15-deoxy-delta12,14-prostaglandin J2-induced apoptosis in amnion-like WISH cells

Apoptosis at the site of rupture has been proposed to play a role in premature rupture of the fetal membranes, a condition associated with increased risk of neonatal sepsis and preterm birth. We investigated the ability of peroxisome proliferator-activated receptor (PPAR)-gamma ligands 15-deoxy-delta12,14PGJ2 (15d-PGJ2), delta12PGJ2, ciglitizone and rosiglitazone to induce apoptosis in the amnion-like WISH cell line. 15d-PGJ2 (10 microM) induced morphological characteristics of apoptosis within 2 h, with biochemical indices (caspase activation and substrate cleavage) following shortly after; maximum cell death (approximately 60%) was observed by 16 h, with an EC50) of approximately 7 microM 15d-PGJ2. Delta12-PGJ2 also induced apoptosis but was less potent and acted at a much slower rate. While ciglitizone also induced apoptosis, rosiglitazone had no effect on cell viability. The mechanism of induction of apoptosis by 15d-PGJ2 and delta12PGJ2, which may be independent of PPAR-gamma activation, requires further elucidation.

In vitro sealing of punctured fetal membranes: potential treatment for midtrimester premature rupture of membranes

OBJECTIVE

Midtrimester premature rupture of membranes causes significant perinatal morbidity and death. No effective treatment exists. We investigated (1) whether a needle puncture in the fetal membranes could be sealed in vitro and (2) the optimal composition of the sealant to be used.

STUDY DESIGN

Membranes from second trimester pregnancies (16-24 weeks of gestation) were stretched over a modified syringe with a 2.5-cm open diameter. The syringe was filled with 20 mL of second trimester amniotic fluid, and the membrane was punctured with a 20-gauge needle. Sealants were injected into the amniotic fluid. The primary outcome variable was time for leakage of amniotic fluid. Median times for leakage for the formulations were compared by Wilcoxon exact rank sum test.

RESULTS

Platelets alone failed to seal the puncture site. All other formulations stopped leakage temporarily. Tisseel (Baxter Corp, Glendale, Calif) and cryoprecipitate/thrombin preparations led to more prolonged sealing of punctured amniotic membranes than platelets (P <.01) and were not significantly different from each other.

CONCLUSION

Of the sealants tested in vitro, amniotic membranes are best sealed by a fibrin/thrombin-based sealant.

17beta-estradiol modulates prostaglandin E2 release from human amnion-derived wish cells

In human amnion-derived WISH cells [(3)H]estradiol-17beta binding sites are not detectable, but they become measurable in cells exposed to cAMP elevating agents such as forskolin or Ro 20-1724. In cells unexposed to these drugs, 17beta-estradiol stimulates prostaglandin (PG)E(2) release but exerts an evident inhibitory effect in cells exposed to Ro 20-1724. Both stimulatory and inhibitory actions are inhibited by the estrogen receptor antagonist, tamoxifen, by cell pretreatment with cycloheximide, or when the hormone is bound to BSA. Our data demonstrate for the first time that 1) 17beta-estradiol modulates PGE(2) release from WISH cells, interacting with specific intracellular receptors and probably evoking new protein synthesis, and 2) WISH cell responsiveness to 17beta-estradiol seems to be modulated by cAMP, whose levels are significantly increased by the steroid hormone in the presence of Ro 20-1724. The nucleotide is presumably responsible for the enhacement of hormone receptor availability and for the inhibition of PGE(2) release observed in the presence of Ro 20-1724.

Support for an infection-induced apoptotic pathway in human fetal membranes

OBJECTIVE

Lipopolysaccharide and tumor necrosis factor alpha levels are both elevated in the amniotic fluid of women during infection-associated preterm labor and premature rupture of fetal membranes. Our laboratory has shown that apoptosis is associated with premature rupture of fetal membranes but is not associated with preterm labor. The exact pathway that leads to apoptosis-mediated premature rupture of fetal membranes is still unclear. Because infection and increased inflammatory cytokine response are associated with the majority of cases of premature rupture of fetal membranes, we examined the roles of bacterial lipopolysaccharide and tumor necrosis factor alpha in inducing the proapoptotic caspase pathway in fetal membranes.

