11Beta-hydroxysteroid dehydrogenases in human endometrium

Intratumoral cortisol associated with aromatase in the endometrial cancer microenvironment

Glucocorticoids bind to glucocorticoid receptors (GR). In the peripheral tissues, active cortisol is produced from inactive cortisone by 11β-hydroxysteroid dehydrogenase (HSD)1. 11β-HSD2 is responsible for this reverse catalysis. Although GR and 11β-HSDs have been reported to be involved in the malignant behavior of various cancer types, the concentration of glucocorticoids in cancer tissues has not been investigated. In this study, we measured glucocorticoids in serum and cancer tissues using liquid chromatography-tandem mass spectrometry and clarified, for the first time, the intratumoral "intracrine" production of cortisol by 11β-HSD1/2 in endometrial cancer. Intratumoral cortisol levels were high in the high-malignancy type and the cancer proliferation marker Ki-67-high group, suggesting that cortisol greatly contributes to the malignant behavior of endometrial cancer. A low expression level of the metabolizing enzyme 11β-HSD2 is more important than a high expression level of the synthase 11β-HSD1 for intratumoral cortisol action. Intratumoral cortisol was positively related to the expression/activity of estrogen synthase aromatase, which involved GR expressed in fibroblastic stromal cells but not in cancer cells. Blockade of GR signaling by hormone therapy is expected to benefit patients with endometrial cancer.

Androgen signalling in the ovaries and endometrium

Currently, our understanding of hormonal regulation within the female reproductive system is largely based on our knowledge of estrogen and progesterone signalling. However, while the important functions of androgens in male physiology are well known, it is also recognized that androgens play critical roles in the female reproductive system. Further, androgen signalling is altered in a variety of gynaecological conditions, including endometriosis and polycystic ovary syndrome, indicative of regulatory roles in endometrial and ovarian function. Co-regulatory mechanisms exist between different androgens, estrogens, and progesterone, resulting in a complex network of steroid hormone interactions. Evidence from animal knockout studies, in vitro experiments, and human data indicate that androgen receptor expression is cell-specific and menstrual cycle stage-dependent, with important regulatory roles in the menstrual cycle, endometrial biology, and follicular development in the ovaries. This review will discuss the expression and co-regulatory interactions of androgen receptors, highlighting the complexity of the androgen signalling pathway in the endometrium and ovaries, and the synthesis of androgens from additional alternative pathways previously disregarded as male-specific. Moreover, it will illustrate the challenges faced when studying androgens in female biology, and the need for a more in-depth, integrative view of androgen metabolism and signalling in the female reproductive system.

Uterine bleeding: how understanding endometrial physiology underpins menstrual health

Menstruation is a physiological process that is typically uncomplicated. However, up to one third of women globally will be affected by abnormal uterine bleeding (AUB) at some point in their reproductive years. Menstruation (that is, endometrial shedding) is a fine balance between proliferation, decidualization, inflammation, hypoxia, apoptosis, haemostasis, vasoconstriction and, finally, repair and regeneration. An imbalance in any one of these processes can lead to the abnormal endometrial phenotype of AUB. Poor menstrual health has a negative impact on a person's physical, mental, social, emotional and financial well-being. On a global scale, iron deficiency and iron deficiency anaemia are closely linked with AUB, and are often under-reported and under-recognized. The International Federation of Gynecology and Obstetrics have produced standardized terminology and a classification system for the causes of AUB. This standardization will facilitate future research endeavours, diagnosis and clinical management. In a field where no new medications have been developed for over 20 years, emerging technologies are paving the way for a deeper understanding of the biology of the endometrium in health and disease, as well as opening up novel diagnostic and management avenues.

The Plasminogen Activator System, Glucocorticoid, and Mineralocorticoid Receptors in the Primate Endometrium During Artificial Menstrual Cycles

As a key mechanism in fibrinolysis and tissue remodeling, the plasminogen activator system has been suggested in the process of endometrial shedding and tissue remodeling. Previous studies have explored the role of estrogen, progesterone, and androgen receptors as well as elements of the renin-angiotensin-aldosterone system in shaping the morphology of the endometrium. This study investigates the distribution and concentrations of the mineralocorticoid receptor, glucocorticoid receptor, tissue plasminogen activator, urokinase plasminogen activator, and plasminogen activator inhibitor-1 within the endometrial stroma, glandular, and endothelial cells of the primate endometrium during artificial menstrual cycles. Our immunohistochemistry quantification shows mineralocorticoid and glucocorticoid receptors are ubiquitously distributed within the macaque endometrium with their patterns of expression following similar fluctuations to urokinase and tissue plasminogen activators particularly within the endometrial vasculature. These proteins are present in endometrial vasculature in high levels during the proliferative phase, decreasing levels during the secretory phase followed by rising levels in the menstrual phase. These similarities could suggest overlapping pathways and interactions between the plasminogen activator system and the steroid receptors within the endometrium. Given the anti-inflammatory properties of glucocorticoids and the role of plasminogen activators in endometrial breakdown, the glucocorticoid receptor may be contributing to stabilizing the endometrium by regulating plasminogen activators during the proliferative phase and menstruation. Furthermore, given the anti-mineralocorticoid properties of certain anti-androgenic progestins and their reduced unscheduled uterine bleeding patterns, the mineralocorticoid receptor may be involved in unscheduled endometrial bleeding.

The Menstrual Endometrium: From Physiology to Future Treatments

Abnormal uterine bleeding (AUB) is experienced by up to a third of women of reproductive age. It can cause anaemia and often results in decreased quality of life. A range of medical and surgical treatments are available but are associated with side effects and variable effectiveness. To improve the lives of those suffering from menstrual disorders, delineation of endometrial physiology is required. This allows an increased understanding of how this physiology may be disturbed, leading to uterine pathologies. In this way, more specific preventative and therapeutic strategies may be developed to personalise management of this common symptom. In this review, the impact of AUB globally is outlined, alongside the urgent clinical need for improved medical treatments. Current knowledge of endometrial physiology at menstruation is discussed, focusing on endocrine regulation of menstruation and local endometrial inflammation, tissue breakdown, hypoxia and endometrial repair. The contribution of the specialised endometrial vasculature and coagulation system during menstruation is highlighted. What is known regarding aberrations in endometrial physiology that result in AUB is discussed, with a focus on endometrial disorders (AUB-E) and adenomyosis (AUB-A). Gaps in existing knowledge and areas for future research are signposted throughout, with a focus on potential translational benefits for those experiencing abnormal uterine bleeding. Personalisation of treatment strategies for menstrual disorders is then examined, considering genetic, environmental and demographic characteristics of individuals to optimise their clinical management. Finally, an ideal model of future management of AUB is proposed. This would involve targeted diagnosis of specific endometrial aberrations in individuals, in the context of holistic medicine and with due consideration of personal circumstances and preferences.

