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PubMed1993

Protein kinase A activators inhibit agonist induced prostaglandin production in human amnion.

Prostaglandin (PG) production by human amnion has been postulated to have a role in the onset of labor. Previous work by ourselves and others has demonstrated that oxytocin, phorbol esters and epidermal growth factor (EGF) increase PGE2 production in human amnion cells by activation of the Phospholipase C/Protein Kinase C (PKC) cascade system. The present study was undertaken to determine the effect of prior activation of the Adenylate Cyclase cascade system upon subsequent stimulation of PGE2 production by oxytocin, phorbol 12-myristate-13-acetate (PMA) or EGF in amnion cells and membrane discs. Isoproterenol, forskolin and dibutyryl cyclic adenosine monophosphate (dbcAMP) were utilized to activate the Adenylate Cyclase system at the receptor, enzyme and second messenger level. In control amnion cells, oxytocin, PMA and EGF each provoked dose dependent increases in PGE2 production. In cells preincubated with dbcAMP, forskolin or isoproterenol, agonist stimulated PGE2 production was markedly (50-90%) inhibited (p < 0.01). Inhibition was dose dependent upon preincubator concentrations. Maximal inhibition by adenylate cyclase activators occurred with 2-4 h of preincubation. In membrane discs, forskolin preincubation also inhibited oxytocin, PMA and EGF stimulation of PGE2 production. Activation of the Adenylate Cyclase system in human amnion cells or membrane discs inhibits the subsequent action of potent stimulators of PGE2 production in human amnion.

Adenylyl Cyclases↗
PubMed2005

Labor-associated regulation of prostaglandin E and F synthesis and action in the ovine amnion and cervix.

OBJECTIVE: Prostaglandins (PGs) are key regulators of cervical dilatation and membrane breakdown at the onset of labor. PG synthase and receptor expression has been previously documented in uterine tissues; however, mechanisms governing the changes occurring in the cervix and amnion are less well established. The aim of the current study was to determine the level of expression of PG synthetic enzymes and receptors in these tissues in association with induced labor in sheep. METHODS: Labor was induced in sheep at 135 days of gestation by continuous fetal dexamethasone infusion. Amnion and cervical tissue was obtained before and after labor for measurement of mRNA encoding enzymes (cytosolic phospholipase A2 [cPLA2], PGH synthase-2 [PGHS-2], PGF synthase [PGFS], and PGE synthase [PGES]) and receptors (FP and EP1-4) by real-time polymerase chain reaction (PCR). RESULTS: cPLA2 expression increased significantly in cervical tissue at labor onset, whereas expression of the other enzymes measured did not change. There was a marked rise in EP3 expression in the cervix, but abundance of this receptor was lower than EP2 and FP expression, which did not change. The amnion exhibited a labor-associated decrease in PGHS-2, PGFS, and FP mRNA expression. CONCLUSION: The regulation of PG synthesis and action occurring in the amnion and cervix in association with labor appear to differ markedly between the two tissues, indicating tissue-specific roles for PGs. The data support a role for increased PG synthesis and action in the cervix and suggest a decrease in PG production and action in the amnion, in sharp contrast to the pattern reported in human amnion.

Amnion↗
PubMed2006

Aquaporin 3 expression in human fetal membranes and its up-regulation by cyclic adenosine monophosphate in amnion epithelial cell culture.

