Prevalence of non-alcoholic fatty liver and characteristics in overweight adolescents in the general population

Association of PAF and its metabolic enzymes with GGT and the Fatty Liver Index in healthy volunteers

BACKGROUND

Platelet-activating factor (PAF) is a lipid inflammatory mediator implicated in liver disease. Its main biosynthetic enzymes are cytidine diphosphate (CDP)-choline:1-alkyl-2-acetyl-sn-glycerol-cholinephosphotransferase (PAF-CPT) and acetyl-coenzyme A: lyso-PAF-acetyltransferases (Lyso-PAF-AT), while PAF acetylhydrolase (PAF-AH) and lipoprotein-associated phospholipase A2 (Lp-PLA2) degrade PAF.

OBJECTIVE

To explore the relation of PAF metabolism with liver diseases and non-alcoholic fatty liver disease, as reflected by the fatty liver index (FLI).

METHODS

In 106 healthy volunteers, PAF concentration, the activity of its metabolic enzymes, and gamma-glutamyl transferase (GGT) were measured in whole blood, leukocytes, and serum, respectively, and the FLI was calculated. Partial correlations and linear regression models were used.

RESULTS

In males, serum GGT activity was positively correlated with abdominal fat (as assessed by analysis of a manually defined region of interest in dual-energy X-ray absorptiometry), triacylglycerols, bound-PAF, and Lp-PLA2, while the FLI was positively correlated with Lp-PLA2 activity. In females, serum GGT activity was negatively associated with high-density lipoprotein cholesterol (HDL-C) (age-adjusted correlations, all p<0.05). Lp-PLA2 was a significant determinant of serum GGT activity in males after controlling for age, low-density lipoprotein cholesterol (LDL-C), and abdominal fat. The addition of bound-PAF in the model significantly increased the explained variance of serum GGT activity (total variance explanation 30%).

CONCLUSION

Bound-PAF and Lp-PLA2 activity predicted serum GGT activity, while Lp-PLA2 was also related to FLI. Our findings shed light on the metabolic pathways linking Lp-PLA2 to other atherosclerosis and/or oxidative markers, such as HDL-C, LDL-C, GGT, and FLI, and underline the important role of PAF.

Epidemiology of nonalcoholic fatty liver disease in Europe: a systematic review and meta-analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the developed countries. The aim of this study was to evaluate the NAFLD prevalence in European adults and children/adolescents of the general population and specific subgroups.

METHOD

Search for all articles published between 01/1990-06/2019 reporting NAFLD prevalence from European countries.

RESULTS

Nineteen studies with adults and 9 with children/adolescents were included. Pooled NAFLD prevalence in adults was 26.9%, being higher in studies using ultrasonography (27.2%) or fatty liver index (FLI) (30.1%) than liver biochemical tests (19.1%) and without differences between Mediterranean and non-Mediterranean countries or publication periods. Pooled NAFLD prevalence was higher in men than women (32.8% vs. 19.6%) and in patients with than those without metabolic syndrome (75.3% vs. 17.9%) or any of its components (always P<0.01). Ultrasound and FLI performed equally in estimating NAFLD prevalence in most subgroups. A higher prevalence was reported using FLI in obese and in diabetic patients, whereas a higher prevalence was observed with ultrasound in non-obese patients and in individuals without metabolic syndrome. NAFLD prevalence was 2.7% in unselected and 31.6% in obese/overweight children/adolescents.

CONCLUSIONS

NAFLD prevalence exceeds 25% in European adults, being higher in those with metabolic syndrome component(s)-related comorbidities. It remains low in unselected NAFLD population, but increased in overweight/obese European children/adolescents, particularly from Mediterranean countries.

Sex-Specific Metabolite Biomarkers of NAFLD in Youth: A Prospective Study in the EPOCH Cohort

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in developed nations. There are currently no accurate biomarkers of NAFLD risk in youth.

OBJECTIVE

Identify sex-specific metabolomics biomarkers of NAFLD in a healthy cohort of youth.

DESIGN/SETTING

This prospective study included 395 participants of the EPOCH cohort in Colorado, who were recruited 2006-2009 ("T1 visit") and followed for 5 years ("T2 visit"). We entered 767 metabolites measured at T1 into a reduced rank regression model to identify the strongest determinants of hepatic fat fraction (HFF) at T2, separately for boys and girls. We compared the capacity of metabolites versus conventional risk factors (overweight/obesity, insulin, alanine transaminase, aspartate transaminase) to predict NAFLD (HFF ≥5%) and high HFF (fourth vs first quartile) using area under the receiver operating characteristic curve (AUC).

RESULTS

Prevalence of NAFLD was 7.9% (8.5% of boys, 7.1% of girls). Mean ± SD HFF was 2.5 ± 3.1%. We identified 13 metabolites in girls and 10 metabolites in boys. Metabolites were in lipid, amino acid, and carbohydrate metabolism pathways. At T1, the metabolites outperformed conventional risk factors in prediction of high HFF but not NAFLD. At T2, the metabolites were superior to conventional risk factors as predictors of high HFF (AUC for metabolites vs conventional risk factors for boys: 0.9565 vs 0.8851, P = 0.02; for girls: 0.9450 vs 0.8469, P = 0.02) with similar trends for NAFLD, although the differences were not significant.

CONCLUSIONS

The metabolite profiles identified herein are superior predictors of high HFF when assessed 5 years prior and concurrently in a general-risk setting.

