Interaction of iron, insulin resistance, and nonalcoholic steatohepatitis

Abbreviated Multiparametric MR Solution (the "Liver Triple Screen"), the Future of Non-Invasive MR Quantification of Liver Fat, Iron, and Fibrosis

Background/Objectives: To review the findings of a multiparametric MRI (the "liver triple screen") solution for the non-invasive assessment of liver fat, iron, and fibrosis in patients with chronic liver disease (CLD). Methods: A retrospective evaluation of all consecutive triple screen MRI cases was performed at our institution over the last 32 months. Relevant clinical, laboratory, and radiologic data were analyzed using descriptive statistics. Results: There were 268 patients, including 162 (60.4%) males and 106 (39.6%) females. The mean age was 54 ± 15.2 years (range 16 to 71 years). The most common cause of CLD was metabolic dysfunction-associated steatotic liver disease (MASLD) at 45.5%. The most common referring physician group was Gastroenterology at 62.7%. In 23.9% of cases, the reason for ordering the MRI was a pre-existing failed or unreliable US elastography. There were 17 cases (6.3%) of MRI technical failure. Our analysis revealed liver fibrosis in 66% of patients, steatosis in 68.3%, and iron overload in 22.1%. Combined fibrosis and steatosis were seen in 28.7%, steatosis and iron overload in 16.8%, fibrosis and iron overload in 6%, and combined fibrosis, steatosis, and iron overload in 4.1%. A positive MEFIB index, a predictor of liver-related outcomes, was found in 57 (27.5%) of 207 patients. Incidental findings were found in 14.9% of all MRIs. Conclusions: The liver triple screen MRI is an effective tool for evaluating liver fat, iron, and fibrosis in patients with CLD. It provides essential clinical information and can help identify MASLD patients at risk for liver-related outcomes.

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.

Non-alcoholic fatty liver disease (NAFLD) and mental illness: Mechanisms linking mood, metabolism and medicines

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world and one of the leading indications for liver transplantation. It is one of the many manifestations of insulin resistance and metabolic syndrome as well as an independent risk factor for cardiovascular disease. There is growing evidence linking the incidence of NAFLD with psychiatric illnesses such as schizophrenia, bipolar disorder and depression mechanistically via genetic, metabolic, inflammatory and environmental factors including smoking and psychiatric medications. Indeed, patients prescribed antipsychotic medications, regardless of diagnosis, have higher incidence of NAFLD than population norms. The mechanistic pharmacology of antipsychotic-associated NAFLD is beginning to emerge. In this review, we aim to discuss the pathophysiology of NAFLD including its risk factors, insulin resistance and systemic inflammation as well as its intersection with psychiatric illnesses.

Platelets in Non-alcoholic Fatty Liver Disease

Non alcoholic steatohepatitis (NASH) is the inflammatory reaction of the liver to excessive accumulation of lipids in the hepatocytes. NASH can progress to cirrhosis and hepatocellular carcinoma (HCC). Fatty liver is the hepatic manifestation of metabolic syndrome. A subclinical inflammatory state is present in patients with metabolic alterations like insulin resistance, type-2 diabetes, obesity, hyperlipidemia, and hypertension. Platelets participate in immune cells recruitment and cytokines-induced liver damage. It is hypothesized that lipid toxicity cause accumulation of platelets in the liver, platelet adhesion and activation, which primes the immunoinflammatory reaction and activation of stellate cells. Recent data suggest that antiplatelet drugs may interrupt this cascade and prevent/improve NASH. They may also improve some metabolic alterations. The pathophysiology of inflammatory liver disease and the implication of platelets are discussed in details.

The transcription factors CREBH, PPARa, and FOXO1 as critical hepatic mediators of diet-induced metabolic dysregulation

The liver is a critical mediator of lipid and/or glucose homeostasis and is a primary organ involved in dynamic changes during feeding and fasting. Additionally, hepatic-centric pathways are prone to dysregulation during pathophysiological states including metabolic syndrome (MetS) and non-alcoholic fatty liver disease. Omics platforms and GWAS have elucidated genes related to increased risk of developing MetS and related disorders, but mutations in these metabolism-related genes are rare and cannot fully explain the increasing prevalence of MetS-related pathologies worldwide. Complex interactions between diet, lifestyle, environmental factors, and genetic predisposition jointly determine inter-individual variability of disease risk. Given the complexity of these interactions, researchers have focused on master regulators of metabolic responses incorporating and mediating the impact of multiple environmental cues. Transcription factors are DNA binding, terminal executors of signaling pathways that modulate the cellular responses to complex metabolic stimuli and are related to the control of hepatic lipid and glucose homeostasis. Among numerous hepatic transcription factors involved in regulating metabolism, three emerge as key players in transducing nutrient sensing, which are dysregulated in MetS-related perturbations in both clinical and preclinical studies: cAMP Responsive Element Binding Protein 3 Like 3 (CREB3L3), Peroxisome Proliferator Activated Receptor Alpha (PPAR), and Forkhead Box O1 (FOXO1). Additionally, these three transcription factors appear to be amenable to dietary and/or nutrient-based therapies, being potential targets of nutritional therapy. In this review we aim to describe the activation, regulation, and impact of these transcription factors in the context of metabolic homeostasis. We also summarize their perspectives in MetS and nutritional therapies.

A high-fructose diet in rats induces systemic iron deficiency and hepatic iron overload by an inflammation mechanism

Nonalcoholic fatty liver disease (NAFLD) correlates with the high intake of fructose-rich soft drinks. Both inflammation and dysregulated iron metabolism are pathogenic factors in the development of NAFLD. The present investigation assessed the effects of a high-fructose diet (HF diet) on inflammation and iron metabolism. In this study, rats were fed a control or HF diet for 4, 8, or 12 weeks, after which insulin resistance, transaminases levels, serum and liver lipid profiles, inflammatory factors, and iron metabolism-related molecules were evaluated. The activities of the hepatic inflammation-associated pathways, IKKβ/NF-κB, and JAK2/STAT3, were detected by western blot. Result showed that the HF diet-fed animals developed a time-dependent serum lipid increase and hepatic lipid accumulation as well as insulin resistance. Serum iron (SI), serum ferritin (SF), and transferrin saturation (TS) decreased while total iron-binding capacity (TIBC) and serum transferrin (s-TF) increased at 8 and 12 weeks in the HF diet group. The HF diet led to increased transaminases levels at 8 and 12 weeks, and iron deposition was observed in the liver, accompanied by an upregulation of ferritin light chain (FTL), hepcidin (HEPC), transferrin (TF), transferrin receptor 1 (TfR1), iron regulatory protein 1 (IRP1), hemojuvelin (HJV), and divalent metal transporter 1 (DMT1). Moreover, ferroportin (FPN1) levels were downregulated, as expected from the increased HEPC. A progressive inflammation phenotype was apparent, with increased inflammatory factors, MDA, IL-1β, IL-6, and TNF-α, in the serum and liver tissue. Concomitantly, the hepatic IKKβ/NF-κB and JAK2/STAT3 pathways were activated. In summary, we verified that HF diet induces systemic iron deficiency and hepatic iron accumulation, likely due to the activation of inflammation via the NF-κB and JAK2/STAT3 pathways. PRACTICAL APPLICATIONS: As increasing numbers of individuals consume HF diets, the health implications of this type of over nutrition become globally relevant. Using a high-fructose diet rat model, our present study reveals inflammation as the link between a HF diet and dysregulated iron metabolism. Importantly, both inflammation and disrupted iron metabolism have been shown to be pathogenic factors in nonalcoholic fatty liver disease (NAFLD). The iron regulatory hormone, HEPC, is a link between the liver, inflammation, and iron metabolism. As fructose-rich foods become increasingly abundant and people's fructose intake increases, the impact of high fructose on health requires increased attention. Little research has been conducted on the effects of fructose on iron metabolism. Our study provides useful insights into the prevention and treatment of iron metabolism disorders arising from metabolic syndrome.

