Decidua Vera Tissue Research Articles

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.

Inactivation of prostaglandins in human decidua vera (parietalis) tissue: Substrate specificity of prostaglandin dehydrogenase

Prostaglandin dehydrogenase catalyzes the initial reaction in the inactivation of prostaglandin E2 and F2 alpha. To address the potential importance of this enzyme in regulating the tissue levels of active prostaglandins, we evaluated the kinetic properties of prostaglandin dehydrogenase in uterine decidua vera tissue of women. Specifically, we characterized the enzyme activity under optimal in vitro conditions in cytosolic fractions of uterine decidua vera tissue obtained at term and compared the substrate and cosubstrate specificities of prostaglandin dehydrogenase in cytosolic fractions of decidual tissues. The incubation conditions were optimized with either prostaglandin E2 or F2 alpha and nicotinamide-adenine dinucleotide or nicotinamide-adenine dinucleotide phosphate as substrates to ensure linearity of product formation with time of incubation and protein concentration. The apparent Michaelis-Menten constant of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase for prostaglandin E2 was 5.5 mumol/L. The apparent Michaelis-Menten constant of nicotinamide-adenine dinucleotide phosphate-dependent prostaglandin dehydrogenase for prostaglandin F2 alpha was 15 mumol/L. Prostaglandin E2 serves as a better substrate for prostaglandin dehydrogenase than does prostaglandin F2 alpha, irrespective of the cosubstrate. In cytosolic fractions of decidual tissues, the specific activity (apparent Vmax) of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase was greater than that of nicotinamide-adenine dinucleotide phosphate-dependent prostaglandin dehydrogenase. In addition, we found that in decidual tissue obtained before or after the onset of labor, the specific activity of prostaglandin dehydrogenase varied widely. In tissues obtained after delivery by cesarean section, no significant differences were apparent in the specific activity of the enzyme before (9.3 to 125.8 nmol/min/mg protein) and after (27.8 to 103.4 nmol/min/mg protein) the onset of labor. In cytosolic fractions of decidual tissue obtained after vaginal delivery, the specific activity of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase ranged from undetectable levels to 38.4 nmol/min/mg protein. We speculate that nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase in decidua serves to regulate the levels of bioactive prostaglandins in decidua vera tissue and the amounts of prostaglandins (and metabolites) produced in decidua or fetal membranes that reach myometrium and fetal membranes and enter maternal blood and amniotic fluid.

Prostaglandin E2 9-ketoreductase activity in human decidua vera tissue

Amnion is believed to be a tissue of central importance in the biochemical processes of parturition. In this tissue, prostaglandin E2 is the near exclusive prostaglandin produced. And although the production of prostaglandin E2 is increased during labor in women, the levels of the major metabolite of prostaglandin E2 in maternal plasma are not elevated; rather, the levels of 13,14-dihydro-15-ketoprostaglandin F2α, the major circulating metabolite of prostaglandin F2α, are increased strikingly. Because of this apparent paradox, we considered the possibility that prostaglandin E2, originating in amnion, chorion laeve, or decidua vera, is converted to prostaglandin F2α in decidua vera by the action of prostaglandin E2-9-ketoreductase. We found that prostaglandin E2 9-ketoreductase, the enzyme that catalyzes the conversion of prostaglandin E2 to F2α, is present in cytosolic fractions prepared from homogenates of uterine decidua vera tissue. The specific activity of 9-ketoreductase in cytosolic fractions of decidua of six women varied from 3.2 to 155 pmol × min−1 × mg−1 protein. We also evaluated the conversion of exogenous prostaglandin E2 to F2α in intact human endometrial stromal cells in monolayer culture. We found that prostaglandin E2, added to the culture medium, was converted to prostaglandin F2α by endometrial stromal cells that were maintained in the presence of inhibitors of prostaglandin synthase. The extent of conversion of exogenous prostaglandin E2 to F2α, however, was low relative to the specific activity of prostaglandin E2 9-ketoreductase found in decidual cytosol. These findings are consistent with the possibility that prostaglandin E2 formed in decidua vera tissue may be converted in that tissue to prostaglandin F2α by 9-ketoreductase; on the other hand, prostaglandin E2 formed in contiguous tissues probably is not converted significantly to prostaglandin F2α by decidual 9-ketoreductase.

Separation and quantitation of fatty acids by high-performance liquid chromatography

To facilitate the determination of the fatty acid composition of tissues and the investigation of fatty acid metabolism, we developed a method for the rapid separation by high-performance liquid chromatography and quantitation (by ultraviolet light absorption) of p-bromophenyl esters of fatty acids which vary in chain length from 10 to 22 carbon atoms. The utility of the method was demonstrated by evaluating the fatty acid composition of human uterine decidua vera tissue and human endometrial stromal cells that are maintained in monolayer culture.

The identification and characterization of protein kinase C activity in fetal membranes

Protein kinase C activity was demonstrated in cytosolic fractions prepared from human amnion and decidua vera tissues. The enzyme has been partially purified and was found to be glycerophospholipid-dependent. Phosphatidylserine was most active in the stimulation of protein kinase C. Ca 2+ was also required for the expression of the enzyme activity. In the presence of unsaturated diacylglycerols, maximum activation of protein kinase C was observed at suboptimal concentrations of Ca 2+. A possible role of phospholipid-dependent protein kinase C in the regulation of arachidonic acid release in this tissue is discussed.

