Identification and localization of prostaglandin E2 receptors in upper and lower segment human myometrium during pregnancy

Raspberry Leaves and Extracts-Molecular Mechanism of Action and Its Effectiveness on Human Cervical Ripening and the Induction of Labor

The gestational period is an incredibly stressful time for a pregnant woman. Pregnant patients constantly seek effective and reliable compounds in order to achieve a healthy labor. Nowadays, increasing numbers of women use herbal preparations and supplements during pregnancy. One of the most popular and most frequently chosen herbs during pregnancy is the raspberry leaf (Rubus idaeus). Raspberry extracts are allegedly associated with a positive effect on childbirth through the induction of uterine contractions, acceleration of the cervical ripening, and shortening of childbirth. The history of the consumption of raspberry leaves throughout pregnancy is vast. This review shows the current status of the use of raspberry leaves in pregnancy, emphasizing the effect on the cervix, and the safety profile of this herb. The majority of women apply raspberry leaves during pregnancy to induce and ease labor. However, it has not been possible to determine the exact effect of using raspberry extracts on the course of childbirth and the perinatal period. Additionally, it is unclear whether this herb has only positive effects. The currently available data indicate a weak effect of raspberry leaf extracts on labor induction and, at the same time, their possible negative impact on cervical ripening.

Role of intraluteal and intrauterine prostaglandin signaling in LH-induced luteolysis in pregnant rats

Luteal dysfunctions lead to fertility disorders and pregnancy complications. Normal luteal function is regulated by many factors, including luteinizing hormone (LH). The luteotropic roles of LH have been widely investigated but its role in the process of luteolysis has received little attention. LH has been shown to have luteolytic effects during pregnancy in rats and the role of intraluteal prostaglandins (PGs) in LH-mediated luteolysis has been demonstrated by others. However, the status of PG signaling in the uterus during LH-mediated luteolysis remains unexplored. In this study, we utilized the repeated LH administration (4×LH) model for luteolysis induction. We have examined the effect of LH-mediated luteolysis on the expression of genes involved in luteal/uterine PG synthesis, luteal PGF_2α signaling, and uterine activation during different stages (mid and late) of pregnancy. Further, we analyzed the effect of overall PG synthesis machinery blockage on LH-mediated luteolysis during late pregnancy. Unlike the midstage of pregnancy, the expression of genes involved in PG synthesis, PGF_2α signaling, and uterine activation in late-stage pregnant rats' luteal and uterine tissue increase 4×LH. Since the cAMP/PKA pathway mediates LH-mediated luteolysis, we analyzed the effect of inhibition of endogenous PG synthesis on the cAMP/PKA/CREB pathway, followed by the analysis of the expression of markers of luteolysis. Inhibition of endogenous PG synthesis did not affect the cAMP/PKA/CREB pathway. However, in the absence of endogenous PGs, luteolysis could not be activated to the full extent. Our results suggest that endogenous PGs may contribute to LH-mediated luteolysis, but this dependency on endogenous PGs is pregnancy-stage dependent. These findings advance our understanding of the molecular pathways that regulate luteolysis.

cAMP Compartmentalisation in Human Myometrial Cells

Preterm birth is the leading cause of childhood mortality and morbidity. A better understanding of the processes that drive the onset of human labour is essential to reduce the adverse perinatal outcomes associated with dysfunctional labour. Beta-mimetics, which activate the myometrial cyclic adenosine monophosphate (cAMP) system, successfully delay preterm labour, suggesting a key role for cAMP in the control of myometrial contractility; however, the mechanisms underpinning this regulation are incompletely understood. Here we used genetically encoded cAMP reporters to investigate cAMP signalling in human myometrial smooth muscle cells at the subcellular level. We found significant differences in the dynamics of the cAMP response in the cytosol and at the plasmalemma upon stimulation with catecholamines or prostaglandins, indicating compartment-specific handling of cAMP signals. Our analysis uncovered significant disparities in the amplitude, kinetics, and regulation of cAMP signals in primary myometrial cells obtained from pregnant donors compared with a myometrial cell line and found marked response variability between donors. We also found that in vitro passaging of primary myometrial cells had a profound impact on cAMP signalling. Our findings highlight the importance of cell model choice and culture conditions when studying cAMP signalling in myometrial cells and we provide new insights into the spatial and temporal dynamics of cAMP in the human myometrium.

Signaling Pathways Regulating Human Cervical Ripening in Preterm and Term Delivery

At the end of gestation, the cervical tissue changes profoundly. As a result of these changes, the uterine cervix becomes soft and vulnerable to dilation. The process occurring in the cervical tissue can be described as cervical ripening. The ripening is a process derivative of enzymatic breakdown and inflammatory response. Therefore, it is apparent that cervical remodeling is a derivative of the reactions mediated by multiple factors such as hormones, prostaglandins, nitric oxide, and inflammatory cytokines. However, despite the research carried out over the years, the cellular pathways responsible for regulating this process are still poorly understood. A comprehensive understanding of the entire process of cervical ripening seems crucial in the context of labor induction. Greater knowledge could provide us with the means to help women who suffer from dysfunctional labor. The overall objective of this review is to present the current understanding of cervical ripening in terms of molecular regulation and cell signaling.

The role of progesterone receptor isoforms in the myometrium

Myometrial contraction is stringently controlled throughout pregnancy and parturition. Progesterone signaling, effecting through the progesterone receptor (PR), is pivotal in modulating uterine activity. Evidence has shown that two major PR isoforms, PR-A and PR-B, have distinct activities on gene regulation, and the ratio between these isoforms determines the contractility of the myometrium at different gestational stages. Herein, we focus on the regulation of PR activity in the myometrium, especially the differential actions of the two PR isoforms, which maintain uterine quiescence during pregnancy and regulate the switch to a contractile state at the onset of labor. To demonstrate the PR regulatory network and its mechanisms of actions on myometrial activity, we summarized the findings into three parts: Regulation of PR Expression and Isoform Levels, Progesterone Receptor Interacting Factors, and Biological Processes Regulated by Myometrial Progesterone Receptor Isoforms. Recent genomic and epigenomic data, from human specimens and mouse models, are recruited to support the existing knowledge and offer new insights and future directions in myometrial biology.

Salicornia herbacea Aqueous Extracts Regulate NLRP3 Inflammasome Activation in Macrophages and Trophoblasts

Salicornia herbacea L. (Chenopodiaceae), an edible salt marsh plant with anti-inflammatory effects, was examined in macrophages and trophoblasts whether it modulates NLRP3 inflammasome activity. Pretreatment and delayed treatment of S. herbacea extract (SHE) in bone marrow-derived macrophages (BMDMs) reduced the activity of NLRP3 inflammasome induced by lipopolysaccharide (LPS) and adenosine triphosphate stimulation and downregulated interleukin (IL)-1β production. SHE also inhibited pyroptotic cell death, the adaptor molecule apoptosis-associated speck-like protein containing a CARD (ASC), oligomerization, and speck by NLRP3 inflammasome activity in BMDM. Similarly, SHE decreased the mRNA expression of NLRP3, ASC, IL-1β, and IL-6 in the LPS-stimulated human trophoblast cell line, Swan 71 cells. In addition, SHE inhibited the production of IL-6 and IL-1β and decreased the expression of cyclooxygenase-2 and prostaglandin E2 in stimulated Swan 71 cells. Finally, 3,5-dicaffeoylquinic acid (3,5-DCQA), one of the components of S. herbacea, inhibited IL-1β produced by NLRP3 inflammasome activity. In conclusion, SHE downregulated the activity of the NLRP3 inflammasome in macrophages and trophoblasts.

