Nonalcoholic steatohepatitis: risk factors and diagnosis

Discovery of dual rho-associated protein kinase 1 (ROCK1)/apoptosis signal-regulating kinase 1 (ASK1) inhibitors as a novel approach for non-alcoholic steatohepatitis (NASH) treatment

In the current study we suggest a novel approach to curb non-alcoholic steatohepatitis (NASH) progression, and we suggest privileged scaffolds for the design of novel compounds for this aim. NASH is an advanced form of non-alcoholic fatty liver disease that can further progress into fibrosis, cirrhosis, and hepatocellular carcinoma. It is a widely emerging disease affecting 25% of the global population and has no current approved treatments. Protein kinases are key regulators of cellular pathways, of which, Rho-associated protein kinase 1 (ROCK1) and apoptosis signal-regulating kinase 1 (ASK1) play an important role in the progression of NASH and they stand out as promising targets for NASH therapy. Interestingly, their kinase domains are found to be similar in sequence and topology; therefore, dual inhibition of ROCK1 and ASK1 is expected to be amenable and could achieve a more favourable outcome. To reach this goal, a training set of ROCK1 and ASK1 protein structures co-crystalized with type 1 (ATP-competitive) inhibitors was constructed to manually generate receptor-based pharmacophore models representing ROCK1 and ASK1 inhibitors' common pharmacophoric features. The models produced were assessed using a test set of both ROCK1 and ASK1 actives and decoys, and their performance was evaluated using different assessment metrics. The best pharmacophore model obtained, showing a Mathew's correlation coefficient (MCC) of 0.71, was then used to screen the ZINC purchasable database retrieving 6178 hits that were filtered accordingly using several medicinal chemistry and pharmacokinetics filters returning 407 promising compounds. To confirm that these compounds are capable of binding to the target kinases, they were subjected to molecular docking simulations at both protein structures. The results were then assessed individually and filtered, setting the spotlight on various privileged scaffolds that could be exploited as the nucleus for designing novel ROCK1/ASK1 dual inhibitors.

Meta-analysis: Impact of intragastric balloon therapy on NAFLD-related parameters in patients with obesity

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease affecting approximately 25% of adults in the western world. Intragastric balloon (IGB) is an endoscopic bariatric therapy -a therapeutic endoscopic tool that has shown promise in inducing weight loss. Its role in the treatment of NAFLD is yet to be established.

AIM

To evaluate the effect of IGB as a treatment option in NAFLD.

METHODS

We searched MEDLINE (PubMed) and EMBASE from inception to September 2022. We included studies evaluating the impact of IGB on obesity with the assessment of one or more liver-related outcomes and studies primarily evaluating the impact of IGB on NAFLD. We included comparative and non-comparative studies; primary outcomes were liver-related NAFLD surrogates.

RESULTS

We included 19 studies with 911 patients. IGB demonstrated an effect on NAFLD parameters including NAFLD activity score (NAS): mean difference (MD): -3.0 [95% CI: -2.41 to -3.59], ALT: MD: -10.40 U/L [95% CI: -7.31 to -13.49], liver volume: MD -397.9 [95% CI: -212.78 to 1008.58] and liver steatosis: MD: -37.76 dB/m [95% CI: -21.59 to -53.92]. There were significant reductions in non-liver-related outcomes of body weight, BMI, glycated haemoglobin and HOMA-IR.

CONCLUSION

Intragastric balloons may play an important role in addressing the treatment gap in NAFLD management.

A machine-learning approach for nonalcoholic steatohepatitis susceptibility estimation

BACKGROUND

Nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, can lead to advanced liver damage and has become an increasingly prominent health problem worldwide. Predictive models for early identification of high-risk individuals could help identify preventive and interventional measures. Traditional epidemiological models with limited predictive power are based on statistical analysis. In the current study, a novel machine-learning approach was developed for individual NASH susceptibility prediction using candidate single nucleotide polymorphisms (SNPs).

METHODS

A total of 245 NASH patients and 120 healthy individuals were included in the study. Single nucleotide polymorphism genotypes of candidate genes including two SNPs in the cytochrome P450 family 2 subfamily E member 1 (CYP2E1) gene (rs6413432, rs3813867), two SNPs in the glucokinase regulator (GCKR) gene (rs780094, rs1260326), rs738409 SNP in patatin-like phospholipase domain-containing 3 (PNPLA3), and gender parameters were used to develop models for identifying at-risk individuals. To predict the individual's susceptibility to NASH, nine different machine-learning models were constructed. These models involved two different feature selections including Chi-square, and support vector machine recursive feature elimination (SVM-RFE) and three classification algorithms including k-nearest neighbor (KNN), multi-layer perceptron (MLP), and random forest (RF). All nine machine-learning models were trained using 80% of both the NASH patients and the healthy controls data. The nine machine-learning models were then tested on 20% of both groups. The model's performance was compared for model accuracy, precision, sensitivity, and F measure.

RESULTS

Among all nine machine-learning models, the KNN classifier with all features as input showed the highest performance with 86% F measure and 79% accuracy.

CONCLUSIONS

Machine learning based on genomic variety may be applicable for estimating an individual's susceptibility for developing NASH among high-risk groups with a high degree of accuracy, precision, and sensitivity.

Gut Microbiome in Non-Alcoholic Fatty Liver Disease: From Mechanisms to Therapeutic Role

Non-alcoholic fatty liver disease (NAFLD) is considered to be a significant health threat globally, and has attracted growing concern in the research field of liver diseases. NAFLD comprises multifarious fatty degenerative disorders in the liver, including simple steatosis, steatohepatitis and fibrosis. The fundamental pathophysiology of NAFLD is complex and multifactor-driven. In addition to viruses, metabolic syndrome and alcohol, evidence has recently indicated that the microbiome is related to the development and progression of NAFLD. In this review, we summarize the possible microbiota-based therapeutic approaches and highlight the importance of establishing the diagnosis of NAFLD through the different spectra of the disease via the gut–liver axis.

