Respiratory consequences of prematurity: evolution of a diagnosis and development of a comprehensive approach

Interdisciplinary clinical bronchopulmonary dysplasia programs: development, evolution, and maturation

Multidisciplinary bronchopulmonary dysplasia (BPD) programs provide improved and consistent medical management, care of the developing infant, family support, and smoother transitions in care resulting in improved survival, pulmonary, and extra-pulmonary outcomes. This review summarizes the benefits of interdisciplinary BPD management, as well as strategies for initial programmatic development, program growth, and maintenance at centers across the United States factoring in institutional, provider, and parent reported goals that were derived from a consensus conference on BPD management.

Association of cord blood Ang-1 and sCD105 levels with bronchopulmonary dysplasia in preterm infants

BACKGROUND

To investigate the relationship between cord blood levels of Angiopoietin-1 (Ang-1) and S-endoglin (sCD105) and bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

Sixty-one preterm infants admitted to the neonatal intensive care unit of the study hospital between July 2021 and September 2022 were included. Cord blood was collected after the birth of premature infants. Ang-1 and sCD105 levels were quantified using the vascular endothelial growth factor enzyme-linked immunosorbent assay. Preterm infants were divided into BPD and non-BPD groups, and differences in Ang-1 and sCD105 levels between the two groups were compared. A binary logistic model was used to assess the association between low and high levels Ang-1 and BPD in preterm infants.

RESULTS

In the study, there were 20 preterm infants with BPD (32.8%) and 41 preterm infants with non-BPD (67.2%). Ang-1 concentration levels were lower in the BPD group than in the non-BPD group (7105.43 (5617.01-8523.00) pg/ml vs. 10488.03 (7946.19-15962.77) pg/ml, P = 0.027). However, the sCD105 concentration levels were not significantly different between the BPD and non-BPD groups (P = 0.246). A median Ang-1 concentration of 8800.40 pg/ml was calculated. Logistic regression analysis showed that after adjusting for gestational age, birth weight, and maternal prenatal steroid hormone application, the odds ratio (OR) was 8.577 for the risk of BPD in preterm infants with Ang-1 concentrations of ≤ 8800.40 pg/ml compared to those with Ang-1 concentrations of > 8800.40 pg/ml (OR: 8.577, 95% confidence interval: 1.265-58.155, P = 0.028).

CONCLUSION

Our study indicated that Ang-1 levels in the cord blood of preterm infants may be associated the risk of BPD. In the future, we will continue to conduct study with large samples.

Deficiency of Secreted Phosphoprotein 1 Alleviates Hyperoxia-induced Bronchopulmonary Dysplasia in Neonatal Mice

Bronchopulmonary dysplasia (BPD) is a common chronic lung disorder characterized by impaired proximal airway and bronchoalveolar development in premature births. Secreted phosphoprotein 1 (SPP1) is involved in lung development and lung injury events, while its role was not explored in BPD. For establishing the in vivo models of BPD, a mouse model of hyperoxia-induced lung injury was generated by exposing neonatal mice to hyperoxia for 7 days after birth. Alveolar myofibroblasts (AMYFs) were treated with hyperoxia to establish the in vitro models of BPD. Based on the scRNA-seq analysis of lungs of mice housed under normoxia or hyperoxia conditions, mouse macrophages and fibroblasts were main different cell clusters between the two groups, and differentially expressed genes in fibroblasts were screened. Further GO and KEGG enrichment analysis revealed that these differentially expressed genes were mainly enriched in the pathways related to cell proliferation, apoptosis as well as the PI3K-AKT and ERK/MAPK pathways. SPP1 was found up-regulated in the lung tissues of hyperoxia mice. We also demonstrated the up-regulation of SPP1 in the BPD patients, the mouse model of hyperoxia-induced lung injury, and hyperoxia-induced cells. SPP1 deficiency was revealed to reduce the hyperoxia-induced apoptosis, oxidative stress and inflammation and increase the viability of AMYFs. In the mouse model of hyperoxia induced lung injury, SPP1 deficiency was demonstrated to reverse the hyperoxia-induced alveolar growth disruption, oxidative stress and inflammation. Overall, SPP1 exacerbates BPD progression in vitro and in vivo by regulating oxidative stress and inflammatory response via the PI3K-AKT and ERK/MAPK pathways, which might provide novel therapeutic target for BPD therapy.

New insights into the natural history of bronchopulmonary dysplasia from proteomics and multiplexed immunohistochemistry

Bronchopulmonary dysplasia (BPD) is a disease of prematurity related to the arrest of normal lung development. The objective of this study was to better understand how proteome modulation and cell-type shifts are noted in BPD pathology. Pediatric human donors aged 1-3 yr were classified based on history of prematurity and histopathology consistent with "healed" BPD (hBPD, n = 3) and "established" BPD (eBPD, n = 3) compared with respective full-term born (n = 6) age-matched term controls. Proteins were quantified by tandem mass spectroscopy with selected Western blot validations. Multiplexed immunofluorescence (MxIF) microscopy was performed on lung sections to enumerate cell types. Protein abundances and MxIF cell frequencies were compared among groups using ANOVA. Cell type and ontology enrichment were performed using an in-house tool and/or EnrichR. Proteomics detected 5,746 unique proteins, 186 upregulated and 534 downregulated, in eBPD versus control with fewer proteins differentially abundant in hBPD as compared with age-matched term controls. Cell-type enrichment suggested a loss of alveolar type I, alveolar type II, endothelial/capillary, and lymphatics, and an increase in smooth muscle and fibroblasts consistent with MxIF. Histochemistry and Western analysis also supported predictions of upregulated ferroptosis in eBPD versus control. Finally, several extracellular matrix components mapping to angiogenesis signaling pathways were altered in eBPD. Despite clear parsing by protein abundance, comparative MxIF analysis confirms phenotypic variability in BPD. This work provides the first demonstration of tandem mass spectrometry and multiplexed molecular analysis of human lung tissue for critical elucidation of BPD trajectory-defining factors into early childhood.NEW & NOTEWORTHY We provide new insights into the natural history of bronchopulmonary dysplasia in donor human lungs after the neonatal intensive care unit hospitalization. This study provides new insights into how the proteome and histopathology of BPD changes in early childhood, uncovering novel pathways for future study.

Umbilical cord blood exosomes from very preterm infants with bronchopulmonary dysplasia aggravate lung injury in mice

Bronchopulmonary dysplasia (BPD) is characterized by abnormal development of the blood vessels and alveoli in lungs, which largely occurs in premature infants. Exosomes (EXO) from very preterm infants (VPI) with BPD (BPD-EXO) impair angiogenic activities of human umbilical vein endothelial cells (HUVECs) via EXO-miRNAs cargo. This study aimed to determine whether and how BPD-EXO affect the development of BPD in a mouse model. We showed that treating BPD mice with BPD-EXO chronically and irreversibly aggravated lung injury. BPD-EXO up-regulated 139 and down-regulated 735 genes in the mouse lung tissue. These differentially expressed genes were enriched to the MAPK pathway (e.g., Fgf9 and Cacna2d3), which is critical to angiogenesis and vascular remodeling. BPD-EXO suppressed expression of Fgf9 and Cacna2d3 in HUVECs and inhibited migration, tube formation, and increased cell apoptosis in HUVECs. These data demonstrate that BPD-EXO aggravate lung injury in BPD mice and impair lung angiogenesis, plausibly leading to adverse outcomes of VPI with BPD. These data also suggest that BPD-EXO could serve as promising targets for predicting and treating BPD.

