Bronchopulmonary dysplasia in preterm infants: pathophysiology and management strategies

Intratracheal Administration of Budesonide with Surfactant for Prevention of Death or Bronchopulmonary Dysplasia in Extremely Low Birth Weight Infants: A before-after Study

OBJECTIVE

 Previous studies have suggested a potential role for inhaled corticosteroids, such as budesonide, in reducing bronchopulmonary dysplasia (BPD) among preterm infants. The objective of our study was to investigate the effectiveness of intratracheal administration of corticosteroid with surfactant on the composite outcome of death or BPD at 36 weeks in extremely low birth weight (ELBW) infants.

STUDY DESIGN

 This before-after cohort study compared outcomes in ELBW infants with respiratory distress syndrome (RDS) who received intratracheal surfactant with budesonide to a historical cohort who received surfactant alone. Data were collected retrospectively for neonates in the surfactant group and prospectively for those receiving surfactant plus budesonide.

RESULTS

 A total of 385 ELBW infants were included. Death or BPD occurred in 123/203 (60.5%) in the surfactant with budesonide group versus 105/182 (57.6%) in the surfactant group; adjusted odds ratio 1.10 (95% CI: 0.69-1.75; p = 0.69). Statistical analysis revealed no significant difference in the incidence of the composite primary outcome (death or BPD at 36 weeks of postmenstrual gestational age), and its components, between the two study groups.

CONCLUSION

 In our study, coadministration of budesonide and surfactant was deemed safe and feasible among ELBW infants with RDS. However, we did not observe a significant reduction in the rates of composite or individual outcomes of death or BPD. Larger, randomized controlled trials are necessary to explore the potential advantages of this intervention.

KEY POINTS

· Small clinical trials have shown promising benefits of intratracheal administration of budesonide with surfactant for improving respiratory outcomes in preterm infants.. · This before-after intervention study showed that intratracheal budesonide with surfactant was safe and feasible in ELBW infants.. · However, coadministration of budesonide and surfactant did not reduce the composite outcome of death or BPD in the study population..

A Paternal Fish Oil Diet Preconception Reduces Lung Inflammation in a Toxicant-Driven Murine Model of New Bronchopulmonary Dysplasia

New bronchopulmonary dysplasia (BPD) is a neonatal disease that is theorized to begin in utero and manifests as reduced alveolarization due to inflammation of the lung. Risk factors for new BPD in human infants include intrauterine growth restriction (IUGR), premature birth (PTB) and formula feeding. Using a mouse model, our group recently reported that a paternal history of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure increased his offspring's risk of IUGR, PTB, and new BPD. Additionally, formula supplementation of these neonates worsened the severity of pulmonary disease. In a separate study, we reported that a paternal preconception fish oil diet prevented TCDD-driven IUGR and PTB. Not surprisingly, eliminating these two major risk factors for new BPD also significantly reduced development of neonatal lung disease. However, this prior study did not examine the potential mechanism for fish oil's protective effect. Herein, we sought to determine whether a paternal preconception fish oil diet attenuated toxicant-associated lung inflammation, which is an important contributor to the pathogenesis of new BPD. Compared to offspring of standard diet TCDD-exposed males, offspring of TCDD-exposed males provided a fish oil diet prior to conception exhibited a significant reduction in pulmonary expression of multiple pro-inflammatory mediators (Tlr4, Cxcr2, Il-1 alpha). Additionally, neonatal lungs of pups born to fish oil treated fathers exhibited minimal hemorrhaging or edema. Currently, prevention of BPD is largely focused on maternal strategies to improve health (e.g., smoking cessation) or reduce risk of PTB (e.g., progesterone supplementation). Our studies in mice support a role for also targeting paternal factors to improve pregnancy outcomes and child health.

Comparative effectiveness of calfactant and beractant in neonatal respiratory distress syndrome: A systemic review and meta-analysis

INTRODUCTION

Animal derived surfactants are considered to be the standard treatment for neonatal respiratory distress syndrome (NRDS). However, their comparative effectiveness remains inconclusive given the multiple prior studies with inconsistent results. Therefore, we conducted a systematic review and meta analysis to compare the effectiveness of two animal extract surfactants (calfactant and beractant) for the management of NRDS.

METHODS

We searched Pubmed, Scopus, and Google Scholar for studies comparing efficacy of calfactant and beractant for the treatment of NRDS. Mean differences (MD) and risk ratios (RR) with a 95% confidence interval (CI) were calculated using Review Manager.

