Altered placental glutathione peroxidase mRNA expression in preeclampsia according to the presence or absence of labor.

Increased placental oxidative stress in preeclampsia (PE) has been associated in part to a decrease in glutathione peroxidase (GPX) antioxidant activity. However, it is not clear if GPX mRNA expression is affected in PE, and how the presence of labor may impair this expression. In this study, we characterized by quantitative PCR, in situ hybridization and immunohistochemistry, the expression of four GPX (GPX1 to 4) in the placenta of normotensive (NP; n = 23) and PE pregnancies (n = 25) according to mode of delivery: vaginal delivery (with labor) or cesarean (without labor); the tissue layer: amnion-chorion (AC) and villi; and the sampling site: peri-insertion or peripheral. Concomitantly, oxidative stress markers mRNA expression, HSP70 and HO-1 were measured. All GPX mRNA and protein were detected in all layers of the placenta and sampling sites. In absence of labor, GPX1 is more expressed near the umbilical cord than at the periphery of the villi (p = 0.037). At the periphery of AC membranes, GPX2 was more expressed in PE than in controls in presence of labor (p = 0.037). Interestingly, GPX4 mRNA level was clearly deficient in the PE villi in presence or absence of labor (p < 0.0473). Also, the GPX4 expression in PE was lower than controls in AC membranes in presence of labor (p = 0.0007). Oxidative stress markers, HSP70 and HO-1, were higher in PE placental membranes than in controls in absence of labor (p < 0.011). HSP70 was also upregulated in PE placental membranes in presence of labor (p = 0.034). Correlations between stress markers and GPX mRNA expression were mostly present in AC membranes in presence of labor in NP. Most of the latter correlations were lost in PE. In conclusion, our results suggest that the reported decrease in GPx activity and increased oxidative stress in PE placental villi may be attributed in part to GPX4 independently of the presence or absence of labor.