Leptin, free leptin index, insulin resistance and liver fibrosis in children with non-alcoholic fatty liver disease

Circulating leptin in patients with nonalcoholic fatty liver disease-related liver fibrosis: a systematic review and a meta-analysis

BACKGROUND AND AIM

Clinical data on the association between leptin levels and nonalcoholic fatty liver disease (NAFLD)-related liver fibrosis are conflicting. This meta-analysis aimed to compare circulating leptin between NAFLD patients with versus without liver fibrosis or non-NAFLD controls.

METHODS

A systematic search was conducted in PubMed, Scopus, and the Cochrane Library. Fifteen studies were included, reporting data from 964 individuals (422 NAFLD patients with fibrosis, 297 NAFLD patients without fibrosis, 245 no-NAFLD controls).

RESULTS

Leptin standardized mean difference (SMD) was higher in NAFLD patients with fibrosis (F1-F4) than in controls (SMD: 2.27; 95% confidence interval [CI]: 0.81-3.73); however, this association did not remain robust after the exclusion of studies with morbidly obese individuals. No difference was observed in leptin SMD between NAFLD patients with fibrosis and those without fibrosis (F0), and NAFLD patients without fibrosis versus controls. Heterogeneity was high (I2: 66-98%) among studies. Meta-regression analysis revealed a positive association of leptin SMD with homeostasis model assessment-insulin resistance, when comparing NAFLD patients with fibrosis versus NAFLD patients without fibrosis (beta: 0.53; 95% CI: 0.04-1.03), and a negative association of leptin SMD with age, when comparing NAFLD patients with fibrosis versus controls (beta: -0.29; 95% CI: -0.53 to -0.05).

CONCLUSION

Circulating leptin was higher in NAFLD patients with liver fibrosis than non-NAFLD controls, an association, however, attenuated after the exclusion of a study with morbidly obese individuals. Circulating leptin was not different between NAFLD patients with and without fibrosis, or NAFLD patients without fibrosis and controls.

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different

In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.

LncOb rs10487505 variant is associated with leptin levels in pediatric non-alcoholic fatty liver disease

BACKGROUND

Low and high leptin levels are associated with non-alcoholic fatty liver disease (NAFLD). The LncOb rs10487505 variant has been associated with body mass index (BMI), and the C allele was reported as leptin-lowering. We evaluated the association of rs10487505 with leptin levels, liver histology, and surgery-induced weight loss in youths with NAFLD.

METHODS

One-hundred five obese youths with NAFLD, of whom 19 undergoing laparoscopic sleeve gastrectomy (LSG), were analyzed for rs10487505 and leptin circulating levels.

RESULTS

The G allele frequency was lower in youths with NAFLD than in controls (p = 0.049). No difference was found in anthropometrics, biochemistry and histology between G allele carriers and CC homozygotes, except for leptin levels (p = 0.016). Leptin correlated with body weight, BMI, BMI-z score, waist circumference, insulin resistance/sensitivity, and triglycerides (p ≤ 0.01). A multivariable regression model including body weight and homeostasis model assessment of insulin resistance was a good predictor of plasma leptin (R² = 0.45), and the addition of genotype to the model increased the R² to 0.50. Following LSG, leptin levels and body weight were more reduced in G allele carriers (p < 0.05).

CONCLUSIONS

LncOb rs10487505 variant was associated with pediatric NAFLD and high leptin levels, and with weight and leptin reduction after LSG in youths.

IMPACT

The interplay of environment, genetics and epigenetics is crucial inflating the risk of non-alcoholic fatty liver disease (NAFLD). Several long non-coding RNA (LncRNAs) are found associated with NAFLD pathogenesis. Here, we evaluated the impact of the genetic variant rs10487505 in LncOb which is involved in the regulation of leptin gene expression. The LncOb rs10487505 is associated with increased levels of leptin, but not with liver histology, in youths with NAFLD. The LncOb rs10487505 was also associated with the significant decrease of leptin and body weight after bariatric surgery.

Lower Circulating Leptin Levels Are Related to Non-Alcoholic Fatty Liver Disease in Children With Obesity

Background

While for individuals with obesity an association between hyperleptinemia and an increased risk of non-alcoholic fatty liver disease (NAFLD) is assumed, a leptin deficiency is also related to the development of NAFLD early in life in ob/ob mice, in patients with leptin deficiency due to biallelic likely pathogenic variants in the leptin gene, and in patients with lipodystrophy.

Objectives

To investigate the association of circulating leptin levels in pre-pubertal children with obesity and steatosis hepatis.

Methods

The cross-sectional study consisted data of n=97 (nmale=76) pre-pubertal children (11.8 ± 1.5 years) with obesity (BMIz: 2.4 ± 0.4). Fasting concentrations of cardiometabolic parameters were measured: insulin, c-peptide, glucose, triglyceride, cholesterol, HDL, LDL, AST, ALT, GGT, leptin. Steatosis hepatis was diagnosed by an ultrasound examination (mild, moderate or severe). Patients were categorized into two groups: low z-score of circulating leptin levels (≤25th percentile) vs. normal z-score of circulating leptin levels.

Results

One-third of the children with obesity were diagnosed with steatosis hepatis (I°: 63.6%, II°/III°: 36.4%). Children with steatosis hepatis had significantly lower z-scores of circulating leptin levels compared to children with an unremarkable liver ultrasonography (-2.1 ± 0.8 vs. -0.7 ± 0.6). Z-scores of circulating leptin levels correlate negatively with degree of steatosis hepatis. Children with low z-scores of circulating leptin levels had significantly higher triglyceride, fasting insulin and c-peptide levels compared to children with normal z-scores of circulating leptin levels.

Conclusion

Prepubertal children with NAFLD and obesity and partial leptin deficiency might be defined as a clinical subgroup.

Deleted genes associated with obesity in Mexican patients diagnosed with nonalcoholic fatty liver disease

AIM

Nonalcoholic fatty liver disease (NAFLD) is a complex metabolic condition in which both lifestyle and genetic factors have a pathogenic role. The LEP gene encodes leptin, which regulates appetite, body weight, and several metabolic functions. Proopiomelanocortin (POMC), regulates food intake and energy balance. The aim of the study was to determine partial or complete deletions of genes associated with obesity in patients diagnosed with NAFLD.

MATERIAL AND METHODS

Blood samples and DNA from 43 individuals diagnosed with NAFLD by ultrasonographic technique (Fibroscan) were obtained. The partial or complete deletions of genes were determined by MLPA (Multiplex Ligation-dependent Probe Amplification) using the SALSA probemix P220-B2 Obesity only on 43 individuals. Fifty blood samples from healthy individuals were included.

RESULTS

Eleven out of 43 individuals analyzed by MLPA presented some deletion of the genes analyzed: six were female and five were male. The partial or complete deletion of the LEPR and POMC genes was observed in eight patients (18.6%), SIM1 in six patients (13.9%), GRIK2 and SH2B1 in two patients (4.7%), SEZGL2 in four patients (9.3%), and MCR4 in one patient (2.3%).

CONCLUSION

Partial deletion was observed in LEPR, POMC, SIM1, GRIK2, SH2B1, SEZGL2, and MCR4 genes in 26% of the cases, and we suggest that these alterations probably has a potential relationship for the development of NAFLD.

Serum leptin as a mediator of the influence of insulin resistance on hepatic steatosis in youths with excess adiposity

BACKGROUND AND AIMS

The relationship between insulin resistance (IR) and hepatic steatosis (fatty liver) is well known; however, the extent to which the satiety hormone leptin acts as a confounder or mediator in this relationship is uncertain. We examined whether the association between IR and hepatic steatosis is mediated by leptin in Colombian adolescents with excess adiposity.

