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PubMed1995

Interleukin-1 beta induces the synthesis and activity of cytosolic phospholipase A2 and the release of prostaglandin E2 in human amnion-derived WISH cells.

The objective of this study was to examine the expression and activity of cytosolic phospholipase A2 (cPLA2) in relation to prostaglandin E2 (PGE2) synthesis in human amnion-derived WISH cells in response to stimulation by interleukin-1 beta (IL-1 beta). cPLA2 activity was characterized by sensitivity to heat and acid treatment, stability to dithiothreitol, and inhibition by the specific inhibitor, arachidonyl trifluoromethyl ketone (AACOCF3). Treatment of WISH cells with IL-1 beta (0.01-1 ng/mL) for up to 24 h resulted in a significant increase in PGE2 release in a concentration- and time-dependent manner accompanied by increases both in total cellular cPLA2 activity and in cPLA2 protein levels detected by Western blot analysis. The parallel increase in total cellular cPLA2 activity and cPLA2 protein level indicates that IL-1 beta may induce the synthesis of cPLA2. Incubation of the cells with 10 microM AACOCF3 for 24 h significantly inhibited IL-1 beta-induced PGE2 production strongly suggesting that cPLA2 mediates IL-1 beta-induced PGE2 formation. In unstimulated cells, there is appreciable total cellular cPLA2 activity and protein, but these cells produce low amounts of PGE2 until stimulated by IL-1 beta, suggesting that cPLA2 translocation from cytosol to the membrane is necessary for its bioactivity. In contrast to IL-1 beta, treatment with phorbol ester (12-O-tetradecanoyl phorbol-13-acetate, TPA, 10(-10)-10(-6)M) for 24 h significantly inhibited total cellular cPLA2 activity in a concentration-dependent manner. The amount of total cellular cPLA2 protein seen on Western blot remained unchanged following TPA treatment. These data suggest that in WISH cells, IL-1 beta induces both translocation to the membrane and de novo synthesis of cPLA2 protein to sustain prostaglandin (PG) synthesis. In contrast, TPA may only cause cPLA2 translocation but no increase in cPLA2 protein synthesis, resulting in limited PG synthesis. Our results provide a mechanism for the effect of IL-1 beta on prostaglandin synthesis in human amnion cells and provide support for a role of cPLA2 in the mechanism initiating human parturition.

Amnion↗
PubMed1986

Monoclonal antibodies to human amnion.

Mouse hybridoma cell lines secreting monoclonal antibodies to human amnion were established. The reactivities of eight of these monoclonal antibodies (GB1, GB3, GB4, GB5, GB6, GB9, GB10 and GB11) on human skin and term extra-embryonic tissues, which included reflected amniochorions, basal plates, placentae, chorionic plates and umbilical cords, are reported. GB1, GB4, GB5, GB6, GB9 and GB11 showed various reactivity patterns on the epithelial cells of amnion, chorion and skin at different stages of differentiation. In addition, GB9 and GB11 showed extracellular reactivities; GB9 detected chorionic villi which were usually surrounded by fibrinoid and GB11 reacted with fibrinoid structures in the placentae and chorion laeve. GB10 recognized connective tissues in fetal mesenchyme and adult dermis. This study demonstrates the expression of many shared antigens between tissues derived from the extra-embryonic ectoderm and adult skin. These monoclonal antibodies will provide useful tools for further investigations of epithelial differentiation and transformation.

Amnion↗
PubMed1988

Rat amnion membrane matrix as a substratum for regenerating axons from peripheral and central neurons: effects in a silicone chamber model.

An extracellular matrix preparation, the human amnion membrane matrix (hAMM) can serve as a neurite-promoting substratum for cultured peripheral and central neurons, and also as a support for axonal growth in experimentally injured adult brain in vivo. In the present study, we tested similar materials as bridges in a silicone chamber model for the regeneration of sciatic nerve in the adult rat. Since hAMM elicited an inflammatory response, we developed a rat amnion membrane matrix (rAMM), which proved to be an excellent neurite-promoting substratum for cultured ganglionic and spinal cord neurons. The rAMM was coiled and inserted in the 10 mm gap between the two nerve stumps from the silicone chambers. At 16 days after implantation, temporal progress of regeneration was grossly similar as in saline-prefilled control chambers. However, rAMM-prefilled chambers displayed significantly higher number of vessels and a markedly different geometry of the regenerate: an endoneurium, surrounded by a perineurial-like cell layer, was formed outside the largely preserved central portion of the rAMM coil. After longer regeneration times (28 days), a rAMM core was no longer detected, but some rAMM-like materials remained interspersed in the endoneurium. The overall organization of the regenerate and the number of myelinated axons at this time were similar to those of control chambers, although the endoneurial cross-sectional area was larger in the rAMM chambers. One specimen, however, displayed the very patterns for which the experiments were designed, namely an array of numerous, myelinated axons tracing the spiraling spaces between consecutive lamellae of the rAMM coil.