Non-alcoholic fatty liver infiltration in children: an underdiagnosed evolving disease

Non-alcoholic fatty liver disease (NAFLD) constitutes the most common liver disease, one that is still underdiagnosed in pediatric populations (as well as in the general population), this due to the progressive increase in childhood obesity observed both in developed and developing countries during the last few decades. The pathophysiology of the disease has not been thoroughly clarified yet. The condition displays common pathways in adults and children; however, there are age-related differences. Unlike adults, children with NAFLD require extensive laboratory analysis, because underlying pathologies other than obesity may contribute to the evolution of the disease. Despite the presence of several serum markers and imaging techniques that contribute to NAFLD diagnosis, liver biopsy remains the gold standard diagnostic procedure. Early intervention and obesity prevention are mandatory, as NAFLD is reversible at an early stage. If left undiagnosed and untreated, NAFLD can progress to steatohepatitis (NASH) and subsequent liver failure, a potentially lethal complication. Of note, there are no treatment options when advanced liver fibrosis occurs. This review summarizes literature data on NAFLD in childhood indicating that this is an evolving disease and a significant component of the metabolic syndrome. Pediatricians should be aware of this entity, screening children at high risk and providing appropriate early management, in collaboration with pediatric subspecialists.

The influence of hepatic steatosis on the evaluation of fibrosis with non-alcoholic fatty liver disease by acoustic radiation force impulse

Acoustic radiation force impulse (ARFI) elastography is a non-invasive method for the assessment of liver by measuring liver stiffness. The aim of this study is to evaluate the accuracy of ARFI for the diagnosis of liver fibrosis and to assess impact of steatosis on liver fibrosis stiffness measurement, in rats model of non-alcoholic fatty liver disease (NAFLD). The rat models were conducted in 59 rats. The right liver lobe was processed and embedded in a fabricated gelatin solution. Liver mechanics were measured using shear wave velocity (SWV) induced by acoustic radiation force. In rats with NAFLD, the diagnostic performance of ARFI elastography in predicting severe fibrosis (F ≥ 3) and cirrhosis (F ≥ 4) had the areas under the receiver operating characteristic curves (AUROC) of 0.993 and 0.985. Among rats mean SWV values were significantly higher in rats with severe steatosis by histology compared to those mild or without steatosis for F0-F2 fibrosis stages (3.07 versus 2.51 m/s, P = 0.01). ARFI elastography is a promising method for staging hepatic fibrosis with NAFLD in rat models. The presence of severe steatosis is a significant factor for assessing the lower stage of fibrosis.

Role of acoustic radiation force impulse imaging elastography in the assessment of steatohepatitis and fibrosis in rat models

Acoustic radiation force impulse (ARFI) elastography is a non-invasive method for performing liver assessment via liver shear wave velocity (SWV) measurements. The aim of this study was to evaluate the performance of the ARFI technique in the diagnosis of nonalcoholic steatohepatitis (NASH) and fibrosis and to investigate the effect of steatosis and inflammation on liver fibrosis SWV measurements in a rat model of nonalcoholic fatty liver disease (NAFLD). The ex vivo right liver lobes from 110 rats were processed and embedded in a fabricated gelatin phantom, and the other lobes were used for histologic assessment. The SWV induced by acoustic radiation force was derived to evaluate liver stiffness. The experimental results showed that the liver SWV value could be used to differentiate non-NASH rats from NASH-presenting rats and NASH from cirrhosis, and these comparisons showed areas under the receiver operating characteristic curves (AUROC) of 0.951 and 0.980, respectively. The diagnostic performances of ARFI elastography in predicting severe fibrosis (F ≥ 3) and cirrhosis (F ≥ 4) showed AUROC values of 0.997 and 0.993, respectively. In rats with mild fibrosis (F0-F1), severe steatosis had a significant effect on the mean SWV values. In rats with significant fibrosis (F2-F4), severe lobular inflammation had significant effects on the mean SWV values. Our findings indicate that ARFI elastography is a promising method for differentiating non-NASH rats from NASH rats and for staging hepatic fibrosis in NASH. The presence of severe steatosis and severe lobular inflammation are significant factors for evaluating fibrosis stages.

Gamma-glutamyltransferase, fatty liver index and hepatic insulin resistance are associated with incident hypertension in two longitudinal studies

OBJECTIVE

We hypothesized that liver markers and the fatty liver index (FLI) are predictive of incident hypertension and that hepatic insulin resistance plays a role.

METHODS

The association between liver markers and incident hypertension was analysed in two longitudinal studies of normotensive individuals, 2565 from the 9-year data from an epidemiological study on the insulin resistance cohort and the 321 from the 3-year 'Relationship between Insulin Sensitivity and Cardiovascular disease' cohort who had a measure of endogenous glucose production. The FLI is calculated from BMI, waist circumference, triglycerides and gamma-glutamyltransferase (GGT) and the hepatic insulin resistance index from endogenous glucose production and fasting insulin.

RESULTS

The incidence of hypertension increased across the quartiles groups of both baseline GGT and alanine aminotransferase. After adjustment for sex, age, waist circumference, fasting glucose, smoking and alcohol intake, only GGT was significantly related with incident hypertension [standardized odds ratio: 1.21; 95% confidence interval (1.10-1.34); P = 0.0001]. The change in GGT levels over the follow-up was also related with an increased risk of hypertension, independently of changes in body weight. FLI analysed as a continuous value, or FLI at least 60 at baseline were predictive of incident hypertension in the multivariable model. In the RISC cohort, the hepatic insulin resistance index was positively related with the risk of 3-year incident hypertension [standardized odds ratio: 1.54 (1.07-2.22); P = 0.02].

CONCLUSION

Baseline GGT and FLI, as well as an increase in GGT over time, were associated with the risk of incident hypertension. Enhanced hepatic insulin resistance predicted the onset of hypertension and may be a link between liver markers and hypertension.

Increased prevalence and risk of non-alcoholic fatty liver disease in overweight and obese patients with Type 2 diabetes in South China

AIMS

To investigate the prevalence of and risk factors for non-alcoholic fatty liver disease in overweight and obese patients with Type 2 diabetes mellitus.

METHODS

We recruited patients with Type 2 diabetes with a BMI ≥ 24 kg/m² , who visited the diabetes clinics of 60 hospitals in 21 cities in Guangdong Province, China from August 2011 to March 2012. Anthropometric measurements, biochemical tests and abdominal ultrasonography were performed for all the patients.

