Leptin: a potential biomarker for childhood obesity?

Neuroendocrinological and Clinical Aspects of Leptin

Obesity is characterized by an abnormal increase in adipose tissue mass and is regarded as a neurobehavioral as well as a metabolic disorder. Increases in body fat are caused by even slight, long-term discrepancies between energy intake and energy expenditure. It is a chronic condition linked to the metabolic syndrome, a spectrum of risky conditions, such as diabetes, high blood pressure, and heart disease. With a swiftly rising prevalence, obesity has emerged as a significant global health concern. Leptin influences the brain's neuroendocrine and metabolic processes, which is important for maintaining energy homeostasis. White adipose tissue secretes the majority of leptin, and there is a positive correlation between leptin levels in the blood and body fat percentages. The central nervous system is also modulated by leptin levels to modify energy intake and usage. The idea of an obesity cure sparked excitement after it was discovered more than 25 years ago. However, the leptin medication only effectively reduces weight in patients with congenital leptin insufficiency and not in patients with typical obesity who may also have leptin resistance. Recent research has focused on the role of leptin in managing weight reduction and preventing "yo-yo dieting". This review concentrates on the neurological effects of leptin with a focus on therapeutic and diagnostic applications, particularly for childhood obesity.

Evaluation of aptamer and molecularly imprinted polymers as a first hybrid sensor for leptin detection at femtogram levels

Selective and sensitive determination of macromolecules maintains its importance in diagnosing and determining diseases to protect human health. In this study, a hybrid sensor designed with dual recognition elements consisting of both aptamers (Apt) and molecularly imprinted polymers (MIPs) was carried out for the ultra-sensitive determination of Leptin. Firstly, the screen-printed electrode (SPE) surface was coated with platinum nanospheres (Pt NSs) and gold nanoparticles (Au NPs) to provide immobilization of the Apt[Leptin] complex on the surface. In the next step, the formed polymer layer around the complex using the electropolymerization of orthophenilendiamine (oPD) kept the Apt molecules on the surface more effectively. As expected, a synergistic effect occurred between the formed MIP cavities by removing Leptin from the surface and the embedded Apt molecules to fabricate a hybrid sensor. Under optimal conditions, responses in differential pulse voltammetry (DPV) currents showed a linear response over a wide concentration range from 1.0 fg/mL to 10.0 pg/mL with a limit of detection (LOD) of 0.31 fg/mL for Leptin detection. Moreover, the effectiveness of the hybrid sensor was assessed using real samples, such as human serum and plasma samples, and satisfactory recovery findings (106.2-109.0%) were found.

The ALINFA Intervention Improves Diet Quality and Nutritional Status in Children 6 to 12 Years Old

The study aimed to evaluate the efficacy of a new nutritional intervention, focused on improving the quality of the diet in children aged 6 to 12 years. A 2-month parallel, controlled randomized trial was conducted in the Spanish child population. The children were randomized to ALINFA nutritional intervention, which consisted of a normocaloric diet that incorporates products, ready-to-eat meals and healthy recipes specifically designed for the study, or a control group, which received the usual advice on healthy eating. The change in diet quality was assessed through the Kidmed index. The secondary outcomes were anthropometry, glucose and lipid profiles, inflammation markers, dietary intake and lifestyle. The participants in the intervention group showed an increase in the mean score of the Kidmed index (p < 0.001). Alongside that, these children decreased their intake of calories (p = 0.046), and total and saturated fat (p = 0.016//p = 0.011), and increased fiber intake (p < 0.001). Likewise, the children in the ALINFA group increased the intake of white fish (p = 0.001), pulses (p = 0.004), whole grains (p < 0.001) and nuts (p < 0.001), and decreased fatty meat (p = 0.014), refined grain (p = 0.008), pastry (p < 0.001), fast food (p < 0.001) and sugar (p = 0.001) intake. Moreover, these children had a significantly decreased BMI (p < 0.001), BMI z-score (p < 0.001), waist circumference (p = 0.016) and fat mass (p = 0.011), as well as leptin (p = 0.004). Participants in the control group did not report significant changes in diet quality. In conclusion, ALINFA nutritional intervention is possibly a useful strategy to increase the diet quality in children, which is associated to improvements in the nutritional status. These results highlight the importance of developing well-designed nutritional interventions.

