Expression and function of galectins in the endometrium and at the human feto-maternal interface.

Galectins are classified as lectins that share structural similarities and bind ß-galactosides via a conserved carbohydrate recognition domain. So far 16 out of 19 identified galectins were shown to be present in humans and numerous studies revealed galectins as pivotal modulators of cell death, differentiation and growth. Galectins were highlighted to interact with both the adaptive and innate immune response. In the field of reproductive medicine and placenta research different roles for galectins have been proposed. Several galectins, being abundantly present at the human feto-maternal interphase and endometrium, were hypothesized to significantly contribute to endometrial receptivity and pregnancy physiology. Hence, this review outlines selected aspects of galectin action within endometrial function and at the feto-maternal interphase. Further current knowledge on galectins in reproductive and pregnancy disorders like endometriosis, abortion or preeclampsia is summarized.

The effect of CRH and its inhibitor, antalarmin, on in vitro growth of preantral mouse follicles, early embryo development, and steroidogenesis.

In vitro growth systems of preantral follicles allow studying the effect of various endocrine, paracrine, and autocrine factors on follicular growth and oocyte maturation. CRH is a 41-amino-acid neuropeptide responsible for endocrine, autonomic, immunological, and behavioral responses of mammals to stress and has two receptors, CRH receptor type 1 (CRH-R1) and CRH-R2. Antalarmin, a CRH-R1 antagonist, has been used to elucidate the role of CRH in stress, inflammation, and reproduction. The present study describes in vitro growth of mouse preantral follicles, early embryo development, and steroidogenesis in the presence of CRH and its antagonist antalarmin. We cultured 732 follicles in control media, 1306 in CRH 10(-7) mol/liter, and 1202 in CRH 10(-7) plus antalarmin 10(-6) mol/liter. The culture medium was assayed on alternate days for 17ß-estradiol, progesterone, and ß-human chorionic gonadotropin. Total RNA was extracted from preantral follicles as well as early preimplantation embryos and was assessed by real-time RT-PCR for the expression of CRH-R1 and CRH-R2 mRNAs. Hormone analysis showed that the CRH group had lower levels of 17ß-estradiol, progesterone, and ß-human chorionic gonadotropin as the culture progressed, in comparison with the other two groups. RT-PCR demonstrated the presence of CRH-R1 and CRH-R2 in all stages of preantral follicle culture. Morula/blastocyst-stage embryos expressed only CRH-R1. In conclusion, CRH has an inhibitory effect on in vitro fertilized oocytes, resulting from cultured preantral follicles at all stages of preimplantation embryo development. Furthermore, the presence of CRH in the culture medium inhibits steroidogenesis by preantral mouse follicles cultured in vitro.

Best practices of ASRM and ESHRE: a journey through reproductive medicine.

BACKGROUND: The American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) are the two largest societies in the world whose members comprise the major experts and professionals working in the field of reproductive medicine and embryology. These societies have never before had a joint scientific meeting. METHODS: A 3-day meeting was planned and took place in March of 2012. The goal was to present and debate key topics, as well as modes of practice in reproductive medicine and to discuss recent developments in the field. RESULTS: Presentations by members of ASRM and ESHRE were of three types: 'state of the art' lectures, 'back-to-back' presentations of two points of view and debates. CONCLUSIONS: For the first time, ASRM and ESHRE held a joint meeting where a special emphasis was given to presentations on the hottest topics in the field. Although different opinions and approaches sometimes exist on the two sides of the Atlantic, an appreciation and acceptance of these differences was evident, and there was more commonality than divergence of opinion.

Aberrant expression of corticotropin-releasing hormone in pre-eclampsia induces expression of FasL in maternal macrophages and extravillous trophoblast apoptosis.

Corticotropin-releasing hormone (CRH) and its receptors are expressed in human placenta. Recently, the impaired function of this system has been associated with a number of complications of pregnancy, including pre-eclampsia. The aim of the study was to test the hypothesis that CRH participates in the pathophysiology of pre-eclampsia through the induction of macrophage-mediated apoptosis of extravillous trophoblasts (EVTs). We found that the expression of CRH was increased in the EVT of the placental bed biopsy specimens from pre-eclamptic pregnancies (1.8-fold increase; P < 0.05). In addition, significantly larger numbers of apoptotic EVT were detected in pre-eclamptic placentas compared with normal ones (P < 0.05), and only in pre-eclamptic placentas, decidual macrophages were found to be Fas ligand (FasL)-positive. In vitro studies on the effect of CRH on human macrophages suggested that CRH induced the expression of the FasL protein in human macrophages and potentiated their ability to induce the apoptosis of a Fas-expressing EVT-based hybridoma cell line in co-cultures. These findings demonstrate a possible mechanism by which the aberrant expression of CRH in pre-eclampsia may activate the FasL-positive decidual macrophages, impair the physiological turnover of EVT and eventually disturb placentation.