STUDY DESIGN

Amniochorionic membranes collected from women undergoing elective repeat cesarean delivery at term were placed in an organ explant system. At the end of a 48-hour incubation period, membranes were stimulated with lipopolysaccharide (50 ng/mL) and recombinant tumor necrosis factor (50 ng/mL). Total ribonucleic acid extracted from these samples was subjected to reverse transcription and two separate sets of multiple polymerase chain reaction. One set studied the expression of Fas, Fas ligand, caspase 8, Fas-associated death domain, and tumor necrosis factor receptor-associated death domain genes and the second set studied the expression of caspase 2, 4, 6, 7, and 10. Caspase 2, 3, and 9 expression was also studied by reverse transcriptase-polymerase chain reaction.

RESULTS

Multiple polymerase chain reactions and reverse transcriptase-polymerase chain reactions documented the induction of Fas and caspase 2, 3, 7, 8, and 9 genes in amniochorion after lipopolysaccharide and tumor necrosis factor stimulation compared with the nonstimulated controls. Neither lipopolysaccharide nor tumor necrosis factor induced Fas ligand expression in human fetal membranes. Caspase 3, 4, and 6, Fas-associated death domain, and tumor necrosis factor receptor-associated death domain expressions were constitutive in all the tissues tested; however, tumor necrosis factor receptor-associated death domain expression appeared stronger in tumor necrosis factor-stimulated tissues.

CONCLUSION

The presence of the signal docking proteins tumor necrosis factor receptor-associated death domain and Fas-associated death domain and the induction of caspase cascade initiators (caspase 2, 8, and 10) and effector caspases (caspase 3, 6, 7, and 9) by lipopolysaccharide and tumor necrosis factor suggest that tumor necrosis factor-tumor necrosis factor receptor-mediated apoptosis may occur in the human fetal membrane.

Sequential use of Prepidil and extra-amniotic saline infusion for the induction of labor in nulliparous women with very low Bishop scores

OBJECTIVE

To evaluate the efficacy of sequential use of Prepidil (prostaglandin E2 gel) and extra-amniotic saline infusion for the induction of labor in nulliparous women with very low Bishop scores.

STUDY DESIGN

Nulliparous women with singleton gestations, intact membranes and a cervical Bishop score of < or = 2 who received Prepidil gel and extra-amniotic saline infusion sequentially for the induction of labor between July 1996 and July 1998 were studied.

RESULTS

Thirty-one women met the inclusion criteria. Indications for induction included post-dates (six of 31), pre-eclampsia (ten of 31), diabetes (three of 31), oligohydramnios (three of 31), intrauterine growth restriction (two of 31) and non-reactive non-stress test (NST) (seven of 31). The average time from onset of induction to delivery was 38.1 +/- 13.5 h. Vaginal delivery was achieved in 80.6%. Women requiring > 2 doses of Prepidil had a higher risk of delivering abdominally (OR = 3.5). Three of seven (42.9%) women with labor induced for non-reactive NST but only three of 24 (12.5%) with labor induced for other indications had a Cesarean section delivery (p < 0.001).

CONCLUSIONS

Nulliparous women with very unfavorable cervices can be counselled that they have an 80% chance of vaginal delivery using sequential Prepidil and extra-amniotic saline infusion as an induction method, with 90% delivering within the first 48 h.

Lack of embryotoxicity of homocysteine thiolactone in mouse embryos in vitro

Recent work from humans and chick embryos has suggested that homocysteine may play a role in producing neural tube defects (NTDs). In an effort to determine if homocysteine is able to produce NTDs in mammalian embryos, mouse embryos were explanted on GD 8 and cultured for 44 h. When either homocysteine or homocysteine thiolactone was added to the culture medium, treated embryos developed as well as controls and had closed neural tubes. Homocysteine thiolactone was also microinjected into the amniotic sac of mouse embryos. Again, development proceeded normally with no significant increase in the number of embryos with open neural tubes at the end of the culture period. HPLC analysis of embryonic thiols 24 h after microinjection revealed a significant increase in embryonic cystathionine levels. These data suggest that homocysteine does not produce NTDs in mouse embryos cultured in vitro and that early organogenesis-stage embryos are able to metabolize homocysteine.