Impact of Metabolic Syndrome on Postoperative Outcomes Among Medicare Beneficiaries Undergoing Hepatectomy

INTRODUCTION

The impact of metabolic syndrome (MetS) on postoperative outcomes following liver surgery is not well studied. The objective of the current study was to examine the association of MetS with individual perioperative outcomes, as well as the composite "textbook outcome" (TO) following liver resection for both benign and malignant indications.

METHODS

The Medicare 100% Standard Analytic Files were reviewed to identify Medicare beneficiaries who underwent hepatectomy between 2013 and 2017. The impact of MetS on complications, length of stay (LOS), 90-day readmission, 90-day mortality, and TO following hepatectomy was investigated.

RESULTS

Among 13,898 patients who underwent hepatectomy, 2491 (17.9%) had MetS while 11,407 (82.1%) did not. Patients with MetS were more often male (59.1% vs 48.5%), Black (8.5% vs 6.6%), and had a diagnosis of cancer (69.9% vs 65.1%) (all p<0.001). On multivariable analysis, patients with MetS had higher odds of complications (OR 1.41, 95% CI 1.28-1.55), 90-day readmission (OR 1.27, 95% CI 1.15-1.40), and 90-day mortality (OR 1.32, 95% CI 1.13-1.54). In turn, patients with MetS had markedly lower odds of TO following hepatectomy compared with non-MetS patients (OR=0.76, 95% CI 0.70-0.83). Of note, patients with MetS had lower odds of TO after both minimally invasive (OR=0.59, 95% CI 0.43-0.81) and open (OR=0.75, 95% CI 0.68-0.82) liver surgery. Individuals with MetS also had a higher overall expenditure during the index hospitalization compared with non-MetS patients ($19.9k USD vs. $18.8k USD, p<0.001).

CONCLUSION

Patients with MetS had increased morbidity and mortality, as well as lower likelihood to achieve a TO following liver resection. MetS increased the operative risk and overall Medicare expenditures associated with hepatic resection.

Association between the Severity of Nonalcoholic Fatty Liver Disease and the Risk of Coronary Artery Calcification

Background and Objectives: There are limited data on the association between severity of non-alcoholic fatty liver disease (NAFLD) and coronary artery calcification. This study investigated sonographic diagnosed NAFLD and coronary artery calcium score (CAC) as detected by cardiac multidetector computed tomography in general populations. Materials and Methods: A total of 545 patients were enrolled in this study. NAFLD was diagnosed by ultrasonography examination and CAC score were evaluated by cardiac multidetector computed tomography. The association between NAFLD and artery calcium score stage was determined by logistic regression analysis and Spearman correlation coefficient analysis. Results: Of all the participants, 437 (80.2%) had ultrasonography-diagnosed NAFLD and 242 (44%) had coronary artery calcification (CAC > 0). After adjustment for cardiovascular risk factors, the risk of developing coronary artery calcification was 1.36-fold greater in the patients with different severity of NAFLD compared to those without NAFLD (OR = 1.36, 95% CI = 1.07-1.77, p = 0.016). The highest OR for separate coronary artery calcification was 1.98 (OR = 1.98, 95% CI = 1.37-2.87, p < 0.001) in the left main artery, and the risk was still 1.71-fold greater after adjustments (OR = 1.71, 95% CI = 1.16-2.54, p = 0.007). Conclusions: This cross-sectional study demonstrated that the severity of NAFLD was associated with the presence of significant coronary artery calcification, especially in the left main coronary artery, suggesting increasing the cardiovascular risk.

Metabolic Syndrome Exponentially Increases the Risk of Adverse Outcomes in Operative Diverticulitis

BACKGROUND

Metabolic syndrome (MS) is defined as the cluster: hypertension, obesity, and diabetes. Operative diverticulitis in the setting of MS can be challenging to manage. The aim of our study was to evaluate the impact of MS on outcomes in operative acute diverticulitis patients.

METHODS

We analyzed the (2012-2015) NSQIP database. We identified acute diverticulitis patients who underwent surgery. MS was defined as follows: body mass index (BMI) >30 kg/m², hypertension, and diabetes. Our primary outcome measure was the occurrence of any adverse events (complications, 30-d readmission, and mortality). Secondary outcome measures were complications, hospital length of stay, 30-d readmission, and mortality. Regression and receiver operating characteristic curve analysis was performed.

RESULTS

A total of 4572 patients were identified. Mean BMI was 29 ± 10 kg/m². 14.6% (275) of obese patients had metabolic syndrome. Adverse events were higher in patients with MS (odds ratio [OR], 8.1; P < 0.001) versus the obese group and the obese and hypertensive group. Patients with MS had higher odds of reintubation (OR 1.9; P = 0.03), >48 h ventilator dependence (OR 3.5; P = 0.01), myocardial infarction (OR 2.3; P = 0.03), and superficial or deep surgical-site infections (OR 2.1; P = 0.01) compared with patients with no MS. MS patients had a longer length of stay (β = 1.23; P = 0.02), higher 30-d readmissions (OR 1.7; P < 0.01), and mortality (OR 2.1; P < 0.01). The area under the receiver operating characteristic curve of metabolic syndrome for predicting adverse outcomes was 0.797, which was higher than the area under the receiver operating characteristic curve for BMI (0.58), hypertension (0.51), or diabetes (0.64) alone.

CONCLUSIONS

Adverse events in patients with MS after surgery for diverticulitis are higher than obesity, hypertension, or diabetes alone. Patients with MS have longer recovery, and higher rates of complications, readmissions, and mortality.

LEVEL OF EVIDENCE

Level III Prognostic.

