Longitudinal assessment of spiral artery and intravillous arteriole blood flow and adverse pregnancy outcome.

OBJECTIVE: Superb microvascular imaging (SMI) has been shown to improve visualization of small vessels by suppressing global motions while preserving low-flow components, such as the microvessels in the placenta. We sought to determine if SMI-aided visualization of flow velocity waveforms in the spiral arteries (SA) and intravillous fetal arterioles (IVA) could predict fetal growth restriction (FGR), gestational hypertension (GH) and/or pre-eclampsia (PE). METHODS: This was a prospective longitudinal study of singleton pregnancies without fetal anomaly, receiving prenatal care in one of two medical centers over a 5-year period. Using SMI-aided color Doppler, SA and IVA flow velocity was measured at three timepoints: 11 + 0 to 14 + 0, 18 + 0 to 22 + 6 and 28 + 0 to 34 + 6 weeks of gestation. SA and IVA flow velocity waveforms were reported as resistance indices (RI). RI values were analyzed using multilevel modeling; individual regression curves were estimated and combined to obtain the reference intervals for SA-RI and IVA-RI in uncomplicated pregnancies. The primary clinical outcome was FGR and secondary outcomes were PE and GH. FGR was defined as estimated fetal weight < 10th percentile. Student's t-test was used to compare deviation from expected RI between normal and complicated pregnancies. RESULTS: Among 540 pregnancies included in the analysis, 18 (3.3%) had FGR, 31 (5.7%) PE and 61 (11.3%) GH. In uncomplicated pregnancies, the SA-RI decreased progressively with advancing gestation, whereas the IVA-RI increased with gestational age. In the third trimester, the mean SA-RI and IVA-RI values were significantly higher in the FGR group compared with pregnancies that did not develop FGR, while the mean SA-RI was significantly higher in PE compared with non-PE pregnancies. There was no significant difference in mean SA-RI or IVA-RI between pregnancies with vs those without GH at any gestational age. When all three adverse outcomes were combined, SA-RI was significantly higher in pregnancies with these outcomes when compared to uncomplicated pregnancies in the third trimester (mean ± SD, 0.29 ± 0.12 vs 0.26 ± 0.12; P = 0.02). In screening for FGR using SA-RI, the areas under the receiver-operating-characteristics curves (AUC) were 0.68, 0.73 and 0.73 in the first, second and third trimesters, respectively. The respective AUCs for IVA-RI were 0.72, 0.72 and 0.73 for each trimester. CONCLUSIONS: SA-RI and IVA-RI, measured using SMI technology, were significantly higher in pregnancies at risk for FGR in late gestation. Larger studies are needed to determine if SA and IVA flow are reliable predictors of adverse pregnancy outcome. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Long-acting progestin-only contraceptives enhance human endometrial stromal cell expressed neuronal pentraxin-1 and reactive oxygen species to promote endothelial cell apoptosis.

CONTEXT: Despite the absence of progesterone receptor protein in human endometrial endothelial cells (HEECs), endometria of women receiving long-acting progestin-only contraceptives (LAPCs) display reduced uterine blood flow, elevated reactive oxygen species generation, increased angiogenesis, and irregularly distributed, enlarged, fragile microvessels resulting in abnormal uterine bleeding. OBJECTIVE: We propose that paracrine factors from LAPC-treated human endometrial stromal cells (HESCs) impair HEEC functions by shifting the balance between HEEC viability and death in favor of the latter. DESIGN AND SETTING: Proliferation, apoptosis, and transcriptome analyses were performed in HEECs treated with conditioned medium supernatant (CMS) derived from HESCs treated with estradiol (E2) ± medroxyprogesterone acetate or etonogestrel under normoxia or hypoxia. Mass spectrometry interrogated the CMS secretome while immunostaining for neuronal pentraxin-1 (NPTX1), cleaved caspase-3, and cytochrome c was performed in cultured HEECs and paired endometria from women using LAPCs. MAIN OUTCOME: HEEC apoptosis and its underlying mechanism. RESULTS: HESC CMS from E2 + medroxyprogesterone acetate or E2 + etonogestrel incubations under hypoxia induced HEEC apoptosis (P < .05), whereas mass spectrometry of the CMS revealed increased NPTX1 secretion (P < .05). Endothelial cleaved caspase-3 and stromal NPTX1 immunoreactivity were significantly higher in LAPC-treated endometria (P < .001). Transcriptomics revealed AKT signaling inhibition and mitochondrial dysfunction in HEECs incubated with HESC CMS. In vitro analyses proved that CMS decreased HEEC AKT phosphorylation (P < .05) and that recombinant NPTX1 (P < .05) or NPTX1 + H2O2 (P < .001) increase HEEC apoptosis and cytosolic cytochrome c levels. CONCLUSIONS: LAPC-enhanced NPTX1 secretion and reactive oxygen species generation in HESCs impair HEEC survival resulting in a loss in vascular integrity, demonstrating a novel paracrine mechanism to explain LAPC-induced abnormal uterine bleeding.