OBJECTIVE: The cell membrane water channel protein aquaporins (AQPs) may be important in regulating the intramembranous (IM) pathway of amniotic fluid (AF) resorption. The objective of the present study was to determine whether aquaporin 3 (AQP3) is expressed in human fetal membranes and to further determine if AQP3 expression in primary human amnion cell culture is regulated by second-messenger cyclic adenosine monophosphate (cAMP). METHODS: AQP3 expression in human fetal membranes of normal term pregnancy was studied by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). To determine the effect of cAMP on AQP3 expression, primary human amnion cell cultures were treated in either heat-inactivated medium alone (control), or heat-inactivated medium containing: (1) SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP agonist, or (2) forskolin, an adenylate cyclase stimulator. Total RNA was isolated and multiplex real-time RT-PCR employed for relative quantitation of AQP3 expression. RESULTS: We detected AQP3 expression in placenta, chorion, and amnion using RT-PCR. Using IHC, we identified AQP3 protein expression in placenta syncytiotrophoblasts and cytotrophoblasts, chorion cytotrophoblasts, and amnion epithelia. In primary amnion epithelial cell culture, AQP3 mRNA significantly increased at 2 hours following forskolin or SP-cAMP, remained elevated at 10 hours following forskolin, and returned to baseline levels by 20 hours following treatment. CONCLUSION: This study provides evidence of AQP3 expression in human fetal membranes and demonstrates that AQP3 expression in primary human amnion cell culture is up-regulated by second-messenger cAMP. As AQP3 is permeable to water, urea, and glycerol, modulation of its expression in fetal membranes may contribute to AF homeostasis.

Amnion↗
PubMedDate not supplied

Differential gene expression in the amnion, chorion, and trophoblast of the human placenta.

Human chorionic gonadotrophin (hCG), placental alkaline phosphatase (PLAP), and pregnancy-specific glycoprotein (PSG) are three major proteins produced by the trophoblast of the human placenta. Immunocytochemical studies suggest that PSG and hCG are also present in the human amnion. In this study, we examined whether amniotic and chorionic membranes were capable of expressing trophoblastic-specific genes. As previously reported, trophoblasts express high levels of hCG beta, hCG alpha, PLAP, and PSG. Both amnion and chorion were found to express PLAP and hCG beta mRNA. However, the hCG alpha transcript was expressed only by the amnion, but not by the chorion in the term placenta. Recent molecular cloning studies indicate that human PSGs are a group of closely related placental proteins that, together with the carcinoembryonic antigen family members, comprise a subfamily within the immunoglobulin superfamily. To demonstrate that amnion and chorion also express PSG transcripts, we employed ribonuclease protection analysis using probes specific to the 5' and 3' region of PSG mRNAs. Our data indicate that while amniotic as well as chorionic membrane expressed low levels of the PSG genes, only a certain subpopulation of PSG transcripts were expressed. Furthermore, the amnion and chorion demonstrated differences in PSG species expression from each other and from trophoblastic tissue. Thus, human amnion, chorion and trophoblast selectively express several placental genes.

Alkaline Phosphatase↗
PubMed1999

Adhesion of shed menstrual tissue in an in-vitro model using amnion and peritoneum: a light and electron microscopic study.

We have investigated the adhesion of endometrial tissue isolated from antegradely shed menstrual effluent to amnion and peritoneum. This endometrial tissue was cultured overnight on either side of intact and stripped amnion and on the mesothelial side of peritoneum. Light and electron microscopy were applied to evaluate adhesion. With light microscopy adhesion of endometrial fragments to stripped membranes was observed in nine out of 12 specimens and in 12 out of 13 specimens when layered on the extracellular matrix side of amnion. Adhesion when layered on the epithelial side was seen in only four out of 13 specimens. However, when using scanning electron microscopy adhesion of menstrual endometrial tissue could be visualized in all samples. Numerous adhering fragments were seen when layered on the extracellular matrix side of untreated amnion. On several occasions not only adhesion but also spreading of cells was observed. When layered on the epithelial side of untreated amnion or peritoneum, adhesion was exclusively seen at locations where the epithelium was damaged or absent. These findings were confirmed by transmission electron microscopy. These observations indicate that endometrial tissue isolated from antegradely shed menstrual effluent preferentially adheres to subepithelial structures of amnion and peritoneum. The lack of adhesion to epithelial cells suggests that an intact mesothelial lining prevents adhesion of menstrual endometrial tissue.

Amnion↗
PubMed2004

Engraftment potential of human amnion and chorion cells derived from term placenta.