Human induced pluripotent stem cell-derived extracellular vesicles reduce hepatic stellate cell activation and liver fibrosis

Progression of fibrosis and the development of cirrhosis are responsible for the liver related morbidity and mortality associated with chronic liver diseases. There is currently a great unmet need for effective anti-fibrotic strategies. Stem cells play a central role in wound healing responses to restore liver homeostasis following injury. Here we tested the hypothesis that extracellular vesicles (EVs) isolated from induced pluripotent stem cells (iPSC) modulate hepatic stellate cell (HSCs) activation and may have anti-fibrotic effects. Human iPSCs were generated by reprogramming primary skin fibroblasts. EVs were isolated by differential centrifugation, quantified by flow cytometry (FACS) and characterized by dynamic light scattering (DLS) and electron microscopy (TEM). Primary human HSCs were activated with TGFβ (10 ng/mL) and exposed to iPSC-EVs. Efficacy of iPSC-EVs was tested on HSC in vitro and in two murine models of liver injury (CCl4 and bile duct ligation). Characterization of iPSC-derived EVs by flow cytometry identified a large population of EVs released by iPSC, primarily with a diameter of 300 nm and that could be visualized by TEM as round, cup-shaped objects. Fluorescent tracing assays detected iPSC-EVs in HSC cytosol after a short incubation and EV uptake by HSCs resulted in both decrease of pro-fibrogenic markers αSMA, CollagenIα1, Fibronectin and TIMP-1 and HSC pro-fibrogenic responses such as chemotaxis and proliferation. Genomics analyses of iPSC-EV miRNA cargo revealed 22 highly expressed miRNAs, among which miR-92a-3p resulted the most abundant. Transcriptome analysis identified 60 genes down-modulated and 235 up-regulated in TGF-β-primed HSC in presence or absence of iPSC-EVs. Intravenous injection of iPSC-EVs in CCl4 and bile duct ligation-induced liver fibrosis resulted in anti-fibrotic effects at protein and gene levels. Results of this study identify iPSC-EVs as a novel anti-fibrotic approach that may reduce or reverse liver fibrosis in patients with chronic liver disease.

Diagnosis and Evaluation of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis, Including Noninvasive Biomarkers and Transient Elastography

The incidence and prevalence of nonalcoholic fatty liver disease (NAFLD) are increasing and identification of people at risk of disease progression is extremely important. The current gold standard for diagnosing NAFLD/nonalcoholic steatohepatitis (NASH) is by liver biopsy, but it has several limitations. Noninvasive tests via biomarkers and transient elastography to assess NAFLD/NASH are being used in clinical practice. The most validated diagnostic panels include the NAFLD fibrosis score, FIB-4 (Fibrosis-4), and FibroMeter. Transient elastography is very useful in evaluating advanced fibrosis and cirrhosis.

Non-alcoholic fatty liver disease: A sign of systemic disease

Non-alcoholic fatty liver disease (NAFLD) is the most common form of liver disease and leading cause of cirrhosis in the United States and developed countries. NAFLD is closely associated with obesity, insulin resistance and metabolic syndrome, significantly contributing to the exacerbation of the latter. Although NAFLD represents the hepatic component of metabolic syndrome, it can also be found in patients prior to their presentation with other manifestations of the syndrome. The pathogenesis of NAFLD is complex and closely intertwined with insulin resistance and obesity. Several mechanisms are undoubtedly involved in its pathogenesis and progression. In this review, we bring together the current understanding of the pathogenesis that makes NAFLD a systemic disease.

Epidemiology and natural history of non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis (NASH) is part of the spectrum of non-alcoholic fatty liver disease (NAFLD) that leads to progressive liver disease and presents a growing challenge to public health. Because of the increased prevalence of metabolic syndrome and obesity, NAFLD and NASH have expanded to a substantial extent. In NASH patients, advanced fibrosis is the major predictor of morbidity and liver-related mortality, and an accurate diagnosis of NASH is mandatory. Although there is currently no validated test of serum biomarkers available to diagnose NASH, and histologic evaluation with a liver biopsy remains the gold standard, screening for fibrosis is recommended in patients with suspicion of NASH. Clinical prediction models and serum biomarkers for advanced fibrosis have relatively good negative predictive value and can be useful for screening. Also, transient elastography is increasingly available to estimate fibrosis in NASH. Therefore, due to the lack of a reliable and accepted non-invasive diagnostic modality, screening for NASH in the general population is not currently recommended. Better understanding of the natural history of NASH is needed to evaluate the utility and cost-effectiveness of screening.

Lipopolysaccharide-binding protein plasma levels as a biomarker of obesity-related insulin resistance in adolescents

Purpose

Lipopolysaccharide-binding protein (LBP) is a 65-kDa acute phase protein, derived from the liver, which is present in high concentrations in plasma. Data regarding the association between circulating plasma LBP levels and obesity-related biomarkers in the pediatric population are scarce. We aimed to determine whether there was a difference in plasma LBP levels between overweight/obese and normal-weight adolescents and to assess the correlation of circulating LBP levels with anthropometric measures and obesity-related biomarkers, including insulin resistance, liver enzyme levels, and lipid profiles.

Methods

The study included 87 adolescents aged 12–13 years; 44 were overweight/obese and 43 were of normal-weight. We assessed anthropometric and laboratory measures, including body mass index (BMI), blood pressure, insulin resistance, liver enzyme levels, and lipid profiles. Plasma LBP levels were measured using an enzyme-linked immunosorbent assay.

Results

The mean age of the participants was 12.9±0.3 years. Circulating plasma LBP levels were significantly increased in overweight/obese participants compared with those in normal-weight participants (7.8±1.9 µg/mL vs. 6.0±1.6 µg/mL, P<0.001). LBP levels were significantly and positively associated with BMI, systolic blood pressure, aspartate aminotransferase, alanine aminotransferase, total cholesterol, low density lipoprotein-cholesterol, fasting glucose and insulin, and insulin resistance as indicated by the homeostatic model assessment of insulin resistance (HOMA-IR) (all P<0.05). In multivariate linear regression analysis, BMI and HOMA-IR were independently and positively associated with plasma LBP levels.

Conclusion

LBP is an inflammatory biomarker associated with BMI and obesity-related insulin resistance in adolescents. The positive correlation between these parameters suggests a potentially relevant pathophysiological mechanism linking LBP to obesity-related insulin resistance in adolescents.