The role of phosphatase and tensin homolog in drug-induced gingival overgrowth.

BACKGROUND AND OBJECTIVE: We proposed that phosphatase and tensin homolog (PTEN) might be one of the signaling proteins that alter the balance between cell growth and cell death in drug-induced gingival overgrowth. The aim of this study was to investigate the expression of PTEN in subjects using cyclosporine A and to analyze the relationship between PTEN and cell proliferation marker, proliferating cell nuclear antigen (PCNA), in cyclosporine A-induced gingival overgrowth. MATERIAL AND METHODS: In total, samples from 36 subjects, i.e. 24 cyclosporine A-mediated renal transplant patients with gingival overgrowth (n = 12) or without gingival overgrowth (n = 12) and 12 matched periodontally healthy subjects, were included in the study. PTEN and PCNA expressions in gingival tissues were analyzed using immunohistochemistry, PTEN expression was also analyzed by western blot. PTEN immunoreactivity was calculated with a histologic score (HSCORE) value and PCNA immunoreactivity was calculated with the PCNA-proliferative index. RESULTS: Phosphatase and tensin homolog HSCORE for the group with gingival overgrowth was found to be significantly lowest compared to the group without gingival overgrowth and the control group (p < 0.001) while the highest PTEN HSCORE was found in the control group. In addition, the PTEN HSCORE for the group without gingival overgrowth was significantly lower compared to controls (p < 0.001). The highest PCNA-proliferative index score was observed in the group with gingival overgrowth while the lowest score was observed in the control group (p < 0.001). The immunoblot signal for PTEN was significantly decreased in the group with gingival overgrowth compared to the group without gingival overgrowth and the control group (p < 0.001). Western blot results were different from immunohistochemistry and revealed there was no significant difference between the without gingival overgrowth and the control group (p > 0.05). CONCLUSION: Our results showing decreased PTEN levels in patients with gingival overgrowth supported with increased PCNA expression suggested that PTEN might take part in the imbalance between cell proliferation and death in drug-induced gingival overgrowth.

Fresh transfer outcome predicts the success of a subsequent frozen transfer utilizing blastocysts of the same cohort.

The objective of this retrospective analysis was to assess whether the outcomes of fresh blastocyst transfer cycles are predictive of the chances for pregnancy and live birth in subsequent frozen blastocyst transfer cycles using sibling embryos from the same retrieval. Clinical pregnancy rate (CPR) and live birth rate (LBR) per fresh and frozen blastocyst transfer were assessed. All subgroups had similar patient and cycle characteristics. Overall, CPR and LBR in fresh cycles were 44% and 29%, and in frozen were 34% and 30%, respectively. However, the CPR and LBR in frozen cycles were significantly higher in patients who were not pregnant with their fresh cycles (CPR 43% versus 22%, P=0.01; and LBR 36% versus 17%, P=0.03, respectively). When fresh cycles are unsuccessful, the remaining frozen blastocysts of the same cohort have the same chance of success in producing a clinical pregnancy as the fresh cycle (43% versus 44%). Frozen cycles following successful fresh cycles have significantly lower CPR and LBR. These data reinforce the concept that only a few embryos per cohort are competent for a live birth. During IVF cycles, many patients are fortunate enough to have excess high-quality embryos remaining after their embryo transfer. These embryos can be frozen, or cryopreserved, for later transfer. The transfer of cryopreserved embryos increases the cumulative success rates after a single IVF stimulation. Many studies have examined success rates such as clinical pregnancy rate and live birth rate in frozen embryo transfer cycles. While these frozen embryo transfer cycles have excellent success rates, they are significantly lower than success rates in cycles where a "fresh", non-frozen, embryo is transferred. Few studies have carefully examined the impact of the result of the fresh embryo transfer (whether the patient became pregnant or not) on subsequent frozen embryo transfer success. Here we show that women who are not pregnant after a fresh embryo transfer have higher success rates in subsequent frozen embryo transfer cycles that use frozen embryos generated during a single IVF cycle. In these women (not pregnant after a fresh embryo transfer), frozen embryo transfer pregnancy rates are the same as rates using fresh embryos.

