The possible role of AhR in the protective effects of cigarette smoke on preeclampsia.

Although smoking during pregnancy may lead to many adverse effects, such as fetal growth restriction, placental abruption, stillbirth, and preterm labor, smoking is the only environmental exposure known to consistently reduce the risk of preeclampsia and gestational hypertension. The exact mechanisms through which cigarette smoke reduces the risk of preeclampsia are not yet understood. Aryl hydrocarbon receptor (AhR), as the most abundant expression protein in the placenta, was widely studied in the human reproduction. We propose that cigarette smoke decreases the risk of developing preeclampsia via direct activation of AhR system in placenta. In this review we will address, and provide evidence for, our specific hypotheses that: cigarette significantly enhance trophoblast invasion and decrease placental oxidative damage through activation of AhR. This mechanism of suppression must be further investigated as they may provide valuable clues to novel therapeutic design in the realm of preeclampsia research.