Association of apolipoprotein E polymorphisms in patients with non-alcoholic steatohepatitis

Circulating Ferritin in Patients with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

Objectives

To synthesize data on circulating ferritin between patients with histologically confirmed nonalcoholic fatty liver disease (NAFLD) and non-NAFLD controls.

Methods

A systematic literature search was conducted in PubMed, Scopus, and the Cochrane Library. Thirty-one studies comprising data on 5631 individuals (2929 biopsy-proven NAFLD patients and 2702 controls) were included in the meta-analysis.

Results

Higher circulating ferritin levels were observed in NAFLD patients than in controls [standardized mean difference (SMD) 1.14; 95% confidence interval (95% CI) 0.73-1.55], in patients with simple nonalcoholic fatty liver (NAFL) than in controls (SMD 0.57; 95% CI 0.34-0.80), in patients with nonalcoholic steatohepatitis (NASH) than in controls (SMD 0.95; 95% CI 0.69-1.22), and in NASH than in NAFL patients (SMD 0.62; 95% CI 0.25-0.99). There was moderate-to-high heterogeneity among studies in the above pairs of comparisons (I2 = 68-97%); no risk of publication bias was observed by Egger's test (P = 0.81, P = 0.72, P = 0.59, P = 0.42, respectively). The heterogeneity was reduced in the subgroup of biopsy-proven controls in all pairs of comparisons (I2 = 0-65%). The heterogeneity was also reduced after excluding studies with the Newcastle-Ottawa Scale (NOS) score <7 (n = 10) for the comparison of NAFLD patients vs. controls (I2 = 54%, P = 0.02). The meta-regression analysis revealed that the male ratio was positively associated with ferritin SMD in the comparison between NAFLD patients and controls and accounted for 32.7% (P = 0.002) of the heterogeneity in this pair of comparison.

Conclusions

Circulating ferritin was higher in NAFLD (or NAFL or NASH) patients compared with controls. Higher levels of circulating ferritin were also associated with the severity of the disease, which, however, should be cautiously interpreted.PROSPERO registration ID: CRD42022354025.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Human APOE4 Protects High-Fat and High-Sucrose Diet Fed Targeted Replacement Mice against Fatty Liver Disease Compared to APOE3

Recent genome- and exome-wide association studies suggest that the human APOE ε4 allele protects against non-alcoholic fatty liver disease (NAFLD), while ε3 promotes hepatic steatosis and steatohepatitis. The present study aimed at examining the APOE genotype-dependent development of fatty liver disease and its underlying mechanisms in a targeted replacement mouse model. Male mice expressing the human APOE3 or APOE4 protein isoforms on a C57BL/6J background and unmodified C57BL/6J mice were chronically fed a high-fat and high-sucrose diet to induce obesity. After 7 months, body weight gain was more pronounced in human APOE than endogenous APOE expressing mice with elevated plasma biomarkers suggesting aggravated metabolic dysfunction. APOE3 mice exhibited the highest liver weights and, compared to APOE4, massive hepatic steatosis. An untargeted quantitative proteome analysis of the liver identified a high number of proteins differentially abundant in APOE3 versus APOE4 mice. The majority of the higher abundant proteins in APOE3 mice could be grouped to inflammation and damage-associated response, and lipid storage, amongst others. Results of the targeted qRT-PCR and Western blot analyses contribute to the overall finding that APOE3 as opposed to APOE4 promotes hepatic steatosis, inflammatory- and damage-associated response signaling and fibrosis in the liver of obese mice. Our experimental data substantiate the observation of an increased NAFLD-risk associated with the human APOEε3 allele, while APOEε4 appears protective. The underlying mechanisms of the protection possibly involve a higher capacity of nonectopic lipid deposition in subcutaneous adipose tissue and lower hepatic pathogen recognition in the APOE4 mice.

Bombax ceiba Linn. leaf extract rich in phenolic compounds to mitigate non-alcoholic fatty liver-related complications in experimental model

OBJECTIVES

Obesity, diabetes mellitus, insulin resistance (IR), and hypertriglyceridemia are common features observed in non-alcoholic fatty liver diseases (NAFLD). There is a critical medical necessity to find novel therapeutics that can halt the development of NAFLD.

METHODS

Bombax ceiba Linn. leaf extract was prepared and its phytochemical profile was determined. Standard and high carbohydrate high-fat diets (HCHF) were prepared. Rats were fed HCHF for 18 weeks to induce a non-alcoholic fatty liver (NAFL) model. Forty male rats were divided into control, B. ceiba Linn. leaf extract, NAFL, prophylactic, and treated groups. Serum fasting blood sugar (FBS), insulin, insulin resistance (HOMA-IR), cholesterol, high-density lipoprotein (HDL), triglycerides (TG), low density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), intelectin-1 (ITLN1), p38 MAP kinase (MAPK), peroxisome proliferator-activated receptor alpha (PPAR-α), and interleukin-6 (IL-6) were evaluated.

RESULTS

Data obtained showed that HCHF-induced NAFL resulting in a significant increase in FBS, serum insulin, HOMA-IR, cholesterol, LDL, TG, ALT, AST, and IL-6 and a significant decrease in serum levels of HDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the control group. The analysis of B. ceiba Linn. leaf extract showed high content of phenol compounds which may cause a significant decrease in the levels of FBS, insulin, HOMA-IR values, lipid profile, and levels of IL-6 while a significant increase in serum levels of LDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the NAFL group.

CONCLUSIONS

B. ceiba Linn. Leaf extract is a highly protective and promising therapeutic agent against inflammation and oxidative stress in the NAFLD model induced by HCHF.

Genetic Markers Predisposing to Nonalcoholic Steatohepatitis

The growing prevalence of nonalcoholic fatty liver disease (NAFLD) has sparked interest in understanding genetics and epigenetics associated with the development and progression of the disease. A better understanding of the genetic factors related to progression will be beneficial in the risk stratification of patients. These genetic markers can also serve as potential therapeutic targets in the future. In this review, we focus on the genetic markers associated with the progression and severity of NAFLD.

Associations of different serum folate forms with indices of nonalcoholic fatty liver disease and advanced fibrosis

OBJECTIVE

We aim to examine the associations of different serum folate forms (total folate, 5-methyltetrahydrofolate [5-mTHF] and unmetabolized folic acid [UMFA]), with the prevalence of nonalcoholic fatty liver disease (NAFLD) and advanced fibrosis.

METHODS

This cross-sectional analysis was conducted in 6610 participants aged ≥ 18 years from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) database. NAFLD was defined as a United States fatty liver index (USFLI) ≥ 30. Advanced fibrosis was defined as a Fibrosis-4 score (FIB-4) > 3.25, a NAFLD Fibrosis Score (NFS) > 0.676, and a Hepamet Fibrosis Score (HFS) ≥ 0.47, respectively.

RESULTS

The prevalence of NAFLD was 34.5%. Overall, serum total folate and 5-mTHF were inversely associated with the prevalence of NAFLD (both P for trend across quartiles <0.001). A similar trend was found for advanced fibrosis based on NFS and HFS (both P for trend across quartiles <0.05). However, a higher concentration of UMFA was significantly related to a higher prevalence of NAFLD (P for trend across quartiles =0.004). A similar relation was found for advanced fibrosis based on NFS (P for trend across quartiles =0.024).

CONCLUSIONS

Higher concentrations of serum total folate and 5-mTHF were associated with a lower prevalence of NAFLD and advanced fibrosis, while a higher concentration of UMFA was related to a higher prevalence of NAFLD.

Bi-directional causal effect between vitamin B12 and non-alcoholic fatty liver disease: Inferring from large population data

Objectives

Many observational studies evaluate the association between vitamin B12 and non-alcoholic fatty liver disease (NAFLD). However, the causality of this association remains uncertain, especially in European populations. We conducted a bidirectional Mendelian randomization study to explore the association between vitamin B12 and NAFLD.