The c-Abl expression in uterine epithelium during the mouse estrus cycle.

The epithelial cells of the mouse endometrium comprises the recurring physiologic changes such as proliferation and apoptosis induced by the reproductive hormones throughout the estrus cycle. The c-Abl is a protein tyrosine kinase, localized in the different cellular compartments such as nucleus, cytoplasm, mitochondria, and endoplasmic reticulum, interacts with different cellular proteins, including signaling adaptors, kinases, phosphatases, cell-cycle regulators, transcription factors and cytoskeletal proteins. Our hypothesis is that the c-Abl expression in the mouse uterine epithelium shows cyclic changes during the estrus cycle that is involved in regulation of the endometrial epithelial cells. The regulation of c-Abl gene and protein expression in the uterus of intact animals in the different cycle phases was investigated using immunohistochemistry, western blot and semi-quantitative RT-PCR. The immunohistochemistry results revealed that the luminal and the glandular epithelium (LE) and (GE), respectively, showed gradually increase in the expression of c-Abl from the proestrus (P) to the metestrus and followed by a decrease in the diestrus (D). c-Abl immunoreactivity was detected in the both LE and GE cells, especially the LE showed diminished the c-Abl protein expression on the D phase and the minimal value was detected on the P day. The c-Abl protein level in the LE was increased during the M, presenting a high correlation with the hormonal level of this cell type. The result of c-Abl RT-PCR analysis was compatible with pattern of c-Abl protein expression. In conclusion, the stage-specific protein pattern of the mammalian c-Abl tyrosine kinase presented a good correlation with the mouse estrus cycle and may have a regulative function during the uterine remodeling.

Human labor is associated with reduced decidual cell expression of progesterone, but not glucocorticoid, receptors.

CONTEXT: Unchanging plasma progesterone (P4) levels suggest that human labor is initiated by reduced P4 receptor (PR) expression, which elicits functional P4 withdrawal. The glucocorticoid receptor (GR) is also implicated in this process. OBJECTIVE: Our objective was to compare PR and GR staining in human decidual cells (DCs) and interstitial trophoblasts (ITs) of gestational age-matched pre- and postcontraction specimens and to evaluate steroid effects on PR and GR expression in human DC cultures. INTERVENTIONS AND MAIN OUTCOME MEASURES: Decidua basalis and parietalis sections were immunostained for PR or GR and then for the cytoplasmic DC and IT markers vimentin and cytokeratin. Western blotting measured PR and GR levels in nuclear extracts of cultured leukocyte-free term DCs after incubation with estradiol-17beta (E2) with or without medroxyprogesterone acetate (MPA). RESULTS: PR histological scores (HSCOREs) were significantly higher in DC nuclei from pre- vs. post-uterine-contraction decidua basalis and parietalis sections with PR immunostaining absent from ITs. In contrast, immunoreactive GR was localized in IT and DC nuclei. GR HSCORES were significantly higher in ITs than DCs but similar in pre- vs. post-uterine-contraction specimens. In term DC monolayers, PR-A and PR-B were enhanced by E2 and inhibited by MPA, whereas E2 plus MPA produced intermediate PR expression. The GR was constitutively expressed. CONCLUSIONS: In post- vs. pre-uterine-contraction specimens, significantly lower HSCOREs in DC nuclei, but not IT, and unchanging GR levels in DCs and ITs suggest that functional P4 withdrawal may occur in DCs and is unlikely to involve the GR. Nuclear extracts from DC monolayer cultures express steroid-regulated PR-A and PR-B and constitutive GR.

Involvement of human decidual cell-expressed tissue factor in uterine hemostasis and abruption.