Glucocorticoid therapy in assisted reproduction

As glucocorticoids are well-known as important regulators of stress and the immune system, their function and clinical use have elicited substantial interest in the field of reproduction. In particular, the effect of glucocorticoid therapy on endometrial receptivity during assisted reproduction, including in vitro fertilization (IVF) cycles, has led to a great deal of interest and controversy. However, previous studies have not been able to provide consistent and reliable evidence due to their small, non-controlled designs and use of different criteria. Considering the potential risk of exposure to glucocorticoids for mothers and fetuses in early pregnancy, the use of glucocorticoids in IVF cycles should be carefully evaluated, including the balance between risk and benefit. To date, there is no conclusive evidence that the use of glucocorticoids improves the pregnancy rate in IVF cycles with unselected subjects, and a further investigation should be considered with a proper study design.

Aldosterone from endometrial glands is benefit for human decidualization

Local renin-angiotensin system (RAS) in female reproductive system is involved in many physiological and pathological processes, such as follicular development, ovarian angiogenesis, ovarian, and endometrial cancer progress. However, studies on the functional relevance of RAS in human endometrium are limited, especially for renin-angiotensin-aldosterone system (RAAS). In this study, we defined the location of RAS components in human endometrium. We found that angiotensin II type-1 receptor (AT₁R) and aldosterone synthase (CYP11B2), major components of RAAS, are specifically expressed in endometrial gland during mid-secretory phase. Aldosterone receptor, mineralocorticoid receptor (MR), is elevated in stroma in mid-secretory endometrium. In vitro, MR is also activated by aldosterone during decidualization. Activated MR initiates LKB1 expression, followed by phosphorylating of AMPK that stimulates PDK4 expression. The impact of PDK4 on decidualization is independent on PDHE1α inactivation. Based on co-immunoprecipitation, PDK4 interacts with p-CREB to prevent its ubiquitination for facilitating decidualization via FOXO1. Restrain of MR activation interrupts LKB1/p-AMPK/PDK4/p-CREB/FOXO1 pathway induced by aldosterone, indicating that aldosterone action on decidualization is mainly dependent on MR stimulation. Aldosterone biosynthesized in endometrial gland during mid-secretory phase promotes decidualization via activating MR/LKB1/p-AMPK/PDK4/p-CREB/FOXO1 signaling pathway. This study provides the valuable information for understanding the underlying mechanism during decidualization.

Physiology of the Endometrium and Regulation of Menstruation

The physiological functions of the uterine endometrium (uterine lining) are preparation for implantation, maintenance of pregnancy if implantation occurs, and menstruation in the absence of pregnancy. The endometrium thus plays a pivotal role in reproduction and continuation of our species. Menstruation is a steroid-regulated event, and there are alternatives for a progesterone-primed endometrium, i.e., pregnancy or menstruation. Progesterone withdrawal is the trigger for menstruation. The menstruating endometrium is a physiological example of an injured or “wounded” surface that is required to rapidly repair each month. The physiological events of menstruation and endometrial repair provide an accessible in vivo human model of inflammation and tissue repair. Progress in our understanding of endometrial pathophysiology has been facilitated by modern cellular and molecular discovery tools, along with animal models of simulated menses. Abnormal uterine bleeding (AUB), including heavy menstrual bleeding (HMB), imposes a massive burden on society, affecting one in four women of reproductive age. Understanding structural and nonstructural causes underpinning AUB is essential to optimize and provide precision in patient management. This is facilitated by careful classification of causes of bleeding. We highlight the crucial need for understanding mechanisms underpinning menstruation and its aberrations. The endometrium is a prime target tissue for selective progesterone receptor modulators (SPRMs). This class of compounds has therapeutic potential for the clinical unmet need of HMB. SPRMs reduce menstrual bleeding by mechanisms still largely unknown. Human menstruation remains a taboo topic, and many questions concerning endometrial physiology that pertain to menstrual bleeding are yet to be answered.

Identification of key genes, regulatory factors, and drug target genes of recurrent implantation failure (RIF)

Objective: Recurrent implantation failure (RIF) exacerbates the physical trauma of infertile women that undergone in vitro fertilization-embryo transfer (IVF-ET). We aimed to identify the key genes, regulatory factors, and drug target genes involved in the RIF.Methods: The dataset GSE58144 that obtained from the Gene Expression Omnibus mainly contained 43 RIF and 72 control endometrial samples. Differently expressed genes (DEGs) between RIF and control groups were firstly analyzed, followed by the pathway and Gene Ontology (GO) enrichment analysis. Then, protein-protein interaction (PPI) network and miRNA-transcript factor (TF)-DEGs network were established. Finally, a drug-target interaction network was constructed.Results: A total of 399 DEGs were identified between the RIF and controls. In the PPI and key module network, UBE2I, PLK4, XPO1, AURKB, and NUP107 were identified as the hub genes, which mainly enriched in RNA transport and cell division cycle-related pathways and GO items. In the miRNA-TF-DEGs network, E2F4, SIN3A, miRNA489, miRNA199A, miRNA369-3P, miRNA422, and miRNA522 were considered as the key regulatory factors during RIF. In addition, HTR1A, NR3C1, and GABRA3 were the main targets of the drugs annotated in DrugBank.Conclusion: The effects of PLK4, XPO1, AURKB, and NUP107 on the RIF may be via affecting the proliferation and differentiation of endometrial stromal cells. Besides, SIN3A and miRNA199A may be crucial for embryo implantation. In addition, NR3C1 may be used as a possible target for the clinical therapy of RIF.

Immune status during postpartum, peri-implantation and early pregnancy in cattle: An updated view

Throughout the estrous cycle the mammalian endometrium undergoes morphological and functional changes that are essential for the establishment of pregnancy and proper ovarian and uterine functions. Among these changes, the most important are alterations in both inter- and intracellular signalling molecules, many of which modulate immune processes. In the endometrial tissue there are local innate (nonspecific) and adaptive (specific/acquired) response mechanisms which vary because of the endocrine status during the estrous cycle, pregnancy and postpartum period. Endometrial cells have responses that support the immune system by producing pro-inflammatory factors such as cytokines, sensors, effector molecules and chemokines. This response is important during gestation, pregnancy, and fetal growth, as well as in preventing infection, and immuno-rejection of the semi-allogeneic embryo. In dairy cows, both before and immediately after calving, there are marked changes in the values for hormonal and metabolic variables and the immune status is impaired. Thus, in several studies there has been assessment of the physiological and/or abnormal maternal immune changes and possible effects on dairy cow reproductive performance. The objective with this review is to summarize the novel information about the immune mechanisms involved during the postpartum period, subsequent peri-implantation period and pregnancy in dairy cows, and the possible effects on reproductive performance. This information provides for an enhanced understanding of the local and systemic immune responses associated with the metabolic and hormonal status of dairy cows, and alterations in the immune system of high producing cows and the possible effects on subsequent fertility.

Local Cortisol Elevation Contributes to Endometrial Insulin Resistance in Polycystic Ovary Syndrome

CONTEXT

Endometrial insulin resistance (IR) may account for the endometrial dysfunction in polycystic ovary syndrome (PCOS). The underlying mechanism remains to be elucidated.

OBJECTIVE

To investigate whether the abundance of 11β-hydroxysteroid dehydrogenases (11β-HSDs) 1 and 2 and cortisol as well as the insulin signaling pathway are altered in PCOS endometrium and to clarify the relationship between endometrial IR and local cortisol.

