Pitfalls, problems, and progress in bronchopulmonary dysplasia

Stem cell-derived extracellular vesicles: a potential intervention for Bronchopulmonary Dysplasia

Despite advances in neonatal care, the incidence of Bronchopulmonary Dysplasia (BPD) remains high among extreme preterm infants. The pathogenesis of BPD is multifactorial, with inflammation playing a central role. There is strong evidence that stem cell therapy reduces inflammatory changes and restores normal lung morphology in animal models of hyperoxia-induced lung injury. These therapeutic effects occur without significant engraftment of the stem cells in the host lung, suggesting more of a paracrine mechanism mediated by their secretome. In addition, there are multiple concerns with stem cell therapy which may be alleviated by administering only the effective vesicles instead of the cells themselves. Extracellular vesicles (EVs) are cell-derived components secreted by most eukaryotic cells. They can deliver their bioactive cargo (mRNAs, microRNAs, proteins, growth factors) to recipient cells, which makes them a potential therapeutic vehicle in many diseases, including BPD. The following review will highlight recent studies that investigate the effectiveness of EVs derived from stem cells in preventing or repairing injury in the preterm lung, and the potential mechanisms of action that have been proposed. Current limitations will also be discussed as well as suggestions for advancing the field and easing the transition towards clinical translation in evolving or established BPD. IMPACT: Extracellular vesicles (EVs) derived from stem cells are a potential intervention for neonatal lung diseases. Their use might alleviate the safety concerns associated with stem cell therapy. This review highlights recent studies that investigate the effectiveness of stem cell-derived EVs in preclinical models of bronchopulmonary dysplasia. It adds to the existing literature by elaborating on the challenges associated with EV research. It also provides suggestions to advance the field and ease the transition towards clinical applications. Optimizing EV research could ultimately improve the quality of life of extreme preterm infants born at vulnerable stages of lung development.

Exploring research trends and hotspots on oxidative stress and bronchopulmonary dysplasia: Insights from bibliometric and visualized study

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a severe chronic lung disease primarily affecting premature infants, often resulting from prolonged mechanical ventilation and oxygen therapy. Oxidative stress plays a critical role in the pathogenesis of BPD, contributing to lung injury, inflammation, and impaired lung development. Despite extensive research, there is a need to systematically map out the research trends and hotspots in this field to inform future studies and therapeutic strategies.

METHODS

This study utilized bibliometric and visualized analysis to explore global research trends and hotspots on oxidative stress and BPD from 2004 to 2024. A comprehensive literature search was conducted in the Web of Science Core Collection, focusing on publications related to oxidative stress and BPD. Tools such as VOSviewer, Citespace, and the R package Bibliometrix were employed to analyze Coauthorship, co-citation, and keyword co-occurrence networks, as well as to identify emerging research fronts and influential studies.

RESULTS

The analysis identified 597 relevant publications, showing a steady increase in research output over the 20-year period, with a significant surge in the last decade. The United States led in research contributions, followed by China and Germany, with notable collaborations among these countries. Coauthorship analysis highlighted key research institutions, such as Harvard University and the University of California, as central nodes in the research network. Thematic clustering revealed five major research areas: antioxidant mechanisms, inflammation, molecular pathways, lung development, and therapeutic interventions. The keyword co-occurrence analysis showed a shift in research focus over time. Early studies concentrated on basic pathophysiological mechanisms, while recent research has increasingly focused on advanced molecular techniques, such as gene expression and targeted therapies. Notably, the study identified emerging research hotspots, including the role of extracellular vesicles and cellular senescence in BPD, as well as the potential therapeutic applications of antioxidants like superoxide dismutase mimetics.

CONCLUSION

This bibliometric study provides a comprehensive overview of the research landscape on oxidative stress and BPD, identifying key trends, influential authors, and emerging research topics. The findings underscore the importance of continued research in this field, particularly in translating basic scientific insights into clinical applications to improve outcomes for infants affected by BPD. The study also highlights potential areas for future investigation, including the development of novel therapeutic strategies targeting oxidative stress in BPD.

The potential therapeutic effect of human umbilical cord mesenchymal stem cell-derived exosomes in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of preterm infants, with its incidence rising due to improved survival rates of these infants. BPD results from a combination of prenatal and postnatal factors, such as mechanical ventilation, oxygen toxicity, and infections, all of which significantly impact the prognosis and growth of affected infants. Current treatment options for BPD are largely supportive and do not address the underlying pathology. Exosomes are cell-derived bilayer-enclosed membrane structures enclosing proteins, lipids, RNAs, growth factors, cytokines and metabolites. They have become recognized as crucial regulators of intercellular communication in various physiological and pathological processes. Previous studies have revealed the therapeutic potential of human umbilical cord mesenchymal stem cells-derived exosomes (HUCMSCs-Exos) in promoting tissue repair and regeneration. Therefore, HUCMSCs-Exos maybe a promising and effective therapeutic modality for BPD. In this review, we firstly provide a comprehensive overview of BPD, including its etiology and the mechanisms of lung injury. Then we detail the isolation, characterization, and contents of HUCMSCs-Exos, and discuss their potential mechanisms of HUCMSCs-Exos in BPD treatment. Additionally, we summarize current clinical trials and discuss the challenges in translating these findings from bench to bedside. This review aims to lay the groundwork for future clinical applications of HUCMSCs-Exos in treating BPD.

Strategies for the prevention of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. The pathogenesis of BPD is multifactorial, and the clinical phenotype is variable. Extensive research has improved the current understanding of the factors contributing to BPD pathogenesis. However, effectively preventing and managing BPD remains a challenge. This review aims to provide an overview of the current evidence regarding the prevention of BPD in preterm infants, offering practical insights for clinicians.

Measurement of lung oxygenation by near-infrared spectroscopy in preterm infants with bronchopulmonary dysplasia

INTRODUCTION

It has recently been reported that it is possible to monitor lung oxygenation (rSO2L) by near-infrared spectroscopy (NIRS) in preterm infants with respiratory distress syndrome (RDS). Thus, our aim was to assess the possibility of monitoring rSO2L in infants with evolving and established bronchopulmonary dysplasia (BPD) and to evaluate if rSO2L correlates with BPD severity and other oxygenation indices.

METHODS

We studied 40 preterm infants with gestational age ≤30 weeks at risk for BPD. Patients were continuously studied for 2 h by NIRS at 28 ± 7 days of life and 36 weeks ± 7 days of postmenstrual age.

RESULTS

rSO2L was similar at the first and second NIRS recordings (71.8 ± 7.2 vs. 71.4 ± 4.2%) in the overall population, but it was higher in infants with mild than in those with moderate-to-severe BPD at both the first (73.3 ± 3.1 vs. 71.2 ± 3.2%, p = .042) and second (72.3 ± 2.8 vs. 70.5 ± 2.8, p = .049) NIRS recording. A rSO2L cutoff value of 71.6% in the first recording was associated with a risk for moderate-to-severe BPD with a sensitivity of 66% and a specificity of 60%. Linear regression analysis demonstrated a significant positive relationship between rSO2L and SpO2/FiO2 ratio (p = .013) and a/APO2 (p = .004).

CONCLUSIONS

Monitoring of rSO2L by NIRS in preterm infants with evolving and established BPD is feasible and safe. rSO2L was found to be higher in infants with mild BPD, and predicts the risk for developing moderate-to-severe BPD and correlates with other indices of oxygenation.

A clinical informatics approach to bronchopulmonary dysplasia: current barriers and future possibilities

Bronchopulmonary dysplasia (BPD) is a complex, multifactorial lung disease affecting preterm neonates that can result in long-term pulmonary and non-pulmonary complications. Current therapies mainly focus on symptom management after the development of BPD, indicating a need for innovative approaches to predict and identify neonates who would benefit most from targeted or earlier interventions. Clinical informatics, a subfield of biomedical informatics, is transforming healthcare by integrating computational methods with patient data to improve patient outcomes. The application of clinical informatics to develop and enhance clinical therapies for BPD presents opportunities by leveraging electronic health record data, applying machine learning algorithms, and implementing clinical decision support systems. This review highlights the current barriers and the future potential of clinical informatics in identifying clinically relevant BPD phenotypes and developing clinical decision support tools to improve the management of extremely preterm neonates developing or with established BPD. However, the full potential of clinical informatics in advancing our understanding of BPD with the goal of improving patient outcomes cannot be achieved unless we address current challenges such as data collection, storage, privacy, and inherent data bias.

