Chorion Laeve Research Articles

Microscopic Chorionic Pseudocysts in Placental Membranes: A Histologic Lesion of in Utero Hypoxia

Grossly apparent and microscopically intermediate trophoblast-lined subchorionic, septal, and cell island cysts are relatively common placental findings. To analyze the clinicopathologic correlations of histologically similar but grossly inapparent microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes (mccpm), selected placental and clinical parameters of all 172 consecutive placentas with mccpm (study group, sg) and all consecutive 3743 placentas without mccpm (comparative group, cg) from years 1994 through 2005 were statistically compared; mccpm were observed in 4.3% of all placentas and in 14.9% of placentas from preeclamptic mothers from 24- to 42-week pregnancies, their gestational weeks' distribution almost mirroring that of the distribution of preeclampsia, with a peak in the middle of the 3rd trimester. Microscopic chorionic pseudocysts (lakes) arising in the chorion laeve of placental membranes were statistically significantly more common in patients with preeclampsia and maternal diabetes mellitus. In placentas with mccpm, decidual arteriolopathy, homogeneous placental maturation, global hypoxic pattern of placental injury, chorangiosis, placental infarction, laminar necrosis of membranes, stem obliterative endarteritis, erythroblasts of fetal blood, and decidual hemosiderosis were statistically significantly more common, while acute chorioamnionitis, villous fibrosis, and villous edema were less common (P < or = 0.05). There were no statistically significant differences between sg and cg in meconium staining, retroplacental hematoma, perivillous fibrin deposition, intervillous thrombi, chronic villitis, chorangiomas, placenta accreta, amnion nodosum, and marginate/vallate placenta. Highly statistically significant associations of mccpm with preeclampsia and a cluster of placental lesions known to be linked to placental hypoxia indicate that the mccpm form in response to hypoxia, particularly in patients with preeclampsia; mccpm should therefore be regarded and reported as a hypoxia-associated placental lesion.

Corticotropin-Releasing Hormone Receptor Type 1 and Type 2 Mediate Differential Effects on 15-Hydroxy Prostaglandin Dehydrogenase Expression in Cultured Human Chorion Trophoblasts

Throughout gestation, the chorion laeve controls the levels of biologically active prostaglandins (PGs) by its high level of nicotinamide adenine dinucleotide-dependent 15-hydroxy PG dehydrogenase (PGDH). In this study, we investigate the effects mediated by CRH receptors on the expression of PGDH in the chorion. We found that both CRHR1 and CRHR2 were localized in cultured chorion trophoblast cells, with CRH-R1alpha, R1beta, R1c, R1e, and R1f and CRHR2beta isoforms identified in these cells. To block the actions of endogenous CRH and its related peptides, cultured chorion trophoblasts were treated with an increasing concentration of alpha-helical CRH 9-41, the nonselective CRH receptor antagonist, which resulted in decreased mRNA and protein expression as well as the activity of PGDH. To investigate the individual role of CRHR1 and CRHR2, cell cultures were treated with the specific CRHR1 antagonist antalarmin and CRHR2 antagonist astressin2B, respectively. The results showed that antalarmin increased whereas astressin2B decreased mRNA and protein expression as well as the activity of PGDH in chorion cells. When the cells were treated with an exclusive CRHR2 agonist, urocortin II, elevated expression and activity of PGDH was exhibited. However, cells treated with either exogenous CRH or urocortin I showed significantly increased PGDH expression, and these effects could be blocked by astressin2B but not by antalarmin. We suggest that, in chorion trophoblast cells, CRHR1 and CRHR2 mediate divergent effects on PGDH expression, and this may provide a precise regulation of PGs levels from chorion to myometrium during pregnancy.

