Metabolic syndrome and liver histology in paediatric non-alcoholic steatohepatitis

Genetic predisposition in NAFLD and NASH: impact on severity of liver disease and response to treatment

Liver fat deposition related to systemic insulin resistance defines non-alcoholic fatty liver disease (NAFLD) which, when associated with oxidative hepatocellular damage, inflammation, and activation of fibrogenesis, i.e. non-alcoholic steatohepatitis (NASH), can progress towards cirrhosis and hepatocellular carcinoma. Due to the epidemic of obesity, NAFLD is now the most frequent liver disease and the leading cause of altered liver enzymes in Western countries. Epidemiological, familial, and twin studies provide evidence for an element of heritability of NAFLD. Genetic modifiers of disease severity and progression have been identified through genome-wide association studies. These include the Patatin-like phosholipase domain-containing 3 (PNPLA3) gene variant I148M as a major determinant of inter-individual and ethnicity-related differences in hepatic fat content independent of insulin resistance and serum lipid concentration. Association studies confirm that the I148M polymorphism is also a strong modifier of NASH and progressive hepatic injury. Furthermore, a few large multicentre case-control studies have demonstrated a role for genetic variants implicated in insulin signalling, oxidative stress, and fibrogenesis in the progression of NAFLD towards fibrosing NASH, and confirm that hepatocellular fat accumulation and insulin resistance are key operative mechanisms closely involved in the progression of liver damage. It is now important to explore the molecular mechanisms underlying these associations between gene variants and progressive liver disease, and to evaluate their impact on the response to available therapies. It is hoped that this knowledge will offer further insights into pathogenesis, suggest novel therapeutic targets, and could help guide physicians towards individualised therapy that improves clinical outcome.

Developmental programming of pediatric nonalcoholic fatty liver disease: redefining the"first hit"

The incidence of pediatric nonalcoholic fatty liver disease has increased dramatically, and growing evidence indicates that the pathophysiology may be unique from the adult form, suggesting a role for early-life events. Recent radiologic techniques have now demonstrated that maternal obesity contributes to hepatic fat storage in newborn infants. In this review, we will explore how maternal obesity and a hyperlipidemic environment can initiate liver histopathogenesis in utero, including steatosis, mitochondrial dysfunction, oxidative stress, and inflammatory priming. Thus, early exposure to excess lipids may represent the "first hit" for the fetal liver, placing it on a trajectory toward future metabolic disease.

A 360-degree overview of paediatric NAFLD: recent insights

Non-alcoholic fatty liver disease (NAFLD) is a multi-faceted disorder, which ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) with/without fibrosis. The effects of specific risk factors, such as obesity and sedentary lifestyle, on predisposing genetic settings eventually lead to the development of NAFLD in children. The complex interplay between genes and environment in NAFLD pathogenesis is sustained by multiple mechanisms that involve liver crosstalk with other organs and tissues, especially gut and adipose tissue. Unfortunately, natural history of paediatric NAFLD is lacking, and the etiopathogenesis is still in the process of being defined. Potential early predictors and suitable non-invasive diagnostic tools can be discovered based on the pathogenetic mechanisms and histological patterns. This will also help design novel treatments and a comprehensive and successful management strategy for patients. In this review, we discuss the recent advances made in genetics, etiopathogenesis, diagnosis, and therapeutic management of NAFLD, focusing especially on the obesity-related steatotic liver condition.

The effect of weight loss on pediatric nonalcoholic Fatty liver disease

This study evaluated the effect of weight loss on pediatric nonalcoholic fatty liver disease (NAFLD). Subjects included 81 overweight NAFLD patients referred to two pediatric gastroenterologists from 2000 to 2010. Data on subjects were obtained from review of medical charts. The effect of weight loss was assessed at 1–4 months, 5–8 months, 9–12 months, and beyond one year as the change in weight, BMI z-score (for age-and-sex), and alanine aminotransferase and the relationship between the change in body weight and BMI z-score, and the change in alanine aminotransferase. Subjects were mostly obese (99%), male (86%), and Asian (63%) and had median age of 14.1 (11.2–16.2) years and alanine aminotransferase of 105 (78–153) U/L at referral. Alanine aminotransferase decreased 32 ± 66 (P = 0.016), 30 ± 65 (P = 0.134), 37 ± 75 (P = 0.0157), and 45 ± 69 (P = 0.014) for subjects with follow-up data at 1–4 months (n = 47), 5–8 months (n = 26), 9–12 months (n = 19), and beyond one year (n = 19), respectively. During these time periods, neither was body weight (−0.2 to +7.1 kg) or BMI z-score (−0.12 to −0.05) significantly reduced, nor were changes in these variables associated with the change in alanine aminotransferase. These findings suggest that weight and BMI z-score may not be sufficient indicators of treatment response in pediatric NAFLD patients.

Pediatric non alcoholic fatty liver disease: old and new concepts on development, progression, metabolic insight and potential treatment targets

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. NAFLD has emerged to be extremely prevalent, and predicted by obesity and male gender. It is defined by hepatic fat infiltration >5% hepatocytes, in the absence of other causes of liver pathology. It includes a spectrum of disease ranging from intrahepatic fat accumulation (steatosis) to various degrees of necrotic inflammation and fibrosis (non-alcoholic steatohepatatis [NASH]). NAFLD is associated, in children as in adults, with severe metabolic impairments, determining an increased risk of developing the metabolic syndrome. It can evolve to cirrhosis and hepatocellular carcinoma, with the consequent need for liver transplantation. Both genetic and environmental factors seem to be involved in the development and progression of the disease, but its physiopathology is not yet entirely clear. In view of this mounting epidemic phenomenon involving the youth, the study of NAFLD should be a priority for all health care systems. This review provides an overview of current and new clinical-histological concepts of pediatric NAFLD, going through possible implications into patho-physiolocical and therapeutic perspectives.

Paediatric non-alcoholic Fatty liver disease: impact on patients and mothers' quality of life

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the causes of fatty liver in adults and is currently the primary form of chronic liver disease in children and adolescents. However, the psychological outcome (i.e. the behavioural problems that can in turn be related to psychiatric conditions, like anxiety and mood disorders, or lower quality of life) in children and adolescents suffering of NAFLD has not been extensively explored in the literature.

OBJECTIVES

The present study aims at evaluating the emotional and behavioural profile in children suffering from NAFLD and the quality of life in their mothers.