BACKGROUND: Fetal membranes are tissues of particular interest for several reasons, including their role in preventing rejection of the fetus and their early embryologic origin. which may entail progenitor potential. The immunologic reactivity and the transplantation potential of amnion and chorion cells, however, remain to be elucidated. METHODS: Amnion and chorion cells were isolated from human term placenta and characterized by immunohistochemistry, flow cytometric analysis, and expression profile of relevant genes. The immunomodulatory characteristics of these cells were studied in allogeneic and xenogeneic mixed lymphocyte reactions and their engraftment potential analyzed by transplantation into neonatal swine and rats. Posttransplant chimerism was determined by polymerase chain reaction analysis with probes specific for human DNA. RESULTS: Phenotypic and gene expression studies indicated mesenchymal stem cell-like profiles in both amnion and chorion cells that were positive for neuronal, pulmonary, adhesion, and migration markers. In addition, cells isolated both from amnion and chorion did not induce allogeneic nor xenogeneic lymphocyte proliferation responses and were able to actively suppress lymphocyte responsiveness. Transplantation in neonatal swine and rats resulted in human microchimerism in various organs and tissues. CONCLUSIONS: Human amnion and chorion cells from term placenta can successfully engraft neonatal swine and rats. These results may be explained by the peculiar immunologic characteristics and mesenchymal stem cell-like phenotype of these cells. These findings suggest that amnion and chorion cells may represent an advantageous source of progenitor cells with potential applications in a variety of cell therapy and transplantation procedures.

Amnion↗
PubMed1994

Interleukin-1 receptor antagonist (IL-1ra) production by human amnion, chorion, and decidua.

PROBLEM: This study was conducted to determine whether (1) conditioned media from unstimulated primary cultures of human amnion, chorion, or decidua contain detectable concentrations of IL-1ra in vitro, and (2) bacterial endotoxin (LPS), tumor necrosis factor-alpha (TNF-alpha), or IL-1-beta (IL-1 beta) stimulate amnion, chorion, or decidua to produce increased amounts of IL-1ra. METHOD: Placentae were obtained from women at term with intact membranes before the onset of labor. Amnion, chorion, and decidual cells were isolated by standard procedures and grown to confluence. Cells were then cultured in quadruplicate for 16 h in tissue culture medium supplemented with 10% fetal calf serum or, additionally, with various concentrations of Escherichia coli LPS, TNF-alpha, or IL-1 beta. Culture supernatants were collected, and concentrations of IL-1ra were quantitated by a sensitive and specific enzyme-linked immunosorbent assay for IL-1ra. RESULTS: Results showed that primary cultures of amnion and chorion from 4 of 9 and decidua from 10 of 12 placentae had detectable rates of production of IL-1ra (ranges: 0.08-6.5, 0.42-12.1, and 1.55-96.5 pg IL-1ra/microgram protein/16 h, respectively). In addition, LPS (10-1,000 ng/ml) and IL-1 beta (0.1-10 ng/ml), but not TNF-alpha (0.01-100 ng/ml), stimulated decidual cells to release/secrete increased amounts of IL-1ra compared with media alone (range: 2.5-400 pg IL-1ra/microgram protein/16 h, P < 0.0001). In contrast, neither LPS, TNF-alpha, or IL-1 beta could stimulate amnion or chorion to release/secrete IL-1ra. CONCLUSIONS: These results indicate (1) that amnion, chorion, and predominantly decidua, can release or secrete IL-1ra in vitro, and (2) that LPS and IL-1 beta can stimulate decidual cells to produce increased amounts of IL-1ra.

Amnion↗
PubMed2006

Use of amnion and placenta in neonatal screening for canine GM1-gangliosidosis and the risk of diagnostic misclassifications.

