Intrauterine growth restriction predicts lower lung function at school age in children born very preterm

Pulmonary vascular reactivity in growth restricted fetuses using computational modelling and machine learning analysis of fetal Doppler waveforms

The aim of this study was to investigate the pulmonary vasculature in baseline conditions and after maternal hyperoxygenation in growth restricted fetuses (FGR). A prospective cohort study of singleton pregnancies including 97 FGR and 111 normally grown fetuses was carried out. Ultrasound Doppler of the pulmonary vessels was obtained at 24-37 weeks of gestation and data were acquired before and after oxygen administration. After, Machine Learning (ML) and a computational model were used on the Doppler waveforms to classify individuals and estimate pulmonary vascular resistance (PVR). Our results showed lower mean velocity time integral (VTI) in the main pulmonary and intrapulmonary arteries in baseline conditions in FGR individuals. Delta changes of the main pulmonary artery VTI and intrapulmonary artery pulsatility index before and after hyperoxygenation were significantly greater in FGR when compared with controls. Also, ML identified two clusters: A (including 66% controls and 34% FGR) with similar Doppler traces over time and B (including 33% controls and 67% FGR) with changes after hyperoxygenation. The computational model estimated the ratio of PVR before and after maternal hyperoxygenation which was closer to 1 in cluster A (cluster A 0.98 ± 0.33 vs cluster B 0.78 ± 0.28, p = 0.0156). Doppler ultrasound allows the detection of significant changes in pulmonary vasculature in most FGR at baseline, and distinct responses to hyperoxygenation. Future studies are warranted to assess its potential applicability in the clinical management of FGR.

Reduced pulmonary oxygen diffusion at 36 weeks of postmenstrual age in small-for-gestational-age preterm infants of less than 32 weeks without bronchopulmonary dysplasia

BACKGROUND

Small-for-gestational-age (SGA) preterm infants are at increased risk of developing bronchopulmonary dysplasia (BPD). There is limited information on pulmonary oxygen diffusion of SGA preterm infants, particularly in those without BPD.

OBJECTIVE

To compare the pulmonary oxygen diffusion of SGA to that of appropriate-for-gestational-age (AGA) preterm infants without BPD.

STUDY DESIGN

Preterm infants with a gestational age (GA) between 24.0 and 31.6 weeks were studied. The oxygen saturation (SpO2 ), fraction to inspired oxygen (FiO2 ), and the SpO2 to FiO2 ratio (SFR) were compared between SGA and AGA infants. The association between SGA and SFR at 36 weeks was assessed using a multiple regression analysis. In the subgroup without BPD, SGA were match-paired for GA and gender with AGA infants.

RESULTS

We analyzed 1189 infants surviving at 36 weeks: 194 (16%) were SGA and 995 (84%) AGA. The incidence of BPD was significantly higher in SGA than AGA infants (32% vs. 13%; p = .000). Out of the 995 infants without BPD, 132 (13%) were SGA and 863 (87%) AGA. SGA was negatively associated with the SFR value at 36 weeks, independently from BPD. SGA infants without BPD had significantly higher (better) SFR at birth, but lower (worse) SpO2 and SFR and from 33 to 36 weeks than their matched AGA counterpart. At 36 weeks, median SpO2 and SFR values were 97.7 versus 98.4 (p = .006) and 465 versus 468 (p = .010) in match-paired SGA and AGA, respectively.

CONCLUSION

Among preterm infants of less than 32 weeks and without BPD, SGA infants had a reduced pulmonary oxygen diffusion at 36 weeks in comparison with AGA infants.

Lung function deficits and bronchodilator responsiveness at 12 years of age in children born very preterm compared with controls born at term

INTRODUCTION

Very preterm birth is associated with lung function impairment later in life, but several aspects have not been studied. We aimed to comprehensively assess lung function at school age in very preterm infants and term controls, with special emphasis on bronchopulmonary dysplasia (BPD), sex, and bronchodilator response.

METHODS

At 12 years of age, 136 children born very preterm (85 with and 51 without BPD) and 56 children born at term performed spirometry, body plethysmography, impulse oscillometry, measurement of diffusion capacity, and multiple breath washout, before and after bronchodilator inhalation.

RESULTS

Airway symptoms and a diagnosis of asthma were more common in children born very preterm. These children had more airflow limitation, seen as lower forced expiratory volume in 1 s (FEV1 ) (p < .001), FEV1 /forced vital capacity (FVC) (p = .011), and mean forced expiratory flow between 25% and 75% of FVC (p < .001), and a higher total and peripheral airway resistance compared with term-born controls. There was no difference in total lung capacity but air trapping and lung clearance index were higher in children born very preterm. Diffusion capacity was lower in children born very preterm, especially in those with a diagnosis of BPD. In most other tests, the differences between preterm-born children with or without BPD were smaller than between children born preterm versus at term. Boys born preterm had more lung function deficits than preterm-born girls. In children born very preterm, airway obstruction was to a large extent reversible.

CONCLUSION

At 12 years of age, children born very preterm had lower lung function than children born at term in most aspects and there was only little difference between children with or without BPD. Airway obstruction improved markedly after bronchodilator inhalation.

Morphometric, Developmental, and Anti-Inflammatory Effects of Transamniotic Stem Cell Therapy (TRASCET) on the Fetal Heart and Lungs in a Model of Intrauterine Growth Restriction