PATIENTS AND METHODS

A total of 57 children (18 females/39 males) with NAFLD were compared to 39 age-matched control children (25 females/14 males). All participants were submitted to the following psychological tools to assess behavior, mood, and anxiety: the Multidimensional Anxiety Scale for Children (MASC), the Child Behavior Checklist (CBCL), and the Children's Depression Inventory (CDI). Moreover, the mothers of 40 NAFLD and 39 control children completed the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire.

RESULTS

NAFLD children scored significantly higher as compared to control children in MASC (P = 0.001) and CDI total (P < 0.001) scales. The CBCL also revealed significantly higher scores for NAFLD children in total problems (P = 0.046), internalizing symptoms (P = 0.000) and somatic complaints (P < 0.001). The WHOQOL-BREF revealed significantly lower scores for the mothers of NAFLD children in the overall perception of the quality of life (P < 0.001), and in the "relationships" domain (P = 0.023).

CONCLUSIONS

Increased emotional and behavioural problems were detected in children with NAFLD as compared to healthy control children, together with an overall decrease in their mothers' quality of life. These results support the idea that these patients may benefit from a psychological intervention, ideally involving both children and parents, whose quality of life is likely negatively affected by this disease.

Fatty liver is a good indicator of subclinical atherosclerosis risk in obese children and adolescents regardless of liver enzyme elevation

AIM

To investigate the presence of association between nonalcoholic fatty liver disease (NAFLD) and subclinical atherosclerosis using carotid intima media thickness (c-IMT) in obese children and adolescents. Additionally, we wished to investigate the relationship between fatty liver and elevated liver enzymes.

METHODS

A total of 157 obese patients (78 boys and 79 girls, mean age: 11.3 ± 2.6 years, age range: 6-16 years) were enrolled in the study. Aminotransferase, fasting glucose and lipid levels were determined. An oral glucose tolerance test was performed. The c-IMT was measured. Infectious and metabolic causes of elevated liver enzymes were excluded. The diagnosis of NAFLD was based on ultrasound scan.

RESULTS

Obese patients with NAFLD had markedly increased carotid IMT (mean: 0.48 mm, 95% CI: 0.47-0.49) than those without NAFLD (mean: 0.45 mm 95% CI: 0.44-0.45, p < 0.001). The presence of NAFLD significantly increased c-IMT whether the patient had elevated liver enzyme or not (ANOVA, p < 0.001). In a multiple-regression model, only the presence of NAFLD was associated with increased c-IMT (β = 0.031, SE (β) = 0.008, p < 0.001).

CONCLUSION

Obese children and adolescents with NAFLD are at risk of early atherosclerotic changes. As liver function tests are not sufficient to identify patients with fatty liver, ultrasonographic evaluation of NAFLD might be considered in all obese children and adolescents.

The efficacy of pharmacological treatment in pediatric nonalcoholic Fatty liver disease

PURPOSE

With growing number of obese children, the prevalence of nonalcoholic fatty liver disease (NAFLD) in pediatric population is increasing. Nonalcoholic steatohepatitis (NASH) is a severe form of NAFLD, and can cause morbid complications. It is important to identify patients in order to grade pathologic severities and treat those children who possibly have NASH. This study was performed to evaluate whether the pharmacological therapy is also effective as well as the body weight reduction in pediatric NAFLD.

METHODS

Among the 52 children presenting with obesity and hepatopathy, NAFLD was diagnosed through liver biopsy in 29 children, who were 7 to 14 years of age, from January 2006 to December 2011. The patients were advised to reduce their body weight through diverse methods. Medication with Ursodeoxycholic acid (UDCA) and vitamin E was performed in children whose liver functions did not improve or their weight reductions were not successful. The therapeutic effects were monitored and assessed via the biochemical profiles and the physical measurements.

RESULTS

The therapy of vitamin E and UDCA combined with body mass index (BMI) reduction showed significantly higher rate of improvement in clinical profiles, which could be seen in data of aspartate aminotransferase (AST), alanine aminotransferase (ALT), AST/ALT ratio, alkaline phosphatase, total bilirubin and γ-glutamyl transpeptidase. Children whose BMI were successfully reduced showed favorable clinical improvements without any medication, but those without BMI reduction did not show any improvement despite medications.

CONCLUSION

This study showed that the first line of therapy should be the BMI reduction in NAFLD and drug therapy combined with BMI reduction could have additive therapeutic effect in children with NAFLD.

Cannabinoid receptor type 2 functional variant influences liver damage in children with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) comprises a spectrum of disease ranging from simple steatosis to inflammatory steatohepatitis (NASH) with different degrees of fibrosis that can ultimately progress to cirrhosis. Accumulating evidence suggests the involvement of the endocannabinoid-system in liver disease and related complications. In particular, hepatoprotective properties for Cannabinoid Receptor type 2 (CB2) have been shown both through experimental murine models of liver injury and association study between a CB2 functional variant, Q63R, and liver enzymes in Italian obese children with steatosis.

Here, in order to clarify the role of CB2 in severity of childhood NAFLD, we have investigated the association of the CB2 Q63R variant, with histological parameters of liver disease severity in 118 Italian children with histologically-proven NAFLD.

CB2 Q63R genotype was assigned performing a TaqMan assay and a general linear model analysis was used to evaluate the association between the polymorphism and the histological parameters of liver damage.

We have found that whereas CB2 Q63R variant is not associated with steatosis or fibrosis, it is associated with the severity of the inflammation (p = 0.002) and the presence of NASH (p = 0.02).

Our findings suggest a critical role for CB2 Q63R variant in modulating hepatic inflammation state in obese children and in the consequent increased predisposition of these patients to liver damage.

Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude

AIM: To use leptin-deficient (ob/ob) mice with demonstrated differences in steatosis levels to test a new diagnostic method using the acoustical structure quantification (ASQ) mode and the associated analytical parameter, “focal disturbance ratio” (FD-ratio).

METHODS: Nine ob/ob mice, at 5, 8, and 12 wk of age (n = 3 in each age group), were used as models for hepatic steatosis. Echo signals obtained from ultrasonography in the mice were analyzed by ASQ, which uses a statistical analysis of echo amplitude to estimate inhomogeneity in the diagnostic region. FD-ratio, as calculated from this analysis, was the focus of the present study. FD-ratio and fat droplet areas and sizes were compared between age groups.

