Antenatal factors and the development of bronchopulmonary dysplasia

Impact of antenatal corticosteroids-to-delivery interval on very preterm neonatal outcomes: a retrospective study in two tertiary centers in Japan

BACKGROUND

Antenatal corticosteroids (ACS) are administered to prevent neonatal complications and death in women at risk of imminent preterm birth. Internationally, the optimal interval from ACS to delivery (ACS-to-delivery interval) is within seven days; however, evidence in Asian populations specifically is limited. This study aimed to investigate the association between ACS-to-delivery interval and the incidence of neonatal complications in Japan.

METHODS

This retrospective observational study enrolled singleton neonates born preterm at < 32 weeks of gestational age between 2012 and 2020 at two tertiary centers. A total of 625 neonates were divided into the following four groups according to the timing of ACS (measured in days): no ACS (n = 145), partial ACS (n = 85), ACS 1-7 (n = 307), and ACS ≥ 8 (n = 88). The following outcomes were compared between the groups: treated respiratory distress syndrome (RDS), severe intraventricular hemorrhage (IVH), treated patent ductus arteriosus (PDA), necrotizing enterocolitis, sepsis, bronchopulmonary dysplasia (BPD), treated retinopathy of prematurity (ROP), periventricular leukomalacia, and death discharge.

RESULTS

The ACS 1-7 group had significantly decreased adjusted odds ratios (ORs) for treated RDS (0.37 [95% confidence interval: 0.23, 0.57]), severe IVH (0.21 [0.07, 0.63]), treated PDA (0.47 [0.29, 0.75]), and treated ROP (0.50 [0.25, 0.99]) compared with the no ACS group. The ACS ≥ 8 group also showed significantly reduced adjusted ORs for RDS (0.37 [0.20, 0.66]) and treated PDA (0.48 [0.25, 0.91]) compared with the no ACS group. However, the adjusted ORs for BPD significantly increased in both the ACS 1-7 (1.86 [1.06, 3.28]) and ACS ≥ 8 groups (2.94 [1.43, 6.05]) compared to the no ACS group.

CONCLUSIONS

An ACS-to-delivery interval of 1-7 days achieved the lowest incidence of several complications in preterm neonates born at < 32 weeks of gestational age. Some of the favorable effects of ACS seem to continue even beyond ≥ 8 days from administration. In contrast, ACS might be associated with an increased incidence of BPD, which was most likely to be prominent in neonates delivered ≥ 8 days after receiving ACS. Based on these findings, the duration of the effect of ACS on neonatal complications should be studied further.

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.

Beyond Bronchopulmonary Dysplasia: A Comprehensive Review of Chronic Lung Diseases in Neonates

In neonates, pulmonary diseases such as bronchopulmonary dysplasia and other chronic lung diseases (CLDs) pose significant challenges due to their complexity and high degree of morbidity and mortality. This review discusses the etiology, pathophysiology, clinical presentation, and diagnostic criteria for these conditions, as well as current management strategies. The review also highlights recent advancements in understanding the pathophysiology of these diseases and evolving strategies for their management, including gene therapy and stem cell treatments. We emphasize how supportive care is useful in managing these diseases and underscore the importance of a multidisciplinary approach. Notably, we discuss the emerging role of personalized medicine, enabled by advances in genomics and precision therapeutics, in tailoring therapy according to an individual's genetic, biochemical, and lifestyle factors. We conclude with a discussion on future directions in research and treatment, emphasizing the importance of furthering our understanding of these conditions, improving diagnostic criteria, and exploring targeted treatment modalities. The review underscores the need for multicentric and longitudinal studies to improve preventative strategies and better understand long-term outcomes. Ultimately, a comprehensive, innovative, and patient-centered approach can enhance the quality of care and outcomes for neonates with CLDs.

Epididymal embryonic development harbors TLR4/NFKB signaling pathway as a morphogenetic player

The Wolffian duct (WD) is an embryonic tissue that undergoes androgen-induced morphological changes to become the epididymis. Toll-like receptor 4 (TLR4)- and nuclear factor kB (NFKB)-induced effectors are expressed in the adult epididymis and represent important players in epididymal innate immune responses. TLR4/NFKB signaling pathway is evolutionarily conserved and plays a critical morphogenetic role in several species; however, its function during WD morphogenesis is unknown. We hypothesized that TLR4/NFKB pathway plays a role during WD development. Here we examined TLR4 expression and regulation of TLR4-target genes during rat WD morphogenesis between embryonic days (e) 17.5-20.5. The functionality of TLR4/NFKB signaling was examined using WD organotypic cultures treated with lipopolysaccharide (LPS) from E. coli (TLR4 agonist) and PDTC (NFKB inhibitor). TLR4 was detected at mRNA level in e17.5 (uncoiled duct) and e20.5 (coiled duct) WDs, and spatio-temporal changes in TLR4 immunoreactivity were observed between these two time points. Expression level analysis of a subset of TLR4-regulated genes showed that TLR4/NFKB pathway was activated after exposure of cultured WD to LPS (4 h), an event that was abrogated by PDTC. Long-term exposure of cultured WDs to LPS (96 h) resulted in dysregulations of morphogenetic events and LAMA1 immunodistribution changes, suggesting the extracellular matrix at the intersection between WD morphogenesis and balance of innate immune components. Our results unveil the epididymal morphogenesis as an event equipped with TLR4/NFKB signaling components that may serve developmental functions, and eventually transition to host defense function when the fetus is exposed to an infectious or noninfectious threat.

Association between maternal cervicovaginal swab positivity for Ureaplasma spp. or other microorganisms and neonatal respiratory outcome and mortality

OBJECTIVE

We investigated the association between maternal cervicovaginal cultures, its antibiotic treatment, and neonatal outcome.

STUDY DESIGN

This retrospective cohort study enrolled 480 neonates born prior to 32 weeks' gestation. They were divided into groups according to maternal cervicovaginal culture results. Multivariate logistic regression analysis was used to predict neonatal outcome based on maternal culture results, adjusted for perinatal risk factors and neonatal morbidities.

RESULT

Maternal cervicovaginal Ureaplasma colonization was independently associated with bronchopulmonary dysplasia at 36 weeks (BPD) (OR 8.34; 95% CI 1.21-57.45). In neonates with and without maternal cervicovaginal Ureaplasma colonization BPD occurred in 12.3% and 3.8%, respectively. Maternal colonization with other microorganisms was associated with a higher neonatal mortality (p = 0.002), lower gestational age (p = 0.026), and birth weight (p = 0.036).

CONCLUSIONS

This study underscores the role of the maternal cervicovaginal microbiome as a predictor of neonatal outcome. Cervicovaginal Ureaplasma colonization seems not to be an innocent bystander in the multifactorial etiology of BPD.

Labor dystocia and risk of histological chorioamnionitis and funisitis: a study from a single tertiary referral center

Background

Intrauterine inflammation affects short- and long-term neonatal outcomes. Histological chorioamnionitis and funisitis are acute inflammatory responses in the fetal membranes and umbilical cord, respectively. Although labor dystocia includes a potential risk of intrauterine inflammation, the risk of histological chorioamnionitis and funisitis of labor dystocia has not been evaluated yet. This study aimed to examine the association between labor dystocia and risk of histological chorioamnionitis and funisitis.

Methods

In this retrospective cohort study, the cases who underwent histopathological examinations of the placenta and umbilical cord at Fukushima Medical University Hospital, Japan, between 2015 and 2020, were included. From the dataset, the pathological findings of the patients with labor dystocia and spontaneous preterm birth were reviewed. Based on the location of leukocytes, the inflammation in the placenta (histological chorioamnionitis) and umbilical cord (funisitis) was staged as 0–3. Multiple logistic regression analysis was performed to evaluate the risk of histological chorioamnionitis, histological chorioamnionitis stage ≥2, funisitis, and funisitis stage ≥2.

