Steatohepatitis in children

Amino Acid-Related Metabolic Signature in Obese Children and Adolescents

The growing interest in metabolomics has spread to the search for suitable predictive biomarkers for complications related to the emerging issue of pediatric obesity and its related cardiovascular risk and metabolic alteration. Indeed, several studies have investigated the association between metabolic disorders and amino acids, in particular branched-chain amino acids (BCAAs). We have performed a revision of the literature to assess the role of BCAAs in children and adolescents' metabolism, focusing on the molecular pathways involved. We searched on Pubmed/Medline, including articles published until February 2022. The results have shown that plasmatic levels of BCAAs are impaired already in obese children and adolescents. The relationship between BCAAs, obesity and the related metabolic disorders is explained on one side by the activation of the mTORC1 complex-that may promote insulin resistance-and on the other, by the accumulation of toxic metabolites, which may lead to mitochondrial dysfunction, stress kinase activation and damage of pancreatic cells. These compounds may help in the precocious identification of many complications of pediatric obesity. However, further studies are still needed to better assess if BCAAs may be used to screen these conditions and if any other metabolomic compound may be useful to achieve this goal.

Stoffwechselerkrankungen

Entsprechend ihrer Wanderung bei isoelektrischer Fokussierung werden die allelen Varianten des α1-AT als Proteinaseinhibitorphänotypen (Pi) klassifiziert. Die dominierende Isoform ist der normale Phänotyp M, daneben gibt es die Mangelvarianten S und Z sowie eine 0-Variante.

Histopathological diagnosis of non-alcoholic and alcoholic fatty liver disease

The diagnostic procedures in patients with suspected fatty liver disease-with or without known alcohol consumption-should be standardized and generally accepted. We therefore present a guideline, summarizing the current concepts of etiology, diagnostic as well as differential diagnostic of patients with fatty liver disease. Alcoholic as well as and non-alcoholic fatty liver are characterised by lipid deposition in hepatocytes. The diagnosis of steatosis is made when lipid deposition exceeds 5% of hepatocytes, while involvement of more than 50% is called "fatty liver". An additional inflammatory reaction leads to alcoholic (ASH) or non-alcoholic steatohepatitis (NASH). Steatohepatitis is present when both inflammatory infiltrates of mixed cells in the small liver lobules as well as liver cell injury in terms of ballooning can be detected. Liver biopsy represents the "golden standard" for confirming diagnosis and determining inflammatory activity and potential fibrosis of fatty liver disease. The differential diagnosis of ASH vs. NASH cannot be made on the basis of histological criteria alone. Steatosis, inflammatory changes and hepatocytic injury can be semiquantified as a "Brunt Score" or "NAS" (NAFLD activity score), providing the basis on which to decide whether or not steatohepatitis is present. People at increased risk of developing a fatty liver possess an increased risk of developing chemotherapy-associated steatohepatitis. Histologically, pediatric NASH differs from adult NASH and is often only clinically manifest through a mild if persistent elevation in transaminases.

Histopathological diagnosis of non-alcoholic and alcoholic fatty liver disease

The diagnostic procedures in patients with suspected fatty liver disease-with or without known alcohol consumption-should be standardized and generally accepted. We therefore present a guideline, summarizing the current concepts of etiology, diagnostic as well as differential diagnostic of patients with fatty liver disease. Alcoholic as well as and non-alcoholic fatty liver are characterised by lipid deposition in hepatocytes. The diagnosis of steatosis is made when lipid deposition exceeds 5% of hepatocytes, while involvement of more than 50% is called "fatty liver". An additional inflammatory reaction leads to alcoholic (ASH) or non-alcoholic steatohepatitis (NASH). Steatohepatitis is present when both inflammatory infiltrates of mixed cells in the small liver lobules as well as liver cell injury in terms of ballooning can be detected. Liver biopsy represents the "golden standard" for confirming diagnosis and determining inflammatory activity and potential fibrosis of fatty liver disease. The differential diagnosis of ASH vs. NASH cannot be made on the basis of histological criteria alone. Steatosis, inflammatory changes and hepatocytic injury can be semiquantified as a "Brunt Score" or "NAS" (NAFLD activity score), providing the basis on which to decide whether or not steatohepatitis is present. People at increased risk of developing a fatty liver possess an increased risk of developing chemotherapy-associated steatohepatitis. Histologically, pediatric NASH differs from adult NASH and is often only clinically manifest through a mild if persistent elevation in transaminases.