Vascular injury increases access and binding of plasma-derived factor VII to perivascular cell membrane-bound tissue factor (TF). The resulting TF/VIIa complex promotes hemostasis by cleaving pro-thrombin to thrombin leading to the fibrin clot. In human pregnancy, decidual cell-expressed TF prevents decidual hemorrhage (abruption). During placentation, trophoblasts remodel decidual spiral arteries into high conductance vessels. Shallow trophoblast invasion impedes decidual vascular conversion, producing an inadequate uteroplacental blood flow that elicits abruption-related placental ischemia. Thrombin induces several biological effects via cell surface protease activated receptors. In first trimester human DCs thrombin increases synthesis of sFlt-1, which elicits placental ischemia by impeding angiogenesis-related decidual vascular remodeling. During pregnacy, the fibrillar collagen-rich amnion and choriodecidua extracellular matrix (ECM) provides greater than additive tensile strength and structural integrity. Thrombin acts as an autocrine/paracrine mediator that degrades these ECMs by augmenting decidual cell expression of: 1) matrix metalloproteinases and 2) interleukin-8, a key mediator of abruption-associated decidual infiltration of neutrophils, which express several ECM degrading proteases. Among the cell types at the maternal fetal interface at term, TF expression is highest in decidual cells indicating that this TF meets the hemostatic demands of labor and delivery. TF expression in cultured term decidual cells is enhanced by progestin and thrombin suggesting that the maintenance of elevated circulating progesterone provides hemostatic protection and that abruption-generated thrombin acts in an autocrine/paracrine fashion on decidual cells to promote hemostasis via enhanced TF expression.

Progestin and thrombin regulate tissue factor expression in human term decidual cells.

CONTEXT: Perivascular cell membrane-bound tissue factor (TF) initiates hemostasis via thrombin generation. The identity and potential regulation of TF-expressing cells at the human maternal-fetal interface that confers hemostatic protection during normal and preterm delivery is unclear. OBJECTIVES: The objective of the study were to identify TF-expressing cells at the maternal-fetal interface in term and preterm decidual sections by immunohistochemistry and evaluate progestin, thrombin, TNF-alpha, and IL-1beta effects on TF expression by cultured human term decidual cells (DCs). INTERVENTIONS AND MAIN OUTCOME MEASURES: Serial placental sections were immunostained for TF. Leukocyte-free term DC monolayers were incubated with 10(-8) M estradiol (E2) or E2 plus 10(-7) M medroxyprogestrone acetate (MPA) +/- thrombin or TNF-alpha or IL-1beta. ELISA and Western blotting assessed TF in cell lysates. Quantitative real-time RT-PCR measured TF mRNA levels. RESULTS: Immunolocalized TF in DC membranes in preterm and term placental sections displayed higher Histologic Scores than villous mesenchymal cells (P < 0.05). TF was undetected in interstitial or extravillous trophoblasts. Compared with DCs incubated with E2, MPA and 2.5 U/ml thrombin each doubled TF levels (P < 0.05) and E2 + MPA + thrombin further doubled TF levels (P < 0.05), whereas TNF-alpha and IL-1beta were ineffective. Western blotting confirmed the ELISA results. Quantitative RT-PCR revealed corresponding changes in TF mRNA levels. CONCLUSIONS: In human term placental sections, DC-expressed TF exceeds that of other cell types at the maternal-fetal interface and is localized at the cell membranes in which it can bind to factor VII and meet the hemostatic demands of labor and delivery via thrombin formation. Unlike the general concept that TF is constitutive in cells that highly express it, MPA and thrombin significantly enhanced TF expression in term DC monolayers.

Plasma levels of nitrites, PGF1alpha, and nitrotyrosine in LPS-treated rats: functional and histochemical implications in aorta.

We investigated the effects of lipopolysaccharide (LPS) administration on plasma nitrite, nitrotyrosine and 6-keto prostaglandin F1alpha, (PGF1alpha) levels and the related resultant changes in function and histochemistry of aorta in rats. Plasma nitrite and PGF1alpha nitrotyrosine levels were analysed after 5 mg/kg intravenous LPS was administered to rats compared with those in non-treated rats. The distribution of nitrotyrosine in the aorta was studied immunohistochemically. The contractile responses of aortic rings to phenylephrine (PE) from both the LPS-treated and control rats were studied in the organ baths. There were increases in plasma nitrite, PGF1alpha, and nitrotyrosine concentrations of LPS-treated rats compared to non-treated rats. Immunoreactivity of nitrotyrosine residues were detected in the endothelial and smooth muscle cells in LPS-treated but not in control rat aorta. The contractile responses to PE of the LPS-treated rat aortic rings were significantly reduced as compared with those of control rat's. Incubation of the aortic rings from LPS-treated rats with cyclooxygenase inhibitor indomethacine or with a combination of indomethacine and nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) increased the contractile responses to the levels observed in control rats suggesting that both prostanoids and particularly nitric oxide (NO) are involved in the reduced contractile responses in LPS-treated rats. These results supported the view that LPS might cause an increment in both NO and PGI2 levels. This increase in the NO and PGI2 levels may be responsible from the reduction in responses of aorta to contractile agents in LPS-treated rats. Increased peroxynitrite formation in LPS-treated rats may lead to nitration of the tyrosil residues of the proteins in the aorta.

