Pierluigi Marzuillo

The association of PNPLA3 variants with liver enzymes in childhood obesity is driven by the interaction with abdominal fat.

Background and Aims A polymorphism in adiponutrin/patatin-like phospholipase-3 gene (PNPLA3), rs738409 C->G, encoding for the I148M variant, is the strongest genetic determinant of liver fat and ALT levels in adulthood and childhood obesity. Aims of this study were i) to analyse in a large group of obese children the role of the interaction of not-genetic factors such as BMI, waist circumference (W/Hr) and insulin resistance (HOMA-IR) in exposing the association between the I148M polymorphism and ALT levels and ii) to stratify the individual risk of these children to have liver injury on the basis of this gene-environment interaction. Methods 1048 Italian obese children were investigated. Anthropometric, clinical and metabolic data were collected and the PNPLA3 I148M variant genotyped. Results Children carrying the 148M allele showed higher ALT and AST levels (p = 0.000006 and p = 0.0002, respectively). Relationships between BMI-SDS, HOMA-IR and W/Hr with ALT were analysed in function of the different PNPLA3 genotypes. Children 148M homozygous showed a stronger correlation between ALT and W/Hr than those carrying the other genotypes (p: 0.0045) and, therefore, 148M homozygotes with high extent of abdominal fat (W/Hr above 0.62) had the highest OR (4.9, 95% C. I. 3.2–7.8, p = 0.00001) to develop pathologic ALT. Conclusions We have i) showed for the first time that the magnitude of the association of PNPLA3 with liver enzymes is driven by the size of abdominal fat and ii) stratified the individual risk to develop liver damage on the basis of the interaction between the PNPLA3 genotype and abdominal fat.

Predicting Metabolic Syndrome in Obese Children and Adolescents: Look, Measure and Ask

Objective: To verify in obese children whether or not the presence of i) high waist-to-height ratio (WHtR), ii) family history for type 2 diabetes (T2D) and iii) acanthosis nigricans (AN), singularly or together, might predict the occurrence of metabolic syndrome or prediabetes. Methods. 1,080 Italian obese children (567 females) were enrolled. Blood pressure, fasting plasma glucose, insulin, and lipids were measured, and oral glucose tolerance test (OGTT) was performed. The WHtR was calculated, family history for T2D was assessed, and the presence of AN was noticed. The odds ratios for showing metabolic syndrome and/or prediabetes according to the presence of these features were calculated. Results: The prevalence of metabolic syndrome was 29.2%. AN (OR1.81; p = 0.002) and WHtR higher than 0.60 (OR 2.24; p < 0.0001) were the clinical signs linked to higher risk for showing metabolic syndrome, and the odds raised significantly when these elements occurred simultaneously (OR 3.34; p < 0.0001). T2D family history (OR 2.36; p = 0.01) and WHtR higher than 0.60 (OR 2.32; p = 0.009) were the two features associated with increased odds of showing prediabetes. Conclusions: Three simple actions, i.e., looking at the patient, asking about T2D family history, and measuring WHtR, may represent a powerful tool in the hands of pediatricians to identify obese children with high cardiovascular and metabolic risk.

TM6SF2 Glu167Lys polymorphism is associated with low levels of LDL-cholesterol and increased liver injury in obese children.

The Glu167Lys (E167K) transmembrane 6 superfamily member 2 (TM6SF2) variant has been associated with liver steatosis, high alanine transaminase (ALT) levels and reduced plasma levels of liver‐derived triglyceride‐rich lipoproteins.

Pediatric non-alcoholic fatty liver disease: New insights and future directions.