RESULTS

The study included 3861 patients (1860 men) with a mean ± sd (range) age of 58.91 ± 13.06 (18-90) years. Non-alcoholic fatty liver disease was found in 1751 patients (45.4%), with a significantly higher prevalence among men than women (48.0 vs 42.9%). The peak of non-alcoholic fatty liver disease prevalence was in patients with a BMI of 34-35 kg/m² , those with a triglyceride/HDL cholesterol ratio of 5.5-6.0, men aged < 30 years and women aged 40-50 years. Assessment using the BARD (BMI, aspartate aminotransferase/alanine aminotransferase ratio, diabetes) score system showed that the prevalence of advanced fibrosis was 80.52% in all patients and that women had a higher prevalence than men (86.52 vs 74.16%). Multiple logistic regression analyses showed that dyslipidaemia, BMI and 2-h postprandial plasma glucose were independent risk factors for non-alcoholic fatty liver disease, while heart rate and female gender were protective factors.

CONCLUSION

The prevalence of non-alcoholic fatty liver disease in overweight and obese patients with Type 2 diabetes in South China is high. Multiple metabolic disorders were significantly associated with non-alcoholic fatty liver disease in overweight and obese patients with Type 2 diabetes.

Ex vivo study of acoustic radiation force impulse imaging elastography for evaluation of rat liver with steatosis

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in developed countries. Accurate, noninvasive tests for diagnosing NAFLD are urgently needed. The goals of this study were to evaluate the utility of acoustic radiation force impulse (ARFI) elastography for determining the severity grade of steatosis in rat livers, and to investigate the changes in various histologic and biochemical characteristics. Steatosis was induced in the livers of 57 rats by gavage feeding of a high fat emulsion; 12 rats received a standard diet only and served as controls. Liver mechanics were measured ex vivo using shear wave velocity (SWV) induced by acoustic radiation force. The measured mean values of liver SWV ranged from 1.33 to 3.85m/s for different grades of steatosis. The area under the receiver operative characteristic curve (⩾S1) was equal to 0.82 (95% CI=0.69, 0.96) between the steatosis group and the normal group, and the optimal cutoff value was 2.59 with sensitivity of 88% and specificity of 76%. However, there are no significant differences in SWV measurements between the steatosis grades. SWV values did not correlate with the early grade of inflammation. In conclusion, ARFI elastography is a promising method for differentiating normal rat liver from rat liver with steatosis, but it cannot reliably predict the grade of steatosis in rat livers. The early grade of inflammation activity did not significantly affect the SWV measurements.

The epidemiology of non-alcoholic fatty liver disease

The increase in Non-alcoholic Fatty Liver Disease (NAFLD) and the imminent disappearance of chronic viral hepatitis thanks to new and effective therapies is motivating hepatologists to change their clinical approach to chronic liver disease. NAFLD-cirrhosis or NAFLD-Hepatocellular Carcinoma (HCC) are now the second cause of liver transplantation in the USA. This short-review is focused to the epidemiology of NAFLD/Non-alchoholic Steatohepatitis (NASH), including the definition of this disease which should be revised as well discussing the prevalence, risk factors for progression, natural history and mortality. NAFLD is considered to be the hepatic manifestation of the metabolic syndrome (MS). It affects 25-30% of the general population and the risk factors are almost identical to those of MS. The natural history involves either the development of cardiovascular diseases or cirrhosis and HCC. HCC can also develop in NASH in the absence of cirrhosis (45% of cases). We conclude that an international consensus conference on the definition, natural history, policies of surveillance and new pharmacological treatments of NAFLD and NASH is urgently needed.

Accuracy of Liver Fat Quantification With Advanced CT, MRI, and Ultrasound Techniques: Prospective Comparison With MR Spectroscopy

OBJECTIVE

The purpose of this study was to prospectively evaluate the accuracy of proton-density fat-fraction, single- and dual-energy CT (SECT and DECT), gray-scale ultrasound (US), and US shear-wave elastography (US-SWE) in the quantification of hepatic steatosis with MR spectroscopy (MRS) as the reference standard.

SUBJECTS AND METHODS

Fifty adults who did not have symptoms (23 men, 27 women; mean age, 57 ± 5 years; body mass index, 27 ± 5) underwent liver imaging with un-enhanced SECT, DECT, gray-scale US, US-SWE, proton-density fat-fraction MRI, and MRS for this prospective trial. MRS voxels for the reference standard were colocalized with all other modalities under investigation. For SECT (120 kVp), attenuation values were recorded. For rapid-switching DECT (80/140 kVp), monochromatic images (70-140 keV) and fat density-derived material decomposition images were reconstructed. For proton-density fat fraction MRI, a quantitative chemical shift-encoded method was used. For US, echogenicity was evaluated on a qualitative 0-3 scale. Quantitative US shear-wave velocities were also recorded. Data were analyzed by linear regression for each technique compared with MRS.

RESULTS

There was excellent correlation between MRS and both proton-density fat-fraction MRI (r² = 0.992; slope, 0.974; intercept, -0.943) and SECT (r² = 0.856; slope, -0.559; intercept, 35.418). DECT fat attenuation had moderate correlation with MRS measurements (r² = 0.423; slope, 0.034; intercept, 8.459). There was good correlation between qualitative US echogenicity and MRS measurements with a weighted kappa value of 0.82. US-SWE velocity did not have reliable correlation with MRS measurements (r² = 0.004; slope, 0.069; intercept, 6.168).

CONCLUSION

Quantitative MRI proton-density fat fraction and SECT fat attenuation have excellent linear correlation with MRS measurements and can serve as accurate noninvasive biomarkers for quantifying steatosis. Material decomposition with DECT does not improve the accuracy of fat quantification over conventional SECT attenuation. US-SWE has poor accuracy for liver fat quantification.

