Respiratory Outcomes Program Research Articles

Local clinical informatics investments are required for in silico biomarker generation across the globe: lessons learned from a secondary analysis of the PROP trial

Background Advances in statistical modelling and machine learning approaches, which can be deployed locally using open source programming languages, represent a unique opportunity to improve workflows and lower costs in health care across the globe through the creation of in silico biomarkers. The goal of this study was to extract meaningful data from the publicly available Prematurity and Respiratory Outcomes Program (PROP) trial data that could help generate useful clinical diagnostic aids with minimal cost for deployment in global healthcare settings. Methods A cluster analysis of the PROP dataset was conducted. We generated a simple model using an open-source software platform that generates a growth prediction of patients born less than 30 weeks. We then obtained validation data from a Uruguayan hospital to test the capacity for deployment of the models. Results Analysis revealed two main clusters of patients in the trial, with differentiation mainly based on the clinical and anthropomorphic measurements of birth gestational age, birth weight, and head circumference. The anthropometric measurements of daily weight, birth weight, head circumference, and birth gestational age were highly correlated with respiratory dysfunction and co-morbidities We note that deviation from this predicted growth curve in PROP patients was associated with culture-proven sepsis, and may represent a more sensitive anthropomorphic biomarker than the weight percentile systems routinely used globally such as Fenton curves. We found that early deviation from our projected growth model was highly associated with patient fatality. However, over long-term predictions, models trained on PROP clinical trial patients showed significantly more error in the Uruguayan patients. Conclusions Although these prediction models built upon PROP data were not generalizable to Uruguayan patients, our data suggest that prediction models using simple anthropomorphic measurements, if trained on local patients, may be able to provide value as a low-cost in silico biomarker. We concluded that local investment in clinical informatics infrastructure is needed to train models based on locally extracted clinical data.

Transcriptome-Wide m6A Methylome and m6A-Modified Gene Analysis in Asthma.

N6-methyladenosine (m6A) modification is one of the most prevalent RNA modification forms and is an important posttranscriptional mechanism for regulating genes. In previous research, we found that m6A regulator–mediated RNA methylation modification was involved in asthma; however, the specific modified genes are not clear. In this study, we systematically evaluated the transcriptome-wide m6A methylome and m6A-modified genes in asthma. Here, we performed two high-throughput sequencing methods, methylated RNA immunoprecipitation sequencing (MeRIP-seq), and RNA sequencing (RNA-seq) to identify key genes with m6A modification in asthma. Through difference analysis, we found that 416 methylation peaks were significantly upregulated and 152 methylation peaks were significantly downregulated, and it was mainly distributed in 3′ UTR. Furthermore, compared with the control group, there were 2,505 significantly upregulated genes and 4,715 significantly downregulated genes in the asthma group. Next, through a combined analysis of transcriptome and differential peaks, 14 differentially expressed genes related to RNA methylation modification were screened. Finally, through 87 health controls and 411 asthma cases from the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes) program, we verified three m6A-modified key genes (BCL11A, MATK, and CD300A) and found that they were mainly distributed in exons and enriched in 3' UTR. Our findings suggested that intervening in m6A-modified genes may provide a new idea for the treatment of asthma.

Pulmonary function tests in extremely low gestational age infants at one year of age.

Identifying neonatal and post-discharge exposures among extremely low gestational age newborns (ELGANs) that drive increased pulmonary morbidity and abnormal lung function at 1 year of age proves challenging. The NIH-sponsored Prematurity and Respiratory Outcomes Program (PROP), evaluated infant pulmonary function tests (iPFTs) at 1 year corrected age to determine which demographic and clinical factors are associated with abnormal lung function. iPFTs were performed on a PROP subcohort of 135 participants following Institutional Review Board (IRB)-approved written consent. Demographic data, Neonatal Intensive Care Unit (NICU) clinical care, and post-NICU exposures were analyzed for association with iPFTs. A significant decrease in forced expiratory volume at 0.5 s (FEV0.5 ) and/or forced expiratory flows at 75% of forced vital capacity (FEF75 ), were associated with male sex and African American race. Clinical factors including longer duration of ventilatory support, exposure to systemic steroids, and weight less than the 10th percentile at 36 weeks postmenstrual age were also associated with airflow obstruction, whereas supplemental oxygen requirement and bronchopulmonary dysplasia were not. Additionally, the need for respiratory medications, technology, or hospitalizations during the first year, ascertained by a quarterly survey, were the only post-NICU factors associated with decreased FEV0.5 and FEF75 . Only 7% of infants had reversible airflow obstruction. Neonatal demographic factors, respiratory support in the NICU, and a history of greater post-NICU medical utilization for respiratory disease had the strongest association with lower lung function at 1 year in ELGANs.

