The histologic spectrum of nonalcoholic fatty liver disease

(E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone, a Major Homoisoflavonoid, Attenuates Free Fatty Acid-Induced Hepatic Steatosis by Activating AMPK and PPARα Pathways in HepG2 Cells

BACKGROUND

(E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone (HMC), a homoisoflavonoid isolated from Portulaca oleracea, has significant anti-adipogenesis potential; it regulates adipogenic transcription factors. However, whether HMC improves hepatic steatosis in hepatocytes remains vague. This study investigated whether HMC ameliorates hepatic steatosis in free fatty acid-treated human hepatocellular carcinoma (HepG2) cells, and if so, its mechanism of action was analyzed.

METHODS

Hepatic steatosis was induced by a free fatty acid mixture in HepG2 cells. Thereafter, different HMC concentrations (10, 30, and 50 µM) or fenofibrate (10 µM, a PPARα agonist, positive control) was treated in HepG2 cells.

RESULTS

HMC markedly decreased lipid accumulation and triglyceride content in free fatty acid-treated HepG2 cell; it (10 and 50 μM) markedly upregulated protein expressions of pAMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase. HMC (10 and 50 μM) markedly inhibited the expression of sterol regulatory element-binding protein-1c, fatty acid synthase, and stearoyl-coA desaturase 1, which are the enzymes involved in lipid synthesis. Furthermore, HMC (10 and 50 μM) markedly upregulated the protein expression of peroxisome proliferator-activated receptor alpha (PPARα) and enhanced the protein expressions of carnitine palmitoyl transferase 1 and acyl-CoA oxidase 1.

CONCLUSION

HMC inhibits lipid accumulation and promotes fatty acid oxidation by AMPK and PPARα pathways in free fatty acid-treated HepG2 cells, thereby attenuating hepatic steatosis.

Accumulation of α-synuclein in hepatocytes in nonalcoholic steatohepatitis and its usefulness in pathological diagnosis

BACKGROUNDS

Nonalcoholic steatohepatitis (NASH) is characterized by fat deposition, inflammation, and hepatocellular damage. The diagnosis of NASH is confirmed pathologically, and hepatocyte ballooning is an important finding for definite diagnosis. Recently, α-synuclein deposition in multiple organs was reported in Parkinson's disease. Since it was reported that α-synuclein is taken up by hepatocytes via connexin 32, the expression of α-synuclein in the liver in NASH is of interest. The accumulation of α-synuclein in the liver in NASH was investigated. Immunostaining for p62, ubiquitin, and α-synuclein was performed, and the usefulness of immunostaining in pathological diagnosis was examined.

METHODS

Liver biopsy tissue specimens from 20 patients were evaluated. Several antibodies against α-synuclein, as well as antibodies against connexin 32, p62, and ubiquitin were used for immunohistochemical analyses. Staining results were evaluated by several pathologists with varying experience, and the diagnostic accuracy of ballooning was compared.

RESULTS

Polyclonal α-synuclein antibody, not the monoclonal antibody, reacted with eosinophilic aggregates in ballooning cells. Expression of connexin 32 in degenerating cells was also demonstrated. Antibodies against p62 and ubiquitin also reacted with some of the ballooning cells. In the pathologists' evaluations, the highest interobserver agreement was obtained with hematoxylin and eosin (H&E)-stained slides, followed by slides immunostained for p62 and α-synuclein, and there were cases with different results between H&E staining and immunostaining CONCLUSION: These results indicate the incorporation of degenerated α-synuclein into ballooning cells, suggesting the involvement of α-synuclein in the pathogenesis of NASH. The combination of immunostaining including polyclonal α-synuclein may contribute to improving the diagnosis of NASH.

Association between liver fibrosis and decreased myocardial mechano-energetic efficiency in individuals with different degree of glucose tolerance

AIM

Decreased myocardial mechano-energetic efficiency (MEEi) is associated with NAFLD and poorer prognosis in liver cirrhosis. We aim to investigate the association between liver fibrosis severity and MEEi in individuals participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study.

METHODS

Myocardial MEEi, assessed by an echocardiography-derived measure, and fibrosis severity, estimated by the fibrosis-4 index (FIB-4), were evaluated in 2383 subjects with different degree of glucose tolerance. Participants were divided into four groups according to FIB-4 index values: lowest risk of fibrosis (<1.3); low risk of fibrosis (≥1.3 to < 1.67); moderate risk of fibrosis (≥1.67 to < 2.67); high risk of fibrosis (≥2.67).

RESULTS

Subjects with higher risk of liver fibrosis displayed a graded decrease in myocardial MEEi compare to those with the lowest risk of liver fibrosis. In a multivariable regression analysis, FIB-4 index was independently associated with MEEi (β = -0.080, P < 0.001), along with total cholesterol (β = -0.067, P = 0.01), hsCRP (β = -0.081, P < 0.001), sex (β = -0.099, P < 0.001), glucose tolerance status (β = -0.109, <0.001) and HOMA-IR index (β = -0.143, P < 0.001).

CONCLUSION

Compromised myocardial MEEi is already reported in individuals with high risk of hepatic fibrosis suggesting that its assessment may help to identify among subjects with NAFLD those with worst prognosis.

Characterization of signature trends across the spectrum of non-alcoholic fatty liver disease using deep learning method

AIMS

The timely diagnosis of different stages in NAFLD is crucial for disease treatment and reversal. We used hepatocellular ballooning to determine different NAFLD stages.

MAIN METHODS

We analyzed differentially expressed genes (DEGs) in 78 patients with NAFLD and in healthy controls from previously published RNA-seq data. We identified two expression types in NAFLD progression, calculated the predictive power of candidate genes, and validated them in an independent cohort. We also performed cancer studies with these candidates retrieved from the Cancer Genome Atlas.

KEY FINDINGS

We identified 103 DEGs in NAFLD patients compared to healthy controls: 75 genes gradually increased or decreased in the NAFLD stage, whereas 28 genes showed differences only in NASH. The former were enriched in negative regulation and binding-related genes; the latter were involved in positive regulation and cell proliferation. Feature selection showed the gradual up- or down-regulation of 21 genes in NASH compared to controls; 18 were highly expressed only in NASH. Using deep-learning method with subset of features from lasso regression, we obtained reliable determination performance in NAFL and NASH (accuracy: 0.857) and validated these genes using an independent cohort (accuracy: 0.805). From cancer studies, we identified significant differential expression of several candidate genes in LIHC; 5 genes were gradually up-regulated and 6 showing high expression only in NASH were influential to patient survival.

SIGNIFICANCE

The identified biomolecular signatures may determine the spectrum of NAFLD and its relationship with HCC, improving clinical diagnosis and prognosis and enabling a therapeutic intervention for NAFLD.

Steatosis Grading Comparison Between Qualitative Ultrasonography and Magnetic Resonance Spectroscopy in Patients With Nonalcoholic Fatty Liver Disease

Objective:

Assess the correlation between the qualitative sonographic score for detecting hepatic steatosis (HS) and liver fat quantification, using proton magnetic resonance spectroscopy (MRS).

Materials and Methods:

Sixty-six patients with known or suspected nonalcoholic fatty liver disease (NAFLD) underwent ultrasonography (US) and magnetic resonance imaging (MRI). The qualitative sonographic score and fat quantification, measured by MRS, were the techniques used. A Kappa coefficient was used for agreement calculation, and a Fisher test was used to assess the normality of the variables. The MRS results were the gold standard for US quality assessment.