DESIGN

We measured cortisol and cortisone concentrations, 11β-HSD1 and 11β-HSD2, and core insulin signaling molecules in endometrial biopsies collected from non-PCOS and PCOS with or without IR patients on the seventh day after human chorionic gonadotropin injection. We also studied the effects of cortisol on glucose uptake and the insulin signaling pathway in primary cultured endometrial epithelial cells (EECs).

RESULTS

The cortisol concentration was elevated, whereas 11β-HSD2 expression was diminished in endometrial biopsies obtained from PCOS with IR patients compared with those from non-PCOS and PCOS without IR patients. The implantation rate was relatively impaired and the endometrial insulin signaling pathway was defective in PCOS with IR patients. In addition, cortisol attenuated insulin-stimulated glucose uptake in EECs, which was mediated by inhibition of Akt phosphorylation and glucose transporter type 4 translocation via induction of phosphatase and tensin homolog deleted on chromosome ten (PTEN).

CONCLUSIONS

Decreased oxidation of cortisol and defects of insulin signaling in endometrium were observed in PCOS with IR patients. The excessive cortisol level, derived from the reduction of 11β-HSD2, might contribute to the development of endometrial IR by inhibiting the insulin signaling pathway via induction of PTEN expression in EECs.

Steroids Regulate CXCL4 in the Human Endometrium During Menstruation to Enable Efficient Endometrial Repair

Context

Repair of the endometrial surface at menstruation must be efficient to minimize blood loss and optimize reproductive function. The mechanism and regulation of endometrial repair remain undefined.

Objective

To determine the presence/regulation of CXCL4 in the human endometrium as a putative repair factor at menses.

Patients/Setting

Endometrial tissue was collected throughout the menstrual cycle from healthy women attending the gynecology department. Menstrual blood loss was objectively measured in a subset, and heavy menstrual bleeding (HMB) was defined as >80 mL per cycle. Monocytes were isolated from peripheral blood.

Design

CXCL4 messenger RNA (mRNA) and protein were identified by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The function/regulation of endometrial CXCL4 was explored by in vitro cell culture.

Results

CXCL4 mRNA concentrations were significantly increased during menstruation. Intense staining for CXCL4 was detected in late secretory and menstrual tissue, localized to stromal, epithelial and endothelial cells. Colocalization identified positive staining in CD68+ macrophages. Treatment of human endometrial stromal and endothelial cells (hESCs and HEECs, respectively) with steroids revealed differential regulation of CXCL4. Progesterone withdrawal resulted in significant increases in CXCL4 mRNA and protein in hESCs, whereas cortisol significantly increased CXCL4 in HEECs. In women with HMB, CXCL4 was reduced in endothelial cells during the menstrual phase compared with women with normal menstrual bleeding. Cortisol-exposed macrophages displayed increased chemotaxis toward CXCL4 compared with macrophages incubated with estrogen or progesterone.

Conclusions

These data implicate CXCL4 in endometrial repair after menses. Reduced cortisol at the time of menses may contribute to delayed endometrial repair and HMB, in part by mechanisms involving aberrant expression of CXCL4.

11β-hydroxysteroid dehydrogenase type 1 and pregnancy: Role in the timing of labour onset and in myometrial contraction

Glucocorticoids play a primary role in the maturation of fetal organs and may contribute to the onset of labour. Glucocorticoid activity depends on the 11β-hydroxysteroid dehydrogenase family (11β-HSDs), catalysing the interconversion between "active" cortisol into inactive cortisone. No definitive study exists on 11β-HSD expression profile in human decidua and myometrium during pregnancy. We investigated the implications of 11β-HSD1 in the regulation of uterine activity in pregnancy, examining its role on contraction of a myocyte cell line and murine 11β-hsd1 levels in utero. Murine 11β-hsd1 mRNA and protein levels in utero progressively increased until the last day of gestation and significantly decreased at the onset of labour (P < 0.0001) (n = 3 to 5 in the various gestational days analysed). Experiments on human myometrial samples confirm the significant fall in 11β-hsd1 mRNA levels at labour, compared to end pregnancy samples (n = 5 to 8). In vitro experiments showed that human myometrial contraction is inhibited by using a non-selective inhibitor of 11β-HSD1. The present study shows the temporal localisation of 11β-HSD1 in uterus, highlighting its importance in the timing of gestation and suggesting its contribution in the myometrium contraction.

Immunoprofiling of human uterine mast cells identifies three phenotypes and expression of ERβ and glucocorticoid receptor

Background: Human mast cells (MCs) are long-lived tissue-resident immune cells characterised by granules containing the proteases chymase and/or tryptase. Their phenotype is modulated by their tissue microenvironment. The human uterus has an outer muscular layer (the myometrium) surrounding the endometrium, both of which play an important role in supporting a pregnancy. The endometrium is a sex steroid target tissue consisting of epithelial cells (luminal, glandular) surrounded by a multicellular stroma, with the latter containing an extensive vascular compartment as well as fluctuating populations of immune cells that play an important role in regulating tissue function. The role of MCs in the human uterus is poorly understood with little known about their regulation or the impact of steroids on their differentiation status. The current study had two aims: 1) To investigate the spatial and temporal location of uterine MCs and determine their phenotype; 2) To determine whether MCs express receptors for steroids implicated in uterine function, including oestrogen (ERα, ERβ), progesterone (PR) and glucocorticoids (GR). Methods: Tissue samples from women (n=46) were used for RNA extraction (n=26) or fixed (n=20) for immunohistochemistry. Results: Messenger RNAs encoded by TPSAB1 (tryptase) and CMA1 (chymase) were detected in endometrial tissue homogenates. Immunohistochemistry revealed the relative abundance of tryptase MCs was myometrium>basal endometrium>functional endometrium. We show for the first time that uterine MCs are predominantly of the classical MC subtypes: (positive, +; negative, -) tryptase+/chymase- and tryptase+/chymase+, but a third subtype was also identified (tryptase-/chymase+). Tryptase+ MCs were of an ERβ+/ERα-/PR-/GR+ phenotype mirroring other uterine immune cell populations, including natural killer cells. Conclusions: Endometrial tissue resident immune MCs have three protease-specific phenotypes. Expression of both ERβ and GR in MCs mirrors that of other immune cells in the endometrium and suggests that MC function may be altered by the local steroid microenvironment.