Tissue kallikrein and kininogen levels in fetoplacental tissues from normotensive pregnant women and women with pregnancy-induced hypertension

Objectives An imbalance of vasoconstrictor and vasodilator substances in the placenta has been postulated in the pathogenesis of pregnancy-induced hypertension (PIH). There is however little information available on the kallikrein-kinin system (KKS) in women with PIH. The aim of this study therefore was to determine tissue kallikrein and kininogen levels and their distribution patterns in fetoplacental tissues from both normotensive pregnant (NTP) women and women with PIH. Study design The study group consisted of 24 women, 12 of whom had normal pregnancies, while 12 had PIH. Portions of amnion, chorion laeve, placental plate chorion, fetal placenta and maternal placenta were dissected from each freshly delivered placenta. Tissue kallikrein (total, active and inactive) and kininogen levels were estimated using a synthetic chromogenic substrate, S-2266 and an enzyme immunoassay, respectively. The data were analysed using Mann–Whitney U and Kruskal–Wallis tests. Results No significant differences were found for total, active and inactive tissue kallikrein levels in all fetoplacental tissues between both groups. However, kininogen levels were found to be significantly lower in chorion laeve, placental plate chorion, fetal placenta and maternal placenta from women with PIH when compared to those in similar tissues from NTP women. Conclusion These findings suggest the presence of an abnormality in the kallikrein-kinin system in the placentas of women with PIH, which requires further study.

Association of PAT Proteins with Lipid Storage Droplets in Term Fetal Membranes

As depots for neutral lipids, lipid storage droplets (LDs) accumulate with advancing gestation within the fetal membranes. Little is currently known about the proteins associated with the LDs of these cells. The PAT family [ perilipin, adipose differentiation-related protein (ADRP), and tail-interacting protein of 47 kilodaltons (TIP47)] represents a unique group of proteins thought to contribute to LD formation and function. We examined the association of each of the PAT proteins with LDs of term fetal membranes. We found that large LDs of amnion epithelial cells were reactive for neutral lipid stains and simultaneously encoated with ADRP and TIP47, but not perilipin. Within the remaining cell types, LDs were frequently co-labeled with antibodies recognizing ADRP and TIP47; however, in cells harboring only small LDs, the majority of TIP47 labeling was cytoplasmic. Structures labeled with perilipin antibodies were present only in chorion laeve trophoblasts. Gene and protein expression analyses suggested this to be a small molecular weight perilipin isoform, such as that seen in steroidogenic cells. We conclude that LDs are heterogeneous among differing cell types of the fetal membranes. Subclassification of LDs based on associated proteins suggests that these organelles may serve specialized functions within individual cells.

Raised Leptin Concentrations in Feto-Placental Tissues from Women with Preeclampsia

Objective. The aim of this study was to estimate the levels of leptin in the amnion, chorion laeve, and placenta and to examine for any differences in leptin levels in these tissues from preeclamptic and normotensive pregnant women. Method. Fresh samples of amnion, chorion laeve, and placenta were obtained from 10 normotensive and 10 preeclamptic women following vaginal delivery. After repeated washing with Krebs Heinsleit solution, 2 g of each tissue were homogenized separately. Following centrifugation, the supernatant was removed and stored at − 80°C for analysis of leptin at a later date. Leptin in supernatants from homogenates was measured using commercially available radioimmunoassay (RIA) Kits. Statistical analysis was performed using student's t-test for independent samples and all results are expressed as mean ± SEM. Results. Leptin concentrations were significantly higher in all the three tissues from preeclamptic women when compared to the corresponding tissues from normotensive controls (0.52 ± 0.1 vs. 1.15 ± 0.41; 0.99 ± 0.16 vs. 2.19 ± 0.71; and 10.28 ± 1.06 vs. 13.95 ± 1.13 in the amnion, chorion laeve, and placenta, respectively, from normotensive pregnant women and women with preeclampsia; p < 0.05). Conclusion. Leptin concentration is significantly raised in fetoplacental tissues from women with preeclampsia. Its role in preeclampsia remains unclear and it is not possible to say from this study if the raised levels of leptin evident in placentas from preeclamptic women are a cause or consequence of preeclampsia, although the latter seems more likely.