Polyphenol-rich oolong tea alleviates obesity and modulates gut microbiota in high-fat diet-fed mice

Obesity is a major public health issue worldwide. Oolong tea (OT), which is partially fermented from Camellia sinensis leaves, has proven health benefits and potential preventive applications in multiple studies. However, research on the role of OT in obesity prevention and potential mechanisms is still limited. The purpose of this study was to investigate the modulatory effects of OT intervention on high-fat diet (HFD)-induced obesity and gut microbiota dysbiosis using an obese mouse model. Our results showed that 8-week OT supplementation with 93.94% polyphenols significantly decreased body weight gain, adipose tissue mass, and serum levels of triglyceride (2.60 mmol/L), cholesterol (5.49 mmol/L), and low-density lipoprotein cholesterol (0.61 mmol/L) in HFD-fed mice. Meanwhile, OT intervention was observed to improve fat accumulation, hepatic damage, glucose intolerance, and endotoxemia and alleviate inflammation by decreasing the levels of pro-inflammatory factors. OT also upregulated the expression of genes including Srebf1, Ppara, Lxra, Pgc1a, and Hsl and downregulated the expression of genes including Leptin, Il-6, and Il-1b. In addition, the gut dysbiosis characterized by decreased flora diversity and increased Firmicutes/Bacteroidetes ratio in obese mice was recovered by OT intervention. Certain differentially abundant microbes caused by HFD feeding, including Enterococcus, Intestinimonas, Blautia, and Bilophila, were also improved by OT treatment. This study demonstrated that OT, as a novel resource of dietary polyphenols, exhibited a protective effect on HFD-induced obesity and gut microbiota disorder.

Association between Leptin (G2548A) and Leptin Receptor (Q223R) Polymorphisms with Plasma Leptin, BMI, Stress, Sleep and Eating Patterns among the Multiethnic Young Malaysian Adult Population from a Healthcare University

Relative leptin resistance in childhood to absolute leptin resistance in maturity suggests sleep, eating behaviour, and the psychological state as probable causes. The current body of research provides inconclusive evidence linking G2548A and Q223R to obesity. Furthermore, we could find very little data that have observed the association between the environment and gene polymorphism, especially in the multiethnic population that exists in Malaysia. This study searched for a possible link between sleeping habits, eating behaviour, and stress indicators with plasma leptin and its genetic variation in young adult Malaysian healthcare students. The study involved 185 first- and second-year medical and dental students from a healthcare university. Polymerase Chain Reaction−Restriction Fragment Length Polymorphism(PCR-RFLP) determined the genotype, Enzyme Linked Immunoabsorbant Assay (ELISA) tested the serum leptin, and a self-administered questionnaire evaluated sleep, eating behaviour, and psychological condition. Gender and ethnicity are linked to fasting plasma leptin levels (p < 0.001). Plasma leptin also affects stress, anxiety, and sadness. Leptin (LEP) and Leptin Receptor (LEPR) polymorphisms were not associated with BMI, plasma leptin, sleep, eating behaviour, or psychological state. Young adult Malaysian Indians were obese and overweight, while Chinese were underweight. These findings imply overweight and obese participants were in stage I of leptin resistance and lifestyle change or leptin therapy could prevent them from becoming cripplingly obese as they age.

Similar effects of milk protein and blends of milk and plant-based protein on appetite-related hormones in 7- to 8-year-old healthy Danish children: secondary analyses from the PROGRO randomised trial

AIM

The effect of different protein sources on the appetite-related hormones in children is largely unknown. We investigated the effect of milk protein versus blends of milk and rapeseed protein on plasma leptin and adiponectin in children.

METHODS

We included 88 Danish 7- to 8-year-old children randomised to receive 35 g protein/day for 4 weeks in 2018 as either milk protein or blends of milk and rapeseed protein (ratio 54:46 or 30:70). Outcomes included absolute and fat mass-adjusted adiponectin and leptin measured at baseline, Weeks 1 and 4.

RESULTS

There was no difference in changes in absolute and fat mass-adjusted adiponectin and leptin after 1 or 4 weeks between the three groups (p ≥ 0.100). Leptin increased within all groups (p ≤ 0.046). Combining the three groups, leptin and fat mass-adjusted leptin increased by 23% (95% CI 11;35) and 17% (6.4;29) during the intervention respectively (both p ≤ 0.001). Adiponectin variables did not change during the intervention period.

CONCLUSION

There were no differences between milk protein and blends of milk and rapeseed protein on absolute and fat mass-adjusted leptin and adiponectin in healthy children with a habitual intake of milk. However, leptin increased within all three groups. Future studies should further investigate effect on appetite-related hormones of rapeseed protein alone.

Causative Mechanisms of Childhood and Adolescent Obesity Leading to Adult Cardiometabolic Disease: A Literature Review

The past few decades have shown a worrisome increase in the prevalence of obesity and its related illnesses. This increasing burden has a noteworthy impact on overall worldwide mortality and morbidity, with significant economic implications as well. The same trend is apparent regarding pediatric obesity. This is a particularly concerning aspect when considering the well-established link between cardiovascular disease and obesity, and the fact that childhood obesity frequently leads to adult obesity. Moreover, most obese adults have a history of excess weight starting in childhood. In addition, given the cumulative character of both time and severity of exposure to obesity as a risk factor for associated diseases, the repercussions of obesity prevalence and related morbidity could be exponential in time. The purpose of this review is to outline key aspects regarding the current knowledge on childhood and adolescent obesity as a cardiometabolic risk factor, as well as the most common etiological pathways involved in the development of weight excess and associated cardiovascular and metabolic diseases.