BACKGROUND: A closed breeding colony of Shiba dogs with GM1-gangliosidosis is maintained at Hokkaido University (Sapporo, Japan). Neonatal genotyping is essential to control the breeding colony genetically as an animal model for the human disease. OBJECTIVES: The purpose of the present study was to determine the utility of amnion and placenta in the neonatal screening or diagnosis for canine GM1-gangliosidosis. METHODS: Twenty neonatal Shiba dogs of a pedigree with GM1- gangliosidosis were differentiated into 3 genotypes--normal, heterozygous, and affected dogs--by using a previously reported DNA mutation assay. Acid beta-galactosidase activity was measured in amnion and placenta and compared among the 3 genotypes. RESULTS: The level of beta-galactosidase activity in the amnion of affected dogs was negligible and <2% of the mean activity in normal dogs; there was no significant difference among the 3 genotypes. In placenta, beta-galactosidase activity was significantly different among all the genotypes; however, there was wide overlap in enzyme activity between normal and heterozygous dogs. The level of activity in affected dogs was relatively high and >10% of the mean activity in normal dogs. The DNA mutation assay gave correct information about genotype with genomic DNA extracted from amnion but ambiguous information with DNA from placenta. CONCLUSIONS: Amnion and placenta were not useful as enzyme sources in neonatal screening in canine GM1-gangliosidosis because of the risk of misdiagnosis. DNA from amnion is applicable as a template for genotyping, whereas placenta should not be used because canine placenta contains maternal cells.

Amnion↗
PubMed1990

Effects of glucocorticoids on prostaglandin formation by human amnion.

The human amnion may be an important source of prostaglandins involved in the onset of human labor and therefore it is important to define the factors that regulate their formation in this tissue. In the present study we demonstrate that glucocorticoids inhibit prostaglandin production by freshly isolated amnion cells. The inhibitory action of the glucocorticoids, however, changes to a stimulatory action when the cells are maintained in primary culture for a few days. For both inhibition and stimulation, concentrations of 10(-8) M dexamethasone or greater were required to give significant effects, and estradiol and progesterone had no effect on the prostaglandin output of the cells. Epidermal growth factor (EGF), which has previously been found to stimulate prostaglandin output by confluent amnion cells, did not alter prostaglandin output of cells initially placed in culture. Furthermore, the stimulatory action of EGF and dexamethasone appeared additive. The calcium ionophore A23187 stimulated prostaglandin output in freshly isolated cells and accentuated the inhibitory effect of dexamethasone. These studies indicate that prostaglandin formation by human amnion during pregnancy could be regulated by glucocorticoids. These steroids are easily available to the amnion by way of cortisone conversion to cortisol by the maternal decidua. The results also indicate that amnion is capable of responding to glucocorticoids in both a stimulatory and inhibitory fashion and whether one or both actions are of importance in vivo is a question that is as yet unresolved.

Amnion↗
PubMedDate not supplied

Repair kinetics of amnion cells after microsurgical injury.

OBJECTIVE: There is a paucity of data regarding healing of fetal membranes. We assessed the repairing ability of a microsurgically-injured monolayer of amnion-derived cells compared to an endothelial cell line. MATERIALS AND METHODS: Amnion-derived cells (FL cells) were grown to confluence in 10% fetal calf serum (FCS). A microsurgical incision was performed under an inverted microscope. The area of each incision was measured at times 0, 6, 12 and 24 h using MCID M4 image analysis software. The experiments were repeated using 1% FCS. The observations were also made replacing the media at 6 and 12 h. Umbilical-cord-derived endothelial cells were used for comparison. The rate of repair of the incision was measured using three methods: (a) absolute closure rate (ACR): (A0-A1)/T, where A0 is the original incisional area, and A1 is the new area at interval T: (b) relative percentage rate (RPR): (A0-A1)/A0/T x 100, and (c) healing rate (HR): (A0-A1)/A0 x 100. RESULTS: Amnion cells were capable of repairing the microsurgical defect. The ACR decreased over time, and was higher with larger defects. A lower concentration of FCS nor the addition of fresh media altered the repair process significantly. Endothelial cells were significantly faster than amnion cells or amnion-supplemented cells with endothelial media. The RPR remained relatively constant for all groups, suggesting Gompertzian kinetics. CONCLUSIONS: Amnion cells are capable of repairing a surgical defect at a relatively constant percent rate, but are slower than an endothelial cell line. The decreased rate of closure over time may be due to relative contact inhibition. Further studies will concentrate on the molecular and cellular mechanisms involved in this process.

Amnion↗
PubMedDate not supplied

Modulators of prostaglandin E2 synthesis in human amnion.