Leukocyte Migration through the Basement Membrane: Ultrastructural-Cytochemical Observation of the Human Fetal Membrane in Women with Chorioamnionitis-Related Preterm Delivery

Polymorphonuclear leukocytes (PMNs) infiltrating the chorioamnion is one causal agent of preterm delivery. Although the basement membrane (BM) has been proven to be a barrier against PMN migration in various tissues, there is a lack of data focusing on the relationship between PMN morphology and chorion laeve BM. Using peroxidase enzyme-cytochemistry, we morphologically studied PMN infiltration into the chorioamnion, especially the chorion laeve BM. The accumulated PMNs lay side by side just beneath the BM, while the cytoplasmic processes of some PMNs penetrated the BM. Peroxidase deposits appeared not only in the leukocyte granule but also on the phagosomes, indicating that PMNs at the site were activated. These features resembled those of activated PMNs migrating through a filter according to the gradient of chemo-attractant. The chorion laeve BM thus may be a barrier to PMN migration through the chorioamnion. Activated PMNs and BM may be involved in the pathophysiology of preterm delivery.

Placental oxidative stress: from miscarriage to preeclampsia.

To review the role of oxidative stress in two common placental-related disorders of pregnancy, miscarriage and preeclampsia. Review of published literature. Miscarriage and preeclampsia manifest at contrasting stages of pregnancy, yet both have their roots in deficient trophoblast invasion during early gestation. Early after implantation, endovascular trophoblast cells migrate down the lumens of spiral arteries, and are associated with their physiological conversion into flaccid conduits. Initially these cells occlude the arteries, limiting maternal blood flow into the placenta. The embryo therefore develops in a low oxygen environment, protecting differentiating cells from damaging free radicals. Once embryogenesis is complete, the maternal intervillous circulation becomes fully established, and intraplacental oxygen concentration rises threefold. Onset of the circulation is normally a progressive periphery-center phenomenon, and high levels of oxidative stress in the periphery may induce formation of the chorion laeve. If trophoblast invasion is severely impaired, plugging of the spiral arteries is incomplete, and onset of the maternal intervillous circulation is premature and widespread throughout the placenta. Syncytiotrophoblastic oxidative damage is extensive, and likely a major contributory factor to miscarriage. Between these two extremes will be found differing degrees of trophoblast invasion compatible with ongoing pregnancy but resulting in deficient conversion of the spiral arteries and an ischemia-reperfusion-type phenomenon. Placental perfusion will be impaired to a greater or lesser extent, generating commensurate placental oxidative stress that is a major contributory factor to preeclampsia. Miscarriage, missed miscarriage, and early- and late-onset preeclampsia represent a spectrum of disorders secondary to deficient trophoblast invasion.

Expression of extracellular matrix metalloproteinase inducer in human placenta and fetal membranes at term labor.

Matrix metalloproteinases (MMPs) are the main mediators of extracellular matrix (ECM) degradation during human parturition. However, the mechanisms involved in regulation of MMP production during parturition remain poorly understood. Recently, an extracellular matrix metalloproteinase inducer (EMMPRIN) has been shown to play a key role, as a local regulator, in stimulating MMP production in cancer systems. Whether EMMPRIN is expressed and stimulates MMP production in human placenta and fetal membranes is presently unknown. In this study, we investigated the expression of EMMPRIN at the levels of mRNA and protein in human term placenta and fetal membranes with or without labor. Western blot analysis showed that EMMPRIN protein was detected in term placenta and fetal membranes at two molecular masses of 40 and 65 kDa (glycosylated protein) and one of approximately 30 kDa (nonglycosylated protein). The ratio of 65 kDa EMMPRIN to total EMMPRIN significantly increased (P < 0.05) in term labor chorio-decidua and amnion compared with nonlabor chorio-decidua and amnion. Immunohistochemical analysis revealed that EMMPRIN was expressed in placental syncytiotrophoblast, amniotic epithelial cells, trophoblast cells of chorion laeve, and decidua parietalis. EMMPRIN was also detected at the mRNA level using RT-PCR in cultured placental syncytiotrophoblast, amniotic epithelial cells, and chorionic trophoblast cells. We conclude that human placenta and fetal membranes express EMMPRIN, with the potential to stimulate MMP production, thereby facilitating fetal membrane rupture and leading to detachment of the placenta and fetal membranes from the maternal uterus at the time of parturition.

