Metabolic and hepatic effects of bloodletting in dysmetabolic iron overload syndrome: A randomized controlled study in 274 patients

Eicosanoids and Oxylipin Signature in Hereditary Hemochromatosis Patients Are Similar to Dysmetabolic Iron Overload Syndrome Patients but Are Impacted by Dietary Iron Absorption

INTRODUCTION

Oxylipins are mediators of oxidative stress. To characterize the underlying inflammatory processes and phenotype effect of iron metabolism disorders, we investigated the oxylipin profile in hereditary hemochromatosis (HH) and dysmetabolic iron overload syndrome (DIOS) patients.

METHODS

An LC-MS/MS-based method was performed to quantify plasma oxylipins in 20 HH and 20 DIOS patients in fasting conditions and 3 h after an iron-rich meal in HH patients.

RESULTS

Principal component analysis showed no separation between HH and DIOS, suggesting that the clinical phenotype has no direct impact on oxylipin metabolism. 20-HETE was higher in DIOS and correlated with hypertension (p = 0.03). Different oxylipin signatures were observed in HH before and after the iron-rich meal. Discriminant oxylipins include epoxy fatty acids derived from docosahexaenoic acid and arachidonic acid as well as 13-HODE and 9-HODE. Mediation analysis found no major contribution of dietary iron absorption for 16/22 oxylipins significantly affected by the meal.

DISCUSSION

The oxylipin profiles of HH and DIOS seemed similar except for 20-HETE, possibly reflecting different hypertension prevalence between the two groups. Oxylipins were significantly affected by the iron-rich meal, but the specific contribution of iron was not clear. Although iron may contribute to oxidative stress and inflammation in HH and DIOS, this does not seem to directly affect oxylipin metabolism.

The iron matters: Aged microplastics disrupted the iron homeostasis in the liver organoids

Plastic products undergo artificial and unintentional aging during daily use, causing the presence of aged microplastics (aMP). Humans are inevitably exposed to aMP. Liver is one of the critical target organs of MP through oral intake, however, limited research has focused on the hepatic toxicity of aMP compared to pristine MP (pMP). We utilized the human pluripotent stem cells-derived liver organoids (LOs) to compare the cytotoxicity of pristine polystyrene microplastics (pPS) (1 μm, carbonyl index 0.08) and aged polystyrene microplastics (aPS) (1 μm, carbonyl index 0.20) ranged from 20 to 200 ng/mL. Our findings indicate that aPS was more cytotoxic than pPS. We explored the disrupted iron homeostasis in terms of the [Fe2+] and [Fe3+] levels, iron storage and transport. A "vector-like effect" induced by aPS has been preliminarily suggested by the correlated change in total iron level and co-localization of PS and ferritin light chain (FTL) in the LOs following exposure to aPS and ferric ammonium citrate (FAC) individually and combinedly. In addition, we observed abnormal mitochondrial morphology, elevated lipid peroxidation, and declined GSH peroxidase activity, together with the declined expression of transferrin receptor (TFRC) and elevated expressions of SLC7A11, FTL. The gene handled iron transport and iron use were disrupted by aPS. Moreover, we employed FAC to introduce iron overload and Nacetylcysteine (NAC) to protect the lipid peroxidation. In aPS + FAC group, aggravated effects could be observed in aspects of [Fe2+] level, lipid peroxidation, and compromised expression levels of iron homeostasis-related markers, in contrast, in aPS + NAC group, most of changes recovered but the hepatocytoxicity remained. Specifically, a dimorphic change in elevated FTL and decreased ferritin heavy chain (FTH1) caused by 50 ng/mL aMP (57.33 ± 3.57 items/mL, equivalent to human intake level), indicated a specific response to low-dose aMP.

[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.

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.

Iron as a therapeutic target in chronic liver disease

It was clearly realized more than 50 years ago that iron deposition in the liver may be a critical factor in the development and progression of liver disease. The recent clarification of ferroptosis as a specific form of regulated hepatocyte death different from apoptosis and the description of ferritinophagy as a specific variation of autophagy prompted detailed investigations on the association of iron and the liver. In this review, we will present a brief discussion of iron absorption and handling by the liver with emphasis on the role of liver macrophages and the significance of the iron regulators hepcidin, transferrin, and ferritin in iron homeostasis. The regulation of ferroptosis by endogenous and exogenous mod-ulators will be examined. Furthermore, the involvement of iron and ferroptosis in various liver diseases including alcoholic and non-alcoholic liver disease, chronic hepatitis B and C, liver fibrosis, and hepatocellular carcinoma (HCC) will be analyzed. Finally, experimental and clinical results following interventions to reduce iron deposition and the promising manipulation of ferroptosis will be presented. Most liver diseases will be benefited by ferroptosis inhibition using exogenous inhibitors with the notable exception of HCC, where induction of ferroptosis is the desired effect. Current evidence mostly stems from in vitro and in vivo experimental studies and the need for well-designed future clinical trials is warranted.

