Should we still use vitamin A to prevent bronchopulmonary dysplasia?

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.

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.

Vitamin A supplementation in very-preterm or very-low-birth-weight infants to prevent morbidity and mortality: a systematic review and meta-analysis of randomized trials

BACKGROUND

A previous systematic review showed that intramuscular vitamin A supplementation reduced the risk of bronchopulmonary dysplasia (BPD) in very-low-birth-weight (VLBW) infants. However, more recent studies have questioned this finding.

OBJECTIVES

Our objective was to synthesize current evidence on vitamin A supplementation in very-preterm (<32 wk gestational age) or VLBW infants and investigate the factors that may modify its efficacy.

METHODS

A systematic review was conducted using the Cochrane systematic review methodology. We included randomized controlled trials investigating vitamin A supplementation for reducing morbidity and mortality in very-preterm or VLBW infants. Certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) recommendations. Prespecified subgroup analyses assessed factors that may modify the effects of vitamin A supplementation.

RESULTS

We included 17 studies (n = 2471) in the qualitative and 15 studies (n = 2248) in the quantitative synthesis. Moderate-certainty evidence suggested a beneficial effect of vitamin A for decreasing the risk of BPD at 36 wk postmenstrual age (RR: 0.83; 95% CI: 0.74, 0.93; numbers needed to treat for an additional beneficial outcome: 16; 95% CI: 9, 53; 9 studies, n = 1752; P = 0.002). Subgroup analysis suggested that the beneficial effect was limited to infants with baseline vitamin A intake <1500 IU · kg-1 · d-1. Both enteral and parenteral routes were effective. Vitamin A supplementation did not have adverse effects and did not alter mortality before discharge (12 studies, n = 1917) or neurodevelopmental outcomes at 18-22 mo (1 study, n = 538).

CONCLUSIONS

The benefit of vitamin A supplementation for reducing BPD is likely to be limited to infants with baseline vitamin A intake <1500 IU · kg-1 · d-1 and is not affected by the route of administration.

Serum vitamin A levels as a novel predictor for respiratory distress syndrome in neonates: is it beneficial?

BACKGROUND

Neonatal respiratory distress syndrome (RDS) is a very important dangerous disease in neonates and is accompanied by neonatal complications and death.

OBJECTIVE

Early determination of neonatal serum vitamin A levels as a possible novel predictor for neonatal RDS.

PATIENTS AND METHODS

A case-control study, with the identification number TCTR20210206001 was done on 100 neonates who were admitted to the neonatal intensive care unit (NICU) of Tanta University Hospital (TUH) suffering from RDS (patient group) and 100 healthy neonates (control group). Estimation of serum vitamin A (retinol) was occurred for all neonates of this study within the first four hours after birth before any nutrition or therapies.

RESULTS

Showed no significant difference between serums retinol (RT) levels in grade 1&2 RDS neonates (patient group) and the serum RT levels in the control group while there was significant difference between serums retinol levels in grade 3&4 RDS neonates (patient group) and the serum retinol levels in the control group where the P-value was 0.006, 0.002 respectively.

CONCLUSION

Serum vitamin A levels in neonates were decreased in RDS neonates and could be used as a predictor for the development and severity of RDS.

RECOMMENDATION

Routine estimation of serum vitamin A levels in neonates as a novel predictor for neonatal RDS.

Should Vitamin A Injections to Prevent Bronchopulmonary Dysplasia or Death Be Reserved for High-Risk Infants? Reanalysis of the National Institute of Child Health and Human Development Neonatal Research Network Randomized Trial

OBJECTIVE

To determine whether infants at higher risk of bronchopulmonary dysplasia (BPD) or death benefit more from vitamin A therapy than those at lower risk.

