Impact of silencing MMP9 gene on the biological behaviors of trophoblasts

Fractalkine Regulates HEC-1A/JEG-3 Interaction by Influencing the Expression of Implantation-Related Genes in an In Vitro Co-Culture Model

Embryo implantation is a complex process regulated by a network of biological molecules. Recently, it has been described that fractalkine (CX3CL1, FKN) might have an important role in the feto-maternal interaction during gestation since the trophoblast cells express fractalkine receptor (CX3CR1) and the endometrium cells secrete fractalkine. CX3CR1 controls three major signalling pathways, PLC-PKC pathway, PI3K/AKT/NFκB pathway and Ras-mitogen-activated protein kinases (MAPK) pathways regulating proliferation, growth, migration and apoptosis. In this study, we focused on the molecular mechanisms of FKN treatment influencing the expression of implantation-related genes in trophoblast cells (JEG-3) both in mono-and in co-culture models. Our results reveal that FKN acted in a concentration and time dependent manner on JEG-3 cells. FKN seemed to operate as a positive regulator of implantation via changing the action of progesterone receptor (PR), activin receptor and bone morphogenetic protein receptor (BMPR). FKN modified also the expression of matrix metalloproteinase 2 and 9 controlling invasion. The presence of HEC-1A endometrial cells in the co-culture contributed to the effect of fractalkine on JEG-3 cells regulating implantation. The results suggest that FKN may contribute to the successful attachment and implantation of embryo.

Transcriptional Dynamics of Cultured Human Villous Cytotrophoblasts

During human pregnancy, cytotrophoblasts (CTBs) play key roles in uterine invasion, vascular remodeling, and anchoring of the feto-placental unit. Due to the challenges associated with studying human placentation in utero, cultured primary villous CTBs are used as a model of the differentiation pathway that leads to invasion of the uterine wall. In vitro, CTBs emulate in vivo cell behaviors, such as migration, aggregation, and substrate penetration. Although some of the molecular features related to these cell behaviors have been described, the underlying mechanisms, at a global level, remain undefined at midgestation. Thus, in this study, we characterized second-trimester CTB differentiation/invasion in vitro, correlating the major morphological transitions with the transcriptional changes that occurred at these steps. After plating on Matrigel as individual cells, CTBs migrated toward each other and formed multicellular aggregates. In parallel, using a microarray approach, we observed differentially expressed (DE) genes across time, which were enriched for numerous functions, including cell migration, vascular remodeling, morphogenesis, cell communication, and inflammatory signaling. DE genes encoded several molecules that we and others previously linked to critical CTB function in vivo, suggesting that the novel DE molecules we discovered played important roles. Immunolocalization confirmed that CTBs in situ gave a signal for two of the most highly expressed genes in vitro. In summary, we characterized, at a global level, the temporal dynamics of primary human CTB gene expression in culture. These data will enable future analyses of various types of in vitro perturbations-for example, modeling disease processes and environmental exposures.

Kisspeptin regulation of genes involved in cell invasion and angiogenesis in first trimester human trophoblast cells

The precise regulation of extravillous trophoblast invasion of the uterine wall is a key process in successful pregnancies. Kisspeptin (KP) has been shown to inhibit cancer cell metastasis and placental trophoblast cell migration. In this study primary cultures of first trimester human trophoblast cells have been utilized in order to study the regulation of invasion and angiogenesis-related genes by KP. Trophoblast cells were isolated from first trimester placenta and their identity was confirmed by immunostaining for cytokeratin-7. Real-time quantitative RT-PCR demonstrated that primary trophoblast cells express higher levels of GPR54 (KP receptor) and KP mRNA than the trophoblast cell line HTR8Svneo. Furthermore, trophoblast cells also expressed higher GPR54 and KP protein levels. Treating primary trophoblast cells with KP induced ERK1/2 phosphorylation, while co-treating the cells with a KP antagonist almost completely blocked the activation of ERK1/2 and demonstrated that KP through its cognate GPR54 receptor can activate ERK1/2 in trophoblast cells. KP reduced the migratory capability of trophoblast cells in a scratch-migration assay. Real-time quantitative RT-PCR demonstrated that KP treatment reduced the expression of matrix metalloproteinase 1, 2, 3, 7, 9, 10, 14 and VEGF-A, and increased the expression of tissue inhibitors of metalloproteinases 1 and 3. These results suggest that KP can inhibit first trimester trophoblast cells invasion via inhibition of cell migration and down regulation of the metalloproteinase system and VEGF-A.