Transamniotic stem cell therapy (TRASCET) with mesenchymal stem cells (MSCs) can attenuate placental inflammation and minimize intrauterine growth restriction (IUGR). We sought to determine whether MSC-based TRASCET could mitigate fetal cardiopulmonary effects of IUGR. Pregnant Sprague-Dawley dams were exposed to alternating 12-h hypoxia (10.5% O2) cycles in the last fourth of gestation. Their fetuses (n = 155) were divided into 4 groups. One group remained untreated (n = 42), while three groups received volume-matched intra-amniotic injections of either saline (sham; n = 34), or of syngeneic amniotic fluid-derived MSCs, either in their native state (TRASCET; n = 36) or "primed" by exposure to interferon-gamma and interleukin-1beta before administration in vivo (TRASCET-primed; n = 43). Normal fetuses served as additional controls (n = 30). Multiple morphometric and biochemical analyses were performed at term for select markers of cardiopulmonary development and inflammation previously shown to be affected by IUGR. Among survivors (75%; 117/155), fetal heart-to-body weight ratio was increased in both the sham and untreated groups (P < 0.001 for both) but normalized in the TRASCET and TRASCET-primed groups (P = 0.275, 0.069, respectively). Cardiac b-type natriuretic peptide levels were increased in all hypoxia groups compared with normal (P < 0.001), but significantly decreased from sham and untreated in both TRASCET groups (P < 0.0001-0.005). Heart tumor necrosis factor-alpha levels were significantly elevated in sham and TRASCET groups (P = 0.009, 0.002), but normalized in the untreated and TRASCET-primed groups (P = 0.256, 0.456). Lung transforming growth factor-beta levels were significantly increased in both sham and untreated groups (P < 0.001, 0.003), but normalized in both TRASCET groups (P = 0.567, 0.303). Similarly, lung endothelin-1 levels were elevated in sham and untreated groups (P < 0.001 for both), but normalized in both TRASCET groups (P = 0.367, 0.928). We conclude that TRASCET with MSCs decreases markers of fetal cardiac strain, insufficiency, and inflammation, as well as of pulmonary fibrosis and hypertension in the rodent model of IUGR.

Perinatal origins of bronchopulmonary dysplasia-deciphering normal and impaired lung development cell by cell

Bronchopulmonary dysplasia (BPD) is a multifactorial disease occurring as a consequence of premature birth, as well as antenatal and postnatal injury to the developing lung. BPD morbidity and severity depend on a complex interplay between prenatal and postnatal inflammation, mechanical ventilation, and oxygen therapy as well as associated prematurity-related complications. These initial hits result in ill-explored aberrant immune and reparative response, activation of pro-fibrotic and anti-angiogenic factors, which further perpetuate the injury. Histologically, the disease presents primarily by impaired lung development and an arrest in lung microvascular maturation. Consequently, BPD leads to respiratory complications beyond the neonatal period and may result in premature aging of the lung. While the numerous prenatal and postnatal stimuli contributing to BPD pathogenesis are relatively well known, the specific cell populations driving the injury, as well as underlying mechanisms are still not well understood. Recently, an effort to gain a more detailed insight into the cellular composition of the developing lung and its progenitor populations has unfold. Here, we provide an overview of the current knowledge regarding perinatal origin of BPD and discuss underlying mechanisms, as well as novel approaches to study the perturbed lung development.

Neonatal respiratory support related to lung function abnormalities in school-age children with bronchopulmonary dysplasia

OBJECTIVE

To elucidate the relationship between abnormal lung function (LF) at school age and neonatal respiratory support in very low birth weight children with bronchopulmonary dysplasia (BPD).

STUDY DESIGN

We retrospectively examined 78 BPD children whose LF was evaluated at 8-9 years. LF abnormalities were defined by reduced values of spirometric parameters. Adjusted odds ratios (aORs) for abnormal LF by the type and postmenstrual age (PMA) of respiratory support were calculated using logistic regression analysis after controlling perinatal factors.

RESULTS

Overall, 24 (31%) patients had LF abnormalities. Antenatal steroid use was associated with a decreased risk of abnormal LF [aOR, 0.31; 95% CI, 0.09-0.92]. Requiring positive-pressure support at 37 weeks' PMA correlated with abnormal LF [aOR, 4.58; 95% CI, 1.15-21.90]; whereas only low-flow oxygen at any PMA did not.

CONCLUSION

Requiring positive-pressure support at 37 weeks' PMA could be an indicator of abnormal LF at school age.

Prematurity and BPD: what general pediatricians should know

More and more very low birth weight (VLBW) infants around the world survive nowadays, with consequently larger numbers of children developing prematurity-related morbidities, especially bronchopulmonary dysplasia (BPD). BPD is a multifactorial disease and its rising incidence in recent years means that general pediatricians are much more likely to encounter a child born extremely preterm, possibly with BPD, in their clinical practice. Short- and long-term sequelae in VLBW patients may affect not only pulmonary function (principally characterized by an obstructive pattern), but also other aspect including the neurological (neurodevelopmental and neuropsychiatric disorders), the sensorial (earing and visual impairment), the cardiological (systemic and pulmonary hypertension, reduced exercise tolerance and ischemic heart disease in adult age), nutritional (feeding difficulties and nutritional deficits), and auxological (extrauterine growth restriction). For the most premature infants at least, a multidisciplinary follow-up is warranted after discharge from the neonatal intensive care unit in order to optimize their respiratory and neurocognitive potential, and prevent respiratory infections, nutritional deficiencies or cardiovascular impairments.  Conclusion: The aim of this review is to summarize the main characteristics of preterm and BPD infants, providing the general pediatrician with practical information regarding these patients' multidisciplinary complex follow-up. We explore the current evidence on respiratory outcomes and their management that actually does not have a definitive available option. We also discuss the available investigations, treatments, and strategies for prevention and prophylaxis to improve the non-respiratory outcomes and the quality of life for these children and their families, a critical aspect not always considered. This comprehensive approach, added to the increased needs of a VLBW subjects, is obviously related to very high health-related costs that should be beared in mind. What is Known: • Every day, a general pediatrician is more likely to encounter a former very low birth weight infant. • Very low birth weight and prematurity are frequently related not only with worse respiratory outcomes, but also with neurological, sensorial, cardiovascular, renal, and nutritional issues. What is New: • This review provides to the general pediatrician a comprehensive approach for the follow-up of former premature very low birth weight children, with information to improve the quality of life of this special population.

