Dysregulation of iron and copper homeostasis in nonalcoholic fatty liver

Hepatocyte programmed cell death: the trigger for inflammation and fibrosis in metabolic dysfunction-associated steatohepatitis

By replacing and removing defective or infected cells, programmed cell death (PCD) contributes to homeostasis maintenance and body development, which is ubiquitously present in mammals and can occur at any time. Besides apoptosis, more novel modalities of PCD have been described recently, such as necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death. PCD not only regulates multiple physiological processes, but also participates in the pathogenesis of diverse disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is mainly classified into metabolic dysfunction-associated steatotic liver (MASL) and metabolic dysfunction-associated steatohepatitis (MASH), and the latter putatively progresses to cirrhosis and hepatocellular carcinoma. Owing to increased incidence and obscure etiology of MASH, its management still remains a tremendous challenge. Recently, hepatocyte PCD has been attracted much attention as a potent driver of the pathological progression from MASL to MASH, and some pharmacological agents have been proved to exert their salutary effects on MASH partly via the regulation of the activity of hepatocyte PCD. The current review recapitulates the pathogenesis of different modalities of PCD, clarifies the mechanisms underlying how metabolic disorders in MASLD induce hepatocyte PCD and how hepatocyte PCD contributes to inflammatory and fibrotic progression of MASH, discusses several signaling pathways in hepatocytes governing the execution of PCD, and summarizes some potential pharmacological agents for MASH treatment which exert their therapeutic effects partly via the regulation of hepatocyte PCD. These findings indicate that hepatocyte PCD putatively represents a new therapeutic point of intervention for MASH.

R2* Impact on Hepatic Fat Quantification With a Commercial Single Voxel Technique at 1.5 and 3.0 T

Rationale and Objectives: Fat quantification accuracy using a commercial single-voxel high speed T2-corrected multi-echo (HISTO) technique and its robustness to R2* variations at 3.0 T, such as those introduced by iron in liver, has not been fully established. This study evaluated HISTO at 3.0 T and sought to reproduce results at 1.5 T. Methods: Phantoms were prepared with a range of fat content and R2*. Data were acquired at 1.5 T and 3.0 T, using HISTO and a Dixon technique. Fat quantification accuracy was evaluated as a function of R2*. The patient study included 239 consecutive patients. Data were acquired at 1.5 T or 3.0 T, using HISTO and Dixon techniques. The techniques were compared using Bland-Altman plots. Bias significance was evaluated using a one-sample t-test. Results: In phantoms, HISTO was accurate within 10% up to a R2* of 100 s-1 at both field strengths, while Dixon was accurate within 10% where R2* was accurately quantified (up to 350 s-1 at 1.5 T, and 550 s-1 at 3.0 T). In patients, where R2* was <100 s-1, fat quantification from both techniques agreed at 1.5 T (P = .71), but not at 3.0 T (P = .007), with a bias <1%. Conclusion: Results suggest that HISTO is reliable when R2* is <100 s-1, corresponding to patients with at most mild liver iron overload, and that it should be used with caution when R2* is >100 s-1. Dixon should be preferred for hepatic fat quantification due to its robustness to R2* variations.

STEAP2 promotes hepatocellular carcinoma progression via increased copper levels and stress-activated MAP kinase activity

Six Transmembrane Epithelial Antigen of Prostate 2 (STEAP2) belongs to a family of metalloreductases, which indirectly aid in uptake of iron and copper ions. Its role in hepatocellular carcinoma (HCC) remains to be characterized. Here, we report that STEAP2 expression was upregulated in HCC tumors compared with paired adjacent non-tumor tissues by RNA sequencing, RT-qPCR, Western blotting, and immunostaining. Public HCC datasets demonstrated upregulated STEAP2 expression in HCC and positive association with tumor grade. Transient and stable knockdown (KD) of STEAP2 in HCC cell lines abrogated their malignant phenotypes in vitro and in vivo, while STEAP2 overexpression showed opposite effects. STEAP2 KD in HCC cells led to significant alteration of genes associated with extracellular matrix organization, cell adhesion/chemotaxis, negative enrichment of an invasiveness signature gene set, and inhibition of cell migration/invasion. STEAP2 KD reduced intracellular copper levels and activation of stress-activated MAP kinases including p38 and JNK. Treatment with copper rescued the reduced HCC cell migration due to STEAP2 KD and activated p38 and JNK. Furthermore, treatment with p38 or JNK inhibitors significantly inhibited copper-mediated cell migration. Thus, STEAP2 plays a malignant-promoting role in HCC cells by driving migration/invasion via increased copper levels and MAP kinase activities. Our study uncovered a novel molecular mechanism contributing to HCC malignancy and a potential therapeutic target for HCC treatment.

Iron metabolism and ferroptosis in nonalcoholic fatty liver disease: what is our next step?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease with increasing prevalence worldwide. NAFLD could develop from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), NASH-related fibrosis, cirrhosis, and even hepatocellular carcinoma. However, the mechanism of NAFLD development has not yet been fully defined. Recently, emerging evidence shows that the dysregulated iron metabolism marked by elevated serum ferritin, and ferroptosis are involved in the NAFLD. Understanding iron metabolism and ferroptosis can shed light on the mechanisms of NAFLD development. Here, we summarized studies on iron metabolism and the ferroptosis process involved in NAFLD development to highlight potential medications and therapies for treating NAFLD.

Erythropoietin hyporesponsiveness in non-alcoholic fatty liver disease

Treatment with erythropoietin (EPO) can correct anaemia in chronic kidney disease (CKD) patients; however, up to 10% exhibit resistance or hyporesponsiveness to EPO. Non-alcoholic fatty liver disease (NAFLD), prevalent liver disease in CKD patients, may limit EPO response because of thrombopoietin deficiency, iron homeostasis disorder and inflammation. Therefore, we hypothesized NAFLD is a risk factor for EPO responsiveness. To test our hypothesis, we evaluated the effect of EPO in healthy rats and rats with NAFLD induced by a high-fat, high-carbohydrate (HFHC) diet. After 12 weeks on the HFHC diet, NAFLD rats showed lower erythroid response to EPO treatment than healthy rats. We, then, determined that the primary cause of EPO hyporesponsiveness could be iron deficiency associated with inflammation, which reduces erythroid cell production. Specifically, the concentrations of hepcidin, ferritin, transferrin and white blood cells in NAFLD rats were 12.8-, 16.4-, 2.51- and 1.40-fold higher than those in healthy rats, respectively. However, erythroid cell types in the bone marrow of NAFLD rats were significantly reduced. In conclusion, our data suggest that NAFLD could be a risk factor for EPO responsiveness, which is attributed to functional iron deficiency associated with inflammation.

Association between serum trace element, mineral, and amino acid levels with non-alcoholic fatty liver disease (NAFLD) in adult women

The objective of the present study is assessment of serum trace element and amino acid levels in non-alcoholic fatty liver disease (NAFLD) patients with subsequent evaluation of its independent associations with markers of liver injury and metabolic risk.

MATERIALS AND METHODS

140 women aged 20-90 years old with diagnosed NAFLD and 140 healthy women with a respective age range were enrolled in the current study. Analysis of serum and hair levels of trace elements and minerals was performed with inductively-coupled plasma mass-spectrometry (ICP-MS). Serum amino acid concentrations were evaluated by high-pressure liquid chromatography (HPLC) with UV-detection. In addition, routine biochemical parameters including liver damage markers, alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT), were assessed spectrophotometrically.

RESULTS

The findings demonstrated that patients with NAFLD were characterized by higher ALT, GGT, lactate dehydrogenase (LDH) and cholinesterase (CE) activity, as well as increased levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and uric acid. NAFLD patients were characterized by reduced serum and hair Co, Se, and Zn levels, as well as hair Cu content and serum Mn concentrations in comparison to controls. Circulating Ala, Cit, Glu, Gly, Ile, Leu, Phe, and Tyr levels in NAFLD patients exceeded those in the control group. Multiple linear regression demonstrated that serum and hair trace element levels were significantly associated with circulating amino acid levels after adjustment for age, BMI, and metabolic parameters including liver damage markers.

