Multidimensional system biology: genetic markers and proteomic biomarkers of adverse pregnancy outcome in preterm birth

Determinants of preterm birth: proposal for a hierarchical theoretical model

Abstract Preterm birth (PB) is a syndrome resulting from a complex relationship between multiple factors which do not have fully understood relationships and causality. This article discusses a hierarchical theoretical model of PB determinants, considering maternal characteristics such as sociodemographic, psychosocial, nutritional, behavioral and biological aspects, traditionally associated with increased risk of PB. The variables were distributed in six dimensions within three hierarchical levels (distal, intermediate and proximal). In this model, the socioeconomic determinants of the mother, family, household and neighborhood play indirect effects on PB through variables at the intermediate level, which in turn affect biological risk factors at the proximal level that have a direct effect on PB. The study presents a hierarchical theoretical model of the factors involved in the PB determination chain and their interrelationships. Understanding these interrelationships is an important step in trying to break the causal chain that makes some women vulnerable to preterm birth.

Determinants of preterm birth: proposal for a hierarchical theoretical model

Preterm birth (PB) is a syndrome resulting from a complex relationship between multiple factors which do not have fully understood relationships and causality. This article discusses a hierarchical theoretical model of PB determinants, considering maternal characteristics such as sociodemographic, psychosocial, nutritional, behavioral and biological aspects, traditionally associated with increased risk of PB. The variables were distributed in six dimensions within three hierarchical levels (distal, intermediate and proximal). In this model, the socioeconomic determinants of the mother, family, household and neighborhood play indirect effects on PB through variables at the intermediate level, which in turn affect biological risk factors at the proximal level that have a direct effect on PB. The study presents a hierarchical theoretical model of the factors involved in the PB determination chain and their interrelationships. Understanding these interrelationships is an important step in trying to break the causal chain that makes some women vulnerable to preterm birth.

Advances in the proteomics of amniotic fluid to detect biomarkers for chromosomal abnormalities and fetomaternal complications during pregnancy

INTRODUCTION

Amniotic fluid (AF) is a dynamic and complex mixture that reflects the physiological condition of developing fetus. In the last decade, proteomic analysis of AF for 16-18 weeks normal pregnancy has been done for the composition and functions of this fluid. Other body fluids such as urine, sweat, tears, etc. are being used for diagnosis of disease, but an insight into protein biomarkers of amniotic fluid can save the fetus and mother from future complications. Areas covered: We have covered the proteomics of amniotic fluid done since 2000, in order to strengthen the establishment of these techniques as a recognized diagnostic tool in the field. After classifying the diseases based on chromosomal aneuploidies, gestational changes, and inflammation caused during pregnancy; we have focused on amniotic fluid to detect various complications during and post pregnancy and its effect on the fetomaternal relationship. Expert comment: The main protein biomarkers responsible for various syndromes, diseases, and complications have been summarized. Major proteins identified for gestational conditions are IGFBP-1, fibrinogen, neutrophil defensins like calgranulins A and C, cathelicidin, APOA1, TRFE, etc. Validation of particular technique and establishing a single standardized biomarker for the diagnosis to avoid any overlapping for different diseases is required. After certain improvements, proteomics approach can be considered for diagnosis of diseases associated with fetal-maternal health.

Genetics, hormonal influences, and preterm birth

Prematurity is a devastating disease with high neonatal morbidity and mortality based on gestational age at birth. Genetic and hormonal signals impact directly on the maternal predisposition to preterm birth or sudden onset of myometrial contractility. Candidate gene or genome-wide approaches are beginning to identify potential variants for women at risk for premature delivery or increased responsiveness to hormonal signals including progesterone. However, a majority of these studies have not yielded definitive results to allow for at this stage for development of personalized therapy.

Imbalance of Amniotic Fluid Activin-A and Follistatin in Intraamniotic Infection, Inflammation, and Preterm Birth

CONTEXT

Microbial invasion of the amniotic fluid (AF) cavity stimulates an inflammatory response that involves activin-A, a pleiotropic mediator member of the TGFβ superfamily involved in connective tissue remodeling. The role of AF follistatin, a natural inhibitor of activin-A, in inflammation-induced preterm birth (PTB), has yet to be determined.