Non-invasive diagnostic approach to non-alcoholic fatty liver disease: current evidence and future perspectives

Non-alcoholic fatty liver disease is a new epidemic liver disease, thus, its early diagnosis and the identification of those patients with the worst prognosis is mandatory. Liver biopsy is still the diagnostic gold standard, even if it is associated to a significant rate of complications; moreover, the interpretation of histological samples is not always univocal. Several non-invasive alternative scores have been proposed for the diagnostic approach to non-alcoholic fatty liver disease. This article evaluates the performance of the currently available non-invasive diagnostic strategies. The authors also suggest a potential diagnostic algorithm, with two or more non-invasive techniques, to increase the overall accuracy for identifying patients with worst prognosis, and to minimize the recourse to liver biopsy.

Liver Bid suppression for treatment of fibrosis associated with non-alcoholic steatohepatitis

BACKGROUND & AIMS

Liver fibrosis is the most worrisome feature of non-alcoholic steatohepatitis (NASH). Growing evidence supports a link between hepatocyte apoptosis and liver fibrogenesis. Our aim was to determine the therapeutic efficacy and safety of liver Bid, a key pro-apoptotic molecule, suppression using RNA interference (RNAi) for the treatment of fibrosis.

METHODS

First, we optimized the delivery system for Bid siRNA in mice using ten different stealth RNAi siRNAs and two lipid formulations -Invivofectamine2.0 and a newly developed Invivofectamine3.0 - that have been designed for high efficacy accumulation in the liver, assessed via real-time PCR of Bid mRNA. Next, C57BL/6 mice were placed on a choline-deficient L-amino acid defined (CDAA) diet. After 19weeks of the CDAA diet, a time point that results in severe fibrotic NASH, mice were injected with the selected Bid siRNA-Invivofectamine3.0 biweekly for three weeks. Additionally hepatocyte-specific Bid deficient (Bid(Δhep)) mice were placed on CDAA diet for 20weeks.

RESULTS

A maximum Bid knockdown was achieved at 1.5mg/kg siRNA with Invivofectamine3.0, whereas it was at 7mg/kg with Invivofectamine2.0. In NASH mice, after 3weeks of treatment, BID protein was reduced to 10% and this was associated with an improvement in liver fibrosis and inflammation associated with a marked reduction in TUNEL positive cells, caspase 3 activation, and a reduction in mitochondrial BAX and BAK. Bid(Δhep) mice showed similar protection from fibrotic changes.

CONCLUSION

Our data demonstrate that liver Bid suppression by RNAi technology, as well as hepatocyte-specific Bid deficiency, improves liver fibrosis coupled with a reduction of inflammation in experimental NASH. These findings are consistent with existing evidence that hepatocyte apoptosis triggers hepatic stellate cell activation and liver fibrosis and suggest that Bid inhibition may be useful as an antifibrotic NASH therapy.

FibroGENE: A gene-based model for staging liver fibrosis

BACKGROUND & AIMS

The extent of liver fibrosis predicts long-term outcomes, and hence impacts management and therapy. We developed a non-invasive algorithm to stage fibrosis using non-parametric, machine learning methods designed for predictive modeling, and incorporated an invariant genetic marker of liver fibrosis risk.

METHODS

Of 4277 patients with chronic liver disease, 1992 with chronic hepatitis C (derivation cohort) were analyzed to develop the model, and subsequently validated in an independent cohort of 1242 patients. The model was assessed in cohorts with chronic hepatitis B (CHB) (n=555) and non-alcoholic fatty liver disease (NAFLD) (n=488). Model performance was compared to FIB-4 and APRI, and also to the NAFLD fibrosis score (NFS) and Forns' index, in those with NAFLD.

RESULTS

Significant fibrosis (⩾F2) was similar in the derivation (48.4%) and validation (47.4%) cohorts. The FibroGENE-DT yielded the area under the receiver operating characteristic curve (AUROCs) of 0.87, 0.85 and 0.804 for the prediction of fast fibrosis progression, cirrhosis and significant fibrosis risk, respectively, with comparable results in the validation cohort. The model performed well in NAFLD and CHB with AUROCs of 0.791, and 0.726, respectively. The negative predictive value to exclude cirrhosis was>0.96 in all three liver diseases. The AUROC of the FibroGENE-DT performed better than FIB-4, APRI, and NFS and Forns' index in most comparisons.

CONCLUSION

A non-invasive decision tree model can predict liver fibrosis risk and aid decision making.

Non-alcoholic fatty liver disease among sasang constitutional types: a population-based study in Korea

Background

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is highly prevalent in populations with metabolic conditions such as obesity and type II diabetes. Specific types of Sasang constitution can act as a risk factor for metabolic diseases, but there are no studies addressing the association between the Sasang constitutional types (SCTs) and NAFLD.

Methods

A total of 1184 individuals (508 males, 676 females) that enrolled in the Korean Genome and Epidemiology Study were included in the present study. Classification of SCTs was done with an integrated diagnostic model. NAFLD was diagnosed when the liver attenuation index (LAI) value was <5 Hounsfield units using computed tomography. Relationships between the SCTs and NAFLD were analyzed using multiple logistic regressions.

Results

The average LAI was 13.3 ± 6.0 in the So-eum (SE) type, 12.3 ± 7.0 in the So-yang (SY) type, and 6.5 ± 9.9 in the Tae-eum (TE) type. Prevalence of NAFLD was 4.7 % in the SE type, 14.0 % in the SY type, and 34 % in the TE type. Even after adjusting for possible confounders, the SY and TE types continued to show a 3.90-fold (95 % CI, 1.60-9.51; P = 0.0028) and 3.36-fold (95 % CI, 1.42-7.92; P = 0.0057) increase in chance of having NAFLD, respectively, compared with the SE type. In the additional analysis including only non-obese subjects, the odds ratio of NAFLD was 3.27 (95 % CI, 1.29-8.29; P = 0.0126) in the SY type and 3.53 (95 % CI, 1.30-9.58; P = 0.0134) in the TE type compared with SE type. In the multivariate analysis to determine which parameter had an independent association with NAFLD, higher body mass index, alanine aminotransferase (ALT), triglyceride (TG), and low high-density lipoprotein cholesterol were independently associated with developing NAFLD in the SY type. In contrast, male sex, alcohol consumption, higher ALT, TG, and fasting glucose were risk factors for NAFLD in the TE type.