RESULT

We found no significant difference between calfactnat and beractant groups in the primary outcomes: neonatal mortality before the age of 28 days (RR = 1.19, 95% CI = 0.97-1.46, p = 0.09), mortality before the hospital release (RR = 1.12, 95% Cl = 0.94-1.33, p = 0.22), oxygen requirement at 28 days of age (RR = 0.97, 95% CI = 0.90-1.05, p = 0.52), and death or oxygen need at 36 weeks postmenstrual age (RR = 0.99, 95% CI = 0.91-1.08, p = 0.81). The duration of supplementary oxygen was significantly lower in calfactant users (MD = -4.95, 95% CI = -7.60--2.30, p = 0.0002). Calfactant significantly lowered the duration of hospital stay, risk of pneumothorax and air leak syndrome whereas beractant users had lower risk of intraventricular hemorrhage (Grades 3 and 4).

CONCLUSION

There is no substantial difference in the efficacy of both surfactants in the prophylaxis and treatment of NRDS.

Polymorphisms of fibronectin-1 (rs3796123; rs1968510; rs10202709; rs6725958; and rs35343655) are not associated with bronchopulmonary dysplasia in preterm infants

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that mainly affects premature newborns. Many different factors, increasingly genetic, are involved in the pathogenesis of BPD. The aim of the study is to investigate the possible influence of fibronectin SNP on the occurrence of BPD. The study included 108 infants born between 24 and 32 weeks of gestation. BPD was diagnosed based on the National Institutes of Health Consensus definition. The 5 FN1 gene polymorphisms assessed in the study were the following: rs3796123; rs1968510; rs10202709; rs6725958; and rs35343655. BPD developed in 30 (27.8%) out of the 108 preterm infants. Incidence of BPD was higher in infants with lower APGAR scores and low birthweight. Investigation did not confirm any significant prevalence for BPD development in any genotypes and alleles of FN1. Further studies should be performed to confirm the role of genetic factors in etiology and pathogenesis of BPD.

A Preconception Paternal Fish Oil Diet Prevents Toxicant-Driven New Bronchopulmonary Dysplasia in Neonatal Mice

New bronchopulmonary dysplasia is a developmental lung disease associated with placental dysfunction and impaired alveolarization. Risk factors for new BPD include prematurity, delayed postnatal growth, the dysregulation of epithelial-to-mesenchymal transition (EMT), and parental exposure to toxicants. Our group previously reported that a history of paternal toxicant exposure increased the risk of prematurity and low birth weight in offspring. A history of paternal toxicant exposure also increased the offspring's risk of new BPD and disease severity was increased in offspring who additionally received a supplemental formula diet, which has also been linked to poor lung development. Risk factors associated with new BPD are well-defined, but it is unclear whether the disease can be prevented. Herein, we assessed whether a paternal fish oil diet could attenuate the development of new BPD in the offspring of toxicant exposed mice, with and without neonatal formula feeding. We investigated the impact of a paternal fish oil diet preconception because we previously reported that this intervention reduces the risk of TCDD associated placental dysfunction, prematurity, and low birth weight. We found that a paternal fish oil diet significantly reduced the risk of new BPD in neonatal mice with a history of paternal toxicant exposure regardless of neonatal diet. Furthermore, our evidence suggests that the protective effects of a paternal fish oil diet are mediated in part by the modulation of small molecules involved in EMT.

The role of cytochrome P450 (CYP) enzymes in hyperoxic lung injury

INTRODUCTION

Hyperoxic lung injury is a condition that can occur in patients in need of supplemental oxygen, such as premature infants with bronchopulmonary dysplasia or adults with acute respiratory distress syndrome. Cytochrome P450 (CYP) enzymes play critical roles in the metabolism of endogenous and exogenous compounds.

AREAS COVERED

Through their complex pathways, some subfamilies of these enzymes may contribute to or protect against hyperoxic lung injury. Oxidative stress from reactive oxygen species (ROS) production is most likely a major contributor of hyperoxic lung injury. CYP1A enzymes have been shown to protect against hyperoxic lung injury while CYP1B enzymes seem to contribute to it. CYP2J2 enzymes help protect against hyperoxic lung injury by triggering EET production, thereby, increasing antioxidant enzymes. The metabolism of arachidonic acid to ω-terminal hydroxyeicosatetraenoic acid (20-HETEs) by CYP4A and CYP4F enzymes could impact hyperoxic lung injury via the vasodilating effects of 20-HETE. CYP2E1 and CYP2A enzymes may contribute to the oxidative stress in the lungs caused by ethanol- and nicotine-metabolism, respectively.

EXPERT OPINION

Overall, the CYP enzymes, depending upon the isoform, play a contributory or protective role in hyperoxic lung injury, and are, therefore, ideal candidates for developing drugs that can treat oxygen-mediated lung injury.

Impact and Clinical Implications of Prematurity on Adaptive Immune Development

Purpose of Review

Detail normal adaptive immune maturation during fetal and neonatal life and review the clinical implications of arrested immune development.