Result

Of 317 women who met the study criteria, 83 and 144 women had labor dystocia and spontaneous preterm birth, respectively, and 90 women were included as controls. Labor dystocia was a risk factor for histological chorioamnionitis (adjusted odds ratio, 6.3; 95% confidential interval, 1.9–20.5), histological chorioamnionitis stage ≥2 (adjusted odds ratio, 6.0; 95% confidence interval, 1.7–21.8), funisitis (adjusted odds ratio, 15.4; 95% confidence interval, 2.3–101.3), and funisitis stage ≥2 (adjusted odds ratio, 18.5; 95% confidence interval, 2.5–134.0). Spontaneous preterm birth was also a risk factor for histological chorioamnionitis (adjusted odds ratio, 3.7; 95% confidence interval, 1.7–7.8), histological chorioamnionitis stage ≥2 (adjusted odds ratio, 3.0; 95% confidence interval, 1.2–7.9), and funisitis (adjusted odds ratio, 6.6; 95% confidence interval, 1.4–30.6). However, the adjusted odds ratio was smaller in spontaneous preterm births than in labor dystocia.

Conclusion

Labor dystocia is a risk factor for severe histological chorioamnionitis and funisitis. Further studies are required to evaluate the effects of histological chorioamnionitis and funisitis on long-term neonatal outcomes.

Dietary Inflammatory Index during Pregnancy and the Risk of Intrapartum Fetal Asphyxia: The Japan Environment and Children's Study

We aimed to examine the impact of a daily pro-inflammatory diet during pregnancy on intrapartum fetal acidemia using a large birth cohort study in Japan. We used data on singleton pregnancies in the Japan Environment and Children’s Study (JECS) involving births from 2011 to 2014 through vaginal delivery to calculate the maternal dietary inflammatory index (DII). Participants were categorized according to DII quintiles. A multiple logistic regression model was used to estimate the risk of a pro-inflammatory diet on fetal umbilical artery pH. In total, 56,490 participants were eligible for this study. Multiple regression analysis showed that nulliparous women who had undergone vaginal delivery and were consuming a pro-inflammatory diet had an increased risk of pH < 7.10 (adjusted odds ratio [aOR]: 1.64, 95% confidence interval [CI]: 1.12–2.39). Among these women, the risk of pH < 7.10 was not affected by the duration of labor (aOR: 1.64, 95% CI: 1.11–2.42). In conclusion, following a pro-inflammatory diet during pregnancy is a risk factor for fetal acidosis among nulliparous women undergoing vaginal delivery. A high DII diet during pregnancy may modify the intrapartum fetal heart rate pattern via intrauterine inflammation.

Correlation between chorionic plate vascularization and risk of bronchopulmonary dysplasia in extremely preterm infants

INTRODUCTION/OBJECTIVES

The chorionic plate vessels of the placenta are in direct continuity with the fetal vasculature, suggesting chorionic and fetal angiogenesis may be subjected to similar regulatory mechanisms. In this study, we determined the correlation between chorionic plate vascularization and complications of prematurity, focusing on bronchopulmonary dysplasia (BPD) and other conditions with important microvascular components.

METHODS

We performed a clinicoplacental analysis of 127 extremely preterm infants (23-28 weeks gestation). Chorionic plate vascularization was assessed by number and density of perforating chorionic vessels (PCVs). Charts were reviewed for relevant maternal and neonatal data, including respiratory, neurologic and gastrointestinal complications of prematurity.

RESULTS

The placentas displayed marked variability in number (36-523/placenta) and density of PCVs (0.46-3.74 PC V/cm²). The median PCV density of infants with severe BPD was significantly higher than that of infants without BPD (1.51 PC V/cm² versus 1.09 PC V/cm², P < 0.05). Conversely, the frequency of moderate-to-severe BPD was 33% higher in infants with PCV density ≥1.50 PC V/cm² than in those with PCV density <1.50 PC V/cm² (56% versus 40%, P < 0.01). There was no correlation with neonatal neurologic or gastrointestinal complications.

CONCLUSION

Chorionic plate vascularization correlates with frequency and severity of BPD, supporting a vascular basis that in part is antenatal in origin. Quantitative assessment of chorionic plate vascularization may allow early identification of preterm infants at high risk for BPD (proposed threshold: PCV density ≥1.50 PC V/cm²). The lack of correlation between chorionic vascularization and neurologic/gastrointestinal complications suggests these conditions may have less important antenatal and/or vascular contributions.

In-line filtration in very preterm neonates: a randomized controlled trial

In-line filtration is increasingly used in critically-ill infants but its benefits, by preventing micro-particle infusion in very preterm neonates, remain to be demonstrated. We conducted a randomized controlled trial among very preterm infants allocated to receive either in-line filtration of all the intra-venous lines or standard care without filters. The primary outcome was differences greater than 20% in the median changes in pro-inflammatory cytokine serum concentrations measured at day 3 and day 8 (+/-1) using a Luminex multianalytic profiling technique. Major neonatal complications were analyzed as secondary predefined outcomes. We randomized 146 infants, assigned to filter (n = 73) or control (n = 73) group. Difference over 20% in pro-inflammatory cytokine concentration between day 3 and day 8 was not found statistically different between the two groups, both in intent-to-treat (with imputation) and per protocol (without imputation) analyses. The incidences of most of neonatal complications were found to be similar. Hence, this trial did not evidence a beneficial effect of in-line filtration in very preterm infants on the inflammatory response syndrome and neonatal morbidities. These data should be interpreted according to local standards in infusion preparation and central line management.

Bone marrow stem cells accelerate lung maturation and prevent the LPS-induced delay of morphological and functional fetal lung development in the presence of ErbB4

ErbB4 is a regulator in lung development and disease. Prenatal infection is an important risk factor for the delay of morphologic lung development, while promoting the maturation of the surfactant system. Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to prevent lung injury. We hypothesized that BMSCs in comparison with hematopoietic control stem cells (HPSCs) minimize the lipopolysaccharide (LPS)-induced lung injury only when functional ErbB4 receptor is present. We injected LPS and/or murine green fluorescent protein-labeled BMSCs or HPSCs into the amniotic cavity of transgenic ErbB4^heart mothers at gestational day 17. Fetal lungs were analyzed 24 h later. BMSCs minimized significantly LPS-induced delay in morphological lung maturation consisting of a stereologically measured increase in mesenchyme and septal thickness and a decrease of future airspace and septal surface. This effect was more prominent and significant in the ErbB4^heart+/- lungs, suggesting that the presence of functioning ErbB4 signaling is required. BMSC also diminished the LPS induced increase in surfactant protein (Sftp)a mRNA and decrease in Sftpc mRNA is only seen if ErbB4 is present. The reduction of morphological delay of lung development and of levels of immune-modulating Sftp was more pronounced in the presence of the ErbB4 receptor. Thus, ErbB4 may be required for the protective signaling of BMSCs.

