Nicolas Porta

Differential Patterns of 27 Cord Blood Immune Biomarkers Across Gestational Age

OBJECTIVES. Inflammation has been associated with preterm delivery and adverse neonatal outcomes such as cerebral palsy and chronic lung disease. However, no study to date has simultaneously examined a wide range of inflammatory mediators and their relationship to gestational age. We sought to describe the distribution of immune biomarkers in cord blood across gestational age and to investigate the association between biomarker level patterns and preterm birth. PATIENTS AND METHODS. As part of a large-scale molecular epidemiological study of preterm birth conducted at Boston Medical Center, this study analyzed both clinical and biomarker data from 927 births. Twenty-seven biomarkers were simultaneously quantified by immunoassay. The associations between the quartiles of 27 biomarkers and 3 gestational groups (≤32, 33–36, and ≥37 weeks) were analyzed. Biomarkers found to be significant were further analyzed for dose-response correlation with preterm birth by logistic regression, adjusted for pertinent demographic and clinical factors. RESULTS. The 27 biomarkers could be classified into 1 of 3 groups: (1) biomarkers increased in preterm birth (interleukin [IL]-2, IL-4, IL-5, IL-8, IL-10, monocyte chemoattractant protein 1, macrophage inflammatory protein [MIP]-1α, MIP-1β, soluble IL-6 receptor α, tumor necrosis factor α, soluble tumor necrosis factor receptor I, and TREM-1 [triggering receptor expressed on myeloid cells 1]); (2) biomarkers decreased in preterm birth (brain-derived neurotrophic factor, IL-1β, IL-18, matrix metalloproteinase 9, and neurotrophin 3); and (3) biomarkers not associated with preterm birth (IL-6, IL-12, IL-17, granulocyte/macrophage colony-stimulating factor, interferon γ, macrophage migration inhibitory factor, neurotrophin 4, RANTES [regulated on activation, normal T-cell expressed and secreted], transforming growth factor β, and tumor necrosis factor β). CONCLUSIONS. Biomarkers have different directions of association with prematurity; for significant biomarkers, the strength of association increases with biomarker concentration. Our results provide important information that could be used to guide additional studies aimed at determining mechanisms that contribute to preterm birth.

Fetal growth restriction and pulmonary hypertension in premature infants with bronchopulmonary dysplasia

Objective:To identify the association between birth weight (BW)-for-gestational age (GA) and pulmonary hypertension (PHTN) at 36 weeks in infants with moderate–severe bronchopulmonary dysplasia (BPD).Study Design:In this retrospective cohort study, we followed 138 premature infants (⩽28 weeks) with moderate and severe BPD (National Institutes of Health consensus definition) born at Prentice Women’s Hospital between 2005 and 2009. BW percentiles were calculated using the Fenton growth curve for premature infants. PHTN was determined using a standardized algorithm of echocardiogram review at 36 weeks. Logistic regression was used to evaluate the associations between BW percentile subgroups and PHTN, taking into account antenatal and neonatal factors that were related to PHTN.Result:PHTN was associated with small BW-for-GA, ranging from thresholds of <10th to <25th percentile (P<0.001). These associations remained significant when comparing BW <25th percentile to the reference group (50 to 89th percentile); after adjustment for GA, gender, multiple gestation, race/ethnicity (odds ratio (OR)=4.2; 95% confidence interval (CI)=1.5, 12.1); and after further adjustment for maternal vascular disease, intrauterine infection, oligohydramnios and relevant postnatal factors (OR=5.7; 95% CI=1.5, 21.2). Longitudinal follow-up of this cohort showed a trend toward higher morbidity and death among PHTN infants with BW <25th percentile.Conclusion:BW-for-GA is an important predictor of PHTN in premature infants with moderate–severe BPD. Our findings contribute to the growing evidence supporting fetal mechanisms of later onset pulmonary vascular disease.

