Circulating Irisin Levels in Preadolescents and Adolescents Born Preterm

Abstract

Introduction. Prematurity is associated with increased cardiometabolic risk later in life. The adipomyokine irisin has been acknowledged as a modulator of energy metabolism and insulin sensitivity. The aim of this study was to investigate circulating levels of irisin and their relation to anthropometric measurements and cardiometabolic phenotype in a population of preterm-born children vs. full-term-born peers. Methods. A total of 160 children (87 born preterm aged 8.1-14.8 years and 73 born full-term of similar age and gender distribution) were studied. Arterial blood pressure, anthropometry, body composition assessments with dual energy X-ray absorptiometry (DXA) and skin fold measurements were performed. Blood biochemistry and circulating levels of irisin, insulin, cortisol, leptin, and adiponectin were also determined. Results. The preterm group had higher diastolic blood pressure, triceps skin fold, subscapular skin fold (SSF) and abdominal skin fold measurements and more central adiposity than the full-term group. Irisin was significantly lower (p=0.002), whereas leptin was higher (p=0.03), in the preterm than the full-term group. Irisin correlated positively with gestational age (r=0.19, p=0.01), birthweight (r=0.23, p=0.003) and high-density lipoprotein cholesterol (r=0.20, p=0.01), and negatively with SSSF (r=-0.25 p=0.003) and chronological age (r=-0.21, p=0.008). Conclusion. Lower levels of irisin and a slightly unhealthy adiposity and cardiometabolic pattern were detected in preterm-born children in comparison to their full-term-born peers. Whether low irisin levels in preadolescents and adolescents born prematurely could be of prognostic value for the development of cardiometabolic sequelae later in life remains to be further studied.

Association of Plasma Irisin Levels with Circulating Endothelial Microparticles (EMPs) and Endothelial Progenitor Cells (EPCs) in Children Born Prematurely

“…The decreased irisin levels in our preterm-born population are consistent with the results of previous studies in preterm and SGA neonates, as well as in children born prematurely [ 33 , 34 , 35 ]. The suppression of irisin production in preterm and SGA neonates and children might be due to their reduced muscular mass and brown adipose tissue [ 34 , 35 , 50 ].…”

“…The suppression of irisin production in preterm and SGA neonates and children might be due to their reduced muscular mass and brown adipose tissue [ 34 , 35 , 50 ]. Moreover, adipose tissue partitioning alterations and, specifically, the prematurity-related predisposition to a more central fat deposition pattern may be responsible for the decreased irisin levels in the preterm-born individuals compared to full-term peers [ 33 , 51 ] since visceral adipose tissue has a minor contribution to the production and signaling of FNDC5/irisin in comparison with subcutaneous adipocytes [ 51 ].…”

“…A statistical power analysis was performed for sample size estimation based on data from previous studies that investigated potential differences in circulating irisin levels between preterm-born and full-term-born individuals [ 33 , 34 ], as well as previous studies that investigated possible correlations of irisin levels with EMP and EPC subpopulations [ 24 , 31 ]. Regarding previous studies that examined irisin levels in preterm-born individuals compared to individuals born at term, the effect size (ES) was medium using Cohen’s (1988) criteria; ES = 0.52 [ 33 ] and ES = 0.55 [ 34 ]. With an alpha = 0.05 and power = 0.80, the projected sample size needed with this effect size (GPower 3.1.9.2 software) was found to be at least N = 53 for each of the groups of children studied.…”

“…Regarding the effect of preterm birth on irisin levels, previous studies have shown lower circulating irisin levels in children born prematurely compared to full-term born peers [ 33 ]; furthermore, lower irisin levels have been observed in preterm-born infants compared to infants born at term [ 34 , 35 ]. However, the effect of irisin on cardiovascular risk and endothelial dysfunction of preterm-born individuals is still under investigation.…”