Postnatal Alveologenesis Depends on FOXF1 Signaling in c-KIT+ Endothelial Progenitor Cells

Rationale: Disruption of alveologenesis is associated with severe pediatric lung disorders, including bronchopulmonary dysplasia (BPD). Although c-KIT+ endothelial cell (EC) progenitors are abundant in embryonic and neonatal lungs, their role in alveolar septation and the therapeutic potential of these cells remain unknown.Objectives: To determine whether c-KIT+ EC progenitors stimulate alveologenesis in the neonatal lung.Methods: We used single-cell RNA sequencing of neonatal human and mouse lung tissues, immunostaining, and FACS analysis to identify transcriptional and signaling networks shared by human and mouse pulmonary c-KIT+ EC progenitors. A mouse model of perinatal hyperoxia-induced lung injury was used to identify molecular mechanisms that are critical for the survival, proliferation, and engraftment of c-KIT+ EC progenitors in the neonatal lung.Measurements and Main Results: Pulmonary c-KIT+ EC progenitors expressing PECAM-1, CD34, VE-Cadherin, FLK1, and TIE2 lacked mature arterial, venal, and lymphatic cell-surface markers. The transcriptomic signature of c-KIT+ ECs was conserved in mouse and human lungs and enriched in FOXF1-regulated transcriptional targets. Expression of FOXF1 and c-KIT was decreased in the lungs of infants with BPD. In the mouse, neonatal hyperoxia decreased the number of c-KIT+ EC progenitors. Haploinsufficiency or endothelial-specific deletion of Foxf1 in mice increased apoptosis and decreased proliferation of c-KIT+ ECs. Inactivation of either Foxf1 or c-Kit caused alveolar simplification. Adoptive transfer of c-KIT+ ECs into the neonatal circulation increased lung angiogenesis and prevented alveolar simplification in neonatal mice exposed to hyperoxia.Conclusions: Cell therapy involving c-KIT+ EC progenitors can be beneficial for the treatment of BPD.

Lung Function and Relevant Clinical Factors in Very Low Birth Weight Preterm Infants with Chronic Lung Disease: An Observational Study

Background

Chronic lung disease (CLD), most commonly seen in premature infants who required mechanical ventilation, is associated with functional consequences on lungs and respiratory morbidity. This study aimed to evaluate the lung function of premature infants before discharge and their relevant factors related to the lung function.

Methods

Very low birth weight (VLBW) preterm infants, who required respiratory support soon after birth and were admitted to a hospital in Taiwan, were enrolled. Infants with a need for supplemental oxygen or positive-pressure ventilation support at the postmenstrual age (PMA) of 36 weeks were diagnosed with CLD. Lung function was examined once using EXHALYZER® D before infants were ready for discharge.

Results

Forty-five VLBW preterm infants received the lung function test before discharge, 27 of whom were diagnosed with CLD. The gestational age (p=0.001) and birth weight (p < 0.001) were smaller in the CLD group than in the no-CLD group. Furthermore, infants with CLD required a longer duration of respiratory support (p < 0.001). The postnatal age and PMA were higher and body size was bigger in infants with CLD on lung function measurement. However, lung function was comparable between the groups. The functional residual capacity and tidal volume were associated with body size upon measuring lung function among all VLBW premature infants. FRC was positively correlated with the body length on measuring lung function in those with CLD.

Conclusion

In our study, we showed FRC was positively related to the PMA and body length and tidal volume was positively correlated with the body weight and length on lung function measurement in VLBW preterm infants before discharge. Moreover, FRC was positively correlated with the body length on measuring lung function in those with CLD. The lung volume, ventilation, and respiratory mechanics on discharge were comparable between CLD and no-CLD groups.

Prophylactic postnatal corticosteroids: Early hydrocortisone

Inflammation is a key contributor to the pathogenesis of bronchopulmonary dysplasia (BPD) in preterm infants, and cortisol plays a central role in controlling inflammation. Insufficient cortisol limits the ability of the sick newborn to handle stress and inhibit pulmonary inflammation. Evidence of lower cortisol and lower response to adrenocorticotropic hormone in infants subsequently developing BPD led to studies of early low-dose hydrocortisone to prevent BPD. Based on four randomised clinical trials enrolling almost 1000 extremely preterm infants, prophylaxis of early adrenal insufficiency with low-dose hydrocortisone significantly decreased BPD and mortality, as well as medical treatment for a patent ductus arteriosus. An increase in late-onset sepsis reported in the most immature infants had no adverse effect on mortality or neurodevelopmental outcomes. There was no increase in gastrointestinal perforation in the absence of indomethacin. The demonstrated beneficial effects of early low-dose hydrocortisone make a strong case for its use in extremely preterm infants at high risk for BPD.

Utility of cervical length and quantitative fetal fibronectin for predicting spontaneous preterm delivery among symptomatic nulliparous women

OBJECTIVE

To validate the utility of fetal fibronectin (fFN) and cervical length (CL) in predicting preterm delivery among symptomatic nulliparous women.

METHODS

A retrospective cohort study of nulliparous women who presented with uterine contractions, abdominal pain, or cervical change at 21-34 gestational weeks at Fukushima Medical University Hospital, Japan, between 2008 and 2017. fFN (categorized as <50 ng/dL, 50-199 ng/dL, >200 ng/dL) and CL (≥15 mm or <15 mm) were evaluated simultaneously. Adjusted odds ratios (aORs) and confidence intervals (CIs) for preterm delivery before 37 or 34 weeks, and delivery within 28 or 14 days were calculated (references: fFN, <50 ng/dL; CL, ≥15 mm).

RESULT

Among 285 women who met the study criteria, CL less than 15 mm was a risk factor for preterm delivery before 37 (aOR, 4.1; 95% CI, 1.1-6.7) and 34 (aOR, 6.8; 95% CI, 2.3-20.2) weeks. fFN of 200 ng/dL or higher was a risk factor for delivery within 28 (aOR, 19.8; 95% CI, 4.3-90.2) and 14 (aOR, 10.8; 95% CI, 1.7-67.6) days.

CONCLUSION

Among symptomatic nulliparous women, short CL was found to be a risk factor for preterm delivery and higher fFN levels were related to short gestational latency.

Association of Atrial Septal Defects and Bronchopulmonary Dysplasia in Premature Infants

OBJECTIVE

To evaluate the association between the presence of an atrial septal defect (ASD) and the odds of developing bronchopulmonary dysplasia (BPD) in premature infants.

STUDY DESIGN

We identified a cohort of infants that underwent at least one echocardiogram assessment, birth weight 501-1249 g, and gestational age 23-30 weeks discharged from the neonatal intensive care unit from 2004 to 2016. We used a BPD risk estimator to calculate the predicted risk of developing BPD at 6 postnatal ages within the first 28 days of life. We examined the association between the presence of an ASD and the development of BPD using 2 multivariable logistic regression models for each BPD risk severity on each postnatal day. The first model adjusted for predicted BPD risk and the second added therapeutic interventions for BPD.

RESULTS

Of 20 496 infants from 228 NICUs who met inclusion criteria, 8892 (43%) were diagnosed with BPD and 1314 (6%) had an ASD. BPD was present in 48% of infants with an ASD and 43% of infants without an ASD. In infants with an ASD, the OR of developing BPD was higher after adjusting for predicted risk of BPD plus therapeutic interventions, regardless of postnatal age or predicted BPD risk severity.

CONCLUSIONS

The presence of an ASD was associated with an increased odds of BPD in this cohort. Future trials should consider ASD as a potentially modifiable risk factor in this vulnerable population.

Glucocorticoids influence versican and chondroitin sulphate proteoglycan levels in the fetal sheep lung

BACKGROUND

Prenatal glucocorticoid treatment decreases alveolar tissue volumes and facilitates fetal lung maturation, however the mechanisms responsible are largely unknown. This study examines whether changes in versican levels or sulphation patterns of chondroitin sulphate (CS) side chains, are associated with glucocorticoid-induced reductions in peri-alveolar tissue volumes.

METHODS

Lung tissue was collected from 1) fetal sheep at 131 ± 0.1 days gestational age (GA) infused with cortisol (122-131d GA) to prematurely induce a pre-parturient-like rise in circulating cortisol, 2) fetal sheep at 143d GA bilaterally adrenalectomised (ADX) at 112d GA to remove endogenous cortisol and 3) fetal sheep at 124d GA in which bolus doses (2 × 11.4 mg) of betamethasone were administered to the pregnant ewe. The level and distribution of versican and CS glycosaminoglycans (GAG) were determined using immunohistochemistry (IHC). Fluorophore assisted carbohydrate electrophoresis (FACE) was used to determine changes in CS sulphation patterns.