Changes of omentin-1 and chemerin during 4 weeks of lifestyle intervention and 1 year follow-up in children with obesity

AIMS

Data about the influence of short-term lifestyle intervention in children with obesity on long-term follow-up body weight, adipokines and cardiometabolic risk parameters is scarce.

METHODS

In a subgroup of the LOGIC-trial (Long-term Effects of Lifestyle Intervention in Obesity and Genetic Influence in Children), we assessed anthropometry (BMI, BMI-SDS (Standard Deviation Score), adipokines (omentin-1, chemerin, leptin, adiponectin) and cardiometabolic risk parameters, (e.g. hsCRP) in children with overweight/obesity after 4 weeks of lifestyle intervention (n = 156, 14.0 ± 1.8 yrs) and after one year follow-up (n = 50). Data were compared to normal weight children (JuvenTUM school cohort; n = 152, 13.3 ± 0.7 yrs).

RESULTS

Short-term lifestyle intervention was associated with a significant reduction in BMI and BMI-SDS (p < 0.001), with significant reductions in hsCRP, leptin, and chemerin levels, and an increase in adiponectin and omentin-1 levels (p < 0.001 for all). After one year follow-up a significant reduction in BMI and BMI-SDS was observed in children from the LOGIC-trial (p < 0.001). Improvements in adiponectin (p = 0.025) and chemerin levels (p = 0.027) were seen in children with clear weight loss success (BMI-SDS reduction ≥ 0.2), whereas children with no or only mild weight loss success showed an increase in leptin levels (p < 0.001). An increase in omentin-1 levels was observed after 1 year independent of weight change (p < 0.001).

CONCLUSION

Effects of short-term weight reduction on mean BMI and BMI-SDS persist over one year. Improvements in omentin-1 levels were independent of short-term or long-term weight loss.

TRIAL REGISTRATION

ClinicalTrials.gov: LOGIC-trial: NCT01067157, JuvenTUM-trial: NCT00988754.

Association between pubertal development stages and body adiposity in children and adolescents

Background

The study aimed to analyze the association between pubertal development stages and adiposity in children and adolescents.

Methods

Cross-sectional study conducted in 2007 in Florianópolis, Brazil, with 2339 schoolchildren 32 aged 8 to 14 years old (1107 males). The outcome (adiposity) was evaluated using Z score and 33 percentilee values > = 85 of four skinfolds (triceps, subscapular, suprailiac and calf) and waist 34 circumference. Total body adiposity (Z score of the sum of skinfolds), central adiposity (Z score 35 of waist circumference) and peripheral adiposity (Z scores of triceps and calf skinfolds) were 36 estimated. Pubertal development stages was self-assessed according to Tanner stages of development. Thirty-seven Children and adolescents were classified according to tertiles of age for each pubertal development stages 38 stage - early, normal and late. Statistical analysis was performed using univariate and 39 multivariate Poisson regression models.

Results

Children and adolescent from both sexes with early pubertal development stages presented higher prevalence of central adiposity (waist circumference), with adjusted prevalence ratio (CI 95%) of 2.21 (1.12; 4.35) for males and 2.18 (1.04; 4.57) for females (reference group: normal pubertal development stages). Among females, there was a reduction in the prevalence of excess adiposity with decreased occurrence of early pubertal development stages. There was a strong relationship between adiposity and pubertal development stages.

Conclusions

Excess adiposity was higher in both sexes for those with early pubertal development stages.

The effect of weight loss on body composition, serum bone markers, and adipokines in prepubertal obese children after 1-year intervention

Purpose/Aim: The influence of weight loss on bone turnover and bone quality in childhood remains controversial, but it may implicate interactions between adiposity and bone metabolism. Therefore, we studied the relationships between bone markers and adipokines during weight loss in obese children.

MATERIALS AND METHODS

We determined serum leptin, soluble leptin receptor, adiponectin, bone alkaline phosphatase (BALP), C-terminal telopeptide of type I collagen (CTX-I), osteocalcin (OC), carboxylated-OC (Gla-OC), undercarboxylated-OC (Glu-OC), sclerostin, body composition, and bone mineral density (BMD) in 40 obese prepubertal children before and after therapy. The control group, matched for sex and age, consisted of 40 non-obese children.

RESULTS

We found that values of the total body less head-bone mineral content (TBLH-BMC) and TBLH-BMD were significantly increased, but TBLH-BMD Z-score was decreased by 25% (p = 0.002) in obese children with weight loss after therapy. We observed increases of CTX-I to OC ratio (p = 0.009), and Gla-OC concentrations (p = 0.049). Changes in TBLH-BMD Z-score in patients were positively correlated with changes in BMI Z-score (p = 0.001), percentage of fat mass (p = 0.004), and BALP activity (p = 0.01). Changes in BALP activity were negatively correlated (p < 0.001) with changes in adiponectin concentrations, while changes in sclerostin levels were positively correlated (p = 0.001) with leptin changes.

