15-Hydroxyprostaglandin Dehydrogenase Protein Expression in Human Fetal Membranes With and Without Subclinical Inflammation

Prostaglandins play a central role in the stimulation and maintenance of both term and preterm labor. 15-Hydroxyprostaglandin dehydrogenase (PGDH), localized primarily to chorion trophoblasts, is the key enzyme responsible for the metabolism of prostaglandins. In preterm chorion, levels of PGDH protein and activity were lower when compared to term and were further reduced with the presence of infection, but effects of subclinical inflammation and membrane rupture on PGDH expression are not known. Our objectives were (1) to determine the relative expression of PGDH in amnion and chorion and (2) to determine the effect of preterm premature rupture of membranes (PPROM) and (3) subclinical inflammation on PGDH protein expression in preterm fetal membranes. Fetal membranes were collected from women with idiopathic preterm labor. Patients were divided into preterm birth (1) <32 weeks with PPROM (n = 6), (2) <32 weeks with intact membranes (n = 11), (3) >or=32 and <37 weeks with PPROM (n = 10), and (4) >or=32 and <37 weeks with intact membranes (n = 10). Different antibodies were used to detect protein expression and localization of PGDH in amnion and chorion from these patients using both Western blotting and immunohistochemistry. Antibody T (AbT) localized PGDH to chorion trophoblasts, whereas antibody C (AbC) detected immunoreactive (ir) PGDH predominantly in the amnion mesenchyme. By Western blot, AbT showed a stronger 29-kDa ir-PGDH band whereas with AbC, a stronger 55-kDa ir-PGDH signal was detected. 55-kDa ir-PGDH was significantly higher in PPROM amnion, specifically in the <32 weeks group (P < .05) and with PPROM >24 hours (P < .05). No change was detected in the 29-kDa ir-PGDH in either amnion or chorion with gestational age or the presence and absence of PPROM. In addition, neither form of ir-PGDH was altered significantly with or without subclinical inflammation. ir-PGDH is detectable in both chorion trophoblasts and amnion, especially in the mesenchyme; however, the predominant form of the enzyme differs in the 2 tissues. PPROM and subclinical inflammation do not appear to affect the levels of 29-kDa ir-PGDH protein in the fetal membranes. The differential expression of 55-kDa ir-PGDH in preterm amnion with and without PPROM supports the need for a better understanding of the different forms of PGDH.

Genetic Contributions to the Development of Complications in Preterm Newborns

Aim

We aimed to identify specific polymorphisms of genes encoding for vascular endothelial growth factor A (VEGFA), endothelial nitric oxide synthase (eNOS), renin-angiotensin system (angiotensinogen gene [AGT], angiotensinogen type 1 receptor [AGTR1], angiotensin-converting enzyme [ACE]), and heme oxygenase-1 (HMOX-1) in a cohort of preterm infants and correlate their presence with the development of respiratory distress syndrome (RDS) requiring mechanical ventilation (MV), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH) and retinopathy of prematurity (ROP).

Study Design

We carried out a retrospective study to evaluate the allele frequency and genotype distribution of polymorphisms of VEGFA, eNOS, AGT, AGTR1, ACE, and HMOX-1 in a population of preterm neonates (n=342) with a gestational age ≤28 weeks according to the presence or absence of RDS requiring MV, BPD, IVH, or ROP. Moreover, we evaluated through the haplotype reconstruction analysis whether combinations of the selected polymorphisms are related to the occurrence of RDS, BPD, IVH and ROP.

Results

In our population 157 infants developed RDS requiring MV, 71 BPD, 70 IVH, and 43 ROP. We found that TC+CC rs2070744 eNOS (41.7 vs. 25.4%, p=0.01) and GT+TT rs1799983 eNOS (51.8 vs. 35.2%, p=0.01) polymorphisms are independent risk factors for BPD. Haplotype reconstruction showed that haplotypes in VEGF and eNOS are significantly associated with different effects on RDS, BPD, IVH, and ROP in our population.

Conclusions

We found that TC+CC rs2070744 eNOS and GT+TT rs1799983 eNOS polymorphisms are independent predictors of an increased risk of developing BPD. Haplotypes of VEGFA and eNOS may be independent protective or risk markers for prematurity complications.