Reactive oxygen species and preterm premature rupture of membranes-a review

Preterm premature rupture of membranes (PPROM) results initially from damage to collagen in the chorioamnion leading to a tear in the membrane. Tissue-damaging molecules called reactive oxygen species (ROS) are capable of damaging collagen in the chorioamnion that could lead to PPROM. This hypothesis is supported by epidemiological studies linking clinical conditions known to produce ROS or reduce antioxidant protection to PPROM, by in-vitro studies in which membrane segments exposed to ROS exhibited tissue alterations consistent with PPROM, and by clinical studies showing that chorioamnion and amniotic fluid samples obtained from PPROM patients exhibit excessive collagen degradation. The role of antioxidants to protect the chorioamnion from ROS damage has been demonstrated in one in-vitro study. A prospective, randomized blinded trial of antioxidant therapy during pregnancy is needed to evaluate this approach for the prevention of PPROM.

Effects of amniodistention with carbon dioxide on fetal acid-base status during fetoscopic surgery in a sheep model

BACKGROUND

Because the data from previous experiments on the fetal effects of carbon dioxide (CO2) amniodistention in endoscopic fetal surgery are conflicting, we set out to evaluate the fetal acid-base status during CO2 amniodistention, with or without maternal hyperventilation, using a sheep model for endoscopic surgery.

METHODS

We assigned 26 pregnant ewes undergoing amniodistention with CO2 (4-5 mmHg intraamniotic pressure) to one of the following three groups: group I had fetal surgery + no maternal hyperventilation (n = 10); group II had fetal surgery + maternal hyperventilation (n = 10); group III had no fetal surgery + maternal hyperventilation (n = 6). Hyperventilation kept CO2 at 29-31 mmHg; in its absence, pCO2 ranged from 38 to 41. Fetal surgery consisted of fetoscopic tracheal clipping. Maternal blood pressure (mean, 98/69 mmHg) and heart rate (mean, 72 bpm) were kept at values comparable to human pregnancy. Fetal and maternal blood gas measurements were taken every 15 min during 1 h of amniodistention.

RESULTS

The ranges for baseline mean fetal pCO2 (mmHg) and pH were 51-55 and 7.24-7.25, respectively, in all study groups. After 1 h of amniodistention, mean +/- SEM values of fetal pCO2 and pH were 88 +/- 3 and 7.06 +/- 0.03 in group I, 69 +/- 4 and 7.13 +/- 0.02 in group II, and 71 +/- 5 and 7.14 +/- 0.04 in group III, respectively. Therefore, maternal hyperventilation attenuated but could not prevent significant fetal hypercarbia and acidosis. Fetal surgical manipulation had no effect on these observations.

CONCLUSION

CO2 amniodistention should not be considered for clinical practice until ways of preventing its effects on the fetal acid-base status can be demonstrated.

CA125 phosphorylation is associated with its secretion from the WISH human amnion cell line

Evidence is presented suggesting that CA125 is a serine and/or threonine phosphoprotein and that its secretion from the human amnion WISH cell line is closely linked to its phosphorylation. It is also indicated that regulation of CA125 secretion requires protein(s) tyrosine phosphorylation. WISH cells treated with a tyrosine phosphatase inhibitor, vanadate/ H2O2, resulted in increased levels of CA125 secretion. Exposure of vanadate-treated cells to epidermal growth factor further enhanced this secretory activity. Immunohistochemistry of vanadate-treated cells resulted in a substantial increase in not only cytoplasmic tyrosine phosphoproteins but also in membrane-associated CA125 when stained with the PY20 anti-phosphotyrosine and M11 anti-CA125 monoclonal antibodies, respectively. M11 immunoprecipitation of CA125 from cells labelled with [32P]-orthophosphate was analyzed by SDS-PAGE and autoradiography. Immunoprecipitates from cell lysates demonstrated that a phosphoprotein of > 200 kD was isolated and immunoreacted with both the OC125 and M11 anti-CA125 monoclonal antibodies by Western blotting. CA125 immunoprecipitated from vanadate-treated cells showed a marked increase in cell-associated CA125 phosphorylation. Although CA125 could be immunoprecipitated from WISH cell media incubated with [32P]-orthophosphate in the presence or absence of vanadate as detected by Western blotting, autoradiographic analysis of the Western blots revealed no [32P]-labelled CA125 co-migrating with the 200-kD plus molecule detected by M11. When the PY20 anti-phosphotyrosine monoclonal antibody was used as the probe, no tyrosine-phosphorylated CA125 was detected in cell lysates.

