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

PKA and AKIP1 interact to mediate cAMP-driven COX-2 expression: A potentially pivotal interaction in preterm and term labour

Previously, we showed that cAMP increased COX-2 expression in myometrial cells via MAPK. Here, we have extended these observations, using primary myometrial cell cultures to show that the cAMP agonist, forskolin, enhances IL-1β-driven COX-2 expression. We then explored the role of A-kinase interacting protein (AKIP1), which modulates the effect of PKA on p65 activation. AKIP1 knockdown reversed the effect of forskolin, such that its addition inhibited IL-1β-induced COX-2 mRNA expression and reduced the IL-1β-induced increase in nuclear levels of p65 and c-jun. Forskolin alone and with IL-1β increased IκBα mRNA expression suggesting that in the context of inflammation and in the presence of AKIP1, cAMP enhances p65 activation. AKIP1 knockdown reversed these changes. Interestingly, AKIP1 knockdown had minimal effect on the ability of forskolin to repress either basal OTR expression or IL-1β-stimulated OTR mRNA expression. AKIP1 was up-regulated by IL-1β, but not stretch and was repressed by cAMP. The mRNA expression of AKIP1 increased in early labour in tandem with an increase in COX-2 mRNA and protein. AKIP1 protein levels were also increased with inflammation and stretch-induced preterm labour. Our results identify a second important cAMP effector-switch occurring at term in human myometrium and suggest that a hitherto unrecognized interaction may exist between AKIP1, NFκB and AP-1. These data add to the proposition that cAMP acts as a key regulator of human myometrial contractility.

In the mouse, prostaglandin D2 signalling protects the endometrium against adenomyosis

Adenomyosis is characterised by epithelial gland and mesenchymal stroma invasion of the uterine myometrium. Adenomyosis is an oestrogen-dependent gynaecological disease in which a number of factors, such as inflammatory molecules, prostaglandins (PGs), angiogenic factors, cell proliferation and extracellular matrix remodelling proteins, also play a role as key disease mediators. In this study, we used mice lacking both lipocalin and hematopoietic-PG D synthase (L- and H-Pgds) genes in which PGD2 is not produced to elucidate PGD2 roles in the uterus. Gene expression studied by real-time PCR and hormone dosages performed by ELISA or liquid chromatography tandem mass spectroscopy in mouse uterus samples showed that components of the PGD2 signalling pathway, both PGDS and PGD2-receptors, are expressed in the mouse endometrium throughout the oestrus cycle with some differences among uterine compartments. We showed that PGE2 production and the steroidogenic pathway are dysregulated in the absence of PGD2. Histological analysis of L/H-Pgds-/- uteri, and immunohistochemistry and immunofluorescence analyses of proliferation (Ki67), endothelial cell (CD31), epithelial cell (pan-cytokeratin), myofibroblast (α-SMA) and mesenchymal cell (vimentin) markers, identify that 6-month-old L/H-Pgds-/- animals developed adenomyotic lesions, and that disease severity increased with age. In conclusion, this study suggests that the PGD2 pathway has major roles in the uterus by protecting the endometrium against adenomyosis development. Additional experiments, using for instance transcriptomic approaches, are necessary to fully determine the molecular mechanisms that lead to adenomyosis in L/H-Pgds-/- mice and to confirm whether this strain is an appropriate model for studying the human disease.

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.

Cooperative inflammation: The recruitment of inflammatory signaling in marsupial and eutherian pregnancy

The evolution of viviparity in therian mammals, i.e. marsupials and "placental" mammals, occurred by retention of the conceptus in the female reproductive tract and precocious "hatching" from the shell coat. Both eutherian embryo implantation and the opossum embryo attachment reaction are evolutionarily derived from and homologous to a defensive inflammatory process induced after shell coat hatching. However, both lineages, marsupials and placental mammals, have modified the inflammatory response substantially. We review the induction, maintenance, and effects of inflammation throughout pregnancy, with special attention to the role of prostaglandins and the mucosal inflammatory response, both of which likely had roles in early mammalian viviparity. We propose that the key step was not only suppression of the inflammatory response after implantation in placental mammals, but also the transfer of the inflammatory cell-cell communication network to a different set of cell types than in generic inflammation. To support this conclusion we discuss evidence that pro-inflammatory signal production in the opossum is not limited to maternal cells, as expected in bona fide defensive inflammation, but also includes fetal tissues, in a process we term cooperative inflammation. The ways in which the inflammatory reaction was independently modified in these two lineages helps explain major life history differences between extant marsupials and eutherians.