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.

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.

Assessment of plasma catecholamines in patients with dysmetabolic iron overload syndrome

BACKGROUND

Dysmetabolic iron overload syndrome (DIOS) is characterized by hyperferritinemia and normal transferrin saturation level with components of metabolic syndrome (MS). Among cases of MS, we determined those with DIOS and their characterizations, then we evaluated the association between plasma catecholamines status and hypertension in DIOS.

METHODS

We compared 101 hypertensive patients with 50 healthy participants (control group). Iron (iron, transferrin, and ferritin), insulin, and plasma catecholamine (adrenaline, noradrenaline, and dopamine), profiles were measured for both groups. Homeostasis model assessment of insulin resistance index and transferrin saturation were also calculated.

RESULTS

Out of 101 hypertensive patients, 64 were diagnosed with MS, and 6 of the latter met the DIOS diagnostic criteria. Significantly, DIOS patients were older and had lower body mass index (BMI) compared with hypertensive non-DIOS patients with p-values of (0.026), and (0.033), respectively. Adrenaline, noradrenaline, and dopamine levels did not differ significantly between DIOS and non-DIOS patients.

CONCLUSIONS

Of the MS patients, 9.3% were diagnosed with DIOS. Accordingly, complete iron profiling should be performed routinely in the cases of MS for early diagnosis of DIOS, to prevent future complications. Further studies are required to test the hypothesis linking older age and lower BMI with the pathogenesis of DIOS.

Causal relationships between metabolic-associated fatty liver disease and iron status: Two-sample Mendelian randomization

BACKGROUND & AIMS

Dysregulated iron homeostasis plays an important role in the hepatic manifestation of metabolic-associated fatty liver disease (MAFLD). We investigated the causal effects of five iron metabolism markers, regular iron supplementation and MAFLD risk.

METHODS

Genetic summary statistics were obtained from open genome-wide association study databases. Two-sample bidirectional Mendelian randomization analysis was performed to estimate the causal effect between iron status and MAFLD, including Mendelian randomization inverse-variance weighted, weighted median methods and Mendelian randomization-Egger regression. The Mendelian randomization-PRESSO outlier test, Cochran's Q test and Mendelian randomization-Egger regression were used to assess outliers, heterogeneity and pleiotropy respectively.

RESULTS

Mendelian randomization inverse-variance weighted results showed that the genetically predicted per standard deviation increase in liver iron (Data set 2: odds ratio 1.193, 95% confidence interval [CI] 1.074-1.326, p = .001) was associated with an increased MAFLD risk, consistent with the weighted median estimates and Mendelian randomization-Egger regression, although Data set 1 was not significant. Mendelian randomization inverse-variance weighted analysis showed that genetically predicted MAFLD was significantly associated with increased serum ferritin levels in both datasets (Dataset 1: β = .038, 95% CI = .014 to .062, p = .002; Dataset 2: β = .081, 95% CI = .025 to .136, p = .004), and a similar result was observed with the weighted median methods for Dataset 2 instead of Mendelian randomization-Egger regression.

CONCLUSIONS

This study uncovered genetically predicted causal associations between iron metabolism status and MAFLD. These findings underscore the need for improved guidelines for managing MAFLD risk by emphasizing hepatic iron levels as a risk factor and ferritin levels as a prognostic factor.

A critical evaluation of the role of iron overload in fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has been associated with a condition known as the dysmetabolic iron overload syndrome, but the frequency and severity of iron overload in NAFLD is not well described. There is emerging evidence that mild to moderate excess hepatic iron can aggravate the risk of progression of NAFLD to nonalcoholic steatohepatitis and eventually cirrhosis. Mechanisms are postulated to be via reactive oxygen species, inflammatory cytokines, lipid oxidation, and oxidative stress. The aim of this review is to assess the evidence for true hepatic iron overload in NAFLD, to discuss the pathogenesis by which excess iron may be toxic, and to critically evaluate the studies designed to deplete iron by regular venesection. In brief, the studies are inconclusive due to heterogeneity in eligibility criteria, sample size, randomization, hepatic iron measurement, serial histological endpoints, target ferritin levels, length of venesection, and degree of confounding lifestyle intervention. We propose a trial designed to overcome the limitations of these studies.

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.

Effect of acute iron infusion on insulin secretion: A randomized, double-blind, placebo-controlled trial

Background

Chronic exposure to high iron levels increases diabetes risk partly by inducing oxidative stress, but the consequences of acute iron administration on beta cells are unknown. We tested whether the acute administration of iron for the correction of iron deficiency influenced insulin secretion and the production of reactive oxygen species.

Methods

Single-center, double-blinded, randomized controlled trial conducted between June 2017 and March 2020. 32 women aged 18 to 47 years, displaying symptomatic iron deficiency without anaemia, were recruited from a community setting and randomly allocated (1:1) to a single infusion of 1000 mg intravenous ferric carboxymaltose (iron) or saline (placebo). The primary outcome was the between group mean difference from baseline to day 28 in first and second phase insulin secretion, assessed by a two-step hyperglycaemic clamp. All analyses were performed by intention to treat. This trial was registered in ClinicalTrials.gov NCT03191201.

