Maternal tobacco use modestly alters correlated epigenome-wide placental DNA methylation and gene expression.

Several studies linking alterations in differential placental methylation with pregnancy disorders have implicated (de)regulation of the placental epigenome with fetal programming and later-in-life disease. We have previously demonstrated that maternal tobacco use is associated with alterations in promoter methylation of placental CYP1A1 and that these changes are correlated with CYP1A1 gene expression and fetal growth restriction. In this study we sought to expand our analysis of promoter methylation by correlating it to gene expression on a genome-wide scale. Employing side-by-side IlluminaHG-12 gene transcription with Infinium27K methylation arrays, we interrogated correlative changes in placental gene expression and DNA methylation associated with maternal tobacco smoke exposure at an epigenome-wide level and in consideration of signature gene pathways. We observed that the expression of 623 genes and the methylation of 1024 CpG dinucleotides are significantly altered among smokers, with only 38 CpGs showing significant differential methylation (differing by a methylation level of ≥10%). We identified a significant Pearson correlation (≥0.7 or ≤-0.7) between placental transcriptional regulation and differential CpG methylation in only 25 genes among non-smokers but in 438 genes among smokers (18-fold increase, p < 0.0001), with a dominant effect among oxidative stress pathways. Differential methylation at as few as 6 sites was attributed to maternal smoking-mediated birth weight reduction in linear regression models with Bonferroni correction (p < 1.8 × 10(-6)). These studies suggest that a common perinatal exposure (such as maternal smoking) deregulates placental methylation in a CpG site-specific manner that correlates with meaningful alterations in gene expression along signature pathways.

Maternal tobacco use is associated with increased markers of oxidative stress in the placenta.

OBJECTIVE: We sought to extend our prior observations and histopathologically characterize key metabolic enzymes (CYP1A1) with markers of oxidative damage in the placental sections from smokers. STUDY DESIGN: Placental specimens were collected from term singleton deliveries from smokers (n = 10) and nonsmokers (n = 10) and subjected to a detailed histopathological examination. To quantify the extent of oxidative damage, masked score-graded (0-6) histopathology against 4-hydroxy-2-nonenal (4-HNE) and 8-hydroxydeoxyguanisine (8-OHdG) was performed. Minimal significance (P < .05) was determined with a Fisher's exact and a 2-tailed Student t test as appropriate. RESULTS: We observed a significant increase in the presence of syncytial knots in placentas from smokers (70% vs 10%, P = .02). These gross observations were accompanied by a significant aberrant placental aromatic hydrocarbon metabolism (increased CYP1A1, 4.4 vs 2.1, P = .002) in addition to evidence of oxidative damage (4-HNE 3.4 vs 1.1, P = .00005; 8-OHdG 4.9 vs 3.1, P = .0038). CONCLUSION: We observed a strong association between maternal tobacco use and aberrant placental metabolism, syncytial knot formation, and multiple markers of oxidative damage.

Genome-wide array-based copy number profiling in human placentas from unexplained stillbirths.

OBJECTIVE: Accumulating evidence suggests that genomic structural variations, particularly copy number variations (CNV), are a common occurrence in humans that may bear phenotypic consequences for living individuals possessing the variant. While precise estimates vary, large-scale karyotypic abnormalities are present in 6-12% of stillbirths (SB). However, due to inherent limitations of conventional cytogenetics, the contribution of genomic aberrations to stillbirth is likely underrepresented. High-resolution copy number variant analysis by genomic array-based profiling may overcome such limitations. METHODS: Prospectively acquired SB cases > 22 weeks underwent classification of 'unexplained' stillbirth by Wigglesworth and Aberdeen criteria after extensive testing and rigorous multidisciplinary audit. Genome-wide analysis was conducted using high-resolution Illumina single nucleotide polymorphism (SNP) arrays (Human CNV370-Duo) on placental and fetal samples. Potential alternate detection methods were completed by one or more of three independent means (quantitative PCR, Illumina1M, or Agilent105K comparative genomic hybridization arrays). RESULTS: In our cohort of 54 stillbirths, 29 met strict unexplained criteria. Among these, we identified 24 putative novel CNVs. Subsequent interrogation detected 18 of 24 CNVs (75%) in placental samples, 8 of which were also confirmed in available fetal samples; none were present in maternal blood. CONCLUSION: We describe the potential of whole-genome placental profiling to identify small genomic imbalances, which might contribute to a small proportion of well-characterized, unexplained stillbirths.

