Non-alcoholic steatohepatitis and iron: increased prevalence of mutations of the HFE gene in non-alcoholic 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.

Targeting the regulation of iron homeostasis as a potential therapeutic strategy for nonalcoholic fatty liver disease

With aging and the increasing incidence of obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. NAFLD mainly includes simple hepatic steatosis, nonalcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma (HCC). An imbalance in hepatic iron homeostasis is usually associated with the progression of NAFLD and induces iron overload, reactive oxygen species (ROS) production, and lipid peroxide accumulation, which leads to ferroptosis. Ferroptosis is a unique type of programmed cell death (PCD) that is characterized by iron dependence, ROS production and lipid peroxidation. The ferroptosis inhibition systems involved in NAFLD include the solute carrier family 7 member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1)/coenzyme Q10 (CoQ10)/nicotinamide adenine dinucleotide phosphate (NADPH) regulatory axes. The main promotion system involved is the acyl-CoA synthetase long-chain family (ACSL4)/arachidonic lipoxygenase 15 (ALOX15) axis. In recent years, an increasing number of studies have focused on the multiple roles of iron homeostasis imbalance and ferroptosis in the progression of NAFLD. This review highlights the latest studies about iron homeostasis imbalance- and ferroptosis-associated NAFLD, mainly including the physiology and pathophysiology of hepatic iron metabolism, hepatic iron homeostasis imbalance during the development of NAFLD, and key regulatory molecules and roles of hepatic ferroptosis in NAFLD. This review aims to provide innovative therapeutic strategies for NAFLD.

Necroptosis contributes to non-alcoholic fatty liver disease pathoetiology with promising diagnostic and therapeutic functions

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent type of chronic liver disease. However, the disease is underappreciated as a remarkable chronic disorder as there are rare managing strategies. Several studies have focused on determining NAFLD-caused hepatocyte death to elucidate the disease pathoetiology and suggest functional therapeutic and diagnostic options. Pyroptosis, ferroptosis, and necroptosis are the main subtypes of non-apoptotic regulated cell deaths (RCDs), each of which represents particular characteristics. Considering the complexity of the findings, the present study aimed to review these types of RCDs and their contribution to NAFLD progression, and subsequently discuss in detail the role of necroptosis in the pathoetiology, diagnosis, and treatment of the disease. The study revealed that necroptosis is involved in the occurrence of NAFLD and its progression towards steatohepatitis and cancer, hence it has potential in diagnostic and therapeutic approaches. Nevertheless, further studies are necessary.

Prevalence and Crucial Parameters in Diabesity-Related Liver Fibrosis: A Preliminary Study

Diabetes and obesity have been recognized as confirmed risk factors for the occurrence of liver fibrosis. Despite the long-standing acknowledgment of "diabesity", the simultaneous existence of diabetes and obesity, scholarly literature has shown limited attention to this topic. The aim of this pilot study was to assess the prevalence of liver fibrosis among individuals with diabetes (specifically those who are obese) in order to identify the key factors associated with hepatofibrosis and determine the most important associations and differences between patients with and without liver fibrosis. The research included a total of 164 participants (48.17% had comorbid obesity). Liver elastography (Fibroscan) was performed on these individuals in addition to laboratory tests. Liver fibrosis was found in 34.76% of type 2 diabetes patients; male gender almost doubled the risk of hepatofibrosis (RR 1.81) and diabesity nearly tripled this risk (RR 2.81; however, in degree III of obesity, the risk was elevated to 3.65 times higher). Anisocytosis, thrombocytopenia, or elevated liver enzymes raised the incidence of liver fibrosis by 1.78 to 2.47 times. In these individuals, liver stiffness was negatively correlated with MCV, platelet count, and albumin concentration; GGTP activity and HbA1c percentage were positively correlated. The regression analysis results suggest that the concentration of albumin and the activity of GGTP are likely to have a substantial influence on the future management of liver fibrosis in patients with diabesity. The findings of this study can serve as the basis for subsequent investigations and actions focused on identifying potential therapeutic and diagnostic avenues.

AGER1 deficiency-triggered ferroptosis drives fibrosis progression in nonalcoholic steatohepatitis with type 2 diabetes mellitus

Hyperglycemia is an independent risk factor for the rapid progression of nonalcoholic steatohepatitis (NASH) to liver fibrosis with an incompletely defined mechanism. Ferroptosis is a novel form of programmed cell death that has been identified as a pathogenic mechanism in various diseases. However, the role of ferroptosis in the development of liver fibrosis in NASH with type 2 diabetes mellitus (T2DM) is unclear. Here, we observed the histopathological features of the progression of NASH to liver fibrosis as well as hepatocyte epithelial-mesenchymal transition (EMT) in a mouse model of NASH with T2DM and high-glucose-cultured steatotic human normal liver (LO2) cells. The distinctive features of ferroptosis, including iron overload, decreased antioxidant capacity, the accumulation of reactive oxygen species, and elevated lipid peroxidation products, were confirmed in vivo and in vitro. Liver fibrosis and hepatocyte EMT were markedly alleviated after treatment with the ferroptosis inhibitor ferrostatin-1. Furthermore, a decrease in the gene and protein levels of AGE receptor 1 (AGER1) was detected in the transition from NASH to liver fibrosis. Overexpression of AGER1 dramatically reversed hepatocyte EMT in high-glucose-cultured steatotic LO2 cells, whereas the knockdown of AGER1 had the opposite effect. The mechanisms underlying the phenotype appear to be associated with the inhibitory effects of AGER1 on ferroptosis, which is dependent on the regulation of sirtuin 4. Finally, in vivo adeno-associated virus-mediated AGER1 overexpression effectively relieved liver fibrosis in a murine model. Collectively, these findings suggest that ferroptosis participates in the pathogenesis of liver fibrosis in NASH with T2DM by promoting hepatocyte EMT. AGER1 could reverse hepatocyte EMT to ameliorate liver fibrosis by inhibiting ferroptosis. The results also suggest that AGER1 may be a potential therapeutic target for the treatment of liver fibrosis in patients with NASH with T2DM. Chronic hyperglycemia is associated with increased advanced glycation end products, resulting in the downregulation of AGER1. AGER1 deficiency downregulates Sirt4, which disturbs key regulators of ferroptosis (TFR-1, FTH, GPX4, and SLC7A11). These lead to increased iron uptake, decreasing the antioxidative capacity and enhanced lipid ROS production, ultimately leading to ferroptosis, which further promotes hepatocyte epithelial-mesenchymal transition and fibrosis progression in NASH with T2DM.

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.

Ferroptosis in non-alcoholic liver disease: Molecular mechanisms and therapeutic implications

Ferroptosis refers to a novel modality of regulated cell death characterized by excessive iron accumulation and overwhelming lipid peroxidation, which takes an important part in multiple pathological processes associated with cell death. Considering the crucial roles of the liver in iron and lipid metabolism and its predisposition to oxidative insults, more and more studies have been conducted to explore the relationship between ferroptosis and various liver disorders, including non-alcoholic fatty liver disease (NAFLD). With increased morbidity and high mortality rates, NAFLD has currently emerged as a global public health issue. However, the etiology of NAFLD is not fully understood. In recent years, an accumulating body of evidence have suggested that ferroptosis plays a pivotal role in the pathogenesis of NAFLD, but the precise mechanisms underlying how ferroptosis affects NAFLD still remain obscure. Here, we summarize the molecular mechanisms of ferroptosis and its complicated regulation systems, delineate the different effects that ferroptosis exerts in different stages of NAFLD, and discuss some potential effective therapies targeting ferroptosis for NAFLD treatment, which putatively points out a novel direction for NAFLD treatment.