Formyl-methionyl-leucyl-phenylalanine induces prostaglandin E2 release from human amnion-derived WISH cells by phospholipase C-mediated [Ca+]i rise

The presence of binding sites for formyl-methionyl-leucyl-phenylalanine (fMLP), its effect on prostaglandin E (PGE) release, and the signal transduction pathway activated by the peptide were investigated in human amnion-derived WISH cells. Our results demonstrate that specific binding sites for fMLP are present on WISH cells and that the peptide induces a significant increase of prostaglandin (PG)E2 release. The kinetic properties of binding are similar to those previously found in amnion tissue prior to the onset of labor, i.e., only one population of binding sites with low affinity for the peptide is present. Binding of 3H-fMLP in WISH cells is inhibited by N-t-butoxycarbonyl-methionyl-leucyl-phenylalanine, an fMLP receptor antagonist, with an IC50 value very close to that shown by nonlaboring amnion. The fMLP-induced PGE2 output is inhibited by indomethacin, quinacrine, and U-73122, inhibitors of cyclooxygenase, phospholipase A2, and phospholipase C, respectively. As regards the transduction pathway activated by fMLP, we demonstrate that phospholipase C activation, followed by an increase of intracellular calcium concentration ([Ca2+]i), is involved in response to the peptide. Our results add further evidence to the role of proinflammatory agents in the determination of labor. Furthermore, because WISH cells appear to behave like nonlaboring amnion tissue, they represent the ideal candidate for in vitro investigation of the events triggering the mechanism of delivery.

Phthalic acid mimics 17beta-estradiol actions in WISH cells

The object of this study was to evaluate whether phthalic acid, which is one of the metabolites of phthalic acid esters, exerts estrogenic actions in WISH cells, an immortalized cell line derived from human amniotic tissue. Our data demonstrate that phthalic acid (i) displaces [3H]estradiol from its binding sites, (ii) enhances the intracellular cyclic AMP concentration, without influencing adenylyl cyclase activity, (iii) stimulates or inhibits prostaglandin output, probably depending on the intracellular nucleotide level. The effects on prostanoid release are counteracted by addition of the protein-synthesis inhibitor cycloheximide, or when the diffusion of phthalic acid through the cell membrane is prevented. On the basis of our previous demonstration, that 17beta-estradiol exerts similar effects in WISH cells, we suggest that the molecular mechanisms underlying phthalic acid and steroid-hormone responses in this cell line are the same. This is the first demonstration that phthalic acid binds to the estrogen receptor with high affinity and mimics the hormone physiological actions.

Characterization of adriamycin-induced G2 arrest and its abrogation by caffeine in FL-amnion cells with or without p53

We investigated the effect of Adriamycin on FL-amnion (FL) cells. After treatment with the drug, the cells arrested at G2, but we did not detect an increase in the p21 levels. We established a p53-deficient derivative of these cells, in which G2 arrest also occurred after treatment with Adriamycin, suggesting that the arrest we observed in these cells is independent of the p53 pathway. Low doses of Adriamycin (100-200 ng/ml) induced G2 arrest, while late S-phase arrest was observed at high doses (500-1000 ng/ml) in both FL and p53-deficient FL cells. Accumulation of cyclin B1 was detected only in cells arrested at G2, and not in those arrested at S phase, suggesting that the S-phase checkpoint functioned efficiently even in p53-deficient FL cells. In both cell lines, caffeine-induced activation of CDC2 kinase was detected only in cells arrested at G2 and CDC2 kinase-activated cells died exhibiting features of apoptosis. CDC2 kinase activation was inhibited by cycloheximide. Furthermore, cycloheximide inhibited activation of CDK2:cyclin A, which normally precedes CDC2 kinase activation in caffeine-treated cells. These results suggest that p53 and p21 do not have special roles in the S- and G2-phase checkpoints and that CDK2:cyclin A could be the target of the G2-phase DNA damage checkpoint.

Enhancement of amniotic cyclooxygenase type 2 activity in women with preterm delivery associated with twins or polyhydramnios

OBJECTIVE

We tested the hypothesis that preterm delivery in women with twins or polyhydramnios is associated with enhanced expression and activity of cyclooxygenase type 2 in the amnion.

STUDY DESIGN

We obtained amniotic tissue samples from women undergoing preterm delivery complicated by either twins or polyhydramnios and also from women undergoing preterm cesarean delivery before or after labor. We measured amniotic prostaglandin E2 content and determined cyclooxygenase type 1 and type 2 expressions. We inhibited cyclooxygenase type 1 and type 2 activities with selective inhibitors.