OBJECTIVE

The objective of the study was to investigate the relationships between AF activin-A and follistatin in physiological gestation and in pregnancies complicated by PTB and to evaluate a possible role played by the activin-A-follistatin balance in processes leading to PTB and preterm premature rupture of membranes (PPROM).

STUDY DESIGN

The AF levels of total activin-A and follistatin were immunoassayed in 168 women with a normal pregnancy outcome or PTB with and without intraamniotic inflammation or PPROM. The impact of the activin-A-follistatin imbalance on PTB terminal effector pathways (prostaglandins [prostaglandin E2, prostaglandin F2α] and matrix metalloproteinases [MMP-1, MMP-2, MMP-3, and MMP-9]) was investigated in an amniochorion explant system challenged with lipopolysaccharide (LPS) to mimic inflammation.

RESULTS

AF follistatin and the activin-A to follistatin ratio varied with gestational age, both decreasing toward term (P < .001). Activin-A was up-regulated in AF infection (>2-fold elevation in activin-A to follistatin ratio) correlating directly with severity of inflammation (both P < .001). Activin-A increased prostaglandins, MMP-1, and MMP-9 released by amniochorion (P < .05) to LPS-equivalent levels. Follistatin effectively blunted the prostaglandin response to activin-A and LPS and that of MMPs after activin-A but not after LPS challenge.

CONCLUSION

Activin-A and follistatin are part of the complex inflammatory response of the gestational sac to infection and modulate effector pathways leading to PTB. The activin-A to follistatin ratio may play a role in determining the clinical phenotype of PTB as preterm labor or PPROM.

Inflammatory gene networks in term human decidual cells define a potential signature for cytokine-mediated parturition

BACKGROUND

Inflammation is a proximate mediator of preterm birth and fetal injury. During inflammation several microRNAs (22 nucleotide noncoding ribonucleic acid (RNA) molecules) are up-regulated in response to cytokines such as interleukin-1β. MicroRNAs, in most cases, fine-tune gene expression, including both up-regulation and down-regulation of their target genes. However, the role of pro- and antiinflammatory microRNAs in this process is poorly understood.

OBJECTIVE

The principal goal of the work was to examine the inflammatory genomic profile of human decidual cells challenged with a proinflammatory cytokine known to be present in the setting of preterm parturition. We determined the coding (messenger RNA) and noncoding (microRNA) sequences to construct a network of interacting genes during inflammation using an in vitro model of decidual stromal cells.

STUDY DESIGN

The effects of interleukin-1β exposure on mature microRNA expression were tested in human decidual cell cultures using the multiplexed NanoString platform, whereas the global inflammatory transcriptional response was measured using oligonucleotide microarrays. Differential expression of select transcripts was confirmed by quantitative real time-polymerase chain reaction. Bioinformatics tools were used to infer transcription factor activation and regulatory interactions.

RESULTS

Interleukin-1β elicited up- and down-regulation of 350 and 78 nonredundant transcripts (false discovery rate < 0.1), respectively, including induction of numerous cytokines, chemokines, and other inflammatory mediators. Whereas this transcriptional response included marked changes in several microRNA gene loci, the pool of fully processed, mature microRNA was comparatively stable following a cytokine challenge. Of a total of 6 mature microRNAs identified as being differentially expressed by NanoString profiling, 2 (miR-146a and miR-155) were validated by quantitative real time-polymerase chain reaction. Using complementary bioinformatics approaches, activation of several inflammatory transcription factors could be inferred downstream of interleukin-1β based on the overall transcriptional response. Further analysis revealed that miR-146a and miR-155 both target genes involved in inflammatory signaling, including Toll-like receptor and mitogen-activated protein kinase pathways.

CONCLUSION

Stimulation of decidual cells with interleukin-1β alters the expression of microRNAs that function to temper proinflammatory signaling. In this setting, some microRNAs may be involved in tissue-level inflammation during the bulk of gestation and assist in pregnancy maintenance.