Environmental influences on child health outcomes: cohorts of individuals born very preterm

The National Institutes of Health's Environmental influences on Child Health Outcomes (ECHO) Program was designed to address solution-oriented research questions about the links between children's early life environment and their risks of pre-, peri-, and post-natal complications, asthma, obesity, neurodevelopmental disorders, and positive health. Children born very preterm are at increased risk for many of the outcomes on which ECHO focuses, but the contributions of environmental factors to this risk are not well characterized. Three ECHO cohorts consist almost exclusively of individuals born very preterm. Data provided to ECHO from cohorts can be used to address hypotheses about (1) differential risks of chronic health and developmental conditions between individuals born very preterm and those born at term; (2) health disparities across social determinants of health; and (3) mechanisms linking early-life exposures and later-life outcomes among individuals born very preterm. IMPACT: The National Institutes of Health's Environmental Influences on Child Health Outcomes Program is conducting solution-oriented research on the links between children's environment and health. Three ECHO cohorts comprise study participants born very preterm; these cohorts have enrolled, to date, 1751 individuals born in 14 states in the U.S. in between April 2002 and March 2020. Extensive data are available on early-life environmental exposures and child outcomes related to neurodevelopment, asthma, obesity, and positive health. Data from ECHO preterm cohorts can be used to address questions about the combined effects of preterm birth and environmental exposures on child health outcomes.

Preterm rat survival is enhanced by gestational environmental enrichment

Throughout the last decade, the estimated global human preterm birth rate was 10.6 %, with higher rates in Asia, South America, and Africa. Preterm individuals, even in adulthood, are more likely to develop cardiorespiratory, renal, and metabolic disorders. On the other hand, when experimental animals are housed in an enriched environment during gestation, the development of the progeny in utero is accelerated, compared to standard housing conditions. By terminating gestation one and a half days before parturition, we investigated whether environmental enrichment restricted to gestation may have an impact on progeny survival. Our results demonstrate that the gestational enriched environment tripled the rat´s offspring survival, which was associated with decreased expression of anxiety-like behaviors in the pregnant mother. Sex of the offspring was not a factor in determining survival. We discuss the effect of increased secretion of various trophic factors and hormones induced by the enriched environment on progeny survival.

Placing Ureaplasma within the Context of Bronchopulmonary Dysplasia Endotypes and Phenotypes

Different pathophysiological pathways (endotypes), leading to very preterm birth may result in distinct clinical phenotypes of bronchopulmonary dysplasia (BPD). Ureaplasma is a unique player in the pathogenesis of BPD. The interaction between factors inherent to Ureaplasma (virulence, bacterial load, duration of exposure), and to the host (immune response, infection clearance, degree of prematurity, respiratory support, concomitant infections) may contribute to BPD development in a variable manner. The data reviewed herein support the hypothesis that Ureaplasma, as a representative of the infectious/inflammatory endotype, may produce pulmonary damage predominantly in parenchyma, interstitium, and small airways. In contrast, Ureaplasma may have a very limited role in the pathogenesis of the vascular phenotype of BPD. In addition, if Ureaplasma is a key factor in BPD pathogenesis, its eradication by macrolides should prevent BPD. However, various meta-analyses do not show consistent evidence that this is the case. The limitations of current definitions and classifications of BPD, based on respiratory support needs instead of pathophysiology and phenotypes, may explain this and other failures in strategies aimed to prevent BPD. The precise mechanisms through which Ureaplasma infection leads to altered lung development and how these pathways can result in different BPD phenotypes warrant further investigation.

La habilidad lingüística en prematuros extremos en edad escolar

En España, el número de nacimientos prematuros es de 30.000, siendo una de las principales causas de mortalidad perinatal. En los últimos años, gracias a los avances médicos, la tasa de supervivencia de esta población se ha visto incrementada, lo cual ha evidenciado la aparición de nuevas morbilidades y comorbilidades que pueden interferir en su proceso de aprendizaje. Este estudio, de carácter cualitativo y longitudinal, cuenta con un muestreo no probabilístico por conveniencia. Su objeto es analizar la habilidad lingüística de cuatro menores grandes prematuros, con una edad gestacional al nacimiento igual o inferior a las 28 semanas, que actualmente cursan 4º de Educación Primaria, para detectar posibles dificultades en la adquisición y en el uso del lenguaje. Se les administró la Batería del Lenguaje Objetiva y Criterial Revisado (BLOC-SR) a la edad cronológica de 8 y 10 años. Los resultados sugieren que existen dificultades en la adquisición de los componentes del lenguaje: en el morfológico, por ejemplo, aparece en el uso de las formas verbales, en los sustantivos derivados, etc.; en el sintáctico, en las oraciones subordinadas de causa y condición, etc.; en el semántico se evidencian en los locativos, etc., y en el pragmático, en la realización de preguntas. A modo de conclusión, los menores prematuros extremos, debido a su condición de vulnerabilidad biológica al quedar interrumpida la maduración cerebral por su nacimiento temprano, necesitan potenciar las destrezas lingüísticas, entre las que destaca la conciencia semántica, siendo necesario diseñar propuestas de intervención para el ámbito escolar.

Lung ultrasound completely replaced chest X-ray for diagnosing neonatal lung diseases: a 3-year clinical practice report from a neonatal intensive care unit in China

BACKGROUND AND OBJECTIVE

Lung ultrasound (LUS) has been widely used in the diagnosis and differential diagnosis of neonatal lung diseases (NLDs), but whether it can replace the routine use of chest X-ray (CXR) in neonatal intensive care units (NICUs) remains controversial. This paper summarizes the clinical practice of our neonatal intensive care unit (NICU) during the past three years to explore the feasibility and necessity of using LUS instead of CXR to diagnose NLDs in the NICU setting.

METHODS

The clinical data and LUS examination results from 1,381 newborn infants with respiratory difficulty who were hospitalized in our NICU from March 2017 to February 2020 were retrospectively collected to analyze the types of lung diseases diagnosed and the reliability of LUS for diagnosing NLDs.

RESULTS

(1) During this period, 1381 newborn infants with dyspnea were admitted to our NICU, accounting for 41.2% of all hospitalized children. (2) Among the 1381 infants, 17 patients with respiratory distress were confirmed as having severe heart disease by echocardiography, while the remaining 1364 patients had different kinds of lung diseases: pneumonia (697 patients, 51.1%), respiratory distress syndrome (251 patients, 17.4%), transient tachypnea of the newborn (197 patients, 13.3%), atelectasis (89 patients, 5.6%), pneumothorax (46 patients, 3.2%), pulmonary hemorrhage (69 patients, 4.5%), severe pleural effusion (18 patients, 1.32%), congenital pulmonary sequestration (3 patients, 0.22%), bullae of the lung (2 patients, 0.15%), and congenital cystic adenomatoid malformation (2 patients). (5) Among the 1381 infants, 217 received CXR examination before admission, which resulted in misdiagnosis in 45 patients (20.7%) and missed diagnosis in 12 patients (5.5%); the missed diagnosis and misdiagnosis rate was 26.3%.

CONCLUSION

Our 3-year clinical practice experience indicated that LUS could completely replace chest X-ray for the diagnosis and differential diagnosis of NLDs in the NICU. Compared with X-ray, LUS had higher accuracy and reliability in diagnosing NLDs.

Endotypes of Prematurity and Phenotypes of Bronchopulmonary Dysplasia: Toward Personalized Neonatology

Bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity, is increasingly recognized as the consequence of a pathological reparative response of the developing lung to both antenatal and postnatal injury. According to this view, the pathogenesis of BPD is multifactorial and heterogeneous with different patterns of antenatal stress (endotypes) that combine with varying postnatal insults and might distinctively damage the development of airways, lung parenchyma, interstitium, lymphatic system, and pulmonary vasculature. This results in different clinical phenotypes of BPD. There is no clear consensus on which are the endotypes of prematurity but the combination of clinical information with placental and bacteriological data enables the identification of two main pathways leading to birth before 32 weeks of gestation: (1) infection/inflammation and (2) dysfunctional placentation. Regarding BPD phenotypes, the following have been proposed: parenchymal, peripheral airway, central airway, interstitial, congestive, vascular, and mixed phenotype. In line with the approach of personalized medicine, endotyping prematurity and phenotyping BPD will facilitate the design of more targeted therapeutic and prognostic approaches.

Weaning Strategy of Diuretics in Outpatient Preterm Infants with Bronchopulmonary Dysplasia: A National Survey

OBJECTIVE

Long-term diuretic treatment in patients with bronchopulmonary dysplasia (BPD) is common despite lack of data that support its use. We aimed to characterize the commonly used diuretics weaning strategies for outpatient clinically stable preterm infants with BPD.

