Relationship between high plasma leptin concentrations and metabolic syndrome in obese pre-pubertal children

Effects of exercise training on inflammatory and cardiometabolic health markers in overweight and obese adults: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

The improvements in inflammation and cardiometabolic health play an important role in the prevention and treatment of obesity. However, the interactions between different exercise training (ET) modalities with inflammatory and cardiometabolic biomarkers are not completely understood. This systematic review and meta-analysis investigated the effects of ET on inflammatory and cardiometabolic health markers in overweight and obese adults.

EVIDENCE ACQUISITION

A systematic search was conducted in PubMed, CINAHL, MEDLINE, Cochrane, Google Scholar, Scopus and Web of Science up to December 15, 2021. Thirty-five studies including 2752 participants were included and analyzed using a random-effects model to estimate weighted mean differences (MD) with 95% confidence intervals (CI).

EVIDENCE SYNTHESIS

The meta-analysis found that ET significantly (P<0.05) increased adiponectin (WMD: 0.72 µg/mL; 95% CI: 0.60 to 0.84; SMD=0.65) and maximal oxygen consumption levels (WMD: 5.26 mL.kg.min; 95% CI: 3.84, 6.69; SMD=1.21). Moreover, ET significantly (P<0.05) reduced fasting insulin (WMD: -2.40 μIU/mL; 95% CI: -3.43 to -1.37; SMD=-0.87), fasting blood glucose (WMD: -5.41 mg/dL; 95% CI: -7.91, -2.91; SMD=-0.66), insulin resistance (WMD: -0.66; 95% CI: -1.08, -0.24; SMD=-0.66) and triglyceride levels (WMD: -10.88 mg/dL; 95% CI: -17.61, -4.15; SMD=-0.91). No significant changes were observed in interleukin-6, tumor necrosis factor-α, leptin, C-reactive protein and cholesterol concentrations. Subgroup analysis by type of training indicated that aerobic and resistance exercise had the most consistent beneficial effects as compared to other modalities.

CONCLUSIONS

Our findings suggest that ET may improve inflammation and cardiometabolic health in overweight and obese adults. Aerobic and resistance training appear to be more beneficial for improving adiponectin, fasting insulin, fasting blood glucose, insulin resistance index and triglyceride levels as compared to other exercise modalities. Further long-term studies are required to confirm and expand on these findings.

Blood level of adipokines and nutritional status variables in adolescent pregnancy

Objective

To evaluate the serum levels of adiponectin and leptin and their relationship with nutritional variables during pregnancy in adolescents.

Methods

This prospective cohort study evaluated eutrophic pregnant adolescents (body mass index [BMI], 18.5–24.9 kg/m²) during the 3 gestational trimesters (first, 10–14 weeks; second, 24–28 weeks; and third, 30–34 weeks). Serum adiponectin and leptin concentrations were measured using the enzyme-linked immunosorbent assay method. The relationship of these adipokines with the pre-gestational BMI, gestational weight gain, weight at the time of sample collection, and newborn weight were evaluated. Analysis of variance and the Kruskal-Wallis test were used for statistical analysis.

Results

The study group comprised 62 pregnant adolescents. The serum concentration of adiponectin showed a significant difference between the first and third trimesters (P=0.003), which decreased during pregnancy, but unrelated to nutritional variables. Serum leptin levels increased throughout the pregnancy (P<0.0001) and showed a positive correlation with pre-gestational BMI, total weight gain, pregnancy weight at the time of sample collection, and newborns’ weight.

Conclusion

Serum levels of adiponectin and leptin vary inversely throughout pregnancy. This pattern in adolescents is similar to that observed in adults. Moreover, leptin concentrations increased throughout pregnancy, and they were positively correlated with all variables evaluated.

Higher Prevalence of Metabolic Syndrome in Child-adolescent Patients with Bipolar Disorder

Objective

Previous studies have indicated a convergent and bidirectional relationship between metabolic syndrome (MetS) and bipolar disorder (BD). As most of these studies focused mainly on adults diagnosed with BD, our study aims to investigate and characterize metabolic disturbances in child-adolescents diagnosed with BD.

Methods

We retrospectively examined the medical records of psychiatric hospitalizations with admitting diagnosis of BD in child-adolescents (age < 18 years). Body mass index (BMI), lipid profile, fasting blood glucose, and blood pressure were primary variables. National Cholesterol Education Program criteria were used to define MetS. Reference group data was obtained from the National Health and Nutrition Examination Survey study. Statistical analyses included ttests, chi-square tests, and Fisher’s exact tests.

Results

We identified 140 child-adolescent patients with BD (mean age = 15.12 ± 1.70 years, 53% male). MetS was significantly more common in BD compared to the reference group: 14% (95% confidence interval [95% CI] 8−20) vs. 6.7% (95% CI 4.1−9.2), p = 0.001 with no significant difference by sex. MetS components were higher in the BD group, particularly BMI ≥ 95% (25% vs. 11.8%, p < 0.001) and high blood pressure (17% vs. 8%, p = 0.05). Moreover, female patients had lower odds of high blood pressure (odds ratio = 0.24 [95% CI 0.08−0.69], p = 0.005).

Conclusion

Compared with the general child-adolescent population, the prevalence of MetS was significantly higher in patients with BD of same age. This reiterates the notion of an increased risk of MetS in patients diagnosed with BD; and thus, further exploration is warranted.

Circulating leptin levels are associated with adiposity in survivors of childhood brain tumors

Survivors of Childhood Brain Tumors (SCBT) are at a higher risk of developing cardiovascular disease and type 2 diabetes compared to the general population. Adiposity is an important risk factor for the development of these outcomes, and identifying biomarkers of adiposity may help the stratification of survivors based on their cardiovascular risk or allow for early screening and interventions to improve cardiometabolic outcomes. Leptin is an adipokine that positively correlates with the adipose mass in the general population and is a predictor of adverse cardiometabolic outcomes, yet its association with adiposity in SCBT has not been studied. The aim of this study was to determine if leptin levels are associated with the adipose mass in SCBT, and to define its predictors. This cross-sectional study included 74 SCBT (n = 32 females) with 126 non-cancer controls (n = 59 females). Total adiposity was measured using Bioelectrical Impendence Analysis (BIA) and central adiposity was measured using waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). We used multivariable linear regression analysis to determine if leptin predicts adiposity in SCBT and adjusted for age, sex, puberty, and cancer status. Leptin correlated strongly with total (p < 0.001) and central (WHR p = 0.001; WHtR p < 0.001) adiposity in SCBT and non-cancer controls. In conclusion, leptin is a potential biomarker for adiposity in SCBT, and further investigation is needed to clarify if leptin is a predictor of future cardiometabolic risk in SCBT.

Relationship between the insulin resistance and circulating predictive biochemical markers in metabolic syndrome among young adults in western Algeria

AIM

The metabolic syndrome (MetS) becomes increasingly obvious from an early age. The current study aimed at exploring the relationship between insulin resistance and the main biomarkers of MetS in young adult algerian patients.

METHODS

Glucose, HbA1C, total cholesterol (TC), hjgh bensity lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), insulinemia and C-peptide, adipokins (leptin, adiponectin), inflammatory cytokines (IL-6 and TNF-a), us-CRP and GLP-1 were measured by suitable methods. Homeostasis model assessment (HOMA) was used to detect the degree of insulin resistance.

RESULTS

The MetS patients displayed higher glucose, insulin, HbA1c values and impaired lipid profile as judged by increasing TC, TG, LDL-C levels and lower HDL-C. Furthermore, adipokines, HDL-C and CRP contents were significantly higher whilst TG and LDL-C were much lower in MetS female group as compared to male patients suggesting most pronounced metabolic perturbation in the latter group. The probability of a significant correlation between HOMA and studied variables was often higher in female than male subjects. Such was the case for total cholesterol, HDL-cholesterol, triglycerides, adiponectin, interleukin-6, TNF-α and hs-CRP.