Results:

The agreement between MRS and US was 50% (Kappa 0.35). Ultrasonography results were more severe in 42.4% of the cases, and 66.7% of the patients had a body mass index greater than 30 ( P = .017). For diagnosis of HS, US presented 100% sensitivity, 30.8% to 60% specificity, 61.7% to 72.7% accuracy, 40% to 69.2% false-positive rate, 0% false-negative rate, 53.8% positive predictive value, and 100% negative predictive value.

Conclusion:

Ultrasonography is a reliable exam for detecting HS, although not for grading purposes. Therefore, US is not a good predictor of HS severity for the management and follow-up of NAFLD.

The role of fibrosis index FIB-4 in predicting liver fibrosis stage and clinical prognosis: A diagnostic or screening tool?

This review evaluates the ability of the fibrosis index based on four factors (FIB-4) identifying fibrosis stages, long-time prognosis in chronic liver disease, and short-time outcomes in acute liver injury. FIB-4 was accurate in predicting the absence or presence of advanced fibrosis with cut-offs of 1.0 and 2.65 for viral hepatitis B, 1.45 and 3.25 for viral hepatitis C, 1.30 (<65 years), 2.0 (≥65 years), and 2.67 for non-alcoholic fatty liver disease (NAFLD), respectively, but had a low-to-moderate accuracy in alcoholic liver disease (ALD) and autoimmune hepatitis. It performed better in excluding fibrosis, so we built an algorithm for identifying advanced fibrosis by combined methods and giving work-up and follow-up suggestions. High FIB-4 in viral hepatitis, NAFLD, and ALD was associated with significantly high hepatocellular carcinoma incidence and mortality. Additionally, FIB-4 showed the ability to predict high-risk varices with cut-offs of 2.87 and 3.91 in cirrhosis patients and predict long-term survival in hepatocellular carcinoma patients after hepatectomy. In acute liver injury caused by COVID-19, FIB-4 had a predictive value for mechanical ventilation and 30-day mortality. Finally, FIB-4 may act as a screening tool in the secondary prevention of NAFLD in the high-risk population.

Molecular mechanism of DLBS3733, a bioactive fraction of Lagerstroemia speciosa (L.) Pers., on ameliorating hepatic lipid accumulation in HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lagerstroemia speciosa (L.) Pers., commonly known as banaba and locally known as bungur, is widely used in Indonesia and other countries as a folk remedy for various chronic diseases such as diabetes mellitus and hypertension. L. speciosa (L.) Pers. has been used and evaluated on conditions associated to liver diseases by altering cholesterol absorption, lipid metabolism, as well as the related gene expressions.

AIM OF THE STUDY

The aim of this study is to evaluate the effect of DLBS3733, a standardized bioactive fraction of Lagerstroemia speciosa (L.) Pers. leaves, on ameliorating hepatic steatosis induced by oleic acid, and elucidate its mechanism of action to ameliorate lipid accumulation in HepG2 cells.

MATERIALS AND METHODS

Effects of DLBS3733 on expression of genes and proteins associated with lipid metabolism were evaluated in HepG2 cells in this study. Genes associated with lipid metabolism were evaluated using PCR, while the protein levels were revealed using western blot and ELISA. Cellular lipid accumulations and triglyceride (TG) synthesis were measured using ELISA, and antioxidant assay was conducted using DPPH assay.

RESULTS

DLBS3733 significantly reduced lipid accumulation and TG synthesis by 51% and 32% (p < 0.01), respectively, through the significant increment of adiponectin expression by 58% (p < 0.01). Subsequently, adiponectin enhanced PPARα expression and AMPK phosphorylation which further regulate the downstream signaling pathway of lipogenesis and lipolysis. Moreover, 2.5 µg/mL DLBS3733 was found to significantly downregulate the expression of HMGCR, ACC and SREBP by 66%, 61% and 36%, respectively (p < 0.01), as well as significantly upregulate CPT-1 by 300% at the protein level (P < 0.05). DLBS3733 was also found to possess high antioxidant activity, where the highest concentration exhibited DPPH inhibition activity by up to 93% (P < 0.01).

CONCLUSIONS

We propose that DLBS3733 may provide a prevention on hepatic steatosis through its activity as anti-lipogenesis, anti-cholesterologenesis and pro-lipolysis in HepG2 cells. This is the first report that revealed the molecular mechanism of L. speciosa (L.) Pers. as a potential treatment of hepatic steatosis-related diseases.

Pregnancy and lactation after Roux-en-Y gastric bypass worsen nonalcoholic fatty liver disease in obese rats and lead to differential programming of hepatic de novo lipogenesis in offspring

Maternal obesity increases the risk of nonalcoholic fatty liver disease (NAFLD) in offspring. The Roux-en-Y gastric bypass (RYBG) is effective for achieving weight loss and ameliorates NAFLD. To determine whether these benefits are maintained after pregnancy and/or lactation, and whether they modulate hepatic morphofunction in the next generation, we evaluated hepatic lipid metabolism in Western diet (WD)-obese female rats that underwent RYGB and in their F1 offspring at adulthood. Female Wistar rats consumed a WD from 21 to 130 days of age, before being submitted to RYGB (WD-RYGB-F0) or SHAM (WD-SHAM-F0) operations. After 5 weeks, these females were mated with control male breeders, and the male and female F1 offspring were identified as WD-RYGB-F1 and WD-SHAM-F1. WD-RYGB-F0 dams exhibited lower serum lipids levels, but severe hepatic steatosis and pathological features of advanced liver injury. The hepatic proteins involved in lipogenesis were reduced in WD-RYGB-F0, as were the genes related to β-oxidation and bile acids (BAs). Although the female and male WD-RYGB-F1 groups did not exhibit hepatic steatosis, the livers of female WD-RYGB-F1 demonstrated higher amounts of lipogenic genes and proteins, while male WD-RYGB-F1 presented a similar downregulation of lipogenic factors to that seen in WD-RYGB-F0 dams. In contrast, maternal and offspring groups of both sexes displayed reductions in the expressions of genes involved in BAs physiology and gluconeogenesis. As such, RYGB aggravates NAFLD after pregnancy and lactation and induces a gender-dependent differential expression of the hepatic lipogenesis pathway in offspring, indicating that female WD-RYGB-F1 may be an increased risk of developing NAFLD.

Virtual noncontrast images derived from dual-energy CT for assessment of hepatic steatosis in living liver donors

PURPOSE

This study aimed to investigate the correlation of attenuation between virtual noncontrast (VNC) and true noncontrast (TNC) CT images and compare the diagnostic performance for hepatic steatosis using MR spectroscopy (MRS) as the reference standard.

METHODS

A total of 131 consecutive hepatic donor candidates who underwent dual-source dual-energy CT and MRS within one month from January 2018 to April 2019 were included. An MRS value > 5.8 % was regarded as substantial hepatic steatosis. The correlation of attenuation between TNC and VNC in the liver and spleen, and liver attenuation index (LAI), defined as hepatic minus splenic attenuation, was evaluated using Spearman's rank correlation. The diagnostic performance of the LAI for hepatic steatosis was compared using receiver operating characteristic analyses.

RESULTS

Twenty-three candidates (17.6 %) had substantial hepatic steatosis. The median liver attenuation (66.7 [IQR, 63.5-70.9] vs. 63.5 [IQR, 60.3-66.9], p < .001) and LAI (12.9 [9.3-16.7] vs. 7.4 [3.9-11.9], p < .001) in the VNC were higher than those in the TNC. Hepatic attenuation (r = 0.93, p < .001), splenic attenuation (r = 0.55, p < .001), and LAI (r = 0.87, p < .001) were significantly correlated between TNC and VNC. Area under the curve of LAI in TNC and VNC were 0.88 (cutoff, LAI < 3.1) and 0.84 (cutoff, LAI < 10.1), respectively, indicating no statistically significant difference (p = 0.11).