Immunoprofiling of human uterine mast cells identifies three phenotypes and expression of ERβ and glucocorticoid receptor

Background: Human mast cells (MCs) are long-lived tissue-resident immune cells characterised by granules containing the proteases chymase and/or tryptase. Their phenotype is modulated by their tissue microenvironment. The human uterus has an outer muscular layer (the myometrium) surrounding the endometrium, both of which play an important role in supporting a pregnancy. The endometrium is a sex steroid target tissue consisting of epithelial cells (luminal, glandular) surrounded by a multicellular stroma, with the latter containing an extensive vascular compartment as well as fluctuating populations of immune cells that play an important role in regulating tissue function. The role of MCs in the human uterus is poorly understood with little known about their regulation or the impact of steroids on their differentiation status. The current study had two aims: 1) To investigate the spatial and temporal location of uterine MCs and determine their phenotype; 2) To determine whether MCs express receptors for steroids implicated in uterine function, including oestrogen (ERα, ERβ), progesterone (PR) and glucocorticoids (GR). Methods: Tissue samples from women (n=46) were used for RNA extraction or fixed for immunohistochemistry. Results: Messenger RNAs encoded by TPSAB1 (tryptase) and CMA1 (chymase) were detected in endometrial tissue homogenates. Immunohistochemistry revealed the relative abundance of tryptase MCs was myometrium>basal endometrium>functional endometrium. We show for the first time that uterine MCs are predominantly of the classical MC subtypes: (positive, +; negative, -) tryptase+/chymase- and tryptase+/chymase+, but a third subtype was also identified (tryptase-/chymase+). Tryptase+ MCs were of an ERβ+/ERα-/PR-/GR+ phenotype mirroring other uterine immune cell populations, including natural killer cells. Conclusions: Endometrial tissue resident immune MCs have three protease-specific phenotypes. Expression of both ERβ and GR in MCs mirrors that of other immune cells in the endometrium and suggests that MC function may be altered by the local steroid microenvironment.

Reduced Transforming Growth Factor-β Activity in the Endometrium of Women With Heavy Menstrual Bleeding

Context

Heavy menstrual bleeding (HMB) is common and incapacitating. Aberrant menstrual endometrial repair may result in HMB. The transforming growth factor (TGF)-β superfamily contributes to tissue repair, but its role in HMB is unknown.

Objective

We hypothesized that TGF-β1 is important for endometrial repair, and women with HMB have aberrant TGF-β1 activity at menses.

Participants/Setting

Endometrial biopsies were collected from women, and menstrual blood loss objectively measured [HMB >80 mL/cycle; normal menstrual bleeding (NMB) <80 mL].

Design

Immunohistochemistry and reverse transcription polymerase chain reaction examined endometrial TGF-β1 ligand, receptors, and downstream SMADs in women with NMB and HMB. The function and regulation of TGF-β1 were examined using cell culture.

Results

TGFB1 mRNA was maximal immediately prior to menses, but no differences detected between women with NMB and HMB at any cycle stage. Histoscoring of TGFB1 revealed reduced staining in the stroma during menses in women with HMB (P < 0.05). There were no significant differences in TGFBR1/2 or TGFBR1/2 immunostaining. Cortisol increased activation of TGFB1 in the supernatant of human endometrial stromal cells (HES; P < 0.05) via thrombospondin-1. Endometrial SMAD2 and SMAD3 were lower in women with HMB during menstruation (P < 0.05), and decreased phosphorylated SMAD2/3 immunostaining was seen in glandular epithelial cells during the late secretory phase (P < 0.05). Wound scratch assays revealed increased repair in HES cells treated with TGF-β1 versus control (P < 0.05).

Conclusions

Women with HMB had decreased TGF-β1 and SMADs perimenstrually. Cortisol activated latent TGF-β1 to enhance endometrial stromal cell repair. Decreased TGF-β1 activity may hinder repair of the denuded menstrual endometrium, resulting in HMB.

Expression and regulation of 11β-hydroxysteroid dehydrogenase type 1 in first trimester human decidua cells: Implication in preeclampsia

Glucocorticoids are implicated in successful blastocyst implantation, whereas alterations in glucocorticoid levels are associated with various pregnancy disorders including preeclampsia. Tissue concentration of active glucocorticoids depends on the expression of 11β-hydroxysteroid dehydrogenase (11β-HSD). This study investigated the contribution of first trimester decidua to glucocorticoid availability at the fetal-maternal interface by assessing the expression and regulation of 11β-HSD in human first trimester decidual tissues and cells and by evaluating 11β-HSD levels in preeclamptic vs. gestational age-matched decidua. 11β-HSD1 was the predominant isoform in first trimester decidua. In vitro, decidual cell 11β-HSD1 levels and enzymatic activity were up-regulated by ovarian steroids and inflammatory cytokines. Higher levels of 11β-HSD1 were found in preeclamptic decidua compared to controls. The present study indicates the predominance of 11β-HSD oxoreductase isoform in early decidua. Observations that ovarian hormones and inflammatory cytokines up-regulate 11β-HSD1, together with increased 11β-HSD1 expression in preeclampsia, highlight a role for decidual cells in controlling biologically active glucocorticoids in early pregnancy.

Compartmentalized localization of 11β-HSD 1 and 2 at the feto-maternal interface in the first trimester of human pregnancy

Glucocorticoids are engaged in a number of actions at the feto-maternal interface for the establishment of early pregnancy. However, excessive glucocorticoids can be deleterious to fetal development. Therefore, compartmentalized distribution of 11β-hydroxysteroid dehydrogenase 1 and 2 (11β-HSD1 and 2), which regenerates and inactivates cortisol respectively, would ensure an optimal cortisol concentration at the feto-maternal interface for the establishment of early gestation. However, the distribution pattern of 11β-HSD1 and 2 at the feto-maternal interface in early human pregnancy is not clearly defined. Here we showed that 11β-HSD1 distributed extensively on the maternal side including decidual stromal cells and epithelial cells but scarcely on the fetal side except for localization in the fetal blood vessels of the chorionic villi. In contrast, 11β-HSD2 was abundantly localized in syncytial layer of the chorionic villi and the decidual epithelium. In primary cultures, cortisol upregulated not only 11β-HSD1 expression in decidual stromal cells but also 11β-HSD2 expression in villous trophoblasts of early pregnancy. Further studies revealed that cortisol inhibited the expression of interleukin-1β and 6 in decidual stromal cells and villous trophoblasts, and stimulated expression of human chorionic gonadotropin in villous trophoblasts. Collectively, this study has revealed a compartmentalized distribution pattern of 11β-HSD 1 and 2 at the feto-maternal interface, both of which can be upregulated by glucocorticoids, suggesting that a coordinated interaction between 11β-HSD 1 and 2 may exist to ensure an optimal cortisol concentration at discrete locations at the feto-maternal interface for the establishment of early pregnancy.

Cortisol regulates the paracrine action of macrophages by inducing vasoactive gene expression in endometrial cells

The human endometrium undergoes inflammation and tissue repair during menstruation. We hypothesized that the local availability of bioactive glucocorticoids plays an important role in immune cell-vascular cell interactions in endometrium during tissue repair at menstruation, acting either directly or indirectly via tissue resident macrophages. We sought to determine whether endometrial macrophages are direct targets for glucocorticoids; whether cortisol-treated macrophages have a paracrine effect on angiogenic gene expression by endometrial endothelial cells; and whether endometrial macrophages express angiogenic factors. Human endometrium (n = 41) was collected with ethical approval and subject consent. Donor peripheral blood monocyte-derived macrophages were treated with estradiol, progesterone, or cortisol. The effect of peripheral blood monocyte-derived macrophage secretory products on the expression of angiogenic RNAs by endothelial cells was examined. Immunofluorescence was used to examine localization in macrophages and other endometrial cell types across the menstrual cycle. Endometrial macrophages express the glucocorticoid receptor. In vitro culture with supernatants from cortisol-treated peripheral blood monocyte-derived macrophages resulted in altered endometrial endothelial cell expression of the angiogenic genes, CXCL2, CXCL8, CTGF, and VEGFC These data highlight the importance of local cortisol in regulating paracrine actions of macrophages in the endometrium. CXCL2 and CXCL8 were detected in endometrial macrophages in situ. The expression of these factors was highest in the endometrium during the menstrual phase, consistent with these factors having a role in endometrial repair. Our data have indicated that activation of macrophages with glucocorticoids might have paracrine effects by increasing angiogenic factor expression by endometrial endothelial cells. This might reflect possible roles for macrophages in endometrial repair of the vascular bed after menstruation.

