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PubMed2001

Antibacterial properties of human amnion and chorion in vitro.

OBJECTIVE: The purpose of the present study was to explore the direct effects of amnion and chorion on bacterial growth in vitro including the antibacterial spectrum. Chorioamniotic membranes were obtained under sterile conditions from 13 healthy women undergoing elective cesarean section at term. Likewise, chorioamniotic membranes were obtained from 10 healthy women with spontaneous vaginal delivery at term. Five strains of Hemolytic streptococci group B (GBS) were tested and one clinical isolate of the following species or bacterial groups: Hemolytic streptococcus group A, Staphylococcus aureus, Staphylococcus saprophyticus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter calcoaceticus and Lactobacillus species. Bacteriological media included (1) blood-agar medium; (2) a transparent agar medium for submerged cultures; and (3) a nutrient broth medium. RESULTS: An inhibitory effect of fetal membranes against a range of bacteria was found. Consistent results were obtained in experiments with cultures on agar and cultures suspended in agar (membranes from eight women in both studies). In experiments with liquid cultures (seven women) only chorion showed a marginal inhibitory effect. All strains were inhibited, but the most pronounced inhibition was obtained for streptococcus group A, S. aureus and S. saprophyticus by both chorion and amnion. CONCLUSION: This study demonstrated an inhibitory effect of the fetal membranes on a diverse panel of bacteria

Agar↗
PubMed2001

The effect of dexamethasone on expression of mitogen-induced cyclooxygenase-2 mRNA by amnion-derived (WISH) cells.

OBJECTIVES: It has been reported that prostaglandin E(2) (PGE(2)) is synthesized in the amnion and that this synthesis increases during labor. The purpose of this study was to clarify the mechanism for the expression of cyclooxygenase-2 (COX-2) mRNA and the PGE(2) synthesis of amnion-derived (WISH) cells. STUDY DESIGN: Cells were cultured and treated by 12-O-tetradecanoylphorbol-13-acetate (TPA) and dexamethasone (DEX). PGE(2) in the culture medium was measured by ELISA. Total RNA was extracted from the cells, and COX-2 mRNA expression was analyzed by Northern blot analysis. RESULTS: During the time course of PGE(2) production in response to TPA stimulation, the PGE(2) production could not be detected until incubation had continued for 2h, but this production appeared to continue after 4h of incubation. PGE(2) production was significantly increased by TPA and suppressed by treatment with TPA and DEX. During the time course of COX-2 mRNA expression in response to treatment with TPA, the COX-2 mRNA band was detected after 1.5h. The strongest expression of COX-2 mRNA was observed at 2h incubation. After pre-treatment with TPA for 1h, the TPA-induced COX-2 mRNA was suppressed by treatment with DEX for 1 or 2h incubation in a dose-dependent manner. CONCLUSIONS: These results suggest that COX-2 mRNA is induced by TPA which activate protein kinase C, and suppressed by DEX in WISH cells.

Amnion↗
PubMed1999

Multiple-pulse-mediated electrofusion of intact erythrocyte onto human term placental amnion.

The creation of surface modified human term placental amnion by electrofusing human cells onto its surface has been thought of. A multiple-pulse electrofusion protocol with 10 square pulses of 10-micros pulse length, and electric field of 0.2 kV cm(-1), can make erythrocyte-amnion tissue electrofusion possible. The protocol devised merge the cell-tissue-adherence steps with fusogenic pulse. The finding opens up a new avenue of cell electrofusion onto human tissue with minimal procedural complexities.

Amnion↗
PubMed1999

Unfused amnion and chorion after 14 weeks of gestation: associated fetal structural and chromosomal abnormalities.