Cross-Generational Impact of Innate Immune Memory Following Pregnancy Complications

Pregnancy complications can have long-term negative effects on the health of the affected mothers and their children. In this review, we highlight the underlying inflammatory etiologies of common pregnancy complications and discuss how aberrant inflammation may lead to the acquisition of innate immune memory. The latter can be described as a functional epigenetic reprogramming of innate immune cells following an initial exposure to an inflammatory stimulus, ultimately resulting in an altered response following re-exposure to a similar inflammatory stimulus. We propose that aberrant maternal inflammation associated with complications of pregnancy increases the cross-generational risk of developing noncommunicable diseases (i.e., pregnancy complications, cardiovascular disease, and metabolic disease) through a process mediated by innate immune memory. Elucidating a role for innate immune memory in the cross-generational health consequences of pregnancy complications may lead to the development of novel strategies aimed at reducing the long-term risk of disease.

Fetal growth restriction and neonatal-pediatric lung diseases: Vascular mechanistic links and therapeutic directions

Bronchopulmonary dysplasia (BPD) is the most common respiratory sequela of prematurity, and infants born with fetal growth restriction (FGR) are disproportionately represented in BPD statistics, as factors which affect somatic growth may also affect pulmonary growth. Effects of in-utero hypoxia underlying FGR on lung parenchymal architecture predisposing to BPD are well documented, but the pulmonary vascular constructs are not well appreciated. Disruption of angiogenesis during critical periods of lung growth impairs alveolarization, contributing to BPD pathogenesis. Pulmonary artery thickness/stiffness has been noted in FGR in the initial postnatal weeks, and also in well-grown infants with established BPD. The lack of waveform cushioning by the major arteries exposes the pulmonary resistance vessels to higher pulsatile stress, thereby accelerating microvascular disease. Reactive oxygen species, increased sympathetic activity and endothelial dysfunction are common mediators in FGR and BPD; each putative targets for prevention and/or therapeutics using interleukin (IL)-1 receptor antagonist (IL-1Ra), melatonin or inhibition of renin-angiotensin-aldosterone system. While BPD is the archetypal respiratory disease of infancy, effects of FGR on pulmonary function are long-term, extending well into childhood. This narrative links FGR in very/extremely preterm infants with BPD through the vascular affliction as a mechanistic and potentially, therapeutic pathway. Our objectives were to depict the burden of disease for FGR and BPD amongst preterm infants, portray vascular involvement in the placenta in FGR and BPD cohorts, provide high resolution vascular ultrasound information in both cohorts with a view to address therapeutic relevance, and lastly, link this information with paediatric age-group lung diseases.

Maternal and perinatal obesity induce bronchial obstruction and pulmonary hypertension via IL-6-FoxO1-axis in later life

Obesity is a pre-disposing condition for chronic obstructive pulmonary disease, asthma, and pulmonary arterial hypertension. Accumulating evidence suggests that metabolic influences during development can determine chronic lung diseases (CLD). We demonstrate that maternal obesity causes early metabolic disorder in the offspring. Here, interleukin-6 induced bronchial and microvascular smooth muscle cell (SMC) hyperproliferation and increased airway and pulmonary vascular resistance. The key anti-proliferative transcription factor FoxO1 was inactivated via nuclear exclusion. These findings were confirmed using primary SMC treated with interleukin-6 and pharmacological FoxO1 inhibition as well as genetic FoxO1 ablation and constitutive activation. In vivo, we reproduced the structural and functional alterations in offspring of obese dams via the SMC-specific ablation of FoxO1. The reconstitution of FoxO1 using IL-6-deficient mice and pharmacological treatment did not protect against metabolic disorder but prevented SMC hyperproliferation. In human observational studies, childhood obesity was associated with reduced forced expiratory volume in 1 s/forced vital capacity ratio Z-score (used as proxy for lung function) and asthma. We conclude that the interleukin-6-FoxO1 pathway in SMC is a molecular mechanism by which perinatal obesity programs the bronchial and vascular structure and function, thereby driving CLD development. Thus, FoxO1 reconstitution provides a potential therapeutic option for preventing this metabolic programming of CLD.

Tracking of lung function from 10 to 35 years after being born extremely preterm or with extremely low birth weight

Background

Lifelong pulmonary consequences of being born extremely preterm or with extremely low birth weight remain unknown. We aimed to describe lung function trajectories from 10 to 35 years of age for individuals born extremely preterm, and address potential cohort effects over a period that encompassed major changes in perinatal care.

Methods

We performed repeated spirometry in three population-based cohorts born at gestational age ≤28 weeks or with birth weight ≤1000 g during 1982–85, 1991–92 and 1999–2000, referred to as extremely preterm-born, and in term-born controls matched for age and gender. Examinations were performed at 10, 18, 25 and 35 years. Longitudinal data were analysed using mixed models regression, with the extremely preterm-born stratified by bronchopulmonary dysplasia (BPD).

Results

We recruited 148/174 (85%) eligible extremely preterm-born and 138 term-born. Compared with term-born, the extremely preterm-born had lower z-scores for forced expiratory volume in 1 s (FEV₁) at most assessments, the main exceptions were in the groups without BPD in the two youngest cohorts. FEV₁ trajectories were largely parallel for the extremely preterm- and term-born, also during the period 25–35 years that includes the onset of the age-related decline in lung function. Extremely preterm-born had lower peak lung function than term-born, but z-FEV₁ values improved for each consecutive decade of birth (p=0.009). More extremely preterm—than term-born fulfilled the spirometry criteria for chronic obstructive pulmonary disease, 44/148 (30%) vs 7/138 (5%), p<0.001.

Conclusions

Lung function after extremely preterm birth tracked in parallel, but significantly below the trajectories of term-born from 10 to 35 years, including the incipient age-related decline from 25 to 35 years. The deficits versus term-born decreased with each decade of birth from 1980 to 2000.