Expression of 8-oxoguanine glycosylase in human fetal membranes

PROBLEM

The most common DNA lesion generated by oxidative stress (OS) is 7, 8-dihydro-8-oxoguanine (8-oxoG) whose excision repair is performed by 8-oxoguanine glycosylase (OGG1). We investigated OGG1 expression changes in fetal membranes from spontaneous preterm birth (PTB) and preterm premature rupture of the membranes (pPROM) and its changes in vitro in normal fetal membranes exposed to OS inducer water-soluble cigarette smoke extract (CSE).

METHOD OF STUDY

DNA damage was determined in amnion cells treated with CSE by comet and FLARE assays. OGG1 mRNA expression and localization in fetal membranes from clinical specimens and in normal term membranes exposed to CSE were examined by QRT-PCR and by immunohistochemistry.

RESULTS

DNA strand and base damage was seen in amnion cells exposed to CSE. OGG1 expression was 2.5-fold higher in PTB samples compared with pPROM (P = 0.045). No significant difference was seen between term and pPROM or PTB and term. CSE treatment showed a nonsignificant decrease in OGG1. OGG1 was localized to both amnion and chorion with less intense staining in pPROM and CSE-treated membranes.

CONCLUSION

Increased OS-induced DNA damage predominated by 8-oxoG is likely to persist in fetal cells due to reduced availability of base excision repair enzyme OGG1. This can likely lead to fetal cell senescence associated with some adverse pregnancy outcome.

Expression profiles of fetal membrane nicotinamide adenine dinucleotide phosphate oxidases (NOX) 2 and 3 differentiates spontaneous preterm birth and pPROM pathophysiologies

INTRODUCTION

Nicotinamide adenine dinucleotide phosphate oxidases (NOX 1-5) are enzymes that generate cellular reactive oxygen species (ROS) besides mitochondria and might be important ROS sources associated with pregnancy complications, particularly preterm premature rupture of membranes (pPROM), that has been related to ROS.

OBJECTIVE

To characterize NOX enzymes expression in human fetal membranes.

METHODS

Differential expression and localization of NOX isoforms in human fetal membranes collected from women with uncomplicated pregnancies at term, preterm birth (PTB) or pPROM and in vitro in normal term membranes maintained in an organ explant system stimulated with water-soluble cigarette smoke extract (wsCSE) were documented by real time PCR and immunohistochemistry.

RESULTS

Fetal membranes from term deliveries, PTB and pPROM expressed NOX 2, 3 and 4 mRNAs whereas NOX 1 and 5 were not detected. NOX 2 expression was 2.3-fold higher in PTB than pPROM (p = 0.005) whereas NOX 3 was 2.2-fold higher in pPROM compared to PTB (p = 0.04). NOX 2 and 3 expressions at term mimicked pPROM and PTB, respectively. No difference in NOX 4 expression was observed among the studied groups. NOX 2, 3 and 4 were localized to both amniotic and chorionic cells. Expression of NOX 2, 3 and 4 were not significant in wsCSE-stimulated membranes compared to untreated controls.

DISCUSSION/CONCLUSIONS

NOX enzymes are present in the fetal membranes and are differentially expressed in PTB and pPROM. Absence of any changes in NOXs expression after wsCSE stimulation suggests ROS generation in the membranes does not always correlate with NOX expression.

Interaction between maternal passive smoking during pregnancy and CYP1A1 and GSTs polymorphisms on spontaneous preterm delivery

OBJECTIVE

The present study aimed to examine the association between maternal passive smoking during pregnancy and the risk of spontaneous PTD and to explore the potential interaction of the single or joint gene polymorphism of CYP1A1 and GSTs with maternal passive smoking on the risk of spontaneous PTD.

METHOD

We investigated whether the association between maternal passive smoking and PTD can be modified by 2 metabolic genes, i.e. cytochrome P4501A1 (CYP1A1) and glutathione S-transferases (GSTs), in a case-control study with 198 spontaneous preterm and 524 term deliveries in Shenzhen and Foshan, China. We used logistic regression to test gene-passive smoking interaction, adjusting for maternal socio-demographics and prepregnancy body mass index.

