Drugs for the Prevention and Treatment of Bronchopulmonary Dysplasia

Theophylline impact on weaning in oxygen-dependent infants followed in an outpatient Kangaroo Program

Background

Theophylline was an orally administered xanthine used for treatment of apnea of prematurity and Bronchopulmonary Dysplasia in ambulatory follow-up of Low-Birth-Weight infants (LBWI) with oxygen-dependency in the outpatient Kangaroo Mother Care Program (KMCP). Theophylline's main metabolic product is caffeine; therefore, it was an alternative due to the frequent lack of ambulatory oral caffeine in low and middle-income countries.

Objective

To assess the effectiveness of oral theophylline in decreasing days with oxygen and to describe frequency of adverse related events.

Methods

Quasi-experiment before and after withdrawal of theophylline given systematically to LBWI with ambulatory oxygen in two KMCPs.

Results

729 patients were recruited; period 1: 319 infants when theophylline was given routinely and period 2: 410 infants when theophylline was no longer used. The theophylline cohort had less gestational age, less weight at birth, more days in Neonatal Intensive Care Unit, more days of oxygen-dependency at KMCP admission, and more frequencies of Intrauterine Growth Restriction and apneas. After adjusting with propensity score matching, multiple linear regression showed that nutrition was associated with days of oxygen-dependency, but theophylline treatment not. No differences were found in frequencies of readmissions up to 40 weeks, intraventricular hemorrhage or neurodevelopmental problems. Participants in period 2 had more tachycardia episodes.

Conclusions

We did not find association between oral theophylline treatment and the reduction of days with ambulatory oxygen. For the current management of oxygen-dependency in LBW infants, the importance of nutrition based on exclusive breast feeding whenever possible, is the challenge.

Nesfatin-1 alleviates hyperoxia-induced bronchopulmonary dysplasia (BPD) via the nuclear factor-κB (NF-κB) p65 signaling pathway

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease in newborns, which severely influences the health of infants and lacks effective clinical treatment strategies. The pathogenesis of BPD is correlated to enhanced inflammation and activated oxidative stress (OS). The application of antioxidants and anti-inflammatory treatment could be hot spots for BPD treatment. Nesfatin-1, a peptide with a suppressive property against inflammation, was tested herein for its potential therapeutic value in BPD. Neonatal SD rats were stimulated with hyperoxia, followed by being intraperitoneally administered with 20 μg/kg/day Nesfatin-1 for 2 weeks. Decreased RAC value in lung tissues, increased wet weight/dry weight (W/D) pulmonary ratio and bronchoalveolar lavage fluid (BALF) proteins, elevated cytokine release in BALF, increased malondialdehyde (MDA) content, and declined superoxide dismutase (SOD) activity were observed in BPD rats, all of which were sharply mitigated by Nesfatin-1. Rat epithelial type II cells (AECIIs) were handled with hyperoxia, and then cultured with 1 and 10 nM Nesfatin-1. Reduced cell viability, elevated lactate dehydrogenase production, elevated cytokine secretion, elevated MDA content, and decreased SOD activity were observed in hyperoxia-handled AECIIs, all of which were markedly alleviated by Nesfatin-1. Furthermore, activated nuclear factor-κB (NF-κB) signaling observed in both BPD rats and hyperoxia-handled AECIIs were notably repressed by Nesfatin-1. Collectively, Nesfatin-1 alleviated hyperoxia-triggered BPD by repressing inflammation and OS via the NF-κB signaling pathway.

Recruitment of PVT1 Enhances YTHDC1-Mediated m6A Modification of IL-33 in Hyperoxia-Induced Lung Injury During Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that specifically affects preterm infants. Oxygen therapy administered to treat BPD can lead to hyperoxia-induced lung injury, characterized by apoptosis of lung alveolar epithelial cells. Our epitranscriptomic microarray analysis of normal mice lungs and hyperoxia-stimulated mice lungs revealed elevated RNA expression levels of IL-33, as well as increased m6A RNA methylation levels of IL-33 and PVT1 in the hyperoxia-stimulated lungs. This study aimed to investigate the role of the PVT1/IL-33 axis in BPD. A mouse model of BPD was established through hyperoxia induction, and lung histological changes were assessed by hematoxylin-eosin staining. Parameters such as radial alveolar count and mean chord length were measured to assess lung function. Mouse and human lung alveolar epithelial cells (MLE12 and A549, respectively) were stimulated with hyperoxia to create an in vitro BPD model. Cell apoptosis was detected using Western blotting and flow cytometry analysis. Our results demonstrated that silencing PVT1 suppressed apoptosis in MLE12 and A549 cells and improved lung function in hyperoxia-stimulated lungs. Additionally, IL-33 reversed the effects of PVT1 both in vivo and in vitro. Through online bioinformatics analysis and RNA-binding protein immunoprecipitation assays, YTHDC1 was identified as a RNA-binding protein (RBP) for both PVT1 and IL-33. We found that PVT1 positively regulated IL-33 expression by recruiting YTHDC1 to mediate m6A modification of IL-33. In conclusion, silencing PVT1 demonstrated beneficial effects in alleviating BPD by facilitating YTHDC1-mediated m6A modification of IL-33. Inhibition of the PVT1/IL-33 axis to suppress apoptosis in lung alveolar epithelial cells may hold promise as a therapeutic approach for managing hyperoxia-induced lung injury in BPD.