One of the most common complications of childhood obesity is the non-alcoholic fatty liver disease (NAFLD), which is the most common form of liver disease in children. NAFLD is defined by hepatic fat infiltration > 5% hepatocytes, as assessed by liver biopsy, in the absence of excessive alcohol intake, viral, autoimmune and drug-induced liver disease. It encompasses a wide spectrum of liver diseases ranging from simple steatosis to non-alcoholic steatohepatitis, which, in turn, can evolve into cirrhosis and end stage liver disease. Obesity and insulin resistance are the main risk factors for pediatric NAFLD. In fact, NAFLD is strongly associated with the clinical features of insulin resistance especially the metabolic syndrome, prediabetes and type 2 diabetes mellitus (T2D). In particular, it has been clearly shown in obese youth that the prevalence of metabolic syndrome, pre-diabetes and type 2 diabetes increases with NAFLD severity progression. Evidence that not all of the obese patients develop NAFLD suggests that the disease progression is likely to depend on complex interplay between environmental factors and genetic predisposition. Recently, a non-synonymous SNP (rs738409), characterized by a C to G substitution encoding an isoleucine to methionine substitution at the amino acid position 148 in the patatin like phospholipase containing domain 3 gene (PNPLA3), has been associated with hepatic steatosis in a multiethnic cohort of adults as well as in children. Another important polymorphisms that acts with PNPLA3 to convey susceptibility to fatty liver in obese youths is the rs1260326 polymorphism in the glucokinase regulatory protein. The pharmacological approach in NAFLD children poorly adherent to or being unresponsive/partially responsive to lifestyle changes, is aimed at acting upon specific targets involved in the pathogenesis. There are some therapeutic approaches that are being studied in children. This article reviews the current knowledge regarding the pediatric fatty liver disease, the new insights and the future directions.

Effect of the rs997509 Polymorphism on the Association between Ectonucleotide Pyrophosphatase Phosphodiesterase 1 and Metabolic Syndrome and Impaired Glucose Tolerance in Childhood Obesity

CONTEXT Variants on the nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP-1) gene have been associated with obesity and insulin resistance. Because insulin resistance is a pivotal factor in the development of metabolic syndrome (MS) and impaired glucose tolerance (IGT), we aimed to test the association between the K121Q and rs997509 ENPP-1 variants with obesity, MS and IGT in obese children and adolescents. METHODS We screened 809 children, 409 obese and 400 lean controls. Obese subjects underwent a standard oral glucose tolerance test, whole body insulin sensitivity index (WBISI) and homeostasis model assessment (HOMA) were calculated. RESULTS No difference in prevalence for K121Q and rs997509 polymorphisms between obese and controls (P > 0.05) were observed. Obese children carrying the rs997509 rare allele showed higher insulin (P = 0.001), HOMA (P < .001) and lower WBISI values (P = 0.04) compared with common allele homozygous. A similar observation was done for K121Q variant, with 121Q allele carriers showing higher insulin (P = 0.03) and HOMA (P = 0.04) values than 121K homozygotes. Moreover, subjects carrying the rs997509 rare allele had higher risk of MS (odds ratio 2.4, 95% confidence interval: 1.3-4.3) and IGT (odds ratio 4.7, 95% confidence interval: 1.9-11.4) than common allele homozygotes. Evaluating combined effects of both polymorphisms, which are in strong linkage disequilibrium, we showed that the effect on insulin sensitivity was due to the rs997509 T variant. CONCLUSION We conclude that the ENPP1 rs997509T allele can predispose obese children to MS and IGT and that this variant might drive the association between the ENPP1 121Q allele and insulin resistance.

Understanding the pathophysiological mechanisms in the pediatric non-alcoholic fatty liver disease: The role of genetics.

Classically, the non-alcoholic fatty liver disease (NAFLD) physiopathology and progression has been summarized in the two hits hypothesis. The first hit is represented by the action of hyperinsulinemia and insulin resistance, accompanying obesity, that leads to liver steatosis increasing the absolute non esterified fatty acids uptake in the liver and the esterification to form triacylglycerol. The oxidative stress is involved in the second hit leading to the progression to nonalcoholic steatohepatitis (NASH) because of its harmful action on steatosic hepatocytes. However, at the present time, the two hits hypothesis needs to be updated because of the discover of genetic polymorphisms involved both in the liver fat accumulation and progression to NASH that make more intriguing understanding the NAFLD pathophysiological mechanisms. In this editorial, we want to underline the role of PNPLA3 I148M, GPR120 R270H and TM6SF2 E167K in the pediatric NAFLD development because they add new pieces to the comprehension of the NAFLD pathophysiological puzzle. The PNPLA3 I148M polymorphism encodes for an abnormal protein which predisposes to intrahepatic triglycerides accumulation both for a loss-of-function of its triglyceride hydrolase activity and for a gain-of-function of its lipogenic activity. Therefore, it is involved in the first hit, such as TM6SF2 E167K polymorphisms that lead to intrahepatic fat accumulation through a reduced very low density lipoprotein secretion. On the other hand, the GPR120 R270H variant, reducing the anti-inflammatory action of the GPR120 receptor expressed by Kuppfer cells, is involved in the second hit leading to the liver injury.