Antenatal mesenchymal stromal cell extracellular vesicle treatment preserves lung development in a model of bronchopulmonary dysplasia due to chorioamnionitis

Antenatal stressors such as chorioamnionitis (CA) increase the risk for bronchopulmonary dysplasia (BPD). Studies have shown that experimental BPD can be ameliorated by postnatal treatment with mesenchymal stromal cell-derived extracellular vesicles (MEx). However, the antenatal efficacy of MEx to prevent BPD is unknown. To determine whether antenatal MEx therapy attenuates intrauterine inflammation and preserves lung growth in a rat model of CA-induced BPD. At embryonic day (E)20, rat litters were treated with intra-amniotic injections of saline, endotoxin (ETX) to model chorioamnionitis, MEx, or ETX plus MEx followed by cesarean section delivery with placental harvest at E22. Placental and lung evaluations were conducted at day 0 and day 14, respectively. To assess the effects of ETX and MEx on lung growth in vitro, E15 lung explants were imaged for distal branching. Placental tissues from ETX-exposed pregnancies showed increased expression of inflammatory markers NLRP-3 and IL-1ß and altered spiral artery morphology. In addition, infant rats exposed to intrauterine ETX had reduced alveolarization and pulmonary vessel density (PVD), increased right ventricular hypertrophy (RVH), and decreased lung mechanics. Intrauterine MEx therapy of ETX-exposed pups reduced inflammatory cytokines, normalized spiral artery architecture, and preserved distal lung growth and mechanics. In vitro studies showed that MEx treatment enhanced distal lung branching and increased VEGF and SPC gene expression. Antenatal MEx treatment preserved distal lung growth and reduced intrauterine inflammation in a model of CA-induced BPD. We speculate that MEx may provide a novel therapeutic strategy to prevent BPD due to antenatal inflammation.

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

Patho-mechanisms of the origins of bronchopulmonary dysplasia

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

Lung function between 8 and 15 years of age in very preterm infants with fetal growth restriction

BACKGROUND

The impact of intrauterine growth restriction (IUGR) on lung function in very preterm children is largely unknown as current evidence is mainly based on studies in children born small for gestational age but not necessarily with IUGR.

METHODS

Spirometry, transfer factor of the lung for carbon monoxide (TLco), and lung clearance index (LCI) were cross-sectionally evaluated at 8.0-15.0 years of age in children born <32 weeks of gestation with IUGR (n = 28) and without IUGR (n = 67). Controls born at term (n = 67) were also included.

RESULTS

Very preterm children with IUGR had lower mean forced expired volume in the first second (FEV₁) z-score than those with normal fetal growth (∆ -0.66, 95% confidence interval (CI) -1.12, -0.19), but not significant differences in LCI (∆ +0.24, 95% CI -0.09, 0.56) and TLco z-score (∆ -0.11, 95% CI -0.44, 0.23). The frequency of bronchopulmonary dysplasia (BPD) in the two groups was, respectively, 43% and 10% (P = 0.003). IUGR was negatively associated with FEV₁ (B = -0.66; P = 0.004), but the association lost significance (P = 0.05) when adjusting for BPD.

CONCLUSIONS

IUGR has an impact on conducting airways function of very preterm children at school age, with part of this effect being mediated by BPD. Ventilation inhomogeneity and diffusing capacity, instead, were not affected.

IMPACT

IUGR does not necessarily imply a low birthweight for gestational age (and vice versa). While a low birthweight is associated with worse respiratory outcomes, the impact of IUGR on lung function in premature children is largely unknown. IUGR affects conducting airways function in school-age children born <32 weeks with IUGR, but not ventilation inhomogeneity and diffusing capacity. The impact of IUGR on FEV₁ seems mainly related to the higher risk of BPD in this group.

Intrauterine growth retardation and lung function of very prematurely born young people

OBJECTIVES

To assess if intrauterine growth retardation (IUGR) was associated with reduced lung function at 16-19 years.

WORKING HYPOTHESIS

Very prematurely born young people who had IUGR would have reduced lung function postpuberty.

STUDY DESIGN

Prospective follow-up study.

PATIENT-SUBJECT SELECTION

One hundred and fifty-nine 16-19 year olds born before 29 weeks of gestation; 37 had IUGR.

METHODOLOGY

Lung function tests were performed: spirometry was used to assess forced expiratory volume in one second (FEV1), forced expiratory flow at 75%, 50% and 25% of expired vital capacity (FEF75, FEF50 and FEF25), peak expiratory flow (PEF) and forced vital capacity (FVC). Functional residual capacity (FRCpleth) total lung capacity (TLCpleth) and residual volume (RVpleth) were measured. Alveolar function was assessed by diffusion capacity within the lungs of carbon monoxide (DLCO). Impulse oscillometry was used to assess respiratory resistance and lung clearance index to assess ventilation homogeneity. Exercise capacity was assessed using a shuttle sprint test.

RESULTS

After adjustment for BMI, the mean FEV-1/FVC, FEF75, FEF25-75, FRCpleth and RVpleth were poorer in those who had had IUGR, with differences between 0.56 and 0.75 z-scores. After further adjustment for BPD and postnatal corticosteroid use, only the difference in RVpleth z-scores remained statistically significant, adjusted difference (95% CI): 0.66 (0.18,1.13). Exercise capacity was lower in those with IUGR and this was more pronounced in males (p=0.04).

CONCLUSIONS

At 16-19 years of age, those who had IUGR had poorer lung function and exercise capacity compared with those with adequate intrauterine growth.

Perinatal Nutritional and Metabolic Pathways: Early Origins of Chronic Lung Diseases

Lung development is not completed at birth, but expands beyond infancy, rendering the lung highly susceptible to injury. Exposure to various influences during a critical window of organ growth can interfere with the finely-tuned process of development and induce pathological processes with aberrant alveolarization and long-term structural and functional sequelae. This concept of developmental origins of chronic disease has been coined as perinatal programming. Some adverse perinatal factors, including prematurity along with respiratory support, are well-recognized to induce bronchopulmonary dysplasia (BPD), a neonatal chronic lung disease that is characterized by arrest of alveolar and microvascular formation as well as lung matrix remodeling. While the pathogenesis of various experimental models focus on oxygen toxicity, mechanical ventilation and inflammation, the role of nutrition before and after birth remain poorly investigated. There is accumulating clinical and experimental evidence that intrauterine growth restriction (IUGR) as a consequence of limited nutritive supply due to placental insufficiency or maternal malnutrition is a major risk factor for BPD and impaired lung function later in life. In contrast, a surplus of nutrition with perinatal maternal obesity, accelerated postnatal weight gain and early childhood obesity is associated with wheezing and adverse clinical course of chronic lung diseases, such as asthma. While the link between perinatal nutrition and lung health has been described, the underlying mechanisms remain poorly understood. There are initial data showing that inflammatory and nutrient sensing processes are involved in programming of alveolarization, pulmonary angiogenesis, and composition of extracellular matrix. Here, we provide a comprehensive overview of the current knowledge regarding the impact of perinatal metabolism and nutrition on the lung and beyond the cardiopulmonary system as well as possible mechanisms determining the individual susceptibility to CLD early in life. We aim to emphasize the importance of unraveling the mechanisms of perinatal metabolic programming to develop novel preventive and therapeutic avenues.