Correlation of cervical length, fetal fibronectin, phIGFBP-1, and cytokines in spontaneous preterm birth up to 14 days from sampling

OBJECTIVE

The aim of this study was to determine the relationship between sonographic cervical length, fetal fibronectin (fFN), phIGFBP-1 (actim partus test), cytokines (IL-6, IL-2R, and TNF-α), and spontaneous preterm birth (SPTB) up to 14 days from sampling.

METHODS

Fifty-eight patients were recruited in a period of 6 months from September 2013 until March 2014 with symptoms or complaints suggestive of preterm labor. Consenting women were treated according to usual hospital protocol, with addition of vaginal swabs taken for fetal fibronectin, phIGFBP-1 (actim partus test) and cervical IL6, IL2R, and TNF-α. The outcome variable was occurrence of preterm delivery within 14 days from the day of hospital admission.

RESULTS

Thirty-six patients (62.07%) were delivered within 14 days from admission. Our results indicated that the cervical length significantly inversely correlates with the concentration of IL-6 in the CVF (Spearman's coefficient R=-0.382, P<0.05). Cervical length also correlated with a positive phIGFBP-1 test, i.e., patients with a positive test had an average cervical length of 18.5±4.63 mm, which is significantly lower than patients with a negative test -23.43±7.39 mm (P=0.003).

CONCLUSIONS

The studied biochemical markers were only moderately successful in the prediction of preterm delivery.

Passive smoking and preterm birth in urban China

Studies investigating the relationship between maternal passive smoking and the risk of preterm birth have reached inconsistent conclusions. A birth cohort study that included 10,095 nonsmoking women who delivered a singleton live birth was carried out in Lanzhou, China, between 2010 and 2012. Exposure to passive smoking during pregnancy was associated with an increased risk of very preterm birth (<32 completed weeks of gestation; odds ratio = 1.98, 95% confidence interval: 1.41, 2.76) but not moderate preterm birth (32-36 completed weeks of gestation; odds ratio = 0.98, 95% confidence interval: 0.81, 1.19). Risk of very preterm birth increased with the duration of exposure (P for trend = 0.0014). There was no variability in exposures by trimester. The associations were consistent for both medically indicated and spontaneous preterm births. Overall, our findings support a positive association between passive smoking and the risk of very preterm birth.

Genetics and preterm birth

Although the etiology of preterm birth is incompletely understood, phenotype classifications combined with recent technologies such as genome-wide association studies and next-generation sequencing could lead to discovering genotypes associated with preterm birth. Identifying genetic contributions will allow for genetic screening tests to predict or detect pregnancies with potential for preterm birth. In this article we discuss current knowledge regarding phenotype classifications, genotypes, and their associations with preterm birth.

Amniotic fluid: the use of high-dimensional biology to understand fetal well-being

Our aim was to review the use of high-dimensional biology techniques, specifically transcriptomics, proteomics, and metabolomics, in amniotic fluid to elucidate the mechanisms behind preterm birth or assessment of fetal development. We performed a comprehensive MEDLINE literature search on the use of transcriptomic, proteomic, and metabolomic technologies for amniotic fluid analysis. All abstracts were reviewed for pertinence to preterm birth or fetal maturation in human subjects. Nineteen articles qualified for inclusion. Most articles described the discovery of biomarker candidates, but few larger, multicenter replication or validation studies have been done. We conclude that the use of high-dimensional systems biology techniques to analyze amniotic fluid has significant potential to elucidate the mechanisms of preterm birth and fetal maturation. However, further multicenter collaborative efforts are needed to replicate and validate candidate biomarkers before they can become useful tools for clinical practice. Ideally, amniotic fluid biomarkers should be translated to a noninvasive test performed in maternal serum or urine.

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.