Conclusions

These results indicated that the SY and TE types are independent risk factors for NAFLD.

Non-alcoholic fatty liver disease resolution following sleeve gastrectomy

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), a disease highly prevalent among the morbidly obese population, is one of the most common causes of chronic liver disease today. The purpose of this study was to observe the effect of laparoscopic sleeve gastrectomy (LSG) on the resolution of NAFLD.

METHODS

A retrospective study was conducted of 84 patients diagnosed with NAFLD prior to undergoing LSG. The diagnosis of NAFLD was achieved based on transabdominal ultrasonographic imaging as per the 2012 joint guidelines for the diagnosis of NAFLD (American Gastroenterological Association, American Association for the Study of Liver Diseases, and American College of Gastroenterology). The patients had follow-up anthropometric measurements and were re-evaluated with postoperative ultrasounds at different time frames to assess the resolution of the disease.

RESULTS

The median age of the patients was 44 (17-62), and 66.7 % were female. Average time since surgery was 3.3 years (range 1-5 years). The mean pre- and postoperative BMIs were 46.6 ± 7.8 and 33.0 ± 7.1, respectively, with a mean percent excess weight loss (%EWL) of 55.7 % ± 23.0. A total of 47 (56 %) patients showed complete resolution of NAFLD postoperatively. Multivariate analysis showed a significant resolution of NAFLD in patients achieving >50 % EWL (OR 10.1; p < 0.001) after controlling for age and sex.

CONCLUSIONS

Weight loss after LSG effectively resolved NAFLD in more than half of the obese patients in this study and can prove to be a useful tool in tackling the disease in the future.

Type 2 diabetes: a risk factor for liver mortality and complications in hepatitis B cirrhosis patients

BACKGROUND AND AIM

The effect of type 2 diabetes mellitus (DM) on morbidity and mortality among hepatitis B virus (HBV) cirrhosis patients is poorly defined. We assess the effect of DM on the HBV cirrhosis outcomes and survival.

METHODS

A retrospective study of HBV cirrhosis patients who sought care at a sole public hospital in a geographically defined region, from year 2000 to 2012. Cirrhosis complications, liver transplantations, and mortality were reviewed. Primary outcome is the composite of liver-related and overall mortality or orthotopic liver transplantation (OLT).

RESULTS

Two hundred twenty-three patients entered into the final analysis; 50 patients (22.4%) have DM at cirrhosis diagnosis. Seventy-two percent of DM patients have DM for more than 5 years at cirrhosis diagnosis. The incidence of hepatocellular carcinoma (HCC) was 25.4 and 60.5 per 1000 patient-years for non-DM and DM patients, respectively (P = 0.006). In multivariate analysis, DM was a predictor of HCC (hazard ratio [HR] 2.36, [1.14-4.85], P = 0.02), hepatic complications (HR 2.04, [1.16-3.59], P = 0.01), liver mortality or OLT (HR 2.26, [1.05-4.86], P = 0.04), and overall mortality or OLT (HR 2.25, [1.96-4.22], P = 0.01). Insulin and/or sulphonylurea use and poor diabetic control (glycosylated hemoglobin ≥ 7.0%) were predictors of HCC and cirrhosis complications (all P < 0.05). The 5-year liver-related mortality or OLT rate was 23.4% for DM patients and 9.4% for non-DM patients, respectively (P = 0.009).

CONCLUSION

The presence of DM and poor diabetic control at cirrhosis diagnosis significantly increase the rate of cirrhosis complications and reduced survival in patients with HBV cirrhosis. Improving diabetic control should be essential part of the cirrhosis care in these patients.

Associations of matrix metalloproteinase (MMP)-8, MMP-9, and their inhibitor, tissue inhibitor of metalloproteinase-1, with obesity-related biomarkers in apparently healthy adolescent boys

Purpose

Matrix metalloproteinases (MMPs) have been implicated in atherosclerosis, and therefore, are considered risk factors for metabolic dysfunction in adults. However, there is little data on circulating levels of MMPs and tissue inhibitors of MMPs (TIMPs) with regard to obesity-related biomarkers in the general adolescent population. In the present study, we determined the associations of MMP-8, MMP-9, and TIMP-1 levels and MMP-8/TIMP-1 and MMP-9/TIMP-1 ratios with obesity-related biomarkers in apparently healthy adolescent boys.

Methods

We measured MMP and TIMP concentrations in plasma samples using the enzyme-linked immunosorbent assay and analyzed their associations with obesity-related biomarkers, such as liver enzymes and lipid profiles, in a sample of 91 Korean boys aged 13-14 years who participated in a general health check-up.

Results

The mean age of the boys was 13.8±0.3 years; 72 boys were normal weight and 19 were overweight/obese. The Pearson correlation coefficients revealed a significant correlation between MMP-8 and aspartate aminotransferase (r=0.217, P=0.039) and alanine aminotransferase (r=0.250, P=0.017) and between TIMP-1 and aspartate aminotransferase (r=0.267, P=0.011). In a multivariate linear regression analysis, serum alanine aminotransferase was positively associated with the MMP-8 level. There were no significant differences in the MMP-8, MMP-9, and TIMP-1 levels or MMP-8/TIMP-1 and MMP-9/TIMP-1 ratios between control and overweight/obese subjects.

Conclusion

We found a significant association between the MMP-8 level and alanine aminotransferase in the apparently healthy adolescent boys. These findings indicate that there may be a pathophysiological mechanism underlying the relationship between MMP-8 and liver enzymes in young adolescents.

