Rae-Chi Huang

Perinatal and childhood origins of cardiovascular disease

Background:Features of the metabolic syndrome comprise a major risk for cardiovascular disease and will increase in prevalence with rising childhood obesity. We sought to identify early life influences on development of obesity, hypertension and dyslipidemia in children.Methods and results:Cluster analysis was used on a subset of a longitudinal Australian birth cohort who had blood samples at age 8 (n=406). A quarter of these 8-year-olds fell into a cluster with higher body mass index, blood pressure (BP), more adverse lipid profile and a trend to higher serum glucose resembling adult metabolic syndrome. There was a U-shaped relationship between percentage of expected birth weight (PEBW) and likelihood of being in the high-risk cluster. The high-risk cluster had elevated BP and weight as early as 1 and 3 years old. Increased likelihood of the high-risk cluster group occurred with greatest weight gain from 1 to 8 years old (odds ratio (OR)=1.4, 95% confidence interval (CI)=1.3–1.5/kg) and if mothers smoked during pregnancy (OR=1.82, CI=1.05–3.2). Risk was lower if children were breast fed for ⩾4 months (OR=0.6, 95% CI=0.37–0.97). Newborns in the upper two quintiles for PEBW born to mothers who smoked throughout pregnancy were at greatest risk (OR=14.0, 95% CI=3.8–51.1) compared to the nadir PEBW quintile of non-smokers.Conclusion:A U-shaped relationship between birth weight and several components of the metabolic syndrome was confirmed in a contemporary, well-nourished Western population of full-term newborns, but post-natal weight gain was the dominant factor associated with the high-risk cluster. There was a prominence of higher as well as lowest birth weights in those at risk. Future health programs should focus on both pre- and post-natal factors (reducing excess childhood weight gain and smoking during pregnancy), and possibly the greatest benefits may arise from targeting the heaviest, as well as lightest newborns, especially with a history of maternal smoking during pregnancy.

Prospective associations between sugar-sweetened beverage intakes and cardiometabolic risk factors in adolescents

Background: High sugar-sweetened beverage (SSB) consumption is associated with cardiometabolic disturbances in adults, but this relation is relatively unexplored in children and adolescents. Objective: We tested the hypothesis that higher SSB intakes are associated with increases in cardiometabolic risk factors between 14 and 17 y of age. Design: Data were provided by 1433 adolescent offspring from the Western Australian Pregnancy Cohort (Raine) Study. At 14 and 17 y of age, SSB intakes were estimated by using a food-frequency questionnaire; body mass index (BMI), waist circumference, blood pressure, fasting serum lipids, glucose, and insulin were measured, and overall cardiometabolic risk was estimated. Prospective associations between cardiovascular disease risk factors and SSB intake were examined with adjustment for age, pubertal stage, physical fitness, socioeconomic status, and major dietary patterns. Results: The average SSB intake in consumers (89%) was 335 g/d or 1.3 servings/d. Girls who moved into the top tertile of SSB consumption (>1.3 servings/d) between 14 and 17 y of age had increases in BMI (3.8%; 95% CI: 1.8%, 5.7%), increased overweight and obesity risk (OR: 4.8, 95% CI: 2.1, 11.4), and greater overall cardiometabolic risk (OR: 3.2; 95% CI: 1.6, 6.2) (all P-trend ≤ 0.001). Girls and boys who moved into the top tertile of SSB intake showed increases in triglycerides (7.0–8.4%; P-trend ≤ 0.03), and boys showed reductions in HDL cholesterol (−3.1%; 95% CI: −6.2%, 0.1%; P-trend < 0.04) independent of BMI. Some associations were attenuated after adjustment for major dietary patterns. Conclusion: Increased SSB intake may be an important predictor of cardiometabolic risk in young people, independent of weight status.

Synergy Between Adiposity, Insulin Resistance, Metabolic Risk Factors, and Inflammation in Adolescents