Liver sinusoidal endothelial cells (LSECs) function and NAFLD; NO-based therapy targeted to the liver

Liver sinusoidal endothelial cells (LSECs) present unique, highly specialised endothelial cells in the body. Unlike the structure and function of typical, vascular endothelial cells, LSECs are comprised of fenestrations, display high endocytic capacity and play a prominent role in maintaining overall liver homeostasis. LSEC dysfunction has been regarded as a key event in multiple liver disorders; however, its role and diagnostic, prognostic and therapeutic significance in nonalcoholic fatty liver disease (NAFLD) is still neglected. The purpose of this review is to provide an overview of the importance of LSECs in NAFLD. Attention is focused on the LSECs-mediated NO-dependent mechanisms in NAFLD development. We briefly describe the unique, highly specialised phenotype of LSECs and consequences of LSEC dysfunction on function of hepatic stellate cells (HSC) and hepatocytes. The potential efficacy of liver selective NO donors against liver steatosis and novel treatment approaches to modulate LSECs-driven liver pathology including NAFLD are also highlighted.

Comparison between a pediatric health promotion center and a pediatric obesity clinic in detecting metabolic syndrome and non-alcoholic fatty liver disease in children

This study was done to evaluate the efficacy of health check-ups in children in detecting metabolic syndrome and non-alcoholic fatty liver disease (NAFLD) by comparing the pediatric health promotion center with the pediatric obesity clinic. Children who visited a pediatric health promotion center (n=218) or a pediatric obesity clinic (n=178) were included. Anthropometric data, blood pressure, laboratory tests, and abdominal ultrasonography were evaluated. Two different criteria were applied to diagnose metabolic syndrome. The prevalence of metabolic syndrome in the 2 units was 3.2%-3.7% in a pediatric health promotion center and 23%-33.2% in a pediatric obesity clinic. Significant differences were observed in the prevalence of each component of metabolic syndrome between the 2 units including abdominal adiposity, blood pressure, serum triglycerides, and fasting blood glucose (P<0.05). The prevalence of NAFLD was 8.7% and 71.9% in the 2 units according to liver enzymes and 5.9% and 61.8% according to ultrasonography (P<0.05). The prevalence of metabolic syndrome and NAFLD was higher among patients visiting the obesity clinic targeting obese children than that among patients visiting the health promotion center offering routine check-ups. An obesity-oriented approach is required to prevent obesity-related health problems in children.

Improvement in nonalcoholic fatty liver disease and metabolic syndrome in adolescents undergoing bariatric surgery

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children. It is linked to obesity and the metabolic syndrome (MS), predisposing to future cirrhosis. The objective of this study was to demonstrate the effects that weight loss achieved with laparoscopic adjustable gastric band (LAGB) has on the metabolic parameters and NAFLD scores of obese adolescents with evidence of fatty liver disease.

METHODS

Adolescents undergoing LAGB were evaluated for NAFLD with evidence of fatty liver on preoperative sonogram, serum biochemistry, or both between 2005 and 2011. Primary endpoint was change in NAFLD scores after LAGB and secondary endpoint change in MS criteria.

RESULTS

Fifty-six out of 155 adolescents had evidence of fatty liver disease at presentation. The group consisted of 17 (30%) male and 39 (70%) females, mean age 16.1 years (range 14-17.8 yr). Preoperative body mass index (BMI) was 48.8 kg/m(2) (±7) dropping to 37.9 kg/m(2) (±8.3) at 12 months and 36.8 kg/m(2) (±8.2) at 24 months. Fifteen (27%) patients met the criteria for MS. When comparing 1-year postsurgery to presurgery, the NAFLD score decreased by an average of .68 (SD = 1.03, P<.01). The 2-year NAFLD score decreased by a mean of .38 (SD = .99, P = .01). The reoperation rate for band/port related complications was 10.7% at 2 years with no mortality. MS rates improved from 27% to 2% at 2 years (P< .01).

CONCLUSIONS

LAGB is a safe and effective operation for obese adolescents with NAFLD. There was significant improvement in NAFLD scores and resolution of MS.

Vitamin D levels and liver histological alterations in children with nonalcoholic fatty liver disease

OBJECTIVE

To investigate the association between plasma vitamin D (VD) levels and histological liver damage in children with nonalcoholic fatty liver disease (NAFLD).

SUBJECTS AND METHODS

In this cross-sectional study, carried out in a tertiary care center for obesity, 73 consecutive overweight and obese children with persistently elevated serum aminotransferase levels and diffusely hyperechogenic liver on ultrasonography were selected for liver biopsy. Nonalcoholic steatohepatitis (NASH) and fibrosis were histologically diagnosed using NAFLD Clinical Research Network (CRN) criteria. The plasma levels of 25-OH-VD were measured by HPLC. Bone mineral density (BMD) of lumbar spine was evaluated by dual-energy X-ray absorptiometry. Multiple linear regression analysis was used to evaluate the association between 25-OH-VD levels and the predictors of interest after correction for age, gender, waist circumference, BMI, and other potential confounders.

RESULTS

The children (64% males) were aged 8-18 years, and their median BMI was 2.45 SDS. Both parathyroid hormone levels and BMD were within the normal range. All cases of fibrosis were detected in children with NASH. On multivariable linear regression with correction for age, gender, and BMI, 25-OH-VD levels were found to be 9 (95% CI 12-6) ng/ml lower in children with NASH than in those without NASH (P<0.001) and 9 (12-6) ng/ml lower in children with stage 1 fibrosis than in those with stage 0 fibrosis and 9 (13-6) ng/ml lower in children with stage 2 than in those with stage 0 fibrosis (P<0.001 for both).

CONCLUSION

VD levels are inversely associated with NASH and fibrosis in children with NAFLD.