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.

Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different

In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.

Ferroptosis plays a novel role in nonalcoholic steatohepatitis pathogenesis

Ferroptosis relies on iron, and ferroptotic cell death is triggered when the balance of the oxidation-reduction system is disrupted by excessive lipid peroxide accumulation. A close relationship between ferroptosis and nonalcoholic steatohepatitis (NASH) is formed by phospholipid peroxidation substrates, bioactive iron, and reactive oxygen species (ROS) neutralization systems. Recent studies into ferroptosis during NASH development might reveal NASH pathogenesis and drug targets. Our review summarizes NASH pathogenesis from the perspective of ferroptosis mechanisms. Further, we discuss the relationship between mitochondrial dysfunction, ferroptosis, and NASH. Finally, potential pharmacological therapies directed to ferroptosis in NASH are hypothesized.

Ferroptosis: Shedding Light on Mechanisms and Therapeutic Opportunities in Liver Diseases

Cell death is a vital physiological or pathological phenomenon in the development process of the organism. Ferroptosis is a kind of newly-discovered regulated cell death (RCD), which is different from other RCD patterns, such as apoptosis, necrosis and autophagy at the morphological, biochemical and genetic levels. It is a kind of iron-dependent mode of death mediated by lipid peroxides and lipid reactive oxygen species aggregation. Noteworthily, the number of studies focused on ferroptosis has been increasing exponentially since ferroptosis was first found in 2012. The liver is the organ that stores the most iron in the human body. Recently, it was frequently found that there are different degrees of iron metabolism disorder and lipid peroxidation and other ferroptosis characteristics in various liver diseases. Numerous investigators have discovered that the progression of various liver diseases can be affected via the regulation of ferroptosis, which may provide a potential therapeutic strategy for clinical hepatic diseases. This review aims to summarize the mechanism and update research progress of ferroptosis, so as to provide novel promising directions for the treatment of liver diseases.

Role of Ferroptosis in Non-Alcoholic Fatty Liver Disease and Its Implications for Therapeutic Strategies

Non-alcoholic fatty liver disease (NAFLD) has become the chronic liver disease with the highest incidence throughout the world, but its pathogenesis has not been fully elucidated. Ferroptosis is a novel form of programmed cell death caused by iron-dependent lipid peroxidation. Abnormal iron metabolism, lipid peroxidation, and accumulation of polyunsaturated fatty acid phospholipids (PUFA-PLs) can all trigger ferroptosis. Emerging evidence indicates that ferroptosis plays a critical role in the pathological progression of NAFLD. Because the liver is the main organ for iron storage and lipid metabolism, ferroptosis is an ideal target for liver diseases. Inhibiting ferroptosis may become a new therapeutic strategy for the treatment of NAFLD. In this article, we describe the role of ferroptosis in the progression of NAFLD and its related mechanisms. This review will highlight further directions for the treatment of NAFLD and the selection of corresponding drugs that target ferroptosis.

Ferroptosis as a new therapeutic opportunity for nonviral liver disease

Nonviral liver disease is a global public health problem due to its high mortality and morbidity. However, its underlying mechanism is unclear. Ferroptosis is a novel form of cell death that is involved in a variety of disease processes. Both abnormal iron metabolism (e.g., iron overload) and lipid peroxidation, which is induced by deletion of glutathione (GSH) or glutathione peroxidase 4 (GPX4), and the accumulation of polyunsaturated fatty acid-containing phospholipids (PUFA-PLs) trigger ferroptosis. Recently, ferroptosis has been involved in the pathological process of nonviral liver diseases [including alcohol-related liver disease (ALD); nonalcoholic fatty liver disease (NAFLD); hereditary hemochromatosis (HH); drug-, ischemia/reperfusion- or immune-induced liver injury; liver fibrosis; and liver cancer]. Hepatocyte ferroptosis is activated in ALD; NAFLD; HH; drug-, ischemia/reperfusion- or immune-induced liver injury; and liver fibrosis, whereas hepatic stellate cell and liver cancer cell ferroptosis are inhibited in liver fibrosis and liver cancer, respectively. Thus, ferroptosis is an ideal target for nonviral liver diseases. In the present review, we discuss the latest findings on ferroptosis and potential drugs targeting ferroptosis for nonviral liver diseases. This review will highlight further directions for the treatment and prevention of nonviral liver diseases.

Ferroptotic Cell Death: New Regulatory Mechanisms for Metabolic Diseases

Background:

Cell death is a fundamental biological phenomenon that contributes to the pathogenesis of various diseases. Regulation of iron and iron metabolism has received considerable research interests especially concerning the progression of metabolic diseases.

Discussion:

Emerging evidence shows that ferroptosis, a non-apoptotic programmed cell death induced by iron-dependent lipid peroxidation, contributes to the development of complex diseases such as non-alcoholic steatohepatitis, cardiomyopathy, renal ischemia-reperfusion, and neurodegenerative diseases. Therefore, inhibiting ferroptosis can improve the pathophysiology of associated metabolic diseases. This review describes the vital role of ferroptosis in mediating the development of certain metabolic diseases. Besides, the potential risk of iron and ferroptosis in atherosclerosis and cardiovascular diseases is also described. Iron overload and ferroptosis are potential secondary causes of death in metabolic diseases. Moreover, this review also provides potential novel approaches against ferroptosis based on recent research advances.

Conclusion:

Several controversies exist concerning mechanisms underlying ferroptotic cell death in metabolic diseases, particularly in atherosclerosis. Since ferroptosis participates in the progression of metabolic diseases such as non-alcoholic steatohepatitis (NASH), there is a need to develop new drugs targeting ferroptosis to alleviate such diseases.

Iron at the Interface of Hepatocellular Carcinoma

Cancer incidence and mortality are rapidly growing, with liver cancer being the sixth most diagnosed cancer worldwide and the third leading cause of cancer death in 2020. A number of risk factors have been identified that trigger the progression to hepatocellular carcinoma. In this review, we focus on iron as a potential risk factor for liver carcinogenesis. Molecules involved in the regulation of iron metabolism are often upregulated in cancer cells, in order to provide a supply of this essential trace element for all stages of tumor development, survival, proliferation, and metastasis. Thus, cellular and systemic iron levels must be tightly regulated to prevent or delay liver cancer progression. Disorders associated with dysregulated iron metabolism are characterized with increased susceptibility to hepatocellular carcinoma. This review discusses the association of iron with metabolic disorders such as hereditary hemochromatosis, non-alcoholic fatty liver disease, obesity, and type 2 diabetes, in the background of hepatocellular carcinoma.

[Cell death mechanisms in non-alcoholic steatohepatitis]

Continuous cell death associated with inflammation is a key trigger of disease progression notably in chronic liver diseases such as non-alcoholic steatohepatitis (NASH). Apoptosis has been studied as a potential target for reducing cell death in NASH. However, recent studies suggest that caspase inhibition is inefficient to treat NASH patients and may aggravate the disease by redirecting cells to alternative mechanisms of cell death. Alternative forms of lytic cell death have recently been identified and are known to induce strong inflammatory responses due to cell membrane permeabilization. Therefore, controlling lytic cell death modes offers new opportunities for potential therapeutic intervention in NASH. This review summarizes the underlying molecular mechanisms of apoptosis and lytic cell death modes, including necroptosis, pyroptosis and ferroptosis, and discusses their relevance in NASH.

