Lipid metabolism and liver inflammation. II. Fatty liver disease and fatty acid oxidation

Fatty liver disease (FLD), whether it is alcoholic FLD (AFLD) or nonalcoholic FLD (NAFLD), encompasses a morphological spectrum consisting of hepatic steatosis (fatty liver) and steatohepatitis. FLD has the inherent propensity to progress toward the development of cirrhosis and hepatocellular carcinoma. It is generally difficult to distinguish AFLD from NAFLD on morphological grounds alone despite the distinctions implied by these etiological designations. The indistinguishable spectrum of histological features of both AFLD and NAFLD suggests a possible convergence of pathogenetic mechanisms at some critical juncture that enables the progression of steatohepatitis toward cirrhosis and liver cancer. From a pathogenetic perspective, FLD may be considered a single disease with multiple etiologies. Excess energy consumption and reduced energy combustion appear to be critical events that culminate in lipid storage in the liver. Energy combustion in the liver is controlled by peroxisome proliferator-activated receptor (PPAR)-alpha-regulated mitochondrial and peroxisomal fatty acid beta-oxidation systems and the microsomal omega-oxidation system. PPAR-alpha, a receptor for peroxisome proliferators, functions as a sensor for fatty acids (lipid sensor), and ineffective PPAR-alpha sensing can lead to reduced energy burning resulting in hepatic steatosis and steatohepatitis. Delineation of the pathogenetic aspects of FLD is necessary for developing novel therapeutic strategies for this disease.     

Systems Biology Elucidates Common Pathogenic Mechanisms between Nonalcoholic and Alcoholic-Fatty Liver Disease

The abnormal accumulation of fat in the liver is often related either to metabolic risk factors associated with metabolic syndrome in the absence of alcohol consumption (nonalcoholic fatty liver disease, NAFLD) or to chronic alcohol consumption (alcoholic fatty liver disease, AFLD). Clinical and histological studies suggest that NAFLD and AFLD share pathogenic mechanisms. Nevertheless, current data are still inconclusive as to whether the underlying biological process and disease pathways of NAFLD and AFLD are alike. Our primary aim was to integrate omics and physiological data to answer the question of whether NAFLD and AFLD share molecular processes that lead to disease development. We also explored the extent to which insulin resistance (IR) is a distinctive feature of NAFLD. To answer these questions, we used systems biology approaches, such as gene enrichment analysis, protein–protein interaction networks, and gene prioritization, based on multi-level data extracted by computational data mining. We observed that the leading disease pathways associated with NAFLD did not significantly differ from those of AFLD. However, systems biology revealed the importance of each molecular process behind each of the two diseases, and dissected distinctive molecular NAFLD and AFLD-signatures. Comparative co-analysis of NAFLD and AFLD clarified the participation of NAFLD, but not AFLD, in cardiovascular disease, and showed that insulin signaling is impaired in fatty liver regardless of the noxa, but the putative regulatory mechanisms associated with NAFLD seem to encompass a complex network of genes and proteins, plausible of epigenetic modifications. Gene prioritization showed a cancer-related functional map that suggests that the fatty transformation of the liver tissue is regardless of the cause, an emerging mechanism of ubiquitous oncogenic activation. In conclusion, similar underlying disease mechanisms lead to NAFLD and AFLD, but specific ones depict a particular disease signature that has a different impact on the systemic context.     

SCD1 deficiency protects mice against ethanol-induced liver injury

Stearoyl-CoA desaturase 1 (SCD1) is a delta-9 fatty acid desaturase that catalyzes the synthesis of mono-unsaturated fatty acids (MUFA). SCD1 is a critical control point regulating hepatic lipid synthesis and β-oxidation. Scd1 KO mice are resistant to the development of diet-induced non-alcoholic fatty liver disease (NAFLD). Using a chronic-binge protocol of ethanol-mediated liver injury, we aimed to determine if these KO mice are also resistant to the development of alcoholic fatty liver disease (AFLD).Mice fed a low-fat diet (especially low in MUFA) containing 5% ethanol for 10 days, followed by a single ethanol (5 g/kg) gavage, developed severe liver injury manifesting as hepatic steatosis. This was associated with an increase in de novo lipogenesis and inflammation. Using this model, we show that Scd1 KO mice are resistant to the development of AFLD. Scd1 KO mice do not show accumulation of hepatic triglycerides, activation of de novo lipogenesis nor elevation of cytokines or other pro-inflammatory markers. Incubating HepG2 cells with a SCD1 inhibitor induced a similar resistance to the effect of ethanol, confirming a role for SCD1 activity in mediating ethanol-induced hepatic injury.Taken together, our study shows that SCD1 is a key player in the development of AFLD and associated deleterious effects, and suggests SCD1 inhibition as a therapeutic option for the treatment of this hepatic disease.     