OBJECTIVE: The purpose of these studies was to determine the effects of the essential fatty acid, linoleic acid, and the commonly used non-steroidal anti-inflammatory agents, aspirin and acetaminophen, on the rate of prostaglandin (PG) biosynthesis by human amnion cells. METHODS: Amnion cells were isolated from term, normal pregnancies and grown to confluence. Cells were incubated with control or medium containing 100 mumol/L linoleic acid. Cells were also incubated with control medium or medium containing 10 or 100 micrograms/mL aspirin or acetaminophen. RESULTS: Following an initial delay, amnion cells exposed to linoleic acid exhibited a significant increase in PGE synthesis. Both aspirin and acetaminophen in clinically relevant concentrations had a significant inhibitory effect on amnion cell PGE synthesis. CONCLUSIONS: Linoleic acid has a stimulatory effect and aspirin and acetaminophen have an inhibitory effect on PGE synthesis in human amnion cells in culture. We speculate that dietary habits, supplement ingestion, and over-the-counter drug use may affect amnion cell PG production. In view of the potential importance of intrauterine PG production in normal and abnormal labor, further study in this area is indicated.

Acetaminophen↗
PubMed1992

Molecular size characterization of oxytocin receptors in rabbit amnion.

The binding of oxytocin (OT) to receptors in rabbit amnion cells stimulates PGE2 release. We previously studied the binding characteristics, changes in receptor concentration during pregnancy, and agonist specificity of OT action on amnion cells. In this study the molecular size of OT receptors in rabbit amnion was estimated by photoaffinity labeling, radiation inactivation, and gel filtration of solubilized receptor, using an iodinated OT antagonist, [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid, 2-O-methyltyrosine,4-threonine,8-ornithine,9-tyrosylamide]vasotoci n (OTA), or [3H]OT. Two electrophoretic bands, about 50 and 65 kilodaltons (kDa), were specifically covalently labeled with azidobenzoyl-[125I]OTA. Both sizes correspond to that determined by radiation inactivation, about 55 kDa, using [3H]OT binding to assess the fraction of receptor sites remaining. When we used [125I]OTA, the radiation inactivation size was about 30 kDa. These differences in radiation inactivation size suggest that the receptor binding site is comprised of more than one domain and that the binding of the antagonist involves fewer points of interaction than does OT. The molecular size of the receptor estimated from [125I]OTA binding by detergent-solubilized extracts of amnion membranes was about 350 kDa, as determined by gel filtration on columns of Sepharose 6B. Although the functional size of the receptor is about 65 kDa, it appears to be closely associated with other membrane proteins. The size estimates of amnion OT receptors agree with those in rabbit myometrium and rat mammary gland, both of which differ from amnion by contracting in response to OT. Despite different responses, OT receptors in different tissues appear to be very similar in size.

Amnion↗
PubMed1993

Up-regulation of oxytocin receptors in rabbit amnion by adenosine 3',5'-monophosphate.

The marked up-regulation of oxytocin (OT) receptors in rabbit amnion at term was reproduced in cultured amnion cells by raising intracellular cAMP levels. (Bu)2AMP, forskolin, or cholera toxin caused 2- to 8-fold increases in specific binding of iodinated OT antagonist. The rise in OT receptors involves activation of protein kinase-A activity and protein synthesis, as forskolin's effects were inhibited by H-7 and H-8 and by cycloheximide, respectively. Forskolin treatment also increased specific cross-linking of a photoaffinity derivative of [125I]OT antagonist to a 50-kilodalton electrophoretic band corresponding in size to the amnion OT receptor. Forskolin and (Bu)2cAMP increased OT stimulation of prostaglandin E2 (PGE2) release; PGE2 release elicited by epidermal growth factor or calcium ionophore was unchanged. Forskolin also enhanced stimulation of PGE2 synthesis by phorbol 12-myristate 13-acetate, an activator of protein kinase-C. Because protein kinase-C mediates OT action in amnion cells, forskolin causes increases in both the signal and signal transduction mechanisms. These results suggest that cAMP mediates the exponential-like rise in rabbit amnion OT receptors occurring in vivo at term. The physiological signals increasing cAMP concentrations in amnion may be important for OT stimulation of PGE2 release and, therefore, have a significant role in the initiation and/or progression of labor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Renin increases human amnion cell prostaglandin E2 biosynthesis.

