Current pharmacologic approaches for prevention and treatment of bronchopulmonary dysplasia

Complex roles of TGF-β signaling pathways in lung development and bronchopulmonary dysplasia

As survival of extremely preterm infants continues to improve, there is also an associated increase in bronchopulmonary dysplasia (BPD), one of the most significant complications of preterm birth. BPD development is multifactorial resulting from exposure to multiple antenatal and postnatal stressors. BPD has both short-term health implications and long-term sequelae including increased respiratory, cardiovascular, and neurological morbidity. Transforming growth factor β (TGF-β) is an important signaling pathway in lung development, organ injury, and fibrosis and is implicated in the development of BPD. This review provides a detailed account on the role of TGF-β in antenatal and postnatal lung development, the effect of known risk factors for BPD on the TGF-β signaling pathway, and how medications currently in use or under development, for the prevention or treatment of BPD, affect TGF-β signaling.

Headway and the remaining hurdles of mesenchymal stem cells therapy for bronchopulmonary dysplasia

Objective

Preterm infants are at a high risk of developing BPD. Although progression in neonatal care has improved, BPD still causes significant morbidity and mortality, which can be attributed to the limited therapeutic choices for BPD. This review discusses the potential of MSC in treating BPD as well as their hurdles and possible solutions.

Data Sources

The search for data was not limited to any sites but was mostly performed on all clinical trials available in ClinicalTrials.gov as well as on PubMed by applying the following keywords: lung injury, preterm, inflammation, neonatal, bronchopulmonary dysplasia and mesenchymal stem cells.

Study Selections

The articles chosen for this review were collectively determined to be relevant and appropriate in discussing MSC not only as a potential treatment strategy for curbing the incidence of BPD but also including insights on problems regarding MSC treatment for BPD.

Results

Clinical trials regarding the use of MSC for BPD had good results but also illustrated insights on problems to be addressed in the future regarding the treatment strategy. Despite that, the clinical trials had mostly favourable reviews.

Conclusion

With BPD existing as a constant threat and there being no permanent solutions, the idea of regenerative medicine such as MSC may prove to be a breakthrough strategy when it comes to treating BPD. The success in clinical trials led to the formulation of prospective MSC‐derived products such as PNEUMOSTEM®, and there is the possibility of a stem cell medication and permanent treatment for BPD in the near future.

Bronchioalveolar stem cells in lung repair, regeneration and disease

Bronchioalveolar stem cells (BASCs) are a lung resident stem cell population located at bronchioalveolar duct junctions that contribute to the maintenance of bronchiolar club cells and alveolar epithelial cells of the distal lung. Their transformed counterparts are considered to be likely progenitors of lung adenocarcinomas, which has been a major area of research in relation to BASCs. A critical limitation in addressing the function of BASCs in vivo has been the lack of a unique BASC marker, which has prevented specific targeting of BASCs in animal models of respiratory conditions. Recently, there have been several studies describing genetically modified mice that allow in vivo quantification, tracing, and functional analysis of BASCs to address this long-standing issue. These cutting-edge experimental tools will likely have significant implications for future experimental studies involving BASCs and the elucidation of their role in various lung diseases. To date, this has been largely explored in models of lung injury including naphthalene-induced airway injury, bleomycin-induced alveolar injury, hyperoxia-induced models of bronchopulmonary dysplasia, and influenza virus infection. These novel experimental mouse tools will facilitate the assessment of the impact of BASC loss on additional respiratory conditions including infection-induced severe asthma and chronic obstructive pulmonary disease, as well as respiratory bacterial infections, both in early life and adulthood. These future studies may shed light on the potential broad applicability of targeting BASCs for a diverse range of respiratory conditions during lung development and in promoting effective regeneration and repair of the lung in respiratory diseases. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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

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

Pharmacotherapy for the Prevention of Bronchopulmonary Dysplasia: Can Anything Compete with Caffeine and Corticosteroids?