Lymphocyte-Specific Biomarkers Associated With Preterm Birth and Bronchopulmonary Dysplasia.

Many premature babies who are born with neonatal respiratory distress syndrome (RDS) go on to develop Bronchopulmonary Dysplasia (BPD) and later Post-Prematurity Respiratory Disease (PRD) at one year corrected age, characterized by persistent or recurrent lower respiratory tract symptoms frequently related to inflammation and viral infection. Transcriptomic profiles were generated from sorted peripheral blood CD8+ T cells of preterm and full-term infants enrolled with consent in the NHLBI Prematurity and Respiratory Outcomes Program (PROP) at the University of Rochester and the University at Buffalo. We identified outcome-related gene expression patterns following standard methods to identify markers for oxygen utilization and BPD as outcomes in extremely premature infants. We further identified predictor gene sets for BPD based on transcriptomic data adjusted for gestational age at birth (GAB). RNA-Seq analysis was completed for CD8+ T cells from 145 subjects. Among the subjects with highest risk for BPD (born at <29 weeks gestational age (GA); n=72), 501 genes were associated with oxygen utilization. In the same set of subjects, 571 genes were differentially expressed in subjects with a diagnosis of BPD and 105 genes were different in BPD subjects as defined by physiologic challenge. A set of 92 genes could predict BPD with a moderately high degree of accuracy. We consistently observed dysregulation of TGFB, NRF2, HIPPO, and CD40-associated pathways in BPD. Using gene expression data from both premature and full-term subjects (n=116), we identified a 28 gene set that predicted the PRD status with a moderately high level of accuracy, which also were involved in TGFB signaling. Transcriptomic data from sort-purified peripheral blood CD8+ T cells from 145 preterm and full-term infants identified sets of molecular markers of inflammation associated with independent development of BPD in extremely premature infants at high risk for the disease and of PRD among the preterm and full-term subjects.

Early Neonatal Oxygen Exposure Predicts Pulmonary Morbidity and Functional Deficits at 1 Year

To evaluate the predictive value of cumulative oxygen exposure thresholds over the first 2 postnatal weeks, linking them to bronchopulmonary dysplasia (BPD) and 1-year pulmonary morbidity and lung function in extremely low gestational age newborns. Infants (N=704) enrolled in the Prematurity and Respiratory Outcomes Program, a multicenter prospective cohort study, that survived to discharge were followed through their neonatal intensive care unit hospitalization to 1-year corrected age. Cumulative oxygen exposure (OxygenAUC14) thresholds were derived from univariate models of BPD, stratifying infants into high-, intermediate-, and low-oxygen exposure groups. These groups were then used in multivariate logistic regressions to prospectively predict post-prematurity respiratory disease (PRD), respiratory morbidity score (RMS) in the entire cohort, and pulmonary function z scores (N=108 subset of infants) at 1-year corrected age. Over the first 14 postnatal days, infants exposed to high oxygen averaged ≥33.1% oxygen, infants exposed to intermediate oxygen averaged 29.1%-33.1%, and infants exposed to low oxygen were below both cutoffs. In multivariate models, infants exposed to high oxygen showed increased PRD and RMS, whereas infants exposed to intermediate oxygen demonstrated increased moderate/severe RMS. Infants in the high/intermediate groups had decreased forced expiratory volume at 0.5seconds/forced vital capacity ratio. OxygenAUC14 establishes 3 thresholds of oxygen exposure that risk stratify infants early in their neonatal course, thereby predicting short-term (BPD) and 1-year (PRD, RMS) respiratory morbidity. Infants with greater OxygenAUC14 have altered pulmonary function tests at 1year of age, indicating early evidence of obstructive lung disease and flow limitation, which may predispose extremely low gestational age newborns to increased long-term pulmonary morbidity. ClinicalTrials.gov: NCT01435187.