Menstrual physiology: implications for endometrial pathology and beyond

BACKGROUND

Each month the endometrium becomes inflamed, and the luminal portion is shed during menstruation. The subsequent repair is remarkable, allowing implantation to occur if fertilization takes place. Aberrations in menstrual physiology can lead to common gynaecological conditions, such as heavy or prolonged bleeding. Increased knowledge of the processes involved in menstrual physiology may also have translational benefits at other tissue sites.

METHODS

Pubmed and Cochrane databases were searched for all original and review articles published in English until April 2015. Search terms included ‘endometrium’, ‘menstruation’, ‘endometrial repair’, ‘endometrial regeneration’ ‘angiogenesis’, ‘inflammation’ and ‘heavy menstrual bleeding’ or ‘menorrhagia’.

RESULTS

Menstruation occurs naturally in very few species. Human menstruation is thought to occur as a consequence of preimplantation decidualization, conferring embryo selectivity and the ability to adapt to optimize function. We highlight how current and future study of endometrial inflammation, vascular changes and repair/regeneration will allow us to identify new therapeutic targets for common gynaecological disorders. In addition, we describe how increased knowledge of this endometrial physiology will have many translational applications at other tissue sites. We highlight the clinical applications of what we know, the key questions that remain and the scientific and medical possibilities for the future.

CONCLUSIONS

The study of menstruation, in both normal and abnormal scenarios, is essential for the production of novel, acceptable medical treatments for common gynaecological complaints. Furthermore, collaboration and communication with specialists in other fields could significantly advance the therapeutic potential of this dynamic tissue.

Glucocorticoid Regulation of Reproduction

It is well accepted that stress, measured by increased glucocorticoid secretion, leads to profound reproductive dysfunction. In times of stress, glucocorticoids activate many parts of the fight or flight response, mobilizing energy and enhancing survival, while inhibiting metabolic processes that are not necessary for survival in the moment. This includes reproduction, an energetically costly procedure that is very finely regulated. In the short term, this is meant to be beneficial, so that the organism does not waste precious energy needed for survival. However, long-term inhibition can lead to persistent reproductive dysfunction, even if no longer stressed. This response is mediated by the increased levels of circulating glucocorticoids, which orchestrate complex inhibition of the entire reproductive axis. Stress and glucocorticoids exhibits both central and peripheral inhibition of the reproductive hormonal axis. While this has long been recognized as an issue, understanding the complex signaling mechanism behind this inhibition remains somewhat of a mystery. What makes this especially difficult is attempting to differentiate the many parts of both of these hormonal axes, and new neuropeptide discoveries in the last decade in the reproductive field have added even more complexity to an already complicated system. Glucocorticoids (GCs) and other hormones within the hypothalamic-pituitary-adrenal (HPA) axis (as well as contributors in the sympathetic system) can modulate the hypothalamic-pituitary-gonadal (HPG) axis at all levels-GCs can inhibit release of GnRH from the hypothalamus, inhibit gonadotropin synthesis and release in the pituitary, and inhibit testosterone synthesis and release from the gonads, while also influencing gametogenesis and sexual behavior. This chapter is not an exhaustive review of all the known literature, however is aimed at giving a brief look at both the central and peripheral effects of glucocorticoids on the reproductive function.

Cyclic decidualization of the human endometrium in reproductive health and failure

Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Transcriptomic profiling of human choriodecidua during term labor: inflammation as a key driver of labor

PROBLEM

Inflammation is a driver of labor in myometrium and cervix; however, the involvement of decidua is poorly defined. We have reported decidual leukocyte infiltration prior to and during labor; the regulators of these inflammatory processes are unknown.

METHOD OF STUDY

Choriodecidua RNA obtained after term labor or elective cesarean delivery was applied to Affymetrix GeneChips. Pathway analysis and gene validation were performed.

RESULTS

Extensive inflammatory activation was identified in choriodecidua following labor, predominantly upregulation of genes regulating leukocyte trafficking and cytokine signalling. Genes governing cell fate, tissue remodelling, and translation were also altered. Upregulation of candidate genes (ICAM1, CXCR4, CD44, TLR4, SOCS3, BCL2A, and IDO) was confirmed. NFκB, STAT1&3, HMGB1, and miRNA-21, miRNA-46, miRNA-141, and miRNA-200 were predicted upstream regulators.

CONCLUSION

This study confirms inflammatory processes are major players in labor events in choriodecidua, as in other gestational tissues. Suppressing uterine inflammation is likely to be critical for arresting premature labor.

A role for glucocorticoids in stress-impaired reproduction: beyond the hypothalamus and pituitary

In addition to the well-characterized role of the sex steroid receptors in regulating fertility and reproduction, reproductive events are also mediated by the hypothalamic-pituitary-adrenal axis in response to an individual's environment. Glucocorticoid secretion in response to stress contributes to the well-characterized suppression of the hypothalamic-pituitary-gonadal axis through central actions in the hypothalamus and pituitary. However, both animal and in vitro studies indicate that other components of the reproductive system are also regulated by glucocorticoids. Furthermore, in the absence of stress, it appears that homeostatic glucocorticoid signaling plays a significant role in reproduction and fertility in all tissues comprising the hypothalamic-pituitary-gonadal axis. Indeed, as central regulators of the immune response, glucocorticoids are uniquely poised to integrate an individual's infectious, inflammatory, stress, nutritional, and metabolic status through glucocorticoid receptor signaling in target tissues. Endocrine signaling between tissues regulating the immune and stress response and those determining reproductive status provides an evolutionary advantage, facilitating the trade-off between reproductive investment and offspring fitness. This review focuses on the actions of glucocorticoids in tissues important for fertility and reproduction, highlighting recent studies that show glucocorticoid signaling plays a significant role throughout the hypothalamic-pituitary-gonadal axis and characterizing these effects as permissive or inhibitory in terms of facilitating reproductive success.

Elevated periimplantation uterine natural killer cell density in human endometrium is associated with impaired corticosteroid signaling in decidualizing stromal cells

BACKGROUND

Decidualizing human endometrial stromal cells (HESCs) profoundly up-regulate 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), the enzyme that converts inert cortisone to active cortisol. We postulated that the induction of a cortisol gradient upon decidualization of the periimplantation endometrium may impact on the uterine natural killer (uNK) cell population and on local expression of corticosteroid-dependent target genes.

METHODS

Midluteal endometrial biopsies (n = 55) were processed for uNK cell (CD56) analysis and primary HESC cultures. The cultures remained either untreated or were decidualized for 4 or 8 days. A tissue microarray was constructed from endometria with normal (n = 18) and elevated uNK cell (n = 18) scores. An abnormal uNK cell test was defined as greater than 5% CD56(+) cells in the subluminal stroma.

