Anna Prats-Puig

Changes in Circulating MicroRNAs Are Associated With Childhood Obesity

CONTEXT Circulating microRNAs (miRNAs) are valuable biomarkers of metabolic diseases and potential therapeutic targets in this field. OBJECTIVE Our objective was to define the circulating pattern of miRNAs in childhood obesity. DESIGN, SETTINGS, AND MAIN OUTCOME MEASURE: The genome-wide circulating miRNA profile was assessed by RT-PCR in 10 boys (5 lean and 5 obese children). The most relevant miRNAs were cross-sectionally validated in 85 lean versus 40 obese children (63 boys and 62 girls) and longitudinally evaluated in samples from the same children when they were ≈ 7 and ≈ 10 years old (23 boys and 22 girls). RESULTS The cross-sectional validation study disclosed that 15 specific circulating miRNAs were significantly deregulated in prepubertal obesity, including the decreased miR-221 and miR-28-3p and increased concentrations in plasma of miR-486-5p, miR-486-3p, miR-142-3p, miR-130b, and miR-423-5p (all P < .0001). The circulating concentration of these miRNAs was significantly associated with body mass index and other measures of obesity such as percent fat mass, waist, regional fat distribution and with laboratory parameters such as homeostasis model assessment of insulin resistance, high-molecular-weight adiponectin, C-reactive protein, and circulating lipids in concordance with anthropometric associations. Plasma concentrations of 10 of these circulating miRNAs changed significantly and differently during the 3-year follow-up in children who increased or decreased their normalized weight. CONCLUSION This study provides the first evidence that circulating miRNAs are deregulated in prepubertal obese children. Thus, the very early detection of an abnormal circulating miRNA profile may be a promising strategy to identify obese children who may suffer from metabolic abnormalities.

Carboxylation of osteocalcin affects its association with metabolic parameters in healthy children.

OBJECTIVE Osteocalcin (OC), a bone-derived protein, was recently shown to regulate metabolic pathways in mice. Undercarboxylated OC (ucOC), but not carboxylated OC (cOC), increases adiponectin and insulin secretion. It is unclear if carboxylation of OC affects its association with metabolic parameters in humans. RESEARCH DESIGN AND METHODS The associations between ucOC, cOC, total and high-molecular-weight (HMW) adiponectin, and insulin secretion (homeostasis model assessment [HOMA]-β) were investigated in a population-based sample of healthy prepubertal children (n = 103; 49 boys and 54 girls). RESULTS Weight-dependent associations were observed between the different forms of OC and metabolic parameters. Higher cOC was related to lower HMW adiponectin (with a stronger association in leaner children; P < 0.001). Higher ucOC-to-cOC ratio was associated with higher HOMA-β (P < 0.01) in leaner children and associated with higher HMW adiponectin (P < 0.001) in heavier children. CONCLUSIONS In a weight-dependent manner, cOC and the proportion of ucOC are differentially related to HMW adiponectin and insulin secretion in healthy children.

Lower Free Thyroxin Associates with a Less Favorable Metabolic Phenotype in Healthy Pregnant Women

CONTEXT A lower free T(4) (fT4), within the euthyroid range, has been shown in adults to associate with an adverse metabolic phenotype. Thyroid physiology changes significantly during gestation and affects maternal and fetal well-being. OBJECTIVE The aim of the study was to test the hypothesis that a lower serum fT4 in healthy euthyroid pregnant women is related to a less favorable metabolic phenotype and to fetal or placental weight. DESIGN, SETTING, PATIENTS, AND OUTCOME MEASURES: We examined associations of thyroid function tests (TSH and fT4) and the free T(3) (fT3)-to-fT4 ratio (as a proxy of deiodinase activity) with a metabolic profile [preload and postload glucose, glycosylated hemoglobin (HbA1c), high molecular-weight (HMW)-adiponectin, homeostasis model of assessment for insulin resistance (HOMA-IR), and serum lipids] in 321 healthy pregnant women. All women were euthyroid and had negative anti-thyroid peroxidase antibodies. None received thyroid hormone replacement. Blood tests were performed in women between 24 and 28 wk gestation. Placentas and newborns were weighed at birth. RESULTS Circulating TSH did not relate to metabolic parameters, but decreasing fT4 and increasing fT3-to-fT4 ratio associated with a less favorable metabolic phenotype, as judged by higher postload glucose, HbA1c, fasting insulin, HOMA-IR, and triglycerides, and by a lower HMW-adiponectinemia (all P ≤ 0.005). In multiple regression analyses, fT4 was independently associated with HbA1c (β = -0.135; P = 0.038), HMW-adiponectin (β = 0.218; P < 0.001), and placental weight (β = -0.185; P < 0.005), whereas the fT3-to-fT4 ratio was independently associated with maternal body mass index (β = 0.265; P < 0.001), HMW-adiponectinemia (β = -0.237; P < 0.002), HOMA-IR (β = 0.194; P = 0.014), and placental weight (β = 0.174; P = 0.020). CONCLUSION In pregnant women without a history of thyroid dysfunction, lower concentrations of fT4 and a higher conversion of fT4 to fT3, as inferred by changes in the fT3-to-fT4 ratio, were found to be associated with a less favorable metabolic phenotype and with more placental growth.

