Retinol-binding protein 4 in neonates born small for gestational age

Abstract

ABSTRACT. Background: Retinol-binding protein 4 (RBP4) is an adipocyte-derived 'signal' that may contribute to the pathogenesis of insulin resistance and Type 2 diabetes. The relationship of RBP4 with insulin resistance and metabolic risk in human beings has been the subject of several studies. Subjects born small for gestational age (SGA) are at risk of insulin resistance and Type 2 diabetes. Though RBP4 could represent an early marker of insulin resistance, to date, none have determined RBP4 in SGA children. Aim: Our aim was to measure RBP4 concentrations in cord blood of SGA newborns compared with those in children born with a birth weight appropriate for gestational age (AGA) and to determine whether serum RBP4 levels at birth correlate with insulin sensitivity markers. Subjects and methods: Sixty-four newborns, 17 born SGA (mean gestational age: 36.4±2.1 weeks), and 47 born AGA (mean gestational age: 37.0±3.6 weeks) were studied. The main outcome measures included anthropometry, lipid profile, insulin, homeostasis model assessment, quantitative insulin-sensitivity check index, adiponectin, and RBP4. Results: RBP4 concentrations were significantly reduced in SGA newborns (p<0.002). No relationship was found between RBP4 and insulin sensitivity parameters. Stepwise regression analysis revealed that birth weight was the major predictor of RBP4 serum concentrations (p<0.001). Conclusion: RBP4 is reduced in SGA newborns, birth weight representing the major determinant of RBP4 concentrations, and is not related to insulin sensitivity. No significant difference in adiponectin levels and insulin sensitivity markers was found between SGA and AGA neonates. INTRODUCTIONRetinol-binding protein 4 (RBP4) is an adipocyte-derived 'signal' that may contribute to the pathogenesis of insulin resistance (IR) and Type 2 diabetes. RBP4 could play a role in obesity-induced IR, since chronic elevation of RBP4 in mice increases hepatic glucose production, down-regulates insulin signaling in muscle, and causes systemic IR (1). Furthermore, lowering elevated serum RBP4 levels in obese mice with a synthetic retinoid improves insulin sensitivity and normalizes glucose tolerance (1). In humans, the link between RBP4 and IR is less clear. In adulthood, serum RBP4 levels have been shown to correlate with the magnitude of IR in subjects with obesity, impaired glucose tolerance, and Type 2 diabetes (2). Moreover, elevated serum RBP4 was associated with components of the metabolic syndrome, including increased body mass index, waist-tohip ratio, serum triglyceride levels, and systolic blood pressure and decreased HDL cholesterol levels (2). In childhood, a relationship between serum RBP4 and obesity and components of the metabolic syndrome has been described in pre-pubertal and early pubertal children (3).Increased risk of developing IR and Type 2 diabetes in adulthood is associated with low birth weight (4). Although this association is clearly established in adults (5), results in children are still conflicting (6). Some authors have sugg...

RBP4: a controversial adipokine

“…Birth weight, and not parameters of insulin sensitivity, is the major parameter determining circulating RBP4 levels in this population (70).…”

Investigation of urine proteome of preterm newborns with respiratory pathologies

“…The role of some core proteins in the kidney and urinary tract function of adults and children was previously discussed [33][34][35][36][37][38]. EGF participates in renal development, a postnatal rise in renal EGF content and urinary EGF excretion suggests a role of EGF in renal maturation [38].…”

“…Cystatin C is mainly used as a biomarker of kidney function and glomerular filtration rate (GFR) [34][35][36] and its level was shown to be higher in preterm as compared to term neonates [33]. Retinol-binding protein is a low molecular weight protein of 21 kDa that transports retinol from the liver to peripheral tissues.…”

Clinical immunology Retinol-binding protein 4 levels are related to maternal triglyceride levels

“…Previous studies comparing RBP4 levels with birth weight reported conflicting results [10][11][12]. We hypothesized that abnormalities in maternal RBP4 levels and the associated proinflammatory state, controlled by IL-8 and IL-17 levels, might affect birth weight.…”

“…Previously, high levels of cord blood RBP4 were suggested to be associated with the delivery of LGA/SGA neonates [10] but another study opposed these findings [12]. Giacomozzi et al suggested an association between SGA infants and cord blood RBP4 levels [11], RBP4 levels were suggested to decrease in SGA infants independent of insulin resistance markers [11]. We did not control the fetal markers of insulin resistance in cord blood, but the maternal markers of insulin resistance were not correlated with RBP4 levels.…”