CONCLUSION

It is proposed that altered trace element handling may contribute to NAFLD pathogenesis through modulation of amino acid metabolism.

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Copper Deficiency Induces Oxidative Stress in Liver of Mice by Blocking the Nrf2 Pathway

Copper (Cu) is an essential metal required for many physiological processes and biological reactions. Liver is the main organ of metabolism of Cu and is also the site where synthesis of some metalloproteins. The purpose of this study is to explore the effects of Cu deficiency on the liver and to evaluate the changes in liver oxidative stress levels to reveal its possible impact mechanisms. Mice were feed to a nutritional Cu-deficiency diet from weaning and injected with copper sulfate (CuSO4) intraperitoneally to correct Cu deficiency. Cu deficiency resulted in reduced liver index, liver histological alteration, and oxidative stress; decreased the contents of Cu and ALB; elevated ALT and AST concentrations in serum together with decreased mRNA and protein expressions of Nrf2 pathway related molecules (Nrf2, HO-1, NQO1); and increased mRNA and protein expressions of Keap1. However, the supplement of copper sulfate (CuSO4) significantly ameliorated the changes mentioned above. Our results indicate that Cu deficiency can cause hepatic damage in mice is associated with the activation of oxidative stress and inhibition of Nrf2 pathway.

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Synergistic Differential DNA Demethylation Activity of Danshensu (Salvia miltiorrhiza) Associated with Different Probiotics in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a major hepatic disorder occurring in non-alcohol-drinking individuals. Salvianic acid A or Danshensu (DSS, 3-(3, 4-dihydroxyphenyl)-(2R)-lactic acid), derived from the root of Danshen (Salvia miltiorrhiza), has demonstrated heart and liver protective properties. In this work, we investigated the antioxidant activity and hepatoprotective activity of Danshensu alone and in combination with different agents, such as probiotic bacteria (Lactobacillus casei and Lactobacillus acidophilus), against several assays. The inhibition mechanism of the methylation gene biomarkers, such as DNMT-1, MS, STAT-3, and TET-1, against DSS was evaluated by molecular docking and RT-PCR techniques. The physicochemical and pharmacokinetic ADMET properties of DSS were determined by SwissADME and pkCSM. The results indicated that all lipid blood test profiles, including cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), were reduced after the oral administration of Danshensu combined with probiotics (L. casei and L. acidophilus) that demonstrated good, efficient free radical scavenging activity, measured using anti-oxidant assays. ADMET and drug-likeness properties certify that the DSS could be utilized as a feasible drug since DSS showed satisfactory physicochemical and pharmacokinetic ADMET properties.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

A cross-sectional analysis of zinc and copper levels and their relationship to cardiovascular disease risk markers in Qatar biobank participants

Cardiovascular diseases (CVD) are the leading cause of mortality and morbidity worldwide. Dietary intake, particularly zinc (Zn) and copper (Cu) has been strongly associated with CVD. These trace elements play a crucial role in human enzyme activity, suppressing inflammation, catalyzing lipid metabolism enzymes, reducing oxidative stress, and regulating glucose metabolism. However, imbalances in these elements are linked to cardiovascular disturbances. Thus, this study aimed to investigate the association between circulating levels of Zn, Cu, and Zn/Cu ratio with CVD risk factors in the Qatari population. Bivariate logistic regression, adjusted for age, nationality, gender, and education was performed to examine the impact of Zn, Cu, and Zn/Cu ratio (as independent variables) on major CVD risk markers (as dependent variables). Participants in the highest Zn tertiles (T2 and T3) were at greater odds ratio (OR) of unfavorable metabolic functions such as elevated HbA1C [OR = 2.5, p = 0.015 (T2) and OR = 3.2, p = 0.002 (T3)], triglycerides [OR = 2.17, p = 0.015 (T2), and TyG index [OR = 2.21, p = 0.004 (T2), and OR = 2.67, p < 0.001 (T3)] compared to T1. Conversely, they had significantly lower ORs for prolonged prothrombin time [OR = 0.37, p = 0.001 (T3)]. Higher levels of Cu (T2 and T3) had higher OR for elevated HDL-C levels [OR = 1.69, p = 0.046 (T2), and OR = 2.27, p = 0.002 (T3)] and lower OR for elevated levels of triglycerides (OR = 0.4, p = 0.009, T3), diastolic blood pressure [OR = 0.41, p = 0.024 (T2), and OR = 0.47, p = 0.049 (T3)], and creatinine kinase (OR = 0.27, p = 0.014, T3) compared to T1. Higher levels of Cu (T2 and T3) were associated with a higher risk for elevated fibrinogen levels [OR = 3.1, p = 0.035 (T2), and OR = 5.04, p = 0.002 (T3)]. Additionally, higher Zn/Cu ratio (T2 and T3) were associated with lower ORs for elevated fibrinogen levels [OR = 0.3, p = 0.005 (T2), and OR = 0.27, p = 0.005 (T3)] compared to T1, indicating a lower risk of developing CVD. The study reveals a link between Zn, Cu, and the Zn/Cu ratio and cardiovascular disease risk. A higher Zn/Cu ratio may protect against CVD, while elevated Cu levels are linked to obesity, fibrinogen levels, and HbA1C. Maintaining optimal levels of these trace elements, either through diet or supplementation, may help reduce CVD risk.

Altered splicing factor and alternative splicing events in a mouse model of diet- and polychlorinated biphenyl-induced liver disease

Non-alcoholic fatty liver disease (NAFLD) is associated with human environmental exposure to polychlorinated biphenyls (PCBs). Alternative splicing (AS) is dysregulated in steatotic liver disease and is regulated by splicing factors (SFs) and N-6 methyladenosine (m6A) modification. Here integrated analysis of hepatic mRNA-sequencing data was used to identify differentially expressed SFs and differential AS events (ASEs) in the livers of high fat diet-fed C57BL/6 J male mice exposed to Aroclor1260, PCB126, Aroclor1260 + PCB126, or vehicle control. Aroclor1260 + PCB126 co-exposure altered 100 SFs and replicate multivariate analysis of transcript splicing (rMATS) identified 449 ASEs in 366 genes associated with NAFLD pathways. These ASEs were similar to those resulting from experimental perturbations in m6A writers, readers, and erasers. These results demonstrate specific hepatic SF and AS regulatory mechanisms are disrupted by HFD and PCB exposures, contributing to the expression of altered isoforms that may play a role in NAFLD progression to NASH.

Linking Metallic Micronutrients and Toxic Xenobiotics to Atherosclerosis and Fatty Liver Disease-Postmortem ICP-MS Analysis of Selected Human Tissues

Dyslipidaemia is a disorder of the lipid metabolism, caused mainly by poor eating habits. The most severe consequence of an inappropriate diet is the development of atherosclerosis and hepatic steatosis. It is generally believed that a change in nutrition, and increased physical activity can eliminate these health problems. The contemporary research and therapies used to treat dyslipidemia mainly focus on lowering the triglyceride and cholesterol levels. However, disturbances in trace element homeostasis or the accumulation of toxic elements can also affect physiological processes, and be involved in the development of metabolically mediated diseases. The present study aimed to determine the mineral profiles of liver and brain tissues collected at autopsy (n = 39) in groups of people with hepatic steatosis (n = 5), atherosclerosis (n = 9), hepatic steatosis, and atherosclerosis (n = 16), and others without the selected disorders (n = 9). Concentrations of 51 elements were analysed via inductively coupled plasma mass spectrometry (ICP-MS) after the initial wet mineralisation of the samples with nitric acid. The results obtained allow us to conclude that the hepatic steatosis group suffers from a deficiency of important trace elements, such as copper, zinc, and molybdenum (p < 0.05), whereas the group with atherosclerosis is characterised by elevated levels of cadmium in the liver tissue (p = 0.01). Analysing the mean values of the element concentrations measured in 11 brain areas, statistically significant higher levels of calcium and copper (p < 0.001) were found in the atherosclerosis group, compared to the hepatic steatosis group, confirming the involvement of these elements in the pathogenesis of atherosclerosis. In addition, an accumulation of cadmium, lead, titanium, and strontium in the brain tissue was observed in the atherosclerosis group. While the accumulation of individual elements differs in different parts of the brain, the differences in the cadmium content (p < 0.05) between the study groups apply to the whole brain, except for the nucleus accumbens septi area, where a statistically significant titanium accumulation occurs in the atherosclerosis and steatosis groups, compared to the others (p < 0.05). In addition, the disruption of elemental homeostasis in the brain of a single case with bipolar disorder, and a case with hip replacement was observed. Our results confirm the involvement of chemical elements in the pathogenesis of selected metabolic diseases, and the need for further studies in larger populations.