Expression of cathepsin-D in primary breast cancer and corresponding local recurrence or metastasis: an immunohistochemical study.

BACKGROUND/AIM: The role of cathepsin-D is well established in breast cancer progression, being correlated with worse clinical outcomes. However, to our knowledge, no study has been performed investigating its expression in primary breast cancer tumors and their corresponding recurrences or metastasis. MATERIALS AND METHODS: Tissue sections from ten breast cancer cases and their corresponding local recurrences and six breast cancer cases and their corresponding metastases were immunohistochemically assessed for cathepsin-D reactivity. Cases diagnosed as either ductal carcinoma in situ (n=7), or breast carcinoma with no evidence of local recurrence or metastasis during follow-up (n=8) served as controls. RESULTS: Cathepsin-D was significantly up-regulated in all the study groups compared to controls. No difference was found between primary tumors and their corresponding recurrences or metastases. CONCLUSION: Cathepsin-D-expressing breast cancer cells seem to be involved in local recurrence or metastasis formation. Large series are needed to further verify this result with the aim of possible future molecular intervention.

Retinoid X receptor alpha (RXRα) and peroxisome proliferator-activated receptor gamma (PPARγ) expression in breast cancer: an immunohistochemical study.

BACKGROUND/AIM: The role of retinoid X receptor alpha (RXRα) and peroxisome proliferator-activated receptor gamma (PPARγ) in breast cancer has been well studied in vitro. The aim of the study was to assess the presence of these molecules in human breast cancer specimens and correlate them with major clinicopathological features. PATIENTS AND METHODS: Tissue sections from 82 breast cancer cases clustered according to histological grade, lymph node (LN) and hormone receptor (HR) status were assessed by immunohistochemistry for RXRα and PPARγ. RESULTS: RXRα was found to be strongly and moderately expressed in 11 (14.10%) and 33 (42.31%) cases, respectively. PPARγ was found to be strongly and moderately expressed in 33 (41.25%) and 25 (31.25%) cases, respectively. Only RXRα expression was inversely correlated with histological grade. Surprisingly, significantly elevated PPARγ expression was found in cases with positive LN status. Survival analysis did not yield significant results. CONCLUSION: Our data support the current thesis of RXRα being a potential target for feature molecular interventions.

Effects of phytoestrogen extracts isolated from flax on hormone production of trophoblast tumour cells Jeg 3 and BeWo.

UNLABELLED: AIM AND SETTING: To test the effects of crude extracts from flax (Linum usitatissimum) on progesterone and estradiol and ERα and ß/PR production in choriocarcinoma cell lines Jeg 3 and BeWo. Tumor trophoblast cells (Jeg 3 and BeWo) were incubated in the presence of different concentrations of the flax crude extracts. Estradiol and progesterone production was measured. Estrogen receptor α and ß as well as progesterone receptor expressions were also assessed. RESULTS: In Jeg 3 cells, progesterone production was downregulated by flax root and leaves extract, while in BeWo cells only flax root extract did manage to downregulate progesterone production. ERß expression was significantly downregulated by flax root and flax leaves extract in both cell lines; on the contrary, ERα expression was increased by flax leaves extract in BeWo cells. PR expression was downregulated by flax leaves extract in Jeg 3 and by flax root extract in BeWo cells. CONCLUSION: Flax extracts derived from leaves and especially from roots can modify progesterone and possibly estradiol production, while at the same time they seem to alter ERß expression. Further studies on animal models and adequately designed retrospective epidemiological studies are imperative to clarify this role upon progesterone.

The expression of receptivity markers in the fallopian tube epithelium.