Relaxin augments the inflammatory IL6 response in the choriodecidua

Intrauterine infection frequently leads to preterm birth (PTB), with the pathophysiology involving activation of the innate immune system and its associated inflammatory response. The choriodecidua produces relaxin (RLN) and elevated levels are associated with preterm premature rupture of the fetal membranes. However, it is not increased in bacterially-mediated PTB, but may act as an endogenous sterile inflammatory mediator. Elevated systemic RLN levels from the corpus luteum are also associated with PTB, but the mechanism is unknown. In clinical obstetrics, intrauterine inflammation or infection can coexist with elevated RLN. Therefore, in this study, we further characterized the effects of RLN alone or together with an inflammatory mediator on the production of IL1B, CSF2 (GM-CSF), IL6, IL8 and TNF, from chorionic cytotrophoblasts (CyT), decidual fibroblasts (DF) and stromal cells (DSC), using interleukin-1 beta (IL1B) to mimic sterile inflammation or lipopolysaccharide (LPS) for bacterial infection. Endogenous differences between the cells showed that the CyT expressed more RLN, its receptor RXFP1 and the RXFP1 splice variant D. CyT also showed the most robust cAMP response to RLN with increased IL6 secreted after 4 h, preceded by increased transcription at 1 h, likely due to activation of RXFP1 and cAMP. When all cell types were treated with IL1B and RLN, RLN augmented secretion of IL6 and IL8 from CyT and DF, but not DSC. Similarly, RLN augmented LPS-induced IL6 secretion from CyT and DF. Despite the structural similarity between TLR4 and RXFP1, blocking TLR4 in CyT had no effect on RLN-induced IL6 secretion, suggesting specific activation of RXFP1. Thus, we have shown that in the presence of a low level of intrauterine inflammation/infection, elevated RLN could act on the CyT and DF to augment the inflammatory response, contributing to the pathophysiology of PTB.

SUMMARY

RLN augments the inflammatory responses induced by IL1B or LPS in chorionic cytotrophoblasts and decidual fibroblasts.

The relationship between follicle development and progesterone receptor membrane component-1 expression in women undergoing in vitro fertilization

OBJECTIVE

To determine the relationship between progesterone receptor membrane component-1 (PGRMC1) expression and the outcome of IVF treatment.

DESIGN

A prospective study in which PGRMC1 messenger RNA (mRNA) levels, methylation status of the Pgrmc1 promoter, and the presence of point mutations within Pgrmc1 were obtained from granulosa (GC)/luteal cells of women undergoing controlled ovarian hyperstimulation (COH).

SETTING

Fertility center/basic science laboratory.

PATIENT(S)

Eighty-five patients undergoing IVF treatment and 10 women who were undergoing COH for the purpose of oocyte donation were included in this study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The PGRMC1 measurements were correlated with clinical outcomes, such as number of follicles, number of retrieved oocytes, and ongoing pregnancy rates (PR).

RESULT(S)

The PGRMC1 mRNA levels within GC/luteal cells of 18% of IVF patients were >2.25-fold higher than those of oocyte donors. Individuals with elevated PGRMC1 mRNA levels had 30% fewer large follicles and fewer oocytes retrieved. The elevated PGRMC1 mRNA levels were associated with an increase in the methylation of Pgrmc1 promoter.

CONCLUSION(S)

In patients with elevated PGRMC1 mRNA levels, gonadotropin-induced follicle development is attenuated, although sufficient numbers of follicles develop to allow for ET and subsequent pregnancy.

Application of proteomics for the identification of biomarkers in amniotic fluid: are we ready to provide a reliable prediction?

Proteomics-based identification of biomarkers for fetal abnormalities and pregnancy complications in amniotic fluid (AF) has made significant progress in the past 5 years. This is attributed mainly to advances in mass spectrometry-based proteomic technologies that enable new strategies for discovering biomarkers from complex biological fluids in a high-throughput and sensitive manner. These markers, although they still need to be verified, are diagnostic and may in the future provide targets for therapeutic intervention. In the current review we focus on the emergence of proteomics as a major platform technology in studying AF and developing biomarkers for fetal aneuploidies and pregnancy-related disorders.

Preventing preterm birth and neonatal mortality: exploring the epidemiology, causes, and interventions

Globally, each year, an estimated 13 million infants are born before 37 completed weeks of gestation. Complications from these preterm births are the leading cause of neonatal mortality. Preterm birth is directly responsible for an estimated one million neonatal deaths annually and is also an important contributor to child and adult morbidities. Low- and middle-income countries are disproportionately affected by preterm birth and carry a greater burden of disease attributed to preterm birth. Causes of preterm birth are multifactorial, vary by gestational age, and likely vary by geographic and ethnic contexts. Although many interventions have been evaluated, few have moderate-to high-quality evidence for decreasing preterm birth: smoking cessation and progesterone treatment in women with a high risk of preterm birth in low- and middle-income countries and cervical cerclage for those in high-income countries. Antepartum and postnatal interventions (eg, antepartum maternal steroid administration, or kangaroo mother care) to improve preterm neonatal survival after birth have been demonstrated to be effective but have not been widely implemented. Further research efforts are urgently needed to better understand context-specific pathways leading to preterm birth; to develop appropriate, efficacious prevention strategies and interventions to improve survival of neonates born prematurely; and to scale-up known efficacious interventions to improve the health of the preterm neonate.