CONCLUSION

The high rate of metabolic syndrome among young obese adults is alarming, this requiring extensive investigations in prone subjects.

Gastrointestinal factors regulating lipid droplet formation in the intestine

Cytoplasmic lipid droplets (CLD) are considered as neutral lipid reservoirs, which protect cells from lipotoxicity. It became clear that these fascinating dynamic organelles play a role not only in energy storage and metabolism, but also in cellular lipid and protein handling, inter-organelle communication, and signaling among diverse functions. Their dysregulation is associated with multiple disorders, including obesity, liver steatosis and cardiovascular diseases. The central aim of this review is to highlight the link between intra-enterocyte CLD dynamics and the formation of chylomicrons, the main intestinal dietary lipid vehicle, after overviewing the morphology, molecular composition, biogenesis and functions of CLD.

Blood pressure, dyslipidemia and inflammatory factors are related to body mass index in scholar adolescents

INTRODUCTION

Obesity is associated with increased occurrence of numerous diseases, including hypertension, dyslipidemia, insulin resistance, diabetes, and atherosclerosis. Blood pressure (BP), dyslipidemia, and inflammation markers and their relationships with body mass index (BMI) were determined in scholar adolescents.

MATERIAL AND METHODS

Adolescents (n = 210) (sex ratio G/B = 106/104; 11 to 16 years) were recruited in three colleges of Oran city. Anthropometric parameters were measured to classify adolescents as thin (T), normal weight (NW), overweight (OW), or obese (O). Waist circumference (WC) and BP were measured, and serum glucose, uric acid, urea, lipid parameters, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), C-reactive protein (CRP), insulin, leptin, and adiponectin were analyzed.

RESULTS

Adolescents were classified according to their BMI as T (15%), NW (63%), OW (13%), and O (9%). Compared to NW, increased values of WC, BP (p < 0.001), and glucose (p < 0.01) were noted in OW and O groups. Total cholesterol (TC) level was elevated in O adolescents (p < 0.01). Increased low-density lipoprotein cholesterol (LDL-C) in OW (p < 0.05) and O (p < 0.01), and reduced high-density lipoprotein cholesterol (HDL-C) concentrations were noted in both OW and O groups (p < 0.05), compared to NW. Elevated triglyceride (TG) values and TG : HDL-C ratio were observed in OW (p < 0.05) and O (p < 0.01). High values of uric acid were noted in OW and O adolescents (p < 0.01). Compared to NW, there was no significant difference in IL-1β whereas IL-6 was elevated in T (p < 0.05), OW (p < 0.01) and O (p < 0.001). Leptin, TNF-α, and CRP concentrations were significantly increased (p < 0.001), whereas adiponectin values were decreased in both OW and O groups (p < 0.01), compared to NW.

CONCLUSIONS

Significant associations were noted between WC, BP, dyslipidemia, inflammation markers, and BMI, indicating that both OW and O adolescents have a tendency to present metabolic syndrome risk factors.

Genistein treatment improves fracture resistance in obese diabetic mice

BACKGROUND

Obese, type two diabetics are at an increased risk for fracturing their limb bones in comparison to the general population. Phytoestrogens like as the soy isoflavone genistein have been shown to protect against bone loss. In this study, we tested the effects of genistein treatment on femurs of ob/ob mice, a model for obesity and type two diabetes mellitus.

METHODS

Twenty six-week-old female mice were divided into obese (ob/ob) control, obese genistein-treated, lean (ob/+) control, and lean genistein-treated groups (n = 5 each). Treatment with genistein consisted of 600 mg genistein/kg diet. Control mice were given standard rodent chow. At the end of a four-week treatment period, bone histomorphometric and three-point bending properties were compared among groups.

RESULTS

Obese mice had larger bone areas (B.Ar.; P < 0.05) and total areas (Tt.Ar.; P < 0.05), but similar bone volume (B.Ar./Tt.Ar.; P > 0.05) of the proximal femoral epiphysis in comparison to lean mice. Treatment with genistein decreased Tt.Ar. and femur length, and increased ultimate force required to fracture the femur and the maximum deformation to failure (P < 0.05).

CONCLUSIONS

Genistein improves resistance to fracture from bending loads.

Early-onset obesity dysregulates pulmonary adipocytokine/insulin signaling and induces asthma-like disease in mice

Childhood obesity is a risk factor for asthma, but the molecular mechanisms linking both remain elusive. Since obesity leads to chronic low-grade inflammation and affects metabolic signaling we hypothesized that postnatal hyperalimentation (pHA) induced by maternal high-fat-diet during lactation leads to early-onset obesity and dysregulates pulmonary adipocytokine/insulin signaling, resulting in metabolic programming of asthma-like disease in adult mice. Offspring with pHA showed at postnatal day 21 (P21): (1) early-onset obesity, greater fat-mass, increased expression of IL-1β, IL-23, and Tnf-α, greater serum leptin and reduced glucose tolerance than Control (Ctrl); (2) less STAT3/AMPKα-activation, greater SOCS3 expression and reduced AKT/GSK3β-activation in the lung, indicative of leptin resistance and insulin signaling, respectively; (3) increased lung mRNA of IL-6, IL-13, IL-17A and Tnf-α. At P70 body weight, fat-mass, and cytokine mRNA expression were similar in the pHA and Ctrl, but serum leptin and IL-6 were greater, and insulin signaling and glucose tolerance impaired. Peribronchial elastic fiber content, bronchial smooth muscle layer, and deposition of connective tissue were not different after pHA. Despite unaltered bronchial structure mice after pHA exhibited significantly increased airway reactivity. Our study does not only demonstrate that early-onset obesity transiently activates pulmonary adipocytokine/insulin signaling and induces airway hyperreactivity in mice, but also provides new insights into metabolic programming of childhood obesity-related asthma.

Leptin and metabolic syndrome in patients with Duchenne/Becker muscular dystrophy

OBJECTIVES

To determine whether patients with Duchenne/Becker muscular dystrophy (DMD/BMD) have components of metabolic syndrome (MetSy) and to evaluate whether leptin is associated with components of MetSy.

METHODS

This study included 78 patients (nine, <6 years of age; 54, 6 to <16 years of age; and 15 patients, ≥16 years of age). Obesity and body fat mass were determined by waist circumference and dual-energy X-ray absorptiometry, respectively. A 12-h fasting blood sample was collected in the morning. Patients were categorized into four groups according to the number of criteria for MetSy: group 0: none; group 1: one; group 2: two and group 3: three or more criteria.

RESULTS

All age groups showed components of MetSy. The concentration of these components was significantly higher in patients ≥16 years old. The prevalence of hypertriglyceridemia was from ~37% to 46% in all age groups. The prevalence of MetSy was 7.1% for patients from 6 to <16 years of age and 24% for patients ≥16 years of age. Serum leptin levels increased significantly (P < 0.05) with age; the highest (13.43 ± 9.4 ng/ml) value was observed in patients >16 years of age. Total leptin was correlated with the number of patients with MetSy (r = 0.383; P = 0.001).

CONCLUSIONS

Components of MetSy are significant in patients with DMD/BMD. A high prevalence of hypertriglyceridemia was observed. Younger patients with DMD/BMD have risk factors for MetSy. Although leptin increased according to different degrees of MetSy, this relation disappeared when the body fat was corrected by leptin; therefore, the association could be caused by a common risk factor-fat.