Trends in the Incidence of Bronchopulmonary Dysplasia after the Introduction of Neurally Adjusted Ventilatory Assist (NAVA)

OBJECTIVE

This study investigates the difference in the rates of bronchopulmonary dysplasia in very low birth weight infants before and after the introduction of neurally adjusted ventilatory assist (NAVA).

STUDY DESIGN

A retrospective cohort study comparing rates of Bronchopulmonary dysplasia (BPD) before and after implementation of NAVA. Eligibility criteria included all very low birth weight VLBW neonates needing ventilation. For analysis, each cohort was divided into three subgroups based on gestational age. Changes in the rate of BPD, length of stay, tracheostomy rates, invasive ventilator days, and home oxygen therapy were compared.

RESULTS

There were no differences in the incidence of BPD in neonates at 23-25 6/7 weeks' and 29-32 weeks' gestation between the two cohorts. A higher incidence of BPD was seen in the 26-28 5/7 weeks' gestation NAVA subgroup compared to controls (86% vs. 68%, p = 0.05). No significant difference was found for ventilator days, but infants in the 26-28 6/7 subgroup in the NAVA cohort had a longer length of stay (98 ± 34 days vs. 82 ± 24 days, p = 0.02), a higher percentage discharged on home oxygen therapy (45% vs. 18%, respectively, p = 0.006), and higher tracheostomy rates (3/36 vs. 0/60, p = 0.02), compared to the control group.

CONCLUSIONS

The NAVA mode was not associated with a reduction in BPD when compared to other modes of ventilation. Unexpected increases were seen in BPD rates, home oxygen therapy rates, tracheostomy rates, and the length of stay in the NAVA subgroup born at 26-28 6/7 weeks' gestation.

The value of hematocrit for predicting bronchopulmonary dysplasia in very low birth weight preterm infants

To determine hematocrit (HCT) and to identify independent risk factors for predicting bronchopulmonary dysplasia (BPD) in preterm infants with very low birth weight (VLBW) infants. This retrospective study included 296 premature infants with VLBW in the neonatal intensive care unit of the First Affiliated Hospital of the University of Science and Technology of China between January 2015 and December 2019. Maternal pregnant information and clinical information as well as hematological parameters of preterm babies were collected and compared. Then the maximum area under the curve of receiver operating characteristic curve was developed to estimate the predictive indicator in the blood. Finally, differential variables together with the predictive index were screened for multiple logistic regression analysis to determine independent prognostic factors for BPD. Infants were divided into a BPD group (134 cases) and a non-BPD group (162 cases). The area under the curve of HCT at postnatal 1 week was 0.737 with the sensitivity of 52.30 % and the specificity of 86.00%. Birth weight (BW) <1.12 kg, gestational age <28.4 weeks, newborn respiratory distress syndrome, mechanical ventilation ≥ 7 days, ventilation associated pneumonia, patent arterial duct, PaO2/FiO2 <300 mm Hg and HCT <0.455 at postnatal 1 week were risk factors for BPD of VLBW infants. HCT levels below 0.455 at 1 week after birth serve as a valuable indicator for the potential development of BPD.

A predictive model for prognosis in very low birth weight infants with late-onset sepsis

OBJECTIVES

This study aims to develop a predictive model to assess the probability of poor prognosis in very low birth weight infants (VLBWI) with late-onset sepsis (LOS).

METHODS

A total of 309 eligible VLBWI with LOS were included in the study. Logistic regression was used to determine prognostic factors for VLBWI with LOS. A nomogram incorporating these factors was created to predict the probability of poor prognosis. Poor prognosis includes death and survival with severe complications.

RESULTS

In the developmental cohort, the incidence of poor prognosis was 59.5% (147/247). Forward stepwise logistic regression analysis showed that HCO3, albumin (ALB), ionized calcium (iCa), blood urea nitrogen (BUN), gestational age (GA), and birth weight (BW) were independent predictors of poor prognosis in VLBWI with LOS. The predictive model showed good discrimination and calibration. In the developmental cohort, the prediction model had a sensitivity of 83.7%, a specificity of 74.0%, and a C-index of 0.845 (95% confidence interval: 0.795-0.894).

CONCLUSION

Our study identified independent predictors of poor prognosis in VLBWI with LOS and used them to construct a predictive model. This model can help clinicians to identify high-risk groups with poor prognosis early and provide important clinical reference information.

IMPACT

This article highlights the development of a predictive model to assess the probability of poor prognosis in very low birth weight infants with late-onset sepsis (LOS). The model constructed in this manuscript was the first model to predict the poor prognosis of VLBWI with LOS. We mean a poor prognosis that includes death and some severe complications that may lead to long-term disability. Clinicians can use the model's scoring results to assess a patient's condition and accurately identify the occurrence of poor prognosis.

Early Origins of Chronic Obstructive Pulmonary Disease: Prenatal and Early Life Risk Factors

The main risk factor for chronic obstructive pulmonary disease (COPD) is active smoking. However, a considerable amount of people with COPD never smoked, and increasing evidence suggests that adult lung disease can have its origins in prenatal and early life. This article reviews some of the factors that can potentially affect lung development and lung function trajectories throughout the lifespan from genetics and prematurity to respiratory tract infections and childhood asthma. Maternal smoking and air pollution exposure were also analyzed among the environmental factors. The adoption of preventive strategies to avoid these risk factors since the prenatal period may be crucial to prevent, delay the onset or modify the progression of COPD lung disease throughout life.

The Role of Insulin Receptor Substrate Proteins in Bronchopulmonary Dysplasia and Asthma: New Potential Perspectives

Insulin receptor substrates (IRSs) are proteins that are involved in signaling through the insulin receptor (IR) and insulin-like growth factor (IGFR). They can also interact with other receptors including growth factor receptors. Thus, they represent a critical node for the transduction and regulation of multiple signaling pathways in response to extracellular stimuli. In addition, IRSs play a central role in processes such as inflammation, growth, metabolism, and proliferation. Previous studies have highlighted the role of IRS proteins in lung diseases, in particular asthma. Further, the members of the IRS family are the common proteins of the insulin growth factor signaling cascade involved in lung development and disrupted in bronchopulmonary dysplasia (BPD). However, there is no study focusing on the relationship between IRS proteins and BPD yet. Unfortunately, there is still a significant gap in knowledge in this field. Thus, in this review, we aimed to summarize the current knowledge with the major goal of exploring the possible roles of IRS in BPD and asthma to foster new perspectives for further investigations.

Predictive Value of Ionized Calcium for Prognosis of Sepsis in Very Low Birth Weight Infants

Purpose

Previous studies have shown that ionized calcium (iCa) is strongly correlated with critical illnesses, including sepsis. However, there are few studies on the association of iCa levels and sepsis in very low birth weight infants (VLBWI). Therefore, the aim of this study was to investigate the role of iCa in assessing the severity of sepsis and in predicting the prognosis of sepsis in VLBWI.

Patients and Methods

249 eligible VLBWI with sepsis were included in the present study and were divided into good and poor prognosis groups according to prognosis. We collected complete laboratory and clinical data. The lowest iCa measured during the first 24h from sepsis onset was recorded, and the Pediatric Risk of Mortality (PRISM III) score was calculated for each newborn.

Results

Neonatal mortality was higher in the hypocalcemia group (32.80% vs 12.80%, P < 0.001), and iCa levels were negatively correlated with PRISM III scores (r= −0.819, P < 0.001). The result of multiple logistic regression analysis showed that iCa was an independent predictor of poor prognosis (odds ratio [OR]= 0.558, 95% confidence interval [CI], 0.406–0.768, P < 0.001). Furthermore, our data demonstrated that iCa was also an independent predictor for the occurrence of death in VLBWI with sepsis who have a poor prognosis (OR= 0.659, 95% CI, 0.445–0.977, P =0.038). ROC curve analysis showed that iCa had good discriminatory power in predicting the poor prognosis (AUC=0.739, 95% CI, 0.664–0.813, P <0.001) in VLBWI with sepsis.

Conclusion

iCa levels correlate with the severity of sepsis and can be an independent predictor of poor prognosis in VLBWI with sepsis.

Early severity prediction of BPD for premature infants from chest X-ray images using deep learning: A study at the 28th day of oxygen inhalation

BACKGROUND AND OBJECTIVE

Bronchopulmonary dysplasia is a common respiratory disease in premature infants. The severity is diagnosed at the 56th day after birth or discharge by analyzing the clinical indicators, which may cause the delay of the best treatment opportunity. Thus, we proposed a deep learning-based method using chest X-ray images of the 28th day of oxygen inhalation for the early severity prediction of bronchopulmonary dysplasia in clinic.