Recent Findings

Advancements in the field of immunology have enabled investigations of the adaptive immunity starting during fetal life. New insights have drawn important distinctions between the neonatal and adult immune systems. The presence of diverse immunologic responses in the perinatal period suggests the importance of in utero immune development. Disruption of immune maturation due to premature birth may have significant implications for clinical pathology.

Summary

Establishing protective adaptive immunity during the perinatal period is critical for effective immune responses later in life. Preterm infants are susceptible to aberrant immune system maturation and inflammatory immune responses have been associated with the development of necrotizing enterocolitis (NEC) and bronchopulmonary dysplasia (BPD). Improving our understanding of how immune responses contribute to the pathogenesis of NEC and BPD may offer new opportunities for future treatment and prevention of these diseases.

Effect of sustained inflations and intermittent positive pressure ventilation on bronchopulmonary dysplasia or death among neonatal: A protocol for systematic review

BACKGROUND

Sustained Inflations (SI) and Intermittent Positive Pressure Ventilation (IPPV) are two interventions to prevent Bronchopulmonary dysplasia (BPD). The aim of this study is to assess the effect of these two interventions.

METHODS

The databases of PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) will be comprehensively searched from inception to September 2019. All RCTs and quasi-RCTs which compare the efficacy of SI vs IPPV among preterm infants are eligible. We will assess the methodological quality using the Cochrane Handbook version 5.1.0. A meta-analysis will be performed using RevMan 5.3 software and the results will be presented using risk ratios (RRs) and 95% confidence intervals (CIs).

CONCLUSIONS

This study will provide strong evidence for assessing the effect of SI and IPPV on BPD or death among preterm infants.

PROSPERO REGISTRATION NUMBER

CRD42019135816.

Randomised controlled trial on the impact of kinesthetic stimulation on early somatic growth of preterm infants in Kangaroo position

AIM

Evaluation of early growth in preterm infants receiving kinesthetic stimulation with massage in Kangaroo position or in incubator.

METHODS

A cohort of 66 infants between 30 and 33 weeks of gestational age (GA), born at a university hospital in 2013 in Bogota, were randomised when eligible to intervention. We measured weight gain (g/kg/day) at five days and 15 days postrandomisation and weight at 40 weeks, according to chronological age at randomisation.

RESULTS

Daily weight gain was significantly higher (p = 0.02) with kinesthetic stimulation in Kangaroo position with a growth at five days of 11.0 g/kg/day (95% CI 5.7;16.3) and at 15 days of 12.1 g/kg/day (95% CI 10.4;13.7) versus 2.1 g/kg/day (95% CI -3.1;7.4) at five days and 9.4 g/kg/day (95% CI 7.7;11.1) at 15 days in incubator. Weight at 40 weeks was higher (p = 0.05) in Kangaroo position group (2.904 g) than in incubator group (2.722 g) (95% CI 2.784;3.007). Daily weight gain according to chronological age at randomisation was higher when kinesthetic stimulation initiates before five days of life in Kangaroo position with 1.53 g/kg/day (95% CI 5.9;9.0) versus -11.9 g/kg/day (95% CI -19.0;-4.8) in incubator.

CONCLUSION

Early kinesthetic stimulation in Kangaroo position reduces the initial weight loss in infants between 30-33 weeks born without major health problems.

Respiratory Medications in Infants <29 Weeks during the First Year Postdischarge: The Prematurity and Respiratory Outcomes Program (PROP) Consortium

OBJECTIVE

To determine patterns of respiratory medications used in neonatal intensive care unit graduates.

STUDY DESIGN

The Prematurity Respiratory Outcomes Program enrolled 835 babies <29 weeks of gestation in the first week. Of 751 survivors, 738 (98%) completed at least 1, and 85% completed all 4, postdischarge medication usage in-person/telephone parental questionnaires requested at 3, 6, 9, and 12 months of corrected age. Respiratory drug usage over the first year of life after in neonatal intensive care unit discharge was analyzed.

RESULTS

During any given quarter, 66%-75% of the babies received no respiratory medication and 45% of the infants received no respiratory drug over the first year. The most common postdischarge medication was the inhaled bronchodilator albuterol; its use increased significantly from 13% to 31%. Diuretic usage decreased significantly from 11% to 2% over the first year. Systemic steroids (prednisone, most commonly) were used in approximately 5% of subjects in any one quarter. Inhaled steroids significantly increased over the first year from 9% to 14% at 12 months. Drug exposure changed significantly based on gestational age with 72% of babies born at 23-24 weeks receiving at least 1 respiratory medication but only 40% of babies born at 28 weeks. Overall, at some time in the first year, 55% of infants received at least 1 drug including an inhaled bronchodilator (45%), an inhaled steroid (22%), a systemic steroid (15%), or diuretic (12%).

CONCLUSION

Many babies born at <29 weeks have no respiratory medication exposure postdischarge during the first year of life. Inhaled medications, including bronchodilators and steroids, increase over the first year.