Adipokines and Insulin Resistance in Young Adult Survivors of Childhood Cancer

We examined the association between adipokines (leptin, adiponectin, and resistin), radiotherapy, measurement of body fat, and insulin resistance among young adult survivors of childhood cancer (CCS). Materials and Methods. Seventy-six survivors were included (mean age 24.1 ± 3.5 years). Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA-IR). The serum levels of adipokines were assayed by immunoassays. Fat mass was evaluated by DXA. Results. Mean adiponectin level and mean body FAT were higher in the examined females than in males (10009 ± 6367 ng/mL versus 6433 ± 4136 ng/mL, p < 0.01; 35.98 ± 9.61% versus 22.7 ± 7.46%, p < 0.001). Among CCS, one of 75 patients met the criteria of insulin resistance, and in 14 patients there was impaired fasting glucose. The multiple regression model for females showed that leptin/adiponectin ratio (LA ratio) significantly affected HOMA-IR (increase of 0.024 per each unit of LA ratio; p < 0.05). Radiotherapy had no effect on serum adipokines and IR. Conclusion. The observed results support the hypothesis that adiponectin might be associated with insulin resistance and it can not be ruled out that changes in the mean level of adiponectin per FAT mass or leptin/adiponectin ratio may precede the occurrence of insulin resistance in the future.

Relationship of high leptin levels with an adverse lipid and insulin profile in 6-8 year-old children in Spain

BACKGROUND AND AIMS

Leptin, an adipokine elevated in obesity, may be related to an adverse cardiovascular risk profile in childhood. However, evidence for this relationship in pre-pubertal children is scarce. We aimed to analyze the relationship between leptin levels and lipid and insulin profiles in Spanish children.

METHODS AND RESULTS

Our population-based sample included 389 males and 369 females aged 6-8 years. Lipid levels were determined by standard methods, insulin by radioimmunoassay and leptin by sandwich ELISA. Leptin levels were higher in girls (8.6 ng/ml) than boys (4.7 ng/ml) (p < 0.001). Leptin increased from ages 6 to 8 in girls, but remained steady in boys. In both sexes, leptin increased significantly (p < 0.001) across weight category from normal weight to obese. Children in the highest tertile of leptin concentration showed significantly (p < 0.01) lower levels of HDL-cholesterol (HDL-C) and apolipoprotein-AI (apo-AI) and significantly higher triglyceride (TG) levels than children in lower tertiles. However, in linear regression analysis, after adjustment for body mass index (BMI), leptin only accounted for 1.5% of the variance of HDL-C in boys, and 2.6% of the variance of apo-AI in girls. Leptin was strongly and positively correlated with insulin and HOMA. Upon regression analysis, leptin contributed to over 20% of the variability in insulin and HOMA, independent of BMI.

CONCLUSION

Leptin levels show sex differences in pre-pubertal children. In this age group, leptin levels are strongly related to insulin, and affect lipid profile -namely HDL-C, apo-AI and TG- particularly when leptin levels are high.

Leptin and cardiometabolic risk factors in obese children and adolescents

AIM

To verify the relationship between leptin and cardiometabolic risk factors in obese children and adolescents.

METHODS

A cross-sectional study evaluated 200 children and adolescents treated in Campina Grande, Brazil, from April 2009 to March 2010. Leptin, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides were determined. The t-test was used to compare leptin means of two groups and analysis of variance to compare means of three groups. Multiple comparisons of pairs of group means were performed with Tukey's test. In all tests, a significance level of 0.05 was adopted.

RESULTS

The leptin sample mean was 22.7 ± 10.0 μg/L (95% confidence interval: 21.3 μg/L to 24.1 μg/L). Leptin was significantly higher in the following groups: female, teenager, increased waist circumference, high systolic blood pressure, elevated triglycerides hyperinsulinemia, insulin resistance and metabolic syndrome. Most cardiometabolic risk factors had higher means in the last quartile of leptin, except total-cholesterol, LDL-C and triglycerides levels. HDL-C was reduced in the last quartile of leptin. Simple linear regression analysis showed a significant negative correlation between leptin and HDL-C and a positive correlation between leptin and triglycerides, insulin, HOMA-IR, body mass index, waist circumference, and systolic and diastolic blood pressure. Multiple linear regression models showed an independent association between leptin and HDL-C, triglycerides, insulin, HOMA-IR, body mass index, waist circumference, systolic and diastolic blood pressure, after age and gender control.

CONCLUSION

Leptin may be a useful marker of metabolic syndrome and insulin resistance in obese adolescents.

Adipocytokines in childhood cancer survivors and correlation with metabolic syndrome components

BACKGROUND

Although there are several studies on the prevalence of metabolic syndrome (MetS) in childhood cancer survivors (CCS), the association between MetS components and serum adipocytokine level has not been elucidated.

METHODS

The charts of 49 patients (27 male, 22 female) who had attended the CCS clinic of the Department of Pediatrics, Kyoto University Hospital, between April 2009 and March 2010 were retrospectively reviewed. Median age was 10.7 years, and the median interval since the completion of chemotherapy was 5.1 years. The diagnosis of MetS was made based on the Japanese criteria for either children or adults.

RESULTS

Three (6.1%) of 49 patients fulfilled the criteria for MetS, and 28 (57.1%) had at least one component of MetS. High leptin level was seen in 18 patients (36.7%), and low total adiponectin level was seen in 20 (40.8%). The number of patients with high leptin was correlated with body mass index z-score (>2.0), abdominal circumference/height (≥0.5), diastolic blood pressure and fasting blood sugar. The number of patients with low total adiponectin was correlated with systolic blood pressure and triglyceride. When the patients were divided into three groups based on the number of positive MetS components (0, 1 and 2-4), leptin and adiponectin tended to be higher and lower in the third group, respectively.

CONCLUSIONS

Adipocytokines may play a role in the pathogenesis of MetS occurring in CCS. It is recommended that adipocytokines be evaluated together with MetS components at the CCS follow-up clinics.

Leptin, abdominal obesity, and onset of depression in older men and women

OBJECTIVE

The mechanisms that underlie the association between abdominal obesity and depression risk in older persons are not well known, but the "leptin hypothesis" of depression suggests that leptin resistance may be involved in mood regulation. We tested whether high circulatory concentration of leptin, alone and in combination with visceral adiposity, is associated with onset of depression in a sample of older persons.

METHOD

Participants were 1,220 men and 1,282 women aged 70-79 years and enrolled in the Health, Aging, and Body Composition study. Serum concentration of leptin and abdominal visceral fat, ascertained by computed tomography, were assessed at baseline (April 1997-June 1998). Onset of depression, the primary outcome measure, was defined as a Center for Epidemiologic Studies-depression scale 10-item score ≥ 10 and/or new antidepressant medication use at any annual visit over a 5-year follow-up.

RESULTS

Higher leptin level was associated with the risk of depression onset in men with high levels of visceral fat (hazard ratio [HR] = 1.25; 95% CI, 1.06-1.46; P = .01) but not in those with normal visceral fat (HR = 0.98; 95% CI, 0.80-1.19; P = .80) (leptin-by-visceral fat, P = .04). No interaction between leptin and visceral fat was detected in the analysis focusing on women (P = .90).

CONCLUSIONS

In older men, high leptin level was associated with an increased onset of depressive symptoms, especially in the presence of abdominal obesity, suggesting that underlying leptin resistance may play a role in this link. Differences in visceral fat levels and metabolic consequences may explain the absence of this association in women. These findings suggest a potential biological link between depression, obesity, and their joint association with negative health outcomes.

Hyperleptinemia and hypoadiponectinemia in extreme pediatric obesity

BACKGROUND

Adiponectin and leptin, adipokines associated with metabolic syndrome, type 2 diabetes, and cardiovascular disease, have not been well characterized in extreme pediatric obesity. Therefore, levels were compared in youth that were extremely obese (EO) to normal weight (NW), overweight (OW), and obese (OB) youth.