Histopathological diagnosis of non-alcoholic and alcoholic fatty liver disease

The diagnostic procedures in patients with suspected fatty liver disease-with or without known alcohol consumption-should be standardized and generally accepted. We therefore present a guideline, summarizing the current concepts of etiology, diagnostic as well as differential diagnostic of patients with fatty liver disease. Alcoholic as well as and non-alcoholic fatty liver are characterised by lipid deposition in hepatocytes. The diagnosis of steatosis is made when lipid deposition exceeds 5% of hepatocytes, while involvement of more than 50% is called "fatty liver". An additional inflammatory reaction leads to alcoholic (ASH) or non-alcoholic steatohepatitis (NASH). Steatohepatitis is present when both inflammatory infiltrates of mixed cells in the small liver lobules as well as liver cell injury in terms of ballooning can be detected. Liver biopsy represents the "golden standard" for confirming diagnosis and determining inflammatory activity and potential fibrosis of fatty liver disease. The differential diagnosis of ASH vs. NASH cannot be made on the basis of histological criteria alone. Steatosis, inflammatory changes and hepatocytic injury can be semiquantified as a "Brunt Score" or "NAS" (NAFLD activity score), providing the basis on which to decide whether or not steatohepatitis is present. People at increased risk of developing a fatty liver possess an increased risk of developing chemotherapy-associated steatohepatitis. Histologically, pediatric NASH differs from adult NASH and is often only clinically manifest through a mild if persistent elevation in transaminases.

[Histopathological diagnosis of non-alcoholic and alcoholic fatty liver disease. Grade 2 consensus-based guidelines]

Both alcoholic (AFL) and non-alcoholic fatty liver (NAFL) are characterized by lipid deposition in hepatocytes. The diagnosis of steatosis is made when lipid deposition exceeds 5% of hepatocytes, while involvement of more than 50% is called "fatty liver ". An additional inflammatory reaction leads to alcoholic (ASH) or non-alcoholic steatohepatitis (NASH). Steatohepatitis is present when both inflammatory infiltrates of mixed cells in the small liver lobules as well as liver cell injury in terms of ballooning can be detected.Liver biopsy represents the "gold standard" for confirming diagnosis and determining inflammatory activity and potential fibrosis of fatty liver disease.The differential diagnosis of ASH-NASH cannot be made on the basis of histological criteria alone. Steatosis, inflammatory changes and hepatocytic injury can be semiquantified as a "Brunt Score" or "NAS" (NAFLD activity score), providing the basis on which to decide whether or not steatohepatitis is present.People at increased risk of developing a fatty liver possess an increased risk of developing chemotherapy-associated steatohepatitis (CASH).Histologically, pediatric NASH differs from adult NASH and is often only clinically manifest through a mild if persistent elevation in transaminases.

Intima-media thickness of carotid artery and susceptibility to atherosclerosis in obese children with nonalcoholic fatty liver disease

OBJECTIVE

To test, via prospective case-control study, whether measurements of carotid artery intima-media thickness (cIMT) reflect the susceptibility to atherosclerosis in obese children with nonalcoholic fatty liver disease.

PATIENTS AND METHODS

In all, 80 obese asymptomatic normotensive adolescents (body mass index [BMI], 29.12 +/- 5.13; 8.5-17.5 years) and 30 age- and sex-matched nonobese healthy children (BMI 18.55 +/- 2.24). Children were analysed in 4 groups: Controls formed group 1, 26 children with obesity without hepatosteatosis formed group 2, 32 children with grade 1 hepatosteatosis formed group 3, and 22 children with grade 2 or 3 hepatosteatosis formed group 4. The key parameters were BMI, liver function tests, lipid profiles, glucose, hepatic ultrasonography, and IMT of common carotid artery (CCA), left carotid bulbus (CB), and left internal carotid artery (ICA).