Raised prorenin and renin concentrations in pre-eclamptic placentae when measured after acid activation

Aim The aim of the study was to ascertain if there was any difference in the levels of prorenin and active renin between pre-eclamptic and normotensive feto-placental tissues. Methods Supernatants of homogenates from fresh, vaginally delivered placentae from 15 normotensive and 15 pre-eclamptic women were measured for renin concentration (RC), prorenin concentration and renin activity (RA). RA and RC were measured in the absence and presence of nephrectomised sheep plasma, respectively. Prorenin was estimated as the difference between renin concentration in the sample before and after acid activation. All concentrations are expressed as rate of angiotensin generation (ng/ml/h). Angiotensin I was measured by radioimmunoassay. Statistical analysis was performed using Student's ‘ t’ test for unpaired samples. All results are presented as mean ± SEM. Results The concentrations of renin and prorenin were highest in the chorion laeve when compared to amnion and placenta ( p<0.01) in both the groups. Furthermore, the concentrations of renin and prorenin were significantly higher in all the tissues from women with pre-eclampsia ( p<0.01). Conclusion Renin and prorenin levels are raised in the placental tissues from women with pre-eclampsia. With recent evidence suggesting that both prorenin and renin may have cellular effects independent of angiotensin II generation, there is a need for further study into its role in placentation.

Cyclic AMP enhances the expression of an extravillous trophoblast marker, melanoma cell adhesion molecule, in choriocarcinoma cell JEG3 and human chorionic villous explant cultures.

Human trophoblasts consist of two main cell lineages, villous trophoblasts (VT) and extravillous trophoblasts (EVT). To identify the molecules which are involved in EVT differentiation, we have raised a monoclonal antibody (mAb) designated CHL1, by immunizing a mouse against human chorion laeve which is composed of EVT. By immunohistochemical analysis, the CHL1 antigen was found to be expressed on the majority of EVT but not on VT in addition to its expression on endothelial and myometrial cells. A subsequent cDNA panning method revealed that the CHL1 antigen was identical to melanoma cell adhesion molecule (MCAM, Mel-CAM, S-endo 1 or MUC18/CD146), which has been previously reported as one of the EVT markers. MCAM expression on JEG3 cells, a human choriocarcinoma-derived cell line, was significantly enhanced when they were co-cultured with isolated human decidual tissue. Various cytokines and growth factors that were reportedly present in decidual tissue failed to increase MCAM expression in JEG3 cells, but decidua-induced MCAM expression in JEG3 cells was attenuated by the addition of protein kinase A inhibitor H89. In addition, cAMP, which is known to stimulate differentiation of VT, enhanced MCAM expression in JEG3 cells. Its promoting effect on MCAM expression was also observed in human chorionic villous explant cultures. These findings suggest that a cAMP-dependent intracytoplasmic signalling pathway is involved in the differentiation mechanism of human EVT.

The control of prostaglandin endoperoxide H-Synthase-2 expression in the human chorion laeve at term.

Prostaglandin endoperoxide H synthase-2 (PGHS-2), the key enzyme of prostaglandin biosynthesis in gestational tissues, is expressed in the chorion laeve at term. We have determined the mechanisms that control the level of PGHS-2 mRNA in the chorion membrane in order to assess the significance of chorion-derived prostaglandins in term labor. Chorion membranes were collected after elective cesarean delivery (CD, n = 21) and after spontaneous labor (SL, n = 20) at term. The PGHS-2 gene transcription rate was measured by transcriptional run-on, and PGHS-2 mRNA and heterogeneous RNA (hnRNA) abundance was determined by quantitative real-time reverse transcriptase polymerase chain reaction. PGHS-2 mRNA stability, PGHS-2 hnRNA processing rate, and the short-term dynamics of the two RNA species were characterized in 0-24-hour-long tissue incubations. The transcriptional activity of the PGHS-2 gene predicted (P <.02) the abundance of PGHS-2 mRNA and hnRNA in individual tissues. PGHS-2 gene activity and hnRNA processing rate were not different in the CD and SL groups. PGHS-2 mRNA was constitutively stable before and after labor, and its abundance spontaneously increased sixfold in tissues incubated for 24 hours. At the same time, PGHS-2 gene activity decreased by 80% within 2 hours and rebounded to 60% of its initial level by 24 hours. PGHS-2 mRNA is highly stable, and its abundance is transcriptionally controlled in the chorion laeve at term. Labor is not associated with changing PGHS-2 gene activity. Endogenous factors drive PGHS-2 gene transcription in the chorion, and the stable PGHS-2 mRNA accumulates in the tissue at term. This accumulation has little or no impact on the timing of labor.