METHODS

We first adopted a two-step lung field extraction method by combining digital image processing and human-computer interaction to form the one-to-one corresponding image and label. The designed XSEG-Net model was then trained for segmenting the chest X-ray images, with the results being used for the analysis of heart development and clinical severity. Therein, Six-Point cardiothoracic ratio measurement algorithm based on corner detection was designed for the analysis of heart development; and the transfer learning of deep convolutional neural network models were used for the early prediction of clinical severities.

RESULTS

The dice and cross-entropy loss value of the training of XSEG-Net network reached 0.9794 and 0.0146. The dice, volumetric overlap error, relative volume difference, precision, and recall were used to evaluate the trained model in testing set with the result being 98.43 ± 0.39%, 0.49 ± 0.35%, 0.49 ± 0.35%, 98.67 ± 0.40%, and 98.20 ± 0.47%, respectively. The errors between the Six-Point cardiothoracic ratio measurement method and the gold standard were 0.0122 ± 0.0084. The deep convolutional neural network model based on VGGNet had the promising prediction performance, with the accuracy, precision, sensitivity, specificity, and F1 score reaching 95.58 ± 0.48%, 95.61 ± 0.55%, 95.67 ± 0.44%, 96.98 ± 0.42%, and 95.61±0.48%, respectively.

CONCLUSIONS

These experimental results of the proposed methods in lung field segmentation, cardiothoracic ratio measurement and clinic severity prediction were better than previous methods, which proved that this method had great potential for clinical application.

Vascular endothelial growth factor levels and bronchopulmonary dysplasia in preterm infants

BACKGROUND

Vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) regulate both vasculogenesis, the development of blood vessels from precursor cells, and angiogenesis, the formation of blood vessels from preexisting vessels. In the fetal lung, high-affinity receptors for VEGF are expressed mainly in alveolar epithelial cells and myocytes, suggesting a paracrine role for VEGF in modulating activities in adjacent vascular endothelium. Previous studies have shown that vascular growth is impaired in bronchopulmonary dysplasia (BPD).

OBJECTIVE

The goal of this study was to examine tracheal (T-VEGF) and gastric (G-VEGF) levels in premature infants in the first and third day of life and examine if these levels were associated with the development of BPD.

DESIGN/METHODS

Tracheal aspirates from intubated infants and gastric samples from others were obtained on postnatal days 1 (D1) and 3 (D3) from 43 preterm infants (<2000 g birth weight, ≤34 wks gestation). VEGF was quantified by a VEGF Elisa Kit. Demographic, clinical, and pulmonary outcome data were collected including information on respiratory support (oxygenation index (OI) and ventilatory index (VI)) and on the development of BPD, determined at 36 weeks PMA using NICHD criteria.

RESULTS

The mean birth weight was 1060 ± 379 g and gestational age 27.5 ± 2.8 wks. BPD was diagnosed in 26 infants who were less mature than the 17 controls without BPD. Day 1 and day 3T-VEGF concentrations did not correlate, but day 3 levels correlated with gestational age (r = 0.75, p < .05). BPD infants, characterized by longer ventilator, CPAP and oxygen days, had day 1T-VEGF levels similar to control infants (126.6 ± 194.7 vs. 149.7 ± 333.2 pg/ml) but day 3 levels were significantly lower (168.9 ± 218.8 vs. 1041.6 ± 676.7 pg/ml). Day 1G-VEGF levels reflected tracheal samples, trending lower in BPD infants. Mode of delivery, race, sex, antenatal steroid administration, chorioamnionitis, sepsis, or growth restriction did not impact VEGF levels. However, lower VEGF levels were associated with a lower VI and lower OI: Day 3 OI correlated with day 3T-VEGF (r = 0.72, p > .05), albeit not significantly. T-VEGF increased from day 1 to day 3 in controls and decreased in BPD infants. There was no relationship between oxygen, CPAP and ventilator days and day 1 or day 3T-VEGF levels.

CONCLUSIONS

BPD may be associated with low-serum VEGF levels during the first week of life. This finding is likely related to decreased expression in the lungs of the less mature infants, who are at the highest risk for BPD.

Adiponectin ameliorates hyperoxia-induced lung endothelial dysfunction and promotes angiogenesis in neonatal mice

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common respiratory disease of preterm infants. Lower circulatory/intrapulmonary levels of the adipokine, adiponectin (APN), occur in premature and small-for-gestational-age infants and at saccular/alveolar stages of lung development in the newborn rat. However, the role of low intrapulmonary APN during hyperoxia exposure in developing lungs is unknown.

METHODS

We test the hypothesis that treatment of hyperoxia-exposed newborn mice with recombinant APN protein attenuates the BPD phenotype characterized by inflammation, impaired alveolarization, and dysregulated vascularization. We used developmentally appropriate in vitro and in vivo BPD modeling systems as well as human lung tissue.

RESULTS

We observed reduced levels of intrapulmonary APN in experimental BPD mice and human BPD lungs. APN-deficient (APN^-/-) newborn mice exposed to moderate (60% O₂) hyperoxia showed a worse BPD pulmonary phenotype (inflammation, enhanced endothelial dysfunction, impaired pulmonary vasculature, and alveolar simplification) as compared to wild-type (WT) mice. Treatment of hyperoxia-exposed newborn WT mice with recombinant APN protein attenuated the BPD phenotype (diminished inflammation, decreased pulmonary vascular injury, and improved pulmonary alveolarization) and improved pulmonary function tests.

CONCLUSIONS

Low intrapulmonary APN is associated with disruption of lung development during hyperoxia exposure, while recombinant APN protein attenuates the BPD pulmonary phenotype.

IMPACT

Intrapulmonary APN levels were significantly decreased in lungs of experimental BPD mice and human BPD lung tissue at various stages of BPD development. Correlative data from human lung samples with decreased APN levels were associated with increased lung adhesion markers (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin). Decreased APN levels were associated with endothelial dysfunction and moderate BPD phenotype in APN-deficient, as compared to WT, experimental BPD mice. WT experimental BPD mice treated with recombinant APN protein had an improved pulmonary structural and functional phenotype. Exogenous APN may be considered as a potential therapeutic agent to prevent BPD.

Mortality in Outpatients with Bronchopulmonary Dysplasia

OBJECTIVES

To study the demographic and clinical characteristics of preterm infants with bronchopulmonary dysplasia (BPD) to identify the factors most strongly predictive of outpatient mortality, with the goal of identifying those individuals at greatest risk.

STUDY DESIGN

Demographic and clinical characteristics were retrospectively reviewed for 862 subjects recruited from an outpatient BPD clinic. Characteristics of the deceased and living participants were compared using nonparametric analysis. Regression analysis was performed to identify factors associated with mortality.

RESULTS

Of the 862 subjects, 13 (1.5%) died during follow-up, for an overall mortality rate of approximately 15.1 deaths per 1000 subjects. Two patients died in the postneonatal period (annual mortality incidence, 369.9 per 100 000), 9 died between age 1 and 4 years (annual mortality incidence, 310.2 per 100 000), and 2 died between age of 5 and 14 years (annual mortality incidence, 71.4 per 100 000). After adjusting for gestational age and BPD severity, mortality was found to be associated with the amount of supplemental oxygen required at discharge from the neonatal intensive care unit (adjusted hazard ratio [aHR], 4.10; P = .001), presence of a gastrostomy tube (aHR, 8.13; P = .012), and presence of a cerebrospinal fluid (CSF) shunt (aHR, 4.31; P = .021).

CONCLUSIONS

The incidence of mortality among preterm infants with BPD is substantially higher than that seen in the general population. The need for greater amounts of home supplemental oxygen and the presence of a gastrostomy tube or CSF shunt were associated with an increased risk of postdischarge mortality. Future studies should focus on clarifying risk factors for the development of severe disease to allow for early identification and treatment of those at highest risk.

Volumetric Capnography at 36 Weeks Postmenstrual Age and Bronchopulmonary Dysplasia in Very Preterm Infants

OBJECTIVES

To assess the feasibility of volumetric capnography in spontaneously breathing very preterm infants at 36 weeks postmenstrual age (PMA) and its association with clinical markers of lung disease including the duration of respiratory support and bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We obtained mainstream volumetric capnography measurements in 143 very preterm infants at 36 weeks PMA. BPD was categorized into no, mild, moderate, and severe according to the 2001 National Heart, Lung and Blood Institute workshop report. Normalized capnographic slopes of phase II (S_nII) and phase III (S_nIII) were calculated. We assessed the effect of BPD, duration of respiratory support, and duration of supplemental oxygen on capnographic slopes.

