Haemochromatosis

Reference diagnosis and treatment process of juvenile hemochromatosis patients

The compelling case report by Xie et al, published in a renowned medical journal, is an excellent example of meticulous clinical evaluation, comprehensive laboratory testing, advanced imaging, and genetic analysis. The authors identified novel compound heterozygous mutations in the hemojuvelin gene of a patient diagnosed with juvenile hemochromatosis. They suggested that long-term, strategic phlebotomy might offer a novel therapeutic strategy for severe juvenile hemochromatosis, challenging the traditional treatment paradigms.

Incidence of liver complications with hemochromatosis-associated HFE p.C282Y homozygosity: The role of central adiposity

BACKGROUND AND AIMS

The HFE p.C282Y+/+ (homozygous) genotype and central adiposity both increase liver disease and diabetes risks, but the combined effects are unclear. We estimated waist-to-hip ratio (WHR) associations with incident clinical outcomes in routine care in p.C282Y+/+ participants in the UK Biobank community cohort.

APPROACH AND RESULTS

Baseline WHR data available in 1297 male and 1602 female p.C282Y+/+ with 13.3-year mean follow-up for diagnoses. Spline regressions and Cox proportional hazard models were adjusted for age and genetic principal components. Cumulative incidence was from age 40 to 80 years. In p.C282Y+/+ males, there were positive linear WHR relationships for hospital inpatient-diagnosed liver fibrosis/cirrhosis ( p = 2.4 × 10 -5 ), liver cancer ( p = 0.007), non-alcoholic fatty liver disease ( p = 7.7 × 10 -11 ), and type 2 diabetes ( p = 5.1 × 10 -16 ). The hazard ratio for high WHR in p.C282Y+/+ males (≥0.96; 33.9%) was 4.13 for liver fibrosis/cirrhosis (95% CI: 2.04-8.39, p = 8.4 × 10 -5 vs. normal WHR); cumulative age 80 incidence 15.0% (95% CI: 9.8%-22.6%) versus 3.9% (95% CI: 1.9%-7.6%); for liver cancer, cumulative incidence was 9.2% (95% CI: 5.7%-14.6%) versus 3.6% (95% CI: 1.9%-6.6%). Hemochromatosis was diagnosed in 23 (96%) of the 24 high WHR p.C282Y+/+ males with incident fibrosis/cirrhosis. High WHR (≥0.85; 30.0%) p.C282Y+/+ females had raised hazards for liver fibrosis/cirrhosis (hazard ratio = 9.17, 95% CI: 2.51-33.50, p = 3.8 × 10 -7 ) and Non-alcoholic fatty liver disease (hazard ratio = 5.17, 95% CI: 2.48-10.78, p = 1.2 × 10 -5 ). Fibrosis/cirrhosis associations were similar in the subset with additional primary care diagnoses.

CONCLUSIONS

In p.C282Y+/+ males and females, increasing WHR is associated with substantially higher risks of liver complications. Interventions to reduce central adiposity to improve these outcomes should be tested.

Nrf2 activators for the treatment of rare iron overload diseases: From bench to bedside

Iron overload and related oxidative damage are seen in many rare diseases, due to mutation of iron homeostasis-related genes. As a core regulator on cellular antioxidant reaction, Nrf2 can also decrease systemic and cellular iron levels by regulating iron-related genes and pathways, making Nrf2 activators very good candidates for the treatment of iron overload disorders. Successful examples include the clinical use of omaveloxolone for Friedreich's Ataxia and dimethyl fumarate for relapsing-remitting multiple sclerosis. Despite these uses, the therapeutic potentials of Nrf2 activators for iron overload disorders may be overlooked in clinical practice. Therefore, this study talks about the potential use, possible mechanisms, and precautions of Nrf2 activators in treating rare iron overload diseases. In addition, a combination therapy with Nrf2 activators and iron chelators is proposed for clinical reference, aiming to facilitate the clinical use of Nrf2 activators for more iron overload disorders.

Studies of Slc30a10 Deficiency in Mice Reveal That Intestinal Iron Transporters Dmt1 and Ferroportin Transport Manganese

BACKGROUND & AIMS

SLC11A2 (DMT1) and SLC40A1 (ferroportin) are essential for dietary iron absorption, but their role in manganese transport is debated. SLC30A10 deficiency causes severe manganese excess due to loss of gastrointestinal manganese excretion. Patients are treated with chelators but also respond to oral iron, suggesting that iron can outcompete manganese for absorption in this disease. Here, we determine if divalent metal transport 1 (Dmt1) and ferroportin can transport manganese using Slc30a10-deficient mice as a model.

METHODS

Manganese absorption and levels and other disease parameters were assessed in Slc30a10-/- mice with and without intestinal Dmt1 and ferroportin deficiency using gastric gavage, surgical bile collections, multiple metal assays, and other techniques. The contribution of intestinal Slc30a10 deficiency to ferroportin-dependent manganese absorption was explored by determining if intestinal Slc30a10 deficiency increases manganese absorption in a mouse model of hereditary hemochromatosis, a disease of iron excess due to ferroportin upregulation.

RESULTS

Manganese absorption was increased in Slc30a10-deficient mice despite manganese excess. Intestinal Dmt1 and ferroportin deficiency attenuated manganese absorption and excess in Slc30a10-deficient mice. Intestinal Slc30a10 deficiency increased manganese absorption and levels in the hemochromatosis mouse model.

CONCLUSIONS

Aberrant absorption contributes prominently to SLC30A10 deficiency, a disease previously attributed to impaired excretion, and is dependent upon intestinal Dmt1 and ferroportin and exacerbated by loss of intestinal Slc30a10. This work expands our understanding of overlaps between manganese and iron transport and the mechanisms by which the body regulates absorption of 2 nutrients that can share transport pathways. We propose that a reconsideration of the role of Dmt1 and ferroportin in manganese homeostasis is warranted.

Hemochromatosis

Hemochromatosis is an inheritable condition that mainly affects White populations of European descent. Most patients remain asymptomatic, but others develop advanced organ damage that reduces quality of life and long-term survival. Arthropathy, diabetes mellitus, cirrhosis, hypogonadotropic hypogonadism, and cardiomyopathy are key clinical manifestations. Primary care and hospital medicine physicians play an essential role in early identification of this disease, which can be accomplished via standard hematologic testing. Early diagnosis and therapeutic phlebotomy improve clinical outcomes.

Diagnosis and Treatment of Hemochromatosis

Hemochromatosis is not a new disease and genetic variants for hemochromatosis have been identified in human fossils that are over 4,000 years old in North Western Europe1. These variants were postulated to promote iron absorption as a survival benefit. In contrast, excess iron absorption can lead to serious complications, including arthritis, liver fibrosis, cirrhosis, primary liver cancer, and diabetes. In this review, the emphasis is on recent developments in the diagnosis and treatment of hemochromatosis, focusing on those homozygous for the C282Y variant in the HFE gene. In this condition, there is a clear need for earlier diagnosis leading to earlier treatment to prevent morbidity and mortality from iron overload.