sTRAIL levels and TRAIL gene polymorphisms in Chinese patients with fatty liver disease

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily, and has been identified as a novel mediator of fatty liver disease (FLD). The aim of our study was to further investigate the relationship between TRAIL and FLD. We found that soluble TRAIL (sTRAIL) concentrations in non-alcoholic FLD (NAFLD) patients were significantly higher than those of controls, and that sTRAIL levels positively correlated with triglyceride concentrations in NAFLD patients. Our results also indicated that the AA/TT genotypes of TRAIL at 1525/1595 engendered a lower risk of FLD attack and a less severe form of steatosis for NAFLD patients in Chinese population. This study provides a means to test for susceptibility to FLD and may assist in the diagnosis of FLD. In addition, we found that 1525G/A and 1595C/T sites were in complete linkage disequilibrium in Chinese population. This might indicate a haplotype with high genetic frequency of TRAIL.     

Diet-Quality Scores and Prevalence of Nonalcoholic Fatty Liver Disease: A Population Study Using Proton-Magnetic Resonance Spectroscopy

Dietary pattern analysis is an alternative approach to examine the association between diet and nonalcoholic fatty liver disease (NAFLD). This study examined the association of two diet-quality scores, namely Diet Quality Index-International (DQI-I) and Mediterranean Diet Score (MDS) with NAFLD prevalence. Apparently healthy Chinese adults (332 male, 465 female) aged 18 years or above were recruited through a population screening between 2008 and 2010 in a cross-sectional population-based study in Hong Kong. DQI-I and MDS, as well as major food group and nutrient intakes were calculated based on dietary data from a food frequency questionnaire. NAFLD was defined as intrahepatic triglyceride content at ≥5% by proton-magnetic resonance spectroscopy. Multivariate logistic regression models were used to examine the association between each diet-quality score or dietary component and prevalent NAFLD with adjustment for potential lifestyle, metabolic and genetic factors. A total of 220 subjects (27.6%) were diagnosed with NAFLD. DQI-I but not MDS was associated with the prevalence of NAFLD. A 10-unit decrease in DQI-I was associated with 24% increase in the likelihood of having NAFLD in the age and sex adjusted model (95% CI: 1.06–1.45, p = 0.009), and the association remained significant when the model was further adjusted for other lifestyle factors, metabolic and genetic factors [OR: 1.26 (95% CI: 1.03–1.54), p = 0.027]. Multivariate regression analyses showed an inverse association of the intake of vegetables and legumes, fruits and dried fruits, as well as vitamin C with the NAFLD prevalence (p<0.05). In conclusion, a better diet quality as characterized by a higher DQI-I and a higher consumption of vegetables, legumes and fruits was associated with a reduced likelihood of having NAFLD in Hong Kong Chinese.     

Nonalcoholic Fatty Liver Disease and Risk of Diabetes: A Prospective Study in China

Objective: We aimed to investigate whether liver steatosis severity affects the risk of developing diabetes in a large cohort study.Methods: We prospectively examined the association in 41,650 Chinese adults with negative hepatitis-B surface antigen who were free of alcohol consumption, diabetes, and liver cirrhosis at baseline. Cox proportional models were used to estimate the risk of diabetes after a mean of 3.6 years of follow-up. Nonalcoholic fatty liver disease (NAFLD) was assessed with hepatic ultrasonography. Elevated alanine transaminase (ALT) was defined as ALT concentrations >19 and >30 U/L in females and males, respectively. Diabetes was defined as a fasting glucose ³7.0 mmol/L or treatment with hypoglycemic medication.Results: Liver steatosis severity was significantly associated with higher risks of developing diabetes (adjusted hazard ratio [HR] for severe vs. without NAFLD = 2.66, 95% confidence interval [CI]: 2.17–3.25, P-trend<.001) and impaired fasting glucose (fasting glucose between 5.6 and 6.9 mmol/L, adjusted HR = 1.36, 95% CI: 1.16–1.59, P-trend<.001), as well as a faster increase rate of fasting glucose concentrations (P-trend<.001), during 3.6 years of follow-up. Elevated ALT was also associated with incident diabetes (HR = 1.12, 95% CI: 1.02–1.22), adjusting for NAFLD and other covariates.Conclusion: We observed a dose-response relationship between liver steatosis severity and increased diabetes risk, and ALT may predict incident diabetes independently of NAFLD.Abbreviations: ALT = alanine transaminase; BP = blood pressure; CI = confidence interval; HCV = hepatitis C virus; HR = hazard ratio; IFG = impaired fasting glucose; NAFLD = nonalcoholic fatty liver disease; ULN = upper limit of normal     