OBJECTIVE The purpose of this study was to investigate relationships between inflammatory markers and components of a metabolic syndrome cluster in adolescents. RESEARCH DESIGN AND METHODS This was a cross-sectional analysis of an Australian childhood cohort (n = 1,377) aged 14 years. Cluster analysis defined a “high-risk” group similar to adults with metabolic syndrome. Relevant measures were anthropometry, fasting insulin, glucose, lipids, inflammatory markers, liver function, and blood pressure. RESULTS Of the children, 29% fell into a high-risk metabolic cluster group compared with 2% by a pediatric metabolic syndrome definition. Relative to the “low-risk” cluster, they had higher BMI (95% CI 19.5–19.8 vs. 24.5–25.4), waist circumference (centimeters) (95% CI 71.0–71.8 vs. 83.4–85.8), insulin (units per liter) (95% CI 1.7–1.8 vs. 3.5–3.9), homeostasis model assessment (95% CI 1.7–1.8 vs. 3.5–3.9), systolic blood pressure (millimeters of mercury) (95% CI 110.8–112.1 vs. 116.7–118.9), and triglycerides (millimoles per liter) (95% CI 0.78–0.80 vs. 1.25–1.35) and lower HDL cholesterol (millimoles per liter) (95% CI 1.44–1.48 vs. 1.20–1.26). Inflammatory and liver function markers were higher in the high-risk group: C-reactive protein (CRP) (P < 0.001), uric acid (P < 0.001), alanine aminotransferase (ALT) (P < 0.001), and γ-glutamyl transferase (GGT) (P < 0.001). The highest CRP, GGT, and ALT levels were restricted to overweight children in the high-risk group. CONCLUSIONS Cluster analysis revealed a strikingly high proportion of 14 year olds at risk of cardiovascular disease–related metabolic disorders. Adiposity and the metabolic syndrome cluster are synergistic in the pathogenesis of inflammation. Systemic and liver inflammation in the high-risk cluster is likely to predict diabetes, cardiovascular disease, and nonalcoholic fatty liver disease.

Lifecourse Childhood Adiposity Trajectories Associated With Adolescent Insulin Resistance

OBJECTIVE In light of the obesity epidemic, we aimed to characterize novel childhood adiposity trajectories from birth to age 14 years and to determine their relation to adolescent insulin resistance. RESEARCH DESIGN AND METHODS A total of 1,197 Australian children with cardiovascular/metabolic profiling at age 14 years were studied serially from birth to age 14 years. Semiparametric mixture modeling was applied to anthropometric data over eight time points to generate adiposity trajectories of z scores (weight-for-height and BMI). Fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were compared at age 14 years between adiposity trajectories. RESULTS Seven adiposity trajectories were identified. Three (two rising and one chronic high adiposity) trajectories comprised 32% of the population and were associated with significantly higher fasting insulin and HOMA-IR compared with a reference trajectory group (with longitudinal adiposity z scores of approximately zero). There was a significant sex by trajectory group interaction (P < 0.001). Girls within a rising trajectory from low to moderate adiposity did not show increased insulin resistance. Maternal obesity, excessive weight gain during pregnancy, and gestational diabetes were more prevalent in the chronic high adiposity trajectory. CONCLUSIONS A range of childhood adiposity trajectories exist. The greatest insulin resistance at age 14 years is seen in those with increasing trajectories regardless of birth weight and in high birth weight infants whose adiposity remains high. Public health professionals should urgently target both excessive weight gain in early childhood across all birth weights and maternal obesity and excessive weight gain during pregnancy.

Early infant feeding and adiposity risk: from infancy to adulthood

Introduction: Systematic reviews suggest that a longer duration of breast-feeding is associated with a reduction in the risk of later overweight and obesity. Most studies examining breast-feeding in relation to adiposity have not used longitudinal analysis. In our study, we aimed to examine early infant feeding and adiposity risk in a longitudinal cohort from birth to young adulthood using new as well as published data. Methods: Data from the Western Australian Pregnancy Cohort (Raine) Study in Perth, W.A., Australia, were used to examine associations between breast-feeding and measures of adiposity at 1, 2, 3, 6, 8, 10, 14, 17, and 20 years. Results: Breast-feeding was measured in a number of ways. Longer breast-feeding (in months) was associated with reductions in weight z-scores between birth and 1 year (β = -0.027; p < 0.001) in the adjusted analysis. At 3 years, breast-feeding for <4 months increased the odds of infants experiencing early rapid growth (OR 2.05; 95% CI 1.43-2.94; p < 0.001). From 1 to 8 years, children breast-fed for ≤4 months compared to ≥12 months had a significantly greater probability of exceeding the 95th percentile of weight. The age at which breast-feeding was stopped and a milk other than breast milk was introduced (introduction of formula milk) played a significant role in the trajectory of the BMI from birth to 14 years; the 4-month cutoff point was consistently associated with a higher BMI trajectory. Introduction of a milk other than breast milk before 6 months compared to at 6 months or later was a risk factor for being overweight or obese at 20 years of age (OR 1.47; 95% CI 1.12-1.93; p = 0.005). Discussion: Breast-feeding until 6 months of age and beyond should be encouraged and is recommended for protection against increased adiposity in childhood, adolescence, and young adulthood. Adverse long-term effects of early growth acceleration are fundamental in later overweight and obesity. Formula feeding stimulates a higher postnatal growth velocity, whereas breast-feeding promotes slower growth and a reduced likelihood of overweight and obesity. Biological mechanisms underlying the protective effect of breast-feeding against obesity are based on the unique composition and metabolic and physiological responses to human milk.

