Epithelial cell-derived neutrophil-activating peptide-78 is present in fetal membranes and amniotic fluid at increased concentrations with intra-amniotic infection and preterm delivery

Intra-amniotic secretion and abundance of epithelial cell-derived neutrophil-activating peptide (ENA)-78, a potent chemoattractant and activator of neutrophils, was studied in the context of term and preterm parturition. Staining of ENA-78 immunoperoxidase was localized predominantly to chorionic trophoblasts and amniotic epithelium in term and preterm gestational membranes, with weaker and less consistent staining in decidual cells. The abundance of ENA-78 in membrane tissue homogenates was significantly increased ( approximately 4-fold) with term labor in amnion (n = 15), and with preterm labor ( approximately 30-fold) in amnion and choriodecidua (n = 31). In amnion tissue homogenate extracts, ENA-78 levels were positively correlated with the degree of leukocyte infiltration (r2 = 0.481). In amniotic fluids, median ENA-78 levels from pregnancies with preterm labor without intra-amniotic infection were significantly lower (P < 0.01 by ANOVA) than those from pregnancies with preterm deliveries with infection; levels in samples derived from term pregnancies were similar before and after labor. Production of ENA-78 by amnion monolayers was stimulated in a concentration-dependent fashion by both interleukin-1beta and tumor necrosis factor alpha. Production of ENA-78 by choriodecidual explants was increased modestly after 2-4 h of exposure to lipopolysaccharide (5 microg/ml). An immunoreactive doublet ( approximately 8 kDa) was detected in choriodecidual explant-conditioned media by immunoblotting. We conclude that ENA-78, derived from the gestational membranes, is present in increased abundance in the amniotic cavity in response to intrauterine infection and, hence, may play a role in the mechanism of infection-driven preterm birth and rupture of membranes secondary to leukocyte recruitment and activation.

Quantitative chemical identification of four gases in remote infrared (9-11 mum) differential absorption lidar experiments

A combined experimental and computational approach utilizing tunable CO(2) lasers and chemometric analysis was employed to detect chemicals and their concentrations in the field under controlled release conditions. We collected absorption spectra for four organic gases in the laboratory by lasing 40 lines of the laser in the 9.3-10.8-mum range. The ability to predict properly the chemicals and their respective concentrations depends on the nature of the target, the atmospheric conditions, and the round-trip distance. In 39 of the 45 field experiments, the identities of the released chemicals were identified correctly without predictions of false positives or false negatives.

5-Hydroxyeicosatetraenoic acid and human parturition

5-Hydroxyeicosatetraenoic acid (5-HETE) is an arachidonic acid (AA) metabolite derived from the lipoxygenase pathway which is capable of inducing uterine contractions. The purpose of this study was to determine a). whether 5-HETE concentrations in amniotic fluid increase before or after the onset of labor and b). whether acetylsalicylic acid (ASA) could modulate the production of 5-HETE by human amnion cells. 5-HETE concentrations are increased in amniotic fluid before the onset of labor. Furthermore, ASA treatment as expected inhibited PGE2, but also significantly increased 5-HETE production by amnion cells. 5-HETE concentrations on average increased by greater than 2.5 fold (p < 0.001) in amniotic fluid prior to spontaneous labor when compared with samples obtained from the same patients earlier in gestation and therefore may be important in mechanisms regulating the onset of labor. ASA provokes an increase in 5-HETE biosynthesis by amnion cells: control media 2.60 +/- 1.5, ASA treatment alone 5.17 +/- 0.20, IL-1 beta alone 6.39 +/- 2.1, and ASA + IL-1 beta 8.95 +/- 1.2 (mean +/- SEM) picograms per microgram protein per 16 hours. These findings may explain in part why cyclooxygenase inhibitors are not always successful in treating women with preterm labor.