Methods

Two-sample Mendelian randomization study was conducted. Summary statistics for vitamin B12 were acquired from a genome-wide association studies (GWAS) meta-analysis including 45,576 subjects. Summary-level data for NAFLD was obtained from a GWAS meta-analysis of 8,434 cases and 770,180 non-cases and another GWAS meta-analysis of 1,483 cases and 17,781 non-cases. Summary-level data for 4 enzymes including alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma glutamyltransferase (GGT), was available from the UK Biobank. Inverse variance weighting (as main analysis), weighted median estimate, robust adjusted profile score, MR-Egger, and MR-PRESSO (sensitivity analyses) were performed to calculate causal estimates.

Results

Genetically predicted higher vitamin B12 concentrations were consistently associated with an increased NAFLD in two sources. The combined odds ratio (OR) of NAFLD was 1.30 (95% confidence interval (CI), 1.13 to 1.48; p < 0.001) per SD-increase in vitamin B12 concentrations. Genetic liability to NAFLD was also positively associated with vitamin B12 concentrations (Beta 0.08, 95%CI, 0.01 to 0.16; p = 0.034). Sensitivity analyses also revealed consistent results. Genetically predicted vitamin B12 concentrations showed no significant association with liver enzymes.

Conclusion

The present study indicates that increased serum vitamin B12 concentrations may play a role in NAFLD risk. NAFLD also has a causal impact on elevated vitamin B12 concentrations in the circulation. Notably, vitamin B12 concentrations imply the levels of vitamin B12 in the circulation, and higher intake of vitamin B12 may not directly lead to higher levels of serum vitamin B12, instead the higher levels of vitamin B12 in the circulation may be caused by the dysregulation of the metabolism of this vitamin in this study. There exist bidirectional causal effects between serum vitamin B12 concentrations and risk of NAFLD in European individuals.

Serum concentrations of folic acid and cobalamin and energy metabolism of ewes as a function of the energy density of the diet, peripartum period, and pregnancy toxemia

The aim of this study was to determine the serum levels of folic acid, cobalamin, and indicators of energy metabolism during the peripartum period of ewes submitted to different diets and with or without pregnancy toxemia. Forty Santa Inês ewes were divided into three groups, a group of 20 animals fed only roughage-diet with low energy density (G1), a group of 10 ewes submitted to diet containing roughage and concentrate-diet with high energy density (G2), and a group of 10 ewes with diagnosis of pregnancy toxemia (PT) (G3). In the ewes of groups G1 and G2, blood samples were collected -30, -15, -7 days pre-partum, on the day of partum, and 7, 15, and 30 days postpartum; blood samples from G3 animals were collected during the veterinary clinic care. Significant variations were observed in the plasma concentration of glucose and serum folic acid, cobalamin, fructosamine, NEFA, and β-hydroxybutyrate in the groups fed diets with different energy levels, with and without PT (P < 0.05). A positive correlation of folic acid and cobalamin was observed with plasma glucose and serum NEFA concentrations, in addition to negative correlation of glucose with NEFA and β-hydroxybutyrate and positive correlation between the latter biomarkers of energy metabolism. The ewes diagnosed with PT showed higher levels of folic acid, NEFA, and β-hydroxybutyrate (P < 0.05). Ewes fed diet containing roughage and concentrate present higher serum levels of folic acid, cobalamin, and glucose, in the pre-partum period and in the lactation period. The results obtained contribute to better understanding of the application of blood concentration tests for folic acid and cobalamin in the energy metabolism and in PT in ewes.

Homocysteine, folate, and nonalcoholic fatty liver disease: a systematic review with meta-analysis and Mendelian randomization investigation

BACKGROUND

Circulating concentrations of homocysteine and folate are inconsistently associated with the risk of nonalcoholic fatty liver disease (NAFLD) in observational studies.

OBJECTIVES

We conducted a meta-analysis and Mendelian randomization (MR) analyses to examine these associations.

METHODS

We performed a meta-analysis of observational studies identified from 3 databases to evaluate the associations of serum homocysteine and folate concentrations with NAFLD from inception to 7 April 2022. We conducted MR analyses to strengthen the causal inference in these associations. Independent single-nucleotide polymorphisms without linkage disequilibrium (r2 < 0.01) that were strongly associated (P < 5 × 10-8) with serum homocysteine (n = 13) and folate (n = 2) concentrations were selected as instrumental variables from 2 meta-analyses of genome-wide association studies (GWASs) of 44,147 and 37,645 individuals of European ancestry, respectively. Data on NAFLD were obtained from a GWAS of 8434 NAFLD cases and 770,180 controls of European ancestry. We further included 4 liver enzymes as secondary outcomes from a GWAS of 361,194 individuals with European descent.

RESULTS

Twenty-two observational studies comprising 30,368 participants were included in the meta-analysis. There was a positive association between serum homocysteine and NAFLD risk (n = 20; OR: 1.96; 95% CI: 1.57, 2.45) and an inverse association between serum folate and NAFLD risk (n = 12; OR: 0.75; 95% CI: 0.58, 0.99). In MR analysis, the ORs of NAFLD were 1.17 (95% CI: 1.01, 1.36) and 0.75 (95% CI: 0.55, 1.02) per 1-SD increment of genetically predicted circulating concentrations of homocysteine and folate, respectively. Each 1-SD increase of genetically predicted circulating homocysteine and folate conferred a change in ALT concentrations of 0.62 U/L (95% CI: 0.20, 1.04) and -0.84 U/L (95% CI: -0.14, -1.54).

CONCLUSIONS

This study suggests a potential role of circulating homocysteine and possibly folate in NAFLD, which calls for future clinical exploration of the possibility of lowering homocysteine concentrations to prevent NAFLD. This systematic review was registered at PROSPERO as CRD42021296434.

The genetic interactions between non-alcoholic fatty liver disease and cardiovascular diseases

The ongoing debate on whether non-alcoholic fatty liver disease (NAFLD) is an active contributor or an innocent bystander in the development of cardiovascular disease (CVD) has sparked interests in understanding the common mediators between the two biologically distinct entities. This comprehensive review identifies and curates genetic studies of NAFLD overlapping with CVD, and describes the colinear as well as opposing correlations between genetic associations for the two diseases. Here, CVD described in relation to NAFLD are coronary artery disease, cardiomyopathy and atrial fibrillation. Unique findings of this review included certain NAFLD susceptibility genes that possessed cardioprotective properties. Moreover, the complex interactions of genetic and environmental risk factors shed light on the disparity in genetic influence on NAFLD and its incident CVD. This serves to unravel NAFLD-mediated pathways in order to reduce CVD events, and helps identify targeted treatment strategies, develop polygenic risk scores to improve risk prediction and personalise disease prevention.

The National Consensus statement on the management of adult patients with non-alcoholic fatty liver disease and main comorbidities

The National Consensus was prepared with the participation of the National Medical Association for the Study of the Multimorbidity, Russian Scientific Liver Society, Russian Association of Endocrinologists, Russian Association of Gerontologists and Geriatricians, National Society for Preventive Cardiology, Professional Foundation for the Promotion of Medicine Fund PROFMEDFORUM. The aim of the multidisciplinary consensus is a detailed analysis of the course of non-alcoholic fatty liver disease (NAFLD) and the main associated conditions. The definition of NAFLD is given, its prevalence is described, methods for diagnosing its components such as steatosis, inflammation and fibrosis are described. The association of NAFLD with a number of cardio-metabolic diseases (arterial hypertension, atherosclerosis, thrombotic complications, type 2 diabetes mellitus (T2DM), obesity, dyslipidemia, etc.), chronic kidney disease (CKD) and the risk of developing hepatocellular cancer (HCC) were analyzed. The review of non-drug methods of treatment of NAFLD and modern opportunities of pharmacotherapy are presented. The possibilities of new molecules in the treatment of NAFLD are considered: agonists of nuclear receptors, antagonists of pro-inflammatory molecules, etc. The positive properties and disadvantages of currently used drugs (vitamin E, thiazolidinediones, etc.) are described. Special attention is paid to the multi-target ursodeoxycholic acid (UDCA) molecule in the complex treatment of NAFLD as a multifactorial disease. Its anti-inflammatory, anti-oxidant and cytoprotective properties, the ability to reduce steatosis an independent risk factor for the development of cardiovascular pathology, reduce inflammation and hepatic fibrosis through the modulation of autophagy are considered. The ability of UDCA to influence glucose and lipid homeostasis and to have an anticarcinogenic effect has been demonstrated. The Consensus statement has advanced provisions for practitioners to optimize the diagnosis and treatment of NAFLD and related common pathogenetic links of cardio-metabolic diseases.

