Decreased expression of thioredoxin and glutaredoxin in placentae from pregnancies with pre-eclampsia and intrauterine growth restriction.

Pre-eclampsia is one of the major contributors to perinatal morbidity. This study was performed to test a hypothesis which suggests that pre-eclampsia is associated with inadequate control by the thioredoxin system and other related reducing systems. Placental tissue from normal pregnancies (NC), severe pre-eclampsia with fetuses small for gestational age (SPE), mild pre-eclampsia with fetuses small for gestational age (MPE) and pregnancies with small fetuses for gestational age without any sign of pre-eclampsia (IUGR) was collected immediately after delivery. The mRNA levels for thioredoxin and glutaredoxin were determined using a solution hybridization method and the distribution of the proteins in a normal placenta was analysed by immunohistochemistry. Results showed that the thioredoxin mRNA level in the SPE group was decreased to one third of the level in the NC group. Also the IUGR group showed a significant decrease. The glutaredoxin mRNA level in the SPE group was one half of that seen in the NC group. There was significant correlation between the mRNA levels for thioredoxin and glutaredoxin, both in the normal and growth restricted pregnancies. We conclude that the thioredoxin and glutaredoxin reducing systems are affected in placenta from pregnancies with pre-eclampsia and/or growth restriction of fetuses, and that the decrease correlates to the severity of the condition.