RESULTS

Comparisons of IMT measurements of left CCA, left CB, and left ICA between controls and obesity group revealed statistically significant differences (each segment P < 0.0001). There was an increase in the mean of IMT of each segment with the increase in hepatosteatosis grade (each segment P < 0.0001). The relation between the mean of IMT of left CCA, left CB, and left ICA with BMI (P = 0.001, r = 0.318), alanine aminotransferase (P = 0.007, r = 0.256), and hepatosteatosis (P < 0.0001, r = 0.470) was significant. Multiple regression analysis between left CCA, left CB, and left ICA, and age, sex, relative weight, alanine aminotransferase, total cholesterol, obesity, and hepatosteatosis grade was significant for only hepatosteatosis grade.

CONCLUSIONS

The cIMT is significantly higher, increasing susceptibility to atherosclerosis, in obese children with hepatosteatosis than in healthy children or obese children without hepatosteatosis.

Methylenetetrahydrofolate reductase gene polymorphisms in patients with nonalcoholic steatohepatitis (NASH)

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal hepatic steatosis in the absence of a history of alcohol use. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. Hyperhomocysteinemia causes steatosis, and the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms result in hyperhomocysteinemia. To examine whether the C677T and A1298C polymorphisms of the MTHFR gene were associated with NASH, we analysed the allele and genotype distribution of the MTHFR C677T and A1298C polymorphisms in 57 well-diagnosed NASH patients, 324 healthy controls in a case-control study of Turkish subjects of Caucasian origin. The diagnosis of the NASH patients was based on liver biopsy. The method used in the analysis of genotypes was PCR-RFLP. The MTHFR A1298C polymorphism was significantly associated with NASH (chi(2) = 8.439; p = 0.015) in the total NASH patients compared with healthy controls. The MTHFR 1298C allele (odds ratio (OR) = 2.480; 95%CI = 1.286-4.782; chi(2) = 7.703; df = 1; p = 0.006) was significantly associated with NASH in the total NASH patients. The MTHFR C677C/A1298C compound genotype (OR = 2.218; 95%CI = 1.003-4.906; chi(2) = 3.998; df = 1; p = 0.046) in men patients was also significantly associated with NASH. Likewise the MTHFR C1298C genotype was significantly associated with NASH in women patients with NASH (OR = 2.979; 95%CI = 1.027-8.641; chi(2) = 4.343; df = 1; p = 0.037). In conclusion, the MTHFR 1298C allele in all NASH patients, C1298C genotype, C677C/C1298C compound genotype in women NASH patients and C677C/A1298C compound genotype in men NASH patients were genetic risk factors for NASH.

Liver steatosis in obese prepubertal children: a possible role of insulin resistance

OBJECTIVE

To determine whether in obese prepubertal children insulin resistance (IR) is associated with the development of liver steatosis.

METHODS AND PROCEDURES

Cross-sectional study evaluating the prevalence of liver steatosis in 100 severely obese prepubertal children and comparing IR indexes between children with (group 1) and without steatosis (group 2). Furthermore, IR indexes were compared to values of 50 normal weight children. Fasting blood samples were collected for the evaluation of liver function tests, lipid profile, plasma glucose, and insulin levels. All children underwent an oral glucose tolerance test and anthropometric measurements. Hepatic ultrasound was performed according to international criteria and by one single operator. Analysis was performed by Mann-Whitney U-test, Pearson correlation, and logistic regression.

RESULTS

Liver steatosis was found in 52% obese children and was equally distributed between the two sexes. Obese children were more insulin resistant when compared to controls (homeostasis model assessment of IR (HOMA-IR): P = 0.0001; whole body insulin sensitivity index (WBISI): P = 0.0005; fasting glucose/fasting insulin ratio (G/I): P = 0.0001), and group 1 presented an even higher degree of IR when compared to group 2 (HOMA-IR P = 0.0001; WBISI P = 0.0004; G/I P = 0.0001). The area under the curve (AUC) for insulin was significantly higher in group 1 when compared to group 2, while no difference was found in the AUC for glucose. There was no association between IR and adiposity indexes (P >0.05). The role of IR as a predictor for the development of steatosis was analyzed by multiple logistic regression, which documented that IR indexes were significantly related to steatosis independently of BMI-SDS.

DISCUSSION

Liver steatosis is an emerging problem in prepubertal severely obese children, and it appears to be an association between liver steatosis and IR in these subjects.