Genome-Wide Association Study of NAFLD Using Electronic Health Records

Genome-wide association studies (GWAS) have identified several risk loci for nonalcoholic fatty liver disease (NAFLD). Previous studies have largely relied on small sample sizes and have assessed quantitative traits. We performed a case-control GWAS in the UK Biobank using recorded diagnosis of NAFLD based on diagnostic codes recommended in recent consensus guidelines. We performed a GWAS of 4,761 cases of NAFLD and 373,227 healthy controls without evidence of NAFLD. Sensitivity analyses were performed excluding other co-existing hepatic pathology, adjusting for body mass index (BMI) and adjusting for alcohol intake. A total of 9,723,654 variants were assessed by logistic regression adjusted for age, sex, genetic principal components, and genotyping batch. We performed a GWAS meta-analysis using available summary association statistics. Six risk loci were identified (P < 5*10-8 ) (apolipoprotein E [APOE], patatin-like phospholipase domain containing 3 [PNPLA3, transmembrane 6 superfamily member 2 [TM6SF2], glucokinase regulator [GCKR], mitochondrial amidoxime reducing component 1 [MARC1], and tribbles pseudokinase 1 [TRIB1]). All loci retained significance in sensitivity analyses without co-existent hepatic pathology and after adjustment for BMI. PNPLA3 and TM6SF2 remained significant after adjustment for alcohol (alcohol intake was known in only 158,388 individuals), with others demonstrating consistent direction and magnitude of effect. All six loci were significant on meta-analysis. Rs429358 (P = 2.17*10-11 ) is a missense variant within the APOE gene determining ϵ4 versus ϵ2/ϵ3 alleles. The ϵ4 allele of APOE offered protection against NAFLD (odds ratio for heterozygotes 0.84 [95% confidence interval 0.78-0.90] and homozygotes 0.64 [0.50-0.79]). Conclusion: This GWAS replicates six known NAFLD-susceptibility loci and confirms that the ϵ4 allele of APOE is associated with protection against NAFLD. The results are consistent with published GWAS using histological and radiological measures of NAFLD, confirming that NAFLD identified through diagnostic codes from consensus guidelines is a valid alternative to more invasive and costly approaches.

Lrp6 Genotype affects Individual Susceptibility to Nonalcoholic Fatty Liver Disease and Silibinin Therapeutic Response via Wnt/β-catenin-Cyp2e1 Signaling

Background: Nonalcoholic fatty liver disease (NAFLD) is a serious threat to human health worldwide, with a high genetic susceptibility. Rs2302685, a functional germline variant of LRP6, has been recently found to associate with NAFLD risk. This study was aimed to clarify the underlying mechanism associated with rs2302685 risk and its impact on pharmacotherapy in treatment of NAFLD.

Methods: Venous blood samples were collected from NAFLD and non-NAFLD patients for SNP genotyping by using mass spectrometry. The Lrp6-floxdel mouse (Lrp6^(+/-)) was generated to model the partial function associated with human rs2302685. The liver injury and therapeutic effects of silibinin were compared between Lrp6^(+/-) and Lrp6^(+/+) mice received a methionine-choline deficient (MCD) diet or normal diet. The effect of Lrp6 functional alteration on Wnt/β-catenin-Cyp2e1 signaling activities was evaluated by a series of cellular and molecular assays.

Results: The T allele of LRP6 rs2302685 was confirmed to associate with a higher risk of NAFLD in human subjects. The carriers of rs2302685 had reduced level of AST and ALT as compared with the noncarriers. The Lrp6^(+/-) mice exhibited a less severe liver injury induced by MCD but a reduced response to the treatment of silibinin in comparison to the Lrp6^(+/+) mice, suggesting Lrp6 as a target of silibinin. Wnt/β-catenin-Cyp2e1 signaling together with ROS generation could be exacerbated by the overexpression of Lrp6, while decreased in response to Lrp6 siRNA or silibinin treatment under NAFLD modeling.

Conclusions: The Lrp6 function affects individual susceptibility to NAFLD and the therapeutic effect of silibinin through the Wnt/β-catenin-Cyp2e1 signaling pathway. The present work has provided an underlying mechanism for human individual susceptibility to NAFLD associated with Lrp6 polymorphisms as well as a rationale for the effective use of silibinin in NAFLD patients.

Association between apolipoprotein E gene polymorphism and nonalcoholic fatty liver disease in Southern China: A case-control study

BACKGROUND

Apolipoprotein E (ApoE) polymorphisms have been reported to be associated with nonalcoholic fatty liver disease (NAFLD), but the conclusions of studies are inconsistent in different regions. The present study aims to investigate the role of ApoE genotypes on NAFLD in southern China.

METHODS

A total of 1064 subjects including 372 NAFLD patients and 692 controls who attended Meizhou People's Hospital located in southern China from March 1, 2016 to April 30, 2020 were enrolled in this study. The ApoE genotypes were detected and the laboratory parameters were examined.

RESULTS

Significant differences were observed between NAFLD patients and controls in the prevalence of ε3/ε3 (p < 0.001) and ε3/ε4 (p = 0.004). NAFLD patients presented higher frequency of ε4 allele than controls (p = 0.013). Logistic regression analysis suggested that ε3/ε3 was an independent risk factor (OR: 1.435, 95% CI: 1.084-1.891, p = 0.010), while ε3/ε4 was an independent protective factor (OR: 0.578, 95% CI: 0.404-0.828, p = 0.003) for development of NAFLD. In addition, allele ε4 showed a protective effect on NAFLD with an adjusted OR of 0.588 (95% CI: 0.420-0.824, p = 0.002).

CONCLUSION

Our results suggested that ApoE genotype was associated with the development of NAFLD in the population of southern China. Individuals carrying ε3/ε3 were at higher risk of NAFLD, while those carrying ε3/ε4 were at lower risk of NAFLD.

VITAMIN B12 AND HOMOCYSTEINE LEVELS IN PATIENTS WITH NAFLD: A SYSTEMATIC REVIEW AND METANALYSIS

BACKGROUND

The vitamin B12 absorption can be affected in patients with nonalcoholic fatty liver disease (NAFLD), and low serum vitamin B12 levels has been related to the high homocysteine (HCY) levels and to the degree of NAFLD.

OBJECTIVE

To carry out a systematic review and metanalysis of serum vitamin B12 and HCY levels in patients with NAFLD.

METHODS

Original studies including serum vitamin B12 and HCY levels in humans with NAFLD were included. The searches were performed in four databases.

RESULTS

159 studies were identified, and after excluding the duplicates and non-eligible titles, eight original articles were included. Six out of eight showed higher B12 levels in NAFLD patients (404.9±136.2 pg/mL in relation to controls 353.91±117.3 pg/mL). Seven of the eight studies also showed higher HCY levels in NAFLD patients (14.2±3.44 umol/L in relation to controls 11.05±3.6 umol/L). The results for serum vitamin B12 and HCY levels were submitted to metanalysis, showing no difference in the vitamin B12 levels between patients with NAFLD and controls. However, the levels of Hcy were higher in NAFLD patients than in controls.

CONCLUSION

There was no relashionship between the vitamin B12 levels and NAFLD. The levels of HCY were significantly higher in patients with NAFLD, suggesting this could be a potential marker for liver damage.

