Teresa Gavela-Pérez

Circulating kisspeptin levels exhibit sexual dimorphism in adults, are increased in obese prepubertal girls and do not suffer modifications in girls with idiopathic central precocious puberty.

The system KISS1-KISS1R is one of the main regulators of the hypothalamic-pituitary-gonadal axis and constitutes a link between metabolism and reproduction through its interaction with leptin. The aim of this study was to clarify the possible utility of kisspeptin as a pubertal marker and/or the possible influence of nutritional status in kisspeptin levels. To this end, we have studied kisspeptin plasma levels throughout sexual development and in prepubertal obese girls and girls affected by idiopathic central precocious puberty (CPP). Plasma kisspeptin concentrations were analyzed by RIA. An increase in kisspeptin levels was observed in adult females compared to healthy prepubertal and pubertal girls (p<0.001) and to adult males (p<0.001). Additionally, kisspeptin was increased in prepubertal obese girls compared to healthy prepubertal girls (p<0.01) and girls with idiopathic CPP (p<0.05). As revealed by the regression analysis, in prepubertal healthy and obese girls and girls with idiopathic CCP, the parameters that influenced kisspeptin levels were BMI (R(2)=0.10, p<0.05) and leptin levels (R(2)=0.14, p<0.01). In conclusion, kisspeptin levels do not seem to be a good pubertal marker. The results obtained in prepubertal and idiopathic CCP girls point to a relationship between leptin, BMI and kisspeptin at least in this group, and suggest a possible role for adipose tissue in the modulation kisspeptin synthesis.

Resistin levels are related to fat mass, but not to body mass index in children.

The relationship of resistin levels with obesity remains unclear. The aim of this study was to determine resistin levels in prepubertal children and adolescents and evaluate their association with anthropometric parameters and body composition. The study population included 420 randomly selected 6-8-year-old children and 712 children aged 12-16 years. Anthropometric data were measured and body mass index (BMI) and waist-to-hip and waist-to-height ratios were calculated. Body composition was assessed using an impedance body composition analyzer. Serum resistin levels were determined using a multiplexed bead immunoassay. Resistin levels were not significantly different between sexes. No significant differences in serum resistin concentrations were found between obese, overweight, and normal weight children at any age, and no significant correlations were observed between resistin concentrations and weight or BMI. However, resistin levels showed a significant positive correlation with fat mass in 12-16-year-old children, particularly in girls. In addition to describing serum resistin levels in prepubertal children and adolescents, our study suggests that resistin is related to body fat rather than to BMI in adolescents.

The influence of puberty on vitamin D status in obese children and the possible relation between vitamin D deficiency and insulin resistance

Abstract Background: Puberty can affect vitamin D levels. Objectives: The goal of this study was to analyze the relation between vitamin D deficiency and puberty in obese Spanish children, along with the possible interrelation between vitamin D status and degree of insulin resistance. Methods: A cross-sectional study was carried out, in which clinical and biochemical data were gathered from 120 obese and 50 normal weight children between January 2011 and January 2013. Results: Mean vitamin D levels were 19.5 and 31.6 ng/mL in obese pubertal and obese prepubertal children, respectively. About 75% of the obese pubertal subjects and 46% of the obese prepubertal subjects had vitamin D deficiency. Vitamin D levels were significantly lower in pubescent subjects compared with pre-pubescent subjects in summer, fall, and winter. There was no apparent relation between vitamin D levels and homeostasis model assessment index for insulin resistence (expressed in standard deviation score for sex and Tanner stage) in either puberty or pre-puberty. Conclusion: Puberty may be a risk factor for the vitamin D deficiency commonly found in the obese child population. This deficiency is not associated with higher insulin resistance in obese pubertal children compared with obese prepubertal children.

Earlier menarcheal age in Spanish girls is related with an increase in body mass index between pre-pubertal school age and adolescence.

Higher body mass index (BMI) has been associated with earlier pubertal development.

Plasma kisspeptin levels are elevated in cord blood and present sexual dimorphism in the adult population: Relation with leptin, gonadotropins and anthropometrical data

Kisspeptin, the product of the hypothalamic KISS1 gene, is a main regulator of the hypothalamic-pituitary-gonadal axis and could be a link between metabolism and reproduction through its interaction with leptin. Kisspeptin could be involved in gonadotropin regulation and responsive to leptin levels from the first stages of life, exhibiting, as does leptin, sexual dimorphism. To test our hypothesis, we have analyzed plasma kisspeptin levels and their possible relationship with gonadotropins and leptin in a cohort composed of newborns (n = 86) and adults (n = 55). Plasma kisspeptin, gonadotropin and leptin levels were measured by RIA and multiplexed bead immunoassays, respectively. We have built a multivariate linear regression model (analyzing kisspeptin and LH separately as dependent variables) by stepwise analysis, incorporating the variables that had shown significant correlation in the univariate analysis. Cord blood samples exhibited high kisspeptin levels 127.01(113-141.02 pmol/l), but these were not sexually dimorphic. The adult population exhibited sexual dimorphism (3.72(2.95-4.49) vs. 1.77(1.23-2.31)pmol/l women vs. men, p<0.05). Leptin levels showed sexual dimorphism in cord blood samples and also in the adult population. Furthermore, there was a significant interaction between LH and kisspeptin levels and kisspeptin was negatively correlated with age. The high kisspeptin levels observed in cord blood, with no sexual dimorphism, suggest a placental source. The sexual dimorphism exhibited in adulthood supports the notion that there are different sources and/or differential kisspeptin regulation between men and women.