Perinatal events predicting retinopathy of prematurity in extremely pre-term infants.

Extremely preterm infants are peculiar in regard to their risk of retinopathy of prematurity (ROP). In this study, we aim to study insults that may affect extremely preterm infants, including prenatal, at birth, and postnatal insults and their effect on the development of ROP. This study used the data from Prematurity and Respiratory Outcomes Program (PROP). All included infants with a gestational age of 23 0/7 to 28 6/7 weeks using best obstetrical estimate. We included stressful events and/or modifiable variables that may affect the normal development. We used multiple regression analysis in our statistical analysis. We included a total of 751 infants in our study. The mean birth weight for the included sample was 915.1 (±232.94) grams. 391 (52.1%) Infants were diagnosed with ROP. We found a significant negative correlation between ROP development and birth weight (p < 0.001), with a correlation coefficient of - 0.374. We found that the need for prophylactic indomethacin (OR 1.67), the occurrence of air leaks (OR: 2.35), ventilator-associated pneumonia (OR: 2.01), isolated bowel perforations (OR: 3.7), blood culture-proven sepsis (OR: 1.5), other infections (OR: 1.44), and receiving ventricular shunt (OR: 2.9) are significantly associated with the development of ROP. We believe this study included the largest number of factors studied in the largest sample of extremely premature infants. We recommend a screening program for extremely preterm infants that takes into account a scoring system with higher scores for complicated condition.

Secondary Analysis of Premature Respiratory Outcomes Program (PROP) Clinical Trial to Identify Correlations of Risk Factors for Respiratory Morbidity and Mortality in Premature Infants

BackgroundThe Premature Respiratory Outcomes Program (PROP) was a collaborative, multi‐disciplinary clinical study that sought to analyze the factors that could predict future risk for respiratory morbidity and mortality for 835 premature infants with gestational ages 23 0/7 to 28 6/7 weeks. PROP investigators conducted physiologic challenges called Room Air Challenges (RAC) and Hypoxic Challenges Tests (HCT) to determine whether the premature infants could maintain their SpO2 in the target range of ≥90% and to assess pulmonary reserve in former premature infants without Bronchopulmonary Dysplasia(BPD) at 36 weeks’ premenstrual age (PMA). This project was funded by the National Institutes of Health (NIH) and the National Heart, Lung, and Blood Institute (NHLBI) for 5 years through a $18.5 million research initiative.ObjectiveWe are interested in understanding the relationship between brain imaging data and respiration outcomes, and infection or chorioamnionitis and respiration outcomes. In addition, the RAC and HCT provides the opportunity to analyze the outcomes of physiologic challenges in preterm infants compared to term infants undergoing the same challenges in studies that conducted preflight HCT.Statement of the methodsWe utilized machine learning tools such as random forest, support vector machines, gradient boosted machines, and logistic regression to generate predictive models of the aforementioned features.Summary of resultsPreliminary data analysis of key variables to be included in our future data analytics includes standard deviations for birth weight (gm) (235.98), the baby’s head circumference (cm) (83.05), APGAR for one minute (scored 1–10) (2.47), and APGAR 5 minutes (2.10).Statement of conclusionsThis PROP clinical study encapsulates an immense amount of multidisciplinary data from 835 premature infants, which is an extremely special population to include in research as approximately 1 out of every 9 births in the United States occurs prematurely.Support or Funding InformationR01HL132355

Urine gastrin‐releasing peptide in the first week correlates with bronchopulmonary dysplasia and post‐prematurity respiratory disease