Spatial and temporal distribution of Tie-1 and Tie-2 during very early development of the human placenta.

Vasculogenesis in the human placenta comprises differentiation and growth of newly forming blood vessels derived from hemangiogenic stem cells within the mesenchymal core of villi. In a second stage, angiogenesis leads to the expansion and remodeling of the already existing vessels. At present, relatively little is known about the regulatory mechanisms of vasculogenesis and angiogenesis during very early placentation. Using placental villous tissues from days 22 to 48 of pregnancy, we analyzed the spatial and temporal expression of Tie-1 and Tie-2 in parallel to vascular maturation in the human placenta. In immunohistochemistry both receptors, Tie-1 and Tie-2 show a cell and villous type specific expression during this early phase of placental development. Especially, cytotrophoblast and hemangiogenic cell cords in mesenchymal villi and Hofbauer cells in immature intermediate villi have the strongest immunoreactivities. Western blot analysis showed that no significant changes were detected for Tie-1 and Tie-2 as pregnancy advanced. Moreover, phospho-Tie-2 levels did not change significantly in parallel to pregnancy ages. We conclude that both receptors are involved in angiogenesis as well as vascular modulation of early vessels. Due to their spatial distribution we speculate on an additional role in regulation of villous and extravillous trophoblastic behavior.

Sequential steps during vasculogenesis and angiogenesis in the very early human placenta.

Development of blood vessels takes place via two subsequent processes, vasculogenesis and angiogenesis. During vasculogenesis, formation of first blood vessels is achieved by differentiation of hemangiogenic stem cells from pluripotent mesenchymal cells, while during angiogenesis new blood vessels form from already existing vessels. The combination of our data with those from the literature leads us to depict the chronological steps of cell differentiation in the mesenchymal core of placental villi during vasculogenesis and angiogenesis. This current opinion will focus on the temporal and spatial expression of VEGF and its receptors VEGFR-1 and VEGFR-2, and the angiopoietin receptors Tie-1 and Tie-2 in parallel to vascular maturation in human placental villi during very early stages of placental development. There is evidence that the interplay of a variety of growth factors secreted from different cell types during development is needed to trigger as well as maintain placental vasculogenesis and angiogenesis.

Differential expression of VASP in normal lung tissue and lung adenocarcinomas.

BACKGROUND: Vasodilator stimulated phosphoprotein (VASP) is associated with focal adhesions and is thought to have an important role in actin filament assembly and cell motility. We hypothesise that an increase in the expression of VASP is involved in the progression and invasion of lung adenocarcinomas in parallel to tumour progression. A study was undertaken to analyse VASP expression in normal lung tissue and lung adenocarcinomas. METHODS: Human lung tissues with adenocarcinomas (n = 26) were used. Normal lung tissue specimens (n = 14) were taken from areas a standard distance (3 cm) from resected adenocarcinomas of patients who underwent surgical lung resection. Adenocarcinomas were classified according to pathological staging and histopathological grades. Tissues were stained for VASP using immunohistochemistry. RESULTS: Normal lung pneumocytes showed no VASP expression while alveolar macrophages had the strongest immunoreactivity for VASP. Bronchial epithelium (surface epithelium, goblet cells) and bronchial gland cells had a very weak immunoreactivity for VASP. Adenocarcinomas had significantly greater VASP expression than normal epithelium (p < 0.001). Moreover, VASP expression in adenocarcinomas increased significantly with more advanced tumour stage (p < 0.001). CONCLUSIONS: The spatial and differential expression of VASP in normal lung tissue and lung adenocarcinomas suggests that it is likely to be involved in the differentiation of normal lung cells to adenocarcinomas. The significant increase in the expression of VASP in adenocarcinomas in parallel to pathological staging suggests that it may regulate the invasive behaviour of lung adenocarcinomas as adenocarcinoma invasion is increased in more advanced tumours.