Pinopodes represent the morphological and integrins, the biomolecular markers of endometrial receptivity. We studied using scanning electron microscopy, the expression of pinopodes on tubal samples and their corresponding endometria, from 21 women of reproductive age (7 from proliferative phase, 7 from day LH +5 and 7 from day LH +7). In addition, we examined the immunohistochemical staining of integrins alpha v beta 3, alpha v beta 5 and their ligands, fibronectin (FN) and osteopontin (OPN) in the same tubal epithelium samples. Pinopodes were detected on the tubal epithelium exclusively during day LH +7, coincident with their formation in the endometrium and synchronous to alpha v beta 3 sharp increase in the oviduct epithelium, suggesting a regulation similar to the endometrium. In contrast, alpha v beta 5, FN and OPN remained unchanged during the cycle. These results show for the first time the formation of pinopodes in the tubal epithelium at the time of endometrial receptivity and correlate it with the upregulation of the intact dimmer alpha v beta 3 in the tubes.

Abortion is associated with increased expression of FasL in decidual leukocytes and apoptosis of extravillous trophoblasts: a role for CRH and urocortin.

Human reproduction is remarkably inefficient, with more than half of spontaneous conceptions failing to complete the first trimester. However, little is known on the molecular events that take place at the implantation site during abortion. Here, we examined the hypothesis that the expression of the proapoptotic Fas/FasL system at the implantation site is impaired in abortions. We found that, in contrast to normal pregnancy, abortive deciduas contain leukocytes that are positive for FasL and extravillous trophoblasts (EVTs), which show increased expression of Fas and increased rates of apoptosis. In addition, the neuropeptides, corticotropin-releasing hormone and urocortin, were elevated in placental material obtained from abortions. In vitro, these peptides induced the expression of FasL in decidual lymphocytes (DL) obtained from elective termination of pregnancy placentas and thus potentiated the cells' ability to induce Fas-mediated apoptosis in an EVT-based hybridoma cell line. Finally, DL from abortion sites effectively induced apoptosis of EVT without prior treatment. It is possible that these events may impede successful early placentation and thus contribute to the pathophysiology of human abortion.

Intratumoral CRH modulates immuno-escape of ovarian cancer cells through FasL regulation.

Although corticotropin-releasing hormone (CRH) and Fas ligand (FasL) have been documented in ovarian carcinoma, a clear association with tumour progression and immuno-escape has not been established. FasL plays an important role in promoting tumour cells' ability to counterattack immune cells. Here, we examined immunohistochemically the expression of CRH, CRHR1, CRHR2 and FasL in 47 human ovarian cancer cases. The ovarian cancer cell lines OvCa3 and A2780 were further used to test the hypothesis that CRH might contribute to the immune privilege of ovarian tumours, by modulating FasL expression on the cancer cells. We found that CRH, CRHR1, CRHR2 and FasL were expressed in 68.1, 70.2, 63.8 and 63.8% of the cases respectively. Positivity for CRH or FasL expression was associated with higher tumour stage. Finally, CRH increased the expression of FasL in OvCa3 and A2780 cells through CRHR1 thereby potentiated their ability to induce apoptosis of activated peripheral blood lymphocytes. Corticotropin-releasing hormone produced by human ovarian cancer might favour survival and progression of the tumour by promoting its immune privilege. These findings support the hypothesis that CRHR1 antagonists could potentially be used against ovarian cancer.

The role of corticotropin-releasing hormone in blastocyst implantation and early fetal immunotolerance.

During blastocyst implantation, the maternal endometrial response to the invading semi-allograft has characteristics of an acute, aseptic inflammatory response. However, once implanted, the embryo suppresses this response and prevents rejection. Simultaneously, the mother's immune system prevents a graft VS. host reaction deriving from the fetal immune system. We have shown that embryonic trophoblast and maternal decidua cells, i.e., cells located in the interface between the fetal placenta and the maternal endometrium, produce corticotropin-releasing hormone (CRH) and express Fas ligand. CRH may play a crucial role in the implantation and the anti-rejection process that protects the fetus from the maternal immune system, primarily by killing activated T cells through the Fas-FasL interaction. In experimental animals, type 1 CRH receptor (CRH-R1) blockade by antalarmin, a specific type 1 CRH receptor antagonist, decreased implantation sites by approximately 70%. CRH is also involved in controlled trophoblast invasion, by downregulating the synthesis of the carcinoembryonic antigen-related cell adhesion molecule 1 by extravillous trophoblast cells. IN VITRO findings showed that CRH-R1 blockade by antalarmin increased trophoblast invasion by approximately 60%. Defective uterine CRH/CRH-R1 system during early pregnancy may be implicated in the pathophysiology of recurrent miscarriage, placenta accreta, and preeclampsia.

Expression of urocortin in the extravillous human trophoblast at the implantation site.