Advances, challenges and future applications of liver organoids in experimental regenerative medicine

The liver is a vital organ responsible for numerous metabolic processes in the human body, including the metabolism of drugs and nutrients. After liver damage, the organ can rapidly return to its original size if the causative factor is promptly eliminated. However, when the harmful stimulus persists, the liver's regenerative capacity becomes compromised. Substantial theoretical feasibility has been demonstrated at the levels of gene expression, molecular interactions, and intercellular dynamics, complemented by numerous successful animal studies. However, a robust model and carrier that closely resemble human physiology are still lacking for translating these theories into practice. The potential for liver regeneration has been a central focus of ongoing research. Over the past decade, the advent of organoid technology has provided improved models and materials for advancing research efforts. Liver organoid technology represents a novel in vitro culture system. After several years of refinement, human liver organoids can now accurately replicate the liver's morphological structure, nutrient and drug metabolism, gene expression, and secretory functions, providing a robust model for liver disease research. Regenerative medicine aims to replicate human organ or tissue functions to repair or replace damaged tissues, restore their structure or function, or stimulate the regeneration of tissues or organs within the body. Liver organoids possess the same structure and function as liver tissue, offering the potential to serve as a viable replacement for the liver, aligning with the goals of regenerative medicine. This review examines the role of liver organoids in regenerative medicine.

Exploring the Mechanisms of Iron Overload-Induced Liver Injury in Rats Based on Transcriptomics and Proteomics

Iron is a trace element that is indispensable for the growth and development of animals. Excessive iron supplementation may lead to iron overload and elevated reactive oxygen species (ROS) production in animals, causing cellular damage. Nevertheless, the precise mechanism by which iron overload causes cell injury remains to be fully elucidated. In this study, 16 male SD rats aged 6 to 7 weeks were randomly assigned to either a control group (CON) or an iron overload group (IO). Rats in the iron overload group received 150 mg/kg iron dextran injections every three days for a duration of four weeks. The results indicated that iron treatment with iron dextran significantly increased the scores of steatosis (p < 0.05) and inflammation (p < 0.05) in the NAS score. The integrated transcriptomic and proteomic analysis suggests that HO-1 and Lnc286.2 are potentially significant in iron overload-induced liver injury in rats. In vitro experiments utilizing ferric ammonium citrate (FAC) were conducted to establish an iron overload model in rat liver-derived BRL-3A cells. The result found that FAC treatment can significantly increase the BRL-3A cell's Fe2+ content (p < 0.05), ROS (p < 0.01), lipid ROS (p < 0.01) levels, and the expression of the HO-1 gene and protein (p < 0.01), aligning with proteomic and transcriptomic findings. HO-1 inhibition can significantly decrease BRL-3A cell vitality (p < 0.01) and promote ROS (p < 0.05) and lipid ROS (p < 0.01), thus aggravating FAC-induced BRL-3A cell iron overload damage. Using the agonist of HO-1 agonist cobalt protoporphyrin (CoPP) to induce HO-1 overexpression can significantly alleviate the decrease in FAC-induced BRL-3A cell viability (p < 0.01), ROS (p < 0.01), and lipid ROS (p < 0.01). In addition, siLnc286.2 treatment can increase HO-1 expression, alleviate the decline of FAC-induced BRL-3A cell activity, and increase lipid ROS (p < 0.05) content. In conclusion, the findings of this study suggest that by suppressing the expression of Lnc286.2, we can enhance the expression of HO-1, which in turn alleviates lipid peroxidation in cells and increases their antioxidant capacity, thereby exerting a protective effect against liver cell injury induced by iron overload.

Association of HFE genotypes with hemochromatosis-related phenotypes in the All of Us research program

Purpose

Type 1 hereditary hemochromatosis (HH) can result in iron overload and liver disease if not detected and treated early. Most cases are found among people homozygous for HFE p.Cys282Tyr variants. Compound heterozygosity with the HFE p.His63Asp variant is associated with disease to a lesser degree. We sought to examine the association of HFE variation with HH-related phenotypes and assess the prevalence of testing and diagnosis of HH using All of Us data.

Methods

We used data from 133,978 participants with genetic information linked to medical records. For different HFE genotypes, we examined the prevalence of HH diagnosis codes and related biochemical and clinical phenotypes.

Results

Among participants who were p.Cys282Tyr homozygotes, the prevalence of HH diagnosis codes was 22.6% among males and 15.6% among females. Serum transferrin-iron saturation measures were available only for 31.4% of males and 21.1% of females who were p.Cys282Tyr homozygotes. Liver disease, including cirrhosis or hepatocellular carcinoma, was present more among males who were p.Cys282Tyr homozygotes compared with males with no p.Cys282Tyr or p.His63Asp variants (15.5% vs 8.5%, P = .0001). Of the 71 participants who were p.Cys282Tyr homozygotes with indication of liver disease, 32 (45.1%) did not have a serum transferrin-iron saturation measure, and 37 (52.1%) did not have diagnosis codes for HH.

Conclusion

Limited serum transferrin-iron saturation measures or HH diagnosis codes among p.Cys282Tyr homozygotes, even those with liver disease, suggests potential undertesting and underdiagnosis of type 1 HH in clinical practice and a need for improved awareness, education, and testing around HH.

Iron-Mediated Regulation in Adipose Tissue: A Comprehensive Review of Metabolism and Physiological Effects

PURPOSE OF REVIEW

Review the latest data regarding the intersection of adipose tissue (AT) and iron to meet the needs of AT metabolism and the progression of related diseases.

RECENT FINDINGS

Iron is involved in fundamental biological metabolic processes and is precisely fine-tuned within the body to maintain cellular, tissue and even systemic iron homeostasis. AT not only serves as an energy storage depot but also represents the largest endocrine organ in the human body, maintaining systemic metabolic homeostasis. It is involved in physiological processes such as energy storage, insulin sensitivity regulation and lipid metabolism. As a unique iron-sensing tissue, AT expresses related regulatory factors, including the classic hepcidin, ferroportin (FPN), iron regulatory protein/iron responsive element (IRP/IRE) and ferritin. Consequently, the interaction between AT and iron is intricately intertwined. Imbalance of iron homeostasis produces the potential risks of steatosis, impaired glucose tolerance and insulin resistance, leading to AT dysfunction diseases, including obesity, type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). Despite the role of AT iron has garnered increasing attention in recent years, a comprehensive review that systematically organizes the connection between iron and AT remains lacking. Given the necessity of iron homeostasis, emphasizing its potential impact on AT function and metabolism regulation provides valuable insights into physiological effects such as adipocyte differentiation and thermogenesis. Futhermore, regulators including adipokines, mitochondria and macrophages have been mentioned, along with analyzing the novel perspective of iron as a key mediator influencing the fat-gut crosstalk.