Lytic cell death in metabolic liver disease

Regulated cell death is intrinsically associated with inflammatory liver disease and is pivotal in governing outcomes of metabolic liver disease. Different types of cell death may coexist as metabolic liver disease progresses to inflammation, fibrosis, and ultimately cirrhosis. In addition to apoptosis, lytic forms of hepatocellular death, such as necroptosis, pyroptosis and ferroptosis elicit strong inflammatory responses due to cell membrane permeabilisation and release of cellular components, contributing to the recruitment of immune cells and activation of hepatic stellate cells. The control of liver cell death is of fundamental importance and presents novel opportunities for potential therapeutic intervention. This review summarises the underlying mechanism of distinct lytic cell death modes and their commonalities, discusses their relevance to metabolic liver diseases of different aetiologies, and acknowledges the limitations of current knowledge in the field. We focus on the role of hepatocyte necroptosis, pyroptosis and ferroptosis in non-alcoholic fatty liver disease, alcohol-associated liver disease and other metabolic liver disorders, as well as potential therapeutic implications.

Ferroptosis in Liver Diseases: An Overview

Ferroptosis is an iron-dependent form of cell death characterized by intracellular lipid peroxide accumulation and redox imbalance. Ferroptosis shows specific biological and morphological features when compared to the other cell death patterns. The loss of lipid peroxide repair activity by glutathione peroxidase 4 (GPX4), the presence of redox-active iron and the oxidation of polyunsaturated fatty acid (PUFA)-containing phospholipids are considered as distinct fingerprints of ferroptosis. Several pathways, including amino acid and iron metabolism, ferritinophagy, cell adhesion, p53, Keap1/Nrf2 and phospholipid biosynthesis, can modify susceptibility to ferroptosis. Through the decades, various diseases, including acute kidney injury; cancer; ischemia–reperfusion injury; and cardiovascular, neurodegenerative and hepatic disorders, have been associated with ferroptosis. In this review, we provide a comprehensive analysis of the main biological and biochemical mechanisms of ferroptosis and an overview of chemicals used as inducers and inhibitors. Then, we report the contribution of ferroptosis to the spectrum of liver diseases, acute or chronic. Finally, we discuss the use of ferroptosis as a therapeutic approach against hepatocellular carcinoma, the most common form of primary liver cancer.

Hepatic ferroptosis plays an important role as the trigger for initiating inflammation in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a metabolic liver disease that progresses from simple steatosis to the disease state of inflammation and fibrosis. Previous studies suggest that apoptosis and necroptosis may contribute to the pathogenesis of NASH, based on several murine models. However, the mechanisms underlying the transition of simple steatosis to steatohepatitis remain unclear, because it is difficult to identify when and where such cell deaths begin to occur in the pathophysiological process of NASH. In the present study, our aim is to investigate which type of cell death plays a role as the trigger for initiating inflammation in fatty liver. By establishing a simple method of discriminating between apoptosis and necrosis in the liver, we found that necrosis occurred prior to apoptosis at the onset of steatohepatitis in the choline-deficient, ethionine-supplemented (CDE) diet model. To further investigate what type of necrosis is involved in the initial necrotic cell death, we examined the effect of necroptosis and ferroptosis inhibition by administering inhibitors to wild-type mice in the CDE diet model. In addition, necroptosis was evaluated using mixed lineage kinase domain-like protein (MLKL) knockout mice, which is lacking in a terminal executor of necroptosis. Consequently, necroptosis inhibition failed to block the onset of necrotic cell death, while ferroptosis inhibition protected hepatocytes from necrotic death almost completely, and suppressed the subsequent infiltration of immune cells and inflammatory reaction. Furthermore, the amount of oxidized phosphatidylethanolamine, which is involved in ferroptosis pathway, was increased in the liver sample of the CDE diet-fed mice. These findings suggest that hepatic ferroptosis plays an important role as the trigger for initiating inflammation in steatohepatitis and may be a therapeutic target for preventing the onset of steatohepatitis.

Noninvasive Differential Diagnosis of Liver Iron Contents in Nonalcoholic Steatohepatitis and Simple Steatosis Using Multiecho Dixon Magnetic Resonance Imaging

RATIONALE AND OBJECTIVES

The roles of iron stores in nonalcoholic fatty liver disease have not yet been clearly identified, and it is lack of uniform criteria and a standardized study design for assessing the liver iron content (LIC) in nonalcoholic steatohepatitis (NASH). This study was to compare LICs in biopsy-proven simple steatosis (SS) and NASH based on T₂^⁎-relaxometry.

MATERIAL AND METHODS

A total of 32 subjects divided to three groups, consisting of 10 healthy controls, 12 SS and 10 NASH. All MRI examinations were performed on a 3 T MRI with a 32-channel body coil. To measure T₂^⁎-value, we used a gradient echo sequence with six multiechoes within a single breath-hold. Hepatic iron contents among three groups were compared using Kruskal-Wallis H test and Mann-Whitney's posthoc tests. Diagnostic accuracy was determined by calculating the area under the receiver operating characteristics curve. To identify the reliability of iron measurements in the different region of interests, coefficient of variance (CV) was calculated overall CV values for the variability of measurements. Interobserver agreement and reliability were estimated by calculating the intraclass correlation coefficient.

RESULTS

The variations of all LIC measurements are not exceeded 20%, as a mean CV value 18.3%. intraclass correlation coefficients were higher than 0.9. Mean T₂^⁎-values at localized region of interests were healthy controls 45.42 ± 7.19 ms, SS 20.96 ± 4.28 ms, and NASH 15.49 ± 2.87 ms. The mean T₂^⁎-value in NASH is significantly shorter than that in SS (p = 0.008). The area under the receiver operating characteristics curve to distinguish NASH from SS was 0.908 (95% confidence interval 0.775-1.000, p = 0.001) at a cut-off of iron contents greater than 17.95 ms, and its diagnostic accuracy had 0.833 sensitivity and 0.800 specificity.

CONCLUSION

This study demonstrates that the T₂^⁎ calculation can help to differentially diagnose NASH.

Accuracy of ultrasonography in the assessment of liver fat compared with MRI

AIM

To investigate the accuracy of ultrasonography in the assessment of hepatic steatosis using magnetic resonance imaging (MRI) as standard of reference and to explore the influence of additional hepatic iron overload.

MATERIAL AND METHODS

A total of 2,783 volunteers (1,442 women, 1,341 men; mean age, 52.3±13.8 years) underwent confounder-corrected chemical-shift-encoded MRI of the liver at 1.5 T. Proton-density fat fraction (PDFF) and transverse relaxation rate (R2*) were calculated to estimate hepatic steatosis and liver iron overload, respectively. In addition, the presence of hepatic steatosis was assessed by B-mode ultrasonography. The sensitivity, specificity, and accuracy of hepatic ultrasonography were determined for different degrees of hepatic steatosis and different amounts of liver iron.

