Peroxisome proliferator-activated receptor gamma expression in peripheral blood mononuclear cells and angiopoietin-like protein 4 levels in obese children and adolescents

Abstract

Purpose

The peroxisome proliferator-activated receptor γ (PPARγ) is highly expressed in adipose tissue and functions as transcriptional regulator of metabolism and adipocyte differentiation. Angiopoietin-like protein 4 (ANGPTL4), a central player in various aspects of energy homoeostasis, is induced by PPARγ. The aim of this study was to evaluate ANGPTL4 plasma levels and PPARγ gene expression in peripheral blood mononuclear cells (PBMCs) of children and adolescents with obesity and their association with metabolic parameters.

Methods

Seventy children and adolescents (35 obese and 35 age- and gender-matched control subjects), were selected. PBMCs were separated and their total RNA was extracted. After cDNA synthesis, PPARG gene expression was analyzed by real-time PCR. Relative differences in gene expression were calculated by ΔCt method using β-actin as a normalizer. Serum ANGPTL4 and insulin were measured using ELISA, and insulin resistance (IR) was calculated by the homeostatic model assessment of insulin resistance (HOMA-IR). Fasting plasma glucose (FPG), triglyceride, total cholesterol, LDL-C and HDL-C were also measured.

Results

The expression of the PPARG gene as well as the plasma ANGPTL4 levels were significantly diminished in obese subjects as compared to control ones. However, they were not significantly different in obese children with IR compared to obese children without IR or in those with or without metabolic syndrome. A significant positive correlation was found between PPARγ and ANGPTL4 (r = 0.364, p = 0.002). PPARγ expression levels were also significantly correlated with FPG (r = −0.35, p = 0.003).

Conclusion

PPARγ is decreased in childhood obesity and may be responsible for diminished ANGPTL4 levels.

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