Altered Circulating miRNA Expression Profile in Pregestational and Gestational Obesity

CONTEXT MicroRNAs (miRNAs) are valuable circulating biomarkers and therapeutic targets for metabolic diseases. OBJECTIVE The objective of the study was to define the pattern of circulating miRNAs in pregestational and gestational obesity and to explore their associations with maternal metabolic parameters and with markers for pre- and postnatal growth. design, settings, and main outcome measure: TaqMan low-density arrays were used to profile plasma miRNAs in six women with pregestational obesity (PregestOB), six with gestational obesity (GestOB), and six with normal pregnancies (control) during the second trimester of gestation. The most relevant miRNAs were validated in 70 pregnant women (20 PregestOB, 25 GestOB, and 25 control). Maternal metabolic parameters including glucose, glycated hemoglobin, homeostasis model assessment index of insulin resistance, C-peptide, and lipids were assessed. Placentas were weighed at delivery and newborns also during 6 months of life. RESULTS We identified 13 circulating miRNAs differentially expressed in maternal obesity, including decreased levels of miR-29c, miR-99b, miR-103, miR-221, and miR-340 and increased levels of miR-30a-5p, miR-130a, and miR-150 in GestOB; and decreased levels of miR-122, miR-324-3p, miR-375, and miR-652 and increased levels of miR-625 in both PregestOB and GestOB (P < .05 to P < .0001 vs control). Decreased levels of several of these miRNAs associated with a more adverse maternal metabolic status (more pregnancy weight gain, glucose, glycated hemoglobin, homeostasis model assessment index of insulin resistance, C-peptide, and triacylglycerol and less high density lipoprotein cholesterol), with more placental weight, weight at birth, and weight at 6 months of life (all P < .05 to P < .001). CONCLUSIONS This study provides the first identification of altered circulating miRNAs in maternal obesity and suggests a possible role of such miRNAS as markers for pre- and postnatal growth.

Toward an Early Marker of Metabolic Dysfunction: Omentin‐1 in Prepubertal Children

Omentin‐1 is a recently recognized adipokine primarily originating in visceral adipose tissue. We posited that circulating omentin‐1 could be an early marker of metabolic dysfunction. To this end, we examined the associations between circulating omentin‐1, body fat (bioelectric impedance), an endocrine‐metabolic profile (homeostasis model assessment for insulin resistance (HOMAIR), serum lipids, high‐molecular‐weight (HMW) adiponectin and blood pressure (BP)) and family history of obesity and diabetes in asymptomatic prepubertal children (n = 161; 77 boys and 84 girls; age 7 ± 1 year) with a normal distribution of height and weight. Increased circulating omentin‐1 was associated with a poorer metabolic profile, with relatively higher HOMAIR, fasting triacylglycerol, BP and familial prevalence of diabetes (all P < 0.005 to P < 0.0001), and relatively lower fraction of HMW adiponectin (P < 0.005), whereas no relationship was found with body weight or fat or with family history of obesity. All these associations were independent of age, gender and fat mass. In conclusion, circulating omentin‐1 may become a marker of metabolic dysfunction integrating insulin sensitivity, markers of adipose‐tissue metabolism and BP as early as in prepubertal childhood.

Placental FTO expression relates to fetal growth

Objective:The fat mass and obesity-associated gene (FTO) participates in the control of postnatal weight gain. We assessed whether FTO is expressed in human placenta and whether such expression relates to prenatal weight gain and to the rs9939609 single nucleotide polymorphism (SNP) in FTO.Design and subjects:In a birth cohort study, placentas from women (n=147) with an uncomplicated, singleton, term pregnancy were weighed at delivery. Real-time PCR was used to study, in placental tissue, the expression of FTO and of housekeeping genes (TATA box binding protein and succinate dehydrogenase complex, subunit A) and to genotype the rs9939609 SNP in FTO. Weights and lengths of the newborns were measured; circulating insulin and insulin-like growth factor-I (IGF-I) were quantified in cord blood.Results:FTO was highly expressed in placenta and was associated with increased fetal weight and length (P<0.001 to P<0.0001). Maternal parity showed an interaction (P<0.001) in the association between placental FTO expression and placental weight. Placental FTO mRNA expression was associated with increased fetal-to-placental weight ratio (P<0.005) in infants from primiparous women, and was associated with increased fetal weight and length and placental weight (P<0.001 to P<0.0001) in infants from nonprimiparous women. These associations were not explained by either cord insulin or IGF-I. Placental FTO expression was unrelated to placental FTO rs9939609 SNPConclusion:FTO is expressed in the human placenta. In a maternal parity-dependent manner, placental FTO may participate either in the control of fetal weight gain or in the partitioning between placental and fetal growth.