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.

Gestational tissue inflammatory biomarkers at term labor: A systematic review of literature

Parturition at term is characterized by inflammatory overload in both feto-maternal tissues. Despite the large number of individual studies on changes in inflammatory biomarkers linked to labor, a comprehensive profile of them in each of the uterine compartments is not available to better understand their mechanistic contributions to labor. This systematic review investigated the pro- and anti-inflammatory biomarkers reported in intra-uterine tissues (amnion, chorion, decidua, placenta, and myometrium) at term labor. We conducted a systematic review of studies on pro- and anti-inflammatory biomarkers (mRNA and/or protein) reported in feto-maternal tissues during normal human term labor, published in English (1980-2016), in 3 electronic data bases. From a total of 3712 citations, 172 were included for final review. Each tissue expresses a unique set of biomarkers at the time of term labor, but there is significant overlap between tissues. All tissues had IL-6, IL-8, IL-1β, COX-2, PGE-2, TNF-α, and hCAP18 in common at term labor. Common and unique inflammatory biomarkers are expressed in various feto-maternal compartments at term labor. Increase in pro-inflammatory markers in all gestational tissue signifies their harmonious functional role in promoting labor. Anti-inflammatory markers at term labor are hardly reported.

Characteristic Changes in Decidual Gene Expression Signature in Spontaneous Term Parturition

Background

The decidua has been implicated in the “terminal pathway” of human term parturition, which is characterized by the activation of pro-inflammatory pathways in gestational tissues. However, the transcriptomic changes in the decidua leading to terminal pathway activation have not been systematically explored. This study aimed to compare the decidual expression of developmental signaling and inflammation-related genes before and after spontaneous term labor in order to reveal their involvement in this process.

Methods

Chorioamniotic membranes were obtained from normal pregnant women who delivered at term with spontaneous labor (TIL, n = 14) or without labor (TNL, n = 15). Decidual cells were isolated from snap-frozen chorioamniotic membranes with laser microdissection. The expression of 46 genes involved in decidual development, sex steroid and prostaglandin signaling, as well as pro- and anti-inflammatory pathways, was analyzed using high-throughput quantitative real-time polymerase chain reaction (qRT-PCR). Chorioamniotic membrane sections were immunostained and then semi-quantified for five proteins, and immunoassays for three chemokines were performed on maternal plasma samples.

Results

The genes with the highest expression in the decidua at term gestation included insulin-like growth factor-binding protein 1 (IGFBP1), galectin-1 (LGALS1), and progestogen-associated endometrial protein (PAEP); the expression of estrogen receptor 1 (ESR1), homeobox A11 (HOXA11), interleukin 1β (IL1B), IL8, progesterone receptor membrane component 2 (PGRMC2), and prostaglandin E synthase (PTGES) was higher in TIL than in TNL cases; the expression of chemokine C-C motif ligand 2 (CCL2), CCL5, LGALS1, LGALS3, and PAEP was lower in TIL than in TNL cases; immunostaining confirmed qRT-PCR data for IL-8, CCL2, galectin-1, galectin-3, and PAEP; and no correlations between the decidual gene expression and the maternal plasma protein concentrations of CCL2, CCL5, and IL-8 were found.

Conclusions

Our data suggests that with the initiation of parturition, the decidual expression of anti-inflammatory mediators decreases, while the expression of pro-inflammatory mediators and steroid receptors increases. This shift may affect downstream signaling pathways that can lead to parturition.

The Human Ureaplasma Species as Causative Agents of Chorioamnionitis

The human Ureaplasma species are the most frequently isolated microorganisms from the amniotic fluid and placentae of women who deliver preterm and are also associated with spontaneous abortions or miscarriages, neonatal respiratory diseases, and chorioamnionitis. Despite the fact that these microorganisms have been habitually found within placentae of pregnancies with chorioamnionitis, the role of Ureaplasma species as a causative agent has not been satisfactorily explained. There is also controversy surrounding their role in disease, particularly as not all women infected with Ureaplasma spp. develop chorioamnionitis. In this review, we provide evidence that Ureaplasma spp. are associated with diseases of pregnancy and discuss recent findings which demonstrate that Ureaplasma spp. are associated with chorioamnionitis, regardless of gestational age at the time of delivery. Here, we also discuss the proposed major virulence factors of Ureaplasma spp., with a focus on the multiple-banded antigen (MBA), which may facilitate modulation/alteration of the host immune response and potentially explain why only subpopulations of infected women experience adverse pregnancy outcomes. The information presented within this review confirms that Ureaplasma spp. are not simply "innocent bystanders" in disease and highlights that these microorganisms are an often underestimated pathogen of pregnancy.