RESULTS

Cortisol infusion significantly decreased chondrotin-6-sulphate levels (C-6-S) to 16.4 ± 0.7 AU, compared with saline-infused fetuses (18.9 ± 0.7 AU: p = 0.04) but did not significantly alter the level of versican or chondroitin-4-sulphate (C-4-S). ADX significantly increased the level of C-4-S (28.2 ± 2.2 AU), compared with sham-operated fetuses (17.8 ± 2.0 AU; p = 0.006) without altering versican or C-6-S levels. Betamethasone significantly decreased versican, C-4-S and C-6-S in the fetal sheep lung (19.2 ± 0.9 AU, 24.9 ± 1.4 AU and 23.2 ± 1.0 AU, respectively), compared with saline-exposed fetuses (24.3 ± 0.4 AU, p = 0.0004; 33.3±0.6 AU, p = 0.0003; 29.8±1.3 AU, 0.03, respectively).

CONCLUSIONS

These results indicate that glucocorticoids alter versican levels and CS side chain microstructure in alveolar lung tissue. Betamethasone appears to have a greater impact on versican and CS side chains than cortisol.

The effects of hydrogen peroxide and lipopolysaccharide on rat alveolar L2 cells

PURPOSE

This study aimed to investigate differential cell responses of alveolar epithelial cells (AECs) after treatments with lipopolysaccharide (LPS) and hydrogen peroxide (H₂O₂) to mimic the exposure to inflammation and oxidative stress and the mechanisms of a double-hit model of apoptosis.

MATERIALS AND METHODS

AECs were cultured and treated with combinations of 1 μg/mL of LPS and 500 μM H₂O₂ as follows: LPS-only at 0 h, LPS at 0 h with H₂O₂ at 6 h (LPS + H₂O₂), H₂O₂-only at 0 h, H₂O₂ at 0 h with LPS at 6 h (H₂O₂ + LPS), and control. We investigated mRNA expression (TNF-α, Fas, Fas ligand, Bax, Bcl-2, Caspase-7), protein expression (Fas, Bax, Bcl-2, Caspase-7) and apoptosis (Caspase-3 activity, TUNEL assay) at 0, 3, 6, 9, 12, and 24 h.

RESULTS

In the H₂O₂ + LPS group, the Caspase-7, and Fas mRNA levels were significantly higher than the other groups at 9 h and 12 h, and Bax was higher at 12 h. The Bax/Bcl-2 protein expression ratio was significantly higher in the H₂O₂ + LPS group than that of the other groups at 12h and 24h. Apoptotic index was highest in the H₂O₂ + LPS group at 24 h.

CONCLUSIONS

The sequence of stimulation may modify the cell response in rat AECs. The results suggest that previous oxidative stress and subsequent LPS-induced inflammation primarily influence apoptosis of L2 cells by up-regulation of cell signaling.

Bronchopulmonary Dysplasia: Chronic Lung Disease of Infancy and Long-Term Pulmonary Outcomes

Bronchopulmonary dysplasia (BPD) is a chronic lung disease most commonly seen in premature infants who required mechanical ventilation and oxygen therapy for acute respiratory distress. While advances in neonatal care have resulted in improved survival rates of premature infants, limited progress has been made in reducing rates of BPD. Lack of progress may in part be attributed to the limited therapeutic options available for prevention and treatment of BPD. Several lung-protective strategies have been shown to reduce risks, including use of non-invasive support, as well as early extubation and volume ventilation when intubation is required. These approaches, along with optimal nutrition and medical therapy, decrease risk of BPD; however, impacts on long-term outcomes are poorly defined. Characterization of late outcomes remain a challenge as rapid advances in medical management result in current adult BPD survivors representing outdated neonatal care. While pulmonary disease improves with growth, long-term follow-up studies raise concerns for persistent pulmonary dysfunction; asthma-like symptoms and exercise intolerance in young adults after BPD. Abnormal ventilatory responses and pulmonary hypertension can further complicate disease. These pulmonary morbidities, combined with environmental and infectious exposures, may result in significant long-term pulmonary sequalae and represent a growing burden on health systems. Additional longitudinal studies are needed to determine outcomes beyond the second decade, and define risk factors and optimal treatment for late sequalae of disease.

Early inhaled steroid use in extremely low birthweight infants: a randomised controlled trial

OBJECTIVE

We hypothesised that a prophylactic inhaled steroid would prevent the progression of bronchopulmonary dysplasia (BPD) in extremely low birthweight infants (ELBWIs).

DESIGN

This study was a multicentre, randomised, double-blinded, placebo-controlled trial.

SETTING

This investigation was conducted in 12 level III neonatal intensive care units (NICUs).

PATIENTS

A total of 211 ELBWIs requiring ventilator support were enrolled.

INTERVENTION

Starting within 24 h of birth and continuing until 6 weeks of age or extubation, two doses of 50 μg fluticasone propionate (FP) or placebo were administered every 24 h.

MAIN OUTCOME MEASUREMENT

The primary outcome measure used to indicate the morbidity of severe BPD incidence was death or oxygen dependence at discharge from the NICU. The secondary measures were neurodevelopmental impairments (NDIs) at 18 months of postmenstrual age and 3 years of age. We performed subgroup analyses based on gestational week (GW) and the presence of chorioamnionitis (CAM).

RESULTS

Infants were randomised into the FP (n=107) or placebo (n=104) groups. No significant differences were detected between the FP and placebo groups with respect to either the frequency of death or the oxygen dependence at discharge or NDIs. In subgroup analyses, the frequencies of death and oxygen dependence at discharge were significantly decreased in the FP group for infants born at 24-26 GWs and for infants with CAM, regardless of the GW at birth.

CONCLUSIONS

Inhaled steroids have no effect on the prevention of severe BPD or long-term NDI but might decrease the severity of BPD for ELBWIs with a risk factor.

TRIAL REGISTRATION NUMBER

UMIN-CTR C000000405.

Progressive Vascular Functional and Structural Damage in a Bronchopulmonary Dysplasia Model in Preterm Rabbits Exposed to Hyperoxia

Bronchopulmonary dysplasia (BPD) is caused by preterm neonatal lung injury and results in oxygen dependency and pulmonary hypertension. Current clinical management fails to reduce the incidence of BPD, which calls for novel therapies. Fetal rabbits have a lung development that mimics humans and can be used as a translational model to test novel treatment options. In preterm rabbits, exposure to hyperoxia leads to parenchymal changes, yet vascular damage has not been studied in this model. In this study we document the early functional and structural changes of the lung vasculature in preterm rabbits that are induced by hyperoxia after birth. Pulmonary artery Doppler measurements, micro-CT barium angiograms and media thickness of peripheral pulmonary arteries were affected after seven days of hyperoxia when compared to controls. The parenchyma was also affected both at the functional and structural level. Lung function testing showed higher tissue resistance and elastance, with a decreased lung compliance and lung capacity. Histologically hyperoxia leads to fewer and larger alveoli with thicker walls, less developed distal airways and more inflammation than normoxia. In conclusion, we show that the rabbit model develops pulmonary hypertension and developmental lung arrest after preterm lung injury, which parallel the early changes in human BPD. Thus it enables the testing of pharmaceutical agents that target the cardiovascular compartment of the lung for further translation towards the clinic.

Gene expression profiling at birth characterizing the preterm infant with early onset infection

Abstract

Early onset infection (EOI) in preterm infants <32 weeks gestational age (GA) is associated with a high mortality rate and the development of severe acute and long-term complications. The pathophysiology of EOI is not fully understood and clinical and laboratory signs of early onset infections in this patient cohort are often not conclusive. Thus, the aim of this study was to identify signatures characterizing preterm infants with EOI by using genome-wide gene expression (GWGE) analyses from umbilical arterial blood of preterm infants. This prospective cohort study was conducted in preterm infants <32 weeks GA. GWGE analyses using CodeLink human microarrays were performed from umbilical arterial blood of preterm infants with and without EOI. GWGE analyses revealed differential expression of 292 genes in preterm infants with EOI as compared to infants without EOI. Infants with EOI could be further differentiated into two subclasses and were distinguished by the magnitude of the expression of genes involved in both neutrophil and T cell activation. A hallmark activity for both subclasses of EOI was a common suppression of genes involved in natural killer (NK) cell function, which was independent from NK cell numbers. Significant results were recapitulated in an independent validation cohort. Gene expression profiling may enable early and more precise diagnosis of EOI in preterm infants.