CONCLUSIONS

We suggest that alterations in adipokines metabolism were associated with a lower rate of bone mineral accrual as a result of decreased bone formation rather than increased bone resorption. The lower rate of bone mass accrual in weight losing children may be an effect of reduced BALP levels related to increase in adiponectin levels.

Association of cord blood ghrelin, leptin and insulin concentrations in term newborns with anthropometric parameters at birth

BACKGROUND

Ghrelin, leptin and insulin, generally considered as regulators of energy homeostasis of the organism may be related to fetal and early postnatal growth. Numerous studies have confirmed the presence of these hormones in the cells of the fetus indicating their importance in development at early stages of life.

METHODS

This study analyzed active and total ghrelin by radioimmunoassay (RIA), leptin and insulin concentrations by enzyme-linked immunosorbent assay (ELISA) in 65 cord blood samples, from term newborns, and measured the birth anthropometric parameters [birth weight (BW), head circumference, chest, stomach, thigh and arm circumference].

RESULTS

Active ghrelin (AG) concentrations correlated negatively with BW, head circumference, stomach and thigh circumference. When divided by gender, AG correlated negatively with males' BW, stomach and thigh circumference. Females' head circumference correlated negatively with AG. Cord leptin correlated positively with arm circumference. When divided by gender, cord leptin was positively associated with BW and stomach circumference in male newborns and with thigh and arm circumference in female newborns. Insulin concentrations tended to correlate positively with BW in male newborns.

CONCLUSIONS

In summary, it was confirmed that cord blood ghrelin, leptin and insulin correlate with anthropometric parameters at birth. This study showed a negative correlation of AG with anthropometric parameters, which may emphasize that this hormone is an indicator of growth restriction. This is in contrast to cord leptin and insulin, which are more connected with overgrowth. Taking all the results into consideration, the metabolic status of the fetus and newborn is an essential component in understanding the regulation of perinatal development.

The effects of antipsychotics on weight gain, weight-related hormones and homocysteine in children and adolescents: a 1-year follow-up study

To analyze weight gain, metabolic hormones, and homocysteine (Hcys) levels in children and adolescents on antipsychotics (AP) during a year-long follow-up. 117 patients, AP-naïve or quasi-naïve (less than 30 days on AP), were included. Weight, body mass index (BMI), BMI z-score (z-BMI), and levels of leptin, insulin, insulin resistance (HOMA-IR), adiponectin, ghrelin, thyroid stimulating hormone (TSH), free thyroxine (FT4), and Hcys were measured at baseline, and at 3, 6, and 12 months, while patients remained on the same AP. Patients (mean age: 14.4 ± 3 years; 64.1 % male) were on risperidone (N = 84), olanzapine (N = 20) or quetiapine (N = 13) from baseline up to 1-year follow-up and significantly increased weight (5.8 ± 4.3 kg at 3-month, 8.1 ± 6.1 kg at 6-month, and 11.6 ± 7.0 kg at 1 year), BMI, and z-BMI. Leptin levels significantly increased from baseline to 3 and 6 months, as did TSH levels from baseline to 3 months, while FT4 levels decreased from baseline to 3 and 6 months. Patients with BMI >85th percentile at baseline (N = 16) significantly increased weight, BMI, and z-BMI, more than patients with normal BMI over time. Higher baseline levels of insulin, HOMA-IR, and leptin were associated with increased weight/BMI during follow-up, while higher baseline levels of FT4, adiponectin, and ghrelin were associated with lower weight/BMI during follow-up. All AP were associated with increased weight and BMI/z-BMI in all of the assessments; however, at 1-year assessment, this increase was significantly higher for patients on quetiapine. Both higher baseline levels of insulin, HOMA-IR, and leptin, as well as being overweight/obese at baseline were associated with increased weight/BMI during 1-year follow-up in children and adolescents on AP. Awareness of weight-related parameters in this population may help inform decisions regarding AP prescriptions.

Cardiometabolic risk markers of normal weight and excess body weight in Brazilian adolescents

Excess body weight leads to a variety of metabolic changes and increases the risk for cardiovascular diseases (CVD) in adulthood. The objective of this study was to investigate the presence of risk markers for CVD among Brazilian adolescents of normal weight and with excess body weight. The markers included blood pressure, C-reactive protein, homocysteine, tumor necrosis factor alpha, fibrinogen, fasting insulin and glucose, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, total cholesterol, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and triglycerides. We calculated odds ratios (OR) using logistic regression and adjusted for potential confounders such as age, sex, physical activity, and socioeconomic background. Compared with normal weight subjects, overweight/obese adolescents were more likely to have higher systolic blood pressure (OR = 3.49, p < 0.001), fasting insulin (OR = 8.03, p < 0.001), HOMA-IR (OR = 8.03, p < 0.001), leptin (OR = 5.55, p < 0.001), and LDL-c (OR = 5.50, p < 0.001) and lower serum HDL-c concentrations (OR = 2.76, p = 0.004). After adjustment for confounders, the estimates did not change substantially, except for leptin for which the risk associated with overweight increased to 11.09 (95% CI: 4.05-30.35). In conclusion, excess body weight in adolescents exhibits strong associations with several markers that are established as causes of CVD in adults. This observation stresses the importance of primary prevention and of maintaining a healthy body weight throughout adolescence to reduce the global burden of CVD.