Iron Complexes with Antarctic Krill-Derived Peptides Show Superior Effectiveness to Their Original Protein-Iron Complexes in Mice with Iron Deficiency Anemia

Antarctic krill protein-iron complex and peptide-iron complex were acquired to investigate their iron bioavailability, expression of iron-regulated genes, and in vivo antioxidant capacity. Results indicated that the Antarctic krill peptide-iron complex significantly increased the hemoglobin (Hb), serum iron (SI), and iron contents in the liver and spleen in iron-deficiency anemia (IDA) mice (p < 0.05) compared with those of the Antarctic krill protein-iron complex. Despite the gene expressions of the divalent metal transporter 1(DMT1), the transferrin (Tf), and the transferrin receptor (TfR) being better regulated by both Antarctic krill peptide-iron complex and protein-iron complex, the relative iron bioavailability of the Antarctic krill peptide-iron complex group (152.53 ± 21.05%) was significantly higher than that of the protein-iron complex group (112.75 ± 9.60%) (p < 0.05). Moreover, Antarctic krill peptide-iron complex could enhance the antioxidant enzyme activities of superoxidase dismutase (SOD) and glutathione peroxidase (GSH-Px), reduce the malondialdehyde (MDA) level in IDA mice compared with the protein-iron complex, and reduce the cell damage caused by IDA. Therefore, these results indicated that Antarctic krill peptide-iron complex could be used as a highly efficient and multifunctional iron supplement.

Copper induces liver lipotoxicity disease by up-regulating Nrf2 expression via the activation of MTF-1 and inhibition of SP1/Fyn pathway

Excessive copper (Cu) intake leads to hepatic lipotoxicity disease, which has adverse effects on health, but the underlying mechanism is unclear. We found that Cu increased lipotoxicity by promoting Nrf2 recruitment to the ARE site in the promoters of five lipogenic genes (g6pd, 6pgd, me, icdh and pparγ). We also found that Cu affected the Nrf2 expression via different pathways: metal regulatory transcription factor 1 (MTF-1) mediated the Cu-induced Nrf2 transcriptional activation; Cu also enhanced the expression of Nrf2 by inhibiting the SP1 expression, which was achieved by inhibiting the negative regulator Fyn of Nrf2. These promoted the enrichment of Nrf2 in the nucleus and ultimately affected lipotoxicity. Thus, for the first time, we elucidated that Cu induced liver lipotoxicity disease by up-regulating Nrf2 expression via the MTF-1 activation and the inhibition of SP1/Fyn pathway. Our study elucidates the Cu-associated obesity and NAFLD for fish and possibly humans.

Multiparametric MR assessment of liver fat, iron, and fibrosis: a concise overview of the liver "Triple Screen"

Chronic liver disease (CLD) is a common source of morbidity and mortality worldwide. Non-alcoholic fatty liver disease (NAFLD) serves as a major cause of CLD with a rising annual prevalence. Additionally, iron overload can be both a cause and effect of CLD with a negative synergistic effect when combined with NAFLD. The development of state-of-the-art multiparametric MR solutions has led to a change in the diagnostic paradigm in CLD, shifting from traditional liver biopsy to innovative non-invasive methods for providing accurate and reliable detection and quantification of the disease burden. Novel imaging biomarkers such as MRI-PDFF for fat, R2 and R2* for iron, and liver stiffness for fibrosis provide important information for diagnosis, surveillance, risk stratification, and treatment. In this article, we provide a concise overview of the MR concepts and techniques involved in the detection and quantification of liver fat, iron, and fibrosis including their relative strengths and limitations and discuss a practical abbreviated MR protocol for clinical use that integrates these three MR biomarkers into a single simplified MR assessment. Multiparametric MR techniques provide accurate and reliable non-invasive detection and quantification of liver fat, iron, and fibrosis. These techniques can be combined in a single abbreviated MR "Triple Screen" assessment to offer a more complete metabolic imaging profile of CLD.

Uncertainty-aware physics-driven deep learning network for free-breathing liver fat and R2 * quantification using self-gated stack-of-radial MRI

PURPOSE

To develop a deep learning-based method for rapid liver proton-density fat fraction (PDFF) and R2 * quantification with built-in uncertainty estimation using self-gated free-breathing stack-of-radial MRI.

METHODS

This work developed an uncertainty-aware physics-driven deep learning network (UP-Net) to (1) suppress radial streaking artifacts because of undersampling after self-gating, (2) calculate accurate quantitative maps, and (3) provide pixel-wise uncertainty maps. UP-Net incorporated a phase augmentation strategy, generative adversarial network architecture, and an MRI physics loss term based on a fat-water and R2 * signal model. UP-Net was trained and tested using free-breathing multi-echo stack-of-radial MRI data from 105 subjects. UP-Net uncertainty scores were calibrated in a validation dataset and used to predict quantification errors for liver PDFF and R2 * in a testing dataset.

RESULTS

Compared with images reconstructed using compressed sensing (CS), UP-Net achieved structural similarity index >0.87 and normalized root mean squared error <0.18. Compared with reference quantitative maps generated using CS and graph-cut (GC) algorithms, UP-Net achieved low mean differences (MD) for liver PDFF (-0.36%) and R2 * (-0.37 s-1 ). Compared with breath-holding Cartesian MRI results, UP-Net achieved low MD for liver PDFF (0.53%) and R2 * (6.75 s-1 ). UP-Net uncertainty scores predicted absolute liver PDFF and R2 * errors with low MD of 0.27% and 0.12 s-1 compared to CS + GC results. The computational time for UP-Net was 79 ms/slice, whereas CS + GC required 3.2 min/slice.

CONCLUSION

UP-Net rapidly calculates accurate liver PDFF and R2 * maps from self-gated free-breathing stack-of-radial MRI. The pixel-wise uncertainty maps from UP-Net predict quantification errors in the liver.

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.

Recent advances in the application of ionomics in metabolic diseases

Trace elements and minerals play a significant role in human health and diseases. In recent years, ionomics has been rapidly and widely applied to explore the distribution, regulation, and crosstalk of different elements in various physiological and pathological processes. On the basis of multi-elemental analytical techniques and bioinformatics methods, it is possible to elucidate the relationship between the metabolism and homeostasis of diverse elements and common diseases. The current review aims to provide an overview of recent advances in the application of ionomics in metabolic disease research. We mainly focuses on the studies about ionomic or multi-elemental profiling of different biological samples for several major types of metabolic diseases, such as diabetes mellitus, obesity, and metabolic syndrome, which reveal distinct and dynamic patterns of ion contents and their potential benefits in the detection and prognosis of these illnesses. Accumulation of copper, selenium, and environmental toxic metals as well as deficiency of zinc and magnesium appear to be the most significant risk factors for the majority of metabolic diseases, suggesting that imbalance of these elements may be involved in the pathogenesis of these diseases. Moreover, each type of metabolic diseases has shown a relatively unique distribution of ions in biofluids and hair/nails from patients, which might serve as potential indicators for the respective disease. Overall, ionomics not only improves our understanding of the association between elemental dyshomeostasis and the development of metabolic disease but also assists in the identification of new potential diagnostic and prognostic markers in translational medicine.