Associations between Bronchopulmonary Dysplasia, Insulin-like Growth Factor I and Nutrition

Insulin-like growth factor I (IGF-I) has been suggested as an important factor in the pathogenesis of bronchopulmonary dysplasia (BPD). In turn, nutrition has been associated with IGF-I levels and could be of importance in the pathogenesis of BPD. This study aimed to explore the association between nutrition, the IGF-I axis and the occurrence of BPD. Eighty-six preterm infants (44 male, mean gestational age: 29.0 weeks (standard deviation: 1.7 weeks)) were enrolled in an observational study. Serum IGF-I (µg/L) and insulin-like growth factor binding protein 3 (IGFBP-3; mg/L) were measured at birth and at 2, 4 and 6 weeks postnatal age. BPD was diagnosed at 36 weeks postmenstrual age. Twenty-nine infants were diagnosed with BPD. For every µg/L per week increase in IGF-I, the odds of BPD decreased (0.68, 95% CI 0.48-0.96, corrected for gestational age). The change in IGF-I in µg/L/week, gestational age in weeks and a week of predominant donor human milk feeding were associated with the occurrence of BPD in the multivariable analysis (respectively, OR 0.63 (0.43-0.92), OR 0.44 (0.26-0.76) and 7.6 (1.2-50.4)). IGFBP-3 was not associated with the occurrence of BPD in the multivariable analysis. In conclusion, a slow increase in IGF-I levels and a lower gestational age increase the odds of BPD. Donor human milk might increase the odds of BPD and should be further explored.

Molsidomine decreases hyperoxia-induced lung injury in neonatal rats

BACKGROUND

The study's objective is to evaluate if Molsidomine (MOL), an anti-oxidant, anti-inflammatory, and anti-apoptotic drug, is effective in treating hyperoxic lung injury (HLI).

METHODS

The study consisted of four groups of neonatal rats characterized as the Control, Control+MOL, HLI, HLI + MOL groups. Near the end of the study, the lung tissue of the rats were evaluated with respect to apoptosis, histopathological damage, anti-oxidant and oxidant capacity as well as degree of inflammation.

RESULTS

Compared to the HLI group, malondialdehyde and total oxidant status levels in lung tissue were notably reduced in the HLI + MOL group. Furthermore, mean superoxide dismutase, glutathione peroxidase, and glutathione activities/levels in lung tissue were significantly higher in the HLI + MOL group as compared to the HLI group. Tumor necrosis factor-α and interleukin-1β elevations associated with hyperoxia were significantly reduced following MOL treatment. Median histopathological damage and mean alveolar macrophage numbers were found to be higher in the HLI and HLI + MOL groups when compared to the Control and Control+MOL groups. Both values were increased in the HLI group when compared to the HLI + MOL group.

CONCLUSIONS

Our research is the first to demonstrate that bronchopulmonary dysplasia may be prevented through the protective characteristics of MOL, an anti-inflammatory, anti-oxidant, and anti-apoptotic drug.

IMPACT

Molsidomine prophylaxis significantly decreased the level of oxidative stress markers. Molsidomine administration restored the activities of antioxidant enzymes. Molsidomine prophylaxis significantly reduced the levels of inflammatory cytokines. Molsidomine may provide a new and promising therapy for BPD in the future. Molsidomine prophylaxis decreased lung damage and macrophage infiltration in the tissue.

AMPK-driven Macrophage Responses Are Autophagy Dependent in Experimental Bronchopulmonary Dysplasia

The pathogenesis of bronchopulmonary dysplasia (BPD) remains incompletely understood. Recent studies suggest insufficient AMP-activated protein kinase (AMPK) activation as a potential cause of impaired autophagy in rodent and nonhuman primate models of BPD. Impaired autophagy is associated with enhanced inflammatory signaling in alveolar macrophages (AMs) and increased severity of murine BPD induced by neonatal hyperoxia exposure. The goal of this study was to determine the role of autophagy and AMPK activation in macrophage responses in murine BPD. C57BL/6J mice were exposed to neonatal hyperoxia starting on postnatal day (P)1 and treated with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) between P3 and P6. Mice were euthanized on P7, and markers of AMPK activation and autophagy were assessed by immunoblotting. Alveolarization was assessed using radial alveolar counts, mean linear intercept measurements, and quantification of alveolar septal myofibroblasts. Relative mRNA expression of M1-like and M2-like genes was assessed in AMs isolated from BAL fluid from wild-type, LysMCre--Becn1fl/fl, and LysMCre+-Becn1fl/fl mice after neonatal hyperoxia exposure. AICAR treatment resulted in AMPK activation and induction of autophagic activity in whole-lung and BAL cell lysates and attenuated hyperoxia-induced alveolar simplification in neonatal lungs. AICAR-treated control but not Beclin1-deficient AMs demonstrated significantly decreased expression of M1-like markers and significantly increased expression of M2-like markers. In conclusion, pharmacologic activation of AMPK by AICAR resulted in induction of autophagy and played a protective role, at least in part, through attenuation of proinflammatory signaling in AMs via autophagy-dependent mechanisms in a murine model of BPD.