Continuous Metabolic Syndrome Scores for Children Using Salivary Biomarkers

Background

Binary definitions of the metabolic syndrome based on the presence of a particular number of individual risk factors are limited, particularly in the pediatric population. To address this limitation, we aimed at constructing composite and continuous metabolic syndrome scores (cmetS) to represent an overall measure of metabolic syndrome (MetS) in a large cohort of metabolically at-risk children, focusing on the use of the usual clinical parameters (waist circumference (WC) and systolic blood pressure (SBP), supplemented with two salivary surrogate variables (glucose and high density lipoprotein cholesterol (HDLC). Two different approaches used to create the scores were evaluated in comparison.

Methods

Data from 8,112 Kuwaiti children (10.00 ± 0.67 years) were used to construct two cmetS for each subject. The first cmetS (cmetS-Z) was created by summing standardized residuals of each variable regressed on age and gender; and the second cmetS (cmetS-PCA) was defined as the first principal component from gender-specific principal component analysis based on the four variables.

Results

There was a graded relationship between both scores and the number of adverse risk factors. The areas under the curve using cmetS-Z and cmetS-PCA as predictors for severe metabolic syndrome (defined as the presence of ≥3 metabolic risk factors) were 0.935 and 0.912, respectively. cmetS-Z was positively associated with WC, SBP, and glucose, but inversely associated with HDLC. Except for the lack of association with glucose, cmetS-PCA was similar to cmetS-Z in boys, but had minimum loading on HDLC in girls. Analysis using quantile regression showed an inverse association of fitness level with cmetS-PCA (p = 0.001 for boys; p = 0.002 for girls), and comparison of cmetS-Z and cmetS-PCA suggested that WC and SBP were main contributory components. Significant alterations in the relationship between cmetS and salivary adipocytokines were demonstrated in overweight and obese children as compared to underweight and normal-weight children.

Conclusion

We have derived continuous summary scores for MetS from a large-scale pediatric study using two different approaches, incorporating salivary measures as surrogate for plasma measures. The derived scores were viable expressions of metabolic risk, and can be utilized to study the relationships of MetS with various aspects of the metabolic disease process.

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.

The role of leptin in diencephalic syndrome

Diencephalic syndrome is a rare condition associated with central nervous system tumors. The most common presentation is secondary failure to thrive with proper caloric intake and no statural impairment. Despite the importance of this syndrome, little is known of its pathophysiology. Some reports have documented changes in human growth hormone and insulin levels at the onset, whereas others have described endocrine disorders of hypothalamic insufficiency resulting from surgery of the tumor. It has been suggested that the hormonal changes described, such as increased human growth hormone and ghrelin or decreased insulin and leptin levels, are related to a patient's BMI. These findings support the role of these 4 hormones as indicators of the patient's nutritional status but not as mediators or potential therapeutic targets of the disease. We report the case of an infant who initially presented with tumor progression and, after chemotherapy, progressive weight gain and reduced tumor size. Because he presented no hormonal deficiencies or obesity after therapy, we were able to analyze his hormonal status uninfluenced by effects of metabolic treatment or excess weight. Although ghrelin and leptin levels have been related to nutritional status, our patient's leptin levels fell when tumor size decreased and weight increased: an extraordinary finding because leptin concentration is expected to increase with weight gain. This paradoxical response suggests that leptin may be dysregulated in diencephalic syndrome or that the diencephalic astrocytoma may have had an effect on leptin secretion.

Leptin concentration and nutritional status in the course of treatment in children with brain tumours--preliminary report

PURPOSE

To assess the nutritional status in children with central nervous system (CNS) tumours, including concentration of leptin, the neuropeptide responsible for regulation of energetic homeostasis in an organism.

METHOD

The studied group comprised 44 children with brain tumours, aged (4.02-18.7). In all children during the whole therapy (from the start to the period of 1 year and more after the end of therapy), a number of standard deviations (SDs) for the body mass index (SDS BMI) was derived from anthropometric measurements. Concentrations of leptin were assayed simultaneously.

RESULT

The lowest values of the anthropometric indices were found in children during the maintenance therapy. Concentrations of leptin in patients with malignant CNS tumours and significant undernutrition were slightly greater as compared to patients presenting normal nutritional status; however, without statistical significance.

CONCLUSION

In children with tumours of the central nervous system, there are quantitative disorders of the nutritional status which correlate with the period of the treatment. The most significant disorders in the nutritional status are observed during maintenance chemotherapy. There was no statistically significant correlation between the concentration of leptin and nutritional status in children with malignant brain tumours during the course of treatment and after its completion.

Association of leptin and insulin with childhood obesity and retinal vessel diameters

OBJECTIVE

Childhood obesity is associated with an impaired retinal microcirculation. The aim of the study was to investigate the association between specific obesity-related biomarkers, physical fitness and retinal vessel diameters in school children.