Expression of Membrane Prostaglandin E Synthase in Human Placenta and Fetal Membranes and Effect of Labor

Initiation and maintenance of labor in humans is associated with an increase in prostaglandin synthesis by intrauterine tissues. The objective of the present study was to characterize the distribution of membrane-bound PGES (mPGES) protein and mPGES mRNA in human placenta, fetal membranes, and decidua at term and to determine whether any changes occurred with labor. Immunoreactive mPGES was found to be highly concentrated in amnion epithelial cells and the chorion laeve trophoblasts, with lower levels in the mesenchymal layers. The enzyme was at very low levels or undetectable in the decidual tissue. Much lower levels of mPGES protein and mRNA were found in placenta than in fetal membranes. mPGES was associated with the syncytiotrophoblast and in cells surrounding blood vessels. The expression of mPGES mRNA did not change with labor in full membranes or placenta, but Western analysis showed an increase in mPGES protein in chorion laeve and a decrease in mPGES protein in placenta during labor, with no change in the amnion. The differences in expression found among placenta, chorion, and amnion before and after labor would indicate that this enzyme is differentially regulated in these tissues at this time.

Expression of nitric oxide synthase isoforms in the human placenta is not altered by labor.

Nitric oxide has various biological activities including smooth muscle relaxation, anti-inflammatory activity, anti-coagulatory activity. As the human placenta is known to express nitric oxide synthases, this study investigated the possible effect of labor on the expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in human placental tissues at term. Both eNOS and iNOS mRNA expression in placental tissues in labor were significantly higher than those in the amnion, chorion laeve, decidua vera and myometrium. The eNOS mRNA and protein expressions in placental tissues in labor (n = 12) were 1.6023 +/- 0.1652 (eNOS/GAPDH, mean +/- SEM) and 12.8 +/- 1.3 arbitrary units (AU), respectively, which were similar to those not in labor (n = 10), 1.5806 +/- 0.2042 (eNOS/GAPDH) and 11.4 +/- 1.8 AU. The iNOS mRNA and protein expressions in the placental tissues in labor were 1.2831 +/- 0.2436 (iNOS/GAPDH) and 10.7 +/- 2.1 AU respectively, similar to those not in labor, 1.9254 +/- 0.8004 (iNOS/GAPDH) and 13.3 +/- 1.8 AU. The guanosine 3',5'-cyclic monophosphate (cGMP) concentration in the placental tissues in labor was 23.6 +/- 1.4 fmol/g wet tissue, similar to that not in labor, 26.1 +/- 2.0 fmol/g wet tissue. These findings suggest that nitric oxide production in the human placenta is maintained during labor.

Trophoblastic Oxidative Stress in Relation to Temporal and Regional Differences in Maternal Placental Blood Flow in Normal and Abnormal Early Pregnancies