Findings

Iron infusion did not affect first and second phase insulin release. For first phase, the between group mean difference from baseline to day 28 was 0 μU × 10 min/mL [95% CI, -22 to 22, P = 0.99]. For second phase, it was -5 μUx10min/mL [95% CI, -161 to 151; P = 0.95] at the first plateau of the clamp and -249 μUx10min/mL [95% CI, -635 to 137; P = 0.20] at the second plateau. Iron infusion increased serum ascorbyl/ascorbate ratio, a marker of plasma oxidative stress, at day 14, with restoration of normal ratio at day 28 relative to placebo. Finally, high-sensitive C-reactive protein levels remained similar among groups.

Interpretation

In iron deficient women without anaemia, intravenous administration of 1000 mg of iron in a single sitting did not impair glucose-induced insulin secretion despite a transient increase in the levels of circulating reactive oxygen species.

Funding

The Swiss National Science Foundation, University of Lausanne and Leenaards, Raymond-Berger and Placide Nicod Foundations.

Prevalence of HFE-related haemochromatosis and secondary causes of hyperferritinaemia and their association with iron overload in 1059 French patients treated by venesection

BACKGROUND

Venesection is the key therapy in haemochromatosis, but it remains controversial in hyperferritinaemia with moderate iron accumulation. There is substantial evidence that the results of HFE genotyping are routinely misinterpreted, while elevated serum ferritin has become more frequent in recent years in white adult populations following the increase of obesity and metabolic traits.

AIMS

To examine the reasons for prescribing venesection in 1,059 French patients during the period 2012-2015, determine the true prevalence of HFE-related haemochromatosis, and compare iron overload profiles between haemochromatosis and non-haemochromatosis patients.

RESULTS

Only 258 of the 488 patients referred for haemochromatosis had the p.[Cys282Tyr];[Cys282Tyr] disease causative genotype (adjusted prevalence: 24.4%). Of the 801 remaining patients, 112 (14.0%) had the debated p.[Cys282Tyr];[His63Asp] compound heterozygote genotype, 643 (80.3%) had central obesity, 475 (59.3%) had metabolic syndrome (MetS) and 93 (11.6%) were heavy drinkers. The non-haemochromatosis patients started therapeutic venesection 9 years later than haemochromatosis patients (P < 0.001). Despite similar serum ferritin values, they had lower transferrin saturation (41.1% vs 74.3%; P < 0.001), lower amounts of iron removed by venesection (1.7 vs 3.2 g; P < 0.001) and lower hepatic iron concentrations (107 vs 237 µmol/g; P < 0.001).

CONCLUSIONS

Haemochromatosis is over-diagnosed and is no longer the main reason for therapeutic venesection in France. Obesity and other metabolic abnormalities are frequently associated with mild elevation of serum ferritin, the MetS is confirmed in ~50% of treated patients. There is a minimal relationship between serum ferritin and iron overload in non-p.Cys282Tyr homozygotes. Our observations raise questions about venesection indications in non-haemochromatosis patients.

A Pilot Study on the Prevalence of Micronutrient Imbalances in a Dutch General Population Cohort and the Effects of a Digital Lifestyle Program

Maintaining an adequate micronutrient status can be achieved by following a complete, diverse diet. Yet, food trends in Western countries show suboptimal consumption of healthy nutrients. In this study, we explored the prevalence of vitamin and mineral imbalances in a general population cohort of Dutch adults and evaluated the effect of a digital lifestyle program on the nutritional status and nutrition health behaviors of these individuals. A micronutrient panel was measured in 348 participants, alongside a dietary assessment. One hundred users subsequently underwent a remeasurement. We identified at least one nutritional imbalance in 301 individuals (86.5%). A total of 80% improved and normalized B6, 67% improved folate, 70% improved B12, and 86% improved vitamin D. Iron abnormalities were corrected in 75% of the participants. In conclusion, this study found that micronutrient deficiencies of easily obtainable vitamins through diet or supplementation such as B vitamins and vitamin D were more prevalent than expected in a Dutch population. This can partly be explained by insufficient consumption of food groups rich in B vitamins. Our preliminary results in those remeasured after a digitally enabled lifestyle intervention show these imbalances can be corrected with adequate behavioral support complemented with supplementation where needed.

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.

MRI-Based Iron Phenotyping and Patient Selection for Next-Generation Sequencing of Non-Homeostatic Iron Regulator Hemochromatosis Genes

BACKGROUND AND AIMS

High serum ferritin is frequent among patients with chronic liver disease and commonly associated with hepatic iron overload. Genetic causes of high liver iron include homozygosity for the p.Cys282Tyr variant in homeostatic iron regulator (HFE) and rare variants in non-HFE genes. The aims of the present study were to describe the landscape and frequency of mutations in hemochromatosis genes and determine whether patient selection by noninvasive hepatic iron quantification using MRI improves the diagnostic yield of next-generation sequencing (NGS) in patients with hyperferritinemia.

