Reproductive Sciences

Background: Understanding spontaneous preterm birth ([PTB] < 37 weeks) is difficult due to heterogeneities associated with multitudes of risk factors and pathophysiological pathways. Several biomarkers are routinely used clinically for predicting preterm labor; however, these factors are either nonspecific or detected too late. Objective: Systematic review of literature on PTB biomarkers in the last 40 years to map out the existing knowledge and gaps in understanding PTB biomarkers. Search strategies: Five electronic databases were searched for human studies on PTB biomarkers published in any language between 1965 and 2008. Selection criteria: The phenotype of interest for final data extraction was exclusively spontaneous PTB with no rupture of membranes. Data extraction included (a) general characteristics of the study (clinical setting, period, and study design), (b) study/participant characteristics (inclusion and exclusion criteria, race/ethnicity, number of participants, gestational age at sampling, (c) characteristics of the biomarker (type, rationale for its selection, type of biological sample, and assay used, and (d) concentration of biomarkers in cases and controls. Data collection and analysis: The search yielded 7255 citations and data were extracted from 217 articles which met our inclusion and exclusion criteria. Main results: A total of 116 different biomarkers were reported and these were assayed 578 times in the 217 included studies. Over two thirds of the 217 studies were performed on North American or European populations. No reliable biomarkers emerged as a risk predictor of PTB. Conclusions: Identifying similar studies on biomarkers for the prediction of PTB was a very challenging task due heterogeneities in study design, sampling issues (types, timing and processing), assay methods, and analyses. Major areas of concern identified in this review include poor phenotype definition, nonideal study designs and poor rationale for biomarker selection and assays and population stratification issues.

Preterm delivery (PTD) has been associated with inflammation along with activation of the coagulation pathway. These studies sought to characterize the expression of several coagulation pathway genes including plasminogen activator inhibitor 1 (PAI-1), tissue factor (TF), protease-activated receptor 1 (Par1), protease-activated receptor 2 (Par2), fibrinogen-like protein 2 (Fgl2), and thrombomodulin (TM) during lipopolysaccharide (LPS)-induced PTD in day 15 pregnant CD-1 mice. Western blot studies confirmed protein expression for PAI-1, Par1, Par2, Fgl2, and TM in the mouse uterus. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) confirmed increased PAI-1 messenger RNA (mRNA) in the uteri, lung, kidney, and liver tissues at 2 to 6 hours after LPS injection. In contrast, TF expression significantly decreased by 12 hours in uterine tissue; whereas, its expression was unchanged in the other maternal tissues. The uterine mRNA for Par1, Par2, Fgl2, and TM remained stable. In summary, these studies have confirmed expression of coagulation pathway genes within the pregnant uterus; some of which are modulated during LPS-induced PTD.

Endometriosis is an estrogen-dependent disease. Steroidogenic factor 1 (SF-1), a transcription factor, is essential for the activation of multiple steroidogenic genes for estrogen biosynthesis in endometriosis-derived stromal cells. Objective: Unravel the mechanism for differential SF-1 expression in endometrial and endometriotic stromal cells. DESIGN: We identified a novel CpG island in the SF-1 gene, which spans from exon II to intron III. We evaluated the methylation status of this CpG island. PATIENTS: Eutopic endometrium from disease-free participants (n = 8) and the walls of cystic endometriosis lesions of the ovaries (n = 8). None of the patients had received any preoperative hormonal therapy. Stromal cells were isolated from these 2 types of tissues. Results: SF-1 messenger RNA (mRNA) levels in endometriotic stromal cells were significantly higher than those in endometrial stromal cells. Bisulfite sequencing showed strikingly increased methylation in endometriotic cells compared with endometrial cells (P < .001). A strong correlation between mRNA levels and percentage methylation of the exon II/intron III are observed. Specifically, the Pearson correlation coefficient was .98 (P < .001) for this association. Conclusions: We demonstrated that methylation of a coding exon/intron sequence in the SF-1 gene positively regulated its expression in endometriosis, whereas its hypomethylation in normal endometrium was associated with drastically lower SF-1 levels.

Human endogenous retroviruses (HERVs) represent up to 8% of the human genome and express several of its genes in the placenta. Studies have demonstrated that HERV envelope proteins syncytins 1 and 2 play a crucial role in trophoblast fusion and placenta development. Here, we compared the levels of placental expression of syncytins with the severity of preeclampsia (PE) symptoms. Confocal microscopy experiments indicated a pronounced deficiency in cellular fusion in trophoblast cells from patients with PE when compared to controls. As determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot analyses, syncytin mRNA and protein levels were decreased in PE placentas versus controls. Interestingly, syncytin 2 levels were more importantly impaired than syncytin 1. Our results further highlighted the existence of a correlation between the extent of the decrease in the expression levels of both fusogenic proteins and the degree of severity of PE symptoms. These HERV proteins could thereby be used as potential markers for the early diagnosis of PE.