Bronchopulmonary dysplasia (BPD) is associated with post-prematurity respiratory disease (PRD) in survivors of extreme preterm birth. Identifying early biomarkers that correlate with later development of BPD and PRD may provide insights for intervention. In a preterm baboon model, elevated gastrin-releasing peptide (GRP) is associated with BPD, and GRP inhibition mitigates BPD occurrence. We performed a prospective cohort study to investigate whether urine GRP levels obtained in the first postnatal week were associated with BPD, PRD, and other urinary biomarkers of oxidative stress. Extremely low gestational age infants (23-28 completed weeks) were enrolled in a US multicenter observational study, The Prematurity and Respiratory Outcomes Program (http://clinicaltrials.gov/ct2/show/NCT01435187). We used multivariable logistic regression to examine the association between urine GRP in the first postnatal week and multiple respiratory outcomes: BPD, defined as supplemental oxygen use at 36 + 0 weeks postmenstrual age, and post-PRD, defined by positive quarterly surveys for increased medical utilization over the first year (PRD score). A total of 109 of 257 (42%) infants had BPD, and 120 of 217 (55%) had PRD. On adjusted analysis, GRP level more than 80 was associated with BPD (adjusted odds ratio [aOR], 1.83; 95% confidence interval [CI], 1.03-3.25) and positive PRD score (aOR, 2.46; 95% CI, 1.35-4.48). Urine GRP levels correlated with duration of NICU ventilatory and oxygen support and with biomarkers of oxidative stress: allantoin and 8-hydroxydeoxyguanosine. Urine GRP in the first postnatal week was associated with concurrent urine biomarkers of oxidative stress and with later diagnoses of BPD and PRD.

Respiratory medication use in extremely premature (

The use of medications to treat respiratory conditions of extreme prematurity is often based upon studies of adults or children over 2 years of age. Little is known about the spectrum of medications used or dosing ranges. To inform the design of future studies, we conducted a prospective analysis of respiratory medication exposure among 832 extremely low gestational age neonates. The prematurity and respiratory outcomes program (PROP) enrolled neonates less than 29-week gestation from 6 centers incorporating 13 clinical sites. We collected recorded daily "respiratory" medications given along with dosing information through 40-week postmenstrual age orneonatal intensive care unit discharge if earlier. PROP participants were exposed to a wide range of respiratory medications, often at doses beyond published recommendations. Nearly 50% received caffeine and furosemide beyond published recommendations for cumulative dose. Those who developed bronchopulmonary dysplasia were more likely to receive treatment with respiratory medications. However, more than 30% of PROP subjects that did not develop bronchopulmonary dysplasia also were treated with diuretics, systemic steroids, and other respiratory medications. Extremely preterm neonates in PROP were exposed to high doses of medications at levels known to generate significant adverse effects. With limited evidence for efficacy, there is an urgent need for controlled trials in this vulnerable patient population.

Respiratory Medications in Infants

To determine patterns of respiratory medications used in neonatal intensive care unit graduates. The Prematurity Respiratory Outcomes Program enrolled 835 babies <29weeks of gestation in the first week. Of 751 survivors, 738 (98%) completed at least 1, and 85% completed all 4, postdischarge medication usage in-person/telephone parental questionnaires requested at 3, 6, 9, and 12months of corrected age. Respiratory drug usage over the first year of life after in neonatal intensive care unit discharge was analyzed. During any given quarter, 66%-75% of the babies received no respiratory medication and 45% of the infants received no respiratory drug over the first year. The most common postdischarge medication was the inhaled bronchodilator albuterol; its use increased significantly from 13% to 31%. Diuretic usage decreased significantly from 11% to 2% over the first year. Systemic steroids (prednisone, most commonly) were used in approximately 5% of subjects in any one quarter. Inhaled steroids significantly increased over the first year from 9% to 14% at 12months. Drug exposure changed significantly based on gestational age with 72% of babies born at 23-24weeks receiving at least 1 respiratory medication but only 40% of babies born at 28weeks. Overall, at some time in the first year, 55% of infants received at least 1 drug including an inhaled bronchodilator (45%), an inhaled steroid (22%), a systemic steroid (15%), or diuretic (12%). Many babies born at <29weeks have no respiratory medication exposure postdischarge during the first year of life. Inhaled medications, including bronchodilators and steroids, increase over the first year.