MAFLD: A Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease

Fatty liver associated with metabolic dysfunction is common, affects a quarter of the population, and has no approved drug therapy. Although pharmacotherapies are in development, response rates appear modest. The heterogeneous pathogenesis of metabolic fatty liver diseases and inaccuracies in terminology and definitions necessitate a reappraisal of nomenclature to inform clinical trial design and drug development. A group of experts sought to integrate current understanding of patient heterogeneity captured under the acronym nonalcoholic fatty liver disease (NAFLD) and provide suggestions on terminology that more accurately reflects pathogenesis and can help in patient stratification for management. Experts reached consensus that NAFLD does not reflect current knowledge, and metabolic (dysfunction) associated fatty liver disease "MAFLD" was suggested as a more appropriate overarching term. This opens the door for efforts from the research community to update the nomenclature and subphenotype the disease to accelerate the translational path to new treatments.

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.

Relationship between lifestyle factors and nutritional status and non-alcoholic fatty liver disease among a group of adult Jordanians

BACKGROUND AND STUDY AIMS

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. NAFLD may progress from simple steatosis to nonalcoholic steatohepatitis, cirrhosis and finally decompensated liver failure. This study aims at assessing the relationship between lifestyle factors and nutrients intake and the development of non-alcoholic fatty liver disease (NAFLD) in a group of Jordanian adults 30-60 years of age.

PATIENTS AND METHODS

In this case-control study, a total of 120 Jordanian adults 30-60 years of age were recruited. Sixty NAFLD patients and 60 control subjects were enrolled. The diagnosis of NAFLD was made based on the basis of ultrasonography. Weight, height and waist circumference (WC) were measured and body mass index (BMI) was calculated. Nutrients intake and physical activity level were assessed using validated questionnaires.

RESULTS

The results showed that patients with NAFLD had a higher significant difference in BMI, WC, and weight compared to controls (p = 0.001). Physical activity level was significantly higher in control subjects than in cases (p = 0.001). The metabolic parameters were significantly different both groups. The mean daily intakes of macronutrients were significantly higher in cases than in control subjects (p = 0.001). A significant difference was detected in the daily intake of some vitamins and minerals among cases compared to control subjects (p < 0.05).

CONCLUSION

The present study supports the findings of the presence of a relationship between macro- and micronutrients intake and some anthropometric and biochemical variables and NAFLD.

Iron deficiency in chronic kidney disease patients with diabetes mellitus

BACKGROUNDS

Iron deficiency has been studied extensively in patients with chronic kidney disease on hemodialysis therapy. However, few studies looked at iron treatment in the non-dialysis chronic kidney disease population.

METHODS

Five hundred and eighty patients were studied (247 were diabetic persons). Patients were divided into 4 groups: non-diabetic subjects without CKD, non-diabetic ones with GFR < 60 mL/min, diabetic persons without CKD and diabetic ones with GFR < 60 mL/min). Iron deficiency was diagnosed when serum ferritin level was <100 mg/dl. It was defined as diminished iron availability when ferritin was above 100 mg/dl and serum transferrin saturation (TSAT) was <20%.

RESULTS

Anemia was more frequent in the diabetic CKD patients group (52.4%, p < 0.001). Anemia prevalence was also higher in all CKD patients as well as in diabetic patients compared with non-diabetic ones. Iron deficiency was more frequent in diabetic patients. Among CKD diabetic patients the prevalence of iron deficiency was higher than in non-diabetic CKD ones. Diminished iron availability prevalence was higher in non-diabetic patients. Logistic regression analysis showed that only sex and diabetes mellitus were independently associated with iron deficiency.

CONCLUSIONS

Anemia was more common in diabetic CKD patients. Diabetes mellitus was independently associated with iron deficiency. Surprisingly, diminished iron availability was not more frequent in diabetic patients. The physio-pathological mechanisms that could explain these findings remain to be elucidated.

Effect of iron on cholesterol 7α-hydroxylase expression in alcohol-induced hepatic steatosis in mice

Both iron and lipids are involved in the progression of alcoholic fatty liver disease (AFLD), but the interaction between iron and lipids in AFLD is unclear. Here, we tested the hypothesis that iron regulates the expression of genes involved in lipid metabolism through iron regulatory proteins (IRPs), which interact with the iron-responsive elements (IREs) in the untranslated regions (UTRs) of genes, resulting in lipid accumulation. Using "RNA structure software", we predicted the mRNA secondary structures of more than 100 genes involved in lipid metabolism to investigate whether the IRE structure exists in novel mRNAs. Cholesterol 7α-hydroxylase (Cyp7a1) has an IRE-like stem-loop, a noncanonical IRE structure, in its 3'-UTR. Cyp7a1 expression can be regulated by in vivo and in vitro iron treatment. In addition, the noncanonical IRE motif can efficiently bind both to IRP1 and IRP2. The results indicate that hepatic iron overloading in AFLD mice decreased Cyp7a1 expression and resulted in cholesterol accumulation, providing a new mechanism of iron-regulated gene transcription and translation through the interaction between iron and a noncanonical IRE structure in Cyp7a1 mRNA. This finding has significant implications in studying a proposed mechanism for the regulation of cholesterol homeostasis by an Fe/IRP/noncanonical IRE axis.

Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress

Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders.