STUDY DESIGN

We conducted a cross-sectional web-based survey among all pediatric pulmonologists and neonatologists in Israel. Questionnaire included data regarding practitioners' different diuretics-weaning practice in this population.

RESULTS

The response rate for pulmonologists and neonatologists were 35/50 (70%) and 36/120 (30%), respectively. When both oxygen and diuretics are used, 59% wean oxygen first and 32% wean diuretics first. If patients are solely on diuretics, 27% discontinue instantly, 34% decrease the dosage gradually, and 34% outgrow the discharge dosage. Significantly more pulmonologists decrease the dosage gradually, while more neonatologists discontinue at once (p < 0.001). Most participants (94%) reported being unsatisfied with the existing data and guidelines regarding these issues.

CONCLUSION

Our results showed a wide range of practice patterns in the weaning strategy of diuretics in outpatient preterm infants with BPD. Pulmonologists and neonatologists differ significantly in their weaning strategy. A prospective larger controlled study to explore the outcome of gradual tapering versus discontinuation without weaning is warranted.

KEY POINTS

· Diuretic treatment in patients with BPD is common despite lack of data that support its use.. · We demonstrated a wide range of practice patterns in the weaning strategy of diuretics in outpatients' BPDs.. · Pulmonologists and neonatologists differ significantly in their weaning strategy.. · Most participants are unsatisfied with the existing data and guidelines regarding these issues..

Hyperoxia Induced Bronchopulmonary Dysplasia-Like Inflammation via miR34a-TNIP2-IL-1β Pathway

Lung injury induced by oxygen is a key contributor to the pathogenesis of preterm infant bronchopulmonary dysplasia (BPD). To date, there are comprehensive therapeutic strategy for this disease, but the underlying mechanism is still in progress. By using lentivirus, we constructed microRNA34a (miR34a)-overexpressing or knockdown A549 cell lines, and exposure to hyperoxia to mimic oxygen induce lung injury. In this study, we investigated 4 proinflammatory cytokines, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), angiopoietin-1 (Ang-1), and Cyclooxygenase-2 (COX-2) in the secreted sputum of infants who received mechanical ventilation, and found that IL-1β was substantially elevated in the first week after oxygen therapy and with no significant decrease until the fourth week, while TNF-α, Ang-1, and COX-2 were increased in the first week but decreased quickly in the following weeks. In addition, in vitro assay revealed that hyperoxia significantly increased the expression of miR-34a, which positively regulated the proinflammatory cytokine IL-1β in a time- and concentration-dependent manner in A549 cells. Overexpressing or knockdown miR34 would exacerbate or inhibit production of IL-1β and its upstream NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome signaling pathway. Mechanically, it's found that TNFAIP3 interacting protein 2 (TNIP2), an inhibitor of nuclear factor κB (NF-κB), is a direct target of miR34a, negatively regulated activation of NLRP3 inflammasome and the production of IL-1β. Overexpressing TNIP2 ameliorated hyperoxia-induced production of IL-1β and cell apoptosis. Our findings suggest that TNIP2 may be a potential clinical marker in the diagnosis of BPD.

The value of plasma insulin-like growth factor 1 and interleukin-18 in the diagnosis of bronchopulmonary dysplasia in premature infants

OBJECTIVE

To explore the diagnostic value of IGF-1 and IL-18 in premature infants with BPD.

METHODS

Through a prospective observational study, the serum samples of infants in the BPD group and the non-BPD group were collected at different targeted time points, and the serum IGF-1 and IL-18 concentrations were dynamically monitored by ELISA. The Student t-test and one-way analysis of variance were adopted to analyze data, and the receiver operating characteristic (ROC) curve was used to test the diagnostic value.

RESULT

A total of 90 VLBW premature infants admitted to NICU between January 2020 and 2021 were finally included. Compared with the non-BPD group, infants diagnosed with BPD had a significantly lower serum concentration of IGF-1 (P < 0.05) but a higher level of IL-18 (P < 0.05) on days 1, 7, 14, and 28 after birth. With the ROC curve analysis, the serum concentration IGF-1 on day 14 and IL-18 on day 28 reported high sensitivity and specificity to predict the risk of BPD (IGF-1: sensitivity: 89.29%, specificity: 77.78%, AUC: 0.8710; IL-18: sensitivity: 53.57%, specificity: 83.33%, AUC: 0.7887). And more substantial predictive power was found in combined analysis of IGF-1 and serum IL-18 on day 14: the sensitivity was 91.07% and the specificity was 83.33%, with the AUC of 0.9142.

CONCLUSION

IGF-1 and IL-18 might be closely involved in the occurrence and development of BPD. The serum concentration of IGF-1 combined with IL-18 could be potentially sensitive markers for the early diagnosis and severity of BPD.

Randomized trial of azithromycin to eradicate Ureaplasma respiratory colonization in preterm infants: 2-year outcomes

BACKGROUND

To assess the potential impact of azithromycin treatment in the first week following birth on 2-year outcomes in preterm infants with and without Ureaplasma respiratory colonization who participated in a double-blind, placebo-controlled randomized controlled trial.

METHODS

Respiratory morbidity was assessed at NICU discharge and at 6, 12, and 22-26 months corrected age using pulmonary questionnaires. Comprehensive neurodevelopmental assessments were completed between 22 and 26 months corrected age. The primary and secondary composite outcomes were death or severe respiratory morbidity and death or moderate-severe neurodevelopmental impairment, respectively, at 22-26 months corrected age.

RESULTS

One hundred and twenty-one randomized participants (azithromycin, N = 60; placebo, N = 61) were included in the intent-to-treat analysis. There were no significant differences in death or serious respiratory morbidity (34.8 vs 30.4%, p = 0.67) or death or moderate-severe neurodevelopmental impairment (47 vs 33%, p = 0.11) between the azithromycin and placebo groups. Among all trial participants, tracheal aspirate Ureaplasma-positive infants experienced a higher frequency of death or serious respiratory morbidity at 22-26 months corrected age (58%) than tracheal aspirate Ureaplasma-negative infants (34%) or non-intubated infants (21%) (p = 0.028).

CONCLUSIONS

We did not observe strong evidence of a difference in long-term pulmonary and neurodevelopment outcomes in preterm infants treated with azithromycin in the first week of life compared to placebo.

IMPACT

No strong evidence of a difference in long-term pulmonary and neurodevelopment outcomes was identified at 22-26 months corrected age in infants treated with azithromycin in the first week of life compared to placebo. The RCT is the first study of 2-year pulmonary and neurodevelopmental outcomes of azithromycin treatment in ELGANs. Provides evidence that ELGANs with lower respiratory tract Ureaplasma have the most frequent serious respiratory morbidity in the first 2 years of life, suggesting that a Phase III trial of azithromycin to prevent BPD targeting this population is warranted.

Differences in clinical and laboratory biomarkers for short and long-term respiratory outcomes in preterm neonates

BACKGROUND

Pulmonary outcome of premature neonates has focused more on short-term than long-term respiratory morbidities.

OBJECTIVE

Describe risk factors/biomarkers associated with short-term (bronchopulmonary dysplasia [BPD]) (supplemental oxygen use at 36 weeks postmenstrual age [PMA]) and longer-term (chronic respiratory morbidity [CRM]) (respiratory related symptoms, medications, medical/emergency visits, hospitalizations at 6-12 months corrected gestational age [CGA]) respiratory outcomes in a longitudinal cohort.

DESIGN/METHODS

Neonates born at 24-29-week gestation were prospectively followed to 6-12-month CGA. Associations between clinical and laboratory risk factors/biomarkers of BPD and CRM were explored.

RESULTS

Of 86 subjects, 94% survived. Outcomes were available for 89% at 36-week PMA (BPD present in 42% of infants) and 72% at 6-12-month CGA (CRM present in 47% of infants). For the 54 infants with known outcomes for both BPD and CRM, diagnoses were discordant in 41%. BPD was associated with lower birthweight and birthweight Z-score for GA, lower Apgar scores, more surfactant doses, higher SNAPPE-II scores, highest Day 1 inspired oxygen concentration, Day 7 oxygen use, prolonged ventilatory support, bacteremia, necrotizing enterocolitis, and treated patent ductus arteriosus. CRM was associated with lower Apgar scores, Day 7 oxygen use and higher urine vascular endothelial growth factor. Patterns of plasma and urine lipid oxidation products differed in the two outcomes.