RESULTS: No fibrosis or inflammation was observed in any of the groups. The fat droplet area significantly (P < 0.01) increased with age from 1.25% ± 0.28% at 5 wk to 31.07% ± 0.48% at 8 wk to 51.69% ± 3.19% at 12 wk. The median fat droplet size also significantly (P < 0.01) increased with age, from 1.33 (0.55-10.52) μm at 5 wk, 2.82 (0.61-44.13) μm at 8 wk and 6.34 (0.66-81.83) μm at 12 wk. The mean FD-ratio was 0.42 ± 0.11 at 5 wk, 0.11 ± 0.05 at 8 wk, and 0.03 ± 0.02 at 12 wk. The FD-ratio was significantly lower at 12 wk than at 5 wk and 8 wk (P < 0.01). A significant negative correlation was observed between the FD-ratio and either the fat droplet area (r = -0.7211, P = 0.0017) or fat droplet size (r = -0.9811, P = 0.0052).

CONCLUSION: This tool for statistical analysis of signals from ultrasonography using the FD-ratio can be used to accurately quantify fat in vivo in an animal model of hepatic steatosis, and may serve as a quantitative biomarker of hepatic steatosis.

Potential clinical translation of juvenile rodent inactivity models to study the onset of childhood obesity

According to the latest data from the Center for Disease Control and Prevention 17%, or 12.5 million, of children and adolescents aged 2-19 years in the United States are obese. Physical inactivity is designated as one of the actual causes of US deaths and undoubtedly contributes to the obesity epidemic in children and adults. Examining the effects of inactivity on physiological homeostasis during youth is crucial given that 58% of children between the ages 6-11 yr old fail to obtain the recommended 60 min/day of physical activity and 92% of adolescents fail to achieve this goal [Troiano et al. Med Sci Sports Exerc. 40, 2008]. Nonetheless, invasive mechanistic studies in children linking diminished physical activity with metabolic maladies are lacking for obvious ethical reasons. The rodent wheel lock (WL) model was adopted by our laboratory and others to study how different organ systems of juvenile rats respond to a cessation of daily physical activity. Our WL model houses rats in cages equipped with voluntary running wheels starting at 28 days of age. After a certain period of voluntary running (3 to 6 wk), the wheels are locked, thus preventing the rats' primary source of physical activity. The studies discussed herein suggest that obesity-associated maladies including skeletal muscle insulin resistance, hypothalamic leptin resistance, fatty acid oxidation impairments in skeletal muscle and adipose tissue, nonalcoholic fatty liver disease, and endothelial dysfunction are initiated in juvenile animals that are restrained from voluntary exercise via WL. The use of the juvenile rodent WL or other inactivity models will continue to provide a powerful clinical translational tool that can be used for primordial prevention of human childhood obesity.

Children with NAFLD are more sensitive to the adverse metabolic effects of fructose beverages than children without NAFLD

CONTEXT

Dietary fructose induces unfavorable lipid alterations in animal models and adult studies. Little is known regarding metabolic tolerance of dietary fructose in children.

OBJECTIVES

The aim of the study was to evaluate whether dietary fructose alters plasma lipids in children with nonalcoholic fatty liver disease (NAFLD) and in healthy children.

DESIGN AND SETTING

We performed a 2-d, crossover feeding study at the Inpatient Clinical Interaction Site of the Atlanta Clinical and Translational Science Institute at Emory University Hospital.

PARTICIPANTS AND INTERVENTION

Nine children with NAFLD and 10 matched controls without NAFLD completed the study. We assessed plasma lipid levels over two nonconsecutive, randomly assigned, 24-h periods under isocaloric, isonitrogenous conditions with three macronutrient-balanced, consecutive meals and either: 1) a fructose-sweetened beverage (FB); or 2) a glucose beverage (GB) being consumed with each meal.

MAIN OUTCOME MEASURES

Differences in plasma glucose, insulin, triglyceride, apolipoprotein B, high-density lipoprotein cholesterol, and nonesterified free fatty acid levels were assessed using mixed models and 24-h incremental areas under the time-concentration curve.

RESULTS

After FB, triglyceride incremental area under the curve was higher vs. after GB both in children with NAFLD (P = 0.011) and those without NAFLD (P = 0.027); however, incremental response to FB was greater in children with NAFLD than those without NAFLD (P = 0.019). For all subjects, high-density lipoprotein cholesterol declined in the postprandial and overnight hours with FB, but not with GB (P = 0.0006). Nonesterified fatty acids were not impacted by sugar but were significantly higher in NAFLD.

CONCLUSIONS

The dyslipidemic effect of dietary fructose occurred in both healthy children and those with NAFLD; however, children with NAFLD demonstrated increased sensitivity to the impact of dietary fructose.

Increased pancreatic fat fraction is present in obese adolescents with metabolic syndrome

OBJECTIVES

Little is known about pancreatic fat accumulation and its possible associations with metabolic syndrome (MetS) and glucose metabolism. The aim of the present study was to quantify pancreatic fat fraction (PFF) in lean and obese adolescents and explore its relation to metabolic parameters.

METHODS

We recruited 25 lean and 24 obese adolescents. PFF and visceral adipose tissue (VAT) were determined using magnetic resonance imaging. We measured blood pressure, fasting glucose, insulin, liver enzymes, leptin, and lipid levels. Obese subjects underwent an oral glucose tolerance test.

RESULTS

PFF was significantly higher in obese than in lean subjects (4.8±1.2 vs 3.6±0.9; P<0.001) and was associated with VAT, γ-glutamyltransferase, triglycerides, high-density lipoprotein cholesterol, leptin concentrations, and MetS (P<0.05 for all). None of the obese subjects had glucose intolerance, but when adjusted for VAT, the following 3 parameters correlated negatively with PFF: fasting and 30- minute and 120-minute insulin levels. We divided subjects into 3 groups: group I, lean without MetS; group II, obese without MetS; and group III, obese with MetS, and observed that PFF increased gradually among groups (I: 3.56%±0.88%; II: 4.70%±1.06%; III: 5.34%±1.49%; P<0.001).

CONCLUSIONS

Obese adolescents accumulate fat in the pancreas. PFF correlates with the presence of MetS. Even in the absence of glucose intolerance, pancreatic fat deposition is associated with impaired insulin response to glucose overload. This suggests that β-cell dysfunction may already be present in nondiabetic obese adolescents, mirroring what has been shown in adults, and that pancreatic fat accumulation may participate in obesity-associated pancreatic endocrine dysfunction.

LPIN1 rs13412852 polymorphism in pediatric nonalcoholic fatty liver disease

OBJECTIVES

The aim of the present study was to evaluate whether the lipin1 rs13412852 C>T polymorphism is associated with nonalcoholic steatohepatitis and fibrosis in pediatric Italian patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 142 untreated, consecutive children and 115 adults with biopsy-proven NAFLD and 337 healthy controls without steatosis were studied. Liver histology was assessed by the NAFLD activity score and the rs13412852 polymorphism by a 5' nuclease Taqman assay.