A single-cell atlas of the myometrium in human parturition

Parturition is a well-orchestrated process characterized by increased uterine contractility, cervical ripening, and activation of the chorioamniotic membranes; yet, the transition from a quiescent to a contractile myometrium heralds the onset of labor. However, the cellular underpinnings of human parturition in the uterine tissues are still poorly understood. Herein, we performed a comprehensive study of the human myometrium during spontaneous term labor using single-cell RNA sequencing (scRNA-Seq). First, we established a single-cell atlas of the human myometrium and unraveled the cell type–specific transcriptomic activity modulated during labor. Major cell types included distinct subsets of smooth muscle cells, monocytes/macrophages, stromal cells, and endothelial cells, all of which communicated and participated in immune (e.g., inflammation) and nonimmune (e.g., contraction) processes associated with labor. Furthermore, integrating scRNA-Seq and microarray data with deconvolution of bulk gene expression highlighted the contribution of smooth muscle cells to labor-associated contractility and inflammatory processes. Last, myometrium-derived single-cell signatures can be quantified in the maternal whole-blood transcriptome throughout pregnancy and are enriched in women in labor, providing a potential means of noninvasively monitoring pregnancy and its complications. Together, our findings provide insights into the contributions of specific myometrial cell types to the biological processes that take place during term parturition.

[Factors Associated with Prolonged Duration of Labor in Medical Termination of Pregnancy in the 2nd and 3rd Trimesters]

OBJECTIVE

In the context of a medical termination of pregnancy, prolonged labor may accentuate the difficulty of women's experience and increase the risk of associated complications. The factors associated with prolonged labor are not known. Reducing the duration of labor could limit these complications. Determining the relevant factors associated with prolonged labor defined as a delay between the onset of induction and delivery greater than or equal to 12hours and comparing the complications rates between the two groups.

METHOD

We conducted a retrospective study at Port Royal Maternity Hospital from 2017 to 2019, including medical terminations of pregnancy by vaginal delivery in the 2nd and 3rd trimesters for fetal or maternal reasons.

RESULTS

Two hundred twenty-seven patients were included and divided into two comparative groups based on the duration of labor: labor <12h (n=173) and labor ≥12h (n=54). The mean maternal age was 33.7 years. Forty-four percent of patients were nulliparous, 15.8 % had a history of cesarean section. The average gestational age was 20+2 weeks of gestation. The average duration of labor was 9.7hours. The duration of labor was greater than 24hours in 3% of cases (7/227). Advanced gestational age (22+3 vs. 20+5 p=0,04) and nulliparity (p=0.01) were associated with prolonged labor. Two other intermediate factors, not independent of the duration of labor, were significant: long time to rupture of membranes (239min vs. 427min p<0,01) and an unfavorable Bishop score at rupture (p=0,003). In both groups, the complications were placental retention and the occurrence of fever during labor.

CONCLUSION

Two main factors affecting labor duration were identified in this study (term and nulliparity). This knowledge could allow women to be better informed about the expected time of labor and the potential associated risks.

Preterm labor is a distinct process from term labor following computational analysis of human myometrium

BACKGROUND

The onset of the term human parturition involves myometrial gene expression changes to transform the uterus from a quiescent to a contractile phenotype. It is uncertain whether the same changes occur in the uterus during preterm labor.

OBJECTIVE

This study aimed to compare the myometrial gene expression between term and preterm labor and to determine whether the presence of acute clinical chorioamnionitis or twin gestation affects these signatures.

STUDY DESIGN

Myometrial specimens were collected during cesarean delivery from the following 7 different groups of patients: term not in labor (n=31), term labor (n=13), preterm not in labor (n=21), preterm labor with acute clinical chorioamnionitis (n=6), preterm labor with no acute clinical chorioamnionitis (n=9), twin preterm not in labor (n=8), and twin preterm labor with no acute clinical chorioamnionitis (n=5). RNA was extracted, reverse transcribed and quantitative polymerase chain reactions were performed on 44 candidate genes (with evidence for differential expression in human term labor) using the Fluidigm platform. Computational analysis was performed using 2-class unpaired Wilcoxon tests and principal component analysis.

RESULTS

Computational analysis revealed that gene expression in the preterm myometrium, irrespective of whether in labor or not in labor, clustered tightly and is clearly different from the term labor and term not-in-labor groups. This was true for both singleton and twin pregnancies. Principal component analysis showed that 57% of the variation was explained by 3 principal components. These 44 genes interact in themes of prostaglandin activity and inflammatory signaling known to be important during term labor, but are not a full representation of the myometrium transcriptional activity.

CONCLUSION

The myometrial contractions associated with preterm labor are associated with a pattern of gene expression that is distinct from term labor. Therefore, preterm labor may be initiated by a different myometrial process or processes outside the myometrium.

Role of epigenetics in parturition and preterm birth

Preterm birth occurs worldwide and is associated with high morbidity, mortality, and economic cost. Although several risk factors associated with parturition and preterm birth have been identified, mechanisms underlying this syndrome remain unclear, thereby limiting the implementation of interventions for prevention and management. Known triggers of preterm birth include conditions related to inflammatory and immunological pathways, as well as genetics and maternal history. Importantly, epigenetics, which is the study of heritable phenotypic changes that occur without alterations in the DNA sequence, may play a role in linking social and environmental risk factors for preterm birth. Epigenetic approaches to the study of preterm birth, including analyses of the effects of microRNAs, long non-coding RNAs, DNA methylation, and histone modification, have contributed to an improved understanding of the molecular bases of both term and preterm birth. Additionally, epigenetic modifications have been linked to factors already associated with preterm birth, including obesity and smoking. The prevention and management of preterm birth remains a challenge worldwide. Although epigenetic analysis provides valuable insights into the causes and risk factors associated with this syndrome, further studies are necessary to determine whether epigenetic approaches can be used routinely for the diagnosis, prevention, and management of preterm birth.

PGE2 vs PGF2α in human parturition

Prostaglandin E2 (PGE2) and F2α (PGF2α) are the two most prominent prostanoids in parturition. They are involved in cervical ripening, membrane rupture, myometrial contraction and inflammation in gestational tissues. Because multiple receptor subtypes for PGE2 and PGF2α exist, coupled with diverse signaling pathways, the effects of PGE2 and PGF2α depend largely on the spatial and temporal expression of these receptors in intrauterine tissues. It appears that PGE2 and PGF2α play different roles in parturition. PGE2 is probably more important for labor onset, while PGF2α may play a more important role in labor accomplishment, which may be attributed to the differential effects of PGE2 and PGF2α in gestational tissues. PGE2 is more powerful than PGF2α in the induction of cervical ripening. In terms of myometrial contraction, PGE2 produces a biphasic effect with an initial contraction and a following relaxation, while PGF2α consistently stimulates myometrial contraction. In the fetal membranes, both PGE2 and PGF2α appear to be involved in the process of membrane rupture. In addition, PGE2 and PGF2α may also participate in the inflammatory process of intrauterine tissues at parturition by stimulating not only neutrophil influx and cytokine production but also cyclooxygenase-2 expression thereby intensifying their own production. This review summarizes the differential roles of PGE2 and PGF2α in parturition with respect to their production and expression of receptor subtypes in gestational tissues. Dissecting the specific mechanisms underlying the effects of PGE2 and PGF2α in parturition may assist in developing specific therapeutic targets for preterm and post-term birth.

