECT). Second, we used Mendelian randomisation to test the causal effects of 25 predominantly metabolic traits on liver iron content. Third, we tested phenome-wide associations between liver iron variants and 770 traits and disease outcomes.

RESULTS

We identified 3 independent genetic variants (rs1800562 [C282Y] and rs1799945 [H63D] in HFE and rs855791 [V736A] in TMPRSS6) associated with liver iron content that reached the GWAS significance threshold (p <5 × 10-8). The 2 HFE variants account for ∼85% of all cases of hereditary haemochromatosis. Mendelian randomisation analysis provided evidence that higher central obesity plays a causal role in increased liver iron content. Phenome-wide association analysis demonstrated shared aetiopathogenic mechanisms for elevated liver iron, high blood pressure, cirrhosis, malignancies, neuropsychiatric and rheumatological conditions, while also highlighting inverse associations with anaemias, lipidaemias and ischaemic heart disease.

CONCLUSION

Our study provides genetic evidence that mechanisms underlying higher liver iron content are likely systemic rather than organ specific, that higher central obesity is causally associated with higher liver iron, and that liver iron shares common aetiology with multiple metabolic and non-metabolic diseases.

LAY SUMMARY

Excess liver iron content is common and is associated with liver diseases and metabolic diseases including diabetes, high blood pressure, and heart disease. We identified 3 genetic variants that are linked to an increased risk of developing higher liver iron content. We show that the same genetic variants are linked to higher risk of many diseases, but they may also be associated with some health advantages. Finally, we use genetic variants associated with waist-to-hip ratio as a tool to show that central obesity is causally associated with increased liver iron content.

Serum iron, Magnesium, Copper, and Manganese Levels in Alcoholism: A Systematic Review

The aim of this paper was to review recent literature (from 2000 onwards) and summarize the newest findings on fluctuations in the concentration of some essential macro- and microelements in those patients with a history of chronic alcohol abuse. The focus was mainly on four elements which the authors found of particular interest: Iron, magnesium, copper, and manganese. After independently reviewing over 50 articles, the results were consistent with regard to iron and magnesium. On the other hand, data were limited, and in some cases contradictory, as far as copper and manganese were concerned. Iron overload and magnesium deficiency are two common results of an excessive and prolonged consumption of alcohol. An increase in the levels of iron can be seen both in the serum and within the cells, hepatocytes in particular. This is due to a number of factors: Increased ferritin levels, lower hepcidin levels, as well as some fluctuations in the concentration of the TfR receptor for transferrin, among others. Hypomagnesemia is universally observed among those suffering from alcoholism. Again, the causes for this are numerous and include malnutrition, drug abuse, respiratory alkalosis, and gastrointestinal problems, apart from the direct influence of excessive alcohol intake. Unfortunately, studies regarding the levels of both copper and manganese in the case of (alcoholic) liver disease are scarce and often contradictory. Still, the authors have attempted to summarize and give a thorough insight into the literature available, bearing in mind the difficulties involved in the studies. Frequent comorbidities and mutual relationships between the elements in question are just some of the complications in the study of this topic.

Review article: iron disturbances in chronic liver diseases other than haemochromatosis - pathogenic, prognostic, and therapeutic implications

BACKGROUND

Disturbances in iron regulation have been described in diverse chronic liver diseases other than hereditary haemochromatosis, and iron toxicity may worsen liver injury and outcome.

AIMS

To describe manifestations and consequences of iron dysregulation in chronic liver diseases apart from hereditary haemochromatosis and to encourage investigations that clarify pathogenic mechanisms, define risk thresholds for iron toxicity, and direct management METHODS: English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed.

RESULTS

Hyperferritinemia is present in 4%-65% of patients with non-alcoholic fatty liver disease, autoimmune hepatitis, chronic viral hepatitis, or alcoholic liver disease, and hepatic iron content is increased in 11%-52%. Heterozygosity for the C282Y mutation is present in 17%-48%, but this has not uniformly distinguished patients with adverse outcomes. An inappropriately low serum hepcidin level has characterised most chronic liver diseases with the exception of non-alcoholic fatty liver disease, and the finding has been associated mainly with suppression of transcriptional activity of the hepcidin gene. Iron overload has been associated with oxidative stress, advanced fibrosis and decreased survival, and promising therapies beyond phlebotomy and oral iron chelation have included hepcidin agonists.

CONCLUSIONS

Iron dysregulation is common in chronic liver diseases other than hereditary haemochromatosis, and has been associated with liver toxicity and poor prognosis. Further evaluation of iron overload as a co-morbid factor should identify the key pathogenic disturbances, establish the risk threshold for iron toxicity, and promote molecular interventions.

Measurement of liver iron by magnetic resonance imaging in the UK Biobank population

The burden of liver disease continues to increase in the UK, with liver cirrhosis reported to be the third most common cause of premature death. Iron overload, a condition that impacts liver health, was traditionally associated with genetic disorders such as hereditary haemochromatosis, however, it is now increasingly associated with obesity, type-2 diabetes and non-alcoholic fatty liver disease. The aim of this study was to assess the prevalence of elevated levels of liver iron within the UK Biobank imaging study in a cohort of 9108 individuals. Magnetic resonance imaging (MRI) was undertaken at the UK Biobank imaging centre, acquiring a multi-echo spoiled gradient-echo single-breath-hold MRI sequence from the liver. All images were analysed for liver iron and fat (expressed as proton density fat fraction or PDFF) content using LiverMultiScan. Liver iron was measured in 97.3% of the cohort. The mean liver iron content was 1.32 ± 0.32 mg/g while the median was 1.25 mg/g (min: 0.85 max: 6.44 mg/g). Overall 4.82% of the population were defined as having elevated liver iron, above commonly accepted 1.8 mg/g threshold based on biochemical iron measurements in liver specimens obtained by biopsy. Further analysis using univariate models showed elevated liver iron to be related to male sex (p<10⁻¹⁶, r² = 0.008), increasing age (p<10⁻¹⁶, r² = 0.013), and red meat intake (p<10⁻¹⁶, r² = 0.008). Elevated liver fat (>5.6% PDFF) was associated with a slight increase in prevalence of elevated liver iron (4.4% vs 6.3%, p = 0.0007). This study shows that population studies including measurement of liver iron concentration are feasible, which may in future be used to better inform patient stratification and treatment.

Haemochromatosis

Haemochromatosis is defined as systemic iron overload of genetic origin, caused by a reduction in the concentration of the iron regulatory hormone hepcidin, or a reduction in hepcidin-ferroportin binding. Hepcidin regulates the activity of ferroportin, which is the only identified cellular iron exporter. The most common form of haemochromatosis is due to homozygous mutations (specifically, the C282Y mutation) in HFE, which encodes hereditary haemochromatosis protein. Non-HFE forms of haemochromatosis due to mutations in HAMP, HJV or TFR2 are much rarer. Mutations in SLC40A1 (also known as FPN1; encoding ferroportin) that prevent hepcidin-ferroportin binding also cause haemochromatosis. Cellular iron excess in HFE and non-HFE forms of haemochromatosis is caused by increased concentrations of plasma iron, which can lead to the accumulation of iron in parenchymal cells, particularly hepatocytes, pancreatic cells and cardiomyocytes. Diagnosis is noninvasive and includes clinical examination, assessment of plasma iron parameters, imaging and genetic testing. The mainstay therapy is phlebotomy, although iron chelation can be used in some patients. Hepcidin supplementation might be an innovative future approach.