RESULTS

Homozygosity for the rs13412852 T allele was underrepresented in pediatric, but not adult, patients with NAFLD compared with healthy controls (7% vs 14%; odds ratio [OR] 0.58, 95% confidence interval [CI] 0.35-0.91), and it was associated with lower triglycerides both in pediatric patients and healthy controls (P ≤ 0.01). Affected children carrying the rs13412852 TT genotype had a trend for a lower prevalence of nonalcoholic steatohepatitis, and significantly less severe liver damage, as indicated by NAFLD activity score severity (P = 0.026) and a lower prevalence of liver fibrosis (P = 0.012). The negative association between rs13412852 TT genotype and fibrosis was independent of Patatin-like phospholipase domain-containing-3 genotype and other clinical risk factors, including age, waist circumference, the presence of hyperglycemia, and alanine transaminase levels (OR 0.29; 95% CI 0.11-0.66), and it was confirmed at multivariate analysis in adults (OR 0.15; 95% CI 0.02-0.67).

CONCLUSIONS

Lipin1 rs13412852 single nucleotide polymorphism is associated with the severity of liver damage and fibrosis progression in pediatric patients with histological NAFLD.

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.

Effect of a 10-week weight loss camp on fatty liver disease and insulin sensitivity in obese Danish children

BACKGROUND AND OBJECTIVE

Childhood nonalcoholic fatty liver disease (NAFLD) associated with insulin resistance and obesity is a growing problem and increases the risk of cirrhosis, type 2 diabetes mellitus, and cardiovascular complications. We examined the effects of a 10-week "weight loss camp" residency in obese children on the prevalence and degree of NAFLD and insulin sensitivity with 12-month follow-up.

METHODS

At the camp, 117 obese white children (body mass index 28.0 ± 3.6  kg/m, age 12.1 ± 1.3 years) exercised moderately for 1 hour/day and restricted their energy intake to induce weight loss. NAFLD was diagnosed and graded using ultrasound and transaminasemia. Insulin sensitivity and glucose tolerance were assessed using homeostasis model assessment and oral glucose tolerance test. We performed anthropometric measurements and determined body composition using bioimpedance. Data were collected from 71 of 117 children at entry, after the 10 weeks at the camp, and 12 months after the camp ended.

RESULTS

The children showed an average weight loss of 7.1 ± 2.7  kg during the camp. At baseline, 43% had ultrasonographic liver steatosis, 50% elevated transaminases (>25  IU/L), and reduced insulin sensitivity. These abnormalities were mutually related and improved significantly during the camp (P ≤ 0.05). Liver fat improvement was sustained at 12 months. At the 12-month follow-up, 17 of 71 (24%) children maintained the body weight.

CONCLUSIONS

This short-term diet and exercise program induced weight loss, markedly improved all aspects of the threatening condition of NAFLD, and reduced insulin sensitivity in childhood obesity; 24% of the children maintained weight loss at least until the 12-month follow-up.

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.

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.

Non-alcoholic fatty liver disease impairs hippocampal-dependent memory in male rats

Non-alcoholic fatty liver disease (NAFLD) is a disorder observed in children and adults characterized by an accumulation of liver fat (>5% wet weight) in the absence of excessive alcohol intake. NAFLD affects 10 to 30% of the American population and is the most common cause of liver disease in the United States. NAFLD leads to serious disturbances in cardiovascular and hormonal function; however, possible effects on brain function have been overlooked. The aims of the present study were to test whether diet-induced NAFLD impairs hippocampal-dependent memory and to determine whether any observed deficits are associated with changes in hippocampal insulin signaling or concentrations of brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1). Post-weanling male Sprague-Dawley rats were fed a high fructose (60% of calories) or control diet for 12 weeks and then trained and tested in a spatial water maze. NAFLD was confirmed with postmortem measures of liver mass and liver lipid concentrations. NAFLD did not affect acquisition of the spatial water maze, but did impair retention tested 48 h later. Specifically, both groups demonstrated similar decreases in latency to swim to the escape platform over training trials, but on the memory test NAFLD rats took longer to reach the platform and made fewer visits to the platform location than control diet rats. There were no differences between the groups in terms of insulin-stimulated phosphorylation of insulin receptor β subunit (IR-β) and protein kinase B (PKB/AKT) in hippocampal slices or hippocampal BDNF or IGF-1 concentrations. Thus, these data indicate that NAFLD impairs hippocampal-dependent memory function and that the deficit does not appear attributable to alterations in hippocampal insulin signaling or hippocampal BDNF or IGF-1 concentrations.

The association of metabolic syndrome, insulin resistance and non-alcoholic fatty liver disease in overweight/obese children

BACKGROUND/AIM

To study the prevalence of metabolic syndrome (MS), insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD) in overweight/obese children with clinical hepatomegaly and/or raised alanine aminotransferase (ALT).

PATIENTS AND METHODS

Thirty-three overweight and obese children, aged 2-13 years, presenting with hepatomegaly and/or raised ALT, were studied for the prevalence of MS, IR and NAFLD. Laboratory analysis included fasting blood glucose, serum insulin, serum triglycerides (TG), total cholesterol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c) and liver biochemical profile, in addition to liver ultrasound and liver biopsy.

RESULTS

Twenty patients (60.6%) were labeled with MS. IR was present in 16 (48.4%). Fifteen (44%) patients had biopsy-proven NAFLD. Patients with MS were more likely to have NAFLD by biopsy (P=0.001). Children with NAFLD had significantly higher body mass index, waist circumference, ALT, total cholesterol, LDL-c, TG, fasting insulin, and lower HDL-c compared to patients with normal liver histology (P< 0.05) and fitted more with the criteria of MS (80% vs. 44%). IR was significantly more common among NAFLD patients (73% vs. 28%).

CONCLUSION

There is a close association between obesity, MS, IR and NAFLD. Obese children with clinical or biochemical hepatic abnormalities are prone to suffer from MS, IR and NAFLD.

Advances in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of pediatric liver disease in the developed world. Children have a form of NAFLD that is pathologically distinct from adults. Although NAFLD remains a pathologic diagnosis, biomarkers and imaging studies hold promise as noninvasive means of both establishing the diagnosis and following the disease course. Significant advancements have recently been made in genetics, pathophysiology, and the treatment of NAFLD. The purpose of this article is to provide a clinically relevant review of pediatric NAFLD with an emphasis on recent developments in the field.