Fatty liver in childhood

A parenchimás szervek – mint például a máj – abnormális zsírfelhalmozódását zsíros átalakulásnak nevezzük. A máj elzsírosodásának hátterében a májsejtek zsírfelvevő és zsírleadó folyamatainak egyensúlyzavara áll, miáltal a felesleges triglicerid felhalmozódik a hepatocytákban. Normál esetben a sejtek kb. 5%-a tartalmaz trigliceridet, zsírmáj esetén ez az érték 50% fölé is emelkedhet. 50% alatt májelzsírosodásról, 50% felett zsírmájról beszélünk. Enyhébb esetben nem feltétlenül okoz sejtműködési zavart, súlyosabb formánál azonban igen, sokszor a sejthalál előfutára. A zsírmáj olyan kórállapotnak tekinthető, mely érzékennyé teszi a májat egyéb toxikus hatásokkal szemben. Nem önálló betegség, legtöbbször valamilyen ártalom, egyéb kórfolyamat kísérő jelensége. Önmagában – bizonyos súlyossági fokig (a fibrosis megjelenéséig) – reverzíbilis károsodást jelent, a kiváltó ok megszűnésekor a máj a felesleges triglicerid-tartalmát leadja. Kezelni az alapfolyamatot kell; még nem ismert olyan specifikus gyógyszer, amely a hepatocytákban lerakódott zsírt csökkenti.

[Effectiveness of weight loss in the treatment of non-alcoholic steatohepatitis in an obese adolescent]

Childhood obesity is the most frequent nutritional disorder in developed countries and has been described as a global epidemic by the World Health Organization. In children, as in adults, obesity is the most significant risk factor for the development of non-alcoholic fatty liver disease. Therefore, it may become the most frequent chronic liver disease in children. However, pediatric publications on this disorder, which can progress to severe liver disease with risk of mortality, are scarce, with small series and few histological studies. The present article describes an obese adolescent who presented severe steatosis and steatohepatitis, which responded to weight loss with clinical and histological normalization. The risk of obesity comorbidity is increasing significantly in the pediatric population.

Unexpected diagnosis of cystic fibrosis at liver biopsy: a report of four pediatric cases

We report here four cases of pediatric patients in whom the diagnosis of cystic fibrosis was made only after the histological examination of a liver specimen obtained by biopsy (three cases) or at autopsy (one case). There were two boys and two girls, aged 13 months to 7.5 years. None had a personal or familial history suggestive of cystic fibrosis. One patient, presenting with myocardial lesion and hepatomegaly, died of heart failure; at autopsy, the liver showed a typical aspect of focal biliary cirrhosis. In the three other cases, liver disease was the only manifestation of cystic fibrosis at the time of diagnosis. Liver biopsy examination showed focal biliary cirrhosis in one case and massive steatosis in two. In all four cases, the diagnosis was confirmed by the existence of known pathogenic mutations in the CFTR gene. The evolution was variable; one patient had progressive liver disease with severe portal hypertension after 7 years; another one had lung complications after 1 year. In conclusion, our experience recalls that the diagnosis of cystic fibrosis must be considered in children presenting with unexplained liver disease; its confirmation by molecular techniques makes it possible to set up an appropriate follow-up.

Non invasive evaluation of liver fibrosis in paediatric patients with nonalcoholic steatohepatitis

AIM: To identify the independent predictors of hepatic fibrosis in 69 children with nonalcoholic steatohepatitis (NASH) due to nonalcoholic fatty liver disease (NAFLD).

METHODS: All patients with clinically suspected NASH underwent liver biopsy as a confirmatory test. The following clinical and biochemical variables at baseline were examined as likely predictors of fibrosis at histology: age, body mass index (BMI), systolic blood pressure (SBP), dyastolic blood pressure (DBP), fasting glucose, fasting insulin, homeostatic model assessment for insulin resistence (HOMA-IR), cholesterol, tryglicerides, alanine aminotransferase (ALT), aspartate aminotransferase (AST), AST/ALT ratio, gamma glutamil transferase (GT), platelet count, prothrombin time (PT).

RESULTS: At histology 28 (40.6%) patients had no fibrosis and 41 (59.4%) had mild to bridging fibrosis. At multivariate analysis, BMI > 26.3 was the only independent predictor of fibrosis (OR = 5.85, 95% CI = 1.6-21).