Paving the Road for Mesenchymal Stem Cell-Derived Exosome Therapy in Bronchopulmonary Dysplasia and Pulmonary Hypertension

Bronchopulmonary dysplasia (BPD) is a chronic neonatal lung disease characterized by inflammation and arrest of alveolarization. Its common sequela, pulmonary hypertension (PH), presents with elevated pulmonary vascular resistance associated with remodeling of the pulmonary arterioles. Despite notable advancements in neonatal medicine, there is a severe lack of curative treatments to help manage the progressive nature of these diseases. Numerous studies in preclinical models of BPD and PH have demonstrated that therapies based on mesenchymal stem/stromal cells (MSCs) can resolve pulmonary inflammation and ameliorate the severity of disease. Recent evidence suggests that novel, cell-free approaches based on MSC-derived exosomes (MEx) might represent a compelling therapeutic alternative offering major advantages over treatments based on MSC transplantation. Here, we will discuss the development of MSC-based therapies, stressing the centrality of paracrine action as the actual vector of MSC therapeutic functionality, focusing on MEx. We will briefly present our current understanding of the biogenesis and secretion of MEx, and discuss potential mechanisms by which they afford such beneficial effects, including immunomodulation and restoration of homeostasis in diseased states. We will also review ongoing clinical trials using MSCs as treatment for BPD that pave the way for bringing cell-free, MEx-based therapeutics from the bench to the NICU setting.

Therapeutic Applications of Extracellular Vesicles: Perspectives from Newborn Medicine

With the advancements in antenatal steroid therapies and surfactant replacement, current clinical practices in neonatal intensive care units allow the survival of infants at very low gestational age. Despite these advances, there continues to be significant morbidity associated with extreme preterm birth that includes both short-term and long-term cardiorespiratory impairment. With no effective single therapy in preventing or treating developmental lung injuries, the need for new tools to treat and reduce risk of complications associated with extreme preterm birth is urgent. Stem cell-based therapies, in particular therapies utilizing mesenchymal stem (stromal) cells (MSCs), have shown promise in a number of animal models of lung pathologies relevant to neonatology. Recent studies in this field have consolidated the concept that the therapeutic mechanism of MSC action is paracrine, and this led to wide acceptance of the concept that the delivery of the MSC secretome rather than live cells may provide an alternative therapeutic approach for many complex diseases. Here, we summarize the significance and application of cell-free based therapies in preclinical models of neonatal lung injury. We emphasize the development of extracellular vesicle (EV)-based therapeutics and focus on the challenges that remain to be addressed before their application to clinical practice.

The Effect of Inhaled Budesonide on the Prevention of Chronic Lung Disease in Premature Neonates with Respiratory Distress Syndrome

BACKGROUND

Considering all the latest achievements in neonatal respiratory care, bronchopulmonary dysplasia (BPD) is still among the most prevalent morbidity causes in premature infants. Involvement in this process results in longer period of hospitalization for the newborn and in the long run makes the living conditions more difficult. Taking the multifactorial pathogenesis into account, approaches to tackle chronic lung disease (CLD) are mainly focused on interventions and prevention procedures. This study tries to investigate the potential capability of inhaled budesonide in the prevention of BPD in newborns with gestational age of <28 weeks with the respiratory distress syndrome (RDS).

METHODS

This study was a randomized clinical trial done on seventy newborns with gestational ages of 23-28 weeks with RDS in Isfahan Shahid Beheshti Educational Hospital from June 2014 to April 2016. Patients were randomly assigned to two groups of intervention with budesonide and control. There were 35 newborns in each group. Upon recording demographic characteristics, the newborns in two groups were compared based on the length of noninvasive ventilation, the need for invasive mechanical ventilation, the number of surfactant administrations, pneumothorax, intraventricular hemorrhage, patent ductus arteriosus (PDA), CLD, and death.

RESULTS

The length of the need for nasal continuous positive airway pressure showed no statistically significant difference between the groups (P = 0.54). The number of newborns who needed invasive mechanical ventilation also revealed no meaningful difference (P = 0.14). Similarly, the number of newborns who were characterized as affected by CLD also showed no significant difference between the groups (P = 0.053). Moreover, the number of newborns who experienced pneumothorax was not significantly different for the groups (P = 0.057). The number of newborns who received three administrations of surfactant had also no statistically meaningful difference between the groups (P = 0.69). However, the number of newborns who received two doses of surfactant was statistically lower in budesonide intervention group than the control (P = 0.041). The prevalence of intraventricular hemorrhage with degrees of I, II, and III also showed no statistically meaningful difference between the groups with P = 0.74, 0.32, and 0.49, respectively. The occurrence of PDA had no meaningful difference between the groups (P = 0.66). Relative death cases also revealed no significant difference between the groups (P = 0.53).

