Abstract & Introduction

Obesity increases the risk for insulin resistance and metabolic syndrome in both adults and children.

FABP4 is a member of the intracellular lipid-binding protein family that is predominantly expressed in adipose tissue, and plays an important role in maintaining glucose and lipid homeostasis.

The purpose of this study was to measure FABP4 plasma levels, assess FABP4 allelic variants, and explore potential associations with fasting glucose and insulin levels in young school-age children with and without obesity.

Methods

A total of 309 consecutive children ages 5-7 years were recruited. Children were divided based on BMI z score into Obese (OB; BMI z score >1.65) and non-obese (NOB).

Fasting plasma glucose, lipids, insulin, hsCRP, and FABP4 levels were measured. HOMA was used as correlate of insulin sensitivity.

Four SNPs of the human FABP4 gene (rs1051231, rs2303519, rs16909233 and rs1054135), corresponding to several critical regions of the encoding FABP4 gene sequence were genotyped.

Results

Compared to NOB, circulating FABP4 levels were increased in OB, as were LDL, hsCRP and HOMA. FABP4 levels correlated with BMI, and also contributed to the variance of HOMA and hsCRP, but not serum lipids.

The frequency of rs1054135 allelic variant was increased in OB, and was associated with increased FABP4 levels, while the presence of rs16909233 variant allele, although similar in OB and NOB, was associated with increased HOMA values.

Conclusions

Childhood obesity is associated with higher FABP4 levels that may promote cardiometabolic risk. The presence of selective SNPs in the FABP4 gene may account for increased risk for insulin resistance or systemic inflammation in the context of obesity.  

Introduction

Childhood obesity is a serious public health problem that has reached epidemic proportions all over the world [1-3].

Metabolic and cardiovascular complications of obesity in childhood, while less common than in adulthood, may nevertheless include hyperlipidemia, insulin resistance and type 2 diabetes, and systemic low grade inflammation.

In children, the presence of obesity has been associated with increased levels of high sensitivity CRP (hsCRP) [4], as well as other inflammatory mediators [5-9], all of which promote the development of endothelial and metabolic dysfunction [10-14].

However, substantial variability is found among obese children as to the presence of metabolic dysfunction or increased inflammatory markers, suggesting that individual genomic variance may account for such discrepancies.

Fatty acid binding proteins (FABP) are a group of related molecules that serve as intracellular chaperones for lipid moieties, coordinate cellular lipid responses, and thereby play a critical role in metabolic and inflammatory pathways [15,16].

Adipocyte FABP, also known as FABP4, A-FABP, or aP2, was initially detected in mature adipocytes, and plays critical roles in hyperlipidemia, atherogenesis and type 2 diabetes, particularly when obesity is concurrently present [17,18]).

FABP4 is produced and released to the circulation, and FABP4 levels appear to correlate with the degree of metabolic dysfunction [19,20].

Similar to adults, children who are obese are more likely to display elevations in FABP4 plasma levels, which will be reduced by interventions leading to weight loss [21,22].

We hypothesized that the presence of obesity in community based children will be associated with increased FABP4 levels which may account for individual discrepancies in the presence or absence of insulin resistance or high sensitivity C-reactive protein (hsCRP) plasma levels, and that single nucleotide polymorphisms in the FABP4 gene may underlie the variance in such relationships  

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Lipids Health Dis. 2010; 9: 18. doi: 10.1186/1476-511X-9-18.

Abdelnaby Khalyfa,¹ Bharat Bhushan,¹ Mohamed Hegazi,¹ Jinkwan Kim,¹ Leila Kheirandish-Gozal,¹ Rakesh Bhattacharjee,² Oscar Sans Capdevila,³ and David Gozal¹

¹Department of Pediatrics, Comer Children's Hospital, The University of Chicago, Chicago, IL, USA ²Division of Sleep and Respiratory Medicine, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada ³Pediatric Sleep Unit, Division of Neurophysiology, Department of Neurology, Hospital Sant Joan de Déu, Barcelona, Spain

Corresponding author.

Abdelnaby Khalyfa: akhalyfa@peds.bsd.uchicago.edu ;

Bharat Bhushan: bbhushan@peds.bsd.uchicago.edu ;

Mohamed Hegazi: dr_no3man@hotmail.com ;

Jinkwan Kim: jkkim@peds.bsd.uchicago.edu ;

Leila Kheirandish-Gozal: lgozal@peds.bsd.uchicago.edu ;

Rakesh Bhattacharjee: rakesh.bhattacharjee@sickkids.ca ; Oscar Sans Capdevila: osans@hsjdbcn.org ;

David Gozal: dgozal@peds.bsd.uchicago.edu

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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