Peri-ovulatory endocrine regulation of the prostanoid pathways in the bovine uterus at early dioestrus

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n = 15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P < 0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P < 0.05) and phospholipase A2 was downregulated (P < 0.05) in endometrium of the LF-LCL group. No difference (P > 0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P < 0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.

The Long Path of Human Placenta, and Its Derivatives, in Regenerative Medicine

In the 1800s, a baby born with a caul, a remnant of the amniotic sack or fetal membranes, was thought to be lucky, special, or protected. Over time, fetal membranes lost their legendary power and were soon considered nothing more than biological waste after birth. However, placenta tissues have reclaimed their potential and since the early 1900s an increasing body of evidence has shown that these tissues have clinical benefits in a wide range of wound repair and surgical applications. Nowadays, there is a concerted effort to understand the mechanisms underlying the beneficial effects of placental tissues, and, more recently, cells derived thereof. This review will summarize the historical and current clinical applications of human placental tissues, and cells isolated from these tissues, and discuss some mechanisms thought to be responsible for the therapeutic effects observed after tissue and/or cell transplantation.

A new approach to oxidative stress and inflammatory signaling during labour in healthy mothers and neonates

The objective of the current study was to investigate for the first time and simultaneously the oxidative stress and inflammatory signaling induced during the delivery in healthy mothers and their neonates. 56 mothers with normal gestational course and spontaneous delivery were selected. Blood samples were taken from mother (before and after delivery) both from vein and artery of umbilical cord. Lower antioxidant enzymes activities were observed in neonates compared with their mothers and lower oxidative stress in umbilical cord artery with respect to vein. There was an overexpression of inflammatory cytokines in the mother, such as IL-6 and TNF-α, and, in addition, PGE₂ was also increased. Neonates showed lower levels of IL-6 and TNF-α and higher values of sTNF-RII and PGE₂ in comparison with their mothers. Parturition increases oxidative damage in the mother, although the indicators of oxidative damage were lower in umbilical cord artery with respect to umbilical vein. The overexpression of inflammatory cytokines reveals that fetus suffers its own inflammatory process during parturition.

Expression of the prostaglandin F synthase AKR1B1 and the prostaglandin transporter SLCO2A1 in human fetal membranes in relation to spontaneous term and preterm labor

BACKGROUND

Human labor is a complex series of cellular and molecular events that occur at the materno-fetal and uterine levels. Many hypotheses have been proposed for the initiation of human labor, one hypothesis suggests that maturation of the fetus releases a signal in the amniotic fluid that will be transmitted to myometrium via the fetal membranes and initiate uterine contractions. There is strong evidence that prostaglandins (PGs) play a central role in initiation and progression of human labor.

OBJECTIVES

In this study we intended to investigate the expression of prostaglandin F synthase and the prostaglandin transporter in the human fetal membranes and to explore the relationship between cytokines and PGs in the mechanism of human labor.

METHODS

We used fetal membranes obtained before labor at term and after spontaneous labor at term or preterm to identify the changes in prostaglandin F synthase (AKR1B1) and human prostaglandin transporter (SLCO2A1) proteins in relation to parturition. Using fetal membranes explants we tested the effect of cytokines (interleukin-1 and tumor necrosis factor alpha) on PG production and the concomitant changes in cyclooxygenase-2 (PTGS2), AKR1B1 and SLCO2A1 expression.

RESULTS

Expression of PTGS2 and AKR1B1 was upregulated in the fetal membranes in association with term labor while SLCO2A1 was downregulated with advancing gestation and during term labor. Before labor, IL-1 increased the expression of PTGS2, however during labor TNF upregulated PTGS2 and AKR1B1 proteins.