Urocortin (UCN) is a 40 amino acid peptide which is closely related to corticotropin-releasing hormone and binds with high affinity to both CRH type 1 and type 2 receptors. UCN is expressed in human reproductive tissues including endometrium, ovary, and placenta. This study was designed to investigate the cellular localization of UCN at the implantation site of the human blastocyst, as well as the regulation of the UCN promoter by two major intracellular signaling pathways, the cAMP/PKA and diacylglycerol/PKC pathways, in cells of placental origin. For this reason, immunohistochemistry was performed on tissue sections from paraffin-embedded human first trimester placentas and freshly isolated human invasive extravillous trophoblast cells (EVT) were analyzed for UCN expression using RT-PCR and immunofluorescence. Finally, UCN promoter activity was analyzed in the JEG3 human choriocarcinoma cell line. Immunohistochemistry revealed expression of UCN in the cytotrophoblast, the EVT and decidual cells. Both UCN mRNA and peptide were detectable in freshly isolated EVT. Finally, a human UCN promoter luciferase reporter construct transfected into JEG3 cells was significantly inducible by phorbol ester plus ionomycin, but not by phorbol ester alone or by forskolin. Collectively, the present study reports the expression of UCN in EVT and the activation of the UCN gene promoter by the diacylglycerol/PKC pathway. The functional significance of urocortin for the physiology of EVT requires further investigation.

Expression of inhibin/activin subunits alpha (-alpha), betaA (-betaA), and betaB (-betaB) in placental tissue of normal, preeclamptic, and HELLP pregnancies.

During human pregnancy the placenta produces a variety of proteins for the establishment of the fetoplacental unit, including inhibins and activins. Inhibins are dimeric glycoproteins, composed of an alpha-subunit and one of two possible beta-subunits (betaA or betaB). Aims of the present study were (a) the determination of the frequency and tissue distribution patterns of the inhibin/activin subunits in human placental tissue of normal pregnancies and pregnancies complicated with preeclampsia and HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) and (b) the assessment of a combined expression of inhibin-alpha- and both beta-subunits (betaA-and betaB-subunits) using double immunofluorescence technique. A significant lower expression of the inhibin-alpha subunit in preeclamptic and HELLP placental tissue compared to normal pregnancies was observed, while the inhibin-alpha immunostaining was significantly upregulated in syncytotrophoblast. Additionally, we demonstrated a significant down-regulation of inhibin-betaB subunit in extravillous trophoblast cells between normal and preeclamptic compared to HELLP placental tissue, while inhibin-betaA-subunit was significantly higher in preeclamptic syncytotrophoblast cells. A colocalization of inhibin-alpha and the beta-subunits could be demonstrated, suggesting a production and secretion of intact inhibin A and inhibin B. Therefore, inhibin A and activin A might be useful markers in preeclampsia. Valuable parameters in HELLP syndrome could be inhibin A, rather than inhibin B, and activin B. Furthermore, the lower betaB-subunit production in extravillous trophoblast cells demonstrates that this subunit might have an important role in the pathogenesis of HELLP syndrome. Additionally, the higher production of the betaA-subunit in syncytotrophoblast cells suggest a higher production of activin A rather than inhibin A in preeclampsia that might be utilized as a marker of placental function.

Expression of inhibin/activin subunits alpha (-alpha), beta A (-beta (A)) and beta B (-beta (B)) in placental tissue of normal and intrauterine growth restricted (IUGR) pregnancies.

During human pregnancy the placenta produces a variety of proteins like steroid hormones and their receptors that are responsible for the establishment and ongoing of the feto-placental unit. Inhibins are dimeric glycoproteins, composed of an alpha-subunit and one of two possible beta-subunits (beta (A) or beta (B)). Aims of the present study were the determination of the frequency and tissue distribution patterns of the inhibin/activin subunits in human placental tissue of normal pregnancies and pregnancies complicated with fetal growth restriction (IUGR). Slides of paraffin embedded placental tissue were obtained after delivery from patients diagnosed with IUGR (n = 6) and normal term placentas (n = 8). Tissue samples were fixed and incubated with monoclonal antibodies inhibin/activin-subunits -alpha, -beta (A), -beta (B). Intensity of immunohistochemical reaction on the slides was analysed using a semi-quantitative score and statistical analysis was performed (P<0.05). A significant lower expression of the inhibin-alpha subunit in IUGR extravillous trophoblast compared to normal pregnancies was observed, while the inhibin-alpha immunostaining was significantly upregulated in syncytiotrophoblast. Additionally, a significant down-regulation of inhibin-beta (B) subunit in extravillous trophoblast cells in IUGR syncytiotrophoblast cells was demonstrated. A co-localisation of inhibin-alpha and the beta-subunits was also observed, suggesting a production and secretion of intact inhibin A and inhibin B. Although the precise role of these inhibin/activin subunits in human placenta and IUGR pregnancies is still unclear, they could be involved in autocrine/paracrine signalling, contributing to several aspects like angiogenesis and tissue remodelling.

