High plasma concentration of remnant lipoprotein cholesterol in obese children and adolescents

Reduced Sensitivity to Thyroid Hormones Is Associated With High Remnant Cholesterol Levels in Chinese Euthyroid Adults

CONTEXT

It remains unclear whether the thyroid system could regulate the atherogenic remnant cholesterol (RC) levels in euthyroid status.

OBJECTIVE

We aimed to investigate the relationship between sensitivity to thyroid hormones and RC levels in Chinese euthyroid population.

METHODS

This study included 18 766 euthyroid adults. High RC levels were defined as the upper quartile of RC levels. The thyroid hormone sensitivity indices, including thyroid feedback quantile-based index (TFQI), thyroid-stimulating hormone index (TSHI), thyrotrophic thyroxine resistance index (TT4RI), and free triiodothyronine to free thyroxine (FT3/FT4) ratio were calculated. Linear and binary logistic regression analysis were applied to determine the associations between those composite indices with RC levels by genders.

RESULTS

Both females and males with high RC levels exhibited co-existing higher TSH and FT4 levels. Linear regression analysis revealed that TFQI, TSHI, and TT4RI were positively, while FT3/FT4 ratio levels were negatively associated with serum RC levels. The odds ratios (ORs) (95% CI) for high RC levels were increased with rising TFQI quartiles (Q) [females: Q3 1.41 (1.22-1.63), Q4 1.61 (1.39-1.86); males: Q3 1.25 (1.09-1.45), Q4 1.38 (1.19-1.59), all P for trend < 0.001] after full adjustment, with Q1 as the reference. TSHI and TT4RI yielded similar results. By contrast, the ORs (95% CI) for high RC levels were decreased with increasing FT3/FT4 ratio quartiles in both genders (P for trend < 0.001).

CONCLUSION

In euthyroid adults, reduced sensitivity to thyroid hormones was associated with high RC levels. Our results suggested an additive cardiometabolic risk of euthyroid population with thyroid hormones insensitivity.

The relationship of remnant cholesterol and abdominal obesity in children: A cross-sectional study

Background

Previous studies found that remnant cholesterol (RC) is a risk factor for cardiovascular diseases and childhood obesity is associated with cardiometabolic diseases. This study aimed to explore the relationship between RC and abdominal obesity in children.

Methods

A total of 5,959 children, aged 6−12 years old, were selected from a cross-sectional study in urban-rural areas of Chongqing, China. RC was calculated by total cholesterol (TC)—high-density lipoprotein (HDL-C) cholesterol—low-density lipoprotein (LDL-C) cholesterol and was divided into four groups by quartiles (Q1–Q4).

Results

Compared to children with the lowest RC (Q1), children with higher RC had significantly higher odds of abdominal obesity (Q2: OR = 1.450, 95% CI: 1.131−1.859, p < 0.05; Q3: OR = 2.127, 95% CI: 1.632−2.772, p < 0.001; Q4: OR = 2.386, 95% CI: 1.819−3.130, p < 0.001). In the stratified analyses by urban-rural areas, the odds ratios were greater in rural areas (Q2: OR = 2.228, 95% CI: 1.572−3.160, p < 0.001; Q3: OR = 3.668, 95% CI: 2.191−6.140, p < 0.001; Q4: OR = 6.490, 95% CI: 2.271−18.551, p < 0.001) than in urban areas (Q2: OR = 1.644, 95% CI: 1.192−2.266, p < 0.05; Q3: OR = 2.266, 95% CI: 1.667−3.082, p < 0.001; Q4: OR = 2.711, 95% CI: 2.005−3.665, p < 0.001).

Conclusions

Our study found that RC was positively correlated with abdominal obesity in children, and this association was higher for children living in rural areas.

Elevated Serum Concentrations of Remnant Cholesterol Associate with Increased Carotid Intima-Media Thickness in Children and Adolescents

OBJECTIVE

To evaluate the relationship between remnant cholesterol and carotid intima-media thickness (cIMT), a surrogate marker for atherosclerosis, in children and adolescents.

STUDY DESIGN

Anthropometric, laboratory, liver, and carotid ultrasonographic data were obtained from 767 youths (594, overweight/obese; 173, normal weight). Fasting remnant cholesterol was calculated from the standard lipid profile. cIMT ≥0.56 mm (corresponding to the 90th percentile of values observed in normal-weight children) was chosen to define elevated cIMT. Logistic regression analysis was used to estimate the risk of elevated cIMT according to tertiles of remnant cholesterol levels.