APPROACH AND RESULTS

A cohort of 410 unselected liver clinic patients with high serum ferritin (defined as ≥200 μg/L for women and ≥300 μg/L for men) was investigated by HFE genotyping and abdominal MRI R2*. Forty-one (10%) patients were homozygous for the p.Cys282Tyr variant in HFE. Of the remaining 369 patients, 256 (69%) had high transferrin saturation (TSAT; ≥45%) and 199 (53%) had confirmed hepatic iron overload (liver R2* ≥70 s^-1 ). NGS of hemochromatosis genes was carried out in 180 patients with hepatic iron overload, and likely pathogenic variants were identified in 68 of 180 (38%) patients, mainly in HFE (79%), ceruloplasmin (25%), and transferrin receptor 2 (19%). Low spleen iron (R2* <50 s^-1 ), but not TSAT, was significantly associated with the presence of mutations. In 167 patients (93%), no monogenic cause of hepatic iron overload could be identified.

CONCLUSIONS

In patients without homozygosity for p.Cys282Tyr, coincident pathogenic variants in HFE and non-HFE genes could explain hyperferritinemia with hepatic iron overload in a subset of patients. Unlike HFE hemochromatosis, this type of polygenic hepatic iron overload presents with variable TSAT. High ferritin in blood is an indicator of the iron storage disease, hemochromatosis. A simple genetic test establishes this diagnosis in the majority of patients affected. MRI of the abdomen can guide further genetic testing.

Lactobacillus casei relieves liver injury by regulating immunity and suppression of the enterogenic endotoxin-induced inflammatory response in rats cotreated with alcohol and iron

Excessive alcohol and iron intake can reportedly cause liver damage. In the present study, we investigated the effect of Lactobacillus casei on liver injury in rats co-exposed to alcohol and iron and evaluated its possible mechanism. Sixty male Wistar rats were randomly divided into three groups for 12 weeks: the Control group (administered normal saline by gavage and provided a normal diet); alcohol +iron group (Model group, treated with alcohol [3.5-5.3 g/kg/day] by gavage and dietary iron [1,500 mg/kg]); Model group supplemented with L. casei (8 × 108 CFU kg-1 day-1) (L. casei group). Using hematoxylin and eosin (HE) staining and transmission electron microscopy, we observed that L. casei supplementation could alleviate disorders associated with lipid metabolism, inflammation, and intestinal mucosal barrier injury. Moreover, levels of serum alanine aminotransferase, gamma-glutamyl transferase, triglyceride (TG), and hepatic TG were significantly increased in the model group; however, these levels were significantly decreased following the 12-week L. casei supplementation. In addition, we observed notable improvements in intestinal mucosal barrier function and alterations in T lymphocyte subsets and natural killer cells in L. casei-treated rats when compared with the model group. Furthermore, L. casei intervention alleviated serum levels of tumor necrosis factor-α and interleukin-1β, accompanied by decreased serum endotoxin levels and downregulated expression of toll-like receptor 4 and its related molecules MyD88, nuclear factor kappa-B p65, and TNF-α. Accordingly, supplementation with L. casei could effectively improve liver injury induced by the synergistic interaction between alcohol and iron. The underlying mechanism for this improvement may be related to immune regulation and inhibition of enterogenic endotoxin-mediated inflammation.

Does iron overload in metabolic syndrome affect macrophage profile? A case control study

AIMS

Dysmetabolic iron overload syndrome (DIOS) is common but the clinical relevance of iron overload is not understood. Macrophages are central cells in iron homeostasis and inflammation. We hypothesized that iron overload in DIOS could affect the phenotype of monocytes and impair macrophage gene expression.

METHODS

This study compared 20 subjects with DIOS to 20 subjects with metabolic syndrome (MetS) without iron overload, and 20 healthy controls. Monocytes were phenotyped by Fluorescence-Activated Cell Sorting (FACS) and differentiated into anti-inflammatory M2 macrophages in the presence of IL-4. The expression of 38 genes related to inflammation, iron metabolism and M2 phenotype was assessed by real-time PCR.

RESULTS

FACS showed no difference between monocytes across the three groups. The macrophagic response to IL-4-driven differentiation was altered in four of the five genes of M2 phenotype (MRC1, F13A1, ABCA1, TGM2 but not FABP4), in DIOS vs Mets and controls demonstrating an impaired M2 polarization. The expression profile of inflammatory genes was not different in DIOS vs MetS. Several genes of iron metabolism presented a higher expression in DIOS vs MetS: SCL11A2 (a free iron transporter, +76 %, p = 0.04), SOD1 (an antioxidant enzyme, +27 %, p = 0.02), and TFRC (the receptor 1 of transferrin, +59 %, p = 0.003).