Characterization of ornithine decarboxylase activity in human uterine decidua vera

Ornithine decarboxylase (ODC) catalyzes the rate-limiting step in the biosynthesis of the polyamines putrescine, spermidine, and spermine. In the present study, we characterized the activity of ODC in human uterine decidua vera tissue. We evaluated the activity of the enzyme in decidua vera tissue that was obtained from pregnancies at term before or after the spontaneous onset of labor and in decidua vera tissue that was obtained between 8 and 18 weeks' postconceptional gestational age at the time of elective abortion. Among these tissues, no significant differences in ODC activity were demonstrable.

Characterization of catechol-O-methyltransferase activity in human uterine decidua vera tissue

In the present investigation, we characterized the activity of catechol-O-methyltransferase (COMT) in homogenates prepared from human decidua vera tissue. The specific activity of COMT in decidua vera is greater than that in liver and myometrium and much greater than that in adipose tissue and erythrocytes. The specific activity of COMT in decidua vera obtained at term was significantly greater (p < 0.001) than that obtained early in gestation. However, we do not as yet ascribe physiologic significance to this finding since the period of time between delivery of the tissue and assay of the enzyme activity may have varied between the two groups.

Initiation of human parturition: XIII. Phospholipase C, phospholipase A2, and diacylglycerol lipase activities in fetal membranes and decidua vera tissues from early and late gestation.

Phospholipase C, phospholipase A2, and diacylglycerol lipase activities in human amnion, chorion laeve, and uterine decidua vera tissues obtained in early and late gestation were examined. The specific activities of phospholipase C in amnion tissues obtained at 13–17 and 38–41 weeks gestation were 1.1 and 6.3 μmol • h−1 • mg−1 protein, respectively. A similar fold-increase in the specific activity of phospholipase A2 in amnion tissue obtained from early and late gestational periods was also observed (3.5 to 12.6 nmol • h−1 • mg−1 protein). In late gestation, the specific activities of phospholipase A2 and phospholipase C were greater in amnion tissue than in either chorion laeve or decidua vera tissues. Diacylglycerol lipase activity also was demonstrated in these three tissues. No change in the specific activity of diacylglycerol lipase was observed in any of the three tissues as gestation advanced. The specific activity of diacylglycerol lipase was greatest in decidua vera tissue. The increase in amnion tissue of the specific activities of phospholipase C and A2 during gestation suggests that this tissue may occupy a central role in the regulation of prostaglandin formation that accompanies human parturition and may provide an explanation for the preferential loss of arachidonic acid from phosphatidylinositol and phosphatidylethanolamine in amnion that occurs during early labor in the human.

Diacylglycerol metabolism and arachidonic acid release in human fetal membranes and decidua vera.

Diacylglycerol lipase activity has been demonstrated in human fetal membranes and decidua vera tissues. The specific activity of the enzyme is highest in the microsomal fraction of decidua vera tissue. The acylester bond at the sn-1 position of 1,2-diacyl-sn-glycerol is hydrolyzed followed by release of the fatty acid at the sn-2 position. The diacylglycerol lipase activity present in the microsomal fraction of decidua vera tissue hydrolyzes preferentially a diacylglycerol containing an arachidonoyl group in the sn-2 position. Monoacylglycerol lipase activity was also demonstrated in these tissues. The specific activity of monoacylglycerol lipase was significantly greater than that of diacylglycerol lipase and catalyzed preferentially the hydrolysis of monoacylglycerols containing an arachidonyl group in the sn-2 position. Based on the subcellular distribution and the differential effects of various inhibitors, we suggest that the monoacylglycerol lipase and diacylglycerol lipase in decidua vera tissue are 2 distinct enzymes. Diacylglycerol kinase specific activity was examined also and was found to be 4-5 times greater in amnion than in either chorion laeve or decidua vera. The importance of diacylglycerol metabolism in the mechanism of arachidonic acid release and prostaglandin biosynthesis is discussed.

Initiation of human parturition: XII. Biosynthesis and metabolism of prostaglandins in human fetal membranes and uterine decidua

Prostaglandin synthetase activity was assayed in homogenates prepared from human fetal membranes and uterine decidua tissues with [14C]arachidonic acid used as substrate. In amnion, chorion laeve, and decidua vera tissues obtained after the spontaneous onset of labor and vaginal delivery the mean specific activities of prostaglandin synthetase were respectively 1.47, 0.53, and 0.39 nmoles × hr−1 × gm−1 tissue; in these same tissues obtained at elective cesarean section before the onset of labor the mean specific activities of prostaglandin synthetase were respectively 0.61, 0.33, and 0.28. The specific activity of prostaglandin synthetase of amnion (but not chorion laeve or decidua vera) was significantly greater in samples obtained after labor than in those obtained before labor (p < 0.02). Prostaglandin synthesis in amnion, chorion laeve, and decidua vera was inhibited by acetylsalicylic acid and by indomethacin. Prostaglandin E2 was formed in amnion and chorion laeve, whereas prostaglandin E2 and prostaglandin F2α were formed in decidua vera. The activity of NAD+-dependent 15-hydroxyprostaglandin dehydrogenase was also assayed and the specific activities of this enzyme in chorion laeve and decidua vera tissues obtained before and after labor were high, whereas 15-hydroxyprostaglandin dehydrogenase activity in amnion was low.