Melatonin: Potential avenue for treating iron overload disorders

Iron overload as a highly risk factor, can be found in almost all human chronic and common diseases. Iron chelators are often used to treat iron overload; however, patient adherence to these chelators is poor due to obvious side effects and other disadvantages. Numerous studies have shown that melatonin has a high iron chelation ability and direct free radical scavenging activity, and can inhibit the lipid peroxidation process caused by iron overload. Therefore, melatonin may become potential complementary therapy for iron overload-related disorders due to its iron chelating and antioxidant activities. Here, the research progress of iron overload is reviewed and the therapeutic potential of melatonin in the treatment of iron overload is analyzed. In addition, studies related to the protective effects of melatonin on oxidative damage induced by iron overload are discussed. This review provides a foundation for preventing and treating iron homeostasis disorders with melatonin.

Nonalcoholic steatohepatitis and mechanisms by which it is ameliorated by activation of the CNC-bZIP transcription factor Nrf2

Non-alcoholic steatohepatitis (NASH) represents a global health concern. It is characterised by fatty liver, hepatocyte cell death and inflammation, which are associated with lipotoxicity, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, iron overload and oxidative stress. NF-E2 p45-related factor 2 (Nrf2) is a transcription factor that combats oxidative stress. Remarkably, Nrf2 is downregulated during the development of NASH, which probably accelerates disease, whereas in pre-clinical studies the upregulation of Nrf2 inhibits NASH. We now review the scientific literature that proposes Nrf2 downregulation during NASH involves its increased ubiquitylation and proteasomal degradation, mediated by Kelch-like ECH-associated protein 1 (Keap1) and/or β-transducin repeat-containing protein (β-TrCP) and/or HMG-CoA reductase degradation protein 1 (Hrd1, also called synoviolin (SYVN1)). Additionally, downregulation of Nrf2-mediated transcription during NASH may involve diminished recruitment of coactivators by Nrf2, due to increased levels of activating transcription factor 3 (ATF3) and nuclear factor-kappaB (NF-κB) p65, or competition for promoter binding due to upregulation of BTB and CNC homology 1 (Bach1). Many processes that downregulate Nrf2 are triggered by transforming growth factor-beta (TGF-β), with oxidative stress amplifying its signalling. Oxidative stress may also increase suppression of Nrf2 by β-TrCP through facilitating formation of the DSGIS-containing phosphodegron in Nrf2 by glycogen synthase kinase-3. In animal models, knockout of Nrf2 increases susceptibility to NASH, while pharmacological activation of Nrf2 by inducing agents that target Keap1 inhibits development of NASH. These inducing agents probably counter Nrf2 downregulation affected by β-TrCP, Hrd1/SYVN1, ATF3, NF-κB p65 and Bach1, by suppressing oxidative stress. Activation of Nrf2 is also likely to inhibit NASH by ameliorating lipotoxicity, inflammation, ER stress and iron overload. Crucially, pharmacological activation of Nrf2 in mice in which NASH has already been established supresses liver steatosis and inflammation. There is therefore compelling evidence that pharmacological activation of Nrf2 provides a comprehensive multipronged strategy to treat NASH.

Mechanistic study of regulation of iron homeostasis by N. sativa seeds and P. ovata husks on high fat/high sucrose diet induced non-alcoholic fatty liver disease

BACKGROUND

In recent years, nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions. Characteristic findings in NAFLD patients are elevated iron stores, as iron plays an important role in the pathophysiology of chronic liver disease. The current study was aimed at investigating the possible protective effects of N. sativa seeds and P. ovata husks on the regulation of iron homeostasis in NAFLD.

METHODS

Two age groups of Wistar rats (four weeks and twelve weeks old), further subdivided into four groups were fed on high fat/high sucrose (HF/SF) diet for sixteen weeks to induce NAFLD and randomized into three groups (HF/SF diet control (Group I), HF/SF diet with N. sativa seeds (Group II) and HF/SF diet with P. ovata husks (Group III) and normal diet, serving as negative control (Group 0). At the end of the experiment, histochemical analysis of hepatic sections, biochemical evaluates of the blood, and gene expression analysis were conducted.

RESULTS

The results revealed that both N. sativa seeds and P. ovata husks possess the capacity to maintain iron homeostasis by regulating the level of blood hemoglobin, serum iron contents, expression of key genes involved in iron metabolism, and iron deposition in hepatic sections. While N. sativa seeds proved more effective.

CONCLUSIONS

N. sativa seeds are a more potent iron regulator compared to P. ovata husks at reducing the iron overburden associated with NAFLD.

Potential role of selenium in alleviating obesity-related iron dyshomeostasis

Obesity is a serious health problem in modern life and increases the risk of many comorbidities including iron dyshomeostasis. In contrast to malnourished anemia, obesity-related iron dyshomeostasis is mainly caused by excessive fat accumulation, inflammation, and disordered gut microbiota. In obesity, iron dyshomeostasis also induces disorders associated with gut microbiota, neurodegenerative injury, oxidative damage, and fat accumulation in the liver. Selenium deficiency is often accompanied by obesity or iron deficiency, and selenium supplementation has been shown to alleviate obesity and overcome iron deficiency. Selenium inhibits fat accumulation and exhibits anti-inflammatory activity. It regulates gut microbiota, prevents neurodegenerative injury, alleviates oxidative damage to the body, and ameliorates hepatic fat accumulation. These effects theoretically meet the requirements for the inhibition of factors underlying obesity-related iron dyshomeostasis. Selenium supplementation may have a potential role in the alleviation of obesity-related iron dyshomeostasis. This review verifies this hypothesis in theory. All the currently reported causes and results of obesity-related iron dyshomeostasis are reviewed comprehensively, together with the effects of selenium. The challenges and strategies of selenium supplementation are also discussed. The findings demonstrate the possibility of selenium-containing drugs or functional foods in alleviating obesity-related iron dyshomeostasis.

Genetic effects of iron levels on liver injury and risk of liver diseases: A two-sample Mendelian randomization analysis

Background and aims

Although iron homeostasis has been associated with liver function in many observational studies, the causality in this relationship remains unclear. By using Mendelian Randomization analyses, we aimed to evaluate the genetic effects of increased systemic iron levels on the risk of liver injury and various liver diseases. Moreover, in light of the sex-dependent iron regulation in human beings, we further estimated the sex-specific effect of iron levels in liver diseases.

Methods

Independent single nucleotide polymorphisms associated with systemic iron status (including four indicators) at the genome-wide significance level from the Genetics of Iron Status (GIS) Consortium were selected as instrumental variables. Summary data for six liver function biomarkers and five liver diseases were obtained from the UK Biobank, the Estonian Biobank, the eMERGE network, and FinnGen consortium. Mendelian Randomization assessment of the effect of iron on liver function and liver diseases was conducted.

Results

Genetically predicted iron levels were positively and significantly associated with an increased risk of different dimensions of liver injury. Furthermore, increased iron status posed hazardous effects on non-alcoholic fatty liver disease, alcoholic liver disease, and liver fibrosis/cirrhosis. Sex-stratified analyses indicated that the hepatoxic role of iron might exist in NAFLD and liver fibrosis/cirrhosis development among men. No significantly causal relationship was found between iron status and viral hepatitis.

Conclusion

Our study adds to current knowledge on the genetic role of iron in the risk of liver injury and related liver diseases, which provides clinical and public health implications for liver disease prevention as iron status can be modified.

