Keith W. Marvin

Cytokine abundance in placental tissues: Evidence of inflammatory activation in gestational membranes with term and preterm parturition ☆ ☆☆ ★

OBJECTIVES This study of the changes in cytokine concentrations in gestational tissues from women with term and preterm labor was undertaken to assess the extent of inflammatory activation associated with spontaneous labor and delivery. STUDY DESIGN Extracts of amniotic, chorionic-decidual, and placental tissues from women delivered at term before labor (n = 15), at term after labor (n = 15), and preterm (n = 31) were assayed for interleukin 1beta, interleukin 6, and interleukin 8. RESULTS In amniotic tissues of women delivered by spontaneous labor at term the median interleukin-6, interleukin-8, and interleukin-1beta concentrations were 3.8 to 5.4 times those of tissues from women delivered at term without labor (P <.05, Mann-Whitney U test). Interleukin-6 and interleukin-8 concentrations were also significantly increased (3. 3-4 times) in chorionic-decidual tissues. Marked increases (approximately 3-6 times) in the concentrations of all 3 cytokines were observed in both amniotic and chorionic-decidual tissues from women with preterm deliveries with respect to those from women with term deliveries after labor. Cytokine concentrations were significantly correlated within amniotic tissues from both women with term delivery after labor and women with preterm delivery and also in preterm chorionic-decidual tissues but not preterm placental tissues. Concentrations of cytokines in the tissues of women delivered preterm were not significantly affected by mode of delivery, treatment with antibiotics, or twin birth. In preterm tissues with evidence of intrauterine infection only amniotic interleukin-1beta concentrations were significantly elevated (P <. 05). Little or no labor-related change in cytokine concentrations was seen within placental tissues. CONCLUSIONS Increased cytokine abundance in gestational membranes associated with labor supports the view that an inflammatory process is involved in both term and preterm labor. This process does not, however, appear to be evident in the villous placenta.

UDP-glucuronosyltransferase activity, expression and cellular localization in human placenta at term

The activity, expression and localization of the UDP-glucuronosyltransferases (UGTs) were investigated in human placenta at term. UGT activity (measured with the substrate 4-methylumbelliferone (4-MU)) was observed in all 25 placentas sampled and maximum velocity (V(max)) ranged 13-fold from 5.1+/-0.9 to 66.9+/-17.5 nmol/min/mg protein (mean+/-SD). Substrate affinity (K(m)) ranged 5-fold from 246+/-24 to 1124+/-422 microM. Using reverse transcriptase-polymerase chain reaction (RT-PCR), expression of the isoforms UGT2B4, 2B7, 2B10, 2B11 and 2B15 was observed in all (12/12) placentas sampled and expression of UGT2B17 was noted in 8/12 placentas. Northern analysis of the UGT2B7 isoform in 12 placentas revealed a 10-fold difference in expression with RT-PCR variability and the 13-fold variation observed in UGT activity. The presence of UGT2B4 and 2B7 proteins (52 and 56kDa, respectively) was demonstrated by Western blotting. The sites of placental UGT2B transcription (in situ hybridization) and protein expression (immunohistochemistry) were located in the syncytium of the placental trophoblasts bordering the placental villi. UGT1A proteins could not be observed with immunohistochemistry or Western blotting and expression could not be observed with RT-PCR. Our discovery of UGT expression and activity at the site of maternal-fetal exchange is consistent with a role for UGTs in detoxification of exogenous and endogenous ligands and the maintenance of placental function through clearance and regulation of steroid hormones.

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 effect of thromboxane inhibitors on cytokine production by term primary amnion explants also were examined. Results: Prostaglandin (PG)A2, PGD2, PGF2α PGE2, PGJ2, and the PGI2 analogue carbaprostacyclin (1-1000 nmol/L) exhibited no significant effects on cytokine production. However, the thromboxane A2 (TXA2) agonists 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 ≥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-1β-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 effect of IL-1β 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.

Expression of intercellular adhesion molecule-1 (ICAM-1) in choriodecidua with labour and delivery at term and preterm.

