N-glycans of human amniotic fluid transferrin stimulate progesterone production in human first trimester trophoblast cells in vitro

Aims: During pregnancy, the placenta produces a variety of steroid
hormones and proteins. Several of these substances have been shown
to exert immunomodulatory effects. Progesterone is thought to
mediate some of these effects by regulating uterine responsiveness.
The aim of this study was to clarify the effect of amniotic fluid
transferrin and its N-glycans on the release of progesterone by
first trimester trophoblast cells in vitro. Methods:
Cytotrophoblast cells were prepared from human first trimester
placentae by trypsin-DNAse dispersion of villous tissue followed by
a percoll gradient centrifugation and depletion of CD45 positive
cells by magnetic cell sorting. Trophoblasts were incubated with
varying concentrations (50-300 mug/ml) of transferrin from human
amniotic fluid and serum as well as with N-glycans obtained from
amniotic fluid transferrin. Culture supernatants were assayed for
progesterone by enzyme-immunometric methods. Results: The release
of progesterone increased in amniotic fluid transferrin- and
N-glycan-treated trophoblast cell cultures compared to untreated
trophoblast cells. There was no stimulating effect of serum
transferrin on the progesterone production of trophoblast cells.
Conclusions: The results suggest that amnion-transferrin and
especially its N-glycans modulate the endocrine function of
trophoblasts in culture by up regulating progesterone secretion.