International Union of Basic and Clinical Pharmacology. CIX. Differences and Similarities between Human and Rodent Prostaglandin E2 Receptors (EP1-4) and Prostacyclin Receptor (IP): Specific Roles in Pathophysiologic Conditions

Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.

Human Uterine Biopsy: Research Value and Common Pitfalls

The human uterus consists of the inner endometrium, the myometrium, and the outer serosa. Knowledge of the function of the uterus in health and disease is relevant to reproduction, fertility, embryology, gynaecology, endocrinology, and oncology. Research performed on uterine biopsies is essential to further the current understanding of human uterine biology. This brief review explores the value of the uterine biopsy in gynaecological and human fertility research and explores the common problems encountered when analysing data generated from different types of uterine biopsies, with the aim of improving the quality, reproducibility, and clinical translatability of future research.

Distribution and Function of Prostaglandin E2 Receptors in Mouse Uterus: Translational Value for Human Reproduction

Prostaglandin (PG) E analogs are used clinically to ripen the cervix and induce labor. However, selective receptor agonists may have potential to improve induction response rates or manage unwanted uterine hypercontractility in conditions such as dysmenorrhea and preterm labor. To characterize their therapeutic value, PGE₂ analogs were used to investigate the functional E-type prostanoid (EP) receptor population in isolated human uterus. Responsiveness in mouse tissues was also examined to validate its use as a preclinical model. Uterine samples were obtained from mice at dioestrus (n = 12), term gestation (n = 14), and labor (n = 12) and from the lower uterus of women undergoing hysterectomy (n = 12) or Caesarean section (n = 18). Vehicle and agonist effects were assessed using superfusion and immersion techniques. PGE₂ evoked predominant excitatory responses in mouse and relaxation in human tissues. Selective EP₄ agonists inhibited tissue activity in both nonpregnant species, while the EP₂ mimetic CP533536 also attenuated uterine contractions throughout gestation. The uterotonic effects of the EP_3/1 agonist sulprostone were more pronounced than the EP₁ agonist ONO-D1-004, corresponding to abundant EP₃ receptor expression in all samples. The contractile phenotype in mouse compared with human uteri may relate to regional differences as well as high expression of EP₃ receptor transcripts. Similarities in nonpregnant and gestational tissues across species suggest that EP₃ may represent a valuable translational drug target for preventing uterine hypercontractility by employing a selective antagonist. SIGNIFICANCE STATEMENT: This research validates the use of nonpregnant mice for preclinical drug discovery of uterine EP receptor targets. To determine the utility of novel drugs and delivery systems at term pregnancy and labor, pharmacological agents interacting with EP₃ receptors have clear translational value.

Cyclooxygenase inhibitors for treating preterm labour: What is the molecular evidence? 1

Preterm birth (<37 weeks of gestation) significantly increases the risk of neonatal mortality and morbidity. As many as half of all preterm births occur following spontaneous preterm labour. Since in such cases there are no known reasons for the initiation of labour, treatment of preterm labour (tocolysis) has sought to stop labour contractions and delay delivery. Despite some success, the use of cyclooxygenase (COX) inhibitors is associated with maternal/fetal side effects, and possibly increased risk of preterm birth. Clinical use of these drugs predates the collection of molecular and biochemical evidence in vitro, examining the expression and activity of COX enzymes in pregnant uterine tissues with and without labour. Such evidence is important to the rationale that COX enzymes are, or are not, appropriate targets for the tocolysis. The current study systematically searched existing scientific evidence to address the hypothesis that COX expression/activity is increased with the onset of human labour, in an effort to determine whether there is a rationale for the use of COX inhibitors as tocolytics. Our review identified 44 studies, but determined that there is insufficient evidence to support or refute a role of COX-1/-2 in the onset of preterm labour that supports COX-targeted tocolysis.

How do Spondias mombin L (Anacardiaceae) leaves extract increase uterine smooth muscle contractions to facilitate child birth in parturient women?

Background

Spondias mombin L. (Anacardiaceae) leaves were used in Togolese folk to treat dystocia, expel placenta and manage post-partum hemorrhage during child birth.

Objectives

This study aimed to establish how the extract of S. mombin leaves increase uterine smooth muscle contractions relevant to its traditional use to facilitate child birth.

Methods

Tests were performed on uterus muscle strips from Sprague-Dawley rats. Central portion of uterine horns were dissected, cleaned of surrounding fat and loose connective tissue, and cut longitudinally into strips which were placed in the organ bath for isometric tension record in presence of different substances.

Results

S. mombin leaves extract increased uterine spontaneous contractions. This effect was reduced by indomethacin (2 × 10-6 M), yohimbine (2 × 10-6 M) and 2-aminoethoxydiphenyl borate (2-APB) (5 × 10-5 M), but not by atropine (3.45 × 10-8 M) and cholesterol (2.5 mg/ml).

Conclusion

The pharmacological justification for the traditional use of S. mombin leaves to treat dystocia and expel placenta was that its hydro-ethanolic extract induced prostaglandins release, α2-adrenoceptors stimulation, calcium release from internal stores and lifted inhibitory effect of cholesterol on uterine contractions in order to increase uterine smooth muscle contractions.

Yimu San improves obstetric ability of pregnant mice by increasing serum oxytocin levels and connexin 43 expression in uterine smooth muscle

Prolonged farrowing remains one of the critical challenges in intensive pig farming. This study aims to explore the effects and mechanism of Yimu San (YMS), a Chinese veterinary medicine micro mist, on delivery ability with mouse models. Thirty-two pregnant mice were randomly divided into a control group and low-YMS, med-YMS, and high-YMS groups. The labor process time and stillbirth rate were recorded, the levels of serum oxytocin and prostaglandin E₂ (PGE₂) were measured with enzyme-linked immunosorbent assay (ELISA). Contractility measurements of the isolated uterus and the expression of connexin 43 (Cx43) in uterine smooth muscle were evaluated. The results showed that compared with the control group, the birth process time and stillbirth rate in the med-YMS and high-YMS groups were remarkably lower. The in vitro uterine contractions, levels of oxytocin, PGE₂, and Cx43 in the med-YMS and high-YMS groups were significantly higher than those in the control group. The differences of the above measurements between the low-YMS group and the control group were not obvious. It can be speculated that YMS could significantly promote labor in pregnant mice by enhancing the levels of oxytocin, Cx43, and PGE₂.

HoxA10 and HoxA11 Regulate the Expression of Contraction-Associated Proteins and Contribute to Regionalized Myometrium Phenotypes in Women

A relaxed fundus (FUN) and a contracted lower uterine segment (LUS) of human myometrium are required for maintaining pregnancy. How this regional myometrium function is regulated remains unclear. We have previously reported that the homeobox protein A13 (HoxA13) is highly expressed in the LUS and can enhance the expression of contraction-associated proteins (CAPs). Here, we show that in contrast to HoxA13, HoxA10 and HoxA11 genes are expressed at significantly higher levels in myometrium tissues and primary myocytes from the FUN. When introduced exogenously into a human myometrial cell line, HoxA10 and HoxA11 suppress the messenger RNA (mRNA) levels of several CAP genes including interleukin-1 beta (IL-1β), IL-6, connexin 43 (Cx43), and cyclooxygenase 2 (Cox2). Consistently, enhanced HoxA10 and HoxA11 expressions strongly inhibited IL-1β and Cx43 protein levels. We further confirmed that higher expression of HoxA10 and HoxA11 genes in primary myocytes from the FUN compared to that from the LUS was associated with lower expression of IL-1β, IL-6, Cox2, and Cx43 genes. We conclude that the expression patterns of HoxA10, HoxA11, and HoxA13 and their actions in regulating CAP genes in FUN and LUS create regionalized myometrium phenotypes in women that may be important to control regionalized myometrium contractility for maintaining pregnancy.

