The involvement of the transcription factor Nrf2 in fetal growth restriction

N Kweider; CJ Wruck; J Lambertz; T Pufe; W Rath

doi:10.1055/s-0033-1361386

Zeitschrift für Geburtshilfe und Neonatologie, Inhaltsverzeichnis

The involvement of the transcription factor Nrf2 in fetal growth restriction

N Kweider ¹, CJ Wruck ¹, J Lambertz ¹, T Pufe ¹, W Rath ²

¹Medical Faculty, RWTH Aachen University, Department of Anatomy and Cell Biology, Aachen, Germany
²Medical Faculty, University Hospital of RWTH, Obstetrics and Gynecology, Aachen, Germany

Abstract

Objectives: It has been shown that preeclampsia is associated with an increased activity of the transcription factor NF-E2-related factor 2 (Nrf2) within the cytotrophoblast, we recently discussed in vitro a link between Nrf2 and vascular homeostasis. Also early onset IUGR associated with preeclampsia has been associated with impaired invasion of the extravillous trophoblast and dysfunctional Nrf2 signaling.

To assess the interaction between Nrf2 signal-transduction pathways and the angiogenesis process, we tested first in vitro the effect of Nrf2 activation on the pro- and anti-angiogenic factors. Then we investigated the placental phenotype of the Nrf2 knockout mice (Nrf2^-/-) and wild type (Nrf2^+/+) around embryonic day (ED) 18.5.

Methods: In vitro; BeWo and primary HUVECs were used to study the angiogenic effect of Nrf2-activation. ELISA, scratch- and tube formation-assay were applied.

In vivo; around the embryonic day (ED 18.5) the placentas of Nrf2 knockout mice (Nrf2 ^-/^-) and Nrf2 wild type mice (Nrf2 ⁺/⁺) were fixed and embedded in paraffin.

H&E stain, Periodic Acid Schiff (PAS) and immunohistochemistry, using antibodies against the vascular endothelial growth factor (VEGF), Nrf2 and the lipid peroxidation marker 4-hydroxy-2-nonenal (4-HNE), were performed in this study.

Results: The induction of Nrf2 led to a significant increase in the protein levels of VEGF and decrease in the augmented- Soluble fms-like tyrosine kinase-1 (sFlt-1) in the supernatant of the treated cells. Activation of Nrf2 enhanced tube formation and migration of the endothelial cells.

Nrf2 knockout embryos (Nrf2^-/-) were found to be 13% smaller than the wild type embryos at embryonic day E 18.5 (Nrf2^+/+0,9715 ± 0,01894 and the Nrf2^-/-0,8391 ± 0,01569). The Phenotypic analysis of ED 18.5 placentas showed presence of trophoblast clusters in the labyrinth and frequent enlarged maternal blood lacunae in Nrf2^-/-.

Furthermore, placenta from Nr2^-/- mice showed increased levels of the lipid peroxidation product 4- Hydroxinonoeal.

Conclusion: This data point to necessity of Nrf2 for the placental development, as it may interact with the differentiation of the trophoblast lineage and diminish the oxidative damage during pregnancy. On the other hand, the activation of Nrf2 inhibited the release of sFlt-1 in vitro, thus the activation of Nrf2 during the first trimester may improve the balance of the pro- and anti-angiogenic factors and thereby prevent IUGR from occurring.