DESIGN AND SUBJECTS

We studied 381 children aged 10-11 years (body mass index (BMI): 19.3±3.7 kg m(-2)) in a school-based setting.

MEASUREMENTS

Anthropometric measurements and blood sampling were conducted using standard protocols for children. The serum biomarkers leptin, adiponectin, insulin as well as interleukin-6 (IL-6) were analyzed. Physical fitness was determined by a six-item-test battery and physical activity by use of a questionnaire. Central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and the arteriolar-to-venular diameter ratio (AVR) were assessed with a non-mydriatic vessel analyzer (SVA-T) using a computer-based program.

RESULTS

Compared with normal weight children (n=254), obese children (n=39) showed higher leptin (P<0.001), higher insulin (P<0.001), higher IL-6 (P<0.001) and lower adiponectin levels (P=0.013). Obese children demonstrated wider CRVE (P=0.041) and lower AVR (P<0.001). Higher leptin levels were associated with wider CRVE (P=0.032) and lower AVR (P=0.010), that was BMI dependent. Insulin levels were associated with arteriolar (P=0.045) and venular dilatation (P=0.034) after adjustment for BMI. No significant associations between adiponectin levels, IL-6 levels, physical fitness or physical activity and retinal vessel diameter were observed. Lower leptin levels were independently correlated with higher physical fitness (r=-0.33; P<0.001).

CONCLUSION

Leptin and insulin levels are associated with changes of the retinal microcirculation. Especially insulin seems to be a good target marker for the cardiometabolic risk assessment in children since elevated insulin levels are independently associated with microvascular end-organ alterations at an early stage. Lifestyle intervention studies are warranted to examine whether improvement of physical fitness or weight reduction can affect cardiometabolic risk markers and reverse alterations of the retinal microcirculation.

Is obesity a risk factor for chronic kidney disease in children?

There is a rapid increase worldwide in the prevalence of obesity in adults and children. Obesity is not only a comorbidity for chronic kidney disease (CKD) but may also be a risk factor for CKD. Epidemiological correlations and pathophysiological changes have been observed associating obesity with CKD. Low birth weight may be associated with both obesity and low nephron mass, leading to CKD later in life. Elevated levels of adipokines, such as leptin and adiponectin, in obesity may be factors in CKD pathogenesis and progression. Furthermore, various other factors, such as hypertension, increased cardiovascular morbidity, insulin resistance, dyslipidemia, and lipotoxicity, may play significant roles in the pathogenesis of CKD in obesity. Reduction in obesity, which is a potentially modifiable risk factor, might help decrease the burden of CKD in the population. Apart from individualized options, community-based interventions have the potential to create a strong impact in this condition.

Leptin, adiponectin, and short-term and long-term weight loss after a lifestyle intervention in obese children

OBJECTIVE

In overweight children, high leptin levels are independently associated with higher risk for cardiovascular disease, whereas adiponectin seems to be protective against type 2 diabetes and atherosclerosis. The study examines the predictive value of leptin for weight loss after a 4- to 6-wk inpatient therapy and again after 1 y; as well as the association among weight loss, leptin, and adiponectin levels and changes in cardiometabolic risk factors after therapy.

METHODS

Body mass index (BMI), blood pressure, Tanner stage, and cardiometabolic risk factors were studied in 402 children (59.2% females, 13.9 ± 2.3 y, BMI 33.8 ± 5.7 kg/m(2)) before and after a 4-to 6-wk inpatient intervention (exercise, diet, and behavioral therapy) and BMI 1 y later (n = 206).

RESULTS

BMI was reduced from 33.8 ± 5.7 to 30.5 ± 5.1 kg/m(2) (P < 0.001) during the lifestyle intervention and remained unchanged after 1 y. Baseline BMI was positively associated with leptin (r = 0.60; P < 0.001) and cardiometabolic risk factors (blood pressure, high-density lipoprotein [HDL] cholesterol, triglycerides). Baseline leptin was associated with BMI and triglycerides (r = 0.39; P < 0.001), baseline adiponectin with HDL-cholesterol (r = 0.40; P < 0.001). Baseline BMI explained 40.7% of the variance in weight loss during therapy. The combination of BMI, sex, and leptin explained 50.4% of the variance. Neither BMI nor leptin predicted weight changes over the long term.

CONCLUSIONS

Overweight children maintained a substantial amount of weight loss after participation in a short-term inpatient lifestyle intervention. Baseline BMI was positively associated with weight reduction during the intervention, whereas baseline leptin had only a minor predictive value.