CONCLUSIONS

In DIOS, macrophage polarization toward the M2 alternative phenotype is impaired but not associated with a pro-inflammatory profile. The up regulation of transferrin receptor 1 (TFRC) in DIOS macrophages suggests an adaptive role that may limit iron toxicity in DIOS.

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 depletion attenuates steatosis in a mouse model of non-alcoholic fatty liver disease: Role of iron-dependent pathways

BACKGROUND & AIMS

Iron has been proposed as influencing the progression of liver disease in subjects with non-alcoholic fatty liver disease (NAFLD). We have previously shown that, in the Hfe^-/- mouse model of hemochromatosis, feeding of a high-calorie diet (HCD) leads to increased liver injury. In this study we investigated whether the feeding of an iron deficient/HCD to Hfe^-/- mice influenced the development of NAFLD.

METHODS

Liver histology was assessed in Hfe^-/- mice fed a standard iron-containing or iron-deficient diet plus or minus a HCD. Hepatic iron concentration, serum transferrin saturation and free fatty acid were measured. Expression of genes implicated in iron regulation and fatty liver disease was determined by quantitative real-time PCR (qRT-PCR).

RESULTS

Standard iron/HCD-fed mice developed severe steatosis whereas NAS score was reduced in mice fed iron-deficient HCD. Mice fed iron-deficient HCD had lower liver weights, lower transferrin saturation and decreased ferroportin and hepcidin gene expression than HCD-fed mice. Serum non-esterified fatty acids were increased in iron-deficient HCD-fed mice compared with standard iron HCD. Expression analysis indicated that genes involved in fatty-acid binding and mTOR pathways were regulated by iron depletion.

CONCLUSIONS

Our results indicate that decreasing iron intake attenuates the development of steatosis resulting from a high calorie diet. These results also suggest that human studies of agents that modify iron balance in patients with NAFLD should be revisited.

Fat and Iron Don't Mix

Low-grade chronic adipose tissue (AT) inflammation is now recognized as a pivotal driver of the multi-organ dysfunction associated with obesity-related complications; and adipose tissue macrophages (ATMs) are key to the development of this inflammatory milieu. Along with their role in immunosurveillance, ATMs are central regulators of AT iron homeostasis. Under optimal conditions, ATMs maintain a proper homeostatic balance of iron in adipocytes; however, during obesity, this relationship is altered, and iron is repartitioned into adipocytes as opposed to ATMs. This adipocyte iron overload leads to systemic IR and the mechanism for these effects is still under investigation. Here, we comment on the most recent findings addressing the interplay between adipocyte and ATM iron handling, and metabolic dysfunction.

Relationship between iron status markers and insulin resistance: an exploratory study in subjects with excess body weight

Background

Controversy exists on the relationship between iron metabolism and cardiometabolic risk. The aim of this study was to determine if there is a link between dysmetabolic iron and cardiometabolic markers in subjects with excess body weight.

Methods

Cross-sectional study with fifty participants presenting overweight or obesity and at least another metabolic syndrome factor. Determinations: anthropometry, body composition, blood pressure, lipids, glucose, insulin, leptin, areas under the curve (AUC) for glucose and insulin after an oral glucose tolerance test, hs-C reactive protein (hs-CRP), blood count, ferritin, transferrin, transferrin saturation (TSAT), soluble transferrin receptor (sTfR). Gender-adjusted linear correlations and two independent samples t tests were used.

Results

Ferritin was positively correlated with insulin-AUC (r = 0.547, p = 0.008) and TSAT was negatively correlated with waist-hip ratio (r =  − 0.385, p = 0.008), insulin (r =  − 0.551, p < 0.001), and insulin resistance (HOMA-IR, r =  − 0.586, p < 0.001). Subjects with TSAT ≤ 20% had higher insulin (p = 0.012) and HOMA-IR (p = 0.003) compared to those with TSAT > 20%. In conclusion, the observed results suggest that iron transport and storage are altered in subjects with overweight/obesity, at the same time that they exhibit the characteristic features of insulin resistance. Nevertheless, this occurs without iron overload or deficiency. These results should be validated in wider cohorts since they suggest that iron transport and storage should be assessed when performing the clinical evaluation of subjects with excess body weight.

Liver iron concentration in dysmetabolic hyperferritinemia: Results from a prospective cohort of 276 patients

INTRODUCTION AND OBJECTIVES

We aimed to study the liver iron concentration in patients referred for hyperferritinemia to six hospitals in the Basque Country and to determine if there were differences between patients with or without metabolic syndrome.

PATIENTS AND METHODS

Metabolic syndrome was defined by accepted criteria. Liver iron concentration was determined by magnetic resonance imaging.