[Arthropathy as the first manifestation of undiagnosed hemochromatosis: a case report on an unusual course]

A 54-year-old man presented with increasing arthralgia and swelling of the metacarpophalangeal (MCP) joints II and III for approximately 2 years. He also reported morning stiffness and joint pain in both knees and feet.Both MCP joints II and III and the proximal interphalangeal joints II and III were tender without visible swelling. X-rays of the hands showed symmetrical osteoarthritic changes of the MCP joints I-III on both sides. Joint ultrasound revealed symmetrical osteophyte formation without inflammatory signs. Laboratory tests showed elevated ferritin (1436µg/l), iron (252µg/dl), and transferrin saturation (79%). Genetic testing confirmed a homozygous C282Y mutation, and FibroScan elastography indicated advanced fibrosis.Hemochromatosis-associated arthropathy.A symptom-oriented analgesic treatment with Metamizole was initiated. During the hospital stay, the patient received physical and occupational therapy. Hepatology specialists will manage further treatment at a university center, and the outcome remains to be seen.Symmetrical involvement of the MCP joints II and III should raise suspicion of hemochromatosis.

Sex and Gender Differences in Iron Chelation

BACKGROUND/OBJECTIVES

In the absence of physiological mechanisms to excrete excessive iron, the administration of iron chelation therapy is necessary. Age and hormones have an impact on the absorption, distribution, metabolism, and excretion of the medications used to treat iron excess, resulting in notable sex- and gender-related variances.

METHODS

Here, we aimed to review the literature on sex and gender in iron overload assessment and treatment.

RESULTS

The development of iron chelators has shown to be a successful therapy for lowering the body's iron levels and averting the tissue damage and organ failure that follows. Numerous studies have described how individual factors can impact chelation treatment, potentially impact therapeutic response, and/or result in inadequate chelation or elevated toxicity; however, most of these data have not considered male and female patients as different groups, and particularly, the effect of hormonal variations in women have never been considered.

CONCLUSIONS

An effective iron chelation treatment should take into account sex and gender differences.

Mortality and risk of diabetes, liver disease, and heart disease in individuals with haemochromatosis HFE C282Y homozygosity and normal concentrations of iron, transferrin saturation, or ferritin: prospective cohort study

OBJECTIVES

To test whether haemochromatosis HFE C282Y homozygotes have increased risk of diabetes, liver disease, and heart disease even when they have normal plasma iron, transferrin saturation, or ferritin concentrations and to test whether C282Y homozygotes with diabetes, liver disease, or heart disease have increased mortality compared with non-carriers with these diseases.

DESIGN

Prospective cohort study.

SETTING

Three Danish general population cohorts: the Copenhagen City Heart Study, the Copenhagen General Population Study, and the Danish General Suburban Population Study.

PARTICIPANTS

132 542 individuals genotyped for the HFE C282Y and H63D variants, 422 of whom were C282Y homozygotes, followed prospectively for up to 27 years after study enrolment.

MAIN OUTCOME MEASURE

Hospital contacts and deaths, retrieved from national registers, covering all hospitals and deaths in Denmark.

RESULTS

Comparing C282Y homozygotes with non-carriers, hazard ratios were 1.72 (95% confidence interval (CI) 1.24 to 2.39) for diabetes, 2.22 (1.40 to 3.54) for liver disease, and 1.01 (0.78 to 1.31) for heart disease. Depending on age group, the absolute five year risk of diabetes was 0.54-4.3% in C282Y homozygous women, 0.37-3.0% in non-carrier women, 0.86-6.8% in C282Y homozygous men, and 0.60-4.80% in non-carrier men. When studied according to levels of iron, transferrin saturation, and ferritin in a single blood sample obtained at study enrolment, risk of diabetes was increased in C282Y homozygotes with normal transferrin saturation (hazard ratio 2.00, 95% CI 1.04 to 3.84) or ferritin (3.76, 1.41 to 10.05) and in C282Y homozygotes with normal levels of both ferritin and transferrin saturation (6.49, 2.09 to 20.18). C282Y homozygotes with diabetes had a higher risk of death from any cause than did non-carriers with diabetes (hazard ratio 1.94, 95% CI 1.19 to 3.18), but mortality was not increased in C282Y homozygotes without diabetes. The percentage of all deaths among C282Y homozygotes that could theoretically be prevented if excess deaths in individuals with a specific disease were eliminated (the population attributable fraction) was 27.3% (95% CI 12.4% to 39.7%) for diabetes and 14.4% (3.1% to 24.3%) for liver disease. Risk of diabetes or liver disease was not increased in H63D heterozygotes, H63D homozygotes, C282Y heterozygotes, or C282Y/H63D compound heterozygotes.

CONCLUSIONS

Haemochromatosis C282Y homozygotes with normal transferrin saturation and/or ferritin, not recommended for HFE genotyping according to most guidelines, had increased risk of diabetes. Furthermore, C282Y homozygotes with diabetes had higher mortality than non-carriers with diabetes, and 27.3% of all deaths among C282Y homozygotes were potentially attributable to diabetes. These results indicate that prioritising detection and treatment of diabetes in C282Y homozygotes may be relevant.

Diagnosis and management of hereditary hemochromatosis: lifestyle modification, phlebotomy, and blood donation

The term hemochromatosis refers to a group of genetic disorders characterized by hepcidin insufficiency in the context of normal erythropoiesis, iron hyperabsorption, and expansion of the plasma iron pool with increased transferrin saturation, the diagnostic hallmark of the disease. This results in the formation of toxic non-transferrin-bound iron, which ultimately accumulates in multiple organs, including the liver, heart, endocrine glands, and joints. The most common form is HFE-hemochromatosis (HFE-H) due to p.Cys282Tyr (C282Y) homozygosity, present in nearly 1 in 200 people of Northern European descent but characterized by low penetrance, particularly in females. Genetic and lifestyle cofactors (especially alcohol and dysmetabolic features) significantly modulate clinical expression so that HFE-H can be considered a multifactorial disease. Nowadays, HFE-H is mostly diagnosed before organ damage and is easily treated by phlebotomy, with an excellent prognosis. After iron depletion, maintenance phlebotomy can be usefully transformed into a blood donation program. Lifestyle changes are important for management. Non-HFE-H, much rarer but highly penetrant, may lead to early and severe heart, liver, and endocrine complications. Managing severe hemochromatosis requires a comprehensive approach optimally provided by consultation with specialized centers. In clinical practice, a proper diagnostic approach is paramount for patients referred for hyperferritinemia, a frequent finding that reflects hemochromatosis only in a minority of cases.