RESULTS

MRI revealed hepatic steatosis in 40% of participants (n=1,112), which was mild in 68.9% (n=766), moderate in 26.7% (n=297), and severe in 4.4% (n=49) of patients. Ultrasonography detected hepatic steatosis in 37.8% (n=1,052), corresponding to 74.5% sensitivity and 86.6% specificity. The sensitivity of ultrasound increased with the amount of hepatic fat present and was 65.1%, 95%, and 96% for low, moderate, and high fat content; whereas the specificity was constantly high at 86.6%. The diagnostic accuracy of ultrasound for detection of hepatic steatosis did not vary significantly with the amount of liver iron present.

CONCLUSION

Ultrasonography is an excellent tool to assess hepatic steatosis in the clinical setting with some limitations in patients with a low liver fat content. The detection of hepatic steatosis by ultrasonography is not influenced by liver iron.

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

BACKGROUND

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

AIMS

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

RESULTS

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

CONCLUSIONS

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

Steatosis and steatohepatitis found in adults after death due to non-burn trauma

OBJECTIVE

With the increasing prevalence of steatosis, the number of steatotic liver grafts from deceased donors is also increasing. Thus, determining the prevalence and the population risk factors of steatosis may assist in risk stratification. The aim of this study was to evaluate the prevalence and predictors of steatosis and steatohepatitis among livers from adults who died due to non-burn trauma.

METHODS

Specimens were collected from 224 adults undergoing autopsy at a regional autopsy referral center from September 2011 to April 2013. Histopathological examination was performed on six samples obtained from different lobes of each liver. The outcomes of interest were the presence of steatosis, steatohepatitis, NASH inflammation and NASH fibrosis. The main predictors were body mass index, abdominal circumference, liver weight and volume, presence of cholelithiasis, and siderosis. Our modeling strategy made use of a series of generalized linear models with a binomial family.

RESULTS

Our sample had a mean age of 40 years; steatosis was diagnosed in 48.2% of cases, and steatohepatitis was diagnosed in 2.7%. The presence of a high proportion of fatty changes was more prevalent among males and older individuals, with the most affected age group being 41-60 years. When evaluating the crude odds ratio for steatosis, the factors significantly associated with an increased risk of steatosis were greater abdominal circumference, BMI, and liver weight and the presence of siderosis.

CONCLUSION

Our study reinforces the role of older age, obesity and hepatomegaly as predictors of fatty liver disease. These variables should be considered in the assessment of fatty changes in the livers of potential liver donors.

Catalase and nonalcoholic fatty liver disease

Obesity and insulin resistance are considered the main causes of nonalcoholic fatty liver disease (NAFLD), and oxidative stress accelerates the progression of NAFLD. Free fatty acids, which are elevated in the liver by obesity or insulin resistance, lead to incomplete oxidation in the mitochondria, peroxisomes, and microsomes, leading to the production of reactive oxygen species (ROS). Among the ROS generated, H₂O₂ is mainly produced in peroxisomes and decomposed by catalase. However, when the H₂O₂ concentration increases because of decreased expression or activity of catalase, it migrates to cytosol and other organelles, causing cell injury and participating in the Fenton reaction, resulting in serious oxidative stress. To date, numerous studies have been shown to inhibit the pathogenesis of NAFLD, but treatment for this disease mainly depends on weight loss and exercise. Various molecules such as vitamin E, metformin, liraglutide, and resveratrol have been proposed as therapeutic agents, but further verification of the dose setting, clinical application, and side effects is needed. Reducing oxidative stress may be a fundamental method for improving not only the progression of NAFLD but also obesity and insulin resistance. However, the relationship between NAFLD progression and antioxidants, particularly catalase, which is most commonly expressed in the liver, remains unclear. Therefore, this review summarizes the role of catalase, focusing on its potential therapeutic effects in NAFLD progression.

Validation of water-fat MRI and proton MRS in assessment of hepatic fat and the heterogeneous distribution of hepatic fat and iron in subjects with non-alcoholic fatty liver disease

BACKGROUND

Research studies demonstrated pathologic lesions were unevenly distributed in patients with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis. As hepatic steatosis occurs prior to steatohepatitis and other late stage liver conditions, the distribution pattern of hepatic fat and iron concentration should be investigated to prevent sampling variability. The first purpose of this study was to perform comparison and validation of in-house hepatic fat measurements using water-fat MRI and MRS. The second objective was to quantify hepatic fat-fraction and T2* values in left and right liver lobes using water-fat MRI.

METHOD

Fifty-four non-alcoholic adults (27 NAFLD, age: 42.8 ± 11.8), 27 non-NAFLD, age: 45.5 ± 11.2) and 46 non-alcoholic teenagers (23 NAFLD (age: 15.4 ± 2.6), 23 non-NAFLD (age: 13.9 ± 2.3) were recruited. All participants underwent chemical shift water-fat MRI and 1H MRS at 3 T. Hepatic steatosis was defined by intrahepatic triglyceride more than the threshold of 5.56% using MRS (clinical reference) and non-alcoholic was defined by alcohol ingestion of no more than 30 g and 20 g per day for male and female respectively. Hepatic fat-fractions in left and right liver lobes were measured using regions-of-interest (ROIs) approach. Three ROIs were drawn on the fat-fraction images and duplicated on to the co-registered T2* images at the inferior right, superior right and superior left liver lobes. Comparison and validation of water-fat MRI and MRS were performed using intraclass correlation coefficient (ICC) and Bland-Altman plot. Hepatic fat-fraction and T2* measured from the ROIs were compared using repeated measures ANOVA. Independent t-test was used for between groups analysis.

RESULTS

Statistical analysis indicated good correlation (R = 0.987) and agreement (ICC = 0.982) between MRS and water-fat MRI in hepatic fat measurements. Results indicated that hepatic fat was significantly higher in the right lobe compared to the left in NAFLD adults (p < 0.001) and NAFLD teenagers (p < 0.001). For T2*, significant difference between left and right lobes was observed in NAFLD adults (p < 0.001) and non-NAFLD adults (p < 0.001) but not in teenagers.

CONCLUSION

Hepatic fat measurements using MRS and water-fat MRI are statistically equivalent. In subjects with NAFLD regardless of their age, hepatic fat is stored preferentially in the right live lobe probably due to the streamline of blood flow to the right liver. T2* value is significantly higher in the right liver lobe in adults but not in the teenagers regardless of their hepatic fat contents probably due to the longer time span of hepatic iron accumulation.

Matriptase-2 deficiency protects from obesity by modulating iron homeostasis

Alterations in iron status have frequently been associated with obesity and other metabolic disorders. The hormone hepcidin stands out as a key regulator in the maintenance of iron homeostasis by controlling the main iron exporter, ferroportin. Here we demonstrate that the deficiency in the hepcidin repressor matriptase-2 (Tmprss6) protects from high-fat diet-induced obesity. Tmprss6^−/− mice show a significant decrease in body fat, improved glucose tolerance and insulin sensitivity, and are protected against hepatic steatosis. Moreover, these mice exhibit a significant increase in fat lipolysis, consistent with their dramatic reduction in adiposity. Rescue experiments that block hepcidin up-regulation and restore iron levels in Tmprss6^−/− mice via anti-hemojuvelin (HJV) therapy, revert the obesity-resistant phenotype of Tmprss6^−/− mice. Overall, this study describes a role for matritpase-2 and hepcidin in obesity and highlights the relevance of iron regulation in the control of adipose tissue function.