Biochemical parameters and anthropometry predict NAFLD in obese children

The aim of the present study was to build a predictive model of nonalcoholic fatty liver disease (NAFLD) in obese children. Fifty-six obese 10-year-old children underwent blood tests for biochemical measures and magnetic resonance imaging for NAFLD diagnosis. A model combining waist-to-height ratio, homeostasis model assessment of insulin resistance, adiponectin, and alanine aminotransferase was accurate in predicting NAFLD (AUROC = 0.94 [95% confidence interval 0.89-0.99], P < 10). When adiponectin was not included in the model, the discrimination accuracy was still good (AUROC = 0.88 [95% confidence interval 0.79-0.97], P < 10). In conclusion, a predictive equation combining routinely available variables may allow physicians to identify obese children at the highest risk of NAFLD.

Metabolic syndrome in pediatrics: old concepts revised, new concepts discussed

The worldwide epidemic of childhood obesity in the last decades is responsible for the occurrence in pediatrics of disorders once mainly found in adults, such as the metabolic syndrome. A key factor in the pathogenesis of metabolic syndrome is insulin resistance, a phenomenon occurring mainly in obese subjects with a general resistance to the insulin effect only on carbohydrates metabolism. Given that the metabolic syndrome is driven by obesity, the prevalence of the latter will strongly influence the prevalence of metabolic syndrome. This article addresses the causes of metabolic syndrome and the relevance of obesity in the pediatric population.

Pediatric nonalcoholic fatty liver disease, metabolic syndrome and cardiovascular risk

Nonalcoholic fatty liver disease (NAFLD) encompasses a range of liver histology severity and outcomes in the absence of chronic alcohol use. The mildest form is simple steatosis in which triglycerides accumulate within hepatocytes. A more advanced form of NAFLD, non-alcoholic steatohepatitis, includes inflammation and liver cell injury, progressive to cryptogenic cirrhosis. NAFLD has become the most common cause of chronic liver disease in children and adolescents. The recent rise in the prevalence rates of overweight and obesity likely explains the NAFLD epidemic worldwide. NAFLD is strongly associated with abdominal obesity, type 2 diabetes, and dyslipidemia, and most patients have evidence of insulin resistance. Thus, NAFLD shares many features of the metabolic syndrome (MetS), a highly atherogenic condition, and this has stimulated interest in the possible role of NAFLD in the development of atherosclerosis. Accumulating evidence suggests that NAFLD is associated with a significantly greater overall mortality than in the general population, as well as with increased prevalence of cardiovascular disease (CVD), independently of classical atherosclerotic risk factors. Yet, several studies including the pediatric population have reported independent associations between NAFLD and impaired flow-mediated vasodilatation and increased carotid artery intimal medial thickness-two reliable markers of subclinical atherosclerosis-after adjusting for cardiovascular risk factors and MetS. Therefore, the rising prevalence of obesity-related MetS and NAFLD in childhood may lead to a parallel increase in adverse cardiovascular outcomes. In children, the cardiovascular system remains plastic and damage-reversible if early and appropriate interventions are established effectively. Therapeutic goals for NAFLD should address nutrition, physical activity, and avoidance of smoking to prevent not only end-stage liver disease but also CVD.

Diagnostic challenges of nonalcoholic fatty liver disease (NAFLD) in children of normal weight

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is generally regarded as affecting the overweight or obese. Though previously reported, the notion that NAFLD occurs in the presence of normal body weight (adult BMI<25) is unfamiliar in adults and problematic in children. Normal-body-weight NAFLD accounts for approximately 15% of all NAFLD and may be more prevalent with certain ethnicities.

CASE

We describe a case of a child who appeared to have normal-body-weight NAFLD, on the basis of typical age of presentation, ultrasonographically evident hepatic steatosis and compatible liver histology, including a NAFLD activity score of 7, but was shown conclusively to have cystic fibrosis. Further we present a clinical strategy for diagnosis of childhood NAFLD, which would discriminate between this patient and actual normal-body-weight NAFLD children in our clinical practice.

CONCLUSION

NAFLD requires affirmative diagnostic criteria and should not be merely a diagnosis of exclusion.

What is the significance of soluble and endogenous secretory receptor for advanced glycation end products in liver steatosis in obese prepubertal children?

The endogenous secretory receptor for advanced glycation end products (esRAGE) and soluble RAGE (sRAGE) have been shown in human plasma and have emerged as reliable biomarkers of several pathological conditions, including insulin resistance and liver injury. We examined esRAGE and sRAGE levels in obese prepubertal children with and without liver steatosis. esRAGE and sRAGE levels were significantly lower in obese prepubertal children affected by liver steatosis and were independently related to liver steatosis. These findings suggest that AGE-RAGE pathway plays an independent role in the development of liver injury already present in this age group.

Non-alcoholic fatty liver disease: An early mediator predicting metabolic syndrome in obese children?

AIM

To investigate if non-alcoholic fatty liver disease (NAFLD) is an early mediator for prediction of metabolic syndrome, and if liver B-ultrasound can be used for its diagnosis.

METHODS

We classified 861 obese children (6-16 years old) into three subgroups: group 0 (normal liver in ultrasound and normal transaminases); group 1 (fatty liver in ultrasound and normal transaminases); and group 2 (fatty liver in ultrasound and elevated transaminases). We measured the body mass index, waist and hip circumference, blood pressure, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), whole-body insulin sensitivity index (WBISI), lipid profile and transaminases in all the participants. The risk of developing metabolic syndrome (MS) was assessed according to the degree of liver fatty infiltration based on the B-ultrasound examination.

RESULTS

Among the 861 obese children, 587 (68.18%) were classified as having NAFLD, and 221 (25.67%) as having MS. The prevalence of MS in NAFLD children (groups 1 and 2) was 37.64% (221/587), which was much higher than that in non-NAFLD group (group 0, 12.04%) (P < 0.01). There were significantly higher incidences concerning every component of MS in group 2 compared with group 0 (P < 0.05). The incidence of NAFLD in MS patients was 84.61% (187/221), which was significantly higher than that of hypertension (57.46%, 127/221) and glucose metabolic anomalies (22.62%, 50/221), and almost equal to the prevalence of dyslipidemia (89.14%, 197/221). Based on the B-ultrasound scales, the presence of moderate and severe liver fatty infiltration carried a high risk of hypertension [odds ratio (OR): 2.18, 95% confidence interval (95% CI): 1.27-3.75], dyslipidemia (OR: 7.99, 95% CI: 4.34-14.73), impaired fasting glucose (OR: 3.65, 95% CI: 1.04-12.85), and whole MS (OR: 3.77; 95% CI: 1.90-7.47, P < 0.01). The state of insulin resistance (calculated by HOMA-IR and WBISI) deteriorated as the degree of fatty infiltration increased.