Clinical approaches to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), leading to fibrosis and potentially cirrhosis, and it is one of the most common causes of liver disease worldwide. NAFLD is associated with other medical conditions such as metabolic syndrome, obesity, cardiovascular disease and diabetes. NASH can only be diagnosed through liver biopsy, but noninvasive techniques have been developed to identify patients who are most likely to have NASH or fibrosis, reducing the need for liver biopsy and risk to patients. Disease progression varies between individuals and is linked to a number of risk factors. Mechanisms involved in the pathogenesis are associated with diet and lifestyle, influx of free fatty acids to the liver from adipose tissue due to insulin resistance, hepatic oxidative stress, cytokines production, reduced very low-density lipoprotein secretion and intestinal microbiome. Weight loss through improved diet and increased physical activity has been the cornerstone therapy of NAFLD. Recent therapies such as pioglitazone and vitamin E have been shown to be beneficial. Omega 3 polyunsaturated fatty acids and statins may offer additional benefits. Bariatric surgery should be considered in morbidly obese patients. More research is needed to assess the impact of these treatments on a long-term basis. The objective of this article is to briefly review the diagnosis, management and treatment of this disease in order to aid clinicians in managing these patients.

Clinical approaches to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), leading to fibrosis and potentially cirrhosis, and it is one of the most common causes of liver disease worldwide. NAFLD is associated with other medical conditions such as metabolic syndrome, obesity, cardiovascular disease and diabetes. NASH can only be diagnosed through liver biopsy, but noninvasive techniques have been developed to identify patients who are most likely to have NASH or fibrosis, reducing the need for liver biopsy and risk to patients. Disease progression varies between individuals and is linked to a number of risk factors. Mechanisms involved in the pathogenesis are associated with diet and lifestyle, influx of free fatty acids to the liver from adipose tissue due to insulin resistance, hepatic oxidative stress, cytokines production, reduced very low-density lipoprotein secretion and intestinal microbiome. Weight loss through improved diet and increased physical activity has been the cornerstone therapy of NAFLD. Recent therapies such as pioglitazone and vitamin E have been shown to be beneficial. Omega 3 polyunsaturated fatty acids and statins may offer additional benefits. Bariatric surgery should be considered in morbidly obese patients. More research is needed to assess the impact of these treatments on a long-term basis. The objective of this article is to briefly review the diagnosis, management and treatment of this disease in order to aid clinicians in managing these patients.

Obesity, nutrition, and liver disease in children

In this article, several aspects of childhood obesity are discussed, including epidemiology, associated metabolic complications, management strategies, and therapy with particular attention to the impact of obesity on the liver, resulting in nonalcoholic or metabolic fatty liver disease. The deleterious effects of obesity on the liver and health overall can be significantly impacted by a culture that fosters sustained nutritional improvement and regular physical activity. The current evidence is summarized supporting pharmacologic, behavioral, and dietary interventions for the management of obesity and fatty liver disease in children.

Obesity, an independent risk factor for hepatocellular carcinoma (HCC) in NAFLD non-cirrhotic patients

Hepatocellular carcinoma (HCC) is one of the most common malignancies with increasing incidence in developed countries. Epidemiological studies show that the cause of new discovered HCC cases remains unclear in 15%-50% of cases. Obesity and the subsequent/ underlying nonalcoholic fatty liver disease (NAFLD) can be responsible for most of these cases. The aim of our study was to estimate the risk of HCC in obese patients diagnosed with NAFLD, without clinical or imagistic features of liver cirrhosis, in order to see if HCC can develop in fatty liver in the absence of cirrhosis. Patients with regular/daily alcohol consumption or diagnosed with liver viral infections were excluded. We studied 214 obese patients with NAFLD over a period of 5 years. We evaluated all patients using abdominal ultrasound and serum alpha-fetoprotein every 6 month, in order to detect the HCC occurrence. Kaplan-Meier analysis estimated the cumulative incidence of HCC. Univariate and multivariate Cox regression analysis were used to assess associations between HCC and obesity. The median follow-up was 4.3 years. During the study period, 16 from 118 cirrhotic NFLAD patients (13.5%) and 12 from 96 non-cirrhotic NAFLD patients (12.5 %) developed HCC (p = 0.07, ns). The cumulative incidence of HCC was found to be 2.9% in obese patients with NAFLD-cirrhosis, compared with 2.2% in obese patients without cirrhosis (p = 0.09, ns). Multivariate regression analysis revealed that older age (p = 0.04) was independent variable associated with development of HCC in patients with/without NAFLDcirrhosis. Obesity seems to be an independent risk factor for HCC occurrence, regardless the presence of mild or advanced liver fibrosis in NAFLD patients.

Review article: the diagnosis of non-alcoholic fatty liver disease -- availability and accuracy of non-invasive methods

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) encompasses a wide spectrum of clinical conditions, actually representing an emerging disease of great clinical interest. Currently, its diagnosis requires liver biopsy, an invasive procedure not free from potential complications. However, several non-invasive diagnostic strategies have been proposed as potential diagnostic alternatives, each with different sensitivities and accuracies.

AIM

To review non-invasive diagnostic parameters and tools for NAFLD diagnosis and to formulate a diagnostic and prognostic algorithm for a better classification of patients.

METHODS

A literature search was carried out on MEDLINE, EMBASE, Web of Science and Scopus for articles and abstracts in English. The search terms used included 'NAFLD', 'non invasive method and NAFLD', 'transient elastography' and 'liver fibrosis'. The articles cited were selected based on their relevancy to the objective of the review.

RESULTS

Ultrasonography still represents the first-line diagnostic tool for simple liver steatosis; its sensitivity could be enhanced by the complex biochemical score SteatoTest. Serum cytokeratin-18 is a promising and accurate non-invasive parameter (AUROCs: 0.83; 0.91) for the diagnosis of non-alcoholic steatohepatitis (NASH). The staging of liver fibrosis still represents the most important prognostic problem: the most accurate estimating methods are FibroMeter, FIB-4, NAFLD fibrosis score (AUROCs: 0.94; 0.86; 0.82) and transient elastography (AUROC: 0.84-1.00).

CONCLUSIONS

Different non-invasive parameters are available for the accurate diagnosis and prognostic stratification of non-alcoholic fatty liver disease which, if employed in a sequential algorithm, may lead to a reduced use of invasive methods, i.e. liver biopsy.

Probucol ameliorates the development of nonalcoholic steatohepatitis in rats fed high-fat diets

AIMS

We sought to evaluate the effects of probucol on steatohepatitis and associated molecular mechanisms in a rat model of nonalcoholic steatohepatitis (NASH) induced by high-fat diet (HFD).