Why cells need iron: a compendium of iron utilisation

Iron deficiency is globally prevalent, causing an array of developmental, haematological, immunological, neurological, and cardiometabolic impairments, and is associated with symptoms ranging from chronic fatigue to hair loss. Within cells, iron is utilised in a variety of ways by hundreds of different proteins. Here, we review links between molecular activities regulated by iron and the pathophysiological effects of iron deficiency. We identify specific enzyme groups, biochemical pathways, cellular functions, and cell lineages that are particularly iron dependent. We provide examples of how iron deprivation influences multiple key systems and tissues, including immunity, hormone synthesis, and cholesterol metabolism. We propose that greater mechanistic understanding of how cellular iron influences physiological processes may lead to new therapeutic opportunities across a range of diseases.

Hepatic immune regulation and sex disparities

Chronic liver disease is a major cause of morbidity and mortality worldwide. Epidemiology, clinical phenotype and response to therapies for gastrointestinal and liver diseases are commonly different between women and men due to sex-specific hormonal, genetic and immune-related factors. The hepatic immune system has unique regulatory functions that promote the induction of intrahepatic tolerance, which is key for maintaining liver health and homeostasis. In liver diseases, hepatic immune alterations are increasingly recognized as a main cofactor responsible for the development and progression of chronic liver injury and fibrosis. In this Review, we discuss the basic mechanisms of sex disparity in hepatic immune regulation and how these mechanisms influence and modify the development of autoimmune liver diseases, genetic liver diseases, portal hypertension and inflammation in chronic liver disease. Alterations in gut microbiota and their crosstalk with the hepatic immune system might affect the progression of liver disease in a sex-specific manner, creating potential opportunities for novel diagnostic and therapeutic approaches to be evaluated in clinical trials. Finally, we identify and propose areas for future basic, translational and clinical research that will advance our understanding of sex disparities in hepatic immunity and liver disease.

Computed Tomography and Magnetic Resonance Imaging in Liver Iron Overload: From Precise Quantification to Prognosis Assessment

Liver iron overload is associated with conditions such as hereditary hemochromatosis, thalassemia major, and chronic liver diseases. The liver-related outcomes, patient outcomes, and treatment recommendations of these patients differ depending on the cause and extent of iron overload. Accurate quantification of the liver iron concentration (LIC) is critical for effective patient management. This review focuses on the application of computed tomography (CT) and magnetic resonance imaging (MRI) for the precise quantification and prognostic assessment of liver iron overload. In recent years, the use of dual-energy CT and the emergence of MRI-based sequences (such as UTE, QSM, Dixon, and CSE technologies) have significantly increased the potential for noninvasive liver iron quantification. However, the establishment of internationally standardized imaging parameters, postprocessing procedures, and reporting protocols is urgently needed for better management of patients with liver iron overload.

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

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

SUGP2 p.(Arg639Gln) variant is involved in the pathogenesis of hemochromatosis via the CIRBP/BMPER signaling pathway

Pathogenic variants in HFE and non-HFE genes have been identified in hemochromatosis in different patient populations, but there are still a certain number of patients with unexplained primary iron overload. We recently identified in Chinese patients a recurrent p.(Arg639Gln) variant in SURP and G-patch domain containing 2 (SUGP2), a potential mRNA splicing-related factor. However, the target gene of SUGP2 and affected iron-regulating pathway remains unknown. We aimed to investigate the pathogenicity and underlying mechanism of this variant in hemochromatosis. RNA-seq analysis revealed that SUGP2 knockdown caused abnormal alternative splicing of CIRBP pre-mRNA, resulting in an increased normal splicing form of CIRBP V1, which in turn increased the expression of BMPER by enhancing its mRNA stability and translation. Furthermore, RNA-protein pull-down and RNA immunoprecipitation assays revealed that SUGP2 inhibited splicing of CIRBP pre-mRNA by a splice site variant at CIRBP c.492 and was more susceptible to CIRBP c.492 C/C genotype. Cells transfected with SUGP2 p.(Arg639Gln) vector showed up-regulation of CIRBP V1 and BMPER expression and down-regulation of pSMAD1/5 and HAMP expression. CRISPR-Cas9 mediated SUGP2 p.(Arg622Gln) knock-in mice showed increased iron accumulation in the liver, higher total serum iron, and decreased serum hepcidin level. A total of 10 of 54 patients with hemochromatosis (18.5%) harbored the SUGP2 p.(Arg639Gln) variant and carried CIRBP c.492 C/C genotype, and had increased BMPER expression in the liver. Altogether, the SUGP2 p.(Arg639Gln) variant down-regulates hepcidin expression through the SUGP2/CIRBP/BMPER axis, which may represent a novel pathogenic factor for hemochromatosis.

Iron, hemochromatosis genotypes, and risk of infections: a cohort study of 142 188 general population individuals

ABSTRACT

It is unclear whether risk of infection is increased in individuals with hereditary hemochromatosis and in individuals with low or high plasma iron, transferrin saturation, or ferritin. Therefore, we tested whether high and low iron, transferrin saturation, and ferritin are associated with risk of infections observationally and genetically through HFE genotypes. We studied 142 188 Danish general population individuals. Iron, transferrin saturation, and ferritin were measured in 136 656, 136 599, and 38 020 individuals, respectively. HFE was genotyped for C282Y and H63D in 132 542 individuals. Median follow-up after study enrollment was 8 years (range, 0-38) for hospital and emergency room admissions with infections (n = 20 394) using the National Patient Register, covering all Danish hospitals. Hazard ratios for any infection were 1.20 (95% confidence interval [CI], 1.12-1.28) and 1.14 (95% CI, 1.07-1.22) in individuals with plasma iron ≤5th or ≥95th percentile compared with individuals with iron from 26th to 74th percentiles. Findings for transferrin saturation were similar, whereas infection risk was not increased in individuals with ferritin ≤5th or ≥95th percentile. Hazard ratios in C282Y homozygotes vs noncarriers were 1.40 (95% CI, 1.16-1.68) for any infection, 1.69 (95% CI, 1.05-2.73) for sepsis, and 2.34 (95% CI, 1.41-3.90) for death from infectious disease. Risk of infection was increased in C282Y homozygotes with normal plasma iron, transferrin saturation, or ferritin, and in C282Y homozygotes without liver disease, diabetes, and/or heart failure. In summary, low and high plasma iron and transferrin saturation were independently associated with increased infection risk. C282Y homozygotes had increased risk of any infection, sepsis, and death from infections. Even C282Y homozygotes with normal iron, transferrin saturation, or ferritin, not currently recommended for genotyping, had increased infection risk.

Population Screening for Hereditary Haemochromatosis-Should It Be Carried Out, and If So, How?