Allele-specific variation at APOE increases nonalcoholic fatty liver disease and obesity but decreases risk of Alzheimer's disease and myocardial infarction

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease and is highly correlated with metabolic disease. NAFLD results from environmental exposures acting on a susceptible polygenic background. This study performed the largest multiethnic investigation of exonic variation associated with NAFLD and correlated metabolic traits and diseases. An exome array meta-analysis was carried out among eight multiethnic population-based cohorts (n = 16 492) with computed tomography (CT) measured hepatic steatosis. A fixed effects meta-analysis identified five exome-wide significant loci (P < 5.30 × 10-7); including a novel signal near TOMM40/APOE. Joint analysis of TOMM40/APOE variants revealed the TOMM40 signal was attributed to APOE rs429358-T; APOE rs7412 was not associated with liver attenuation. Moreover, rs429358-T was associated with higher serum alanine aminotransferase, liver steatosis, cirrhosis, triglycerides and obesity; as well as, lower cholesterol and decreased risk of myocardial infarction and Alzheimer's disease (AD) in phenome-wide association analyses in the Michigan Genomics Initiative, United Kingdom Biobank and/or public datasets. These results implicate APOE in imaging-based identification of NAFLD. This association may or may not translate to nonalcoholic steatohepatitis; however, these results indicate a significant association with advanced liver disease and hepatic cirrhosis. These findings highlight allelic heterogeneity at the APOE locus and demonstrate an inverse link between NAFLD and AD at the exome level in the largest analysis to date.

Impact of apolipoprotein E genetic polymorphisms on liver disease: An essential review

Cirrhosis is an advanced stage of liver disease, compromising liver function with systemic health implications and poor quality of life. Hepatitis C virus (HCV) infection and alcoholic liver disease are the main causes of this pathology. However, since genetic factors may play a large role in the progression and severity of liver disease, and as apolipoprotein E (apoE) has been recognised to be mainly synthesised in the liver, apoE polymorphism studies are important to better understand the causal mechanisms in liver diseases. In this review, we summarise up-to-date studies addressing how apoE polymorphisms influence liver cirrhosis and liver transplantation outcomes and potential protective mechanisms. Although more clinical studies are needed to support these findings, the apoE ɛ4 allele seems to be protective against the progression of liver cirrhosis in the majority of aetiologies and the postoperative serum apoE phenotype of the transplanted subject receptors was converted to that of the donor, indicating that >90% of apoE in plasma is synthesised in the hepatic system.

Non-Alcoholic Steatohepatitis: A Review of Its Mechanism, Models and Medical Treatments

Non-alcoholic steatohepatitis (NASH) develops from non-alcoholic fatty liver disease (NAFLD). Currently, around 25% of the population is estimated to have NAFLD, and 25% of NAFLD patients are estimated to have NASH. NASH is typically characterized by liver steatosis inflammation, and fibrosis driven by metabolic disruptions such as obesity, diabetes, and dyslipidemia. NASH patients with significant fibrosis have increased risk of developing cirrhosis and liver failure. Currently, NASH is the second leading cause for liver transplant in the United States. More importantly, the risk of developing hepatocellular carcinoma from NASH has also been highlighted in recent studies. Patients may have NAFLD for years before progressing into NASH. Although the pathogenesis of NASH is not completely understood, the current “multiple-hits” hypothesis suggests that in addition to fat accumulation, elevated oxidative and ER stress may also drive liver inflammation and fibrosis. The development of clinically relevant animal models and pharmacological treatments for NASH have been hampered by the limited understanding of the disease mechanism and a lack of sensitive, non-invasive diagnostic tools. Currently, most pre-clinical animal models are divided into three main groups which includes: genetic models, diet-induced, and toxin + diet-induced animal models. Although dietary models mimic the natural course of NASH in humans, the models often only induce mild liver injury. Many genetic and toxin + diet-induced models rapidly induce the development of metabolic disruption and serious liver injury, but not without their own shortcomings. This review provides an overview of the “multiple-hits” hypothesis and an evaluation of the currently existing animal models of NASH. This review also provides an update on the available interventions for managing NASH as well as pharmacological agents that are currently undergoing clinical trials for the treatment of NASH.

Role of micronutrients in staging of nonalcoholic fatty liver disease: A retrospective cross-sectional study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) presents high incidence throughout the world and has been progressively increasing in prevalence. This disease has a heterogeneous natural history, including simple steatosis, nonalcoholic steatohepatitis (NASH), and cirrhosis. The factors that determine its evolution to more severe forms of the disease are still poorly understood, and micronutrients with antioxidant potential may be involved in the pathophysiology of the disease.

AIM

To evaluate the relationship between serum levels of micronutrients and the severity of NAFLD.

METHODS

A retrospective, observational and cross-sectional study was conducted. This study included all patients undergoing bariatric surgery who experienced liver biopsy during the procedure, and had serum levels of micronutrients (vitamin D, vitamin B12, zinc, iron, and magnesium), which was assessed in a preoperative evaluation conducted at a reference center in southern Brazil.

RESULTS

A total of 614 patients were analyzed, of which 93% had steatosis, 70.7% had NASH, and 49.3% had some degree of fibrosis. Serum levels of vitamin D were negatively correlated with the severity of steatosis and NASH, and serum levels of vitamin B12 were positively correlated with the severity of steatosis and fibrosis. The other micronutrients showed no association with NAFLD staging.

CONCLUSION

Serum levels of vitamin D are inversely related to the severity of steatosis and NASH, and serum levels of vitamin B12 are higher in more advanced stages of simple steatosis and liver fibrosis. Serum levels of zinc, iron, and magnesium were not associated with NAFLD severity.

Plasma ApoE elevations are associated with NAFLD: The PREVEND Study

Non-alcoholic fatty liver disease (NAFLD) is featured by increased plasma very low density lipoproteins (VLDL). The extent to which plasma apolipoprotein E (ApoE) levels are elevated in NAFLD is unclear. We determined whether plasma ApoE is elevated in subjects with suspected NAFLD. Plasma ApoE and genotypes were determined in 6,762 participants of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) cohort. A Fatty Liver Index (FLI) ≥ 60 was used as a proxy of NAFLD. A total of 1,834 participants had a FLI ≥ 60, which coincided with increased triglycerides, non-HDL cholesterol, ApoB and ApoE (all P<0.001). In multivariable linear regression analysis, plasma ApoE levels were positively associated with an elevated FLI when taking account of ApoE genotypes and other clinical and laboratory covariates (fully adjusted model: β = 0.201, P<0.001). Stratified analysis for ApoE genotypes (ApoE ε3ε3 homozygotes, ApoE ε2 carriers, and ApoE ε3ε4 and ε4ε4 carriers combined), also showed positive associations of plasma ApoE levels with an elevated FLI in each group (all P<0.001). In conclusion, it is suggested that NAFLD is characterized by increased plasma ApoE levels, even when taking account of the various ApoE genotypes. Increased plasma ApoE may contribute to altered VLDL metabolism and to increased atherosclerosis susceptibility in NAFLD.

Genetic and Epigenetic Culprits in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic Fatty Liver Disease (NAFLD) constitutes a wide spectrum of liver pathology with hepatic steatosis at the core of this pathogenesis. Variations of certain genetic components have demonstrated increased susceptibility for hepatic steatosis. Therefore, these inciting variants must be further characterized in order to ultimately provide effective, targeted therapies for NAFLD and will be the focus of this review. Several genetic variants revealed an association with NAFLD through Genome-wide Association Study, meta-analyses, and retrospective case-control studies. PNPLA3 rs738409 and TM6SF2 rs58542926 are the two genetic variants providing the strongest evidence for association with NAFLD. However, it remains to be determined if these genetic variants serve as the primary culprit which induces the pathogenesis of NAFLD. Prospective and intervention studies are urgently needed to firmly establish a cause-and-effect relationship between the presence of certain genetic variants and risk of NAFLD development and progression.

Association of serum ferritin with non-alcoholic fatty liver disease: a meta-analysis

Background

A growing number of studies reported the connection between the level of serum ferritin (SFL) and non-alcoholic fatty liver disease (NAFLD). However, such connection was still disputable. The aim of our meta-analysis was to estimate SFL between the groups as below: patients with NAFLD against control group; non-alcoholic steatohepatitis (NASH) patients against control group; non-alcoholic fatty liver (NAFL) patients against a control group and NASH patients vs NAFL patients.