CONCLUSIONS

The prostaglandin F synthase AKR1B1 is upregulated while prostaglandin transporter is downregulated during term labor. The amnion is more responsive than choriodecidua to stimulation with pro-inflammatory cytokines. The mechanisms of term and preterm labor are different.

Prostaglandin pathway gene expression in human placenta, amnion and choriodecidua is differentially affected by preterm and term labour and by uterine inflammation

Background

Elucidation of the biochemical pathways involved in activation of preterm and term human labour would facilitate the development of effective management and inform judgements regarding the necessity for preterm tocolysis and post-term induction. Prostaglandins act at all stages of human reproduction, and are potentially activators of labour.

Methods

Expression of 15 genes involved in prostaglandin synthesis, transport and degradation was measured by qPCR using tissue samples from human placenta, amnion and choriodecidua at preterm and full-term vaginal and caesarean delivery. Cellular localisation of eight prostaglandin pathway proteins was determined by immunohistochemistry.

Results

Expression of prostaglandin pathway genes was differentially affected by factors including gestational age at delivery, and the incidence and duration of labour. Chorioamnionitis/deciduitis was associated with upregulation of PTGS2 (prostaglandin-endoperoxide synthase 2 (prostaglandin G/H synthase and cyclooxygenase)), along with the inflammatory genes IL8 (interleukin 8), S100A8 (S100 calcium binding protein A8) and TLR2 (toll-like receptor 2), in amnion and choriodecidua, and with downregulation of CBR1 (carbonyl reductase 1) and HPGD (hydroxyprostaglandin dehydrogenase 15-(NAD)) in choriodecidua. Protein localisation differed greatly between the various maternal and fetal cell types.

Conclusions

Preterm and term labour are associated with distinct prostaglandin pathway expression profiles; inflammation provokes specific changes, unrelated to the presence of labour; spontaneous and induced term labour are indistinguishable.

Central role for protein kinase C in oxytocin and epidermal growth factor stimulated cyclooxygenase 2 expression in human myometrial cells

BACKGROUND

Prostaglandins are important mediators of uterine contractility and cervical ripening during labour. Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2, is a rate limiting enzyme involved in the conversion of arachidonic acid into prostaglandins at parturition. In this paper, the pathways underlying agonist-induced cyclooxygenase-2 expression in human myometrial cells were studied.

RESULTS

Myometrial cells were stimulated with different agonists: oxytocin (OXT), epidermal growth factor (EGF), interleukin-1β (IL1β), and phorbol-12-myristate-13-acetate (PMA) alone and in the presence of specific signalling pathway inhibitors. The nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB) pathway was inhibited by means of the IKK-2 inhibitor TPCA-1. Signalling through extracellular signal-regulated kinases (ERK) was inhibited using the MEK1/2 inhibitor PD-184352. Bisindolylmaleimide-I was used to inhibit protein kinase C (PKC) signalling. COX-2 expression and ERK phosphorylation were measured using immunoblotting.OXT induced COX-2 expression by activating PKC and ERK. EGF increased COX-2 expression via stimulation of PKC, ERK and NFKB. As expected, the pro-inflammatory cytokine IL1β induced COX-2 expression by activating PKC- and NFKB-dependent pathways. Stimulation of PKC directly with PMA provoked strong COX-2 expression.

CONCLUSIONS

PKC plays a central role in OXT and EGF induced COX-2 expression in human myometrial cells. However, other pathways, notably ERK and NFKB are also involved to an extent which depends on the type of agonist used.

Generation of human endometrial knockout cell lines with the CRISPR/Cas9 system confirms the prostaglandin F2α synthase activity of aldo-ketoreductase 1B1