Chorionic cells are known to produce several protein hormones; among them is prorenin/renin, whose function is unknown at this time. Amnion is contiguous with chorion and plays a part in the mechanism(s) of parturition through increased prostaglandin (PG) production. The purpose of the present study was to determine whether renin has any action on amnion cell PGE2 biosynthesis. Amnion cells in primary monolayer culture were incubated for 16 h with increasing concentrations of renin. Renin induced a concentration-dependent increase in amnion cell PGE2 production (e.g. in picograms of PGE2 per microgram protein/16 h; mean +/- SEM; n = 4; control, 3.01 +/- 0.15; 0.0001 U/mL renin, 9.66 +/- 2.0; 0.001 U/mL renin, 10.36 +/- 1.91; 0.01 U/mL renin, 10.3 +/- 3.36; 0.1 U/mL renin, 13.82 +/- 2.1). Significant stimulation of amnion cell PGE2 by renin is not observed until 2 h of incubation; stimulation continues a further 6 h, with little change in the following 8 h. We tested the possibility that renin's stimulatory effects were due to angiotensin-I (AI) and angiotensin-II (AII) formation by testing the effects of AI and AII directly and that of renin in the presence of saralasin, a potent antagonist of AII action. Saralasin did not inhibit the effect of renin, nor was AI or AII alone (10(-10)-10(-6) M) stimulatory. Thus, we believe that chorionic renin may have a novel role in the regulation of amnion cell PGE2 production that is independent of angiotensin formation.

Amnion↗
PubMed1993

Protein kinase-C stimulatory activity in human amnion cytosol.

Cytosolic preparations from human amnions at term were tested for the presence of endogenous modulators of protein kinase-C (PKC) activity. Tissues were obtained from 14 patients undergoing cesarean section (CS) and 14 patients after spontaneous delivery (SL). PKC activity was significantly greater in cytosols from CS than SL amnion (1.65 +/- 0.04 vs 0.73 +/- 0.2 pmol/min, respectively; mean +/- SE; n = 14 CS; n = 14 SL; P < 0.05). When amnion cytosols were mixed with a control preparation of PKC (rat brain cytosol partially purified on diethylaminoethyl), PKC activity was significantly increased compared to the control value (control, 12.81 +/- 2.1; control + CS, 22.19 +/- 1.5; control + SL, 21.98 +/- 0.7 pmol/min). The stimulation of PKC was dose dependent. The PKC stimulatory factor in amnion cytosol was stable to heat treatment at 80-90 C for 2 min (control + heat-treated CS, 23.20 +/- 1.2; control + heat-treated SL, 24.49 +/- 1.0 pmol/min) and substituted for phosphatidylserine and diacylglycerol in the PKC assay (control, no lipids, 0.05 +/- 0.04 pmol/min; control + amnion cytosol, no lipids, 9.60 +/- 1.06 pmol/min). The PKC stimulatory factor was calcium dependent, was not extractable in organic solvents, and was greater then 100,000 mol wt. Thus, the human amnion contains a PKC stimulatory factor which may modify or mediate the cellular response to extracellular stimulators of the PKC pathway.

Amnion↗
PubMed1994

Prostaglandin endoperoxide-H synthase (PGHS) activity and immunoreactive PGHS-1 and PGHS-2 levels in human amnion throughout gestation, at term, and during labor.