Patient, Family, and Center-Based Factors Associated with Attrition in Neonatal Clinical Research: A Prospective Study

Background: Attrition, or loss to follow-up, presents a significant threat to the integrity and validity of longitudinal clinical research. Little is known about predictors of attrition in neonatal clinical research, and no prior studies have examined how families’ experiences participating in research with their infants influences study compliance. Objective: To identify novel factors that were associated with attrition over 1 year of study follow-up among preterm infants enrolled in the multicenter Prematurity and Respiratory Outcomes Program (PROP) observational study. Methods: At discharge, research coordinators estimated the likelihood of attrition. The parents completed questionnaires about their experience with the study at discharge and at 1 year corrected age. The primary endpoint was completion of 4 PROP interviews during the first year. Logistic models were used to evaluate the associations between infant, family, and center-based characteristics and attrition. Results: Among 318 children, 283 (89%) met the primary endpoint. In bivariate analyses, lower maternal education, more people in the household, public insurance, and site were associated with attrition (p < 0.05). Parent survey responses, infant characteristics, and site characteristics were unrelated to attrition. Coordinators’ prediction of attrition was associated with completion of early study interviews; this effect waned over time. In multivariable analyses, lower maternal education and more people in the household were the factors most strongly associated with attrition. Conclusion: Future neonatal research should evaluate novel strategies to decrease the burden associated with study participation and reinforcement of study goals with families who have lower educational levels to facilitate participation and decrease attrition bias.

Tidal Breathing Measurements at Discharge and Clinical Outcomes in Extremely Low Gestational Age Neonates.

The relationship between respiratory function at hospital discharge and the severity of later respiratory disease in extremely low gestational age neonates is not well defined. To test the hypothesis that tidal breathing measurements near the time of hospital discharge differ between extremely premature infants with bronchopulmonary dysplasia (BPD) or respiratory disease in the first year of life and those without these conditions. Study subjects were part of the PROP (Prematurity and Respiratory Outcomes Program) study, a longitudinal cohort study of infants born at less than 29 gestational weeks followed from birth to 1 year of age. Respiratory inductance plethysmography was used for tidal breathing measurements before and after inhaled albuterol 1 week before anticipated hospital discharge. Infants were breathing spontaneously and were receiving less than or equal to 1 L/min nasal cannula flow at 21% to 100% fraction of inspired oxygen. A survey of respiratory morbidity was administered to caregivers at 3, 6, 9, and 12 months corrected age to assess for respiratory disease. We compared tidal breathing measurements in infants with and without BPD (oxygen requirement at 36 wk) and with and without respiratory disease in the first year of life. Measurements were also performed in a comparison cohort of term infants. A total of 765 infants survived to 36 weeks postmenstrual age, with research-quality tidal breathing data in 452 out of 564 tested (80.1%). Among these 452 infants, the rate of postdischarge respiratory disease was 65.7%. Compared with a group of 18 term infants, PROP infants had abnormal tidal breathing patterns. However, there were no clinically significant differences in tidal breathing measurements in PROP infants who had BPD or who had respiratory disease in the first year of life compared with those without these diagnoses. Bronchodilator response was not significantly associated with respiratory disease in the first year of life. Extremely premature infants receiving less than 1 L/min nasal cannula support at 21% to 100% fraction of inspired oxygen have tidal breathing measurements that differ from term infants, but these measurements do not differentiate those preterm infants who have BPD or will have respiratory disease in the first year of life from those who do not. Clinical trial registered with www.clinicaltrials.gov (NCT01435187).