Obstructive sleep apnea screening in pregnancy, perinatal outcomes, and impact of maternal obesity.

We employed accepted, validated symptom-based screening measures to discern attributable risk of obstructive sleep apnea (OSA) to adverse pregnancy outcomes, taking into account potential maternal confounders. Commonly employed OSA screening measures (Berlin and Epworth scales) were performed in the second and third trimesters; maternal and neonatal outcome data were thereafter obtained. The relationship between OSA and outcomes of interest were explored in stratified and multivariate models controlling for potential confounders. The overall prevalence of OSA was 25.4%. Given a nonlinear increase by body mass index (BMI) strata (8.9%, 46%; p < 0.0001), stratified multivariate analysis was subsequently performed. Among nonobese (BMI <30) gravidae, frequency of preeclampsia was significantly higher among women with OSA (adjusted odds ratio = 6.58, 95% confidence interval = 1.04, 38.51; p = 0.035). Among the obese (BMI ≥30) gravidae, infant birth weight ratio (or birth weight by gestational age) was higher with OSA + screening than OSA - (1.099 versus 1.035; p = 0.04), and this association remained significant after adjustment for potential confounders (p = 0.05). OSA prevalence increases significantly among obese gravidae, raising concerns for the overall validity of commonly employed screening measures in pregnancy. Nevertheless, OSA status continues to exert an independent influence, as obese and nonobese gravidae are at increased risk for a limited number of adverse perinatal outcomes in multivariate models.

Rate of wound complications with enoxaparin use among women at high risk for postpartum thrombosis.

OBJECTIVE: To estimate the rate of wound complications associated with protocol-driven postcesarean enoxaparin thromboprophylaxis. METHODS: After implementing an Institutional Clinical Practice Guideline for postoperative cesarean delivery thromboprophylaxis among at-risk gravid women (older than 35 years of age, body mass index greater than 30 kg/m2, or both), data on all cesarean deliveries over the first 23 months of guideline implementation were extracted and analyzed. Primary (wound hematoma, separation, or dehiscence) and secondary (venous thromboembolism) outcomes were compared in stratified and multivariable models controlling for potential confounders. RESULTS: Over 23 months, 2,509 cesarean deliveries were performed. A total of 1,677 (68%) gravid women met criteria for thromboprophylaxis; 653 received enoxaparin per protocol ("cases"), and, at the discretion of the ordering physician, 1,024 did not (at-risk, protocol-noncompliant "controls"). Cases differed significantly by virtue of maternal age, body mass index, and diabetic status. Univariable analysis subsequently revealed a higher rate of wound separation (6.8% compared with 3.6%, P=.003), rehospitalization (2.1% compared with 0.8%, P=.017) and composite score (8.9% compared with 4.8%, P=.002) among protocol-compliant cases, but no increased risk of wound hematoma (P>.06). In multivariable analysis, adjusted odds ratios continued to reveal an association between enoxaparin use and wound separation (OR 1.66, P=.04) as well as higher composite score (OR 1.69, P=.01). However, among the protocol-noncompliant controls, a nonsignificant increase in the rate of venous thromboembolism occurred. CONCLUSION: In our series, prophylactic enoxaparin use among at-risk gravid women undergoing cesarean delivery was accompanied by an increased risk of wound separation. LEVEL OF EVIDENCE: II.

Epigenomics: maternal high-fat diet exposure in utero disrupts peripheral circadian gene expression in nonhuman primates.