Misoprostol modulates the gene expression prostaglandin E2 and oxidative stress markers in myometrial cells

Misoprostol, prostaglandin E1 analogue, used for labour induction. However, one-third of patients who have labour induced with prostaglandins do not reach vaginal delivery. The differential expression of prostaglandin receptors in myometrial cells could account for this differential response. Since delivery physiology also involves modulation of oxidative metabolism that can be potentially affected by pharmacological drugs, in the present investigation the role of misoprostol on expression of prostaglandin receptors, and oxidative markers of myometrial cells was evaluated. Samples of myometrial tissues procured from women with spontaneous (SL) and nonspontaneous (NSL) labours were cultured in vitro and exposed to different concentrations of misoprostol. Gene expression was evaluated by qRT-PCR and oxidative biomarkers were evaluated by spectrophotometric and fluorometric analysis. Cells from SL women presented greater responsiveness to misoprostol, since an upregulation of genes related to increased muscle contraction was observed. Otherwise, cells from NSL women had low responsiveness to misoprostol exposure or even a suppressive effect on the expression of these genes. Oxidative biomarkers that previously have been related to labour physiology were affected by misoprostol treatment: lipoperoxidation and protein carbonylation (PC). However, a decrease in lipoperoxidation was observed only in SL cells treated with low concentrations of misoprostol, whereas a decrease of PC occurred in all samples treated with different misoprostol concentrations. The results suggest a pharmacogenetic effect of misoprostol in labour induction involving differential regulation of EP receptor genes, as well as some minor differential modulation of oxidative metabolism in myometrial cells.

Differential impact of acute and prolonged cAMP agonist exposure on protein kinase A activation and human myometrium contractile activity

KEY POINTS

Over 15 million babies are born prematurely each year with approximately 1 million of these babies dying as a direct result of preterm delivery. β₂ -Adrenoreceptor agonists that act via cAMP can reduce uterine contractions to delay preterm labour, but their ability to repress uterine contractions lasts ≤ 48 h and their use does not improve neonatal outcomes. Previous research has suggested that cAMP inhibits myometrial contractions via protein kinase A (PKA) activation, but this has yet to be demonstrated with PKA-specific agonists. We investigated the role of PKA in mediating cAMP-induced human myometrial relaxation, and the impact of prolonged cAMP elevation on myometrial contractility. Our findings suggest that PKA is not the sole mediator of cAMP-induced myometrial relaxation and that prolonged prophylactic elevation of cAMP alone is unlikely to prevent preterm labour (PTL).

ABSTRACT

Acute cAMP elevation inhibits myometrial contractility, but the mechanisms responsible are not fully elucidated and the long-term effects are uncertain. Both need to be defined in pregnant human myometrium before the therapeutic potential of cAMP-elevating agents in the prevention of preterm labour can be realised. In the present study, we tested the hypotheses that PKA activity is necessary for cAMP-induced myometrial relaxation, and that prolonged cAMP elevation can prevent myometrial contractions. Myometrial tissues obtained from term, pre-labour elective Caesarean sections were exposed to receptor-independent cAMP agonists to determine the relationship between myometrial contractility (spontaneous and oxytocin-induced), PKA activity, HSP20 phosphorylation and expression of contraction-associated and cAMP signalling proteins. Acute (1 h) application of cAMP agonists promoted myometrial relaxation, but this was weakly related to PKA activation. A PKA-specific activator, 6-Bnz-cAMP, increased PKA activity (6.8 ± 2.0 mean fold versus vehicle; P = 0.0313) without inducing myometrial relaxation. Spontaneous myometrial contractility declined after 24 h but was less marked when tissues were constantly exposed to cAMP agonists, especially for 8-bromo-cAMP (4.3 ± 1.2 mean fold versus vehicle; P = 0.0043); this was associated with changes to calponin, cofilin and HSP20 phosphorylated/total protein levels. Oxytocin-induced contractions were unaffected by pre-incubation with cAMP agonists despite treatments being able to enhance PKA activity and HSP20 phosphorylation. These data suggest that cAMP-induced myometrial relaxation is not solely dependent on PKA activity and the ability of cAMP agonists to repress myometrial contractility is lost with prolonged exposure. We conclude that cAMP agonist treatment alone may not prevent preterm labour.

Mapping PTGERs to the Ovulatory Follicle: Regional Responses to the Ovulatory PGE2 Signal

Prostaglandin E2 (PGE2) is a key intrafollicular mediator of ovulation in many, if not all, mammalian species. PGE2 acts at follicular cells via four distinct PGE2 receptors (PTGERs). Within the ovulatory follicle, each cell type (e.g., oocyte, cumulus granulosa cell, mural granulosa cell, theca cell, endothelial cell) expresses a different subset of the four PTGERs. Expression of a subset of PTGERs has consequences for the generation of intracellular signals and ultimately the unique functions of follicular cells that respond to PGE2. Just as the ovulatory LH surge regulates PGE2 synthesis, the LH surge also regulates expression of the four PTGERs. The pattern of expression of the four PTGERs among follicular cells before and after the LH surge forms a spatial and temporal map of PGE2 responses. Differential PTGER expression, coupled with activation of cell-specific intracellular signals, may explain how a single paracrine mediator can have pleotropic actions within the ovulatory follicle. Understanding the role of each PTGER in ovulation may point to previously unappreciated opportunities to both promote and prevent fertility.

HoxA13 Stimulates Myometrial Cells to Secrete IL-1β and Enhance the Expression of Contraction-Associated Proteins

Bipedalism in humans requires regionalization of myometrial function with a contracted lower uterine segment and a relaxed fundus during pregnancy to prevent fetal pressure on the cervix and reversal of this phenotype during labor. The HoxA13 gene is highly expressed in the lower uterine segment before term labor and regulates the regionalization of myometrium contractility. However, how HoxA13 regulates signal pathways to exert its functions remains unclear. Using a gene microarray technique, we profiled HoxA13 transcriptome in myometrial cells containing immune response genes (eg, IL-1β, IL-6, and IL-8) and contraction-associated proteins (CAPs) such as cyclooxygenase-2 (Cox-2) and connexin-43. IL-1β is responsible for mediating HoxA13 actions in up-regulating IL-6, IL-8, Cox-2, and connexin-43 expression. Blocking IL-1β with its inhibitor abolishes these HoxA13 actions. HoxA13-induced IL-1β stimulates the recruitment of activated THP-1 monocytes to myometrial cells, which in turn amplify the secretion of IL-1β, IL-6, and IL-8 through a mutual feed-forward loop between these cell types. As a result, Cox-2 expression is dramatically enhanced. These findings lead us to conclude that HoxA13 increases myometrial cell contractility by enhancing the secretion of IL-1β, resulting in an up-regulation of CAP and other proinflammatory cytokine expression. HoxA13-induced IL-1β in myometrial cells also prompts leukocyte recruitment and further amplifies CAP expression.