Endometrial and placental CRH as regulators of human embryo implantation.

Epithelial cells of the human endometrium and differentiated endometrial stromal cells express the corticotropin-releasing hormone (CRH) gene. CRH is also produced by human placental cytotrophoblast. Endometrial and placental CRH are under the endocrine control of gonadal steroids as well as under autocrine/paracrine regulation by prostanoids and interleukins. Human endometrium, myometrium and placenta express the relevant receptors. Human trophoblast and decidualized endometrial cells also express Fas ligand (FasL), a pro-apoptotic molecule. These findings suggest that intra-uterine CRH may participate in local inflammatory phenomena associated with blastocyst implantation, while FasL may assist with maternal immune tolerance to the semi-allograft embryo. A nonpeptidic CRH receptor type 1 (CRH-R1)-specific antagonist decreased the expression of FasL by human trophoblasts, suggesting that CRH regulates the pro-apoptotic potential of these cells in an auto-paracrine fashion. Invasive trophoblasts promoted apoptosis of activated Fas-expressing human T lymphocytes, an effect potentiated by CRH and inhibited by the CRH antagonist. Female rats treated with the CRH antagonist in the first 6 days of gestation had a dose-dependent decrease of endometrial implantation sites and live embryos as well as markedly diminished endometrial FasL expression. However, embryos of mothers lacking T cells (nude rats) and embryos of syngeneic matings were not rejected when mothers were treated with antalarmin, suggesting that the effect of antalarmin on embryonic implantation is not due to a nonspecific toxicity of this compound but a specific effect on T cells. Our data suggest important physiological roles of endometrial and placental CRH in the regulation of blastocyst implantation and early maternal tolerance.

Stress and the female reproductive system.

The hypothalamic-pituitary-adrenal (HPA) axis, when activated by stress, exerts an inhibitory effect on the female reproductive system. Corticotropin-releasing hormone (CRH) inhibits hypothalamic gonadotropin-releasing hormone (GnRH) secretion, and glucocorticoids inhibit pituitary luteinizing hormone and ovarian estrogen and progesterone secretion. These effects are responsible for the "hypothalamic" amenorrhea of stress, which is observed in anxiety and depression, malnutrition, eating disorders and chronic excessive exercise, and the hypogonadism of the Cushing syndrome. In addition, corticotropin-releasing hormone and its receptors have been identified in most female reproductive tissues, including the ovary, uterus, and placenta. Furthermore, corticotropin-releasing hormone is secreted in peripheral inflammatory sites where it exerts inflammatory actions. Reproductive corticotropin-releasing hormone is regulating reproductive functions with an inflammatory component, such as ovulation, luteolysis, decidualization, implantation, and early maternal tolerance. Placental CRH participates in the physiology of pregnancy and the onset of labor. Circulating placental CRH is responsible for the physiologic hypercortisolism of the latter half of pregnancy. Postpartum, this hypercortisolism is followed by a transient adrenal suppression, which may explain the blues/depression and increased autoimmune phenomena observed during this period.

Expression of Wilms' tumor suppressor gene (WT1) in human endometrium: regulation through decidual differentiation.