Nonalcoholic fatty liver disease and type 2 diabetes in obese children

Nonalcoholic fatty liver disease (NAFLD) is commonly found in adults and adolescents with type 2 diabetes (T2DM). The cause-effect relations of these 2 conditions are complex and it is difficult to decipher whether one drives the other or vice versa. Genetic predispositions, along with obesity, are probably shared culprits of both. NAFLD may precede the diagnosis of diabetes and play a critical role of driving its development by way of increasing hepatic and whole body insulin resistance. On the other hand, T2DM is associated with hyperinsulinemia, a resistance to some of the effects of gut derived peptides and increased systemic free fatty acids, that can all promote hepatic lipid deposition. Thus, each condition may promote the development of the other and their mutual presence creates a vicious cycle. Upon studying this complex interplay from another angle, reduction of liver fat significantly improves glucose metabolism in patients with T2DM highlighting the tight pathophysiological link between them.

Epidemiological survey and risk factor analysis of fatty liver disease of adult residents, Beijing, China

BACKGROUND AND AIM

With the changes in diet structure and lifestyle, the incidence of fatty liver disease is increasing in China, especially in cities. The goal of the present study was to accurately determine the prevalence and risk factors of fatty liver disease in Beijing residents, China.

METHODS

By using random multistage stratification and cluster sampling, residents aged > 20 years in Dongcheng District and Tongzhou District were recruited, and questionnaire survey, physical examination, detection of fasting glucose, blood lipids and liver biochemistry, and ultrasonography of the liver, gallbladder, and spleen were carried out. Database EpiData 3.0 was employed for data input, followed by statistical analysis with SPSS version 11.0.

RESULTS

A total of 3762 residents were included in the present study including 2328 males and 1434 females with a mean age of 46.37 ± 14.28 years (range 20-92 years). Ultrasonography revealed fatty liver in 1486 residents with a prevalence of 39.5%. Moreover, non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease were found in 1177 (31.3%) and 309 (8.2%) residents, respectively. After adjustment of prevalence based on the age and gender constituents of Beijing residents, the standardized prevalence of overall fatty liver disease, NAFLD, and alcoholic fatty liver disease was 35.1%, 31.0%, and 4.1%, respectively. Binary logistic regression analysis revealed waist-to-hip ratio, diastolic pressure, fasting blood glucose, triglyceride, high-density lipoprotein cholesterol, and low density lipoprotein cholesterol were closely related to NAFLD.

CONCLUSIONS

The Beijing residents have a high prevalence of fatty liver disease as much as 35.1%, which is characterized by NAFLD. Obesity, and glucose and lipid metabolism disorders are the main risk factors of fatty liver disease.

The burden of liver disease in Europe: a review of available epidemiological data

To survey the burden of liver disease in Europe and its causes 260 epidemiological studies published in the last five years were reviewed. The incidence and prevalence of cirrhosis and primary liver cancer are key to understand the burden of liver disease. They represent the end-stage of liver pathology and thus are indicative of the associated mortality. About 0.1% of Hungarian males will die of cirrhosis every year compared with 0.001% of Greek females. WHO estimate that liver cancer is responsible for around 47,000 deaths per year in the EU. Harmful alcohol consumption, viral hepatitis B and C and metabolic syndromes related to overweight and obesity are the leading causes of cirrhosis and primary liver cancer in Europe. Chronic hepatitis B affects 0.5-0.7% of the European population. In the last decade the prevalence of chronic hepatitis C was 0.13-3.26%. It is of great concern that about 90% of people in Europe infected by viral hepatitis are unaware of their status. Available data suggest the prevalence rate of NAFLD is 2-44% in the general European population (including obese children) and 42.6-69.5% in people with type 2 diabetes. Each of these four major causes of liver disease is amenable to prevention and treatment, reducing the burden of liver disease in Europe and saving lives. Further surveys are urgently needed to implement cost-effective prevention programmes and novel treatments to tackle this problem.

Association between liver-specific gene polymorphisms and their expression levels with nonalcoholic fatty liver disease

Genetic factors account for a significant proportion of the phenotypic variance of nonalcoholic fatty liver disease (NAFLD); however, very few predisposing genes have been identified. We aimed to (1) identify novel genetic associations with NAFLD by performing a genome-wide association study (GWAS), and (2) examine the biological expression of the strongest genetic associations in a separate cohort. We performed GWAS of a population-based cohort (Raine Study) of 928 adolescents assessed for NAFLD by ultrasound at age 17. Expression of genes with single nucleotide polymorphisms (SNPs) that were associated with NAFLD at a significance level of P < 10(-5) was examined in adults with NAFLD and controls by quantifying hepatic messenger RNA (mRNA) expression and serum levels of protein. After adjustment for sex and degree of adiposity, SNPs in two genes expressed in liver were associated with NAFLD adolescents: group-specific component (GC) (odds ratio [OR], 2.54; P = 1.20 × 10(-6)) and lymphocyte cytosolic protein-1 (LCP1) (OR, 3.29; P = 2.96 × 10(-6)). SNPs in two genes expressed in neurons were also associated with NAFLD: lipid phosphate phosphatase-related protein type 4 (LPPR4) (OR, 2.30; P = 4.82 × 10(-6)) and solute carrier family 38 member 8 (SLC38A8) (OR, 3.14; P = 1.86 × 10(-6) ). Hepatic GC mRNA was significantly reduced (by 83%) and LCP1 mRNA was increased (by 300%) in liver biopsy samples from patients with NAFLD compared to controls (P < 0.05). Mean serum levels of GC protein were significantly lower in patients with NAFLD than controls (250 ± 90 versus 298 ± 90, respectively; P = 0.004); GC protein levels decreased with increasing severity of hepatic steatosis (P < 0.01).

CONCLUSION

The association between GC and LCP1 SNPs and NAFLD as well as altered biological expression implicate these genes in the pathogenesis of NAFLD.