OBJECTIVE: To assess possible associations between delayed chorioamniotic fusion after the end of the first trimester and fetal structural and/or chromosomal abnormalities. DESIGN: We prospectively studied 492 fetuses from high-risk pregnancies between 14 and 18 weeks of gestation by transabdominal ultrasonography. Of these, 60 (12%) had unfused amnion and chorion. RESULTS: No additional abnormalities were detected in 28/60 fetuses (47%). Karyotyping was performed in 27/28 cases, and one fetus had trisomy 13 (4%). Ten of 24 fetuses (42%) of this group attending a second mid-trimester scan after 18 weeks of gestation had abnormal sonographic findings not noted at the initial scan. Thirty-two of 60 (53%) fetuses had additional abnormalities at the initial scan: cystic hygroma (n = 12), increased nuchal translucency (n = 10) and other abnormalities (n = 10). Karyotyping revealed aneuploidy in 13 of 28 fetuses (46%) tested: trisomy 21 (n = 5), Turner's syndrome (n = 3), trisomy 18 (n = 3) and trisomy 13 (n = 2). Additional fetal abnormalities were detected only at the second scan after 18 weeks of gestation in three of eight fetuses (38%). CONCLUSIONS: These preliminary data suggest that the sonographic finding of unfused amnion and chorion after 14 weeks of gestation may be associated with fetal structural and/or chromosomal abnormalities.

Amnion↗
PubMed2000

Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) in amnion with term and preterm labour.

To evaluate the association between intercellular adhesion molecule-1 (ICAM-1) in the amnion and preterm labour and delivery, we have assessed ICAM-1 mRNA abundance by Northern analysis and protein levels by enzyme-linked immunosorbent assay (ELISA), in samples of this tissue after term and preterm delivery. The median ICAM-1 mRNA expression following preterm delivery (PTD, n=30) was 24 times greater (P< 0.05) than following elective caesarean section prior to labour at term (CST, n=14). ICAM-1 expression following vaginal delivery after spontaneous labour at term (SLT, n=11) was seven times greater than in the CST group (P< 0.05). The concentration of ICAM-1 protein in the PTD samples (n=31) was four-fold greater than (P< 0.05) in CST (n=14). It was also three-fold greater than in the SLT (n=15) samples (P< 0.05). The results were substantially the same when a preterm spontaneous labour group (PTL) (n=26), exclusive of deliveries complicated by pre-eclampsia (n=1) or intrauterine growth restriction (n=3), was compared to the CST and SLT groups. The ICAM-1 mRNA expression did not differ significantly (P=0.93) between PTL with (n=12) or without (n=14) indicators of intrauterine infection. The results were similar when ICAM-1 protein concentrations were compared (P=0.43) between these two groups. These findings indicate that ICAM-1 is expressed by the human amnion and that this expression is elevated with preterm labour and delivery.

Amnion↗
PubMed2000

Human placenta, chorion, amnion and decidua express different variants of corticotropin-releasing factor receptor messenger RNA.

Human placenta is a major source of corticotropin-releasing factor (CRF), and local effects of CRF in fetal membranes and placenta have been shown, i.e., adrenocorticotropic hormone (ACTH) and oxytocin release from cultured placental cells, as well as prostaglandin release from amnion, chorion and decidua. Two distinct CRF receptors (CRF-R1 and CRF-R2) have been characterized: CRF-R1 consists of two isoforms (CRF-R1alpha and CRF-R1beta) while CRF-R2 has at least three different splice variants (CRF-R2alpha, CRF-R2beta and CRF-R2gamma). To date, CRF-R1 receptor has been identified in human placenta and in pregnant myometrium, while no evidence for placental CRF-R2 receptor isoforms has been provided. The present study investigated whether the different isoforms of CRF-R1 and CRF-R2 receptor mRNA are expressed in fetal membranes and placenta. Tissues were collected after spontaneous vaginal delivery (38-40 weeks) or elective caesarean section (39-41 weeks). The gene expression of CRF receptors was first studied by reverse transcriptase-polymerase chain reaction (RT-PCR), and the presence of CRF-R1alpha, but not of CRF-R1beta, in human placental trophoblast, amnion/chorion and decidua was shown. In addition, among the three CRF-R2 splice variants, only CRF-R2beta mRNA was expressed by trophoblast and fetal membranes. By using in situ hybridization, CRF-R1 and CRF-R2 probes positively hybridized trophoblast and related membranes. CRF-R1 was localized in the syncytiotrophoblast cells, chorionic trophoblast and decidua with a small amount in the amnion. CRF-R2 probe mainly hybridized syncytiotrophoblast cells, but cytotrophoblast also contained discreet amounts of CRF-R2 mRNA signal. The CRF-R2 hybridization signal was also observed within the structure of the villi (blood vessels), chorionic trophoblast and decidual cells, but it was faint or absent in the amniotic epithelium. There was no significant difference in the distribution of CRF-R1 or CRF-R2 mRNA signal between placentas collected from vaginal delivery or caesarean section. The evidence that intrauterine tissues differently express CRF-R1alpha and CRF-R2beta supports possible different local roles of CRF and related peptides into intrauterine tissues during pregnancy.