CONCLUSION

In this hypothesis generating and exploratory study, BPD and CRM were associated with different risk factors/biomarker patterns. Concordance between these two outcomes was weak. Strategies for reducing CRM should be studied in cohorts identified by appropriate early risk factors/biomarkers.

Murine Neonatal Oxidant Lung Injury: NRF2-Dependent Predisposition to Adulthood Respiratory Viral Infection and Protection by Maternal Antioxidant

NRF2 protects against oxidant-associated airway disorders via cytoprotective gene induction. To examine if NRF2 is an important determinant of respiratory syncytial virus (RSV) susceptibility after neonate lung injury, Nrf2-deficient (Nrf2^−/−) and wild-type (Nrf2^+/+) mice neonatally exposed to hyperoxia were infected with RSV. To investigate the prenatal antioxidant effect on neonatal oxidative lung injury, time-pregnant Nrf2^−/− and Nrf2^+/+ mice were given an oral NRF2 agonist (sulforaphane) on embryonic days 11.5–17.5, and offspring were exposed to hyperoxia. Bronchoalveolar lavage and histopathologic analyses determined lung injury. cDNA microarray analyses were performed on placenta and neonatal lungs. RSV-induced pulmonary inflammation, injury, oxidation, and virus load were heightened in hyperoxia-exposed mice, and injury was more severe in hyperoxia-susceptible Nrf2^−/− mice than in Nrf2^+/+ mice. Maternal sulforaphane significantly alleviated hyperoxic lung injury in both neonate genotypes with more marked attenuation of severe neutrophilia, edema, oxidation, and alveolarization arrest in Nrf2^−/− mice. Prenatal sulforaphane altered different genes with similar defensive functions (e.g., inhibition of cell/perinatal death and inflammation, potentiation of angiogenesis/organ development) in both strains, indicating compensatory transcriptome changes in Nrf2^−/− mice. Conclusively, oxidative injury in underdeveloped lungs NRF2-dependently predisposed RSV susceptibility. In utero sulforaphane intervention suggested NRF2-dependent and -independent pulmonary protection mechanisms against early-life oxidant injury.

Low Dose Hyperoxia Primes Airways for Fibrosis in Mice after Influenza A Infection

It is well known that supplemental oxygen used to treat preterm infants in respiratory distress is associated with permanently disrupting lung development and the host response to influenza A virus (IAV). However, many infants who go home with normally functioning lungs are also at risk for hyperreactivity after a respiratory viral infection. We recently reported a new, low-dose hyperoxia mouse model (40% for 8 days; 40x8) that causes a transient change in lung function that resolves, rendering 40x8 adult animals functionally indistinguishable from room air controls. Here we reported that when infected with IAV, 40x8 mice display an early transient activation of TGFβ signaling and later airway hyperreactivity associated with peribronchial inflammation (profibrotic macrophages) and fibrosis compared to infected room air controls, suggesting neonatal oxygen induced hidden molecular changes that prime the lung for hyperreactive airways disease. While searching for potential activators of TGFβ signaling, we discovered that thrombospondin-1 (TSP-1) is elevated in naïve 40x8 mice compared to controls and localized to lung megakaryocytes and platelets before and during IAV infection. Elevated TSP-1 was also identified in human autopsy samples of former preterm infants with bronchopulmonary dysplasia. These findings reveal how low doses of oxygen that do not durably change lung function may prime it for hyperreactive airways disease by changing expression of genes, such as TSP-1, thus helping to explain why former preterm infants who have normal lung function are susceptible to airway obstruction and increased morbidity after viral infection.

The relationship between intermittent hypoxemia events and neural outcomes in neonates

This brief review examines 1) patterns of intermittent hypoxemia in extremely preterm infants during early postnatal life, 2) the relationship between neonatal intermittent hypoxemia exposure and outcomes in both human and animal models, 3) potential mechanistic pathways, and 4) future alterations in clinical care that may reduce morbidity. Intermittent hypoxemia events are pervasive in extremely preterm infants (<28 weeks gestation at birth) during early postnatal life. An increased frequency of intermittent hypoxemia events has been associated with a range of poor neural outcomes including language and cognitive delays, motor impairment, retinopathy of prematurity, impaired control of breathing, and intraventricular hemorrhage. Neonatal rodent models have shown that exposure to short repetitive cycles of hypoxia induce a pathophysiological cascade. However, not all patterns of intermittent hypoxia are deleterious and some may even improve neurodevelopmental outcomes. Therapeutic interventions include supplemental oxygen, pressure support and pharmacologic drugs but prolonged hyperoxia and pressure exposure have been associated with cardiopulmonary morbidity. Therefore, it becomes imperative to distinguish high risk from neutral and/or even beneficial patterns of intermittent hypoxemia during early postnatal life. Identification of such patterns could improve clinical care with targeted interventions for high-risk patterns and minimal or no exposure to treatment modalities for low-risk patterns.

Extreme Prematurity and Pulmonary Outcomes Program in Saitama: Protocol for a Prospective Multicenter Cohort Study in Japan

Background

Because of the improvements in survival rates for preterm infants, not only the rates of bronchopulmonary dysplasia (BPD) but also those of long-term respiratory complications of premature birth are increasing, resulting in financial and health burdens in developed countries. Thus far, the risk factors of respiratory morbidities in extremely preterm infants remain unknown. Furthermore, the definition and the predictive ability of BPD for long-term respiratory outcomes are yet to be determined.

Objective

The objective of our study, Extreme Prematurity and Pulmonary Outcomes Program in Saitama, is to develop the diagnostic criteria for BPD and to determine the prognostic factors contributing to the long-term pulmonary outcomes manifesting in extremely preterm infants.

Methods

The Extreme Prematurity and Pulmonary Outcomes Program in Saitama is an observational prospective cohort study performed by a consortium of six neonatal intensive care units (NICUs) in Saitama, Japan. The subjects included in this study are infants (from each clinical center) with gestational ages 22 to 27 weeks. The target is 400 subjects. This study aims to determine the definition of BPD and other perinatal factors that accurately predict the long-term pulmonary outcomes in survivors of extreme prematurity. Moreover, the association between BPD and postprematurity respiratory disease will be investigated using generalized linear models.

Results

The protocol and consent forms were evaluated and approved on September 5, 2019, by the Ethics Committee of Saitama Medical Center, Saitama Medical University. Enrollment began on April 1, 2020. It is expected to end on March 31, 2023. The follow-up for 1 year corrected age is expected to continue through the middle of 2024.

Conclusions

The Extreme Prematurity and Pulmonary Outcomes Program in Saitama incorporates aspects of neonatal care in secondary- and tertiary-level NICUs to develop existing research studies on the definition of BPD, objective biomarkers, and outcome measures of respiratory morbidity in extremely preterm infants beyond NICU hospitalization, thereby leading to a novel understanding of the nature and natural history of BPD and potential mechanistic and therapeutic targets in at-risk subjects.

International Registered Report Identifier (IRRID)

DERR1-10.2196/22948

Inhaled vitamin A is more effective than intramuscular dosing in mitigating hyperoxia-induced lung injury in a neonatal rat model of bronchopulmonary dysplasia

Prevention of bronchopulmonary dysplasia (BPD) in premature-birth babies continues to be an unmet medical need. Intramuscular vitamin A is currently employed in preterm neonates to prevent BPD but requires intramuscular injections in fragile neonates. We hypothesized that noninvasive inhaled delivery of vitamin A, targeted to lung, would be a more effective and tolerable strategy. We employed our well-established hyperoxia-injury neonatal rat model, exposing newborn rats to 7 days of constant extreme (95% O₂) hyperoxia, comparing vitamin A dosed every 48 h via either aerosol inhalation or intramuscular injection with normoxic untreated healthy animals and vehicle-inhalation hyperoxia groups as positive and negative controls, respectively. Separately, similar vitamin A dosing of normoxia-dwelling animals was performed. Analyses after day 7 included characterization of alveolar histomorphology and protein biomarkers of alveolar maturation [surfactant protein C (SP-C), peroxisome proliferator-activated receptor (PPAR) γ, cholinephosphate cytidylyl transferase, vascular endothelial growth factor and its receptor, FLK-1, and retinoid X receptors (RXR-α, -β, and -γ], apoptosis (Bcl2 and Bax) key injury repair pathway data including protein markers (ALK-5 and β-catenin) and neutrophil infiltration, and serum vitamin A levels. Compared with intramuscular dosing, inhaled vitamin A significantly enhanced biomarkers of alveolar maturation, mitigated hyperoxia-induced lung damage, and enhanced surfactant protein levels, suggesting that it may be more efficacious in preventing BPD in extremely premature infants than the traditionally used IM dosing regimen. We speculate lung-targeted inhaled vitamin A may also be an effective therapy against other lung damaging conditions leading to BPD or, more generally, to acute lung injury.