SIRT1 attenuates palmitate-induced endoplasmic reticulum stress and insulin resistance in HepG2 cells via induction of oxygen-regulated protein 150

Endoplasmic reticulum (ER) stress has been implicated in the pathology of type 2 diabetes mellitus (T2DM). Although SIRT1 has a therapeutic effect on T2DM, the mechanisms by which SIRT1 ameliorates insulin resistance (IR) remain unclear. In this study, we investigated the impact of SIRT1 on palmitate-induced ER stress in HepG2 cells and its underlying signal pathway. Treatment with resveratrol, a SIRT1 activator significantly inhibited palmitate-induced ER stress, leading to the protection against palmitate-induced ER stress and insulin resistance. Resveratrol and SIRT1 overexpression induced the expression of oxygen-regulated protein (ORP) 150 in HepG2 cells. Forkhead box O1 (FOXO1) was involved in the regulation of ORP150 expression because suppression of FOXO1 inhibited the induction of ORP150 by SIRT1. Our results indicate a novel mechanism by which SIRT1 regulates ER stress by overexpression of ORP150, and suggest that SIRT1 ameliorates palmitate-induced insulin resistance in HepG2 cells via regulation of ER stress.

Differences in triglyceride and cholesterol metabolism and resistance to obesity in male and female vitamin D receptor knockout mice

A lean phenotype has been detected in vitamin D receptor (VDR) knockout mice; however, the gender differences in fat metabolism between male and female mice both with age and in response to a high-fat diet have not been studied before. The objective of our study was to assess changes in body and fat tissue weight, food intake and serum cholesterol and triglyceride in VDR knockout mice from weaning to adulthood and after a challenge of adult animals with a high-fat diet. Although VDR knockout mice of both sexes consumed more food than wild-type and heterozygous littermates, their body weight and the weight of fat depots was lower after 6 months on a diet with 5% crude fat content. When adult animals were challenged with a high-fat diet containing 21% crude fat content for 8 weeks, VDR knockout mice of both sexes had a significantly higher food intake but gained less weight than their wild-type littermates. Cholesterol levels were higher after 2 days on the high-fat diet in both sexes, but in the VDR knockout mice, less cholesterol was detected in the serum after 8 weeks. Wild-type male mice showed signs of fatty liver disease at the end of the experiment, which was not detected in the other groups. In conclusion, lack of the VDR receptor results in reduced fat accumulation with age and when adult mice are fed a high-fat diet, despite a higher food intake of VDR knockout mice relative to their wild-type littermates. These effects can be detected in both sexes. Wild-type male mice react with the highest weight gain and cholesterol levels of all groups and develop fatty liver disease after 8 weeks on a high-fat diet, while male VDR knockout mice appear to be protected.

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 effects of diet-induced obesity on hepatocyte insulin signaling pathways and induction of non-alcoholic liver damage

The prevalence of diet-induced obesity is increasing amongst adults and children worldwide, predisposing millions of people to an array of health problems that include metabolic syndrome, non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. In this study we used experimental animals to investigate the effects of dietary obesity on markers of hepatic insulin signaling as well as structural changes in hepatocytes. Adult male Wistar rats were randomized and assigned to either a control group or a test group. Controls were fed standard laboratory pelleted diet (chow-fed), while the test group had free access to a highly-palatable diet (HPD). After eight weeks, the HPD-fed animals were subdivided into three subgroups and their diets altered as follows: HPD-to-chow, HPD with the addition of fenofibrate given by oral gavage for a further seven weeks, or HPD with vehicle (1% carboxymethylcellulose at 1 mL/kg body weight) given by oral gavage for a further seven weeks, respectively. Untreated diet-fed animals had significantly higher body weight, liver weight, and all measured metabolic profiles compared with chow-fed and treated diet-fed groups. Expression of kinases IRβ, IRS-1, AKt, eNOS, Shc and ERK1/2 were unaffected by obesity, while IRS-2 and P I3 kinase levels were significantly reduced in untreated HPD animals. Compared with chow-fed animals, steatosis and steatohepatitis were almost doubled in animals from untreated HPD, while removal of HPD and fenofibrate-treatment reduced steatosis by 40% and 80% respectively. These data suggest that diet-induced obesity affects intracellular insulin signaling mechanisms, namely IRS-2 and PI 3-kinase, leading to hepatic insulin resistance. Moreover, diet-induced obesity induces fatty liver, an effect which can be reversed by either removal of the source of obesity or treatment with fenofibrate, a peroxisome proliferator-activated receptor alpha agonist.

Cardiovascular risk factors, nonalcoholic fatty liver disease, and carotid artery intima-media thickness in an adolescent population in southern Italy

The objective of this study was to determine, in an adolescent population, the prevalence of nonalcoholic fatty liver disease (NAFLD) and the association of NAFLD and cardiovascular risk factors with carotid artery intima-media thickness (IMT), a marker of subclinical atherosclerosis. The authors conducted a population-based study among 642 randomly selected adolescents aged 11-13 years in Reggio Calabria, southern Italy, between November 2007 and October 2008. Prevalences of overweight and obesity were 30.5% and 13.5%, respectively. The overall prevalence of NAFLD was 12.5%, increasing to 23.0% in overweight/obese adolescents. In univariate analysis, increased IMT was positively associated with the presence of NAFLD, body mass index (BMI), waist circumference, systolic blood pressure (all P's < 0.001), diastolic blood pressure (P = 0.006), gamma-glutamyl transpeptidase (P = 0.006), alanine aminotransferase (P = 0.007), and C-reactive protein (P = 0.008) and was inversely associated with high density lipoprotein cholesterol (P < 0.001). In multivariate analysis, NAFLD (P = 0.002), BMI (P = 0.004), waist circumference (P = 0.003), and systolic blood pressure (P = 0.005) retained significant associations. The authors conclude that NAFLD, BMI, waist circumference, and systolic blood pressure are independent markers of increased IMT in a random sample of adolescents.