CONCLUSION

The LAI of VNC is significantly correlated with that of TNC and might be feasible for diagnosing substantial hepatic steatosis in living liver donor candidates using different cutoff values of LAI.

Bisphenol-A exposure worsens hepatic steatosis in ovariectomized mice fed on a high-fat diet: Role of endoplasmic reticulum stress and fibrogenic pathways

AIMS

Bisphenol (BP)-A exposure can impair glucose and lipid metabolism. However, it is unclear whether this endocrine disruptor (ED) modulates these processes in postmenopause, a period with organic changes that increase the risk for metabolic diseases. Herein, we evaluated the effects of BPA exposure on adiposity, glucose homeostasis and hepatic steatosis in ovariectomized (OVX) mice fed on a high-fat diet (HFD).

MAIN METHODS

Adult Swiss female mice were OVX and submitted to a normolipidic diet or HFD and drinking water without [control (OVX CTL) and OVX HFD groups, respectively] or with 1 μg/mL BPA (OVX CBPA and OVX HBPA groups, respectively), for 3 months.

KEY FINDINGS

OVX HFD females displayed increased adiposity, glucose intolerance, insulin resistance and moderate hepatic steatosis. This effect was associated with a high hepatic expression of genes involved in lipogenesis (Srebf1 and Scd1), β-oxidation (Cpt1a) and endoplasmic reticulum (ER) stress (Hspa5 and Hyou1). BPA did not alter adiposity or glucose homeostasis disruptions induced by HFD. However, this ED triggered severe steatosis, exacerbating hepatic fat and collagen depositions in OVX HBPA, in association with a reduction in Mttp mRNA, and up-regulation of genes involved in β-oxidation (Acox1 and Acadvl), mitochondrial uncoupling (Ucp2), ER stress (Hyou1 and Atf6) and chronic liver injury (Tgfb1and Casp8). Furthermore, BPA caused mild steatosis in OVX CBPA females, increasing the hepatic total lipids and mRNAs for Srebf1, Scd1, Hspa5, Hyou1 and Atf6.

SIGNIFICANCE

BPA aggravated hepatic steatosis in OVX mice. Especially when combined with a HFD, BPA caused NAFLD progression, which was partly mediated by chronic ER stress and the TGF-β1 pathway.

Hepatoprotective Effect of Cranberry Nutraceutical Extract in Non-alcoholic Fatty Liver Model in Rats: Impact on Insulin Resistance and Nrf-2 Expression

Background

Non-alcoholic fatty liver disease (NAFLD) is a pathological accumulation of triglycerides (TGs) in the hepatocyte in the absence of alcohol intake. Untreated NAFLD is expected to progress into liver fibrosis. Cranberry is rich in polyphenols with antioxidant and anti-inflammatory activities.

Hypothesis

The present study was performed to evaluate our hypothesis of the possible anti-fibrotic effect of cranberry nutraceuticals in a high fat cholesterol diet induced (HFCD)-NAFLD in rats, focusing on improving insulin sensitivity and modulating the expression of nuclear factor erythroid-2-related factor-2 (Nrf2) (a transcription factor responsible for regulating cellular redox balance).

Method

Male albino wistar rats (12 weeks) received HFCD and/or cranberry (50 and 100 mg/kg/day, three times/week) orally for 8 consecutive weeks.

Results

In comparison to the HFCD group, cranberry treated groups (50 and 100 mg/kg) showed marked hepatoprotection, where it significantly decreased liver enzymes (alanine transaminases by 49 and 64% and aspartate transaminases by 45 and 64%; respectively), TGs, and ameliorated the histopathological alterations (such as inflammatory cells infiltration and ballooning degeneration) induced by HFCD. Cranberry also alleviated oxidative stress (malondialdehyde, glutathione, catalase and superoxide dismutase) and inflammation (tumor necrosis factor- alpha, interleukine-6 and nuclear factor kappa-b) and significantly reduced the HOMA-IR and TyG index. On the other hand, cranberry treated groups (50 and 100 mg/kg) showed a marked increase in the expression of adiponectin, by 8 and 13-fold, insulin receptor substrate-2 by 21 and 79%, and Nrf2 by 13 and 61%, respectively. Notably, cranberry significantly reduced the fibrotic markers, TGF–β and α-SMA expression and collagen deposition.

Conclusion

The present study showed that cranberry significantly attenuated NAFLD, in a dose dependent manner, which could be partially recognized by its antioxidant, anti-inflammatory activities, and its ability to improve insulin sensitivity. Notably, our study proves for the first time that the anti-fibrotic activity of cranberry is promising.

Non-alcoholic fatty liver disease in lean individuals

Non-alcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease, encompassing a spectrum from non-alcoholic fatty liver to non-alcoholic steatohepatitis, which can progress to cirrhosis. It has recently been recognised that NAFLD also occurs in individuals who are not obese, especially in Asian populations. In these patients, NAFLD manifests at lower overall body mass index thresholds in the presence of increased visceral adipose tissue. Currently, the principles of clinical management are similar to those in obese individuals, although, in specific regions and clinical situations, unique aetiologies of NAFLD must be treated specifically.

Inhibiting Extracellular Cathepsin D Reduces Hepatic Steatosis in Sprague⁻Dawley Rats †

Dietary and lifestyle changes are leading to an increased occurrence of non-alcoholic fatty liver disease (NAFLD). Using a hyperlipidemic murine model for non-alcoholic steatohepatitis (NASH), we have previously demonstrated that the lysosomal protease cathepsin D (CTSD) is involved with lipid dysregulation and inflammation. However, despite identifying CTSD as a major player in NAFLD pathogenesis, the specific role of extracellular CTSD in NAFLD has not yet been investigated. Given that inhibition of intracellular CTSD is highly unfavorable due to its fundamental physiological function, we here investigated the impact of a highly specific and potent small-molecule inhibitor of extracellular CTSD (CTD-002) in the context of NAFLD. Treatment of bone marrow-derived macrophages with CTD-002, and incubation of hepatic HepG2 cells with a conditioned medium derived from CTD-002-treated macrophages, resulted in reduced levels of inflammation and improved cholesterol metabolism. Treatment with CTD-002 improved hepatic steatosis in high fat diet-fed rats. Additionally, plasma levels of insulin and hepatic transaminases were significantly reduced upon CTD-002 administration. Collectively, our findings demonstrate for the first time that modulation of extracellular CTSD can serve as a novel therapeutic modality for NAFLD.

Combined effects of DDE and hyperlipidic diet on metallothionein expression and synthesis in rat tissues

Metallothionein is well known for its detoxificant and anti-oxidant properties and has been shown to be effective to prevent hydroxyl radical-generated DNA degradation. The purpose of this investigation was to analyze the combined effect of two factors promoting cellular oxidative-stress, that is, the administration of the pesticide dichloro-diphenyl-dichloroethylene (DDE) and a high fat diet, on metallothionein expression and synthesis in rat liver and kidney. DDE is the main metabolite of dichloro-diphenyl-trichloroethane (DDT), and is commonly found in the food chain and in all tissues of living organisms, carried by the fats. Male Wistar rats were fed with a standard (N) or a high fat (HF) diet and exposed to DDE (10 mg/kg body mass, N + DDE and HF + DDE groups) or vehicle (corn oil, N, and HF groups) via gavage every day for 28 days. Tissues histology was determined by light microscopy analysis; differences in metallothionein gene expression and synthesis by real-time PCR and western blot, respectively. Finally, protein cellular localization was established by immunocytochemistry. The results showed a different involvement of metallothionein in defending tissues from HF- and DDE-induced oxidative stress, suggesting that hepatic and renal cells use different strategies against pro-oxidant species. In both cell types a marked increase in the metallothionein content was observed in the nucleus, with a concomitant drop of the cytoplasmatic protein, either under HF- and DDE-stress conditions; however, no synergistic or additive effects were observed between the action of fats and pesticide. These findings reinforce the role of metallothionein in protecting DNA from oxidative damage.