Phenotypes of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic morbidity in preterm infants. In the absence of effective interventions, BPD is currently a major therapeutic challenge. Several risk factors are known for this multifactorial disease that results in disrupted lung development. Inflammation plays an important role and leads to persistent airway and pulmonary vascular disease. Since corticosteroids are potent anti-inflammatory agents, postnatal corticosteroids have been used widely for BPD prevention and treatment. However, the clinical responses vary to a great degree across individuals, and steroid-related complications remain major concerns. Emerging studies on the molecular mechanism of lung alveolarization during inflammatory stress will elucidate the complicated pathway and help discover novel therapeutic targets. Moreover, with the advances in metabolomics, there are new opportunities to identify biomarkers for early diagnosis and prognosis prediction of BPD. Pharmacometabolomics is another novel field aiming to identify the metabolomic changes before and after a specific drug treatment. Through this "metabolic signature," a more precise treatment may be developed, thereby avoiding unnecessary drug exposure in non-responders. In the future, more clinical, genetic, and translational studies would be required to improve the classification of BPD phenotypes and achieve individualized care to enhance the respiratory outcomes in preterm infants.

Characterization of Disease Phenotype in Very Preterm Infants with Severe Bronchopulmonary Dysplasia

Rationale: Bronchopulmonary dysplasia (BPD) is a heterogenous condition with poorly characterized disease subgroups.Objectives: To define the frequency of three disease components: moderate-severe parenchymal disease, pulmonary hypertension (PH), or large airway disease, in a referral cohort of preterm infants with severe BPD. The association between each component and a primary composite outcome of death before hospital discharge, tracheostomy, or home pulmonary vasodilator therapy was assessed.Methods: This was a retrospective, single-center cohort study of infants born at <32 weeks' gestation with severe BPD who underwent both chest computed tomography with angiography (CTA) and echocardiography between 40 and 50 weeks postmenstrual age between 2011 and 2015. Moderate-severe parenchymal lung disease was defined as an Ochiai score ≥8 on CTA. PH was diagnosed by echocardiogram using standard criteria. Large airway disease was defined as tracheomalacia or bronchomalacia on bronchoscopy and/or tracheoscopy or CTA.Measurements and Main Results: Of 76 evaluated infants, 73 (96%) were classifiable into phenotypic subgroups: 57 with moderate-severe parenchymal disease, 48 with PH, and 44 with large airway disease. The presence of all three disease components was most common (n = 23). Individually, PH and large airway disease, but not moderate-severe parenchymal disease, were associated with increased risk for the primary study outcome. Having more disease components was associated with an incremental increase in the risk for the primary outcome (2 vs. 1: odds ratio, 4.9; 95% confidence interval, 1.4-17.2 and 3 vs. 1: odds ratio, 12.8; 95% confidence interval, 2.4-70.0).Conclusions: Infants with severe BPD are variable in their predominant pathophysiology. Disease phenotyping may enable better risk stratification and targeted therapeutic intervention.

Foetal lung volumes in pregnant women who deliver very preterm: a pilot study

BACKGROUND

Infants born preterm are at increased risk of pulmonary morbidity. The contribution of antenatal factors to impairments in lung structure/function has not been fully elucidated. This study aimed to compare standardized lung volumes from foetuses that were delivered <32 weeks' gestation with foetuses that were delivered >37 weeks.

METHODS

Fourteen women who delivered <32 weeks gestation and 56 women who delivered >37 underwent a foetal MRI. Slice-volume reconstruction was then used and the foetal lungs were then segmented using multi-atlas approaches. Body volumes were calculated by manual segmentation and lung:body volume ratios generated.

RESULTS

Mean gestation at MRI of the preterm group was 27⁺² weeks (SD 2.9, range 20⁺⁶-31⁺³) and control group 25⁺³ weeks (SD 4.7 range 20⁺⁵-31⁺⁶). Mean gestation at delivery of the preterm group was 29⁺² weeks (SD 2.6, range 22⁺⁰-32⁺⁰). Lung:body volume ratios and foetal lung volumes were smaller in foetuses that were delivered preterm both with and without preterm premature rupture of membranes compared to those born at term (p < 0.001 in all cases).

CONCLUSIONS

Foetuses that were delivered very preterm had reduced lung volumes when standardized for foetal size, irrespective of ruptured membranes. These are novel findings and suggest an antenatal aetiology of insult and possible focus for future preventative therapies.

Respiratory Outcome of the Former Premature Infants

The research aims to identify the respiratory pathology during the first two years of life in premature infants with gestational ages between 30-34 weeks and the risk factors for these conditions (familial, prenatal, and neonatal).

There were investigated 31 premature infants with gestational ages between 30-34 weeks and the incidence of bronchopulmonary dysplasia, infections with the respiratory syncytial virus, or other viral infections requiring hospitalization, recurrent wheezing, and nasal colonization with pathogenic bacteria were noted. Also, regression models for each type of respiratory pathology as a function of the antenatal (smoking in the family, atopy, mother’s age) and neonatal (gestational age, respiratory distress syndrome, duration of the treatment with antibiotics, use of the reserve antibiotics) factors were elaborated.

Respiratory distress syndrome was present in 20 premature infants, and 19 infants received respiratory support. Two former premature infants presented with bronchopulmonary dysplasia, 3 with severe respiratory syncytial virus infections, 7 with recurrent wheezing, and 16 with viral infections requiring hospitalization. Respiratory distress syndrome and severe viral infections were more frequently found in families of smokers. Low gestational age and familial atopy were identified as good predictors of severe respiratory syncytial virus infections (p< 0.03)

Premature infants with gestational ages between 30-34 weeks present with the risk of appearance of respiratory diseases during the first two years of life, especially disorders of the airways. Familial atopy and low gestational age represent independent risk factors for severe respiratory syncytial virus infections.

Respiratory medication use in extremely premature (<29 weeks) infants during initial NICU hospitalization: Results from the prematurity and respiratory outcomes program

BACKGROUND

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.

METHODS

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 or neonatal intensive care unit discharge if earlier.

RESULTS

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.

CONCLUSION

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.

Early Pulmonary Vascular Disease in Preterm Infants Is Associated with Late Respiratory Outcomes in Childhood

RATIONALE

Early pulmonary vascular disease (PVD) after preterm birth is associated with a high risk for developing bronchopulmonary dysplasia (BPD), but its relationship with late respiratory outcomes during early childhood remains uncertain.

OBJECTIVES

To determine whether PVD at 7 days after preterm birth is associated with late respiratory disease (LRD) during early childhood.

METHODS

This was a prospective study of preterm infants born before 34 weeks postmenstrual age (PMA). Echocardiograms were performed at 7 days and 36 weeks PMA. Prenatal and early postnatal factors and postdischarge follow-up survey data obtained at 6, 12, 18, and 24 months of age were analyzed in logistic regression models to identify early risk factors for LRD, defined as a physician diagnosis of asthma, reactive airways disease, BPD exacerbation, bronchiolitis, or pneumonia, or a respiratory-related hospitalization during follow-up.