Sequential expression of VEGF and its receptors in human placental villi during very early pregnancy: differences between placental vasculogenesis and angiogenesis.

Vascularization within the human placenta is the result of the de novo formation of vessels derived from pluripotent precursor cells in the mesenchymal core of the villi. Vascularization of placental villi starts at around day 21 post conception (p.c.) with a four somite embryo. At this stage progenitors of haemangiogenic cells differentiate to form first vessels. These progenitor cells are thought to be directly derived from mesenchymal cells rather than originating from fetal blood cells. We investigated the relation between differentiation of stromal cells towards endothelial cells and vascular structures and the expression pattern of the respective growth factors. Using transmission electron microscopy and immunohistochemistry (for VEGF, Flt-1, Flk-1, CD14, CD34, and CD68) the development of placental vasculogenesis during very early stages of pregnancy (days 22-48 p.c.) was studied. We found that VEGF is strongly expressed in villous cytotrophoblast cells and subsequently in Hofbauer cells while its receptors Flt-1 and Flk-1 are found on vasculogenic and angiogenic precursor cells. The developmental expression and secretion of VEGF suggests its involvement in recruitment, maintenance and formation of first angiogenic cells and vessels. Interactions between VEGF and Flk-1 and Flt-1 may regulate placental vasculogenesis and angiogenesis in a paracrine and autocrine manner. The sequential expression of growth factors in different cell types may point to the fact that placental vasculogenesis and angiogenesis are clearly distinct events.

Regulation of Fas ligand expression by vascular endothelial growth factor in endometrial stromal cells in vitro.

When Fas ligand (FasL) interacts with the Fas receptor, it induces apoptosis through autocrine and/or paracrine signalling. Vascular endothelial growth factor (VEGF) is a potent mitogenic cytokine. VEGF plays a role during remodelling of the endometrium following menstruation. We hypothesized that, by regulating FasL expression, VEGF may play a role in endometrial stromal cell survival by decreasing autocrine apoptotic signalling. We aimed to determine the expression of FasL in cultured endometrial stromal cells and its modulation by VEGF. VEGF induced a decrease in both FasL-positive cell number and FasL intensity as determined by immunocytochemistry and western blot respectively (P < 0.05). These effects of VEGF were observed in a concentration-dependent manner (10-42%; P < 0.05). Anti-VEGF neutralizing antibody alone resulted in an increase in the FasL expression. When combined with VEGF, anti-VEGF reversed the VEGF-induced decrease in FasL level up to 100% (P < 0.05). In addition, western blot analysis showed that FasL expression in endometrial stromal cells demonstrated a cyclic change every 12 h during 48 h of incubation. These results suggest that down-regulation of FasL by VEGF may affect endometrial stromal cell survival in an autocrine or paracrine manner. The decrease in FasL level may be due to a stimulation of its degradation. Our results show that FasL in endometrial stromal cells in culture has a cyclic expression model, suggesting that there may be a regulation at the translation level.

Endocrine-immune interactions in human endometrium.

The immune system is a complex entity designed to eliminate foreign intruding antigens and is influenced by and, in turn, influences the function of the reproductive system. Despite the widespread associations between immunology and reproductive medicine, the study of system interactions remains in its infancy. Many diverse facts are accumulating, and pieces of the puzzle are becoming available to provide a clearer picture. In this review article, we focus on the interactions between endocrine and immune systems in the human endometrium. Understanding the molecular pathways in endocrine-immune interactions in the human endometrium is crucial to understand events such as menstrual bleeding, tissue repair and regeneration, inflammation, angiogenesis, blastocyst implantation, and progression of pregnancy. These events require a balanced regulation of endometrial differentiation, proliferation, cell survival, leukocyte recruitment, apoptosis, and angiogenesis by sex steroids. In this review, we first outline the role of survival factors such as phosphoinositol 3-kinase/protein kinase B, PTEN, NFkappaB, and apoptotic molecules (Fas-FasL, Bcl-2). We then discuss their regulation by estrogen and progesterone in the endometrium. We present evidence for direct and/or indirect roles of steroid hormones on the expression of chemotactic cytokines (interleukin-8 and monocyte chemotactic protein-1) and on the survival versus apoptosis of resident endometrial cells (stromal, epithelial, and endothelial cells) and nonresident cells (leukocytes).

Expression of insulin, insulin-like growth factor I and glucocorticoid receptor in rat uterus and embryo during decidualization, implantation and organogenesis.