RESULTS

Preterm delivery attributed to twins or polyhydramnios was associated with higher prostaglandin E2 production and enhanced amniotic expression of cyclooxygenase type 2. In contrast, cyclooxygenase type 1 expression was unchanged. Incubation of amniotic samples in vitro with either indomethacin or the selective cyclooxygenase type 2 inhibitor SC-236, but not with the cyclooxygenase type 1 inhibitor SC-560, effectively reduced prostaglandin E2 production.

CONCLUSION

Preterm delivery related to multiple gestation or polyhydramnios was associated with enhanced amniotic expression and activity of cyclooxygenase type 2.

Complementary mechanisms of enhanced oxytocin-stimulated prostaglandin E2 synthesis in rabbit amnion at the end of gestation

The up-regulation of oxytocin (OT) receptors in rabbit amnion at the end of gestation is associated with a large increase in the ability of OT to stimulate PGE2 synthesis. The purpose of these investigations was to determine what other factors contribute to this increase. OT enhanced PGE2 synthesis at several levels. The concentrations of cytosolic phospholipase A2, which generates arachidonic acid for PGE2 synthesis, and PGH endoperoxide synthases (types 1 and 2), which catalyze the conversion of arachidonic acid to prostanoids, rose substantially in rabbit amnion at term. OT stimulated translocation of cytosolic phospholipase A2 to the cell particulate fraction, presumably by a Ca2+-mediated process, and phosphorylation of cytosolic phospholipase A2 via the extracellular regulated protein kinase 2/1-mediated pathway. OT-stimulated increases in intracellular Ca2+ concentrations and extracellular regulated protein kinase 2/1 phosphorylation were both mediated by G(q/11) activation. OT also increased the expression of PGH endoperoxide synthase-2 after treatment of amnion cells in culture for 2 h; however, PGE2 release in response to OT was virtually immediate. These findings show that the rapid stimulation of PGE2 synthesis by OT occurs through cytosolic phospholipase A2 activation and PGH endoperoxide synthase-1 activity, both of which, along with OT receptor concentrations, are considerably up-regulated in the amnion at the end of gestation.

Pretreatment of human amnion-chorion with vitamins C and E prevents hypochlorous acid-induced damage

OBJECTIVE

Preterm premature rupture of fetal membranes has been associated with infection, cigarette smoking, and bleeding. Hypochlorous acid (a reactive oxygen species) is central to the body's response to infection, yet it may damage surrounding tissue while destroying pathogens. We examined in vitro the tissue-damaging actions of hypochlorous acid on the amnion-chorion and the protective role provided by pretreatment with vitamins C and E.

STUDY DESIGN

Amnion-chorion samples were obtained from 4 term pregnancies, cut into segments, and divided into 6 exposure groups. Half were treated in advance with vitamins C and E (Trolox C) and half were treated with buffer solution alone. After rinsing, amnion-chorion samples were exposed to hypochlorous acid at 1 or 10 mmol/L for 4 hours. Histologic and immunocytochemical evaluations were conducted with antibodies for collagen I and IV.

RESULTS

Extensive damage to amniotic epithelium and collagen I but not collagen IV resulted from hypochlorous acid exposure and was dose related. Pretreatment with vitamins C and E prevented this damage in all cases.

CONCLUSION

Hypochlorous acid damages the amniotic epithelium and collagen I in the amnion-chorion. The protection against hypochlorous acid-induced damage provided by antioxidant therapy (vitamins C and E) is of therapeutic significance.

Association effects of vitamin B6 and various magnesium salts on a pharmacological model: the human amniotic membrane