DNA methylation of the IGF2/H19 imprinting control region and adiposity distribution in young adults.

BackgroundThe insulin-like growth factor 2 (IGF2) and H19 imprinted genes control growth and body composition. Adverse in-utero environments have been associated with obesity-related diseases and linked with altered DNA methylation at the IGF2/H19 locus. Postnatally, methylation at the IGF2/H19 imprinting control region (ICR) has been linked with cerebellum weight. We aimed to investigate whether decreased IGF2/H19 ICR methylation is associated with decreased birth and childhood anthropometry and increased contemporaneous adiposity.DNA methylation in peripheral blood (n = 315) at 17 years old was measured at 12 cytosine-phosphate-guanine sites (CpGs), analysed as Sequenom MassARRAY EpiTYPER units within the IGF2/H19 ICR. Birth size, childhood head circumference (HC) at six time-points and anthropometry at age 17 years were measured. DNA methylation was investigated for its association with anthropometry using linear regression.ResultsThe principal component of IGF2/H19 ICR DNA methylation (representing mean methylation across all CpG units) positively correlated with skin fold thickness (at four CpG units) (P-values between 0.04 to 0.001) and subcutaneous adiposity (P = 0.023) at age 17, but not with weight, height, BMI, waist circumference or visceral adiposity. IGF2/H19 methylation did not associate with birth weight, length or HC, but CpG unit 13 to 14 methylation was negatively associated with HC between 1 and 10 years. β-coefficients of four out of five remaining CpG units also estimated lower methylation with increasing childhood HC.ConclusionsAs greater IGF2/H19 methylation was associated with greater subcutaneous fat measures, but not overall, visceral or central adiposity, we hypothesize that obesogenic pressures in youth result in excess fat being preferentially stored in peripheral fat depots via the IGF2/H19 domain. Secondly, as IGF2/H19 methylation was not associated with birth size but negatively with early childhood HC, we hypothesize that the HC may be a more sensitive marker of early life programming of the IGF axis and of fetal physiology than birth size. To verify this, investigations of the dynamics of IGF2/H19 methylation and expression from birth to adolescence are required.

Effects of early-life environment and epigenetics on cardiovascular disease risk in children: highlighting the role of twin studies

Cardiovascular disease (CVD) is the leading cause of death worldwide and originates in early life. The exact mechanisms of this early-life origin are unclear, but a likely mediator at the molecular level is epigenetic dysregulation of gene expression. Epigenetic factors have thus been posited as the likely drivers of early-life programming of adult-onset diseases. This review summarizes recent advances in epidemiology and epigenetic research of CVD risk in children, with a particular focus on twin studies. Classic twin studies enable partitioning of phenotypic variance within a population into additive genetic, shared, and nonshared environmental variances, and are invaluable in research in this area. Longitudinal cohort twin studies, in particular, may provide important insights into the role of epigenetics in the pathogenesis of CVD. We describe candidate gene and epigenome-wide association studies (EWASs) and transgenerational epigenetic inheritance of CVD, and discuss the potential for evidence-based interventions. Identifying epigenetic changes associated with CVD-risk biomarkers in children will provide new opportunities to unravel the underlying biological mechanism of the origins of CVD and enable identification of those at risk for early-life interventions to alter the risk trajectory and potentially reduce CVD incidence later in life.

Supplementation with N-3 long-chain polyunsaturated fatty acids or olive oil in men and women with renal disease induces differential changes in the DNA methylation of FADS2 and ELOVL5 in peripheral blood mononuclear cells.