Exome sequencing identifies gene variants and networks associated with extreme respiratory outcomes following preterm birth

BackgroundPrevious studies have identified genetic variants associated with bronchopulmonary dysplasia (BPD) in extremely preterm infants. However, findings with genome-wide significance have been rare, and not replicated. We hypothesized that whole exome sequencing (WES) of premature subjects with extremely divergent phenotypic outcomes could facilitate the identification of genetic variants or gene networks contributing disease risk.ResultsThe Prematurity and Respiratory Outcomes Program (PROP) recruited a cohort of > 765 extremely preterm infants for the identification of markers of respiratory morbidity. We completed WES on 146 PROP subjects (85 affected, 61 unaffected) representing extreme phenotypes of early respiratory morbidity. We tested for association between disease status and individual common variants, screened for rare variants exclusive to either affected or unaffected subjects, and tested the combined association of variants across gene loci. Pathway analysis was performed and disease-related expression patterns were assessed. Marginal association with BPD was observed for numerous common and rare variants. We identified 345 genes with variants unique to BPD-affected preterm subjects, and 292 genes with variants unique to our unaffected preterm subjects. Of these unique variants, 28 (19 in the affected cohort and 9 in unaffected cohort) replicate a prior WES study of BPD-associated variants. Pathway analysis of sets of variants, informed by disease-related gene expression, implicated protein kinase A, MAPK and Neuregulin/epidermal growth factor receptor signaling.ConclusionsWe identified novel genes and associated pathways that may play an important role in susceptibility/resilience for the development of lung disease in preterm infants.

Acute Responses to Diuretic Therapy in Extremely Low Gestational Age Newborns: Results from the Prematurity and Respiratory Outcomes Program Cohort Study

To determine if daily respiratory status improved more in extremely low gestational age (GA) premature infants after diuretic exposure compared with those not exposed in modern neonatal intensive care units. The Prematurity and Respiratory Outcomes Program (PROP) was a multicenter observational cohort study of 835 extremely premature infants, GAs of 230/7-286/7 weeks, enrolled in the first week of life from 13 US tertiary neonatal intensive care units. We analyzed the PROP study daily medication and respiratory support records of infants ≤34 weeks postmenstrual age. We determined whether there was a temporal association between the administration of diuretics and an acute change in respiratory status in premature infants in the neonatal intensive care unit, using an ordered categorical ranking of respiratory status. Infants in the diuretic exposed group of PROP were of lower mean GA and lower mean birth weight (P < .0001). Compared with infants unexposed to diuretics, the probability (adjusted for infant characteristics including GA, birth weight, sex, and respiratory status before receiving diuretics) that the exposed infants were on a higher level of respiratory support was significantly greater (OR, >1) for each day after the initial day of diuretic exposure. Our analysis did not support the ability of diuretics to substantially improve the extremely premature infant's respiratory status. Further study of both safety and efficacy of diuretics in this setting are warranted. Clinicaltrials.gov: NCT01435187.

Pulmonary hypertension in the premature infant population: Analysis of echocardiographic findings and biomarkers.

Extremely low gestational age neonates (ELGANs) are at risk for pulmonary hypertension (PH). We hypothesized that PH, defined by echocardiogram at 36 weeks gestational age (GA), would associate with respiratory morbidity, increased oxidant stress, and reduced nitric oxide production. ELGANs in the Vanderbilt fraction of the Prematurity and Respiratory Outcomes Program (PROP) who had echocardiograms at 36 ± 1 weeks GA were studied. Echocardiogram features of PH were compared with clinical characteristics as well as markers of oxidant stress and components of the nitric oxide pathway. Biomarkers were obtained at enrollment (median day 3), 7, 14, and 28 days of life. Sixty of 172 infants had an echocardiogram at 36 weeks; 11 had evidence of PH. Infants did not differ by PH status in regards to demographics, respiratory morbidity, or oxidant stress. However, odds of more severe PH were significantly higher in infants with higher nitric oxide metabolites (NOx) at enrollment and with a lower citrulline level at day 7. Respiratory morbidity may not always associate with PH at 36 weeks among ELGANs. However, components of nitric oxide metabolism are potential biologic markers of PH in need of further study.

When does BPD begin?