Natural Extracts Abolished Lipid Accumulation in Cells Harbouring non-favourable PNPLA3 genotype

Background &amp; aims. G-allele of PNPLA3 (rs738409) favours triglycerides accumulation and steatosis. In this study, we examined the effect of quercetin and natural extracts from mushroom and artichoke on reducing lipid accumulation in hepatic cells.

MATERIAL AND METHODS

Huh7.5 cells were exposed to oleic acid (OA) and treated with quercetin and extracts to observe the lipid accumulation, the intracellular-TG concentration and the LD size. Sterol regulatory element binding proteins-1 (SREBP-1), peroxisome proliferator-activated receptor (PPARα-γ) and cholesterol acyltransferase (ACAT) gene expression levels were analysed.

RESULTS

Quercetin decreased the intracellular lipids, LD size and the levels of intracellular-TG through the down-regulation of SREBP-1c, PPARγ and ACAT1 increasing PPARα. The natural-extracts suppressed OA-induced lipid accumulation and the intracellular-TG. They down-regulate the hepatic lipogenesis through SREBP-1c, besides the activation of lipolysis through the increasing of PPARα expression.

CONCLUSIONS

Quercetin and the aqueous extracts decrease intracellular lipid accumulation by down-regulation of lipogenesis and up-regulation of lipolysis.

Anti-steatosis compounds from leaves of Mallotus furetianus

There is no drug administration-approved therapy for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this study, eight compounds, gallic acid (1), methyl gallate (2), corilagin (3), 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (4), repandinin B (5), (Z)-3-hexenyl-β-D-glucopyranoside (6), (+)-lyoniresinol-3α-O-α-L-rhamnopyranoside (7) and mallophenol A (8) were isolated from the active fractions of Mallotus furetianus. Three compounds, (6, 7 and 8) revealed potent anti-steatosis activity in the oleic acid (OA)-induced steatosis cell model, with the minimum effective concentration of 0.05 (6), 0.0005 (7) and 0.0005 (8) μg/mL, which were much lower than the control compound, fibrate (72.4 μg/mL).

FT3/FT4 ratio predicts non-alcoholic fatty liver disease independent of metabolic parameters in patients with euthyroidism and hypothyroidism

OBJECTIVE

This study was performed to evaluate the effects of metabolic parameters and thyroid dysfunction on the development of non-alcoholic fatty liver disease (NAFLD).

METHODS

The current study evaluated a total of 115 patients, 75 female and 40 male. Physical examination and anthropometric measurements were applied to all participants. Hypothyroidism was considered at a thyroid stimulating hormone level ≥ 4.1 mIU/L. Patients with euthyroidism and patients with hypothyroidism were compared. Abdominal ultrasonography was used to diagnose non-alcoholic fatty liver disease. The participants were further compared with regard to the presence of non-alcoholic fatty liver disease. Logistic regression modeling was performed to identify the relationship between non-alcoholic fatty liver disease and independent variables, such as metabolic parameters and insulin resistance.

RESULTS

Non-alcoholic fatty liver disease was identified in 69 patients. The mean waist circumference, body mass index, fasting plasma insulin, HOMA-IR (p<0.001) and FT3/FT4 ratio (p=0.01) values were significantly higher in the patients with NAFLD compared to those without it. Multivariate regression analysis revealed that FT3/FT4 ratio, waist circumference and insulin resistance were independent risk factors for non-alcoholic fatty liver disease.

CONCLUSION

Insulin resistance, enlarged waist circumference, elevated body mass index, higher FT3/FT4 ratio and hypertriglyceridemia are independent risk factors for NADLF, whereas hypothyroidism is not directly related to the condition.

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.

Metabolic syndrome and nonalcoholic fatty liver disease: Is insulin resistance the link?

Metabolic syndrome (MetS) is a disease composed of different risk factors such as obesity, type 2 diabetes or dyslipidemia. The prevalence of this syndrome is increasing worldwide in parallel with the rise in obesity. Nonalcoholic fatty liver disease (NAFLD) is now the most frequent chronic liver disease in western countries, affecting more than 30% of the general population. NAFLD encompasses a spectrum of liver manifestations ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis, which may ultimately progress to hepatocellular carcinoma. There is accumulating evidence supporting an association between NAFLD and MetS. Indeed, NAFLD is recognized as the liver manifestation of MetS. Insulin resistance is increasingly recognized as a key factor linking MetS and NAFLD. Insulin resistance is associated with excessive fat accumulation in ectopic tissues, such as the liver, and increased circulating free fatty acids, which can further promote inflammation and endoplasmic reticulum stress. This in turn aggravates and maintains the insulin resistant state, constituting a vicious cycle. Importantly, evidence shows that most of the patients developing NAFLD present at least one of the MetS traits. This review will define MetS and NAFLD, provide an overview of the common pathophysiological mechanisms linking MetS and NAFLD, and give a perspective regarding treatment of these ever growing metabolic diseases.

Normal controlled attenuation parameter values: a prospective study of healthy subjects undergoing health checkups and liver donors in Korea

BACKGROUND/AIMS

The controlled attenuation parameter (CAP) is a noninvasive method of assessing hepatic steatosis. We defined the normal range of CAP values in healthy subjects and evaluated the associated factors.

METHODS

CAP values were measured in a cohort of healthy subjects who were screened as living liver transplantation donors and those who underwent health checkups. Subjects with current or a history of chronic liver disease, abnormalities on liver-related laboratory tests, or fatty liver on ultrasonography or biopsy were excluded.

RESULTS

The mean age of the 264 recruited subjects (131 males and 133 females; 76 potential liver donors and 188 subjects who had undergone health checkups) was 49.2 years. The mean CAP value was 224.8 ± 38.7 dB/m (range 100.0-308.0 dB/m), and the range of normal CAP values (5th-95th percentiles) was 156.0-287.8 dB/m. The mean CAP value was significantly higher in the health checkup than in the potential liver donor group (227.5 ± 42.0 vs. 218.2 ± 28.3 dB/m, P = 0.040). CAP values did not differ significantly according to gender or age in either group (all P > 0.05). In a multivariate linear regression analysis, body mass index (β = 0.271, P = 0.024) and triglyceride levels (β = 0.348, P = 0.008) were found to be independently associated with CAP values.

CONCLUSION

We determined the normal range of CAP values and found that body mass index and triglyceride levels were associated with the CAP values of healthy subjects.