METHODS AND RESULTS

A total of 122 adolescents (mean age: 13.4 years; 68% girls) participated in the study. We assessed body composition, hepatic steatosis (as defined by the controlled attenuation parameter [CAP]), cardiometabolic risk factors (body mass index, waist circumference, body composition), biochemical variables (leptin, insulin, glucose, lipid profile, cardiometabolic Z-score, transaminases, etc.), and physical fitness (cardiorespiratory fitness and grip strength). Partial correlation, regression, and mediation analyses were conducted using the Barron and Kenny framework.

RESULTS

Ninety-two youths (75.4%) had IR. Mediation analysis revealed a positive relationship between Homeostasis Model Assessment-IR (HOMA-IR) and CAP (β_dir = 3.414, 95% confidence interval [CI]: 1.012 to 5.816, p < 0.001), which was attenuated when leptin was included in the model, thus indicating that leptin mediates this relationship (β_ind = 1.074, 95% CI: 0.349 to 2.686, p < 0.001). The percentage of the total effect mediated by leptin was 21%. Regarding sex, the mediation effect of leptin remains significant among boys (β_ind = 0.962, 95% CI: 0.009 to 2.615, p < 0.001), but not in girls (β_ind = 0.991, 95% CI: 1.263 to 5.483, p = 0.477).

CONCLUSIONS

The findings are clinically relevant to consider leptin levels as a surrogate marker of insulin sensitivity when assessing youths with excess adiposity and/or suspected Nonalcoholic hepatic steatosis or nonalcoholic fatty liver disease (NAFLD).

Prevalence of prediabetes and diabetes in children and adolescents with biopsy-proven non-alcoholic fatty liver disease

BACKGROUND & AIMS

We undertook a cross-sectional study of children/adolescents with and without non-alcoholic fatty liver disease (NAFLD) to compare the prevalence of prediabetes and diabetes, and to examine the role of abnormal glucose tolerance as a predictor of liver disease severity.

METHODS

We recruited a cohort of 599 Caucasian children/adolescents with biopsy-proven NAFLD, and 118 children/adolescents without NAFLD, who were selected to be similar for age, sex, body mass index and waist circumference to those with NAFLD. The diagnosis of prediabetes and diabetes was based on either hemoglobin A1c, fasting plasma glucose or 2 h post-load glucose concentrations.

RESULTS

Children/adolescents with NAFLD had a significantly higher prevalence of abnormal glucose tolerance (prediabetes or diabetes) than those without NAFLD (20.6% vs. 11%, p = 0.02). In particular, 124 (20.6%) children/adolescents with NAFLD had abnormal glucose tolerance, with 19.8% (n = 119) satisfying the diagnostic criteria for prediabetes and 0.8% (n = 5) satisfying the criteria for diabetes. The combined presence of prediabetes and diabetes was associated with a nearly 2.2-fold increased risk of non-alcoholic steatohepatitis (NASH; unadjustedodds ratio 2.19; 95% CI 1.47-3.29; p <0.001). However, this association was attenuated (but remained significant) after adjustment for age, sex, waist circumference (adjustedodds ratio 1.69, 95% CI 1.06-2.69, p = 0.032), and the PNPLA3 rs738409 polymorphism. Both this PNPLA3 polymorphism and waist circumference were strongly associated with NASH.

CONCLUSIONS

Abnormal glucose tolerance (especially prediabetes) is highly prevalent among children/adolescents with biopsy-proven NAFLD. These children also have a higher risk of NASH, though central adiposity is the factor that is most strongly associated with NASH.

LAY SUMMARY

Children with biopsy-proven non-alcoholic fatty liver disease (NAFLD) have a higher prevalence of abnormal glucose tolerance (prediabetes or type 2 diabetes) than children without NAFLD. Children with biopsy-proven NAFLD and abnormal glucose tolerance also have a higher prevalence of the progressive form of disease, non-alcoholic steatohepatitis, than those with normal glucose tolerance, though central adiposity is the factor that is most strongly associated with non-alcoholic steatohepatitis.

The Role of Genetic Predisposition, Programing During Fetal Life, Family Conditions, and Post-natal Diet in the Development of Pediatric Fatty Liver Disease

OBJECTIVE

To evaluate, in patients with nonalcoholic fatty liver disease (NAFLD), the role of lifetime exposures associated with genetic predisposition, family history (parental obesity, economic income), programming during fetal life (gestational age, birthweight), being breastfed or not, and later biomarkers of dietary habits and lifestyle in the development of fibrosis.

STUDY DESIGN

In total, 182 children with overweight/obesity diagnosed with NAFLD proven by biopsy results were enrolled in our study and evaluated for liver fibrosis. We estimated prevalence ORs of fibrosis according to genetics, parental obesity, occupational socioeconomic status (SES), birth weight, breastfeeding, fructose intake (indicator of junk food consumption), and vitamin D status (inflammatory indicator) using logistic regression models, adjusted for age and children's body mass.

RESULTS

One hundred thirty-seven patients (75.3%) had liver fibrosis, and 45 patients (24.7%) did not have liver fibrosis. The ORs of fibrosis were significant (P < .05) for patatin like phospholipase domain-containing 3-GG genotype (OR 2.1), parental obesity (OR 2.9), not being breastfed (OR 3.1), vitamin D status (<20 mg/dL) (OR 1.24), and fructose consumption (OR 1.6 per 1 g/day increase), whereas a high SES maternal occupation was inversely associated with fibrosis (OR 0.30).

CONCLUSIONS

Our results show independent roles of the patatin like phospholipase domain-containing 3 gene, parental obesity, maternal SES, and postnatal diet and lifestyle in the development of progressive liver disease secondary to NAFLD.

Including Fibroblast Growth Factor-21 in Combined Biomarker Panels Improves Predictions of Liver Steatosis Severity in Children

Background: Previous studies reported conflicting results regarding the association between fibroblast growth factor-21 (FGF-21) and non-alcoholic fatty liver disease (NAFLD). This study aimed to evaluate the feasibility of combining FGF-21, obesity indices, and biochemical tests for predicting high-grade liver steatosis in children. Methods: A total of 203 children and adolescents aged 5-18 years were enrolled, and their anthropometric data, body composition, liver ultrasound score for NAFLD (range, 0-6), biochemical test results, and FGF-21, leptin, and adiponectin levels were analyzed. Children were categorized according to body mass index (BMI) and NAFLD scores. Univariate analysis and multivariate linear regression were used to identify independent predictors for the degree of liver steatosis. The accuracy of the models was also evaluated using a receiver-operating characteristic (ROC) curve. Results: FGF-21 levels were significantly higher in subjects with high-grade liver steatosis (P < 0.001). In obese and overweight children, regression analysis indicated that higher BMI and higher gamma-glutamyl transferase (γ-GT), triglycerides (TG), and FGF-21 levels were independent risk factors strongly correlated with NAFLD scores. FGF-21 combined with any of the above parameters showed a larger area under the ROC (AUROC, 0.861-0.873) than either parameter used alone. Overall, the best performance was obtained by combing FGF-21, γ-GT, and TG, with an AUROC of 0.871, specificity of 82.54%, and sensitivity of 83.78% for predicting high-grade liver steatosis. Conclusion: BMI, FGF-21, γ-GT, and TG levels were strongly correlated with liver steatosis severity. Including FGF-21 in the biomarker panels may improve the accuracy for identifying obese and overweight children with high-grade liver steatosis.

Bile acid regulation: A novel therapeutic strategy in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive fat deposition in the liver in the absence of significant alcohol consumption. Dysregulated bile acid (BA) metabolism is an important indicator in the pathology of NAFLD, which could progress into more severe forms of liver injury. Lipid metabolism, immune environment and intestinal bacteria are all affected by dysregulated BA metabolism directly, but the mechanisms remain unclear. Several drug candidates that target BA metabolism, either used alone or in combination with other agents, are currently under development for treatment of NAFLD. Here, we summarize the relationship of dysregulated BA metabolism and NAFLD, discuss the effects and mechanisms of dysregulated BAs-induced lipid metabolism disorder. Challenges in developing novel treatments are also discussed.