Assessment of liver steatosis in chicken by using acoustic radiation force impulse imaging: preliminary results

OBJECTIVE

To evaluate acoustic radiation force impulse (ARFI) imaging as a non-invasive tool for quantification of the grades of liver steatosis in chickens.

METHODS

We used two different diets: a standard diet (SD group) and a hyperlipidaemic diet (HD group). The ARFI technique was performed in all the animals in the right hepatic lobe and shear wave velocity (SWV) was measured and expressed in metres per second (m/s). Plasma lipid levels were analysed. Steatosis was quantified by using semiquantitative analysis. Statistical analysis was used and Pearson's correlation coefficient was calculated.

RESULTS

Mean SWV was 0.94 ± 0.16 m/s (range 0.8-1.3 m/s) in the SD group and 1.91 ± 0.25 m/s (range 1.3-2.2 m/s) in the HD group (p < 0.001). The lowest SWVs (≤1.3 m/s) corresponded to the chickens in the SD group, with 100% of the animals returning a score of 0, whereas the range of SWV in the HD group chickens was between 1.6 and 2.2 m/s. A substantial correlation was observed between SWVs with histological semiquantitative analysis of steatosis (r = 0.85, p < 0.001).

CONCLUSION

ARFI imaging is a non-invasive diagnostic tool that allows discrimination between the grades of liver steatosis in chickens.

Response to Fasting in an Unnaturally Obese Carnivore, the Captive European Polecat Mustela putorius

The European polecat ( Mustela putorius) is a naturally lean carnivore prone to excessive weight gain in captivity. This study assessed its suitability to investigate the natural history of the obese phenotype displayed in overweight humans, domestic animals, and seasonally obese wild mammals. Ten farm-bred polecats were subjected to a 5-day fast with 10 controls. Obesity (40% body fat) was associated with an unfavorable plasma lipid profile and high glucose and insulin concentrations. The polecats were in phase II of fasting with normoglycemia, low liver carbohydrate stores, and decreased plasma concentrations of urea and most amino acids. Although the plasma nonesterified fatty acid (NEFA) levels were elevated, the adipose tissue lipase activities suggested a blunted lipolytic response. Lipid mobilization was more efficient from intraabdominal fat. The animals developed hepatic lipidosis with elevated NEFA influx into the liver and losses of n-3 polyunsaturated fatty acids and arginine as hypothetical etiological factors. The plasma leptin, insulin, and triiodothyronine levels decreased but were not accompanied by reduced sex steroid or increased stress hormone concentrations. The blunted lipolytic response often encountered in obesity suggests that the organism is trying to defend the obese phenotype. Liver lipidosis and decreased insulin and triiodothyronine levels seem to be among the most consistent responses to fasting manifested in diverse mammalian orders and different levels of body fatness. The polecat could be recommended as an easily accessible carnivorean model to study the natural history of the obese phenotype and its comorbidities.

Nonalcoholic fatty liver disease in women

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in developed countries and is increasing in prevalence with the rise of diabetes and obesity. In addition to obesity and age, gender may also influence the prevalence and severity of NAFLD. However, mechanisms underlying gender-based differences in NAFLD have not been clearly defined. Furthermore, alterations in body composition, fat distribution and/or hormonal or metabolic changes that occur following menopause and in the setting of polycystic ovary syndrome may influence the development and progression of NAFLD. In this article, we will summarize known gender differences as well as the proposed mechanisms for gender differences in NAFLD, review two women-specific issues that may influence the prevalence and severity of NAFLD, menopause and polycystic ovary syndrome, and discuss potential therapeutic options for women with NAFLD who are postmenopausal or have polycystic ovary syndrome.

[Is bariatric surgery in adolescents appropriate?]

Current recommendations for bariatric surgery are limited to patients older than 18 years. Two studies in 2007 showed that bariatric surgery improves survival in adults. Medical management of severe obesity in adolescents is all too often ineffective. For these reasons, early surgical intervention for adolescents with morbid obesity may be expected to prevent or avoid comorbidities, decrease mortality, and improve the quality of life. Several studies have demonstrated the feasibility of adolescent bariatric surgery with morbidity comparable to that seen in adult series. The earlier the surgery, the better the result in terms of prevention or reversal of comorbid conditions. In the USA, a consensus definition of adolescents eligible for bariatric surgery specifies attainment of Tanner Stage IV of sexual maturity and achievement of 95% of axial growth. Just as in adults, bariatric surgery in adolescents requires prolonged follow-up; it is important that such surgery be performed in centers specialized in adult bariatric surgery having the necessary multidisciplinary structure.

Trends in nonalcoholic fatty liver disease-related hospitalizations in US children, adolescents, and young adults

OBJECTIVE

To investigate temporal trends of nonalcoholic fatty liver disease (NAFLD) and obesity among hospitalized US children, adolescents, and young adults over the past 2 decades and to examine potential sex disparities in NAFLD hospitalizations.

METHODS

Hospitalization discharges with NAFLD or obesity were identified among children and young adults (6-25 years, weighted n = 91,687,413) from the 1986 to 2006 National Hospital Discharge Survey data. Age- and sex-specific rates and trends in hospitalizations with NAFLD and obesity were estimated. Rates were standardized to age distribution of the 2000 US Census population. Sex disparities were examined for the most recent period 2004 to 2006 (weighted n = 12,969,532).

RESULTS

Between 1986 to 1988 and 2004 to 2006, hospitalizations with NAFLD diagnosis increased from 0.9 to 4.3/100,000 population (P < 0.001). During the same time, hospitalizations with a diagnosis of obesity increased from 35.5 to 114.7/100,000 population (P < 0.001). During 2004 to 2006, hospitalization rates with a diagnosis of NAFLD were higher among females than among males (5.9 vs 2.7/100,000 population, P < 0.001), as were hospitalizations with a diagnosis of obesity (140.8 vs 61.5/100,000 population, P < 0.001). Obesity and diabetes were reported in 43.3% and 31.9%, respectively, of discharges with NAFLD.