Saturated free fatty acids induce cholangiocyte lipoapoptosis

Recent studies have identified a cholestatic variant of nonalcoholic fatty liver disease (NAFLD) with portal inflammation and ductular reaction. Based on reports of biliary damage, as well as increased circulating free fatty acids (FFAs) in NAFLD, we hypothesized the involvement of cholangiocyte lipoapoptosis as a mechanism of cellular injury. Here, we demonstrate that the saturated FFAs palmitate and stearate induced robust and rapid cell death in cholangiocytes. Palmitate and stearate induced cholangiocyte lipoapoptosis in a concentration-dependent manner in multiple cholangiocyte-derived cell lines. The mechanism of lipoapoptosis relied on the activation of caspase 3/7 activity. There was also a significant up-regulation of the proapoptotic BH3-containing protein, PUMA. In addition, palmitate-induced cholangiocyte lipoapoptosis involved a time-dependent increase in the nuclear localization of forkhead family of transcription factor 3 (FoxO3). We show evidence for posttranslational modification of FoxO3, including early (6 hours) deacetylation and dephosphorylation that coincide with localization of FoxO3 in the nuclear compartment. By 16 hours, nuclear FoxO3 is both phosphorylated and acetylated. Knockdown studies confirmed that FoxO3 and its downstream target, PUMA, were critical for palmitate- and stearate-induced cholangiocyte lipoapoptosis. Interestingly, cultured cholangiocyte-derived cells did not accumulate appreciable amounts of neutral lipid upon FFA treatment.

CONCLUSION

Our data show that the saturated FFAs palmitate and stearate induced cholangiocyte lipoapoptosis by way of caspase activation, nuclear translocation of FoxO3, and increased proapoptotic PUMA expression. These results suggest that cholangiocyte injury may occur through lipoapoptosis in NAFLD and nonalcoholic steatohepatitis patients.

Pinus densiflora Sieb. et Zucc. alleviates lipogenesis and oxidative stress during oleic acid-induced steatosis in HepG2 cells

Excess accumulation of lipids and oxidative stress in the liver contribute to nonalcoholic fatty liver disease (NAFLD). We hypothesized that Pinus densiflora Sieb. et Zucc. (PSZ) can protect against NAFLD by regulating lipid accumulation and oxidative stress in the liver. To investigate the effect of PSZ upon NAFLD, we used an established cellular model: HepG2 cells treated with oleic acid. Then, the extent of hepatic steatosis and oxidative stress was assessed and levels of inflammatory markers measured. Oleic acid-treated HepG2 cells, compared with controls, had greater lipid accumulation. PSZ decreased lipid accumulation by 63% in oleic acid-treated HepG2 cells. Additionally, PSZ decreased the target gene expression of lipogenesis such as sterol regulatory element binding protein-1c, fatty acid synthase, stearoyl-CoA desaturase-1, diacylglycerol O-acyltransferase-1, and acetyl-CoA carboxylase-1 by 1.75, 6.0, 2.32, 1.93 and 1.81 fold, respectively. In addition, Oleic acid-treated HepG2 cells elicited extensive accumulation of tumor necrosis factor-α (TNFα) by 4.53 fold, whereas PSZ-treated cells decreased the expression of TNFα mRNA by 1.76 fold. PSZ significantly inhibited oxidative stress induced by reactive oxygen species. These results suggest that PSZ has effects on steatosis in vitro and further studies are needed in vivo to verify the current observations.

Animal models are reliably mimicking human diseases? A morphological study that compares animal with human NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a clinical-pathological syndrome that includes a wide spectrum of morphological alterations. In research, animal models are crucial in evaluating not only the pathogenesis of NAFLD and its progression, but also the therapeutic effects of various agents. Investigations on the ultrastructural features of NAFLD in humans are not copious, due to the difficulty to obtain human samples and to the long time of NAFLD to evolve. Translational comparative studies on the reliability of animal models in representing the histopathologic picture as seen in humans are missing. To overcome this lack of investigations, we compared the ultrastructural NAFLD features of an animal model versus human. Sprague-Dawley rats were fed with a high fat diet (HFD) for 1-4 weeks, while control rats were fed with a standard diet. Human specimens were collected from patients with diagnosed fatty liver disease, undergoing liver biopsies or surgery. Rat and human samples were examined by light microscopy and by transmission and high resolution scanning electron microscopy. The present work demonstrated that NAFLD in animal model and in human, share overlapping ultrastructural features. In conclusion, animal HFD represent an appropriate tool in studying the pathogenesis of NAFLD.

Hugan Qingzhi medication ameliorates hepatic steatosis by activating AMPK and PPARα pathways in L02 cells and HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Hugan Qingzhi tablet (HQT), a lipid- lowering traditional Chinese medicine formula, has been used for the prevention and treatment of nonalcoholic fatty liver (NAFLD).

AIM OF THE STUDY

This study was realized to evaluate the effects of HQT-medicated serum on hepatic steatosis using in vitro experiments with cells and explore the relevant mechanisms with method of serum pharmacology.

MATERIALS AND METHODS

A model of hepatic steatosis in the L02 and HepG2 cells was induced by free fatty acid (FFA). The components in the HQT-medicated serum were assayed by high-performance liquid chromatography. Intracellular lipid droplets were detected by Oil Red O staining, and their ultrastructure was examined by transmission electron microscope. The biochemical parameters, including triglyceride (TG), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), total antioxidant capacity (T-AOC), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH), were measured with commercial kits. Furthermore, the expression of adiponectin, AMP-activated protein kinase (AMPK) phosphorylation, sterol regulatory element-binding protein 1 (SREBP-1), peroxisome proliferator activated receptor-α (PPARα), carnitine palmitoyltransferase 1 (CPT-1), and acetyl-CoA oxidase 1 (ACOX1) was analyzed by Western blot and/or quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

RESULTS

Moderate- and high-dose HQT-medicated serum reduced (P<0.05 or P<0.01) the accumulation of lipid droplets and the cellular TG content in L02 and HepG2 cells. They caused significant reductions (P<0.01) in LDH, AST, ALT and MDA and significant increase (P<0.05 or P<0.01) in T-AOC in the culture medium. They also caused increase (P<0.05 or P<0.01) in GSH level and SOD activity in FFA-induced steatotic L02 and HepG2 cells. Furthermore, moderate- and high-dose HQT-medicated serum enhanced (P<0.01) adiponectin expression in a concentration-dependent manner and increased (P<0.05 or P<0.01) the phosphorylation of AMPK and the expression of PPARα, CPT-1, and ACOX1, and reduced (P<0.05 or P<0.01) the expression of SREBP-1.

CONCLUSION

The results suggested that HQT-medicated serum exerts a preventive effect against hepatic steatosis, and the potential mechanism might be activation of AMPK and PPARα pathways.

Targeting Hepatic Glycerolipid Synthesis and Turnover to Treat Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of metabolic abnormalities ranging from simple hepatic steatosis (accumulation of neutral lipid) to development of steatotic lesions, steatohepatitis, and cirrhosis. NAFLD is extremely prevalent in obese individuals and with the epidemic of obesity; nonalcoholic steatohepatitis (NASH) has become the most common cause of liver disease in the developed world. NASH is rapidly emerging as a prominent cause of liver failure and transplantation. Moreover, hepatic steatosis is tightly linked to risk of developing insulin resistance, diabetes, and cardiovascular disease. Abnormalities in hepatic lipid metabolism are part and parcel of the development of NAFLD and human genetic studies and work conducted in experimentally tractable systems have identified a number of enzymes involved in fat synthesis and degradation that are linked to NAFLD susceptibility as well as progression to NASH. The goal of this review is to summarize the current state of our knowledge on these pathways and focus on how they contribute to etiology of NAFLD and related metabolic diseases.

Liver damage is not reversed during the lean period in diet-induced weight cycling in mice

AIM

Weight cycling (WC) is frequent in obesity treatment. We evaluated the degree of regression of the liver damage in WC.

METHODS

C57BL/6 male mice received standard chow (SC, 10% energy from lipids) or high-fat diet (HF, 60% energy from lipids) for 6 months (SC6 or HF6) or a diet that alternated every 2 months (SC2/HF2/SC2 or HF2/SC2/HF2).