Key message

Gene expression (GE) profiling at birth characterizes preterm infants with EOI.

GE analysis indicates dysregulation of NK cell activity.

NK cell activity at birth may be a useful marker to improve early diagnosis of EOI.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-016-1466-4) contains supplementary material, which is available to authorized users.

Response to bronchodilators in very preterm infants with evolving bronchopulmonary dysplasia

BACKGROUND

There are few effective and safe medications to treat very low birth weight (VLBW) infants with evolving BPD. Bronchodilators are often given to patients who have clinical signs of reactive airway disease, but there is not enough information regarding their effectiveness within this population.

OBJECTIVE

To quantify the pulmonary function response to bronchodilator therapy in a population of VLBW infants with evolving BPD.

DESIGN/METHODS

This is a retrospective analysis of an ongoing large database of pulmonary function tests (PFTs) in premature infants. We reviewed pre and post bronchodilator PFTs ordered by a physician due to concern for reactive airway disease. Inclusion criteria: BW< 1500 grams; > 14 days of age; admission diagnosis of respiratory distress syndrome; requiring ongoing oxygen, CPAP or ventilator support at the time of PFT. PFTs were done prior to albuterol therapy and repeated 30 minutes after the therapy was given. PFTs included the measurement of passive respiratory mechanics with the single breath occlusion technique, including passive respiratory compliance (Crs), resistance (Rrs) and tidal volume (Vt).

RESULTS

40 VLBW infants (mean gestation of 27.4 weeks; mean birth weight (BW) of 848 grams) were identified as having PFTs. 29 of these patients had a BW of ≤ 1000 grams. Patients were studied at a mean corrected gestational age of 34.9 weeks. 29 of 40 were extubated at the time of the PFT. Of these patients, 21 (52.5%) had a decrease in Rrs of ≥10%. From the other 19 patients, 5 (12.5%) had a decrease of 0 to < 10% in Rrs, 14 (35%) showed no response to therapy. There was no significant difference in Crs between groups.

The effect of prenatal maternal infection on respiratory function in mouse offspring: evidence for enhanced chemosensitivity

Systemic maternal inflammation is implicated in preterm birth and bronchopulmonary dysplasia (BPD) and may induce morbidities including reduced pulmonary function, sleep-disordered breathing, and cardiovascular disorders. Here we test the hypothesis that antenatal maternal inflammation per se causes altered alveolar development and increased chemoreflex sensitivity that persists beyond infancy. Pregnant C57BL/6 mice were administered lipopolysaccharide (LPS) (150 μg/kg ip) to induce maternal inflammation or saline (SHAM) at embryonic day 16 (randomized). Pups were weighed daily. On days 7, 28, and 60 (D07, D28, and D60), unrestrained wholebody plethysmography quantified ventilation and chemoreflex responses to hypoxia (10%), hypercapnia (7%), and asphyxia (hypoxic hypercapnia). Lungs were harvested to quantify alveolar number, size, and septal thickness. LPS pups had reduced baseline ventilation per unit bodyweight (∼40%, P < 0.001) vs. SHAM. LPS increased ventilatory responses to hypoxia (D07: 66% vs. 28% increase in ventilation; P < 0.001) hypercapnia (170% vs. 88%; P < 0.001), and asphyxia (249% vs. 154%; P < 0.001); hypersensitive hypoxic responsiveness persisted until D60 (P < 0.001). LPS also increased apnea frequency (P < 0.01). LPS caused thicker alveolar septae (D07, P < 0.001), diminished alveolar number (D28, P < 0.001) vs. SHAM, but effects were minimal by D60. Pups delivered from mothers exposed to antenatal inflammation exhibit deficits in lung structure and hypersensitive responses to respiratory stimuli that persist beyond the newborn period. Antenatal inflammation may contribute to impaired gas exchange and unstable breathing in newborn infants and adversely affect long-term health.

Animal models of bronchopulmonary dysplasia. The term mouse models

The etiology of bronchopulmonary dysplasia (BPD) is multifactorial, with genetics, ante- and postnatal sepsis, invasive mechanical ventilation, and exposure to hyperoxia being well described as contributing factors. Much of what is known about the pathogenesis of BPD is derived from animal models being exposed to the environmental factors noted above. This review will briefly cover the various mouse models of BPD, focusing mainly on the hyperoxia-induced lung injury models. We will also include hypoxia, hypoxia/hyperoxia, inflammation-induced, and transgenic models in room air. Attention to the stage of lung development at the timing of the initiation of the environmental insult and the duration of lung injury is critical to attempt to mimic the human disease pulmonary phenotype, both in the short term and in outcomes extending into childhood, adolescence, and adulthood. The various indexes of alveolar and vascular development as well as pulmonary function including pulmonary hypertension will be highlighted. The advantages (and limitations) of using such approaches will be discussed in the context of understanding the pathogenesis of and targeting therapeutic interventions to ameliorate human BPD.

Lipopolysaccharide induces up-regulation of TGF-α through HDAC2 in a rat model of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is characterized by alveolar simplification with decreased alveolar number and increased airspace. Previous studies suggested that transforming growth factor-α (TGF-α) may contribute to arrested alveolar development in BPD. Histone deacetylases (HDACs) control cellular signaling and gene expression. HDAC2 is crucial for suppression of inflammatory gene expression. Here we investigated whether HDAC2 was involved in the arrest of alveolarization, as well as the ability of HDAC2 to regulate TGF-α expression in a rat model of BPD induced by intra-amniotic injection of lipopolysaccharide (LPS). Results showed that LPS exposure led to a suppression of both HDAC1 and HDAC2 expression and activity, induced TGF-α expression, and disrupted alveolar morphology. Mechanistic studies showed that overexpression of HDAC2, but not HDAC1, suppressed LPS-induced TGF-α expression. Moreover, the HDAC inhibitor TSA or downregulation of HDAC2 by siRNA both significantly increased TGF-α expression in cultured myofibroblasts. Finally, preservation of HDAC activity by theophylline treatment improved alveolar development and attenuated TGF-α release. Together, these findings indicate that attenuation of TGF-α-mediated effects in the lung by enhancing HDAC2 may have a therapeutic effect on treating BPD.

Anti-inflammatory effect of caffeine is associated with improved lung function after lipopolysaccharide-induced amnionitis

BACKGROUND

Although caffeine enhances respiratory control and decreases the need for mechanical ventilation and resultant bronchopulmonary dysplasia, it may also have anti-inflammatory properties in protecting lung function.

OBJECTIVE

We hypothesized that caffeine improves respiratory function via an anti-inflammatory effect in lungs of a lipopolysaccharide (LPS)-induced pro-inflammatory amnionitis rat pup model.

METHODS

Caffeine was given orally (10 mg/kg/day) from postnatal day (p)1 to p14 to pups exposed to intra-amniotic LPS or normal saline. Expression of IL-1β was assessed in lung homogenates at p8 and p14, and respiratory system resistance (Rrs) and compliance (Crs) as well as CD68 cell counts and radial alveolar counts were assessed at p8.

RESULTS

In LPS-exposed rats, IL-1β and CD68 cell counts both increased at p8 compared to normal saline controls. These increases in pro-inflammatory markers were no longer present in caffeine-treated LPS-exposed pups. Rrs was higher in LPS-exposed pups (4.7 ± 0.9 cm H2O/ml·s) at p8 versus controls (1.6 ± 0.3 cm H2O/ml·s, p < 0.01). LPS-exposed pups no longer exhibited a significant increase in Rrs (2.8 ± 0.5 cm H2O/ml·s) after caffeine. Crs did not differ significantly between groups, although radial alveolar counts were lower in both groups of LPS-exposed pups.