Onset of the maternal-placental circulation was studied by Doppler ultrasonography in 65 pairs of age-matched normal and abnormal pregnancies. In normal pregnancies intervillous blood flow increased with gestational age, being detected in 9 of 25 cases at 8 to 9 weeks but in 18 of 20 at 12 to 13 weeks (P = 0.001). By contrast, in abnormal pregnancies flow was detected in nearly all cases (22 of 25) at 8 to 9 weeks (P < 0.001). In addition, regional differences were observed between the groups. Early flow was restricted to the peripheral regions of most normal placentas (P < 0.001), whereas in missed miscarriages it was most common in central regions or throughout the placenta (P < 0.05 and P < 0.001, respectively). Immunoreactivity for heat shock protein 70 and nitrotyrosine residues was greater in samples from peripheral than from central regions of normal placentas (P = 0.028 and P = 0.019, respectively), and from missed miscarriages compared to controls (P = 0.005 and P = 0.001, respectively). Our results indicate that oxidative damage to the trophoblast, induced by premature and widespread onset of the maternal placental circulation secondary to shallow trophoblast invasion, is a key factor in early pregnancy loss. High oxygen concentrations in the periphery of normal early placentas may similarly induce local regression of the villi, leading to formation of the chorion laeve.

Progesterone receptor Localization and Isoforms in Myometrium, Decidua, and Fetal Membranes From Rhesus Macaques: Evidence for Function Progresterone Withdrawal at Parturtion

It is not known whether withdrawal of progesterone (P) action is a prerequisite for parturition in women or in nonhuman primates because concentrations of circulating progesterone or progesterone receptors (PR) in myometrium and decidua do not decrease before delivery. To examine this potentially important regulatory mechanism, we determined PR isoforms, PR localization, and mRNA in myometrium, decidua, and fetal membranes from rhesus monkeys during pregnancy and in spontaneous labor at term. Gestational tissues were obtained midpregnancy (day 80-100), late pregnancy (day 130-145), and during spontaneous labor at term (day 161-167). Samples of rhesus monkey myometrium, decidua, chorion-decidua, and amnion were collected and analyzed for total nuclear and cytosolic PR by competitive binding assay. Progesterone receptor isoforms were identified and quantified by Western blot analysis, and PR mRNA was determined by a specific ribonuclease protection assay. Nuclear PR was localized by immunohistochemistry with monoclonal anti-PR (JZB39) after microwave stabilization. Myometrium and decidua showed no change in total PR during pregnancy and labor. Nuclear PR was not detected in fetal membranes by binding assay but was localized in amnion epithelial and mesenchymal cells and in chorion laeve cytotrophoblasts by immunohistochemistry. Staining for PR was substantially less by serial antibody dilution in fetal membranes than in decidua. Message for PR was confirmed in all tissues analyzed. A significant (P <.05) shift in the ratio of PR isoforms (from PR-B dominance at midpregnancy to PR-A dominance in labor) was observed in myometrium but not in decidua. Both PR-A and PR-B isoforms and PR nuclear staining were nearly undetectable in amnion obtained during labor. A shift to PR-A dominance in myometrium at term together with a loss of PR in fetal membranes provides evidence for a functional progesterone withdrawal mechanism, which may facilitate the initiation of parturition in primates.

Localization of Nuclear Factor-κB (NFκB) and Inhibitory Factor-κB (IκB) in Human Fetal Membranes and Decidua at Term and Preterm Delivery

The human fetal membranes and decidua are thought to be involved in the onset of human parturition. These tissues produce and respond to various cytokines, which may be involved in preterm labour and possibly term labour. They also show increasing production of prostaglandins (PGs) with advancing gestation and labour. The expression of PGHS-2, a rate limiting enzyme in PG synthesis, is increased in the fetal membranes at labour. The gene for PGHS-2 and many of the cytokine genes (e.g. TNFα, IL-1, IL-6) are stimulated by the transcription factor NFκB. This factor is composed of two subunits, p50 and p65, which are localized in the cytoplasm bound to IκB. When activated IκB is metabolized, and p50, p65 translocate to the nucleus to activate various genes. The purpose of the present study was to examine the tissue and cellular distribution of p65 and IκB in the human fetal membranes and decidua throughout gestation. Term tissues were obtained prior to labour by elective caesarean section (n=10) or following vaginal delivery (n=10) and 10 preterm tissues were obtained following labour prior to 37 weeks gestation. None of the tissues had any evidence of infection. The immunoreactive NFκB and IκB were localized in the tissues. p65 protein was found in the nucleus and cytoplasm of cells in the amnion, chorion laeve and decidua. In the amnion and chorion laeve, no changes occurred in subcellular localization with advancing gestation or term labour. However, in the decidua, there was a marked increase in the nuclear localization of i.r. p 65 in tissues obtained at term when compared with tissues delivered preterm. In the case of IκB, it was localized to the cytoplasm of cells in all tissues and there was an increase i.r. IκB in decidua at term compared to preterm but no change occurred in the amnion or chorion. The increase in nuclear localization of p65 in the decidua that occurs with advancing gestation, highlights the potential importance of this factor in the regulation of parturition related genes in this tissue.