Biosynthesis and bioavailability of long-chain polyunsaturated fatty acids in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has a high occurrence in most countries. Recent studies estimate its prevalence to be near 30% in United States, Italian and Japanese general adult populations. NAFLD commonly presents along with obesity and insulin resistance (IR), pathologies that share with NAFLD metabolic and inflammatory components. These conditions, particularly NAFLD, are associated with alterations in the bioavailability of long-chain polyunsaturated fatty acids (LCPUFAs). In the human population, the bioavailability of LCPUFAs depends both on endogenous biosynthesis and diet amount of preformed LCPUFAs. However, the lower liver LCPUFAs product/precursor ratio namely (20:5n?3 + 22:6n?3)/18:3n?3, 20:4n?6/18:2n?6 present in common Western diets, makes critical an adequate pathway activity to ensure minimum bioavailability of LCPUFAs in most Western populations. The key step of this biosynthesis involves Δ5 and Δ6-desaturases, whose activities are altered in NAFLD. During the disease, the presence of molecular activators of these two enzymes does not correlate with the scarce LCPUFAS biosynthesis observed. The key to this apparent contradiction, or at least part of it, could be explained on the basis of the possible sensitivity of the desaturases to oxidative stress; a metabolic condition strongly linked to inflammatory pathologies such as NAFLD, obesity and IR and that, according to latest research, not only would be consequence but also possibly a cause of these diseases. The present review is focused on the relationship between NAFLD and the bioavailability of LCPUFAs, with special reference to the role that oxidative stress could play in the modulation of the liver fatty acid desaturase activity.     

Combined Serum Biomarkers in Non-Invasive Diagnosis of Non-Alcoholic Steatohepatitis

Background

Non-alcoholic steatoheaptitis (NASH), the critical stage of non-alcoholic fatty liver disease (NAFLD), is of chronic progression and can develop cirrhosis even hepatocellular carcinoma (HCC). However, non-invasive biomarkers for NASH diagnosis remain poorly applied in clinical practice. Our study aims at testing the accuracy of the combination of cytokeratin-18 M30 fragment (CK-18-M30), fibroblast growth factor 21 (FGF-21), interleukin 1 receptor antagonist (IL-1Ra), pigment epithelium-derived factor (PEDF) and osteoprotegerin (OPG) in diagnosing NAFLD and NASH.

Methods

179 patients with biopsy-proven NAFLD were enrolled as training group, 91 age- and gender-matched healthy subjects were recruited at the same time as controls. 63 other NAFLD patients were separately collected as validation group. 45 alcoholic fatty liver disease (AFLD) patients, 50 hepatitis B virus (HBV) patients, 52 hepatitis C virus (HCV) patients were also included. Serum biomarker levels were measured by enzyme-linked immunosorbent assay.

Results

Serum levels of CK-18-M30, FGF-21, IL-1Ra and PEDF increased, while OPG decreased in a stepwise fashion in controls, non-NASH NAFLD patients and NASH patients (P < 0.01). The area under receiver-operating characteristics curve to diagnose NASH was 0.86 for CK-18-M30, 0.89 for FGF-21, 0.89 for IL-1Ra, 0.89 for PEDF and 0.89 for OPG. CK-18-M30 had 70% negative predictive value (NPV) and 79% positive predictive value (PPV) to diagnose NASH. A 5-step approach measuring CK-18-M30 followed by FGF21, IL-1Ra, PEDF and OPG gradually improved the NPV to 76% and PPV to 85%, which reached 80% and 76% respectively in the validation cohort.