CONCLUSION: BMI helps identify children with NASH who might have fibrotic deposition in the liver.

Histological assessment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an important complication of the metabolic syndrome, which is becoming an increasingly common cause of chronic liver disease. Histological changes typically mainly affect perivenular regions of the liver parenchyma and include an overlapping spectrum of steatosis, steatohepatitis and persinusoidal or pericellular fibrosis, in some cases leading to cirrhosis. Once cirrhosis has developed, typical hepatocellular changes are often no longer conspicuous, leading to such cases being mistakenly diagnosed as 'cryptogenic'. Portal inflammation, ductular reaction and periportal fibrosis can also be seen as part of the morphological spectrum of NAFLD, particularly in the paediatric population. Hepatocellular carcinoma has also been described as a complication of NAFLD-associated cirrhosis. NAFLD is also an important cofactor in other chronic liver diseases, especially hepatitis C. Histological assessments have an important role to play in the diagnosis and management of NAFLD. These include making the potentially important distinction between simple steatosis and steatohepatitis and providing pointers to the aetiology, including cases where a dual pathology exists. A number of systems have been devised for grading and staging the severity of fatty liver disease. These require further evaluation, but have a potentially important role to play in determining prognosis and monitoring therapeutic responses.

Non-alcoholic fatty liver disease (NAFLD)--a novel common aspect of the metabolic syndrome

Non-alcoholic fatty liver disease (NAFLD) is emerging as one of the most common liver disorders claiming the urgent attention of both medical professionals and the public sphere because of the imminent epidemic of advanced liver injury that appendages epidemic of obesity. Recent research reveals simple triglyceride accumulation in hepatocytes (i.e., liver steatosis) frequently becoming complicated by inflammation (i.e., non-alcoholic steatohepatitis, or NASH) that may progress into more advanced stages of the disease including cirrhosis or, eventually, hepatocellular carcinoma. The exact mechanisms of the progression of NAFLD into overt NASH and advanced disease stages are largely unknown. There is urgent need in terms of both intensive research pursuits and effective practical measures to deal with this common threat.

Nonalcoholic fatty liver disease

NAFLD likely is the most common liver disease in children and is responsible for significant progression to cirrhosis, portal hypertension, and the need for liver transplantation in adults and even in some adolescents. Early diagnosis and lifestyle interventions appear to be our best hope for controlling progression of disease. The pediatrician is responsible for screening all obese children with measurement of aminotransferases. Those with elevated enzymes (particularly ALT) for longer than 3 months, in the absence of markers of hepatitis B or C, autoimmune chronic active hepatitis, Wilson's disease, hemochromatosis, or alpha-1-antitrypsin deficiency, should follow up with an abdominal ultrasound. In patients with a BMI in the morbidly obese range, an ultrasound to search for a diffusely echogenic liver should be performed even if the liver enzymes are normal. Findings suggestive of NAFLD should prompt the institution of appropriate dietary and exercise regimens. If these are unsuccessful after a 3-month trial, the patient should be referred to a pediatric gastroenterologist and hepatologist for further work-up and treatment, preferably in the context of a controlled therapeutic trial. Only by aggressively engaging this current epidemic will we be able to decrease the mounting human cost of NAFLD.

Nonalcoholic fatty liver disease: from steatosis to cirrhosis

Nonalcoholic steatohepatitis (NASH), the lynchpin between steatosis and cirrhosis in the spectrum of nonalcoholic fatty liver disorders (NAFLD), was barely recognized in 1981. NAFLD is now present in 17% to 33% of Americans, has a worldwide distribution, and parallels the frequency of central adiposity, obesity, insulin resistance, metabolic syndrome and type 2 diabetes. NASH could be present in one third of NAFLD cases. Age, activity of steatohepatitis, and established fibrosis predispose to cirrhosis, which has a 7- to 10-year liver-related mortality of 12% to 25%. Many cases of cryptogenic cirrhosis are likely endstage NASH. While endstage NAFLD currently accounts for 4% to 10% of liver transplants, this may soon rise. Pathogenic concepts for NAFLD/NASH must account for the strong links with overnutrition and underactivity, insulin resistance, and genetic factors. Lipotoxicity, oxidative stress, cytokines, and other proinflammatory mediators may each play a role in transition of steatosis to NASH. The present "gold standard" management of NASH is modest weight reduction, particularly correction of central obesity achieved by combining dietary measures with increased physical activity. Whether achieved by "lifestyle adjustment" or anti-obesity surgery, this improves insulin resistance and reverses steatosis, hepatocellular injury, inflammation, and fibrosis. The same potential for "unwinding" fibrotic NASH is indicated by studies of the peroxisome proliferation activator receptor (PPAR)-gamma agonist "glitazones," but these agents may improve liver disease at the expense of worsening obesity. Future challenges are to approach NAFLD as a preventive public health initiative and to motivate affected persons to adopt a healthier lifestyle.

