Genetic variants associated with patent ductus arteriosus in extremely preterm infants

Clinical and echocardiography predictors of response to first-line acetaminophen treatment in preterm infants with hemodynamically significant patent ductus arteriosus

OBJECTIVE

To assess clinical and echocardiography predictors of acetaminophen response for the treatment of patent ductus arteriosus (PDA) in preterm neonates.

STUDY DESIGN

Retrospective cohort study of preterm infants born <30 weeks, with a diagnosis of hemodynamically significant PDA, who received 1st line treatment with intravenous acetaminophen during the first 2 postnatal weeks. Response was defined by PDA closure or improvement in PDA score of >50%.

RESULTS

A total of 100 infants were included whose median weight and gestational age at birth were 663 grams and 24.6 weeks respectively. In total, 66 infants were classified as responders and were more likely to have intrauterine growth restriction, exposure to maternal hypertension and chorioamnionitis. Non-response was more common among infants with thrombocytopenia and anemia.

CONCLUSION

Responders were more likely to be IUGR with echocardiography indices of lower preload. Response to 1st line intravenous acetaminophen therapy is comparable to non-steroidal drugs in preterm infants. Relationship of response to acetaminophen to perinatal characteristics requires further characterization.

Prenatal benzene exposure alters offspring hypothalamic development predisposing to metabolic disease in later life

The hypothalamus is essential in the regulation of metabolism, notably during critical windows of development. An abnormal hormonal and inflammatory milieu during development can trigger persistent changes in the function of hypothalamic circuits, leading to long-lasting effects on the body’s energy homeostasis and metabolism. We recently demonstrated that gestational exposure to benzene at smoking levels induces severe metabolic dysregulation in the offspring. Given the central role of the hypothalamus in metabolic control, we hypothesized that prenatal exposure to benzene impacts hypothalamic development, contributing to the adverse metabolic effects in the offspring. C57BL/6JB dams were exposed to benzene in the inhalation chambers exclusively during pregnancy (from E0.5 to E19). The transcriptome analysis of the offspring hypothalamus at postnatal day 21 (P21) revealed changes in genes related to metabolic regulation, inflammation, and neurodevelopment exclusively in benzene-exposed male offspring. Moreover, the hypothalamus of prenatally benzene-exposed male offspring displayed alterations in orexigenic and anorexigenic projections, impairments in leptin signaling, and increased microgliosis. Additional exposure to benzene during lactation did not promote further microgliosis or astrogliosis in the offspring, while the high-fat diet (HFD) challenge in adulthood exacerbated glucose metabolism and hypothalamic inflammation in benzene-exposed offspring of both sexes. These findings reveal the persistent impact of prenatal benzene exposure on hypothalamic circuits and neuroinflammation, predisposing the offspring to long-lasting metabolic health conditions.

Contributions of the NICHD neonatal research network to the diagnosis, prevention, and treatment of bronchopulmonary dysplasia

Despite improvements in the care and outcomes of infants born extremely preterm, bronchopulmonary dysplasia (BPD) remains a common and frustrating complication of prematurity. This review summarizes the BPD-focused research conducted by the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN). To improve disease classification and outcome prediction, the NRN developed new data-driven diagnostic criteria for BPD and web-based tools that allow clinicians and investigators to reliably estimate BPD risk in preterm infants. Randomized trials of intramuscular vitamin A and prophylactic nasal continuous positive airway pressure conducted by the NRN have contributed to our current use of these therapies as evidence-based approaches to reduce BPD risk. A recent large, randomized trial of hydrocortisone administered beginning between the 2nd and 4th postnatal weeks provided strong evidence that this therapy promotes successful extubation but does not lower BPD rates. Ongoing studies within the NRN will address important, unanswered questions on the risks and benefits of intratracheal surfactant/corticosteroid combinations and treatment versus expectant management of the patent ductus arteriosus to prevent BPD.

Sex Differences in Patent Ductus Arteriosus Incidence and Response to Pharmacological Treatment in Preterm Infants: A Systematic Review, Meta-Analysis and Meta-Regression

A widely accepted concept in perinatal medicine is that boys are more susceptible than girls to complications of prematurity. However, whether this ‘male disadvantage of prematurity’ also involves persistent patent ductus arteriosus (PDA) has been scarcely investigated. Our aim was to conduct a systematic review and meta-analysis on studies addressing sex differences in the risk of developing PDA among preterm infants. We also investigated whether the response to pharmacological treatment of PDA differs between boys and girls. PubMed/Medline and Embase databases were searched. The random-effects male/female risk ratio (RR) and 95% confidence interval (CI) were calculated. We included 146 studies (357,781 infants). Meta-analysis could not demonstrate sex differences in risk of developing any PDA (37 studies, RR 1.03, 95% CI 0.97 to 1.08), hemodynamically significant PDA (81 studies, RR 1.00, 95% CI 0.97 to 1.02), or in the rate of response to pharmacological treatment (45 studies, RR 1.01, 95% CI 0.98 to 1.04). Subgroup analysis and meta-regression showed that the absence of sex differences was maintained over the years and in different geographic settings. In conclusion, both the incidence of PDA in preterm infants and the response rate to pharmacological treatment of PDA are not different between preterm boys and girls.