METHODS

Leptin, adiponectin, body mass index (BMI), blood pressure, fasting glucose, insulin, and lipids were obtained in 277 children and adolescents (age 13.4±2.6 years; 152 boys). Participants were classified into four BMI groups (NW, OW, OB, EO). Variables were compared across groups using analysis of covariance (ANCOVA) adjusted for gender, age, and race.

RESULTS

Risk factors generally worsened across BMI groups. EO had significantly higher levels of leptin than OB (P<0.0001), OW (P<0.0001), and NW (P<0.0001). Leptin was higher in OB compared to OW (P<0.005) and NW (P<0.0001) and higher in OW compared to NW (P<0.0001). Adiponectin levels in EO did not significantly differ from OB or OW but were significantly lower than NW (P<0.0001). Adiponectin was not significantly different among the OB, OW, and NW groups.

CONCLUSIONS

Leptin was markedly elevated in EO children and adolescents, suggesting that this subset of obese youth may be at particularly high risk of future weight gain and potentially reduced response to weight-loss interventions.

Nontraditional risk factors and biomarkers for cardiovascular disease: mechanistic, research, and clinical considerations for youth: a scientific statement from the American Heart Association

The rapid increase in the prevalence and severity of obesity in children is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide. Understanding the pathophysiology and improving the clinical management of cardiovascular disease involve a knowledge of novel risk factors and biomarkers. The clinical and mechanistic roles of these novel biological factors during childhood are currently being investigated. The goals of this scientific statement are to present the existing knowledge and theoretical framework of nontraditional risk factors for cardiovascular disease as they relate to children and adolescents, to describe the relevance and weight of available experimental and clinical evidence and the therapeutic implications pertaining to nontraditional risk factors in the pediatric population, and to stimulate further research with a goal of developing valid and reliable approaches to identify and validate novel risk factors that will aid in the clinical evaluation and perhaps prediction of cardiovascular disease in the pediatric population. Although several biomarkers are promising, substantial research is required before nontraditional risk factors can be used to identify and reduce cardiovascular disease risk in children and adolescents.

Serum leptin is associated with cardiometabolic risk and predicts metabolic syndrome in Taiwanese adults

BACKGROUND

Leptin is associated with cardiovascular disease (CVD); however, few studies have assessed its relationship with metabolic syndrome, especially in an Asian population. Therefore, the aim of the present study was to assess leptin levels and evaluate its association with CVD and metabolic syndrome.

METHODS

In 2009, 957 subjects, who underwent a routine physical examination and choose leptin examination, were selected to participate. Participants (269 females and 688 males) were stratified according to leptin level quartiles. Metabolic syndrome was defined by NCEP ATP III using waist circumference cutoffs modified for Asian populations, and CVD risk was determined using the Framingham Heart Study profile.

RESULTS

Leptin levels were correlated with CVD risk in men and women. With the exception of fasting plasma glucose, increased leptin levels were observed as factors associated with metabolic syndrome increased in both males and females. After adjusting for age, an association between leptin levels and metabolic syndrome was observed. After adjusting for age alone or with tobacco use, subjects in the highest leptin quartile had a higher risk of having metabolic syndrome than those in the lowest quartile (OR=6.14 and 2.94 for men and women, respectively). After further adjustment for BMI, metabolic syndrome risk remained significantly increased with increasing leptin quartiles in men. Finally, increased leptin levels were a predictor of metabolic syndrome in men and women.

CONCLUSIONS

Serum leptin levels are correlated with CVD risk and metabolic syndrome. Analysis of leptin as part of routine physical examinations may prove beneficial for early diagnosis of metabolic syndrome.

Inflammatory adipokines, high molecular weight adiponectin, and insulin resistance: a population-based survey in prepubertal schoolchildren

Background

The aim of this study was to investigate sex differences and associations of high molecular weight (HMW) adiponectin, leptin and proinflammatory adipokines, individually or in combinations, with adiposity and insulin resistance (IR) measures in prepubertal childhood.

Methodology

We studied 305 prepubertal children (boys/girls: 144/161; Tanner stage 1; age: 5-13 yr), included in a cohort of 44,231 adolescents who participated in an extensive Italian school-based survey. According to Cole's criteria, 105 individuals were lean (L; boys/girls: 59/46), 60 overweight (OW; boys/girls: 32/28) and 140 obese (OB; boys/girls: 70/70). Measurements comprised total and HMW adiponectin, leptin, as well as a panel of proinflammatory adipokines/chemokines associated with diabetes risk.

Principal Findings

Leptin-, and the leptin-to-HMW adiponectin ratio (L/HMW)-, increased progressively (p<0.0001) from L to OW to OB boys and girls. When compared with L peers, OW and OB girls exhibited lower (p<0.001) HMW adiponectin levels, while in boys the HMW multimers did not differ significantly across the BMI-stratified groups. OB girls displayed higher (p<0.05) IL-8, IL-18, monocyte chemoattractant protein-1 (MCP-1) and soluble intercellular adhesion molecule-1 levels (sICAM-1) than L girls, whereas increased macrophage migration inhibitory factor (MIF) concentrations in OB vs OW boys were seen. HMW adiponectin (negatively), leptin or inflammatory markers (positively) correlated with adiposity and IR measures. In multivariate models, leptin represented a strong and independent determinant of HOMA-IR (R² 0.378; p<0.01). Adjustment for age, BMI_z-score, lipids and inflammatory mediators abolished the association between leptin and HOMA-IR in boys, while in girls leptin remained still a significant predictor of IR (R² 0.513; p<0.01). Finally, in both sexes, the joint effect of the L/HMW did not improve the prediction of basal IR as compared with leptin levels alone, which were mainly explained by the BMI_z-score.

Conclusions

In prepubertal children, leptin emerges as a sex-independent discrimination marker of adiposity degree and as a useful, sex-associated predictor of the systemic insulin resistance.

The prevalence and trends of overweight, obesity and nutrition-related non-communicable diseases in the Arabian Gulf States

This paper reviews studies on the prevalence of overweight, obesity and related nutrition-related non-communicable diseases in Bahrain, Kuwait, Qatar, Oman, Saudi Arabia and the UAE. Obesity is common among women; while men have an equal or higher overweight prevalence. Among adults, overweight plus obesity rates are especially high in Kuwait, Qatar and Saudi Arabia, and especially among 30-60 year olds (70-85% among men; 75-88% among women), with lower levels among younger and elderly adults. The rate of increase in obesity was pronounced in Saudi Arabia and Kuwait. Prevalence of obesity is high among Kuwaiti and Saudi pre-schoolers (8-9%), while adolescent overweight and obesity are among the highest in the world, with Kuwait having the worst estimates (40-46%); however, comparison of child data is difficult because of differing standards. Among nutrition-related non-communicable diseases, hypertension and diabetes levels are very high and increase with age, with the UAE performing the worst because of a rapid rate of increase between 1995 and 2000. Additional monitoring of the prevalence of metabolic syndrome and cancers is necessary. Nationally representative longitudinal surveys with individual, household and community-level information are needed to determine the importance of various factors that contribute to these troubling trends.

Obesity and metabolic syndrome in 7-9 years-old Portuguese schoolchildren

BACKGROUND

Body fat is related to changes in lipid profile, blood pressure and metabolism of insulin and glucose, known as the metabolic syndrome (MS). The aim of this study was to estimate the prevalence of metabolic syndrome (MS) and its components among overweight and obese Portuguese schoolchildren, and to identify associated clinical and biochemical characteristics.