Mitochondrial dysfunction in NASH: causes, consequences and possible means to prevent it

Calorie-enriched diet and lack of exercise are causing a worldwide surge of obesity, insulin resistance and lipid accretion in liver (i.e. hepatic steatosis), which can lead to steatohepatitis. Steatosis and nonalcoholic steatohepatitis (NASH) can also be induced by drugs such as amiodarone, tamoxifen and some antiretroviral drugs, including stavudine and zidovudine. There is accumulating evidence that mitochondrial dysfunction (more particularly respiratory chain deficiency) plays a key role in the physiopathology of NASH whatever its initial cause. In contrast, the mitochondrial beta-oxidation of fatty acids can be either increased (as in insulin resistance-associated NASH) or decreased (as in drug-induced NASH). However, in both circumstances, generation of reactive oxygen species (ROS) by the damaged respiratory chain can be augmented. ROS generation in an environment enriched in lipids in turn induces lipid peroxidation which releases highly reactive aldehydic derivatives (e.g. malondialdehyde) that have diverse detrimental effects on hepatocytes and other hepatic cells. In hepatocytes, ROS, reactive nitrogen species and lipid peroxidation products further impair the respiratory chain, either directly or indirectly through oxidative damage to the mitochondrial genome. This consequently leads to the generation of more ROS and a vicious cycle occurs. Mitochondrial dysfunction can also lead to apoptosis or necrosis depending on the energy status of the cell. ROS and lipid peroxidation products also increase the generation of several cytokines (TNF-alpha, TGF-beta, Fas ligand) playing a key role in cell death, inflammation and fibrosis. Recent investigations have shown that some genetic polymorphisms can significantly increase the risk of steatohepatitis and that several drugs can prevent or even reverse NASH. Interestingly, most of these drugs could exert their beneficial effects by improving directly or indirectly mitochondrial function in liver. Finding a drug, which could fully prevent oxidative stress and mitochondrial dysfunction in NASH is a major challenge for the next decade.

Serum adiponectin, resistin levels and non-alcoholic fatty liver disease in obese children

The objective is to investigate the relation between the levels of two serum adipocytokines (adiponectin and resistin) and non-alcoholic fatty liver disease (NAFLD) in obese children. In this study, 113 obese children were enrolled and divided into 3 groups. Obese group 1 was defined as obese children without any liver abnormality. Obese group 2 was defined as obese children just with fatty infiltration of the liver in ultrasonic appearance and obese group 3 was defined as obese children with liver function abnormality. The controls consisted of 37 nonobese children without endocrine, metabolic or kidney disease. The levels of serum adiponectin and resistin were measured by ELISA method. Insulin resistance by homeostasis model (HOMA-IR), area under curve of glucose (AUCG), serum total cholesterol, triglyceride, alanine aminotransferase, uric acid, HDL-cholesterol, LDL-cholesterol and body mass index (BMI) were measured as well. In obese children, NAFLD were found in 63 cases (55.75%). Serum adiponectin levels of obese children were significantly lower than that of controls (3.63 vs 5.79 microg/mL, P<0.001) while serum resistin levels were not different (P = 0.876). Moreover, serum adiponectin levels in obese group 1 were significantly higher than that of group 2 and 3 (4.24 vs 3.37 and 3.12 microg/mL, all P<0.05) and no difference was found between obese group 2 and obese group 3 (P>0.05). Serum resistin levels among the three obese groups were 4.37 ng/mL, 3.72 ng/mL and 4.24 ng/mL without significant difference (P = 0.592). NAFLD, BMI, gender and HDL-cholesterol were independent determinants of serum adiponectin levels in children analyzed by multiple regression analysis, which explained 33% of the variance. Serum adiponectin levels were inversely associated with BMI, gender and NAFLD (all P<0.05) and were positively associated with HDL-cholesterol levels (P = 0.033). These results suggest that adiponectin might be a protective factor in NAFLD occurrence in obese children, and that the measurement of adiponectin should be part of the standard evaluation of the obese child and may help to evaluate the occurrence of NAFLD.

