Comprehensive RNA profiling of villous trophoblast and decidua basalis in pregnancies complicated by preterm birth following intra-amniotic infection

INTRODUCTION

We performed RNA sequencing with the primary goal of discovering key placental villous trophoblast (VT) and decidua basalis (DB) transcripts differentially expressed in intra-amniotic infection (IAI)-induced preterm birth (PTB).

METHODS

RNA was extracted from 15 paired VT and DB specimens delivered of women with: 1) spontaneous PTB in the setting of amniocentesis-proven IAI and histological chorioamnionitis (n = 5); 2) spontaneous idiopathic PTB (iPTB, n = 5); and 3) physiologic term pregnancy (n = 5). RNA sequencing was performed using the Illumina HiSeq 2500 platform, and a spectrum of computational tools was used for gene prioritization and pathway analyses.

RESULTS

In the VT specimens, 128 unique long transcripts and 7 mature microRNAs differed significantly between pregnancies complicated by IAI relative to iPTB (FDR<0.1). The up-regulated transcripts included many characteristic of myeloblast-derived cells, and bioinformatic analyses revealed enrichment for multiple pathways associated with acute inflammation. In an expanded cohort including additional IAI and iPTB specimens, the expression of three proteins (cathepsin S, lysozyme, and hexokinase 3) and two microRNAs (miR-133a and miR-223) was validated using immunohistochemistry and quantitative PCR, respectively. In the DB specimens, only 11 long transcripts and no microRNAs differed significantly between IAI cases and iPTB controls (FDR<0.1). Comparison of the VT and DB specimens in each clinical scenario revealed signatures distinguishing these placental regions.

DISCUSSION

IAI is associated with a transcriptional signature consistent with acute inflammation in the villous trophoblast. The present findings illuminate novel signaling pathways involved in IAI, and suggest putative therapeutic targets and potential biomarkers associated with this condition.

Compartmentalization of acute phase reactants Interleukin-6, C-Reactive Protein and Procalcitonin as biomarkers of intra-amniotic infection and chorioamnionitis

BACKGROUND

The arsenal of maternal and amniotic fluid (AF) immune response to local or systemic infection includes among others the acute-phase reactants IL-6, C-Reactive Protein (CRP) and Procalcitonin (PCT). If these molecules can be used as non-invasive biomarkers of intra-amniotic infection (IAI) in the subclinical phase of the disease remains incompletely known.

METHODS

We used time-matched maternal serum, urine and AF from 100 pregnant women who had an amniocentesis to rule out IAI in the setting of preterm labor, PPROM or systemic inflammatory response (SIR: pyelonephritis, appendicitis, pneumonia) to infection. Cord blood was analyzed in a subgroup of cases. We used sensitive immunoassays to quantify the levels of inflammatory markers in the maternal blood, urine and AF compartment. Microbiological testing and placental pathology was used to establish infection and histological chorioamnionitis.

RESULTS

PCT was not a useful biomarker of IAI in any of the studied compartments. Maternal blood IL-6 and CRP levels were elevated in women with subclinical IAI. Compared to clinically manifest chorioamnionitis group, women with SIR have higher maternal blood IL-6 levels rendering some marginal diagnostic benefit for this condition. Urine was not a useful biological sample for assessment of IAI using either of these three inflammatory biomarkers.

CONCLUSIONS

In women with subclinical IAI, the large overlapping confidence intervals and different cut-offs for the maternal blood levels of IL-6, CRP and PCT likely make interpretation of their absolute values difficult for clinical decision-making.

Assessment of cervicovaginal vascular endothelial growth factor in predicting preterm delivery

AIM

The aim of this study is to estimate the effectiveness of cervicovaginal vascular endothelial growth factor (VEGF) in predicting preterm delivery.

METHODS

Cervicovaginal VEGF was measured in 30 women who presented symptoms or signs of threatened preterm labor and the control group of 30 healthy pregnant patients by enzyme-linked immunoassay.

RESULTS

There was no statistically significant difference in cervicovaginal VEGF values between the threatened preterm labor group and the control group (P > 0.05). Similarly, no statistically significant difference was observed in terms of cervical length and cervicovaginal VEGF values between preterm and term-delivered groups (P > 0.05). Additionally, there was no correlation between cervicovaginal VEGF values and cervical length (P > 0.05) between the threatened preterm labor and the control groups.

CONCLUSION

No correlation was found between cervicovaginal VEGF values and the preterm delivery. However, we believe that the role of VEGF in preterm delivery needs to be investigated further in well-designed studies with larger samples.

The association between maternal biomarkers and pathways to preterm birth in twin pregnancies

OBJECTIVE

We sought to estimate the association between cervical length (CL) and fetal fibronectin (fFN) and each pathway leading to preterm birth in twin pregnancies.