The Human Genome Project, completed in 2003, heralded a new era in precision medicine. Somewhat tempering the excitement of the elucidation of the human genome is the emerging recognition that there are fewer single gene disorders than first anticipated, with most diseases predicted to be polygenic or at least gene-environment modified. Hereditary haemochromatosis (HH) is an inherited iron overload disorder, for which the vast majority of affected individuals (>90%) have homozygosity for a single pathogenic variant in the HFE gene, resulting in p.Cys282Tyr. Further, there is significant benefit to an individual in identifying the genetic risk of HH, since the condition evolves over decades, and the opportunity to intervene and prevent disease is both simple and highly effective through regular venesection. Add to that the immediate benefit to society of an increased pool of ready blood donors (blood obtained from HH venesections can generally be used for donation), and the case for population screening to identify those genetically at risk for HH becomes more cogent. Concerns about genetic discrimination, creating a cohort of "worried well", antipathy to acting on medical advice to undertake preventive venesection or simply not understanding the genetic risk of the condition adequately have all been allayed by a number of investigations. So why then has HH population genetic screening not been routinely implemented anywhere in the world? The answer is complex, but in this article we explore the pros and cons of screening for HH and the different views regarding whether it should be phenotypic (screening for iron overload by serum ferritin and/or transferrin saturation) or genotypic (testing for HFE p.Cys282Tyr). We argue that now is the time to give this poster child for population genetic screening the due consideration required to benefit the millions of individuals at risk of HFE-related iron overload.

Manganese transporter SLC30A10 and iron transporters SLC40A1 and SLC11A2 impact dietary manganese absorption

SLC30A10 deficiency is a disease of severe manganese excess attributed to loss of SLC30A10-dependent manganese excretion via the gastrointestinal tract. Patients develop dystonia, cirrhosis, and polycythemia. They are treated with chelators but also respond to oral iron, suggesting that iron can outcompete manganese for absorption in this disease. Here we explore the latter observation. Intriguingly, manganese absorption is increased in Slc30a10-deficient mice despite manganese excess. Studies of multiple mouse models indicate that increased dietary manganese absorption reflects two processes: loss of manganese export from enterocytes into the gastrointestinal tract lumen by SLC30A10, and increased absorption of dietary manganese by iron transporters SLC11A2 (DMT1) and SLC40A1 (ferroportin). Our work demonstrates that aberrant absorption contributes prominently to SLC30A10 deficiency and expands our understanding of biological interactions between iron and manganese. Based on these results, we propose a reconsideration of the role of iron transporters in manganese homeostasis is warranted.

HFE and Non-HFE Hereditary Hemochromatosis Based on Screening of 854 Individuals: 12 Years of an Iranian Experience

Introduction: The genetics of hereditary hemochromatosis (HH) is understudied in Iran. Here, we report the result of genetic screening of 854 individuals, referred as "suspected cases of HH," to a diagnostic laboratory in Iran over a 12-year period. Materials and Methods: From 2011 to 2012, 121 cases were screened for HH using Sanger sequencing of HFE exons. After 2012, this method was replaced by a commercial reverse hybridization assay (RHA) targeting 18 variants in the HFE, TFR2, and FPN1(SLC40A1) genes and 733 cases were screened using this method. Results: From the total studied population, HH was confirmed by genetic diagnosis in only seven cases (0.82%): two homozygotes for HFE:C282Y and five homozygotes for TFR2:AVAQ 594-597 deletion. In 254 cases (29.7%), H63D, C282Y, S65C, and four other HFE variants not targeted by RHA were identified. Although the resulting genotypes in the latter cases did not confirm HH, some of them were known modifying factors of iron overload or could cause HH in combination with a possibly undetected variant. No variant was detected in 593 cases (69.4%). Conclusion: This study showed that the spectrum of genetic variants of HH in the Iranian population includes HFE and TFR2 variants. However, HH was not confirmed in the majority (99.2%) of suspected cases. This could be explained by limitations of our genetic diagnostics and possible inaccuracies in clinical suspicion of HH. A cooperative clinical and genetic investigation is proposed as a solution to this issue.

MRI-derived brain iron, grey matter volume, and risk of dementia and Parkinson's disease: Observational and genetic analysis in the UK Biobank cohort

BACKGROUND

Iron overload is observed in neurodegenerative diseases, especially Alzheimer's disease (AD) and Parkinson's disease (PD). Homozygotes for the iron-overload (haemochromatosis) causing HFE p.C282Y variant have increased risk of dementia and PD. Whether brain iron deposition is causal or secondary to the neurodegenerative processes in the general population is unclear.

METHODS

We analysed 39,533 UK Biobank participants of European genetic ancestry with brain MRI data. We studied brain iron estimated by R2* and quantitative susceptibility mapping (QSM) in 8 subcortical regions: accumbens, amygdala, caudate, hippocampus, pallidum, putamen, substantia nigra, and thalamus. We performed genome-wide associations studies (GWAS) and used Mendelian Randomization (MR) methods to estimate the causal effect of brain iron on grey matter volume, and risk of AD, non-AD and PD. We also used MR to test whether genetic liability to AD or PD causally increased brain iron (R2* and QSM).

FINDINGS

In GWAS of R2* and QSM we replicated 83% of previously reported genetic loci and identified 174 further loci across all eight brain regions. Higher genetically predicted brain iron, using both R2* and QSM, was associated with lower grey matter volumes in the caudate, putamen and thalamus (e.g., Beta-putamenQSM: -0.37, p = 2*10-46). Higher genetically predicted thalamus R2* was associated with increased risk of non-AD dementia (OR 1.36(1.16;1.60), p = 2*10-4) but not AD (p > 0.05). In males, genetically predicted putamen R2* increased non-AD dementia risk, but not in females. Higher genetically predicted iron in the caudate, putamen, and substantia nigra was associated with an increased risk of PD (Odds Ratio QSM ∼ substantia-nigra 1.21(1.07;1.37), p = 0.003). Genetic liability to AD or PD was not associated with R2* or QSM in the dementia or PD-associated regions.

INTERPRETATION

Our genetic analysis supports a causal effect of higher iron deposition in specific subcortical brain regions for Parkinson's disease, grey matter volume, and non-Alzheimer's dementia.

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

Scientific opinion on the tolerable upper intake level for iron

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for iron. Systematic reviews were conducted to identify evidence regarding high iron intakes and risk of chronic diseases, adverse gastrointestinal effects and adverse effects of iron supplementation in infancy, young childhood and pregnancy. It is established that systemic iron overload leads to organ toxicity, but no UL could be established. The only indicator for which a dose-response could be established was black stools, which reflect the presence of large amounts of unabsorbed iron in the gut. This is a conservative endpoint among the chain of events that may lead to systemic iron overload but is not adverse per se. Based on interventions in which black stools did not occur at supplemental iron intakes of 20-25 mg/day (added to a background intake of 15 mg/day), a safe level of intake for iron of 40 mg/day for adults (including pregnant and lactating women) was established. Using allometric scaling (body weight0.75), this value was scaled down to children and adolescents and safe levels of intakes between 10 mg/day (1-3 years) and 35 mg/day (15-17 years) were derived. For infants 7-11 months of age who have a higher iron requirement than young children, allometric scaling was applied to the supplemental iron intakes (i.e. 25 mg/day) and resulted in a safe level of supplemental iron intake of 5 mg/day. This value was extended to 4-6 month-old infants and refers to iron intakes from fortified foods and food supplements, not from infant and follow-on formulae. The application of the safe level of intake is more limited than a UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Advance in Iron Metabolism, Oxidative Stress and Cellular Dysfunction in Experimental and Human Kidney Diseases