CONCLUSIONS

The current study revealed a decrease in CLD prevalence for newborns in interventional group; however, this decrease was not statistically meaningful. The newborns, in the intervention group, who had received two doses of surfactant (survanta) showed a significant decrease, which can be the basis for further research in this field.

Abnormal findings in brainstem auditory evoked response at 36-37weeks of postconceptional age in babies with neonatal chronic lung disease

AIM

To examine brainstem auditory function at 36-37weeks of postconceptional age in preterm infants who are diagnosed to have neonatal chronic lung disease (CLD).

STUDY DESIGN

Preterm infants, born at 31 and less weeks of gestation, were studied at 36-37weeks of postconceptional age when they were diagnosed to have neonatal CLD. Brainstem auditory evoked response (BAER) was recorded and analyzed at different click rates.

RESULTS

Compared with healthy controls at the same postconceptional age, the CLD infants showed a slightly increase in BAER wave V latency. However, the I-V, and III-V interpeak intervals in the CLD infants were significantly increased. The III-V/I-III interval ratio was also significantly increased. The amplitudes of BAER waves III and V in the CLD infants tended to be reduced. These BAER findings were similar at all 21, 51 and 91/s clicks, although the abnormalities tended to be more significant at higher than at low click rates.

CONCLUSION

At 36-37weeks of postconceptional age, BAER was abnormal in preterm infants who were diagnosed to have neonatal CLD. This suggests that at time when the diagnosis of CLD is made there is functional impairment, reflecting poor myelination, in the brainstem auditory pathway in preterm infants with neonatal CLD.

Vitamin A Supplementation for the Prevention of Bronchopulmonary Dysplasia in Preterm Infants: An Update

Bronchopulmonary dysplasia (BPD) is a common complication of premature birth and is associated with significant morbidity. Vitamin A supplementation has been suggested as a potential preventative measure against BPD due to its role in lung maturation and because preterm infants are particularly predisposed to vitamin A deficiency. The aim of this review was to determine whether vitamin A supplementation reduces BPD risk among preterm infants. PubMed, CINAHL, and Web of Science databases were searched with the keywords "bronchopulmonary dysplasia," "vitamin A," and "preterm infants" and with the time frame of 2006-2016, and 4 studies were selected for review per the inclusion criteria. Only 1 study found a significant reduction in BPD risk associated with vitamin A supplementation; however, 2 studies indicated a nonsignificant benefit and may have been underpowered to show statistical significance. One study revealed an increased risk of sepsis associated with vitamin A supplementation (for infants weighing >1000 g at birth), but no risk was seen with vitamin A supplementation in the other studies. Because intramuscular vitamin A has shown benefit with minimal risk, continued supplementation for preterm infants is warranted. Future studies aimed at assessing infant groups that are most likely to benefit from supplementation (based on birth weight or other conditions), as well as determining the optimal dosing while minimizing injections, would be beneficial.

Zinc supplementation reduces morbidity and mortality in very-low-birth-weight preterm neonates: a hospital-based randomized, placebo-controlled trial in an industrialized country

BACKGROUND

Zinc plays a pivotal role in the pathogenesis of many diseases and in body growth. Preterm neonates have high zinc requirements.

OBJECTIVE

The objective of the study was to investigate the efficacy of zinc supplementation in reducing morbidity and mortality in preterm neonates and to promote growth.

DESIGN

This was a prospective, double-blind, randomized controlled study of very-low-birth-weight preterm neonates randomly allocated on the seventh day of life to receive (zinc group) or not receive (control group) oral zinc supplementation. Total prescribed zinc intake ranged from 9.7 to 10.7 mg/d in the zinc group and from 1.3 to 1.4 mg/d in the placebo control group. The main endpoint was the rate of neonates with ≥ 1 of the following morbidities: late-onset sepsis, necrotizing enterocolitis, bronchopulmonary dysplasia, periventricular leucomalacia, and retinopathy of prematurity. Secondary outcomes were mortality and body growth.

RESULTS

We enrolled 97 neonates in the zinc group and 96 in the control group. Morbidities were significantly lower in the zinc group (26.8% compared with 41.7%; P = 0.030). The occurrence of necrotizing enterocolitis was significantly higher in the control group (6.3% compared with 0%; P = 0.014). Mortality risk was higher in the placebo control group (RR: 2.37; 95% CI: 1.08, 5.18; P = 0.006). Daily weight gain was similar in the zinc (18.2 ± 5.6 g · kg⁻¹ · d⁻¹) and control (17.0 ± 8.7 g · kg⁻¹ · d⁻¹) groups (P = 0.478).

CONCLUSION

Oral zinc supplementation given at high doses reduces morbidities and mortality in preterm neonates. This trial was registered in the Australian New Zealand Clinical Trial Register as ACTRN12612000823875.