Combination of a high-fat diet with sweetened condensed milk exacerbates inflammation and insulin resistance induced by each separately in mice

Obesogenic diets increase body weight and cause insulin resistance (IR), however, the association of these changes with the main macronutrient in the diet remains to be elucidated. Male C57BL/6 mice were fed with: control (CD), CD and sweetened condensed milk (HS), high-fat (HF), and HF and condensed milk (HSHF). After 2 months, increased body weight, glucose intolerance, adipocyte size and cholesterol levels were observed. As compared with CD, HS ingested the same amount of calories whereas HF and HSHF ingested less. HS had increased plasma AST activity and liver type I collagen. HF caused mild liver steatosis and hepatocellular damage. HF and HSHF increased LDL-cholesterol, hepatocyte and adipocyte hypertrophy, TNF-α by macrophages and decreased lipogenesis and adiponectin in adipose tissue (AT). HSHF exacerbated these effects, increasing IR, lipolysis, mRNA expression of F4/80 and leptin in AT, Tlr-4 in soleus muscle and IL-6, IL-1β, VCAM-1, and ICAM-1 protein in AT. The three obesogenic diets induced obesity and metabolic dysfunction. HS was more proinflammatory than the HF and induced hepatic fibrosis. The HF was more detrimental in terms of insulin sensitivity, and it caused liver steatosis. The combination HSHF exacerbated the effects of each separately on insulin resistance and AT inflammatory state.

Comparison of the Phenotype and Approach to Pediatric vs Adult Patients With Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the main chronic noncommunicable diseases in Westernized societies; its worldwide prevalence has doubled during the last 20 years. NAFLD has serious health implications not only for adults, but also for children. However, pediatric NAFLD is not only an important global problem in itself, but it is likely to be associated with increases in comorbidities, such as metabolic syndrome and cardiovascular diseases. There are several differences between NAFLD in children and adults, and it is not clear whether the disease observed in children is the initial phase of a process that progresses with age. The increasing prevalence of pediatric NAFLD has serious implications for the future adult population requiring appropriate action. Studies of NAFLD progression, pathogenesis, and management should evaluate disease phenotypes in children and follow these over the patient's lifetime. We review the similarities and differences of NAFLD between children and adults.

Leptin, Leptin Soluble Receptor, and the Free Leptin Index following a Diet and Physical Activity Lifestyle Intervention in Obese Males and Females

Leptin (LEP) is associated with appetite regulation and metabolism. Concentration is linear with adiposity, suggesting LEP resistance. LEP circulates freely and bound with its soluble receptor (sOB-r); the ratio is the free leptin index (FLI), an index of leptin resistance; lower FLI suggests reduced biological action. Purpose. The aim was to determine the effect of changes in adipose tissue distribution on LEP, sOB-r, and FLI following 6 months (6 M) of a diet/exercise weight loss program (WLP). In addition, we aim to identify predictors of the FLI. Methods. 6 M WLP consisted of diet/lifestyle interventions following ADA guidelines. Body composition was assessed by DXA. LEP and sOB-r analysis were done via ELISA. Results. 10 adults completed the WLP. Significant reductions were seen in total fat percentage (% fat), nontrunk fat, (NTF), and trunk fat (TF) from base to 3 m and 6 M (p ≤ 0.05). The FLI were reduced at 3 M and 6 M for males and 6 M for females. Total body fat and body weight predicted the FLI in both sexes. Conclusions. LEP and FLI reductions following 6 M of WLP were achieved independent of sOB-r changes. We also demonstrate that the FLI can be predicted noninvasively through total fat mass and body weight in kilograms.

Circulating leptin in non-alcoholic fatty liver disease: a systematic review and meta-analysis

AIMS/HYPOTHESIS

Clinical data regarding circulating leptin levels in patients with non-alcoholic fatty liver disease (NAFLD) are conflicting. The purpose of this meta-analysis was to compare leptin levels between the following groups: patients with biopsy-proven NAFLD vs controls; simple steatosis (SS) patients vs controls; non-alcoholic steatohepatitis (NASH) patients vs controls and NASH patients vs SS patients.

METHODS

We performed a systematic search in PubMed, Scopus and the Cochrane Library. We analysed 33 studies, published between 1999 and 2014, including 2,612 individuals (775 controls and 1,837 NAFLD patients).

RESULTS

Higher circulating leptin levels were observed in NAFLD patients vs controls (standardised mean difference [SMD] 0.640; 95% CI 0.422, 0.858), SS patients vs controls (SMD 0.358; 95% CI 0.043, 0.673), NASH patients vs controls (SMD 0.617; 95% CI 0.403, 0.832) and NASH patients vs SS patients (SMD 0.209; 95% CI 0.023, 0.395). These results remained essentially unchanged after excluding studies involving paediatric or adolescent populations and/or individuals undergoing bariatric surgery. There was moderate-to-severe heterogeneity among studies in all comparisons, but no significant publication bias was detected. Meta-regression analysis demonstrated that BMI was inversely associated with leptin SMD and accounted for 26.5% (p = 0.014) and 32.7% (p = 0.021) of the between-study variance in the comparison between NASH patients and controls and NAFLD patients and controls, respectively. However, when bariatric studies were excluded, BMI did not significantly explain the between-study variance.

CONCLUSIONS/INTERPRETATION

Circulating leptin levels were higher in patients with NAFLD than in controls. Higher levels of circulating leptin were associated with increased severity of NAFLD, and the association remained significant after the exclusion of studies involving paediatric or adolescent populations and morbidly obese individuals subjected to bariatric surgery.

Gender Specific Association of Serum Leptin and Insulinemic Indices with Nonalcoholic Fatty Liver Disease in Prediabetic Subjects

Adipose tissue-derived hormone leptin plays a functional role in glucose tolerance through its effects on insulin secretion and insulin sensitivity which also represent the risk factors for nonalcoholic fatty liver disease (NAFLD). The present study explored the gender specific association of serum leptin and insulinemic indices with NAFLD in Bangladeshi prediabetic subjects. Under a cross-sectional analytical design a total of 110 ultrasound examined prediabetic subjects, aged 25-68 years consisting of 57.3% male (55.6% non NAFLD and 44.4% NAFLD) and 42.7% female (57.4% non NAFLD and 42.6% NAFLD), were investigated. Insulin secretory function (HOMA%B) and insulin sensitivity (HOMA%S) were calculated from homeostasis model assessment (HOMA). Serum leptin showed significant positive correlation with fasting insulin (r = 0.530, P = 0.004), postprandial insulin (r = 0.384, P = 0.042) and HOMA-IR (r = 0.541, P = 0.003) as well as significant negative correlation with HOMA%S (r = -0.388, P = 0.046) and HOMA%B (r = -0.356, P = 0.039) in male prediabetic subjects with NAFLD. In multiple linear regression analysis, log transformed leptin showed significant positive association with HOMA-IR (β = 0.706, P <0.001) after adjusting the effects of body mass index (BMI), triglyceride (TG) and HOMA%B in male subjects with NAFLD. In binary logistic regression analysis, only log leptin [OR 1.29 95% (C.I) (1.11-1.51), P = 0.001] in male subjects as well as HOMA%B [OR 0.94 95% (C.I) (0.89-0.98), P = 0.012], HOMA-IR [OR 3.30 95% (C.I) (0.99-10.95), P = 0.049] and log leptin [OR 1.10 95% (C.I) (1.01-1.20), P = 0.026] in female subjects were found to be independent determinants of NAFLD after adjusting the BMI and TG. Serum leptin seems to have an association with NAFLD both in male and female prediabetic subjects and this association in turn, is mediated by insulin secretory dysfunction and insulin resistance among these subjects.