RESULTS

S_nIII was steeper in infants with moderate to severe BPD (76 ± 25/L) compared with mild (31 ± 20/L) or no BPD (26 ± 18/L) (P < .001). The association of S_nIII with moderate to severe BPD persisted after adjusting for birth weight z-score, respiratory rate, and airway dead space to tidal volume ratio. The diagnostic usefulness of S_nIII to discriminate between infants with and without moderate to severe BPD was high (area under the curve, 0.94; 95% CI, 0.89-0.99).

CONCLUSIONS

Volumetric capnography is feasible in spontaneously breathing preterm infants at 36 weeks PMA and reflects the degree of lung disease. This promising bedside lung function technique may offer an objective, continuous physiological outcome measure for assessment of BPD severity.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02083562.

Volume-guarantee vs. pressure-limited ventilation in evolving bronchopulmonary dysplasia

INTRODUCTION

Extremely premature infants are at high risk for developing bronchopulmonary dysplasia (BPD). While noninvasive support is preferred, they may require ventilator support. Although volume-targeted ventilation (VTV) has been shown to be beneficial in preventing BPD, no data exists to guide ventilator management of infants with evolving BPD. Thus, clinicians employ a host of ventilator strategies, traditionally time-cycled pressure-limited ventilation (PLV) and more recently volume-guarantee ventilation (VGV) (a form of VTV). In this study, we sought to test the hypothesis that use of VGV in evolving BPD is associated with improved clinical and pulmonary outcomes when compared with PLV.

DESIGN

Single-center, retrospective cohort review of premature infants born less than 28 weeks inborn to a Level 4 NICU from January 2015 to December 2020. Data abstracted included demographics, maternal and birth data, and ventilator data until death or discharge. Exposure to either VGV or PLV was also examined, including ventilator "dose" (number of time points from DOL 14, 21 and 28 the patient was on that particular ventilator) during the period of evolving BPD.

RESULTS

Of a total of 471 patients with ventilation data available on DOL 14, 268 were not ventilated and 203 were ventilated. PLV at DOL 21 and 28 was associated with significantly higher risk of BPD and the composite outcome of BPD or death before 36 weeks compared to VGV. Both increasing VGV and PLV doses were significantly associated with higher odds of BPD and the composite outcome. For each additional time point of VGV and PLV exposure, the predicted length of stay (LOS) increased by 15.3 days (p < 0.001) and 28.8 days (p < 0.001), respectively.

DISCUSSION

Our study demonstrates the association of use of VGV at DOL 21 and 28 with decreased risk of BPD compared to use of PLV. Prospective trials are needed to further delineate the most effective ventilatory modality for this population with "evolving" BPD.

Respiratory morbidity in preterm infants predicted by natriuretic peptide (MR-proANP) and endothelin-1 (CT-proET-1)

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a major complication in preterm infants <32 weeks. We aimed to assess whether plasma levels of mid-regional pro-atrial natriuretic peptide (MR-proANP) and C-terminal pro-endothelin-1 (CT-proET-1) predict respiratory morbidity.

METHODS

This was a prospective, two-center, observational cohort study. MR-proANP and CT-proET-1 were measured at day 7 (±2) of life. Associations with duration of supplemental oxygen and the composite outcome of moderate or severe BPD or death (BPD/death) were investigated.

RESULTS

Two hundred and twenty-nine infants <32 weeks were included (median gestational age [GA] 29.6 weeks [interquartile range 29.0-30.7], median birth weight 1150 g [IQR 840-1410]). MR-proANP and CT-proET-1 were associated with the duration of supplemental oxygen in univariable analysis (both p < 0.001) but not after adjusting for co-factors. Infants with BPD/death showed higher plasma levels of MR-proANP (623.50 pmol/L [IQR 458.50-881.38] vs. 308.35 pmol/L [IQR 216.72-538.10]; p < 0.001) and CT-proET-1 (255.40 pmol/L [IQR 202.60-311.15] vs. 198.30 pmol/L [IQR 154.70-297.95]; p = 0.015) compared to infants without BPD/death. Levels of both biomarkers were significantly associated with BPD/death in univariable models but not after adjusting for co-factors.

CONCLUSIONS

MR-proANP and CT-proET-1 are associated with the duration of supplemental oxygen and the composite outcome BPD/death, but their prognostic value does not complement that of clinical risk factors.

IMPACT

Plasma levels of MR-proANP and CT-proET-1, measured on day 7 of life (±2 days) are associated in univariable analyses with duration of supplemental oxygen and the combined outcome of BPD or death in VLGA infants. Associations between both biomarkers and respiratory morbidity do not persist in multivariable models, in particular when gestational age is included. MR-proANP and CT-proET-1 have limited additional value to predict respiratory morbidity in VLGA infants compared to clinical parameters.

Patho-mechanisms of the origins of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) continues to be one of the most common complications of prematurity, despite significant advancement in neonatology over the last couple of decades. The new BPD is characterized histopathologically by impaired lung alveolarization and dysregulated vascularization. With the increased survival of extremely preterm infants, the risk for the development of BPD remains high, emphasizing the continued need to understand the patho-mechanisms that play a role in the development of this disease. This brief review summarizes recent advances in our understanding of the maldevelopment of the premature lung, highlighting recent research in pathways of oxidative stress-related lung injury, the role of placental insufficiency, growth factor signaling, the extracellular matrix, and microRNAs.

The challenge of accurately describing the epidemiology of bronchopulmonary dysplasia (BPD) based on the various current definitions of BPD

Despite marked improvements in the survival of extremely low birth weight preterm infants, bronchopulmonary dysplasia (BPD) remains a prevalent morbidity. BPD has evolved pathologically and epidemiologically but the definition has failed to keep up. The majority of the definitions of BPD still use the respiratory support provided to the infants at a single timepoint. The lack of a uniform definition of BPD presently reflects the changing BPD pathogenesis and phenotype and limits defining the epidemiology. To address the epidemiology of BPD, the definition should be clarified; even the newer definitions have not been validated entirely. The definition needs to be meaningful clinically and be predictive of long-term respiratory outcomes. We believe the definition should have a composite assessment like a score (quantitative measurement) and include the different phenotypes (qualitative measurements) so that optimally they can be applied to the different phases of BPD and at different timepoints. Furthermore, the definitions need to be easy to measure and assess so that generalizability is enhanced.

Diagnosis and management of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infants and is associated with increased mortality, respiratory morbidity, neurodevelopmental impairment, and increased healthcare costs. In parallel with advances made in the field of neonatal intensive care, the phenotype of BPD has evolved from a fibrocystic disease affecting late preterm infants to one of impaired parenchymal development and dysregulated vascular growth predominantly affecting infants born before 29 weeks' gestational age. BPD has been shown to have significant lifelong consequences. Adults with BPD have been found to have abnormal lung function tests, reduced exercise tolerance, and may be at increased risk for developing chronic obstructive pulmonary disease. Evidence shows that BPD occurs secondary to genetic-environmental interactions in an immature lung. In this review, we evaluate the various clinical definitions, imaging modalities, and biomarker data that are helpful in making an early diagnosis of BPD. In addition, we evaluate recent evidence about the prevention and treatment of BPD. We discuss the invasive and non-invasive ventilation strategies and pharmacological agents used in the early, evolving, and established phases of BPD.

Development and verification of a risk prediction model for bronchopulmonary dysplasia in very low birth weight infants

BACKGROUND

To analyze the risk factors of bronchopulmonary dysplasia (BPD) of very low birth weight infants (VLBWIs), and to develop and verify a risk prediction model of BPD.

METHODS

The data of 611 VLBWIs from the neonatal intensive care unit (NICU) of a tertiary grade A hospital in Suzhou from January 2017 to September 2019 were collected. The data was randomly divided into the modeling set (451 cases) and the validation set (160 cases). Binary logistic regression was used to analyze the data, and the model was examined by a receiver operating characteristic (ROC) curve. The grouped data was used to verify the sensitivity and specificity of the model.