Interstrain differences in the progression of nonalcoholic steatohepatitis to fibrosis in mice are associated with altered hepatic iron metabolism

Nonalcoholic fatty liver disease (NAFLD) is a major health problem worldwide. Currently, there is a lack of conclusive information to clarify the molecular events and mechanisms responsible for the progression of NAFLD to fibrosis and cirrhosis and, more importantly, for differences in interindividual disease severity. The aim of this study was to investigate a role of interindividual differences in iron metabolism among inbred mouse strains in the pathogenesis and severity of fibrosis in a model of NAFLD. Feeding male A/J, 129S1/SvImJ and WSB/EiJ mice a choline- and folate-deficient diet caused NAFLD-associated liver injury and iron metabolism abnormalities, especially in WSB/EiJ mice. NAFLD-associated fibrogenesis was correlated with a marked strain- and injury-dependent increase in the expression of iron metabolism genes, especially transferrin receptor (Tfrc), ferritin heavy chain (Fth1), and solute carrier family 40 (iron-regulated transporter), member 1 (Slc40a1, Fpn1) and their related proteins, and pronounced down-regulation of the iron regulatory protein 1 (IRP1), with the magnitude being A/J<129S1/SvImJ<WSB/EiJ. Mechanistically, down-regulation of IRP1 was linked to an increased expression of microRNAs miR-200a and miR-223, which was negatively correlated with IRP1. The results of this study demonstrate that the interstrain variability in the extent of fibrogenesis was associated with a strain-dependent deregulation of hepatic iron homeostasis.

The common marmoset as a model for the study of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome. The more clinically concerning form of the disease, nonalcoholic steatohepatitis (NASH), is characterized by steatosis, lobular inflammation, and ballooning degeneration. Here we describe a naturally occurring syndrome in the common marmoset that recapitulates the pathologic findings associated with NAFLD/NASH in humans. Hepatomegaly determined to result from NAFLD was observed in 33 of 183 marmosets. A comprehensive histopathologic assessment performed in 31 marmosets demonstrated that NAFLD was characterized by variably sized, Oil Red O staining cytoplasmic vacuoles and observed primarily in animals with evidence of obesity and insulin resistance. A subset of marmosets (16 of 31) also demonstrated evidence of NASH characterized by multifocal inflammation combined with ballooning hepatocellular degeneration. Marmosets with NASH demonstrated an increase in immunostaining with an antibody targeted against the human leukocyte antigens (HLA)-DP, HLA-DQ, and HLA-DR compared with marmosets without NASH (38.89 cells/10× field vs 12.05 cells/10× field, P = .05). In addition, marmosets with NASH demonstrated increased Ki-67 immunopositive cellular proliferation compared with those without (5.95 cells/10× field vs 1.53 cells/10× field, P = .0002). Finally, animals with NASH demonstrated significantly increased mean circulating serum iron levels (160.47 μg/dl, P = .008) and an increase in numbers of Prussian blue-positive Kupffer cells (9.28 cells/40× field, P = .005) relative to marmosets without NASH (97.75 μg/dl and 1.87 cells/40×, respectively). This study further characterizes the histopathology of NAFLD/NASH and suggests that the marmoset may be a valuable animal model with which to investigate the host and environmental factors contributing to the progression of NAFLD/ NASH.

Fat and iron quantification in the liver: past, present, and future

Liver fat, iron, and combined overload are common manifestations of diffuse liver disease and may cause lipotoxicity and iron toxicity via oxidative hepatocellular injury, leading to progressive fibrosis, cirrhosis, and eventually, liver failure. Intracellular fat and iron cause characteristic changes in the tissue magnetic properties in predictable dose-dependent manners. Using dedicated magnetic resonance pulse sequences and postprocessing algorithms, fat and iron can be objectively quantified on a continuous scale. In this article, we will describe the basic physical principles of magnetic resonance fat and iron quantification and review the imaging techniques of the "past, present, and future." Standardized radiological metrics of fat and iron are introduced for numerical reporting of overload severity, which can be used toward objective diagnosis, grading, and longitudinal disease monitoring. These noninvasive imaging techniques serve an alternative or complimentary role to invasive liver biopsy. Commercial solutions are increasingly available, and liver fat and iron quantitative imaging is now within reach for routine clinical use and may soon become standard of care.

High Fat Diet Induces Liver Steatosis and Early Dysregulation of Iron Metabolism in Rats

This paper is dedicated to the memory of our wonderful colleague Professor Alfredo Colonna, who passed away the same day of its acceptance. Fatty liver accumulation, inflammatory process and insulin resistance appear to be crucial in non-alcoholic fatty liver disease (NAFLD), nevertheless emerging findings pointed an important role also for iron overload. Here, we investigate the molecular mechanisms of hepatic iron metabolism in the onset of steatosis to understand whether its impairment could be an early event of liver inflammatory injury. Rats were fed with control diet or high fat diet (HFD) for 5 or 8 weeks, after which liver morphology, serum lipid profile, transaminases levels and hepatic iron content (HIC), were evaluated. In liver of HFD fed animals an increased time-dependent activity of iron regulatory protein 1 (IRP1) was evidenced, associated with the increase in transferrin receptor-1 (TfR1) expression and ferritin down-regulation. Moreover, ferroportin (FPN-1), the main protein involved in iron export, was down-regulated accordingly with hepcidin increase. These findings were indicative of an increased iron content into hepatocytes, which leads to an increase of harmful free-iron also related to the reduction of hepatic ferritin content. The progressive inflammatory damage was evidenced by the increase of hepatic TNF-α, IL-6 and leptin, in parallel to increased iron content and oxidative stress. The major finding that emerged of this study is the impairment of iron homeostasis in the ongoing and sustaining of liver steatosis, suggesting a strong link between iron metabolism unbalance, inflammatory damage and progression of disease.

FXR agonist INT-747 upregulates DDAH expression and enhances insulin sensitivity in high-salt fed Dahl rats

Aims

Genetic and pharmacological studies have shown that impairment of the nitric oxide (NO) synthase (NOS) pathway is associated with hypertension and insulin-resistance (IR). In addition, inhibition of NOS by the endogenous inhibitor, asymmetric dimethylarginine (ADMA), may also result in hypertension and IR. On the other hand, overexpression of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that metabolizes ADMA, in mice is associated with lower ADMA, increased NO and enhanced insulin sensitivity. Since DDAH carries a farnesoid X receptor (FXR)-responsive element, we aimed to upregulate its expression by an FXR-agonist, INT-747, and evaluate its effect on blood pressure and insulin sensitivity.

Methods and Results

In this study, we evaluated the in vivo effect of INT-747 on tissue DDAH expression and insulin sensitivity in the Dahl rat model of salt-sensitive hypertension and IR (Dahl-SS). Our data indicates that high salt (HS) diet significantly increased systemic blood pressure. In addition, HS diet downregulated tissue DDAH expression while INT-747 protected the loss in DDAH expression and enhanced insulin sensitivity compared to vehicle controls.

Conclusion

Our study may provide the basis for a new therapeutic approach for IR by modulating DDAH expression and/or activity using small molecules.