STUDY DESIGN

We conducted a post hoc reanalysis of a landmark phase III randomized controlled trial conducted from January 1996 to July 1997 at 14 university-affiliated neonatal intensive care units in the US. Data analysis was performed from October 2019 to October 2020. Infants born weighing 401-1000 g and receiving respiratory support at 24 hours of age were assigned to intramuscular vitamin A 5000 IU or sham procedure 3 times weekly for 4 weeks. The primary outcome was BPD, defined as use of supplemental oxygen, or death at 36 weeks postmenstrual age. An externally validated model for predicting BPD or death was used to estimate the risk of these outcomes for each infant.

RESULTS

As previously reported, 222 of 405 infants (54.8%) assigned vitamin A therapy and 248 of 402 infants (61.7%) in the control group developed BPD or died (relative risk [RR], 0.89 [95% CI, 0.80-0.99]; risk difference [RD], -6.9% [95% CI, -13.0 to -0.7]). The predicted individual risks of BPD or death ranged from 7.1% to 98.6% (median, 61.5%; mean, 60.9%). The effect of vitamin A therapy on BPD or death depended on infants' risk of the primary outcome (P = .03 for interaction): for example, a RR of 0.73 (RD, -14.5%) for infants with a 25% predicted risk and a RR of 0.96 (RD, -1.0%) for infants with a 75% risk. There was no difference in the decrease in vitamin A deficiency across risk groups.

CONCLUSIONS

Contrary to expectations, the effect of vitamin A therapy on BPD or death was greater for lower risk than higher risk infants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01203488.

Severity of Bronchopulmonary Dysplasia Among Very Preterm Infants in the United States

BACKGROUND AND OBJECTIVES

The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network recently proposed new, severity-based diagnostic criteria for bronchopulmonary dysplasia (BPD). This study provides the first benchmark epidemiological data applying this definition.

METHODS

Retrospective cohort study of infants born from 22 to 29 weeks' gestation in 2018 at 715 US hospitals in the Vermont Oxford Network. Rates of BPD, major neonatal morbidities, and common respiratory therapies, stratified by BPD severity, were determined.

RESULTS

Among 24 896 infants, 2574 (10.3%) died before 36 weeks' postmenstrual age (PMA), 12 198 (49.0%) did not develop BPD, 9192 (36.9%) developed grade 1 or 2 BPD, and 932 (3.7%) developed grade 3 BPD. Rates of mortality before 36 weeks' PMA and grade 3 BPD decreased from 52.7% and 9.9%, respectively, among infants born at 22 weeks' gestation to 17.3% and 0.8% among infants born at 29 weeks' gestation. Grade 1 or 2 BPD peaked in incidence (51.8%) among infants born at 25 weeks' gestation. The frequency of severe intraventricular hemorrhage or cystic periventricular leukomalacia increased from 4.8% among survivors without BPD to 23.4% among survivors with grade 3 BPD. Similar ranges were observed for late onset sepsis (4.8%-31.4%), surgically treated necrotizing enterocolitis (1.4%-17.1%), severe retinopathy of prematurity (1.2%-23.0%), and home oxygen therapy (2.0%-67.5%).

CONCLUSIONS

More than one-half of very preterm infants born in the United States died before 36 weeks' PMA or developed BPD. Greater BPD severity was associated with more frequent development of major neonatal morbidities, in-hospital mortality, and use of supplemental respiratory support at discharge.

Attenuation of Hyperoxic Lung Injury in Newborn Thioredoxin-1-Overexpressing Mice through the Suppression of Proinflammatory Cytokine mRNA Expression