The association between hypertensive disorders in pregnancy and bronchopulmonary dysplasia: a systematic review

BACKGROUND

Whether hypertensive disorders in pregnancy (HDP) are the risk factors of bronchopulmonary dysplasia (BPD) is controversial. A systematic review was made to determine the association between HDP and BPD in preterm infants.

METHODS

We searched PubMed, Embase, Cochrane Library, ScienceDirect, Web of Science, with no language limitation, and reviewed the reference lists of the selected articles to identify additional relevant publications and contacted the authors of relevant studies for further information. The data were extracted independently by 2 reviewers who used a predetermined data extraction form. Studies were combined with an odds ratio (OR) using a random-effects model. Meta-regression and subgroup analysis were used to explore potential confounders. Funnel plots, Egger's test and Begg's test were used to investigate the publication bias. The Trim and Fill method was used to control the publication bias.

RESULTS

A total of 787 studies were identified and only 15 studies (20 779 patients) were included. The pooled unadjusted OR showed that HDP was significantly associated with BPD (P=0.04; OR=1.29, 95% CI=1.01-1.65). Heterogeneity was substantial (I(2)=74%) and might be partially explained by different variables in maternal complications between the control groups across the studies. The pooled adjusted OR suggested the same conclusion that HDP was a risk factor for BPD (P=0.01; OR=1.59, 95% CI=1.11-2.26). Funnel plot and Egger's test showed that there were publication bias of unadjusted estimate of association between HDP and BPD.

CONCLUSIONS

Unadjusted analyses showed that the rate of BPD was slightly higher in the infants exposed to HDP, and adjusted analyses confirmed this finding. But this result should be interpreted cautiously because substantial heterogeneity and publication bias were identified in this review.

Gestational exposure of mice to secondhand cigarette smoke causes bronchopulmonary dysplasia blocked by the nicotinic receptor antagonist mecamylamine

BACKGROUND

Cigarette smoke (CS) exposure during gestation may increase the risk of bronchopulmonary dysplasia (BPD)-a developmental lung condition primarily seen in neonates that is characterized by hypoalveolarization, decreased angiogenesis, and diminished surfactant protein production and may increase the risk of chronic obstructive pulmonary disease.

OBJECTIVE

We investigated whether gestational exposure to secondhand CS (SS) induced BPD and sought to ascertain the role of nicotinic acetylcholine receptors (nAChRs) in this response.

METHODS

We exposed BALB/c and C57BL/6 mice to filtered air (control) or SS throughout the gestation period or postnatally up to 10 weeks. Lungs were examined at 7 days, 10 weeks, and 8 months after birth.

RESULTS

Gestational but not postnatal exposure to SS caused a typical BPD-like condition: suppressed angiogenesis [decreased vascular endothelial growth factor (VEGF), VEGF receptor, and CD34/CD31 (hematopoietic progenitor cell marker/endothelial cell marker)], irreversible hypoalveolarization, and significantly decreased levels of Clara cells, Clara cell secretory protein, and surfactant proteins B and C, without affecting airway ciliated cells. Importantly, concomitant exposure to SS and the nAChR antagonist mecamylamine during gestation blocked the development of BPD.

CONCLUSIONS

Gestational exposure to SS irreversibly disrupts lung development leading to a BPD-like condition with hypoalveolarization, decreased angiogenesis, and diminished lung secretory function. Nicotinic receptors are critical in the induction of gestational SS-induced BPD, and the use of nAChR antagonists during pregnancy may block CS-induced BPD.

Can nitric oxide-based therapy prevent bronchopulmonary dysplasia?

A growing understanding of endogenous nitric oxide (NO) biology is helping to explain how and when exogenous NO may confer benefit or harm; this knowledge is also helping to identify new better-targeted NO-based therapies. In this review, results of the bronchopulmonary dysplasia clinical trials that used inhaled NO in the preterm population are placed in context, the biologic basis for novel NO therapeutics is considered, and possible future directions for NO-focused clinical and basic research in developmental lung disease are identified.

G-protein-coupled receptor kinase interacting protein-1 is required for pulmonary vascular development

BACKGROUND

The G-protein-coupled receptor kinase interacting protein-1 (GIT1) is a multidomain scaffold protein that participates in many cellular functions including receptor internalization, focal adhesion remodeling, and signaling by both G-protein-coupled receptors and tyrosine kinase receptors. However, there have been no in vivo studies of GIT1 function to date.