RESULTS

The study found that neonatal asphyxia, the positive rate of sputum culture, neonatal sepsis, neonatal respiratory distress syndrome (NRDS), blood transfusions (≥3), patent ductus arteriosus (PDA), the time of invasive mechanical ventilation, the duration of oxygen therapy, and the time of parenteral nutrition were the independent risk factors of BPD, while 1 min Apgar score was a protective factor. The model formula was Z=neonatal asphyxia * 1.229 + the positive rate of sputum culture * 1.265 + neonatal sepsis * 1.677 + NRDS * 1.848 + blood transfusions (≥3) * 1.455 + PDA * 1.835 - 1 min Apgar score * 0.25 + the time of invasive mechanical ventilation * 0.123 + the duration of oxygen therapy * 0.09 + the time of parenteral nutrition * 0.057 - 8.077. The area under the ROC curve of this model was 0.965 (95% CI: 0.946-0.983), with a sensitivity of 93.7% and a specificity of 91.3%. Verification of this prediction model showed a sensitivity of 92.9% and a specificity of 76%, demonstrating that the effects of this model were satisfactory.

CONCLUSIONS

The risk prediction model had a good predictive effect for the risk of BPD in VLBWIs, and can provide a reference for preventive treatment and nursing intervention.

Chitin-Derived AVR-48 Prevents Experimental Bronchopulmonary Dysplasia (BPD) and BPD-Associated Pulmonary Hypertension in Newborn Mice

Bronchopulmonary dysplasia (BPD) is the most common complication of prematurity and a key contributor to the large health care burden associated with prematurity, longer hospital stays, higher hospital costs, and frequent re-hospitalizations of affected patients through the first year of life and increased resource utilization throughout childhood. This disease is associated with abnormal pulmonary function that may lead to BPD-associated pulmonary hypertension (PH), a major contributor to neonatal mortality and morbidity. In the absence of any definitive treatment options, this life-threatening disease is associated with high resource utilization during and after neonatal intensive care unit (NICU) stay. The goal of this study was to test the safety and efficacy of a small molecule derivative of chitin, AVR-48, as prophylactic therapy for preventing experimental BPD in a mouse model. Two doses of AVR-48 were delivered either intranasally (0.11 mg/kg), intraperitoneally (10 mg/kg), or intravenously (IV) (10 mg/kg) to newborn mouse pups on postnatal day (P)2 and P4. The outcomes were assessed by measuring total inflammatory cells in the broncho-alveolar lavage fluid (BALF), chord length, septal thickness, and radial alveolar counts of the alveoli, Fulton’s Index (for PH), cell proliferation and cell death by immunostaining, and markers of inflammation by Western blotting and ELISA. The bioavailability and safety of the drug were assessed by pharmacokinetic and toxicity studies in both neonatal mice and rat pups (P3-P5). Following AVR-48 treatment, alveolar simplification was improved, as evident from chord length, septal thickness, and radial alveolar counts; total inflammatory cells were decreased in the BALF; Fulton’s Index was decreased and lung inflammation and cell death were decreased, while angiogenesis and cell proliferation were increased. AVR-48 was found to be safe and the no-observed-adverse-effect level (NOAEL) in rat pups was determined to be 100 mg/kg when delivered via IV dosing with a 20-fold safety margin. With no reported toxicity and with a shorter half-life, AVR-48 is able to reverse the worsening cardiopulmonary phenotype of experimental BPD and BPD-PH, compared to controls, thus positioning it as a future drug candidate.

Role of Infection and Immunity in Bovine Perinatal Mortality: Part 2. Fetomaternal Response to Infection and Novel Diagnostic Perspectives

Simple Summary

Bovine perinatal mortality (death of the fetus or calf before, during, or within 48 h of calving at full term (≥260 days) may be caused by noninfectious and infectious causes. Although infectious causes of fetal mortality are diagnosed less frequently, infection in utero may also compromise the development of the fetus without causing death. This review presents fetomaternal responses to infection and the changes which can be observed in such cases. Response to infection, especially the concentration of immunoglobulins and some acute-phase proteins, may be used for diagnostic purposes. Some changes in internal organs may also be used as an indicator of infection in utero. However, in all cases (except pathogen-specific antibody response) non-pathogen-specific responses do not aid in pathogen-specific diagnosis of the cause of calf death. But, nonspecific markers of in utero infection may allow us to assign the cause of fetal mortality to infection and thus increase our overall diagnosis rate, particularly in cases of the “unexplained stillbirth”.

Abstract

Bovine perinatal mortality due to infection may result either from the direct effects of intrauterine infection and/or the fetal response to such infection, leading to the fetal inflammatory response syndrome (FIRS). Both intrauterine infection and FIRS, which causes multi-organ damage and involution of immune organs, compromise fetal survivability, sometimes fatally. Organ injury associated with FIRS may, in addition to causing fetal mortality, irreversibly compromise extrauterine adaptation of the neonate, a recognized problem in human fetuses. Diagnosis of intrauterine infection and of FIRS requires related, but independent analytical approaches. In addition to detection of pathogens, the immune and inflammatory responses of the bovine fetus may be utilized to diagnose intrauterine infection. This can be done by detection of specific changes in internal organs and the measurement of antibodies and/or elements of the acute phase reaction. Currently our ability to diagnose FIRS in bovine fetuses and neonates is limited to research studies. This review focuses on both the fetomaternal response to infection and diagnostic methods which rely on the response of the fetus to infection and inflammatory changes, as well other methods which may improve diagnosis of intrauterine infection in cases of bovine perinatal mortality.

The association of vitamin D and vitamin E levels at birth with bronchopulmonary dysplasia in preterm infants

BACKGROUND

Despite improvements made in neonatal care, bronchopulmonary dysplasia (BPD) is still the most common respiratory disease in preterm infants. The relationship between the blood contents of vitamin D/E in premature infants and BPD is still controversial.

METHODS

Preterm infants were recruited as the research subjects. On the basis of the inclusion and exclusion criteria, a total of 133 eligible cases were finally included. A total of 63 preterm infants with a clear diagnosis of BPD and 5 preterm infants who died before the diagnosis of BPD were in the case group, and 65 non-BPD preterm infants with equivalent baseline characteristics were in the control group. The BPD group included 38 cases in Grade Ⅰ, 18 cases in Grade Ⅱ, and 12 cases in Grade Ⅲ. The contents of vitamin D and E in the cord blood of different groups were detected by high-performance liquid chromatography and enzyme-linked immunosorbent assay. Correlation analysis adopted the Pearson correlation analytic method.

RESULTS

The serum vitamin D and E levels at birth were remarkably lower in the BPD group than the non-BPD group, both of which were also correlated with the severity of BPD. The vitamin D and E contents were negatively correlated with the oxygen support duration required for premature infants with BPD.

CONCLUSION

This study deepens our understanding of the field of BPD pathogenesis by demonstrating an association between vitamin D/E deficiency and BPD severity, suggesting that vitamin D and E might have potential clinical value in the prognosis and treatment of BPD.

Hyperoxia-induced miR-342-5p down-regulation exacerbates neonatal bronchopulmonary dysplasia via the Raf1 regulator Spred3

BACKGROUND AND PURPOSE

Bronchopulmonary dysplasia (BPD) is the most prevalent chronic paediatric lung disease and is linked to the development of chronic obstructive pulmonary disease. MicroRNA-based regulation of type II alveolar epithelial cell (T2AEC) proliferation and apoptosis is an important factor in the pathogenesis of BPD and warrants further investigation.

EXPERIMENTAL APPROACH

Two murine models of hyperoxic lung injury (with or without miR-342-5p or Sprouty-related, EVH1 domain-containing protein 3 [Spred3] modulation) were employed: a hyperoxia-induced acute lung injury model (100% O₂ on postnatal days 1-7) and the BPD model (100% O₂ on postnatal days 1-4, followed by room air for 10 days). Tracheal aspirate pellets from healthy control and moderate/severe BPD neonates were randomly selected for clinical miR-342-5p analysis.

KEY RESULTS

Hyperoxia decreased miR-342-5p levels in primary T2AECs, MLE12 cells and neonatal mouse lungs. Transgenic miR-342 overexpression in neonatal mice ameliorated survival rates and improved the BPD phenotype and BPD-associated pulmonary arterial hypertension (PAH). T2AEC-specific miR-342 transgenic overexpression, as well as miR-342-5p mimic therapy, also ameliorated the BPD phenotype and associated PAH. miR-342-5p targets the 3'UTR of the Raf1 regulator Spred3, inhibiting Spred3 expression. Treatment with recombinant Spred3 exacerbated the BPD phenotype and associated PAH. Notably, miR-342-5p inhibition under room air conditions did not mimic the BPD phenotype. Moderate/severe BPD tracheal aspirate pellets exhibited decreased miR-342-5p levels relative to healthy control pellets.