Methods

We screened the studies in PubMed, EMBASE, the Cochrane Database and the Cochrane Central register controlled trials from the beginning to July 10, 2016 to find the studies indicated the connection between SFL and NAFLD (NAFL and/or NASH). Fourteen published studies which evaluate the SFL in NAFLD patients were selected.

Results

Higher SFL was noticed in NAFLD patients against control group (standardized mean difference [SMD] 1.01; 95% CI 0.89, 1.13), NASH patients against control group (SMD 1.21; 95% CI 1.00, 1.42), NAFL patients against control group (SMD 0.51; 95% CI 0.24, 0.79) and NASH patients against NAFL patients (SMD 0.63; 95% CI 0.52, 0.75). These results remained unaltered actually after the elimination of studies which were focused on paediatric or adolescent populations. Higher SFL was presented in NAFLD patients against the control group (SMD 1.08; 95% CI 0.95, 1.20) in adults and NASH patients against NAFL patients in adults (SMD 0.74; 95% CI 0.62, 0.87). The connection between SFL and NASH against NAFL group in paediatric or adolescent populations was observed inconsistently (SMD 0.10; 95% CI -0.18, 0.38).

Conclusions

The level of SFL was elevated in patients with NAFLD (NAFL and/or NASH) compared with the controls. Compared with NAFL, The level of SFL was increased in NASH. The result remained unaltered actually after the elimination of studies focused on paediatric or adolescent populations.

High prevalence of apolipoprotein B dyslipoproteinemias in non-alcoholic fatty liver disease: The lifelines cohort study

OBJECTIVE

Cardiovascular disease (CVD) is a major adverse consequence of non-alcoholic fatty liver disease (NAFLD). The association of NAFLD with various apolipoprotein B (apoB) dyslipoproteinemias is unclear. We determined the prevalence of specific apoB dyslipoproteinemias in subjects with suspected NAFLD.

METHODS

This study was conducted among 22,865 fasting adults living in the northern part of the Netherlands (Lifelines Cohort Study). Six apoB dyslipoproteinemias were defined using an algorithm derived from apoB, total cholesterol and triglycerides. NAFLD was defined as Fatty Liver Index (FLI) ≥60. Advanced hepatic fibrosis was defined as NAFLD fibrosis score (NFS) ≥0.676.

RESULTS

4790 participants (20.9%) had an FLI≥60. NAFLD subjects were older, more likely to be men, more obese and more often had diabetes and metabolic syndrome (P<0.001 for each). Among NAFLD subjects, any apoB dyslipoproteinemia was present in 61.5% vs. 16.5% in subjects without NAFLD (P<0.001). Elevated chylomicrons were not observed in NAFLD. In univariate analysis, NAFLD was associated with a higher prevalence of each apoB dyslipoproteinemia vs. subjects with an FLI<60 (P<0.001), except for low density lipoprotein (LDL) dyslipoproteinemia. Additionally, each apoB dyslipoproteinemia was independently associated with NAFLD in age- and sex-adjusted logistic regression analysis, including the apoB dyslipoproteinemias together (P<0.001). The prevalence of apoB dyslipoproteinemias was not altered in subjects with NFS ≥0.676.

CONCLUSIONS

NAFLD rather than advanced hepatic fibrosis is independently associated with increased prevalence of chylomicrons+very low-density lipoproteins (VLDL) remnants, VLDL, LDL and VLDL+LDL dyslipoproteinemias. ApoB dyslipoproteinemias may contribute to increased CVD risk associated with NAFLD.

Genetic factors that affect nonalcoholic fatty liver disease: A systematic clinical review

AIM: To investigate roles of genetic polymorphisms in non-alcoholic fatty liver disease (NAFLD) onset, severity, and outcome through systematic literature review.

METHODS: The authors conducted both systematic and specific searches of PubMed through December 2015 with special emphasis on more recent data (from 2012 onward) while still drawing from more historical data for background. We identified several specific genetic polymorphisms that have been most researched and, at this time, appear to have the greatest clinical significance on NAFLD and similar hepatic diseases. These were further investigated to assess their specific effects on disease onset and progression and the mechanisms by which these effects occur.

RESULTS: We focus particularly on genetic polymorphisms of the following genes: PNPLA3, particularly the p. I148M variant, TM6SF2, particularly the p. E167K variant, and on variants in FTO, LIPA, IFNλ4, and iron metabolism, specifically focusing on HFE, and HMOX-1. We discuss the effect of these genetic variations and their resultant protein variants on the onset of fatty liver disease and its severity, including the effect on likelihood of progression to cirrhosis and hepatocellular carcinoma. While our principal focus is on NAFLD, we also discuss briefly effects of some of the variants on development and severity of other hepatic diseases, including hepatitis C and alcoholic liver disease. These results are briefly discussed in terms of clinical application and future potential for personalized medicine.

CONCLUSION: Polymorphisms and genetic factors of several genes contribute to NAFLD and its end results. These genes hold keys to future improvements in diagnosis and management.

Non-alcoholic fatty liver disease and dyslipidemia: An update

Non-alcoholic fatty liver (NAFLD) is the most common liver disease worldwide, progressing from simple steatosis to necroinflammation and fibrosis (leading to non-alcoholic steatohepatitis, NASH), and in some cases to cirrhosis and hepatocellular carcinoma. Inflammation, oxidative stress and insulin resistance are involved in NAFLD development and progression. NAFLD has been associated with several cardiovascular (CV) risk factors including obesity, dyslipidemia, hyperglycemia, hypertension and smoking. NAFLD is also characterized by atherogenic dyslipidemia, postprandial lipemia and high-density lipoprotein (HDL) dysfunction. Most importantly, NAFLD patients have an increased risk for both liver and CV disease (CVD) morbidity and mortality. In this narrative review, the associations between NAFLD, dyslipidemia and vascular disease in NAFLD patients are discussed. NAFLD treatment is also reviewed with a focus on lipid-lowering drugs. Finally, future perspectives in terms of both NAFLD diagnostic biomarkers and therapeutic targets are considered.

Influence of the APOE genotype on hepatic stress response: Studies in APOE targeted replacement mice and human liver cells

Apolipoprotein E (APOE) is a multifunctional plasma protein mainly acting in lipid metabolism. Human APOE is polymorphic with three major isoforms (APOE2, APOE3 and APOE4). Up to 75% of the body's APOE is produced by the liver. There is increasing evidence from studies in brain-derived cells that APOE4 affects mitochondrial function and biogenesis as well as stress and inflammatory responses - processes, whose disturbances are considered hallmarks of the ageing process. However, although the liver is the main production site of APOE, knowledge about the impact of the APOE genotype on hepatic stress response-related processes is rather limited. Therefore, we studied biomarkers of oxidative status (glutathione levels, 3-nitrotyrosine adducts, protein carbonyl concentration), ER stress (XBP1(S), BiP, DDIT3), proteasome activity, mitochondrial function (respiratory complexes, ATP levels and mitochondrial membrane potential as well as biomarkers of mitochondrial biogenesis, fission and fusion), autophagy (LC3, LAMP2A), apoptosis (BCL2, BAX, CYCS) and DNA damage in the liver of APOE targeted replacement (TR) mice and in Huh7 hepatocytes overexpressing the APOE3 and the APOE4 isoform, respectively. APOE4 mice exhibited a lower chymotrypsin-like and a higher trypsin-like proteasome activity. Levels of protein carbonyls were moderately higher in liver tissue of APOE4 vs. APOE3 mice. Other biomarkers of oxidative stress were similar between the two genotypes. Under basal conditions, the stress-response pathways investigated appeared largely unaffected by the APOE genotype. However, upon stress induction, APOE4 expressing cells showed lower levels of adenosine triphosphate (ATP) and lower mRNA levels of the ATP-generating complex V of the mitochondrial respiratory chain. Overall, our findings provide evidence for a rather low influence of the APOE genotype on the hepatic stress response processes investigated in this study.