Conclusion

Compared to single biomarker, stepwise combination of CK-18-M30, FGF-21, IL-1Ra, PEDF and OPG can further improve the accuracy in diagnosing NASH.     

Fatty liver: Role of inflammation and fatty acid nutrition

Nonalcoholic fatty liver disease (NAFLD) refers to a wide spectrum of liver damage, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), advanced fibrosis, and cirrhosis. NAFLD is strongly associated with insulin resistance and is defined by accumulation of liver fat >5% per liver weight in the presence of <10 g of daily alcohol consumption. The exact prevalence of NAFLD is uncertain because of the absence of simple noninvasive diagnostic tests to facilitate an estimate of prevalence but in subgroups of people such as those with type 2 diabetes, the prevalence may be as high as 70%. NASH is an important subgroup within the spectrum of NAFLD that progresses over time with worsening fibrosis and cirrhosis, and NASH is associated with increased risk for cardiovascular disease. It is, therefore, important to understand the pathogenesis of NASH specifically, to develop strategies for interventions to treat this condition. The purpose of this review is to discuss the roles of inflammation, fatty acids and fatty acids in nutrition, in the pathogenesis and potential treatment of NAFLD.     

Food components with antifibrotic activity and implications in prevention of liver disease

Increasing prevalence of nonalcoholic fatty liver disease (NAFLD) in parallel with the obesity epidemic has been a major public health concern. NAFLD is the most common chronic liver disease in the United States, ranging from fatty liver to steatohepatitis, fibrosis and cirrhosis in the liver. In response to chronic liver injury, fibrogenesis in the liver occurs as a protective response; however, prolonged and dysregulated fibrogenesis can lead to liver fibrosis, which can further progress to cirrhosis and eventually hepatocellular carcinoma. Interplay of hepatocytes, macrophages and hepatic stellate cells (HSCs) in the hepatic inflammatory and oxidative milieu is critical for the development of NAFLD. In particular, HSCs play a major role in the production of extracellular matrix proteins. Studies have demonstrated that bioactive food components and natural products, including astaxanthin, curcumin, blueberry, silymarin, coffee, vitamin C, vitamin E, vitamin D, resveratrol, quercetin and epigallocatechin-3-gallate, have antifibrotic effects in the liver. This review summarizes current knowledge of the mechanistic insight into the antifibrotic actions of the aforementioned bioactive food components.     

Fatty Liver Through the Ages: Nonalcoholic Steatohepatitis

ObjectiveThe global epidemic of obesity and type 2 diabetes mellitus is the main driver of the growing global prevalence of nonalcoholic fatty liver disease (NAFLD). We aimed to review the current literature on NAFLD and nonalcoholic steatohepatitis (NASH) as it impacts children and adults.MethodsWe performed a literature search on fatty liver specifically NAFLD and NASH among children and adults.ResultsThe prevalence of NAFLD in children ranges from 8% to 12%, while the prevalence in adults ranges 25% to 48%. The prevalence of NASH among children with NAFLD is 23%, while it ranges from 13% to 65% in adults. There are similar risk factors for NAFLD among children and adults. However, in children, the diagnostic tests in the studies of NAFLD are limited to the elevation of the alanine aminotransferase level or a liver biopsy. In adults, additional diagnostic modalities, including noninvasive tests, have been used. From the spectrum of NAFLD, patients with NASH are predominantly at risk of progressive liver disease to cirrhosis and liver-related mortality. NAFLD is associated with impairment of health-related quality of life and substantial economic burden.ConclusionThe comprehensive burden (clinical, health-related quality of life, and economic) of NAFLD is high and increasing.     

Non-alcoholic fatty liver disease and risk of in-stent restenosis after bare metal stenting in native coronary arteries