RESULTS

In the entire cohort, the mean concentration of remnant cholesterol was 17.9 ± 10.3 mg/dL and mean cIMT value was 0.51 ± 0.8 mm. Remnant cholesterol significantly correlated with age, sex, body mass index, waist circumference, blood pressure, lipids, liver enzymes, and insulin resistance. cIMT value increased progressively with rising remnant cholesterol tertiles (P_{for trend} < .001). Compared with subjects in the lowest remnant cholesterol tertile, those in the middle and highest remnant cholesterol tertiles had a 2.3- and 2.4-fold increased risk of elevated cIMT, independently of age, sex, pubertal stage, body mass index, and apolipoprotein B (all P_adj ≤ .003). When the effects of overweight/obesity on the association between remnant cholesterol and cIMT were determined, normal-weight as well as overweight/obese subjects in the highest remnant cholesterol tertile had a 3.8- and 2.3-fold increased risk to have elevated cIMT compared with the respective study groups in the lowest tertile, after adjustment for conventional risk factors (P_adj = .038 and P_adj = .003, respectively).

CONCLUSIONS

In youths, elevated levels of remnant cholesterol might represent a marker of early atherosclerotic damage.

Epidemiology of Childhood Obesity in Korea

Over the past several decades, the prevalence of obesity has increased dramatically worldwide and is increasing not only in developed countries, but also in developing countries. This increase may lead to an increase in the incidence of chronic diseases throughout the lifespan. In Korean children and adolescents, the prevalence of obesity increased from 6.8% in 1998 to 10.0% in 2013. Obesity is a state that more commonly influences children and adolescents of lower socioeconomic status (SES) than those with a higher SES. However, the prevalence of metabolic syndrome in a nationally representative sample of Korean adolescents decreased from 1998 to 2012. According to the Diabetes Fact Sheet of the Korean Diabetes Association, the prevalence of type 2 diabetes among children aged 18 years or younger was 153.5 per 100,000 in 2006 and 205.0 per 100,000 in 2013. Obesity is a complex disease influenced by many interacting factors, such as adipocytokines, lipopolysaccharide-binding protein, adenovirus 36 infection, birth weight, lifestyle, and endocrine-disrupting chemicals. Obesity in youth can adversely impact practically every organ system and lead to serious consequences, such as metabolic, gastrointestinal, pulmonary, cardiovascular, and psychosocial complications. Therefore, coordinated efforts by governments, organizations, communities, and individuals are needed to prevent and treat childhood obesity. In particular, a long-term policy to improve the social environment will also be necessary.

Apolipoprotein E synthesized by adipocyte and apolipoprotein E carried on lipoproteins modulate adipocyte triglyceride content

Excessive energy storage of adipose tissue makes contribution to the occurrence and progression of obesity, which accompanies with multiple adverse complications, such as metabolic syndrome, cardiovascular diseases. It is well known that apolipoprotein E, as a component of lipoproteins, performs a key role in maintaining plasma lipoproteins homeostasis. Interestingly, apolipoprotein E is highly expressed in adipocyte and has positive relation with body fat mass. Apolipoprotein E knock-out mice show small fat mass compared to wild type mice. Moreover, adipocyte deficiency in apolipoprotein E shows impaired lipoproeteins internalization and triglyceride accumulation. Apolipopreotein E-deficient lipoproteins can not induce preadipocyte to form round full-lipid adipocyte, whereas apolipoprotein E-containing lipoproteins can. This article mainly reviews the modulation of apolipoprotein E synthesized by adipocyte and apolipoprotein E carried on lipoproteins in adipocyte triglyceride content.

Differential significance of plasma visfatin concentrations according to adiposity in children and adolescents

BACKGROUND/AIMS

Visfatin is an adipocytokine predominantly expressed in visceral adipose tissue. We examined the relationship between plasma visfatin concentrations and anthropometric and metabolic parameters in children and adolescents, who are relatively less influenced by the effects of accompanying disease.

METHODS

We studied 135 children and adolescents (8-16 years old). Plasma glucose, insulin, lipid profile, visfatin and other adipocytokine levels were measured. CT scans were performed to evaluate the distribution of abdominal fat. We analyzed the relationship between circulating visfatin levels and anthropometric and metabolic parameters according to central adiposity (total abdominal fat by CT scan).

RESULTS

In the lower-adiposity group, plasma visfatin concentrations were significantly correlated with total abdominal fat, visceral fat, subcutaneous abdominal fat, plasma triglyceride level and homeostasis model assessment of insulin resistance (HOMA-IR). In a multiple linear regression analysis, visceral fat and triglycerides were independently associated with plasma visfatin levels. In the higher-adiposity group, plasma visfatin concentrations were not correlated with visceral fat or HOMA-IR but were significantly correlated with circulating interleukin-6 levels.

CONCLUSION

These data suggest that the relationship between plasma visfatin concentrations and metabolic parameters differs according to central adiposity and that plasma visfatin concentrations are correlated with visceral fat and triglyceride levels, especially in children and adolescents with lower adiposity.