Timing and cell specificity of senescence drives postnatal lung development and injury

Senescence causes age-related diseases and stress-related injury. Paradoxically, it is also essential for organismal development. Whether senescence contributes to lung development or injury in early life remains unclear. Here, we show that lung senescence occurred at birth and decreased throughout the saccular stage in mice. Reducing senescent cells at this stage disrupted lung development. In mice (<12 h old) exposed to hyperoxia during the saccular stage followed by air recovery until adulthood, lung senescence increased particularly in type II cells and secondary crest myofibroblasts. This peaked during the alveolar stage and was mediated by the p53/p21 pathway. Decreasing senescent cells during the alveolar stage attenuated hyperoxia-induced alveolar and vascular simplification. Conclusively, early programmed senescence orchestrates postnatal lung development whereas later hyperoxia-induced senescence causes lung injury through different mechanisms. This defines the ontogeny of lung senescence and provides an optimal therapeutic window for mitigating neonatal hyperoxic lung injury by inhibiting senescence.

Upregulating carnitine palmitoyltransferase 1 attenuates hyperoxia-induced endothelial cell dysfunction and persistent lung injury

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a chronic lung disease in premature infants that may cause long-term lung dysfunction. Accumulating evidence supports the vascular hypothesis of BPD, in which lung endothelial cell dysfunction drives this disease. We recently reported that endothelial carnitine palmitoyltransferase 1a (Cpt1a) is reduced by hyperoxia, and that endothelial cell-specific Cpt1a knockout mice are more susceptible to developing hyperoxia-induced injury than wild type mice. Whether Cpt1a upregulation attenuates hyperoxia-induced endothelial cell dysfunction and lung injury remains unknown. We hypothesized that upregulation of Cpt1a by baicalin or L-carnitine ameliorates hyperoxia-induced endothelial cell dysfunction and persistent lung injury.

METHODS

Lung endothelial cells or newborn mice (< 12 h old) were treated with baicalin or L-carnitine after hyperoxia (50% and 95% O2) followed by air recovery.

RESULTS

We found that incubation with L-carnitine (40 and 80 mg/L) and baicalin (22.5 and 45 mg/L) reduced hyperoxia-induced apoptosis, impaired cell migration and angiogenesis in cultured lung endothelial cells. This was associated with increased Cpt1a gene expression. In mice, neonatal hyperoxia caused persistent alveolar and vascular simplification in a concentration-dependent manner. Treatment with L-carnitine (150 and 300 mg/kg) and baicalin (50 and 100 mg/kg) attenuated neonatal hyperoxia-induced alveolar and vascular simplification in adult mice. These effects were diminished in endothelial cell-specific Cpt1a knockout mice.

CONCLUSIONS

Upregulating Cpt1a by baicalin or L-carnitine ameliorates hyperoxia-induced lung endothelial cell dysfunction, and persistent alveolar and vascular simplification. These findings provide potential therapeutic avenues for using L-carnitine and baicalin as Cpt1a upregulators to prevent persistent lung injury in premature infants with BPD.

Online clinical tool to estimate risk of bronchopulmonary dysplasia in extremely preterm infants

OBJECTIVE

Develop an online estimator that accurately predicts bronchopulmonary dysplasia (BPD) severity or death using readily-available demographic and clinical data.

DESIGN

Retrospective analysis of data entered into a prospective registry.

SETTING

Infants cared for at centres of the United States Neonatal Research Network between 2011 and 2017.

PATIENTS

Infants 501-1250 g birth weight and 23 0/7-28 6/7 weeks' gestation.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Separate multinomial regression models for postnatal days 1, 3, 7, 14 and 28 were developed to estimate the individual probabilities of death or BPD severity (no BPD, grade 1 BPD, grade 2 BPD, grade 3 BPD) defined according to the mode of respiratory support administered at 36 weeks' postmenstrual age.

RESULTS

Among 9181 included infants, birth weight was most predictive of death or BPD severity on postnatal day 1, while mode of respiratory support was the most predictive factor on days 3, 7, 14 and 28. The predictive accuracy of the models increased at each time period from postnatal day 1 (C-statistic: 0.674) to postnatal day 28 (C-statistic 0.741). We used these results to develop a web-based model that provides predicted estimates for BPD by postnatal day.

CONCLUSION

The probability of BPD or death in extremely preterm infants can be estimated with reasonable accuracy using a limited amount of readily available clinical information. This tool may aid clinical prognostication, future research, and center-specific quality improvement surrounding BPD prevention.

TRIAL REGISTRATION NUMBER

NCT00063063.