The role of thioredoxin-1 (TRX), a small redox-active protein with antioxidant effects, during hyperoxic lung injury in newborns remains undetermined. We investigated TRX impact on hyperoxic lung injury in newborn TRX transgenic (TRX-Tg) and wildtype (WT) mice exposed to 21% or 95% O₂ for four days, after which some mice were allowed to recover in room air for up to 14 days. Lung morphology was assessed by hematoxylin/eosin and elastin staining, as well as immunostaining for macrophages. The gene expression levels of proinflammatory cytokines were evaluated using quantitative real-time polymerase chain reaction. During recovery from hyperoxia, TRX-Tg mice exhibited an improved mean linear intercept length and increased number of secondary septa in lungs compared with the WT mice. Neonatal hyperoxia enhanced the mRNA expression levels of proinflammatory cytokines in the lungs of both TRX-Tg and WT mice. However, interleukin-6, monocyte chemoattractant protein-1, and chemokine (C-X-C motif) ligand 2 mRNA expression levels were reduced in the lungs of TRX-Tg mice compared with the WT mice during recovery from hyperoxia. Furthermore, TRX-Tg mice exhibited reduced macrophage infiltration in lungs during recovery. These results suggest that in newborn mice TRX ameliorates hyperoxic lung injury during recovery likely through the suppression of proinflammatory cytokines.

Nutrients and Microbiota in Lung Diseases of Prematurity: The Placenta-Gut-Lung Triangle

Cardiorespiratory function is not only the foremost determinant of life after premature birth, but also a major factor of long-term outcomes. However, the path from placental disconnection to nutritional autonomy is enduring and challenging for the preterm infant and, at each step, will have profound influences on respiratory physiology and disease. Fluid and energy intake, specific nutrients such as amino-acids, lipids and vitamins, and their ways of administration -parenteral or enteral-have direct implications on lung tissue composition and cellular functions, thus affect lung development and homeostasis and contributing to acute and chronic respiratory disorders. In addition, metabolomic signatures have recently emerged as biomarkers of bronchopulmonary dysplasia and other neonatal diseases, suggesting a profound implication of specific metabolites such as amino-acids, acylcarnitine and fatty acids in lung injury and repair, inflammation and immune modulation. Recent advances have highlighted the profound influence of the microbiome on many short- and long-term outcomes in the preterm infant. Lung and intestinal microbiomes are deeply intricated, and nutrition plays a prominent role in their establishment and regulation. There is an emerging evidence that human milk prevents bronchopulmonary dysplasia in premature infants, potentially through microbiome composition and/or inflammation modulation. Restoring antibiotic therapy-mediated microbiome disruption is another potentially beneficial action of human milk, which can be in part emulated by pre- and probiotics and supplements. This review will explore the many facets of the gut-lung axis and its pathophysiology in acute and chronic respiratory disorders of the prematurely born infant, and explore established and innovative nutritional approaches for prevention and treatment.

Oral vitamin A supplementation in very low birth weight neonates: a randomized controlled trial

This randomized double-blind placebo-controlled trial evaluated the effects of early postnatal oral vitamin A supplementation (VAS) in 196 inborn very-low birth weight (VLBW) infants requiring respiratory support at 24 h of age. Eligible infants were randomized to receive aqueous syrup of vitamin A (10,000 IU of retinol/dose; n = 98) or placebo (n = 98) on alternate days for 28 days. Primary outcome variable was composite incidence of all-cause mortality and/or oxygen requirement for 28 days. Secondary outcome variables were safety/tolerability of VAS, serum retinol concentration at recruitment and day 28, duration of oxygen requirement and respiratory support and incidences of complications. On intention-to-treat analysis, composite incidence of all-cause mortality and oxygen requirement for 28 days was significantly lower in vitamin A group (relative risk (95% confidence interval), 0.440 (0.229-0.844); p < 0.05, number needed to benefit, 7). Requirement and duration of oxygen supplementation and non-invasive respiratory support, incidences of late-onset sepsis, patent ductus arteriosus, and duration of hospital stay were also significantly lower in vitamin A group. Serum retinol concentration improved significantly after VAS. No major adverse effect was observed.Conclusions: Early postnatal oral VAS was associated with better composite outcome of all-cause mortality and oxygen requirement without any major adverse effects.Clinical Trial Registration: Clinical Trials Registry of India (CTRI/2017/03/008131). What is Known: • Postnatal intramuscular vitamin A supplementation improves the survival, respiratory outcome and other morbidities in very low birth weight neonates without major adverse effects. • Limited studies on oral vitamin A supplementation did not document substantial benefits. What is New: • Early postnatal alternate-day oral vitamin A supplementation at the dose of 10,000 IU/dose for 28 days improves the composite outcome of death and oxygen requirement in very low birth weight neonates with respiratory distress • No major adverse effects were documented.