Mouse models of patent ductus arteriosus (PDA) and their relevance for human PDA

The ductus arteriosus (DA) is a unique fetal vascular shunt, which allows blood to bypass the developing lungs in utero. After birth, changes in complex signaling pathways lead to constriction and permanent closure of the DA. The persistent patency of the DA (PDA) is a common disorder in preterm infants, yet the underlying causes of PDA are not fully defined. Although limits on the availability of human DA tissues prevent comprehensive studies on the mechanisms of DA function, mouse models have been developed that reveal critical pathways in DA regulation. Over 20 different transgenic models of PDA in mice have been described, with implications for human DA biology. Similarly, we enumerate 224 human single-gene syndromes that are associated with PDA, including a small subset that consistently feature PDA as a prominent phenotype. Comparison and functional analyses of these genes provide insight into DA development and identify key regulatory pathways that may serve as potential therapeutic targets for the management of PDA.

Interactions between PDA-associated polymorphisms and genetic ancestry alter ductus arteriosus gene expression

BACKGROUND

DNA polymorphisms in PTGIS and TFAP2B have been identified as risk factors for patent ductus arteriosus (PDA) in a population composed of preterm infants with European genetic ancestry but not in more genetically diverse populations.

GOAL

To determine if the effects of TFAP2B and PTGIS polymorphisms on ductus arteriosus (DA) gene expression differ based on genetic ancestry.

METHODS

DA from 273 human second trimester fetuses were genotyped for TFAP2B and PTGIS polymorphisms and for polymorphisms distributing along genetic ancestry lines. RT-PCR was used to measure the RNA expression of 49 candidate genes involved with DA closure.

RESULTS

Seventeen percent of the DA analyzed were of European ancestry. In multivariable regression analyses we found consistent associations between four PDA-related TFAP2B polymorphisms (rs2817399(A), rs987237(G), rs760900(C), and rs2817416(C)) and expression of the following genes: EPAS1, CACNB2, ECE1, KCNA2, ATP2A3, EDNRA, EDNRB, BMP9, and BMP10, and between the PTGIS haplotype rs493694(G)/rs693649(A) and PTGIS and NOS3. These changes only occurred in DA with European ancestry. No consistent positive or negative associations were found among DA samples unless an interaction between the polymorphisms and genetic ancestry was taken into account.

CONCLUSION

PTGIS and TFAP2B polymorphisms were associated with consistent changes in DA gene expression when present in fetuses with European ancestry.

IMPACT

DNA polymorphisms in PTGIS and TFAP2B have been identified as risk factors for patent ductus arteriosus (PDA) in a population composed primarily of preterm infants with European genetic ancestry but not in more genetically diverse populations. The same PTGIS and TFAP2B polymorphisms are associated with changes in ductus gene expression when present in ductus from fetuses with European genetic ancestry. No consistent associations with gene expression can be found unless an interaction between the polymorphisms and genetic ancestry is taken into account.

Genetic predictors of severe intraventricular hemorrhage in extremely low-birthweight infants

OBJECTIVE

To test associations between grades 3 or 4 (severe) intraventricular hemorrhage (IVH) and single nucleotide polymorphisms (SNPs) associated with coagulation, inflammation, angiogenesis, and organ development in an exploratory study.

STUDY DESIGN

Extremely low-birthweight (ELBW) infants enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network's (NRN) Cytokines Study were included if they had cranial ultrasound (CUS) and genotyping data available in the NRN Anonymized DNA Repository and Database. Associations between SNPs and IVH severity were tested with multivariable logistic regression analysis.

RESULT

One hundred thirty-nine infants with severe IVH and 687 infants with grade 1 or 0 IVH were included. One thousand two hundred seventy-nine SNPs were genotyped. Thirteen were preliminarily associated with severe IVH including five related to central nervous system (CNS) neuronal and neurovascular development.

CONCLUSION

Genetic variants for CNS neuronal and neurovascular development may be associated with severe IVH in premature infants.