RESULTS

Increased uNK cell density was associated with lower endometrial expression of 11βHSD1 and mineralocorticoid receptor (MR) but not glucocorticoid receptor in vivo. Elevated uNK cell density also corresponded to impaired induction of key decidual markers (11βHSD1, prolactin, and insulin-like growth factor binding protein-1) and MR-dependent enzymes (dehydrogenase/reductase member 3 and retinol saturase) in differentiating HESC cultures. Increased uNK cell density in vivo was not associated with increased in vitro expression of either IL-15 or IL-11, two cytokines implicated in uNK cell regulation.

CONCLUSIONS

Elevated levels of uNK cells in the stroma underlying the surface epithelium are associated with inadequate cortisol biosynthesis by resident decidualizing cells and suboptimal induction of key MR-dependent enzymes involved in lipid biogenesis and the retinoid transport pathway. Our observations suggest that uNK cell testing identifies those women at risk of reproductive failure due to relative uterine cortisol deficiency.

11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action

Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.

Cardiovascular Effects of Aldosterone

Background—

High plasma aldosterone has deleterious cardiovascular effects that are independent of blood pressure, but the role of the mineralocorticoid receptor remains unclear. Renal pseudohypoaldosteronism type 1 is a rare autosomal-dominant disease caused by NR3C2 loss-of-function mutations, which is characterized by renal salt loss and compensatory high renin and aldo secretion. We aimed to assess the cardiovascular outcomes in adults carrying NR3C2 mutations.

Methods and Results—

In this case-control study, 39 NR3C2 mutation carriers were compared with sex- and age-paired noncarriers. Patients underwent cardiac and vascular ultrasound, cardiac MRI with gadolinium injection, measurement of pulse wave velocity, extracellular water, 24-hour ambulatory blood pressure, and autonomous nervous system activity. Mutation carriers showed increased aldo and renin plasma levels (4.5- and 1.6-fold, respectively; P <0.0001), together with increased salt appetite (1.8-fold; P =0.002), with normal extracellular water and blood pressure, and no autonomous nervous system activation. Cardiac and vascular parameters were not significantly different between mutation carriers and noncarriers (no left ventricular remodeling or fibrosis, normal left ventricular systolic function, and aorta stiffness). Tissue Doppler showed better diastolic left ventricular function in mutation carriers (e′, P =0.001; E/e′, P =0.003). Mutation carriers had significantly more frequent history of slow body weight recovery at birth, symptomatic hypotension, and miscarriage in women.

Conclusions—

Despite life-long increase in plasma aldosterone and renin levels, no adverse cardiovascular outcome occurred in pseudohypoaldosteronism type 1, but rather an improved diastolic left ventricular function. This suggests that the cardiovascular consequences of aldosterone excess require full mineralocorticoid receptor signaling.

Clinical Trial Registration—

http://www.clinicaltrials.gov ; unique identifier: NCT00646828.

Induction of 11β-HSD 1 and activation of distinct mineralocorticoid receptor- and glucocorticoid receptor-dependent gene networks in decidualizing human endometrial stromal cells

The actions of glucocorticoids at the feto-maternal interface are not well understood. Here, we show that decidualization of human endometrial stromal cells (HESCs) in response to progesterone and cAMP signaling is associated with a strong induction of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) expression and enzyme activity. Decidualization also triggered a gradual decrease in glucocorticoid receptor (GR) expression and reciprocal increase in mineralocorticoid receptor (MR) levels. Gene expression profiling of differentiating HESCs after small interfering RNA (siRNA)-mediated knockdown of either GR or MR identified 239 and 167 significantly regulated genes, respectively. Interestingly, GR-repressed genes were enriched for Krüppel-associated box domain containing zinc-finger proteins, transcriptional repressors involved in heterochromatin formation. In agreement, GR knockdown was sufficient to enhance trimethylated H3K9 levels in decidualizing cells. Conversely, we identified several MR-dependent genes implicated in lipid droplet biogenesis and retinoid metabolism. For example, the induction in differentiating HESCs of DHRS3, encoding a highly conserved enzyme that catalyzes the oxidation/reduction of retinoids and steroids, was enhanced by aldosterone, attenuated in response to MR knockdown, and abolished upon treatment with the MR antagonist RU26752. Furthermore, we demonstrate that decidualization is associated with dynamic changes in the abundance and distribution of cytoplasmic lipid droplets, the formation of which was blocked by RU26752. In summary, progesterone drives local cortisol biosynthesis by decidual cells through induction of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), leading to transcriptional regulation of distinct GR and MR gene networks involved in epigenetic programming and lipid and retinoid metabolism, respectively.

Steroid regulation of menstrual bleeding and endometrial repair

The ovarian steroid hormones progesterone and estradiol are well established regulators of human endometrial function. However, more recent evidence suggests that androgens and locally generated steroids, such as the glucocorticoids, also have a significant impact on endometrial breakdown and repair. The temporal and spatial pattern of steroid receptor presence in endometrial cells has a significant impact on the endometrial response to steroids. Furthermore, regulation of steroid receptor function by modulatory proteins further refines local responses. This review focuses on steroid regulation of endometrial function during the luteo-follicular transition with a focus on menstruation and endometrial repair.

The endocrine and paracrine control of menstruation

During the reproductive life, the human endometrium undergoes cycles of substantial remodeling including, at menstruation, a massive but delimited tissue breakdown immediately followed by scarless repair. The present review aims at summarizing the current knowledge on the endocrine and paracrine control of menstruation in the light of recent observations that undermine obsolete dogmas. Menstruation can be globally considered as a response to falling progesterone concentration. However, tissue breakdown is heterogeneous and tightly controlled in space and time by a complex network of regulators and effectors, including cytokines, chemokines, proteases and various components of an inflammatory response. Moreover, menstruation must be regarded as part of a complex and integrated mechanism of tissue remodeling including features that precede and follow tissue lysis, i.e. decidualization and immediate post-menstrual regeneration. The understanding of the regulation of menstruation is of major basic and clinical interest. Indeed, these mechanisms largely overlap with those controlling other histopathological occurrences of tissue remodeling, such as development and cancer, and inappropriate control of menstrual features is a major potential cause of two frequent endometrial pathologies (i.e. abnormal uterine bleeding and endometriosis).

The diversity of sex steroid action: the role of micro-RNAs and FOXO transcription factors in cycling endometrium and cancer

The rise and fall in ovarian oestrogen and progesterone production orchestrates a series of events that are indispensable for reproduction, including ovulation, implantation, decidualisation and menstruation. In the uterus, these events involve extensive tissue remodelling, characterised by waves of endometrial cell proliferation, differentiation, recruitment of inflammatory cells, apoptosis, tissue breakdown, menstruation and regeneration. The ability of ovarian hormones to trigger such diverse physiological responses is foremost dependent upon interaction of activated steroid receptors with specific transcription factors, such as Forkhead box class O (FOXO) proteins, involved in cell fate decisions. Furthermore, micro-RNAs (miRNAs), small non-coding RNAs that function as posttranscriptional regulators of gene expression, have emerged as a major regulator system of steroid hormone responses in the female reproductive tract. Consequently, increasing evidence shows that deregulated uterine miRNA expression underpins a spectrum of common reproductive disorders, ranging from implantation failure to endometriosis. Furthermore, by targeting FOXO transcription factors and other key regulators of tissue homeostasis, oncogenic endometrial miRNAs promote tumourigenesis and cancer progression.