The effect of in utero exposure to a maternal high-fat diet on the peripheral circadian system of the fetus is unknown. Using mRNA copy number analysis, we report that the components of the peripheral circadian machinery are transcribed in the nonhuman primate fetal liver in an intact phase-antiphase fashion and that Npas2, a paralog of the Clock transcription factor, serves as the rate-limiting transcript by virtue of its relative low abundance (10- to 1000-fold lower). We show that exposure to a maternal high-fat diet in utero significantly alters the expression of fetal hepatic Npas2 (up to 7.1-fold, P<0.001) compared with that in control diet-exposed animals and is reversible in fetal offspring from obese dams reversed to a control diet (1.3-fold, P>0.05). Although the Npas2 promoter remains largely unmethylated, differential Npas2 promoter occupancy of acetylation of fetal histone H3 at lysine 14 (H3K14ac) occurs in response to maternal high-fat diet exposure compared with control diet-exposed animals. Furthermore, we find that disruption of Npas2 is consistent with high-fat diet exposure in juvenile animals, regardless of in utero diet exposure. In summary, the data suggest that peripheral Npas2 expression is uniquely vulnerable to diet exposure.

Genetic and epigenetic influences associated with intrauterine growth restriction due to in utero tobacco exposure.

While many fetuses are exposed to tobacco in utero, not all experience adverse outcomes as a result of this exposure. Mechanisms leading to the attenuation of fetal birth weight and adverse pregnancy outcomes are complex. Therefore many studies have begun to focus, not only on the contribution of maternal and fetal genes to phenotypic outcome, but also on epigenetic changes associated with exposure to maternal tobacco smoke. In this review, we detail the epidemiologic evidence associating an adverse pregnancy outcome to maternal tobacco use. We provide a brief summary of studies demonstrating an association between maternal and fetal gene polymorphisms with low birth weight in response to maternal tobacco exposure. We also review the literature showing epigenetic changes in the offspring associated with in utero tobacco exposure. The complex interplay of genomic and epigenomic factors may contribute to specific phenotypic outcomes and can help begin to elucidate the differential susceptibilities to tobacco smoke in utero.

In utero tobacco exposure epigenetically modifies placental CYP1A1 expression.

The metabolic pathways used by higher-eukaryotic organisms to deal with potentially carcinogenic xenobiotic compounds from tobacco smoke have been well characterized. Carcinogenic compounds such as polycyclic aromatic hydrocarbons are metabolized sequentially in 2 phases: in phase I, CYP1A1 catalyzes conversion into harmful hydrophilic DNA adducts, whereas in phase II, GSTT1 enables excretion via conjugation into polar electrophiles. In an effort to understand susceptibility to in utero tobacco exposure, we previously characterized known metabolic functional polymorphisms and demonstrated that although deletion of fetal GSTT1 significantly modified birth weight in smokers, no polymorphism fully accounted for fetal growth restriction. Because smoking up-regulates CYP1A1 expression, we hypothesized that nonallelic (epigenetic) dysregulation of placental CYP1A1 expression via alterations in DNA methylation (meCpG) may further modify fetal growth. In the present article, we compared placental expression of multiple CYP family members among gravidae and observed significantly increased CYP1A1 expression among smokers relative to controls (4.4-fold, P < .05). To fully characterize CYP1A1 meCpG status, bisulfite modification and sequencing of the entire proximal 1-kilobase promoter (containing 59 CpG sites) were performed. CpG sites immediately proximal to the 5'-xenobiotic response element transcription factor binding element were significantly hypomethylated among smokers (55.6% vs 45.9% meCpG, P = .027), a finding that uniquely correlated with placental gene expression (r = 0.737, P = .007). Thus, in utero tobacco exposure significantly increases placental CYP1A1 expression in association with differential methylation at a critical xenobiotic response element.

Management of ornithine transcarbamylase deficiency in pregnancy.

Ornithine transcarbamylase (OTC) deficiency is the most common enzymatic deficiency in the urea cycle. In catabolic states, such as the intrapartum and immediate postpartum periods, hyperammonemic comas with permanent neurological damage and death can develop. We report six cases of OTC deficiency during pregnancy managed at our institution and review the literature on OTC deficiency during pregnancy. Using the patient database from our Metabolic Clinic, pregnant OTC deficiency carriers were identified. The antenatal, intrapartum, and postpartum periods were analyzed. Corresponding literature was reviewed and an extensive multidisciplinary management plan developed. All six pregnant women had favorable outcomes. No hyperammonemic episodes occurred, and intensive care unit admissions and hemodialysis were not required. Although risk to women with OTC deficiency during the intra- and postpartum period exists, multidisciplinary management and a coherent plan usually result in successful labor, delivery, and postpartum. A comprehensive plan for patients who develop hyperammonemia is recommended.