Effects of temporary low-dose galactose supplements in children aged 5-12 y with classical galactosemia: a pilot study

BACKGROUND

Classical galactosemia is caused by severe galactose-1-phosphate uridyltransferase deficiency. Despite life-long galactose-restriction, many patients experience long-term complications. Intoxication by galactose and its metabolites as well as over-restriction of galactose may contribute to the pathophysiology. We provided temporary low-dose galactose supplements to patients. We assessed tolerance and potential beneficial effects with clinical monitoring and measurement of biochemical, endocrine, and IgG N-glycosylation profiles.

METHODS

We enrolled 26 patients (8.6 ± 1.9 y). Thirteen were provided with 300 mg of galactose/day followed by 500 mg for 2 wk each (13 patient controls).

RESULTS

We observed no clinical changes with the intervention. Temporary mild increase in galactose-1-phosphate occurred, but renal, liver, and bone biochemistry remained normal. Patients in the supplementation group had slightly higher leptin levels at the end of the study than controls. We identified six individuals as "responders" with an improved glycosylation pattern (decreased G0/G2 ratio, P < 0.05). There was a negative relationship between G0/G2 ratio and leptin receptor sOb-R in the supplementation group (P < 0.05).

CONCLUSION

Temporary low-dose galactose supplementation in children over 5 y is well tolerated in the clinical setting. It leads to changes in glycosylation in "responders". We consider IgG N-glycan monitoring to be useful for determining individual optimum galactose intake.

Non-alcoholic fatty liver and metabolic syndrome in children: a vicious circle

During the last decade, paediatricians have observed a dramatic increase of non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) in children. Furthermore, several lines of evidence have reported that a large part of children with NAFLD presents one or more traits of MS making plausible that, in the coming years, these subjects may present a rapid course of disease towards more severe cirrhosis and cardiovascular disease. Genetic susceptibility and the pressure of intrauterine environment and lifestyle are all crucial to activate molecular machinery that leads to development of NAFLD and MS in childhood. In this scenario, central obesity and consequent adipose tissue inflammation are critical to promote both MS-associated metabolic dysfunctions and NAFLD-related hepatic damage. An excessive dietary intake may in fact cause a specific lipid partitioning and induce metabolic stressors, which in turn promote insulin resistance and the release of several circulating factors. These molecules, on the one hand, trigger steatosis and the inflammatory response that characterize liver damage in NAFLD, and on the other hand contribute to the onset of other features of MS. This review provides an overview of current genetic, pathogenetic and clinical evidence of the vicious circle created by NAFLD and MS in children.

Temporal relationship between diet-induced steatosis and onset of insulin/leptin resistance in male Wistar rats

Rats fed with high-fat-high-sucrose (HFHS) diet are known to manifest metabolic syndrome including hyperinsulinemia, hyperleptinemia, hyperglycemia, diabetic dyslipidemia, and hepatic steatosis. The aim of the current study is to determine the temporal relationships between the development of hepatic steatosis and the onset of insulin and leptin resistance in hypothalamus and liver in male Wistar rats (six weeks of age) fed chow or HFHS diet for up to 8 weeks. Fasting plasma glucose, lipids/lipoproteins, insulin and leptin levels were quantified, histopathologic score of hepatic steatosis and inflammation were assessed, and the responses of common checkpoints of insulin and leptin signalling responsible for lipogenesis and gluconeogenesis were analyzed. In addition, acute insulin or leptin administration was performed at different stages of HFHS dieting to determine the responsiveness of the respective signalling pathways. Hyperinsulinemia, hyperglycemia, dyslipidemia, and increased homeostasis model assessment of basal insulin resistance occurred 1-week after HFHS dieting, coinciding with upregulation of suppressor of cytokine signalling 3 in both hypothalamus and liver. However, hepatosteatosis, accompanied with increased expression of sterol regulatory element binding protein 1c and phosphoenolpyruvate carboxykinase, did not manifest until 4- to 8-week after HFHS dieting. Lowered insulin sensitivity (shown by decreased insulin receptor substrate 1 and protein kinase B phosphorylation) occurred approximately 2 weeks prior to leptin resistance (shown by impaired signal transducer and activator of transcription 3 activation) in both the liver and hypothalamus. Acute insulin/leptin administration also demonstrated the impaired insulin or leptin signalling transduction. These data suggest that lowered insulin sensitivity and leptin resistance occurred at least 2–3 weeks earlier than the manifestation of hepatosteatosis in rats fed HFHS diet.

Diagnosis and classification of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis: Current concepts and remaining challenges

The high prevalence of non-alcoholic fatty liver disease (NAFLD) has made the condition an important public health issue. Two clinical entities are manifestations of NAFLD, namely, non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). The former tends to be benign and non-progressive while the latter can progress to cirrhosis, which in rare cases gives rise to hepatocellular carcinoma. The diagnosis of NAFLD is based on: (i) a history of no or limited daily alcohol intake (<20 g for women and <30 g for men); (ii) presence of hepatic steatosis by imaging or by histology; and (iii) exclusion of other liver diseases. NAFL is defined histologically by the presence of bland, primarily macrovesicular, hepatocellular fatty change, while NASH features fatty change with inflammation and evidence of hepatocyte injury, such as ballooning degeneration. Presence of fibrosis is a sign of chronicity. Thus, the diagnosis of NAFL/NASH rests on clinicopathological criteria; it always requires both clinical and biopsy-based information. NAFLD could be both the result and the cause of metabolic syndrome, with a vicious cycle operating between these conditions. Remaining challenges are: (i) the lack of a clear threshold alcohol intake for defining "non-alcoholic"; (ii) a lacking consensus for the classification of fatty liver disease; and (iii) absence of a histological definition of NASH, which currently remains the gold standard for the diagnosis. Further challenges include the overlap of the criteria for NAFLD and alcoholic liver disease as many obese individuals also consume considerable volumes of alcohol.

Leptin in nonalcoholic fatty liver disease: a narrative review

Leptin, the first described adipokine, interplays with hepatic metabolism. The aim of this review was to summarize available data on the association between leptin and nonalcoholic fatty liver disease (NAFLD). Leptin has a potential dual action on NAFLD experimental models, exerting a possible anti-steatotic, but also a proinflammatory and profibrogenic action. Observational clinical studies have shown higher or similar leptin levels between simple steatosis and nonalcoholic steatohepatitis (NASH) compared with controls. Interventional studies showed that circulating leptin diminishes together with body mass index after successful weight loss following lifestyle modifications or bariatric surgery. Studies providing evidence for the effect of other medications on leptin levels in NAFLD populations are limited and of low power. Data from small studies claim that recombinant leptin administration had a possibly beneficial effect on steatosis, but not fibrosis, in NAFLD patients with hypoleptinemia. Although the aforementioned dual leptin action has not yet been validated in humans, leptin administration in NAFLD patients with normoleptinemia or hyperleptinemia is discouraged. Further well-controlled studies in cautiously selected populations are needed to elucidate whether leptin has any prognostic and therapeutic role in NAFLD patients.

Discovery of a Potent 9-Deazaxanthine-based Agent for the Treatment of Obesity-Related Non-alcoholic Fatty Liver Disease

A series of deazaxanthine-based derivatives were rationally prepared and evaluated. 8g exhibited the most potent glucose-lowering effect on HepG2 cell line and modulated adiponectin and leptin expression in 3T3-L1 adipocytes. Oral administration of 8g at 25 mg/kg/day for 4 weeks manifested therapeutic effects on high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) by decreasing the weights of the body, liver, and fat. 8g also modulated the serum levels of fasting glucose and adiponectin, triglycerides, low-density lipoprotein-cholesterol, and alanine aminotransferase, as well as the hepatic concentrations of triglycerides, total cholesterol. Moreover, 8g significantly decreased steatosis and blocked the increase of adipocytes and the size of adipose tissues from NAFLD. In the DIO mice model, 8g ameliorated the obesity-related symptoms and normalized serum biomarkers.