Amnion↗
PubMed2000

Tumour necrosis factor-alpha regulation of prostaglandin H synthase-2 transcription is not through nuclear factor-kappaB in amnion-derived AV-3 cells.

Tumour necrosis factor (TNF)-alpha-stimulated prostaglandin (PG) E(2)biosynthesis by amnion-derived AV3 cells is accompanied by increased prostaglandin H synthase (PGHS)-2 mRNA expression. PGHS-1 mRNA expression is unchanged. PGHS-2 promoter-reporter constructs (-891/+9 and 5' deletions thereof) were prepared. The regions containing concensus nuclear factor kappaB (NF-kappaB) elements (-447/-438 and -222/-213) did not enhance promoter activity. Elements associated with both basal and TNF-alpha-stimulated expression lie between bases -52 and -203. Site-directed mutagenesis of nuclear factor of interleukin-6 (NF-IL6) and cyclic AMP response elements (CREs) in this region reduced both basal and induced transcriptional activity of the -203/+9 construct by over 95 per cent. Electrophoretic mobility-shift assays using oligonucleotides derived from these sites demonstrated formation of specific DNA-protein complexes. Both NF-IL6 and CRE unlabelled oligonucleotides inhibited complex formation with the NF-IL6 oligonucleotide probe. Unlabelled CRE oligonucleotide also effectively inhibited formation of the complex with the CRE probe, but reduced effectiveness was observed when the NF-IL6 oligonucleotide was the competitor. Finally, unlabelled, consensus NF-kappaB oligonucleotide failed to compete for either probe. TNF-alpha treatment did not increase levels of these complexes. Thus NF-kappaB does not enhance basal or TNF-alpha-responsive PGHS-2 transcription in amnion-derived AV-3 cells. A permissive role for NF-IL6/CRE binding proteins in regulating PGHS-2 expression in these cells is indicated, but requires further clarification.

Amnion↗
PubMed1999

Cyclic AMP response element mediates dexamethasone induced suppression of prostaglandin H synthase-2 gene expression in human amnion derived WISH cells.

A human PGHS-2 promoter fragment (300 BP) linked to the luciferase reporter was used to study the regulation of PGHS-2 gene expression in human amnion-derived WISH cells. A cyclic AMP (cAMP) response element (CRE) was found to be important in the induction of PGHS-2 gene expression. This was demonstrated by showing that coexpression of CREB stimulated native but not CRE mutant promoter and that IL-1beta and PMA induced less activity with the mutant promoter as compared to the native promoter. The effect of dexamethasone on IL-1beta and PMA induced promoter activities was further examined. IL-1beta or PMA induced activity was blocked by dexamethasone, whereas IL-1beta or PMA induced mutant activity was not responsive to dexamethasone. Direct activation of CRE by a cAMP elevating agent, isoproterenol, was found to be inhibited significantly dexamethasone. These results suggest that CRE may mediate the induction of PGHS-2 by IL-1beta and PMA as well as the suppression of expression by dexamethasone in amnion-derived cells.