Iron homeostasis dysfunctions have been associated with several metabolic disorders including obesity, steatosis and diabetes. Here the authors demonstrate that the hepcidin repressor matriptase-2 regulates adiposity and its deficiency protects mice against obesity and promotes lipolysis.

Bile acid detoxifying enzymes limit susceptibility to liver fibrosis in female SHRSP5/Dmcr rats fed with a high-fat-cholesterol diet

During middle age, women are less susceptible to nonalcoholic steatohepatitis (NASH) than men. Thus, we investigated the underlying molecular mechanisms behind these sexual differences using an established rat model of NASH. Mature female and male stroke-prone spontaneously hypertensive 5/Dmcr rats were fed control or high-fat-cholesterol (HFC) diets for 2, 8, and 14 weeks. Although HFC-induced hepatic fibrosis was markedly less severe in females than in males, only minor gender differences were observed in expression levels of cytochrome P450 enzymes (CYP)7A1, CYP8B1 CYP27A1, and CYP7B1, and multidrug resistance-associated protein 3, and bile salt export pump, which are involved in fibrosis-related bile acid (BA) kinetics. However, the BA detoxification-related enzymes UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT) 2A1, and the nuclear receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR), were strongly suppressed in HFC-fed males, and were only slightly changed in HFC-diet fed females. Expression levels of the farnesoid X receptor and its small heterodimer partner were similarly regulated in a gender-dependent fashion following HFC feeding. Hence, the pronounced female resistance to HFC-induced liver damage likely reflects sustained expression of the nuclear receptors CAR and PXR and the BA detoxification enzymes UGT and SULT.

SREBP‑2 expression pattern contributes to susceptibility of Mongolian gerbils to hypercholesterolemia

Gerbils are susceptible to dietary cholesterol and prone to hypercholesterolemia and non‑alcoholic fatty liver disease. The present study aimed to explore the role of sterol regulatory element binding protein (SREBP)‑2 and 3‑hydroxy‑3‑methylglutaryl CoA reductase (HMGCR) in hypercholesterolemia susceptibility in gerbils. Male gerbils were fed the normal diet or a high‑fat diet (HFD) for 2 weeks, or the HFD for 2 weeks followed with the normal diet for an additional 2 weeks. Serum lipid levels and hepatic fat deposition were measured, and mRNA and protein levels of SREBP‑2 and HMGCR were evaluated by quantitative polymerase chain reaction and Western blotting. In addition, the role of SREBP‑2 function in cholesterol synthesis from the gerbil primary hepatic cells was also investigated by modulation of SERBP‑2 expression via the transfection of SREBP‑2 overexpression and knockdown plasmids, respectively. The data demonstrated that the total cholesterol and low‑density lipoprotein cholesterol levels in the gerbil serum samples were rapidly and significantly elevated in response to HFD. In addition, the effect of the HFD was rapidly attenuated in the gerbils following a return to the normal diet. HMGCR expression and activation were not altered by dietary cholesterol consumption in the livers from the gerbils in model or recovery groups. HMGCR expression and activation were effectively regulated in cultured hepatic cells from the gerbils. These results indicated that the activation of SREBP‑2 to HMGCR was not terminated in gerbil livers during cholesterol intake. Therefore, stable SREBP‑2 expression contributes to the susceptibility of gerbils to hypercholesterolemia.

Prevalence of Fatty Liver Disease and Hepatic Iron Overload in a Northeastern German Population by Using Quantitative MR Imaging

Purpose To quantify liver fat and liver iron content by measurement of confounder-corrected proton density fat fraction (PDFF) and R2* and to identify clinical associations for fatty liver disease and liver iron overload and their prevalence in a large-scale population-based study. Materials and Methods From 2008 to 2013, 2561 white participants (1336 women; median age, 52 years; 25th and 75th quartiles, 42 and 62 years) were prospectively recruited to the Study of Health in Pomerania (SHIP). Complex chemical shift-encoded magnetic resonance (MR) examination of the liver was performed, from which PDFF and R2* were assessed. On the basis of previous histopathologic calibration, participants were stratified according to their liver fat and iron content as follows: none (PDFF, ≤5.1%; R2*, ≤41.0 sec^-1), mild (PDFF, >5.1%; R2*, >41 sec^-1), moderate (PDFF, >14.1%; R2*, >62.5 sec^-1), high (PDFF: >28.0%; R2*: >70.1 sec^-1). Prevalence of fatty liver diseases and iron overload was calculated (weighted by probability of participation). Clinical associations were identified by using boosting for generalized linear models. Results Median PDFF was 3.9% (range, 0.6%-41.5%). Prevalence of fatty liver diseases was 42.2% (1082 of 2561 participants); mild, 28.5% (730 participants); moderate, 12.0% (307 participants); high content, 1.8% (45 participants). Median R2* was 34.4 sec^-1 (range, 14.0-311.8 sec^-1). Iron overload was observed in 17.4% (447 of 2561 participants; mild, 14.7% [376 participants]; moderate, 0.8% [20 participants]; high content, 2.0% [50 participants]). Liver fat content correlated with waist-to-height ratio, alanine transaminase, uric acid, serum triglycerides, and blood pressure. Liver iron content correlated with mean serum corpuscular hemoglobin, male sex, and age. Conclusion In a white German population, the prevalence of fatty liver diseases and liver iron overload is 42.2% (1082 of 2561) and 17.4% (447 of 2561). Whereas liver fat is associated with predictors related to the metabolic syndrome, liver iron content is mainly associated with mean serum corpuscular hemoglobin. ^© RSNA, 2017 Online supplemental material is available for this article.

3D Multiecho Dixon for the Evaluation of Hepatic Iron and Fat in a Clinical Setting

PURPOSE

To prospectively evaluate a new 3D-multiecho-Dixon (3D-ME-Dixon) sequence for the quantification of hepatic iron and fat in a clinical setting.

MATERIALS AND METHODS

In all, 120 patients underwent 1.5T magnetic resonance imaging of the liver between December 2013 and June 2015 including the following three sequences: 3D-ME-Dixon with inline calculation of R2* and proton-density fat-fraction (PDFF) maps, single-voxel-spectroscopy (SVS), 2D multigradient-echo sequence (2D-ME-GRE). SVS and 2D-ME-GRE were used as reference for PDFF and R2*, respectively. R2*- and PDFF-values from 3D-ME-Dixon were compared with those of the reference. Linear regression analysis, Bland-Altman plots, and agreement parameters were calculated.

RESULTS

In total, 103 patients were finally included (87 men and 16 women; mean age, 50.51 years); 17/120 were excluded due to fat/water-swaps or R2*-values exceeding the constraint of 400 1/s for 3D-ME-Dixon. A strong correlation (r = 0.992, P < 0.001) between R2* of 3D-ME-Dixon and the reference 2D-ME-GRE was found. Bland-Altman analysis revealed systematically lower values for 3D-ME-Dixon (16.499%). Using an adapted threshold of 57 1/s, 3D-ME-Dixon obtained a positive/negative percentage agreement (PPA/NPA) of 84.4%/91.4% for detecting hepatic iron overload. For hepatic fat the correlation between 3D-ME-Dixon and the reference SVS was strong (r = 0.957, P < 0.001); PPA/NPA was 88.3%/91.4%.