METHODS

Cohort study of 560 patients with twin pregnancies who underwent routine serial CL and fFN screening from 22 to 32 weeks in one maternal fetal medicine practice during 2005-2013. We calculated the association between a short CL (≤20 mm) or positive fFN with overall preterm birth <32 weeks, and then subdivided the analysis into preterm birth <32 weeks from preterm labor, preterm premature rupture of membranes (PPROM) and indicated causes. We excluded cases of monochorionic-monoamniotic placentation, vasa previa, twin-twin transfusion and patients with cerclage.

RESULTS

The overall rate of preterm birth <32 weeks was 6.9% (3.9% from preterm labor, 1.6% from PPROM and 1.4% indicated). A short cervix was associated with preterm birth <32 weeks arising from preterm labor (12.4% versus 2.0%, p < 0.001), but not PPROM (1.9% versus 1.3%, p = 0.651). Positive fFN was associated with preterm birth <32 weeks both from preterm labor (17.0% versus 2.4%, p < 0.001) as well as from PPROM (5.7% versus 1.0%, p = 0.034). Neither was significantly associated with preterm birth <32 weeks from indicated causes.

CONCLUSIONS

The mechanism leading toward preterm influences the accuracy of screening tests chosen to assess risk in twin pregnancies. A shortened cervical length and positive fFN is associated with spontaneous preterm labor and birth <32 weeks. However, PPROM does not appear to be preceded by a short cervix, but is preceded by a positive fFN. Neither test is associated with an indicated preterm birth.

Increased Serpin A5 levels in the cervicovaginal fluid of HIV-1 exposed seronegatives suggest that a subtle balance between serine proteases and their inhibitors may determine susceptibility to HIV-1 infection

HIV-exposed seronegative individuals (HESNs) are persons who remain seronegative despite repeated exposure to HIV, suggesting an in vivo resistance mechanism to HIV. Elucidation of endogenous factors responsible for this phenomenon may aid in the development of new classes of microbicides and therapeutics. We compared cervicovaginal protein abundance profiles between high-risk HESN and two control groups: low-risk HESN and HIV-positives. Four iTRAQ-based quantitative experiments were performed using samples classified based on presence/absence of particular gynaecological conditions. After statistical analysis, two proteins were shown to be differentially abundant between high-risk HESNs and control groups. Serpin A5, a serine proteinase inhibitor and Myeloblastin, a serine protease, were up- and downregulated, respectively. Commercially available ELISA assays were used to confirm differential Serpin A5 levels. These results suggest that HIV resistance in CVF of HESNs is the result of a delicate balance between two complementary mechanisms: downregulation of serine proteinases and upregulation of their inhibitors.

Advances in medical diagnosis of intra-amniotic infection

INTRODUCTION

Intrauterine infection is a global problem and a significant contributor to morbidity and perinatal death. The host response to infection causes an inflammatory state that acts synergistically with microbial insult to induce preterm birth and fetal damage. Prompt and accurate diagnosis of intra-amniotic infection in the asymptomatic stage of the disease is critical for improved maternal and neonatal outcomes.

AREAS COVERED

This article provides an overview of the most recent progress, challenges, and opportunities for discovery and clinical implementation of various maternal serum, cervicovaginal, and amniotic fluid biomarkers in pregnancies complicated by intra-amniotic infection.

EXPERT OPINION

Clinically relevant biomarkers are critical to the accurate diagnostic of intrauterine infection. Front-end implementation of such biomarkers will also translate in lower incidence of early-onset neonatal sepsis (EONS) which is an important determinant of neonatal morbidity and mortality associated with prematurity. However, of the hundreds of differentially expressed proteins, only few may have clinical utility and thus function as biomarkers. The small number of validation studies along with barriers to implementation of technological innovations in the clinical setting are current limitations.

Use of cervicovaginal fluid for the identification of biomarkers for pathologies of the female genital tract

Cervicovaginal fluid has an important function in the homeostasis and immunity of the lower female genital tract. Analysis of the cervicovaginal fluid proteome may therefore yield important information about the pathogenesis of numerous gynecological pathologies. Additionally, cervicovaginal fluid has great potential as a source of biomarkers for these conditions.

This review provides a detailed discussion about the human cervicovaginal proteome and the proteomics studies performed to characterize this biological fluid. Furthermore, infection-correlated pathological conditions of the female genital tract are discussed for which cervicovaginal fluid has been used in order to identify potential biomarkers. Recent years, numerous studies have analyzed cervicovaginal fluid samples utilizing antibody-based technologies, such as ELISA or Western blotting, to identify biomarkers for preterm birth, premature preterm rupture of membranes, bacterial vaginosis and cervical cancer. The present article will discuss the importance of proteomic technologies as alternative techniques to gain additional meaningful information about these conditions. In addition, the review focuses on recent proteomic studies on cervicovaginal fluid samples for the identification of potential biomarkers. We conclude that the use of proteomic technology for analysis of human cervicovaginal fluid samples is promising and may lead to the discovery of new biomarkers which can improve disease prevention and therapy development.