Prostaglandins (PGs) are important regulators of female reproductive function. The primary PGs produced in the endometrium are PGE2 and PGF2α. Relatively little is known about the biosynthetic pathways leading to the formation of PGF2α. We have described the role of aldo-ketoreductase (AKR)1B1 in increased PGF2α production by human endometrial cells following stimulation with interleukin-1β (IL-1β). However, alternate PGF synthases are expressed concurrently in endometrial cells. A definite proof of the role of AKR1B1 would require gene knockout; unfortunately, this gene has no direct equivalent in the mouse. Recently, an efficient genome-editing technology using RNA-guided DNase Cas9 and the clustered regularly interspaced short palindromic repeats (CRISPR) system has been developed. We have adapted this approach to knockout AKR1B1 gene expression in human endometrial cell lines. One clone (16-2) of stromal origin generated by the CRISPR/Cas9 system exhibited a complete loss of AKR1B1 protein and mRNA expression, whereas other clones presented with partial edition. The present report focuses on the characterization of clone 16-2 exhibiting deletion of 68 and 2 nucleotides, respectively, on each of the alleles. Cells from this clone lost their ability to produce PGF2α but maintained their original stromal cell (human endometrial stromal cells-2) phenotype including the capacity to decidualize in the presence of progesterone (medroxyprogesterone acetate) and 8-bromo-cAMP. Knockout cells also maintained their ability to increase PGE2 production in response to IL-1β. In summary, we demonstrate that the new genome editing CRISPR/Cas9 system can be used in human cells to generate stable knockout cell line models. Our results suggest that genome editing of human cell lines can be used to complement mouse KO models to validate the function of genes in differentiated tissues and cells. Our results also confirm that AKR1B1 is involved in the synthesis of PGF2α.

A comprehensive immunohistochemistry of prostaglandins F2α and E2 synthetic enzymes in rat ovary and uterus around parturition

A comprehensive immunohistochemistry with the isoform-distinguishable antibodies against prostaglandin (PG) F2α and PGE2 biosynthetic enzymes was undertaken to identify the cellular types and enzyme isoforms in rat ovary and uterus around parturition. In general ovarian and uterine cells showed positive immunoreactions for phospholipase A2 groups 4A and 6A, but not group 2A, and cyclooxygenase (COX)-1 rather than COX-2. Their immunoreactions for PGF2α synthase and PGE2 synthase were cell type-dependently variable. The putative PGF2α and PGE2 producing cell types included, as expected, ovarian luteal cells, uterine endometrial epithelium and myometrium, and cervical connective tissue and, unexpectedly, ovarian stromal cells and basal lamina of cervical endometrium. Obtained data indicate the generation of PGF2α and PGE2 by multiple sites, which are entirely the same as established sites of actions, in parturition processes and tissue-dependent differential usage of PG biosynthetic pathway.

Aberrant placenta gene expression pattern in bovine pregnancies established after transfer of cloned or in vitro produced embryos

In the present study, we used the global transcriptome profile approach to identify dysregulated genes, molecular pathways, and molecular functional alterations in bovine placentas derived from somatic cell nuclear transfer (SCNT) and in vitro embryo production (IVP) pregnancies compared with their artificial insemination (AI) counterparts at day 50 of gestation. For this, day 7 blastocysts derived from AI, IVP, or SCNT were transferred to oestrus-synchronized cows. The pregnant animals were slaughtered at day 50 of gestation, and the placentas were then recovered and used for transcriptome analysis using Affymetrix GeneChip bovine genome array. Results showed the SCNT placenta to be different from its AI counterpart in the expression of 1,196 transcripts. These genes were found to be associated with alterations in key biological processes and molecular pathways in SCNT placenta, and the dysregulation of 9% (n = 110) of these genes was due to transcriptional reprogramming error. IVP placenta also displayed alterations in the expression of 72 genes, of which 58 were common to SCNT placenta. Gene enrichment analysis revealed that the expression of genes involved in organ development, blood vessel development, extracellular matrix organization, and the immune system was affected in both SCNT and IVP placentas. However, 96% of the affected genes in SCNT were not significantly altered in IVP groups. Thus, the higher transcriptome dysregulation in SCNT placenta followed by IVP would reflect the degree of placental abnormality in SCNT and IVP pregnancies at day 50 of the gestation, which may have a profound effect on subsequent fetal development and health of the offspring.

Cross talk between PKC and CREB in the induction of COX-2 by PGF2α in human amnion fibroblasts

