Immunohistochemical localization of alpha-tocopherol transfer protein and lipoperoxidation products in human first-trimester and term placenta.
OBJECTIVE
Pregnancy is described as a state of oxidative stress arising from the high metabolic turnover taking place during feto-placental development and little is known about the balance of oxidation and antioxidation in early human pregnancy. The aim of this study was to analyze placental expression of alpha-tocopherol transfer protein (alpha-TTP) as the major transport protein for the antioxidant alpha-tocopherol as well as the placental expression of two lipoperoxidation products, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE) in early first-trimester and term human placenta.


METHODS
Placental tissue was obtained from 10 pregnancy interruptions at 6-8 weeks gestational age and 10 samples were obtained from term pregnancies after routine cesarean section. The placental expression of alpha-TTP, MDA and HNE has been investigated with immunohistochemistry by the use of specific human alpha-TTP, MDA and HNE antibodies.


RESULTS
While MDA and HNE showed similar expression in first-trimester and term placenta, alpha-TTP expression was less in first-trimester syncytiotrophoblast as compared to term. In first-trimester specimen, alpha-TTP showed major expression in extravillous trophoblast. In amniotic epithelial cells, a rising tendency in all three parameters investigated from immature to mature cells could be documented. No direct correlation between alpha-TTP, MDA and HNE expression was detected.


CONCLUSIONS
Our study shows the presence of alpha-TTP not only in term, but in first-trimester extravillous trophoblast, syncytiotrophoblast and amniotic epithelium. Furthermore, lipoperoxidation products MDA and HNE are also present in first-trimester and term placenta, documenting the presence of oxidative processes in the placenta from early on. It therefore seems possible that scavenging of reactive oxygen species (ROS) by alpha-tocopherol is already required in first-trimester human pregnancy, but the missing correlation to MDA and HNE expression leads to the speculation that alpha-TTP and its ligand alpha-tocopherol have functions beyond the antioxidative capacity of alpha-tocopherol in early pregnancy.
Division of Neonatology, Department of Pediatrics, University of Heidelberg, INF 150, D-69120 Heidelberg, Germany. daisy.rotzoll@med.uni-heidelberg.de
Daisy E
DE
Rotzoll
Regina
R
Scherling
Ronny
R
Etzl
Holger
H
Stepan
Lars-Christian
LC
Horn
Johannes M
JM
Pöschl
D000447:Aldehydes / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy / Q000378:metabolism*; D011261:Pregnancy Trimester, First / Q000378:metabolism*; D011263:Pregnancy Trimester, Third / Q000378:metabolism
D000447:Aldehydes; D000975:Antioxidants; D002352:Carrier Proteins; C017763:alpha-tocopherol transfer protein; D008315:Malondialdehyde; C027576:4-hydroxy-2-nonenal