METHODS

Forty male rats weighing 100-120 g were randomly assigned to the following treatments (n = 10 for each treatment): standard diet + normal saline (NC group), standard diet + 500 mg/kg/day probucol (NP group), HFD + normal saline (HD group), and HFD + 500 mg/kg/day probucol (HP group). All animals received the above treatments for 15 weeks. Lipid metabolism and steatohepatitis were assessed. Systemic insulin resistance, oxidative stress status, serum tumor necrosis factor-alpha (TNF-α) and adiponectin levels, and gene expression were examined.

RESULTS

High-fat feeding resulted in macrovesicular steatosis, lobular inflammation, and hepatocellular ballooning degeneration in the liver, coupled with increased concentrations of serum aspartate aminotransferase and alanine aminotransferase. Probucol exposure attenuated the biochemical and histological changes comparable with NASH. Moreover, probucol treatment significantly prevented the elevations of serum total cholesterol, low-density lipoprotein, and high-density lipoprotein and the increase in the expression of numerous lipid metabolism-related genes in HFD-fed rats. There were increased insulin sensitivity and serum adiponectin levels and enhanced hepatic AMP-activated protein kinase phosphorylation in the HP group. Probucol lessened the HFD-induced elevation of serum TNF-α and hepatic malondialdehyde and reduced antioxidant enzymatic activities.

CONCLUSIONS

Probucol shows beneficial effects on HFD-induced steatohepatitis by improving insulin resistance and attenuating oxidative stress and systemic inflammation.

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.

Effect of metabolic syndrome on perioperative outcomes after liver surgery: A National Surgical Quality Improvement Program (NSQIP) analysis

BACKGROUND

The problem of obesity has risen to epidemic levels in the United States. A subset of patients with obesity will have metabolic syndrome. We sought to examine the impact of metabolic syndrome on the risk of morbidity and mortality among a large cohort of patients who underwent hepatic resection.

METHODS

Patients included in the National Surgical Quality Improvement Program (NSQIP) dataset who underwent hepatic resection between January 2005 and December 2008 were identified. Data on clinical characteristics, comorbidities, operative details, as well as postoperative complications and mortality were collected and analyzed. Patients with BMI >30 kg/m(2) who also had hypertension and diabetes were defined as having metabolic syndrome.

RESULTS

A total of 3,973 patients who underwent a liver resection were identified. Overall mean body mass index was 28 kg/m(2); 31.7% patients were obese (>30 kg/m(2)). Of the patients who were obese, 256 (20%) had metabolic syndrome. Patients with metabolic syndrome were less likely to have had a major hepatectomy (≥hemi-hepatectomy, 36% vs 43%; P = .01) but had a greater mean number of red blood cell transfusions (1.6 vs 1; P = .02). The incidence of postoperative complications after hepatectomy was 23%. Patients with metabolic syndrome had a greater risk for reintubation (odds ratio [OR] 1.9; P = .02), >48 hours ventilator dependence (OR 2.0; P = .003), myocardial infarction (OR 5.5; P = .01) and superficial surgical-site infections (OR 1.7; P = .02) compared with nonmetabolic patients. Overall postoperative mortality was 3%. Metabolic syndrome was associated with an increased risk of postoperative death (OR 2.7; P = .001).

CONCLUSION

The presence of metabolic syndrome was associated with a greater risk of perioperative complications. In addition, patients with metabolic syndrome had greater than a 2-fold increased risk of death after hepatic resection.

Identification of a support vector machine-based biomarker panel with high sensitivity and specificity for nonalcoholic steatohepatitis

BACKGROUND

Although liver biopsy remains the best diagnostic standard for nonalcoholic steatohepatitis (NASH), non-invasive tests are eagerly awaited. In this study, we sought to develop a support vector machine (SVM) algorithm to discriminate with high accuracy between subjects with NASH and controls using a blood-based biomarker panel.

METHODS

A total of 17 biomarkers were measured by commercially available enzyme-linked immunosorbent assays in 136 serum samples from patients with biopsy-proven NASH (n = 60) and subjects with normal ALT and no evidence of fatty liver on ultrasound (n = 76). The database was randomly divided (1:1 fashion) into a discovery set for classification training and in a validation set of the chosen biomarkers in blinded samples. Multivariate analysis was performed by means of SVM.

RESULTS

After the identification of a group of three most discriminative biomarkers (osteoprotegerin, fibroblast growth factor 21, and M30) in the discovery set, the application of SVM to the validation test resulted in a 92.5% sensitivity and 84.1% specificity for distinguishing subjects with NASH from controls.

CONCLUSIONS

A targeted biomarker profiling combined with a SVM-based pattern identification approach may allow the identification of patients with NASH with clinically relevant accuracy and validity.

Nonalcoholic fatty liver disease: a review of the spectrum of disease, diagnosis, and therapy

Worldwide, there is an epidemic of obesity and overweight, with two-thirds of Americans affected. A strong association exists between excessive body weight and nonalcoholic fatty liver disease (NAFLD), the most common etiology of abnormal liver function tests. Nonalcoholic fatty liver disease is a spectrum of liver disease, from a "bland" fatty infiltration to chronic hepatitis (nonalcoholic steatohepatitis or NASH), that can result in cirrhosis and organ failure. With the increasing prevalence of obesity in the world, the proportion of people affected by NAFLD is only expected to be parallel. Although primarily noted in obese individuals, NAFLD has also been associated with a number of surgical procedures, metabolic conditions, and medications. NASH is commonly underdiagnosed as most affected patients are symptom free, and routine screening is not performed. Noninvasive diagnostic testing is not sensitive in diagnosis or staging the severity of disease. Fatty infiltration and oxidative injury to the hepatocytes are believed to be the major factors behind the progression of disease from simple fatty infiltration of the liver to chronic hepatitis. Understanding the inflammatory pathways involved in NASH is a subject of extensive research. Currently, few proven treatment options exist, and controlled weight reduction is the only safe modality recommended for treatment of NASH.