Markers in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD), the most common liver disorder worldwide, encompasses a spectrum of abnormal liver histology ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. Population studies show that NAFLD is strongly associated with insulin resistance, obesity, type 2 diabetes mellitus, and lipid abnormalities. In the context of hepatic steatosis, factors that promote cell injury, inflammation, and fibrosis include oxidative stress, early mitochondrial dysfunction, endoplasmic reticulum stress, iron accumulation, apoptosis, adipocytokines, and stellate cell activation. The exact NASH prevalence is unknown because of the absence of simple noninvasive diagnostic tests. Although liver biopsy is the "gold standard" for the diagnosis of NASH, other tests are needed to facilitate the diagnosis and greatly reduce the requirement for invasive liver biopsy. In addition, the development of new fibrosis markers in NASH is needed to facilitate the assessment of its progression and the effectiveness of new therapies. The aim of this chapter, which is overview of biomarkers in NASH, is to establish a systematic approach to laboratory findings of the disease.

Macrophages, TGF-β1 expression and iron deposition in development of NASH

A wide range of molecular markers and different types of cells in liver are possible factors for progression of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) development of liver fibrosis. We investigated biopsies from 57 patients with NASH. The material was obtained from livers and was proceed immunohistochemistry antibodies against CD68 and TGF-beta 1. In addition, biopsies were evaluated for iron content. Macrophages/-positive/could be found in all 57 cases. The number of macrophages in the sinusoids correlated with the degree of portal fibrosis:64.% of the patients with mild or intensive fibrosis had high infiltration with CD68-positive cells, while 100% of the patients without fibrosis hadlow infiltration (χ2=8.56; p=0.003). In specimens we, 69.% of patients with different degree of fibrosis expressed TGF-β1 in their portal tracts, and 100% of patients without fibrosis did demonstrate expression of the protein (χ2=23.7; p<0.001). Hepatic iron was found in 100% (9) of patients with intensive fibrosis vs. 10.3% of the patients mild fibrosis (χ2=23.4; p<0.001). Our results suggest that the macrophages and macrophage-derived TGF-beta1 are the major factors responsible for development of fibrosis and progression of chronic liver disease.

Early changes in the liver-soluble proteome from mice fed a nonalcoholic steatohepatitis inducing diet

Despite the increasing incidence of nonalcoholic steatohepatitis (NASH) with the rise in lifestyle-related diseases such as the metabolic syndrome, little is known about the changes in the liver proteome that precede the onset of inflammation and fibrosis. Here, we investigated early changes in the liver-soluble proteome of female C57BL/6N mice fed an NASH-inducing diet by 2D-DIGE and nano-HPLC-MS/MS. In parallel, histology and measurements of hepatic content of triglycerides, cholesterol and intermediates of the methionine cycle were performed. Hepatic steatosis manifested itself after 2 days of feeding, albeit significant changes in the liver-soluble proteome were not evident before day 10 in the absence of inflammatory or fibrotic signs. Proteomic alterations affected mainly energy and amino acid metabolism, detoxification processes, urea cycle, and the one-carbon/S-adenosylmethionine pathways. Additionally, intermediates of relevant affected pathways were quantified from liver tissue, confirming the findings from the proteomic analysis.

Review article: the iron overload syndromes

BACKGROUND

Iron overload syndromes encompass a wide range of hereditary and acquired conditions. Major developments in the field of genetics and the discovery of hepcidin as a central regulator of iron homeostasis have greatly increased our understanding of the pathophysiology of iron overload syndromes.

AIM

To review advances in iron regulation and iron overload syndrome with special emphasis on hereditary haemochromatosis, the prototype iron overload syndrome.

METHODS

A PubMed search using words such as 'iron overload', 'hemochromatosis', 'HFE', 'Non-HFE', 'secondary iron overload' was undertaken.

RESULTS

Iron overload is associated with significant morbidity and mortality. Sensitive diagnostic tests and effective therapy are widely available and can prevent complications associated with iron accumulation in end- organs. Therapeutic phlebotomy remains the cornerstone of therapy for removal of excess body iron, but novel therapeutic agents including oral iron chelators have been developed for iron overload associated with anaemia.

CONCLUSIONS

Iron overload disorders are common. Inexpensive screening tests as well as confirmatory diagnostic tests are widely available. Increased awareness of the causes and importance of early diagnosis and knowledge of the appropriate use of genetic testing are encouraged. The availability of novel treatments should increase therapeutic options for patients with iron overload disorders.

Non-alcoholic fatty liver disease: is iron relevant?

Non-alcoholic fatty liver disease (NAFLD) is a common and ubiquitous disorder (Bedogni et al. in Hepatology 42:44-52, 2005; Bellentani et al. in Ann Intern Med 132:112-117, 2000) which in a proportion of subjects leads to non-alcoholic steatohepatitis (NASH), advanced liver disease and hepatocellular carcinoma. Although the factors responsible for progression of disease are still uncertain, there is evidence that insulin resistance (IR) is a key operative mechanism (Angulo et al. in Hepatology 30:1356-1362, 1999) and that two stages are involved. The first is the accumulation of triglycerides in hepatocytes followed by a "second hit" which promotes cellular oxidative stress. Several factors may be responsible for the induction of oxidative stress but hepatic iron has been implicated in various studies. The topic is controversial, however, with early studies showing an association between hepatic iron (with or without hemochromatosis gene mutations) and the progression to hepatic fibrosis. Subsequent studies, however, could not confirm an association between the presence of hepatic iron and any of the histological determinants of NAFLD or NASH. Recent studies have reactivated interest in this subject firstly, with the demonstration that hepatic iron loading increases liver cholesterol synthesis with increased lipid deposition in the liver increasing the cellular lipid burden and secondly, a large clinical study has concluded that hepatocellular iron deposition is associated with an increased risk of hepatic fibrosis, thus, strongly supporting the original observation made over a decade ago. An improvement in insulin sensitivity has been demonstrated following phlebotomy therapy but a suitably powered controlled clinical trial is required before this treatment can be implemented.

Iron load and liver enzymes in 10- and 13-year-olds

OBJECTIVES

Iron plays a pivotal role in adult steatosis, but its role in child and adolescent steatosis is unclear. We investigated the effect of dietary iron, serum iron, and ferritin on serum transaminases and γ-glutamyltransferase in 10- and 13-year-olds.

PATIENTS AND METHODS

The study included 4894 fifth and eighth graders enrolled between 2006 and 2009 in all schools in Shunan City, Japan. Multiple regression analyses were performed with adjustments for grade, sex, z score of the body mass index, serum lipids, plasma glucose, frequency of sports activities, having a single parent, number of siblings, tobacco smoking behavior, passive smoking at home, resident areas, and schools, using linear mixed models. In addition, we analyzed ferritin and insulin resistance in randomly selected subset of participants.

RESULTS

Dietary iron intake was positively associated with serum alanine aminotransferase levels (standardized coefficient β = 2.35, P = 0.019). Serum iron concentrations were associated with transaminase and γ-glutamyltransferase levels (β = 3.22, and 4.05, respectively, P < 0.01). In the subset of 421 subjects with further serum analysis, serum ferritin levels were significantly associated with serum enzyme levels (β = 2.43-3.35; P < 0.05) and showed significant odds ratio for the elevated alanine aminotransferase levels (1.05 for 1 SD with 95% confidence intervals 1.02-1.08). However, iron load did not show a positive association with insulin resistance.