Role of adipokines and peroxisome proliferator-activated receptors in nonalcoholic fatty liver disease

Intrahepatic fat deposition has been demonstrated in patients with nonalcoholic fatty liver disease (NAFLD). Genetic and environmental factors are important for the development of NAFLD. Diseases such as obesity, diabetes, and hypertension have been found to be closely associated with the incidence of NAFLD. Evidence suggests that obesity and insulin resistance are the major factors that contribute to the development of NAFLD. In comparing the factors that contribute to the buildup of excess calories in obesity, an imbalance of energy homeostasis can be considered as the basis. Among the peripheral signals that are generated to regulate the uptake of food, signals from adipose tissue are of major relevance and involve the maintenance of energy homeostasis through processes such as lipogenesis, lipolysis, and oxidation of fatty acids. Advances in research on adipose tissue suggest an integral role played by adipokines in NAFLD. Cytokines secreted by adipocytes, such as tumor necrosis factor-α, transforming growth factor-β, and interleukin-6, are implicated in NAFLD. Other adipokines, such as leptin and adiponectin and, to a lesser extent, resistin and retinol binding protein-4 are also involved. Leptin and adiponectin can augment the oxidation of fatty acid in liver by activating the nuclear receptor super-family of transcription factors, namely peroxisome proliferator-activated receptor (PPAR)-α. Recent studies have proposed downregulation of PPAR-α in cases of hepatic steatosis. This review discusses the role of adipokines and PPARs with regard to hepatic energy metabolism and progression of NAFLD.

Noninvasive biomarkers in non-alcoholic fatty liver disease: Current status and a glimpse of the future

The development of non invasive biomarkers of disease has become a major focus of interest in nonalcoholic fatty liver disease (NAFLD). The large prevalence of the disease and the invasive nature of the investigation means that screening with liver biopsy is impractical. In addition to screening, the differentiation of those with simple steatosis vs steatohepatitis and fibrosis is clinically important as the prognosis of each differs. Serum biomarkers may be a combination of simple markers derived from large data sets or direct markers of disease activity. Serum markers of inflammation, apoptosis and oxidative stress in addition to fibrosis have been extensively studied in patients with NAFLD. Other techniques such as transient elastography, magnetic resonance elastography and acoustic radiation force imaging are becoming more established as noninvasive methods of detecting fibrosis in a variety of chronic liver conditions in addition to NAFLD. Newer high throughput methods such as proteomics and glycomics allow the nonhypothesis-driven identification of novel markers and may also potentially contribute to our understanding of the pathogenesis of the condition. This review addresses some of the methodological issues which need to be considered in the search for the ideal biomarker. It is likely that a combination of serum biomarkers and techniques such as transient elastography may provide the optimal diagnostic discrimination however this remains to be proven in large studies.

Non-alcoholic Fatty liver disease in children

In the last years, there has been extremely much information which reveals an alarming increase of obesity in children and, at the same time, an increase of the incidence of non-alcoholic fatty liver disease (NAFLD). NAFLD implies a wide range of affections starting from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH); the latter can evolve to cirrhosis and hepatic carcinoma. All these affections were noticed in children, too. The article presents data on the epidemiology, pathogeny, clinical and paraclinical findings, and treatment of NAFLD in children.

Synthesis and biological evaluation of novel urea- and guanidine-based derivatives for the treatment of obesity-related hepatic steatosis

Leptin, the product of the obese gene, is an adipocyte-secreted protein hormone playing a key role in the progression of obesity and hepatic steatosis. In this study, 28 novel (thio)urea and guanidine-based analogues have been synthesized and N-(1-(4-(3-(2-chloroethyl)ureido)benzyl)piperidin-4-yl)-3-(trifluoromethyl) benzamide (7i) was found to be a potent regulator of leptin expression in 3T3-L1 adipocytes. Treatment with 7i at a dose of 50 mg/kg/day for 35 days reduced the body weight and liver weight of diet-induced obesity mice by 13.5% and 18.4%, respectively, while also improving the serum levels of triglyceride, total cholesterol, leptin, adiponectin, LDL-c, HDL-c. Hematoxylin-eosin (H&E) and Oil Red O staining also confirmed that 7i ameliorated fat deposition in liver tissue and restricted the size of adipocytes in obesity-related fatty liver disease.

Rapid improvement of hepatic steatosis after initiation of leptin substitution in a leptin-deficient girl

BACKGROUND

Leptin deficiency is associated with severe obesity and metabolic disturbances. Increased liver fat content has been reported in only one case beforehand, even though hepatic steatosis is a typical comorbidity of common obesity. It is also frequent in patients with lipodystrophy where it resolves under leptin therapy.

SUBJECT AND METHODS

In 2010, we reported a leptin-deficient patient with a novel homozygous mutation in the leptin gene and severe hepatic steatosis. We have now studied serum changes and changes in liver fat content during the substitution with recombinant methionyl human leptin.

RESULTS

After 23 weeks of leptin substitution, elevated transaminases, total cholesterol and low-density lipoprotein levels normalized. After 62 weeks, homeostasis model assessment of insulin resistance improved from 10.7 to 6.0 and body fat mass dropped from 50.2 to 37.8%. Liver fat content was drastically reduced from 49.7 to 9.4%. The first changes in liver fat content were detectable after 3 days of therapy.

CONCLUSION

Our patient showed a remarkable reduction of liver fat content during the treatment with recombinant methionyl human leptin. These changes occurred rapidly after initiation of the substitution, which implies that leptin has a direct effect on hepatic lipid metabolism in humans as it is seen in rodents.

Adipokines and melanocortins in the hepatic manifestation of metabolic syndrome: nonalcoholic fatty liver disease

Metabolic syndrome is associated with nonalcoholic fatty liver disease and its more aggressive form, nonalcoholic steatohepatitis. Adipokines produced by white adipose tissue possess broad physiological activity and play an important autocrine role in obesity-associated complications, including metabolic syndrome, nonalcoholic fatty liver disease and cardiovascular disease. Various adipokines may have beneficial or harmful effects. Other tissues, particularly stomach and intestine, produce active molecules that can influence the function of adipocytes and, possibly, the levels of adipokine secretion. In some cases, the production sites of these molecules remain unknown. The review focuses on our current understanding of the disease-related effects of the adipokines and the melanocortins on various peripheral tissues, and discusses some of their potential interactions with each other. Potential therapeutic applications are also considered.

Leptin's role in lipodystrophic and nonlipodystrophic insulin-resistant and diabetic individuals

Leptin is an adipocyte-secreted hormone that has been proposed to regulate energy homeostasis as well as metabolic, reproductive, neuroendocrine, and immune functions. In the context of open-label uncontrolled studies, leptin administration has demonstrated insulin-sensitizing effects in patients with congenital lipodystrophy associated with relative leptin deficiency. Leptin administration has also been shown to decrease central fat mass and improve insulin sensitivity and fasting insulin and glucose levels in HIV-infected patients with highly active antiretroviral therapy (HAART)-induced lipodystrophy, insulin resistance, and leptin deficiency. On the contrary, the effects of leptin treatment in leptin-replete or hyperleptinemic obese individuals with glucose intolerance and diabetes mellitus have been minimal or null, presumably due to leptin tolerance or resistance that impairs leptin action. Similarly, experimental evidence suggests a null or a possibly adverse role of leptin treatment in nonlipodystrophic patients with nonalcoholic fatty liver disease. In this review, we present a description of leptin biology and signaling; we summarize leptin's contribution to glucose metabolism in animals and humans in vitro, ex vivo, and in vivo; and we provide insights into the emerging clinical applications and therapeutic uses of leptin in humans with lipodystrophy and/or diabetes.