Amnion↗
PubMedDate not supplied

Efficacy and specificity of non-steroidal anti-inflammatory drugs for the inhibition of cytokine-stimulated prostaglandin E(2) secretion by amnion-derived WISH cells.

Prostaglandin H synthase-2 (PGHS-II) specific inhibitors have been proposed as a potential treatment in the prevention of preterm birth. We examined the efficacy of PGHS inhibitors on basal and cytokine-stimulated prostaglandin (PG) production by the amnion-like WISH cell line. WISH cells were treated with interleukin (IL)-1 beta and tumour necrosis factor (TNF)-alpha in the presence or absence of indomethacin, etodolac, 5,5-dimethy-3-(3-fluorophenyl)-4-(4-methlysulphonyl) phenyl-2 (5H)-furanone (DFU) or nimesulide (1.6-1000 nM) for 16 h. PG production was then measured using radioimmunoassay. Nimesulide and DFU were the most selective non-steroidal anti-inflammatory drugs (NSAIDs) of IL-beta-stimulated PG production in these studies with an a IC(50)(basal)/IC(50)(stimulated) ratio of, respectively, 142.2 and 113.8, followed by etodolac (25.3) and indomethacin (2.2). Similar results were obtained when cells were stimulated with TNF-alpha. The results of this study suggest that PGHS-II-selective NSAIDs may be effective in the prevention of cytokine-driven amnion PG production associated with preterm labour.

Amnion↗
PubMed1999

Regulation of cyclooxygenase-2 expression by phosphatidate phosphohydrolase in human amnionic WISH cells.

Prostaglandins are known to play a key role in the initiation of labor in humans, but the mechanisms governing their synthesis in amnion are largely unknown. In this study, we have examined the regulatory pathways for prostaglandin E(2) (PGE(2)) production during protein kinase C-dependent activation of human WISH cells. In these cells, PGE(2) synthesis appears to be limited not by free arachidonic acid availability but by the expression levels of cyclooxygenase-2 (COX-2). Concomitant with the cells being able to synthesize and secrete PGE(2), we detected significant elevations of both COX-2 protein and mRNA levels. Specific inhibition of COX-2 by NS-398 totally ablated PGE(2) synthesis. All of these responses were found to be strikingly dependent on an active phosphatidate phosphohydrolase 1 (PAP-1). Inhibition of PAP-1 activity by three different strategies (i.e. use of bromoenol lactone, propranolol, and ethanol) resulted in inhibition of COX-2 expression and hence of PGE(2) production. These data unveil a novel signaling mechanism for the regulation of PGE(2) production via regulation of COX-2 expression and implicate phosphatidate phosphohydrolase 1 as a key regulatory component of eicosanoid metabolic pathways in the amnion.

Amnion↗
PubMed2003

Sphingosine 1-phosphate in amniotic fluid modulates cyclooxygenase-2 expression in human amnion-derived WISH cells.

The metabolism of arachidonic acid, in particular the generation of prostaglandins (PGs), has been proposed to play a key role in the regulation of labor. Moreover, several extracellular proteins have been reported to modulate PG synthesis in amnion cells. In this study, we found that lipid components dissolved in the amniotic fluid modulate PG synthesis in WISH human amnion cells and identified one of these components as a sphingosine 1-phosphate (S1P). WISH cells express several S1P receptors including S1P1, S1P2, and S1P3. When WISH cells were stimulated with S1P, PGE2 synthesis increased in a concentration-dependent manner, showing maximal activity at around 100 nM. S1P treatment also caused the up-regulation of cyclooxygenase-2 (COX-2) mRNA and protein, which was apparent within 3-12 h of stimulation. In terms of the intracellular signaling pathway of S1P-induced WISH cell activation, we found that S1P stimulated two kinds of MAPK, ERK, and p38 kinase. We examined the roles of these two MAPKs in S1P-induced COX-2 expression. S1P-induced COX-2 expression was blocked completely by PD-98059 but not by SB-203580, suggesting that ERK has a critical role in the process. Transfection of S1P1 or S1P3 but not of S1P2 antisense oligonucleotide inhibited S1P-induced COX-2 expression and PGE2 production in WISH cells, indicating the involvements of S1P1 and S1P3 in the processes. This study demonstrates the physiological role of S1P in amniotic fluid and its effect on the modulation of COX-2 expression and PGs synthesis in WISH cells.