In-stent restenosis (ISR) remains the most common complication of percutaneous coronary intervention. Due to shared risk factors, it is postulated that non-alcoholic fatty liver disease (NAFLD) patients have an increased risk of ISR. This study aimed to determine the association between NAFLD and ISR in patients after bare metal stenting. This study included a cohort of 210 consecutive patients (150 men and 60 women) undergoing follow-up angiography. The primary end-point was angiographic ISR. Multivariate logistic regression analysis was used to identify independent risk factors for ISR. The cumulative ISR rate during follow-up was analyzed by Kaplan–Meier method. Subgroup analyses were also done for different gender. The ISR rate was 29.5 %. Patients with NAFLD had a significantly higher prevalence of ISR than patients without NAFLD (43.3 vs. 16.0 %, P < 0.001). In logistic regression analysis, NAFLD was associated with increased ISR, independent of low-density lipoprotein cholesterol, body mass index (adjusted odds ratio: 2.688, 95 % confidence intervals: 1.285–5.537, P < 0.001). Male NAFLD patients had a higher prevalence of ISR than patients without NAFLD (48.4 vs. 15.3 %, P < 0.001), while the prevalence of ISR in female patients with and without NAFLD were comparable (7.7 vs. 17.0 %, P = 0.404). Kaplan–Meier analysis showed a significant association between NAFLD and ISR in all patients (log-rank P = 0.008) and in male subgroup (log-rank P = 0.033), but not in female subgroup (log-rank P = 0.313). This preliminary study suggests that NAFLD could independently associate with a high prevalence of ISR, especially in male patients.     

High Dietary Sodium Intake Assessed by Estimated 24-h Urinary Sodium Excretion Is Associated with NAFLD and Hepatic Fibrosis

Background

Although high sodium intake is associated with obesity and hypertension, few studies have investigated the relationship between sodium intake and non-alcoholic fatty liver disease (NAFLD). We evaluated the association between sodium intake assessed by estimated 24-h urinary sodium excretion and NAFLD in healthy Koreans.

Methods

We analyzed data from 27,433 participants in the Korea National Health and Nutrition Examination Surveys (2008–2010). The total amount of sodium excretion in 24-h urine was estimated using Tanaka’s equations from spot urine specimens. Subjects were defined as having NAFLD when they had high scores in previously validated NAFLD prediction models such as the hepatic steatosis index (HSI) and fatty liver index (FLI). BARD scores and FIB-4 were used to define advanced fibrosis in subjects with NAFLD.

Results

The participants were classified into three groups according to estimated 24-h urinary excretion tertiles. The prevalence of NAFLD as assessed by both FLI and HSI was significantly higher in the highest estimated 24-h urinary sodium excretion tertile group. Even after adjustment for confounding factors including body fat and hypertension, the association between higher estimated 24-h urinary sodium excretion and NAFLD remained significant (Odds ratios (OR) 1.39, 95% confidence interval (CI) 1.26–1.55, in HSI; OR 1.75, CI 1.39–2.20, in FLI, both P < 0.001). Further, subjects with hepatic fibrosis as assessed by BARD score and FIB-4 in NAFLD patients had higher estimated 24-h urinary sodium values.

Conclusions

High sodium intake was independently associated with an increased risk of NAFLD and advanced liver fibrosis.     

DNA Methylation Patterns According to Fatty Liver Index and Longitudinal Changes from the Korean Genome and Epidemiology Study (KoGES)

The role of differentially methylated regions (DMRs) in nonalcoholic fatty liver disease (NAFLD) is unclear. This study aimed to identify the role of DMR in NAFLD development and progression using the Korean Genome and Epidemiology Study (KoGES) cohort. We used laboratory evaluations and Illumina Methylation 450 k DNA methylation microarray data from KoGES. The correlation between fatty liver index (FLI) and genomic CpG sites was analyzed in 322 subjects. Longitudinal changes over 8 years were confirmed in 33 subjects. To identify CpG sites and genes related to FLI, we obtained enrichment terms for 6765 genes. DMRs were identified for both high (n = 128) and low (n = 194) groups on the basis of FLI 30 in 142 men and 180 women. To confirm longitudinal changes in 33 subjects, the ratio of follow-up and baseline investigation values was obtained. Correlations and group comparisons were performed for the 8 year change values. PITPNM3, RXFP3, and THRB were hypermethylated in the increased FLI groups, whereas SLC9A2 and FOXI3 were hypermethylated in the decreased FLI groups. DMRs describing NAFLD were determined, and functions related to inflammation were identified. Factors related to longitudinal changes are suggested, and blood circulation-related functions appear to be important in the management of NAFLD.     