CONCLUSIONS

Although an effect size for iron is small in regression analyses, iron is implicated in increased transaminase levels in prepubertal and pubertal children.

Hepatic MR imaging for in vivo differentiation of steatosis, iron deposition and combined storage disorder: single-ratio in/opposed phase analysis vs. dual-ratio Dixon discrimination

OBJECTIVE

To assess whether in vivo dual-ratio Dixon discrimination can improve detection of diffuse liver disease, specifically steatosis, iron deposition and combined disease over traditional single-ratio in/opposed phase analysis.

METHODS

Seventy-one patients with biopsy-proven (17.7 ± 17.0 days) hepatic steatosis (n = 16), iron deposition (n = 11), combined deposition (n = 3) and neither disease (n = 41) underwent MR examinations. Dual-echo in/opposed-phase MR with Dixon water/fat reconstructions were acquired. Analysis consisted of: (a) single-ratio hepatic region-of-interest (ROI)-based assessment of in/opposed ratios; (b) dual-ratio hepatic ROI assessment of in/opposed and fat/water ratios; (c) computer-aided dual-ratio assessment evaluating all hepatic voxels. Disease-specific thresholds were determined; statistical analyses assessed disease-dependent voxel ratios, based on single-ratio (a) and dual-ratio (b and c) techniques.

RESULTS

Single-ratio discrimination succeeded in identifying iron deposition (I/O(Ironthreshold)<0.88) and steatosis (I/O(Fatthreshold>1.15)) from normal parenchyma, sensitivity 70.0%; it failed to detect combined disease. Dual-ratio discrimination succeeded in identifying abnormal hepatic parenchyma (F/W(Normalthreshold)>0.05), sensitivity 96.7%; logarithmic functions for iron deposition (I/O(Irondiscriminator)<e((0.01-F/W(Iron))/0.48)) and for steatosis (I/O(Fatdiscriminator)>e((F/W(Fat)-0.01)/0.48)) differentiated combined from isolated diseases, sensitivity 100.0%; computer-aided dual-ratio analysis was comparably sensitive but less specific, 90.2% vs. 97.6%.

CONCLUSION

MR two-point-Dixon imaging using dual-ratio post-processing based on in/opposed and fat/water ratios improved in vivo detection of hepatic steatosis, iron deposition, and combined storage disease beyond traditional in/opposed analysis.

The H63D genetic variant of the HFE gene is independently associated with the virological response to interferon and ribavirin therapy in chronic hepatitis C

BACKGROUND

Conflicting results have been reported in studies evaluating the relationship between serum markers of iron overload, liver iron deposits, and HFE mutations (C282Y and H63D) in chronic hepatitis C patients, and also their impact on the response to therapy in these patients.

AIM

To evaluate the role of HFE mutations in the severity of liver disease and in the response to therapy in chronic hepatitis C.

METHODS

Two hundred and sixty-four hepatitis C patients treated with standard interferon and ribavirin were divided into two groups according to type of antiviral response: sustained virological response (SVR) and nonresponse or relapse. We evaluated the relationship between HFE mutation and the type of antiviral response, clinical data, biochemical tests, liver histopathology, virological data, and HFE mutations.

RESULTS

Of the 264 patients, 88 (32.1%) had SVR whereas 67.9% had nonresponse or relapse. Liver iron deposits were observed in 49.2% of the patients. The factors associated with SVR were hepatitis C virus genotype 2 or 3, transferrin saturation value of 45% or less, and detection of the H63D mutation. HFE mutation was more frequent in patients with iron deposits, but without association with serum iron biochemistry or severity of liver disease. Steatosis was more frequent in patients with liver iron deposits. CONCLUSION THE: H63D mutation was an independent factor associated with SVR in chronic hepatitis C patients, as also were hepatitis C virus genotype 2 or 3 and transferrin saturation value of 45% or less. Moreover, the H63D mutation was associated with liver iron deposits.

Hepatic iron loading in mice increases cholesterol biosynthesis

Iron and cholesterol are both essential metabolites in mammalian systems, and too much or too little of either can have serious clinical consequences. In addition, both have been associated with steatosis and its progression, contributing, inter alia, to an increase in hepatic oxidative stress. The interaction between iron and cholesterol is unclear, with no consistent evidence emerging with respect to changes in plasma cholesterol on the basis of iron status. We sought to clarify the role of iron in lipid metabolism by studying the effects of iron status on hepatic cholesterol synthesis in mice with differing iron status. Transcripts of seven enzymes in the cholesterol biosynthesis pathway were significantly up-regulated with increasing hepatic iron (R(2) between 0.602 and 0.164), including those of the rate-limiting enzyme, 3-hydroxy-3-methylglutarate-coenzyme A reductase (Hmgcr; R(2) = 0.362, P < 0.002). Hepatic cholesterol content correlated positively with hepatic iron (R(2) = 0.255, P < 0.007). There was no significant relationship between plasma cholesterol and either hepatic cholesterol or iron (R(2) = 0.101 and 0.014, respectively). Hepatic iron did not correlate with a number of known regulators of cholesterol synthesis, including sterol-regulatory element binding factor 2 (Srebf2; R(2) = 0.015), suggesting that the increases seen in the cholesterol biosynthesis pathway are independent of Srebf2. Transcripts of genes involved in bile acid synthesis, transport, or regulation did not increase with increasing hepatic iron.

CONCLUSION

This study suggests that hepatic iron loading increases liver cholesterol synthesis and provides a new and potentially important additional mechanism by which iron could contribute to the development of fatty liver disease or lipotoxicity.

Serum concentration of adiponectin, leptin and resistin in obese children with non-alcoholic fatty liver disease

PURPOSE

Obesity, insulin resistance and dyslipidemia are the most significant risk factors of non-alcoholic fatty liver disease (NAFLD) but the role of adipokines in patomechanism of this disease is not clear. The aim of the study was to evaluate the serum levels of leptin, adiponectin and resistin in obese children with NAFLD.

MATERIAL/METHODS

The fasting serum levels of adipokines were determined in 44 consecutive obese children with suspected liver disease and in 24 lean controls. The degree of the ultrasound liver steatosis was graded according to Saverymuttu.

RESULTS

The fatty liver was confirmed in 33 children by ultrasonography (16 of them also showed an increased ALT activity). The serum leptin level was significantly higher and adiponectin level was lower in the obese children with NAFLD when compared to controls. Only adiponectin correlated with homeostasis model assessment of insulin resistance (HOMA-IR). Significant negative correlations were found between the ultrasonographic grades of liver steatosis and adiponectin and resistin levels. Serum adiponectin and resistin levels were lower in children with an advanced liver steatosis (grade 3, n=10) compared to patients with a mild steatosis (grade 1-2, n=23). The ability of serum adiponectin and resistin to differentiate children with an advanced liver steatosis from those with mild steatosis was significant.