Bronchopulmonary dysplasia (BPD) is a morbidity of prematurity with implications for respiratory and neurologic health into adulthood. Multiple risk factors contribute to the development of BPD leading to examination of various prevention strategies. The roles of systemic corticosteroids and caffeine have been addressed by the American Academy of Pediatrics. The place in therapy of other agents commonly utilized in clinical practice remains unclear. Inhaled nitric oxide has been the subject of numerous large, randomized controlled trials in preterm infants. Despite sound rationale, these trials have largely failed to document benefit, suggesting a limited role for inhaled nitric oxide therapy in the preterm population. In contrast, intramuscular vitamin A has been documented to reduce the incidence of BPD in randomized trials. However, the invasiveness and the sporadic availability of this therapy have led to decreased utilization. All macrolide antibiotics do not appear to have a similar impact on the incidence of BPD; however, azithromycin administered to infants colonized with Ureaplasma may have impact. Questions remain about the optimal dosing approach and long-term safety of this intervention. Finally, diuretic therapy is widely used in clinical practice despite significant toxicities and limited data supporting a role in BPD prevention. Taken together, available data suggest that caffeine and selective use of corticosteroids remain the mainstays of pharmacologic BPD prevention.

Impact of breast milk on respiratory outcomes in infants with bronchopulmonary dysplasia

BACKGROUND

The objective of our study was to examine whether outpatient respiratory morbidities in infants with bronchopulmonary dysplasia (BPD) are influenced by the human milk consumption.

METHODS

Caregivers of subjects recruited from a BPD clinic completed questionnaires regarding breast milk intake and respiratory outcomes.

RESULTS

One-hundred eighty-eight caregivers completed the questionnaire. Of these, 173 (92.0%) reported that the child received some breast milk. Infants who received breast milk for fewer months were more likely to be non-white, and have a lower household income, public insurance, and secondhand smoke exposure. A longer receipt of breast milk was associated with reduced likelihoods of emergency department visits, systemic steroid courses, and cough or chest congestion, and a trend towards a lower risk of re-hospitalizations.

CONCLUSIONS

Longer duration of breast milk intake was associated with markers of higher socio-economic status, and reduced likelihood of acute and chronic respiratory morbidities among preterm infants with bronchopulmonary dysplasia.

Phosphodiesterase inhibitors: Potential role in the respiratory distress of neonates

Phosphodiesterases (PDEs) are a superfamily of enzymes that catalyze the hydrolysis of phosphodiester bonds of 3',5' cyclic adenosine and guanosine monophosphate (cAMP and cGMP). PDEs control hydrolysis of cyclic nucleotides in many cells and tissues. Inhibition of PDEs by selective or nonselective PDE inhibitors represents an effective targeted strategy for the treatment of various diseases including respiratory disorders. Recent data have demonstrated that PDE inhibitors can also be of benefit in respiratory distress in neonates. This article outlines the pharmacological properties of nonselective and selective PDE inhibitors and provides up-to-date information regarding their use in experimental models of neonatal respiratory distress as well as in clinical studies.

Vitamin A Supplementation by Endotracheal Application of a Nano-encapsulated Preparation Is Feasible in Ventilated Preterm Lambs

BACKGROUND

Vitamin A (VA) is crucial for lung growth and development. In premature infants, inadequate VA levels are associated with an increased risk of bronchopulmonary dysplasia (BPD). Intramuscular VA supplementation has been shown to decrease the incidence of BPD, but is not widely used in the clinical setting due to concerns about feasibility and pain. We studied VA kinetics, distribution, and the induction of early genetic expression of retinoid homeostatic genes in the lung after endotracheal and intravenous application in a preterm lamb model.

METHODS

Lambs were delivered prematurely after 85% of gestation, intubated, and ventilated for 3 hours. The animals were randomized to receive no VA ("control"), a bolus of VA intravenously ("i.v."), or VA endotracheally directly after administration of surfactant ("e.t.").

RESULTS

Animals treated with VA endotracheally directly after administration of surfactant showed significant increases of VA in serum and lung compared to controls. Animals treated with a bolus of VA intravenously showed significant increases of VA in serum, lung, and liver; however, peak serum concentrations and mRNA levels of homeostatic genes raised concerns about toxicity in this group.