Amnion↗
PubMed2004

Modelling the influence of amnionicity on the severity of twin-twin transfusion syndrome in monochorionic twin pregnancies.

Clinical treatment for diamniotic-monochorionic twin-twin transfusion syndrome (TTTS) may include conversion of diamniotic pregnancies to a monoamniotic-monochorionic state by disrupting the amnion septum. We sought to test the underlying hypothesis, i.e. that a monoamniotic state reduces the severity of TTTS. With use of our previously developed mathematical model of two equal fetoplacental circulatory units connected by various sizes and types of placental anastomoses, we compared the haemodynamic and amniotic fluid dynamics of monoamniotic and diamniotic twins that develop TTTS. We used three anastomotic patterns that produce severe, moderate or mild forms of TTTS, respectively, in our diamniotic-monochorionic twin model. Monoamnionicity was modelled by adding the two amniotic fluid volumes and using the volume-averaged amniotic fluid osmolality. The results were as follows: for severe TTTS, small differences develop between diamniotic and monoamniotic donor twins in fetal urine production, swallowed volume, blood volume, blood pressures, net fetofetal transfusion, and blood and amniotic fluid osmolality. However, the circulatory imbalance between the monoamniotic twins deteriorates similar to that of diamniotic twins. The pathophysiological differences tend to disappear for milder TTTS. In conclusion, our model suggests that the uncommon finding of TTTS in monoamniotic twins is not due to the presence of a single amniotic sac. Rather, clinically significant differences in anastomotic patterns and the delayed or lack of identification of manifestations in monoamniotic twins account for the reduced rate of TTTS diagnosis. Based on these results we expect the clinical disruption of the amnion septum in diamniotic-monochorionic TTTS pregnancies to have only minimal benefits.

Amnion↗
PubMed2000

NF-IL6 and CRE elements principally account for both basal and interleukin-1 beta-induced transcriptional activity of the proximal 528bp of the PGHS-2 promoter in amnion-derived AV3 cells: evidence for involvement of C/EBP beta.

Prostaglandin H synthase (PGHS)-2 promoter fragments (-528 to +9 bp and 5' unidirectional deletions thereof) were cloned upstream of the chloramphenicol acetyl-transferase (CAT) reporter gene. These were transfected into amnion-derived AV3 cells. The region, -528 to -203, which includes NF-kappa B sites, had little influence on CAT expression. The region, -203 and -52, however, was responsible for most of the basal promoter activity and also conferred responsiveness to interleukin (IL)-1 beta (>3-times basal). Point mutations of NF-IL6 and cAMP response element (CRE) in this region reduced both basal and IL-1 beta-stimulated production of CAT; dual mutation eliminated IL-1 beta responsiveness. Factors in nuclear extracts from control or IL-1 beta-stimulated AV3 cells specifically complexed the NF-IL6 and CRE sequences. However, the NF-IL6 and CRE oligonucleotides cross-competed, suggesting a common factor. C/EBP beta was identified by supershift assay as interacting with both sequences. To a lesser extent C/EBP alpha and delta also interacted with the NF-IL6 site. However, CRE binding protein (CREB), was absent from the complex with the CRE. In conclusion, NF-IL6 and CRE elements principally account in AV3 amnion cells for basal and IL-1 beta-inducible transcriptional activity of the proximal 528 bp of the PGHS-2 promoter, while NF-kappa B elements play no substantial role. C/EBPs, particularly C/EBPbeta, are implicated in control of PGHS-2 transcription through the NF-IL6 and CRE sites.

