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The human placenta is a unique organ that performs the function of the majority of fetal organs across gestation. How the placenta communicates with maternal tissues to prepare them for pregnancy is not fully understood. Recently, it has been established that placental cells can communicate with maternal tissues to regulate their biological function via extracellular vesicles (EVs). EVs are subclassified into exosomes or microvesicles (MVs) according to their size, cell or tissue of origin, functions, and physical features. Exosomes are a specific type of EVs from an endocytic origin, while MVs are released via budding from the plasma membrane. With regards to pregnancy, the role of EVs has been described in several functions such as immune responses and maternal metabolic adaptation to gestation. Interestingly, EVs of placental origin can be detected in a variety of body fluids including urine and blood, and have been identified in the maternal circulation at as early as 6 weeks of gestation. Moreover, the number of exosomes across gestation is higher in complications of pregnancies such as preeclampsia and gestational diabetes mellitus compared to normal pregnancies. Circulating exosomes contains proteins and RNAs that are representative of the cell of origin, including surface and cytoplasmic protein, messenger RNA, and micro-RNAs. Finally, exosomes are capable of transferring their contents to other cells and regulating the biological function of the target cell. In this review, we will discuss the effect of the maternal microenvironment on secretion and content of placenta-derived EVs, and how this may lead to complications of pregnancies with a special emphasis on exosomes.

Determination of specific low abundance proteins, usually by radiolabelled or enzyme-linked immunoassays in serum or plasma is widely used in diagnostic medicine. Substitution of these assays by a proteomic approach has been suggested, but this methodology has far from realised its potential as a diagnostic tool. The main protein fractions of plasma represent more than 80% of total protein, making the hundreds or even thousands of other proteins difficult to detect by two-dimensional electrophoresis (2-DE). Thus, loading sufficient sample to detect trace proteins invariably means excessive loading of albumin and other high abundance proteins. The aim of this study was to determine whether centrifugal ultrafiltration of whole plasma could be used to eliminate proteins exceeding a desired molecular weight cut-off. Cellulose filters with a 30 kDa molecular weight cut-off were used with whole plasma, and total protein was determined before and after ultrafiltration. Samples were processed by routine methods for 2-DE using 18 cm, pH 3-10 isoelectric focusing strips for the first dimension and 7-15% gradient gels for the second dimension followed by silver staining. Gel analysis of the retentate fraction (30 kDa) revealed a typical 2-DE plasma profile with most of the major landmark proteins in place and as expected, the gels lacked many of the smaller (30 kDa) proteins. Comparison with gels of the filtrate fraction (30 kDa) revealed very little difference. Not only were many of the higher molecular weight proteins still present, but some of the smaller30 kDa landmark proteins were absent. Overall, gels of both the retentate and filtrate fractions were less informative than gels of whole plasma.

Enhanced prostaglandin production and release by the placenta is an essential element in the normal transition to labour in many animal species. In sheep, expression of prostaglandin G/H synthase (PGHS) is the central enzyme regulating this process. In this study immunohistochemistry was used to examine the distribution of cells expressing PGHS-1 and PGHS-2 in ovine placenta in association with spontaneous parturition (n = 6) and glucocorticoid-induced labour (n = 5). Labour was induced in ewes after the intrafetal injection of betamethasone on day 131 of gestation. Animals administered an intrafetal injection of isotonic saline (n = 5) acted as non-labour controls. In placentomes collected from all groups, immunoreactive PGHS-1 was present in the mononuclear trophoblast cells of the fetal placenta. Cells in the maternal mesenchyme and epithelial syncytium were weakly immunopositive for this enzyme. PGHS-1 immunoreactivity was also demonstrated in the endothelial cells of the chorionic vessels. The PGHS-2 isozyme was localized exclusively to the trophoblast epithelial cells. Immunoreactive PGHS-2 was not detectable in the maternal epithelial syncytium or the stroma of the cotyledons. The binucleate cells of the fetal placenta were consistently immunonegative for both PGHS isozymes. These results indicate that the cellular localization of PGHS-1 and PGHS-2 in ovine placenta does not change during the last 15 days of pregnancy. Co-localization of these isozymes indicates that the source of arachidonic acid and the site of prostanoid formation are the same. Quantitation of the percentage area of positive staining for PGHS-1 and PGHS-2 using image analysis software demonstrated a significant increase in PGHS-2 in the fetal trophoblast after glucocorticoid-induced labour and spontaneous parturition. This finding indicates that increased formation of the PGHS-2 isozyme is responsible for the large increase in prostaglandin production by the ovine placenta at term labour.