Expression of prostaglandin receptors in Chlamydia trachomatis-infected recurrent spontaneous aborters

A study was undertaken to quantify the expression of prostaglandin (PG) receptors and find the effect of gestational age on expression of PG receptor genes in Chlamydia trachomatis-infected recurrent spontaneous aborters (RSA). Endometrial curettage tissue (ECT) was collected from 130 RSA (Group I) and 100 age-matched controls (Group II) at the Department of Obstetrics and Gynecology, Safdarjung Hospital, New Delhi (India). PCR was performed for diagnosis of C. trachomatis cryptic plasmid; mRNA expression of PG receptor genes was assessed by real-time PCR (q-PCR), while serum progesterone/estrogen levels were determined by respective commercial kits. Data were evaluated statistically. A total of 15.4 % RSA (GroupI) were diagnosed as C. trachomatis-positive (200 bp), whereas controls were uninfected. q-PCR showed significant upregulation (P<0.0001) of PGE2 (EP-1, EP-2, EP-3, EP-4), PGF2α (FP) and PGI2 (IP) receptors in Group I versus Group II. The expression of PG receptors increased significantly with advanced gestational age (P<0.002); however, only contractile receptors, EP-1, EP-3 and FP, were positively correlated with gestational age in Group-I. In infected RSA, mean serum progesterone level was significantly low (P<0.0001) while serum oestrogen was high (P<0.0001). Overall, the data suggest that increased expression of PG receptors, particularly contractile gene receptors (EP-1, EP-3, FP), with advanced gestational age and altered steroid levels could be a possible risk factor for abortion in Chlamydia-infected RSA.

An elevated amniotic fluid prostaglandin F2α concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes

OBJECTIVE

To determine whether an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The retrospective cohort study included 132 patients who had singleton pregnancies with preterm labor (< 35 weeks of gestation) and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for genital mycoplasmas. Intra-amniotic inflammation was defined by an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile among pregnant women at 15-36 weeks of gestation who were not in labor (≥170 pg/mL).

RESULTS

(1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40.2% (53/132) in patients with preterm labor and intact membranes; (2) patients with an elevated amniotic fluid PGF2α concentration had a significantly higher rate of positive amniotic fluid culture [19% (10/53) versus 5% (4/79); p = 0.019], intra-amniotic inflammation/infection [49% (26/53) versus 20% (16/79); p = 0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis, and funisitis, as well as a higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count and a shorter amniocentesis-to-delivery interval than those without an elevated concentration of amniotic fluid PGF2α (p < 0.05 for each); and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4-3.1; p = 0.001].

CONCLUSION

The concentration of PGF2α was elevated in the amniotic fluid of 40.2% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis, and funisitis.

HoxA13 Regulates Phenotype Regionalization of Human Pregnant Myometrium

CONTEXT

Bipedalism separates humans from most other animal species, but results in significant physiologic challenges, particularly with respect to the maintenance of pregnancy and induction of parturition. A contracted lower uterine segment (LUS) and a relaxed uterine fundal myometrium (FUN) during pregnancy are required to prevent pressure on the cervix from the fetal head due to gravity. With the onset of labor, this regionalization of myometrial function must be reversed, allowing descent of the fetus, dilation of the cervix, and expulsion of the fetus through the birth canal. However, the molecular mechanisms remain unclear.

OBJECTIVE AND DESIGN

This study sought to identify phenotypic regionalization of LUS and FUN during pregnancy, RNA sequencing was performed to analyze the human myometrial transcriptome. Real-time PCR and immunoblotting were applied to validate sequencing results. Cell contraction/adhesion assays and gene microarrays were used to study the cellular functions of the identified genes.

RESULTS

Homeobox A13 (HoxA13), prostacyclin synthase (PTGIS), and periostin (POSTN) genes are more highly expressed in LUS than FUN of nonlaboring, but not laboring, myometrial cells at term. HoxA13 up-regulates transcription of PTGIS and POSTN genes. Elevated HoxA13 expression enhances myometrial cell contractility and cell-cell adhesion. Gene microarray studies show that HoxA13-regulated genes are associated with immune response, gap junction/cell adhesion, and pregnancy.

CONCLUSION

The LUS expresses higher levels of HoxA13, PTGIS, and POSTN, and is more contractile than the FUN at term prior to labor. This pregnancy-maintaining regionalization of myometrial function may be mediated by HoxA13.

Umbilical cord prostaglandins in term and preterm parturition

OBJECTIVE

Prostaglandins (PGs) are considered the universal mediators of parturition. Amniotic fluid PGE2 and PGF2α concentrations increase before the onset of spontaneous labor at term, as well as during labor. This study was conducted to determine if the concentrations of umbilical cord PGE2 and PGF2α change with advancing gestational age, spontaneous labor at term, and preterm labor (with and without funisitis).

METHODS

Umbilical cord (UC) tissue samples were obtained from women (N = 158) with singleton pregnancies in the following groups: (1) term deliveries without labor (TNL; n = 20); (2) term deliveries with labor (TIL; n = 20); (3) spontaneous preterm deliveries (sPTD) with (n = 20) and without acute funisitis (n = 20); and (4) preeclampsia without labor (n = 78). The concentrations of PGs were determined in different locations of the UC. PGE2 and PGF2α were measured by specific immunoassays. Non-parametric statistics were used for analysis.

RESULTS

(1) In spontaneous preterm deliveries, the median UC PGE2 concentration was higher in cases with funisitis than in those without funisitis (233.7 pg/µg versus 87.4 pg/µg of total protein, p = 0.001); (2) the median UC PGE2 concentration in sPTD with funisitis was also higher than that obtained from samples who had undergone labor at term (233.7 pg/µg versus 116.1 pg/µg of total protein, p = 0.03); (3) the UC PGE2 and PGF2α concentration increased as a function of advancing gestational age before 36 weeks (PGE2: ρ = 0.59, p < 0.001; PGF2α: ρ = 0.39, p = 0.01), but not after 36 weeks (PGE2: ρ = -0.1, p = 0.5; PGF2α: ρ = -0.2, p = 0.2); (4) the median UC concentrations of PGE2 and PGF2α at term was similar in samples obtained from women with and without labor (PGE2: TNL 133.7 pg/µg versus TIL 116.1 pg/µg of total protein, p = 0.9; PGF2α: TNL 8.4 pg/µg versus TIL 8.1 pg/µg of total protein, p = 0.7); and (5) there was no correlation between UC PG concentration and gestational age at term pregnancy (PGE2: ρ = 0.01, p = 0.9; PGF2α: ρ = 0.07, p = 0.7).

CONCLUSIONS

(1) PGE2 concentrations in the UC are higher in the presence of acute funisitis than in the absence of this lesion; (2) spontaneous labor at term was not associated with a change in the UC concentration of PGE2 and PGF2α; and (3) the UC concentrations of PGE2 and PGF2α increased as a function of gestational age. We propose that UC PGs act as inflammatory mediators generated in the context of fetal systemic inflammation.

Dynamic Changes in the Myometrium during the Third Stage of Labor, Evaluated Using Two-Dimensional Ultrasound, in Women with Normal and Abnormal Third Stage of Labor and in Women with Obstetric Complications

OBJECTIVE

To investigate dynamic changes in myometrial thickness during the third stage of labor.

METHODS

Myometrial thickness was measured using ultrasound at one-minute time intervals during the third stage of labor in the mid-region of the upper and lower uterine segments in 151 patients including: women with a long third stage of labor (n = 30), postpartum hemorrhage (n = 4), preterm delivery (n = 7) and clinical chorioamnionitis (n = 4). Differences between myometrial thickness of the uterine segments and as a function of time were evaluated.