Antioxidants: Role the in prevention and treatment of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is one of the major causes of chronic respiratory diseases among infants. Both pharmacological and nonpharmacological approaches have been proposed for its management. Since oxidative stress is known to play a pivotal role in the pathogenesis of BPD, it is reasonable to consider the potential of antioxidant strategies in the prevention and treatment of this condition. Indeed, antioxidants can prevent or inhibit substrate oxidation. Some studies have evaluated the efficacy of the exogenous administration of vitamins and micronutrients in reducing the propagation of free radicals through their scavenging capacity. Nonetheless, encouraging preclinical results did not translate into effective preventive and/or therapeutic interventions. This narrative review evaluates the current evidence about the antioxidants that are potentially useful for preventing and treating BPD and explores the most relevant issues affecting their implementation in clinical practice, as well as their associated evidence gaps and research limitations.

Microbial and metabolic profiles of bronchopulmonary dysplasia and therapeutic effects of potential probiotics Limosilactobacillus reuteri and Bifidobacterium bifidum

AIMS

Bronchopulmonary dysplasia (BPD) is a common respiratory disease in newborns; however, there is no effective treatment. We aimed to investigate the effects of the potential probiotics Limosilactobacillus reuteri (L. reuteri) and Bifidobacterium bifidum (B. bifidum) on BPD using 16S rDNA sequencing and metabolomics methods.

METHODS AND RESULTS

Fecal samples were collected from 10 BPD patients and 10 healthy subjects. 16S rDNA sequencing results showed that microbial diversity was decreased and compositions were affected in BPD. Escherichia-Shigella and Clostridium_sensu_stricto_1 were increased in the BPD group, and Enterobacteriaceae, Megamonas, Blautia, Lactobacillus (Limosilactobacillus), [Eubacterium]_coprostanoligenes_group, Phascolarctobacterium and Bifidobacterium were reduced. Metabolomics analysis identified 129 differentiated metabolites that were changed in BPD patients, and they were associated with a preference for carbohydrate metabolism in translation and metabolism during genetic information processing. Correlation analysis revealed a remarkable relationship between gut microbiota and metabolites. Subsequently, a BPD cell model was constructed to test the effect of the potential probiotics. Cell function experiments verified that treatment with the potential probiotics L. reuteri and B. bifidum promoted proliferation and inhibited apoptosis of hyperoxia-induced MLE-12 cells. In addition, treatment with the potential probiotics L. reuteri and B. bifidum reduced inflammation and oxidative stress damage.

CONCLUSIONS

Treatment with the potential probiotics L. reuteri and B. bifidum could alleviate BPD and reduce inflammation and oxidative stress damage.

SIGNIFICANCE AND IMPACT

This study was the first to report positive roles for the potential probiotics L. reuteri and B. bifidum in BPD. The potential probiotics L. reuteri and B. bifidum were shown to reduce inflammation and oxidative stress damage in BPD. This study provided new insights on the pathogenesis and treatment of BPD.

Pharmacological Neuroprotection of the Preterm Brain: Current Evidence and Perspectives

Despite improvements in viability, the long-term neurodevelopmental outcomes of preterm babies remain serious concern as a significant percentage of these infants develop neurological and/or intellectual impairment, and they are also at increased risk of psychiatric illnesses later in life. The current challenge is to develop neuroprotective approaches to improve adverse outcomes in preterm survivors. The purpose of this review was to provide an overview of the current evidence on pharmacological agents targeting the neuroprotection of the preterm brain. Among them, magnesium sulfate, given antenatally to pregnant women with imminent preterm birth before 30 to 34 weeks of gestation, as well as caffeine administered to preterm infants after birth, exhibited neuroprotective effects for human preterm brain. Erythropoietin treatment of preterm infants did not result in neuroprotection at 2 years of age in two out of three published large randomized controlled trials; however, long-term follow-up of these infants is needed to come to definite conclusions. Further studies are also required to assess whether melatonin, neurosteroids, inhaled nitric oxide, allopurinol, or dietary supplements (omega-3 fatty acids, choline, curcumin, etc.) could be implemented as neuroprotectants in clinical practice. Furthermore, other pharmacological agents showing promising signs of neuroprotective efficacy in preclinical studies (growth factors, hyaluronidase inhibitors or treatment, antidiabetic drugs, cannabidiol, histamine-H3 receptor antagonists, etc.), as well as stem cell- or exosomal-based therapies and nanomedicine, may prove useful in the future as potential neuroprotective approaches for human preterm brain. KEY POINTS: · Magnesium and caffeine have neuroprotective effects for the preterm brain.. · Follow-up of infants treated with erythropoietin is needed.. · Neuroprotective efficacy of several drugs in animals needs to be shown in humans..

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.

The effects of early vitamin A supplementation on the prevention and treatment of bronchopulmonary dysplasia in premature infants: a systematic review and meta-analysis

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common and unique chronic disease of premature infants with a high mortality rate. A large number of studies have shown that vitamin A supplementation has a better effect on the prevention and treatment of BPD.