Prostaglandins (PGs) are of primary importance in the initiation and maintenance of labor in women. A major intrauterine source of prostaglandins is the amnion, which synthesizes increased amounts of PGE2 at term labor. Because PG endoperoxide-H synthase (PGHS) catalyzes the rate-limiting step of PG synthesis from arachidonic acid, we investigated the changes in amniotic PGHS specific activity during gestation and at term and preterm labor. Also, we determined the level of immunoreactive PGHS protein in the amnion to evaluate the mechanisms by which PGHS activity may be regulated. PGHS specific activity, measured at the amount of PGE2 produced by amnion microsomes under optimal conditions, was 18.2 +/- 3.7 pg PGE2/micrograms protein.min (mean +/- SE; n = 19) at term (37-42 weeks gestation) before the spontaneous onset of labor. PGHS specific activity was significantly higher after spontaneous term labor (38.9 +/- 6.0 pg PGE2/micrograms protein.min; n = 19; P < 0.05). Amnion samples from preterm (< 36 weeks gestation) nonlaboring patients contained low levels of PGHS specific activity (5.9 +/- 1.8 pg PGE2/micrograms protein.min; n = 9), which increased significantly with spontaneous preterm labor (28.3 +/- 6.8 pg PGE2/micrograms protein.min; n = 10; P < 0.05). Longitudinal analysis of the data showed that PGHS specific activity was low in the first and second trimesters of gestation, but increased dramatically before labor onset at term. We detected PGHS protein in all microsomal samples, with an antiovine PGHS antibody recognizing both PGHS-1 and -2 isoforms of the enzyme. However, there was no correlation between PGHS specific activity and the amount of immunoreactive PGHS protein. Using an antibody specific for PGHS-2, we detected immunoreactive protein in only 9 of the 25 tissues examined and found no correlation between PGHS specific activity and the amount of PGHS-2 protein. These results suggest that 1) PGHS specific activity in the amnion increases sharply before the onset of labor at term; 2) further increases in specific activity occur during term and preterm labor; and 3) the specific activity of PGHS in the amnion is not related directly to the amount of immunoreactive enzyme protein.

Amnion↗
PubMed1994

Transforming growth factor-beta stimulates, and glucocorticoids and epidermal growth factor inhibit brain natriuretic peptide secretion from cultured human amnion cells.

We previously reported the massive secretion of brain natriuretic peptide (BNP) from human amnion cells and suggested the possible role of BNP in the maintenance of human pregnancy. In this study, to elucidate the regulatory mechanism of BNP secretion from amnion cells, we measured the BNP level in the culture medium of amnion cells by RIA after incubation in the presence of various substances. Among the agents examined, cortisol (1 x 10(-7) to 1 x 10(-6) mol/L), dexamethasone (1 x 10(-8) to 1 x 10(-6) mol/L), and epidermal growth factor (EGF; 2 x 10(-11) to 2 x 10(-8) mol/L) inhibited BNP secretion from the cultured amnion cells in a dose-dependent manner. By contrast, transforming growth factor-beta (TGF beta; 4 x 10(-11) to 4 x 10(-9) mol/L) caused a 3- to 5-fold increase in BNP secretion. TGF beta-augmented BNP secretion was abolished by the addition of cortisol or EGF to the culture medium. Moreover, in this study, we revealed the presence of bioactive TGF beta in human amniotic fluid (approximately 4 x 10(-10) mol/L). The present finding of tight regulation of BNP secretion from amnion cells by cortisol, EGF and TGF beta, all at the concentrations physiologically present in human amniotic fluid, implies a physiological role of BNP secretion from amnion cells in the pregnant uterus.

Amnion↗
PubMed2002

Effect of Astragali radix extract on lipopolysaccharide-induced inflammation in human amnion.

The effects of Astragali radix extract on interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha productions, prostaglandin E2 (PGE2) biosynthesis, and leukotriene C4 (LTC4) production from lipopolysaccharide (LPS)-stimulated human amnion cells were investigated. Amnion cells produced detectable amounts of both IL-6 and TNF-alpha under LPS-stimulated conditions. Astragalus extract inhibited the production of IL-6. However, TNF-alpha production was not inhibited by the extract on L929 cytotoxicity assay. Treatment of amnion cells with LPS for up to 24 h resulted in an increase in PGE2 release in a concentration- and time-dependent manner. The extract (150 mg/ml) significantly inhibited the output of PGE2 by amnion cells (p<0.01). The arachidonate lipoxygenase metabolite (LTC4) was increased by LPS treatment of amnion cells. Astragalus extract (30 mg/ml) inhibited LTC4 production by approximately 65% throughout the culture period. These results suggest that Astragali radix extract may have a role in inhibiting bacterial infection-associated preterm labor by suppressing the productions of IL-6, PGE2, and LTC4 by human amnion cells.

Amnion↗