Amnion↗
PubMed1987

Epidermal growth factor actions on arachidonic acid metabolism in human amnion cells.

Epidermal growth factor (EGF) from human and murine sources increased prostaglandin E2 production by human amnion cells. An anti-EGF receptor monoclonal antibody abolished this stimulatory action of EGF and reduced the basal rate of amnion prostaglandin E2 biosynthesis. The rates of formation of arachidonate lipoxygenase products were also enhanced by EGF.

Amnion↗
PubMed1984

Stimulation of prostaglandin E2 synthesis in human amnion cells maintained in monolayer culture by a substance(s) in amniotic fluid.

A substance(s) in amniotic fluid of human pregnancies promotes a striking increase in prostaglandin E2 production in human amnion cells maintained in primary monolayer culture. The prostaglandin E2 synthesis-stimulatory factor(s) acts in a time- and dose-dependent manner to accelerate prostaglandin E2 formation. We suggest that a substance of fetal origin enters amniotic fluid by way of fetal urine and acts to regulate prostaglandin E2 synthesis in amnion. Such a process may be of fundamental importance in the regulation of amniotic fluid volume homeostasis and in the initiation of parturition.

Amnion↗
PubMed1988

Effects of fetal urinary corticosteroids, catecholamines and kallikrein on PGE2 synthesis in monolayer cultures of human amnion and chorion cells.

We have studied the effects of several compounds isolated from fetal urine on the production of PGE2 by amnion and chorion cells which were maintained in primary monolayer culture. We conclude that desoxycorticosterone and vanillylmandelic acid stimulate PGE2 synthesis by amnion, but adrenaline and kallikrein increase the biosynthesis of PGE2 by chorion. These data suggest that human fetal urine could play a major role in events of parturition.

Adrenal Cortex Hormones↗
PubMed1991

Prostaglandin production by amnion and decidual cells in response to bacterial products.

Media from bacterial cultures have been tested for actions on prostaglandin biosynthesis by human amnion and decidual cells. The bacterial species, which are commonly associated with intrauterine infections, were Group B streptococcus, Escherichia coli, Fusobacterium nucleatum, Bacteroides fragilis, Gardnerella vaginalis, Neisseria gonorrhea, Mycoplasma hominis and Ureaplasma urealyticum. Overall, low doses of bacterial products were stimulatory of amnion prostaglandin production, whereas high doses were inhibitory. A similar pattern of results was obtained for effects on decidual prostaglandin production, although stimulatory actions at low doses were less pronounced. In all experiments interleukin 1 beta consistently induced a stimulation of prostaglandin production that greatly exceeded that caused by any bacterial product. It is possible that the inhibitory action of high doses of bacterial products on prostaglandin biosynthesis may contribute to the poor course of labor experienced by women with chorioamnionitis. Furthermore, these data lend credence to the view that the host response to infection (i.e. cytokine secretion) is the major mediator of subsequent preterm labor.

Amnion↗
PubMed1994

Influence of culture media on prostaglandin output by dispersed amnion cells.

The purpose of the study was to examine the influence of culture media on prostaglandin (PG) production by amnion cells and their response to phospholipase A2. Cells were dispersed from term tissue obtained by elective C-section; the PGE2 output was studied during the first 24 h of culture. The basal PGE2 production from cells cultured in Media 199 (M199) supplemented by 10% horse serum (HS) was significantly greater than that of cells cultured in F12:DME supplemented by 10% fetal calf serum (FCS). Furthermore, phospholipase A2 stimulated PGE2 production in cells cultured with M199 + HS but had no influence on PGE2 output by cells cultured with F12:DME + FCS. This effect was dependent on the presence of HS. The factor(s) in HS responsible was not removed by heating at 56 degrees C for 3 min, treatment with dextran coated charcoal or by ultrafiltration through 10,000 MW filters. Thus, culture media alters the in vitro production of PG and response to phospholipase A2 by amnion cells.

Amnion↗
PubMed2005

Physiological and morphological characteristics of the rhythmic contractions of the amnion in veiled chameleon (Chamaeleo calyptratus) embryogenesis.