CONCLUSIONS

These data suggest a role of both adiponectin and resistin in the pathogenesis of NAFLD in obese children and confirm the association between adiponectin and insulin resistance. Adiponectin and resistin may be suitable serum markers in predicting an advanced liver steatosis in children with NAFLD.

Clinical expression of insulin resistance in hepatitis C and B virus-related chronic hepatitis: differences and similarities

AIM

To investigate the prevalence of the clinical parameters of insulin resistance and diabetes in patients affected by chronic hepatitis C (CHC) or chronic hepatitis B (CHB).

METHODS

We retrospectively evaluated 852 consecutive patients (726 CHC and 126 CHB) who had undergone liver biopsy. We recorded age, sex, ALT, type 2 diabetes and/or metabolic syndrome (MS), body mass index (BMI), and apparent disease duration (ADD).

RESULTS

Age, ADD, BMI, prevalence of MS and diabetes in patients with mild/moderate liver fibrosis were significantly higher in CHC. However, the degree of steatosis and liver fibrosis evaluated in liver biopsies did not differ between CHC and CHB patients. At multivariate analysis, age, sex, BMI, ALT and diabetes were independent risk factors for liver fibrosis in CHC, whereas only age was related to liver fibrosis in CHB. We also evaluated the association between significant steatosis (>30%) and age, sex, BMI, diabetes, MS and liver fibrosis. Diabetes, BMI and liver fibrosis were associated with steatosis >30% in CHC, whereas only age and BMI were related to steatosis in CHB.

CONCLUSION

These data may indicate that hepatitis C virus infection is a risk factor for insulin resistance.

Bile acids and insulin resistance: implications for treating nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease is characterized by an accumulation of excess triglycerides in hepatocytes, and insulin resistance is now considered the fundamental operative mechanism throughout the prevalence and progression of the disease. Besides their role in dietary lipid absorption and cholesterol homeostasis, evidence has accumulated that bile acids are also signaling molecules that play two important roles in glucose and lipid metabolism: in the nuclear hormone receptors as farnesoid X receptors (FXR), as well as ligands for G-protein-coupled receptors TGR5. The activated FXR-SHP pathway regulates the enterohepatic recycling and biosynthesis of bile acids and underlies the down-regulation of hepatic fatty acid and triglyceride biosynthesis and very low density lipoprotein production mediated by sterol-regulatory element-binding protein-1c. The bile acid-TGR5-cAMP-D2 signaling pathway in human skeletal muscle in the fasting-feeding cycle increases energy expenditure and prevents obesity. Therefore, a molecular basis has been provided for a link between bile acids, lipid metabolism and glucose homeostasis, which can open novel pharmacological approaches against insulin resistance and nonalcoholic fatty liver disease.

Biomarkers of body iron stores and risk of developing type 2 diabetes

AIM

Iron may contribute to the pathogenesis of type 2 diabetes mellitus (DM) by inducing oxidative stress and interfering with insulin secretion. Elevated ferritin levels are associated with increased DM risk among healthy individuals. However, it is yet unknown if ferritin predicts DM incidence among high-risk individuals with impaired glucose tolerance (IGT). Furthermore, the association between soluble transferrin receptors (sTfR), a novel marker of iron status, and DM risk has not yet been prospectively investigated in these individuals. We conducted this study to evaluate the association between baseline levels of ferritin and sTfR and the risk of developing DM among overweight and obese individuals at high risk of DM.

METHODS

This nested case-control study (280 cases and 280 matched controls) was conducted within the placebo arm of the Diabetes Prevention Program, is a clinical trial conducted among overweight/obese individuals with IGT. Ferritin and sTfR levels were measured by immunoturbidimetric assays. Incident DM was ascertained by annual 75-g oral glucose tolerance test and semi-annual fasting glucose.

RESULTS

Compared with controls, cases had higher sTfR levels (3.50 +/- 0.07 vs. 3.30 +/- 0.06 mg/l; p = 0.03), but ferritin levels were not statistically different. The multivariable odds ratios (OR) and 95% confidence intervals (95% CI) for DM incidence comparing highest with the lowest quartiles of sTfR was 2.26 (1.37-4.01) (p-trend: 0.008).

CONCLUSIONS

Modestly elevated sTfR levels are associated with increased DM risk among overweight and obese individuals with IGT. Future studies should evaluate factors determining sTfR levels and examine if interventions that lower body iron stores reduce DM incidence.

Role of hepatic iron in non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) includes a spectrum of clinical entities ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) with possible evolution to cirrhosis and hepatocellular carcinoma. Iron is considered a putative element that interacts with oxygen radicals in inducing liver damage and fibrosis. The role of hepatic iron in the progression of NASH remains controversial, but in some patients, iron may have a role in the pathogenesis of NASH. Though genetic factors, insulin resistance, dysregulation of iron-regulatory molecules, erythrophagocytosis by Kupffer cells may be responsible for hepatic iron accumulation in NASH, exact mechanisms involved in iron overload remain to be clarified. Iron reduction therapy such as phlebotomy or dietary iron restriction may be promising in patients with NASH/NAFLD to reduce insulin resistance as well as serum transaminase activities.

Iron overload is associated with hepatic oxidative damage to DNA in nonalcoholic steatohepatitis

Several lines of evidence have suggested that oxidative stress plays an important role for the pathogenesis of nonalcoholic steatohepatitis (NASH). Therefore, by using immunohistochemical staining of liver biopsy samples, we measured hepatic 7,8-dihydro-8-oxo-2' deoxyguanosine (8-oxodG), a DNA base-modified product generated by hydroxyl radicals, of 38 NASH patients and compared with 24 simple steatosis and 10 healthy subjects. Relation of hepatic 8-oxodG with clinical, biochemical, and histologic variables and changes after iron reduction therapy (phlebotomy plus iron-restricted diet) were also examined. Hepatic 8-oxodG levels were significantly higher in NASH compared with simple steatosis (17.5 versus 2.0 8-oxodG-positive cells/10(5) microm(2); P < 0.0001). 8-oxodG was significantly related to iron overload condition, glucose-insulin metabolic abnormality, and severities of hepatic steatosis in NASH patients. Logistic regression analysis also showed that hepatic iron deposit and insulin resistance were independent variables associated with elevated hepatic 8-oxodG. After the iron reduction therapy, hepatic 8-oxodG levels were significantly decreased (from 20.7 to 13.8 positive cells/10(5) microm(2); P < 0.01) with concomitant reductions of serum transaminase levels in NASH patients. In conclusion, iron overload may play an important role in the pathogenesis of NASH by generating oxidative DNA damage and iron reduction therapy may reduce hepatocellular carcinoma incidence in patients with NASH.