MEASUREMENTS AND MAIN RESULTS

Of the 221 subjects (median, 27 wk PMA; interquartile range, 25-28 and 920 g; interquartile range, 770-1090 g) completing follow-up, 61% met LRD criteria. Gestational diabetes and both mechanical ventilator support and PVD at 7 days were associated with LRD. The combination of PVD and mechanical ventilator support at 7 days was among the strongest prognosticators of LRD (odds ratio, 8.1; confidence interval, 3.1-21.9; P < 0.001). Modeled prenatal and early postnatal factors accurately informed LRD (area under the curve, 0.764). Adding BPD status at 36 weeks PMA to the model did not change the accuracy (area under the curve, 0.771).

CONCLUSIONS

Early echocardiographic evidence of PVD after preterm birth in combination with other perinatal factors is a strong risk factor for LRD, suggesting that early PVD may contribute to the pathobiology of BPD.

Postmenstrual age at discharge in premature infants with and without ventilatory pattern instability

RATIONALE

To determine if ventilatory pattern instability, manifested as periodic breathing (PB) during physiologic challenge testing, affects postmenstrual age (PMA) at discharge.

METHODS

Eighty infants underwent challenge testing at 36 weeks PMA. Infants breathing supplemental O₂ received a room air challenge (RAC, N = 51); those breathing ambient air underwent a hypoxic challenge test (HCT, N = 29). Infants were assigned one of four ventilatory control phenotypes based on the presence or absence of PB during their test, and if they passed or failed because of hypoxemia during the challenge test.

RESULTS

There were no clinical or demographic differences between groups. Infants who passed their challenge testing were, on average, discharged 1.6 weeks sooner than those who failed. The groups of ventilatory control phenotypes differed in PMA at discharge (p = 0.0020), but those with PB were younger by PMA at discharge.

CONCLUSIONS

Ventilatory pattern instability did not prolong time to discharge. Passing either challenge was associated with earlier discharge, suggesting these tests might identify infants who can have nasal cannula support removed and be safely discharged sooner. Most of the infants who failed their challenge tests with PB were receiving nasal cannula support. Nasal cannula support may be not only treating hypoxemia due to bronchopulmonary dysplasia (BPD), but also mitigating their ventilatory pattern instability.

Non-invasive measurements of respiratory system mechanical properties by the forced oscillation technique in spontaneously breathing, mixed-breed, normal term lambs from birth to five months of age

OBJECTIVE

To provide a non-invasive approach to monitoring lung function in spontaneously breathing lambs, from birth to five months of life, by the forced oscillation technique (FOT). This report describes the experimental set-up, data processing, and identification of normal predicted values of resistance (Rrs) and reactance (Xrs) of the respiratory system, along with normal bronchodilator response for bronchial reversibility testing.

APPROACH

Rrs and Xrs at 5, 11, and 19 Hz were measured monthly for five months in 20 normal term lambs that breathed spontaneously. In seven lambs, repeated measurements also were made within the first month of life (at 3, 7, 14, and 21 d of life). We determined the repeatability and reproducibility of the measurements and characterized the relationship between lung mechanics and age, sex, and body dimensions, using regression analysis, and measured changes in lung mechanics in response to inhaled bronchodilator.

MAIN RESULTS

The measurements provided repeatable and reproducible data. Rrs decreased, whereas Xrs increased, with growth from birth through the first two months of life, after which no statistically significant differences were detected. We identified normal value equations for Rrs and Xrs and for each of the measured anthropometric variables. Respiratory system mechanics were not affected by the bronchodilator.

SIGNIFICANCE

The FOT provides reliable non-invasive measurement of respiratory system mechanics in spontaneously breathing term lambs from birth to five months of age. The methods and normal reference values defined in this study will facilitate testing of the pathophysiological consequences of preterm birth and prolonged respiratory support on respiratory system mechanics.

The discovery BPD (D-BPD) program: study protocol of a prospective translational multicenter collaborative study to investigate determinants of chronic lung disease in very low birth weight infants

Background

Premature birth is a growing and serious public health problem affecting more than one of every ten infants worldwide. Bronchopulmonary dysplasia (BPD) is the most common neonatal morbidity associated with prematurity and infants with BPD suffer from increased incidence of respiratory infections, asthma, other forms of chronic lung illness, and death (Day and Ryan, Pediatr Res 81: 210–213, 2017; Isayama et la., JAMA Pediatr 171:271–279, 2017). BPD is now understood as a longitudinal disease process influenced by the intrauterine environment during gestation and modulated by gene-environment interactions throughout the neonatal and early childhood periods. Despite of this concept, there remains a paucity of multidisciplinary team-based approaches dedicated to the comprehensive study of this complex disease.

Methods

The Discovery BPD (D-BPD) Program involves a cohort of infants < 1,250 g at birth prospectively followed until 6 years of age. The program integrates analysis of detailed clinical data by machine learning, genetic susceptibility and molecular translation studies.

Discussion

The current gap in understanding BPD as a complex multi-trait spectrum of different disease endotypes will be addressed by a bedside-to-bench and bench-to-bedside approach in the D-BPD program. The D-BPD will provide enhanced understanding of mechanisms, evolution and consequences of lung diseases in preterm infants. The D-BPD program represents a unique opportunity to combine the expertise of biologists, neonatologists, pulmonologists, geneticists and biostatisticians to examine the disease process from multiple perspectives with a singular goal of improving outcomes of premature infants.

Trial registration

Does not apply for this study.

Electronic supplementary material

The online version of this article (10.1186/s12887-019-1610-8) contains supplementary material, which is available to authorized users.

Respiratory Medications in Infants <29 Weeks during the First Year Postdischarge: The Prematurity and Respiratory Outcomes Program (PROP) Consortium

OBJECTIVE

To determine patterns of respiratory medications used in neonatal intensive care unit graduates.

STUDY DESIGN

The Prematurity Respiratory Outcomes Program enrolled 835 babies <29 weeks 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 12 months of corrected age. Respiratory drug usage over the first year of life after in neonatal intensive care unit discharge was analyzed.

RESULTS

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 12 months. Drug exposure changed significantly based on gestational age with 72% of babies born at 23-24 weeks receiving at least 1 respiratory medication but only 40% of babies born at 28 weeks. 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%).

CONCLUSION

Many babies born at <29 weeks have no respiratory medication exposure postdischarge during the first year of life. Inhaled medications, including bronchodilators and steroids, increase over the first year.

Black Race Is Associated with a Lower Risk of Bronchopulmonary Dysplasia

OBJECTIVE

To use a large current prospective cohort of infants <29 weeks to compare bronchopulmonary dysplasia (BPD) rates in black and white infants.

STUDY DESIGN

The Prematurity and Respiratory Outcome Program (PROP) enrolled 835 infants born in 2011-2013 at <29 weeks of gestation; 728 black or white infants survived to 36 weeks postmenstrual age (PMA). Logistic regression was used to compare BPD outcomes (defined as supplemental oxygen requirement at 36 weeks PMA) between the races, adjusted for gestational age (GA), antenatal steroid use, intubation at birth, and surfactant use at birth.

RESULTS

Of 707 black or white infants with available BPD outcomes, BPD was lower in black infants (38% vs 45%), even though they were of significantly lower GA. At every GA, BPD was more common in white infants. The aOR for BPD was 0.60 (95% CI, 0.42-0.85; P = .004) for black infants compared with white infants after adjusting for GA. Despite the lower rate of BPD, black infants had a higher rate of first-year post-prematurity respiratory disease (black, 79%; white, 63%).

CONCLUSIONS

In this large cohort of recently born preterm infants at <29 weeks GA, compared with white infants, black infants had a lower risk of BPD but an increased risk of persistent respiratory morbidity.

Randomized controlled trial protocol to improve multisensory neural processing, language and motor outcomes in preterm infants

BACKGROUND

Premature infants are at risk for abnormal sensory development due to brain immaturity at birth and atypical early sensory experiences in the Neonatal Intensive Care Unit. This altered sensory development can have downstream effects on other more complex developmental processes. There are currently no interventions that address rehabilitation of sensory function in the neonatal period.