METHODS

A total of 82 children (14 overweight and 68 obese; 40 boys and 42 girls) aged 7-9 years, underwent anthropometric measurements. A blood sample was obtained to assess biochemical parameters. Insulin resistance (IR) was determined by the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). MS was defined by the National Cholesterol Education Program Adult Treatment Panel III criteria modified by Cook.

RESULTS

The prevalence of MS was 15.8%. Abdominal obesity was present in all children. Frequency of elevated blood pressure, low HDL-cholesterol and elevated triglyceride concentrations were 62.6%, 13.4% and 11.0%, respectively. None of the children presented impaired fasting glucose, however hyperinsulinemia (7.3%) and IR (8.5%) were observed. The number of components of MS was higher in children with higher z-BMI (rho = 0.411; p < 0.001). MS was associated with higher leptin concentrations. No association was found with adiponectin or ghrelin levels. Leptin correlated positively with obesity, glucose metabolism, lipid profile, hepatic function and C-reactive protein, and negatively with HDL and Apolipoprotein A-I/B ratio.

CONCLUSIONS

This study shows a significant prevalence of MS among obese schoolchildren. Abdominal obesity and elevated blood pressure were the most frequent components of this syndrome. Dyslipidemia, IR and high levels of leptin were also associated with MS in this young group.

Childhood hypo-adiponectinaemia but not hyper-leptinaemia is associated with insulin insensitivity 6 years later

BACKGROUND

Biomarkers of metabolism and inflammation may predict children with increased diabetes risk.

OBJECTIVE

To study plasma adiponectin, leptin, IL-8, and hepatocyte growth factor (HGF) in childhood and their independent associations with insulin insensitivity, cross-sectional and in 6-yr prospective.

SUBJECTS

Danish 8- to 10-yr-olds and 14- to 16-yr-olds from the European Youth Heart Studies I and II.

METHODS

Cross-sectional (n = 386) and prospective (n = 246) linear regressions of baseline concentrations of plasma biomarkers and insulin insensitivity at baseline and 6 yr later. Adjustments were made at four progressive steps for sex, sexual maturity, body mass index (BMI), other biomarkers, physical activity, and school location as well as baseline insulin insensitivity in prospective analyses. Insulin insensitivity was measured using homeostasis model assessment standardized to the sample mean [homoestasis model assessment (HOMA) Z-scores]. Plasma biomarkers were quantified using solid-phase protein immunoassays. Overweight was defined as the highest BMI tertile.

RESULTS

Among overweight but not lean children at baseline, one SD difference in baseline plasma adiponectin was associated with -0.41 SD difference in HOMA Z-scores 6 yr later (p = 0.006). At baseline, one SD difference in plasma leptin was associated with 0.36 SD difference in HOMA Z-scores (p =< 0.0001) among 8- to 10-yr-olds, but a prospective association was not found.

CONCLUSIONS

We found a direct relationship between childhood hypo-adiponectinaemia and insulin insensitivity in adolescence. This association was stronger for overweight than for normal weight children. Hyper-leptinaemia was associated with concurrent insulin insensitivity at baseline but not 6 yr later.

Decrease in leptin production by the adipose tissue in obesity associated with severe metabolic syndrome

OBJECTIVE: To evaluate the associations between leptinemia and the components of metabolic syndrome (MetS). METHODS: Fifty-one obese adults (9 men; 36.7 ± 10.0 years; body mass index (BMI) 46.2 ± 10.0 kg/m²) were submitted to clinical examination, determinations of body fat mass (BF, bioimpedance) and resting energy expenditure (REE, indirect calorimetry), and to hormonal and biochemical analysis. Patients were categorized into three groups, according to the number of criteria for MetS: Group I: none or 1; Group II: 2; and Group III: 3 or 4 criteria. RESULTS: Absolute leptinemia (LepA; 37.5 ± 16.9 ng/mL) was directly correlated with BMI (r = 0.48; p = 0.0004), waist circumference (r = 0.31; p = 0.028) and BF (r = 0.52; p = 0.0001). Leptinemia adjusted for BF (LepBF) was inversely correlated with weight (r = -0.41; p=0.027), REE (r = -0.34; p = 0.01) and number of MetS criteria (r = -0.32; p = 0.02). There was no difference in LepA among the groups. LepBF in Group III (0.58 ± 0.27 ng/mL/kg) was significantly lower compared to Group I (0.81 ± 0.22 ng/mL/kg; p = 0.03) and Group II (0.79 ± 0.30 ng/mL/kg; p = 0.02). CONCLUSIONS: Leptin production by the adipose tissue is decreased in obese subjects fulfilling three or more criteria of MetS, suggesting a state of relative leptin deficiency in obesity associated with advanced stages of MetS.

Hypoadiponectinemia in overweight children contributes to a negative metabolic risk profile 6 years later

Prognostic biomarkers are needed to identify children at increased cardiometabolic risk. The objective was to study whether markers of metabolism and inflammation, for example, circulating plasma adiponectin, leptin, interleukin-8, and hepatocyte growth factor, are associated with cardiometabolic risk factors in childhood and adolescence. This was a cross-sectional and prospective study, and the setting was the Danish part of the European Youth Heart Studies I and II. Participants were randomly selected girls and boys 8 to 10 years of age with complete baseline data (n = 256) and complete follow-up data 6 years later (n = 169). Cardiometabolic risk profile was calculated using a continuous composite score derived from summing of 6 factors standardized to the sample means (Z scores): body mass index, homeostasis model assessment of insulin resistance, total serum cholesterol to serum high-density lipoprotein cholesterol ratio, serum triglycerides, systolic blood pressure, and the reciprocal value of fitness (maximum watts per kilogram). Overweight was defined using international classification of body mass index cutoff points for children. Plasma adiponectin, leptin, interleukin-8, and hepatocyte growth factor were assessed using immunochemical assays. Linear relationships were found between metabolic risk score and both plasma adiponectin (inverse, P = .02) and plasma leptin (P < .0001) at baseline after adjustment for several confounders. In overweight but not normal-weight children, plasma adiponectin at baseline was inversely associated with metabolic risk score 6 years later (P = .04). In childhood, both hypoadiponectinemia and hyperleptinemia accompany a negative metabolic risk profile. In addition, circulating plasma adiponectin may be a useful biomarker to identify overweight children at greater future risk of the cardiometabolic adverse effects of overweight.

Circulating ghrelin, leptin, and soluble leptin receptor concentrations and cardiometabolic risk factors in a community-based sample

CONTEXT

The conjoint effects and relative importance of ghrelin, leptin, and soluble leptin receptor (sOB-R), adipokines involved in appetite control and energy expenditure in mediating cardiometabolic risk, is unknown.

OBJECTIVE

The objective of the study was to study the cross-sectional relations of these adipokines to cardiometabolic risk factors in a community-based sample.

DESIGN, SETTING, AND PARTICIPANTS

We measured circulating ghrelin, leptin, and sOB-R in 362 participants (mean age 45 yr; 54% women) of the Framingham Third Generation Cohort.

MAIN OUTCOME MEASURES

Body mass index, waist circumference (WC), blood pressure, lipid measures, fasting glucose, smoking, and metabolic syndrome (MetS) were measured.

RESULTS

Ghrelin and leptin concentrations were significantly higher in women (P < 0.0001). In multivariable models, ghrelin was inversely associated with age and systolic blood pressure, and leptin was positively related to body mass index and WC. sOB-R was positively associated with age, total cholesterol, and fasting glucose and inversely with WC and high-density lipoprotein cholesterol. Ghrelin and sOB-R concentrations were significantly lower with number of MetS components (P for trend = 0.022 and < 0.0001, respectively), whereas leptin concentrations were higher (P for trend = 0.0001). Relating all adipokines to MetS conjointly, higher ghrelin and leptin concentrations were associated with decreased and increased odds of MetS (odds ratio 0.55, P < 0.0001; odds ratio 4.44, P = 0.0002, per 1 sd increase of respective log adipokine).