The Relationship between Type 2 Diabetes Mellitus and Non-Alcoholic Fatty Liver Disease Measured by Controlled Attenuation Parameter

PURPOSE

The severity of non-alcoholic fatty liver disease (NAFLD) in type 2 diabetes mellitus (T2DM) population compared with that in normal glucose tolerance (NGT) individuals has not yet been quantitatively assessed. We investigated the prevalence and the severity of NAFLD in a T2DM population using controlled attenuation parameter (CAP).

MATERIALS AND METHODS

Subjects who underwent testing for biomarkers related to T2DM and CAP using Fibroscan® during a regular health check-up were enrolled. CAP values of 250 dB/m and 300 dB/m were selected as the cutoffs for the presence of NAFLD and for moderate to severe NAFLD, respectively. Biomarkers related to T2DM included fasting glucose/insulin, fasting C-peptide, hemoglobin A1c (HbA1c), glycoalbumin, and homeostasis model assessment of insulin resistance of insulin resistance (HOMA-IR).

RESULTS

Among 340 study participants (T2DM, n=66; pre-diabetes, n=202; NGT, n=72), the proportion of subjects with NAFLD increased according to the glucose tolerance status (31.9% in NGT; 47.0% in pre-diabetes; 57.6% in T2DM). The median CAP value was significantly higher in subjects with T2DM (265 dB/m) than in those with pre-diabetes (245 dB/m) or NGT (231 dB/m) (all p<0.05). Logistic regression analysis showed that subjects with moderate to severe NAFLD had a 2.8-fold (odds ratio) higher risk of having T2DM than those without NAFLD (p=0.02; 95% confidence interval, 1.21-6.64), and positive correlations between the CAP value and HOMA-IR (ρ0.407) or fasting C-peptide (ρ0.402) were demonstrated.

CONCLUSION

Subjects with T2DM had a higher prevalence of severe NAFLD than those with NGT. Increased hepatic steatosis was significantly associated with the presence of T2DM, and insulin resistance induced by hepatic fat may be an important mechanistic connection.

Genetic Factors That Affect Risk of Alcoholic and Nonalcoholic Fatty Liver Disease

Genome-wide association studies and candidate gene studies have informed our understanding of factors contributing to the well-recognized interindividual variation in the progression and outcomes of alcoholic liver disease and nonalcoholic fatty liver disease. We discuss the mounting evidence for shared modifiers and common pathophysiological processes that contribute to development of both diseases. We discuss the functions of proteins encoded by risk variants of genes including patatin-like phospholipase domain-containing 3 and transmembrane 6 superfamily member 2, as well as epigenetic factors that contribute to the pathogenesis of alcoholic liver disease and nonalcoholic fatty liver disease. We also discuss important areas of future genetic research and their potential to affect clinical management of patients.

Insulin resistance in development and progression of nonalcoholic fatty liver disease

Although insulin resistance (IR) is strongly associated with nonalcoholic fatty liver disease (NAFLD), the association of IR and NAFLD is not universal and correlation between IR and severity of NAFLD is still controversial. In this review, we summarize recent evidence that partially dissociates insulin resistance from NAFLD. It has also been reported that single-nucleotide polymorphisms in the diacylglycerol acyltransferase gene, rather than IR, account for the variability in liver fat content. Polymorphisms of the patatin-like phospholipase 3 gene have also been reported to be associated with NAFLD without metabolic syndrome, which suggests that genetic conditions that promote the development of fatty changes in the liver may occur independently of IR. Moreover, environmental factors such as nutrition and physical activity as well as small intestinal bacterial overgrowth have been linked to the pathogenesis of NAFLD, although some of the data are conflicting. Therefore, findings from both genetically engineered animal models and humans with genetic conditions, as well as recent studies that have explored the role of environmental factors, have confirmed the view that NAFLD is a polygenic disease process caused by both genetic and environmental factors. Therefore, IR is not the sole predictor of the pathogenesis of NAFLD.

Genetic and epigenetic mechanisms of NASH

Along with the obesity epidemic, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased exponentially. The histological disease spectrum of NAFLD ranges from bland fatty liver (hepatic steatosis), to the concomitant presence of inflammation and ballooning which defines nonalcoholic steatohepatitis (NASH). The latter can progress in a subset to fibrosis, leading ultimately to cirrhosis and hepatocellular carcinoma. The past decade has seen tremendous advances in our understanding of the genetic and epigenetic bases of NAFLD, mainly through the application of high end technology platforms including genome-wide association studies (GWAS). These have helped to define common gene variants (minor allele frequency >5 %) that contribute to the NAFLD phenotype. Looking to the future, these discoveries are expected to lead to improved diagnostics, the personalization of medicine, and a better understanding of the pathophysiological underpinnings that drive the transition from NAFLD to steatohepatitis and fibrosis, leading to the identification of novel therapeutic targets. In this review, we summarize data on the current state of knowledge with regard to the genetic and epigenetic mechanisms for the development of NASH.

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.

Association of homocysteine level with biopsy-proven non-alcoholic fatty liver disease: a meta-analysis

Previous studies have reported inconsistent findings regarding the association between plasmatic higher of homocysteine level and non-alcoholic fatty liver disease. We aimed to investigate this association by conducting a meta-analysis. Literature was searched on PubMed from inception to January 2015. Eight studies evaluating plasma level of homocysteine in biopsy-proven non-alcoholic fatty liver disease subjects compared to healthy controls were included. Compared with the controls, non-alcoholic fatty liver disease patients witnessed a higher level of homocysteine [standard mean difference (SMD): 0.66 µmol/L, 95% CI: 0.41, 0.92 µmol/L], and were associated with a significant increased risk for hyperhomocysteinemia [odds ratio (OR) 5.09, 95% CI: 1.69, 15.32]. In addition, patients with non-alcoholic fatty liver presented 0.45 µmol/L higher levels of homocysteine compared to healthy controls (95% CI: 0.09, 0.82 µmol/L), whereas non-alcoholic steatohepatitis patients had 1.02 µmol/L higher levels of homocysteine (95% CI: 0.28, 1.76 µmol/L). There was neither difference of folate level nor vitamin B12 level between non-alcoholic fatty liver disease subjects and healthy controls. This study revealed that non-alcoholic fatty liver disease patients presented an increased serum concentration of homocysteine, and were associated with an increased risk of hyperhomocysteinemia. Further studies are needed to demonstrate a causal role of hyperhomocysteinemia in non-alcoholic fatty liver disease.

Systematic review of genetic association studies involving histologically confirmed non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease has an increasing prevalence in Western countries, affecting up to 20% of the population.

In vitro identification of nonalcoholic fatty liver disease-related protein hnRNPM

AIM: To study the formation of intracellular glyceraldehyde-derived advanced glycation end products (Glycer-AGEs) in the presence of high concentrations of fructose.

METHODS: Cells of the human hepatocyte cell line Hep3B were incubated with or without fructose for five days, and the corresponding cell lysates were separated by two-dimensional gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Glycer-AGEs were detected with the anti-Glycer-AGEs antibody. Furthermore, the identification of the proteins that are modified by glyceraldehyde in the presence of high concentrations of fructose was conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The protein and mRNA levels were determined by Western blotting and real-time reverse transcription PCR, respectively.

RESULTS: The results of the two-dimensional gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a greater amount of Glycer-AGEs in the sample exposed to high concentrations of fructose than in the control. The detected Glycer-AGEs showed isoelectric points in the range of 8.0-9.0 and molecular weights in the range of 60-80 kDa. The heterogeneous nuclear ribonucleoprotein M (hnRNPM), which plays an important role in regulating gene expression by processing heterogeneous nuclear RNAs to form mature mRNAs, was identified as a modified protein using MALDI-TOF-MS. Increasing the concentration of fructose in the medium induced a concentration-dependent increase in the generated Glycer-AGEs. Furthermore, in an experiment using glyceraldehyde, which is a precursor of Glycer-AGEs, hnRNPM was found to be more easily glycated than the other proteins.

CONCLUSION: The results suggest that glyceraldehyde-modified hnRNPM alters gene expression. This change may cause adverse effects in hepatocytes and may serve as a target for therapeutic intervention.