The significance of insulin, insulin-like growth factor I (IGF-I) and glucocorticoids to the early mammalian embryo is clear in that they are key regulators of both mitogenic and metabolic effects during development. In the present study, the temporal sequence of expression of the respective receptor proteins was investigated for the first time in the developing rat utero-embryonic unit between conception and day 12 of gestation using immunocytochemistry. Insulin, IGF-I and glucocorticoid receptor were expressed in embryonic tissues after the start of implantation, and were co-localized in the primary ectoderm, extraembryonic ectoderm as well as in the ectoplacental cone. The parietal endoderm was devoid of glucocorticoid receptor staining, whereas IGF-I receptor was absent in visceral endoderm. After completion of basic organogenesis, the neural tube, notochord, otic placode, Wolffian duct, mesonephros and intestinal tube expressed insulin, IGF-I and glucocorticoid receptor. The glucocorticoid receptor was not expressed in heart tube and dorsal aortae. Considerable amounts of insulin receptor were detected in trophoblast-derived giant cells. In the uterus, luminal epithelium, endometrial stromal and myometrial smooth muscle cells immunoreacted with antisera against insulin, IGF-I and glucocorticoid receptor. Endometrial glands remained negative for the glucocorticoid receptor throughout the gestational period investigated. Uterine hormone receptor expression reached a peak at days 4 and 5 of gestation in endometrial stromal cells and decidua, respectively. In conclusion, the demonstrated ontogenetic pattern of insulin, IGF-I and glucocorticoid receptor expression indicates the potential sites of biological action of the respective ligands, providing supportive evidence for their critical importance during the course of embryogenesis in rats.

Structural differentiation of human uterine luminal and glandular epithelium during early pregnancy: an ultrastructural and immunohistochemical study.

The differentiation of human endometrial epithelium is a dynamic event that occurs throughout the menstrual cycle and early pregnancy. The structural transformation and differentiation of human uterine luminal and glandular epithelium of early human pregnancy (n=14) was investigated ultrastructurally and immunohistochemically using antibodies against cytokeratin (CT), endothelial marker CD31, Fas, and proliferating cell nuclear antigen (PCNA). Ultrastructurally, luminal epithelial cells showed distinctive euchromatic nuclei with prominent nucleoli and relatively loose cell membranes in all poles (apical to basal). Subcellular components were easily recognized in luminal epithelium except in degenerating cells. Mainly two cell types, dark and clear cells, formed the glandular epithelium. In the early gestation period, microvilli were abundant on the apical and apico-lateral poles of these cells. Only a few cytoplasmic projections were observed in dark cells. Numerous cilia were observed on the apical pole of some clear cells, located at the adluminal segment. In contrast, dark cells lacked cilia, nuclear channels, or giant mitochondrial profiles. Glycogen synthesis and apocrine secretion were recognizable for several days during early gestation. The apocrine secretory activity differed among dark cells of the glandular epithelium. The immunoreactivity of PCNA and Fas, and ultrastructural observations in the glandular epithelium suggest that, even in different segments of the same gland, epithelial cells do not regress during early gestation, but proliferate, perhaps representing a resistance against trophoblastic invasion. These morphological and molecular changes suggest that both luminal and glandular epithelium may play an important role in cellular defense and limitation for trophoblastic invasion during early pregnancy since plasma membrane alterations of the surface epithelium take place at the apical, basal and lateral poles compared to early secretory phase endometrial cells. Besides glandular epithelium may be consequently responsible for uterine secretions, which may be critical for early embryo development.

Regulation of Fas ligand expression by estradiol and progesterone in human endometrium.

Implantation involves a complex set of events, including apoptosis in endometrial cells. Apoptosis in human endometrium coincides with the implantation window, suggesting a potential role for steroid hormones in its regulation. Fas ligand (FasL) is one of the mediators of apoptosis in differentiated cells and in embryonic development. Interaction of FasL with its receptor, Fas, induces apoptosis through autocrine and paracrine signaling. We hypothesized that FasL expression in human endometrium is cycle-dependent and that sex steroid hormones regulate FasL expression. We first studied menstrual cycle-dependent expression of FasL in human endometrium by immunohistochemistry in 24 samples. We then investigated the in vitro regulation of FasL expression by ovarian steroid hormones. Throughout the menstrual cycle immunohistochemical staining intensity was stronger in the functional layer of endometrium than it was in the basal layer. FasL immunoreactivity increased gradually through the mid- and late-proliferative phases in both endometrial stromal and glandular cells. Strong FasL expression was observed throughout the late-proliferative and secretory phases. Semiquantitative reverse transcription-polymerase chain reaction analysis in cultured endometrial glandular cells demonstrated that estradiol and progesterone stimulate FasL mRNA expression. Western blot analysis in endometrial glandular and stromal cells in culture revealed that estradiol alone and in combination with progesterone up-regulated FasL protein expression. These results suggest that estradiol and progesterone may have a role in the regulation of maternal immunotolerance for the implantation of a semiallograft embryo by inducing FasL expression. We speculate that increased FasL expression may mediate the apoptosis of endometrial cells and thus may play a role in trophoblast invasion.