CONCLUSIONS

Caffeine promotes anti-inflammatory effects in the immature lung of prenatal LPS-exposed rat pups associated with improvement of Rrs, suggesting a protective effect of caffeine on respiratory function via an anti-inflammatory mechanism.

Cyclooxygenase-2 in newborn hyperoxic lung injury

Supraphysiological O2 concentrations, mechanical ventilation, and inflammation significantly contribute to the development of bronchopulmonary dysplasia (BPD).Exposure of newborn mice to hyperoxia causes inflammation and impaired alveolarization similar to that seen in infants with BPD.Previously, we demonstrated that pulmonary cyclooxygenase-2 (COX-2) protein expression is increased in hyperoxia-exposed newborn mice.The present studies were designed to define the role of COX-2 in newborn hyperoxic lung injury.We tested the hypothesis that attenuation of COX-2 activity would reduce hyperoxia-induced inflammation and improve alveolarization.Newborn C3H/HeN micewere injected daily with vehicle, aspirin (nonselective COX-2 inhibitor), or celecoxib (selective COX-2 inhibitor) for the first 7 days of life.Additional studies utilized wild-type (C57Bl/6, COX-2(+/+)), heterozygous (COX-2(+/-)), and homozygous (COX-2(-/-)) transgenic mice.Micewere exposed to room air (21% O2) or hyperoxia (85% O2) for 14 days.Aspirin-injected and COX-2(-/-) pups had reduced levels of monocyte chemoattractant protein (MCP-1) in bronchoalveolar lavage fluid (BAL).Both aspirin and celecoxib treatment reduced macrophage numbers in the alveolar walls and air spaces.Aspirin and celecoxib treatment attenuated hyperoxia-induced COX activity, including altered levels of prostaglandin (PG)D2 metabolites.Decreased COX activity, however, did not prevent hyperoxia-induced lung developmental deficits.Our data suggest thatincreased COX-2 activity may contribute to proinflammatory responses, including macrophage chemotaxis, during exposure to hyperoxia.Modulation of COX-2 activity may be a useful therapeutic target to limit hyperoxia-induced inflammation in preterm infants at risk of developing BPD.

Antenatal betamethasone attenuates intrauterine infection-aggravated hyperoxia-induced lung injury in neonatal rats

BACKGROUND

Intrauterine infection can exacerbate postnatal hyperoxic lung injury. We hypothesized that antenatal betamethasone treatment attenuates hyperoxic lung injury aggravated by intrauterine infection in neonatal rats.

METHODS

Newborn Sprague-Dawley rats were divided into eight experimental groups according to (i) whether rats were exposed to normoxia (N) or hyperoxia (H, 85% oxygen) from postnatal day (P)1 to P14, (ii) whether antenatal betamethasone (0.2 mg/dose) or vehicle was administered to pregnant rats at gestation days (E)19 and E20, and (iii) whether intrauterine infection was induced or not antenatally. Intrauterine infection was induced by intracervical inoculation of Escherichia coli into pregnant rats on E19. We measured cytokine levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β in P1 rat lungs and performed morphometric analyses and assessed inflammatory responses in lung tissue and bronchoalveolar lavage (BAL) at P14 by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) staining and measurement of myeloperoxidase activity, collagen, and cytokine levels.

RESULTS

Cytokine levels in P1 rat lungs were increased by intrauterine infection, and these increases were attenuated by antenatal betamethasone. Hyperoxic lung injuries, indicated by morphometric changes and an inflammatory response in the lung and BAL fluid, were aggravated by intrauterine infection at P14. This aggravation was significantly attenuated by antenatal betamethasone.

CONCLUSION

Antenatal betamethasone attenuated aggravated hyperoxic lung injuries induced by intrauterine infection in neonatal rats via its anti-inflammatory actions.

Respiratory morbidity at follow-up of small-for-gestational-age infants born very prematurely

BACKGROUND

The aim of this study was to determine whether small-for-gestational-age (SGA) infants born very prematurely had increased respiratory morbidity in the neonatal period and at follow-up.

METHODS

Data were examined from infants recruited into the United Kingdom Oscillation Study (UKOS). Of the 797 infants who were born at <29 wk of gestational age, 174 infants were SGA. Overall, 92% were exposed to antenatal corticosteroids and 97% received surfactant; follow-up data at 22-28 mo were available for 367 infants.

RESULTS

After adjustment for gestational age and sex, SGA infants had higher rates of supplementary oxygen dependency at 36 wk postmenstrual age (odds ratio (OR): 3.23; 95% confidence interval: 2.03, 5.13), pulmonary hemorrhage (OR: 3.07; 95% CI: 1.82, 5.18), death (OR: 3.32; 95% CI: 2.13, 5.17), and postnatal corticosteroid requirement (OR: 2.09; 95% CI: 1.35, 3.23). After adjustment for infant and respiratory morbidity risk factors, a lower mean birth weight z-score was associated with a higher prevalence of respiratory admissions (OR: 1.40; 95% CI: 1.03, 1.88 for 1 SD change in z-score), cough (OR: 1.28; 95% CI: 1.00, 1.65), and use of chest medicines (OR: 1.32; 95% CI: 1.01, 1.73).

CONCLUSION

SGA infants who were born very prematurely, despite routine use of antenatal corticosteroids and postnatal surfactant, had increased respiratory morbidity at follow-up, which was not due to poor neonatal outcome.

Mechanisms of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease affecting premature infants with long term effect on lung function into adulthood. Multiple factors are involved in the development of BPD. This review will summarize the different mechanisms leading to this disease and highlight recent bench and clinical research targeted at understanding the role of the mesenchyme (both its cellular and extracellular components) in the pathogenesis of BPD.

Respiratory hospitalisation of infants supplemented with docosahexaenoic acid as preterm neonates

AIM

To determine the effect of neonatal docosahexaenoic acid (DHA) supplementation in preterm infants on later respiratory-related hospitalisations.

METHODS

We enrolled 657 infants in a multicentre, randomised, controlled trial designed to study the long-term efficacy of higher dose dietary DHA in infants born <33 weeks' gestation. Treatment was with high DHA (∼1%) compared with standard DHA (∼0.3%) in breast milk or formula, given from the first week of life to term equivalent. Parent-reported hospital admissions to 18 months corrected age were recorded. The proportion of children hospitalised for lower respiratory tract (LRT) conditions and the mean number of hospitalisations per infant were determined.

RESULTS

Twenty-three per cent (154/657) of infants were hospitalised for LRT conditions. Seventy-three per cent (173/238) of admissions were for bronchiolitis. There was no significant effect of higher DHA on the proportion of infants admitted for LRT conditions (high DHA 22% vs. standard DHA 25%, adjusted relative risk 0.92, 95% confidence interval (CI) 0.68-1.24, P = 0.57) or in the mean number of admissions per infant (high DHA 0.34, standard DHA 0.38, adjusted ratio of means 0.91, 95% CI 0.63-1.32, P = 0.62). The sexes responded differently to treatment (interaction P = 0.046), with reduced admissions in boys given high DHA, but this was not statistically significant (high DHA 19%, standard DHA 28%, adjusted relative risk 0.69, 95% CI 0.46-1.04, P = 0.08).

CONCLUSIONS

Hospitalisation for LRT problems in the first 18 months for preterm infants was not reduced by neonatal supplementation with 1% DHA.