Western diet in ApoE-LDLR double-deficient mouse model of atherosclerosis leads to hepatic steatosis, fibrosis, and tumorigenesis

Nonalcoholic fatty liver disease has been linked to cardiovascular diseases and atherosclerosis. The aim of the current study was to characterize the hepatic pathology leading to fibrosis and tumors in a murine model of atherosclerosis. Male apolipoprotein E/low-density lipoprotein receptor double-knockout mice (AL) mice were fed with a high fat and high cholesterol western diet for 35 weeks (AL mice on WD). Protein and mRNA analysis as well as micro-computed tomography (micro-CT) were performed to assess oxidative stress, liver damage, inflammation, fibrosis, signaling pathways, vascularization, and tumorigenesis. Controls were chosen to distinguish between genetically and dietary effects in steatohepatitis and associated tumorigenesis. Hepatic inflammation and dyslipidemia were increased in AL mice on WD compared with wild-type mice on WD. Uniquely, AL mice on WD showed a spontaneous development of tumors (30% of cases) and thickening of intrahepatic vessel walls. Functionally relevant underlying signaling pathways such as NF-κB, Stat3, JNK, and AKT were differentially regulated between AL and wild-type mice on WD. Micro-CT was capable of visualizing and quantitatively distinguishing tumor neovascularization from vascularization in non-neoplastic liver tissue. AL mice on WD diet represent a novel model combining atherosclerosis and nonalcoholic fatty liver disease. Signaling pathways of liver cell damage and compensatory liver regeneration in combination with enhanced inflammation appear to be crucial for the spontaneous development of tumors in AL mice on WD. Micro-CT represents a new and powerful technique for the ultrastructural and three-dimensional assessment of the vascular architecture of liver tumors.

Serum proteome of nonalcoholic fatty liver disease: a multimodal approach to discovery of biomarkers of nonalcoholic steatohepatitis

BACKGROUND AND AIM

Nonalcoholic fatty liver disease (NAFLD) is a common condition affecting up to 25% of the developed world. It is a progressive disease, leading in some to the development of liver cirrhosis. Currently, accurate diagnosis and staging of this condition is only possible with histological examination of a liver biopsy. This gold standard test is neither suitable nor practical for large-scale use as is necessary for a condition as common as NAFLD. The aim of this study is to describe the proteome of human NAFLD using two distinct shotgun proteomic methods, translating the findings into potential biomarkers of NAFLD.

METHODS

Two distinct shotgun proteomic techniques (iTRAQ and label free) were used to describe the proteome of NAFLD. Thereafter, candidate biomarkers were selected for validation by ELISA.

RESULTS

Over 550 protein identifications were made in the description of the NAFLD proteome. Several proteins were found to be significantly up/downregulated in nonalcoholic steatohepatitis compared with control, including apolipoprotein E (fold ratio of 1.67), insulin-like growth factor-binding protein 3 (IGFBP3, fold ratio of 1.642), Vitamin D-binding protein (fold ratio of 4.587), and lymphocyte cytosolic protein1 (LCP1, fold ratio of 4.356). ELISA validation of a subset of these proteins confirms the validity of the proteomic studies and suggests possible new biomarkers of NAFLD.

CONCLUSION

Serum markers are able to distinguish between the stages of disease in NAFLD as well as detect the grade of fibrosis. Ultimately, noninvasive serum markers may replace liver biopsy in the investigation of patients with suspected NAFLD.

Serum homocysteine levels, oxidative stress and cardiovascular risk in non-alcoholic steatohepatitis

INTRODUCTION

Hyperhomocysteinemia is considered an independent risk factor for cardiovascular disease. Oxidative stress is one of the major pathogenic mechanisms in non-alcoholic fatty liver disease and atherosclerosis.

AIM

Our study aimed to evaluate serum homocysteine levels and oxidative stress in patients with biopsy-proven non-alcoholic steatohepatitis and possible association with cardiovascular risk measured by carotid artery intima-media thickness (c-IMT).

PATIENTS AND METHODS

50 patients with non-alcoholic steatohepatitis and 30 healthy controls, age and gender matched, were recruited. Lipid profile, liver biochemical markers, serum homocysteine, vitamins B6 and B12, folic acid, glutathione (reduced and total), erythrocyte superoxide dismutase, whole blood glutathione peroxidase, malondialdehyde and carotid intima-media thickness were assayed.

RESULTS

Patients had an altered lipid profile and liver biochemical markers; carotid intima-media thickness and serum homocysteine levels were significantly higher compared to controls, but there were no differences in folate, B12 and B6 vitamins levels. Patients had significantly lower levels of glutathione peroxidase activity, total and reduced glutathione and higher levels of malondialdehyde, but unchanged superoxide dismutase activity compared to control group. Also, serum homocysteine level showed significant positive correlation with waist circumference, body mass index, free cholesterol, triglycerides, LDL-cholesterol, amino transferases and negative correlation with reduced and total glutathione, superoxide dismutase and γ-GT.

CONCLUSION

Non-alcoholic steatohepatitis is an independent cardiovascular risk factor, associated with elevated homocysteine levels, oxidative stress and c-IMT. c-IMT could be used as an indicator of early atherosclerotic changes initiated by dyslipidemia and oxidative stress, while higher level of homocysteine might be an effect of liver damage.

The association of vitamin D deficiency with non-alcoholic fatty liver disease

OBJECTIVE

Vitamin D deficiency has been related to diabetes, hypertension, hyperlipidemia and peripheral vascular disease. In this study, we aimed to investigate the role of vitamin D status in non-alcoholic fatty liver disease.

METHODS

We included 211 consecutive subjects to examine the presence of non-alcoholic fatty liver disease. Of these subjects, 57 did not have non-alcoholic fatty liver disease and 154 had non-alcoholic fatty liver disease.

RESULTS

The non-alcoholic fatty liver disease group had significantly higher fasting blood glucose (p = 0.005), uric acid (p = 0.001), aspartate aminotransferase (p<0.001), alanine aminotransferase (p<0.001), γ-glutamyltransferase (p<0.0001), alkaline phosphatase (p = 0.028), HbA1c (p<0.001), ferritin (p<0.001), insulin (p = 0.016), C-peptide (p = 0.001), HOMA-IR (p = 0.003), total cholesterol (p = 0.001), triglyceride (p = 0.001) and white blood cell (p = 0.04) levels. In contrast, the non-alcoholic fatty liver disease group had significantly lower 25(OH)D levels (12.3±8.9 ng/dl, p<0.001) compared with those of the control group (20±13.6 ng/dl).

CONCLUSIONS

In this study, we found lower serum 25(OH)D levels in patients with non-alcoholic fatty liver disease than in subjects without non-alcoholic fatty liver disease. To establish causality between vitamin D and non-alcoholic fatty liver disease, further interventional studies with a long-term follow-up are needed.

Genetic variants in the PNPLA3 gene are associated with nonalcoholic steatohepatitis

In this study, we report the association of the rs738407, rs738409, and rs2896019 variants of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) (adiponutrin) gene with nonalcoholic steatohepatitis (NASH) (χ(2)=14.528, p=0.001; χ(2)=18.882, p=0.000; χ(2)=7.449, p=0.024, respectively) in 80 patients with NASH and 303 healthy controls. We genotyped the subjects using three polymerase chain reaction-restriction fragment length polymorphism methods developed in our laboratory. Our findings confirm the findings of the recent case-control and genome-wide association studies carried out in different populations around the world. Thus, the three variants in PNPLA3 gene may be a genetic risk factor for NASH.