Individual and joint effects of metal exposure on metabolic syndrome among Chinese adults

Growing evidence suggests that metal exposure contributes to metabolic syndrome (MetS), but little is known about the effects of combined exposure to metal mixtures. This cross-sectional study included 3748 adults who were recruited from the Medical Physical Examination Center of Tongji Hospital, Wuhan, China. The levels of 21 metal(loid)s in urine were measured by inductively coupled plasma mass spectrometry. MetS was diagnosed according to National Cholesterol Education Program's Adult Treatment Panel III recommendations. Multivariate logistic regression model was uesd to explore the effects of single-metal and multi-metal exposures. The elastic net (ENET) regularization with an environmental risk score (ERS) was performed to estimate the joint effects of exposure to metal mixtures. A total of 636 participants (17%) were diagnosed with MetS. In single metal models, MetS was positively associated with zinc (Zn) and negatively associated with nickel (Ni). In multiple metal models, the associations remained significant after adjusting for the other metals. In the joint association analysis, the ENET models selected Zn as the strongest predictor of MetS. Compared to the lowest quartile, the highest quartile of ERS was associated with an elevated risk of MetS (OR = 3.72; 95% CI: 2.77, 5.91; P-trend < 0.001). Overall, we identified that the combined effect of multiple metals was related to an increased MetS risk, with Zn being the major contributor. These findings need further validation in prospective studies.

Iron Metabolism in Pancreatic Beta-Cell Function and Dysfunction

Iron is an essential element involved in a variety of physiological functions. In the pancreatic beta-cells, being part of Fe-S cluster proteins, it is necessary for the correct insulin synthesis and processing. In the mitochondria, as a component of the respiratory chain, it allows the production of ATP and reactive oxygen species (ROS) that trigger beta-cell depolarization and potentiate the calcium-dependent insulin release. Iron cellular content must be finely tuned to ensure the normal supply but also to prevent overloading. Indeed, due to the high reactivity with oxygen and the formation of free radicals, iron excess may cause oxidative damage of cells that are extremely vulnerable to this condition because the normal elevated ROS production and the paucity in antioxidant enzyme activities. The aim of the present review is to provide insights into the mechanisms responsible for iron homeostasis in beta-cells, describing how alteration of these processes has been related to beta-cell damage and failure. Defects in iron-storing or -chaperoning proteins have been detected in diabetic conditions; therefore, the control of iron metabolism in these cells deserves further investigation as a promising target for the development of new disease treatments.

Free-breathing 3D stack-of-radial MRI quantification of liver fat and R2* in adults with fatty liver disease

PURPOSE

To investigate the agreement, intra-session repeatability, and inter-reader agreement of liver proton-density fat fraction (PDFF) and R₂* quantification using free-breathing 3D stack-of-radial MRI, with and without self-gated motion compensation, compared to reference breath-hold techniques in subjects with fatty liver disease (FLD).

METHODS

In this institutional review board-approved prospective study, thirty-eight adults with FLD and/or iron overload (24 male, 58 ± 12 years) were imaged at 3T using free-breathing stack-of-radial MRI, breath-hold 3D Cartesian MRI, and breath-hold single-voxel MR spectroscopy (SVS). Each sequence was acquired twice in random order. To assess agreement compared to reference breath-hold techniques, the dependency of liver PDFF and/or R₂* quantification on the sequence, radial sampling factor, and radial self-gating temporal resolution was assessed by calculating the Bayesian mean difference (MD_B) of the posteriors. Intra-session repeatability and inter-reader agreement (two independent readers) were assessed by the coefficient of repeatability (CR) and intraclass correlation coefficient (ICC), respectively.

RESULTS

Thirty-five participants (21 male, 57 ± 12 years) were included for analysis. Both free-breathing radial MRI techniques (with and without self-gating) achieved ICC ≥ 0.92 for quantifying PDFF and R₂*, and quantified PDFF with MD_B < 1.2% compared to breath-hold techniques. Free-breathing radial MRI required self-gating to accurately quantify R₂* (MD_B < 10s^-1 with self-gating; MD_B < 50s^-1 without self-gating). The radial sampling factor affected PDFF and R₂* quantification while the radial self-gating temporal resolution only affected R₂* quantification. Repeated self-gated free-breathing radial MRI scans achieved CR < 3% and CR < 27 s^-1 for PDFF and R₂*, respectively.

CONCLUSION

A free-breathing stack-of-radial MRI technique with self-gating demonstrated agreement, repeatability, and inter-reader agreement compared to reference breath-hold techniques for quantification of liver PDFF and R₂* in adults with FLD.

Anthropometric Markers With Specific Cut-Offs Can Predict Anemia Occurrence Among Malaysian Young Adults

Objective: Anemia bears a high global prevalence with about 1.6 billion people living with this affliction. Malaysia carries the burden of 13.8% anemia prevalence which urges for extensive research directed to its prediction and amelioration. This is the first study that aims to (a) propose simple non-invasive predictive anthropometric markers and their specific cut-off values for early prediction of anemia among the young adults in Malaysia, (b) provide anemia prevalence based on both gender and ethnicity among young adults of Malaysia.

Method: The present cross-sectional study included 245 participants (113 men and 132 women) aged between 18 and 30 years. Anthropometric parameters were measured following the standard protocols. Blood samples were collected and hemoglobin levels were determined using the HemoCue haemoglobinometer (Hb 201+ System, Angelhom, Sweden) to detect the presence of anemia. The receiver operating characteristics (ROC) curve was employed to assess and compare the efficacy of anthropometric indices in the prediction of anemia. Data were analyzed using SPSS (v. 22.0, IBM, Chicago, IL, USA) and MedCalc (v. 19.05, Ostend, Belgium).

Result: The ROC analysis indicates that body mass index (BMI) is the best anthropometric marker with the highest area under the curve (AUC) and specificity (SP) for predicting the presence of anemia in young adults in Malaysia. Thus, the study proposes the optimal cut-off value of BMI for young men of Malaysia as 20.65 kg/m² (AUC: 0.889) and young women of Malaysia as 19.7 kg/m² (AUC: 0.904). The study also reports that Malaysian Indians have the highest prevalence of anemia (26.22%) followed by Malays (21.54%), “Others” (indigenous ethnic group) (20%), and Chinese (14.5%), with an overall higher prevalence of anemia in young adult women (21.96%) than in men (18.6%) of Malaysia.

Conclusion: The proposed anemia-predictive anthropometric markers with optimal cut-off values will aid early detection of anemia among young adults in Malaysia, and given its simple, inexpensive, and intelligible approach, it can be widely used. The ease of anemia prediction together with the reported distribution of anemia prevalence based on gender and ethnicity will facilitate in gauging the necessary extent of strategies of anemia management in the young adult population of Malaysia.

Low hepatic manganese concentrations in patients with hepatic steatosis - A cohort study of copper, iron and manganese in liver biopsies

BACKGROUND AND AIMS

Hepatic steatosis is the most common histopathological finding on liver biopsy, with the most prevalent etiology being NAFLD. The pathogenesis of hepatic steatosis and NAFLD is multifactorial, however, studies on the importance of manganese in NAFLD are limited. We aimed to study hepatic manganese content, and other trace elements, in relation to hepatic steatosis in patients with chronic liver diseases of different etiology, mainly NAFLD.

METHODS

Patients with chronically elevated liver function tests underwent a diagnostic work-up, including routine blood tests and two liver biopsies. One of the biopsies was sent for histopathological evaluation, and the other for ultra-trace elemental determinations. Steatosis was graded using conventional histopathological methodology, and fat content was also quantitated in biopsy samples by measuring the steatotic area of the section using stereological point counting (SPC). Ultra-trace elemental analysis was utilized for determining manganese, iron, and copper using inductively coupled plasma sector field mass spectrometry (ICP-SFMS).

RESULTS

76 patients were included in the study. Hepatic manganese concentrations in patients with steatosis were lower than in patients without hepatic steatosis (3.8 ± 1.1 vs. 6.4 ± 1.8, P < 0.001). Similar results were seen for blood manganese levels and hepatic steatosis. We found a strong inverse correlation between steatosis grade and hepatic manganese content (ρ=-0.743, P < 0.001). Also, low levels of manganese independently predicted the presence of steatosis (aOR 0.07 [95%CI: 0.01-0.63]).

CONCLUSION

Patients with NAFLD, or other CLD and concomitant hepatic steatosis, showed lower levels of hepatic manganese content with increasing grade of steatosis.