The Wilms' tumor suppressor gene (WT1) encodes a zinc-finger containing transcription factor that is selectively expressed in the developing urogenital tract and functions as a tissue-specific developmental regulator. In addition to its gene-regulatory function through DNA binding properties, WT-1 also regulates transcription by formation of protein-protein complexes. These properties place WT-1 as a major regulator of cell growth and differentiation. In view of these observations, we studied WT1 mRNA and protein in human endometrial extracts and in endometrial stromal cells (ESCs) differentiating into decidual cells in vitro, by RT-PCR and Western blotting, respectively. WT1 protein expression was also studied in situ in the proliferative and the secretory phase of the menstrual cycle in the early pregnant state. Analysis by PCR of total RNA prepared from human ESCs demonstrated the presence of WT1 mRNA and four WT1 mRNA splice variants. Western blot analysis of nuclear protein extracts from ESCs yielded one immunoreactive protein of the expected size (approximately 52-54 kDa) recognized by the WT1 antibody. Immunohistochemical staining showed that WT1 protein is localized only to nuclei of human endometrial stromal cells. It remains constant in the proliferative and the secretory phase of the menstrual cycle and is increased remarkably during decidualization in early pregnancy. ESCs decidualized in vitro were investigated for WT-1 expression, which confirmed that decidualizing stimuli (E2, medroxy-progesterone-acetate, and relaxin for 12 d or cAMP and progesterone for 1-4 d) induced WT-1 mRNA (P < 0.05) and increased protein levels (P < 0.05). These data indicate that in humans the WT1 gene is expressed in ESCs and its mRNA and protein levels remain constant in the proliferative and the secretory phase of the menstrual cycle and that WT1 mRNA and protein expression increases significantly in ESCs when these cells differentiate into decidual cells.

Corticotropin-releasing hormone promotes blastocyst implantation and early maternal tolerance.

The semi-allograft embryo in the blastocyst stage implants itself in the endometrium, yet no immune rejection processes are activated. Embryonic trophoblast and maternal decidua produce corticotropin-releasing hormone (CRH) and express Fas ligand (FasL), a proapoptotic cytokine. We found that antalarmin, a CRH receptor type 1 antagonist, decreased FasL expression and promoted apoptosis of activated T lymphocytes, an effect which was potentiated by CRH and inhibited by antalarmin. Female rats treated with antalarmin showed a marked decrease in implantation sites and live embryos and diminished endometrial FasL expression. Embryos from mothers that lacked T cells or from syngeneic matings were not rejected when the mothers were given antalarmin. These findings suggested that locally produced CRH promotes implantation and maintenance of early pregnancy primarily by killing activated T cells.

The Fas/FasL apoptotic pathway is involved in kappa-opioid-induced apoptosis of human endometrial stromal cells.

Human endometrium expresses specific kappa-opioid binding sites and their endogenous ligands, the dynorphins. In neural crest-derived tissues, kappa-opioids affect apoptosis, a phenomenon of major significance in endometrial stroma physiology. Our hypothesis was that endometrial kappa-opioids may play a role in endometrial stromal cell apoptosis. Thus, we examined the effect of the synthetic kappa-opioid agonist, U69593, on the apoptotic rate of human endometrial stromal cells in primary culture. Apoptosis of endometrial stromal cells was elevated after 3 h exposure to 100 nmol/l U69593, and remained elevated for up to 3 days. This effect was dose-dependent and was reversed by the general opioid antagonist, naloxone, suggesting that it is mediated via opioid receptors. In parallel, semi-quantitative Western blot and flow cytometry analysis showed that U69593 caused a rapid but transient up-regulation of Fas protein, suggesting that its effect on apoptosis is mediated by activation of the Fas/FasL apoptotic pathway. Additionally, U69593 increased the content of the anti-apoptotic members of the Bcl-2 family of proteins, the Bcl-2 and Bcl-x(L), whereas it had no significant effect on the apoptosis-promoting homologues Bax, Bcl-x(S) and Bak. This implies that a transient survival mechanism is activated in stromal cells as a parallel rescue response to the apoptosis-inducing factor. In conclusion, our data suggest that endometrial opioid dynorphins may participate in the apoptotic processes related to endometrial tissue remodelling during early pregnancy or menstruation.

Endometrial and myometrial corticotropin-releasing hormone (CRH): its regulation and possible roles.

In human endometrium, both epithelial and stroma cells produce corticotropin-releasing hormone (CRH). Both types of cells also possess specific CRH-binding sites indicating a local effect of endometrial CRH. The transcription of the CRH gene in human endometrium is under the control of steroid hormones and locally produced prostanoids and interleukins. Endometrial CRH interacts with locally produced prostaglandins and interleukins. Based on these observations it can be hypothesized that CRH, prostaglandins and interleukins form a network responsible for the communication between epithelial and stromal cells, at the level of the endometrium, and between endometrial and myometrial cells at the level of uterus. The net product of these interaction is the micro-regulation of the decidualizing process and the preparation of endometrium for the implantation/nidation of the conceptus. Indeed, this network may represent the core of the intrauterine neuroendocrine-immune interactions involved in the decidualization of stroma and implantation of blastocyst. In addition, this network appears to be essential for the fine-tuning of myometrial tone.