Furosemide Exposure and Prevention of Bronchopulmonary Dysplasia in Premature Infants

OBJECTIVE

To evaluate the association between furosemide exposure and risk of bronchopulmonary dysplasia (BPD).

STUDY DESIGN

This retrospective cohort study included infants (2004-2015) born at 23-29 weeks gestational age and 501-1249 g birth weight. We compared the demographic and clinical characteristics of infants exposed and not exposed to furosemide between postnatal day 7 and 36 weeks postmenstrual age. We examined the association between furosemide exposure and 2 outcomes: BPD and BPD or death. We performed multivariable probit regression models that included demographic and clinical variables in addition to 2 instrumental variables: furosemide exposure by discharge year, and furosemide exposure by site.

RESULTS

Of 37 693 included infants, 19 235 (51%) were exposed to furosemide; these infants were more premature and had higher respiratory support. Of 33 760 infants who survived to BPD evaluation, 15 954 (47%) had BPD. An increase in the proportion of furosemide exposure days by 10 percentage points was associated with a decrease in both the incidence of BPD (4.6 percentage points; P = .001), and BPD or death (3.7 percentage points; P = .01).

CONCLUSIONS

More days of furosemide exposure between postnatal day 7 and 36 weeks was associated with decreased risk of BPD and a combined outcome of BPD or death.

Bronchopulmonary Dysplasia: An Update of Current Pharmacologic Therapies and New Approaches

Bronchopulmonary dysplasia (BPD) remains the most prevalent long-term morbidity of surviving extremely preterm infants and is associated with significant health care utilization in infancy and beyond. Recent advances in neonatal care have resulted in improved survival of extremely low birth weight (ELBW) infants; however, the incidence of BPD has not been substantially impacted by novel interventions in this vulnerable population. The multifactorial cause of BPD requires a multi-pronged approach for prevention and treatment. New approaches in assisted ventilation, optimal nutrition, and pharmacologic interventions are currently being evaluated. The focus of this review is the current state of the evidence for pharmacotherapy in BPD. Promising future approaches in need of further study will also be reviewed.

Newborn Mice Lacking the Gene for Cyp1a1 Are More Susceptible to Oxygen-Mediated Lung Injury, and Are Rescued by Postnatal β-Naphthoflavone Administration: Implications for Bronchopulmonary Dysplasia in Premature Infants

Prolonged hyperoxia contributes to bronchopulmonary dysplasia (BPD) in preterm infants. β-Naphthoflavone (BNF) is a potent inducer of cytochrome P450 (CYP)1A enzymes, which have been implicated in hyperoxic injuries in adult mice. In this investigation, we tested the hypothesis that newborn mice lacking the Cyp1a1 gene would be more susceptible to hyperoxic lung injury than wild-type (WT) mice and that postnatal BNF treatment would rescue this phenotype by mechanisms involving CYP1A and/or NAD(P)H quinone oxidoreductase (NQO1) enzymes. Newborn WT or Cyp1a1-null mice were treated with BNF (10 mg/kg) or the vehicle corn oil (CO) i.p., from postnatal day (PND) 2 to 14 once every other day, while being maintained in room air or hyperoxia (85% O2) for 14 days. Both genotypes showed lung injury, inflammation, and alveolar simplification in hyperoxia, with Cyp1a1-null mice displaying increased susceptibility compared to WT mice. BNF treatment resulted in significant attenuation of lung injury and inflammation, with improved alveolarization in both WT and Cyp1a1-null mice. BNF exposed normoxic or hyperoxic WT mice showed increased expression of hepatic CYP1A1/1A2, pulmonary CYP1A1, and NQO1 expression at both mRNA and protein levels, compared with vehicle controls. However, BNF caused greater induction of hepatic CYP1A2 and pulmonary NQO1 enzymes in the Cyp1a1-null mice, suggesting that BNF protects against hyperoxic lung injury in WT and Cyp1a1-null mice through the induction of CYP1A and NQO1 enzymes. Further studies on the protective role of flavonoids against hyperoxic lung injury in newborns could lead to novel strategies for the prevention and/or treatment of BPD.