Sex dependent effect of maternal e-nicotine on F1 Drosophila development and airways

E-cigarettes are heavily advertised as healthier alternative to common tobacco cigarettes, leading more and more women to switch from regular cigarettes to ENDS (electronic nicotine delivery system) during pregnancy. While the noxious consequences of tobacco smoking during pregnancy on the offspring health are well-described, information on the long-term consequences due to maternal use of e-cigarettes do not exist so far. Therefore, we aimed to investigate how maternal e-nicotine influences offspring development from earliest life until adulthood. To this end, virgin female Drosophila melanogaster flies were exposed to nicotine vapor (8 µg nicotine) once per hour for a total of eight times. Following the last exposure, e-nicotine or sham exposed females were mated with non-exposed males. The F1-generation was then analyzed for viability, growth and airway structure. We demonstrate that maternal exposure to e-nicotine not only leads to reduced maternal fertility, but also negatively affects size and weight, as well as tracheal development of the F1-generation, lasting from embryonic stage until adulthood. These results not only underline the need for studies investigating the effects of maternal vaping on offspring health, but also propose our established model for analyzing molecular mechanisms and signaling pathways mediating these intergenerational changes.

Survival without Bronchopulmonary Dysplasia of Extremely Preterm Infants: A Predictive Model at Birth

INTRODUCTION

Early prediction of survival without bronchopulmonary dysplasia (BPD) at 36 weeks of postmenstrual age remains challenging for infants born extremely preterm. We aimed to provide a new predictive model including variables available only at or soon after birth based on the literature and existing models.

METHODS

We conducted a systematic review to identify all variables considered to be significant predictors of BPD and survival at birth in extremely preterm infants. We then assessed the external validity of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Neonatal Research Network BPD estimator on the PREMILOC cohort, a recent French study with a large sample of extremely preterm infants and a vast number of variables at baseline. Finally, we attempted to improve this model by testing the added value of other early predictors reported in previous studies.

RESULTS

Restricted to baseline predictors, the NICHD Neonatal Research Network BPD estimator confirmed its calibration and fair discrimination (area under the receiver operating characteristic [auROC] [95% CI] = 0.73 [0.68-0.77] when used with a published model and auROC [95% CI] = 0.77 [0.73-0.81] when fitted to the PREMILOC dataset). We were able to improve the discriminatory power by adding candidate variables at birth associated with BPD in previous studies. The modified best predicting model included gestational age at birth, birthweight, respiratory support at baseline, gender, center effect, and multiple pregnancy as baseline predictors. This model showed significantly better discrimination (auROC [95% CI] = 0.85 [0.82-0.88]) and better confirmed calibration (Hosmer-Lemeshow test, p = 0.45).

CONCLUSION

This new model, based on 6 early predictors, appears to improve the prediction soon after birth of BPD-free survival in extremely preterm infants.

Asthma prevalence, lung and cardiovascular function in adolescents born preterm

Our main objective was to study respiratory evolution and pulmonary and cardiac function in adolescents born preterm in the post-surfactant era. Observational cross-sectional study, comparing very preterm (< 32 weeks) and moderately-late preterm adolescents (≥ 32 weeks) (74 each group). We recorded respiratory symptoms, spirometry and functional echocardiogram. Very preterm adolescents required more respiratory admissions (45.9% vs. 28.4%) (p = 0.03, OR 2.1, CI95% 1.1–4.2) and had more current asthma (21.6% vs. 9.5%, p = 0.04, OR 2.3, CI95% 1.1–5.2). Preterm subjects with intrauterine growth restriction (IUGR) presented lower FEV₁ (88.7 ± 13.9 vs. 95.9 ± 13.3, p = 0.027) and lower FVC (88.2 ± 13.6 vs. 95.5 ± 13.3, p = 0.025). When assessing right ventricle, very preterm showed a greater E/E’ ratio (p = 0.02) and longer myocardial performance index (MPI) (p = 0.001). Adolescents with IUGR showed less shortening fraction (p = 0.016), worse E/E′ ratio (p = 0.029) and longer MPI (p = 0.06). Regarding left ventricle, very preterm showed less E′ wave velocity (p = 0.03), greater E/E′ ratio (p = 0.005) and longer MPI (p < 0.001). Gestational age < 32 weeks is independently associated with current asthma in adolescence. Children 13–14 years old born very preterm required more respiratory admissions and had poorer diastolic and global function of both ventricles. IUGR is a risk factor for poorer lung function in preterm adolescents, regardless gestational age.

Perinatal Hypoxia-Inducible Factor Stabilization Preserves Lung Alveolar and Vascular Growth in Experimental Bronchopulmonary Dysplasia