Site-specific augmentation of amnion cyclooxygenase-2 and decidua vera phospholipase-A2 expression in labor: possible contribution of mechanical stretch and interleukin-1 to amnion prostaglandin synthesis.

To investigate a possible site-specific augmentation of prostaglandin (PG) synthesis in the fetal membranes during labor. We used reverse transcriptase-polymerase chain reaction or Western blot analysis to evaluate the expression of cytosolic phospholipase A2 (cPLA2) and cyclooxygenase-1, -2 (COX-1, -2), in both the upper and lower parts of the amnion, chorion laeve, and decidua vera tissues from term pregnant women before (n = 8) and after labor (n = 24). Prostaglandin E2 (PGE2) secretion from amnion-derived WISH cells was assessed using enzyme-linked immunosorbent assay after stimulation by cyclic mechanical stretching and interleukin-1 (IL-1). The expression of cPLA2 and COX-1 and COX-2 mRNAs was detected in all samples examined. Western blot analysis revealed that COX-2 expression in the upper part of the amnion, chorion laeve, and decidua vera tissues after labor was 4.7-, 4.9-, and 3.7-fold higher than that before labor, respectively (P < .05 for all). The cPLA2 protein expression in the upper part of the amnion and chorion laeve tissues after labor was 14.0- and 8.8-fold higher than that before labor, respectively (P < .05 for both). Moreover, in specimens obtained after labor, the amnion COX-2 expression and the decidua vera cPLA2 expression in the lower part of the fetal membrane was 1.9- and 2.6-fold higher than the respective levels in the upper part (P < .05 for both). In an in vitro study, cyclic mechanical stretching significantly enhanced IL-1-augmented PGE2 secretion from WISH cells. In the lower part of the amnion and decidua vera tissues, adjacent to the dilating cervical canal, PG synthesis was upregulated site specifically after labor. Such enhancement of amnion PG synthesis might be regulated at least partly by IL-1 and cyclic distension.

Site-Specific Augmentation of Amnion Cyclooxygenase-2 and Decidua Vera Phospholipase-A2 Expression in Labor: Possible Contribution of Mechanical Stretch and Interleukin-1 to Amnion Prostaglandin Synthesis

To investigate a possible site-specific augmentation of prostaglandin (PG) synthesis in the fetal membranes during labor. We used reverse transcriptase-polymerase chain reaction or Western blot analysis to evaluate the expression of cytosolic phopholipase A2 (cPLA2) and cyclooxygenase-1, -2 (COX-1, -2), in both the upper and lower parts of the amnion, chorion laeve, and decidua vera tissues from term pregnant women before (n = 8) and after labor (n = 24). Prostaglandin E2 (PGE2) secretion from amnion-derived WISH cells was assessed using enzyme-linked immunosorbent assay after stimulation by cyclic mechanical stretching and interleukin-1 (IL-1). The expression of cPLA2 and COX-1 and COX-2 mRNAs was detected in all samples examined. Western blot analysis revealed that COX-2 expression in the upper part of the amnion, chorion laeve, and decidua vera tissues after labor was 4.7-, 4.9-, and 3.7-fold higher than that before labor, respectively (P < .05 for all). The cPLA2 protein expression in the upper part of the amnion and chorion laeve tissues after labor was 14.0- and 8.8-fold higher than that before labor, respectively (P < .05 for both). Moreover, in specimens obtained after labor, the amnion COX-2 expression and the decidua vera cPLA2 expression in the lower part of the fetal membrane was 1.9- and 2.6-fold higher than the respective levels in the upper part (P < .05 for both). In an in vitor study, cyclic mechanical stretching significantly enhanced IL-1-augmented PGE2 secretion from WISH cells. In the lower part of the amnion and decidua vera tissues, adjacent to the dilating cervical canal, PG synthesis was upregulated site specifically after labor. Such enhancement of amnion PG synthesis might be regulated at least partly by IL-1 and cyclic distension.