To evaluate the association between intercellular adhesion molecule-1 (ICAM-1) in the choriodecidua and preterm labour and delivery, ICAM-1 mRNA abundance was assessed by northern analysis, and protein levels by ELISA, in samples of this tissue after term and preterm delivery. The median ICAM-1 mRNA expression following preterm delivery (PTD) was 4.8 and 3.8 times (P<0.05), respectively, those following elective Caesarean section prior to labour at term (CST) and following vaginal delivery after spontaneous labour at term (SLT). The concentration of ICAM-1 protein in the PTD samples was 2.2 and 3.0 times (P<0.05) those in CST and SLT samples, respectively. The differences between the term groups were not significant. The results were substantially the same when a preterm spontaneous labour (PTL) subgroup, exclusive of deliveries complicated by pre-eclampsia or intrauterine growth restriction, was compared with the term groups. Choriodecidual ICAM-1 mRNA expression, but not ICAM-1 protein concentration, significantly correlated to the degree of leukocyte infiltration of the PTD gestational membranes. Neither correlated significantly to clinical indications of intrauterine or neonatal infection. These findings indicate that ICAM-1 is expressed by the human choriodecidua and that this expression is elevated with preterm labour and delivery, particularly with increased leukocyte infiltration.

Expression of interleukin-1 beta mRNA in murine uterine and gestational tissues: Relationship with gestational age

PROBLEM: The pro‐inflammatory cytokine interleukin (IL)‐1β has been shown to stimulate the production of prostaglandins (PG) in gestational tissues. Increased PG synthesis is considered a key step in the initiation of labor both at term and preterm. In this study, IL‐1β mRNA in the uterus and gestational tissues of mice during mid to late pregnancy was studied to characterize its tissue specific as well as gestational age expression.
 METHOD OF STUDY: Gestational tissues (placenta, decidual cap and fetal membranes), uterus, and cervix were collected from pregnant mice during gestation. Total RNA was isolated and probed for the expression of IL‐1β mRNA.
 RESULTS: There was a significantly increased expression of IL‐1β mRNA in the uterus on day 18 of pregnancy. In the decidual caps, there was increased expression of IL‐1β mRNA on day 14 of pregnancy and a decrease in expression with the onset of labor. In the fetal membranes and placenta, IL‐1β mRNA expression significantly increased on days 14 and 18 of pregnancy, respectively, and then remained elevated for the duration of pregnancy. In the cervix, there was a decrease in expression with labor onset.
 CONCLUSIONS: The increases in IL‐1β mRNA in the fetal membranes and placenta late in pregnancy are consistent with a localized, tissue specific inflammatory activation involved in the initiation of parturition.

Expression of prostaglandin H synthase-1 and -2 in murine intrauterine and gestational tissues from mid pregnancy until term.

These studies were undertaken to evaluate the changes in mRNA expression of prostaglandin H synthase (PGHS)-1 and -2 in murine gestational tissues during the latter half of pregnancy. Gestational tissues (decidual caps, membranes surrounding the fetus, and placentae), uterus, and cervix were collected from pregnant mice at days 12, 14, 16, 18, and 19 (am and pm) of gestation (n = 4), and total RNA was isolated and evaluated for PGHS-1 and PGHS-2 expression by northern blot analysis. Expression was normalized to GAPDH. There were no significant increases in PGHS-2 mRNA expression in any of the tissues studied through gestation. In contrast, expression of PGHS-1 mRNA increased significantly at term in the uterus and fetal membranes. In the placenta, mRNA for PGHS-1 was elevated at day 18 and remained elevated over the remainder of the study. These findings suggest that, in the mouse, increased production of PGs by uterine and intrauterine tissues during pregnancy is associated with up-regulation of PGHS-1 and not PGHS-2.

Intercellular adhesion molecule-1 (ICAM-1) in cervicovaginal fluid of women presenting with preterm labor: Predictive value for preterm delivery

PROBLEM: Clinically useful tests for the prediction and diagnosis of preterm labor and delivery remain to be established. We have hypothesized that soluble intercellular adhesion molecule‐1 (sICAM‐1) in the cervicovaginal fluid of women with preterm labor may be a useful diagnostic tool.
 METHOD OF STUDY: The cervicovaginal fluid of 103 women between 240 and 336 weeks gestation with preterm contractions and intact membranes was assayed for sICAM‐1.
 RESULTS: Elevated sICAM‐1 concentrations predicted short intervals to delivery (area under receiver–operator characteristic (ROC) curves, 0.70–0.72 for delivery within 3, 7 and 10 days), with high specificity. Characteristics for delivery within 3 days at a 3 ng/mL threshold for a positive test were sensitivity 33.3%, specificity 98.9%, and positive and negative predictive values of 75.0% and 93.9%, respectively. Predictive ability was independent of and complementary to that of fetal fibronectin (fFN).
 CONCLUSIONS: Measurement of sICAM‐1 in cervicovaginal fluid has potential as a predictor of preterm delivery in women with symptoms of preterm labor, particularly in conjunction with fFN testing.