CONCLUSION

The 3D-ME-Dixon sequence is a valuable tool for the evaluation of hepatic iron and fat in a clinical setting. Fat/water-swaps remain a drawback requiring improvements to the implementation and making it necessary to have proven conventional sequences at hand in case of an eventual occurrence.

LEVEL OF EVIDENCE

1. Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:793-800.

Associations between hemoglobin concentrations and the development of incidental metabolic syndrome or nonalcoholic fatty liver disease

AIMS

Hemoglobin (Hb) is known to be associated with both nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS). We evaluated the relationship between serum Hb levels and the development of MS or NAFLD.

METHODS

A retrospective cohort study was conducted. We recruited participants who underwent abdominal ultrasonography and blood samplings in both 2005 and 2010.

RESULTS

Graded independent relationships were observed between higher Hb levels and the incidence of MS and NAFLD. After adjusting for age, body mass index, and fasting glucose, high-density lipoprotein cholesterol and triglyceride levels, the risk of developing MS was significantly higher according to the Hb quartiles in men (P for trend=0.027). The adjusted odds ratio (OR) and 95% confidence intervals (CIs) for the highest Hb quartile was 1.81 (1.06-3.10) for women and 1.43 (1.00-2.05) for men. The risk of developing NAFLD was also significantly higher according to the Hb quartiles in men (P for trend=0.03). The adjusted OR and 95% CI for the highest Hb quartile was 1.18 (0.73-1.91) in women and 1.76 (1.16-2.66) in men.

CONCLUSIONS

The risk of developing either MS or NAFLD was significantly associated with serum Hb levels in men. These findings have implications in the clinical availability of serum Hb as a predictor of MS and NAFLD.

Association between the HFE C282Y, H63D Polymorphisms and the Risks of Non-Alcoholic Fatty Liver Disease, Liver Cirrhosis and Hepatocellular Carcinoma: An Updated Systematic Review and Meta-Analysis of 5,758 Cases and 14,741 Controls

BACKGROUND

Conflicting results have been obtained for the association between two common polymorphisms (C282Y, H63D) of human HFE (hereditary hemochromatosis) gene and the risks of the liver diseases, including non-alcoholic fatty liver disease (NAFLD), liver cirrhosis and hepatocellular carcinoma (HCC).

METHODS

An updated systematic review and meta-analysis was conducted to evaluate the potential role of HFE polymorphisms in the susceptibility to NAFLD, liver cirrhosis and HCC. After retrieving articles from online databases, eligible studies were enrolled according to the selection criteria. Stata/SE 12.0 software was utilized to perform the statistical analysis.

RESULTS

In total, 43 articles with 5,758 cases and 14,741 controls were selected. Compared with the control group, a significantly increased risk of NAFLD was observed for the C282Y polymorphism in the Caucasian population under all genetic models and for the H63D polymorphism under the allele, heterozygote and dominant models (all OR>1, Passociation<0.05). However, no significant difference between liver cirrhosis cases and the control group was observed for HFE C282Y and H63D (all Passociation>0.05). In addition, we found that HFE C282Y was statistically associated with increased HCC susceptibility in the overall population, while H63D increased the odds of developing non-cirrhotic HCC in the African population (all OR>1, Passociation<0.05). Moreover, a positive association between compound heterozygosity for C282Y/H63D and the risk of NAFLD and HCC, but not liver cirrhosis, was observed.

CONCLUSION

Our meta-analysis provides evidence that the HFE C282Y and H63D polymorphisms confer increased genetic susceptibility to NAFLD and HCC but not liver cirrhosis. Additional well-powered studies are required to confirm our conclusion.

Haemochromatosis

Haemochromatosis is now known to be an iron-storage disease with genetic heterogeneity but with a final common metabolic pathway resulting in inappropriately low production of the hormone hepcidin. This leads to increase in intestinal absorption and deposition of excessive amounts of iron in parenchymal cells which in turn results in eventual tissue damage and organ failure. A clinical enigma has been the variable clinical expression with some patients presenting with hepatic cirrhosis at a young age and others almost asymptomatic for life. Research is unravelling this puzzle by identifying environmental factors-especially alcohol consumption-and associated modifying genes that modulate phenotypic expression. A high index of suspicion is required for early diagnosis but this can lead to presymptomatic therapy and a normal life expectancy. Venesection (phlebotomy) therapy remains the mainstay of therapy, but alternative therapies are the subject of current research.

Artemisia capillaris formula inhibits hepatic steatosis via an miR‑122‑induced decrease in fatty acid synthase expression in vivo and in vitro

Non‑alcoholic fatty liver disease (NAFLD) is a widespread health concern, and there is currently insufficient understanding regarding its pathogenesis and treatment. The present study aimed to explore the effects of Artemisia capillaris formula (ACF) on high‑fat diet‑induced hepatic steatosis and fatty acid‑induced intracellular lipid accumulation, by micro (mi)RNA regulation. A total of 72 Sprague‑Dawley rats were divided into six groups (n=12/group). One group was designated as the control group and fed a normal diet, and the remaining five groups were allowed ad libitum access to a high‑fat diet for eight weeks, in order to establish an NAFLD rat model. The rats were subsequently administered polyene phosphatidylcholine (PP; 0.076 g/kg body weight/day), low dose of ACF (0.462 g/kg body weight/day), middle dose of ACF (0.924 g/kg body weight/day) or high dose of ACF (1.848 g/kg body weight/day) intragastrically for four weeks. HepG2 human hepatocellular carcinoma cells were treated with oleic acid and palm acid, followed by treatment with various concentrations of ACF. Serum alanine transaminase (ALT), aspartate aminotransferase (AST), triglycerides (TG), total cholesterol (TC), high‑density lipoprotein cholesterol (HDL‑C), low‑density lipoprotein cholesterol (LDL‑C), and steatotic HepG2 human liver carcinoma cell TC and TG levels were measured. ACF and PP treatments attenuated high‑fat diet‑induced hepatic steatosis and fatty acid‑induced intracellular lipid accumulation. A modified high‑fat diet significantly increased ALT, AST, TG, TC, LDL‑C levels and decreased HDL‑C levels. Treatment with ACF and PP abrogated the increase in liver enzymes and TG, TC and LDL‑C levels, but did not influence HDL‑C levels in a high‑fat diet induced rat model of steotosis. Steatotic HepG2 cells exhibited significantly increased levels of both TG and TC. Treatment with ACF significantly decreased TC and TG levels in vivo, and ACF and PP treatment decreased the expression levels of fatty acid synthase (FASN) and increased miR‑122 in vivo and in vitro. In conclusion, these results suggested that ACF may inhibit hepatic steatosis via miR‑122‑induced downregulation of FASN in vivo and in vitro.

Quantitative Imaging Biomarkers of NAFLD

Conventional imaging modalities, including ultrasonography (US), computed tomography (CT), and magnetic resonance (MR), play an important role in the diagnosis and management of patients with nonalcoholic fatty liver disease (NAFLD) by allowing noninvasive diagnosis of hepatic steatosis. However, conventional imaging modalities are limited as biomarkers of NAFLD for various reasons. Multi-parametric quantitative MRI techniques overcome many of the shortcomings of conventional imaging and allow comprehensive and objective evaluation of NAFLD. MRI can provide unconfounded biomarkers of hepatic fat, iron, and fibrosis in a single examination-a virtual biopsy has become a clinical reality. In this article, we will review the utility and limitation of conventional US, CT, and MR imaging for the diagnosis NAFLD. Recent advances in imaging biomarkers of NAFLD are also discussed with an emphasis in multi-parametric quantitative MRI.