Prospective trial on obstructive sleep apnea in pregnancy and fetal heart rate monitoring.

OBJECTIVE: Obstructive sleep apnea (OSA) involves episodic nocturnal apneas. Using polysomnography, we examined the predictive capacity of screening questionnaires (Berlin) in pregnancy. Incorporating simultaneous fetal heart rate monitoring (FHM), we examined the association of maternal apnea with FHM abnormalities. STUDY DESIGN: We enrolled 100 pregnant women at 26-39 weeks of gestation with OSA screening and baseline data ascertainment who underwent polysomnography and FHM for > or =3 hours. The relationship between maternal characteristics, OSA, and FHM was explored with multivariate analyses that were controlled for potential confounders. RESULTS: When compared with polysomnography, sensitivity and specificity by Berlin screening was 35% and 63.8%, respectively; the snoring component of the Berlin correlated better with oxygen desaturation <95% (P = .003). Body mass index was a significant confounder (r(s) = 0.44; P < .0001). No association was observed between FHM abnormalities and OSA parameters. CONCLUSION: In pregnancy, the Berlin questionnaire poorly predicts OSA. It is unclear whether fetal compromise during maternal apnea is a mechanism in OSA that is related to pregnancy outcome.

Pharmacogenomics of maternal tobacco use: metabolic gene polymorphisms and risk of adverse pregnancy outcomes.

OBJECTIVE: To assess whether functional maternal or fetal genotypes along well-characterized metabolic pathways (ie, CYP1A1, GSTT1, and CYP2A6) may account for varying associations with adverse outcomes among pregnant women who smoke. METHODS: DNA samples from 502 smokers and their conceptuses, alongside women in a control group, were genotyped for known functional allelic variants of CYP1A1 (Ile462Val AA>AG/GG), GSTT1(del), and CYP2A6 (Lys160His T>A). Modification of the association between smoking and outcome by genotype was evaluated. Outcomes included birth weight, pregnancy loss, preterm birth, small for gestational age, and a composite outcome composed of the latter four components plus abruption. RESULTS: No interaction between maternal or fetal genotype of any of the polymorphisms and smoking could be demonstrated. In contrast, the association of smoking with gestational age-adjusted birth weight (birth weight ratio) was modified by fetal GSTT1 genotype (P for interaction=.02). Fetuses with GSTT1(del) had a mean birth weight reduction among smokers of 262 g (P=.01), whereas in fetuses without the GSTT1(del) the effect of tobacco exposure was nonsignificant (mean reduction 87 g, P=.16). After adjusting for confounding, results were similar. CONCLUSION: Fetal GSTT1 deletion significantly and specifically modifies the effect of smoking on gestational age-corrected birth weight.

Influence of maternal BMI on genetic sonography in the FaSTER trial.

OBJECTIVE: We sought to evaluate the influence of maternal body mass index (BMI) on sonographic detection employing data from the FaSTER trial. METHOD: Unselected singleton pregnancies underwent detailed genetic sonogram to evaluate for structural fetal anomalies and soft markers for aneuploidy. BMI (kg/m(2)) were calculated from reported initial visit values. Sensitivity, specificity, false positive and false negative rates (FPR and FNR), likelihood ratio, detection rates, and a missed diagnosis rate (MDR: FNR + marker recorded as 'missing'/N) were calculated. RESULTS: Eight thousand five hundred and fifty-five patients with complete BMI information had detailed genetic sonography. A lower sensitivity with an elevated FNR and MDR was observed in obese women for multiple aneuploid markers (e.g. > or =2 markers 32% sensitivity with 68% FNR among BMI <25 vs 22% and 78% among BMI >30). Similarly, the detection rate for cardiac anomalies among women at BMI <25 was higher (21.6%) at a significantly lower FPR (78.4%; 95% CI 77.3-79.5%) in comparison to obese women (8.3% with FPR 91.7%; 95% CI 90.1-93.2%). In a logistic regression model, maternal obesity significantly decreased the likelihood of sonographic detection of common anomalies (adjusted OR 0.7; 95% CI 0.6-0.9; p = 0.001). CONCLUSION: The performance of second trimester genetic sonography is influenced by obesity, with a significantly higher MDR for multiple minor markers and lower likelihood for detecting common anomalies.