CONCLUSIONS

Endotracheal VA supplementation in preterm lambs is feasible and might offer advantages in comparison to i.v. Further studies are warranted to explore biological effects in the context of BPD.

The 78-kD Glucose-Regulated Protein Regulates Endoplasmic Reticulum Homeostasis and Distal Epithelial Cell Survival during Lung Development

Bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, has been linked to endoplasmic reticulum (ER) stress. To investigate a causal role for ER stress in BPD pathogenesis, we generated conditional knockout (KO) mice (cGrp78(f/f)) with lung epithelial cell-specific KO of Grp78, a gene encoding the ER chaperone 78-kD glucose-regulated protein (GRP78), a master regulator of ER homeostasis and the unfolded protein response (UPR). Lung epithelial-specific Grp78 KO disrupted lung morphogenesis, causing developmental arrest, increased alveolar epithelial type II cell apoptosis, and decreased surfactant protein and type I cell marker expression in perinatal lungs. cGrp78(f/f) pups died immediately after birth, likely owing to respiratory distress. Importantly, Grp78 KO triggered UPR activation with marked induction of the proapoptotic transcription factor CCAAT/enhancer-binding proteins (C/EBP) homologous protein (CHOP). Increased expression of genes involved in oxidative stress and cell death and decreased expression of genes encoding antioxidant enzymes suggest a role for oxidative stress in alveolar epithelial cell (AEC) apoptosis. Increased Smad3 phosphorylation and expression of transforming growth factor-β/Smad3 targets Cdkn1a (encoding p21) and Gadd45a suggest that interactions among the apoptotic arm of the UPR, oxidative stress, and transforming growth factor-β/Smad signaling pathways contribute to Grp78 KO-induced AEC apoptosis and developmental arrest. Chemical chaperone Tauroursodeoxycholic acid reduced UPR activation and apoptosis in cGrp78(f/f) lungs cultured ex vivo, confirming a role for ER stress in observed AEC abnormalities. These results demonstrate a key role for GRP78 in AEC survival and gene expression during lung development through modulation of ER stress, and suggest the UPR as a potential therapeutic target in BPD.

Synthetic approaches towards the multi target drug spironolactone and its potent analogues/derivatives

Spironolactone is a well-known multi-target drug and is specifically used for the treatment of high blood pressure and heart failure. It is also used for the treatment of edema, cirrhosis of the liver, malignant, pediatric, nephrosis and primary hyperaldosteronism. Spironolactone in association with thiazide diuretics treats hypertension and in association with furosemide treats bronchopulmonary dyspepsia. The therapeutic mechanism of action of spironolactone involves binding to intracellular mineralocorticoids receptors (MRs) in kidney epithelial cells, thereby inhibiting the binding of aldosterone. Since its first synthesis in 1957 there are several synthetic approaches have been reported throughout the years, Synthetic community has devoted efforts to improve the synthesis of spironolactone and to synthesize its analogues and derivatives. This review aims to provide comprehensive insight for the synthetic endeavors devoted towards the synthesis of a versatile drug spironolactone and its analogues/derivatives.

[Clinical efficacy of pulmonary surfactant combined with budesonide for preventing bronchopulmonary dysplasia in very low birth weight infants]

OBJECTIVE

To explore the clinical efficacy of intratracheal instillation of pulmonary surfactant (PS) combined with budesonide for preventing bronchopulmonary dysplasia (BPD) in very low birth weight (VLBW) infants.

METHODS

Thirty VLBW infants with gestational age <32 weeks who developed neonatal respiratory distress syndrome (NRDS) (grade III-IV) suffering from intrauterine infection were randomly assigned into a PS + budesonide group and a PS alone group. The changes were compared between the two groups in arterial blood gas indexes, oxygenation index (OI), duration of mechanical ventilation, duration of oxygen supplementation, incidence of BPD, mortality rate at 36 weeks corrected gestational age and incidences of other complications except BPD.