The Association between Zinc and Copper Circulating Levels and Cardiometabolic Risk Factors in Adults: A Study of Qatar Biobank Data

Cardiometabolic risk (CMR) factors increase the likelihood of developing cardiovascular diseases (CVD). In Qatar, 24% of the total deaths are attributed to CVDs. Several nutritional disturbances have been linked to high risk of CVD. Many studies have discussed the effects of zinc (Zn) and copper (Cu) on CMR factors; however, evidence has been controversial. This investigated the association between CMR factors and the status of Zn and Cu, in addition to Zn/Cu ratio. A total of 575 Qatari men and women aged 18 years and older were obtained from Qatar Biobank. Plasma levels of Zn and Cu were determined using inductively coupled plasma mass spectrometry (ICP-MS). Anthropometric data and CMR factors were determined using standard methods. Adjusted associations between trace minerals and CMR were estimated by logistic regression. Partial correlation was performed to test the strength of the associations. Zn was not strongly correlated (p-value ˃ 0.01) or significantly associated with CMR factors and metabolic syndrome (MetS). Cu levels correlated positively with body mass index (BMI) (0.23; p ˂ 0.001), pulse rate (PR) (0.18; p ˂ 0.001), total cholesterol (0.13; p = 0.01), and high-density lipoproteins (HDL) (0.27; p ˂ 0.001); and negatively with diastolic blood pressure (DBP) (−0.13; p = 0.01). High plasma Cu significantly decreased the risk of metabolic syndrome (MetS) (0.121; p ˂ 0.001). Furthermore, Zn/Cu ratio positively correlated with waist circumference (0.13; p = 0.01), systolic blood pressure (0.13; p ˂ 0.01), and DBP (0.14; p ˂ 0.01); and negatively with BMI (−0.19; p ˂ 0.001), PR (−0.17; p ˂ 0.001), and HDL (−0.27; p ˂ 0.001). High Zn/Cu ratio increased the prevalence of low HDL (4.508; p ˂ 0.001) and MetS (5.570; p ˂ 0.01). These findings suggest that high plasma Cu levels are associated with a protective effect on DBP, HDL and MetS and that high plasma Zn/Cu ratio is associated with the risk of having low HDL and MetS.

Hepcidin Levels and Pathological Characteristics in Children with Fatty Liver Disease

PURPOSE

Hepcidin levels have previously been reported to be correlated with liver damage. However, the association between hepcidin levels and liver fibrosis in children with fatty liver disease remains unclear. This study therefore aimed to investigate the pathophysiology of fibrosis in children with fatty liver disease and its association with hepcidin levels.

METHODS

This retrospective case series included 12 boys aged 6-17 years who were diagnosed with nonalcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH) at the Tokyo Medical University Hospital. Sixteen liver biopsy samples from 12 subjects were analyzed. Serum hepcidin levels were assayed using enzyme-linked immunosorbent assay. Immunostaining for hepcidin was performed, and the samples were stratified by staining intensity.

RESULTS

Serum hepcidin levels were higher in pediatric NAFLD/NASH patients than in controls. Conversely, a significant inverse correlation was observed between hepcidin immunostaining and Brunt grade scores and between hepcidin scores and gamma-glutamyltranspeptidase, hyaluronic acid, and leukocyte levels. We observed inverse correlations with a high correlation coefficient of >0.4 between hepcidin immunostaining and aspartate aminotransferase, alanine aminotransferase, total bile acid, and platelet count.

CONCLUSION

There was a significant inverse correlation between hepcidin immunoreactivity and fibrosis in pediatric NAFLD patients; however, serum hepcidin levels were significantly higher, suggesting that these patients experienced a reduction in the hepcidin-producing ability of the liver in response to iron levels, leading to subsequent fibrosis. Therefore, hepcidin levels can be used as markers to identify the progression of fibrosis in patients with NAFLD.

DISTINCT PHENOTYPE OF NON-ALCOHOLIC FATTY LIVER DISEASE IN PATIENTS WITH LOW LEVELS OF FREE COPPER AND OF CERULOPLASMIN

BACKGROUND

Copper deficiency has been linked to alterations in lipid metabolism and hepatic steatosis. Oxidative stress plays a role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). One of the enzymes that neutralize oxidative stress is Cu/Zn superoxide dismutase, which depends on the availability of adequate amounts of copper.

OBJECTIVE

Correlate the levels of ceruloplasmin and of non-ceruloplasmin-bound copper (NCBC) with clinical, biochemical and histological parameters of non-alcoholic fatty liver disease (NAFLD) patients.

METHODS

Data from 95 consecutively admitted NAFLD patients who underwent liver biopsy composed the groups based on ceruloplasmin levels lower than 25 mg/dL and on negative NCBC. The risk factors for NAFLD in each group were compared.

RESULTS

Body mass index was lower in patients with ceruloplasmin <25 mg/dL (29.1±3.47 vs 32.8±6.24 kg/m2; P=0.005) as were the levels of LDL, HDL and total cholesterol, when compared with their counterparts with ceruloplasmin >25 mg/dL (101±38 vs 116±35 mg/dL, P=0.05; 43±9 vs 51±16 mg/dL, P=0.01; 174±43 vs 197±39 mg/dL, P=0.01, respectively). Mean serum ferritin levels were higher in the ceruloplasmin <25 mg/dL group (343±327 vs 197±190 ng/mL; P=0.02). Otherwise, patients with negative NCBC had higher HOMA-IR (8.2±14.7 vs 4.6±3.7; P=0.03). Age, gender, hypertension and diabetes showed no statistical difference.

CONCLUSION

Patients with NAFLD had different clinical and biochemical markers according to the levels of NCBC and ceruloplasmin.

Clinical heterogeneity in patients with non-alcoholic fatty liver disease-associated hepatocellular carcinoma

INTRODUCTION

The indisputable increase in nonalcoholic Fatty Liver Disease (NAFLD) prevalence (25% of population) has consequently led to an increase in Hepatocellular Carcinoma (HCC) and liver-related mortality worldwide. The characteristics of patients with HCC, secondary to NAFLD, are older age, large tumors due to late diagnosis, often without cirrhosis and high prevalence of the metabolic syndrome components, leading to an increased mortality rate. Although the mechanisms of disease remain partially obscure, insulin resistance, oxidative stress, apoptosis, iron overload, and excessive local and systemic inflammation are identified as culprits for hepatocarcinogenesis in the presence of NAFLD.

AREA COVERED

In this review, the authors report that there are no uniform guidelines for surveillance and early diagnosis in this patient group. Barcelona Clinic Liver Cancer staging is generally applicable to HCC due to NAFLD and management depends on liver function, tumor characteristics, and cardiovascular comorbidity. Evidence suggests that HCC due to NAFLD can be associated with worse survival due to late diagnosis.

EXPERT OPINION

The need for effective early diagnosis and management of NAFLD is urgent, considering the galloping incidence of the obesity and the fact that liver cirrhosis and HCC due to NAFLD will become the first indication for liver transplantation in foreseeable future.

Abnormal metabolic processes involved in the pathogenesis of non-alcoholic fatty liver disease (Review)

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and can lead to liver cirrhosis or liver cancer in severe cases. In recent years, the incidence of NAFLD has increased substantially. The trend has continued to increase and has become a key point of concern for health systems. NAFLD is often associated with metabolic abnormalities caused by increased visceral obesity, including insulin resistance, diabetes mellitus, hypertension, dyslipidemia, atherosclerosis and systemic microinflammation. Therefore, the pathophysiological mechanisms of NAFLD must be clarified to develop new drug treatment strategies. Recently, researchers have conducted numerous studies on the pathogenesis of NAFLD and have identified various important regulatory factors and potential molecular mechanisms, providing new targets and a theoretical basis for the treatment of NAFLD. However, the pathogenesis of NAFLD is extremely complex and involves the interrelationship and influence of multiple organs and systems. Therefore, the condition must be explored further. In the present review, the abnormal metabolic process, including glucose, lipid, amino acid, bile acid and iron metabolism are reviewed. It was concluded that NAFLD is associated with an imbalanced metabolic network that involves glucose, lipids, amino acids, bile acids and iron, and lipid metabolism is the core metabolic process. The current study aimed to provide evidence and hypotheses for research and clinical treatment of NAFLD.