METHODS

Randomized controlled trials (RCTs) on early vitamin A supplementation for the prevention and treatment of BPD were searched in PubMed, EMBASE, and the Cochrane Library database. The search time was from the establishment of the database to July 28, 2021. Two investigators performed standard independent screening trials of the literature according to the inclusion and exclusion criteria. The methodology of the included articles was evaluated, and the data were extracted. If the opinions of the 2 investigators were not consistent, a third party could be consulted. The Cochrane systematic review manual was used to analyze the bias of the included studies, and the RevMan 5.3 software was used to perform the meta-analysis.

RESULTS

In the experimental group, the BPD incidence [-0.71, 95% confidential interval (CI): -0.34 to -0.00; Z=1.98; P=0.05], 28-day oxygen uptake rate (0.81, 95% CI: 0.38-1.730; Z=0.53; P=0.59), 36-week survival rate (1.08, 95% CI: 0.80-1.46; Z=0.49; P=0.62), incidence of patent ductus arteriosus (0.77, 95% CI: 0.27-2.21; Z=0.48; P=0.63), days of mechanical ventilation (0.02, 95% CI: -1.46-1.49; Z=0.02; P=0.98), and 28-day ventilator use (0.77, 95% CI: 0.31-1.92; Z=0.55; P=0.58) were lower than those in the control group, especially the incidence of BPD.

DISCUSSION

Early supplementation of vitamin A showed good efficacy and safety in the prevention and treatment of BPD in premature infants, and can also improve the survival rate of infants. Therefore, it is worthy of clinical application.

Optimizing respiratory management in preterm infants: a review of adjuvant pharmacotherapies

Adjuvant respiratory therapies in preterm neonates aim to reduce long-term morbidities and mortality. Commonly utilized therapies include caffeine, systemic glucocorticosteroids, inhaled steroids, inhaled bronchodilators, and diuretics. This review discusses the available literature that supports some of these practices and points out where clinical practices are not corroborated by evidence. Therapies with no proven clinical benefit must be weighed against potential adverse effects.

Metabolic dysregulation in bronchopulmonary dysplasia: Implications for identification of biomarkers and therapeutic approaches

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in premature infants. Accumulating evidence shows that dysregulated metabolism of glucose, lipids and amino acids are observed in premature infants. Animal and cell studies demonstrate that abnormal metabolism of these substrates results in apoptosis, inflammation, reduced migration, abnormal proliferation or senescence in response to hyperoxic exposure, and that rectifying metabolic dysfunction attenuates neonatal hyperoxia-induced alveolar simplification and vascular dysgenesis in the lung. BPD is often associated with several comorbidities, including pulmonary hypertension and neurodevelopmental abnormalities, which significantly increase the morbidity and mortality of this disease. Here, we discuss recent progress on dysregulated metabolism of glucose, lipids and amino acids in premature infants with BPD and in related in vivo and in vitro models. These findings suggest that metabolic dysregulation may serve as a biomarker of BPD and plays important roles in the pathogenesis of this disease. We also highlight that targeting metabolic pathways could be employed in the prevention and treatment of BPD.

An Update on the Prevention and Management of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. There has been no change in the incidence of BPD over the past 20 years, despite improvements in survival and other outcomes. The preterm lung is vulnerable to injuries occurring as a result of invasive ventilation, hyperoxia, and infections that contribute to the development of BPD. Clinicians caring for infants in the neonatal intensive care unit use multiple therapies for the prevention and management of BPD. Non-invasive ventilation strategies and surfactant administration via thin catheters are treatment approaches that aim to avoid volutrauma and barotrauma to the preterm developing lung. Identifying high-risk infants to receive postnatal corticosteroids and undergo patent ductus arteriosus closure may help to individualize care and promote improved lung outcomes. In infants with established BPD, outpatient management is complex and requires coordination from several specialists and therapists. However, most current therapies used to prevent and manage BPD lack solid evidence to support their effectiveness. Further research is needed with appropriately defined outcomes to develop effective therapies and impact the incidence of BPD.

Development of a severity scale to assess chronic lung disease after extremely preterm birth

OBJECTIVE

Chronic lung disease of prematurity (CLDP) is a frequent complication of prematurity. We aimed to identify what clinicians believe are the most important factors determining the severity of CLDP in extremely preterm infants (<28 weeks gestational age) after discharge from the neonatal intensive care unit (NICU) through 12 months corrected age (CA), and to evaluate how these factors should be weighted for scoring, to develop a CLDP severity scale.

STUDY DESIGN

Clinicians completed a three-round online survey utilizing Delphi methodology. Clinicians rated the importance of various factors used to evaluate the severity of CLDP, from 0 (not at all important) to 10 (very important) for the period between discharge home from the NICU and 12 months CA. Fourteen factors were considered in Round 1; 13 in Rounds 2 and 3. The relative importance of factors was explored via a set of 16 single-profile tasks (i.e., hypothetical patient profiles with varying CLDP severity levels).