CONCLUSION

NAFLD is not only a liver disease, but also an early mediator that reflects metabolic disorder, and liver B-ultrasound can be a useful tool for MS screening.

The latest idea in NAFLD/NASH pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder characterized by fatty accumulation in the liver without alcohol consumption. NAFLD ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), which may progress to end-stage liver disease. The prevalence of NAFLD is rising because of an increasing prevalence of obesity and metabolic syndrome. The progression of these diseases is considered to be related to metabolic syndrome, which is characterized by obesity, glucose impairment, dyslipidemia, hypertension, and adipocytokine impairment. In addition, the pathogenesis of NAFLD/NASH is considered to be multifactorial and complex and is influenced by lifestyle habits, nutritional factors, and genetics. In particular, the PNPLA3 gene has been recently recognized as the most important functional gene polymorphism in the progression of NASH. Disruption in hepatic lipid metabolism is closely related to the development of fatty liver. Accumulation of excess triglycerides (TGs) induces hepatic steatosis. However, TG accumulation itself is not harmful to hepatocytes and may instead act as a protective mechanism against free fatty acid (FFA)-induced lipotoxicity. Excess FFAs also contribute to hepatotoxicity in NAFLD/NASH because oxidation of FFAs in hepatic microsomes generates excessive oxidative stress. Oxidative stress is considered one of the most important pathogenic factors in the development of NASH. Mitochondrial abnormalities, which are frequently observed in NASH-affected livers, are associated with impaired electron transport and result in further oxidative stress formation. The aims of this review are to assess the mechanisms of lipid metabolism and hepatic steatosis, the background of the disease, and the potential molecular mechanisms involved.

Serum hyaluronic acid for the screening of progressive nonalcoholic steatohepatitis in children: a promising approach

Nonalcoholic fatty liver disease (NAFLD) represents now the leading cause of liver disease in children in Western countries. NAFLD encompasses a wide spectrum of liver pathology ranging from simple uncomplicated steatosis to steatohepatitis (NASH), with possible progression to cirrhosis and hepatocarcinoma. Presently only liver biopsy can discriminate patients with NASH, but it remains a costly and invasive procedure, and in children is still perceived to carry a higher risk of complications, and is less accepted than in adults. Thus, there is an urgent need of noninvasive markers of NASH. In the present issue, Nobili and coworkers demonstrate that the evaluation of serum hyaluronic acid (HA), a relatively cheap, immediate, and readily available approach, predicts liver fibrosis independently of biochemical indices of liver damage in 100 children with NAFLD referred to a tertiary care center, and may allow to identify by a double cut-off approach those without fibrosis and those with moderate-severe fibrosis with a high specificity, without recurring to not yet available complex tests for the prediction of fibrosis requiring the evaluation of predictive algorithms. These findings represent a significant step forward and should be replicated in independent series followed at tertiary centers and, thanks to the relatively low cost of the method, in populations at lower risk of liver damage.

I148M patatin-like phospholipase domain-containing 3 gene variant and severity of pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease in children. Genetic variability, which is a main player in NAFLD, is especially characterized by polymorphisms in genes involved in the development and progression of the disease to nonalcoholic steatohepatitis (NASH). Recently, the rs738409 C>G adiponutrin/patatin-like phospholipase domain-containing 3 (PNPLA3) polymorphism, which encodes the I148M protein variant in the catalytic domain, has been associated with severe steatosis, NASH, and liver fibrosis in adults. In this study, we investigated the association between the rs738409 PNPLA3 gene polymorphism and NAFLD in 149 consecutive children and adolescents (age = 6-13 years) with biopsy-proven NAFLD. We analyzed the rs738409 polymorphism by a 5'-nuclease TaqMan assay and assessed its association with NASH: 41% of the subjects with NAFLD showed heterozygosity and 15% showed homozygosity for the at-risk G allele. The rs738409 genotype did not influence the body mass, adiposity, lipid levels, or insulin resistance and was not associated with alanine aminotransferase levels. Interestingly, the rs738409 G allele was strongly associated with the severity of steatosis (P < 0.0001), the presence of NASH (P < 0.0001), hepatocellular ballooning (P < 0.0001), lobular inflammation (P < 0.0001), and the presence of fibrosis (P = 0.01) independently of confounders. Individuals carrying two minor G alleles almost always had severe steatosis and NASH, heterozygotes were at intermediate risk, and patients negative for G alleles had milder and often uncomplicated steatosis.

CONCLUSION

The PNPLA3 rs738409 polymorphism is associated with steatosis severity, hepatocellular ballooning, lobular inflammation, and perivenular fibrosis in pediatric NAFLD.

Association between metabolic syndrome and liver histology among children with nonalcoholic Fatty liver disease

OBJECTIVES

Nonalcoholic steatohepatitis (NASH) is considered the hepatic manifestation of metabolic syndrome (MetS) among adults. Emerging data suggest that MetS may be associated with nonalcoholic fatty liver disease (NAFLD) in children as well. We sought to determine whether MetS or its component features are associated with specific histological features or severity of NAFLD.

METHODS

Children and adolescents aged 6-17 years enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) with clinical data obtained within 6 months of liver biopsy were included. MetS was defined as the presence of three or more of the following features as determined by application of age-adjusted normative values: central obesity, dyslipidemia, impaired fasting glucose, and elevated blood pressure. Liver biopsies were evaluated by the Pathology Committee of the NASH CRN.

RESULTS

Two hundred fifty four children were included in the analysis, of whom 65 (26%) met specified criteria for MetS. Among children with MetS, there is a higher proportion of females who were on average older in age and pubertal. The risk of MetS was greatest among those with severe steatosis (odds ratio (OR)=2.58 for grade 3 vs. grade 1 steatosis, P=0.001). The presence of hepatocellular ballooning was also significantly associated with MetS (OR=2.10, P=0.03). Those with advanced fibrosis (stage 3/4) had an OR for MetS of 3.21 (P=0.04) vs. those without fibrosis (stage 0). Borderline zone 1 or definite NASH patterns compared with "not NASH" were strongly associated with MetS (OR=4.44, P=0.005 and OR=4.07, P=0.002, respectively). The mean NAFLD Activity Score (NAS) was greater among children with MetS vs. those without (4.8 +/- 1.4 vs. 4.3 +/- 1.4, P=0.01). Central obesity was significantly associated with steatosis, fibrosis, hepatocellular ballooning, and NAFLD pattern. Insulin resistance was significantly associated with steatosis, fibrosis, hepatocellular ballooning, NAS, and NAFLD pattern.