RESULTS

We obtained the data needed to diagnose metabolic syndrome in 276 patients; a total of 135 patients (49%), 115/240 men (48%), and 20/36 women (55.6%) presented metabolic syndrome. In all 276 patients, an MRI for the determination of liver iron concentration (mean±SD) was performed. The mean liver iron concentration was 30.83±19.38 for women with metabolic syndrome, 38.84±25.50 for men with metabolic syndrome, and 37.66±24.79 (CI 95%; 33.44-41.88) for the whole metabolic syndrome group. In 141 patients (51%), metabolic syndrome was not diagnosed: 125/240 were men (52%) and 16/36 were women (44.4%). The mean liver iron concentration was 34.88±16.18 for women without metabolic syndrome, 44.48±38.16 for men without metabolic syndrome, and 43.39±36.43 (CI 95%, 37.32-49.46) for the whole non-metabolic syndrome group. Comparison of the mean liver iron concentration from both groups (metabolic syndrome vs non-metabolic syndrome) revealed no significant differences (p=0.12).

CONCLUSIONS

Patients with hyperferritinemia and metabolic syndrome presented a mildly increased mean liver iron concentration that was not significantly different to that of patients with hyperferritinemia and non-metabolic syndrome.

A Low Iron Diet Protects from Steatohepatitis in a Mouse Model

High tissue iron levels are a risk factor for multiple chronic diseases including type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD). To investigate causal relationships and underlying mechanisms, we used an established NAFLD model-mice fed a high fat diet with supplemental fructose in the water ("fast food", FF). Iron did not affect excess hepatic triglyceride accumulation in the mice on FF, and FF did not affect iron accumulation compared to normal chow. Mice on low iron are protected from worsening of markers for non-alcoholic steatohepatitis (NASH), including serum transaminases and fibrotic gene transcript levels. These occurred prior to the onset of significant insulin resistance or changes in adipokines. Transcriptome sequencing revealed the major effects of iron to be on signaling by the transforming growth factor beta (TGF-β) pathway, a known mechanistic factor in NASH. High iron increased fibrotic gene expression in vitro, demonstrating that the effect of dietary iron on NASH is direct. Conclusion: A lower tissue iron level prevents accelerated progression of NAFLD to NASH, suggesting a possible therapeutic strategy in humans with the disease.

Evaluating the association of serum ferritin and hepatic iron with disease severity in non-alcoholic fatty liver disease

BACKGROUND & AIMS

Hyperferritinemia, with or without increased hepatic iron, represents a common finding in non-alcoholic fatty liver disease (NAFLD). However, it is unclear whether it reflects hepatic inflammation or true iron-overload and, in case the latter is confirmed, whether this influences disease progression. We therefore explored the association between serum ferritin, degree and pattern of hepatic iron deposition and liver disease severity in patients with NAFLD.

METHODS

We selected 468 patients with biopsy-proven NAFLD from 2 European centres. Iron, hepatic and metabolic parameters were collected at the time of liver biopsy. Iron deposits in hepatocytes and reticuloendothelial cells were assessed and graded. Diagnosis of non-alcoholic steatohepatitis (NASH) and fibrosis staging were performed.

RESULTS

A total of 122 (26%) patients had hyperferritinemia, whereas stainable hepatic iron was found in 116 (25%) patients (38% predominantly in hepatocytes, 20% in reticuloendothelial cells and 42% in both). Subjects with stainable hepatic iron, particularly those with a mixed pattern, had higher serum ferritin and transaminases but only a mixed pattern of iron deposition was among the variables significantly associated with presence of NASH. Serum ferritin was not associated with presence of NASH, however it increased with worsening fibrosis stage (F3 compared to F0-F1), and significantly decreased in stage F4.

CONCLUSIONS

A mixed pattern of hepatic iron deposition is associated with the presence of steatohepatitis, while serum ferritin increases with worsening fibrosis up to pre-cirrhotic stage. In individual NAFLD patients, serum ferritin could be evaluated as part of non-invasive diagnostic panels but not on its own.

Effect of procyanidin on dietary iron absorption in hereditary hemochromatosis and in dysmetabolic iron overload syndrome: A crossover double-blind randomized controlled trial

BACKGROUND & AIMS

Type I hereditary hemochromatosis (HH) and dysmetabolic iron overload syndrome (DIOS) are the two most prevalent iron overload diseases. Although many food components, particularly polyphenols, reduce iron bioavailability, there is no clinically validated nutritional strategy to reduce food-iron absorption in patients with these diseases. We aimed to determine whether supplementation with 100 mg of procyanidins during a meal reduces dietary iron absorption in patients with HH or DIOS.

METHODS

20 HH and 20 DIOS patients were enrolled in a double-blind three-period crossover randomized study. Basal serum iron level was measured following an overnight fast. Each patient consumed a standardized test iron-rich meal containing 43 mg of iron with two capsules of placebo or procyanidin supplementation. Each period was separated by a 3-day wash-out period. The primary objective was a reduction of dietary iron absorption, assessed by a reduction of serum-iron area under the curve (AUC) corrected for baseline serum iron.