Expression of Matrix Metalloproteinase (MMP)-2 and MMP-9 in Human Placenta and Fetal Membranes in Relation to Preterm and Term Labor

Extensive extracellular matrix (ECM) remodeling is found in many processes during human parturition at term and preterm. These include cervical ripening, fetal membrane rupture, and placental detachment from the maternal uterus. Matrix metalloproteinases (MMPs) are the main mediators of ECM degradation. The present study was designed to investigate the expression of MMP-2 and MMP-9 in human fetal membranes (FMs) and placental (PL) tissues with or without labor at preterm and term parturition. Both zymography and Western blot analysis showed that MMP-9 was significantly (P < 0.01) increased in preterm and term labor FM, compared with nonlabor. Term labor PL also had a much higher (P < 0.05) level of MMP-9 than that of term nonlabor. No significant difference in MMP-2 expression was found between labor and nonlabor tissues. Immunolocalization studies revealed a specific distribution pattern for MMP-2 and MMP-9. MMP-2 was localized to the amnion mesenchyme, chorion laeve trophoblast, decidua parietalis, and blood vessels in PL villi. MMP-9 was localized mainly to amnion epithelia, chorion laeve trophoblast, decidua parietalis, and PL syncytiotrophoblasts. Separate cell culture from different layers of FM and culture of purified PL trophoblast cells showed that PL syncytiotrophoblast and amnion epithelial cells exclusively produced MMP-9; chorion trophoblast cells secreted both MMP-2 and MMP-9, but amnion mesenchymal cells produced only MMP-2. We concluded that MMP-2 and MMP-9 exhibited cell-specific expression in the human PL. An increase in MMP-9 expression may contribute to degradation of the ECM in the FM and PL, thereby facilitating FM rupture and PL detachment from the maternal uterus at labor, both preterm and term.

Expression of matrix metalloproteinase (MMP)-2 and MMP-9 in human placenta and fetal membranes in relation to preterm and term labor.

Extensive extracellular matrix (ECM) remodeling is found in many processes during human parturition at term and preterm. These include cervical ripening, fetal membrane rupture, and placental detachment from the maternal uterus. Matrix metalloproteinases (MMPs) are the main mediators of ECM degradation. The present study was designed to investigate the expression of MMP-2 and MMP-9 in human fetal membranes (FMs) and placental (PL) tissues with or without labor at preterm and term parturition. Both zymography and Western blot analysis showed that MMP-9 was significantly (P < 0.01) increased in preterm and term labor FM, compared with nonlabor. Term labor PL also had a much higher (P < 0.05) level of MMP-9 than that of term nonlabor. No significant difference in MMP-2 expression was found between labor and nonlabor tissues. Immunolocalization studies revealed a specific distribution pattern for MMP-2 and MMP-9. MMP-2 was localized to the amnion mesenchyme, chorion laeve trophoblast, decidua parietalis, and blood vessels in PL villi. MMP-9 was localized mainly to amnion epithelia, chorion laeve trophoblast, decidua parietalis, and PL syncytiotrophoblasts. Separate cell culture from different layers of FM and culture of purified PL trophoblast cells showed that PL syncytiotrophoblast and amnion epithelial cells exclusively produced MMP-9; chorion trophoblast cells secreted both MMP-2 and MMP-9, but amnion mesenchymal cells produced only MMP-2. We concluded that MMP-2 and MMP-9 exhibited cell-specific expression in the human PL. An increase in MMP-9 expression may contribute to degradation of the ECM in the FM and PL, thereby facilitating FM rupture and PL detachment from the maternal uterus at labor, both preterm and term.