CONCLUSIONS

MetS is common among children with NAFLD and is associated with severity of steatosis, hepatocellular ballooning, NAS, NAFLD pattern, and the presence of advanced fibrosis. Individual MetS features, particularly central obesity and insulin resistance, were also associated with severity of NAFLD. MetS features should be considered in children with NAFLD as individually and collectively they help identify children with more advanced disease.

Metabolic differences between male and female adolescents with non-alcoholic fatty liver disease, as detected by ultrasound

BACKGROUND

Age, developmental stage and gender are risk factors for paediatric non-alcoholic fatty liver disease (NAFLD).

AIMS

The aim of this study was to identify differences in clinical or laboratory variables between sexes in adolescents with NAFLD.

METHODOLOGY

Ninety obese adolescents including 36 males and 54 females were evaluated. Inclusion criteria for this study were a Body Mass Index above the 95th percentile, as set forth by the National Center for Health Statistics, and an age of 10-19 years. A clinical and laboratory evaluation was conducted for all adolescents.

RESULTS

The variables that were found to be predictive of NAFLD in adolescence were visceral fat, Aminotransferase, Gamma-Glutamyl Transferase, triglyderides, cholesterol and LDL-cholesterol. We also observed that cholesterol and LDL-cholesterol variables were influenced by gender, i.e. there was a significant statistical difference in the values of these variables between male and female adolescents. With regard to cholesterol serum concentrations, the risk was 6.99 times greater for females, compared with 1.2 times for males; and for LDL-cholesterol serum concentrations the risk was 8.15 times greater for females, compared with and 1.26 times for males.

CONCLUSION

Female adolescents with NAFLD showed a significantly different metabolic behaviour than males.

Pediatric nonalcoholic fatty liver disease: A clinical and laboratory challenge

The true prevalence of pediatric nonalcoholic fatty liver disease (NAFLD) is unknown. Challenges in determining the population prevalence of NAFLD include the type of test (and the reference intervals used to define normal and abnormal), the type of population (general population, hospital series), the demographic characteristics of the population sampled, and the nature of the study design. The natural history of pediatric NAFLD remains uncertain. The issue of when to perform a liver biopsy in children with suspected NAFLD remains controversial. Children with NAFLD but normal alanine aminotransferase are rarely investigated. However, evidence of alterations in glucose metabolism parameters should prompt a better understanding of the natural history of pediatric NAFLD not only in terms of the progression of liver disease but also regarding its potential relationship with other health outcomes such as type 2 diabetes mellitus and cardiovascular disease. This evidence could make liver biopsy mandatory in the majority of cases at risk of progressive and severe hepatic and extrahepatic disease. This conclusion, however, raises the question of the feasibility of liver biopsy assessment in an extremely large at risk population, and of the cost/effectiveness of this policy. There is a considerable, continuous interest in reliable, noninvasive alternatives that will allow the prognosis of pediatric NAFLD to be followed in large community or population-based studies.

Nonalcoholic fatty liver disease in children

PURPOSE OF REVIEW

The intent of this review is to provide a concise overview of all recent acquisitions in terms of therapies and early noninvasive diagnostic approaches for nonalcoholic fatty liver disease (NAFLD) in children.

RECENT FINDINGS

NAFLD is increasingly being diagnosed in children. If undiscovered and if certain risks are present (i.e. obesity), nonalcoholic steatohepatitis, the most severe form of NAFLD, may silently progress to cirrhosis, hepatocarcinoma and liver-related death in adulthood. Current therapies include approaches for reducing the incidence of risk factors (i.e. weight reduction), drugs targeting the major molecular mechanisms thought essential in the pathogenesis of the disease (insulin resistance and oxidative stress) or both, but other novel treatments are under investigation.

SUMMARY

Although weight reduction, achieved through a combination of diet and exercise, makes it possible to modify the natural course of simple steatosis, the addition of adequate drugs might also provide a therapeutic action on nonalcoholic steatohepatitis. Moreover, preventive strategies and the design and translation into clinical practice of indices that integrate noninvasive diagnostic tools and serum biomarkers might be a winning approach for improving management of paediatric NAFLD/nonalcoholic steatohepatitis in the coming years.

Obese boys at increased risk for nonalcoholic liver disease: evaluation of 16,390 overweight or obese children and adolescents

OBJECTIVE

Comorbidities of childhood obesity challenge health-care systems in Europe. Further, there is a lack of population-specific prevalence data and diagnostic strategies available, especially for obesity-related disturbances of liver function. Therefore, the prevalence of elevated liver enzymes and their relationship to biological parameters were studied in a large pediatric obesity cohort.

METHODS

In 111 specialized pediatric obesity centers in Germany, Austria and Switzerland, 16,390 children and adolescents (age 12.4±2.6 years, 58% boys) were categorized as overweight (body mass index (BMI) >90th percentile) and obese (>97th percentile) and studied for related comorbidities, especially nonalcoholic fatty liver disease (NAFLD; as defined by aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) >50 U l(-1)). Data were collected using a standardized software program (APV) for longitudinal multicenter documentation. Pseudonymized data were transmitted for central statistical analysis.

RESULTS

In this pediatric cohort, 16% of the study population was overweight, 46% obese and 35% extremely obese (>99.5th percentile extreme obesity (Xob)). NAFLD was present in 11% of the study population, but predominantly in boys (boys vs girls; 14.4:7.4%; P<0.001), in Xob (obese vs Xob; 9.5:17.0%; P<0.001) and in older age (< 12 vs ≥12 years; 8:12%; P<0.001; adjusted for BMI). ALT >50 U l(-1) was significantly associated with fasting insulin and BMI-SDS. In multiple logistic regression models, Xob and male gender were strongly associated with NAFLD (odds ratio Xob vs normal weight=3.2; boys vs girls OR=2.3).

CONCLUSION

In a large cohort of overweight and obese European children and adolescents, markers of nonalcoholic liver disease, especially ALT, are frequent and predicted by Xob and male gender. The results underline the epidemiological dimension of this obesity-related morbidity even in childhood. Therefore, at least ALT is recommended as a screening parameter in basic care.