Quercetin attenuates the hyperoxic lung injury in neonatal mice: Implications for Bronchopulmonary dysplasia (BPD)

Quercetin (QU) is one of the most common flavonoids that are present in a wide variety of fruits, vegetables, and beverages. This compound possesses potent anti-inflammatory and anti-oxidant properties. Supplemental oxygen is routinely administered to premature infants with pulmonary insufficiency. However, hyperoxia is one of the major risk factors for the development of bronchopulmonary dysplasia (BPD), which is also termed chronic lung disease in premature infants. Currently, no preventive approaches have been reported against BPD. The treatment of BPD is notably limited to oxygen administration, ventilatory support, and steroids. Since QU has been shown to be effective in reducing inflammation and oxidative stress in various disease models, we hypothesized that the postnatal QU treatment of newborn mice will protect against hyperoxic lung injury by the upregulation of the phase I (CYP1A/B) and/or phase II, NADPH quinone reductase enzymes. Newborn C57BL/6J mice within 24 h of birth with the nursing dams were exposed to either 21% O₂ (air) and/or 85% O₂ (hyperoxia) for 7 days. The mice were treated, intraperitoneally (i.p.) once every other day with quercetin, at a concentration of 20 mg/kg, or saline alone from postnatal day (PND) 2-6. The mice were sacrificed on day 7, and lung and liver tissues were collected. The expression levels of CYP1A1, CYP1B1, NQO1 proteins and mRNA as well as the levels of MDA-protein adducts were analyzed in lung and liver tissues. The findings indicated that QU attenuated hyperoxia-mediated lung injury by reducing inflammation and improving alveolarization with decreased number of neutrophil and macrophage infiltration. The attenuation of this lung injury correlated with the upregulation of CYP1A1/CYP1B1/NQO1 mRNA, proteins and the down regulation of NF-kB levels and MDA-protein adducts in lung and liver tissues. The present study demonstrated the potential therapeutic value of quercetin in the prevention and/or treatment of BPD.

"Good things come in small packages": application of exosome-based therapeutics in neonatal lung injury

Infants born at very low gestational age contribute disproportionately to neonatal morbidity and mortality. Advancements in antenatal steroid therapies and surfactant replacement have favored the survival of infants with ever-more immature lungs. Despite such advances in medical care, cardiopulmonary and neurological impairment prevail in constituting the major adverse outcomes for neonatal intensive care unit survivors. With no single effective therapy for either the prevention or treatment of such neonatal disorders, the need for new tools to treat and reduce risk of further complications associated with extreme preterm birth is urgent. Mesenchymal stem/stromal cell (MSC)-based approaches have shown promise in numerous experimental models of lung injury relevant to neonatology. Recent studies have highlighted that the therapeutic potential of MSCs is harnessed in their secretome, and that the therapeutic vector therein is represented by the exosomes released by MSCs. In this review, we summarize the development and significance of stem cell-based therapies for neonatal diseases, focusing on preclinical models of neonatal lung injury. We emphasize the development of MSC exosome-based therapeutics and comment on the challenges in bringing these promising interventions to clinic.