Pheochromocytoma and Von Hippel-Lindau in pregnancy.

Pheochromocytoma is an infrequent but well-acknowledged primary cause of malignant hypertension in pregnancy. Although the majority of pheochromocytomas are sporadic, those that present as bilateral or multifocal tumors may be a manifestation of a rare cancer susceptibility syndrome, such as Von Hippel-Lindau (VHL). Gravidae with unrecognized pheochromocytoma are at risk for recurrent paroxysmal hypertensive crises with ensuant maternal and fetal risks. To further illustrate the challenges of management of pheochromocytoma and VHL in pregnancy, we present two illustrative cases. In the first, a multigravida presented with an intrauterine fetal demise and malignant hypertension and a concurrent diagnosis of bilateral pheochromocytomas. A missense mutation in exon 3 of the VHL gene was identified, confirming the diagnosis of VHL type 2C. In the second case, a multigravida with a prior diagnosis of VHL syndrome but sporadic follow-up underwent renal and adrenal imaging surveillance as part of her prenatal care. Although she was normotensive and clinically asymptomatic, such imaging enabled the detection of bilateral pheochromocytomas. In summary, in this report we discuss our management in gravidae with pheochromocytoma and VHL, emphasizing current recommendations pertaining to obstetric management, genetic testing, and long-term follow-up.

Role of second-trimester genetic sonography after Down syndrome screening.

OBJECTIVE: To estimate the effectiveness of second-trimester genetic sonography in modifying Down syndrome screening test results. METHODS: The First and Second Trimester Evaluation of Risk (FASTER) aneuploidy screening trial participants were studied from 13 centers where a 15- to 23-week genetic sonogram was performed in the same center. Midtrimester Down syndrome risks were estimated for five screening test policies: first-trimester combined, second-trimester quadruple, and testing sequentially by integrated, stepwise, or contingent protocols. The maternal age-specific risk and the screening test risk were modified using likelihood ratios derived from the ultrasound findings. Separate likelihood ratios were obtained for the presence or absence of at least one major fetal structural malformation and for each "soft" sonographic marker statistically significant at the P<.005 level. Detection and false-positive rate were calculated for the genetic sonogram alone and for each test before and after risk modification. RESULTS: A total of 7,842 pregnancies were studied, including 59 with Down syndrome. Major malformations and 8 of the 18 soft markers evaluated were highly significant. The detection rate for a 5% false-positive rate for the genetic sonogram alone was 69%; the detection rate increased from 81% to 90% with the combined test, from 81% to 90% with the quadruple test, from 93% to 98% with the integrated test, from 97% to 98% with the stepwise test, and from 95% to 97% with the contingent test. The stepwise and contingent use of the genetic sonogram after first-trimester screening both yielded a 90% detection rate. CONCLUSION: Genetic sonography can increase detection rates substantially for combined and quadruple tests and more modestly for sequential protocols. Substituting sonography for quadruple markers in sequential screening was not useful. LEVEL OF EVIDENCE: II.

Loss of Erk3 function in mice leads to intrauterine growth restriction, pulmonary immaturity, and neonatal lethality.

Extracellular signal-regulated kinase 3 (Erk3) is an atypical member of the mitogen-activated protein (MAP) kinase family. No function has yet been ascribed to this MAP kinase. Here we show that targeted disruption of the Mapk6 gene (encoding Erk3) leads to intrauterine growth restriction, associated with marked pulmonary hypoplasia, and early neonatal death during the first day of life. Around 40% of Erk3(-/-) neonates die within minutes after birth from acute respiratory failure. Erk3-deficient mice have normal lung-branching morphogenesis, but show delayed lung maturation characterized by decreased sacculation, atelectasis, and defective type II pneumocyte differentiation. Interestingly, in utero administration of glucocorticoid promoted fetal lung maturity and rescued differentiation of type II cells, but failed to alter the neonatal lethality. We observed that loss of Erk3 retards intrauterine growth, as reflected by a marked reduction in fetal lung, heart, and liver weights, and by low body weight at birth. Importantly, we found that insulin-like growth factor (IGF)-2 levels are decreased in the serum of Erk3-deficient mice. Our findings reveal a critical role for Erk3 in the establishment of fetal growth potential and pulmonary function in the mouse.

