Corticotropin-releasing hormone binding to the syncytiotrophoblast membranes

Effects of corticotrophin releasing hormone (CRH) on cell viability and differentiation in the human BeWo choriocarcinoma cell line: a potential syncytialisation inducer distinct from cyclic adenosine monophosphate (cAMP)

BACKGROUND

Placental production of corticotrophin releasing hormone (CRH) rises exponentially as pregnancy progresses, and has been linked with the onset of normal and preterm labour. CRH is produced in syncytiotrophoblast cells and production is increased by glucocorticoids and cAMP. It remains unclear whether cAMP acts by inducing differentiation of cytotrophoblasts and/or through induction of syncytialisation. As CRH can stimulate cAMP pathways we have tested whether a feed-forward system may exist in placental cells during syncytialisation.

METHODS

The choriocarcinoma BeWo cell line was treated with cAMP, CRH or vehicle. Cell viability was determined by MTT assay, while apoptosis was analysed by DAPI staining and by FACS. Differentiation was measured by assaying message for hCG and ERVW-1 (syncytin1) by qRT-PCR, as well as the respective protein by ELISA. Fusion of BeWo cells was assessed by co-staining cell membrane and nuclei with CellMask and Hoechst 33342. CRHR1 and CRHR2 mRNA levels were measured by qRT-PCR.

RESULTS

We show that cAMP has an inductive effect on syncytialisation, as evidenced by induction of hCG secretion, by ERVW-1 mRNA expression and by formation of multinuclear cells. CRH mRNA expression was found to increase prior to the changes in the other syncytialisation markers. cAMP had an inhibitory effect on BeWo cell viability, but exogenous CRH did not. However, CRH did mimic the differentiation inducing effect of cAMP, suggesting a link between CRH and cAMP signalling in syncytialisation. We also found that treatment of BeWo cells with exogenous CRH resulted in elevated cellular CRHR1 levels.

CONCLUSIONS

This study suggests a positive feed-forward role exists for CRH in trophoblast cell differentiation, which may underlie the exponential rise in CRH observed as gestation advances.

Human fetal and maternal corticotrophin releasing hormone responses to acute stress

OBJECTIVES

To study the effect of acute stress, caused by intrauterine needling at the intrahepatic vein (IHV), on fetal plasma concentrations of corticotrophin releasing hormone (CRH), and to compare paired fetal and maternal samples for CRH concentration to determine the extent of their joint control.

DESIGN

Venous blood samples were obtained from fetuses (gestational age 17-38 weeks) undergoing fetal blood sampling (n = 29) or intrauterine transfusion (n = 17) through either the IHV or the placental cord insertion (PCI).

SETTING

The Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London, UK.

PATIENTS

Pregnant women undergoing clinically indicated fetal blood sampling or intrauterine blood/platelet transfusion.

RESULTS

Fetal plasma cortisol increased with intrahepatic vein transfusion (mean (SD) cortisol response Delta64.7 (54.5) nmol/l; p < 0.0001, n = 11), and fetal corticotrophin concentrations were higher after IHV (n = 7) than PCI needling (n = 6). Neither fetal nor maternal plasma CRH increased after IHV transfusion. Fetal CRH levels did not rise with gestation, whereas maternal CRH levels did (r = 0.58; n = 36; p < 0.0001). There was a modest correlation between paired maternal and fetal values (r = 0.36; n = 36; p = 0.03).

CONCLUSIONS

Acute fetal stress, caused by IHV needling of the fetal abdomen, resulted in hypothalamic-pituitary-adrenal axis activation, as shown by a rise in fetal cortisol and corticotrophin. However, it did not result in measurable CRH release into fetal plasma. This suggests that fetal plasma CRH is not derived from the hypophyseal-portal circulation, but from another source, presumably the placenta.