Novel insights into molecular mechanisms of abruption-induced preterm birth

Preterm birth (PTB) complicates more than 12% of all deliveries. Despite significant research, the aetiology of most cases of PTB remains elusive. Two major antecedents of PTB, intra-amniotic infection and decidual haemorrhage (abruption), can exhibit dissimilar demographic and genetic predispositions, despite sharing common molecular and cellular pathways. The use of high-throughput, high-dimensional technologies reveals substantial crosstalk between the coagulation and inflammation pathways. Tissue factor, thrombin and cytokines are key mediators of this crosstalk. Abruptions are associated with excess thrombin generated from decidual-cell-expressed tissue factor. Although thrombin is a primary mediator of the coagulation cascade, it can also promote inflammation-associated PTB by enhancing expression of matrix metalloproteinase and neutrophil-chemoattracting and -activating chemokines. Here, we provide novel insights into the molecular mechanisms and pathways leading to PTB in the setting of placental abruption.

Progress toward improved understanding of infection-related preterm birth

Current strategies to prevent infection-related preterm birth and its associated neonatal morbidities have had limited success. Improved understanding of the pathogen-host interactions underlying altered colonization of the lower genital tract is necessary before significant progress can be made. The application of novel diagnostic techniques such as broad range PCR and proteomic analysis contribute to our knowledge of the diversity and abundance of microbial species invading the amniotic cavity as well as the resultant inflammatory response. Preterm infants delivered following intrauterine infection may respond differently to subsequent infectious challenges in the neonatal intensive care unit.

Interpretation of amniotic fluid white blood cell count in "bloody tap" amniocenteses in women with symptoms of preterm labor

OBJECTIVE

To estimate whether blood-contaminated amniotic fluid affects the performance of white blood cell (WBC) count in diagnosing intraamniotic inflammation and infection.

METHODS

Three hundred fifty-seven consecutive women pregnant with singletons undergoing amniocentesis to rule out infection were enrolled prospectively. A "bloody tap" was defined as a red blood cell (RBC) count of 1,000 cells/mm or more. Proteomics analysis of amniotic fluid was used in this study as the standard for diagnosing inflammation. Infection was confirmed by positive amniotic fluid culture. An amniotic fluid WBC count correction formula was computed using maternal WBC count, hematocrit, and mean corpuscular volume.

RESULTS

The prevalence of a bloody tap amniocentesis was 22% (77 of 357). In the absence of inflammation, the amniotic fluid WBC count was significantly higher in bloody tap (median [interquartile range] 18 [9-58] cells/mm) compared with non-bloody tap specimens (4 [1-10] cells/mm; P<.001). The correction formula reversed this difference to a nonsignificant level (bloody tap 0 [0-17] compared with non-bloody tap 3 [1-10] cells/mm; P=.273). In the setting of inflammation, the observed WBC count of bloody tap samples (778 [197-2,062 cells/mm]) was significantly elevated compared with that of the non-bloody tap specimens (616 [105-1,730] cells/mm; P=.023). Correction of the WBC count in bloody tap amniocenteses improved the test accuracy and positive likelihood ratios for inflammation and infection. A correction algorithm was not useful in amniotic fluid specimens with less than 1,000/RBCs/mm or WBC counts more than 1,100 cells/mm. Given the nonlinear relationship between amniotic fluid WBC and RBC, for a rapid correction of WBC count, the number of neutrophils that need to be subtracted from the observed WBC count is variable.

CONCLUSION

In the setting of an amniotic fluid sample contaminated with 1,000 RBCs/mm or more, WBC count is a less accurate indicator of inflammation and infection. In such samples, correction of WBC count enhances diagnostic performance for inflammation and infection.