RESULTS

The body mass gain followed the HF intake and induced WC in the animals. The liver alanine aminotransferase, triglyceride and cholesterol levels were higher in the groups receiving the HF diet for any period. The plasma insulin and glucose levels were the highest in the HF6 and HF2/SC2/HF2 groups. Any HF intake increased the liver mass. All the groups had some degree of liver steatosis, with the SC6 group exhibiting the lowest level (∼23% compared with 50-70%). The activated hepatic stellate cells were sparse throughout the liver sections from the HF6 and HF2/SC2/HF2 groups. The lowest sterol regulatory element-binding protein-1c (SREBP-1c) level was detected in the SC6 group. The peroxisome proliferator-activated receptor (PPAR)-α expression was higher in the SC6 and SC2/HF2/SC2 groups than in the HF6 and HF2/SC2/HF2 groups that showed reduced expression.

CONCLUSION

WC induced by diet leads to adverse response in the liver, including biochemical and molecular alterations that are not reversed during the lean period of the WC, which must be maintained for a long period to allow the liver to recover from the damage associated with obesity.

Silymarin induces insulin resistance through an increase of phosphatase and tensin homolog in Wistar rats

BACKGROUND AND AIMS

Phosphatase and tensin homolog (PTEN) is a phosphoinositide phosphatase that regulates crucial cellular functions, including insulin signaling, lipid and glucose metabolism, as well as survival and apoptosis. Silymarin is the active ingredient in milk thistle and exerts numerous effects through the activation of PTEN. However, the effect of silymarin on the development of insulin resistance remains unknown.

METHODS

Wistar rats fed fructose-rich chow or normal chow were administered oral silymarin to identify the development of insulin resistance using the homeostasis model assessment of insulin resistance and hyperinsulinemic- euglycemic clamping. Changes in PTEN expression in skeletal muscle and liver were compared using western blotting analysis. Further investigation was performed in L6 cells to check the expression of PTEN and insulin-related signals. PTEN deletion in L6 cells was achieved by small interfering ribonucleic acid transfection.

RESULTS

Oral administration of silymarin at a dose of 200 mg/kg once daily induced insulin resistance in normal rats and enhanced insulin resistance in fructose-rich chow-fed rats. An increase of PTEN expression was observed in the skeletal muscle and liver of rats with insulin resistance. A decrease in the phosphorylation of Akt in L6 myotube cells, which was maintained in a high-glucose condition, was also observed. Treatment with silymarin aggravated high-glucose-induced insulin resistance. Deletion of PTEN in L6 cells reversed silymarin-induced impaired insulin signaling and glucose uptake.

CONCLUSIONS

Silymarin has the ability to disrupt insulin signaling through increased PTEN expression. Therefore, silymarin should be used carefully in type-2 diabetic patients.

Review article: is non-alcoholic fatty liver disease a spectrum, or are steatosis and non-alcoholic steatohepatitis distinct conditions?

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is currently conceptualised as a clinical spectrum that results from a ‘multiple-hit’ process which begins with simple steatosis and subsequently renders the hepatocytes susceptible to a variety of insults. Ultimately, more serious liver injuries like non-alcoholic steatohepatitis (NASH) and cirrhosis may develop. Although the metabolic syndrome is considered the crucial player in the pathogenesis of NAFLD, recent studies have highlighted novel pathophysiological mechanisms in this clinical entity.

AIM

To discuss the pathophysiology of NAFLD based on the hypothesis that simple steatosis and NASH are discrete entities rather than two points on a spectrum.

METHODS

A literature search was conducted in August 2012 on PubMed, Ovid Embase, Ovid Medline and Scopus using the following search terms: steatosis, non-alcoholic steatohepatitis, pathophysiology, fatty liver, natural history and genetics.

RESULTS

Simple steatosis and NASH appear as two distinct pathophysiological entities and progression from pure fatty liver to NASH appears to be so rare as to warrant publication. The possible pathogenetic pathways specifically related to NASH are highlighted.

CONCLUSIONS

Although simple steatosis and non-alcoholic steatohepatitis are currently viewed as two histological subtypes of the unique spectrum of non-alcoholic fatty liver disease, the two conditions are likely distinct not only from a histological but also from a pathophysiological standpoint. Efforts to distinguish simple steatosis from non-alcoholic steatohepatitis using non-invasive modalities should be informed by the current pathophysiology of these two clinical entities.

PPARs in Liver Diseases and Cancer: Epigenetic Regulation by MicroRNAs

Peroxisome-proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors that exert in the liver a transcriptional activity regulating a whole spectrum of physiological functions, including cholesterol and bile acid homeostasis, lipid/glucose metabolism, inflammatory responses, regenerative mechanisms, and cell differentiation/proliferation. Dysregulations of the expression, or activity, of specific PPAR isoforms in the liver are therefore believed to represent critical mechanisms contributing to the development of hepatic metabolic diseases, disorders induced by hepatic viral infections, and hepatocellular adenoma and carcinoma. In this regard, specific PPAR agonists have proven to be useful to treat these metabolic diseases, but for cancer therapies, the use of PPAR agonists is still debated. Interestingly, in addition to previously described mechanisms regulating PPARs expression and activity, microRNAs are emerging as new important regulators of PPAR expression and activity in pathophysiological conditions and therefore may represent future therapeutic targets to treat hepatic metabolic disorders and cancers. Here, we reviewed the current knowledge about the general roles of the different PPAR isoforms in common chronic metabolic and infectious liver diseases, as well as in the development of hepatic cancers. Recent works highlighting the regulation of PPARs by microRNAs in both physiological and pathological situations with a focus on the liver are also discussed.

Down-regulation of phosphatase and tensin homolog by hepatitis C virus core 3a in hepatocytes triggers the formation of large lipid droplets

Hepatitis C virus (HCV) perturbs the host's lipid metabolism and often results in hepatic steatosis. In nonalcoholic fatty liver disease, the intrahepatic down-regulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a critical mechanism leading to steatosis and its progression toward fibrosis and hepatocellular carcinoma. However, whether an HCV infection triggers the formation of large lipid droplets through PTEN-dependent mechanisms is unknown. We assessed PTEN expression in the livers of patients infected with HCV genotype 1 or 3 with or without steatosis. The role of PTEN in the HCV-induced biogenesis of lipid droplets was further investigated in vitro with hepatoma cells transduced with the HCV core protein of genotype 1b or 3a. Our data indicate that PTEN expression was down-regulated at the posttranscriptional level in steatotic patients infected with genotype 3a. Similarly, the in vitro expression of the HCV genotype 3a core protein (but not 1b), typically leading to the appearance of large lipid droplets, down-regulated PTEN expression by a mechanism involving a microRNA-dependent blockade of PTEN messenger RNA translation. PTEN down-regulation promoted in turn a reduction of insulin receptor substrate 1 (IRS1) expression. Interestingly, either PTEN or IRS1 overexpression prevented the development of large lipid droplets, and this indicates that the down-regulation of both PTEN and IRS1 is required to affect the biogenesis of lipid droplets. However, IRS1 knockdown per se did not alter the morphology of lipid droplets, and this suggests that other PTEN-dependent mechanisms are involved in this process.

CONCLUSION

The down-regulation of PTEN and IRS1 is a critical event leading to the HCV genotype 3a-induced formation of large lipid droplets in hepatocytes.