The potential role of fatty liver in paediatric metabolic syndrome: a distinct phenotype with high metabolic risk?

BACKGROUND

The prevalence of obesity and its metabolic consequences has dramatically increased in the last two decades urging physicians to find a reliable definition for early detection, treatment and possibly prevention of metabolic syndrome (MS). MS could be diagnosed in adult patients in the presence of a large waist circumference and ≥2 of the following features: high serum triglycerides, low serum high-density lipoprotein cholesterol, high blood pressure and high fasting glucose. The definition of MS in children is more problematic, and the potential role of its single components on metabolic risk remains largely undefined. Recent evidence strongly suggests not only a relationship between non-alcoholic fatty liver disease (NAFLD) and MS in obese children, adolescents and adults, but also the key role exerted by liver fat deposition in the pathogenesis of MS.

CONCLUSION

We propose that NAFLD should be routinely checked in obese subjects because early lifestyle changes may be effective in reducing the overall risk of MS.

Synthesis and biological evaluation of 5-benzylidenepyrimidine-2,4,6(1H,3H,5H)-trione derivatives for the treatment of obesity-related nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), one of chronic liver diseases, seems to be rising as the obesity epidemic continues. In this study, 54 novel (thio)barbituric acid derivatives have been synthesized and evaluated for pharmacological activity. 7h exhibited potent glucose-lowering effects on insulin-resistant HepG2 cells and regulated adiponectin and leptin expression in 3T3-L1 adipocytes. Oral administration of 7h at 25 mg kg(-1) day(-1) for 4 weeks improved the progression of high fat diet-induced NAFLD by reducing the weight of body, liver, and fat, as well as modulating serum levels of fasting glucose, insulin, triglycerides, LDL-c, ALT, adiponectin and hepatic contents of triglycerides, total cholesterol. H&E stainings revealed that 7h blocked fat deposition in liver and the increase of adipocyte number and size in adipose tissues from NAFLD. Furthermore, treatment with 7h alleviated the obese clinical symptoms, recovered serum biomarkers to appropriate ranges, and improved glucose tolerance by OGTT and IGTT in DIO mice.

Patterns of surgical weight loss and resolution of metabolic abnormalities in superobese bariatric adolescents

PURPOSE

The aim of the study was to compare the baseline and the 18-month follow-up for weight and metabolic characteristics of superobese (SO) (body mass index [BMI] ≥50 kg/m(2)) and morbidly obese (MO) (BMI <50 kg/m(2)) adolescents who participated in a prospective longitudinal study of gastric banding delivered in an adolescent multidisciplinary treatment program.

METHODS

Clinical information was extracted from an institutional review board-approved database of bariatric adolescents. Fasting cytokine and acute phase protein serum levels were analyzed by enzyme-linked immunosorbent assay. Liver histopathologies were assessed using the Kleiner's classification score.

RESULTS

Other than BMI, MO (n = 11) and SO (n = 7) patients have similar degree of insulin resistance, dyslipidemia, and nonalcoholic fatty liver disease. Serum C-reactive protein (10.2 ± 5.6 SO vs 4 ± 3.9 μg/mL MO [P < .02]) and leptin (71 ± 31 SO vs 45 ± 28 MO ng/mL [P = .04]) were more elevated in SO patients. Although weight loss is similar (30 ± 19 kg MO vs 28 ± 12 kg SO, P = .8 at 18 months; mean percent change in BMI, 22.8% ± 11.6% vs 20.5% ± 10.3% SO, P = .2), SO patients has less resolution of insulin resistance and dyslipidemia but experienced significantly improved health-related quality of life.

CONCLUSIONS

The SO adolescents demonstrate equivalent short-term weight loss and improved quality of life but delayed metabolic response to a gastric banding-based weight loss treatment program compared with MO patients, illustrating the importance of early referral for timely intervention of MO patients.

Predicting total, abdominal, visceral and hepatic adiposity with circulating biomarkers in Caucasian and Japanese American women

Background

Characterization of abdominal and intra-abdominal fat requires imaging, and thus is not feasible in large epidemiologic studies.

Objective

We investigated whether biomarkers may complement anthropometry (body mass index [BMI], waist circumference [WC], and waist-hip ratio [WHR]) in predicting the size of the body fat compartments by analyzing blood biomarkers, including adipocytokines, insulin resistance markers, sex steroid hormones, lipids, liver enzymes and gastro-neuropeptides.

Methods

Fasting levels of 58 blood markers were analyzed in 60 healthy, Caucasian or Japanese American postmenopausal women who underwent anthropometric measurements, dual energy X-ray absorptiometry (DXA), and abdominal magnetic resonance imaging. Total, abdominal, visceral and hepatic adiposity were predicted based on anthropometry and the biomarkers using Random Forest models.

Results

Total body fat was well predicted by anthropometry alone (R² = 0.85), by the 5 best predictors from the biomarker model alone (leptin, leptin-adiponectin ratio [LAR], free estradiol, plasminogen activator inhibitor-1 [PAI1], alanine transaminase [ALT]; R² = 0.69), or by combining these 5 biomarkers with anthropometry (R² = 0.91). Abdominal adiposity (DXA trunk-to-periphery fat ratio) was better predicted by combining the two types of predictors (R² = 0.58) than by anthropometry alone (R² = 0.53) or the 5 best biomarkers alone (25(OH)-vitamin D₃, insulin-like growth factor binding protein-1 [IGFBP1], uric acid, soluble leptin receptor [sLEPR], Coenzyme Q10; R² = 0.35). Similarly, visceral fat was slightly better predicted by combining the predictors (R² = 0.68) than by anthropometry alone (R² = 0.65) or the 5 best biomarker predictors alone (leptin, C-reactive protein [CRP], LAR, lycopene, vitamin D₃; R² = 0.58). Percent liver fat was predicted better by the 5 best biomarker predictors (insulin, sex hormone binding globulin [SHBG], LAR, alpha-tocopherol, PAI1; R² = 0.42) or by combining the predictors (R² = 0.44) than by anthropometry alone (R² = 0.29).

Conclusion

The predictive ability of anthropometry for body fat distribution may be enhanced by measuring a small number of biomarkers. Studies to replicate these data in men and other ethnic groups are warranted.

Diagnosis of nonalcoholic fatty liver disease in children and adolescents: position paper of the ESPGHAN Hepatology Committee

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children and adolescents in the United States, and most probably also in the rest of the industrialized world.As the prevalence of NAFLD in childhood increases with the worldwide obesity epidemic, there is an urgent need for diagnostic standards that can be commonly used by pediatricians and hepatologists. To this end, we performed a PubMed search of the adult and pediatric literature on NAFLD diagnosis through May 2011 using Topics and/or relevant Authors as search words. According to the present literature, NAFLD is suspected based on the association of fatty liver combined with risk factors (mainly obesity), after the exclusion of other causes of liver disease. The reference but imperfect standard for confirming NAFLD is liver histology. The following surrogate markers are presently used to estimate degree of steatosis and liver fibrosis and risk of progression to end-stage liver disease: imaging by ultrasonography or magnetic resonance imaging, liver function tests, and serum markers of liver fibrosis.NAFLD should be suspected in all of the overweight or obese children and adolescents older than 3 years with increased waist circumference especially if there is a NAFLD history in relatives. The typical presentation, however, is in children ages 10 years and older. The first diagnostic step in these children should be abdominal ultrasound and liver function tests, followed by exclusion of other liver diseases. Overweight/obese children with normal ultrasonographic imaging and normal liver function tests should still be monitored due to the poor sensitivity of these tests at a single assessment.Indications for liver biopsy include the following: to rule out other treatable diseases, in cases of clinically suspected advanced liver disease, before pharmacological/surgical treatment, and as part of a structured intervention protocol or clinical research trial.