METHODS

This study is a randomized controlled trial of preterm infants enrolled at 32-36 weeks postmenstrual age to either standard care or standard care plus multisensory intervention in order to study the effect of multisensory intervention as compared to standard care alone. The study population will consist of 100 preterm infants in each group (total n = 200). Both groups will receive standard care, consisting of non-contingent recorded parent's voice and skin-to-skin by parent. The multisensory group will also receive contemporaneous holding and light pressure containment for tactile stimulation, playing of the mother's voice contingent on the infant's pacifier sucking for auditory stimulation, exposure to a parent-scented cloth for olfactory stimulation, and exposure to carefully regulated therapist breathing that is mindful and responsive to the child's condition for vestibular stimulation. The primary outcome is a brain-based measure of multisensory processing, measured using time locked-EEG. Secondary outcomes include sensory adaptation, tactile processing, speech sound differentiation, motor and language function, measured at one and two years corrected gestational age.

DISCUSSION

This is the first randomized controlled trial of a multisensory intervention using brain-based measurements in order to explain the causal effects of the multisensory intervention on neural processing changes to mediate neurodevelopmental outcomes in former preterm infants. In addition to contributing a critical link in our understanding of these processes, the protocolized multisensory intervention in this study is therapist administered, parent supported and leverages simple technology. Thus, this multisensory intervention has the potential to be widely implemented in various NICU settings, with the opportunity to potentially improve neurodevelopment of premature infants.

TRIAL REGISTRATION

NIH Clinical Trials ( clinicaltrials.gov ): NCT03232931 . Registered July 2017.

Neonatal intermittent hypoxemia events are associated with diagnosis of bronchopulmonary dysplasia at 36 weeks postmenstrual age

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a chronic lung disease and major pulmonary complication after premature birth. We have previously shown that increased intermittent hypoxemia (IH) events have been correlated to adverse outcomes and mortality in extremely premature infants. We hypothesize that early IH patterns are associated with the development of BPD.

METHODS

IH frequency, duration, and nadirs were assessed using oxygen saturation (SpO₂) waveforms in a retrospective cohort of 137 extremely premature newborns (<28 weeks gestation). Daily levels of inspired oxygen and mean airway pressure exposures were also recorded.

RESULTS

Diagnosis of BPD at 36 weeks postmenstrual age was associated with increased daily IH, longer IH duration, and a higher IH nadir. Significant differences were detected through day 7 to day 26 of life. Infants who developed BPD had lower mean SpO₂ despite their exposure to increased inspired oxygen and increased mean airway pressure.

CONCLUSIONS

BPD was associated with more frequent, longer, and less severe IH events in addition to increased oxygen and pressure exposure within the first 26 days of life. Early IH patterns may contribute to the development of BPD or aid in identification of neonates at high risk.

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

RATIONALE

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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).

Investigation and management of the long-term ventilated premature infant

Bronchopulmonary dysplasia (BPD) is a common complication of prematurity, and despite significant advances in neonatal care over recent decades its incidence has not diminished. Although most affected infants have mild disease requiring a short period of oxygen supplementation or respiratory support, severely affected infants can become dependent on positive pressure support for a prolonged duration. In such cases, investigations should be carried out to ascertain whether there are secondary disease processes exacerbating the child's respiratory status. In case of established severe BPD, respiratory support with non-invasive or invasive positive pressure ventilation is required. In this paper we discuss the indications for, and practicalities of, the various modalities available. Potential cardiorespiratory sequelae of BPD include recurrent respiratory infections, childhood wheezing illnesses, abnormalities of lung structure and function, and pulmonary hypertension.

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

Background

Previous 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.

Results

The 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.

Conclusions

We identified novel genes and associated pathways that may play an important role in susceptibility/resilience for the development of lung disease in preterm infants.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0679-7) contains supplementary material, which is available to authorized users.

Review shows that using surfactant a number of times or as a vehicle for budesonide may reduce the risk of bronchopulmonary dysplasia

AIM

Bronchopulmonary dysplasia (BPD) remains the most common respiratory morbidity in immature infants. This review describes the diagnosis of BPD has evolved and summarises the therapeutic approaches that have made it possible to limit the incidence of BPD.

METHOD

We reviewed the literature from the first definition of BPD by Northway in 1967 to the surfactant treatment policies that are currently in use, drawing on more than 50 papers up to 2017.

RESULTS

Our review showed that improvements in neonatal survival have been associated with an increased risk of severe BPD, significant levels of long-term morbidity and the increased use of healthcare resources. These issues have encouraged researchers to explore potential new treatments that limit the incidence of BPD. Repeated surfactant instillation and the use of surfactant as a vehicle for budesonide are promising strategies for alleviating the burden of chronic lung disease. Ongoing research on surfactant or stem cell therapy may further improve the respiratory prognosis for prematurely born children.

CONCLUSION

Considerable research has been carried out into the increase in BPD, which has resulted from improvements in neonatal survival. Key areas of research include repeated surfactant administration, using surfactant as a vehicle for budesonide and stem cell therapy.

The therapeutic effect of mesenchymal stem cells on pulmonary myeloid cells following neonatal hyperoxic lung injury in mice

Background

Exposure to high levels of oxygen (hyperoxia) after birth leads to lung injury. Our aims were to investigate the modulation of myeloid cell sub-populations and the reduction of fibrosis in the lungs following administration of human mesenchymal stem cells (hMSC) to neonatal mice exposed to hyperoxia.

Method

Newborn mice were exposed to 90% O₂ (hyperoxia) or 21% O₂ (normoxia) from postnatal days 0–4. A sub-group of hyperoxia mice were injected intratracheally with 2.5X10⁵ hMSCs. Using flow cytometry we assessed pulmonary immune cells at postnatal days 0, 4, 7 and 14. The following markers were chosen to identify these cells: CD45⁺ (leukocytes), Ly6C⁺Ly6G⁺ (granulocytes), CD11b⁺CD11c⁺ (macrophages); macrophage polarisation was assessed by F4/80 and CD206 expression. hMSCs expressing enhanced green fluorescent protein (eGFP) and firefly luciferase (fluc) were administered via the trachea at day 4. Lung macrophages in all groups were profiled using next generation sequencing (NGS) to assess alterations in macrophage phenotype. Pulmonary collagen deposition and morphometry were assessed at days 14 and 56 respectively.

Results

At day 4, hyperoxia increased the number of pulmonary Ly6C⁺Ly6G⁺ granulocytes and F4/80^lowCD206^low macrophages but decreased F4/80^highCD206^high macrophages. At days 7 and 14, hyperoxia increased numbers of CD45⁺ leukocytes, CD11b⁺CD11c⁺ alveolar macrophages and F4/80^lowCD206^low macrophages but decreased F4/80^highCD206^high macrophages. hMSCs administration ameliorated these effects of hyperoxia, notably reducing numbers of CD11b⁺CD11c⁺ and F4/80^lowCD206^low macrophages; in contrast, F4/80^highCD206^high macrophages were increased. Genes characteristic of anti-inflammatory ‘M2’ macrophages (Arg1, Stat6, Retnla, Mrc1, Il27ra, Chil3, and Il12b) were up-regulated, and pro-inflammatory ‘M1’ macrophages (Cd86, Stat1, Socs3, Slamf1, Tnf, Fcgr1, Il12b, Il6, Il1b, and Il27ra) were downregulated in isolated lung macrophages from hyperoxia-exposed mice administered hMSCs, compared to mice without hMSCs. Hydroxyproline assay at day 14 showed that the 2-fold increase in lung collagen following hyperoxia was reduced to control levels in mice administered hMSCs. By day 56 (early adulthood), hMSC administration had attenuated structural changes in hyperoxia-exposed lungs.

Conclusions

Our findings suggest that hMSCs reduce neonatal lung injury caused by hyperoxia by modulation of macrophage phenotype. Not only did our cell-based therapy using hMSC induce structural repair, it limited the progression of pulmonary fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0816-x) contains supplementary material, which is available to authorized users.

Effect of Maternal Smoking on Plasma and Urinary Measures of Vitamin E Isoforms in the First Month after Extreme Preterm Birth

We examined the effect of maternal smoking on plasma and urinary levels of vitamin E isoforms in preterm infants. Maternal smoking during pregnancy decreased infant plasma alpha- and gamma-tocopherol concentrations at 1 week and 4 weeks, with 45% of infants of smokers deficient in alpha-tocopherol at 1 month after birth.