This is the 50th anniversary of William Northway's description of bronchopulmonary dysplasia (BPD), a chronic pulmonary disease that he recognized as a common consequence of early respiratory failure in the preterm infant. Since that time, advances to reduce the incidence and severity of BPD have been surprisingly few, while the improved survival of extremely preterm babies has allowed the population of at-risk infants to grow substantially. In this month's volume of The Journal, Keller et al provide several new insights from the Prematurity Respiratory Outcomes Program, a large cohort of extremely preterm babies that has been exceptionally well phenotyped through the first year of life for respiratory outcomes. These data are likely to shape our thinking on how best to identify the highest risk infants, treat them, and think about their outcomes beyond the initial hospitalization. One striking finding in Keller et al's report is that a “perinatal model” of risk factors identified on the first day of life—such as smoking in pregnancy, intrauterine growth restriction, public insurance, black race, and others—predicts chronic respiratory morbidity at 1 year surprisingly well, and almost as well as BPD at 36 weeks' postmenstrual age. These findings also tell us we need to better understand the importance of environmental and other factors before and after the neonatal intensive care unit stay. Therapies in the neonatal intensive care unit are certainly important, but may not always be sufficient to overcome risk factors present before birth and in the home after discharge. Hopefully, the Prematurity Respiratory Outcomes Program data will be put to work to generate new calculators to identify infants at highest risk right as they are born and guide the development of “precision therapeutics” tailored to their specific risk factors. Article page 89 ▶ Bronchopulmonary Dysplasia and Perinatal Characteristics Predict 1-Year Respiratory Outcomes in Newborns Born at Extremely Low Gestational Age: A Prospective Cohort StudyThe Journal of PediatricsVol. 187PreviewTo assess the utility of clinical predictors of persistent respiratory morbidity in extremely low gestational age newborns (ELGANs). Full-Text PDF

Flow-based sorting of neonatal lymphocyte populations for transcriptomics analysis

RationaleEmerging data suggest an important role for T lymphocytes in the pathogenesis of chronic lung disease in preterm infants. Comprehensive assessment of the lymphocyte transcriptome may identify biomarkers and mechanisms of disease. MethodsSmall volume peripheral blood samples were collected from premature infants enrolled with consent in the Prematurity and Respiratory Outcomes Program (PROP), at the time of discharge from the hospital. Blood samples were collected at two sites and shipped to a central laboratory for processing. Peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Hypaque gradient centrifugation and separated into individual lymphocyte cell types by fluorescence-activated cell sorting. Gating strategies were optimized to ensure reproducible recovery of highly purified lymphocyte populations over a multi-year recruitment period. RNA was isolated from sorted cells and characterized by high-throughput sequencing (RNASeq). ResultsBlood volumes averaged 2.5ml, and sufficient PBMCs were collected from 165 of the 246 samples obtained (67%) from the 277 recruited subjects to complete sorting and RNASeq analysis on the resulting sorted cells. The number of total lymphocytes per ml of blood in the neonatal subjects was approximately 4 million/ml. Total lymphocyte frequencies recovered following sort varied widely among subjects, as did the frequency of individual lymphocyte and NK cell sub-populations. RNA yield from sorted cells varied according to cell type, but RNA of sufficient quantity and quality was recovered to enable RNASeq. SummaryOur results describe a validated procedure for the generation of genome-wide expression data from isolated lymphocyte sub-populations obtained from newborn blood.

Increasing F2-isoprostanes in the first month after birth predicts poor respiratory and neurodevelopmental outcomes in very preterm infants.