Pulmonary Vasodilator Therapy in the NICU: : Inhaled Nitric Oxide, Sildenafil, and Other Pulmonary Vasodilating Agents

The perinatal transition from fetal to extrauterine life requires a dramatic change in the circulatory pattern as the organ of gas exchange switches from the placenta to the lungs. Pulmonary hypertension can occur during early newborn life, and present as early respiratory failure or as a complication of more chronic diseases, such as bronchopulmonary dysplasia. The most effective pharmacotherapeutic strategies for infants with persistent pulmonary hypertension of the newborn are directed at selective reduction of pulmonary vascular resistance. This article discusses currently available therapies for pulmonary hypertension, their biologic rationales, and evidence for their clinical effectiveness.

Milrinone enhances relaxation to prostacyclin and iloprost in pulmonary arteries isolated from lambs with persistent pulmonary hypertension of the newborn

Prostacyclin is a pulmonary vasodilator and is produced by prostacyclin synthase and stimulates adenylate cyclase (AC) via the prostacyclin receptor (IP) to produce cAMP. Forskolin is a direct stimulant of AC. Phosphodiesterase 3 hydrolyzes cAMP and is inhibited by milrinone. Objective: To characterize the prostacyclin-AC-cAMP pathway in the ovine ductal ligation model of persistent pulmonary hypertension of the newborn (PPHN). Setting: University-based laboratory animal facility. Subjects: Lambs delivered to time-dated pregnant ewes. Interventions: Fifth generation pulmonary arteries (PA) and lung parenchyma were isolated from control fetal lambs (n = 8) and fetal lambs with PPHN induced by antenatal ductal ligation (n = 9). We studied relaxation responses to various agonists (milrinone, forskolin, prostacyclin, and iloprost, a prostacyclin analog) that increase cAMP in PA after half-maximal constriction with norepinephrine and pretreatment with propranolol ± indomethacin. Lung protein levels of prostacyclin synthase, IP, AC2, and phosphodiesterase 3A were analyzed by Western blot and cAMP by enzyme-linked immunoassay. Main Results: Milrinone relaxed control and PPHN PA and pretreatment with indomethacin significantly impaired this response. Relaxation to milrinone, prostacyclin, and iloprost were significantly impaired in PA from PPHN lambs. Pretreatment with milrinone markedly enhanced relaxation to prostacyclin and iloprost in PPHN PA, similar to relaxation in control PA. Relaxation to forskolin was similar in control and PPHN PAs indicating normal AC activity. Protein levels of prostacyclin synthase and IP were decreased in PPHN lungs compared with control, but AC2, cAMP, and phosphodiesterase 3A remained unchanged. Conclusions: Prostacyclin and iloprost are dilators of PAs from PPHN lambs and their effect is enhanced by milrinone. This combination therapy may be an effective strategy in the management of patients with PPHN.

Placental pathologic changes of maternal vascular underperfusion in bronchopulmonary dysplasia and pulmonary hypertension

INTRODUCTION Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of infancy, and BPD-associated pulmonary hypertension (PH) is a serious complication that can negatively impact later childhood health. There is growing evidence that lung injury leading to BPD and PH is due to chronic fetal hypoxia-ischemia. The purpose of this study was to investigate whether placental pathologic changes of maternal vascular underperfusion (MVU) are associated with BPD, and further increased with PH. METHODS We conducted a 5-year retrospective cohort study of premature infants born ≤28 weeks. BPD was defined as persistent oxygen requirement at 36 weeks corrected gestational age. PH was identified using a standardized algorithm of echocardiogram review. Archived placental slides underwent standardized masked histopathologic review. Logistic regression modeling was performed, taking into account important maternal and infant covariates. RESULTS Among 283 births, 121 had MVU, of which 67 (55%) developed BPD, and 24 (20%) had PH. Among the common neonatal complications of extreme prematurity, BPD was the only outcome that was increased with MVU (P < 0.001). After adjustment for birth weight, fetal growth restriction, preeclampsia and other factors, infants with MVU were more likely to develop BPD (adjusted odds ratio = 2.6; 95% confidence interval = 1.4, 4.8). Certain MVU sublesions (fibrinoid necrosis/acute atherosis and distal villous hypoplasia/small terminal villi) were increased with PH (P < 0.001). DISCUSSION Placental MVU may identify BPD infants who were exposed to intrauterine hypoxia-ischemia, which increases their risk for development of PH disease. CONCLUSIONS Our findings have important implications for providing earlier and more effective therapies for BPD.