Amnion↗
PubMed2001

Apoptosis in the normal human amnion at term, independent of Bcl-2 regulation and onset of labour.

This study was designed to detect apoptosis in the human amnion and to elucidate the signalling pathway involved in its regulation. Samples of human amnion were obtained from 34 women (weeks 11-42 of gestation) and studied using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) method with light microscopy (LM) and transmission electron microscopy (TEM). Apoptotic regulators in the samples were studied by immunohistochemistry and caspase activity assay. The TUNEL method with LM demonstrated that the percentage of TUNEL-positive cells in the amniotic epithelium was the highest in weeks 40-41 of gestation (P < 0.05) independent of the onset of labour, and the cells were often detached from the epithelium into the amniotic cavity at term. The TUNEL method with TEM clearly showed the characteristic features of apoptosis such as the nuclear condensed chromatin with abundant free 3'-OH DNA ends, cell shrinkage and a decrease in the number of desmosomes, except for the presence of apoptotic bodies. Fas and Fas ligand (FasL) were constantly expressed on apical membranes of amniotic epithelial cells from weeks 16-27 through to 40-41 of gestation, while no Bcl-2 expression was observed throughout the gestational periods. Activities of caspase-3 and caspase-8, but not of caspase-9, were higher in weeks 40-41 than those from weeks 16-27 of gestation (P < 0.01). We conclude that apoptosis in term amniotic epithelium is independent of Bcl-2 regulation and onset of labour, and may play an important role in the fragility and rupture of human fetal membranes at term.

Amnion↗
PubMed2003

The effects of labour and of interleukin 1 beta upon the expression of nuclear factor kappa B related proteins in human amnion.

Human labour is associated with persistently increased nuclear factor kappa B (NF-kB) activity in amnion. In this study we have shown that this involves only the p65 and p50 NF-kB subunits and is associated with an increase in the expression of p65 (P < 0.05), and of the NF-kB binding proteins IkBa, IkBb-1 and IkBb-2 (P < 0.05). Interleukin-1b stimulation leads to rapid degradation and resynthesis of IkBa within 2 h, and a decrease in IkBb-1 without a return to full expression by 2 h, but has little effect upon IkBb-2. IkBb-2 was found in both the cytosolic and nuclear protein fractions. These findings demonstrate that persistently increased NF-kB activity in amnion occurs despite increased expression of the inhibitory IkBa protein and is not mediated by persistant I-kappa kinase activity or inhibition of IkBa synthesis. The increased expression and nuclear localization of IkBb-2 suggests that its function may be to protect NF-kB from inactivation by IkBa and to maintain NF-kB-mediated gene transcription.

Amnion↗
PubMed1991

Acidic glycosphingolipids of human amnion.

Six major acidic glycosphingolipids were isolated from human amnion using DEAE Sephadex A-25 and silica beads column chromatography. The structures of these glycosphingolipids were determined by methylation analysis, TLC immunostaining and/or negative ion FAB-MS, and were concluded to be II3 alpha NeuAcLacCer(GM3), IV3 alpha NeuAcnLc4-Cer (sialyl[alpha 2-3]paragloboside), IV6 alpha NeuAcnLc4Cer (sialyl[alpha 2-6]paragloboside), IV3 alpha NeuAcIII4 alpha FucLc4Cer (sialyl Lea), VI3 alpha NeuAcnLc6Cer (i-ganglioside) and II3 alpha (NeuAc alpha 2----8NeuAc)LacCer (GD3). In addition, several minor glycosphingolipids were detected with specific monoclonal antibodies, including glycolipids with NeuAc alpha 2-3Gal beta 1-4GlcNAc-beta 1- or NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1- determinant. Our results show that the glycosphingolipids of human amnion are characterized by having mainly type II chain analogues and onco-fetal antigens.

Amnion↗
PubMed2004

Epidermal growth factor and interleukin-1beta utilize divergent signaling pathways to synergistically upregulate cyclooxygenase-2 gene expression in human amnion-derived WISH cells.

