Human placental peroxisome proliferator-activated receptor δ and γ expression in healthy pregnancy and in preeclampsia and intrauterine growth restriction

OBJECTIVES: Human and animal studies have demonstrated that peroxisome proliferator-activated receptors (PPARs) are important in placental development and play key roles in metabolism and inflammation. We studied placental PPAR delta, PPAR gamma, and retinoid X receptor alpha (RXR alpha) expression in healthy pregnancy and in preeclampsia (PET) and intrauterine growth restriction (IUGR). METHODS AND RESULTS: Using immunocytochemistry, PPAR delta, PPAR gamma, and RXR alpha were localized to the cyto- and syncytiotrophoblast and invading trophoblast columns in first and second trimester placentas. Third trimester placentas from healthy pregnancy, and in PET and IUGR, demonstrated PPAR delta, PPAR gamma, and RXR alpha staining within the syncytium, and localization within isolated cells in the stroma. In uncomplicated pregnancies, PPAR delta mRNA expression (PPAR delta:18s ratio, third trimester median 0.43 [interquartile (IQ) range 0.26-0.52] vs first trimester 0.20 [0.00-0.26], P = .03) and PPAR delta protein expression (third trimester 3.94 [2.45-4.68] vs first trimester 1.29 [0.78-2.29] optical densitometry [OD] mm(2), P = .04) were higher in the third trimester than in the first trimester. There were no consistent differences in PPAR delta, PPAR gamma, or PXR alpha mRNA and protein expression among PET or IUGR placentas and controls. CONCLUSION: PPAR delta expression is up-regulated between the first and third trimester, indicating a role for this nuclear receptor in placental function. We found no evidence that placental PPAR delta, PPAR gamma, and RXR alpha expression is changed in PET or IUGR. This suggests that changes in total placental PPAR expression are riot involved in the pathophysiology, of these conditions. Copyright (c) 2005 by the Society for Gynecologic Investigation.