We tested the hypothesis that interleukin 1 (IL-1) mediates intra-amniotic lipopolysaccharide (LPS)-induced chorioamnionitis in preterm fetal sheep. Time-mated Merino ewes with singleton fetuses received IL-1α, LPS, or saline (control) by intra-amniotic injection 1 to 2 days before operative delivery at 124 ± 1 days gestational age (N = 5-9/group; term = 150 days). Recombinant human IL-1 receptor antagonist (rhIL-1ra) was given into the amniotic fluid 3 hours before intra-amniotic LPS or saline to block IL-1 signaling. Inflammation in the chorioamnion was determined by histology, cytokine messenger RNA (mRNA), protein expression, and by quantitation of activated inflammatory cells. Intra-amniotic IL-1 and LPS both induced chorioamnionitis. However, IL-1 blockade with IL-1ra did not decrease intra-amniotic LPS-induced increases in pro-inflammatory cytokine mRNAs, numbers of inflammatory cells, myeloperoxidase, or monocyte chemotactic protein-1-expressing cells in the chorioamnion. We conclude that IL-1 and LPS both can cause chorioamnionitis, but IL-1 is not an important mediator of LPS-induced chorioamnionitis in fetal sheep.

This study tested the hypothesis that maternal nicotine ingestion increases matrix metalloproteinase (MMP) expression in fetal hearts, which is mediated by the generation of reactive oxygen species. Timed pregnant guinea pigs were administered either water alone, nicotine (200 μg/mL), N-acetylcysteine (NAC), or nicotine plus NAC in their drinking water for 10 days at 52-day gestation (term = 65 days). Near-term (62 days), anesthetized fetuses were extracted, hearts were excised, and left cardiac ventricles snap frozen for analysis of MMP-2/-9/-13 protein and activity levels. Interstitial collagens were identified by Picrosirius red stain to assess changes in the extracellular matrix. Prenatal nicotine increased active MMP-2 forms and interstitial collagen but had no effect on either pro- or active MMP-9 or MMP-13 forms. In the presence of nicotine, NAC decreased active MMP-2 protein levels and reversed the nicotine-induced increase in collagen staining. We conclude that prenatal nicotine alters MMP-2 expression in fetal hearts that may be mediated by reactive oxygen species generation.

A complex network of epigenetic factors participates in regulating the monoallelic expression of a small subset of genes (˜1%) in the human genome. This phenomenon goes under the definition of genomic imprinting, a parent-of-origin effect that, when altered during early embryogenesis, may influence fetal development into adulthood. Pertubations in genomic imprinting have been associated with placental and fetal growth restrictions. We analyzed the differential DNA methylation of all known imprinted genes on 10 appropriate-for-gestational-age, clinically normal, placentas and 7 severe intrauterine growth-restricted placentas. Samples were pooled according to the diagnosis and analyzed by methylated DNA immunoprecipitation (MeDIP) on a tiling microarray platform. The distribution of the differentially methylated regions (DMRs) identified in growth-restricted placentas showed a slight tendency toward hypermethylation. Imprinted genes not expressed in placenta showed a unique DMR profile with the fewest hyper- and hypomethylated DMRs. Promoter and CpG island DMRs were sporadic and randomly distributed. The vast majority of DMR identified (˜99%) were mapped in introns, showing no common sequence features. Also, by using the more advanced array data mining softwares, no significant patterns emerged. In contrast, differential methylation showed a highly significant correlation with gene length. Overall these data suggest that differential methylation changes in growth-restricted placentas occur throughout the genomic regions, encompassing genes actively expressed in the placenta. These findings warrant caution in interpreting the significance of genes carrying clustered DMRs because the distribution of DMRs in a gene may be attributed as a function of its length rather than as a specific biological role.

Previous studies had shown important functions of galectin 3 (Gal-3) in endometrium during embryo implantation, in regulation of endometrial cell proliferation and adhesion by interacting with integrin β3. In this study, we investigated hormonal regulation of Gal-3 in trophoblasts and its extracellular effects on endometrium. We used BeWo and RL95-2 cells as a model of trophoblastic and endometrial epithelial cells, respectively, to create an in vivo model of embryo implantation. Our results indicated that 17β-estradiol (E2), progesterone (P4), and human chorionic gonadotropin (hCG) induced the expression of Gal-3 and promoted its secretion from BeWo cells. The exogenous Gal-3 inhibited cell proliferation and induced apoptosis of endometrial cells (RL95-2 cells) through activation of integrin β1. We further validated the proapoptotic effect of Gal-3 secreted by trophoblastic cell on endometrial cells by culturing RL95-2 cells with Bewo cells and measuring the apoptotic rate. Our analysis provides new insight into the critical roles of Gal-3 in embryo implantation.