Rationale: Antenatal inflammation with placental dysfunction is strongly associated with high bronchopulmonary dysplasia (BPD) risk in preterm infants. Whether antenatal or postnatal HIF (hypoxia-inducible factor) augmentation can preserve lung structure and function and prevent pulmonary hypertension after intrauterine inflammation is controversial.Objectives: To determine whether antenatal or postnatal prolyl-hydroxylase inhibitor (PHi) therapy increases lung HIF expression, preserves lung growth and function, and prevents pulmonary hypertension in a rat model of chorioamnionitis-induced BPD caused by antenatal inflammation.Methods: Endotoxin (ETX) was administered to pregnant rats by intraamniotic injection at Embryonic Day 20, and pups were delivered by cesarean section at Embryonic Day 22. Selective PHi drugs, dimethyloxalylglycine or GSK360A, were administered into the amniotic space at Embryonic Day 20 or after birth by intraperitoneal injection for 2 weeks. Placentas and lung tissue were collected at birth for morphometric and Western blot measurements of HIF-1a, HIF-2a, VEGF (vascular endothelial growth factor), and eNOS (endothelial nitric oxide synthase) protein contents. At Day 14, lung function was assessed, and tissues were harvested to determine alveolarization by radial alveolar counts, pulmonary vessel density, and right ventricle hypertrophy (RVH).Measurements and Main Results: Antenatal PHi therapy preserves lung alveolar and vascular growth and lung function and prevents RVH after intrauterine ETX exposure. Antenatal administration of PHi markedly upregulates lung HIF-1a, HIF-2a, VEGF, and eNOS expression after ETX exposure.Conclusions: HIF augmentation improves lung structure and function, prevents RVH, and improves placental structure following antenatal ETX exposure. We speculate that antenatal or postnatal PHi therapy may provide novel strategies to prevent BPD due to antenatal inflammation.

rhIGF-1/BP3 Preserves Lung Growth and Prevents Pulmonary Hypertension in Experimental Bronchopulmonary Dysplasia

Rationale: Antenatal factors, such as chorioamnionitis, preeclampsia, and postnatal injury, are associated with an increased risk for bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH) after preterm birth. IGF-1 (insulin-like growth factor-1) is markedly decreased in normal preterm infants, but whether IGF-1 treatment can prevent BPD or PH is unknown.Objectives: To evaluate whether postnatal treatment with rhIGF-1 (recombinant human IGF-1)/BP3 (binding peptide 3) improves lung growth and prevents PH in two antenatal models of BPD induced by intraamniotic exposure to endotoxin (ETX) or sFlt-1 (soluble fms-like tyrosine kinase 1), and in a postnatal model due to prolonged hyperoxia.Methods: ETX or sFlt-1 were administered into the amniotic sac of pregnant rats at Embryonic Day 20 to simulate antenatal models of chorioamnionitis and preeclampsia, respectively. Pups were delivered by cesarean section at Embryonic Day 22 and treated with rhIGF-1/BP3 (0.02-20 mg/kg/d intraperitoneal) or buffer for 2 weeks. Study endpoints included radial alveolar counts (RACs), vessel density, and right ventricular hypertrophy (RVH). Direct effects of rhIGF-1/BP3 (250 ng/ml) on fetal lung endothelial cell proliferation and tube formation and alveolar type 2 cell proliferation were studied by standard methods in vitro.Measurements and Main Results: Antenatal ETX and antenatal sFlt-1 reduced RAC and decreased RVH in infant rats. In both models, postnatal rhIGF-1/BP3 treatment restored RAC and RVH to normal values when compared with placebo injections. rhIGF-1/BP3 treatment also preserved lung structure and prevented RVH after postnatal hyperoxia. In vitro studies showed that rhIGF-1/BP3 treatment increased lung endothelial cell and alveolar type 2 cell proliferation.Conclusions: Postnatal rhIGF-1/BP3 treatment preserved lung structure and prevented RVH in antenatal and postnatal BPD models. rhIGF-1/BP3 treatment may provide a novel strategy for the prevention of BPD in preterm infants.

[Establishment of an ovalbumin-induced bronchial asthma model in mice with intrauterine growth retardation]

OBJECTIVE

To establish and evaluate an ovalbumin (OVA)-induced bronchial asthma model in mice with intrauterine growth retardation (IUGR), and to explore the molecular mechanism of relationship between IUGR and asthma.

METHODS

A total of 16 pregnant BALB/c female mice were divided into a low-protein diet group (n=8) and a normal-protein diet group (n=8), which were fed with low-protein (8%) diet and normal-protein (20%) diet respectively. The neonatal mice were weighed 6 hours after birth. Sixteen male neonatal mice with IUGR were randomly chosen from the low-protein diet group and enrolled in the IUGR group, and 16 male neonatal mice from the normal-protein diet group were enrolled in the control group. Blood samples were collected from the mice in both groups for testing of blood glucose. Enzyme-linked immunosorbent assay (ELISA) was used to determine serum insulin level. The mice in the control group were randomized into a control + PBS group and a control + OVA group (n=8 each). The mice in the IUGR group were randomized into an IUGR + PBS group and an IUGR + OVA group (n=8 each). Six-week-old mice in the control + OVA and IUGR + OVA groups were subjected to intraperitoneal injection of 2 mg/mL OVA for sensitization and aerosol inhalation of 1% OVA for challenge. Mice in the control + PBS group and the IUGR + PBS group were treated with an equivalent amount of PBS. ELISA was used to determine serum IgE level in the mice in each group. Bronchoalveolar lavage fluid (BLF) was collected from the mice in each group for cell counting. The lung tissue of the mice in each group was stained with hematoxylin and eosin to observe pathological changes.

RESULTS

The body weight at 6 hours after birth was significantly lower for neonatal mice in the low-protein diet group compared with those in the normal-protein diet group (P<0.01). The IUGR group had a significantly lower serum insulin level than the control group (P<0.01). The IUGR + PBS group had a significantly lower IgE level than the control + PBS group (P<0.01). Compared with the control + PBS and IUGR + PBS groups, the control + OVA and IUGR + OVA groups had a significantly increased IgE level, and the IgE level was significantly higher in the IUGR + OVA group than in the control + OVA group (P<0.01). Compared with the control + PBS and IUGR + PBS groups, the control + OVA and IUGR + OVA groups had significantly increased counts of leukocytes, eosinophils, lymphocytes, and macrophages in the BLF (P<0.01). The pulmonary alveoli of OVA-induced IUGR mice showed massive inflammatory cell infiltration and damage of intercellular continuity. Meanwhile, airway epithelial cell proliferation, bronchial wall thickening, bronchial lumen narrowing, and massive inflammatory cell infiltration around the bronchi and the vascular wall were observed.