Hormonal and metabolic consequences of childhood obesity

It is apparent that chronic illnesses such as type 2 diabetes and cardiovascular disease originate in childhood. Obesity in childhood and adolescence hastens their development, enhances their rates of progression, increases the risks of severe complications, and if persistent, reduces life expectancy.

Design and validation of a histological scoring system for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in the absence of a history of significant alcohol use or other known liver disease. Nonalcoholic steatohepatitis (NASH) is the progressive form of NAFLD. The Pathology Committee of the NASH Clinical Research Network designed and validated a histological feature scoring system that addresses the full spectrum of lesions of NAFLD and proposed a NAFLD activity score (NAS) for use in clinical trials. The scoring system comprised 14 histological features, 4 of which were evaluated semi-quantitatively: steatosis (0-3), lobular inflammation (0-2), hepatocellular ballooning (0-2), and fibrosis (0-4). Another nine features were recorded as present or absent. An anonymized study set of 50 cases (32 from adult hepatology services, 18 from pediatric hepatology services) was assembled, coded, and circulated. For the validation study, agreement on scoring and a diagnostic categorization ("NASH," "borderline," or "not NASH") were evaluated by using weighted kappa statistics. Inter-rater agreement on adult cases was: 0.84 for fibrosis, 0.79 for steatosis, 0.56 for injury, and 0.45 for lobular inflammation. Agreement on diagnostic category was 0.61. Using multiple logistic regression, five features were independently associated with the diagnosis of NASH in adult biopsies: steatosis (P = .009), hepatocellular ballooning (P = .0001), lobular inflammation (P = .0001), fibrosis (P = .0001), and the absence of lipogranulomas (P = .001). The proposed NAS is the unweighted sum of steatosis, lobular inflammation, and hepatocellular ballooning scores. In conclusion, we present a strong scoring system and NAS for NAFLD and NASH with reasonable inter-rater reproducibility that should be useful for studies of both adults and children with any degree of NAFLD. NAS of > or =5 correlated with a diagnosis of NASH, and biopsies with scores of less than 3 were diagnosed as "not NASH."

Role of liver biopsy in the assessment of non-alcoholic fatty liver disease

Assessments of liver biopsies are important in the diagnosis and management of non-alcoholic fatty liver disease. Histology remains the 'gold standard' for making the important distinction between simple steatosis, which is generally non-progressive and readily reversible, and steatohepatitis, which has the potential to progress to severe fibrosis or cirrhosis. Liver biopsy may also identify other causes of liver disease in patients thought to have fatty liver disease and vice versa. Histological grading and staging of fatty liver disease require further study but these are potentially important approaches for studying disease severity and progression, particularly in the context of clinical trials to assess novel therapeutic approaches.

Lipid metabolism in hepatic steatosis

Hepatic steatosis is a consequence of both obesity and ethanol use. Nonalcoholic steatosis (NASH) resemble alcoholic steatosis and steatohepatitis. Both exhibit increased hepatocellular triglycerides(TG), reflecting an increase in long chain fatty acids (LCFA). LCFA enter cells by both facilitated transport and passive diffusion. A driving force for both is the plasma unbound LCFA concentration ([LCFAu]). In both obese rodents and obese patients, adipocyte LCFA uptake via both facilitated transport and diffusion is increased. However, the LCFA uptake Vmax in hepatocytes is not increased in obese animals. Nevertheless, total LCFA uptake in obese rodents is increased ~3-fold, reflecting increased plasma LCFA concentrations. With advancing obesity, resistance to the antilipolytic effects of insulin results in increased lipolysis within the omental fat depot, a consequent further rise in portal venous LCFA, and an even greater rise in portal [LCFAu]. This causes a further increase in hepatocellular LCFA uptake, increased intracellular generation of reactive oxygen species (ROS), and transition from simple steatosis to NASH. By contrast, in rodent hepatocytes and in human hepatoma cell lines, ethanol up-regulates the LCFA uptake Vmax. Consequently, although plasma LCFA are unaltered, hepatocellular LCFA uptake in ethanol-fed rats is also increased~3-fold, leading to increased ROS generation and evolution of alcoholic hepatitis. Thus, while increased hepatic LCFA uptake contributes to the pathogenesis of both NASH and alcoholic hepatitis,the underlying mechanisms differ. Recognizing these mechanistic differences is important in developing strategies for both prevention and treatment of these conditions.