Insulin resistance and metabolic syndrome in the pediatric population

The metabolic syndrome is a constellation of specific anthropometric, physiological, and biochemical abnormalities predisposing affected individuals to the development of diabetes and cardiovascular disease. The syndrome is well described in the adult literature. However, its description in the pediatric literature is more limited. Due in large part to the normal physiological changes that occur in children and adolescents with respect to growth and puberty, investigators have also struggled to establish a standard definition of the syndrome in the pediatric age group, hindering coordinated research efforts. However, whatever definition of the syndrome is used, the prevalence of the metabolic syndrome in the pediatric age group has increased worldwide. Insulin resistance is the principal metabolic abnormality that is common to the development of the metabolic syndrome in both children and adults. This review summarizes current research regarding the pathophysiology of insulin resistance and how this may contribute to specific abnormalities seen in children and adolescents with the metabolic syndrome. Specifically, insulin resistance in pediatric patients is correlated with cardiovascular risk factors such as elevated blood pressure, dyslipidemia, and type 2 diabetes mellitus, all of which are significant risk factors for adult disease. In addition, current treatment and prevention strategies, including lifestyle modifications, pharmacologic agents, and certain surgical therapies, are highlighted. The need for collaborative changes at the family, school, city, state, and national levels to address the growing prevalence of the metabolic syndrome in the pediatric age group is also reviewed.

The possible role of liver steatosis in defining metabolic syndrome in prepubertal children

Insulin resistance is a key component of the metabolic syndrome (MS) and is strongly associated with liver steatosis. Our aim was to evaluate whether MS should be diagnosed already in obese prepubertal children and whether its prevalence is influenced by the inclusion of hepatic steatosis as a diagnostic criterion. Eighty-nine obese children (43 boys; age median [range], 8.5 [6-10] years) were enrolled. Metabolic syndrome was diagnosed according to a classic definition: presence of 3 or more of the following criteria-body mass index greater than 2 standard deviation score, triglycerides greater than the 95th percentile, high-density lipoprotein cholesterol less than the fifth percentile, blood pressure greater than the 95th percentile, and impaired glucose tolerance. Afterward, liver steatosis was included as an additional criterion to this definition. Metabolic syndrome was diagnosed in 12 children (13.5%) according to the first definition and in 18 children (20.2%) when liver steatosis was included. The prevalence of MS increased across homeostasis model assessment of insulin resistance tertiles (P for trend = .01). The prevalence of the single components of the MS was as follows: obesity, 100%; hypertriglyceridemia, 27%; low high-density lipoprotein cholesterol, 2.2%; hypertension, 34.8%; impaired glucose tolerance, 4.5%; and nonalcoholic fatty liver disease, 21.3%. In conclusion, MS is common already among prepubertal obese children, particularly when liver steatosis is included among the diagnostic criteria. Therefore, screening for the MS should be performed in this age group; and hepatic steatosis should be considered as an additional diagnostic criterion.

Fatty liver disease in children: eat now pay later

INTRODUCTION

With the recent epidemic in childhood obesity, nonalcoholic fatty liver disease (NAFLD) has become an emerging problem and a common cause of chronic liver disease in children.

METHODS

In this review, the most recent insights on the pathogenesis, diagnosis, natural history, and treatment of NAFLD in children are discussed.

Pediatric non-alcoholic fatty liver disease: Preventive and therapeutic value of lifestyle intervention

Nonalcoholic fatty liver disease (NAFLD), ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), and eventually cirrhosis and liver failure, is seen to be increasing amongst Western children. NAFLD rates are rising in parallel with the epidemic of childhood obesity, and in particular, fatty liver evolves more easily in NASH when poor dietary habits and sedentary lifestyle are combined. In fact, its general prevalence in the child population varies between 2.6% and 10%, but increases up to 80% in obese children. Since NASH is expected to become the most common cause of pediatric chronic liver disease in the near future, there is broad interest amongst clinical researchers to move forward, both in diagnosis and treatment. Unfortunately, to date, the expensive and invasive procedure of liver biopsy is seen as the gold standard for NASH diagnosis and few noninvasive diagnostic methods can be applied successfully. Moreover, there are still no approved pharmacological interventions for NAFLD/NASH. Therefore, current management paradigms are based upon the presence of associated risk factors and aims to improve an individual’s quality of life, thus reducing NAFLD-associated morbidity and mortality. Today, lifestyle intervention (diet and exercise) is the treatment of choice for NAFLD/NASH. Thus far, no study has evaluated the potential preventive effect of lifestyle intervention on children at risk of NAFLD/NASH. Future studies will be required in this area with the perspective of developing a national program to promote nutrition education and increase physical activity as means of preventing the disease in individuals at risk. Here, we outline the clinical course, pathogenesis and management of NAFLD in children, highlighting the preventive and therapeutic value of lifestyle intervention.

Gender-specific prevalences of fatty liver in obese children and adolescents: roles of body fat distribution, sex steroids, and insulin resistance

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is known to have a gender-dimorphic prevalence in obese children. Less information is available on predictive factors for NAFLD in obese youths.

OBJECTIVE

The aim of the study was to examine the prevalence pattern and to identify clinical and laboratory markers associated with the risk for NAFLD.

DESIGN

This was a cross-sectional study.

SETTING

The study setting was a rehabilitation clinic.

STUDY PARTICIPANTS

A total of 532 obese subjects (291 girls) aged 8-19 yr participated in the study.

MAIN MEASUREMENTS

Steatosis hepatis and visceral fat mass were determined by ultrasound. Laboratory tests included serum lipids, adiponectin, high-sensitivity C-reactive protein, sex steroids, and an oral glucose tolerance test.

RESULTS

Prevalence of hepatic steatosis was significantly higher in boys (41.1%) than in girls (17.2%) and was highest in postpubertal boys (51.2%) and lowest in postpubertal girls (12.2%). Severity of steatosis was associated with increased visceral fat mass, insulin resistance, lower adiponectin levels, and higher blood pressure. Three factors were extracted from the panel of investigated parameters by principal component analysis. Logistic regression analysis revealed significant associations of simple steatosis with the "insulin resistance and visceral fat" factor and the "body fat distribution and inflammation" factor in both genders and additionally with the "steroid hormones" factor in girls. Risk for steatosis hepatis with concomitantly elevated ALT was associated only with "insulin resistance and visceral fat" in girls and with all three factors in boys.

CONCLUSION

Our results suggest significant associations of NAFLD with markers of visceral obesity and insulin resistance in both genders and gender-specific associations with parameters of body fat distribution and sex steroids.