RESULTS

Compared with the PS alone group, the PS+budesonide group had a lower incidence of BPD, shorter duration of mechanical ventilation and oxygen supplementation (P<0.05). On the 2nd to 6th day after treatment, the PS+budesonide group had higher pH value of arterial blood gas and OI and lower carbon dioxide partial pressure compared with the PS alone group (P<0.05). There were no significant differences in the mortality rate at 36 weeks corrected gestational age and the incidences of other complications except BPD between the two groups (P>0.05).

CONCLUSIONS

Intratracheal instillation of PS combined with budesonide can effectively reduce the incidence of BPD in VLBW premature infants with severe NRDS.

Mast cells and exosomes in hyperoxia-induced neonatal lung disease

Chronic lung disease of prematurity (CLD) is a frequent sequela of premature birth and oxygen toxicity is a major associated risk factor. Impaired alveolarization, scarring, and inflammation are hallmarks of CLD. Mast cell hyperplasia is a feature of CLD but the role of mast cells in its pathogenesis is unknown. We hypothesized that mast cell hyperplasia is a consequence of neonatal hyperoxia and contributes to CLD. Additionally, mast cell products may have diagnostic and prognostic value in preterm infants predisposed to CLD. To model CLD, neonatal wild-type and mast cell-deficient mice were placed in an O2 chamber delivering hyperoxic gas mixture [inspired O2 fraction (FiO2) of 0.8] (HO) for 2 wk and then returned to room air (RA) for an additional 3 wk. Age-matched controls were kept in RA (FiO2 of 0.21). Lungs from HO mice had increased numbers of mast cells, alveolar simplification and enlargement, and increased lung compliance. Mast cell deficiency proved protective by preserving air space integrity and lung compliance. The mast cell mediators β-hexosaminidase (β-hex), histamine, and elastase increased in the bronchoalveolar lavage fluid of HO wild-type mice. Tracheal aspirate fluids (TAs) from oxygenated and mechanically ventilated preterm infants were analyzed for mast cell products. In TAs from infants with confirmed cases of CLD, β-hex was elevated over time and correlated with FiO2. Mast cell exosomes were also present in the TAs. Collectively, these data show that mast cells play a significant role in hyperoxia-induced lung injury and their products could serve as potential biomarkers in evolving CLD.

Reviewing the use of corticosteroids in bronchopulmonary dysplasia

OBJECTIVE

Review the risks and benefits of postnatal corticosteroid use for the treatment of bronchopulmonary dysplasia, considering that there is not a more effective therapy.

DATA SOURCES

The literature review was carried out in the BIREME database, using the terms "bronchopulmonary dysplasia and corticosteroid" in the LILACS, IBECS, MEDLINE, Cochrane Library, and SciELO databases, selecting the most relevant articles on the subject, with emphasis on recent literature published in the last five years.

SUMMARY OF THE DATA

In preterm infants, bronchopulmonary dysplasia is still a common problem and remains without a specific therapy, despite knowledge of the several risk factors. The treatment essentially consists of supportive measures, but in the past, corticosteroids were widely used, as they are the only medications that have an impact on disease progression. However, the emergence of cerebral palsy associated with the indiscriminate use of corticosteroids has prevented the prescription of this drug in the last 15 years. Since then, no new measures have been taken, and the incidence of the disease tended to increase during this period, creating the need for a review of corticosteroid use and, possibly, more restricted indications.

CONCLUSIONS

The association between risks and benefits of corticosteroid use in preterm infants needs to be considered due to the fact that some infant subpopulations may show more benefits than risks, such as those using mechanical ventilation with difficult weaning.

Bronchopulmonary dysplasia: structural challenges and stem cell treatment potential

Bronchopulmonary dysplasia (BPD) continues to be a significant cause of morbidity and mortality for premature infants. Currently, most treatment strategies are mainly palliative and do not address the underlying structural changes of the lungs leading to the symptoms. New research and ongoing experiments with mesenchymal stem cells are showing capabilities to mitigate structural damage and promote vascular growth that leads to normal lung architecture in animal models. Looking at the pathophysiology that contributes to BPD and assessing current treatment options available, there still appears to be a gap in treatment that addresses the structural issues within the lungs. This article reviews the findings of several mesenchymal stem cell experiments and the potential for future treatment to help repair the lungs in infants with BPD.