RESULTS

Overall, 91 clinicians from 11 countries who were experienced in treating prematurity-related lung diseases completed Round 1; 88 completed Rounds 2 and 3. Based on Round 3, the most important factors in determining CLDP severity were mechanical ventilation (mean absolute importance rating, 8.89), supplemental oxygen ≥2 L/min (8.49), rehospitalizations (7.65), and supplemental oxygen <2 L/min (7.56). Single-profile tasks showed that supplemental oxygen had the greatest impact on profile classification.

CONCLUSION

The most important factors for clinicians assigning CLDP severity during infancy were mechanical ventilation, supplemental oxygen ≥2 L/min, and respiratory-related rehospitalizations.

Respiratory effects of prolonged prednisolone use in infants with evolving and established Bronchopulmonary dysplasia

BACKGROUND

Current literature focuses on systemic corticosteroids for prevention of bronchopulmonary dysplasia (BPD) in preterm infants with limited data on use for pulmonary disease after the first month of life. Prednisolone may be a reasonable option for late treatment given its desirable pharmacologic properties and use in other pediatric disease states.

AIMS

To characterize a premature population that received an extended prednisolone course and determine the effect on respiratory and anthropometric outcomes over time.

STUDY DESIGN

Single-center, retrospective study.

SUBJECTS

Preterm infants who received ≥30 days of prednisolone or methylprednisolone for treatment of respiratory complications following preterm birth.

OUTCOMES MEASURES

Assessment of pulmonary severity score (PSS), weight, length, and occipital frontal circumference weekly during the first 4 weeks of prednisolone and after discontinuation.

RESULTS

Thirty-four infants with a mean gestational age of 26.5 ± 2.5 weeks and birth weight of 846 ± 353 g were identified. Nine patients were on invasive mechanical ventilation and 25 patients were on non-invasive respiratory support at prednisolone initiation. Prednisolone was initiated at a mean post-menstrual age of 41.7 ± 5 weeks and a mean dose of 1.7 ± 0.6 mg/kg/day. A significant decrease in PSS was seen over time (p < 0.001) without rebound following discontinuation. Eleven patients decreased the mode of respiratory support during prednisolone treatment. No significant impact in anthropometric outcomes were identified.

CONCLUSION

Prolonged prednisolone use was associated with a sustained decrease in PSS without adverse effects on growth measurements. These results suggest potential benefit of prednisolone on respiratory outcomes in a subset of preterm infants.

The association between diuretic class exposures and enteral electrolyte use in infants developing grade 2 or 3 bronchopulmonary dysplasia in United States children's hospitals

OBJECTIVE

To evaluate the association between chronic diuretic exposures and enteral electrolyte use in infants developing severe bronchopulmonary dysplasia (sBPD).

STUDY DESIGN

Retrospective longitudinal cohort study in infants admitted to United States children's hospitals. We identified diuretic exposures and measured enteral NaCl and KCl use during pre-defined exposure risk-interval days. We used mixed-effects logistic regression to model the association between diuretic exposures and electrolyte use.

RESULTS

We identified 442,341 subject-days in 3252 infants. All common diuretic classes and class combinations were associated with increased NaCl and KCl use. Thiazide monotherapy was associated with greater electrolyte use than loop monotherapy. The addition of potassium-sparing diuretics was associated with a limited reduction in KCl use compared to thiazide monotherapy.

CONCLUSIONS

Chronic diuretic exposures are associated with increased NaCl and KCl use. Presumptions about the relative impact of different diuretic classes on electrolyte derangements may be inaccurate and require further study.

New Pharmacologic Approaches to Bronchopulmonary Dysplasia

Bronchopulmonary Dysplasia is the most common long-term respiratory morbidity of preterm infants, with the risk of development proportional to the degree of prematurity. While its pathophysiologic and histologic features have changed over time as neonatal demographics and respiratory therapies have evolved, it is now thought to be characterized by impaired distal lung growth and abnormal pulmonary microvascular development. Though the exact sequence of events leading to the development of BPD has not been fully elucidated and likely varies among patients, it is thought to result from inflammatory and mechanical/oxidative injury from chronic ventilatory support in fragile, premature lungs susceptible to injury from surfactant deficiency, structural abnormalities, inadequate antioxidant defenses, and a chest wall that is more compliant than the lung. In addition, non-pulmonary issues may adversely affect lung development, including systemic infections and insufficient nutrition. Once BPD has developed, its management focuses on providing adequate gas exchange while promoting optimal lung growth. Pharmacologic strategies to ameliorate or prevent BPD continue to be investigated. A variety of agents, to be reviewed henceforth, have been developed or re-purposed to target different points in the pathways that lead to BPD, including anti-inflammatories, diuretics, steroids, pulmonary vasodilators, antioxidants, and a number of molecules involved in the cell signaling cascade thought to be involved in the pathogenesis of BPD.