The effects of the association of vitamin B6 and Mg salts: aspartate, citrate, lactate, pidolate, sulfate, were studied on the ionic transfer through a membraneous pharmacological model: the isolated human amniotic membrane. The ionic transfer was evaluated by measure of the total conductance in the maternal to fetal way (GtM) and in the fetal to maternal way (GtF), of the ionic fluxes (F1 on the maternal side, F2 on the fetal side) and of the ratio F1/F2. The results were explained in terms of monophasic (decrease: screening or increase: binding interactions with the polar surface moities) or biphasic (decrease then increase) action. The results indicated: Mg aspartate decreased GtF, F1, F2 whatever concentration and had a concentration-dependent effect on GtM, F1/F2. The addition of vitamin B6 induced a new concentration-dependent effect (biphasic action: decrease then increase) on GtF, F1 and also modified F2, F1/F2. Mg citrate decreased GtM, GtF, F2 whatever the concentration and had a concentration-dependent effect on F1, F1/F2. The addition of vitamin B6 induced a new biphasic effect on GtM and GtF. Mg lactate decreased GtM, F1, F2, F1/F2 whatever the concentration but had a concentration-dependent effect on GtF. The addition of vitamin B6 induced a new biphasic effect on GtM, F1, F2, F1/F2. Mg pidolate had no effect on GtM, GtF, F2, F1/F2 and decreased F1. The addition of vitamin B6 did not induce variation. Mg sulfate had no effect on GtM, increased GtF and decreased F1, F2, F1/F2. The addition of vitamin B6 induced a new concentration-dependent effect on F2. The association between vitamin B6 and Mg salts implicated a new action on components of the amniotic ionic transfer characterized by a biphasic action (decrease then increase concentration-dependent effect). This effect was dependent on the anion associated with magnesium. The magnesium salts may be classified with regard to the beneficial effect due to the association with vitamin B6 in the following decreasing order: aspartate and lactate, citrate, pidolate, sulfate.

Influence of oxytocin on prostaglandin E2, intracellular calcium, and cyclic adenosine monophosphate in human amnion-derived (WISH) cells

OBJECTIVE

This study was undertaken to investigate the regulation of prostaglandin release by oxytocin and the influence of oxytocin on intracellular calcium and on the cyclic adenosine monophosphate system in human amnion-derived WISH cells.

STUDY DESIGN

We determined prostaglandin E(2) release from WISH cells treated with oxytocin, evaluated the cytosolic calcium concentration in single WISH cells by confocal microscopy, and measured both intracellular cyclic adenosine monophosphate levels and adenylyl cyclase activity after oxytocin treatment.

RESULTS

Treatment of WISH cells with oxytocin resulted in a concentration-dependent release of prostaglandin E(2), which was increased by lithium chloride and inhibited by indomethacin and U-73122. In single WISH cells, oxytocin increased cytosolic calcium. Moreover, the hormone lowered levels of intracellular cyclic adenosine monophosphate but did not alter adenylyl cyclase activity.

CONCLUSIONS

Our data demonstrate, for the first time, that WISH cells respond to oxytocin by increasing prostaglandin E(2) release. In addition to phospholipase C activation and cytosolic calcium increase, the hormone effect involves also a reduction of the cyclic adenosine monophosphate level.

NF-kappaB and AP-1 are required for cyclo-oxygenase 2 gene expression in amnion epithelial cell line (WISH)

Prostaglandins are known to play an important role in human labour and are used clinically to induce labour onset. Cytokines, e.g. interleukin 1 beta (IL-1beta), are up-regulated in the amniotic fluid late in gestation and can increase prostaglandin production through the expression of cyclo-oxygenase 2 (COX-2), the prostaglandin synthetic isoform involved in human labour. We demonstrate in immortalized amnion epithelial (WISH) cells, that IL-1beta causes increased transcription of the COX-2 gene. Luciferase reporter constructs with site-directed mutagenesis of the two NF-kappaB sites and an AP-1 site in the COX-2 promoter showed reduced expression of luciferase in transient transfection studies. This suggests that the binding of transcription factors to these sites is essential for the regulation of COX-2 transcription in IL-1beta-treated WISH cells.

Differential regulation in human amnion epithelial and fibroblast cells of prostaglandin E(2) production and prostaglandin H synthase-2 mRNA expression by dexamethasone but not tumour necrosis factor-alpha