Estradiol regulates monocyte chemotactic protein-1 in human coronary artery smooth muscle cells: a mechanism for its antiatherogenic effect.

OBJECTIVE: The protective effect of estrogen against early atherosclerosis in animal models is well documented, but the mechanisms responsible for this effect are not well understood. The earliest recognizable event in the pathogenesis of atherosclerosis is an increased recruitment of macrophages into the arterial subendothelium. Macrophages first play a protective role by removing low-density lipoproteins, but when the cholesterol is in excess, macrophages are converted into foam cells and form atheromas. Recent human and animal data indicate that the recruitment of macrophages to the arterial wall is mediated by monocyte chemotactic protein-1 (MCP-1). We hypothesized that one of the mechanisms of estrogen's protective effect against atherosclerosis may be the down-regulation of MCP-1 expression in the arterial wall. DESIGN: Human coronary artery smooth muscle cells were replicated to confluence in smooth muscle cell basal medium supplemented with growth factors and 5% fetal bovine serum. Before each experiment, cells were incubated for 24 h with phenol red-free medium containing 5% charcoal-stripped calf serum, and then they were treated with various concentrations of 17beta-estradiol as well as selective estrogen receptor (ER) modulators, raloxifene and tamoxifen. MCP-1 messenger ribonucleic acid (mRNA) levels were quantified by Northern blots. MCP-1 protein was quantified using an enzyme-linked immunosorbent assay. ER expression was evaluated by reverse transcriptase-polymerase chain reaction. RESULTS: Human coronary artery smooth muscle cells expressed MCP-1 mRNA and produced MCP-1 protein. Estradiol induced up to 40% inhibition in mRNA expression at concentrations 10-9 M and higher. Raloxifene and tamoxifen also resulted in an inhibition, but the inhibition was less than when induced by estradiol. Estradiol also inhibited the MCP-1 protein production in a concentration-dependent manner (p < 0.05). Coronary smooth muscle cells expressed both ERalpha and ERbeta. CONCLUSION: Our findings suggest that one of the mechanisms by which estrogen prevents atherosclerosis is by down-regulating MCP-1 expression, thus decreasing macrophage recruitment to the arterial wall.

Expression of aminopeptidase N in human endometrium and regulation of its activity by estrogen.

OBJECTIVES: To determine whether aminopeptidase N (APN) regulates the cycle-dependent bioavailability of interleukin-8 (IL-8) in the endometrium. DESIGN: Prospective study. SETTING: University medical center. PATIENT(S): Women without endometrial pathology from the proliferative (n = 25) or secretory (n = 18) phase of the menstrual cycle. INTERVENTION(S): We first immunolocalized APN in the endometrium using an anti-APN antibody. We then determined the regulation of APN kinetic activity by sex steroids in endometrial stromal cell cultures. MAIN OUTCOME MEASURE(S): Expression of APN in human endometrium throughout the menstrual cycle. Regulation of APN activity by estradiol and progesterone in cultured endometrial stromal cells. RESULT(S): Immunohistochemistry of endometrial sections revealed staining of endometrial stroma throughout the menstrual cycle. There was no detectable staining in glandular cells. The expression of APN as detected by immunohistochemistry was significantly lower in the early proliferative phase. In cultured cells, estradiol inhibited APN activity in a concentration-dependent manner. Progesterone did not have a significant effect. CONCLUSION(S): Stromal localization of APN in endometrium may explain the epithelial rather than stromal presence of IL-8 in vivo. Decreased expression of APN may increase IL-8 bioavailability thus contributing to angiogenesis and polymorphonuclear leukocyte chemotaxis in early proliferative phase.