Decidual Stromal Cell Response to Paracrine Signals from the Trophoblast: Amplification of Immune and Angiogenic Modulators1

Abstract

During the invasive phase of implantation, trophoblasts and maternal decidual stromal cells secrete products that regulate trophoblast differentiation and migration into the maternal endometrium. Paracrine interactions between the extravillous trophoblast and the maternal decidua are important for successful embryonic implantation, including establishing the placental vasculature, anchoring the placenta to the uterine wall, and promoting the immunoacceptance of the fetal allograph. To our knowledge, global crosstalk between the trophoblast and the decidua has not been elucidated to date, and the present study used a functional genomics approach to investigate these paracrine interactions. Human endometrial stromal cells were decidualized with progesterone and further treated with conditioned media from human trophoblasts (TCM) or, as a control, with control conditioned media (CCM) from nondecidualized stromal cells for 0, 3, and 12 h. Total RNA was isolated and processed for analysis on whole-genome, high-density oligonucleotide arrays containing 54,600 genes. We found that 1374 genes were significantly upregulated and that 3443 genes were significantly downregulated after 12 h of coincubation of stromal cells with TCM, compared to CCM. Among the most upregulated genes were the chemokines CXCL1 (GRO1) and IL8,CXCR4, and other genes involved in the immune response (CCL8 [SCYA8], pentraxin 3 (PTX3), IL6, and interferon-regulated and -related genes) as well as TNFAIP6 (tumor necrosis factor alpha-induced protein 6) and metalloproteinases (MMP1, MMP10, and MMP14). Among the downregulated genes were growth factors, e.g., IGF1, FGF1, TGFB1, and angiopoietin-1, and genes involved in Wnt signaling (WNT4 and FZD). Real-time RT-PCR and ELISAs, as well as immunohistochemical analysis of human placental bed specimens, confirmed these data for representative genes of both up- and downregulated groups. The data demonstrate a significant induction of proinflammatory cytokines and chemokines, as well as angiogenic/static factors in decidualized endometrial stromal cells in response to trophoblast-secreted products. The data suggest that the trophoblast acts to alter the local immune environment of the decidua to facilitate the process of implantation and ensure an enriched cytokine/chemokine environment while limiting the mitotic activity of the stromal cells during the invasive phase of implantation.

Implantation of the human embryo requires Rac1-dependent endometrial stromal cell migration

“…More recently, gene expression profiling of hESCs has shown that levels of many hESC mRNAs are modulated in response to trophoblast-conditioned medium (23) or after coculture with firsttrimester trophoblast explants (34), further corroborating the concept of embryo-mediated modulation of endometrial cell gene expression. Here, we have demonstrated that in vitro, the human embryo induces changes in hESC RacGAP1 expression levels.…”

“…The activity of Rac1 and other Rho GTPases can be regulated by guanine nucleotide exchange factors and dissociation inhibitors, which control the exchange of GDP for GTP, and by GTPase-activating proteins (GAPs) that promote GTP hydrolysis. Previous microarray data demonstrated that Rac-GAP1 (also known as MgcRacGAP) is down-regulated in hESCs after exposure to trophoblast-conditioned medium (23). We analyzed RacGAP1 expression in hESCs to determine whether the embryo-induced increase in hESC Rac1 activity that we observed in vitro resulted from localized inhibition or down-regulation of RacGAP1, which, in other cell types, inactivates Rac1 (24).…”

Novel insights into the mechanisms of pregnancy establishment: regulation of prostaglandin synthesis and signaling in the pig

“…Studies using stromal cells of the human endometrium decidualized with progesterone and treated with the conditioned media from trophoblasts indicated that human trophoblast signals the decidua, which in turn amplifies conceptus signals, especially related to immune modulation and angiogenesis, resulting in an enriched cytokine environment (Hess et al 2007). Immune response is one of the most highly represented gene ontology categories of upregulated genes in response to trophoblast-secreted products in decidual stromal cells.…”

Interferon-tau, a Type 1 interferon involved in maternal recognition of pregnancy

“…Although the IFN-τ are unique to the Ruminantia, a sub-order within the much larger Artiodactyla order, there are hints from transcriptional profiling experiments that a partial interferon-response occurs in humans and mice as the trophoblast makes intimate contact with the maternal endometrium and induces the formation of a deciduum, in which stromal fibroblast proliferate and form an edematous structure adjacent to the site of implantation (37)(38)(39). This response does not involve a full-blown up-regulation of many interferon-stimulated genes (ISGs), as noted in the sheep endometrium during early pregnancy (12,13,40), but is instead more limited.…”