Antenatal Dexamethasone Treatment Leads to Changes in Gene Expression in a Murine Late Placenta

Abstract

Antenatal steroids like dexamethasone (DEX) are used to augment foetal lung maturity and there is a major concern that they impair foetal growth. If delivery is delayed after using antenatal DEX, placental function and hence foetal growth may be compromised even further. To investigate the effects of DEX on placental function, we treated 9 pregnant C57/BL6 mice with DEX and 9 pregnant mice were injected with saline to serve as controls. Placental gene expression was studied using microarrays in 3 pairs and other 6 pairs were used to confirm microarray results by semi-quantitative RT-PCR, real-time PCR, in situ hybridization, western blot analysis and Oligo ApopTaq assay. DEXtreated placentas were hydropic, friable, pale, and weighed less (80.0±15.1 mg compared to 85.6.8 ±7.6 mg, p=0.05) (n=62 placentas). Foetal weight was significantly reduced after DEX use (940±32 mg compared to 1162±79 mg, p=0.001) (n=62 foetuses). There was > 99% similarity within and between the three gene chip data sets. DEX led to down-regulation of 1212 genes and up-regulation of 1382 genes. RT-PCR studies showed that DEX caused a decrease in expression of genes involved in cell division such as cyclins A2, B1, D2, cdk 2, cdk 4 and M-phase protein kinase along with growth-promoting genes such as EGF-R, BMP4 and IGFBP3. Oligo ApopTaq assay and western blot studies showed that DEX-treatment increased apoptosis of trophoblast cells. DEX-treatment led to up-regulation of aquaporin 5 and tryptophan hydroxylase genes as confirmed by real-time PCR, and in situ hybridization studies. Thus antenatal DEX treatment led to a reduction in placental and foetal weight, and this effect was associated with a decreased expression of several growth-promoting genes and increased apoptosis of trophoblast cells.

The Effects of Glucocorticoids on Fetal and Placental Development

“…Dex-treatment increased apoptosis of trophoblast cells in mouse and rat placentas. Dex-induced trophoblast apoptosis was mediated through activation of caspases 1 and 3 [58,95]. Apoptosis was also induced in primary cultures of third trimester human decidual cells when treated with cortisol, cortisone, or dexamethasone [34].…”

“…Dex-treated mouse placentas showed swollen trophoblast cells in both the junctional and labyrinth zones and increased apoptosis of trophoblast cells in the junctional zone. Moreover, Dex-treated placentas were hydropic, friable and pale [58]. Increasing antenatal corticosteroid exposure was associated with villous fibrosis, stromal mineralization, and less frequent villous infarction [93].…”

“…Therefore, Dex appears to reduce labyrinth zone growth by preventing the normal development of the fetal vasculature within the labyrinth zone [59]. Moreover, microarray analysis showed that Dex caused a decrease in expression of genes involved in cell division such as cyclins A2, B1, D2, CDK 2, CDK 4 and M-phase protein kinase along with growth-promoting genes such as epidermal growth factor receptor, bone morphogenetic protein 4 and insulin-like growth factor-binding protein 3 [58]. In addition, 3H-thymidine incorporation assay revealed that proliferation of trophoblast cell lines JEG-3 and HTR-8/SV neo and human first-trimester primary trophoblasts was time-and dose-dependently inhibited by glucocorticoids [94].…”

“…In addition, Dex treatment led to down-regulation of genes involved in protein biosynthesis, skeletal development, and collagen metabolism. There was also decreased expression of genes involved in cell division, DNA replication, chromosome segregation, DNA alkylation, nucleotide and nucleoside biosynthesis, microtubule-based processes, B-cell activation and differentiation processes, innate immune response, antigen processing and presentation, and complement system [58]. Treatment of rats with glucocorticoids restricts placental vascular development via inhibition of the VEGF-A and peroxisome proliferator-activated receptor (PPAR ) which is regulated by VEGF-A expression [59,60].…”

Histoquímica e morfometria da placenta de ratas tratadas com dexametasona

“…Sabe-se que as células trofoblásticas gigantes binucleadas surgem da endoduplicação (mitoses incompletas) das células trofoblásticas gigantes da zona do labirinto (Klisch et al 1999, Simmins et al 2007), as quais estão situadas na parte em contato íntimo com a decídua, sendo considerada uma das principais células endócrinas da placenta por secretarem hormônios esteróides e peptídicos. Tem sido demonstrado ainda que o tratamento com dexametasona promoveu um aumento da secreção de gonadotrofina coriônica pelas células trofoblásticas (Baisden et al 2007). Dessa forma o tratamento com dexametasona pode ter estimulado a síntese de gonadotrofinas o que pode ter sido o fator primordial para a migração e desenvolvimento das células trofoblásticas da região do labirinto, diferenciando-se assim nas células trofobláticas gigantes sinusoidais.…”