Background: Visceral adipose tissue-derived serine protease inhibitor (vaspin) has been suggested as a novel adipocytokine related to obesity and insulin sensitivity in adults.
Design: We quantified vaspin serum concentrations in 65 lean and 67 obese children and aimed to evaluate the relationship of vaspin with physical development, obesity, and metabolic and cardiovascular phenotypes in children. We further assessed the acute vaspin response to glucose provocation in 20 obese adolescents and evaluated tissue expression patterns of vaspin in humans.
Results: Vaspin levels were significantly higher in girls than in boys. In girls, vaspin increased with age and pubertal stage, whereas there was no change with development in boys. Obese girls had lower vaspin serum levels than those of lean controls, but there was no significant correlation with body mass index (BMI). Independent of sex, age and BMI, lower vaspin was associated with better insulin sensitivity, with higher systolic blood pressure and impaired endothelial function. In response to glucose provocation during an oral glucose tolerance test, vaspin serum levels declined by approximately 25% in adolescents with hyperinsulinemia, whereas there was no significant decline in normoinsulinemic patients. In support of our clinical data, we not only confirmed vaspin mRNA expression in adipose tissue but also found consistent expression of vaspin in the liver and indications for expression in the pancreas and the skin.
Conclusion: We showed that gender differences in circulating vaspin levels develop during pubertal progression in girls. Although vaspin's association with obesity remains controversial, vaspin was increased with worsening insulin resistance already in children and was acutely down-regulated following glucose provocation in insulin-resistant adolescents independent of obesity. Besides adipose tissue, vaspin expression in the liver and the pancreas may potentially contribute to circulating vaspin levels and their regulation.