Effect of Zn Supplementation on Trace Element Status in Rats with Diet-Induced Non-alcoholic Fatty Liver Disease

The present study aimed to assess the effect of Zn supplementation on trace element levels in the liver, serum, and hair of rats with dietary-induced non-alcoholic fatty liver disease (NAFLD). A total of 26 3-month-old female Wistar rats were divided into four groups: control, NAFLD, Zn-supplemented (227 mg/L zinc as Zn sulfate Zn(SO)₄ dissolved in a drinking water), and NAFLD-Zn-supplemented. NAFLD was verified by histological assessment of liver samples. The serum was examined for routine biochemical parameters. Trace elements content was assessed using inductively coupled plasma mass spectrometry (ICP-MS). Zn treatment resulted in an improvement in liver weight and morphology. Dietary supplementation with Zn prevented NAFLD-induced decrease liver Co. The tendency to increase liver Fe in the Zn-treated group was observed. Zn treatment decreased hepatic Al and serum V levels. However, Zn administration did not affect NAFLD-induced I, Mn, and Se depletion in the liver. Hair Zn levels raised in Zn-supplemented groups. Conclusively, the results of the study indicate that Zn supplementation could have a beneficial effect in modulation of the altered trace element status and liver morphology. HIGHLIGHTS: •Zn treatment improved liver weight and morphology in rats with NAFLD. •Zn supplementation decreased liver Al in NAFLD. •Treatment by Zn prevented depletion of liver Co. •Zn decreased serum V and increased hair Zn levels. •No effect of Zn on NAFLD-induced hepatic I, Mn and Se depletion was observed.

Association between urinary metals levels and metabolic phenotypes in overweight and obese individuals

Epidemiologic studies suggest that circulating metals from the natural environment are linked with cardiometabolic health. However, few studies examined the relationship between multiple metals exposure and metabolic phenotypes, especially in obese individuals. We conducted a cross-sectional study to explore the association between 23 urinary metals and metabolic phenotypes in 1392 overweight and obese individuals (592 males, 800 females, mean age 43.1 ± 9.8 years). Participants were classified as metabolically unhealthy if they had ≥2 of the following metabolic abnormalities: elevated blood pressure, elevated fasting blood glucose, elevated triglycerides, and reduced high-density lipoprotein cholesterol. Odds ratios (ORs) of unhealthy metabolic phenotypes for metal levels categorized into tertiles were assessed using logistic regression models. Five metals (barium, copper, iron, uranium, and zinc) were associated with unhealthy metabolic phenotypes in single-metal models, while in the multiple-metal model, only zinc and zinc-copper ratio remained significant. The ORs (95% CIs) comparing extreme tertiles were 2.57 (1.69, 3.89) for zinc and 1.68 (1.24, 2.27) for zinc-copper ratio after adjustment for confounders (both p-trends were <0.001). The numbers of metabolic abnormalities significantly increased with the levels of zinc and the zinc-copper ratio increased. Similar associations were observed with metabolic syndrome risk. High levels of urinary zinc were positively associated with elevated fasting blood glucose (p-trend < 0.001) and elevated triglycerides (p-trend = 0.003). The results suggest that urinary zinc and zinc-copper ratio are positively associated with increased risk of unhealthy metabolic phenotype. Further prospective studies with a larger sample size are required to verify these findings.

Current Trends of Essential Trace Elements in Patients with Chronic Liver Diseases

Essential trace elements play crucial roles in the maintenance of health, since they are involved in many metabolic pathways. A deficiency or an excess of some trace elements, including zinc, selenium, iron, and copper, frequently causes these metabolic disorders such as impaired glucose tolerance and dyslipidemia. The liver largely regulates most of the metabolism of trace elements, and accordingly, an impairment of liver functions can result in numerous metabolic disorders. The administration or depletion of these trace elements can improve such metabolic disorders and liver dysfunction. Recent advances in molecular biological techniques have helped to elucidate the putative mechanisms by which liver disorders evoke metabolic abnormalities that are due to deficiencies or excesses of these trace elements. A genome-wide association study revealed that a genetic polymorphism affected the metabolism of a specific trace element. Gut dysbiosis was also responsible for impairment of the metabolism of a trace element. This review focuses on the current trends of four trace elements in chronic liver diseases, including chronic hepatitis, liver cirrhosis, nonalcoholic fatty liver disease, and autoimmune liver diseases. The novel mechanisms by which the trace elements participated in the pathogenesis of the chronic liver diseases are also mentioned.

Novel predictive models using serum ceruloplasmin levels for hepatic steatosis in patients with chronic hepatitis B infection

AIMS

To evaluate the significance of serum ceruloplasmin (CP) to diagnosis hepatic steatosis (HS) in Chronic hepatitis B (CHB) patients.

METHODS

A total of 360 CHB patients with HS (n = 136) or without HS (n = 224) were included. Relationships between CP and HS degrees were analyzed by Spearman rank correlation. HS-predictive models including CP were constructed using multivariate logistic regression analysis and compared to other HS predicting indexes.

RESULTS

Serum CP were significantly higher in CHB patients with HS than in patients without HS (P < 0.001) and were positively correlated with HS degree (r = 0.487, P < 0.001). The area under the receiver-operating characteristic curves (AUCs) of using CP to predict HS (S ≥ 1), moderate and severe steatosis (S ≥ 2) and severe steatosis (S = 3) were 0.758, 0.794 and 0.883, respectively. Multivariate analysis showed that CP, age, high density lipoprotein (HDL) and hemoglobin were independent predictors of HS, and CP, body mass index and HDL were independent predictors of moderate and severe HS. Two novel indexes for predicting HS of CHB patients were generated. The AUC of HSCHB-1 (for S ≥ 1) and HSCHB-2 (for S ≥ 2) were 0.881 and 0.916 in the training group, and 0.865 and 0.841 in the validation group, respectively. HSCHB-1 was superior to HS index (P < 0.001), fatty liver disease index (P = 0.0043) and steatosis index of patients with hepatitis B virus infection (P = 0.0029) in predicting HS in CHB patients.

CONCLUSIONS

HS of CHB patients was positively associated with serum CP. HSCHB-1 and HSCHB-2 with inclusion of CP are two novel models for predicting HS in CHB patients.

Macrophage Function in the Pathogenesis of Non-alcoholic Fatty Liver Disease: The Mac Attack

Obesity is a prevalent predisposing factor to non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease in the developed world. NAFLD spectrum of disease involves progression from steatosis (NAFL), to steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma (HCC). Despite clinical and public health significance, current FDA approved therapies for NAFLD are lacking in part due to insufficient understanding of pathogenic mechanisms driving disease progression. The etiology of NAFLD is multifactorial. The induction of both systemic and tissue inflammation consequential of skewed immune cell metabolic state, polarization, tissue recruitment, and activation are central to NAFLD progression. Here, we review the current understanding of the above stated cellular and molecular processes that govern macrophage contribution to NAFLD pathogenesis and how adipose tissue and liver crosstalk modulates macrophage function. Notably, the manipulation of such events may lead to the development of new therapies for NAFLD.