A morpho-functional study of the veiled chameleon (Chamaeleo calyptratus) amnion was performed as part of a general comparative study of amnion rhythmic contractions (ARC) in reptile and bird embryogenesis. Eggs incubated at 27.5 degrees C were used at different developmental stages from day 80 (D80) to D184 for the recording of ARC using a force transducer. Slow ARC, about 1 min in duration, were revealed from D88 (stage 31) to the near-hatching stages (incubation time was 183-198 days). The frequency and amplitude of slow ARC increased significantly towards the end of incubation. This ARC enhancement correlated with the differentiation of smooth muscle elements in the amniotic membrane from single spindle-shaped cells to complex "star-like" structures and with the development of the actin fibers, revealed by phalloidin, in the amniotic muscle layer. Short-term changes in temperature influenced ARC and heart rate (HR). Cooling to 25 degrees C from the control (27.5 degrees C) resulted in a significant decrease in both ARC frequency and HR. Heating to 30 degrees C significantly increased the embryonic HR, but not ARC frequency. Within the temperature range from 25 to 30 degrees C the temperature effect on ARC frequency and HR was reversible.

Actins↗
PubMed2005

Changes in matrix metalloproteinase (MMP)-2 and MMP-9 in the fetal amnion and chorion during gestation and at term and preterm labor.

Increased matrix metalloproteinase (MMP)-9 proteolytic activity is associated with term birth, preterm birth and premature rupture of membranes. However, most studies show no changes with MMP-2, which binds tightly to cell and matrix proteins. We hypothesized better protein extraction would reveal new MMP patterns. Human amnion and chorion were collected from 25 patients at preterm or term, extracted with 2% SDS (a high concentration), and the MMP protein levels and pro-enzyme activities were determined by Western immunoblotting and zymography. MMP-2 protein and MMP-2 and -9 pro-enzyme activities in the amnion increased significantly (p<0.05) with labor at term, and were higher than at preterm labor (p<0.05), when extracted with high SDS concentration. There were no changes in chorion MMPs under any condition. These associations suggest MMP-2 may be another regulator of membrane rupture and other labor-associated mechanisms at term parturition, and its role(s) should be examined further.

Adult↗
PubMed2006

Apoptotic related biochemical changes in human amnion cells induced by tributyltin.

Tributyltin (TBT) is one of the environmental pollutants, which is mostly accumulated in marine animals. The toxic effects of TBT have been extensively documented in several types of cells, but the molecular mechanisms responsible for TBT-induced cell damage are still not fully elucidated. The present study was undertaken to evaluate the apoptotic related biochemical changes in human amnion cells induced by TBT. After cells were exposed to TBT at the concentrations of 1-4 microM for 2h, the results suggested that TBT could induce an early and typical apoptosis, moreover caspase-3, the modifications of cytoskeletal structure and the Bcl-2 family were involved in this process. The results will deepen our understanding about the toxic mechanism of TBT on human amnion cells.

Amnion↗
PubMed1981

Control of adenosine-3',5'-monophosphate level in human amnion by prostaglandin E1 and isoproterenol.

The adenosine-3',5'-monophosphate (cAMP) level in human amnion has been measured in vitro during short-term incubations, with or without prostaglandin E1 (PGE1) or isoproterenol. Concentration-response and kinetic curves were obtained. Isoproterenol and PGE1 stimulated cAMP production by amnion in a time-dependent manner. The stimulating effect of isoproterenol and noradrenalin on cAMP level was abolished by the addition of propranolol. Our study, demonstrating cAMP production by amniotic membranes and its stimulation by PGE1 and beta-agonists, suggests that hormones could modulate the amniotic cell metabolism through the cAMP system.

Adenosine Monophosphate↗
PubMed1987

Progesterone synthesis by human amnion, chorion, and decidua at term.

We investigated the ability of human fetal membranes to produce progesterone from a variety of substrates. Chorion is more active than decidua, and amnion produces little progesterone. Cholesterol or low-density lipoprotein cholesterol was not used as a substrate. Chorion used pregnenolone, pregnenolone sulfate, and 20 alpha-dihydroprogesterone for progesterone synthesis. Decidua also used these three substrates but produced significantly less progesterone than chorion. Amnion used only 20 alpha-dihydroprogesterone as a substrate. Exogenous human chorionic gonadotropin or gonadotropin-releasing hormone or its analogues did not influence progesterone production by any of the tissues. There were several significant changes in substrate usage for progesterone synthesis by the tissues around the time of the onset of labor. Tissue concentrations of progesterone are approximately 4 ng/mg protein, and it appears that local production rates could completely account for this. These data are compatible with the hypothesis that local regulatory mechanisms may determine progesterone concentrations in fetal membrane tissues and that important changes may occur around the time of the onset of parturition.

20-alpha-Dihydroprogesterone↗
PubMed1965

Electrical impedance of isolated amnion.