Accumulation of endoplasmic reticulum stress and lipogenesis in the liver through generational effects of high fat diets

BACKGROUND & AIMS

The dramatic rise of nonalcoholic fatty liver disease (NAFLD) among children in the past decade cannot be solely explained by the increased high fat diet (HFD) intake in kids. Recent studies suggest that the offspring of HFD-fed mothers develop a worse form of NAFLD when weaned on the HFD than when weaned on the normal chow (NC), indicating that a feed-forward circle may exacerbate the syndromes throughout multiple generations. In the present study, the aforementioned feed-forward circle was investigated in mice by employing continuous HFD feeding for three generations.

METHODS

C57BL/6 mice were fed with either a HFD or NC for three consecutive generations (F0, F1, and F2). Body weight, food intake, hepatic histology; levels of insulin, leptin, and triglycerides; expression of factors involved in lipogenesis and endoplasmic reticulum (ER) stress pathways; and histone methylation status were investigated in male offspring.

RESULTS

Obesity occurred earlier, became more severe through generations (F2>F1>F0), and was accompanied by a gradual increase of histological scoring of steatosis in male mice with transgenerational HFD feeding. The highest degree of steatosis occurred in HFD-treated F2 mice and was associated with the highest levels of insulin and leptin. The latter mice were characterized by enhanced lipogenesis and ER stress with a trend of transgenerational changes was detected for LXRα, ERO1-α, histone methylations, and H3K9 histone methyltransferase. Furthermore, chromatin immunoprecipitation (CHIP) assay demonstrated a significantly reduced accumulation of methylated histones in LXRα and ERO1-α gene promoters.

CONCLUSIONS

Under HFD feeding stress, the male offspring of the F2 generation (derived from both grand-maternal and maternal obesity) are extremely susceptible to developing obesity and hepatic steatosis. This is presumably a consequence of transgenerational accumulation of epigenetic modifications leading to up-regulation of lipogenesis and ER stress pathways in the liver.

Metabolic syndrome in childhood from impaired carbohydrate metabolism to nonalcoholic fatty liver disease

Compelling evidence supports the concept that nonalcoholic fatty liver disease (NAFLD) represents the hepatic component of metabolic syndrome (MetS). Intrahepatic fat seems to predict more strongly than does visceral adiposity an individual's cardiovascular risk and the likelihood that metabolic abnormalities are present in youth. Young individuals with fatty liver are more insulin resistant and present with a higher prevalence of metabolic abnormalities than do individuals without intrahepatic fat accumulation. They also present with a certain endothelial dysfunction and greater carotid intima-media thickness. Conversely, youth with MetS seem to have an increased risk of developing liver inflammation, a condition termed nonalcoholic steatohepatitis (NASH), and fibrosis. In the context of MetS, the liver is central in that it can drive both hepatic and systemic insulin resistance, trigger low-grade inflammation, and promote atherogenic processes. In the context of MetS, NAFLD and altered carbohydrate metabolism track from childhood to adulthood. Thus, prevention, recognition, and effective treatment of these two abnormalities may limit the burden of morbidity and mortality associated with obesity and may delay onset of cardiovascular disease in early adulthood. The present review aims at systematically presenting evidence of the critical interplay of fatty liver and altered glucose metabolism in youth. It attempts to provide pathogenetic explanations for such an association and the rationale for its treatment, with particular regard to nutritional interventions. Key teaching points: Overweight and obese youth should be screened for fatty liver disease once after puberty by liver function tests and ultrasonography. Screening for fatty liver should be accurately performed in young patients with features of metabolic syndrome. Obese patients with fatty liver are at increased risk for altered glucose metabolism, thus they should undergo an oral glucose tolerance test. A nutritional and behavioral intervention aimed at achieving a permanent change of the lifestyle in patients and their parents is recommended.

Non-alcoholic fatty liver disease and metabolic syndrome in adolescents: pathogenetic role of genetic background and intrauterine environment

In the last three decades the incidence of metabolic syndrome (MetS) has been growing worldwide along with an increase of obesity, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). In children and adolescents such epidemics are particularly worrisome, since the metabolic consequences in adulthood will significantly burden the health care system. Although the definition of MetS in childhood is still controversial, there is agreement with respect to NAFLD being the hepatic manifestation of MetS. However, the molecular pathogenesis of MetS and its contribution to NAFLD is complex and closely related to the pre- and postnatal environment as well as to genetic predisposing factors. The analysis of the possible relationships between NAFLD and MetS is particularly interesting, not only from an epidemiological point of view, but also to better understand the genetic and environmental factors contributing to the development of both diseases. We here summarize the most recent epidemiological data on the incidence of both diseases in adolescents, and several aspects linking MetS with NAFLD, discussing the possible role played by genetics and intrauterine environment.

Inhibitory effects of garcinol and pterostilbene on cell proliferation and adipogenesis in 3T3-L1 cells

The aim of this work was to study the effects of garcinol and pterostilbene on cell proliferation and adipogenesis in 3T3-L1 cells. The results showed that garcinol and pterostilbene decreased the cell population growth and caused cell cycle arrest at the G2/M phase in 3T3-L1 preadipocytes. During adipocyte differentiation, both garcinol and pterostilbene had inhibitory effects on fat droplet formation and triacylglycerol accumulation. The data indicated that garcinol and pterostilbene could inhibit the glycerol-3-phosphate dehydrogenase (GPDH) activity by 97.8 and 61.5%, respectively, as compared to the control. Both garcinol and pterostilbene significantly attenuated the protein expressions of PPARγ and C/EBPα during 3T3-L1 adipocyte differentiation. Moreover, garcinol and pterostilbene caused an inhibition of lipid accumulation in the 3T3-L1 adipocyte differentiation phase. Garcinol and pterostilbene also significantly up-regulated the gene expression of adiponectin as well as down-regulated the gene expressions of leptin, resistin, and fatty acid synthase (FAS) in 3T3-L1 adipocyte differentiation. In 3T3-L1 adipocytes, garcinol significantly down-regulated the protein expressions of PPARγ and FAS as well as up-regulated the protein expressions of adipose triglyceride lipase (ATGL) and adiponectin. Garcinol also significantly up-regulated the gene expression of adiponectin as well as down-regulated the gene expressions of leptin and FAS. These results suggest that garcinol and pterostilbene have anti-adipogenic effects on preadipocytes and adipocytes.

Correlation of insulin sensitivity with bone mineral status in obese adolescents with nonalcoholic fatty liver disease

AIM

The aim of this study was to investigate the relationships between bone mineral density (BMD) vs insulin resistance and metabolic risk factors in obese adolescents with nonalcoholic fatty liver disease (NAFLD).

PATIENTS AND METHODS

Eighty-two obese adolescents [45 girls and 37 boys, mean age: 12·3 ± 1·7 years, mean body mass index-standard deviation score (BMI-SDS): 1·9 ± 0·2] and 30 control subjects (15 girls and 15 boys, mean age: 12·3 ± 1·45 years, mean BMI-SDS: 0·5 ± 0·7) were enrolled the study. The obese subjects were divided into two groups based on the presence or absence of liver steatosis with high transaminases (NAFLD group and non-NAFLD group). Insulin resistance was evaluated by homeostasis model assessment (HOMA-IR) from fasting samples. BMD was determined by dual-energy X-ray absorptiometry.

RESULTS

Fasting insulin levels in the NAFLD group were significantly higher than in the non-NAFLD obese (32·3 ± 24·0 vs 11·02 ± 2·95 mU/l, P < 0·001) and control groups (8·4 ± 2·4 mU/l, P< 0·001). The NAFLD group had higher values of HOMA-IR than the non-NAFLD obese (7·3 ± 0·1 vs 2·3 ± 0·7, P < 0·001) and control groups (1·8 ± 0·5, P < 0·001). BMD-SDS measurements were lower in the NAFLD group than in the non-NAFLD (0·56 ± 0·3 vs 1·02 ± 0·9, P < 0·001) and control groups (0·56 ± 0·3 vs 1·37 ± 1·04, P < 0·001). BMD-SDS was positively correlated with BMI-SDS (r = 0·530, P = 0·004) and negatively correlated with HOMA-IR (r = -0·628, P = 0·017) in the NAFLD obese group.