CRP is related to higher leptin levels in minority peripubertal females regardless of adiposity levels

Overweight is related to higher levels of C-reactive protein (CRP) and leptin, which have been independently associated with increased risk for diabetes, cardiovascular disease, and the metabolic syndrome. Elevated CRP may trigger leptin resistance by inhibiting the binding of leptin to its receptors. We cross-sectionally examined the relationship between CRP, leptin, BMI z-score, percent body fat (%BF) assessed by air plethysmography (BodPod), and insulin sensitivity (SI) and acute insulin response (AIRg) measured by intravenous glucose tolerance test in 51 Latina and African-American females (77% Latina), mean age 9.2 (±0.9) years, at either Tanner Pubertal Stage (TPS) 1 (n = 25) or TPS 2 (n = 26). Females at TPS 2 had higher BMI z-scores, %BF (23% ± 10.1 vs. 30% ± 10.0, P = 0.02), AIRg (976.7 ± 735.2 vs. 1555.3 ± 1,223 µIU/ml, P = 0.05), fasting insulin (11.0 ± 10.8 vs. 17.2 ± 13.6 µlU/ml, P = 0.00) and leptin levels (11.0 ± 7.1 vs. 19.6 ± 10.9 ng/ml, P < 0.001) than those at TPS 1. There were no ethnic differences in any of the measured variables. CRP was positively correlated with BMI z-score (P = 0.001), %BF (P = 0.006), fasting insulin and AIRg (P = 0.02), and fasting leptin (P = 0.00), and negatively correlated with SI (P = 0.05). A linear regression model showed that CRP independently explained 10% (P = 0.00) of the variance in leptin after adjusting %BF, TPS, ethnicity, habitual physical activity and SI. Hence, low-grade inflammation may contribute to prolonged leptin exposure and leptin resistance, even in healthy children.

The role of metabolic syndrome components and adipokines in insulin resistance in prepubertal children

OBJECTIVE

Insulin resistance has a central role in the pathophysiology of cardiovascular atherosclerotic disease. Adipose tissue is of capital importance in view of its production of adipokines. The present study aims to determine the association of metabolic syndrome components, which constitute risk factors for cardiovascular atherosclerotic disease, and leptin and adiponectin with insulin resistance in prepubertal children.

METHODS

We conducted a cross-sectional study involving 197 children. Of these, 112 children were obese, 36 were overweight and 49 had normal weight. The association of sex, waist circumference, Acanthosis nigricans, age, BMI Z-score, serum lipids, leptin and adipocytokines with insulin resistance [defined as the homeostatic model assessment for insulin resistance (HOMA-IR) index higher than or equal to 2.5] was investigated using logistic regression.

RESULTS

There was positive association of sex (female), age, BMI Z-score, triglycerides and leptin with insulin resistance (p<0.05).

CONCLUSION

Among the conventional components of metabolic syndrome, the role of BMI Z-score and triglycerides stands out in insulin resistance of prepubertal children. Sex (female), age and leptin also showed to be of major importance.

Association of plasma leptin concentrations with adiposity measurements in rural Chinese adolescents

CONTEXT

There is evidence that leptin is involved in the etiology of obesity-related cardiovascular disease in adults. This raises the question of whether leptin levels in adolescence are indicative of adiposity-related cardiovascular risk.

OBJECTIVE

This study investigated gender-specific patterns of plasma leptin during adolescence, assessed which adiposity measurements are most strongly associated with plasma leptin, and estimated to what degree leptin-adiposity associations are influenced by genetic factors.

METHODS

Plasma leptin concentrations were determined using a sandwich immunoassay. Associations between plasma leptin and several adiposity measurements were examined using generalized estimating equations. Genetic contribution to leptin-adiposity association was estimated by Cholesky decomposition models using twin design.

RESULTS

Plasma leptin levels were higher in females than males at all Tanner stages. In females, body mass index, waist circumference, fat mass index (FMI), and percentage body fat (%BF) had similar associations with leptin levels. In males, %BF and FMI were more strongly associated with leptin levels than body mass index and waist circumference. In both males and females, percentage trunk fat had the weakest association with leptin among the five adiposity measures. Shared genetic factors account for more than 80% of the phenotypic correlation between %BF and leptin.

CONCLUSIONS

We found gender differences in leptin levels and leptin-adiposity associations. In both genders, leptin levels were strongly associated with %BF and FMI, particularly in males. Shared genetic factors contributed largely to the phenotypic correlation between leptin and %BF. Our findings underscored the importance of further investigation of leptin as a biomarker of adiposity in adolescents.

Identification and treatment of metabolic complications in pediatric obesity

Metabolic consequences of obesity including insulin resistance, type 2 diabetes mellitus, hyperlipidemia, hypertension, polycystic ovarian syndrome, and non-alcoholic fatty liver infiltration are rapidly emerging in the pediatric population. Identifying effective strategies for identifying and treating these obesity related comorbidities in children are crucial to the prevention of future cardiovascular disease and poor health outcomes.This review discusses the pathophysiologic connections between obesity, metabolic disease and cardiovascular risk. Current evidence and recommendations for screening and treatment for the metabolic consequences of pediatric obesity are reviewed.