Previous studies have identified both pro-inflammatory cytokines and glucocorticoids as positive regulators of amnion prostaglandin (PG) biosynthesis. The stimulatory effects of dexamethasone (Dex), a glucocorticoid agonist, on prostaglandin endoperoxide H synthase (PGHS)-2 mRNA expression and PG biosynthesis in amnion have been attributed to an atypical response by the mesenchymal cells of the amnion. The objective of this study was to confirm previous findings concerning cell type-dependant Dex-induced upregulation of PGHS-2 mRNA expression and PG production using separated amnion cell populations, in comparison with the effects of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha). Amnion cells from placentae delivered at term by caesarian section were isolated by tryptic digestion and epithelial cells were then separated from mesenchymal cells by differential absorption onto plastic. After 24-72 h, the two cell populations were passaged and sub-cultured. Cells were treated with Dex (10(-9)-10(-6) m) or TNF-alpha (0.1-50 ng/ml) or media alone. Thereafter, PGE(2)production was determined and PGHS-2 mRNA content analysed by a competitive quantitative RT-PCR method established and validated for this study. PGE(2)production in fibroblast-enriched cultures was increased to 310+/-41 per cent (mean+/-sem, n=4 wells per treatment point) of control in the presence of 10(-8) m Dex. Conversely, PGE(2)production in Dex-treated amnion epithelial cells was decreased to 67+/-24 per cent of control. Altered PGE(2)biosynthesis was accompanied by the upregulation of PGHS-2 mRNA in amnion fibroblasts but not in epithelial cells. TNF-alpha increased PG output and PGHS-2 expression independent of cell type. Glucocorticoids therefore appear to have opposing effects on PG biosynthesis in the two major cellular components of the human amnion.

Cross-linking of amniotic membranes

Human amniotic membrane was cross-linked with chemical and radiation methods to investigate the effect of cross-linking on its physicochemical and biodegradation properties. Radiation cross-linking was performed with gamma-ray and electron beam while chemical cross-linking was with glutaraldehyde (GA). Both gamma-ray and electron beam irradiation decreased the tensile strength and elongation at break of the amniotic membrane with an increase in the irradiation dose, whereas GA cross-linking had no effect on the tensile properties. This is probably due to the scission of collagen chains through irradiation. No significant change was observed on the water content of cross-linked amniotic membranes for any of the crosslinking methods and in marked contrast with cross-linking of a gelatin membrane. A permeation study revealed that protein permeation through the amniotic membrane was not influenced by the GA concentration at cross-linking. These findings are ascribed to the structure characteristic of the amniotic membrane. The membrane is composed of a fibrous mesh structure from an assemblage of collagen fibers. It is possible that cross-linking takes place in the interior of the fiber assembly without impairing the mesh structure, resulting in no change of the water content and protein permeability. In vitro degradation of cross-linked amniotic membranes revealed that radiation cross-linking appeared to be much less effective than GA cross-linking in retarding the degradation, probably because of low cross-linking densities. GA-cross-linked amniotic membranes were degraded more slowly as the GA concentration at cross-linking increased. When the GA-cross-linked amniotic membrane was subcutaneously implanted in the rat, the tissue response was mild, similar to that of the non-cross-linked native membrane.

Effective diminution of amniotic prostaglandin production by selective inhibitors of cyclooxygenase type 2

OBJECTIVE

Cyclooxygenase inhibitors are effective tocolytic agents, but significant adverse effects limit their use. We hypothesized that selective inhibitors of the isozyme cyclooxygenase 2 would effectively diminish labor-associated prostaglandin production.

STUDY DESIGN

We analyzed cyclooxygenase type 1 and 2 expression in amnion, chorion, decidua, and myometrium from laboring or nonlaboring women and tested the efficacy of selective cyclooxygenase 2 inhibition in diminishing prostaglandin production.

RESULTS

The expression of cyclooxygenase 2 in amnion from women in labor, either preterm or at term, was significantly higher than in amnion before labor. In contrast, cyclooxygenase 1 expression was unchanged by labor. The enhanced expression of amniotic cyclooxygenase 2 was associated with increased prostaglandin E(2) levels in laboring women. Amniotic prostaglandin E(2) production was effectively diminished by the selective cyclooxygenase 2 inhibitors SC-236 and NS-398 but not by the cyclooxygenase 1 inhibitor SC-560.

CONCLUSION

Selective inhibitors of cyclooxygenase 2 are effective in diminishing prostaglandin production in vitro and may be useful in prevention of preterm deliveries.