Kidney diseases pose a significant global health issue, frequently resulting in the gradual decline of renal function and eventually leading to end-stage renal failure. Abnormal iron metabolism and oxidative stress-mediated cellular dysfunction facilitates the advancement of kidney diseases. Iron homeostasis is strictly regulated in the body, and disturbance in this regulatory system results in abnormal iron accumulation or deficiency, both of which are associated with the pathogenesis of kidney diseases. Iron overload promotes the production of reactive oxygen species (ROS) through the Fenton reaction, resulting in oxidative damage to cellular molecules and impaired cellular function. Increased oxidative stress can also influence iron metabolism through upregulation of iron regulatory proteins and altering the expression and activity of key iron transport and storage proteins. This creates a harmful cycle in which abnormal iron metabolism and oxidative stress perpetuate each other, ultimately contributing to the advancement of kidney diseases. The crosstalk of iron metabolism and oxidative stress involves multiple signaling pathways, such as hypoxia-inducible factor (HIF) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways. This review delves into the functions and mechanisms of iron metabolism and oxidative stress, along with the intricate relationship between these two factors in the context of kidney diseases. Understanding the underlying mechanisms should help to identify potential therapeutic targets and develop novel and effective therapeutic strategies to combat the burden of kidney diseases.

Iron overload promotes hemochromatosis-associated osteoarthritis via the mTORC1-p70S6K/4E-BP1 pathway

BACKGROUNDS

Joint iron overload in hemochromatosis induces M1 polarization in synovial macrophages, releasing pro-inflammatory factors and leading to osteoarthritis development. However, the mechanism by which iron overload regulates M1 polarization remains unclear. This study aims to elucidate the mechanism by which synovial iron overload promotes macrophage M1 polarization.

METHODS

In vitro, RAW264.7 macrophages were treated with iron and divided into five groups based on the concentration of the iron chelator, desferrioxamine (DFO): Ctrl, Fe, DFO1, DFO2, and DFO3. In vivo, rats were categorized into five groups based on iron overload and intra-articular DFO injection: A-Ctrl, A-Fe, A-DFO1, A-DFO2, and A-DFO3. Osteoarthritis was induced by transecting the left knee anterior cruciate ligament. Macrophage morphology was observed; Prussian Blue staining quantified iron deposition in macrophages, synovium, and liver; serum iron concentration was measured using the ferrozine method; cartilage damage was assessed using H&E and Safranin O-Fast Green staining; qPCR detected iNOS and Arg-1 expression; Western Blot analyzed the protein expression of iNOS, Arg-1, 4E-BP1, phosphorylated 4E-BP1, p70S6K, and phosphorylated p70S6K; ELISA measured TNF-α and IL-6 concentrations in supernatants; and immunohistochemistry examined the protein expression of F4/80, iNOS, Arg-1, 4E-BP1, phosphorylated 4E-BP1, p70S6K, and phosphorylated p70S6K in the synovium.

RESULTS

In vitro, iron-treated macrophages exhibited Prussian Blue staining indicative of iron overload and morphological changes towards M1 polarization. qPCR and Western Blot revealed increased expression of the M1 polarization markers iNOS and its protein. ELISA showed elevated TNF-α and IL-6 levels in supernatants. In vivo, ferrozine assay indicated significantly increased serum iron concentrations in all groups except A-Ctrl; Prussian Blue staining showed increased liver iron deposition in all groups except A-Ctrl. Iron deposition in rat synovium decreased in a DFO concentration-dependent manner; immunohistochemistry showed a corresponding decrease in iNOS and phosphorylated 4E-BP1 expression, and an increase in Arg-1 expression.

CONCLUSION

Intracellular iron overload may exacerbate joint cartilage damage by promoting synovial macrophage M1 polarization through phosphorylation of 4E-BP1 in the mTORC1-p70S6K/4E-BP1 pathway.

Clinical characteristics of HFE C282Y/H63D compound heterozygotes identified in a specialty practice: key differences from HFE C282Y homozygotes

BACKGROUND

Patients with p.C282Y homozygous (p.C282Y) HFE mutations are more likely to develop hemochromatosis (HC) than p.C282Y/p.H63D compound heterozygotes (p.C282Y/H63D).

RESEARCH DESIGN AND METHODS

We conducted a retrospective chart review of 90 p.C282Y and 31 p.C282Y/H63D patients at a referral practice to illustrate the differences in the natural history of the disease in these two HC cohorts.

RESULTS

Over a median follow-up of 17 years, p.C282Y had higher mean serum ferritin (1105 mg/dL vs. 534 mg/dL, p = 0.001) and transferrin saturations (75.3% vs. 49.5%, p = 0.001) at diagnosis. p.C282Y underwent more therapeutic phlebotomies (TP) till de-ironing (mean 24 vs. 10), had higher mean mobilized iron stores (4759 mg vs. 1932 mg), and required more annual maintenance TP (1.9/year vs. 1.1/year, p = 0.039). p.C282Y/H63D were more likely to have obesity (45.2% vs. 20.2%, p = 0.007) at diagnosis, with a non-significant trend toward consuming more alcohol. There was no significant difference in the development of HC-related complications between the two cohorts.

CONCLUSIONS

p.C282Y have a higher mobilizable iron and require more TP. p.C282Y/H63D likely require additional insults such as obesity or alcohol use to develop elevated ferritin. De-ironing may mitigate the risk of developing HC-related complications.

Advances in the Pathogenesis of Metabolic Liver Disease-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer globally and the primary cause of death in cancer cases, with significant public health concern worldwide. Despite the overall decline in the incidence and mortality rates of HCC in recent years in recent years, the emergence of metabolic liver disease-related HCC is causing heightened concern, especially in countries like the United States, the United Kingdom, and P.R. China. The escalation of metabolic liver disease-related HCC is attributed to a combination of factors, including genetic predisposition, lifestyle choices, and changes in the living environment. However, the pathogenesis of metabolic liver disease-associated HCC remains imperfect. In this review, we encapsulate the latest advances and essential aspects of the pathogenesis of metabolic liver disease-associated HCC, including alcoholic liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and inherited metabolic liver diseases.

HFE genotypes, haemochromatosis diagnosis and clinical outcomes at age 80 years: a prospective cohort study in the UK Biobank

OBJECTIVES

HFE haemochromatosis genetic variants have an uncertain clinical penetrance, especially to older ages and in undiagnosed groups. We estimated p.C282Y and p.H63D variant cumulative incidence of multiple clinical outcomes in a large community cohort.