Spontaneous Closure of the Ductus Arteriosus in Preterm Infants: A Systematic Review

The optimal management strategy for patent ductus arteriosus in preterm infants remains a topic of debate. Available evidence for a treatment strategy might be biased by the delayed spontaneous closure of the ductus arteriosus in preterm infants, which appears to depend on patient characteristics. We performed a systematic review of all literature on PDA studies to collect patient characteristics and reported numbers of patients with a ductus arteriosus and spontaneous closure. Spontaneous closure rates showed a high variability but were lowest in studies that only included preterm infants with gestational ages below 28 weeks or birth weights below 1,000 g (34% on day 4; 41% on day 7) compared to studies that also included infants with higher gestational ages or higher birth weights (up to 55% on day 3 and 78% on day 7). The probability of spontaneous closure of the ductus arteriosus keeps increasing until at least 1 week after birth which favors delayed treatment of only those infants that do not show spontaneous closure. Better prediction of the spontaneous closure of the ductus arteriosus in the individual newborn is a key factor to find the optimal management strategy for PDA in preterm infants.

Early Urinary Metabolomics in Patent Ductus Arteriosus Anticipates the Fate: Preliminary Data

Introduction: In premature neonates, the persistence of hemodynamically significant ductus arteriosus (hsPDA) can be associated with short- and long-term consequences, impairing their outcome. The correct strategy of management for such condition is under debate, especially regarding contraindications and/or side effects. In recent years, metabolomics was applied to several perinatal, pediatric, and adult conditions to investigate potential biomarkers of disease, which have become useful for early diagnosis and/or therapeutic management. Aim of the Study: The main purpose of our exploratory study was to asses, through ¹H-NMR metabolomics analysis of urinary samples at birth, possible metabolic pathways differentiating, with a significant predictive power, those preterm neonates who will subsequently develop hsPDA and neonates of comparable gestational age (GA) who will undergo spontaneous ductal closure or the persistence of an irrelevant PDA (no-hsPDA). Moreover, we investigated potential prenatal or perinatal clinical factors potentially influencing the development of hsPDA. Materials and Methods: We enrolled n = 35 preterm neonates with GA between 24 and 32 weeks; urinary samples were collected within the first 12 h of life. Patients were closely monitored regarding intensive care, respiratory support, fluid balance and administered drugs; an echocardiogram was performed at 48-72 h. Results: Our results reported a significant correlation between lower GA at birth and the development of hsPDA. Moreover, neonates with GA ≤ 30w developing hsPDA were characterized by lower Apgar scores at 1' and 5', higher rates of perinatal asphyxia, higher need of delivery room resuscitation and subsequent surfactant administration. Interestingly, metabolomics analysis at birth detected a clear separation between the ¹H-NMR urinary spectra of subjects GA ≤ 30w not developing hsPDA (n = 19) and those of subjects born at GA ≤ 30w in which hsPDA was confirmed at 48-72 h of life (n = 5). Conclusions: This is the first study applying metabolomics to investigate the PDA condition. Although preliminary and conducted on a limited sample, our results reveal that metabolomics could be a promising tool in the early identification of hsPDA, potentially superior to the clinical or laboratory predictive tools explored to date and even to the clinical observations and correlations in our sample, through the detection of specific urinary metabolites.

Pilot study to establish a prospective neonatal cohort: Study of Preterm Infants and Neurodevelopmental Genes (SPRING)

BACKGROUND

Genetic risk variants and preterm birth are early and potent risk factors for later neuropsychiatric disorders. To understand the interrelationships between these factors, a large-scale genetic study of very preterm (VPT, <32 weeks gestation) infants with prospective follow-up is required. In this paper, we describe a streamlined study approach, using efficient processes for biological and clinical data collection, to feasibly establish such a cohort.

METHODS

We sought to recruit 500 VPT families within a 1 year period from neonatal units. Treating clinical teams recruited eligible participants, obtained parent consent, collected blood samples and posted specimens to the research laboratory. We extracted all clinical data from the National Neonatal Research Database, an existing UK resource that captures daily patient-level data on all VPT infants.

RESULTS

Between May 2017 and June 2018, we established a cohort of 848 VPT infants and their parents from 60 English neonatal units. The study population (median (IQR), gestation: 28.9 (26-30) weeks; birth weight: 1120 (886-1420) g) represented 18.9% of eligible infants born at the study sites during the recruitment period (n=4491). From the subset of 521 complete family trios, we successfully completed genotyping for 510 (97.9%) trios. Of the original 883 infants whose parents consented to participate, the parents of 796 (90.1%) infants agreed to future data linkage and 794 (89.9%) agreed to be recalled.

CONCLUSION

We demonstrate the feasibility and acceptability of streamlined strategies for genetic, neonatal and longitudinal data collection and provide a template for future cost-effective and efficient cohort development.