Relações entre leptina, puberdade e exercício no sexo feminino

O processo de puberdade feminina envolve vários fenômenos anatômico-fisiológicos, sendo o acontecimento da menarca o indicador da maturidade sexual feminina. A idade média de menarca gira em torno de 12 anos. Para meninas atletas, a menarca pode ocorrer mais tarde, e dependendo do estresse causado pelo exercício, pode resultar em um quadro de amenorreia hipotalâmica. O hormônio leptina, além de apresentar relação com a obesidade, também tem relação com o sistema reprodutor. Os estudos mais recentes em humanos demonstram existir relações importantes entre as concentrações de leptina plasmática e o processo de puberdade feminino. Este estudo teve por objetivo verificar a influência da leptina no processo pubertário feminino relacionado com exercício, do ponto de vista fisiológico, por meio de uma pesquisa de revisão bibliográfica. Os resultados das pesquisas apresentadas demonstram que o aumento de leptina sanguínea foi relatado como tendo correlação inversamente proporcional à idade de menarca. Além disso, verificou-se que a leptina tem correlação inversa com o exercício físico; as baixas concentrações de leptina plasmática estão diretamente ligadas à desregulação do sistema reprodutor em mulheres atletas. Conclui-se que a leptina relaciona-se com o sistema reprodutor feminino, fato que fica evidente durante o processo de puberdade. Já em meninas e mulheres atletas, as concentrações de leptina encontradas foram inferiores às daquelas não-atletas, demonstrando a relação tecido adiposo/leptina/sistema reprodutor/exercício.

Altered plasma adipokines and markers of oxidative stress suggest increased risk of cardiovascular disease in First Nation youth with obesity or type 2 diabetes mellitus

OBJECTIVE

To evaluate cardiovascular disease risk in First Nation youth with and without type 2 diabetes mellitus (T2DM) or obesity by comparing pro- and anti-inflammatory adipokines, markers of oxidative stress and the plasma phospholipid fatty acid profile.

METHOD

Self-declared First Nation youth (12-15 yr) with T2DM (n = 24) as well as age-, gender-, and body mass index-matched controls (obese group; n = 19) and unmatched controls (control group; n = 34) were recruited from a pediatric diabetes clinic.

RESULTS

Plasma tumor necrosis factor-alpha, ultrasensitive C-reactive protein, resistin, and total antioxidant status were not different among the three groups. Plasma total leptin, soluble leptin receptor, and free leptin were significantly higher in the T2DM group than the control group (p < 0.001, p = 0.019, p < 0.001, respectively) but did not differ from the obese group. Similarly, oxidized low-density lipoprotein was higher in the T2DM group compared with controls (p = 0.002) but not in the obese group. However, interleukin-6 was significantly higher (p < 0.001) in the T2DM group compared with both the control and the obese groups, suggesting that T2DM, but not an increase in adiposity, was responsible for this elevation. Adiponectin was significantly lower in the T2DM group compared with the control group only (p = 0.035).

CONCLUSIONS

Changes in plasma adipokines and oxidative stress can already be detected in youth with T2DM; however, many of the changes are mirrored in obese youth, suggesting that both these populations are at an increased risk for future cardiovascular complications.

Assessment of adiponectin and leptin as biomarkers of positive metabolic outcomes after lifestyle intervention in overweight and obese children

BACKGROUND

A number of metabolic changes are caused by childhood obesity, including insulin resistance, diabetes, and dyslipidemia. To counteract them, lifestyle modification with changes in dietary habits and physical activity is the primary intervention. Anthropometric parameters may not identify all positive changes associated with lifestyle modifications, whereas circulating adipokines may represent an alternative as biomarkers. The aim of this study was to evaluate adiponectin and leptin levels as markers of positive metabolic outcomes in childhood obesity.

METHODS

Changes in clinical, anthropometric, and metabolic parameters, including adiponectin and leptin, were assessed in 104 overweight and obese children before and after 1 yr of lifestyle intervention. Obesity and overweight were defined according to the Italian body mass index reference tables for age and sex. Fifty-four normal-weight children were evaluated as controls. Forty-eight of the children (47.5%) returned for follow-up at 1 yr.

RESULTS

Compared with normal-weight children, overweight and obese subjects differed significantly at baseline for glycemia, insulinemia, homeostasis model assessment for insulin resistance, adiponectinemia (5.8 vs. 18.2 microg/ml in controls), low-density lipoprotein-cholesterol, and triglycerides. These parameters were all higher in the overweight/obese children. At follow-up, most parameters improved in overweight/obese children. The most significant changes were observed in adiponectin concentration, which increased by 245% (P < 0.0001), reaching the levels observed in normal-weight children. Leptin levels showed changes unrelated to positive metabolic outcomes, remaining high at 1 yr of follow-up in overweight/obese children. Regardless of changes in weight status, children with lifestyle intervention reported changes in homeostasis model assessment for insulin resistance and in adiponectin that were associated with loss of fat mass.

CONCLUSIONS

After lifestyle intervention, adiponectin increased regardless of changes in weight, whereas no consistent changes was observed in serum leptin. Therefore, circulating adiponectin may represent a good biomarker to evaluate the efficacy of lifestyle intervention in overweight/obese children.