DESIGN

Prospective cohort study.

SETTING

22 assessment centres across England, Scotland, and Wales in the UK Biobank (2006-2010).

PARTICIPANTS

451 270 participants genetically similar to the 1000 Genomes European reference population, with a mean of 13.3-year follow-up through hospital inpatient, cancer registries and death certificate data.

MAIN OUTCOME MEASURES

Cox proportional HRs of incident clinical outcomes and mortality in those with HFE p.C282Y/p.H63D mutations compared with those with no variants, stratified by sex and adjusted for age, assessment centre and genetic stratification. Cumulative incidences were estimated from age 40 years to 80 years.

RESULTS

12.1% of p.C282Y+/+ males had baseline (mean age 57 years) haemochromatosis diagnoses, with a cumulative incidence of 56.4% at age 80 years. 33.1% died vs 25.4% without HFE variants (HR 1.29, 95% CI: 1.12 to 1.48, p=4.7×10-4); 27.9% vs 17.1% had joint replacements, 20.3% vs 8.3% had liver disease, and there were excess delirium, dementia, and Parkinson's disease but not depression. Associations, including excess mortality, were similar in the group undiagnosed with haemochromatosis. 3.4% of women with p.C282Y+/+ had baseline haemochromatosis diagnoses, with a cumulative incidence of 40.5% at age 80 years. There were excess incident liver disease (8.9% vs 6.8%; HR 1.62, 95% CI: 1.27 to 2.05, p=7.8×10-5), joint replacements and delirium, with similar results in the undiagnosed. p.C282Y/p.H63D and p.H63D+/+ men or women had no statistically significant excess fatigue or depression at baseline and no excess incident outcomes.

CONCLUSIONS

Male and female p.C282Y homozygotes experienced greater excess morbidity than previously documented, including those undiagnosed with haemochromatosis in the community. As haemochromatosis diagnosis rates were low at baseline despite treatment being considered effective, trials of screening to identify people with p.C282Y homozygosity early appear justified.

Oral iron therapy: Current concepts and future prospects for improving efficacy and outcomes

Iron deficiency (ID) and iron-deficiency anaemia (IDA) are global public health concerns, most commonly afflicting children, pregnant women and women of childbearing age. Pathological outcomes of ID include delayed cognitive development in children, adverse pregnancy outcomes and decreased work capacity in adults. IDA is usually treated by oral iron supplementation, typically using iron salts (e.g. FeSO4 ); however, dosing at several-fold above the RDA may be required due to less efficient absorption. Excess enteral iron causes adverse gastrointestinal side effects, thus reducing compliance, and negatively impacts the gut microbiome. Recent research has sought to identify new iron formulations with better absorption so that lower effective dosing can be utilized. This article outlines emerging research on oral iron supplementation and focuses on molecular mechanisms by which different supplemental forms of iron are transported across the intestinal epithelium and whether these transport pathways are subject to regulation by the iron-regulatory hormone hepcidin.

Hemochromatosis: Ferroptosis, ROS, Gut Microbiome, and Clinical Challenges with Alcohol as Confounding Variable

Hemochromatosis represents clinically one of the most important genetic storage diseases of the liver caused by iron overload, which is to be differentiated from hepatic iron overload due to excessive iron release from erythrocytes in patients with genetic hemolytic disorders. This disorder is under recent mechanistic discussion regarding ferroptosis, reactive oxygen species (ROS), the gut microbiome, and alcohol abuse as a risk factor, which are all topics of this review article. Triggered by released intracellular free iron from ferritin via the autophagic process of ferritinophagy, ferroptosis is involved in hemochromatosis as a specific form of iron-dependent regulated cell death. This develops in the course of mitochondrial injury associated with additional iron accumulation, followed by excessive production of ROS and lipid peroxidation. A low fecal iron content during therapeutic iron depletion reduces colonic inflammation and oxidative stress. In clinical terms, iron is an essential trace element required for human health. Humans cannot synthesize iron and must take it up from iron-containing foods and beverages. Under physiological conditions, healthy individuals allow for iron homeostasis by restricting the extent of intestinal iron depending on realistic demand, avoiding uptake of iron in excess. For this condition, the human body has no chance to adequately compensate through removal. In patients with hemochromatosis, the molecular finetuning of intestinal iron uptake is set off due to mutations in the high-FE2+ (HFE) genes that lead to a lack of hepcidin or resistance on the part of ferroportin to hepcidin binding. This is the major mechanism for the increased iron stores in the body. Hepcidin is a liver-derived peptide, which impairs the release of iron from enterocytes and macrophages by interacting with ferroportin. As a result, iron accumulates in various organs including the liver, which is severely injured and causes the clinically important hemochromatosis. This diagnosis is difficult to establish due to uncharacteristic features. Among these are asthenia, joint pain, arthritis, chondrocalcinosis, diabetes mellitus, hypopituitarism, hypogonadotropic hypogonadism, and cardiopathy. Diagnosis is initially suspected by increased serum levels of ferritin, a non-specific parameter also elevated in inflammatory diseases that must be excluded to be on the safer diagnostic side. Diagnosis is facilitated if ferritin is combined with elevated fasting transferrin saturation, genetic testing, and family screening. Various diagnostic attempts were published as algorithms. However, none of these were based on evidence or quantitative results derived from scored key features as opposed to other known complex diseases. Among these are autoimmune hepatitis (AIH) or drug-induced liver injury (DILI). For both diseases, the scored diagnostic algorithms are used in line with artificial intelligence (AI) principles to ascertain the diagnosis. The first-line therapy of hemochromatosis involves regular and life-long phlebotomy to remove iron from the blood, which improves the prognosis and may prevent the development of end-stage liver disease such as cirrhosis and hepatocellular carcinoma. Liver transplantation is rarely performed, confined to acute liver failure. In conclusion, ferroptosis, ROS, the gut microbiome, and concomitant alcohol abuse play a major contributing role in the development and clinical course of genetic hemochromatosis, which requires early diagnosis and therapy initiation through phlebotomy as a first-line treatment.

Iron, Oxidative Stress, and Metabolic Dysfunction-Associated Steatotic Liver Disease

Excess free iron is a substrate for the formation of reactive oxygen species (ROS), thereby augmenting oxidative stress. Oxidative stress is a well-established cause of organ damage in the liver, the main site of iron storage. Ferroptosis, an iron-dependent mechanism of regulated cell death, has recently been gaining attention in the development of organ damage and the progression of liver disease. We therefore summarize the main mechanisms of iron metabolism, its close connection to oxidative stress and ferroptosis, and its particular relevance to disease mechanisms in metabolic-dysfunction-associated fatty liver disease and potential targets for therapy from a clinical perspective.