Docosahexaenoic acid supplementation early in pregnancy may prevent deep placentation disorders

Uteroplacental ischemia may cause preterm birth, either due to preterm labor, preterm premature rupture of membranes, or medical indication (in the presence of preeclampsia or fetal growth restriction). Uteroplacental ischemia is the product of defective deep placentation, a failure of invasion, and transformation of the spiral arteries by the trophoblast. The failure of normal placentation generates a series of clinical abnormalities nowadays called "deep placentation disorders"; they include preeclampsia, fetal growth restriction, preterm labor, preterm premature rupture of membranes, in utero fetal death, and placental abruption. Early reports suggested that a LC-PUFAs (long chain polyunsaturated fatty acids) rich diet reduces the incidence of deep placentation disorders. Recent randomized controlled trials are inconsistent to show the benefit of docosahexaenoic acid (DHA) supplementation during pregnancy to prevent deep placentation disorders, but most of them showed that DHA supplementation was associated with lower risk of early preterm birth. We postulate that DHA supplementation, early in pregnancy, may reduce the incidence of deep placentation disorders. If our hypothesis is correct, DHA supplementation, early in pregnancy, will become a safe and effective strategy for primary prevention of highly relevant pregnancy diseases, such as preterm birth, preeclampsia, and fetal growth restriction.

Trophoblast invasion and blood vessel remodeling are altered in a rat model of lifelong maternal obesity

Maternal obesity is associated with an increased risk of a number of pregnancy complications, including fetal demise, which may be linked to impaired placental development as a result of altered trophoblast invasion and vessel remodeling. Therefore, we examined these parameters in pregnant rats fed a control (normal weight) or high fat (HF) diet (obese) at 2 critical times of rat placental development. Early trophoblast invasion was increased by approximately 2-fold in HF-fed dams with a concomitant increase in the expression of matrix metalloproteinase 9 protein, a mediator of tissue remodeling and invasion. Furthermore, we observed significantly higher levels of smooth muscle actin surrounding the placental spiral arteries of HF-fed dams, suggesting impaired spiral artery remodeling. Taken together, the results of this study suggest that altered placental development is an important contributor to the poor pregnancy outcomes and increased fetal demise in our model of lifelong maternal obesity.

FOSL1 is integral to establishing the maternal-fetal interface

Remodeling of uterine spiral arteries by trophoblast cells is a requisite process for hemochorial placentation and successful pregnancy. The rat exhibits deep intrauterine trophoblast invasion and accompanying trophoblast-directed vascular modification. The involvement of phosphatidylinositol 3 kinase (PI3K), AKT, and Fos-like antigen 1 (FOSL1) in regulating invasive trophoblast and hemochorial placentation was investigated using Rcho-1 trophoblast stem cells and rat models. Disruption of PI3K/AKT with small-molecule inhibitors interfered with the differentiation-dependent elaboration of a signature invasive-vascular remodeling trophoblast gene expression profile and trophoblast invasion. AKT isoform-specific knockdown also affected the signature invasive-vascular remodeling trophoblast gene expression profile. Nuclear FOSL1 increased during trophoblast cell differentiation in a PI3K/AKT-dependent manner. Knockdown of FOSL1 disrupted the expression of a subset of genes associated with the invasive-vascular remodeling trophoblast phenotype, including the matrix metallopeptidase 9 gene (Mmp9). FOSL1 was shown to occupy regions of the Mmp9 promoter in trophoblast cells critical for the regulation of Mmp9 gene expression. Inhibition of FOSL1 expression also abrogated trophoblast invasion, as assessed in vitro and following in vivo trophoblast-specific lentivirally delivered FOSL1 short hairpin RNA (shRNA). In summary, FOSL1 is a key downstream effector of the PI3K/AKT signaling pathway responsible for development of trophoblast lineages integral to establishing the maternal-fetal interface.