Weight loss allows the dissection of the interaction between abdominal fat and PNPLA3 (adiponutrin) in the liver damage of obese children

Journal of Hepatology 20 group of heterozygous or homozygous subjects for the major allele (p = 0.02 for ALT and p = 0.01 for steatosis). Moreover, after weight loss, no differences among PNPLA3 genotypes were found in ALT levels or in the prevalence of steatosis (p = 0.1 and p = 0.2, respectively). Both the relationships between DBMI SDS and DALT and between DW/Hr and DALT were analysed, based on the different PNPLA3 genotypes, and the slope of the relative regression lines were compared (Fig. 1). Homozygous children for the PNPLA3 minor allele (148M) showed a stronger correlation between DALT and DW/Hr than those carrying the other genotypes, as we observed in the comparison of regression lines (p = 0.002) (Fig. 1A). The same compar-

Paracetamol: a focus for the general pediatrician

Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever in children. This drug has multiple mechanisms of action, but its pharmacodynamic is still not well known. The central nervous system is the main site of action and it mirrors the paracetamol effect compartment. The recommended dosages and routes of administration should be different whether paracetamol is used for the treatment of pain or fever. For example, the rectal route, while being efficacious for the treatment of fever, should be avoided in pain management. Paracetamol is a safe drug, but some clinical conditions and concomitant drugs, which are frequent in clinical practice, may increase the risk of paracetamol toxicity. Therefore, it is important to optimize its administration to avoid overdoses and maximize its effect. The principal mediator of the paracetamol toxicity is the N-acetyl-p-benzo-quinone imine (NAPQI), a toxic product of the paracetamol metabolism, which could bind cysteine groups on proteins forming paracetamol–protein adduct in the liver. Conclusion: Although frequently prescribed, the concept of “effect compartment concentration” and the possible co-factors that could cause toxicity at recommended doses are not familiar to all pediatricians and general practitioners. We reviewed the literature concerning paracetamol mechanisms of action, we highlighted some relevant pharmacodynamic concepts for clinical practice, and we summarized the possible risk factors for toxicity at therapeutic dosages.

Bisphenol A is associated with insulin resistance and modulates adiponectin and resistin gene expression in obese children

Bisphenol A (BPA) exposure has been associated with increased incidence of diabetes and obesity in adults.

Y2 receptor gene variants reduce the risk of hypertension in obese children and adolescents.

Objective To verify whether peptide YY (PYY) and its Y2 receptor (Y2R) gene variants can be associated with obesity or hypertension or both in a cohort of obese children and adolescents. Patients and methods Two hundred and twenty-nine obese children (105 girls, mean z-score BMI 5.1 ± 2.4; mean age 10.5 ± 2.9 years) and 250 age and sex-matched lean controls (130 women, mean z-score BMI 0.5 ± 1.1; mean age 10.3 ± 2.8) were enrolled in the study. Height, weight, BMI, waist circumference and 24-h systolic and diastolic blood pressure were measured. Night-time, day-time and 24-h systolic and diastolic blood pressures were evaluated by 24 h ambulatory blood pressure measurement, and appropriate standard deviation scores according to sex, age and height were calculated. Molecular screening of the PYY and Y2R genes was performed. Results No new mutations were found. We observed three previously described polymorphisms: G767C on PYY and T585C and T936C on Y2R. An association study was carried out in obese patients. No associations were found between the PYY genotypes and the studied phenotypes. The Y2R gene variants, T585C and T936C, which are in almost complete linkage disequilibrium, were found to be associated with night-time, day-time and 24-h systolic and diastolic blood pressures. In particular, subject homozygotes for the T allele showed lower systolic and diastolic blood pressure values compared with the other genotypes. Moreover, obese children homozygous for the T585 allele showed a lower risk of developing hypertension than patients carrying the CC and CT genotypes (χ2 6.9; df = 1, P = 0.03; odds ratio = 0.5, 95% confidence interval: 0.27–0.88). Conclusion Our results suggest that Y2R gene variants are involved in blood pressure regulation in obese children and adolescents.