Pierre TG, Chen J, Frazer DM, Ramm LE, Ramm GA. Extrahepatic Iron Loading Associates With the Propensity to Develop Advanced Hepatic Fibrosis in Hemochromatosis

Background and Aims

Hemostatic iron regulator-hemochromatosis can result in progressive iron-loading and advanced hepatic fibrosis in some individuals. We studied total body and hepatic iron loading to determine whether the distribution of iron-loading influences the risk of advanced fibrosis.

Methods

One hundred thirty-eight men and 66 women with hemochromatosis who underwent liver biopsy for staging of hepatic fibrosis had evaluation of hepatic iron concentration (HIC), hepatic iron index (HIC/age), total body iron stores (mobilizable iron), and mobilizable iron/HIC ratio (a marker of total body iron relative to hepatic iron). The potential impact of liver volume on mobilizable iron stores was assessed using magnetic resonance imaging in a separate cohort of 19 newly diagnosed individuals with hemochromatosis.

Results

Of 204 biopsied subjects, 41 had advanced fibrosis and exhibited 60% greater accumulation of mobilizable iron relative to HIC (mean 0.070 ± 0.008 g Fe/[μmol Fe/g]) compared with 163 subjects with low-grade fibrosis (mean 0.044 ± 0.002 g Fe/[μmol Fe/g], P < .0001). Linear regression modeling confirmed a discrete advanced hepatic fibrosis phenotype associated with greater mobilizable iron stores relative to HIC. The ratios of the upper to lower 95% limits of the distributions of liver volumes and the mobilizable iron/HIC ratios were 2.7 (95% confidence interval 2.3-3.0) and 9.7 (95% confidence interval 8.0-11.7), respectively, indicating that the distribution of liver volumes is not sufficiently wide to explain the variability in mobilizable iron/HIC ratios, suggesting that significant extrahepatic iron loading is present in those with advanced hepatic fibrosis.

Conclusion

Advanced hepatic fibrosis develops in hemostatic iron regulator-hemochromatosis individuals who also have excessive extrahepatic mobilizable iron stores.

[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.

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.

The complex relationship between iron status and anemia in pregnant and postpartum women in India: Analysis of two Indian study cohorts of uncomplicated pregnancies

Low hemoglobin is widely used as an indicator of iron deficiency anemia in India and other low-and-middle income counties, but anemia need not accurately reflect iron deficiency. We examined the relationship between hemoglobin and biomarkers of iron status in antenatal and postnatal period. Secondary analysis of uncomplicated singleton pregnancies in two Indian study cohorts: 1132 antenatal women in third trimester and 837 postnatal women 12-72 h after childbirth. Associations of hemoglobin with ferritin in both data sets, and with sTfR, TSAT, and hepcidin in the postnatal cohort were examined using multivariable linear regression. Multinomial logistic regression was used to examine the association between severity of anemia and iron status. Regression models were adjusted for potential confounders. Over 55% of the women were anemic; 34% of antenatal and 40% of postnatal women had low ferritin, but 4% antenatal and 6% postnatal women had high ferritin. No evidence of association between hemoglobin and ferritin was observed (antenatal: adjusted coefficient [aCoef] -0.0004, 95% confidence interval [CI] -0.001, 0.001; postnatal: aCoef -0.0001, 95% CI -0.001, 0.001). We found a significant linear association of hemoglobin with sTfR (aCoef -0.04, 95% CI -0.07, -0.01), TSAT (aCoef -0.005, 95% CI -0.008, -0.002), and hepcidin (aCoef 0.02, 95% CI 0.02, 0.03) in postnatal women. Likelihood of low ferritin was more common in anemic than non-anemic women, but high ferritin was also more common in women with severe anemia in both cohorts. Causes of anemia in pregnant and postpartum women in India are multifactorial; low hemoglobin alone is not be a useful marker of iron deficiency.

Sigma Receptors: Novel Regulators of Iron/Heme Homeostasis and Ferroptosis

Sigma receptors are non-opiate/non-phencyclidine receptors that bind progesterone and/or heme and also several unrelated xenobiotics/chemicals. They reside in the plasma membrane and in the membranes of the endoplasmic reticulum, mitochondria, and nucleus. Until recently, the biology/pharmacology of these proteins focused primarily on their role in neuronal functions in the brain/retina. However, there have been recent developments in the field with the discovery of unexpected roles for these proteins in iron/heme homeostasis. Sigma receptor 1 (S1R) regulates the oxidative stress-related transcription factor NRF2 and protects against ferroptosis, an iron-induced cell death process. Sigma receptor 2 (S2R), which is structurally unrelated to S1R, complexes with progesterone receptor membrane components PGRMC1 and PGRMC2. S2R, PGRMC1, and PGRMC2, either independently or as protein-protein complexes, elicit a multitude of effects with a profound influence on iron/heme homeostasis. This includes the regulation of the secretion of the iron-regulatory hormone hepcidin, the modulation of the activity of mitochondrial ferrochelatase, which catalyzes iron incorporation into protoporphyrin IX to form heme, chaperoning heme to specific hemoproteins thereby influencing their biological activity and stability, and protection against ferroptosis. Consequently, S1R, S2R, PGRMC1, and PGRMC2 potentiate disease progression in hemochromatosis and cancer. These new discoveries usher this intriguing group of non-traditional progesterone receptors into an unchartered territory in biology and medicine.

A "Mix and Match" in Hemochromatosis-A Case Report and Literature Focus on the Liver

Hemochromatosis is a genetic disorder characterized by increased iron storage in various organs with progressive multisystemic damage. Despite the reports dating back to 1865, the diagnosis of hemochromatosis poses a challenge to clinicians due to its non-specific symptoms and indolent course causing significant delay in disease recognition. The key organ that is affected by iron overload is the liver, suffering from fibrosis, cirrhosis or hepatocellular carcinoma, complications that can be prevented via early diagnosis and treatment. This review aims to draw attention to the pitfalls in diagnosing hemochromatosis. We present a case with multiorgan complaints, abnormal iron markers and a consistent genetic result. We then examine the relevant literature and discuss hemochromatosis subtypes and liver involvement, including transplant outcome and treatment options. In summary, hemochromatosis remains difficult to diagnose due to its symptom heterogeneity and rarity; thus, further education for practitioners of all disciplines is useful in facilitating its early recognition and management.

Oxidative Stress in Liver Pathophysiology and Disease

The liver is an organ that is particularly exposed to reactive oxygen species (ROS), which not only arise during metabolic functions but also during the biotransformation of xenobiotics. The disruption of redox balance causes oxidative stress, which affects liver function, modulates inflammatory pathways and contributes to disease. Thus, oxidative stress is implicated in acute liver injury and in the pathogenesis of prevalent infectious or metabolic chronic liver diseases such as viral hepatitis B or C, alcoholic fatty liver disease, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Moreover, oxidative stress plays a crucial role in liver disease progression to liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Herein, we provide an overview on the effects of oxidative stress on liver pathophysiology and the mechanisms by which oxidative stress promotes liver disease.