Compelling evidence indicates a crucial role of prostaglandin F2α (PGF2α) in parturition. Both the maternal and fetal sides of the fetal membranes synthesize PGF2α, which exerts effects via the prostaglandin F2α receptor (FP) that is coupled to the activation of protein kinase C (PKC). Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step of the inducible synthesis of prostaglandin. Although activation of PKC is known to induce COX-2 expression, it is not clear whether PGF2α can induce COX-2 via FP receptor-coupled PKC activation. COX-2 promoter carries a cAMP-response element (CRE) and phosphorylation of CRE binding protein 1 (CREB1) is associated with COX-2 expression in human amnion fibroblasts. We demonstrated that human amnion fibroblasts produced PGF2α and expressed FP receptor. PGF2α increased COX-2 expression and CREB1 phosphorylation, which could be blocked by either the FP receptor antagonist AL8810 or PKC inhibitor Ro31-7549. The PKC activator, phorbol-12-myristate-13-acetate (PMA), could mimic the induction of COX-2 and CREB1 phosphorylation. The induction of COX-2 by PGF2α and PMA could be attenuated by the small interfering RNA-mediated knockdown of CREB1 expression or overexpressing dominant-negative CREB1. A chromatin immunoprecipitation assay showed that the binding of CREB1 to the COX-2 promoter was increased by PGF2α and PMA in amnion fibroblasts. In conclusion, we provide evidence that PGF2α induces COX-2 expression via the FP receptor and phosphorylates CREB1 by PKC, thus increasing CREB1 binding to the COX-2 promoter and the expression of COX-2 in human amnion fibroblasts. This feed-forward loop may be crucial for the production of prostaglandins in the fetal membranes prior to the onset of labor.

Vitamin D elicits anti-inflammatory response, inhibits contractile-associated proteins, and modulates Toll-like receptors in human myometrial cells

Infection during pregnancy triggers inflammation, which can increase myometrial contractions and the risk of premature labor and delivery. In this study, we assessed the effects of vitamin D, an anti-inflammatory ligand on cytokines, chemokines, toll-like receptors, and contractile-associated proteins on immortalized human myometrial smooth muscle (UtSM) cells stimulated with lipopolysaccharide (LPS), a bacterial endotoxin, or interleukin (IL)-1β and measured Toll-like receptor (TLR)-10 expression in pregnant myometrial tissues. A superarray analysis revealed downregulation of the chemokines monocyte chemoattractant protein (MCP)-1, Chemokine (C-X-C motif) ligand (CXCL)-10, CXCL-11, and chemokine (C-X3-C motif) ligand (CX3CL)-1; the proinflammatory cytokines IL-13 and tumor necrosis factor (TNF)-α; the TLR-4 and -5 and triggering receptor expressed on myeloid cells (TREM)-2 and upregulation of the anti-inflammatory cytokine IL-10, as well as Toll interacting protein (TOLLIP) and TREM-1 in vitamin D-treated UtSM cells. In the presence of LPS, vitamin D caused dose-dependent decreases in the messenger RNA expression of MCP-1, IL-1β, IL-13, TNF-α, TLR-4, and TLR-5, the contractile-associated proteins connexin 43, the oxytocin receptor, and the prostaglandin receptor but caused increases in IL-10 and TLR-10 in UtSM cells. The TLR-10 expression was higher in human myometrial tissue obtained from women at term not in labor compared to labor. Vitamin D also attenuated IL-1β-induced MCP-1, IL-6, connexin 43, cyclooxygenase (COX)-2, and prostaglandin receptor expression. Western analysis showed that vitamin D decreased MCP-1, TLR-4, and connexin 43 in the presence of LPS and decreased connexin 43 in the presence of IL-1β. Our results suggest that vitamin D can potentially decrease infection-induced increases in cytokines and contractile-associated proteins in the myometrium.

The Prostaglandin F Synthase Activity of the Human Aldose Reductase AKR1B1 Brings New Lenses to Look at Pathologic Conditions

Prostaglandins are important regulators of female reproductive functions to which aldose reductases exhibiting hydroxysteroid dehydrogenase activity also contribute. Our work on the regulation of reproductive function by prostaglandins (PGs), lead us to the discovery that AKR1B5 and later AKR1B1were highly efficient and physiologically relevant PGF synthases. PGE2 and PGF2α are the main prostanoids produced in the human endometrium and proper balance in their relative production is important for normal menstruation and optimal fertility. Recent evidence suggests that PGE2/EP2 and PGF2α/FP may constitute a functional dyad with physiological relevance comparable to the prostacyclin-thromboxane dyad in the vascular system. We have recently reported that AKR1B1 was expressed and modulated in association with PGF2α production in response to IL-1β in the human endometrium. In the present study, we show that the human AKR1B1 (gene ID: 231) also known as ALDR1 or ALR2 is a functional PGF2α synthase in different models of living cells and tissues. Using human endometrial cells, prostate, and vascular smooth muscle cells, cardiomyocytes and endothelial cells we demonstrate that IL-1β is able to up regulate COX-2 and AKR1B1 proteins as well as PGF2α production under normal glucose concentrations. We show that the promoter activity of AKR1B1 gene is increased by IL-1β particularly around the multiple stress response region containing two putative antioxidant response elements adjacent to TonE and AP1. We also show that AKR1B1 is able to regulate PGE2 production through PGF2α acting on its FP receptor and that aldose reductase inhibitors like alrestatin, Statil (ponalrestat), and EBPC exhibit distinct and characteristic inhibition of PGF2α production in different cell models. The PGF synthase activity of AKR1B1 represents a new and important target to regulate ischemic and inflammatory responses associated with several human pathologies.