Clinical expression of insulin resistance in hepatitis C and B virus-related chronic hepatitis: Differences and similarities

AIM: To investigate the prevalence of the clinical parameters of insulin resistance and diabetes in patients affected by chronic hepatitis C (CHC) or chronic hepatitis B (CHB).

METHODS: We retrospectively evaluated 852 consecutive patients (726 CHC and 126 CHB) who had undergone liver biopsy. We recorded age, sex, ALT, type 2 diabetes and/or metabolic syndrome (MS), body mass index (BMI), and apparent disease duration (ADD).

RESULTS: Age, ADD, BMI, prevalence of MS and diabetes in patients with mild/moderate liver fibrosis were significantly higher in CHC. However, the degree of steatosis and liver fibrosis evaluated in liver biopsies did not differ between CHC and CHB patients. At multivariate analysis, age, sex, BMI, ALT and diabetes were independent risk factors for liver fibrosis in CHC, whereas only age was related to liver fibrosis in CHB. We also evaluated the association between significant steatosis (> 30%) and age, sex, BMI, diabetes, MS and liver fibrosis. Diabetes, BMI and liver fibrosis were associated with steatosis > 30% in CHC, whereas only age and BMI were related to steatosis in CHB.

CONCLUSION: These data may indicate that hepatitis C virus infection is a risk factor for insulin resistance.

Comparative redox status in alcoholic liver disease and nonalcoholic fatty liver disease

PURPOSE

Altered redox status has been implicated in pathogenesis of alcoholic liver disease (ALD) as well as in nonalcoholic fatty liver disease (NAFLD). This study was planned to find the relative role of redox status in these two diseases.

METHODS

A total of 44 patients with ALD and 32 patients with NAFLD and 25 apparently healthy controls were included in the study. Redox status was estimated by measuring oxidative stress (superoxide dismutase (SOD) and lipid peroxidation products as thiobarbituric acid reactive substances (TBARS)) and antioxidant status (ferric reducing ability of plasma (FRAP) and vitamin C).

RESULTS

TBARS level was raised significantly in both ALD (3.5 (2.3-9.4) vs. 1.8 (0.5-4.1) nmol/ml; P = 0.0001) and NAFLD (5.1 (1-10.2) vs. 1.82 (0.51-4.1) nmol/ml; P = 0.0001) as compared with controls, but was not different between ALD and NAFLD. SOD was significantly higher in ALD as compared to NAFLD (2.4 (1.3-7.8) vs. 0.68 (0.05-19.1) U/ml; P = 0.0001) and controls (1.12 (0.01-3.5) U/ml; P = 0.001). FRAP was lower in ALD as compared with NAFLD (345.4 (56-615.9) vs. 434.1 (197.6-733.3) mumol of Fe(+2) liberated; P = 0.001) but similar to that of controls (340.9 (141.5-697.5) mumol of Fe(+2) liberated).

CONCLUSIONS

ALD patients have a higher degree of redox imbalance as compared with NAFLD patients.

Multiecho reconstruction for simultaneous water-fat decomposition and T2* estimation

PURPOSE

To describe and demonstrate the feasibility of a novel multiecho reconstruction technique that achieves simultaneous water-fat decomposition and T2* estimation. The method removes interference of water-fat separation with iron-induced T2* effects and therefore has potential for the simultaneous characterization of hepatic steatosis (fatty infiltration) and iron overload.

MATERIALS AND METHODS

The algorithm called "T2*-IDEAL" is based on the IDEAL water-fat decomposition method. A novel "complex field map" construct is used to estimate both R2* (1/T2*) and local B(0) field inhomogeneities using an iterative least-squares estimation method. Water and fat are then decomposed from source images that are corrected for both T2* and B(0) field inhomogeneity.

RESULTS

It was found that a six-echo multiecho acquisition using the shortest possible echo times achieves an excellent balance of short scan and reliable R2* measurement. Phantom experiments demonstrate the feasibility with high accuracy in R2* measurement. Promising preliminary in vivo results are also shown.

CONCLUSION

The T2*-IDEAL technique has potential applications in imaging of diffuse liver disease for evaluation of both hepatic steatosis and iron overload in a single breath-hold.

Iron chelation beyond transfusion iron overload

The effects of systemic iron overload in hereditary (e.g., classic HFE hemochromatosis) or acquired disorders (e.g., transfusion-dependent iron overload) are well known. Several other iron overload diseases, with an observed mild-to-moderate increase in iron in selected organs (e.g., the liver or the brain), or with "misdistribution" of iron within cells (e.g., reticuloendothelial cells) or subcellular organelles (e.g., mitochondria), have been recognized more recently. The deleterious impact of any excess iron may be high as active redox iron may directly contribute to cell damage or affect signaling pathways involved in cell necrosis-apoptosis or organ fibrosis and cancer. This article discusses the potential use of iron chelation therapy to treat iron overload from causes other than transfusion overload.

Hemochromatosis genotypes and risk of 31 disease endpoints: meta-analyses including 66,000 cases and 226,000 controls

Hemochromatosis genotypes have been associated with liver disease, diabetes mellitus, heart disease, arthritis, porphyria cutanea tarda, stroke, neurodegenerative disorders, cancer, and venous disease. We performed meta-analyses including 202 studies with 66,263 cases and 226,515 controls to examine associations between hemochromatosis genotypes C282Y/C282Y, C282Y/H63D, C282Y/wild type, H63D/H63D, and H63D/wild type versus wild type/wild type and 9 overall endpoints and 22 endpoint subgroups. We also explored potential sources of heterogeneity. For liver disease, the odds ratio for C282Y/C282Y versus wild type/wild type was 3.9 (99% confidence interval: 1.9-8.1) overall, 11 (3.7-34) for hepatocellular carcinoma, 4.1 (1.2-14) for hepatitis C, and 10 (2.1-53) for nonalcoholic steatohepatitis. For porphyria cutanea tarda, the odds ratios were 48 (24-95) for C282Y/C282Y, 8.1 (3.9-17) for C282Y/H63D, 3.6 (1.8-7.3) for C282Y/wild type, 3.0 (1.6-5.6) for H63D/H63D, and 1.7 (1.0-3.1) for H63D/wild type versus wild type/wild type. Finally, for amyotrophic lateral sclerosis, the odds ratio was 3.9 (1.2-13) for H63D/H63D versus wild type/wild type. These findings were consistent across individual studies. The hemochromatosis genotypes were not associated with risk for diabetes mellitus, heart disease, arthritis, stroke, cancer, or venous disease in the overall analyses; however, the odds ratio for C282Y/C282Y versus wild type/wild type was 3.4 (1.1-11) for diabetes mellitus among North Europeans.

CONCLUSION

In aggregate, clinically ascertained cases who are homozygous for the C282Y mutation are associated with a 4-11-fold risk of liver disease, whereas all 5 hemochromatosis genotypes are associated with a 2-48-fold risk of porphyria cutanea tarda, and H63D/H63D is associated with a 4-fold risk of amyotrophic lateral sclerosis. These results, mainly from case-control studies, cannot necessarily be extrapolated to the general population.

