Study sheds light on role of oxidants in preeclampsia

Accumulating evidence suggests that oxidative stress influences the onset of preeclampsia, but the mechanism is unclear. Now, a new Japanese study helps clarify the etiology by linking low antioxidant activity by indoleamine 2,3-dioxygenase (IDO) to increased oxidative stress in preeclamptic placentas.

The new study, published in Systems Biology in Reproductive Medicine (2011;57:174-178), builds on previous work by the authors showing that reduced IDO expression in the placenta impairs feto-maternal immunotolerance and leads to preeclampsia. Comparison of placental biopsies from 18 preeclamptic pregnancies and 23 normotensive controls revealed that placental levels of the oxidative stress marker 8-hydroxy-2'-deoxy-guanosine (8-OHdG) were markedly higher in preeclamptic than normotensive patients and that an inverse correlation existed between IDO and 8-OHdG levels.

“These results show that oxidative stress is associated with decreased IDO activity in the preeclamptic placenta and suggest an impact of low IDO activity other than immune modulation in promoting the onset of this disorder,” the researchers conclude.

Normal physiological conditions during pregnancy protect the placenta from oxidative stress, the authors explain. “Our present findings indicate that IDO plays a pivotal role in this antioxidant defense system in the placenta and that this is defective in preeclampsia,” they write.

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