RESULTS

There was a significant linear increase in the mean myometrial thickness of the upper uterine segments, as well as a significant linear decrease in the mean myometrial thickness of the lower uterine segments until the expulsion of the placenta (p < 0.001). The ratio of the measurements of the upper to the lower uterine segments increased significantly as a function of time (p < 0.0001). In women with postpartum hemorrhage, preterm delivery, and clinical chorioamnionitis, an uncoordinated pattern among the uterine segments was observed.

CONCLUSION

A well-coordinated activity between the upper and lower uterine segments is demonstrated in normal placental delivery. In some clinical conditions this pattern is not observed, increasing the time for placental delivery and the risk of postpartum hemorrhage.

Functional and molecular characterization of hyposensitive underactive bladder tissue and urine in streptozotocin-induced diabetic rat

Background

The functional and molecular alterations of nerve growth factor (NGF) and Prostaglandin E2 (PGE2) and its receptors were studied in bladder and urine in streptozotocin (STZ)-induced diabetic rats.

Methodology/Principal Findings

Diabetes mellitus was induced with a single dose of 45 mg/kg STZ Intraperitoneally (i.p) in female Sprague-Dawley rats. Continuous cystometrogram were performed on control rats and STZ treated rats at week 4 or 12 under urethane anesthesia. Bladder was then harvested for histology, expression of EP receptors and NGF by western blotting, PGE2 levels by ELISA, and detection of apoptosis by TUNEL staining. In addition, 4-hr urine was collected from all groups for urine levels of PGE2, and NGF assay. DM induced progressive increase of bladder weight, urine production, intercontraction interval (ICI) and residual urine in a time dependent fashion. Upregulation of Prostaglandin E receptor (EP)1 and EP3 receptors and downregulation of NGF expression, increase in urine NGF and decrease levels of urine PGE2 at week 12 was observed. The decrease in ICI by intravesical instillation of PGE2 was by 51% in control rats and 31.4% in DM group at week 12.

Conclusions/Significance

DM induced hyposensitive underactive bladder which is characterized by increased inflammatory reaction, apoptosis, urine NGF levels, upregulation of EP1 and EP3 receptors and decreased bladder NGF and urine PGE2. The data suggest that EP3 receptor are potential targets in the treatment of diabetes induced underactive bladder.

Rationale for the use of prostaglandins and phosphodiesterase inhibitors in the treatment of functional bladder disorders

In this paper a general discussion of the available data on the role of prostaglandin (PG) and phosphodiesterase is discussed. Functional studies would be a next step to understand the functional meaning of the data described in this paper. The data presented are a basis for further research on selective modulation of the EP1 and EP2 receptor which could be a therapeutic target in functional bladder disorders such as OAB. PDE inhibitors are closer to clinical use, as these drugs have been studied and registered for other indications such as erectile dysfunction in men. Therefore, in vivo studies in human subjects can be conducted on short term. However, from a scientific point of view, it is very important to unravel the exact site of action and role of PDE inhibition with in vitro and in vivo studies as is the case with PG. In this way, a combination of drugs targeting different mechanisms involved in bladder physiology such as PG, cGMP, cAMP, and muscarinic receptors, could reduce side effects and improve efficacy.

Role of PGE2 in the colonic motility: PGE2 generates and enhances spontaneous contractions of longitudinal smooth muscle in the rat colon

The aim of this study was to determine which PGE2 receptors (EP1-4 receptors) influence colonic motility. Mucosa-free longitudinal smooth muscle strips of the rat middle colon spontaneously induced frequent phasic contractions (giant contractions, GCs) in vitro, and the GCs were almost completely abolished by a cyclooxygenase inhibitor, piroxicam, and by an EP3 receptor antagonist, ONO-AE3-240, but enhanced by tetrodotoxin (TTX). In the presence of piroxicam, exogenous PGE2, both ONO-AE-248 (EP3 agonist), and ONO-DI-004 (EP1 agonist) induced GC-like contractions, and increased the frequency and amplitude. These effects of EP receptor agonists were insensitive to TTX and ω-conotoxins. In immunohistochemistry, the EP1 and EP3 receptors were expressed in the longitudinal smooth muscle cells. These results suggest that the endogenous PGE2 spontaneously generates and enhances the frequent phasic contractions directly activating the EP1 and EP3 receptors expressed on longitudinal smooth muscle cells in the rat middle colon.

EP2 receptor activates dual G protein signaling pathways that mediate contrasting proinflammatory and relaxatory responses in term pregnant human myometrium

Prostaglandin (PG) E2 (PGE(2)) plays a central role in the regulation of smooth muscle contractions. Classically, PGE(2) stimulates contractions via EP1 and EP3 receptors, whereas EP2 and EP4 maintain quiescence. Labor involves a change from myometrial quiescence to contractions with a shift from anti- to proinflammatory pathways. EP2, a Gαs-coupled receptor, is known to mediate its actions via cAMP signaling. However, we have recently shown that EP2 also activates the proinflammatory PG G/H synthase-2 (PGHS-2). Here, we identify the mechanism underlying the ability of EP2 to maintain uterine quiescence and activate a proinflammatory/prolabor response in term-pregnant human myometrium. Human myometrial biopsies for in vivo and in vitro studies were taken at cesarean section at term, before or after the onset of labor. Activation of EP2 increased intracellular levels of cAMP and reduced contractility. Contrastingly, EP2 stimulation increased levels of PGHS-2, membrane-associated PGE synthase-1, and PGE(2). This was entirely dependent on EP2-mediated activation of calcium signaling. Both calcium signaling and up-regulation of PGHS-2 were insensitive to the Gαi inhibitor pertussis toxin but inhibited by small interfering RNA knockdown of Gαq/11. There were no differences in EP2 mRNA or protein levels between upper or lower segment myometrium or between pre- and postlabor myometrium. However, in myocytes taken after the onset of labor, cAMP signaling was markedly attenuated, whereas activation of calcium and PGHS-2 was preserved. Overall, the dual coupling of EP2 to Gαs-cAMP and Gαq/11-calcium pathways underlies its ability to mediate contrasting functions in term pregnancy and the "switching" to a prolabor receptor.

Development and validation of primary human myometrial cell culture models to study pregnancy and labour

Background

The development of the in vitro cell culture model has greatly facilitated the ability to study gene expression and regulation within human tissues. Within the human uterus, the upper (fundal) segment and the lower segment may provide distinct functions throughout pregnancy and during labour. We have established primary cultured human myometrial cells, isolated from both upper and lower segment regions of the pregnant human uterus, and validated them for the purpose of studying human pregnancy and labour. The specific objectives of this study were to monitor the viability and characterize the expression profile using selected cellular, contractile and pregnancy associated markers in the primary cultured human myometrial cells. Labour has been described as an inflammatory process; therefore, the ability of these cells to respond to an inflammatory stimulus was also investigated.

Methods

Myometrial cells isolated from paired upper segment (US) and lower segment (LS) biopsies, obtained from women undergoing Caesarean section deliveries at term prior to the onset of labour, were used to identify expression of; α smooth muscle actin, calponin, caldesmon, connexin 43, cyclo-oxygenase-2 (COX-2), oxytocin receptor, tropomyosin and vimentin, by RT-PCR and/or immunocytochemistry. Interleukin (IL)-1β was used to treat cells, subsequently expression of COX-2 mRNA and release of interleukin-8 (CXCL8), were measured. ANOVA followed by Bonferroni’s multiple comparisons test was performed.

