Syndecan-1 knockdown in endometrial epithelial cells alters their apoptotic protein profile and enhances the inducibility of apoptosis.

Endometrial epithelial cells are known to undergo apoptosis during trophoblast invasion. We postulate that the cell surface molecule Syndecan-1 which is expressed on endometrial cells and syncytiotrophoblast is important for implantation in general and especially for induction of maternal cell apoptosis during trophoblast invasion because Syndecan-1's influence on apoptotic susceptibility of cancer cells is already described in the literature. Using the human endometrial epithelial cell line RL95-2, a new stable cell line with Syndecan-1 knockdown was generated. Via antibody array analysis, a significant decrease in the expression of anti-apoptotic proteins like inhibitors of apoptosis, Clusterin, heme oxygenase (HO-2), heat shock protein (HSP)27 and -70 and Survivin due to the Syndecan-1 knockdown was discovered. Correspondingly, active Caspase-3 as an indicator for apoptosis was increased more severely in these cells compared with unmodified RL95-2 after treatment with implantation-related stimuli, which are the cytokines interleukin-1ß, interferon-γ, tumor necrosis factor-α and transforming growth factor-ß1 and an anti-Fas antibody. Furthermore, a treatment with a combination of all factors caused a higher Caspase-3 induction compared with each single treatment. These results demonstrate that Syndecan-1 is involved in the control of apoptosis in RL95-2 cells and therefore may affect the fine tuning of apoptosis in endometrial epithelium regulating the embryo's invasion depth as a crucial step for regular implantation followed by successful pregnancy.

The human oviduct transcriptome reveals an anti-inflammatory, anti-angiogenic, secretory and matrix-stable environment during embryo transit.

The human oviduct serves as a conduit for spermatozoa in the peri-ovulatory phase and nurtures and facilitates transport of the developing embryo for nidation during the luteal phase. Interactions between the embryo and oviductal epithelial surface proteins and secreted products during embryo transit are largely undefined. This study investigated gene expression in the human oviduct in the early luteal versus follicular phases to identify candidate genes and biomolecular processes that may participate in maturation and transport of the embryo as it traverses this tissue. Oviductal RNA was hybridized to oligonucleotide arrays and resulting data were analysed by bioinformatic approaches. There were 650 genes significantly down-regulated and 683 genes significantly up-regulated (P<0.05) in the luteal versus follicular phase. Quantitative real-time PCR, immunoblot analysis and immunohistochemistry confirmed selected gene expression and cellular protein localization. Down-regulated genes involved macrophage recruitment, immunomodulation and matrix-degeneration, and up-regulated genes involved anti-inflammatory, ion transport, anti-angiogenic and early pregnancy recognition. The oviduct displayed some similarities and differences in progesterone-regulated genes compared with the human endometrium. Together, these data suggest a unique hormonally regulated environment during embryo development, maturation and transport through human oviduct and some conservation of progesterone signalling in tissues of common embryological origin. The oviduct serves as a conduit for spermatozoa in the peri-ovulatory phase and it nurtures and facilitates transport of the developing embryo during the luteal phase of the menstrual cycle, although precise interactions between the embryo and oviductal epithelium and secreted products are largely undefined. Herein, we investigated gene expression in human oviduct to identify candidate genes and processes that may participate in maturation and transport of the embryo as it develops implantation competence. Total RNA from human ampullary oviducts in the early luteal versus follicular phases was isolated and hybridized to oligonucleotide arrays. The data, analysed by bioinformatic approaches, revealed that 650 genes were significantly down- and 683 genes were significantly up-regulated in the luteal phase. Quantitative real-time PCR, immunoblot analysis and immunohistochemistry confirmed selected gene expression and cellular protein localization. The data demonstrated down-regulation of genes involved in macrophage recruitment, immunomodulation and matrix degeneration and up-regulation of ion transport and secretions, as well as anti-angiogenic and early pregnancy recognition. Together, these data suggest a unique hormonally regulated environment during embryo development, maturation and transport through the human oviduct and provide insight into mechanisms influencing acquisition of implantation competence of the human embryo during its passage through the oviduct en route to the uterine endometrium.

In vitro culture does not alter the expression of vascular endothelial growth factor and its receptors in single murine preimplantation embryos.

BACKGROUND: In vitro culture of embryos, as widely used in assisted reproduction techniques, may influence embryonic development and subsequently the establishment of pregnancy. The aim of this study was to determine a potential influence of the in vitroculture regarding VEGF, VEGFR1 and VEGFR2 mRNA expression in developing single mouse embryos. METHODS: Murine embryos were isolated on day 1 post coitus (p.c.) and cultivated for a developmental time course followed by examination for mRNA expression using RT-nested PCR. Furthermore, in vitro cultured blastocysts were compared to in vivo development at 101 h p.c. RESULTS: At 101 h p.c. there were no significant differences between in vivo and in vitro cultured blastocysts regarding the expression of VEGF and its receptors. In the developmental time course, VEGF expression increased up to 94% in late blastocysts whereas the VEGF receptor expression remained low. CONCLUSIONS: This study showed that the in vitro culture did not alter the embryonic VEGF and VEGFR mRNA expression reassuring that the culture conditions in assisted reproduction techniques are well suited for maintaining the VEGF mRNA expression profile. Additionally, nearly 100% VEGF expression in late blastocysts highlights its importance for angiogenesis induction at the fetal-maternal interface.