Interleukin-8 (IL-8) is a chemotactic cytokine that has been implicated in the process of human parturition, including the processes of cervical ripening and rupture of fetal membranes. In this study, the in vitro release of IL-8 from human amnion, choriodecidua, and placenta tissues obtained before and after spontaneous labor onset both at term and preterm, was assessed. The effect of chorioamnionitis on IL-8 release was also established. All tissue explants examined released IL-8; however, IL-8 release from choriodecidual explants was significantly (p0.02) greater than that observed from amnion and placenta. Furthermore, choriodecidual IL-8 release was significantly (p0.001) greater from term tissues (850 +/- 134.4 ng/mg DNA, n = 18) than from preterm tissues (458 +/- 68.8 ng/mg DNA, n = 17). Spontaneous onset of labor, irrespective of the eventual mode of delivery, was not associated with any significant changes in IL-8 release from human gestational tissues compared to not-in-labor tissues, both at term and preterm. IL-8 release from gestational tissues was not significantly different in the absence or presence of chorioamnionitis. These data are in contrast to the previously reported stimulatory effects of bacterial endotoxin on IL-8 release from human gestational tissues. The data are consistent, however, with the suggestion that IL-8 release is an early event in chorioamnionitis that precedes the appearance of clinically overt symptoms.

Arachidonic acid mobilisation by phospholipase A2 (PLA2) and subsequent prostaglandin synthesis is thought to be a pivotal event in the onset and/or maintenance of human labour. The purpose of this study was to examine the efficacy of a monoclonal human type II PLA2 antibody (10 B2) in reducing prostaglandin F2alpha (PGF2alpha) production in Chinese hamster ovary (CHO) cells (that overexpress human recombinant type II PLA2) and in human placental explants. 10 B2 caused a concentration-dependent inhibition of PLA2 activity (p0.00001) and PGF2alpha release (p0.01) by CHO cells. 1 microM of 10 B2 inhibited PLA2 activity (p0.00001) and PGF2alpha production (p0.0001) in human placental explants. The latter effect was significantly reversed by the addition of arachidonic acid (30 microM; p0.01). On the basis of these findings, it is proposed that 10 B2 inhibits PGF2alpha production by interfering with the extracellular activity of type II PLA2.

Interleukin (IL)-8 is a chemotactic cytokine that has been implicated in the etiology of infection-induced and normal human labor. In particular, IL-8 has been implicated in the processes of cervical ripening and rupture of fetal membranes because of its role in neutrophil activation and release of cellular matrix remodeling enzymes. In this study, we tested the hypotheses that IL-8 is released locally in the intrauterine environment from human amnion, choriodecidua, and placenta, and that IL-8 release from these tissues is increased by bacterial endotoxin, lipopolysaccharides (LPS), and inflammatory cytokines. IL-8 was released from human amnion, choriodecidual, and placental explants, with choriodecidua demonstrating the most abundant release. IL-8 release was significantly (multiple analysis of variance, p0.05) increased by LPS in a time- and dose-dependent manner from both choriodecidual and placental explants, but not from amnion explants. In addition, IL-1alpha (0.28 nM) and tumor necrosis factor alpha (TNFalpha, 10 nM) significantly (Student's t-test, p0.05) increased IL-8 release from placental explants 2- to 3-fold. These studies establish that the amnion, choriodecidua, and placenta are a source of IL-8 and demonstrate tissue-specific and differential regulation of IL-8 release by LPS, IL-1alpha, and TNF-alpha. These data support a role for IL-8 in a cascade of inflammatory events initiated by an intrauterine infection and resulting in activation of the labor process.

Older adults' memory for accurate information which either contradicted their previously held false beliefs or affirmed their previously held true beliefs about osteoarthritis was studied. Independent variables included information type (text affirms or disconfirms the reader's initial belief), explicitness of statement (explicit vs implicit statement of the target belief), filler tasks (repetition vs filter tasks), passage order, and time. Participants were 125 adults (65-80 years old) with average vocabularies who self-reported having osteoarthritis for at least two years. In support of a schema-copy plus tag model, we found (a) false alarm rates were higher for schema-related than for topic-related recognition distractors; (b) updating of erroneous opinions from pretest to immediate posttest was positively correlated with maintenance of accurate recognition from immediate to delayed posttest; and (c) disconfirming information was less accurately recognized and recalled than affirming information. Explicit text presentation and repetition of recognition and opinion tasks enhanced accurate recognition of disconfirming information. Findings suggest that older readers often have difficulty distinguishing between their erroneous prior knowledge and accurate information presented in text.

The aim of this study was to establish the effect of bacterial endotoxin lipopolysaccharide (LPS) on type II phospholipase A2 (PLA2) content and in vitro net PLA2 enzymatic activity in human choriodecidua. More particularly, the objective was to ascertain whether an increase in type II PLA2 tissue content and PLA2 enzymatic activity is associated with the previously documented stimulatory effect of LPS on prostaglandin E2 (PGE2) release from choriodecidua. Choriodecidua explants were incubated in RPMI 1640 (control) or RPMI 1640 containing LPS (0.1 ng/ml to 10 micrograms/ml) for up to 24 h. Under the incubation conditions utilized, LPS (1 microgram/ml) stimulated the release of PGE2 3-fold (p0.001, n = 4 tissues), in a time-dependent manner (p0.005). Tissue immunoreactive (ir)-type II PLA2 content and PLA2 enzymatic activity were determined by monoclonal antibody sandwich ELISA and radiolabeled enzyme assay procedures, respectively. The tissue content of type II PLA2 immunoreactivity in choriodecidua obtained from women (n = 7) at term but not in labor averaged 155 +/- 24 ng/ml DNA. PLA2 enzymatic activity average 29.8 +/- 5.1 pmol phosphatidylethanolamine (PE)/mg DNA/h. LPS at a concentration of 1 microgram/ml increased immunoreactive type II PLA2 tissue content by 180% of the control value (p0.05, n = 7) within 1 h of exposure and remained significantly elevated for 18 h when compared to controls (174% of control, p0.01, n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