CONCLUSION AND IMPLICATIONS

These findings suggest that miR-342-5p mimic therapy may show promise in the treatment or prevention of BPD.

miR34a: a novel small molecule regulator with a big role in bronchopulmonary dysplasia

Preterm infants with bronchopulmonary dysplasia (BPD), characterized by pulmonary inflammation leading to impaired alveolarization and vascular dysregulation, have an increased risk of abnormal lung function in infancy, childhood, and adulthood. These include a heightened risk of pulmonary hypertension, and respiratory illnesses. MicroRNAs (miRNAs) are known to disrupt normal lung development and function by interrupting alveolarization and vascularization resulting in the development of BPD. Among the various miRs involved in BPD, miR34a has been shown to have a significant role in BPD pathogenesis. Targeting miR34a or its downstream targets may be a promising therapeutic intervention for BPD. In this review, we summarize the data on cellular arrest, proliferation, differentiation, epithelial-mesenchymal transition, mitochondrial dysfunction, and apoptosis impacted by miR34a in the development of BPD pulmonary phenotypes while predicting the future perspective of miR34a in BPD.

Qualitative indications for tracheostomy and chronic mechanical ventilation in patients with severe bronchopulmonary dysplasia

BACKGROUND

The decision to pursue chronic mechanical ventilation involves a complex mix of clinical and social considerations. Understanding the medical indications to pursue tracheostomy would reduce the ambiguity for both providers and families and facilitate focus on appropriate clinical goals.

OBJECTIVE

To describe potential indications to pursue tracheostomy and chronic mechanical ventilation in infants with severe BPD (sBPD).

STUDY DESIGN

We surveyed centers participating in the Children's Hospitals Neonatal Consortium to describe their approach to proceed with tracheostomy in infants with sBPD. We requested a single representative response per institution. Question types were fixed form and free text responses.

RESULTS

The response rate was high (31/34, 91%). Tracheostomy was strongly considered when: airway malacia was present, PCO₂ ≥ 76-85 mmHg, FiO₂ ≥ 0.60, PEEP ≥ 9-11 cm H₂O, respiratory rate ≥ 61-70 breaths/min, PMA ≥ 44 weeks, and weight <10th %ile at 44 weeks PMA.

CONCLUSIONS

Understanding the range of indications utilized by high level NICUs around the country to pursue a tracheostomy in an infant with sBPD is one step toward standardizing consensus indications for tracheostomy in the future.

The performance of the alarmin HMGB1 in pediatric diseases: From lab to clinic

INTRODUCTION

The ubiquitously expressed nonhistone nuclear protein high-mobility group box protein 1 (HMGB1) has different functions related to posttranslational modifications and cellular localization. In the nucleus, HMGB1 modulates gene transcription, replication and DNA repair as well as determines chromosomal architecture. When the post-transcriptional modified HMGB1 is released into the extracellular space, it triggers several physiological and pathological responses and initiates innate immunity through interacting with its reciprocal receptors (i.e., TLR4/2 and RAGE). The effect of HMGB1-mediated inflammatory activation on different systems has received increasing attention. HMGB1 is now considered to be an alarmin and participates in multiple inflammation-related diseases. In addition, HMGB1 also affects the occurrence and progression of tumors. However, most studies involving HMGB1 have been focused on adults or mature animals. Due to differences in disease characteristics between children and adults, it is necessary to clarify the role of HMGB1 in pediatric diseases.

METHODS AND RESULTS

Through systematic database retrieval, this review aimed to first elaborate the characteristics of HMGB1 under physiological and pathological conditions and then discuss the clinical significance of HMGB1 in the pediatric diseases according to different systems.

CONCLUSIONS

HMGB1 plays an important role in a variety of pediatric diseases and may be used as a diagnostic biomarker and therapeutic target for new strategies for the prevention and treatment of pediatric diseases.

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.

Recent advances in understanding and management of bronchopulmonary dysplasia

In the current era, the survival of extremely low-birth-weight infants has increased considerably because of new advances in technology; however, these infants often develop chronic dysfunction of the lung, which is called bronchopulmonary dysplasia (BPD). BPD remains an important cause of neonatal mortality and morbidity despite newer and gentler modes of ventilation. BPD results from the exposure of immature lungs to various antenatal and postnatal factors that lead to an impairment in lung development and aberrant growth of lung parenchyma and vasculature. However, we still struggle with a uniform definition for BPD that can help predict various short- and long-term pulmonary outcomes. With new research, our understanding of the pathobiology of this disease has evolved, and many new mechanisms of lung injury and repair are now known. By utilizing the novel ‘omic’ approaches in BPD, we have now identified various factors in the disease process that may act as novel therapeutic targets in the future. New investigational agents being explored for the management and prevention of BPD include mesenchymal stem cell therapy and insulin-like growth factor 1. Despite this, many questions remain unanswered and require further research to improve the outcomes of premature infants with BPD.

Inhibition of microRNA-451 is associated with increased expression of Macrophage Migration Inhibitory Factor and mitgation of the cardio-pulmonary phenotype in a murine model of Bronchopulmonary Dysplasia

Background

Macrophage migration inhibitory factor (MIF) has been implicated as a protective factor in the development of bronchopulmonary dysplasia (BPD) and is known to be regulated by MicroRNA-451 (miR-451). The aim of this study was to evaluate the role of miR-451 and the MIF signaling pathway in in vitro and in vivo models of BPD.

Methods

Studies were conducted in mouse lung endothelial cells (MLECs) exposed to hyperoxia and in a newborn mouse model of hyperoxia-induced BPD. Lung and cardiac morphometry as well as vascular markers were evaluated.

Results

Increased expression of miR-451 was noted in MLECs exposed to hyperoxia and in lungs of BPD mice. Administration of a miR-451 inhibitor to MLECs exposed to hyperoxia was associated with increased expression of MIF and decreased expression of angiopoietin (Ang) 2. Treatment with the miR-451 inhibitor was associated with improved lung morphometry indices, significant reduction in right ventricular hypertrophy, decreased mean arterial wall thickness and improvement in vascular density in BPD mice. Western blot analysis demonstrated preservation of MIF expression in BPD animals treated with a miR-451 inhibitor and increased expression of vascular endothelial growth factor-A (VEGF-A), Ang1, Ang2 and the Ang receptor, Tie2.

Conclusion

We demonstrated that inhibition of miR-451 is associated with mitigation of the cardio-pulmonary phenotype, preservation of MIF expression and increased expression of several vascular growth factors.

Extended Pharmacopeial Characterization of Surfactant Aerosols Generated by a Customized eFlow Neos Nebulizer Delivered through Neonatal Nasal Prongs

The delivery of nebulized medications to preterm infants during Non-Invasive Ventilation (NIV) remains an unmet clinical need. In this regard, the effective delivery of nebulized surfactant has been particularly investigated in preclinical and clinical studies. In this work, we investigated the feasibility of delivering nebulized surfactant through various commercially available nasal prong types. We first performed a compendial characterization of surfactant aerosols generated by the eFlow Neos nebulizer, customized to be used in neonates, determining the amount of surfactant delivered by the device as well as the aerodynamic characteristics of surfactant aerosols. Additionally, we extended the compendial characterization by testing the effect of different nasal prong types on the estimated lung dose using a realistic Continuous Positive Airway Pressure (CPAP) circuit that included a cast of the upper airways of a preterm neonate. The compendial characterization of surfactant aerosols delivered through different nasal prongs achieved relatively high delivered surfactant doses (in the range 63-74% of the nominal dose), with aerodynamic characteristics displaying mass median aerodynamic diameters ranging between 2.52 and 2.81 µm. Nevertheless, when using a representative in vitro setup mimicking NIV in a clinical setting, significant differences were observed in terms of the estimated lung dose accounting for up to two-fold differences (from 10% to 20% estimated lung deposition of the nominal dose) depending on the chosen nasal prong type. Considering that surfactant lung deposition rates are correlated with therapeutic efficacy, this study points out the relevance of choosing the appropriate NIV interface to maximize the lung dose of nebulized medications.