CONCLUSIONS

In our community-based sample, we observed a sexual dimorphism in circulating ghrelin and leptin concentrations. Ghrelin, leptin, and sOB-R were associated with number of MetS components cross-sectionally, consistent with the hypothesis that these adipokines may have a central role in cardiometabolic risk.

Adiponectin receptor R1 is upregulated by valproic acid but not by topiramate in human hepatoma cell line, HepG2

Valproic acid (VPA) is an effective and widely used anticonvulsant, associated with metabolic adverse effects such as weight gain, hyperinsulinemia, hyperleptinemia and hypoadiponectinemia. The aim of this study was to evaluate the influence of VPA and topiramate (TPM) on adiponectin binding receptors, adipoR1 and adipoR2, in human liver cancer cells, HepG2. AdipoR1 but not adipoR2 gene expression was upregulated by VPA treatment. TPM did neither affect adipoR1 nor adipoR2 gene expression. Given the tight association between VPA treatment, metabolic side effects and the adipocytokine-axis, upregulation of adipoR1 possibly represents a favoured and insulin-sensitizing mechanism.

Interactions between ghrelin, leptin and IGF-I affect metabolic syndrome and early atherosclerosis

BACKGROUND

High leptin and low ghrelin are associated with the metabolic syndrome (MS).

AIMS AND METHODS

Ghrelin, leptin (RIA kits), and insulin-like growth factor I (IGF-I) (ELISA kit) concentrations of the population-based cohort of 1045 subjects and their interactions with metabolic parameters were analysed. Intima-media thickness (IMT) was measured with carotid ultrasound.

RESULTS

The interaction between leptin and ghrelin on the MS was significant (P = 0.011). An additive effect of high leptin and low ghrelin on metabolic disturbances was observed: low ghrelin concentration (adjusted for age and sex) (P < 0.001) was associated with the MS and type 2 diabetes in the highest but not in the lower leptin quartiles. In the highest leptin quartile, ghrelin concentrations decreased linearly when the number of International Diabetes Federation MS criteria met (P < 0.01) increased. Ghrelin-leptin relation was independently associated with carotid IMT (P < 0.005). The independent positive association (P < 0.01) between the plasma ghrelin quartile and the carotid IMT was evident in the lowest IGF-I quartile.

CONCLUSIONS

Low ghrelin is associated with MS and type 2 diabetes in the presence of insulin and leptin resistance. Ghrelin-leptin relation is associated with early atherosclerosis. The interaction between IGF-I and ghrelin modifies the association of ghrelin with early atherosclerosis.

The change of serum leptin and its relationship with platelet membrane glycoprotein Ib in patients with coronary heart disease

The aim of this paper was to investigate the change of serum leptin and its relationship with platelet membrane glycoprotein Ib (GP Ib) in patients with coronary heart disease (CHD). The enrolled included 50 patients with CHD (CHD group) and 30 patients without CHD (control group) who were diagnosed by coronary angiography. The positive percentage and the average fluorescence intensity of platelet membrane GP Ib were detected by full-blood flow cytometry. Serum leptin was detected by enzyme linked immunosorbent assay. The positive percentage and the average fluorescence intensity of platelet membrane GP Ib in the CHD group were significantly lower than those in the control group (P < 0.05). After correcting the differences of systolic blood pressure, body mass index (BMI), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting glucose, PPBS, fasting insulin and quantitative insulin sensitive index, serum leptin level in the CHD group was significantly higher than that in the control group (P < 0.05). Single factor correlative analysis revealed that serum leptin in CHD patients was negatively correlated with the average fluorescence intensity of platelet membrane GP Ib (P < 0.05). Multifactorial stepwise regression analysis showed that serum leptin in CHD patients was independently negatively correlated with the average fluorescence intensity of platelet membrane GP Ib (P < 0.05). Logistic analysis demonstrated that serum leptin was independently correlated with the risk of CHD (P < 0.05). Hyperleptinemia was verified in CHD patients. The increase of serum leptin could affect blood platelet activation. Hyperleptinemia may play an important role in the pathogenesis of CHD.

Leptin and high-sensitivity C-reactive protein and their interaction in the metabolic syndrome in middle-aged subjects

High-sensitivity C-reactive protein (hsCRP) and leptin, known to interact at the molecular level, have been associated with the metabolic syndrome (MS). We examined the independent and joint effects of high leptin and hsCRP levels on the development of MS in a population-based cohort of middle-aged subjects (N = 1035). Leptin and hsCRP levels increased with an increase in the number of metabolic abnormalities (P < .001). However, additional adjustment for body mass index diluted the association of leptin with MS in women. In men, the association of high leptin with insulin resistance and waist circumference (P < .001), and in women, the association of high hsCRP with insulin resistance (P = .029) and waist circumference (P = .009) persisted in the multivariate logistic regression models. High leptin in men and high hsCRP in women were significant predictors of MS in logistic regression analysis (P < .001). The highest prevalence of MS (86% in men and 71% in women) was observed in the subjects who belonged to the highest quartile in both leptin and hsCRP. MS is associated independently with high leptin in men and with hsCRP in women, whereas individuals with both of these markers belong to the highest risk of metabolic cluster. The study suggests sex-specific interplay between metabolic and inflammatory markers in the pathogenesis of MS.

Megalin mediates the transport of leptin across the blood-CSF barrier

Leptin, a peptide hormone secreted by adipose tissue, exhibits a large range of central and peripheral actions. It has been proposed that the participation of leptin in diseases such as obesity is due to, at least in part, its impaired transport across the blood-brain barrier (BBB). Since, the mechanisms by which brain takes up leptin remain unclear, we set out to study how leptin may cross the BBB. We have used different immunoassays and lentiviral vectors to analyze the role of megalin in the transport of leptin in rodents and humans. We demonstrate that circulating leptin is transported into the brain by binding to megalin at the choroid plexus epithelium. Indeed, the downregulation of megalin expression in physiological and pathological situations such as aging and Alzheimer's disease was correlated with poor entry of leptin into the brain. Moreover, amyloid beta (Abeta) deposits of choroid plexus could be disturbing megalin function. The present data indicate that leptin represents a novel megalin ligand of importance in the levels and therapeutic actions of leptin into the brain.

Plasma Levels of Leptin Are Associated with the Plasma Levels of LDL Conjugated Dienes in Children

BACKGROUND

Plasma leptin has been suggested to be involved in the proatherogenic process by increasing oxidative stress. We investigated the relationship between leptin and plasma conjugated diene formation, a measure of LDL oxidation in vivo in schoolchildren.

METHODS

We measured blood lipid profiles, plasma antioxidant vitamins, leptin and diene conjugation in LDL of 118 Korean children (35 overweight-obese vs. 83 normal weight children).

RESULTS

The overweight-obese children showed significantly higher levels of leptin (p < 0.0001), conjugated dienes (p = 0.02), total cholesterol (p < 0.05), triglyceride (p < 0.005) and LDL cholesterol (p < 0.01) and a significantly lower level of plasma lycopene (p < 0.0001) compared with the normal weight children. When all the subjects were classified into the three groups by tertiles of leptin levels, significant differences in circulating conjugated dienes (p < 0.05), lipid-corrected lycopene (p < 0.05), total cholesterol (p < 0.05), triglyceride (p < 0.05) and LDL cholesterol (p < 0.05) were found among the three groups.

CONCLUSION

Our results showed that leptin was positively associated with the LDL conjugated diene formation, which might be related to the proatherogenic process in schoolchildren.