Results

We demonstrate that US and LS human myometrial cells stably express all markers examined to at least passage ten (p10). Connexin 43, COX-2 and vimentin mRNA expression were significantly higher in LS cells compared to US cells. Both cell populations respond to IL-1β, demonstrated by a robust release of CXCL8 and increased expression of COX-2 mRNA from passage one (p1) through to p10.

Conclusions

Isolated primary myometrial cells maintain expression of smooth muscle and pregnancy-associated markers and retain their ability to respond to an inflammatory stimulus. These distinct myometrial cell models will provide a useful tool to investigate mechanisms underlying the process of human labour and the concept of functional regionalization of the pregnant uterus.

Maternal serum progesterone, estradiol and estriol levels in successful dinoprostone-induced labor

Hormone-mediated quiescence involves the maintenance of a decreased inflammatory responsiveness. However, no study has investigated whether labor induction with prostanoids is associated with changes in the levels of maternal serum hormones. The objective of this study was to determine whether labor induction with dinoprostone is associated with changes in maternal serum progesterone, estradiol, and estriol levels. Blood samples were obtained from 81 pregnant women at term. Sixteen patients had vaginal birth after spontaneous labor, 12 required cesarean section after spontaneous labor and 16 underwent elective cesarean. Thirty-seven patients had labor induction with dinoprostone. Eligible patients received a vaginal insert of dinoprostone (10 mg) and were followed until delivery. Serum progesterone (P4), estradiol (E2) and estriol (E3) levels and changes in P4/E2, P4/E3 and E3/E2 ratios were monitored from admission to immediately before birth, and the association of these measures with the resulting clinical classification outcome (route of delivery and induction responsiveness) was assessed. Progesterone levels decreased from admission to birth in patients who underwent successful labor induction with dinoprostone [vaginal and cesarean birth after induced labor: 23% (P < 0.001) and 18% (P < 0.025) decrease, respectively], but not in those whose induction failed (6.4% decrease, P > 0.05). Estriol and estradiol levels, P4/E2, P4/E3 and E3/E2 ratios did not differ between groups. Successful dinoprostone-induced labor was associated with reduced maternal progesterone levels from induction to birth. While a causal relationship between progesterone decrease and effective dinoprostone-induced labor cannot be established, it is tempting to propose that dinoprostone may contribute to progesterone withdrawal and favor labor induction in humans.

Fluorescent Human EP3 Receptor Antagonists

Exchange of the lipophilc part of ortho-substituted cinnamic acid lead structures with different small molecule fluorophoric moieties via a dimethylene spacer resulted in hEP3R ligands with affinities in the nanomolar concentration range. Synthesized compounds emit fluorescence in the blue, green, and red range of light and have been tested concerning their potential as a pharmacological tool. hEP3Rs were visualized by confocal laser scanning microscopy on HT-29 cells, on murine kidney tissues, and on human brain tissues and functionally were characterized as antagonists on human platelets. Inhibition of PGE2 and collagen-induced platelet aggregation was measured after preincubation with novel hEP3R ligands. The pyryllium-labeled ligand 8 has been shown as one of the most promising structures, displaying a useful fluorescence and highly affine hEP3R antagonists.

Prostaglandin E2 represses interleukin 1 beta-induced inflammatory mediator output from pregnant human myometrial cells through the EP2 and EP4 receptors

Inflammatory mediators, including prostaglandins, cytokines, and chemokines, are strongly implicated in the mechanism of human labor, though their precise roles remain unknown. Here we demonstrate that interleukin 1 beta (IL-1beta) significantly increased the expression and release of interleukin-8 (CXCL8), monocyte chemotactic protein-1 (CCL2), and granulocyte macrophage colony-stimulating factor (CSF2) by primary human myometrial cells. However, this effect was repressed by prostaglandin E(2) (PGE(2)). As PGE(2) can activate four distinct PGE(2) receptors (EP(1), EP(2), EP(3), and EP(4)) to elicit various responses, we sought to define the EP receptor(s) responsible for this repression. Using selective EP receptor agonists and a selective EP(4) antagonist, we show that PGE(2) mediates the repression of IL-1beta-induced release of CXCL8, CCL2, and CSF2 via activation of the EP(2) and EP(4) receptors. The use of siRNA gene-specific knockdown further confirmed a role for both receptors. Real-time RT-PCR demonstrated that EP(2) was the most highly expressed of all four EP receptors at the mRNA level in human myometrial cells, and immunocytochemistry showed that EP(2) protein is abundantly present throughout the cells. Interestingly, PGE(2) does not appear to reduce mRNA expression of CXCL8, CCL2, and CSF2. Our results demonstrate that PGE(2) can elicit anti-inflammatory responses via activation of the EP(2) and EP(4) receptors in lower segment term pregnant human myometrial cells. Further elucidation of the EP receptor-mediated signaling pathways in the pregnant human uterus may be beneficial for optimizing the maintenance of pregnancy, induction of labor or indeed treatment of preterm labor.

Vaginal Misoprostol vs Vaginal Misoprostol With Estradiol for Labor Induction: A Prospective Double Blind Study

OBJECTIVE

To compare the safety and effectiveness of vaginal misoprostol with combined vaginal misoprostol and estradiol for induction of labor in unfavorable cervix.

METHOD

A prospective study was carried out from Jan 2008 to Jul 2008 on total of 90 women with unfavorable cervix (Bishop's score was <5) and gestation >36 weeks with clinical indication for induction of labor. They were randomly assigned to receive either vaginal misoprostol 25 μg alone or vaginal misoprostol 25 μg with vaginal estradiol 50 μg. Misoprostol alone was repeated every 3 h in both groups till ripening of cervix (Bishop's score was = 8) and establishment of active labor.

RESULTS

Main indications were post dated pregnancies (period of gestation >41 weeks) and pregnancy induced hypertension. Age, parity and mode of delivery were not significantly different. No significant difference was found in pre induction Bishop's score, fetal outcome and maternal complications. However, doses of misoprostol required for cervical ripening (p = 0.017), time required for cervical ripening (p = 0.042), time required for starting of active labor (p = 0.017) and time required for delivery in vaginal delivery cases (p = 0.047) were found significantly less in combined estradiol and misoprostol group.

CONCLUSION

Estradiol acts synergistically with misoprostol vaginally and significantly hastens the process of cervical ripening, initiation of active labor and vaginal delivery.

Prostaglandin receptors EP and FP are regulated by estradiol and progesterone in the uterus of ovariectomized rats

BACKGROUND

Prostaglandins are important for female reproduction. Prostaglandin-E2 acts via four different receptor subtypes, EP1, EP2, EP3 and EP4 whereas prostaglandin-F2alpha acts through FP. The functions of prostaglandins depend on the expression of their receptors in different uterine cell types. Our aim was to investigate the expression of EPs and FP in rat uterus and to identify the regulation by estradiol, progesterone and estrogen receptor (ER) selective agonists.

METHODS

We performed four different rat experiments involving treatments with estradiol, progesterone and ER agonists. Real-time PCR and immunohistochemistry were employed to evaluate receptor expression.