A polarographic oxygen electrode technique was used to quantify the activity of prostaglandin G/H synthase present in microsomes prepared from cotyledons of ewes at 74 to 147 days of gestation (n = 25). Microsomal oxygen consumption was stimulated by arachidonic acid and suppressed significantly (p less than 0.0001) by indomethacin, a specific inhibitor of prostaglandin G/H synthase. A residual indomethacin-incentive oxygen consumption was identified but the magnitude of this component did not change during gestation. During gestation prostaglandin G/H synthase (PGHS) activity, present in ovine cotyledons, increased 22-fold, from 0.6 +/- 0.19 at 70-80 days (n = 3) to 13.22 +/- 2.08 nmol O2/min/mg protein at greater than 145 days of gestation (n = 8; p less than 0.001). This gestational increase in the PGHS activity present in ovine cotyledons was not observed when fetal hypophysectomy was performed at 70-80 days of gestation. The data obtained in this study are consistent with the hypothesis that cotyledonary PGHS activity is increased during the second half of gestation and that this increase may be dependent upon fetal pituitary factors.

The mechanisms involved in the control of oxytocin and progesterone secretion by the ovine corpus luteum have been investigated in vitro using luteal slice incubations. Oxytocin and progesterone were secreted at constant rates from luteal slices for 2 h of incubation (366 +/- 60 pg X mg X h and 18.9 +/- 0.18 ng X mg X h, respectively). Secretion of progesterone, but not of oxytocin, was significantly (p less than 0.02) stimulated in the presence of ovine luteinizing hormone. Incubation of luteal slices in medium containing 100 mM potassium, however, resulted in increased secretion of oxytocin and, to a lesser extent, of progesterone (294 +/- 59% and 142 +/- 15%, respectively, p less than 0.05). Basal oxytocin secretion was reduced during incubation in calcium-free medium, compared to secretion in the presence of calcium (70 +/- 15 and 175 +/- 25 pg X mg X 20 min, respectively, p less than 0.01), whereas progesterone secretion was not altered in the absence of calcium. Secretion of both hormones by luteal slices was stimulated by the addition of the calcium ionophore A23187 (p less than 0.05). Addition of prostaglandin F2 alpha (2.8 microM) had no effect on secretion of either oxytocin or progesterone. We have demonstrated that oxytocin and progesterone can be stimulated, independently, from corpus luteum slices incubated in vitro. The pattern of release is consistent with the proposal that oxytocin, but not progesterone, is associated with and actively released from luteal secretory granules. Our results also indicated that prostaglandin F2 alpha does not directly stimulate release of oxytocin or progesterone from luteal cells in vitro.

The capacity of the diffuse, epitheliochorial porcine placenta (chorioamnion plus endometrium: AMCE and chorioallantois plus endometrium: ALCE) and allantoamnion (ATA), obtained from sows at 47-112 days of gestation (n = 12), to release PGE2, during in vitro explant incubation, was determined. There was no significant difference between PGE2 release from AMCE and ALCE, and the data obtained from these two tissues were pooled. The release of PGE2 from ATA was, at all stages of gestation, significantly less (8-50 fold; p less than 0.01, n = 12) than that released from AMCE/ALCE. During gestation, the basal release of PGE2 from AMCE/ALCE increased from 13.7 +/- 2.8 pmol/100 mg per incubation (n = 8; mean +/- S.E.M.) at less than 80 days to a maximum of 176.5 +/- 30.9 pmol PGE2/100mg per incubation (n = 10) at greater than 109 days of gestation. Basal PGE2 release from ATA increased from 1.6 +/- 0.6 pmol PGE2/100 mg per incubation (n = 3) at less than 80 days to 3.5 +/- 0.5 pmol PGE2/100 mg per incubation at greater than 109 days gestation. At all stages of gestation and in all tissues, the addition of sodium arachidonate significantly stimulated PGE2 release, indicating that during gestation prostaglandin synthesis by porcine placenta and fetal membranes is, at least partly, substrate limited. The observed increase in the release of prostaglandin E2 from placenta and fetal membranes that occurred from 90 days of gestation and rapidly increased at term may reflect an increase in substrate availability, an increase in the activity of prostaglandin endoperoxide H synthase- E isomerase or a combination of these processes.