Lung injury in preterm neonates: the role and therapeutic potential of stem cells

Continuous improvements in perinatal care have allowed the survival of ever more premature infants, making the task of protecting the extremely immature lung from injury increasingly challenging. Premature infants at risk of developing chronic lung disease or bronchopulmonary dysplasia (BPD) are now born at the late canalicular stage of lung development, just when the airways become juxtaposed to the lung vasculature and when gas-exchange becomes possible. Readily available strategies, including improved antenatal management (education, regionalization, steroids, and antibiotics), together with exogenous surfactant and exclusive/early noninvasive ventilatory support, will likely decrease the incidence/severity of BPD over the next few years. Nonetheless, because of the extreme immaturity of the developing lung, the extent to which disruption of lung growth after prematurity and neonatal management lead to an earlier or more aggravated decline in respiratory function in later life is a matter of concern. Consequently, much more needs to be learned about the mechanisms of lung development, injury, and repair. Recent insight into stem cell biology has sparked interest for stem cells to repair damaged organs. This review summarizes the exciting potential of stem cell-based therapies for lung diseases in general and BPD in particular.

Initial respiratory support of preterm infants: the role of CPAP, the INSURE method, and noninvasive ventilation

This article explores the potential benefits and risks for the various approaches to the initial respiratory management of preterm infants. The authors focus on the evidence for the increasingly used strategies of initial respiratory support of preterm infants with continuous positive airway pressure (CPAP) beginning in the delivery room or very early in the hospital course and blended strategies involving the early administration of surfactant replacement followed by immediate extubation and stabilization on CPAP. Where possible, the evidence referenced in this review comes from individual randomized controlled trials or meta-analyses of those trials.

Clinical effectiveness and safety of permissive hypercapnia

Experimental and clinical data indicate that ventilator strategies with permissive hypercapnia may reduce lung injury by a variety of mechanisms. Seven randomized controlled trials in preterm neonates suggest that permissive hypercapnia started early, before the initiation of mechanical ventilation (in conjunction with continuous positive airway pressure), followed by prolonged permissive hypercapnia if mechanical ventilation is needed is an alternative to early ventilation and surfactant. Permissive hypercapnia may improve pulmonary outcomes and survival.

Risk factors for post-neonatal intensive care unit discharge mortality among extremely low birth weight infants

OBJECTIVE

The study goal was to evaluate maternal and neonatal risk factors associated with post-neonatal intensive care unit (NICU) discharge mortality among extremely low birth weight (ELBW) infants.

STUDY DESIGN

This is a retrospective analysis of ELBW (<1000 g) and <27 weeks' gestational age infants born in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network sites between January 2000 and June 2007. Infants were tracked until death or 18 to 22 months' corrected age. Infants who died between NICU discharge and the 18- to 22-month follow-up visit were classified as post-NICU discharge mortality (P-NDM). Association of maternal and infant risk factors with P-NDM was determined using logistic regression analysis. A prediction model with 6 significant predictors was developed and validated.

RESULTS

There were 5364 infants who survived to NICU discharge; 557 (10%) infants were lost to follow-up, and 107 infants died following NICU discharge. P-NDM rate was 22.3 per 1000 ELBW infants. In the prediction model, African American race, unknown maternal health insurance, and hospital stay ≥ 120 days significantly increased risk, and maternal exposure to intrapartum antibiotics was associated with decreased risk of P-NDM.

CONCLUSION

We identified African American race, unknown medical insurance, and prolonged NICU stay as risk factors associated with P-NDM among ELBW infants.

Human amnion epithelial cells reduce ventilation-induced preterm lung injury in fetal sheep

OBJECTIVE

The objective of the study was to explore whether human amnion epithelial cells (hAECs) can mitigate ventilation-induced lung injury.

STUDY DESIGN

An established in utero ovine model of ventilation-induced lung injury was used. At day 110 of gestation, singleton fetal lambs either had sham in utero ventilation (IUV) (n = 4), 12 hours of IUV alone (n = 4), or 12 hours of IUV and hAEC administration (n = 5). The primary outcome, structural lung injury, was assessed 1 week later.

RESULTS

Compared with sham controls, IUV alone was associated with significant lung injury: increased collagen (P = .03), elastin (P = .02), fibrosis (P = .02), and reduced secondary-septal crests (P = .009). This effect of IUV was significantly mitigated by the administration of hAECs: less collagen (P = .03), elastin (P = .04), fibrosis (P = .02), normalized secondary-septal crests (P = .02). The hAECs were immunolocalized within the fetal lung and had differentiated into type I and II alveolar cells.

CONCLUSION

The hAECs mitigate ventilation-induced lung injury and differentiated into alveolar cells in vivo.

Definition and outpatient management of the very low-birth-weight infant with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), also known as chronic lung disease of prematurity, is the major cause of pulmonary disease in infants. The pathophysiology and management of BPD have evolved over the past four decades as improved neonatal intensive care unit (NICU) modalities have increased survival rates. The likelihood for developing BPD increases with the degree of prematurity and reaches 25-35% in very low-birth-weight and extremely low-birth-weight infants. BPD affects many organ systems, and infants with BPD are at increased risk for rehospitalization and numerous complications following NICU discharge. The management of BPD and medically related problems, particularly during the first 2 years of life, remains a continuing challenge for parents and healthcare providers. It is important that a multidisciplinary team consisting of the neonatologist/attending physician, primary care physician, and other specialized support staff work in concert and meet regularly to provide continuity of care and accurate patient assessments.

Lipopolysaccharide disrupts the directional persistence of alveolar myofibroblast migration through EGF receptor

Bronchopulmonary dysplasia (BPD) is characterized by alveolar simplification with decreased alveolar number and increased airspace size. Formation of alveoli involves a process known as secondary septation triggered by myofibroblasts. This study investigated the underlying mechanisms of altered lung morphogenesis in a rat model of BPD induced by intra-amniotic injection of lipopolysaccharide (LPS). Results showed that LPS disrupted alveolar morphology and led to abnormal localization of myofibroblasts in the lung of newborn rats, mostly in primary septa with few in secondary septa. To identify potential mechanisms, in vitro experiments were carried out to observe the migration behavior of myofibroblasts. The migration speed of lung myofibroblasts increased with LPS treatment, whereas the directional persistence decreased. We found that LPS induced activation of EGFR and overexpression of its ligand, TGF-α in myofibroblasts. AG1478, an EGFR inhibitor, abrogated the enhanced locomotivity of myofibroblasts by LPS and also increased the directional persistence of myofibroblast migration. Myofibroblasts showed a high asymmetry of phospho-EGFR localization, which was absent after LPS treatment. Application of rhTGF-α to myofibroblasts decreased the directional persistence. Our findings indicated that asymmetry of phospho-EGFR localization in myofibroblasts was important for cell migration and its directional persistence. We speculate that LPS exposure disrupts the asymmetric localization of phospho-EGFR, leading to decreased stability of cell polarity and final abnormal location of myofibroblasts in vivo, which is critical to secondary septation and may contribute to the arrested alveolar development in BPD.

A comprehensive approach to the prevention of bronchopulmonary dysplasia

The current bronchopulmonary dysplasia (BPD) is seen in infants born extremely premature, with less severe respiratory distress syndrome (RDS) and who received prenatal steroids-"new BPD". The pathophysiology of BPD is based on an impairment of lung maturation with prenatal and postnatal multi-hit insults and genetic susceptibility. This multifactorial pathophysiology of BPD suggests that no single "magic bullet" will prevent it. Thus, to avoid BPD we need to implement a complex and comprehensive strategy. This strategy is based on ventilatory and non-ventilatory measures. The ventilatory route allows an individualized endotracheal intubation approach. Early lung recruitment with nasal respiratory support (nasal continuous positive airway pressure [NCPAP] or nasal intermittent positive pressure ventilation [NIPPV] / synchronized NIPPV [SNIPPV]) and the INSURE (intubation, surfactant and early extubation) approach are discussed. Initial treatment with NCPAP did not reduce the rate of BPD compared to endotracheal ventilation and surfactant administration. While NIPPV/SNIPPV may have short-term advantages over NCPAP, the effect on BPD needs to be further studied. During hospitalization the respiratory goals should aim for adequate oxygenation, permissive hypercapnia, and gentle ventilation. However, these goals were found to have short-term benefits but did not reduce significantly the rate of BPD. Selective use of a short course of low dose corticosteroids can be considered after the first or second week of life in infants who are unable to be weaned from the ventilator and are at high risk for BPD. Non-ventilatory measures include early nutritional support with fluid restriction, caffeine and consideration of vitamin A. Hemodynamic significant patent ductus arteriosus (PDA) may be associated with BPD, but medical or surgical treatment of PDA were not shown to decrease BPD. Each component and the strategy as a whole needs to be further studied in large randomized prospective studies or by meta-analyses, especially in the target population of extremely premature infants who are the most prone to BPD.