RESULTS

Our results showed that all mRNAs and proteins of EPs and FP are expressed in the rat uterus. The expression pattern and intensity of immunostaining vary between different cell types and treatments. The mRNA expression of all EPs and FP are downregulated by estradiol and the ERalpha specific agonist PPT, whereas the ERbeta specific agonist DPN downregulates only EP2 and EP4. The protein expression however, showed an increase in EP2 and EP3 after estradiol treatment. When treated with estradiol and progesterone in combination, the expressions of EP1 and EP3 are upregulated.

CONCLUSIONS

Regulation of EPs and FP expression by estradiol appears to be mainly modulated via ERalpha for EP1, EP3 and FP, while EP2 and EP4 also are affected by the ERbeta selective ligand. Our immunohistochemical data shows a cell specific regulation of prostaglandin receptors under the influence of ovarian steroids, where EP2 is estrogen regulated in all uterine tissues examined. EP1 and EP3 are upregulated by the combination of estradiol and progesterone. Thus, our observations indicate that estradiol and progesterone regulate the mRNA and protein expression of EPs and FP in a receptor and tissue specific way.

International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress

It is now more than 15 years since the molecular structures of the major prostanoid receptors were elucidated. Since then, substantial progress has been achieved with respect to distribution and function, signal transduction mechanisms, and the design of agonists and antagonists (http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=58). This review systematically details these advances. More recent developments in prostanoid receptor research are included. The DP(2) receptor, also termed CRTH2, has little structural resemblance to DP(1) and other receptors described in the original prostanoid receptor classification. DP(2) receptors are more closely related to chemoattractant receptors. Prostanoid receptors have also been found to heterodimerize with other prostanoid receptor subtypes and nonprostanoids. This may extend signal transduction pathways and create new ligand recognition sites: prostacyclin/thromboxane A(2) heterodimeric receptors for 8-epi-prostaglandin E(2), wild-type/alternative (alt4) heterodimers for the prostaglandin FP receptor for bimatoprost and the prostamides. It is anticipated that the 15 years of research progress described herein will lead to novel therapeutic entities.

Genes for prostaglandin synthesis, transport and inactivation are differentially expressed in human uterine tissues, and the prostaglandin F synthase AKR1B1 is induced in myometrial cells by inflammatory cytokines

Prostaglandins (PGs) are important factors in the physiology of human parturition and the control of uterine contractility. We have characterized the expression of 15 genes from all stages of the PG pathway in human pregnant and non-pregnant (NP) myometrium and in other uterine tissues at delivery, and the results show patterns indicative of different capacities for PG synthesis and catabolism in each tissue. In placenta, the PG synthase expression profile favours production of PGD₂, PGE₂ and PGF₂, with high levels of PG transporters and catabolic PG dehydrogenase suggesting rapid PG turnover. Choriodecidua is primed for PGE₂, PGF₂ and PGD₂ production and high PG turnover, whereas amnion expresses genes for PGE₂ synthesis with low levels of PG transporters and dehydrogenase. In umbilical cord, PGI₂ synthase is highly expressed. In pregnant myometrium, PGI₂, PGD₂ and PGF₂ synthases are highly expressed, whereas PG dehydrogenase is underexpressed. Myometrium from women with spontaneous or induced labour had higher expression of the PGH₂ synthase PTGS2 than tissue from women not-in-labour. Myometrium from NP women had lower levels of PG synthases and higher levels of PG dehydrogenase than pregnant myometrium. Discriminant function analysis showed that expression of selected genes in myometrium could distinguish groups of women with different modes of labour from each other and from NP women. In cultured myometrial cells, there was a dose-dependent stimulatory effect of interleukin 1β and tumour necrosis factor α on PTGS2, PTGES and AKR1B1 (PGF synthase) expression.

The expression of angiogenic growth factors and their receptors in ovarian follicles throughout the estrous cycle in the ewe

Healthy follicles are highly vascularized whereas those undergoing atresia have poor vascularity, suggesting a relationship between follicular vascularization and follicular function. Vascularization is regulated by angiogenic factors, and among them vascular endothelial growth factor (VEGF) and angiopoietin-Tie (Ang-Tie) systems are of central importance. The objectives of this study were to determine if VEGF, VEGF receptor-2 (VEGFR-2), and components of the Ang-Tie system are expressed in ovarian follicles at both the protein and mRNA levels and to explore if their expression is related to the stage of the estrous cycle in the ewe. Ovaries from cyclic ewes were collected during the luteal phase (n=5) or before (n=5), during (n=4), and after (n=4) the preovulatory luteinizing hormone (LH) surge. After fixation, ovaries were wax-embedded, serially sectioned, and analyzed for both protein and mRNA expression of VEGF, VEGFR-2, angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), Tie-1 (mRNA only), and Tie-2. mRNA was studied by in situ hybridization using digoxigenin-11-UTP-labeled ovine riboprobes. A similar pattern of expression was observed for mRNA and protein for all of the factors. Both mRNA and protein expression of VEGF, VEGFR-2, Ang-1, Ang-2, Tie-1 (mRNA only), and Tie-2 in the granulosa and theca cells of follicles >or=2mm in diameter was significantly different among the stages of the estrous cycle, with the highest expression detected at the post-LH surge stage. Theca cells expressed significantly greater levels of the six angiogenic factors compared with granulosa cells at all stages of the estrous cycle. Expression levels in granulosa and theca cells were comparable between small (2.0 to 2.5mm) and medium (2.5 to 4.0mm) follicles, but large follicles (>4.0mm) expressed higher mRNA and protein levels (all P<0.05) for all factors at all stages of the estrous cycle. These data show (i) that VEGF, VEGFR-2, and the Ang-Tie system are present in both granulosa and theca cells of the ovarian follicle, (ii) that thecal cells consistently express greater levels of all of these factors compared with granulosa cells, and (iii) that their levels of expression are related to the stage of the estrous cycle and to follicle size.

The effect of estradiol on COX-2, EP2, and EP4 mRNA expression and the extracellular matrix in the cervix of the hypogonadotrophic, ovariectomized ewe

There is a degree of cervical relaxation in the ewe at estrus that is regulated by changes in prostaglandin synthesis, prostaglandin receptor expression, and changes in the cervical extracellular matrix. It is likely that these are regulated by changes in periovulatory hormones, particularly estradiol. This study determined the effect of estradiol benzoate on the mRNA expression of cyclooxygenase-2 (COX-2) and the prostaglandin E receptors EP(2) and EP(4), the concentration of cervical hyaluronan, and the proportion of smooth muscle and collagen in the cervix of the hypogonadotrophic ovariectomized ewe (Ovis aries). Ovariectomized hypogonadotrophic ewes were given 100 microg estradiol benzoate, and their cervices were collected 0, 24, and 48 h thereafter to determine the expression of cervical COX-2, EP(2), and EP(4) mRNA by in situ hybridization, the concentration of hyaluronan by ELISA, and the proportion of smooth muscle and collagen by Masson's trichrome staining. Estradiol benzoate increased the mRNA expression of COX-2 and EP(4) within 24h after treatment (P<0.05), whereas EP(2) mRNA, hyaluronan, and the ratio of smooth muscle to collagen did not change within 48 h after treatment. The COX-2, EP(2), and EP(4) mRNA expression were greatest in the smooth muscle layers (P<0.05) and least in the luminal epithelium (P<0.05). In conclusion, we inferred that estradiol regulates cervical COX-2 and EP(4) mRNA expression and may regulate cervical relaxation via the synthesis of prostaglandin E(2) and activation of the PGE(2) receptors EP(2) and EP(4).