The embryo's cystatin C and F expression functions as a protective mechanism against the maternal proteinase cathepsin S in mice.

A successful implantation of a mammalian embryo into the maternal endometrium depends on a highly synchronized fetal-maternal dialogue involving chemokines, growth factors, and matrix-modifying enzymes. A growing body of evidence suggests an important role for proteinases playing a role in matrix degeneration and enhancing the embryo's invasive capacity and influencing the mother's immunological status in favor of the conceptus. This study focused on the expression of cathepsin S (CTSS) and its inhibitors in the murine fetal-maternal interface as well as the detection of the cellular sources of either proteinase and inhibitors. Nested RT-PCR for detection of embryonic mRNAs, immunohistochemistry of maternal and fetal tissues in B6C3F1 mice, and FACS analysis for determination of immunocompetent cell population were applied. This study shows that the cysteine proteinase CTSS is upregulated in the stroma of the implantation site, and that pregnancy induces an influx of CTSS-positive uterine natural killer cells. Compared to maternal tissues, the CTSS inhibitors cystatin F and C, but not the proteinase itself, are expressed in blastocysts. In conclusion, CTSS underlies a hormonal regulation in the maternal tissue and therewith most likely supports the embryonic implantation. The invading embryo regulates the depth of its own invasion through the expression of the cathepsin inhibitors and furthermore, interleukin-6 to activate CTSS in maternal tissues. Additionally, the observed decrease in CD3(+) cells leads to the hypothesis that cells of the cytotoxic T-cell group are down-regulated in the decidua to support the implantation and ensure the survival of the embryo.

Interleukin-1 system in the human fallopian tube-No spatial but a temporal regulation of mRNA and protein expression.

The human fallopian tube provides the environment for the first 5 days of embryonic development in vivo. The IL-1 system is involved in human embryo implantation. This study aimed to investigate IL-1beta, IL-1ra and IL-1R tI expression within the length of the human fallopian tube on mRNA- and protein-level in samples from proliferative versus secretory phase, postmenopause (PMP) samples and samples from intra- (IUP) and extrauterine pregnancies (EUP) to examine possible spatial and hormonal induced changes (fimbrial, ampullary and isthmic tube segments). On mRNA-level, IL-1beta was expressed in all samples except in PMP. IL-1R tI could be detected in all samples whereas IL-1ra was only expressed in secretory phase and the IUP sample. Immunohistochemically we could detect IL-1beta and IL-1R t1 protein in all proliferative and secretory phase samples with maximum intensity in secretory phase samples whereas IL-1ra was expressed in secretory phase samples only. Overall no spatial but temporal differences possibly due to hormonal changes could be observed suggesting a precise regulation of the IL-1 system, especially for IL-1ra and moreover a stable molecular architecture within the full length of the fallopian tube.

Expression of the vascular endothelial growth factor receptor neuropilin-1 in the human endometrium.

Angiogenesis is a key process in the endometrium which undergoes dramatic changes during the menstrual cycle. Molecules such as vascular endothelial growth factor (VEGF), acting via two tyrosine kinase family receptors (VEGFR1 [Flt-1] and VEGFR2 [KDR/Flk-1]), are potent modulators of angiogenesis and vascular remodelling in the endometrium. Recently, neuropilin-1 (NRP-1) was shown to be expressed in endothelial cells binding VEGF(165) and therewith enhancing the binding of VEGF(165) to VEGFR2. This suggests that NRP-1, in addition to the known VEGF receptors, may play an important role in VEGF-induced angiogenesis. In this study, the expression of NRP-1 in the cycling human endometrium has been investigated by reverse transcription (RT)-polymerase chain reaction (RT-PCR), semi-quantitative competitive RT-PCR (RT-cPCR) and immunohistochemical staining. NRP-1 was expressed in all 32 endometrium samples throughout the menstrual cycle. However, samples from the proliferative phase showed significantly higher expression levels of NRP-1 mRNA compared to samples from the secretory phase (t/c-ratio 2.13 vs. 0.84, p<0.05). Immunohistochemistry confirmed the results showing increased NRP-1 staining in vascular endothelium, glandular epithelium and stromal cells of the proliferative phase endometrium. This study demonstrates mRNA and protein expression of NRP-1 in human endometrium samples throughout the menstrual cycle. The enhanced expression of NRP-1 in the proliferative phase suggests that it may participate in hormonally regulated changes of endometrial angiogenesis, preparing the endometrium for the implantation of an embryo. NRP-1 expression might act as a co-factor for VEGF(165) enhancing the angiogenic stimulus.