LEVEL OF EVIDENCE

II.

The role of proteomics in the diagnosis of chorioamnionitis and early-onset neonatal sepsis

Intrauterine infection is a unique pathologic process that raises the risk for early-onset neonatal sepsis (EONS). By acting synergistically with prematurity, EONS increases the risk for adverse neonatal outcomes, including intraventricular hemorrhage and cerebral palsy. Although several pathways for the pathogenesis of fetal damage have been proposed, the basic molecular mechanisms that modulate these events remain incompletely understood. Discovery of clinically and biologically relevant biomarkers able to reveal key pathogenic pathways and predict pregnancies at risk for antenatal fetal damage is a priority. Proteomics provides a unique opportunity to fill this gap.

Global report on preterm birth and stillbirth (2 of 7): discovery science

Background

Normal and abnormal processes of pregnancy and childbirth are poorly understood. This second article in a global report explains what is known about the etiologies of preterm births and stillbirths and identifies critical gaps in knowledge. Two important concepts emerge: the continuum of pregnancy, beginning at implantation and ending with uterine involution following birth; and the multifactorial etiologies of preterm birth and stillbirth. Improved tools and data will enable discovery scientists to identify causal pathways and cost-effective interventions.

Pregnancy and parturition continuum

The biological process of pregnancy and childbirth begins with implantation and, after birth, ends with the return of the uterus to its previous state. The majority of pregnancy is characterized by rapid uterine and fetal growth without contractions. Yet most research has addressed only uterine stimulation (labor) that accounts for <0.5% of pregnancy.

Etiologies

The etiologies of preterm birth and stillbirth differ by gestational age, genetics, and environmental factors. Approximately 30% of all preterm births are indicated for either maternal or fetal complications, such as maternal illness or fetal growth restriction. Commonly recognized pathways leading to preterm birth occur most often during the gestational ages indicated: (1) inflammation caused by infection (22-32 weeks); (2) decidual hemorrhage caused by uteroplacental thrombosis (early or late preterm birth); (3) stress (32-36 weeks); and (4) uterine overdistention, often caused by multiple fetuses (32-36 weeks). Other contributors include cervical insufficiency, smoking, and systemic infections. Many stillbirths have similar causes and mechanisms. About two-thirds of late fetal deaths occur during the antepartum period; the other third occur during childbirth. Intrapartum asphyxia is a leading cause of stillbirths in low- and middle-income countries.

Recommendations

Utilizing new systems biology tools, opportunities now exist for researchers to investigate various pathways important to normal and abnormal pregnancies. Improved access to quality data and biological specimens are critical to advancing discovery science. Phenotypes, standardized definitions, and uniform criteria for assessing preterm birth and stillbirth outcomes are other immediate research needs.

Conclusion

Preterm birth and stillbirth have multifactorial etiologies. More resources must be directed toward accelerating our understanding of these complex processes, and identifying upstream and cost-effective solutions that will improve these pregnancy outcomes.

Using proteomics in perinatal and neonatal sepsis: hopes and challenges for the future

PURPOSE OF REVIEW

Particularities of the fetal immune response to infection cause a heightened inflammatory state that acts synergistically with microbial insult to induce damage. Proteomics offers the opportunity for detecting fetuses at risk of sepsis and neurological injury.

RECENT FINDINGS

Molecular tools (16S-rRNA) demonstrate that the diversity of microbial agents of intra-amniotic infection exceeds what is suspected clinically or is documented by cultures. The resulting inflammatory process has the potential to damage the fetus in utero. Stepwise algorithms (mass restricted score) have been developed to extract proteomic profiles characteristic of amniotic fluid inflammation. The mass restricted score includes four proteomic biomarkers: defensin-2, defensin-1, S100A12, and S100A8 proteins. Other amniotic fluid biomarkers relevant for preterm birth are S100A9 and insulin-like growth factor-binding protein 1. S100A12 - ligand for the receptor of advanced glycation end products - has the strongest association with histological chorioamnionitis and funisitis. Presence of S100A12 and S100A8 in amniotic fluid is predictive of early-onset neonatal sepsis and poor neurodevelopmental outcome.