CONCLUSION

The prevalence of NAFLD among young hospitalized patients increased in the past 2 decades, paralleling obesity-related hospitalizations. This could be a consequence of the obesity epidemic or of increased screening for liver disease.

Association between leptin and transaminases: 1-year follow-up study in 180 overweight children

Leptin and insulin resistance are being discussed to be involved in the pathogenesis of nonalcoholic fatty liver disease, which is frequently characterized by moderately elevated transaminases. However, longitudinal studies proving an association between leptin, insulin resistance, and transaminases are scarce. We examined weight status, aspartate aminotransferase (AST), alanine aminotransferase (ALT), leptin, glucose, and insulin in 180 overweight children at baseline and 1 year later. Relationships between these parameters at baseline and their changes in the course of 1 year were determined by multiple regression analysis adjusted for age, sex, pubertal stage, and body mass index (BMI). Leptin but not homeostasis model assessment of insulin resistance index correlated significantly to transaminases in both cross-sectional and longitudinal analyses. The same findings were observed in 30 children with suspected nonalcoholic fatty liver disease by ultrasound. The 130 children who participated in a 1-year lifestyle intervention reduced their overweight (standard deviation score [SDS]-BMI, -0.37 +/- 0.11). In the course of 1 year, their changes of transaminases depended on change of weight status (SDS-BMI decrease >0.5: ALT 12 [10-15] --> 9 [8-13] U/L, AST 11 [9-12] --> 9 [8-12] U/L; SDS-BMI decrease >0 but <or=0.5: ALT 14 [11-18] --> 16 [12-26] U/L, AST 10 [8-14] --> 10 [8-24] U/L; no SDS-BMI decrease: ALT 13 [11-20] --> 20[13-33] U/L, AST 11 [9-21] --> 15 [9-24] U/L; data as median and interquartile range). The 50 children without intervention increased their SDS-BMI (+0.02 +/- 0.18) and transaminases (ALT 14 [11-18] --> 19 [15-25] U/L, AST 10 [8-15] --> 16 [10-25] U/L). These findings suggest that leptin may be involved in the pathogenesis of liver diseases. However, to test this hypothesis, careful histologic assessments in correlation to leptin levels are needed.

Adolescent obesity and bariatric surgery

PURPOSE OF REVIEW

Examines the effects of bariatric surgery on adolescent obesity.

RECENT FINDINGS

The risks and outcomes of bariatric surgery in adolescence are presently being defined and may be somewhat different from those in adults. Adolescents may have a greater risk of weight regain, and greater risk of noncompliance to treatment after surgery. However, long-term outcomes are not yet available, and the underlying metabolic benefits appear to be substantial and similar to those of adults.

SUMMARY

Morbid obesity in adolescents has severe acute and chronic complications. Bariatric surgery in adolescents seems as well tolerated as in adults when performed in centers with appropriate experience and adequate surgical volume. The pathophysiologic implications of bariatric surgery are profound. A better understanding of the mechanisms leading to postsurgical improvement in insulin resistance and weight loss could lead to the development of other therapies to achieve the same effects with lesser morbidities.

Prevalence of non-alcoholic fatty liver disease in children and relationship to metabolic syndrome, insulin resistance, and waist circumference

OBJECTIVES

To investigate the prevalence of non-alcoholic fatty liver disease (NAFLD) in children and its relationship to metabolic syndrome, insulin resistance, and waist circumference (WC).

METHODS

This was a population-based cross-sectional, case-control study. Cases were selected among students of a primary and junior high school, respectively, and age- and sex-matched control subjects were selected randomly (ratio of cases to control subject was 37:113).

RESULTS

Of the 846 students, aged between 6 and 15 years, enrolled in the study and screened by ultrasonography, 37 children were diagnosed as having NAFLD (score >/= 1). There was a significant sex difference in the prevalence of NAFLD(P = 0.003). The trend test revealed a strong dose-response relationship (P < 0.001) between pediatric NAFLD and the number of the proposed components of pediatric metabolic syndrome in Japan (MetS-JC), such as a clustering of the components of MetS-JC. Additionally, the linear trend of the odds ratios (ORs) with increasing percentile of the homeostasis model assessment-insulin resistance (HOMA-IR) was statistically significant (P < 0.001). However, when WC was added to the logistic model, the ORs were no longer significant, whereas WC turned out to be an independent risk factor for NAFLD regardless of the HOMA-IR index.

CONCLUSION

The prevalence of NAFLD in children and adolescents is closely related to metabolic syndrome, insulin resistance, and WC.

Nutrition and nonalcoholic fatty liver disease in children

Nonalcoholic fatty liver disease (NAFLD) is an obesity-associated liver disease found in 3% to 9% of children in the United States. NAFLD represents a spectrum of liver disease and is frequently associated with features of the metabolic syndrome. Nutrition's role in NAFLD is complex. It does not appear that overweight children with NAFLD have an unusual diet compared with their overweight counterparts without NAFLD. It is more likely that they have increased genetic susceptibility to the general poor diet and state of positive calorie balance currently found in many children. The available treatment studies using nutrition counseling and increased physical activity are promising. We recommend initiating sustainable family-oriented lifestyle changes in all children with NAFLD.

Nutrition and nonalcoholic fatty liver disease in children

Nonalcoholic fatty liver disease (NAFLD) is an obesity-associated liver disease found in 3% to 9% of children in the United States. NAFLD represents a spectrum of liver disease and is frequently associated with features of the metabolic syndrome. Nutrition's role in NAFLD is complex. It does not appear that overweight children with NAFLD have an unusual diet compared with their overweight counterparts without NAFLD. It is more likely that they have increased genetic susceptibility to the general poor diet and state of positive calorie balance currently found in many children. The available treatment studies using nutrition counseling and increased physical activity are promising. We recommend initiating sustainable family-oriented lifestyle changes in all children with NAFLD.