[Techniques for quantification of liver fat in risk stratification of diabetics]

CLINICAL/METHODICAL ISSUE

Fatty liver disease plays an important role in the development of type 2 diabetes. Accurate techniques for detection and quantification of liver fat are essential for clinical diagnostics.

STANDARD RADIOLOGICAL METHODS

Chemical shift-encoded magnetic resonance imaging (MRI) is a simple approach to quantify liver fat content.

METHODICAL INNOVATIONS

Liver fat quantification using chemical shift-encoded MRI is influenced by several bias factors, such as T2* decay, T1 recovery and the multispectral complexity of fat.

PERFORMANCE

The confounder corrected proton density fat fraction is a simple approach to quantify liver fat with comparable results independent of the software and hardware used.

ACHIEVEMENTS

The proton density fat fraction is an accurate biomarker for assessment of liver fat.

PRACTICAL RECOMMENDATIONS

An accurate and reproducible quantification of liver fat using chemical shift-encoded MRI requires a calculation of the proton density fat fraction.

Genetic, metabolic and environmental factors involved in the development of liver cirrhosis in Mexico

Liver cirrhosis (LC) is a chronic illness caused by inflammatory responses and progressive fibrosis. Globally, the most common causes of chronic liver disease include persistent alcohol abuse, followed by viral hepatitis infections and nonalcoholic fatty liver disease. However, regardless of the etiological factors, the susceptibility and degree of liver damage may be influenced by genetic polymorphisms that are associated with distinct ethnic and cultural backgrounds. Consequently, metabolic genes are influenced by variable environmental lifestyle factors, such as diet, physical inactivity, and emotional stress, which are associated with regional differences among populations. This Topic Highlight will focus on the genetic and environmental factors that may influence the metabolism of alcohol and nutrients in the setting of distinct etiologies of liver disease. The interaction between genes and environment in the current-day admixed population, Mestizo and Native Mexican, will be described. Additionally, genes involved in immune regulation, insulin sensitivity, oxidative stress and extracellular matrix deposition may modulate the degree of severity. In conclusion, LC is a complex disease. The onset, progression, and clinical outcome of LC among the Mexican population are influenced by specific genetic and environmental factors. Among these are an admixed genome with a heterogenic distribution of European, Amerindian and African ancestry; a high score of alcohol consumption; viral infections; a hepatopathogenic diet; and a high prevalence of obesity. The variance in risk factors among populations suggests that intervention strategies directed towards the prevention and management of LC should be tailored according to such population-based features.

Genetic background in nonalcoholic fatty liver disease: A comprehensive review

In the Western world, nonalcoholic fatty liver disease (NAFLD) is considered as one of the most significant liver diseases of the twenty-first century. Its development is certainly driven by environmental factors, but it is also regulated by genetic background. The role of heritability has been widely demonstrated by several epidemiological, familial, and twin studies and case series, and likely reflects the wide inter-individual and inter-ethnic genetic variability in systemic metabolism and wound healing response processes. Consistent with this idea, genome-wide association studies have clearly identified Patatin-like phosholipase domain-containing 3 gene variant I148M as a major player in the development and progression of NAFLD. More recently, the transmembrane 6 superfamily member 2 E167K variant emerged as a relevant contributor in both NAFLD pathogenesis and cardiovascular outcomes. Furthermore, numerous case-control studies have been performed to elucidate the potential role of candidate genes in the pathogenesis and progression of fatty liver, although findings are sometimes contradictory. Accordingly, we performed a comprehensive literature search and review on the role of genetics in NAFLD. We emphasize the strengths and weaknesses of the available literature and outline the putative role of each genetic variant in influencing susceptibility and/or progression of the disease.

Nonalcoholic fatty liver disease-related cardiovascular risk: Is there an association with blood hemoglobin levels?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries. There is emerging evidence on the relationship between NAFLD and increased cardiovascular risk. NAFLD is strongly associated with metabolic syndrome, but several other entities play a role in the pathogenesis of NAFLD more than metabolic syndrome. Currently, studies suggest that elevated hemoglobin levels are associated not only with the existence of nonalcoholic steatohepatitis but also with the severity of hepatic fibrosis. In this review, we aimed to discuss the potential role of high hemoglobin levels in the pathogenesis of NAFLD and NAFLD-associated cardiovascular risk.

Composite prognostic models across the non-alcoholic fatty liver disease spectrum: Clinical application in developing countries

Heterogeneity in clinical presentation, histological severity, prognosis and therapeutic outcomes characteristic of non-alcoholic fatty liver disease (NAFLD) necessitates the development of scientifically sound classification schemes to assist clinicians in stratifying patients into meaningful prognostic subgroups. The need for replacement of invasive liver biopsies as the standard method whereby NAFLD is diagnosed, graded and staged with biomarkers of histological severity injury led to the development of composite prognostic models as potentially viable surrogate alternatives. In the present article, we review existing scoring systems used to (1) confirm the presence of undiagnosed hepatosteatosis; (2) distinguish between simple steatosis and NASH; and (3) predict advanced hepatic fibrosis, with particular emphasis on the role of NAFLD as an independent cardio-metabolic risk factor. In addition, the incorporation of functional genomic markers and application of emerging imaging technologies are discussed as a means to improve the diagnostic accuracy and predictive performance of promising composite models found to be most appropriate for widespread clinical adoption.

Liver fat quantification: Comparison of dual-echo and triple-echo chemical shift MRI to MR spectroscopy

PURPOSE

To assess the diagnostic value of MRI using dual-echo (2PD) and triple-echo (3PD) chemical shift imaging for liver fat quantification against multi-echo T2 corrected MR spectroscopy (MRS) used as the reference standard, and examine the effect of T2(*) imaging on accuracy of MRI for fat quantification.

MATERIALS AND METHODS

Patients who underwent 1.5T liver MRI that incorporated 2PD, 3PD, multi-echo T2(*) and MRS were included in this IRB approved prospective study. Regions of interest were placed in the liver to measure fat fraction (FF) with 2PD and 3PD and compared with MRS-FF. A random subset of 25 patients with a wide range of MRS-FF was analyzed with an advanced FF calculation method, to prove concordance with the 3PD. The statistical analysis included correlation stratified according to T2(*), Bland-Altman analysis, and calculation of diagnostic accuracy for detection of MRS-FF>6.25%.

RESULTS

220 MRI studies were identified in 217 patients (mean BMI 28.0±5.6). 57/217 (26.2%) patients demonstrated liver steatosis (MRS-FF>6.25%). Bland-Altman analysis revealed strong agreement between 3PD and MRS (mean±1.96 SD: -0.5%±4.6%) and weaker agreement between 2PD and MRS (4.7%±16.0%). Sensitivity of 3PD for diagnosing FF> 6.25% was higher than that of 2PD. 3PD-FF showed minor discrepancies (coefficient of variation <10%) from FF measured with the advanced method.

CONCLUSION

Our large series study validates the use of 3PD chemical shift sequence for detection of liver fat in the clinical environment, even in the presence of T2(*) shortening.