The electrical impedance of the guinea pig amniotic membrane was measured, under standardized conditions, over the frequency range of 20 to 7000 cycles/second. This impedance can be represented analytically by a simple frequency-dependent function which is precisely of the form of the Debye relaxation equation. The observed data exhibit a broad dispersion centered at a frequency of 1050 cycles/second and a narrow distribution of time constants centered about 152 microseconds, both effects being due to the polydisperse nature of amniotic tissue. If the narrow time-constant distribution is approximated by a single time constant, amnion impedance can be simulated by a simple electrical circuit of frequency-independent elements. The Maxwell-Wagner interfacial treatment, although successfully adapted for cell suspensions, is shown to lose its quantitative significance in the case of the tightly structured amnion. In addition, determinations were made on the chemical composition of amniotic fluid, fetal blood and urine, and maternal blood and urine; the DC potential across the amniotic membrane was also measured.

Amnion↗
PubMed1979

Studies on the ultrastructure of the term amnion in pathological pregnancy.

The ultrastructure of the amniotic epithelium at term was examined in cases of intrauterine growth retardation of the fetus and compared with amnions obtained from women with a clinically unremarkable pregnancy. In uterine growth retardation the amniotic cells exhibit a general deficiency of a series of functionally significant cell organelles. The RER is insufficiently developed, there is a diminution of the normally numerous free ribosomes as well as of those cell organelles which are involved in secretory function. A further atypical finding is the common lack of intercellular canals playing an important role in the transamniotic exchange of material. Besides this, a very poor development or a complete disintegration of the microfilamentous cytoskelet is generally noticed. The present findings give once again evidence for a very close relation between the structural appearance of the intercellular diffusion canals and the microfilamentous system. The results presented are suggestive of an amnion which is in a state of reduced secretory activity, additionally, due to the common lack of intercellular canals an inhibition of the interepithelial passage between the maternal and amniotic compartment cannot be excluded.

Amnion↗
PubMed2001

Transcriptional regulation of prostaglandin-H-synthase-1 in the amnion-derived AV3 cell line.

Prostaglandin-H-synthase-1 (PGHS-1), while constitutively expressed in most tissues, increases in abundance in human gestational membranes at term. This suggests that PGHS-1 may be up-regulated in preparation for labor, and thus might be a key determinant in timing labor onset. We conducted transient transfection experiments in amnion-derived AV3 cells utilizing pPGHS1CAT to identify substances that might regulate PGHS-1 expression in amnion. Transforming growth factor-beta (1 ng/ml) and 15-deoxy-delta(12,14) prostaglandin J2 (1 microM) significantly (P < 0.05) (33% and 44% respectively) increased PGHS-1 promoter activity. The activity decreased significantly (P < 0.05) in response to interleukin-1 (IL-1)beta (1 ng/ml) (45%), tumor necrosis factor (TNF)-alpha (50 ng/ml) (34%), epidermal growth factor (10 ng/ml) (54%), phorbol myristate acetate (10 nM) (70%), IL-4 (10 ng/ml) (50%), IL-8 (100 ng/ml) (72%) and Activin A (25 ng/ml) (32%). Whether this degree of change in promoter activity leads to physiologically relevant alterations in the amounts of PGHS-1 present in cells remains to be determined.

Amnion↗
PubMedDate not supplied

Importance of vitamin C in maintenance of the normal amnion: an experimental study.

Collagenous matrix in amnion accounts for most of the dry weight of the tissue and provides its mechanical strength and resistance to rupture. Cell and organ culture techniques have been utilized to study the influence of vitamin C upon the synthesis and deposition of extracellular matrix by cells of normal amnion at term. The cultures have been examined using light and electron microscopy and metabolic labelling. These studies show that both epithelial cells and fibroblasts of the deeper stromal layer are active in the production of fibrillar matrix at this time. Matrix deposition by epithelial cells in culture increases several-fold when the vitamin C concentration in the supernatant medium is increased from zero to 50 micrograms/ml, and, at the latter concentration, a continuous anastomosing fibrillar collagenous meshwork appears beneath the cells. This study thus provides new evidence that an adequate dietary supply of vitamin C is probably needed to maintain the strength of the chorioamnion.

Amnion↗
PubMed1996

Prostaglandin H synthase-2 in human gestational tissues: regulation in amnion.

Using reverse transcriptase-polymerase chain reaction we have established that mRNAs for prostaglandin H synthases 1 and 2 (PGHS-1 and PGHS-2) are present in amnion, chorion and decidua from women both at term before and after the onset of labour and from women at 28-35 weeks of gestation before the onset of labour. By Western blot analyses we have demonstrated that epidermal growth factor, interleukin 1 beta and phorbol 12-myristate 13-acetate all increase PGHS-2 amounts in amnion cells. The degree of stimulation caused by these substances (218-311 per cent) is less than the increase in prostaglandin production usually generated (five- to 10-fold). Hence we believe that these substances may have multiple sites of action in the pathways of arachidonic acid metabolism.

Amnion↗