This study examined the association between increased early oxidative stress, measured by F2-isoprostanes (IsoPs), and respiratory morbidity at term equivalent age and neurological impairment at 12 months of corrected age (CA). Plasma samples were collected from 136 premature infants on days 14 and 28 after birth. All participants were infants born at ⩽28 weeks of gestational age enrolled into the Prematurity and Respiratory Outcomes Program (PROP) study. Respiratory morbidity was determined at 40 weeks of postmenstrual age (PMA) by the Respiratory Severity Index (RSI), a composite measure of oxygen and pressure support. Neurodevelopmental assessment was performed using the Developmental Assessment of Young Children (DAYC) at 12 months of CA. Multivariable logistic regression models estimated associations between IsoP change, RSI and DAYC scores. Mediation analysis was performed to determine the relationship between IsoPs and later outcomes. Developmental data were available for 121 patients (90% of enrolled) at 12 months. For each 50-unit increase in IsoPs, regression modeling predicted decreases in cognitive, communication and motor scores of -1.9, -1.2 and -2.4 points, respectively (P<0.001). IsoP increase was also associated with increased RSI at 40 weeks of PMA (odds ratio=1.23; P=0.01). RSI mediated 25% of the IsoP effect on DAYC motor scores (P=0.02) and had no significant impact on cognitive or communication scores. In the first month after birth, increases in plasma IsoPs identify preterm infants at risk for respiratory morbidity at term equivalent age and worse developmental outcomes at 12 months of CA. Poor neurodevelopment is largely independent of respiratory morbidity.

Challenges, priorities and novel therapies for hypoxemic respiratory failure and pulmonary hypertension in the neonate.

Future priorities for the management of hypoxemic respiratory failure (HRF) and pulmonary hypertension include primary prevention of neonatal lung diseases, 'precision medicine' and translating promising clinical and preclinical research into novel therapies. Promising areas of investigation include noninvasive ventilation strategies, emerging pulmonary vasodilators (for example, cinaciguat, intravenous bosentan, rho-kinase inhibitors, peroxisome proliferator-activated receptor-γ agonists) and hemodynamic support (arginine vasopressin). Research challenges include the optimal timing for primary prevention interventions and development of validated biomarkers that predict later disease or serve as surrogates for long-term respiratory outcomes. Differentiating respiratory disease endotypes using biomarkers and experimental therapies tailored to the underlying pathobiology are central to the concept of 'precision medicine' (that is, prevention and treatment strategies that take individual variability into account). The ideal biomarker should be expressed early in the neonatal course to offer an opportunity for effective and targeted interventions to modify outcomes. The feasibility of this approach will depend on the identification and validation of accurate, rapid and affordable point-of-care biomarker tests. Trials targeting patient-specific pathobiology may involve less risk than traditional randomized controlled trials that enroll all at-risk neonates. Such approaches would reduce trial costs, potentially with fewer negative trials and improved health outcomes. Initiatives such as the Prematurity and Respiratory Outcomes Program, supported by the National Heart, Lung, and Blood Institute, provide a framework to develop refined outcome measures and early biomarkers that will enhance our understanding of novel, mechanistic therapeutic targets that can be tested in clinical trials in neonates with HRF.

Management of hypoxemic respiratory failure and pulmonary hypertension in preterm infants.

While diagnoses of hypoxemic respiratory failure (HRF) and pulmonary hypertension (PH) in preterm infants may be based on criteria similar to those in term infants, management approaches often differ. In preterm infants, HRF can be classified as 'early' or 'late' based on an arbitrary threshold of 28 postnatal days. Among preterm infants with late HRF, the pulmonary vascular abnormalities associated with bronchopulmonary dysplasia (BPD) represent a therapeutic challenge for clinicians. Surfactant, inhaled nitric oxide (iNO), sildenafil, prostacyclin and endothelin receptor blockers have been used to manage infants with both early and late HRF. However, evidence is lacking for most therapies currently in use. Chronic oral sildenafil therapy for BPD-associated PH has demonstrated some preliminary efficacy. A favorable response to iNO has been documented in some preterm infants with early PH following premature prolonged rupture of membranes and oligohydramnios. Management is complicated by a lack of clear demarcation between interventions designed to manage respiratory distress syndrome, prevent BPD and treat HRF. Heterogeneity in clinical phenotype, pathobiology and genomic underpinnings of BPD pose challenges for evidence-based management recommendations. Greater insight into the spectrum of disease phenotypes represented by BPD can optimize existing therapies and promote development of new treatments. In addition, better understanding of an individual's phenotype, genotype and biomarkers may suggest targeted personalized interventions. Initiatives such as the Prematurity and Respiratory Outcomes Program provide a framework to address these challenges using genetic, environmental, physiological and clinical data as well as large repositories of patient samples.