PTEN in liver diseases and cancer

The phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homolog (PTEN)/Akt axis is a key signal transduction node that regulates crucial cellular functions, including insulin and other growth factors signaling, lipid and glucose metabolism, as well as cell survival and apoptosis. In this pathway, PTEN acts as a phosphoinositide phosphatase, which terminates PI3K-propagated signaling by dephosphorylating PtdIns(3,4)P₂ and PtdIns(3,4,5)P₃. However, the role of PTEN does not appear to be restricted only to PI3K signaling antagonism, and new functions have been recently discovered for this protein. In addition to the well-established role of PTEN as a tumor suppressor, increasing evidence now suggests that a dysregulated PTEN expression and/or activity is also linked to the development of several hepatic pathologies. Dysregulated PTEN expression/activity is observed with obesity, insulin resistance, diabetes, hepatitis B virus/hepatitis C virus infections, and abusive alcohol consumption, whereas mutations/deletions have also been associated with the occurrence of hepatocellular carcinoma. Thus, it appears that alterations of PTEN expression and activity in hepatocytes are common and recurrent molecular events associated with liver disorders of various etiologies. These recent findings suggest that PTEN might represent a potential common therapeutic target for a number of liver pathologies.

Hepatocellular ballooning in NASH

BACKGROUND & AIMS

Hepatocellular ballooning is a key finding in nonalcoholic steatohepatitis (NASH). It is conventionally defined by hemotoxylin and eosin (H&E) staining showing enlarged cells with rarefied cytoplasm and recently by changes in the cytoskeleton. Fat droplets are emerging as important organelles in cell metabolism. To address a possible relation between fat droplets and ballooning, we studied fat staining, H&E, and keratin 18 staining in human NASH.

METHODS

Sequential staining and high resolution imaging were used to study freshly prepared cryo-sections from 10 patients with histologically confirmed steatohepatitis using oil red O for fat droplet identification, H&E to identify ballooning, and anti-K18 to confirm cytoskeletal changes. High resolution images were captured at each stage using the Aperio Scanscope. To provide ultrastructural correlation, glutaraldehyde-fixed specimens were studied using transmission electron microscopy (TEM) with serial sectioning for localization of ballooned cells by light microscopy and TEM in identical specimens.

RESULTS

Serial staining consistently demonstrated that hepatocellular ballooning is associated with fat droplet accumulation evident by oil red O positivity and depletion of cytoplasmic keratin 18 with K-18 positive Mallory-Denk bodies (MDB). TEM confirmed the association between osmium stained fat droplets, MDB formation, and cellular enlargement and suggested droplet-associated dilation of the endoplasmic reticulum.

CONCLUSIONS

These results indicate a relationship between cellular ballooning, fat droplet accumulation, and cytoskeletal injury in NASH. We speculate that injury to multiple, organelles including fat droplets and endoplasmic reticulum, contribute to this characteristic finding.

Comparison of noninvasive markers of fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND & AIMS

There is a need for a reliable and inexpensive noninvasive marker of hepatic fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). We compared the performance of the FIB4 index (based on age, aspartate aminotransferase [AST] and alanine aminotransferase [ALT] levels, and platelet counts) with 6 other non-invasive markers of fibrosis in patients with NAFLD.

METHODS

Using a nation-wide database of 541 adults with NAFLD, jackknife-validated areas under receiver operating characteristic curves (AUROC) of FIB4 and 7 other markers were compared. The sensitivity at 90% specificity, 80% positive predictive value, and 90% negative predictive values were determined along with cutoffs for advanced fibrosis.

RESULTS

The median FIB4 score was 1.11 (interquartile range = 0.74-1.67). The jackknife-validated AUROC for FIB4 was 0.802 (95% confidence interval [CI], 0.758-0.847), which was higher than that of the NAFLD fibrosis score (0.768; 95% CI, 0.720-0.816; P = .09), Goteburg University Cirrhosis Index (0.743; 95% CI, 0.695-0.791; P < .01), AST:ALT ratio (0.742; 95% CI, 0.690-0.794; P < .015), AST:platelet ratio index (0.730; 95% CI, 0.681-0.779; P < .001), AST:platelet ratio (0.720; 95% CI, 0.669-0.770; P < .001), body mass index, AST:ALT, diabetes (BARD) score (0.70; P < .001), or cirrhosis discriminant score (0.666; 95% CI, 0.614-0.718; P < .001). For a fixed specificity of 90% (FIB4 = 1.93), the sensitivity in identifying advanced fibrosis was only 50% (95% CI, 46-55). A FIB4 > or = 2.67 had an 80% positive predictive value and a FIB4 index < or = 1.30 had a 90% negative predictive value.

CONCLUSIONS

The FIB4 index is superior to 7 other noninvasive markers of fibrosis in patients with NAFLD; however its performance characteristics highlight the need for even better noninvasive markers.

Unsaturated fatty acids promote hepatoma proliferation and progression through downregulation of the tumor suppressor PTEN

BACKGROUND/AIMS

The impact of dietary fatty acids on the development of cancers is highly controversial. We recently demonstrated that unsaturated fatty acids trigger the downregulation of the tumor suppressor PTEN through an mTOR/NF-kappaB-dependent mechanism in hepatocytes. In this study, we investigated whether unsaturated fatty acids promote hepatoma progression by downregulating PTEN expression.

METHODS

The effects of fatty acids and PTEN-specific siRNAs on proliferation, invasiveness and gene expression were assessed using HepG2 hepatoma cells. The tumor promoting activity of unsaturated fatty acids was evaluated in vivo using HepG2 xenografts in nude mice.

RESULTS

Incubation of HepG2 cells with unsaturated fatty acids, or PTEN-specific siRNAs, increased cell proliferation, cell migration and invasiveness, and altered the expression of genes involved in inflammation, epithelial-to-mesenchymal transition and carcinogenesis. These effects were dependent on PTEN expression levels and were prevented by mTOR and NF-kappaB inhibitors. Consistent with these data, the development and size of subcutaneous HepG2-derived tumors in nude mice xenografts were dramatically increased when mice were fed with an oleic acid-enriched diet, even in the absence of weight gain.

CONCLUSIONS

These data demonstrate that dietary unsaturated fatty acids promote hepatoma progression by reducing the expression of the tumor suppressor PTEN.

A decision analysis study of the value of a liver biopsy in nonalcoholic steatohepatitis

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is an increasingly prevalent clinical syndrome reflecting a mixture of pathological liver histology with the potential to progress to cryptogenic cirrhosis. Liver biopsy (LB) is the only way to determine the severity of disease. However, LB is invasive, has complications and financial costs. The aim of this study is to determine the benefits of early LB for diagnosis and early treatment.

METHODS

A decision tree model tracked the potential outcomes of NAFLD between an LB-directed approach vs. no initial LB. Each specific biopsy category determined subsequent care actions. The baseline probabilities were determined by literature review and expert opinion.

RESULTS

An initial LB strategy was projected to have a lower mortality compared with the no initial LB group and fewer transplant eligible patients after 5 years. If the prevalence of NAFLD is increased, the mortality increases in both the study groups. With improved efficacy of medical and/or surgical intervention, the mortality rate was decreased.

CONCLUSION

This decision tree model provides a context for balancing the risk and benefit of LB in NAFLD. With early biopsy, and early intervention, the relative return of preventing advanced liver disease per LB was high.

Activation and dysregulation of the unfolded protein response in nonalcoholic fatty liver disease

BACKGROUND & AIMS

Nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH) are associated with known triggers of the unfolded protein response (UPR). The aims were to (1) evaluate the activity of UPR in NAFL and NASH and (2) correlate expression of UPR pathways with liver histology.

METHODS

Messenger RNA (mRNA) and protein expression were measured by quantitative real-time PCR and Western blot, respectively. Apoptosis was assessed by TUNEL assay. Liver histology was scored using the NASH clinical research network criteria.