Intrauterine growth restriction decreases pulmonary alveolar and vessel growth and causes pulmonary artery endothelial cell dysfunction in vitro in fetal sheep

Intrauterine growth restriction (IUGR) increases the risk for bronchopulmonary dysplasia (BPD). Abnormal lung structure has been noted in animal models of IUGR, but whether IUGR adversely impacts fetal pulmonary vascular development and pulmonary artery endothelial cell (PAEC) function is unknown. We hypothesized that IUGR would decrease fetal pulmonary alveolarization, vascular growth, and in vitro PAEC function. Studies were performed in an established model of severe placental insufficiency and IUGR induced by exposing pregnant sheep to elevated temperatures. Alveolarization, quantified by radial alveolar counts, was decreased 20% (P < 0.005) in IUGR fetuses. Pulmonary vessel density was decreased 44% (P < 0.01) in IUGR fetuses. In vitro, insulin increased control PAEC migration, tube formation, and nitric oxide (NO) production. This response was absent in IUGR PAECs. VEGFA stimulated tube formation, and NO production also was absent. In control PAECs, insulin increased cell growth by 68% (P < 0.0001). Cell growth was reduced in IUGR PAECs by 29% at baseline (P < 0.01), and the response to insulin was attenuated (P < 0.005). Despite increased basal and insulin-stimulated Akt phosphorylation in IUGR PAECs, endothelial NO synthase (eNOS) protein expression as well as basal and insulin-stimulated eNOS phosphorylation were decreased in IUGR PAECs. Both VEGFA and VEGFR2 also were decreased in IUGR PAECs. We conclude that fetuses with IUGR are characterized by decreased alveolar and vascular growth and PAEC dysfunction in vitro. This may contribute to the increased risk for adverse respiratory outcomes and BPD in infants with IUGR.

Respiratory morbidity, healthcare utilisation and cost of care at school age related to home oxygen status

The aim of the study was to determine whether respiratory morbidity, lung function, healthcare utilisation and cost of care at school age in prematurely born children who had bronchopulmonary dysplasia (BPD) were influenced by use of supplementary oxygen at home after neonatal intensive care unit discharge. Healthcare utilisation and cost of care in years 5 to 7 and respiratory morbidity (parent-completed respiratory questionnaire) and lung function measurements at least at age 8 years were assessed in 160 children. Their median gestational age was 27 (range 22-31) weeks and 65 of them had received supplementary oxygen when discharged home (home oxygen group). The home oxygen group had more outpatient attendances (p = 0.0168) and respiratory-related outpatient attendances (p = 0.0032) with greater related cost of care (p = 0.0186 and p = 0.0030, respectively), their cost of care for prescriptions (p = 0.0409) and total respiratory related cost of care (p = 0.0354) were significantly greater. There were, however, no significant differences in cough, wheeze or lung function results between the two groups.

CONCLUSION

Prematurely born children who had BPD and supplementary oxygen at home after discharge had increased healthcare utilisation at school age. Whether such children require greater follow, in the absence of excess respiratory morbidity, merits investigation.

ACE gene polymorphism in premature neonates with respiratory distress syndrome

The purpose of this study was to investigate the relationship between angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism and respiratory distress syndrome (RDS) in premature neonates. The patient group consisted of 101 premature neonates born before 37 weeks of gestation and diagnosed as RDS. The control group consisted of 100 premature neonates born before 37 weeks of gestation, but was not diagnosed as RDS. Genomic DNA from patients and controls was analyzed by polymerase chain reaction. D/D genotype was significantly higher in patient group (60.4% patients vs. 37.0% controls, p<0.05), whereas in the controls I/D genotype was markedly higher (33.7% patients vs. 61.0% controls, p<0.05). However, no marked change was observed with I/I genotype (5.9% patients vs. 2.0% controls). A significant increase of D alleles was observed in patients, whereas I allele was higher in controls (p<0.05). These results demonstrated the existence of higher frequency of the D/D genotype and D allele in premature neonates with RDS. These data may suggest that carriers of the D/D genotype and D allele are at increased risk of RDS development in premature neonates.

High plasma cytokine levels, white matter injury and neurodevelopment of high risk preterm infants: assessment at two years

BACKGROUND

Controversy exists regarding association of high levels of proinflammatory cytokines, neonatal morbidities and poor neurodevelopment outcome in very low birth weight infants.

OBJECTIVE

To determine association between severity of early inflammatory response and neurodevelopment outcome in high risk very low birth weight infants.

METHODS

Sixty-two very preterm infants with high risk for early-onset sepsis were followed up to 24 months corrected age. Blood sample was collected for IL-6, IL-8, IL-10, IL-1β, and TNF-α analysis. Neurodevelopment outcome by Bayley Scales of Infant Development II was assessed at 22 to 24 months. Magnetic Resonance Image was performed at least once during the first 12 months.

RESULTS

In 24 (38.7%) MDI was <85, and 16 (25.8%) had PDI<85. Low birth weight was significantly associated with low MDI, and birth weight and periventricular leukomalacia were significantly associated with low PDI by multiple regression analysis. After controlling for birth weight and gestational age, none of the studied variables was associated with low MDI, and only periventricular leukomalacia with low PDI. Each additional 100g in the birth weight reduced the probability of low MDI and PDI scores in 14%.

CONCLUSIONS

There was no association of high cytokines plasma levels with poor neurodevelopment outcome at 22 to 24 months' corrected age, suggesting that elevations of plasma proinflammatory cytokines early in life do not play an important role in pathophysiology of brain injury in high risk preterm infants.

Chorioamnionitis, respiratory distress syndrome and bronchopulmonary dysplasia in extremely low birth weight infants

OBJECTIVE

To determine if histologic chorioamnionitis (HC) in the presence of respiratory distress syndrome (RDS) augments adverse pulmonary outcomes in extremely low birth weight (ELBW) infants.

STUDY DESIGN

We retrospectively identified 184 ELBW infants who were born at and admitted to the neonatal intensive care units between June 2005 and June 2009.

RESULTS

The mean gestational age of the cases was 27 ± 2 weeks, and the mean birth weight was 791 ± 147 g. A total of 88% (161/184) of patients developed bronchopulmonary dysplasia (BPD). HC was observed in 71 of 238 infants (39%). When infants were divided on the basis of the presence or absence of HC and RDS, the incidence of moderate or severe BPD and duration of oxygen requirement were greater in the HC+RDS+ group than in the HC-RDS+ or HC+RDS- groups. The combination of prenatal (HC) and postnatal (RDS) injuries increased significantly the risk for BPD. In the multivariate analysis, the significant predictors of developing BPD were low gestational age (odds ratio (OR), 0.6; confidence interval (CI), 0.4 to 0.7) and exposure to both HC and RDS (OR, 4.7; CI, 1.1 to 20.2).

CONCLUSION

The HC and RDS work synergistically to induce lung injury in ELBW infants. Chorioamnionitis may interact with RDS to further increase the risk of BPD, despite either HC or RDS could not show independent significant association with BPD.