RESULTS

Overall, maternal passive smoking during pregnancy was associated with higher risk of PTD (adjusted odds ratio = 2.20 [95% confidence interval: 1.56-3.12]). This association was modified by CYP1A1 and GSTs together, but not by any single genotype. For cross-categories of CYP1A1 Msp I and GSTs, maternal passive smoking was associated with higher risk of PTD among those women with CYP1A1 "TC/CC"+ GSTs "null", but not among women with other genotypes; and this interaction was significant (OR = 2.66 [95% CI: 1.19-5.97]; P-value: 0.017). For cross-categories of CYP1A1 BsrD I and GSTs, maternal passive smoking was associated with higher risk of PTD only among those women with CYP1A1"AG/GG"+ GSTs "null", but not among women with other genotypes; and this interaction was significant (OR = 3.00 [95% CI: 1.17-7.74]; P-value: 0.023).

CONCLUSIONS

Our findings suggest that the combined genotypes of CYP1A1 and GSTs can help to identify vulnerable pregnant women who are subject to high risk of spontaneous PTD due to passive smoking.

Matrix metalloproteinase-1 and -9 in human placenta during spontaneous vaginal delivery and caesarean sectioning in preterm pregnancy

Preterm birth is a major public health problem in terms of loss of life, long-term and short term disabilities worldwide. The process of parturition (both term and preterm) involves intensive remodelling of the extracellular matrix (ECM) in the placenta and fetal membranes by matrix metalloproteinases (MMPs). Our previous studies show reduced docosahexaenoic acid (DHA) in women delivering preterm. Further omega 3 fatty acids are reported to regulate MMP levels. This study was undertaken to examine the placental levels of MMPs and their association with placental DHA levels in women delivering preterm. The levels of MMP-1 and MMP-9 in 74 women delivering preterm (52 by spontaneous vaginal delivery and 22 by caesarean sectioning) and 75 women delivering at term (59 by spontaneous vaginal delivery and 16 by caesarean sectioning) were determined by enzyme-linked immunosorbent assay (ELISA) and their association with placental DHA was studied. Placental MMP-1 levels were higher (p<0.05) in women delivering preterm (both by spontaneous vaginal delivery and caesarean sectioning) as compared to those delivering at term. In contrast, placental MMP-9 levels in preterm pregnancies was higher (p<0.05) in women with spontaneous vaginal delivery while lower (p<0.05) in women delivering by caesarean sectioning. Low placental DHA was associated with higher placental MMP-9 levels. Our study suggests a differential effect of mode of delivery on the levels of MMPs from placenta. Further this study suggests a negative association of DHA and the levels of MMP-9 in human placenta although the mechanisms need further study.

Alteration of circulating Placental Leucine Aminopeptidase (P-LAP) activity in preeclampsia

OBJECTIVE

Placental Leucine Aminopeptiadse (P-LAP) also known as oxytocinase, is secreted by syncytiotrophoblast and increases gradually during pregnancy until delivery. It is a regulator of uterine contractions, of vascular resistance and of volume of the retroplacental blood pool. Recently, it was shown that it could also regulate metalloproteinase 9 activity and thus, invasiveness of trophoblastic cells. Since development of preeclampsia could be initiated by decreased cytotrophoblastic invasion of spiral arterioles and a reduced uteroplacental perfusion, we speculate that circulating P-LAP activity could be decreased during preeclampsia.

MATERIALS AND METHODS

Case-control study was evaluated in 84 women. P-LAP activity was measured in n=51 healthy pregnant women at term, and compared with n=16 normotensive women delivering preterm and n=17 women diagnosed with pre-eclampsia. P-LAP activity was determined by colorimetry in plasma samples using L-Leucine-p-nitroanilide as substrate.

RESULTS

P-LAP activity was significantly lower in sera of preeclamptic women (0.91+/-0.122 mDO/min) as compared to normotensive controls (1.41+/-0.103 mDO/min; p=0.003) irrespective of time of delivery.

CONCLUSIONS

These findings confirm the probable involvement of P-LAP in trophoblast invasion and development of preeclampsia.