Dietary fructose and intestinal barrier: potential risk factor in the pathogenesis of nonalcoholic fatty liver disease

Worldwide, not only the prevalence of obesity has increased dramatically throughout the last three decades but also the incidences of co-morbid conditions such as diabetes type 2 and liver disease have increased. The ‘hepatic manifestation of the metabolic syndrome’ is called nonalcoholic fatty liver disease (NAFLD) and comprises a wide spectrum of stages of liver disease ranging from simple steatosis to liver cirrhosis. NAFLD of different stages is found in ～30% of adults and ～20% in the US population. Not just a general overnutrition but also an elevated intake of certain macronutrients such as fat and carbohydrates and herein particularly fructose has been claimed to be risk factors for the development for NAFLD; however, the etiology of this disease is still unknown. The present review outlines some of the potential mechanisms associated with the development of NAFLD and fructose intake with a particular focus on the role of the intestinal barrier functions.     

Association between Dietary Vitamin C Intake and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Middle-Aged and Older Adults

Background

Non-alcoholic fatty liver disease (NAFLD) has become one of the most prevalent chronic liver disease all over the world. The objective of this study was to evaluate the association between dietary vitamin C intake and NAFLD.

Method

Subjects were diagnosed with NAFLD by abdominal ultrasound examination and the consumption of alcohol was less than 40g/day for men or less than 20g/day for women. Vitamin C intake was classified into four categories according to the quartile distribution in the study population: ≤74.80 mg/day, 74.81–110.15 mg/day, 110.16–146.06 mg/day, and ≥146.07 mg/day. The energy and multi-variable adjusted odds ratio (OR), as well as their corresponding 95% confidence interval (CI), were used to determine the relationship between dietary vitamin C intake and NAFLD through logistic regression.

Result

The present cross-sectional study included 3471 subjects. A significant inverse association between dietary vitamin C intake and NAFLD was observed in the energy-adjusted and the multivariable model. The multivariable adjusted ORs (95%CI) for NAFLD were 0.69 (95%CI: 0.54–0.89), 0.93 (95%CI: 0.72–1.20), and 0.71 (95%CI: 0.53–0.95) in the second, third and fourth dietary vitamin C intake quartiles, respectively, compared with the lowest (first) quartile. The relative odds of NAFLD was decreased by 0.71 times in the fourth quartile of dietary vitamin C intake compared with the lowest quartile. After stratifying data by sex or the status of obesity, the inverse association remained valid in the male population or non-obesity population, but not in the female population or obesity population.

Conclusion

There might be a moderate inverse association between dietary vitamin C intake and NAFLD in middle-aged and older adults, especially for the male population and non-obesity population.     

Integrating the contributions of mitochondrial oxidative metabolism to lipotoxicity and inflammation in NAFLD pathogenesis

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing globally. NAFLD includes non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). NASH is the pathological form of the disease characterized by liver steatosis, inflammation, cell injury, and fibrosis. A fundamental contributor to NASH is the imbalance between lipid accretion and disposal. The accumulation of liver lipids precipitates lipotoxicity and the inflammatory contributions to disease progression. This review defines the role of dysregulated of lipid disposal in NAFLD pathophysiology. The characteristic changes in mitochondrial oxidative metabolism pathways and the factors promoting these changes across the spectrum of NAFLD severity are detailed. This includes pathway-specific and integrative perturbations in mitochondrial β-oxidation, citric acid cycle flux, oxidative phosphorylation, and ketogenesis. Moreover, well-recognized and emerging mechanisms through which dysregulated mitochondrial oxidative metabolism mediates inflammation, fibrosis, and disease progression are highlighted.     

n-3 Fatty acids combined with flavan-3-ols prevent steatosis and liver injury in a murine model of NAFLD

Non-alcoholic fatty liver disease (NAFLD) affects 25% of adults and at present no licensed medication has been approved. Despite its complex patho-physiology, dietary strategies aiming at delaying or preventing NAFLD have taken a reductionist approach, examining the impact of single components. Accumulating evidence suggests that n-3 LC-PUFAs are efficacious in regulating lipogenesis and fatty acid oxidation. In addition, plant derived flavonoids are also emerging as a dietary strategy for NAFLD prevention, with efficacy attributed to their insulin sensitising and indirect antioxidant effects. Based on knowledge of their complementary molecular targets, we aimed to demonstrate that the combination of n-3 LC-PUFA (n-3) and flavan-3-ols (FLAV) prevents NAFLD. In a high-fat high-fructose (HF/HFr) fed C57Bl/6 J mouse model, the independent and interactive impact of n-3 and FLAV on histologically defined NAFLD, insulin sensitivity, weight gain, intestinal and hepatic gene expression, intestinal bile acids were examined. Only the combination of FLAV and n-3 (FLAVn-3) prevented steatosis as evidenced by a strong reduction in hepatocyte ballooning. While FLAV reduced body (? 28–30%), adipose tissue (? 45–50%) weights and serum insulin (? 22–25%) as observed following an intra-peritoneal glucose tolerance test, n-3 downregulated the expression of Srebf1 and the lipogenic genes (Acaca, Fasn). Significant impacts of interventions on intestinal bile acid metabolism, farnesoid X receptor (Fxr) signalling in the intestine and liver, and hepatic expression of fatty acid transporters (Fabp4, Vldlr, Cd36) were also evident. FLAVn-3 may be a novel intervention for NAFLD. Future research should aim to demonstrate its efficacy in the prevention and treatment of human NAFLD.     