Hyperoxia-induced bronchopulmonary dysplasia: better models for better therapies

Bronchopulmonary dysplasia (BPD) is a chronic lung disease caused by exposure to high levels of oxygen (hyperoxia) and is the most common complication that affects preterm newborns. At present, there is no cure for BPD. Infants can recover from BPD; however, they will suffer from significant morbidity into adulthood in the form of neurodevelopmental impairment, asthma and emphysematous changes of the lung. The development of hyperoxia-induced lung injury models in small and large animals to test potential treatments for BPD has shown some success, yet a lack of standardization in approaches and methods makes clinical translation difficult. In vitro models have also been developed to investigate the molecular pathways altered during BPD and to address the pitfalls associated with animal models. Preclinical studies have investigated the efficacy of stem cell-based therapies to improve lung morphology after damage. However, variability regarding the type of animal model and duration of hyperoxia to elicit damage exists in the literature. These models should be further developed and standardized, to cover the degree and duration of hyperoxia, type of animal model, and lung injury endpoint, to improve their translational relevance. The purpose of this Review is to highlight concerns associated with current animal models of hyperoxia-induced BPD and to show the potential of in vitro models to complement in vivo studies in the significant improvement to our understanding of BPD pathogenesis and treatment. The status of current stem cell therapies for treatment of BPD is also discussed. We offer suggestions to optimize models and therapeutic modalities for treatment of hyperoxia-induced lung damage in order to advance the standardization of procedures for clinical translation.

Spatiotemporal Changes in the Gene Expression Spectrum of the β2 Adrenergic Receptor Signaling Pathway in the Lungs of Rhesus Monkeys

Objective

β2 adrenergic receptor (ADRB2) agonists mainly participate in regulation of airway function through the ADRB2-G protein-adenylyl cyclase (AC) signaling pathway; however, the key genes associated with this pathway and the spatiotemporal changes in the expression spectrum of some of their subtypes remain unclear, resulting in an insufficient theoretical basis for formulating the dose and method of drug administration for neonates.

Methods

We performed sampling at different developmental time points in rhesus monkeys, including the embryo stage, neonatal stage, and adolescence. The MiSeq platform was used for sequencing of key genes and some of their subtypes in the ADRB2 signaling pathway in lung tissues, and target gene expression was normalized and calculated according to reads per kilobase million.

Results

At different lung-developmental stages, we observed expression of phenylethanolamine N-methyltransferase (PNMT), ADRB2, AC, AKAP and EPAC subtypes (except AC8, AKAP4/5), and various phosphodiesterase (PDE) subtypes (PDE3, PDE4, PDE7, and PDE8), with persistently high expression of AC6, PDE4B, and AKAP(1/2/8/9/12/13, and EZR) maintained throughout the lung-developmental process, PNMT, ADRB2, AC(4/6), PDE4B, and AKAP(1/2/8/9/12/13, EZR, and MAP2)were highly expressed at the neonatal stage.

Conclusion

During normal lung development in rhesus monkeys, key genes associated with ADRB2–G protein–AC signaling and some of their subtypes are almost all expressed at the neonatal stage, suggesting that this signaling pathway plays a role in this developmental stage. Additionally, AC6, PDE4B, and AKAP(1/2/8/9/12/13, and EZR) showed persistently high expression during the entire lung-developmental process, which provides a reference for the development and utilization of key gene subtypes in this pathway.

Enteral Vitamin A for Reducing Severity of Bronchopulmonary Dysplasia: A Randomized Trial

BACKGROUND AND OBJECTIVES

Evidence suggests that intramuscular vitamin A reduces the risk of bronchopulmonary dysplasia (BPD) in preterm infants. Our objective was to compare enteral water-soluble vitamin A with placebo supplementation to reduce the severity of BPD in extremely preterm infants.

METHODS

We conducted a double-blind randomized controlled trial in infants <28 weeks' gestation who were to receive either enteral water-soluble vitamin A (5000 IU per day) or a placebo. Supplementation was started within 24 hours of introduction of feeds and continued until 34 weeks' postmenstrual age (PMA). The primary outcome was the severity of BPD, assessed by using the right shift of the pulse oximeter saturation versus the inspired oxygen pressure curve.

RESULTS

A total of 188 infants were randomly assigned. The mean ± SD birth weight (852 ± 201 vs 852 ± 211 g) and gestation (25.8 ± 1.49 vs 26.0 ± 1.39 weeks) were comparable between the vitamin A and placebo groups. There was no difference in the right shift (median [25th-75th percentiles]) of the pulse oximeter saturation versus inspired oxygen pressure curve (in kilopascals) between the vitamin A (11.1 [9.5-13.7]) and placebo groups (10.7 [9.5-13.1]) (P = .73). Enteral vitamin A did not affect diagnosis of BPD or other clinical outcomes. Plasma retinol levels were significantly higher in the vitamin A group versus the placebo group on day 28 and at 34 weeks' PMA.

CONCLUSIONS

Enteral water-soluble vitamin A supplementation improves plasma retinol levels in extremely preterm infants but does not reduce the severity of BPD.

Lung ultrasound score and diuretics in preterm infants born before 32 weeks: A pilot study

OBJECTIVE

To describe if weekly determined lung ultrasound (LU) scores in preterm infants born before 32 weeks (PTB32W) change with diuretic therapy.

