Perirenal fat is related to carotid intima-media thickness in children.

BACKGROUND/OBJECTIVES: It is well known that increased abdominal fat is associated with cardiovascular (CV) risk. Perirenal fat has been recently associated with CV risk in adults. However, studies with children are lacking. We investigated the relationship of perirenal fat and other abdominal fat depots (including preperitoneal, intra-abdominal and subcutaneous fat) with carotid intima-media thickness (cIMT-a surrogate marker of CV risk) in prepubertal children, so as to identify novel markers that can be easily assessed and used in the early prevention of cardiovascular disease. SUBJECTS/METHODS: Subjects were 702 asymptomatic prepubertal Caucasian children (418 lean, 142 overweight and 142 obese) who were recruited in a primary care setting. Ultrasound measurements (perirenal, preperitoneal, intra-abdominal and subcutaneous fat and cIMT), clinical (body mass index (BMI) and systolic blood pressure) and metabolic parameters (insulin resistance (HOMA-IR), high molecular weight (HMW) adiponectin and serum lipids) were assessed. RESULTS: Perirenal fat was associated with diverse metabolic and CV risk factors in all the studied subjects. However, in overweight and obese children, perirenal fat was mostly associated with cIMT (P<0.001) and was the only fat depot that showed independent associations with cIMT in multivariate analyses (overweight chidren: ß=0.250, P=0.003, r2=12.8%; obese children: ß=0.254, P=0.002, r2=15.5%) after adjusting for BMI, gender, age and metabolic parameters. Perirenal fat was also the only fat depot that showed independent associations with HMW-adiponectin in obese children (ß=-0.263, P=0.006, r2=22.8%). CONCLUSIONS: Perirenal fat is the main abdominal fat depot associated with cIMT, especially in overweight and obese children, and may thus represent a helpful parameter for assessing CV risk in the pediatric population.

The macrophage activation product sCD163 is associated with a less favourable metabolic profile in prepubertal children.

OBJECTIVE: Macrophages are known to be involved in low-grade inflammatory processes such as obesity. soluble cluster of differentiation 163 (sCD163) is shed from the cell surface as specific macrophage activation marker. In prepubertal children, we studied if circulating sCD163 is associated with metabolic and cardiovascular risk markers. METHODS: A population of 236 school-aged Caucasian children (111 girls and 125 boys) aged 8 ± 1 year [81 normal weight (body mass index [BMI]-SDS < 1); 74 overweight (1 ≤ BMI-standard deviation score [SDS] < 2) and 81 with obesity (BMI-SDS ≥ 2)] were studied. BMI, waist circumference, fat mass and visceral fat were measured. Fasting serum sCD163, homeostatic model assessment of insulin resistance, high sensitivity C-reactive protein, gamma-glutamyl transpeptidase and lipids were quantified. RESULTS: Circulating sCD163 concentrations were higher in children with obesity (p < 0.0001). Associations were observed between circulating sCD163 and a less favourable metabolic profile as judged by higher waist circumference, fat mass, visceral fat, epicardial fat, homeostatic model assessment of insulin resistance, high sensitivity C-reactive protein, gamma-glutamyl transpeptidase and triglycerides (all between r = 0.173 and r = 0.363; p < 0.05 to p < 0.0001) and lower high-density lipoprotein-cholesterol (r = -0.285, p < 0.0001). In multiple regression analyses, circulating sCD163 was independently associated with HOMA-IR (ß = 0.162, p = 0.016; model R2 = 0.179) and high density lipoprotein-cholesterol/triglycerides ratio (ß = -0.167, p = 0.012; model R2 = 0.209). CONCLUSIONS: Childhood obesity may increase the risk of developing metabolic diseases later in life through chronic macrophage activation having deleterious effects on metabolism.

Uric acid, carotid intima-media thickness and body composition in prepubertal children.

BACKGROUND: Increased uric acid is an independent biomarker for cardiovascular disease in obese adolescents and adults. OBJECTIVE: We investigated whether uric acid relates to carotid intima-media thickness (cIMT) in prepubertal children, and whether body mass index (BMI) and preperitoneal fat modulate this association. METHODS: 359 asymptomatic prepubertal Caucasian children were stratified according to BMI categories (171 with BMI-SDS < 0; 188 with BMI-SDS ≥ 0) and according to preperitoneal fat levels (180 with preperitoneal fat <50th centile; 179 with preperitoneal fat >50th centile). Uric acid levels, insulin resistance (homeostasis model assessment insulin resistance; HOMA-IR), C-reactive protein (CRP), triacylglycerol (TG), systolic blood pressure (SBP), abdominal fat and cIMT (both by ultrasound) were assessed. RESULTS: Uric acid was associated with several cardiovascular risk factors, namely higher HOMA-IR, CRP, TG, BMI, waist, SBP, preperitoneal fat and cIMT (all P < 0.001 to P < 0.0001). Significant BMI and preperitoneal fat interactions were documented in the relationship between uric acid and cIMT (both P < 0.05), as uric acid was preferentially related to cIMT in heavier children (ß = 0.247, P < 0.001, r(2) = 9.1%) and in children with more preperitoneal fat (ß = 0.263, P < 0.0001, r(2) = 11.9%). CONCLUSIONS: Serum uric acid is associated with cIMT in asymptomatic prepubertal children. Both higher BMI and preperitoneal fat aggravate the potential risk of atherosclerotic disease imposed by higher concentrations of uric acid.

Variations in the obesity genes FTO, TMEM18 and NRXN3 influence the vulnerability of children to weight gain induced by short sleep duration.

OBJECTIVE: Shorter sleep duration predisposes to obesity, but the mechanisms whereby sleep deprivation affects body weight are poorly understood. We tested whether this association is modulated by the obesity genes FTO, TMEM18 and NRXN3. SUBJECTS: Body mass index (BMI), waist circumference, visceral fat (abdominal ultrasound), homeostasis model assessment for insulin resistance (HOMA-IR), systolic blood pressure (SBP) and sleep time per 24 h were assessed in 297 asymptomatic children (151 boys, 146 girls; age range 5-9 years; BMI s.d. score range -2.0-4.0). Associations between sleep duration and the abovementioned outcomes were tested for three common single-nucleotide polymorphisms (SNPs), namely FTO (rs9939609), TMEM 18 (rs4854344) and NRXN3 (rs10146997), as well as for their combination. RESULTS: TT homozygotes (but not A(*) carriers) for the FTO SNP, exhibited nominal associations between decreasing sleep duration and increasing BMI, waist circumference, visceral fat and HOMA-IR (all P<0.05). Similar associations were observed in children with risk alleles (but not in those without risk alleles) for the TMEM18 and NRXN3 SNPs (P<0.05 to P<0.0001). The three SNPs had additive effects on the negative associations between sleep and, respectively, BMI (P<0.001), waist (P<0.005), visceral fat (P<0.001), HOMA-IR (P=0.010) and SBP (P<0.0005). The combined effects on obesity measures and SBP remained significant after correction for multiple testing. On average, 2 h of sleep less per night was associated with an increase in BMI of 1.0 s.d. (95% confidence interval 0.5-1.6 s.d.) and with 8.0 cm (95% confidence interval 3.6-12.2 cm) more waist circumference in genetically susceptible children. CONCLUSION: By age 7, common variations in FTO, TMEM18 and NRXN3 influence the vulnerability to metabolic complications of sleep deprivation. Further genetic studies are warranted to replicate these findings in other populations.