A maternal high-fat diet is accompanied by alterations in the fetal primate metabolome.

OBJECTIVE: To characterize the serum metabolome of a primate model of in utero high-fat exposure. STUDY DESIGN: Serum from maternal and fetal (e130) macaque monkeys exposed to either a high-fat or control diet were analyzed by gas chromatography-mass spectrometry. Multivariate data analysis was performed to reduce the generated data set. Candidate metabolites were further analyzed for significance by using the analysis of variance and comparative t tests. RESULTS: Approximately 1300 chromatographic features were detected. Through multivariate data analysis this number was reduced to 60 possible metabolites. With the use of comparative t tests, 22 metabolites had statistical significance (P < .05) over the entire study. By virtue of maternal high-fat diet alone, fetal phenotypic differences are accompanied by altered metabolite concentrations of 7 metabolites (P < .05). CONCLUSION: In utero high-fat diet exposure is associated with an altered fetal epigenome and parlays a characteristic modification in the fetal metabolite profile.

Group A streptococcal puerperal sepsis: initial characterization of virulence factors in association with clinical parameters.

Group A beta-hemolytic streptococcus (GAS) is an uncommon but potentially fatal source of postpartum infection. Pathogenesis in invasive GAS infections has been linked to bacterial virulence factors. In this study, we sought to provide an initial description of potential virulence factors in association with puerperal morbidity by virtue of specific M-protein type antigens. Women with confirmed GAS puerperal infection in the Salt Lake City region were prospectively identified over a 6-year interval (1991-1997). From this cohort, GAS isolates were analyzed with respect to M-serotype and presence of genes encoding the Streptococcal Pyogenic Exotoxins A and B (SPE-A and SPE-B). Bacterial isolates from 18 subjects with GAS puerperal infection underwent M-serotyping and PCR-based genotyping for the speA and speB genes. Among these, 8/18 subjects manifest criteria of severe disease. All 18 isolate strains expressed speB; 6/18 isolates expressed speA. Of the M-serotypes, 8/8 severe disease isolates expressed M-types 1 (N=3) or 28 (N=5). Pulse-field gel electrophoresis did not indicate an outbreak strain among similar isolates. We conclude that in this initial characterization, morbidity among women with GAS puerperal infection is associated with M-types 1 and 28, but not speB genotype.

Animal models of epigenetic inheritance.

Although genomic DNA is the template of our heredity, it is the coordination and regulation of its expression that results in the wide complexity and diversity seen among organisms. In recent years, an emerging body of evidence has focused on the role of epigenetics as one mechanism by which gene expression can be maintained and modulated throughout the lifetime of an individual. Epigenetics refers to heritable alterations in gene expression that are not mediated by changes in primary DNA sequence and includes mitotic and/or meiotic events. In essence, epigenetic modulation results in functional adaptations of the genomic response to the environment and is believed to play a fundamental role in early developmental plasticity. This article focuses on several animal models that have been developed over the past decade to study epigenetic inheritance, many of which have arisen from the developmental origins of adult health and disease fields.

Environmental influences on epigenetic profiles.

Studies of environmental challenges, such as hazardous air pollutants, nonmutagenic toxins, diet choice, and maternal behavioral patterns, reveal changes in gene expression patterns, DNA methylation, and histone modifications that are in causal association with exogenous exposures. In this article we summarize some of the recent advances in the field of environmental epigenetics and highlight seminal studies that implicate in utero exposures as causative agents in altering not only the epigenome of the exposed gestation, but that of subsequent generations. Current studies of the effects of maternal behavior, exposure to environmental toxins, and exposure to maternal diet and an altered gestational milieu are summarized.