METHODS AND RESULTS

To determine essential functions of GIT1 in vivo, we generated a traditional GIT1 knockout mouse. GIT1 knockout mice exhibited approximately 60% perinatal mortality. Pathological examination showed that the major abnormality in GIT1 knockout mice was impaired lung development characterized by markedly reduced numbers of pulmonary blood vessels and increased alveolar spaces. Given that vascular endothelial growth factor (VEGF) is essential for pulmonary vascular development, we investigated the role of GIT1 in VEGF signaling in the lung and cultured endothelial cells. Because activation of phospholipase-Cgamma (PLCgamma) and extracellular signal-regulated kinases 1/2 (ERK1/2) by angiotensin II requires GIT1, we hypothesized that GIT1 mediates VEGF-dependent pulmonary angiogenesis by modulating PLCgamma and ERK1/2 activity in endothelial cells. In cultured endothelial cells, knockdown of GIT1 decreased VEGF-mediated phosphorylation of PLCgamma and ERK1/2. PLCgamma and ERK1/2 activity in lungs from GIT1 knockout mice was reduced postnatally.

CONCLUSIONS

Our data support a critical role for GIT1 in pulmonary vascular development by regulating VEGF-induced PLCgamma and ERK1/2 activation.

Surface activity of surfactant spiked with vitamin A

Background

Intramuscular injections of vitamin A decrease the risk of broncho-pulmonary dysplasia. Admixture of vitamin A with surfactant as a lipophilic vehicle might be a less invasive modality.

Aim

Test physical properties of surfactant + vitamin A.

Methods

Miscibility and surface activity were tested in surfactant supplemented with retinyl-acetate, -palmitate, 13-cis-, or all-trans-retinoic acid.

Results

Retinol acetate (5000 IU/mL) demonstrated miscibility with surfactant when premixing with ethanol. Its surface activity was 40% lower compared to surfactant alone.

Conclusion

These findings warrant preclinical studies to test whether administration of vitamin A in subjects requiring surfactant is associated with beneficial functional properties.

Urinary vitamin A excretion in very low birth weight infants

Vitamin A (VA) deficiency in very low birth weight (VLBW) infants is associated with an increased risk for disorders related to kidney and lung maturation and function. VA losses through increased urinary retinol (ROH) excretion might contribute to this deficiency risk. The mechanism accounting for ROH loss in the urine has not yet been clarified. The aim of this study was to assess the excretion of ROH, retinol-binding protein 4 (RBP4) and transthyretin (TTR) in urine from VLBW infants in comparison with that in term infants in relation to kidney function. Urine specimens were collected from 15 VLBW infants (birth weight < 1,500 g) as well as from 20 term infants during the first 2 days after birth. ROH in urine was detectable in 14 of the 15 VLBW infants at a median concentration of 234 nmol/g creatinine. In the group of term infants, 17 of the 20 excreted ROH, but at an approximately five-times lower concentration (P < 0.001). Excretion of RBP4 and TTR was also much higher in VLBW infants (both P< 0.001). The urinary ROH excretion in VLBW infants may be related to the impaired tubular handling of its carrier proteins RBP4 and TTR. Thus, ROH excretion might contribute to an increased risk of VA deficiency, especially in VLBW infants.

Clarithromycin, montelukast, and pentoxifylline combination treatment ameliorates experimental neonatal hyperoxic lung injury

OBJECTIVE

We aimed to assess the efficiency of clarithromycin, montelukast, and pentoxifylline treatments, alone and in combination, in reducing hyperoxic lung injury at the histopathologic level.

METHODS

The experiment was carried out with 47 newborn rat pups divided into six groups during postnatal days 3 to 13. The rats belonging to group 1 were designated as the control group and kept in room air without exposure to hyperoxia. Group 2 (clarithromycin), group 3 (montelukast), group 4 (pentoxifylline), group 5 (clarithromycin + montelukast + pentoxifylline combination), and group 6 (placebo) were kept in plexiglass chamber and exposed to hyperoxia (88-92%) throughout the experiment. Alveolar surface area percentage, fibrosis, and smooth muscle actin expression were assessed in the lungs, which were resected by thoracotomy on postnatal day 14.

RESULTS

Drug treatments, when used separately, were not detected to be superior to placebo with regard to mean alveolar surface area, fibrosis, and smooth muscle actin expression. Combination treatment resulted in significantly higher mean lung area percentages and lower actin scores with respect to the placebo treatment group (64.0% vs. 50.2%, p=0.002; 0 (0-1) vs. 7 (2-12), p=0.005, respectively).

CONCLUSIONS

It was determined that clarithromycin, montelukast, and pentoxifylline combination treatment is superior to placebo treatment in the newborn rat hyperoxic lung injury model. The present study indicates that combination therapy might be successful in bronchopulmonary dysplasia, which has complex pathophysiologic processes and lacks established efficient treatment strategies.