Medical and Financial Impact of a Neonatal Extracorporeal Membrane Oxygenation Referral Center in the Nitric Oxide Era

OBJECTIVES. The primary objective of this study was to determine whether widespread use of nitric oxide after Food and Drug Administration approval decreased admissions to a neonatal referral center for extracorporeal membrane oxygenation evaluation. We also sought to determine whether antecedent treatment delayed eventual transfer, resulting in sicker patients, increased mortality, increased extracorporeal membrane oxygenation application, and higher direct costs of care. METHODS. This was a retrospective cohort study of all of the patients transferred to a neonatal referral center for extracorporeal membrane oxygenation evaluation before (1995–1999) and after (2000–2005) Food and Drug Administration approval of nitric oxide. Patients were divided into “congenital diaphragmatic hernia” and “persistent pulmonary hypertension” (all other diagnoses) for additional analysis. RESULTS. Admission rates for extracorporeal membrane oxygenation evaluation decreased in the nitric oxide era, and eventual transfer was not delayed. Persistent pulmonary hypertension patients had improved oxygen indexes, a trend toward decreased mortality, decreased extracorporeal membrane oxygenation use, and decreased direct costs. Congenital diaphragmatic hernia patients had unchanged physiologic measurements, mortality, and extracorporeal membrane oxygenation use with increased direct costs of care. As a whole, outcomes for patients transferred for extracorporeal membrane oxygenation evaluation improved, whereas direct costs were unchanged. CONCLUSIONS. Persistent pulmonary hypertension patients had improved outcomes with decreased costs, whereas congenital diaphragmatic hernia patients had unchanged outcomes with increased costs. Overall, patients admitted to this NICU because of the presence of extracorporeal membrane oxygenation services had improved outcomes without increased costs in the nitric oxide era.

Use of inhaled nitric oxide in the preterm infant

Purpose of review Inhaled nitric oxide is established therapy for term infants with hypoxemic respiratory failure. Laboratory studies demonstrate that inhaled nitric oxide improves lung function and morphology in animal models of bronchopulmonary dysplasia, creating a rationale for clinical studies in premature infants. Four large multicenter randomized trials have now completed enrollment, and one trial has reported neurodevelopmental outcomes at 18–22 months. The purpose of this review is to summarize the results of the most recent preclinical studies and clinical trials. Recent findings In 2006, short-term outcomes from two large multicenter randomized trials were published. These studies differed in their target population and study design. Early use of inhaled nitric oxide was associated with a decrease in brain injury, and decreased chronic lung disease in infants over 1000 g. Inhaled nitric oxide use in older infants (7–21 days) was associated with decreased chronic lung disease, particularly if started early. Summary Neurodevelopmental outcomes after discharge are still needed from three large multicenter randomized trials. These results will help confirm the long-term implications of the benefits reported in the two most recent trials.

Predicting death or extended length of stay in infants with congenital diaphragmatic hernia