Pediatric nonalcoholic fatty liver disease: a multidisciplinary approach

Nonalcoholic fatty liver disease (NAFLD) is a multifactorial condition, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with or without fibrosis. NAFLD affects both adults and children who present with particular risk factors, including obesity, sedentary lifestyle and/or a predisposing genetic background. The escalation of the prevalence of NAFLD in children worldwide is a worrying phenomenon because this disease is closely associated with the development of both cirrhosis and cardiometabolic syndrome in adulthood. The etiopathogenesis of primary NAFLD in children is unknown; however, considerable knowledge about the mechanisms of liver damage that occur during disease progression has been gathered over the past 30 years. Understanding the pathogenetic mechanisms, together with the histological pattern, provide the basis to characterize potential early predictors of the disease, suitable noninvasive diagnostic tools and design novel specific treatments and possible management strategies. Despite a few clinical trials on the use of antioxidants combined with lifestyle intervention for NAFLD that showed encouraging results, to date, no treatment guidelines exist for children with NAFLD. In this Review, we provide an overview of current concepts in epidemiology, histological features, etiopathogenesis, diagnosis and treatment of NAFLD in children and adolescents.

The metabolic syndrome in critically ill patients

Metabolic support in intensive care is a rapidly evolving field with new information being gathered almost on a daily basis. In endocrine practice, over the last 20 years, researchers have focussed on a new entity, termed the "metabolic syndrome". This describes the constellation of abnormalities which include central adiposity, insulin resistance and inflammation. All of these predispose the individual to a greater risk of cardiovascular events. Of interest is the observation that some of the metabolic abnormalities in sepsis and multiple organ dysfunction syndrome of critical illness share several common features with that of the metabolic syndrome. In this chapter we describe the features of the metabolic syndrome as is understood in endocrine parlance, the metabolic abnormalities of critical illness and explore the common threads underlying the pathophysiology and the treatment of the two syndromes. The role of adiponectin in the metabolic abnormalities in both the metabolic syndrome and in sepsis are reviewed. The potential role of the pleiotropic effects of statins in the therapy of sepsis is also discussed.

Association between the presence of brown adipose tissue and non-alcoholic fatty liver disease in adult humans

BACKGROUND

The presence of active brown adipose tissue (BAT) has been associated with a reduced risk of obesity in adult humans.

AIM

To examine whether the presence and activity of BAT in patients undergoing PET-CT examinations is related to the presence of fatty liver.

METHOD

We retrospectively analysed 3666 consecutive PET-CT whole-body scans performed on a total of 1832 patients who were referred for suspected malignancies. BAT-positive subjects (BAT+) were defined as subjects who showed substantial amounts of brown adipose tissue on PET-CT scans. In areas where uptake of [(18)F]FDG was identified by CT for BAT, the maximal standardised uptake values (SUVmax), defined as the maximum activity per millilitre within the region of interest divided by the injected dose in megabecquerels per gram of body weight, were determined. A ratio of mean liver attenuation to spleen attenuation <0.8 on CT scans was considered to indicate NAFLD.

RESULTS

Thirty patients of the 1832 screened individuals (2%) demonstrated brown fat uptake (BAT+ subjects). Ninety matched individuals without evidence of BAT on PET scans (BAT- subjects) were enrolled for comparison purposes. After adjustment for potential confounders, the odds ratio for having NAFLD was significantly higher for BAT- subjects (3.12, 95% confidence interval = 1.03-9.88, P < 0.05). The SUVmax for brown fat tissue was significantly correlated with the ratio of mean liver attenuation to spleen attenuation (P < 0.05).

CONCLUSION

The presence of brown adipose tissue in adulthood is independently associated with a lower likelihood of NAFLD diagnosed by CT findings.

Irbesartan improves endothelial dysfunction, abnormal lipid profile, proteinuria and liver dysfunction in Zucker diabetic fatty rats independent of glucose and insulin levels

Treatment with angiotensin type 1 receptor blockers (ARBs) is known to improve renal dysfunction and glucose metabolism in obese diabetic animal models and humans. This study examined the effects of irbesartan, a unique ARB with PPARγ activation, on endothelial dysfunction, renal dysfunction, abnormal lipid profile, and liver dysfunction in obese fa/fa Zucker diabetic fatty (ZDF) rats. ZDF rats were administered irbesartan (30 mg/kg/day p.o.) for 12 weeks. Blood pressure, glucose metabolism, lipid profile and renal function were measured every 4 weeks. Response of mesenteric artery rings to acetylcholine was also evaluated as an index of endothelial function after 12 weeks of treatment. Although irbesartan did not affect glucose and insulin levels in both glucose and insulin tolerance tests, decreases in systolic blood pressure, dyslipidemia, and urinary protein excretion were noted from 4 weeks after the start of treatment and continued until 12 weeks. Endothelial and liver dysfunctions were also improved after 12 weeks of treatment. Compared to previous reports showing the effects of irbesartan at later time points such as 6 or 12 months, the present study demonstrated that a low-dose of irbesartan had favorable effects from the early period of treatment, independent of glucose metabolism. Our findings suggest that a low-dose of irbesartan improves diabetic complications quickly after starting treatment, and may support the use of irbesartan for preventing progression of diabetic complications.

The cytoskeleton in nonalcoholic steatohepatitis: 100 years old but still youthful

The hepatocellular cytoskeleton consists of three filamentous systems: microfilaments, microtubules and keratins (Ks). While the alterations in microfilaments and microtubules during nonalcoholic steatohepatitis (NASH) are largely unexplored, K8/K18 reorganization into Mallory-Denk bodies (MDBs) represents a NASH hallmark, and serological K18 fragments constitute an established tool to monitor NASH severity. To commemorate the 100th anniversary of the first description of MDBs, this article summarizes the composition and function of the hepatocellular cytoskeleton, as well as the importance of cytoskeletal alterations in NASH. The significance of MDBs in clinical routine is illustrated, as are the findings from MDB mouse models, which shape our current view of MDB pathogenesis. Even after 100 years, the cytoskeleton represents a fascinating but greatly understudied area of NASH biology.