Response to neonatal anesthesia: effect of sex on anatomical and behavioral outcome

Numerous studies have documented the consequences of exposure to anesthesia in models of term and post-term infants, evaluating the incidence of cell loss, physiological alterations and cognitive dysfunction. However, surprisingly few studies have investigated the effect of anesthetic exposure on outcomes in newborn rodents, the developmental equivalent of premature human infants. This is critical given that one out of every eight babies born in the United States is premature, with an increased prevalence of surgical procedures required in these individuals. Also, no studies have investigated if the genetic sex of the individual influences the response to neonatal anesthesia. Using the newborn rat as the developmental equivalent of the premature human, we documented the effect of a single bout of exposure to either the inhalant isoflurane or the injectable barbiturate phenobarbital on hippocampal anatomy, hippocampal dependent behavioral performance and normal developmental endpoints in male and female rats. While both forms of anesthesia led to significant decrements in cognitive abilities, along with a significant reduction in volume and neuron number in the hippocampus in adulthood, the decrements were significantly greater in males than in females. Interestingly, the deleterious effects of anesthesia were manifest on developmental measures including surface righting and forelimb grasp, but were not evident on basic physiological parameters including body weight or suckling. These findings point to the hazardous effects of exposure to anesthesia on the developing CNS and the particular sensitivity of males to deficits.

Retinoids increase lung elastin expression but fail to alter morphology or angiogenesis genes in premature ventilated baboons

Retinoids regulate elastin synthesis by alveolar myofibroblasts and affect angiogenesis pathways, both of which are processes critical for alveolar development. Retinoids accelerate alveolarization in rodents and are now used therapeutically in premature infants at risk of bronchopulmonary dysplasia (BPD). This study examined the effects of retinoid supplementation on alveolar elastin expression and deposition and angiogenesis-related signaling in a primate model of BPD. Premature baboons delivered at 125 d of gestation after maternal steroid treatment were given surfactant and ventilated with minimal supplemental oxygen for 14 d with (n = 5) and without (n = 5) supplemental vitamin A (5000 U/kg/d) and compared with 140-d unventilated controls. Ventilatory efficiency index (VEI) and oxygenation index (OI) were not statistically different between ventilated treatment groups. Expression of vascular endothelial growth factor A (VEGF-A), fms-related tyrosine kinase 1 (Flt-1), and tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE-1) was repressed by premature delivery and mechanical ventilation and was not altered by retinoid supplementation. Retinoid supplementation did not enhance alveolar angiogenesis. Elastin expression was repressed by premature delivery and extended ventilation, and retinoid supplementation increased elastin expression specifically in alveolar myofibroblasts within alveolar walls. These results suggest that the small decrease in mortality among premature infants receiving retinoid supplementation may not be mediated through enhanced alveolar development.

Does bronchopulmonary dysplasia change the postoperative outcome of herniorrhaphy in premature babies?

BACKGROUND

Inguinal hernia is a common surgical condition in premature neonates. Because of physiological immaturity, they can present with lung-related diseases, such as bronchopulmonary dysplasia (BPD), which may influence the time for operation and the postoperative outcome after hernia repair. The aim of this study was to analyze the role of BPD in the outcome of premature infants who underwent herniorrhaphy.

METHODS

Fifty-two premature infants who underwent hernia repair from 1996 to 2004 at CAISM-UNICAMP were included in this study. Seventeen babies had BPD and 35 did not. The features reviewed included: (i) associated preoperative morbidity; (ii) birth data and the hernia; and (iii) hernia diagnosis, surgery and postoperative outcome data. Three sets of analysis were undertaken. The first compared features with and without BPD. The second was an univariate analysis to detect associations between those features and postoperative complications. Finally, a multivariate analysis to determine the effect of BPD when adjusted for other factors.

RESULTS

Some features were different between the studied groups, such as birth weight, age at herniorrhaphy and time of preoperative mechanical ventilation. There was no statistical difference in weight at surgery, duration of postoperative ventilation and weight at discharge between those with BPD and those without. Univariate and multivariate analysis found no association between different studied variables, including BPD, and incidence of postoperative respiratory complications.

CONCLUSION

These data suggest that all premature infants, with or without BPD, should be treated with equal concern regarding the possibility of postoperative pulmonary complications.

Management of infants with chronic lung disease of prematurity in Chile

Despite advances in the prevention and management of respiratory distress syndrome, chronic lung disease of prematurity (CLD) remains a major cause of morbidity and mortality in preterm babies in Chile. Its incidence varies from 10% to 60% in different regions of Chile. Since 1998, the management of CLD after discharge from neonatal unit follows national guidelines. Target oxygen saturation is 85% to 91% in the first 1 week of life, 91% to 94% from 1 to 2 weeks and over 95% after 44 weeks postconceptional age. National home oxygen program has improved outcome in infants with CLD. Other specific treatments are used with caution. Diuretics are used for pulmonary oedema. The adverse neurological outcome in infants treated with postnatal steroids restricts its use to infants who cannot be weaned from mechanical ventilation. Inhaled steroids and bronchodilators may reduce asthma-like symptoms in established CLD. Prevention of RSV infection in CLD babies is paramount. The preterm infant population has been maintained under surveillance nationally since 1998.