Background: Despite increasing evidence that human parturition is associated with alteration in gene expression in the uteroplacental unit, the precise mechanisms that elicit spontaneous term labor in humans remain unknown. Our goal in this study was to compare the mRNA expression pattern of the trophoblast layer of normal term placenta between women who had given natural birth (labor group) and those who had undergone an elective cesarean section without labor (non-labor group).
Methods: We collected placental tissue samples from six pregnant women after term vaginal deliveries (labor group) and from six pregnant women after scheduled Cesarean sections (non-labor group). Frozen sections were made immediately after placental delivery. Because the placenta is a heterogeneous tissue composed of several cell types, we used laser capture microdissection to separate the trophoblast layer from the rest of the placental tissues.
Results: A number of genes were differentially expressed in the trophoblast layer when the labor and non-labor groups were compared. The expression of SIRT1, KAP1, and CRH was significantly lower in the trophoblast layer of the labor group than of the non-labor group. The expression of IL-1b, NF-kB1 and TLR 8 in the labor group was significantly higher than that in the non-labor group.
Conclusions: Human term labor may be closely associated with inflammatory response. We suggest that downregulation of SIRT1, KAP1, and CRH gene expression in the trophoblast may play a key role in parturition and initiation of labor in pregnant human females.