CONCLUSIONS

An OVA-induced bronchial asthma model has been successfully established in the mice with IUGR induced by low-protein diet, which provides a basis for further study of the molecular mechanism of relationship between IUGR and airway inflammation.

Anti-sFlt-1 Therapy Preserves Lung Alveolar and Vascular Growth in Antenatal Models of Bronchopulmonary Dysplasia

RATIONALE

Pregnancies complicated by antenatal stress, including preeclampsia (PE) and chorioamnionitis (CA), increase the risk for bronchopulmonary dysplasia (BPD) in preterm infants, but biologic mechanisms linking prenatal factors with BPD are uncertain. Levels of sFlt-1 (soluble fms-like tyrosine kinase 1), an endogenous antagonist to VEGF (vascular endothelial growth factor), are increased in amniotic fluid and maternal blood in PE and associated with CA.

OBJECTIVES

Because impaired VEGF signaling has been implicated in the pathogenesis of BPD, we hypothesized that fetal exposure to sFlt-1 decreases lung growth and causes abnormal lung structure and pulmonary hypertension during infancy.

METHODS

To test this hypothesis, we studied the effects of anti-sFlt-1 monoclonal antibody (mAb) treatment on lung growth in two established antenatal models of BPD that mimic PE and CA induced by intraamniotic (i.a.) injections of sFlt-1 or endotoxin, respectively. In experimental PE, mAb was administered by three different approaches, including antenatal treatment by either i.a. instillation or maternal uterine artery infusion, or by postnatal intraperitoneal injections.

RESULTS

With each strategy, mAb therapy improved infant lung structure as assessed by radial alveolar count, vessel density, right ventricular hypertrophy, and lung function. As found in the PE model, the adverse lung effects of i.a. endotoxin were also reduced by antenatal or postnatal mAb therapy.

CONCLUSIONS

We conclude that treatment with anti-sFlt-1 mAb preserves lung structure and function and prevents right ventricular hypertrophy in two rat models of BPD of antenatal stress and speculate that early mAb therapy may provide a novel strategy for the prevention of BPD.

Placental transcriptional and histologic subtypes of normotensive fetal growth restriction are comparable to preeclampsia

BACKGROUND

Infants born small for gestational age because of pathologic placenta-mediated fetal growth restriction can be difficult to distinguish from those who are constitutionally small. Additionally, even among fetal growth-restricted pregnancies with evident placental disease, considerable heterogeneity in clinical outcomes and long-term consequences has been observed. Gene expression studies of fetal growth-restricted placentas also have limited consistency in their findings, which is likely due to the presence of different molecular subtypes of disease. In our previous study on preeclampsia, another heterogeneous placenta-centric disorder of pregnancy, we found that, by clustering placentas based only on their gene expression profiles, multiple subtypes of preeclampsia, including several with co-occurring suspected fetal growth restriction, could be identified.

OBJECTIVE

The purpose of this study was to discover placental subtypes of normotensive small-for-gestational-age pregnancies with suspected fetal growth restriction through the use of unsupervised clustering of placental gene expression data and to investigate their relationships with hypertensive suspected fetal growth-restricted placental subtypes.

STUDY DESIGN

A new dataset of 20 placentas from normotensive small-for-gestational-age pregnancies (birthweight <10th percentile for gestational age and sex) with suspected fetal growth restriction (ultrasound features of placental insufficiency) underwent genome-wide messenger RNA expression assessment and blinded detailed histopathologic evaluation. These samples were then combined with a subset of samples from our previously published preeclampsia cohort (n=77) to form an aggregate fetal growth-focused cohort (n=97) of placentas from normotensive small-for-gestational-age, hypertensive (preeclampsia and chronic hypertensive) small-for-gestational-age, and normotensive average-for-gestational-age pregnancies. Gene expression data were subjected to unsupervised clustering, and clinical and histopathologic features were correlated to the identified sample clusters.

RESULTS

Clustering of the aggregate dataset revealed 3 transcriptional subtypes of placentas from normotensive small-for-gestational-age/suspected fetal growth-restricted pregnancies, with differential enrichment of clinical and histopathologic findings. The first subtype exhibited either no placental disease or mild maternal vascular malperfusion lesions, and, co-clustered with the healthy average-for-gestational-age control subjects; the second subtype showed more severe evidence of hypoxic damage and lesions of maternal vascular malperfusion, and the third subtype demonstrated an immune/inflammatory response and histologic features of a maternal-fetal interface disturbance. Furthermore, all 3 of these normotensive small-for-gestational-age subtypes co-clustered with a group of placentas from hypertensive small-for-gestational-age pregnancies with more severe clinical outcomes, but very comparable transcriptional and histologic placental profiles.

CONCLUSION

Overall, this study provides evidence for at least 2 pathologic placental causes of normotensive small-for-gestational-age, likely representing true fetal growth restriction. These subtypes also show considerable similarity in gene expression and histopathology to our previously identified "canonical" and "immunologic" preeclampsia placental subtypes. Furthermore, we discovered a subtype of normotensive small-for-gestational-age (with suspected fetal growth restriction) with minimal placental disease that may represent both constitutionally small infants and mild fetal growth restriction, although these cannot be distinguished with the currently available data. Future work that focuses on the identification of etiology-driven biomarkers and therapeutic interventions for each subtype of fetal growth restriction is warranted.

Neonatal Morbidities of Fetal Growth Restriction: Pathophysiology and Impact

Being born small lays the foundation for short-term and long-term implications for life. Intrauterine or fetal growth restriction describes the pregnancy complication of pathological reduced fetal growth, leading to significant perinatal mortality and morbidity, and subsequent long-term deficits. Placental insufficiency is the principal cause of FGR, which in turn underlies a chronic undersupply of oxygen and nutrients to the fetus. The neonatal morbidities associated with FGR depend on the timing of onset of placental dysfunction and growth restriction, its severity, and the gestation at birth of the infant. In this review, we explore the pathophysiological mechanisms involved in the development of major neonatal morbidities in FGR, and their impact on the health of the infant. Fetal cardiovascular adaptation and altered organ development during gestation are principal contributors to postnatal consequences of FGR. Clinical presentation, diagnostic tools and management strategies of neonatal morbidities are presented. We also present information on the current status of targeted therapies. A better understanding of neonatal morbidities associated with FGR will enable early neonatal detection, monitoring and management of potential adverse outcomes in the newborn period and beyond.

