Abstract
BackgroundDespite 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).MethodsWe 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.ResultsA 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.ConclusionsHuman 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.
Highlights
Human pregnancy lasts for approximately 38 weeks after conception
Researchers from our center previously reported that 351 genes were differentially expressed in the placentas of a vaginal delivery group compared to the placentas of a Cesarean section group
IL-1 and -6 and TNF- α have been shown to be expressed at higher levels in gestational tissue after preterm and term labor compared with tissues from women who delivered at similar gestational ages without labor [16]
Summary
Human pregnancy lasts for approximately 38 weeks after conception. The timing of birth in mice is closely related to maturation of the fetal lungs [1]. Villous placenta consists of a heterogeneous mixture of cell types including the trophoblast layers (syncytiotrophoblasts and cytotrophoblasts) and villous core (villous stroma and fetal blood vessels). Histological techniques such as immunohistochemistry and in-situ hybridization provide information about the localization of proteins and mRNAs encoding specific genes, these are semi-quantitative methods. We used LCM to compare the expression of genes in the trophoblast layer of term placentas between the labor group and non-labor group. As the limited amount of tissue after LCM limits the number of genes that can be studied, we examined the expression of CRH, FLT-1, NF-kB1, TLR8 , KAP1, SIRT1, IL-1B and IL-6 in this study
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