Extracellular vesicle miRNA-21 is a potential biomarker for predicting chronic lung disease in premature infants

Premature infants are often exposed to positive pressure ventilation and supplemental oxygen, which leads to the development of chronic lung disease (CLD). There are currently no standard serum biomarkers used for prediction or early detection of patients who go on to develop CLD. MicroRNAs (miRNAs) are a novel class of naturally occurring, short, noncoding substances that regulate gene expression at the posttranscriptional level and cause translational inhibition and/or mRNA degradation and present in body fluids packaged in extracellular vesicles (EVs), rendering them remarkably stable. Our aim was to evaluate miRNAs identified in serum EVs of premature infants as potential biomarkers for CLD. Serum EVs were extracted from premature infants at birth and on the 28th day of life (DOL). Using a human miRNA array, we identified 62 miRNAs that were universally expressed in CLD patients and non-CLD patients. Of the 62 miRNAs, 59 miRNAs and 44 miRNAs were differentially expressed on DOL0 and DOL28 in CLD and non-CLD patients, respectively. Of these miRNAs, serum EV miR-21 was upregulated in CLD patients on DOL28 compared with levels at birth and downregulated in non-CLD patients on DOL28 compared with levels at birth. In neonatal mice exposed to hyperoxia for 7days, as a model of CLD, five miRNAs (miR-34a, miR-21, miR-712, miR-682, and miR-221) were upregulated, and 7 miRNAs (miR-542-5p, miR-449a, miR-322, miR-190b, miR-153, miR-335-3p, miR-377) were downregulated. MiR-21 was detected as a common miRNA that changed in CLD patients and in the hyperoxia exposed mice. We conclude that EV miR-21 may be a biomarker of CLD.

14-3-3β Is necessary in the regulation of polarization and directional migration of alveolar myofibroblasts by lipopolysaccharide

Aims:Bronchopulmonary dysplasia (BPD) is characterized by alveolarization arrest. During alveolarization, alveolar myofibroblasts are thought to migrate into the septal tips and elongate secondary septa. Lipopolysaccharide (LPS) exposure has been reported to disrupt directional migration and final location of alveolar myofibroblasts in a rat model of BPD induced by intra-amniotic injection of LPS. However, molecular mechanisms that control directional migration of alveolar myofibroblasts have not so far been investigated clearly. Materials and Methods: We assessed the polarization of myofibroblast using scrape wounding assays combined with Golgi tracking. Transwell migration assay was used to detect the directional migration of myofibroblasts. Pull-down assays were performed to isolate the active GTP-bound form using the RhoA activation assay kits. Western blotting analysis was performed to evaluate the changes in protein expression. Functional analysis was performed via siRNA interference. Results: Here, we showed that LPS might affect the directional migration of myofibroblasts by disturbing the polarization of myofibroblasts. In addition, as a main member of RhoGTPases family which plays a vital role in establishing and maintaining cell polarity, RhoA activity was significantly upregulated in myofibroblasts treated with LPS, while activity of epidermal growth factor receptor (EGFR) was upregulated and overexpression of its ligand, TGF-α, in myofibroblasts by LPS treatment. AG1478, an EGFR inhibitor, could abrogate the upregulated RhoA activity of myofibroblasts by LPS and rhTGF-α. Moreover, if we knock down 14-3-3β, LPS and rhTGF-α could not activate RhoA and disturb myofibroblasts polarization. Conclusions: Taken together, our findings suggest that LPS exposure may increase RhoA activity of myofibroblasts by TGF-α/EGFR/14-3-3β signaling pathway, and then disturb myofibroblasts polarization and directional migration.

Hyperoxia causes miR199a-5p-mediated injury in the developing lung

BACKGROUND

Hyperoxia-induced acute lung injury (HALI) is characterized by increased permeability and infiltration of inflammatory cells, impairment of alveolar development, and compromised lung function. Recent evidence has determined that microRNAs (miRs) are implicated in hyperoxia-induced lung injury, including bronchopulmonary dysplasia (BPD). However, the expression profile and functional role of miR199a-5p in developing lungs have not been reported.

METHODS

The present study was undertaken to explore the role of miR199a-5p in developing mice lungs and human neonates. We exposed neonatal mice for 7 days, mouse lung epithelial cells (MLE12), mouse lung endothelial cells (MLECs), and macrophages (RAW246.7), to hyperoxia at different time points.

RESULTS

Our results demonstrated enhanced miR199a-5p expression in hyperoxia-exposed mice lungs and cells, as well as in tracheal aspirates of infants developing BPD, with significant reduction in the expression of its target, caveolin-1. Next, we observed that miR199a-5p-mimic worsens HALI as evidenced by increased inflammatory cells, cytokines, and lung vascular markers. Conversely, miR199a-5p-inhibitor treatment attenuated HALI.

CONCLUSION

Thus, our findings suggest that miR199a-5p is a potential target for attenuating HALI pathophysiology in the developing lung. Moreover, miR199a-5p-inhibitor could be part of a novel therapeutic strategy for improving BPD in preterm neonates.

Impact of SIMPLE Feeding Quality Improvement Strategies on Aerodigestive Milestones and Feeding Outcomes in BPD Infants

BACKGROUND AND OBJECTIVES

Delays with enteral and oral feeding milestones among premature infants with bronchopulmonary dysplasia (BPD) can be due to provider variation or infant-dependent factors. Our objectives with this study were to compare aerodigestive milestones and length of stay in BPD infants after implementing a quality improvement program to improve feeding outcomes.

METHODS

Using the Institute for Healthcare Improvement model for quality improvement, we implemented the simplified, individualized, milestone-targeted, pragmatic, longitudinal, and educational (SIMPLE) feeding strategy to enhance feeding and aerodigestive milestones among BPD infants. The key interventions addressed were as follows: (1) enteral feed initiation and advancement protocol; (2) oral feeding progression guidelines, optimization of respiratory support, feeding readiness scores, nonnutritive breastfeeding, and cue-based feeding; (3) active multidisciplinary collaboration; and (4) family-centered care. Comparisons were made between baseline (January 2009 to March 2010) and SIMPLE feeding strategy (May 2010 to December 2013) groups. Both groups included infants between 23 0/7 and 32 6/7 weeks' birth gestation, and ≤34 weeks' postmenstrual age at admission and discharge.

RESULTS

The baseline group and SIMPLE feeding group included 92 patients and 187 patients, respectively. Full enteral feeding, first oral feeding, full oral feeding, and length of stay milestones were (all P < .05) achieved sooner in the SIMPLE feeding group. Although the overall prevalence of BPD in the 2 groups is similar, the incidence of moderate BPD has decreased (P < .05) and severe BPD has increased (P < .05) in the SIMPLE feeding group.

CONCLUSIONS

SIMPLE feeding strategy advances postnatal maturation and acquisition of feeding milestones irrespective of the severity of BPD and impacts the length of stay, thereby lowering resource use.

Outcome of Very Preterm Infants With Early Optimal Nutrition Strategy: A Comparative Cohort Study

BACKGROUND

Aggressive nutrition may benefit early growth; nevertheless, effects on neurodevelopmental outcomes are unclear. We planned a descriptive analytical study to compare survival without neurodevelopment disability (NDD) at 1 year in 2 groups during 2 time epochs-before and after implementation of early optimal nutrition strategies. NDD was defined as any one of the following: mental and/or motor development quotient < 85 at 12 months of age, corrected for prematurity; Denver Developmental Screening Test abnormal/suspect in even 1 domain out of the 4 domains; seizures; requirement of hearing aid; or blindness in 1 or both eyes. We also compared mortality, survival without bronchopulmonary dysplasia, necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), intraventricular hemorrhage, periventricular leukomalacia, sepsis, metabolic bone disease (MBD), and extrauterine growth restriction (EUGR).

METHODS

Preterm neonates born between 27 and 32 weeks' gestation were included. The prospective study group (AO) was recruited after implementation of early optimal nutrition policy. The comparative retrospective cohort (BO) received nutrition based on clinicians' decisions. Both groups were followed up using a structured plan till 1 year corrected age.

RESULTS

137 neonates were enrolled in AO and 151 in the BO cohort. There was no statistically significant difference in survival without NDD at 1 year-75.5% in AO vs 72.1% in BO, odds ratio 0.84 (95% CI 0.5-1.6). Babies who received early optimal nutrition had less NEC, EUGR, and ROP requiring laser therapy but more MBD.

CONCLUSION

There was no difference in survival without NDD in early optimal nutrition cohort compared to the cohort before implementation of the nutrition strategy. Short-term benefits themselves may justify the need for early optimal nutrition.

