Placental Vitamin D-Binding Protein Expression in Human Idiopathic Fetal Growth Restriction

Vitamin D-binding protein is a multifunctional serum protein with multiple actions related to normal health. Vitamin D-binding protein transports vitamin D and influences the metabolism of this key hormone but it also has additional immunomodulatory and actin-clearing properties. We investigated whether vitamin D-binding protein expression is altered in fetal growth restrictionassociated placental dysfunction. Protein was extracted from 35 placentae derived from 17 healthy control subjects and 18 gestationmatched subjects with fetal growth restriction (FGR). FGR subjects were further subdivided as idiopathic ( = 9) and nonidiopathic ( = 9). Vitamin D-binding protein and 25(OH) vitamin D were measured by ELISA and normalized to protein concentration. The results showed significantly reduced levels of placental vitamin D-binding protein (control versus FGR, < 0.05, Student's -test) that were strongly associated with idiopathic fetal growth restriction ( < 0.01, Kruskal-Wallis), whereas levels of vitamin D-binding protein were not associated with placental 25(OH) vitamin D stores ( = 0.295, Pearson's correlation). As such, vitamin D-binding protein may be a factor in unexplained placental dysfunction associated with idiopathic fetal growth restriction and may potentially serve as a biomarker of this disease