Enteral vitamin A for reducing severity of bronchopulmonary dysplasia in extremely preterm infants: a randomised controlled trial

Background

Intramuscular vitamin A supplementation decreases the risk of bronchopulmonary dysplasia (BPD) in very-low-birth-weight preterm infants without significant adverse effects. However, intramuscular vitamin A supplementation is not widely accepted because of the discomfort and risk of trauma associated with repeated injections. Enteral vitamin A supplementation has not been studied adequately in the clinical trials. Enterally administered water-soluble vitamin A is absorbed better than the fat-soluble form. We hypothesised that enteral administration of a water-soluble vitamin A preparation will decrease severity of BPD compared with a control group receiving placebo.

Methods

We plan a double-blind randomised placebo-controlled trial at a tertiary neonatal-perinatal intensive care unit. Eligibility criteria include infants born at less than 28 weeks’ gestational age and less than 72 h of life. Infants with major congenital gastrointestinal or respiratory tract abnormalities will be excluded. After parental consent, infants will be randomized to receive either enteral water-soluble vitamin A (5000 IU once a day) or placebo. The intervention will be started within 24 h of introduction of feeds and continued until 34 weeks’ post-menstrual age (PMA).

The primary outcome is severity of BPD at 36 weeks’ PMA. Severity of BPD will be assessed objectively from the right-shift of the peripheral oxyhaemoglobin saturation versus partial pressure of inspired oxygen (SpO₂-PiO₂) curve. We require 188 infants for 80% power and 5% significance level based on an expected 20% decrease in the right shift of the SpO₂-PiO₂ curve in the vitamin A group (primary outcome) compared with control group at 36 weeks’ PMA, and a 20% attrition rate.

Secondary outcomes will be plasma and salivary concentrations of vitamin A on day 28 of the trial (first 30 infants), lung and diaphragm function, clinical outcomes at 36 week’ PMA or before discharge/death, and safety of vitamin A.

Discussion

BPD poses a significant economic burden on the health-care system. If our study shows that enteral supplementation of water-soluble vitamin A is safe and effective for decreasing the severity of BPD, it will provide the opportunity to further evaluate a simple, globally acceptable preventive therapy for BPD.

Trial registration

ANZCTR; ACTRN12616000408482 (30th March 2016).

Electronic supplementary material

The online version of this article (10.1186/s12887-017-0958-x) contains supplementary material, which is available to authorized users.

Prevention of bronchopulmonary dysplasia: current strategies

Bronchopulmonary dysplasia (BPD) is one of the few diseases affecting premature infants that have continued to evolve since its first description about half a century ago. The current form of BPD, a more benign and protracted respiratory failure in extremely preterm infants, is in contrast to the original presentation of severe respiratory failure with high mortality in larger premature infants. This new BPD is end result of complex interplay of various antenatal and postnatal factors causing lung injury and subsequent abnormal repair leading to altered alveolar and vascular development. The change in clinical and pathologic picture of BPD over time has resulted in new challenges in developing strategies for its prevention and management. While some of these strategies like Vitamin A supplementation, caffeine and volume targeted ventilation have stood the test of time, others like postnatal steroids are being reexamined with great interest in last few years. It is quite clear that BPD is unlikely to be eliminated unless some miraculous strategy cures prematurity. The future of BPD prevention will probably be a combination of antenatal and postnatal strategies acting on multiple pathways to minimize lung injury and abnormal repair as well as promote normal alveolar and vascular development.

Linking bronchopulmonary dysplasia to adult chronic lung diseases: role of WNT signaling

Bronchopulmonary dysplasia (BPD) is one of the most common chronic lung diseases in infants caused by pre- and/or postnatal lung injury. BPD is characterized by arrested alveolarization and vascularization due to extracellular matrix remodeling, inflammation, and impaired growth factor signaling. WNT signaling is a critical pathway for normal lung development, and its altered signaling has been shown to be involved in the onset and progression of incurable chronic lung diseases in adulthood, such as chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF). In this review, we summarize the impact of WNT signaling on different stages of lung development and its potential contribution to developmental lung diseases, especially BPD, and chronic lung diseases in adulthood.