Progesterone: a pivotal hormone at menstruation

The human endometrium is exposed to repeated inflammation every month, culminating in tissue breakdown and menstruation. Subsequently, the endometrium has a remarkable capacity for efficient repair and remodeling to enable implantation if fertilization takes place. Endometrial function is known to be governed by the ovarian hormones estradiol and progesterone. This review paper focuses on hormonal control of the cyclical tissue injury and repair that takes place in the local endometrial environment at the time of menstruation. Progesterone levels decline premenstrually as the corpus luteum regresses in the absence of pregnancy, and estradiol levels increase during the postmenstrual phase. The functional impact of these significant changes is discussed, including their immediate and downstream effects. Finally, we examine the contribution of aberrant endometrial function to the presentation of heavy menstrual bleeding and identify potential therapeutic targets for the treatment of this common gynecological problem.

Inflammatory pathways in endometrial disorders

Complex interactions between the endocrine and immune systems govern the key endometrial events of implantation and menstruation. In contrast to other tissue sites, cyclical endometrial inflammation is physiological. However, dysregulation of this inflammatory response can lead to endometrial disorders. This review examines the inflammatory processes occurring in the normal endometrium during menstruation and implantation, highlighting recent advances in our understanding and gaps in current knowledge. Subsequently, the role of inflammatory pathways in the pathology of various common endometrial conditions is discussed, including heavy menstrual bleeding, dysmenorrhoea (painful periods), uterine fibroids, endometriosis and recurrent miscarriage.

Expression of the repulsive SLIT/ROBO pathway in the human endometrium and Fallopian tube

We investigated whether the repulsive SLIT/ROBO pathway is expressed in the endometrium and is negatively regulated during implantation. We also examined whether deficient expression in the Fallopian tube (FT) may predispose to ectopic pregnancy (EP). Endometrium (n = 21) and FT (n = 17) were collected across the menstrual cycle from fertile women with regular cycles. Decidualized endometrium (n = 6) was obtained from women undergoing termination, and FT (n = 6) was obtained from women with EP. SLIT/ROBO expression was quantified by reverse transcription-PCR and protein localized by immunohistochemistry. The regulation of SLIT/ROBO expression in vitro, by sex steroids and hCG, was assessed in endometrial (hTERT-EEpC) epithelial cells, and the effects of Chlamydia trachomatis infection and smoking were studied in oviductal (OE-E6/E7) epithelial cells. Endometrial SLIT3 was highest in the mid-secretory phase (P = 0.0003) and SLIT1,2 and ROBO1 showed a similar trend. ROBO2 was highest in proliferative phase (P = 0.027) and ROBO3,4 showed a similar trend. SLIT2,3 and ROBO1, 4 were lower in decidua compared with mid-secretory endometrium (P < 0.05). SLITs and ROBOs, excepting ROBO2, were expressed in FT but there were no differences across the cycle or in EP. SLIT/ROBO proteins were localized to endometrial and FT epithelium. Treatment of hTERT-EEpC with a combination of estradiol and medroxyprogesterone acetate inhibited ROBO1 expression (P < 0.01) but hCG had no effect. Acute treatment of OE-E6/E7 with smoking metabolite, cotinine, and C. trachomatis had no effect. These findings imply a regulated role for the endometrial SLIT/ROBO interaction during normal development and pregnancy but that it may not be important in the aetiology of EP.

Baby on board: do responses to stress in the maternal brain mediate adverse pregnancy outcome?

Stress and adverse environmental surroundings result in suboptimal conditions in a pregnant mother such that she may experience poor pregnancy outcome including complete pregnancy failure and preterm labor. Furthermore her developing baby is at risk of adverse programming, which confers susceptibility to long term ill health. While some mechanisms at the feto-maternal interface underlying these conditions are understood, the underlying cause for their adverse adaptation is often not clear. Progesterone plays a key role at many levels, including control of neuroendocrine responses to stress, procuring the required immune balance and controlling placental and decidual function, and lack of progesterone can explain many of the unwanted consequences of stress. How stress that is perceived by the mother inhibits progesterone secretion and action is beginning to be investigated. This overview of maternal neuroendocrine responses to stress throughout pregnancy analyses how they interact to compromise progesterone secretion and precipitate undesirable effects in mother and offspring.

Oestrogen and progesterone regulation of inflammatory processes in the human endometrium

The human endometrium is a unique tissue that has to undergo cycles of proliferation, differentiation, destruction and repair. This ensures that the endometrium is optimally prepared for potential embryo implantation but in the absence of an embryo, menstruation occurs to allow endometrial regeneration. These cycles of tissue remodelling occur under the sequential influence of the sex steroid hormones, oestrogen and progesterone. The physiological events of implantation and menstruation display features of inflammation, tightly regulated by oestrogen and progesterone. After menstruation cellular proliferation and blood vessel growth is modulated by oestrogen while after ovulation progesterone is the dominant hormone. In preparation for implantation, progesterone regulates decidualization of the endometrium, uterine natural killer cell numbers within the endometrium and chemokine and cytokine expression. Menstruation, in contrast, is preceded by progesterone withdrawal, which results in an influx of leukocytes into the endometrium and increased production of chemokines and matrix metalloproteinases allowing tissue degradation. The aim of this article is to review the current knowledge on the regulation of inflammatory events within the endometrium by oestrogen and progesterone, in relation to two pivotal events for human reproduction, implantation and menstruation.

Reproductive ecology and the endometrium: physiology, variation, and new directions

Endometrial function is often overlooked in the study of fertility in reproductive ecology, but it is crucial to implantation and the support of a successful pregnancy. Human female reproductive physiology can handle substantial energy demands that include the production of fecund cycles, ovulation, fertilization, placentation, a 9-month gestation, and often several years of lactation. The particular morphology of the human endometrium as well as our relative copiousness of menstruation and large neonatal size suggests that endometrial function has more resources allocated to it than many other primates. The human endometrium has a particularly invasive kind of hemochorial placentation and trophoblast that maximizes surface area and maternal-fetal contact, yet these processes are actually less efficient than the placentation of some of our primate relatives. The human endometrium and its associated processes appear to prioritize maximizing the transmission of oxygen and glucose to the fetus over efficiency and protection of maternal resources. Ovarian function controls many aspects of endometrial function and thus variation in the endometrium is often a reflection of ecological factors that impact the ovaries. However, preliminary evidence and literature from populations of different reproductive states, ages and pathologies also suggests that ecological stress plays a role in endometrial variation, different from or even independent of ovarian function. Immune stress and psychosocial stress appear to play some role in the endometrium's ability to carry a fetus through the mechanism of inflammation. Thus, within reproductive ecology we should move towards a model of women's fecundity and fertility that includes many components of ecological stress and their effects not only on the ovaries, but on processes related to endometrial function. Greater attention on the endometrium may aid in unraveling several issues in hominoid and specifically human evolutionary biology: a low implantation rate, high rates of early pregnancy loss, prenatal investment in singletons but postnatal support of several dependent offspring at once, and higher rate of reproductive and pregnancy-related pathology compared to other primates, ranging from endometriosis to preeclampsia. The study of the endometrium may also complicate some of these issues, as it raises the question of why humans have a maximally invasive placentation method and yet slow fetal growth rates. In this review, I will describe endometrial physiology, methods of measurement, variation, and some of the ecological variables that likely produce variation and pregnancy losses to demonstrate the necessity of further study. I propose several basic avenues of study that leave room for testable hypotheses in the field of reproductive ecology. And finally, I describe the potential of this work not just in reproductive ecology, but in the resolution of broader women's health issues.