SUMMARY

Presence of amniotic fluid proteomic biomarkers of inflammation is associated with increased inflammatory status of the fetus at birth. Future challenges are to find biomarkers that provide insight into molecular mechanisms of chronic fetal and neonatal cellular damage and to identify candidates for early neuroprotection strategies.

Medications in pregnancy and lactation: part 1. Teratology

One of the least-developed areas of clinical pharmacology and drug research is the use of medication during pregnancy and lactation. This article is the first in a two-part series designed to familiarize physicians with many aspects of the drugs they commonly prescribe for pregnant and breast-feeding women. Almost every pregnant woman is exposed to some type of medication during pregnancy. Although the majority of pregnant and breast-feeding women consume clinically indicated or over-the-counter drug preparation regularly, only few medications have specifically been tested for safety and efficacy during pregnancy. There is scant information on the effect of common pregnancy complications on drug clearance and efficacy. Often, the safety of a drug for mothers, their fetuses, and nursing infants cannot be determined until it has been widely used. Absent this crucial information, many women are either refused medically important agents or experience potentially harmful delays in receiving drug treatment. Conversely, many drugs deemed "safe" are prescribed despite evidence of possible teratogenicity. Novel research and diagnostic applications evolving from the opportunities presented by the advances in genomics and proteomics are now beginning to affect clinical diagnosis, vaccine development, drug discovery, and unique therapies in a modern diagnostic-therapeutic framework-part of the new scientific field of theranostics. This review critically explores a number of recently raised issues in regard to the use of several classes of medications during gestation and seeks to provide a general and concise resource on drugs commonly used during pregnancy and lactation. It also seeks to make clinicians more aware of the controversies surrounding some drugs in an effort to encourage safer prescribing practices through consultation with a maternal-fetal medicine specialist and through references and Web sites that list up-to-date information.

Fetal renal artery impedance as assessed by Doppler ultrasound in pregnancies complicated by intraamniotic inflammation and preterm birth

OBJECTIVE

The objective of the study was to evaluate the fetal renal artery impedance in the context of inflammation-associated preterm birth.

STUDY DESIGN

We conducted a prospective Doppler assessment of the fetal renal artery impedance in 70 singleton fetuses. The study group consisted of 56 premature fetuses (median, 28.1 [interquartile range, 25.3-30.6] weeks at enrollment). Gestational age (GA) reference ranges were generated based on fetuses with uncomplicated pregnancies (n = 14). Doppler studies included renal artery pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio, and presence or absence of end-diastolic blood flow. Proteomic profiling (surface-enhanced laser desorption ionization time-of-flight) was used for assessment of intraamniotic inflammation and biomarker peak corresponding to beta2-microglubin. Data were interpreted in relationship to amniotic fluid index (AFI), cord blood interleukin (IL)-6 and erythropoietin (EPO) levels. The cardiovascular and metabolic profiles of the neonates were investigated in the first 24 hours of life.

RESULTS

Fetuses delivered by mothers with intraamniotic inflammation had higher cord blood IL-6 but not EPO levels. Fetal inflammation did not affect either renal artery PI, RI, S/D ratio, or end-diastolic blood flow. Neonates delivered in the context of intraamniotic inflammation had higher serum blood urea nitrogen levels, which correlated significantly with AF IL-6 levels. The renal artery RI and SD ratio were inversely correlated with the AFI independent of GA, cord blood IL-6, and status of the membranes.

CONCLUSION

The fetus is capable of sustaining normal renal artery impedance despite inflammation. Resistance in the renal vascular bed affects urine output independent of inflammation.

Fetal inflammatory response in women with proteomic biomarkers characteristic of intra-amniotic inflammation and preterm birth

OBJECTIVE

To determine the relationship between presence of amniotic fluid (AF) biomarkers characteristic of inflammation (defensins 2 and 1 and calgranulins C and A) and fetal inflammatory status at birth.

DESIGN

Prospective observational cohort.

SETTING

Tertiary referral University hospital.

POPULATION

One hundred and thirty-two consecutive mothers (gestational age, median [interquartile range]: 29.6 [24.1-33.1] weeks) who had a clinically indicated amniocentesis to rule out infection and their newborns.