CONCLUSION

This study reports the association between BMD-SDS and insulin resistance in obese adolescents both with and without NAFLD, although the NAFLD group had a lower BMD-SDS than the non-NAFLD group. We suggest that NAFLD has a detrimental effect on bone health in adolescents, and it is correlated with increased insulin resistance.

The changing face of hepatitis in boys with haemophilia associated with increased prevalence of obesity

Hepatitis in children with haemophilia was historically most often associated with transfusion-transmitted infections. However, with the use of recombinant clotting factor concentrates, acquisition of such infections has now become rare. We studied the profile of hepatitis in North-American children with haemophilia in the modern era of safe blood products and excess childhood obesity. A total of 173 boys (<18 years) registered in the Pediatric Comprehensive Care Haemophilia Program were included in this retrospective study. Hospital records were reviewed for baseline data, serial height and weight measurements and serial alanine aminotransferase (ALT) levels. A body mass index (BMI) ranking was available for 170 boys, of whom 25 (14.7%, 95% CI 9.7-20.9%) were obese. The rate of obesity was higher in severe haemophilic boys. Compared with the general childhood population, the rate of obesity trended towards being higher in young haemophilic boys (2-5 years), but was similar in other age groups. A persistently high ALT (≥80 U L(-1) ) was documented in 5 boys and was associated with obesity. Three boys had clinical and imaging studies compatible with non-alcoholic fatty liver disease (NAFLD). Overweight and obesity are common among haemophilic boys, especially those who are younger and with severe disease. In this large group of haemophilic boys, chronic viral hepatitis was rare and NAFLD was a more common cause of liver disease. Overweight and obese haemophilic boys should be evaluated for NAFLD and interventional programmes should be designed to reduce the potential complications associated with obesity.

Macrophage activation is responsible for loss of anticontractile function in inflamed perivascular fat

OBJECTIVE

The aim of this study was to determine whether macrophages dispersed throughout perivascular fat are crucial to the loss of anticontractile function when healthy adipose tissue becomes inflamed and to gain an understanding of the mechanisms involved.

METHODS AND RESULTS

Pharmacological studies on in vitro small arterial segments from a mouse model of inducible macrophage ablation and on wild-type animals were carried out with and without perivascular fat using 2 physiological stimuli of inflammation: aldosterone and hypoxia. Both inflammatory insults caused a similar loss of anticontractile capacity of perivascular fat and increased macrophage activation. Aldosterone receptor antagonism and free radical scavengers were able to restore this capacity and reduce macrophage activation. However, in a mouse deficient of macrophages CD11b-diptheria toxin receptor (CD11b-DTR), there was no increase in contractility of arteries following aldosterone incubation or hypoxia.

CONCLUSIONS

The presence and activation of macrophages in adipose tissue is the key modulator of the increase in contractility in arteries with perivascular fat following induction of inflammation. Despite multiple factors that may be involved in bringing about the vascular consequences of obesity, the ability of eplerenone to ameliorate the inflammatory effects of both aldosterone and hypoxia may be of potential therapeutic interest.

The potential adverse role of leptin resistance in nonalcoholic fatty liver disease: a hypothesis based on critical review of the literature

BACKGROUND

Leptin is an adipocyte-derived hormone that plays a crucial role in energy homeostasis and lipid metabolism. Most of the biological effects of leptin are exerted through activation of the Janus kinase-2/signal transducer and activator of transcription-3 pathway. Signal transducer and activator of transcription-3 activation ultimately leads to an increased transcription and expression of suppressors of cytokine signaling-3, which acts as a feedback inhibitor by attenuating leptin signaling. Apart from inhibiting leptin signaling, suppressor of cytokine signaling-3 inhibits insulin signaling. Leptin increases with increasing fatty mass as a compensatory mechanism to preserve insulin sensitivity, but persistent hyperleptinemia is implicated in liver fibrinogenesis and carcinogenesis.

HYPOTHESIS

Considering this dual role of leptin in the liver pathophysiology, we hypothesized that leptin resistance may vary according to the different types of liver cells and nonalcoholic fatty liver disease progression.

CLINICAL CONSEQUENCES

It is speculated that recombinant leptin, proposed to be used in common forms of obesity or nonalcoholic fatty liver disease, might have serious unfavorable therapeutical drawbacks, through promotion of insulin resistance, fibrosis, and hepatocellular carcinoma.

[Nonalcoholic fatty liver disease in a severely obese adolescent. An arguable liver biopsy]

The growing epidemic of juvenile obesity has prompted pediatricians to investigate obesity-related conditions in obese teenagers. We report a clinical case of severe hepatic fibrosis in an adolescent with severe and recent obesity. Because of elevated serum aminotransferase levels, abnormal hepatic ultrasonography and insulin resistance (impaired glucose tolerance), we suspected nonalcoholic steatohepatitis (NASH). Disease activity and fibrosis were confirmed on liver biopsy. Considering the risk of progression toward cirrhosis and its complications, and the pathological liver lesions, we started long-term medical monitoring and drug therapy to control weight loss. At present, although biopsy is the only validated way to establish the diagnosis of NASH, there is no consensus on its indication when NASH is suspected. Noninvasive strategies are attractive but require validation in children.

Increased soluble leptin receptor levels in morbidly obese patients with insulin resistance and nonalcoholic fatty liver disease

The adipocyte hormone, leptin has been demonstrated to have profibrogenic actions in vitro and in animal models. However, no correlation was found between plasma leptin levels and fibrosis stage in humans. Thus, our aim was to study whether soluble leptin receptor (SLR) or free leptin index (FLI; calculated as the ratio of leptin to SLR), may correlate better with the features of metabolic syndrome and with the histological grade and stage of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). We studied a population (n = 104) of morbidly obese patients undergoing bariatric surgery. Data including BMI, type 2 diabetes mellitus, hypertension, and hyperlipidemia were obtained. Plasma fasting leptin and SLR, fasting glucose and insulin were measured, and homeostasis model of assessment insulin resistance (HOMA(IR)) index and FLI were calculated. All patients had intraoperative liver biopsies. Leptin levels correlated with the BMI. The multiple regression analysis indicated that increasing HOMA and decreasing FLI were predictors of steatosis in the liver (P < 0.0003). SLR levels were positively correlated with the presence of diabetes mellitus and the stage of fibrosis. In conclusion, increased SLR levels in morbidly obese patients with diabetes are correlated with the stage of liver fibrosis, and may reflect progressive liver disease.

Leptin induces an inflammatory phenotype in lean Wistar rats

The present study addressed the hypothesis that leptin promotes leukocyte trafficking into adipose tissue. Accordingly, male Wistar rats were treated with saline or recombinant rat leptin (1 mg/kg) via the tail vein. Leukocyte trafficking in mesenteric venules was quantified by intravital microscopy. Treatment with leptin resulted in a 3- and 5-fold increases in rolling and firm adhesion, respectively. Compared to vehicle controls, leptin enhanced mRNA levels of IL-6 (8-fold) and MCP-1 (5-fold) in mesenteric adipose tissue (MAT). Similar increases in these markers were observed in mesenteric venules and in liver. Finally, the direct effect of leptin was assessed in C3A hepatocytes treated with leptin for 24 hours (7.8 ng/mL–125 ng/mL). Consistent with observations in vivo, production of ICAM-1, MCP-1, and IL-6 by hepatocytes was increased significantly. These findings support the hypothesis that leptin directly initiates inflammation in the local environment of mesenteric adipose tissue as well as systemically.