Valproate, weight gain and carbohydrate craving: a gender study

PURPOSE

To compare the incidence and magnitude of weight gain associated with valproic acid (VPA) monotherapy in male and female epilepsy patients and to determine possible gender-specific differences in frequency of carbohydrate craving, body-composition, glucose homeostasis and lipid metabolism.

METHODS

Epilepsy patients on VPA monotherapy were consecutively recruited at the outpatient clinic of the Department of Neurology, Innsbruck Medical University. Weight gain during VPA-therapy, frequency of carbohydrate craving and physical exercise, sociopsychological problems and family history for diabetes were obtained from all patients. Clinical data also comprised body-impedance analysis, body mass index and waist-to-hip ratio. Morning fasting blood samples were drawn to determine serum leptin, glucose and lipid concentrations, as well as insulin, C-reactive protein and TNF-alpha.

RESULTS

One hundred and six patients (55 women) were enrolled in the study. Significant weight gain was seen during VPA-therapy in both genders (each p<0.001) with women experiencing increment of weight more frequently and more pronounced than did men. Analyses of patients who gained weight during VPA-therapy revealed significantly higher serum leptin concentrations in women than in men (p<0.001). Women also revealed significantly higher high-density lipoprotein-cholesterol and lower triglyceride concentrations than men (p=0.004 and 0.014, respectively). Frequency of carbohydrate craving was 25.8% in women and 14.3% in men. More women tried to lose or control weight through diet than did men (22.6% versus 7.1%). Moreover, weight gain as a sociopsychological problem was more numorous in women than in men.

CONCLUSION

Women are more prone to gain weight during VPA therapy though higher frequency of diet and sociopsychological burden than men, which might possibly be related to leptin-resitance and a higher frequency of carbohydrate craving.

Hemostasis and fibrinolysis in non-diabetic overweight and obese men and women. Is there still a role for leptin?

OBJECTIVE

Leptin has been associated with disturbances in hemostasis and fibrinolysis, with inconsistent results on the influence of fat mass. However, the influence of the amount of visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (SAT) has not yet been studied. In this study, we investigated the relationship between leptin and fibrinogen, von Willebrand factor antigen (vWF:Ag), and plasminogen-activator inhibitor-1 (PAI-1) activity and determined the influence of associated metabolic variables and VAT versus SAT.

METHODS

Fibrinogen, vWF:Ag, PAI-1,VAT and SAT (CT-scan), and insulin resistance (homeostasis model assessment; HOMA-IR) were measured in 199 women and 81 men with overweight or obesity visiting the weight management clinic of a university hospital.

RESULTS

Leptin did not relate to fibrinogen (r = 0.11 and 0.13 in women and men respectively; P > 0.05), a relationship with vWF:Ag was only found in men (r = 0.31; P = 0.005), while leptin related to PAI-1 activity in both men (r = 0.36; P < 0.001) and women (r = 0.23; P < 0.001). Further analysis showed leptin to have an effect on the variation of PAI-1 independent of VAT and HOMA-IR in women, but not in men. Multiple regression showed HOMA-IR to be the most important determinant of PAI-1, both in men and women, but leptin also showed an independent effect. As for vWF:Ag, leptin was an independent determinant in men only.

CONCLUSIONS

PAI-1 related to leptin levels independent of fat mass percentage, HOMA-IR, and the amount of VAT and SAT. For vWF:Ag this relationship was found only in men, and not in women, while a relationship with fibrinogen could not be demonstrated.

Leptin: a potential biomarker for childhood obesity?

Leptin, a hormone made by adipocytes, is an important circulating signal for the regulation of body weight. A review of the scientific literature (PubMed Search 1994 to 2005) for studies examining the relationship among leptin, pediatric obesity and the impact of exercise intervention programmes on leptin concentrations are summarized. The potential utility of leptin as a biomarker for identifying children at risk of obesity is discussed. This literature review demonstrated that (1) leptin directly interacts with the hypothalamus for energy balance regulation; (2) the measurement of free, bound and total leptin as well as soluble leptin receptor concentration are critical for our understanding of obesity in children; and (3) leptin concentration may be an important factor for determining intervention programme responsiveness in pediatric obesity.

Oxidative Stress and Adverse Adipokine Profile Characterize the Metabolic Syndrome in Children

Thirty-four children were assessed for body composition, blood pressure, lipids, glucose tolerance, markers of insulin resistance, oxidative stress, and adipokines. Children were divided into 3 groups: (1) normal weight, (2) overweight but otherwise healthy, and (3) overweight with the metabolic syndrome. There were no differences among any of the groups for age or Tanner stage, and anthropometric variables were similar between the overweight and the overweight with the metabolic syndrome groups. Differences across groups were found for high-density lipoprotein cholesterol (P < .001), triglycerides (P < .01), fasting insulin (P < .001), homeostasis model assessment (P < .01), adiponectin (P < .05), leptin (P < .0001), C-reactive protein (P < .0001), interleukin 6 (P < .0001), and 8-isoprostane (P < .001). In children, oxidative stress and adipokine levels worsen throughout the continuum of obesity and especially in the presence of components of the metabolic syndrome. Overweight children with components of the metabolic syndrome may be at elevated risk for future cardiovascular disease.

Metabolic syndrome and leptin concentrations in obese children

OBJECTIVE

Obesity and its complications including metabolic syndrome has been increased in children and adolescents recently. Leptin is known to play an important role in the pathogenesis of obesity.

METHODS

The objective of this study was to evaluate the relationship of leptin and metabolic syndrome in obese Iranian children. A cross sectional study was carried out in 65 primary schools in Tehran. The children with waist circumferences equal or above 90th percentile for their height and age were chosen for further evaluations. 505 children aged 7-12 years participated in the study. Anthropometric variables measurements, blood pressure, fasting plasma glucose, triglyceride, high-density lipoprotein cholesterol and serum leptin were obtained from the study sample.

RESULTS

Serum leptin levels were significantly higher in girls in comparison to the boys (with median 11.0 Vs 8.25 ng/dl; P value = 0.007). Serum level of leptin were higher in children with metabolic syndrome (median 11.3 Vs 8.9 ng/dl; P value = 0.045). However, after adjustment for sex, this association was removed.

CONCLUSION

Leptin did not appear to have a major role in metabolic syndrome, even though it was strongly associated with obesity parameters. More studies evaluating the relationship between leptin and metabolic syndrome in various ethnic groups are recommended.

Plasma leptin response to oral glucose tolerance and fasting/re-feeding tests in rats with fructose-induced metabolic derangements

The aim of this study was to compare the postprandial leptin response in rats with and without metabolic syndrome induced by a fructose-enriched diet. The effect of aging and the association between variations in metabolic substrates was also evaluated. Oral glucose tolerance test (OGTT) and fasting/re-feeding test were used to evaluate the responses of leptin and to explore the dynamic relationship between endogenous leptin and metabolic substrates, including glucose, insulin and triglycerides (TG). At the 7th week, plasma leptin was unchanged in control rats after oral glucose loading. However, plasma leptin levels increased in fructose-fed rats with insulin resistant OGTT curves. At the 11th month, plasma leptin level was reduced during starvation and returned to the level prior to starvation during re-feeding in control rats. In contrast, the starvation-induced reduction in leptin showed a potentially larger rebound effect during re-feeding in fructose-fed rats. Analysis of covariance demonstrated that there alone was no interactive effect of dietary manipulation between leptin and TG, suggesting that fructose diet-induced insulin resistance-related metabolic syndrome may concomitantly elevate leptin and TG. Furthermore, multiple regression analysis suggests TG was the primary correlative determinant of endogenous leptin concentration. Our data showed that there are different patterns of leptin response to OGTT and fasting/re-feeding tests in rats with and without metabolic syndrome. The results suggest that these effects may be related to a TG-mediated impairment of leptin function and a protective mechanism to reduce lipid-induced tissue damage in patients with metabolic syndrome.