Apolipoprotein B/A1 ratio is associated with free androgen index and visceral adiposity and may be an indicator of metabolic syndrome in male children and adolescents

OBJECTIVE

A high apolipoprotein B/apolipoprotein A1 (apoB/A1) ratio is strongly associated with cardiometabolic diseases. However, few studies have examined this ratio in children and adolescents. The aim of our study was to determine significant factors related to the apoB/A1 ratio and examine its association with paediatric metabolic syndrome.

PATIENTS AND METHODS

Sixty-seven male children and adolescents were recruited. We measured anthropometric parameters, fat areas by abdominal computed tomography, fasting glucose, insulin, lipid profiles, apoB, apoA1, adiponectin, free androgen index (FAI) and oestradiol.

RESULTS

Thirty per cent of participants (n = 20) were identified as having paediatric metabolic syndrome. The apoB/A1 ratio was significantly correlated with BMI z-score, waist circumference, waist-to-hip ratio (WHR), waist-to-height ratio, abdominal fat areas, total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, adiponectin and leptin. In addition to lipid profiles, WHR was identified as a significant independent variable correlated with the apoB/A1 ratio. Obese boys with a high FAI (>75th percentile) had significantly lower adiponectin and higher apoB/A1 ratios than those with a low FAI. The apoB/A1 ratio was higher in subjects with high visceral fat (>50th percentile) and a high FAI when compared with subjects with low visceral fat and a low FAI. The prevalence of paediatric metabolic syndrome was significantly associated with increasing tertiles of the apoB/A1 ratio (highest tertile; odds ratio = 18·8 [95% confidence interval = 1·8-198·8], P < 0·05).

CONCLUSION

ApoB/A1 ratio was significantly higher in viscerally obese male children and adolescents with high levels of FAI and was associated with increased frequency of paediatric metabolic syndrome.

A higher burden of small low-density lipoprotein particles is associated with profound changes in the free androgen index in male adolescents

From a young age, males are at higher cardiovascular risk than females. Dyslipidemia, including a higher burden related to small low-density lipoproteins (LDL), plays an important role in precipitating atherosclerosis in both males and females. We investigated sex differences in atherogenic lipoprotein burden and the independent predictors of LDL particle size in children and adolescents. We measured the concentrations of total testosterone, sex hormone-binding globulin, estradiol, total cholesterol, triglyceride, LDL cholesterol, HDL cholesterol, and LDL particle size in 135 children and adolescents (67 boys, 68 girls). The free androgen index was significantly and negatively correlated with LDL particle size (r = -0.273, P = 0.026) in boys, but estrogen and LDL particle size were not related. In a stepwise multiple regression analysis adjusted for body mass index, age, and homeostasis model assessment for insulin resistance, free androgen index was still an independent predictor of LDL particle size in boys (R(2) = 0.075, P = 0.026). The prominent decrease in LDL particle size along with increased testosterone concentrations in males might explain why they are more likely to display atherogenic dyslipidemia from adolescence.

The prevalence of impaired fasting glucose and type 2 diabetes in a population-based sample of overweight/obese children in the Middle East

BACKGROUND

Type 2 diabetes mellitus (T2DM) and impaired fasting glucose (IFG) are increasing in young population who are facing an escalating trend of overweight. The aim of this study was to determine the prevalence of IFG and T2DM for the first time in a population-based sample of Iranian obese children.

METHODS

This cross-sectional, population-based study was conducted in Isfahan, the second large city of Iran. Overall, 672 overweight and obese school students, selected from 7554 students, aged 6-19 yr, were screened for IFG and T2DM. Fasting plasma glucose (FPG) and lipid profile were measured in all participants. Oral glucose tolerance test and insulin level were measured in those children with IFG. Insulin resistance was defined as homeostasis model assessment for insulin resistance (HOMA-IR) > 3.10.

RESULTS

Among the7554 students (48.7% boys and 51.3% girls) studied, 9.34% (n = 706) were overweight and 5.3% (n = 403) were obese. A number of 672 overweight and obese students including 302 (44.9%) boys and 370 (55.1%) girls, with a mean age of 12.8 +/- 3.10 yr underwent biochemical work up. Overall, the prevalence of IFG was 4.61% (n = 31), the corresponding figure was 2% (n = 4) in the 6-10 yr age group, and 5% (n = 27) in those aged 10.1-19 yr. The prevalence of T2DM was 0.1% (n = 1; age, 18.00 yr). Impaired glucose tolerance and insulin resistance were detected in three and six participants with IFG, who consisted 0.4 and 0.8% of total obese and overweight students, respectively.

CONCLUSIONS

Although the prevalence of T2DM is low in Iranian obese children, IFG is not uncommon. Preventive measures and screening of FPG should be considered for these children.