RESULTS

Compared with subjects with the metabolic syndrome and normal liver histology (n = 17), both NAFL (n = 21) and NASH (n = 21) were associated with increased eukaryotic initiation factor-2alpha (eIF-2alpha) phosphorylation. Activating transcription factor 4 (ATF4) mRNA and protein, C/EBP homologous protein (CHOP), and growth arrest, DNA damage-34 (GADD34) mRNA were not increased in NAFL or NASH. Whereas immunoglobulin heavy chain binding protein mRNA was significantly increased in NASH, unspliced X-box protein-1 (XBP-1) protein did not increase. Also, endoplasmic reticulum degradation-enhancing alpha-mannosidase-like protein mRNA levels were inversely related to spliced XBP-1 mRNA in NASH. NASH was specifically associated with low sXBP-1 protein and increased JNK phosphorylation. This correlated with increased TUNEL activity in NASH. The histologic severity correlated with sXBP-1 mRNA and JNK phosphorylation.

CONCLUSIONS

There is a variable degree of UPR activation in NAFL and NASH. Although both NAFL and NASH are associated with eIF-2alpha phosphorylation, there is a failure to activate downstream recovery pathways, ie, ATF4-CHOP-GADD34. NASH is specifically associated with (1) failure to generate sXBP-1 protein and (2) activation of JNK.

Regenerative capacity differs between micro- and macrovesicular hepatic steatosis

INTRODUCTION

Independent of etiology, the hepatic microvesicular steatosis has a worse prognosis compared with macrovesicular steatosis. Proliferation compensates for apoptosis and reflects regenerative mechanisms following liver injury. It is unknown whether these two types of fatty liver have differences in regenerative capacity and apoptosis, which could have an impact on their prognosis.

METHODS

Two groups of pigs were studied for 72 days under a protein-deficient diet. One group received only protein-deficient diet (n=6), the other was treated in addition to the diet with 6g ethanol/kg/day by means of a percutaneous intragastric catheter (n=6). The rate of proliferating and apoptotic hepatocytes was determined, respectively, by proliferation cell nuclear antigen (PCNA) and ISEL/TUNEL staining for apoptosis in liver biopsies with similar steatosis grade in pigs with micro- or macrovesicular fatty liver.

RESULTS

The ethanol-treated group developed microvesicular steatosis, the other group developed macrovesicular steatosis. Proliferation index was significantly increased in macrovesicular in comparison with microvesicular steatosis (p<0.05). Apoptosis rate was similar in both groups.

CONCLUSIONS

Regeneration, but not apoptosis rate differs between micro- and macrovesicular steatosis. The reduced regenerative capacity in microvesicular steatosis may contribute to the worse prognosis of this subtype of fatty liver disease.

Prevalence and risk factors of non-alcoholic fatty liver disease in potential living liver donors in Korea: a review of 589 consecutive liver biopsies in a single center

BACKGROUND/AIMS

The aim of the study was to evaluate the prevalence and risk factors of biopsy-proven non-alcoholic fatty liver disease (NAFLD) in potential living liver donors and to evaluate the efficacy of imaging techniques for the detection of steatosis in donors.

METHODS

We reviewed the results of liver biopsy, ultrasonography (USG) and computed tomography (CT) and biochemical data performed in 589 consecutive potential liver donors as a pretransplantation work up from July 2004 to September 2005 at Asan Medical Centre.

RESULTS

Of 589 participants, 408 (69.3%) were men, with a mean age of 31.1+/-9.5 years. NAFLD (5% steatosis in biopsy) was diagnosed in 303 (51.4%); >30% steatosis in 61 (10.4%) and non-alcoholic steatohepatitis in 13 (2.2%). The independent risk factors for >30% steatosis were age over 30 (OR=2.223; p=0.014), obesity (OR=5.320; p<0.001) and hypertriglyceridemia (OR=2.253; p=0.019) by multivariate analysis. The sensitivity of USG and CT for detecting >30% steatosis was 92.3% and 64.1%, and positive predictive value was only 34.5% and 45.1%, respectively.

CONCLUSIONS

NAFLD was highly prevalent in potential living liver donors. The independent risk factors for significant steatosis were older age, obesity and hypertriglyceridemia. USG and CT had limitations in detecting significant steatosis in liver donors.

Glycogenic hepatopathy: an underrecognized hepatic complication of diabetes mellitus

Reported are the clinical and pathologic features of glycogenic hepatopathy, a pathologic overloading of hepatocytes with glycogen that is associated with poorly controlled diabetes mellitus. Fourteen cases were studied by stains, including hematoxylin and eosin, trichrome, periodic acid-Schiff, and periodic acid-Schiff with diastase. Ultrastructural analysis was performed in 2 cases. Medical records were reviewed for clinical presentations, laboratory findings, and clinical outcomes. The individuals ranged from 8 to 25 years of age. All had type I diabetes mellitus with poor glycemic control. The clinical presentations included hepatomegaly, abdominal pain, and elevated transaminases (range, 50-1600 IU/L). The transaminases were dramatically elevated in 3 cases to greater than 10 times the upper limit of normal. All biopsies showed diffusely pale staining hepatocytes on hematoxylin and eosin stains, with excessive glycogen accumulation demonstrated by periodic acid-Schiff stains. Ultrastructural examination revealed marked glycogen accumulation in the cytoplasm and nuclei. Most cases showed no evidence for fatty liver disease: steatosis was absent in 12 of 14 cases, simple steatosis was seen in 1 of 14 cases, and mild steatohepatitis was present in 1 of 14 cases. Mallory hyaline was absent in all cases, acidophil bodies were only rarely seen, and inflammation was absent or minimally present. Fibrosis was typically absent, with only 2 cases demonstrating focal mild fibrosis. Three patients had adequate follow-up and demonstrated improvement of liver enzyme levels with control of blood glucose. We conclude that glycogenic hepatopathy can cause hepatomegaly and significant transaminase elevations in individuals with type I diabetes mellitus. The pathology is distinct from steatohepatitis.

Similarities and differences in outcomes of cirrhosis due to nonalcoholic steatohepatitis and hepatitis C

The objective of this study was to prospectively define outcomes of cirrhosis due to nonalcoholic steatohepatitis (NASH) and compare them with those associated with hepatitis C virus (HCV) infection. We compared 152 patients with cirrhosis due to NASH with 150 matched patients with cirrhosis due to HCV. Over 10 years, 29/152 patients with cirrhosis due to NASH died compared with 44/150 patients with HCV (P < .04). This was mainly due to the lower mortality rate in patients with Child class A cirrhosis due to NASH versus HCV (3/74 vs. 15/75; P < .004). There were no significant across-group differences in mortality in patients with Child class B or C cirrhosis. Sepsis was the most common cause of death in both groups; patients with NASH had a higher cardiac mortality (8/152 vs. 1/150; P < .03). Patients with Child class A cirrhosis due to NASH also had a significantly lower risk of decompensation, defined by a 2-point increase in Child-Turcotte-Pugh score (P < .007). Cirrhosis due to NASH was associated with a lower rate of development of ascites (14/101 vs. 40/97 patients at risk; P < .006). NASH also had a significantly lower risk of development of hepatocellular carcinoma (10/149 vs. 25/147 patients at risk; P < .01). In conclusion, compensated cirrhosis due to NASH is associated with a lower mortality rate compared with that due to HCV. It is also associated with a lower rate of development of ascites, hyperbilirubinemia, and hepatocellular carcinoma. However, cardiovascular mortality is greater in patients with NASH.

Approach to the diagnosis and treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease in the United States. It describes several clinicopathologic entities from simple hepatic steatosis to nonalcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma. This article describes the epidemiology, clinical features, natural history, and pathogenesis of NAFLD.