Background Studies in animal models and in cultured cells have shown that fatty acids can induce alterations in the DNA methylation of specific genes. There have been no studies of the effects of fatty acid supplementation on the epigenetic regulation of genes in adult humans. Methods and Results We investigated the effect of supplementing renal patients with 4 g daily of either n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) or olive oil (OO) for 8 weeks on the methylation status of individual CpG loci in the 5′ regulatory region of genes involved in PUFA biosynthesis in peripheral blood mononuclear cells from men and women (aged 53 to 63 years). OO and n-3 LCPUFA each altered (>10% difference in methylation) 2/22 fatty acid desaturase (FADS)-2 CpGs, while n-3 LCPUFA, but not OO, altered (>10%) 1/12 ELOVL5 CpGs in men. OO altered (>6%) 8/22 FADS2 CpGs and (>3%) 3/12 elongase (ELOVL)-5 CpGs, while n-3 LCPUFA altered (>5%) 3/22 FADS2 CpGs and 2/12 (>3%) ELOVL5 CpGs in women. FADS1 or ELOVL2 methylation was unchanged. The n-3 PUFA supplementation findings were replicated in blood DNA from healthy adults (aged 23 to 30 years). The methylation status of the altered CpGs in FADS2 and ELOVL5 was associated negatively with the level of their transcripts. Conclusions These findings show that modest fatty acid supplementation can induce altered methylation of specific CpG loci in adult humans, contingent on the nature of the supplement and on sex. This has implications for understanding the effect of fatty acids on PUFA metabolism and cell function.

Importance of cardiometabolic risk factors in the association between nonalcoholic fatty liver disease and arterial stiffness in adolescents

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and is regarded as the hepatic manifestation of the metabolic syndrome. In adults, NAFLD is a determinant of arterial stiffness and cardiovascular risk, independent of the metabolic syndrome. Our aim was to ascertain if NAFLD is associated with arterial stiffness, independent of cardiometabolic factors in a population‐based cohort of adolescents. The 17‐year‐olds (n = 964) from an Australian birth cohort had measures of anthropometry, blood pressure, fasting insulin, glucose, lipids, and NAFLD by ultrasound. Two‐step cluster analysis identified youth at high metabolic risk. Measures of arterial stiffness (pulse wave velocity [PWV] and augmentation index corrected for heart rate [AI@75]) were obtained using applanation tonometry. The overall prevalence of NAFLD was 13.3%. The “high risk” metabolic cluster at age 17 years included 16% males and 19% females. Compared to “low risk,” the “high risk” cluster participants had greater waist circumference, triglycerides, insulin, systolic blood pressure, and lower high‐density lipoprotein (HDL) cholesterol (all P < 0.0001). Those who had NAFLD but were not in the “high risk” metabolic cluster did not have increased PWV or AI@75. However, males and females who had NAFLD in the presence of the metabolic cluster had greater PWV (b = 0.20, 95% confidence interval [CI] 0.01 to 0.38, P = 0.037). Males who had NAFLD in the presence of the metabolic cluster had greater AI@75 (b = 6.3, 95% CI 1.9 to 10.7, P = 0.005). Conclusion: NAFLD is only associated with increased arterial stiffness in the presence of the “high risk” metabolic cluster. This suggests that arterial stiffness related to the presence of NAFLD is predicated on the presence of an adverse metabolic profile in adolescents. (Hepatology 2013;58:1306–1314)

Extent of metabolic risk in adolescent girls with features of polycystic ovary syndrome

OBJECTIVE To determine prevalence of metabolic syndrome in adolescents with polycystic ovary syndrome (PCOS) and derive features suggestive of propensity for development of metabolic syndrome. DESIGN Prospective cohort study. SETTING Population-based cohort of adolescents in Western Australia. PARTICIPANT(S) Metabolic data from 1,377 children aged 14 years, features of PCOS obtained from 244 girls aged 14 to 17 years. INTERVENTION(S) Assessment for features of PCOS and subsequent fasting blood samples. MAIN OUTCOME MEASURE(S) Relationship between features of PCOS and features of metabolic syndrome. RESULT(S) With use of five definitions of metabolic syndrome the maximal prevalence of metabolic syndrome recorded was 11.8% in girls with PCOS (National Institutes of Health [NIH]) and 6.6% (Rotterdam) (non-PCOS 0.6% and 0.7%, respectively). With use of cluster analysis of metabolic risk (a technique to cluster the adolescents according to multidimensional relationships of established cardiovascular risk factors), 35.3% with PCOS-NIH were at risk for metabolic syndrome and 26.2% with PCOS-Rotterdam (non-PCOS 15.4% and 15.4%, respectively). Menstrual irregularity and high free T (PCOS-NIH) were associated with high metabolic syndrome risk (odds ratio 3.00, confidence interval 1.3-6.4), not after controlling for body mass index. Of PCOS features, an elevated free T level was most predictive of insulin resistance. Menstrual irregularity and polycystic ovary morphology were not associated with insulin resistance (56.3% vs. 52.9% and 60.0% vs. 34.4%, respectively). CONCLUSION(S) Despite the low prevalence of metabolic syndrome in girls with PCOS, one third have features putting them at high risk for development of metabolic syndrome.