In human parturition, uterotonic prostaglandins (PGs) arise predominantly via increased expression of cyclooxygenase-2 (COX-2 [also known as prostaglandin synthase 2]) within intrauterine tissues. Interleukin-1 (IL-1) and epidermal growth factor (EGF), both inducers of COX-2 transcription, are among numerous factors that accumulate within amniotic fluid with advancing gestation. It was previously demonstrated that EGF could potentiate IL-1beta-driven PGE(2) production in amnion and amnion-derived (WISH) cells. To define the mechanism for this observation, we hypothesized that EGF and IL-1beta might exhibit synergism in regulating COX-2 gene expression. In WISH cells, combined treatment with EGF and IL-1beta resulted in a greater-than-additive increase in COX-2 mRNA relative to challenge with either agent independently. Augmentation of IL-1beta-induced transactivation by EGF was not observed in cells harboring reporter plasmids bearing nuclear factor-kappa B (NFkappaB) regulatory elements alone, but was evident when a fragment (-891/ +9) of the COX-2 gene 5'-promoter was present. Both agents transiently activated intermediates of multiple signaling pathways potentially involved in the regulation of COX-2 gene expression. The 26 S proteasome inhibitor, MG-132, selectively abrogated IL-1beta-driven NFkappaB activation and COX-2 mRNA expression. Only pharmacologic blockade of the p38 mitogen-activated protein kinase eliminated COX-2 expression following EGF stimulation. We conclude that EGF and IL-1beta appear to signal through different signaling cascades leading to COX-2 gene expression. IL-1beta employs the NFkappaB pathway predominantly, while the spectrum of EGF signaling is broader and includes p38 kinase. The synergism observed between IL-1beta and EGF does not rely on augmented NFkappaB function, but rather, occurs through differential use of independent response elements within the COX-2 promoter.

Amnion↗
PubMed2005

Modulation of cytokine-induced cyclooxygenase 2 expression by PPARG ligands through NFkappaB signal disruption in human WISH and amnion cells.

Cyclooxygenase (COX) activity increases in the human amnion in the settings of term and idiopathic preterm labor, contributing to the generation of uterotonic prostaglandins (PGs) known to participate in mammalian parturition. Augmented COX activity is highly correlated with increased COX2 (also known as prostaglandin-endoperoxide synthase 2, PTGS2) gene expression. We and others have demonstrated an essential role for nuclear factor kappaB (NFkappaB) in cytokine-driven COX2 expression. Peroxisome proliferator-activated receptor gamma (PPARG), a member of the nuclear hormone receptor superfamily, has been shown to antagonize NFkappaB activation and inflammatory gene expression, including COX2. We hypothesized that PPARG activation might suppress COX2 expression during pregnancy. Using primary amnion and WISH cells, we evaluated the effects of pharmacological (thiazolidinediones) and putative endogenous (15-deoxy-Delta(12,14)-prostaglandin J2, 15d-PGJ2) PPARG ligands on cytokine-induced NFkappaB activation, COX2 expression, and PGE2 production. We observed that COX2 expression and PGE2 production induced by tumor necrosis factor alpha (TNF) were significantly abrogated by 15d-PGJ2. The thiazolidinediones rosiglitazone (ROSI) and troglitazone (TRO) had relatively little effect on cytokine-induced COX2 expression except at high concentrations, at which these agents tended to increase COX2 abundance relative to cells treated with TNF alone. Interestingly, treatment with ROSI, but not TRO, led to augmentation of TNF-stimulated PGE2 production. Mechanistically, we observed that 15d-PGJ2 markedly diminished cytokine-induced activity of the NFkappaB transcription factor, whereas thiazolidinediones had no discernable effect on this system. Our data suggest that pharmacological and endogenous PPARG ligands use both receptor-dependent and -independent mechanisms to influence COX2 expression.

Amnion↗