The level of extracellular superoxide dismutase in the first week of life in very and extremely low birth weight infants and the risk of developing bronchopulmonary dysplasia

Background Antioxidant enzymes may play a significant role in the development of bronchopulmonary dysplasia (BPD). The aim of the study was to assess the relationship between the level of extracellular superoxide dismutase (SOD3) in the serum at days 1 and 7 of life and the risk of developing BPD. Methods The study comprised 103 neonates born before 32 weeks' gestation with a birth weight of ≤1500 g. Results In the investigated group, the median serum SOD3 level at day 1 of life was 4.01 ng/mL [interquartile range (IQR) 2.59-5.09 ng/mL] and at day 7 of life 3.13 ng/mL (IQR 2.49-4.34 ng/mL). A statistically significant decrease in the serum SOD3 level was found in the first week of life, P < 0.0001. No correlation was found between the serum SOD3 level at day 1 of life and gestational age R = 0.07, P = 0.4543 and birth weight R = 0.10, P = 0.3083. No statistically significant correlation was found between the dynamics of change in the SOD3 level in serum at days 1 and 7 of life and the risk of BPD development for the definition of BPD at day 28 of life, P = 0.8764 nor at 36 weeks' postmenstrual age, P = 0.6598. Conclusion The study revealed a statistically significant decrease in the serum SOD3 level in the first week of life in very and extremely low birth weight infants born before 32 weeks of gestation. In the clinical setting, no relationship was observed between the level of SOD3 in serum and the risk of developing BPD.

[Prognosis of bronchopulmonary dysplasia in preterm infants: a follow-up during infancy]

OBJECTIVE

To investigate the physical development, incidence of common respiratory diseases, and motor development during infancy in preterm infants with bronchopulmonary dysplasia (BPD).

METHODS

A retrospective analysis was performed on the clinical features and infantile outcomes of preterm infants with BPD who were admitted to the neonatal intensive care unit between January 2012 and December 2015. Preterm infants without BPD were used as controls who were admitted to the neonatal intensive care unit during the same period and had similar gestational age and birth weight. Physical development, number of hospital stays, the incidences of pneumonia and wheezing, and motor development during infancy were compared between the two groups.

RESULTS

Compared with the control group, BPD infants had a significantly higher incidence of extrauterine growth retardation at discharge (48% vs 41%; P<0.05); BPD infants were more susceptible to pneumonia, wheezing, eczema and rhinitis; BDP infants also had a significantly higher number of readmissions due to respiratory tract infection (P<0.05). BPD infants had a significantly smaller head circumference than the control group at corrected ages of 3, 6, and 12 months (P<0.05). BPD infants had significantly delayed gross, fine, and overall motor development than the control group at corrected ages of 6 and 9 months (P<0.05).

CONCLUSIONS

Infants with BPD are susceptible to extrauterine growth retardation at discharge. Their head circumference growth is relatively slow. They are susceptible to pneumonia and wheezing during infancy. Moreover, they have delayed motor development when compared with those without BPD at corrected ages of 6 and 9 months.

Bronchopulmonary dysplasia: how can we improve its outcomes?

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of preterm infants with multiple factors affected from prenatal to postnatal periods. Despite significant advances in neonatal care over almost 50 years, BPD rates have not decreased; in fact, they may have even increased. Since more preterm infants, even at periviable gestational age, survive today, different stages of lung development affect the pathogenesis of BPD. Hence, the definition of BPD has changed from “old” to “new.” In this review, we discuss the various definitions of BPD, risk factors from the prenatal to postnatal periods, management strategies by phase, and future directions for research.

Genetic Strain and Sex Differences in a Hyperoxia-Induced Mouse Model of Varying Severity of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a disease prevalent in preterm babies with a need for supplemental oxygen, resulting in impaired lung development and dysregulated vascularization. Epidemiologic studies have shown that males are more prone to BPD and have a delayed recovery compared with females, for reasons unknown. Herein, we tried to recapitulate mild, moderate, and severe BPD, using two different strains of mice, in males and females: CD1 (outbred) and C57BL/6 (inbred). Aside from higher body weight in the CD1 strain, there were no other gross morphologic differences with respect to alveolar development between the two strains. With respect to lung morphology after oxygen exposure, females had less injury with better preservation of alveolar chord length and decreased alveolar protein leak and inflammatory cells in the bronchoalveolar lavage fluid. In addition, housekeeping genes, which are routinely used as loading controls, were expressed differently in males and females. In the BPD mouse model, gonadotropin-releasing hormone was increased in females compared with males. Specific miRNAs (miR-146 and miR-34a) were expressed differently in the sexes. In the severe BPD mouse model, administering miR-146 mimic to males attenuated lung damage, whereas administering miR-146 inhibitor to females increased pulmonary injury.

An update on the post-NICU discharge management of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease which develops as a result of neonatal/perinatal lung injury. It is the commonest cause of chronic lung disease in infancy and the most frequent morbidity associated with prematurity. The incidence of BPD has continued to rise despite many advances in neonatal care and this increase has been attributed to the increased survival of younger and more premature babies. There have been many advances in the care of patients with early and evolving BPD, yet there is a paucity of data regarding outpatient management of patients with established BPD. There are limited adequately-powered high-quality studies/randomized controlled trials which assess commonly used therapies such as supplemental oxygen, bronchodilators, steroids and diuretics in patients with BPD, beyond short-term effects. Further research is needed to improve our understanding of the role of currently used treatments on the long-term outcomes of patients with established BPD, post-discharge from the neonatal intensive care unit.

Surfactant, steroids and non-invasive ventilation in the prevention of BPD

Bronchopulmonary dysplasia (BPD) is a complex disorder with multiple factors implicated in its etiopathogenesis. Despite the scientific advances in the field of neonatology, the incidence of BPD has remained somewhat constant due to increased survival of extremely premature infants. Surfactant deficiency in the immature lung, exposure to invasive mechanical ventilation leading to volutrauma, barotrauma and lung inflammation are some of the critical contributing factors to the pathogenesis of BPD. Hence, strategies to prevent BPD in the postnatal period revolve around mitigation of this injury and inflammation. This article reviews the progress made in the last 5 years in the development of new preparations of surfactant, use of corticosteroids and non-invasive ventilation in the prevention of BPD. Emerging techniques of surfactant delivery through minimally invasive and non-invasive routes are also discussed.

Off-label mesenchymal stromal cell treatment in two infants with severe bronchopulmonary dysplasia: clinical course and biomarkers profile

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most prevalent sequelae of premature birth, for which therapeutic options are currently limited. Mesenchymal stromal cells (MSCs) are a potential therapy for prevention or reversal of BPD.

SERIES OF CASES

We report on two infants with severe BPD in whom off-label treatment with repeated intravenous doses of allogeneic bone marrow-derived MSCs were administered. We analyzed the temporal profile of serum and tracheal cytokines and growth factors as well as safety, tolerability and clinical response. The administration of repeated intravenous doses of MSCs in two human babies with severe and advanced BPD was feasible and safe and was associated with a decrease of pro-inflammatory molecules and lung injury biomarkers. Both patients were at very advanced stages of BPD with very severe lung fibrosis and did not survive the disease.

CONCLUSIONS

MSCs are a promising therapy for BPD, but they should be administered in early stages of the disease.

Riociguat prevents hyperoxia-induced lung injury and pulmonary hypertension in neonatal rats without effects on long bone growth

Bronchopulmonary dysplasia (BPD) remains the most common and serious chronic lung disease of premature infants. Severe BPD complicated with pulmonary hypertension (PH) increases the mortality of these infants. Riociguat is an allosteric soluble guanylate cyclase stimulator and is approved by the FDA for treating PH in adults. However, it has not been approved for use in neonates due to concern for adverse effects on long bone growth. To address this concern we investigated if administration of riociguat is beneficial in preventing hyperoxia-induced lung injury and PH without side effects on long bone growth in newborn rats. Newborn rats were randomized to normoxia (21% O₂) or hyperoxia (85% O₂) exposure groups within 24 hours of birth, and received riociguat or placebo by once daily intraperitoneal injections during continuous normoxia or hyperoxia exposure for 9 days. In the hyperoxia control group, radial alveolar count, mean linear intercept and vascular density were significantly decreased, the pathological hallmarks of BPD, and these were accompanied by an increased inflammatory response. There was also significantly elevated vascular muscularization of peripheral pulmonary vessels, right ventricular systolic pressure and right ventricular hypertrophy indicating PH. However, administration of riociguat significantly decreased lung inflammation, improved alveolar and vascular development, and decreased PH during hyperoxia by inducing cGMP production. Additionally, riociguat did not affect long bone growth or structure. These data indicate that riociguat is beneficial in preventing hyperoxia-induced lung injury and PH without affecting long bone growth and structure and hence, suggests riociguat may be a potential novel agent for preventing BPD and PH in neonates.