Prostaglandins and parturition

It seems likely that prostaglandins play a significant part in the mechanisms of parturition both at term and preterm. Concentrations of prostaglandins are increased in the blood, urine and amniotic fluid during labour. There are differences in the concentrations of prostaglandins in amniotic fluid from the forebag and hindbag. Nevertheless, if liquor is sampled only from the hindbag a highly significant increase in prostaglandin concentrations occurs throughout labour. Furthermore, we now have evidence that prostaglandin concentrations in amniotic fluid increase before the onset of labour. Prostaglandins are synthesized by uterine tissues and increased rates of production occur during labour. The amnion, chorion and decidua all contain mRNA for the newly-discovered inducible form of prostaglandin H synthase (PGHS-2) as well as mRNA for the constitutive form (PGHS-1). Using the reverse transcription polymerase chain reaction (RT-PCR) both mRNAs can be detected during late pregnancy whether women are in labour or not. PGHS-2 protein is detected by Western blot analysis in cells derived from all three tissues. There is regulation of PGHS-2 protein amounts by cytokines, phorbol esters and growth factors. For example, in amnion cells interleukin-1 beta induces a rapid increase in PGHS-2 mRNA levels followed by a decrease to undetectable levels within 4 h of treatment; PGHS-2 protein amounts are also elevated by this treatment. Administration of prostaglandins will induce labour and delivery, whereas inhibition of prostaglandin biosynthesis will delay labour and delivery. Hence, increased prostaglandin production is likely to be a key determinant of the onset and progression of the parturient process.

Potential agonist action of the interleukin-1 receptor antagonist protein: implications for treatment of women

The interleukin-1 receptor antagonist protein (IRAP) caused a concentration-related increase in prostaglandin production by human decidual cells. The degree and time course of this stimulatory action were identical to those induced by interleukin 1 beta (IL-1 beta). IRAP had no inhibitory action on IL-1 beta stimulation of decidual prostaglandin production and at high concentrations had an additive effect. We believe that this represents the first description of a potential agonist action of IRAP and suggests caution in treatment of women with this substance.

Isolation of multiple substances in amniotic fluid that regulate amnion prostaglandin E2 production: the effects of gestational age and labor

The present study was undertaken to evaluate the effects of whole amniotic fluid (AF) and fractions of AF on amnion cell prostaglandin E2 (PGE2) production. Amnion cells were grown to confluence and then incubated in the presence of AF, or fractions thereof, obtained at 17-19 weeks gestation (MID), at term prior to the onset of labor (NIL), and at term after spontaneous onset of labor (LABOR). All whole AFs were stimulatory to amnion cell PGE2 production (p less than 0.001) but the stimulation by NIL and LABOR AFs was significantly greater (p less than 0.001) than stimulation by the MID AF. Fractionation of the AFs from the three groups (n = 9-10 per group) revealed multiple discernable peaks of stimulatory activity in each group. The majority of peaks had retention times that were similar among the three groups, and peak stimulatory activities were greater in NIL and LABOR samples than in MID samples.

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

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

Actions of endothelin-1 on prostaglandin production by gestational tissues

Endothelin-1 (10(-11)M-10(-7)M) was incubated with human umbilical vein endothelial cells and cells derived from amnion and decidua and prostaglandin production was determined. The rates of biosynthesis of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and prostaglandin E2 (PGE2) by endothelial cells were increased significantly by treatment with endothelin-1. Amnion cell PGE2 production was reduced significantly by endothelin-1 treatment whereas decidual PGE2 and prostaglandin F2 alpha production was unaffected by this treatment. Thus, it is possible that endothelins may play a part in the regulation of uteroplacental hemodynamics and the mechanisms of parturition.

Prostaglandin biosynthesis by human decidual cells: effects of inflammatory mediators

There is substantial evidence that decidual activation, in association with infection, is linked with the onset of both preterm and term labor. We therefore undertook the present study to evaluate prostaglandin production and its potential regulation by inflammatory mediators in human decidual cells in primary monolayer culture. Upon attaining confluence, the cells were incubated with endotoxin, interleukin 1 alpha (IL1 alpha), interleukin 1 beta (IL1 beta); or tumor necrosis factor (TNF). Production of prostaglandin (PG) E2 and PGF2 alpha was determined using specific radioimmunoassays. Endotoxin and these cytokines all induced significant concentration-dependent increases in PGE2 and PGF2 alpha production. Our results suggest that term human decidual cells are responsive to endotoxin and cytokines and that generation of these substances in the decidua or nearby (eg. in response to infection) will lead to increased prostaglandin production and uterine contractions.