Automated two-point dixon screening for the evaluation of hepatic steatosis and siderosis: comparison with R2-relaxometry and chemical shift-based sequences

OBJECTIVES

To evaluate the automated two-point Dixon screening sequence for the detection and estimated quantification of hepatic iron and fat compared with standard sequences as a reference.

METHODS

One hundred and two patients with suspected diffuse liver disease were included in this prospective study. The following MRI protocol was used: 3D-T1-weighted opposed- and in-phase gradient echo with two-point Dixon reconstruction and dual-ratio signal discrimination algorithm ("screening" sequence); fat-saturated, multi-gradient-echo sequence with 12 echoes; gradient-echo T1 FLASH opposed- and in-phase. Bland-Altman plots were generated and correlation coefficients were calculated to compare the sequences.

RESULTS

The screening sequence diagnosed fat in 33, iron in 35 and a combination of both in 4 patients. Correlation between R2* values of the screening sequence and the standard relaxometry was excellent (r = 0.988). A slightly lower correlation (r = 0.978) was found between the fat fraction of the screening sequence and the standard sequence. Bland-Altman revealed systematically lower R2* values obtained from the screening sequence and higher fat fraction values obtained with the standard sequence with a rather high variability in agreement.

CONCLUSIONS

The screening sequence is a promising method with fast diagnosis of the predominant liver disease. It is capable of estimating the amount of hepatic fat and iron comparable to standard methods.

KEY POINTS

• MRI plays a major role in the clarification of diffuse liver disease. • The screening sequence was introduced for the assessment of diffuse liver disease. • It is a fast and automated algorithm for the evaluation of hepatic iron and fat. • It is capable of estimating the amount of hepatic fat and iron.

Treatment of Nonalcoholic Fatty Liver Disease with Total Alkaloids in Rubus aleaefolius Poir through Regulation of Fat Metabolism

Total alkaloids in Rubus aleaefolius Poir (TARAP) is a folk medicinal herb that has been used clinically in China to treat nonalcoholic fatty liver disease (NAFLD) for many years. However, the mechanism of its anti-NAFLD effect is largely unknown. In this study, we developed a NAFLD rat model by supplying a modified high-fat diet (mHFD) ad libitum for 8 weeks and evaluated the therapeutic effect of TARAP in NAFLD rats as well as the underlying molecular mechanism. We found that TARAP could reduce the serum triglycerides (TG), total cholesterol (TC), and low-density lipoprotein (LDL-C) levels and increase the serum high-density lipoprotein (HDL-C) level in NAFLD rats. In addition, TARAP treatment reduced expression of fatty acid synthetase (FAS), and acetyl-CoA carboxylase (ACC) and upregulated the expression of carnitine palmitoyltransferase (CPT). Our results suggest that regulation of lipid metabolism may be a mechanism by which TARAP treats NAFLD.

Estimation of copper and iron burden in biological samples of various stages of hepatitis C and liver cirrhosis patients

There is accumulative evidence that the metabolism of iron (Fe) and copper (Cu) is altered in human due to infections, indicating that both elements have roles in pathogenesis and progress of viral diseases. In the present study, the correlation of Cu and Fe was evaluate in biological samples (serum and scalp hair) of hepatitis C (hepatitis C virus (HCV)) patients of both genders at different stages. For comparative study, the scalp hair and serum samples of healthy individuals of same age group (30-50 years) and socioeconomic status were collected. The biological samples were analyzed for Fe and Cu by atomic absorption spectroscopy after microwave-assisted acid digestion. The validity and accuracy of methodology were checked by certified reference materials of same matrixes. The levels of Cu and Fe in biological samples were enhanced in hepatic disorder patients, including acute (after diagnosis test, anti-HCV sero-positive) hepatic fibrosis and liver cirrhosis as compared to healthy referents. The difference was significant (p < 0.01) in the case of liver cirrhotic patients. It was observed that the data of Cu and Fe in referents and patients of both genders had normal distributions. The inter-elemental correlation (r) among Cu vs Fe in serum and scalp hair samples of referents and patients were not significant in both genders (p > 0.1) except in the first stage of HCV (p < 0.1). It was concluded that the increase of Cu and Fe content in human body seems to contribute to the development of cirrhosis in patients with viral hepatitis C.

Are oxidative stress mechanisms the common denominator in the progression from hepatic steatosis towards non-alcoholic steatohepatitis (NASH)?

Non-alcoholic fatty liver disease (NAFLD) is not a single disease entity, rather it describes a spectrum of liver conditions that range from fatty liver (steatosis) to more severe steatosis coupled with marked inflammation and fibrosis [non-alcoholic steatohepatitis (NASH)] to severe liver disease such as cirrhosis and possibly hepatocellular carcinoma. Obesity, notably abdominal obesity, is a common risk factor for NAFLD. The pathogenesis from steatosis to NASH is poorly understood, and the 'two hit' model, as suggested nearly two decades ago, provides a feasible starting point for characterization of underlying mechanisms. This review will examine the oxidative stress factors ('triggers') which have been implicated as a 'second hit' in the development of primary NASH. It would be reasonable to assume that multiple, rather than single, pro-oxidative intracellular and extracellular triggers act in conjunction promoting oxidative stress that drives the development of NASH. It is likely that the common denominator of these pro-oxidative triggers is mitochondrial dysfunction. Understanding the contribution of each of these 'triggers' is an essential step in starting to understand and elucidate the mechanisms responsible for progression from steatosis to NASH, thus enabling the development of therapeutic targeting to prevent NASH development and progression.

Novel pathway for iron deficiency in pediatric non-alcoholic steatohepatitis

BACKGROUND & AIMS

Iron may be an important factor in the pathogenesis of non-alcoholic steatohepatitis (NASH) as it catalyzes the production of potent reactive oxygen species. We aim to examine iron status in pediatric NASH.

METHODS

Serum indices of NASH patients (N = 36) were compared to those in the U.S. National Health and Nutrition Examination Survey database (N = 802). Iron related gene expression was examined in NASH livers and normal livers, using microarray and quantitative real-time PCR (10 NASH livers and 6 controls). Transferrin and catalase expression were also examined in hydrogen peroxide treated HepG2 cells.

RESULTS

Serum iron concentration (P < 0.01) and soluble transferrin receptor 1 (P < 0.0001) were decreased while serum ferritin was elevated in NASH patients (P < 0.01). No detectable iron was observed in NASH liver by Perls' Prussian blue staining. Transferrin (P < 0.01) and transferrin receptor 2 (P < 0.01) mRNA were elevated in NASH patients. Of particular interest, transferrin mRNA was positively correlated with catalase mRNA (r = 0.9338, P < 0.0001). H2O2 treatment of HepG2 cells induced mRNA expression of transferrin and catalase.

CONCLUSIONS

Pediatric NASH patients exhibited decreased serum iron concentration and no detectable iron was observed in any NASH liver by Perls' Prussian blue staining. These changes are consistent with the facts that most NASH patients are obese and exhibit chronic inflammation. In line with a status of iron deficiency, gene expression studies suggested decreased expression of transferrin and transferrin receptor 2 in NASH livers. Induction of transferrin by H2O2, and consequently, decreased iron absorption, suggests a novel mechanism for iron deficiency in NASH patients.

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.