Iron overload and cofactors with special reference to alcohol, hepatitis C virus infection and steatosis/insulin resistance

There are several cofactors which affect body iron metabolism and accelerate iron overload. Alcohol and hepatic viral infections are the most typical examples for clarifying the role of cofactors in iron overload. In these conditions, iron is deposited in hepatocytes and Kupffer cells and reactive oxygen species (ROS) produced through Fenton reaction have key role to facilitate cellular uptake of transferrin-bound iron. Furthermore, hepcidin, antimicrobial peptide produced mainly in the liver is also responsible for intestinal iron absorption and reticuloendothelial iron release. In patients with ceruloplasmin deficiency, anemia and secondary iron overload in liver and neurodegeneration are reported. Furthermore, there is accumulating evidence that fatty acid accumulation without alcohol and obesity itself modifies iron overload states. Ineffective erythropoiesis is also an important factor to accelerate iron overload, which is associated with diseases such as thalassemia and myelodysplastic syndrome. When this condition persists, the dietary iron absorption is increased due to the increment of bone marrow erythropoiesis and tissue iron overload will thereafter occurs. In porphyria cutanea tarda, iron is secondarily accumulated in the liver.

Pathogenesis and management issues for non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has, although it is a very common disorder, only relatively recently gained broader interest among physicians and scientists. Fatty liver has been documented in up to 10 to 15 percent of normal individuals and 70 to 80 percent of obese individuals. Although the pathophysiology of NAFLD is still subject to intensive research, several players and mechanisms have been suggested based on the substantial evidence. Excessive hepatocyte triglyceride accumulation resulting from insulin resistance is the first step in the proposed ‘two hit’ model of the pathogenesis of NAFLD. Oxidative stress resulting from mitochondrial fatty acids oxidation, NF-κB-dependent inflammatory cytokine expression and adipocytokines are all considered to be the potential factors causing second hits which lead to hepatocyte injury, inflammation and fibrosis. Although it was initially believed that NAFLD is a completely benign disorder, histologic follow-up studies have showed that fibrosis progression occurs in about a third of patients. A small number of patients with NAFLD eventually ends up with end-stage liver disease and even hepatocellular carcinoma. Although liver biopsy is currently the only way to confirm the NAFLD diagnosis and distinguish between fatty liver alone and NASH, no guidelines or firm recommendations can still be made as for when and in whom it is necessary. Increased physical activity, gradual weight reduction and in selected cases bariatric surgery remain the mainstay of NAFLD therapy. Studies with pharmacologic agents are showing promising results, but available data are still insufficient to make specific recommendations; their use therefore remains highly individual.

Evaluation of a model of latent pathologic factors in relation to serum ferritin elevation

OBJECTIVES

Serum ferritin increases in various disorders and clinical conditions. However, causal associations between the serum ferritin level and clinical factors that influence serum ferritin level are not well characterized. We report a model that quantitatively analyzes the causal relations between the serum ferritin level and clinical factors.

DESIGN AND METHODS

We analyzed the ferritin level and other laboratory data in the sera of 274 patients. Structural equation modeling was used to verify causal relations and the adequacy of latent factors.

RESULTS

Three factors representing clinical status were identified: cell damage, hepatic function, and inflammation. Serum iron (SI) had the strongest effect on serum ferritin elevation. The effect of the cell damage factor on serum ferritin indicated cell destruction, and that of the hepatic function factor represented decreased serum ferritin clearance. The cell damage factor also indirectly increased the ferritin level via SI or the hepatic function factor. The total effect of the inflammatory status factor on ferritin level was very weak.

CONCLUSIONS

These causal relations may explain the mechanism of serum ferritin level elevation in various clinical conditions.

Histological assessment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an important complication of the metabolic syndrome, which is becoming an increasingly common cause of chronic liver disease. Histological changes typically mainly affect perivenular regions of the liver parenchyma and include an overlapping spectrum of steatosis, steatohepatitis and persinusoidal or pericellular fibrosis, in some cases leading to cirrhosis. Once cirrhosis has developed, typical hepatocellular changes are often no longer conspicuous, leading to such cases being mistakenly diagnosed as 'cryptogenic'. Portal inflammation, ductular reaction and periportal fibrosis can also be seen as part of the morphological spectrum of NAFLD, particularly in the paediatric population. Hepatocellular carcinoma has also been described as a complication of NAFLD-associated cirrhosis. NAFLD is also an important cofactor in other chronic liver diseases, especially hepatitis C. Histological assessments have an important role to play in the diagnosis and management of NAFLD. These include making the potentially important distinction between simple steatosis and steatohepatitis and providing pointers to the aetiology, including cases where a dual pathology exists. A number of systems have been devised for grading and staging the severity of fatty liver disease. These require further evaluation, but have a potentially important role to play in determining prognosis and monitoring therapeutic responses.

[Epidemiology and natural history of primary nonalcoholic fatty liver disease]

The clinical impact of nonalcoholic fatty liver disease depends on its prevalence and natural history. The prevalence in the adult population is estimated to be about 23% and is on the increase. Thus, it has become the most common cause of persistent elevated liver enzymes, chronic liver disease, and cryptogenic cirrhosis in developed countries. The increasing prevalence of nonalcoholic fatty liver disease, which is approaching epidemic proportions, is parallel to that of other disorders associated with insulin resistance, especially obesity and type 2 diabetes mellitus. This entity occurs in men and women equally and in all age groups. The natural history is poorly defined mainly due to the scarcity of histologic follow-up studies. Although steatosis alone has a more benign clinical course, steatohepatitis is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in a similar way to other causes of chronic liver diseases. Progression seems to be mainly dependent on the severity of histological damage at diagnosis, but age older than 40 years, obesity, and type 2 diabetes have also been associated with an increased risk of liver fibrosis and progression to cirrhosis.

[Iron overload and insulin resistance]

There is increasing evidence that moderately elevated body iron stores, below levels commonly found in genetic hemochromatosis, may be associated with adverse health outcomes. Genetic hemochromatosis, characterized by transferrin saturation (TS) greater than 45%, is most often linked to homozygosity of the HFE C282Y allele. The phenotype is also modulated by mutations of more recently discovered genes (including ferroportin, hemojuvelin, hepcidin, and transferrin receptor) and environmental factors (including alcohol, viruses, diet, blood loss). Iron overload without hemochromatosis is characterized by high levels of serum ferritin and normal TS, as seen in dysmetabolic hepatosiderosis. Elevated serum ferritin levels predict incident type 2 diabetes in prospective studies and have been associated with hypertension, dyslipidemia, glucose tolerance disturbances, central adiposity, and metabolic syndrome. High ferritin levels are not synonymous with iron overload and may in some cases be a simple marker of insulin resistance.