There is increasing evidence linking in utero infection and inflammation to preterm birth. Many commensal urogenital tract microorganisms, including the Mycoplasmas and Ureaplasmas, are commonly detected in association with preterm birth. Using an ovine model of sterile fetal inflammation, we demonstrated previously that the fetal skin generates a robust inflammatory response following in utero exposure to lipopolysaccharides from Escherichia coli. The fetal skin’s response to colonization of the amniotic fluid by viable microorganisms remains unstudied. We hypothesised that in utero infection with Ureaplasma parvum serovar 3 would induce a proinflammatory response in the fetal skin. We found that (1) cultured fetal keratinocytes (the primary cellular constituent of the epidermis) respond to U. parvum exposure in vitro by increasing the expression of the chemotactant monocyte chemoattractant protein 1 (MCP-1) but not interleukin 1β (IL-1β), IL-6, IL-8, or tumor necrosis factor-α (TNF-α); (2) the fetal skin’s response to 7 days of U. parvum exposure is characterized by elevated expression of MCP-1, TNF-α, and IL-10; and (3) the magnitude of inflammatory cytokine/chemokine expression in the fetal skin is dependent on the duration of U parvum exposure. These novel findings provide further support for the role of the fetal skin in the development of fetal inflammation and the preterm birth that may follow.

The pathogenesis of preeclampsia is unclear but is thought to be related to shallow trophoblast invasion. An invasive phenotype is acquired by trophoblasts through the process of epithelial-mesenchymal transition (EMT). We proposed that EMT in trophoblasts is deregulated in preeclampsia. The homeobox gene DLX4 plays an important role in epithelial-mesenchymal interactions during embryonic and placental development. To elucidate the role of DLX4 in trophoblast EMT and preeclampsia, we investigated the expression of DLX4 in preeclampsia-affected placentas and the effect of DLX4 on EMT in trophoblast-derived JEG-3 cells. DLX4 expression was downregulated in preeclampsia-affected placentas and hypoxic JEG-3 cells. Knockdown of DLX4 by RNA interference (RNAi) inhibited the motility and invasion ability of JEG-3 cells, decreased the expression of E-cadherin, and upregulated the expression of the E-cadherin repressor Snail. Our findings suggest that decreased expression of DLX4 leads to the pathogenesis of preeclampsia by inhibiting EMT in trophoblasts and provides new insight into the pathophysiological mechanism of preeclampsia.

Precis: Many genes are differentially expressed in normal compared to anencephalic human fetal adrenals (HFAs), especially the Fras-1-related extracellular matrix protein (FREM2) gene. FREM2 expression appears to be regulated by adrenocorticotrophic hormone (ACTH). Context: The expression profiles of genes responsible for cortical growth and zonation in the HFA gland are poorly characterized. The neural tube disorder anencephaly is associated with fetal adrenal hypoplasia with a large size reduction of the fetal zone of the HFA. Objective: To determine gene expression profile differences in the adrenals of anencephalic compared to normal HFAs to identify genes that may play important roles in adrenal development. Design and Methods: Fresh tissues were obtained at the time of autopsy from normal and anencephalic human fetuses delivered at mid-gestation. The following techniques were used: cell culture, messenger RNA (mRNA) extraction, microarray analysis, complementary DNA (cDNA) synthesis, quantitative real-time reverse transcriptase polymerase chain reaction (QT-PCR). Results: We identified over 40 genes expressed at levels 4-fold or greater in the normal versus anencephalic HFAs and that 28 genes were expressed at increased levels in the anencephalic HFA. The expression of FREM2 at approximately 40-fold greater levels in the normal HFA compared to the HFA of anencephalic fetuses was confirmed by QT-PCR. Expression of FREM2 in the kidney was not significantly different between normal and anencephalic fetuses. In cultured HFA cells, ACTH treatment for 48 hours increased the expression of FREM2 and a gene responsive to ACTH, CYP17, but not tyrosine hydroxylase. Conclusions: Abnormal expression of many genes may be involved in the adrenal hypoplasia seen in anencephaly. FREM2 appears to be regulated by ACTH and is the most differentially expressed gene, which may be important in the development and function of the HFA, particularly the fetal zone of the HFA.

Objective: To develop a model to identify women at very low risk of recurrent early-onset preeclampsia. Methods: We enrolled 407 women who had experienced early-onset preeclampsia in their first pregnancy, resulting in a delivery before 34 weeks' gestation. Preeclampsia was defined as hypertension (systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg) after 20 weeks' gestation with de novo proteinuria (≥300 mg urinary protein excretion/day). Based on the previous published evidence and expert opinion, 5 predictors (gestational age at previous birth, prior small-for-gestational-age newborn, fasting blood glucose, body mass index, and hypertension) were entered in a logistic regression model. Discrimination and calibration were evaluated after adjusting for overfitting by bootstrapping techniques. Results: Early-onset disease recurred in 28 (6.9%) of 407 women. The area under the receiver operating characteristic (ROC) curve of the model was 0.65 (95% CI: 0.56-0.74). Calibration was good, indicated by a nonsignificant Hosmer-Lemeshow test (P = .11). Using a predicted absolute risk threshold of, for example, 4.6% (ie, women identified with an estimated risk either above or below 4.6%), the sensitivity was 100%, with a specificity of 26%. In such a strategy, no women who developed preeclampsia were missed, while 98 of the 407 women would be regarded as low risk of recurrent early-onset preeclampsia, not necessarily requiring intensified antenatal care. Conclusion: Our model may be helpful in the identification of women at very low risk of recurrent early-onset preeclampsia. Before widespread application, our model should be validated in other populations.