Objective:To predict mortality or length of stay (LOS) >109 days (90th percentile) among infants with congenital diaphragmatic hernia (CDH).Study Design:We conducted a retrospective analysis using the Childrens Hospital Neonatal Database during 2010 to 2014. Infants born >34 weeks gestation with CDH admitted at 22 participating regional neonatal intensive care units were included; patients who were repaired or were at home before admission were excluded. The primary outcome was death before discharge or LOS >109 days. Factors associated with this outcome were used to develop a multivariable equation using 80% of the cohort. Validation was performed in the remaining 20% of infants.Results:The median gestation and age at referral in this cohort (n=677) were 38 weeks and 6 h, respectively. The primary outcome occurred in 242 (35.7%) infants, and was distributed between mortality (n=180, 27%) and LOS >109 days (n=66, 10%). Regression analyses showed that small for gestational age (odds ratio (OR) 2.5, P=0.008), presence of major birth anomalies (OR 5.9, P<0.0001), 5- min Apgar score ⩽3 (OR 7.0, P=0.0002), gradient of acidosis at the time of referral (P<0.001), the receipt of extracorporeal support (OR 8.4, P<0.0001) and bloodstream infections (OR 2.2, P=0.004) were independently associated with death or LOS >109 days. This model performed well in the validation cohort (area under curve (AUC)=0.856, goodness-of-fit (GF) χ2, P=0.16) and acted similarly even after omitting extracorporeal support (AUC=0.82, GF χ2, P=0.05).Conclusions:Six variables predicted death or LOS ⩾109 days in this large, contemporary cohort with CDH. These results can assist in risk adjustment for comparative benchmarking and for counseling affected families.

Cord Blood Biomarkers of Placental Maternal Vascular Underperfusion Predict Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension

Objective To assess whether cord blood biomarkers associated with placental maternal vascular underperfusion (MVU) are predictive of bronchopulmonary dysplasia‐associated pulmonary hypertension (BPD‐PH). Study design Premature infants enrolled in a longitudinal cohort study were randomly sampled from 4 gestational age strata (n = 190, range 23‐36 weeks). Fifteen factors from a human angiogenesis panel were measured in cord blood using multiplex immunoassay. Multivariate linear regression was used to compare biomarker levels according to placental histologic MVU, taking into account acute/chronic inflammation and fetal vascular pathology. Biomarkers associated with MVU were further evaluated in the subgroup of extremely low gestational age infants (gestational age ≤ 28 weeks; n = 48), and measured by enzyme‐linked immunoassay in an additional 39 infants to determine associations with BPD (defined using the National Institutes of Health workshop criteria) and PH (identified by echocardiogram at 36 weeks of gestation). Results Cord blood placental growth factor (PIGF), granulocyte‐colony stimulating factor (G‐CSF), and vascular endothelial growth factor‐A were decreased with MVU (P < .003), and decreased with BPD‐PH (P < .05). The findings were validated for PIGF and G‐CSF in 39 additional extremely low gestational age infants. In the combined group (n = 87), PIGF was decreased in infants with BPD‐PH (n = 21) versus controls without PH (median 3 pg/mL [IQR 2‐7] vs median 15 pg/mL [IQR 6‐30], respectively; P < .001). G‐CSF was similarly decreased with BPD‐PH (median, 55 pg/mL [IQR 38‐85] vs median 243 pg/mL [IQR 48‐1593], respectively; P = .001). Receiver operator curve analysis revealed that decreased PIGF and G‐CSF were predictive of BPD‐PH (area under the curve 0.83 and 0.76, respectively). Conclusions Cord blood angiogenic factors that are decreased with placental MVU may serve as predictors of BPD‐PH.

Inhaled NO in the experimental setting

Nitric oxide, a gas molecule, is a unique pharmaceutical agent that can be inhaled and thus delivered directly to the lung. More than a decade of intensive laboratory and clinical investigation has culminated in the current role for inhaled NO as the only selective pulmonary vasodilator for the treatment of persistent pulmonary hypertension of the newborn (PPHN). Not surprisingly, this potent and successful therapy continues to be studied intensively to better define its mechanism of action and role in PPHN treatment. In addition, there remains intense interest in possible new applications for newborns, as well as strategies that may enhance its efficacy. This review describes several areas of current research on amplification of NO signaling in the neonatal pulmonary vasculature, and reviews our current knowledge about the role of iNO in other conditions such as congenital diaphragmatic hernia and congenital heart disease. In addition, laboratory and clinical studies addressing a potential role for iNO as a therapeutic modality for the preterm infant are reviewed.