Systemic administration of synthetic glucocorticoid induces PE-like features in pregnant rats
We then explored whether excess GCs mediate PE-like features caused by placental 11β-HSD2 downregulation. As shown in Fig.3A&B, administration of DEX from GD 7.5 and 17.5 could result in a significant increase in SBP and protein/creatinine in urine. The rats with DEX treatment also displayed abnormal renal morphology including hypercellularity in mesangial and occlusion of capillary loops and the urinary space (Fig.3C) and a higher histopathological score compared with control rats (Fig.3D). As expected, elevated circulatory sFlt1 level and decreased fetal weight were also found in DEX-treated dams (Fig.3E&F).
Placental 11β-HSD2 downregulation results in deficient invasion of interstitial trophoblasts, impaired endovascular SA remodeling and reduced placental blood flow
The area of interstitial trophoblast invasion in MT was measured for evaluation of trophoblast invasion in uterus (Fig.4A). It was significantly reduced in CBX (1.2 and 2.4 mg/kg) groups compared with vehicle group (Fig.4B). Less trophoblasts infiltrated in SA higher α-actin staining intensity in SA were found in CBX (1.2 and 2.4 mg/kg) groups compared with vehicle group (Fig.4C). Abnormal morphology of placenta was found in CBX (1.2 and 2.4 mg/kg) groups as evidenced by disorganization in the labyrinth zone (Fig.4D) and reduced laminin staining intensity compared with vehicle group (Fig.4E).
Specific delivery of CBX to placenta also led to impaired interstitial trophoblast invasion and SA remodeling. The area of interstitial trophoblast invasion was significantly decreased in CBX-CSA group compared with vehicle. Higher α-actin staining intensity and less trophoblast infiltration in SA were displayed in CBX-CSA group (Fig.5C). Obvious morphological disturbance with disorganization in the labyrinth zone and reduced laminin staining intensity in the placentas were also exhibited in CBX-CSA group (Fig.5D&E). The animals of CBX-NPs and CBX-SCR groups did not show abnormal interstitial trophoblast invasion, trophoblast infiltration and placental morphology.
The placental blood flow was examined by using Doppler ultrasonography (Fig.6A&B). The placental blood flow was significantly decreased in the pregnant rats with CBX (1.2 and 2.4mg/kg) treatment as evidenced by a significant reduction in peak systolic velocity (PSV) of SA, maternal canal and umbilical artery compared with control rats (Fig.6C). As shown in Fig.6D, CBX-CSA group also displayed a significant decrease in PSV of SA, maternal canal and umbilical artery. The rats of CBX-NPs and CBX-SCR groups did not show reduced PSV of SA, maternal canal and umbilical artery compared with control rats.
11β-HSD2 downregulation suppressestrophoblast migration and invasion and promotes sFlt-1 release in the models of cultured human trophoblasts
To extent our rodent studies, we investigate the role of 11β-HSD2 in PE pathogenesis using human placental tissue and trophoblast modelsin vitro . At first, we examined whether 11β-HSD2 is involved in regulation of the migration and invasion of extravillous trophoblast (EVT) cell lines, HTR8 and HIPEC60. It was found that cortisol (10-9M-10-6M) treatment did not significantly affect the migration and invasion function (supplemental Fig. S6). However, cortisol (10-6M) significantly suppressed migration and invasion in the cells transfected with 11β-HSD2 siRNA (supplemental Fig.S6&7).
We then examined the role of 11β-HSD2 in regulation of PlGF and sFlt1secretion in human placental explants and cells. In the presence of 11β-HSD2 inhibitor CBX (10-6-10-5M), cortisol (10-6M) treatment significantly increased sFlt1 release (Fig.7A) but did not significantly affect PlGF secretion in placental explants (supplemental Fig. S8). Cortisol treatment also significantly increased sFlt1 output in cultured primary syncytiotrophoblasts with CBX treatment (Fig.7B). In the syncytiotrophoblasts transfected with 11β-HSD2 siRNA, cortisol could also promote sFlt1 secretion (Fig.7C). We then examined the effect of cortisol on sFlt1 mRNA expression in order to study whether cortisol promotes sFlt1 output via modulating sFlt1 transcript. However, cortisol treatment had no impact on sFlt1 mRNA expression (supplemental Fig. S8).