Genetic predisposition in NAFLD and NASH: impact on severity of liver disease and response to treatment

Liver fat deposition related to systemic insulin resistance defines non-alcoholic fatty liver disease (NAFLD) which, when associated with oxidative hepatocellular damage, inflammation, and activation of fibrogenesis, i.e. non-alcoholic steatohepatitis (NASH), can progress towards cirrhosis and hepatocellular carcinoma. Due to the epidemic of obesity, NAFLD is now the most frequent liver disease and the leading cause of altered liver enzymes in Western countries. Epidemiological, familial, and twin studies provide evidence for an element of heritability of NAFLD. Genetic modifiers of disease severity and progression have been identified through genome-wide association studies. These include the Patatin-like phosholipase domain-containing 3 (PNPLA3) gene variant I148M as a major determinant of inter-individual and ethnicity-related differences in hepatic fat content independent of insulin resistance and serum lipid concentration. Association studies confirm that the I148M polymorphism is also a strong modifier of NASH and progressive hepatic injury. Furthermore, a few large multicentre case-control studies have demonstrated a role for genetic variants implicated in insulin signalling, oxidative stress, and fibrogenesis in the progression of NAFLD towards fibrosing NASH, and confirm that hepatocellular fat accumulation and insulin resistance are key operative mechanisms closely involved in the progression of liver damage. It is now important to explore the molecular mechanisms underlying these associations between gene variants and progressive liver disease, and to evaluate their impact on the response to available therapies. It is hoped that this knowledge will offer further insights into pathogenesis, suggest novel therapeutic targets, and could help guide physicians towards individualised therapy that improves clinical outcome.

Association of nicotinamide-N-methyltransferase gene rs694539 variant with patients with nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal hepatic steatosis in the absence of a history of alcohol use and with a prevalence of 15%-45% in developed nations. Nonalcoholic steatohepatitis (NASH) is an advanced stage of NAFLD with a pronounced major inflammatory component. The aim of this study was to investigate the possible role of nicotinamide-N-methyltransferase (NNMT) gene rs694539 variant in the development of NASH. Therefore, we analyzed 80 NASH patients and 183 healthy controls using a polymerase chain reaction-restriction fragment length polymorphism method developed in our laboratory. The NNMT rs694539 variant was found to be significantly associated with NASH (χ(2)=9.349, p=0.009). The individuals with the GG genotype had protection against NASH (χ(2)=3.793, p=0.051, odds ratio [OR]=0.580, 95% confidence interval [CI]=0.334-1.006), whereas the individuals with the AA genotype showed statistically significant increased risk for NASH (χ(2)=7.748, p=0.005, OR=7.338, 95% CI=1.448-37.190). Moreover, the G allele was protective against NASH (χ(2)=7.748, p=0.005, OR=0.136, and 95% CI=0.027-0.691). On the other hand, the A allele was a risk factor for NASH (χ(2)=3.793, p=0.051, OR=1.725, and 95% CI=0.994-2.996). Consequently, the rs694539 variant of NNMT gene is a genetic risk factor for developing NASH.

Progression of NAFLD to diabetes mellitus, cardiovascular disease or cirrhosis

NAFLD is a spectrum of progressive liver disease that encompasses simple steatosis, NASH, fibrosis and, ultimately, cirrhosis. NAFLD is recognized as the hepatic component of the metabolic syndrome, as these conditions have insulin resistance as a common pathophysiological mechanism. Therefore, NAFLD is strongly associated with type 2 diabetes mellitus and abdominal obesity. As lifestyles have become increasingly sedentary and dietary patterns have changed, the worldwide prevalence of NAFLD has increased dramatically and is projected to be the principal aetiology for liver transplantation within the next decade. Importantly, a growing body of clinical and epidemiological evidence suggests that NAFLD is associated not only with liver-related morbidity and mortality, but also with an increased risk of developing both cardiovascular disease and type 2 diabetes mellitus. This article reviews the evidence that suggests NAFLD is a multisystem disease and the factors that might determine interindividual variation in the development and progression of its major hepatic and extrahepatic manifestations (principally type 2 diabetes mellitus and cardiovascular disease).

Genomic aspects of NAFLD pathogenesis

Non-alcoholic fatty liver disease (NAFLD) is the most predominant liver disease worldwide and hepatic manifestation of the metabolic syndrome. Its histology spectrum ranges from steatosis, to steatohepatitis (NASH) that can further progress to cirrhosis and hepatocellular carcinoma (HCC). The increasing incidence of NAFLD has contributed to rising numbers of HCC occurrences. NAFLD progression is governed by genetic susceptibility, environmental factors, lifestyle and features of the metabolic syndrome, many of which overlap with HCC. Gene expression profiling and genome wide association studies have identified novel disease pathways and polymorphisms in genes that may be potential biomarkers of NAFLD progression. However, the multifactorial nature of NAFLD and the limited number of sufficiently powered studies are among the current limitations for validated biomarkers of clinical utility. Further studies incorporating the links between circadian regulation and hepatic metabolism might represent an additional direction in the search for predictive biomarkers of liver disease progression and treatment outcomes.

Murine Models of Nonalcoholic Fatty Liver Disease and Steatohepatitis

In 1980, Ludwig et al. first reported patients of steatohepatitis who lacked a history of excessive alcohol consumption but showed liver histology resembling alcoholic hepatitis and progression to cirrhosis of the liver accompanied by inflammation and fibrosis. The development of nonalcoholic steatohepatitis (NASH) is associated with obesity, diabetes mellitus, insulin resistance, and hyperlipidemia. However, the pathogenesis of NASH remains incomplete. A “multiple-hit” hypothesis for the pathogenesis of NASH based on an animal model has been proposed and remains a foundation for research in this field. We review the important dietary and genetic animal models and discuss the pathogenesis of NASH.

Lipoprotein metabolism in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), an escalating health problem worldwide, covers a spectrum of pathologies characterized by fatty accumulation in hepatocytes in early stages, with potential progression to liver inflammation, fibrosis, and failure. A close, yet poorly understood link exists between NAFLD and dyslipidemia, a constellation of abnormalities in plasma lipoproteins including triglyceride-rich very low density lipoproteins. Apolipoproteins are a group of primarily liver-derived proteins found in serum lipoproteins; they not only play an extracellular role in lipid transport between vital organs through circulation, but also play an important intracellular role in hepatic lipoprotein assembly and secretion. The liver functions as the central hub for lipoprotein metabolism, as it dictates lipoprotein production and to a significant extent modulates lipoprotein clearance. Lipoprotein metabolism is an integral component of hepatocellular lipid homeostasis and is implicated in the pathogenesis, potential diagnosis, and treatment of NAFLD.

Serum vitamin B12 and folate levels in patients with non-alcoholic fatty liver disease

The aim of the study was the evaluation of serum vitamin B12 and folate levels in patients with biopsy-proven non-alcoholic fatty liver disease (NAFLD) and their association with the disease severity. Thirty patients with biopsy-proven NAFLD and 24 healthy controls matched for gender, age, body mass index and waist circumference were recruited. Blood samples for vitamin B12, folate, insulin and standard biochemical tests were obtained after overnight fasting. Homeostatic model of assessment-insulin resistance was calculated. There was no difference in serum vitamin B12 and folate levels between groups. Neither vitamin B12 nor folate levels were significantly different within any histological category, including steatosis grade, fibrosis stage, lobular inflammation, portal inflammation and ballooning. In conclusion, similar vitamin B12 and folate levels were observed in non-alcoholic steatohepatitis and non-alcoholic fatty liver patients, and controls. Furthermore, vitamin B12 and folate levels were not associated with either insulin resistance or the severity of liver disease.

Genetic factors associated with the presence and progression of nonalcoholic fatty liver disease: a narrative review

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. Whereas insulin resistance and obesity are considered major risk factors for the development and progression of NAFLD, the genetic underpinnings are unclear. Before 2008, candidate gene studies based on prior knowledge of pathophysiology of fatty liver yielded conflicting results. In 2008, Romeo et al. published the first genome wide association study and reported the strongest genetic signal for the presence of fatty liver (PNPLA3, patatin-like phospholipase domain containing 3; rs738409). Since then, two additional genome wide scans were published and identified 9 additional genetic variants. Whereas these results shed light into the understanding of the genetics of NAFLD, most of associations have not been replicated in independent samples and, therefore, remain undetermined the significance of these findings. This review aims to summarize the understanding of genetic epidemiology of NAFLD and highlights the gaps in knowledge.