METHODS

Intra-amniotic inflammation was diagnosed by mass spectrometry surface-enhanced-laser-desorption-ionization time of flight (SELDI-TOF). The AF proteomic fingerprint (mass-restricted [MR] score) ranges from 0-4 (none to all biomarkers present). The intensity of intra-amniotic inflammation was graded based on the number of proteomic biomarkers: MR score 0: 'no' inflammation, MR score 1-2: 'minimal' inflammation and MR score 3-4: 'severe' inflammation. At birth, cord blood was obtained for all women. Severity of histological chorioamnionitis and early-onset neonatal sepsis (EONS) was based on established histological and haematological criteria. Interleukin-6 (IL-6) levels were measured by sensitive immunoassays. The cord blood-to-AF IL-6 ratio was used as an indicator of the differential inflammatory response in the fetal versus the AF compartment.

MAIN OUTCOME MEASURES

To relate proteomic biomarkers of intra-amniotic infection to cord blood IL-6 and to use the latter as the primary marker of fetal inflammatory response.

RESULTS

Women with intra-amniotic inflammation delivered at an earlier gestational age (analysis of variance, P<0.001) and had higher AF IL-6 levels (P<0.001). At birth, neonates of women with severe intra-amniotic inflammation had higher cord blood IL-6 levels (P=0.002) and a higher frequency of EONS (P=0.002). EONS was characterised by significantly elevated cord blood IL-6 levels (P<0.001). Of the 39 neonates delivered by mothers with minimal intra-amniotic inflammation, 15 (39%) neonates had umbilical cord blood IL-6 levels above the mean for the group and 2 neonates had confirmed sepsis. The severity of the neutrophilic infiltrate in the chorionic plate (P<0.001), choriodecidua (P=0.002), umbilical cord (P<0.001) but not in the amnion (P>0.05) was an independent predictor of the cord blood-to-AF IL-6 ratio. Relationships were maintained following correction for gestational age, birthweight, amniocentesis-to-delivery interval, caesarean delivery, status of the membranes, race, MR score and antibiotics and steroid exposure.

CONCLUSIONS

We provide evidence that presence of proteomic biomarkers characteristic of inflammation in the AF is associated with an increased inflammatory status of the fetus at birth. Neonates mount an increased inflammatory status and have positive blood cultures even in the context of minimal intra-amniotic inflammation.

Uncultivated bacteria as etiologic agents of intra-amniotic inflammation leading to preterm birth

Intra-amniotic infection and inflammation are major causes of preterm birth (PTB). However, intra-amniotic inflammation is often detected in the absence of infection. This may partly be due to the culturing methods employed in hospital laboratories, which are unable to detect the uncultivated species. In this study, intra-amniotic microbial infections associated with PTB were examined by both culture and 16S rRNA-based culture-independent methods and were corroborated by the presence of intra-amniotic inflammation. Amniotic fluid (AF) specimens from 46 pregnancies complicated by PTB and 16 asymptomatic women were analyzed. No bacterial DNA was amplified in AF collected from the asymptomatic women. Among the 46 samples associated with PTB, bacterial DNA was amplified from all (16/16) of the culture-positive samples and 17% (5/30) of the culture-negative samples. In the culture-positive group, additional species were detected in more than half (9/16) of the cases by PCR and clone analysis. Altogether, approximately two- thirds of the species detected by the culture-independent methods were not isolated by culture. They included both uncultivated and difficult-to-cultivate species, such as Fusobacterium nucleatum, Leptotrichia (Sneathia) spp., a Bergeyella sp., a Peptostreptococcus sp., Bacteroides spp., and a species of the order Clostridiales. To examine intra-amniotic inflammation, an AF proteomic fingerprint (mass-restricted score) was determined by surface-enhanced laser desorption ionization-time-of-flight mass spectrometry. Inflammation was detected in all five samples which were culture negative but PCR positive. Women who were PCR positive more often had elevated interleukin-6 levels in their AF, histological chorioamnionitis, and funisitis and delivered neonates with early-onset neonatal sepsis. Previously unrecognized, uncultivated, or difficult-to-cultivate species may play a key role in the initiation of PTB.