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.

Undercarboxylated osteocalcin relates to cardiovascular risk markers in offspring of families with metabolic syndrome

BACKGROUND The undercarboxylated form of osteocalcin (ucOC) is an emerging marker of cardiovascular disease. It is unknown if ucOC in related to common cardiovascular risk markers in children. In offspring of families with and without metabolic syndrome (MetS+ and MetS- families), we assessed whether ucOC was related to a continuous metabolic syndrome score (MetS score) and to carotid intima-media thickness (cIMT). METHODS ucOC and total OC, MetS score and cIMT were assessed in 203 asymptomatic prepubertal children (age 7.6 ± 0.1 yr; 49% girls), of whom 99 were from MetS+ families. RESULTS In children from MetS+ families, percent ucOC was higher than in children from MetS- families (p < 0.01). In offspring from MetS+ families, higher ucOC and especially higher percent ucOC was independently associated with both the MetS score and cIMT (both p ≤ 0.01). CONCLUSIONS The undercarboxylated form of OC is related to common cardiovascular risk markers in children at risk for cardiovascular disease.

Carotid Intima-Media Thickness at 7 Years of Age: Relationship to C-Reactive Protein Rather than Adiposity

OBJECTIVE According to the concept of adipose tissue expandability, the vascular complications of obesity are related less to the amount of stored fat than to the low-grade inflammation that excess fat storage may elicit. We tested this concept in 7-year-old children by assessing whether carotid intima-media thickness (cIMT) is related to obesity measures or to circulating highly sensitive C-reactive protein (hsCRP), as a marker of low-grade inflammation. STUDY DESIGN The study group comprised 135 asymptomatic Caucasian children (72 girls and 63 boys; mean age, 7.1±1.1 years) with normal height and weight distributions. Relationships were assessed among cIMT, hsCRP, obesity measures (ie, body mass index [BMI], total fat by bioelectric impedance, and visceral fat by ultrasound), insulin resistance (by the homeostasis model assessment for insulin resistance), and fasting serum lipid levels. RESULTS cIMT was correlated with hsCRP, but not with BMI or body fat; the regression coefficients between cIMT and hsCRP (adjusted for age, sex, BMI, body fat, and serum lipid levels) were fairly similar across all BMI categories (β=0.370-0.411; all P<.001 to<.0001). Serum hsCRP increased with increasing BMI, total fat, and visceral fat (all P<.001). CONCLUSION At age 7 years, cIMT is already associated with low-grade inflammation, as measured by hsCRP, but not with BMI or body fat. These findings imply that public health strategies aimed at early prevention of cardiovascular disease may need to target low-grade inflammation rather than only BMI or adiposity.

Relative Hypoadiponectinemia, Insulin Resistance, and Increased Visceral Fat in Euthyroid Prepubertal Girls With Low-Normal Serum Free Thyroxine

A lower activity of the thyroid axis within the clinical reference range is related to a dysmetabolic phenotype in adult populations. We posited that such an association is already present as early as in prepubertal childhood. Serum thyroid stimulating hormone (TSH) and free T4, body fat (bioelectric impedance), insulin resistance (homeostasis model assessment of insulin resistance (HOMAIR)), total and high molecular weight (HMW)‐adiponectin and serum lipids were assessed in 234 euthyroid prepubertal children (113 boys and 121 girls) attending primary care clinics. Visceral fat (abdominal ultrasound) was measured in a subset of these subjects (n = 147; 74 boys and 73 girls). Explants of visceral adipose tissue from an additional six prepubertal children (three boys and three girls) were used to study the regulation of total and HMW‐adiponectin by thyroid hormone. Serum free T4 was in girls independently associated with HMW‐adiponectin, HOMAIR and visceral fat, so that circulating HMW‐adiponectin decreased by 30% (β = 0.305 P < 0.005, R2 = 0.13) and HOMAIR and visceral fat increased, respectively, by 90% (β = −0.255 P < 0.01, R2 = 0.05) and 30% (β = −0.369, P < 0.005, R2 = 0.12) from the highest to the lowest tertile of serum free T4. Nonsignificant differences in these parameters were found in boys. Treatment of visceral fat explants with thyroid hormone increased total and HMW‐adiponectin by 70% and 53%, respectively, above control values (P < 0.01). In conclusion, a dysmetabolic phenotype, consisting of relative hypoadiponectinemia, insulin resistance and increased visceral fat, is associated with low‐normal serum free thyroxine in euthyroid prepubertal girls. These associations may be partly explained by a positive regulation of HMW‐adiponectin secretion by thyroid hormone.