RESULTS

All patients completed the study. The meal and the procyanidin supplements were well tolerated. In both HH and DIOS patients, the iron-rich meal induced a significant increase of serum iron compared with baseline at 120, 180, 240 min, from 8 to 9.1% (p = 0.002, 0.001 and 0.003, respectively) in DIOS and from 15.8 to 25.7% (p < 0.001) in HH. Iron absorption was 3.5-fold higher in HH than in DIOS (p < 0.001). Procyanidin supplementation did not significantly modify iron absorption in DIOS (AUC of added iron 332.87 ± 649.55 vs 312.61 ± 678.61 μmol.h/L, p = 0.916) or in HH (1168.62 ± 652.87 vs 1148.54 μmol.h/L ± 1290.05, p = 0.917).

CONCLUSIONS

An iron-rich test meal led to a marked increase in iron absorption in HH but a mild increase in DIOS. Procyanidin supplementation does not significantly reduce dietary iron absorption in either disease. CLINICAL TRIAL REGISTRY: clinicaltrials.gov (NCT03453918).

Iron and liver fibrosis: Mechanistic and clinical aspects

Liver fibrosis is characterised by excessive deposition of extracellular matrix that interrupts normal liver functionality. It is a pathological stage in several untreated chronic liver diseases such as the iron overload syndrome hereditary haemochromatosis, viral hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis and diabetes. Interestingly, regardless of the aetiology, iron-loading is frequently observed in chronic liver diseases. Excess iron can feed the Fenton reaction to generate unquenchable amounts of free radicals that cause grave cellular and tissue damage and thereby contribute to fibrosis. Moreover, excess iron can induce fibrosis-promoting signals in the parenchymal and non-parenchymal cells, which accelerate disease progression and exacerbate liver pathology. Fibrosis regression is achievable following treatment, but if untreated or unsuccessful, it can progress to the irreversible cirrhotic stage leading to organ failure and hepatocellular carcinoma, where resection or transplantation remain the only curative options. Therefore, understanding the role of iron in liver fibrosis is extremely essential as it can help in formulating iron-related diagnostic, prognostic and treatment strategies. These can be implemented in isolation or in combination with the current approaches to prepone detection, and halt or decelerate fibrosis progression before it reaches the irreparable stage. Thus, this review narrates the role of iron in liver fibrosis. It examines the underlying mechanisms by which excess iron can facilitate fibrotic responses. It describes the role of iron in various clinical pathologies and lastly, highlights the significance and potential of iron-related proteins in the diagnosis and therapeutics of liver fibrosis.

Hemochromatosis: pathophysiology, evaluation, and management of hepatic iron overload with a focus on MRI

Hereditary hemochromatosis (HH) is an autosomal recessive disorder that occurs in approximately 1 in 200-250 individuals. Mutations in the HFE gene lead to excess iron absorption. Excess iron in the form of non-transferrin-bound iron (NTBI) causes injury and is readily uptaken by cardiomyocytes, pancreatic islet cells, and hepatocytes. Symptoms greatly vary among patients and include fatigue, abdominal pain, arthralgias, impotence, decreased libido, diabetes, and heart failure. Untreated hemochromatosis can lead to chronic liver disease, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Many invasive and noninvasive diagnostic tests are available to aid in diagnosis and treatment. MRI has emerged as the reference standard imaging modality for the detection and quantification of hepatic iron deposition, as ultrasound (US) is unable to detect iron overload and computed tomography (CT) findings are nonspecific and influenced by multiple confounding variables. If caught and treated early, HH disease progression can significantly be altered. Area covered: The data on Hemochromatosis, iron overload, and MRI were gathered by searching PubMed. Expert commentary: MRI is a great tool for diagnosis and management of iron overload. It is safe, effective, and a standard protocol should be included in diagnostic algorithms of future treatment guidelines.

Hepatic iron concentration correlates with insulin sensitivity in nonalcoholic fatty liver disease

Rodent and cell‐culture models support a role for iron‐related adipokine dysregulation and insulin resistance in the pathogenesis of nonalcoholic fatty liver disease (NAFLD); however, substantial human data are lacking. We examined the relationship between measures of iron status, adipokines, and insulin resistance in patients with NAFLD in the presence and absence of venesection. This study forms part of the Impact of Iron on Insulin Resistance and Liver Histology in Nonalcoholic Steatohepatitis (IIRON2) study, a prospective randomized controlled trial of venesection for adults with NAFLD. Paired serum samples at baseline and 6 months (end of treatment) in controls (n = 28) and patients who had venesection (n = 23) were assayed for adiponectin, leptin, resistin, retinol binding protein‐4, tumor necrosis factor α, and interleukin‐6, using a Quantibody, customized, multiplexed enzyme‐linked immunosorbent assay array. Hepatic iron concentration (HIC) was determined using MR FerriScan. Unexpectedly, analysis revealed a significant positive correlation between baseline serum adiponectin concentration and HIC, which strengthened after correction for age, sex, and body mass index (rho = 0.36; P = 0.007). In addition, there were significant inverse correlations between HIC and measures of insulin resistance (adipose tissue insulin resistance (Adipo‐IR), serum insulin, serum glucose, homeostasis model assessment of insulin resistance, hemoglobin A1c, and hepatic steatosis), whereas a positive correlation was noted with the insulin sensitivity index. Changes in serum adipokines over 6 months did not differ between the control and venesection groups. Conclusion: HIC positively correlates with serum adiponectin and insulin sensitivity in patients with NAFLD. Further study is required to establish causality and mechanistic explanations for these associations and their relevance in the pathogenesis of insulin resistance and NAFLD. (Hepatology Communications 2018;2:644‐653)