Neuromedin B and its receptor influence the activity of myometrial primary cells in vitro through regulation of Il6 expression via the Rela/p65 pathway in mice

The neuromedin B receptor (Nmbr) is an important physiological regulator of spontaneous activities and stress responses through different cascades as well as its autocrine and paracrine effects. Previous studies have revealed that neuromedin B (Nmb) and its receptor signal via the Rela (also known as p65)/Il6 pathway in a mouse model of pregnancy. This study investigated the mechanism of Nmbr signaling via the Rela/p65-Il6 pathway and regulation of the concentration of intracellular free calcium ([Ca(2+)](i)) during the onset of labor in primary mouse myometrial cell cultures isolated from mice in term labor. Data demonstrated Nmbr agonist-mediated upregulation of the DNA binding activity of Rela/p65, Il6 expression, and [Ca(2+)](i) in a concentration-dependent manner. Furthermore, a significant correlation was observed between DNA binding activity of Rela/p65 and Il6 expression. Moreover, this up-regulation was blocked by Nmbr and Rela/p65 knockdown, achieved by RNA interference (RNAi) technology. No significant differences were identified in the inhibition of Il6 expression as a result of Nmbr or Rela/p65 knockdown. However, significant differences were observed between the [Ca(2+)](i) in Rela/p65-specific group and that in the Nmbr-specific small interfering RNA (siRNA)-treated groups. These data demonstrated that the Nmb/Nmbr interaction in pregnant myometrial primary cells in vitro predominantly influenced uterine activity through regulation of Il6 expression via the Rela/p65 pathway, although the effects of Nmbr on [Ca(2+)](i) involved several pathways that remain to be elucidated.

Enzymes of the AKR1B and AKR1C Subfamilies and Uterine Diseases

Endometrial and cervical cancers, uterine myoma, and endometriosis are very common uterine diseases. Worldwide, more than 800,000 women are affected annually by gynecological cancers, as a result of which, more than 360,000 die. During their reproductive age, about 70% of women develop uterine myomas and 10-15% suffer from endometriosis. Uterine diseases are associated with aberrant inflammatory responses and concomitant increased production of prostaglandins (PG). They are also related to decreased differentiation, due to low levels of protective progesterone and retinoic acid, and to enhanced proliferation, due to high local concentrations of estrogens. The pathogenesis of these diseases can thus be attributed to disturbed PG, estrogen, and retinoid metabolism and actions. Five human members of the aldo-keto reductase 1B (AKR1B) and 1C (AKR1C) superfamilies, i.e., AKR1B1, AKR1B10, AKR1C1, AKR1C2, and AKR1C3, have roles in these processes and can thus be implicated in uterine diseases. AKR1B1 and AKR1C3 catalyze the formation of PGF2α, which stimulates cell proliferation. AKR1C3 converts PGD2 to 9α,11β-PGF2, and thus counteracts the formation of 15-deoxy-PGJ2, which can activate pro-apoptotic peroxisome-proliferator-activated receptor γ. AKR1B10 catalyzes the reduction of retinal to retinol, and thus lessens the formation of retinoic acid, with potential pro-differentiating actions. The AKR1C1-AKR1C3 enzymes also act as 17-keto- and 20-ketosteroid reductases to varying extents, and are implicated in increased estradiol and decreased progesterone levels. This review comprises an introduction to uterine diseases and AKR1B and AKR1C enzymes, followed by an overview of the current literature on the AKR1B and AKR1C expression in the uterus and in uterine diseases. The potential implications of the AKR1B and AKR1C enzymes in the pathophysiologies are then discussed, followed by conclusions and future perspectives.