Early postnatal additional high-dose oral vitamin A supplementation versus placebo for 28 days for preventing bronchopulmonary dysplasia or death in extremely low birth weight infants

BACKGROUND

Prematurity and the associated risk for bronchopulmonary dysplasia (BPD) remain a significant threat to extremely low birth weight (ELBW) infants. Vitamin A has been considered a therapeutic alternative in reducing the rate of BPD and mortality.

OBJECTIVES

To investigate whether early postnatal, additional high-dose oral vitamin A supplementation for 28 days is more efficient in reducing BPD or death in ELBW infants than placebo treatment.

METHODS

This is a multicenter, double-blind RCT comparing postnatal high-dose oral vitamin A supplementation (5,000 IU vitamin A/kg/day vs. placebo) for 28 days in ELBW neonates requiring mechanical ventilation, noninvasive ventilatory support or supplemental oxygen at 24 h of age. The primary end point is the proportion of children who died before 36 weeks' gestational age or developed moderate or severe BPD. BPD is defined as the need for supplemental oxygen to maintain SaO2 of ≥92% at rest at 36 weeks' postmenstrual age (PMA). Clinical secondary end points include the following: BPD (including mild form), intraventricular hemorrhage, periventricular leukomalacia, retinopathy of prematurity, necrotizing enterocolitis, total number of days of mechanical ventilation and oxygen supplementation, and safety and tolerability of high-dose vitamin A supplementation.

RESULTS AND CONCLUSIONS

The results of the NeoVitaA trial will provide robust data with regard to the efficacy of high-dose oral vitamin A supplementation in reducing the incidence of BPD or death at 36 weeks' PMA in ELBW infants.

An update on pharmacologic approaches to bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most prevalent long-term morbidity in surviving extremely preterm infants and is linked to increased risk of reactive airways disease, pulmonary hypertension, post-neonatal mortality, and adverse neurodevelopmental outcomes. BPD affects approximately 20% of premature newborns, and up to 60% of premature infants born before completing 26 weeks of gestation. It is characterized by the need for assisted ventilation and/or supplemental oxygen at 36 weeks postmenstrual age. Approaches to prevention and treatment of BPD have evolved with improved understanding of its pathogenesis. This review will focus on recent advancements and detail current research in pharmacotherapy for BPD. The evidence for both current and potential future experimental therapies will be reviewed in detail. As our understanding of the complex and multifactorial pathophysiology of BPD changes, research into these current and future approaches must continue to evolve.

Perinatal risk factors for bronchopulmonary dysplasia in a national cohort of very-low-birthweight infants

OBJECTIVE

We sought to assess the independent effect of perinatal factors on the risk for bronchopulmonary dysplasia (BPD) in very-low-birthweight infants.

STUDY DESIGN

This was a population-based observational study. Data were prospectively collected by the Israel Neonatal Network. Multivariable analyses identified independent risk factors for BPD.

RESULTS

Of 12,139 infants surviving to a postmenstrual age of 36 weeks, 1663 (13.7%) developed BPD. BPD was independently associated with young maternal age (odds ratio [OR], 1.53), maternal hypertensive disorders (OR, 1.28), antepartum hemorrhage (OR, 1.26), male gender (OR, 1.41), non-Jewish ethnicity (OR, 1.23), birth defects (OR, 1.94), small for gestational age (GA) (OR, 2.65), and delivery room resuscitation (OR, 1.86). Stratified analysis by GA groups showed that postdelivery resuscitation had a more pronounced effect with increasing maturity.

CONCLUSION

Perinatal factors and pregnancy complications were independently associated with development of BPD in very-low-birthweight infants. Most risk factors identified were consistent within GA groups.