The ins and outs of mitochondrial dysfunction in NASH

Rich diet and lack of exercise are causing a surge in obesity, insulin resistance and steatosis, which can evolve into steatohepatitis. Steatosis and nonalcoholic steatohepatitis (NASH) can also be induced by drugs such as amiodarone, tamoxifen and some antiretroviral drugs. There is growing evidence that mitochondrial dysfunction, and more specifically respiratory chain deficiency, plays a role in the pathophysiology of NASH whatever its initial cause. In contrast, the B-oxidation of fatty acids can be either increased (as in insulin resistance-associated NASH) or decreased (as in drug-induced NASH). However, in both circumstances, the generation of reactive oxygen species (ROS) by the damaged respiratory chain is augmented, as components of this chain are over-reduced by electrons, which then abnormally react with oxygen to form increased amounts of ROS. Concomitantly, ROS oxidize fat deposits to release lipid peroxidation products that have detrimental effects on hepatocytes and other hepatic cells. In hepatocytes, ROS and lipid peroxidation products further impair the respiratory chain, either directly or indirectly through oxidative damage to the mitochondrial genome. This, in turn, leads to the generation of more ROS and a vicious cycle ensues. Mitochondrial dysfunction can also lead to apoptosis or necrosis depending on the energy status of the cell. ROS and lipid peroxidation products also activate stellate cells, thus resulting in fibrosis. Finally, ROS and lipid peroxidation increase the generation of several cytokines (TNF-alpha, TGF-B, Fas ligand) that play sundry roles in the pathogenesis of NASH. Recent investigations have shown that some genetic polymorphisms can significantly increase the risk of steatohepatitis and that several drugs can prevent or even reverse NASH. For the next decade, reducing the incidence of NASH will be a major challenge for hepatologists.

Hepatic function and physiology in the newborn

The liver develops from progenitor cells into a well-differentiated organ in which bile secretion can be observed by 12 weeks' gestation. Full maturity takes up to two years after birth to be achieved, and involves the normal expression of signalling pathways such as that responsible for the JAG1 genes (aberrations occur in Alagille's syndrome), amino acid transport and insulin growth factors. At birth, hepatocytes are already specialized and have two surfaces: the sinusoidal side receives and absorbs a mixture of oxygenated blood and nutrients from the portal vein; the other surface delivers bile and other products of conjugation and metabolism (including drugs) to the canalicular network which joins up to the bile ductules. There is a rapid induction of functions such as transamination, glutamyl transferase, synthesis of coagulation factors, bile production and transport as soon as the umbilical supply is interrupted. Anatomical specialization can be observed across the hepatic acinus which has three distinct zones. Zone 1 borders the portal tracts (also known as periportal hepatocytes) and is noted for hepatocyte regeneration, bile duct proliferation and gluconeogenesis. Zone 3 borders the central vein and is associated with detoxification (e.g. paracetamol), aerobic metabolism, glycolysis and hydrolysis and zone 2 is an area of mixed function between the two zones. Preterm infants are at special risk of hepatic decompensation because their immaturity results in a delay in achieving normal detoxifying and synthetic function. Hypoxia and sepsis are also frequent and serious causes of liver dysfunction in neonates. Stem cell research has produced many answers to the questions about liver development and regeneration, and genetic studies including studies of susceptibility genes may yield further insights. The possibility that fatty liver (increasingly recognized as non-alcoholic steatohepatitis or NASH) may have roots in the neonatal period is a concept which may have important long-term implications.