Systematic review and meta-analysis to determine the impact of iron depletion in dysmetabolic iron overload syndrome and non-alcoholic fatty liver disease

AIMS

Iron reduction has been proposed as treatment for dysmetabolic iron overload syndrome (DIOS) and non-alcoholic fatty liver disease (NAFLD), but results of published trials are conflicting. We undertook a systematic review and meta-analysis to determine the impact of phlebotomy in DIOS and NAFLD.

METHODS

We searched multiple databases systematically for studies evaluating the impact of phlebotomy in DIOS and NAFLD. We calculated weighted summary estimates using the inverse variance method. Study quality was assessed using the Cochrane collaboration tool.

RESULTS

We identified nine studies with 820 patients (427 had phlebotomy, 393 lifestyle changes alone). Iron depletion did not improve the Homeostasis Model Assessment (HOMA) index (mean difference [MD] -0.6; confidence interval (CI), -1.7, 0.5; P = 0.3), insulin level (MD -0.8 mU/L; CI, -5.3, 3.7; P = 0.73), or aspartate aminotransferase (AST) (MD -0.7 IU/L; CI, -3.2, 1.8; P = 0.6) in DIOS and/or NAFLD patients as compared to lifestyle changes alone (five studies, 626 patients). There was mild improvement in alanine aminotransferase (ALT) (MD -6.6 IU/L; CI, -11, -2.1); P < 0.01), but the effect size was very small (Cohen's d, 0.15; r statistic, 0.07). Even in the subgroup of patients with NAFLD and hyperferritinemia, phlebotomy did not improve the HOMA index, insulin level, ALT, or AST. Additionally, no study showed significant improvement in liver inflammation or fibrosis with iron reduction.

CONCLUSIONS

Phlebotomy does not bring about significant improvement in indices of insulin resistance, liver enzymes, or liver histology in patients with DIOS and/or NAFLD compared to lifestyle changes alone. Current evidence does not support the use of phlebotomy in patients with DIOS or NAFLD.

FOXO1/3: Potential suppressors of fibrosis

Fibrosis is a universally age-related disease that involves nearly all organs. It is typically initiated by organic injury and eventually results in organ failure. There are still few effective therapeutic strategy targets for fibrogenesis. Forkhead box proteins O1 and O3 (FOXO1/3) have been shown to have favorable inhibitory effects on fibroblast activation and subsequent extracellular matrix production and can ameliorate fibrosis levels in numerous organs, including the heart, liver, lung, and kidney; they are therefore promising targets for anti-fibrosis therapy. Moreover, we can develop appropriate strategies to make the best use of FOXO1/3's anti-fibrosis properties. The information reviewed here should be significant for understanding the roles of FOXO1/3 in fibrosis and should contribute to the design of further studies related to FOXO1/3 and the fibrotic response and shed light on a potential treatment for fibrosis.

Hepatic iron is the major determinant of serum ferritin in NAFLD patients

BACKGROUND AND AIMS

Elevated serum ferritin is common in NAFLD, and is associated with more advanced disease and increased mortality. Hyperferritinaemia in NAFLD is often attributed to inflammation, while in other conditions ferritin closely reflects body iron stores. The aim of this study was to clarify the underlying cause of hyperferritinaemia in NAFLD.

METHODS

Ferritin levels were examined with markers of iron status, inflammation and liver injury across the clinical spectrum of NAFLD using blood, tissue and magnetic resonance (MR) imaging. A separate larger group of NAFLD patients with hepatic iron staining and quantification were used for validation.

RESULTS

Serum ferritin correlated closely with the iron regulatory hormone hepcidin, and liver iron levels determined by MR. Furthermore, ferritin levels reflected lower serum adiponectin, a marker of insulin resistance, and liver fat, but not cytokine or CRP levels. Ferritin levels differed according to fibrosis stage, increasing from early to moderate disease, and declining in cirrhosis. A similar pattern was found in the validation cohort of NAFLD patients, where ferritin levels were highest in those with macrophage iron deposition. Multivariate analysis revealed liver iron and hepcidin levels as the major determinants of serum ferritin.

CONCLUSIONS

While hyperferritinaemia is associated with markers of liver injury and insulin resistance, serum hepcidin and hepatic iron are the strongest predictors of ferritin levels. These findings highlight the role of disordered iron homeostasis in the pathogenesis of NAFLD, suggesting that therapies aimed at correcting iron metabolism may be beneficial.