DESIGN

We included infants who received diuretics and compared LU scores according to their evolution on respiratory support (RS) before and after diuretics.

RESULTS

We included 18 PTB32W divided into two groups. Both groups were similar in terms of median gestational age: 26 weeks (interquartile range [IQR]: 25-28) in the responders' group and 27 weeks (IQR: 24-28) in the other. They differed, however, in the median number of days on invasive mechanical ventilation: 27 (IQR: 11-43) versus 76 (IQR: 35-117), p = .03; in addition to the number of infants with moderate-severe bronchopulmonary dysplasia: 3 (33%) versus 8 (89%), p = .025. The responders' group showed lower LU scores 2 days after diuretics, with a median LU score of 6 (IQR: 3-12) versus 14 (IQR: 12-17) in the nonresponders group, p = .03; 1 week after (3 [IQR: 0-10] versus 12 [12-12], p = .04); and 3 weeks after (5 [IQR: 3-6] versus 12 [10-15], p = .01). RS also decreased at the same time: 7 out of 9 (78%) were extubated in the responders' group, and 1 out of 9 (11%) in the nonresponders group, p = .02, and these differences remained throughout the entire follow-up.

CONCLUSIONS

There is a group of PTB32W patients whose LU score improves after diuretics. This change appears only in those patients that can be weaned off from RS, and at the same period of time as the administration of diuretics.

Body temperature instability and respiratory morbidity in the very low birth weight infant: a multiple case, intensive longitudinal study

Background

Very low birth weight (VLBW) infant thermal instability upon neonatal intensive care unit admission has been associated with respiratory morbidity; however, the association between ongoing thermal instability and respiratory morbidity remains unclear.

Methods

A longitudinal data analysis was conducted on 12 VLBW infants. Chronic respiratory morbidity risk was defined as supplemental oxygen requirement (FiO₂) or scheduled diuretic dosing at 36 weeks post-menstrual age. Acute respiratory morbidity was quantified as desaturations (SpO₂<90%), bradycardia with desaturations (HR<100 and SpO₂<90%), apnea, increase in FiO₂ requirement, or increase in respiratory support. Multi-level, mixed-effects models and regression analysis examined the relationships between body temperature over the first 14 days of life and respiratory morbidities.

Results

Body temperature was not associated with chronic respiratory morbidity risk (p=0.2765). Desaturations, bradycardia with desaturations, increased FiO₂ requirement, and increased respiratory support were associated with decreased body temperature (p<0.05). Apnea was associated with increased body temperature (p<0.05). The covariate-adjusted risk of desaturations (aOR=1.3), bradycardia with desaturations (aOR=2.2), increase in FiO₂ requirement (aOR=1.2), and increase in respiratory support (aOR=1.2) were significantly greater during episodes of hypothermia.

Conclusion

VLBW infants are dependent on a neutral thermal environment for optimal growth and development. Therefore, the significant associations between hypothermia and symptoms of acute respiratory morbidity require further study to delineate if these are causal relationships that could be attenuated with clinical practice changes, or if these are concurrent symptoms that cluster during episodes of physiological instability.

Impaired Autophagic Activity Contributes to the Pathogenesis of Bronchopulmonary Dysplasia. Evidence from Murine and Baboon Models

Bronchopulmonary dysplasia (BPD) is a common and serious complication associated with preterm birth. The pathogenesis of BPD is incompletely understood, and there is an unmet clinical need for effective treatments. The role of autophagy as a potential cytoprotective mechanism in BPD remains to be fully elucidated. In the present study, we investigated the role and regulation of autophagy in experimental models of BPD. Regulation and cellular distribution of autophagic activity during postnatal lung development and in neonatal hyperoxia-induced lung injury (nHILI) were assessed in the autophagy reporter transgenic GFP-LC3 (GFP-microtubule-associated protein 1A/1B-light chain 3) mouse model. Autophagic activity and its regulation were also examined in a baboon model of BPD. The role of autophagy in nHILI was determined by assessing lung morphometry, injury, and inflammation in autophagy-deficient Beclin 1 heterozygous knockout mice (Becn1^+/-). Autophagic activity was induced during alveolarization in control murine lungs and localized primarily to alveolar type II cells and macrophages. Hyperoxia exposure of neonatal murine lungs and BPD in baboon lungs resulted in impaired autophagic activity in association with insufficient AMPK (5'-AMP-activated protein kinase) and increased mTORC1 (mTOR complex 1) activation. Becn1^+/- lungs displayed impaired alveolarization, increased alveolar septal thickness, greater neutrophil accumulation, and increased IL-1β concentrations when exposed to nHILI. Becn1^+/- alveolar macrophages isolated from nHILI-exposed mice displayed increased expression of proinflammatory genes. In conclusion, basal autophagy is induced during alveolarization and disrupted during progression of nHILI in mice and BPD in baboons. Becn1^+/- mice are more susceptible to nHILI, suggesting that preservation of autophagic activity may be an effective protective strategy in BPD.

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.