Reduced Gut Microbiome Diversity and Metabolome Differences in Rhinoceros Species at Risk for Iron Overload Disorder

Iron overload disorder (IOD) affects many wildlife species cared for ex situ. Two of the four rhinoceros species in human care, Sumatran rhinoceros (Dicerorhinus sumatrensis) and black rhinoceros (Diceros bicornis), are susceptible, whereas the other two, white rhinoceros (Ceratotherium simum) and greater one-horned (GOH) rhinoceros (Rhinoceros unicornis), are relatively resistant to IOD. Complex interrelationships exist between mammalian hosts, their indigenous gut microbiota, metabolome, physical condition, and iron availability. The goal of this study was to gain insight into these relationships within the family Rhinocerotidae. Specific objectives were to (1) characterize the gut microbiome and metabolome of four rhinoceros species; (2) compare the microbiome and metabolome of IOD-susceptible and IOD-resistant rhinoceros species; and (3) identify variation in the microbiome and metabolome associated with compromised health or disease in IOD-susceptible rhinoceroses. Fecal samples were collected from 31 rhinoceroses (Sumatran rhinoceros, n = 3; black rhinoceros, n = 6; GOH rhinoceros, n = 9; white rhinoceros, n = 13) located at five facilities, and matched fecal aliquots were processed for microbiome and metabolome analyses using 16S rRNA gene sequencing and nuclear magnetic resonance spectroscopy, respectively. Despite the phylogenetic disparity and dissimilar zoo diets of the hosts, the structure of the fecal microbiota of the two IOD-susceptible rhinoceros species were more closely related to each other than to those of the two IOD-resistant species (Bray–Curtis dissimilarity; IOD-susceptible vs. IOD-resistant p-value < 0.001). In addition, IOD-susceptible rhinoceroses exhibited less microbial diversity than their IOD-resistant relatives (Shannon diversity; p-value < 0.001) which could have health implications. Of note, the black rhinoceros was distinct among the four rhinoceros species with the most divergent fecal metabolome; interestingly, it contained higher concentrations of short chain fatty acids. Neither age nor sex were associated with differences in microbial community composition (p = 0.253 and 0.488, respectively) or fecal metabolomic profile (p = 0.634 and 0.332, respectively). Differences in the distal gut microbiomes between IOD-resistant and IOD-susceptible rhinoceroses support hypotheses that gut microbes play a role in host iron acquisition, and further studies and experiments to test these hypotheses are warranted.

Protective effect of sestrin2 against iron overload and ferroptosis-induced liver injury

Ferroptosis is the non-apoptotic form of cell death caused by small molecules or conditions that inhibit glutathione biosynthesis or resulting in iron-dependent accumulation of lipid peroxidation by lipid reactive oxygen species (ROS). Sestrin2 (Sesn2), a conserved antioxidant protein, is responsive to various stresses including genotoxic, metabolic, and oxidative stresses and acts to restore homeostatic balance. Sesn2 expression was reported to be regulated via stress-responsive transcription factors including p53, Nrf2, and HIF-1α. However, the role of Sesn2 in regulating ferroptosis is not known. In the current study, we investigated whether ferroptosis inducing compounds including erastin, sorafenib, and buthionine sulfoximine affect Sesn2 expression and the role of Sesn2 in cytoprotection against ferroptosis-mediated cell death. Our data demonstrate that ferroptosis inducers significantly increased Sesn2 in hepatocytes in a dose- and time-dependent manner. Treatment with erastin upregulated Sesn2 mRNA levels and luciferase reporter gene activity, and erastin-mediated Sesn2 induction was transcriptionally regulated by NF-E2-related factor 2 (Nrf2). Furthermore, deletion of the antioxidant response element (ARE) in the Sesn2 promoter or Nrf2 knockout or knockdown abolished erastin-induced Sesn2 expression. In cells expressing Sesn2, erastin-induced cell death, ROS formation, and glutathione depletion were almost completely inhibited compared to that in control cells. Treatment with phenylhydrazine in mice, well-reported iron overload liver injury model, increased ALT and AST levels and altered histological features, which were almost completely inhibited by adenoviral Sesn2 infection. Collectively, our results suggest that ferroptosis-mediated Sesn2 induction is dependent on Nrf2 and plays a protective role against iron overload and ferroptosis-induced liver injury.

Iron overload reduces synthesis and elimination of bile acids in rat liver

Excessive iron accumulation in the liver, which accompanies certain genetic or metabolic diseases, impairs bile acids (BA) synthesis, but the influence of iron on the complex process of BA homeostasis is unknown. Thus, we evaluated the effect of iron overload (IO) on BA turnover in rats. Compared with control rats, IO (8 intraperitoneal doses of 100 mg/kg every other day) significantly decreased bile flow as a consequence of decreased biliary BA secretion. This decrease was associated with reduced expression of Cyp7a1, the rate limiting enzyme in the conversion of cholesterol to BA, and decreased expression of Bsep, the transporter responsible for BA efflux into bile. However, IO did not change net BA content in faeces in response to increased intestinal conversion of BA into hyodeoxycholic acid. In addition, IO increased plasma cholesterol concentrations, which corresponded with reduced Cyp7a1 expression and increased expression of Hmgcr, the rate-limiting enzyme in de novo cholesterol synthesis. In summary, this study describes the mechanisms impairing synthesis, biliary secretion and intestinal processing of BA during IO. Altered elimination pathways for BA and cholesterol may interfere with the pathophysiology of liver damage accompanying liver diseases with excessive iron deposition.

Bromide alleviates fatty acid-induced lipid accumulation in mouse primary hepatocytes through the activation of PPARα signals

Increased plasma free fatty acids (FFAs) and liver triglyceride (TG) accumulations have been implicated in the pathogenesis of hepatic steatosis. On the other hand, trace elements function as essential cofactors that are involved in various biochemical processes in mammals, including metabolic homeostasis. Notably, clinical and animal studies suggest that the plasma levels of bromide negatively correlate with those of TG, total cholesterol (TC) and high‐density lipoprotein‐cholesterol (HDL‐C). However, the effect of bromide on lipid accumulation and the direct molecular target responsible for its action remains unknown. Oil red O (ORO) and Nile red staining were used to detect the effect of bromide on lipid accumulation in mouse primary hepatocytes (PHs) treated with different doses of sodium bromide (NaBr) in the presence of FFAs (0.4 mM oleate/palmitic acid 1:1). Spectrophotometric and fluorometric analyses were performed to assess cellular TG concentrations and rates of fatty acid oxidation (FAO), respectively, in mouse PHs. We found that bromide decreased FFA‐induced lipid accumulation and increased FFA‐inhibited oxygen consumptions in mouse PHs in a dose‐dependent manner via activation of PPARα. Mechanical studies demonstrated that bromide decreased the phosphorylation levels of JNK. More importantly, the PPARα‐specific inhibitor GW6471 partially abolished the beneficial effects of bromide on mouse PHs. Bromide alleviates FFA‐induced excessive lipid storage and increases rates of FAO through the activation of PPARα/JNK signals in mouse PHs. Therefore, bromide may serve as a novel drug in the treatment of hepatic steatosis.

Oxidative Stress and Non-Alcoholic Fatty Liver Disease: Effects of Omega-3 Fatty Acid Supplementation

Aging is a complex phenomenon characterized by the progressive loss of tissue and organ function. The oxidative-stress theory of aging postulates that age-associated functional losses are due to the accumulation of ROS-induced damage. Liver function impairment and non-alcoholic fatty liver disease (NAFLD) are common among the elderly. NAFLD can progress to non-alcoholic steatohepatitis (NASH) and evolve to hepatic cirrhosis or hepatic carcinoma. Oxidative stress, lipotoxicity, and inflammation play a key role in the progression of NAFLD. A growing body of evidence supports the therapeutic potential of omega-3 polyunsaturated fatty acids (n-3 PUFA), mainly docosahaexenoic (DHA) and eicosapentaenoic acid (EPA), on metabolic diseases based on their antioxidant and anti-inflammatory properties. Here, we performed a systematic review of clinical trials analyzing the efficacy of n-3 PUFA on both systemic oxidative stress and on NAFLD/NASH features in adults. As a matter of fact, it remains controversial whether n-3 PUFA are effective to counteract oxidative stress. On the other hand, data suggest that n-3 PUFA supplementation may be effective in the early stages of NAFLD, but not in patients with more severe NAFLD or NASH. Future perspectives and relevant aspects that should be considered when planning new randomized controlled trials are also discussed.