Activin A exerts both pro- and anti-inflammatory effects on human term gestational tissues

There is a growing appreciation of the importance of activin as a modulator of immune function. The aim of the present study was to determine whether activin A exerts any effects on cytokine and prostaglandin (PG) production by the tissues of pregnancy. Explant cultures were established for amnion, choriodecidual and placental tissues derived from pregnancies delivered at term by Caesarean section (n=5 placentae). Explants were treated with activin A (0.5, 5 and 50 ng/ml) in serum-free Ham's F12/DME media for 24 h (n=3-4 replicates). Production rates of interleukin (IL)-1beta, IL-6, IL-8, tumour necrosis factor-alpha (TNF-alpha) and PGE(2)were determined using immunoassay. Differences between treatment groups were analysed by ANOVA followed by Dunnett's test;P< 0.05 was considered to be significant. Amnion IL-6 production exhibited biphasic responses to activin A: at 5 ng/ml activin A, IL-6 production was significantly stimulated (to 246+/-74.6 per cent of control (mean+/-sem), while at 50 ng/ml it was significantly inhibited (to 46+/-7.4 per cent of control). IL-8 and PGE(2)production by amnion showed significant responses to activin A that were similar to those of IL-6. No significant effects of activin A were observed on choriodecidual and placental IL-6, IL-8 and PGE(2)production. However, TNF-alpha production was significantly inhibited by 50 ng/ml activin A in both choriodecidual and placental explants (to 43+/-9.7 per cent and 51+/-6.7 per cent of control, respectively). Placental IL-1beta production was not altered by treatment with activin A at any concentration. These findings support the concept of activin as an immune modulator in tissues of pregnancy.

Prostanoid stimulation of cytokine production in an amnion-derived cell line: evidence of a feed-forward mechanism with implications for term and preterm labor

OBJECTIVE

To test the hypothesis that amnion cytokine production might be regulated by prostanoids.

METHODS

Amnion-derived WISH cells were treated with a range of prostanoids and their effects on production of interleukin (IL)-6 and IL-8 were determined by enzyme-linked immunosorbent assay and Northern analysis. The effects of thromboxane inhibitors on cytokine production by term primary amnion explants also were examined.

RESULTS

Prostaglandin (PG)A2, PGD2, PGF2 alpha, PGE2, PGJ2, and the PGI2 analogue carbaprostacyclin (1-1000 nmol/L) exhibited no significant effects on cytokine production. However, the thromboxane A2 (TXA2) agonist U46619 and carbocyclic (c)TXA2 both stimulated WISH cytokine production with similar potencies under basal or cytokine-stimulated conditions. Significant stimulation of IL-6 production was observed at concentrations > or = 8 nmol/L (P < .05 by analysis of variance), whereas IL-8 production was stimulated significantly but to a lesser extent. The effects of U46619 and cTXA2 were rapid; maximal stimulation of cytokine production occurred within 4 to 8 hours of treatment. U46619 augmented IL-1 beta-stimulated IL-6 and IL-8 mRNA expression within 2 hours of treatment. In amnion explants inhibitors of TX synthesis and action abrogated the stimulatory effects of IL-1 beta on cytokine production.

CONCLUSION

These results are consistent with the presence of a feed-forward loop in amnion involving TXA2 and cytokines, which could play a significant role in the progression of the inflammatory response involved in the mechanism of infection-driven preterm labor.

Cryopreserved human amniotic membrane for ocular surface reconstruction

BACKGROUND

Amniotic membrane transplantation is used for the reconstruction of the ocular surface in the context of, for example, corneal ulcers or conjunctival scarring. The mechanisms by which preserved amniotic membrane grafts promote reepithelialization are unknown. As a first step the viability and proliferative capacity of amnion cells following cryopreservation of membranes in glycerol is investigated.

METHODS

Fresh and cryopreserved (in 50% glycerol) amniotic membranes were investigated histologically and by vital stains. Following enzymatic digestion, amniotic cells were stained for viability and cultured in DMEM+10% FBS. In addition, explant cultures were established from fresh and cryopreserved membranes.

RESULTS

Histological examination showed no significant morphological alteration following cryopreservation. While fresh membranes contained predominantly vital cells, no such cells were detected following cryopreservation. Also, cells removed enzymatically from cryopreserved membranes were not viable and did not grow in culture. While both epithelial and fibroblastic cells grew from fresh membranes, no growth was seen from cryopreserved membranes.

CONCLUSION

The results suggest that the technique for preservation which is most widely used for ophthalmological amniotic membrane transplantation significantly impairs viability and proliferative capacity. This supports the clinical finding that neither immunological reactions nor signs of ingrowth of amniotic cells are observed in patients. Furthermore amniotic membrane grafts seem to function primarily as matrix and not by virtue of transplanted functional cells.