Implementing Co-Regulated Feeding with Mothers of Preterm Infants

PURPOSE

The purpose of this study is to describe implementation of the Co-Regulated Feeding Intervention (CoReg), when provided by mothers and guided by intervention nurses trained in methods of guided participation (GP). Co-regulated feeding intervention aims to prevent stress during feeding and ease the challenge very preterm (VP) infants experience coordinating breathing and swallowing during the early months. Guided participation is a participatory learning method to guide the complex learning required for mothers.

STUDY DESIGN AND METHODS

Sixteen mothers of 17 VP infants participated. Each mother received a median of five intervention sessions during the infant's transition to oral feeding. Intervention field notes, audio recordings of the sessions, and video recordings of the nurse-guided feedings were reviewed, organized, and content analyzed to evaluate implementation.

RESULTS

The co-regulated feeding intervention was well received by mothers; enrollment, participation, and retention rates were high. Most mothers chose to spread out the intervention sessions across the transition period. Scheduling sessions was the greatest barrier. Mothers had competing demands and infant readiness to eat could not be predicted. The top five issues identified as needing attention by the mother or nurse included reading cues, coregulating breathing, providing motoric stability, regulating milk flow, and providing rest periods. Main GP strategies included joint attention with the mother to the dyad's feeding challenges, auditory assessment of breathing and swallowing, and reflection with planning for future feedings using video playback.

CLINICAL IMPLICATIONS

Nurse presence while mothers feed affords rich opportunities to guide coregulated, cue-based feeding. Co-regulated feeding intervention would be enhanced if mothers are guided by the bedside nurse.

Diagnostic value of chest CT combined with x-ray for premature infants with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in the newborns. Staging of BPD severity does not have a high predictive value for the outcomes. This study was aimed to assess the diagnostic value of chest computed tomography (CT) combined with x-ray for premature infants with BPD.Twenty-five premature infants with mild BPD and 20 premature infants with moderate to severe BPD treated at our hospital from January 2015 to December 2015 were randomly selected. The imaging features were compared between premature infants with different severity of BPD.In mild BPD group, the incidence of increased lung opacity (at 3-10 and 29 days) were significantly higher than those in infants with moderate to severe BPD (P = .034, P = .003, respectively). However, the incidences of stage III BPD (3-10 days) and stage IV BPD (11-27 days) were significantly lower in infants with mild BPD than those in infants with moderate to severe BPD (P = .013, P = .033, respectively). The chest x-ray score in the mild BPD group was significantly lower than that in moderate to severe BPD group [3.0 (1.0) vs 5.0 (1.0), P < .001]. Spearman rank correlation analysis indicated that chest x-ray score had significant correlation (r = 0.787, P < .001) with the clinical severity. In the mild BPD group, the chest CT scan score was 11.52 ± 3.49, which was considerably lower than that in the moderate to severe BPD group (24.70 ± 4.32) (P < .001). Moreover, the severity of BPD in the premature infants was significantly correlated to the chest CT scan score (r = 0.855, P < .001).Chest CT combined with x-ray is an effective method for predicting the severity of BPD in premature infants.

Pulmonary sequelae and functional limitations in children and adults with bronchopulmonary dysplasia

Preterm infants with bronchopulmonary dysplasia (BPD) often suffer from life-long pulmonary impairments in pulmonary physical function. This review summarizes our current understanding of the chronic pulmonary impairments and physical functional limitations associated with BPD from preterm birth to adulthood. It also identifies opportunities for intervention in children and adults living with chronic lung disease (CLD) after preterm birth.

A Combination of the Aerosolized PPAR-γ Agonist Pioglitazone and a Synthetic Surfactant Protein B Peptide Mimic Prevents Hyperoxia-Induced Neonatal Lung Injury in Rats

BACKGROUND

Despite improvements in perinatal care, bronchopulmonary dysplasia (BPD) in extremely premature infants has not decreased. Postnatal surfactant therapy provides symptomatic relief from respiratory distress syndrome, but does not translate into a reduction in BPD. Therefore, the search for effective interventions to prevent BPD continues.

OBJECTIVES

Since PPAR-γ agonists have been demonstrated to promote neonatal lung maturation and injury repair, we hypothesized that a formulation of a PPAR-γ agonist, pioglitazone (PGZ) and a synthetic lung surfactant (a surfactant protein B peptide mimic, B-YL) combined would stimulate lung maturation and block hyperoxia-induced neonatal lung injury more effectively than either modality alone.

METHODS

One-day-old Sprague-Dawley rat pups were administered PGZ + B-YL via nebulization every 24 h for up to 72 h. The pups were exposed to either 21 or 95% O2, and then sacrificed. Their lungs were examined for markers of lung maturation (levels of PPAR-γ, SP-C and choline-phosphate cytidylyltransferase [CCT-α] and [3H]triolein uptake) and injury repair (bronchoalveolar lavage cell count and protein content, and levels of LEF-1, fibronectin, ALK5, and β-catenin) by Western blot analysis.

RESULTS

Markers of alveolar epithelial/mesenchymal maturation (PPAR-γ, SP-C, CCT-α, and triolein uptake) increased significantly in the PGZ + B-YL group, more than with either drug alone. Similarly, markers of hyperoxia-induced lung injury were blocked effectively with PGZ + B-YL treatment.

CONCLUSIONS

Nebulized PPAR-γ agonist PGZ with a synthetic lung surfactant accelerates lung maturation and prevents neonatal hyperoxia-induced lung injury more than either modality alone, with the potential to provide more effective prevention of BPD.

A Pathogenic Relationship of Bronchopulmonary Dysplasia and Retinopathy of Prematurity? A Review of Angiogenic Mediators in Both Diseases

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are common and significant morbidities of prematurely born infants. These diseases have in common altered and pathologic vascular formation in the face of incomplete organ development. Therefore, it is reasonable to question whether factors affecting angiogenesis could have a joint pathogenic role for both diseases. Inhibition or induced expression of a single angiogenic factor is unlikely to be 100% causative or protective of either of BPD or ROP. It is more likely that interactions of multiple factors leading to disordered angiogenesis are present, increasing the likelihood of common pathways in both diseases. This review explores this possibility by assessing the evidence showing involvement of specific angiogenic factors in the vascular development and maldevelopment in each disease. Theoretical interactions of specific factors mutually contributing to BPD and ROP are proposed and, where possible, a timeline of the proposed relationships between BPD and ROP is developed. It is hoped that future research will be inspired by the theories put forth in this review to enhance the understanding of the pathogenesis in both diseases.

Bronchopulmonary dysplasia appropriateness as a surrogate marker for long-term pulmonary outcomes: A Systematic review

BACKGROUND

Bronchopulmonary dysplasia (BPD) is used to clinically describe the severity of lung disease and to serve as a common surrogate endpoint for long-term pulmonary morbidity in clinical trials, but its performance as a surrogate end-point warrants evaluation. Our objective was to assess real-world performance of BPD as a surrogate marker for long-term pulmonary outcomes.

METHODS

We performed a systematic review of large, multi-centered, blinded, randomized control trials to evaluate the use of BPD as a surrogate marker for long-term pulmonary outcomes. Long-term pulmonary outcomes occurred within two years and included measures of hospital utilization, respiratory illness, respiratory medication, and mortality. Direction and magnitude of effect were evaluated using number needed to treat analysis.

RESULTS

Five studies were included in our review. Studies varied in definition of BPD and in long-term outcomes measured. Only one study found a significant, consistent risk reduction in both BPD and any long-term pulmonary outcome. Two studies found significant reductions in long-term pulmonary outcomes with a non-significant reduction in BPD.

CONCLUSIONS

BPD is an imperfect surrogate marker for long-term pulmonary outcomes. It did not consistently predict the magnitude or direction of the effect of an intervention on longer-term pulmonary outcomes. Furthermore, there was significant variation in the definitions of BPD and in the long-term pulmonary outcomes used. There is a need for future work to identify more predictive surrogate markers and a need for better standardization of assessments of long-term pulmonary outcomes.