Vegetable and Fruit Intakes Are Associated with hs-CRP Levels in Pre-Pubertal Girls

The influence of diet on inflammation in children remains unclear. We aimed to analyze the influence of diet on high-sensitivity C-reactive protein (hs-CRP) levels in a pre-pubertal population free of other influences that may affect hs-CRP levels. We determined hs-CRP levels in 571 six- to eight-year-old children using an hs-CRP ELISA kit. Information on food and nutrient intake was obtained through a food-frequency questionnaire. Overall dietary quality was assessed using the Healthy Eating Index (HEI). We found that girls in the highest tertile of hs-CRP levels had a higher intake of saturated fatty acid, and lower intakes of fiber and vitamin E and a lower HEI score when compared to those in tertiles 1 and 2. We also observed a significant decrease in fruit and vegetable intakes by hs-CRP tertile. Factor analysis showed that a dietary pattern that was loaded most strongly with vegetable, fruit, fiber and vitamin A and E intakes correlated negatively (−0.132, p < 0.05) with hs-CRP. No such association was found in boys. In conclusion, our data show that girls with a poorer quality diet show higher hs-CRP levels already at a pre-pubertal age.

High-Sensitivity C-Reactive Protein and Leptin Levels Related to Body Mass Index Changes Throughout Childhood

OBJECTIVES To analyze the association between high-sensitivity C-reactive protein (hs-CRP) levels and cardiovascular risk factors in healthy school children, and to evaluate whether changes in body mass index (BMI) category throughout childhood affect hs-CRP levels. STUDY DESIGN We measured serum hs-CRP levels, lipid profile, insulin levels, and leptin levels in 683 prepubertal children and 748 adolescents. A total of 272 children participated in the study in both cohorts, prepubertal (baseline; age 6-8 years) and adolescents (follow-up; age 12-16 years). RESULTS Compared with their normal weight (NW) counterparts, hs-CRP levels were significantly higher in obese and overweight (OW) adolescents and obese prepubertal children. The highest hs-CRP levels were seen in children who were OW at baseline and at follow-up, and the lowest levels in those who transitioned from OW at baseline to NW at follow-up. High-density lipoprotein cholesterol and apolipoprotein A-I levels decreased across the hs-CRP tertile in both prepubertal children and adolescents, with significant differences (P < .001) in concentrations between the highest and lowest tertiles in 6- to 8-year-old boys and girls and in 12- to 16-year-old boys. The hs-CRP levels were also significantly associated with leptin levels in both prepubertal children and adolescents, with a significant increase across hs-CRP tertiles (P < .001). CONCLUSIONS The shift from OW to NW throughout childhood is associated with a decrease in hs-CRP level to below that observed in children who maintain NW throughout childhood. Leptin levels were strongly associated with hs-CRP levels in our population independent of BMI. Our findings suggest that an obesity-related chronic inflammatory state may be reversible by improving weight status.

Sex-related differences in the association of ghrelin levels with obesity in adolescents.

Abstract Background: The utility of ghrelin as a biomarker may be different depending on gender. The aim of this study was to assess ghrelin levels in a population-based sample of adolescents, and to evaluate their association with obesity and obesity-related parameters depending on sex. Methods: The studied population included 601 randomly selected 14-to 16-year-old children. Anthropometrical data were measured and body mass index (BMI) and waist to hip ratio calculated. Body composition was assessed using an impedance body composition analyzer. Total serum ghrelin levels were determined using a multiplexed bead immunoassay. Serum leptin and adiponectin levels were determined by ELISA and insulin by RIA. Results: Ghrelin levels were significantly higher in girls than in boys. Serum ghrelin concentrations were significantly lower (p<0.01) in obese than in normal weight (NW) girls, but showed no differences by weight category in boys. Ghrelin showed a significant negative relationship with waist circumference (WC), waist to hip ratio and fat mass (p<0.05) in both genders, and with weight and BMI (p<0.01) in girls, and insulin (p<0.01) and HOMA (p<0.05) in boys. Ghrelin also correlated negatively with leptin levels in girls (p<0.01). Conclusions: Our study describes serum ghrelin levels in adolescents, showing a sexual dimorphism in ghrelin levels in these 14-to 16-year-old children, and a different association of ghrelin levels with obesity by gender that suggests a different appetite and energy expenditure control depending on sex at this age.

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.

C-reactive protein expression in adipose tissue of children with acute appendicitis

ObjectiveThe aim of this study is to gain insights into the role of visceral adipose tissue as a source of C-reactive protein (CRP) in acute inflammation and to explore the potential relationship of CRP expression with the severity of appendicitis.MethodsA total of 20 pediatric patients undergoing appendectomy were included in the study. Patients were divided into two groups according to appendicitis severity (uncomplicated and complicated). CRP levels were measured in visceral fat samples by western blotting, as well as in serum by biochemical testing.ResultsCRP was found to be expressed in visceral adipose tissue. The adipose tissue of patients with complicated appendicitis showed significantly higher CRP levels (p = 0.002) compared to patients with uncomplicated appendicitis. These results mirrored the CRP values obtained in serum (p = 0.018).ConclusionIn childhood, visceral adipose tissue is a source of CRP in acute inflammation, and its expression is potentially associated with the severity of local inflammation.