Discovery of candidate genes and pathways in the endometrium regulating ovine blastocyst growth and conceptus elongation

Establishment of pregnancy in ruminants requires blastocyst growth to form an elongated conceptus that produces interferon tau, the pregnancy recognition signal, and initiates implantation. Blastocyst growth and development requires secretions from the uterine endometrium. An early increase in circulating concentrations of progesterone (P4) stimulates blastocyst growth and elongation in ruminants. This study utilized sheep as a model to identify candidate genes and regulatory networks in the endometrium that govern preimplantation blastocyst growth and development. Ewes were treated daily with either P4 or corn oil vehicle from day 1.5 after mating to either day 9 or day 12 of pregnancy when endometrium was obtained by hysterectomy. Microarray analyses revealed many differentially expressed genes in the endometria affected by day of pregnancy and early P4 treatment. In situ hybridization analyses revealed that many differentially expressed genes were expressed in a cell-specific manner within the endometrium. The Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used to identify functional groups of genes and biological processes in the endometrium that are associated with growth and development of preimplantation blastocysts. Notably, biological processes affected by day of pregnancy and/or early P4 treatment included lipid biosynthesis and metabolism, angiogenesis, transport, extracellular space, defense and inflammatory response, proteolysis, amino acid transport and metabolism, and hormone metabolism. This transcriptomic data provides novel insights into the biology of endometrial function and preimplantation blastocyst growth and development in sheep.

Cortisol inactivation by 11beta-hydroxysteroid dehydrogenase-2 may enhance endometrial angiogenesis via reduced thrombospondin-1 in heavy menstruation

CONTEXT

Heavy menstrual bleeding (HMB; menorrhagia) impairs quality of life for women and requires medication or surgery. Because glucocorticoids inhibit angiogenesis in other organs, we hypothesized that endometrium of women with HMB is subject to decreased local glucocorticoid exposure and enhanced angiogenesis, thereby increasing menstrual bleeding.

DESIGN

Endometrium was collected from 29 women with menstrual complaints. Menstrual blood loss was measured by alkaline-hematin assay (n = 12, > 80 ml (HMB); n = 17, < 80 ml). Quantitative RT-PCR for thrombospondin-1 (TSP-1) and glucocorticoid-metabolizing enzymes, 11beta-hydroxysteroid dehydrogenases-1 and -2 (11betaHSD1,2) was performed. Glucocorticoid effects on endometrial stromal cells and uterine endothelial cells (UECs) were determined. RNA interference studies in UECs examined the effect of TSP-1 ablation on cortisol action.

RESULTS

Secretory phase endometrium mRNA levels for the cortisol inactivating enzyme 11betaHSD2 were higher [3.78 +/- 1.29 vs. 1.40 +/- 0.6 (arbitrary units), P < 0.05], whereas TSP-1 mRNA was lower [0.40 +/- 0.13 vs. 1.66 +/- 1.02 (arbitrary units), P < 0.05] in women with HMB. In cultured endometrial stromal cells and UECs, cortisol increased TSP-1 expression. Both cortisol and TSP-1 inhibited new vessel formation in endometrial explants embedded in Matrigel. In UECs cortisol inhibition of tube-like structure formation was blocked by small interfering RNA (siRNA) against TSP-1 (25 +/- 2.5% cortisol inhibition with scrambled siRNA vs. 0% cortisol inhibition with TSP-1 siRNA inactivation, P<0.01).

CONCLUSIONS

Enhanced inactivation of cortisol by 11betaHSD2 in endometrium from women with HMB may explain reduced TSP-1 levels and hence endothelial cell dysfunction and abnormal angiogenesis. Inhibition of 11betaHSD2 may be a rational novel therapy for heavy menstrual bleeding.

Role of luteal glucocorticoid metabolism during maternal recognition of pregnancy in women

The human corpus luteum (hCL) is an active, transient, and dynamic endocrine gland. It will experience extensive tissue and vascular remodeling followed by 1) demise of the whole gland without any apparent scarring or 2) maintenance of structural and functional integrity dependent on conceptus-derived human chorionic gonadotropin (hCG). Because cortisol has well-characterized roles in tissue remodeling and repair, we hypothesized that it may have a role in controlling luteal dissolution during luteolysis and would be locally produced toward the end of the luteal cycle. Glucocorticoid-metabolizing enzymes [11beta-hydroxysteroid dehydrogenase (11betaHSD) types 1 and 2] and the glucocorticoid receptor (GR) were assessed in hCL and cultures of luteinized granulosa cells (LGC) using immunofluorescence and quantitative RT-PCR. Furthermore, the effect of cortisol on steroidogenic cell survival and fibroblast-like cell activity was explored in vitro. The hCL expressed 11betaHSD isoenzymes in LGC and nuclear GR in several cell types. hCG up-regulated the expression and activity of 11betaHSD type 1 (P < 0.05) and down-regulated type 2 enzyme (P < 0.05) in vitro and tended to do the same in vivo. Cortisol increased the survival of LGC treated with RU486 (P < 0.05) and suppressed the activity of a proteolytic enzyme associated with luteolysis in fibroblast-like cells (P < 0.05). Our results suggest that, rather than during luteolysis, it is luteal rescue with hCG that is associated with increased local cortisol generation by 11betaHSD type 1. Locally generated cortisol may therefore act on the hCL through GR to have a luteotropic role in the regulation of luteal tissue remodeling during maternal recognition of pregnancy.

Immunoendocrine aspects of endometrial function and implantation

Effective ovarian and uterine function relies on a complex interplay between the endocrine and immune systems. It is generally accepted that in reproductive tissues, oestradiol and progesterone have pro- and anti-inflammatory activities respectively and, in this regard, the paracrine effects of the sex steroids on the ovary are similar to the endocrine effects on the uterus. Ovarian leukocyte recruitment and cytokine release are central to follicle development, ovulation and corpus luteum function. At the uterine level, the cyclical changes in sex steroids regulate the number and distribution of endometrial and decidual immune cells as well as other immune signalling and surveillance factors. The uterine mucosa is unique, in that it must tolerate sperm and the allogeneic blastocyst in a way that does not compromise uterine immune surveillance against bacteria, yeast and viruses. Crosstalk between the sex steroids and immune mediators (systemic and local) are central to these functions, and this article will review these mechanisms and their importance for successful reproductive function and pregnancy success.