Hyperhomocysteinemia correlates with insulin resistance and low-grade systemic inflammation in obese prepubertal children

Obesity is an independent risk factor for the development of cardiovascular disease frequently associated with hypertension, dyslipemia, diabetes, and insulin resistance. Higher homocysteine (Hcy) levels are observed in the hyperinsulinemic obese adults and suggest that Hcy could play a role in the higher risk of cardiovascular disease in obesity. We analyzed total Hcy levels in obese prepubertal children and their possible association with both metabolic syndrome and various inflammatory biomarkers and leptin. We studied 43 obese children (aged 6-9 years) and an equal number of nonobese children, paired by age and sex. The obese subjects presented significantly elevated values for insulin (P = .003), C-reactive protein (P = .033), and leptin (P < .001). No significant differences were found in Hcy levels between the obese and nonobese children. However, Hcy concentration was significantly higher in the hyperinsulinemic obese children than in the normoinsulinemic group (P = .002). Using multivariant regression analysis, in the obese group, corrected for age and sex, the homeostasis model assessment for insulin resistance (P partial = .001) and leptin (P partial = .02) are independent predictive factors for Hcy. In the control group, corrected for age and sex, the homeostasis model assessment for insulin resistance (P partial = .005) and leptin (P partial = .031) also are independent predictive factor for Hcy. Increased plasma Hcy, particularly in hyperinsulinemic obese children, may be causally involved in the pathogenesis of atherosclerosis and/or cardiovascular disease, both of which are common in obesity.

Alleles on rat chromosome 4 (D4Got41-Fabp1/Tacr1) regulate subphenotypes of obesity

OBJECTIVE

The use of inbred animal models is an essential component of the genetic dissection of complex diseases. Because quantitative trait loci for serum triglycerides, total cholesterol, and body weight were mapped on chromosome 4 in a cross of BioBreeding/OttawaKarlsburg (BB/OK) and spontaneously hypertensive (SHR) rats, we established a congenic BB.SHR rat strain by introgressing a SHR segment of chromosome 4 (D4Got41-Tacr1) into a BB/OK background. The phenotype of these BB.SHR rats (BB.4S) confirmed the quantitative trait loci. To discover whether the phenotype of BB.4S can only be attributed to the SHR segment per se, we established an additional congenic BB.WOKW strain by introgressing a similar segment of chromosome 4 (D4Got41-Fabp1) of the Wistar Ottawa Karlsburg RT1(u) rat into a BB/OK background, termed briefly BB.4W.

RESEARCH METHODS AND PROCEDURES

Male normoglycemic BB/OK (20), BB.4S (20), and BB.4W (16) rats were longitudinally studied for body weight, serum triglycerides, total and high-density lipoprotein-cholesterol, and glucose tolerance. At the end of the observation period (32 weeks), serum insulin, leptin, and adiposity index (AI) were determined.

RESULTS AND DISCUSSION

Congenic BB.4S and BB.4W were significantly heavier, and AI, serum triglycerides, and total cholesterol values were significantly elevated in BB.4S and BB.4W compared with BB/OK but more pronounced in BB.4S. The highest serum insulin was found in BB.4W and highest leptin in BB.4S. Because the body weight gain and AI were comparable between BB.4S and BB.4W, the obviously higher insulin levels in BB.4W and higher leptin values in BB.4S suggest that the two congenics most probably define two subphenotypes of obesity and provide the unique opportunity to study their genetics.

Serum and urine leptin concentration in children with nephrotic syndrome

Literature data point to the relationship between leptin concentration and certain markers of the metabolic syndrome, including cholesterol, triglycerides and apolipoproteins. A substantial lipid metabolism disturbance occurs in children with idiopathic nephrotic syndrome (NS). The aim of the study was to find out whether in NS children, serum and urine leptin levels change proportionally to lipid metabolism disturbances. The study was performed on two groups: (I) 30 children with NS (A) before, (B) during, prednisone therapy after proteinuria regression; (II) 25 healthy children. Serum and urine leptin levels were determined by the immunoenzymatic ELISA method. Serum leptin level in NS children before and after treatment was similar to that in the control group (p>0.05). Leptin urinary excretion in group A was approximately 60 times and in group B 24 times higher than in the controls (p<0.01). Before treatment, children with NS had increased concentrations of TC, TG, LDL, beta-lipoprotein, apolipoprotein B (apo B) (p<0.01) and reduced HDL and apolipoprotein A (apo A) (p<0.01). The conclusions were that: (1) in NS children leptin urinary excretion increases but its level is unchanged in serum; (2) serum leptin level is correlated with lipid parameters.

The effect of plasminogen activator inhibitor-1 gene 4G/5G polymorphism on glucose and lipid metabolisms in Turkish obese children

OBJECTIVE

Obesity is a metabolic disorder that is associated with increased plasminogen activator inhibitor-1 (PAI-1) concentration in the circulation. This increase is related to insulin resistance, dyslipidaemia and cardiovascular disease. Some studies have demonstrated a relationship between plasma PAI-1 concentrations and the 4G/5G gene polymorphism in the PAI-1 gene, while other studies have not. It is well known that plasma PAI-1 levels are increased in obesity; however, the relationship between the polymorphism and obesity remains unclear. In this study, we aimed to elucidate the effect of the PAI-1 4G/5G polymorphism on glucose and lipid metabolism parameters in Turkish obese children.

DESIGN AND PATIENTS

Ninety children with obesity (37 male, 53 female; mean age 11.1 +/- 3.4 years; range 5.8-17.6 years) were included in the study. The children were divided into three groups according to the PAI-1 promoter 4G/5G polymorphism (4G/4G, 4G/5G and 5G/5G). These groups were compared for age, body mass index (BMI), serum glucose, lipid and insulin levels, and homeostasis model assessment of insulin resistance (HOMA-IR) score.

RESULTS

The genotype distribution was 52% (47/90) 4G/4G, 25% (22/90) 4G/5G and 23% (21/90) 5G/5G. No statistically significant differences among genotype groups were found with respect to age, BMI, serum levels of glucose, lipid and insulin, and HOMA-IR score.

CONCLUSION

Although the frequency of the 4G/4G genotype was higher in subjects in the current study than in subjects reported in the literature, in our study group we observed no influence of the PAI-1 4G/4G polymorphism on lipid and glucose metabolism.

Independent circadian and sleep/wake regulation of adipokines and glucose in humans

Leptin and adiponectin play important physiological roles in regulating appetite, food intake, and energy balance and have pathophysiological roles in obesity and anorexia nervosa. To assess the relative contributions of day/night patterns in behaviors (sleep/wake cycle and food intake) and of the endogenous circadian pacemaker on observed day/night patterns of adipokines, in six healthy subjects we measured circulating leptin, soluble leptin receptor, adiponectin, glucose, and insulin levels throughout a constant routine protocol (38 h of wakefulness with constant posture, temperature, and dim light, as well as identical snacks every 2 h) and throughout sleep and fasting periods before and after the constant routine. There were significant endogenous circadian rhythms in leptin, glucose, and insulin, with peaks around the usual time of awakening. Sleep/fasting resulted in additional systematic decreases in leptin, glucose, and insulin, whereas wakefulness/food intake resulted in a systematic increase in leptin. Thus, the day/night pattern in leptin is likely caused by combined effects from the endogenous circadian pacemaker and day/night patterns in behaviors. Our data imply that alterations in the sleep/wake schedule would lead to an increased daily range in circulating leptin, with lowest leptin upon awakening, which, by influencing food intake and energy balance, could be implicated in the increased prevalence of obesity in the shift work population.