Expression of NADPH oxidase isoform 1 (Nox1) in human placenta: involvement in preeclampsia

Increased oxidative stress in the placenta has been associated with preeclampsia (PE), a clinical syndrome involving placental pathology. The enzymatic sources of reactive oxygen species in the human placenta are as yet unidentified. We hypothesized that NADPH oxidase is a main source of reactive oxygen species in the placenta and its expression may change in PE. Employing RT-PCR, we have amplified a novel NADPH oxidase isoform Nox1 from human choriocarcinoma BeWo cells. Using polyclonal anti-peptide antiserum recognizing unique Nox1 peptide sequences, we identified by immunohistochemistry and cell fractionation that Nox1 protein localizes in the BeWo cell membrane structures. Immunohistochemistry of normal placental tissues showed that Nox1 was localized in syncytiotrophoblasts, in villous vascular endothelium, and in some stromal cells. At the immunohistochemical level Nox1 expression was significantly increased in syncytiotrophoblast and endothelial cells in placentas from patients with preeclampsia as compared to gestational age-matched controls. Western blot analysis of whole placental homogenate confirmed this increase. Our data suggests that increased Nox1 expression is associated with the increased oxidative stress found in these placentas.