Fasting and postprandial remnant-like particle cholesterol concentrations in obese participants are associated with plasma triglycerides, insulin resistance, and body fat distribution

Elevated plasma concentrations of remnant-like particle cholesterol (RLP-C) are atherogenic. However, factors that determine RLP-C are not fully understood. This study evaluates which factors affect RLP-C in the fasting and postprandial state, using multiple regression analyses in a large cohort of lean and obese participants. All participants (n = 740) underwent a test meal challenge containing 95 energy % (en%) fat (energy content 50% of predicted daily resting metabolic rate). Fasting and postprandial concentrations of circulating metabolites were measured over a 3-h period. Obese participants (n = 613) also participated in a 10-wk weight loss program (-2510 kJ/d), being randomized to either a low-fat or a high-fat diet (20-25 vs. 40-45en% fat). Postprandial RLP-C was associated with fasting RLP-C, waist:hip ratio (WHR), HOMA(IR) (homeostasis model assessment index for insulin resistance) (P < 0.001), and age, independently of BMI and gender [adjusted R(2) (adj. R(2)) = 0.70). These factors were also related to fasting RLP-C (P < 0.010), along with gender and physical activity (adj. R(2) = 0.23). The dietary intervention resulted in significantly lower fasting RLP-C concentrations, independently mediated by weight loss, improvements in HOMA(IR), and the fat content of the prescribed diet. However, after inclusion of plasma triglyceride (TG), HDL-cholesterol, and FFA concentrations in the models, HOMA(IR) and WHR no longer significantly predicted fasting RLP-C, although WHR remained a predictor of postprandial RLP-C (P = 0.002). Plasma TG was strongly associated with both fasting and postprandial RLP-C (P < 0.001). In conclusion, plasma RLP-C concentrations are mainly associated with plasma TG concentrations. Interestingly, the high-fat diet was more effective at decreasing fasting RLP-C concentrations in obese participants than the low-fat diet.

Metabolic syndrome and dyslipidemia in youth

Obesity is a well-known risk factor for metabolic syndrome. Although the cause or causes of metabolic syndrome are debated, insulin resistance, dyslipidemia, and hypertension are increasingly recognized in children and adolescents, especially those who are overweight or obese. Although adoption of a healthy lifestyle early in life offers the best long-term solution, many children and adolescents are currently at risk for future cardiovascular disease. Although long-term outcome data are lacking, the dyslipidemic triad commonly seen in youth with metabolic syndrome (elevated triglycerides, low high-density lipoprotein, and small dense low-density lipoprotein) is likely to significantly contribute to future vascular disease. Surrogate markers (carotid intima-media thickness and flow-mediated vasodilatation) for the precursors of cardiovascular disease are increased in obese youth, consistent with early vascular damage. In this work, we review the features of metabolic syndrome in children and adolescents, including age- and gender-specific norms for lipid values. Diagnostic criteria and modifications of screening guidelines unique to youth are discussed. Although recommendations for lifestyle modification are suggested for all, many youth at high risk of future cardiovascular risk may need more aggressive medical interventions to improve insulin sensitivity, achieve a less atherogenic lipid profile, and lower blood pressure.

Prevalence and Cluster of Cardiometabolic Biomarkers in Overweight and Obese Schoolchildren: Results from a Large Survey in Southwest Germany

Background: Obesity is associated with substantial metabolic changes and subclinical inflammation. We explored associations between body mass index (BMI) and cardiometabolic biomarkers and their clustering in overweight and obese schoolchildren.

Methods: In this population-based, cross-sectional study among 450 children 10 years old, we measured adiponectin, leptin, inflammatory markers, apolipoprotein (apo) AI and B, and lipoprotein-associated phospholipase A2 (Lp-PLA2). Except for adiponectin and apoAI (10th percentile) the 90th percentile was used as cutoff point. Body weight was categorized in age- and sex-specific BMI percentiles and overweight and obesity according to International Obesity Task Force definitions.

Results: In linear regression models, all cardiometabolic markers except apoB were statistically significantly associated with overweight. In logistic regression models, compared with the reference category (25th–75th percentile of BMI), overweight was associated with increased concentrations of leptin [odds ratio (OR) 59.80; 95% CI 16.68–214.39], C-reactive protein (6.30; 2.95–13.45), fibrinogen (2.82; 1.33–6.01), and low apoAI (2.62; 1.19–5.75). Overweight was positively associated with interleukin-6, Lp-PLA2, and apoB concentrations and inversely with adiponectin concentrations. Most importantly, in obese children 35% showed one, 20% two, 10% three, and 15% four or more abnormal cardiometabolic biomarkers. The number of abnormal cardiometabolic markers increased in overweight (ptrend &lt;0.001) and obese (ptrend &lt;0.001) children.

Conclusions: Overweight and obesity in children are associated with complex metabolic changes and a low-grade inflammatory response, and thus might not only accelerate cardiovascular disease later on, but may also be associated with the initiation of atherosclerosis in early life.