Polymorphisms of MRP2 (ABCC2) are associated with susceptibility to nonalcoholic fatty liver disease

AimsWe hypothesized that ABCC2 gene variants may contribute to susceptibility to nonalcoholic fatty liver disease (NAFLD). Additionally, we tested the hypothesis of a relation between gene variants and disease severity.Patients and MethodsThe study involved 167 individuals: 109 consecutively presenting unrelated patients with features of NAFLD and different stages of disease severity, and a group of 58 healthy individuals. Four tag single-nucleotide polymorphisms (SNPs; rs717620 A/G, rs2756105 C/T, rs2002042 C/T and rs3740066 A/G) representing 46 polymorphic sites (r²>.8) were genotyped. Furthermore, two additional SNPs (rs17222723 A/T and rs8187710 G/A) were included.ResultsOn univariate analysis, after multiple comparison correction by permutation tests, there were significant differences observed in the allele frequencies of rs17222723 and rs8187710 between healthy individuals and NAFLD patients (empirical P=.037 and .035, respectively). Allelic odds ratios [95% confidence interval] for rs17222723 and rs8187710 were 2.80 [1.11–7.04] and 2.80 [1.11–7.04], respectively. When we tested the hypothesis of a relation between gene variants and the clinical and histological spectra of NAFLD by multinomial regression analysis, a significant association was observed with the same markers: rs17222723 (P=.0029) and rs8187710 (P=.015).ConclusionsOur study suggests a potential role of ABCC2 in susceptibility to NAFLD and disease severity.     

Serum Complement C3f and Fibrinopeptide A Are Potential Novel Diagnostic Biomarkers for Non-Alcoholic Fatty Liver Disease: A Study in Qingdao Twins

Aims

To compare the different serum peptidome patterns between twins with and without non-alcoholic fatty liver disease (NAFLD) in order to help understand the pathogenesis of NAFLD and to identify potential diagnostic and therapeutic targets.

Methods

The peptidomics patterns of 63 cases with NAFLD were compared with their twin healthy controls in Qingdao, China. Peptides between 800Da and 3500Da were captured and concentrated using C18 reversed-phase columns, followed by MALDI-TOF mass spectrometry. The sequences of peptides associated with NAFLD were further identified by MALDI-TOF-TOF. Further validation studies were conducted. One hundred additional serum samples were detected by commercially available ELISA kits to calculate the concentrations of complement C3f and fibrinopeptide A, respectively. The differences of these two peptides in the NAFLD and control groups were compared using SPSS 17.0, respectively.

Results

Compared with healthy controls, eleven peaks (861.1, 877.07, 904.5, 1206.57, 1350.64, 1518.7, 1690.9, 1777.94, 2931.29, 3190.4, 3261.4) were up-regulated and 7 peaks (942.44, 1020.47, 1060.06, 1211.7, 1263.63, 1449.76, 2768.3) were down-regulated in the NAFLD group. Two peptides derived from complement C3f and fibrinopeptide A, respectively, had the highest ROC values indistinguishing NAFLD cases from their normal controls. In the validation group, the concentrations of complement C3f and fibrinopeptide A (1466.929±78.306 pg/ml, 4.189±0.326 ng/ml, respevtively) in NAFLD group was higher than in control group (complement C3f 1159.357±99.624 pg/ml, FPA 3.039±0.483 ng/ml; P<0.05).

Conclusions

In this study, we established apeptidomics pattern that could help distinguish NAFLD patients from their twin controls. The differently-regulated peptides identified in our study may be potential diagnostic markers or therapeutic targets for NAFLD.