Recent advances in antenatal factors predisposing to bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) remains a major cause of late morbidities and death after preterm birth. BPD is characterized by an arrest of vascular and alveolar growth and high risk for pulmonary hypertension; yet mechanisms contributing to its pathogenesis and early strategies to prevent BPD are poorly understood. Strong epidemiologic studies have shown that the "new BPD" reflects the long-lasting impact of antenatal factors on lung development, partly due to placental dysfunction, as reflected in recent data from animal models. Improved understanding of mechanisms through which antenatal stress alters placental function and contributes to BPD may lead to preventive therapies.

Renal function and blood pressure in 11 year old children born extremely preterm or small for gestational age

Background

Preterm birth and low birth weight are associated with reduced nephron numbers and increased risk of hypertension and kidney disease in later life.

Aims

We tested the hypothesis that extremely preterm birth and intrauterine growth restriction is associated with decreased renal function in mid childhood.

Methods

At 11 years of age the following measures were obtained in a regional cohort of children born extremely premature (EP, i.e. < 28 weeks gestational age—GA) or with extremely low birth weight (ELBW, i.e. BW < 1000 grams) and in matched controls born at term with appropriate BW (AGA): Height, weight, abdominal circumference, triceps and subscapular skin fold thicknesses, blood pressure, plasma levels of creatinine, cystatin C and symmetric dimethyl arginine (SDMA). Small for gestational age (SGA) was defined as a BW < 10^th percentile for GA. Glomerular filtration rate (GFR) was estimated according to the equations by Schwartz, Zappitelli and Gao.

Results

Fifty-seven of 61 eligible EP/ELBW children, 20 (35%) born SGA, and 54 controls, were assessed. Estimated GFR decreased while plasma SDMA increased from the children born AGA at term through those born preterm AGA to preterm SGA. Systolic BP was correlated to fat mass indices (p<0.03), but not to renal function (p>0.2) and did not differ between the groups.

Conclusions

Children born EP/ELBW, particularly those born SGA, had impaired renal function at age 11 years as judged from estimated GFRs and plasma levels of SDMA. Since reduced renal function is associated with an increased risk of later disease, these children should be followed in order to minimize additional risk factors.

Novel functional role of GH/IGF-I in neonatal lung myofibroblasts and in rat lung growth after intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a risk factor for neonatal chronic lung disease (CLD) characterized by reduced alveoli and perturbed matrix remodeling. Previously, our group showed an activation of myofibroblasts and matrix remodeling in rat lungs after IUGR. Because growth hormone (GH) and insulin-like growth factor I (IGF-I) regulate development and growth, we queried 1) whether GH/IGF-I signaling is dysregulated in lungs after IUGR and 2) whether GH/IGF-I signaling is linked to neonatal lung myofibroblast function. IUGR was induced in Wistar rats by isocaloric low-protein diet during gestation. Lungs were obtained at embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Murine embryonic fibroblasts (MEF) or primary neonatal myofibroblasts from rat lungs of control (pnF^Co) and IUGR (pnF^IUGR) were used for cell culture studies. In the intrauterine phase (E21), we found a reduction in GH receptor (GH-R), Stat5 signaling and IGF-I expression in lungs after IUGR. In the postnatal phase (P3-P23), catchup growth after IUGR was linked to increased GH mRNA, GH-R protein, activation of proliferative Stat5/Akt signaling, cyclin D1 and PCNA in rat lungs. On P23, a thickening of the alveolar septae was related to increased vimentin and matrix deposition, indicating fibrosis. In cell culture studies, nutrient deprivation blocked GH-R/IGF-IR signaling and proliferation in MEFs; this was reversed by IGF-I. Proliferation and Stat5 activation were increased in pnF^IUGR. IGF-I and GH induced proliferation and migration of pnF^Co; only IGF-I had these effects on pnF^IUGR. Thus, we show a novel mechanism by which the GH/IGF-I axis in lung myofibroblasts could account for structural lung changes after IUGR.

Nutrition and Lung Growth

Experimental evidence from animal models and epidemiology studies has demonstrated that nutrition affects lung development and may have a lifelong impact on respiratory health. Chronic restriction of nutrients and/or oxygen during pregnancy causes structural changes in the airways and parenchyma that may result in abnormal lung function, which is tracked throughout life. Inadequate nutritional management in very premature infants hampers lung growth and may be a contributing factor in the pathogenesis of bronchopulmonary dysplasia. Recent evidence seems to indicate that infant and childhood malnutrition does not determine lung function impairment even in the presence of reduced lung size due to delayed body growth. This review will focus on the effects of malnutrition occurring at critical time periods such as pregnancy, early life, and childhood, on lung growth and long-term lung function.

How best to capture the respiratory consequences of prematurity?

Chronic respiratory morbidity is a common complication of premature birth, generally defined by the presence of bronchopulmonary dysplasia, both clinically and in trials of respiratory therapies. However, recent data have highlighted that bronchopulmonary dysplasia does not correlate with chronic respiratory morbidity in older children born preterm. Longitudinally evaluating pulmonary morbidity from early life through to childhood provides a more rational method of defining the continuum of chronic respiratory morbidity of prematurity, and offers new insights into the efficacy of neonatal respiratory interventions. The changing nature of preterm lung disease suggests that a multimodal approach using dynamic lung function assessment will be needed to assess the efficacy of a neonatal respiratory therapy and predict the long-term respiratory consequences of premature birth. Our aim is to review the literature regarding the long-term respiratory outcomes of neonatal respiratory strategies, the difficulties of assessing dynamic lung function in infants, and potential new solutions.

Better measures are needed to predict chronic respiratory morbidity in survivors born prematurely http://ow.ly/1L3n30ihq9C

Bronchial hyper-responsiveness after preterm birth

Being born preterm often adversely affects later lung function. Airway obstruction and bronchial hyperresponsiveness (BHR) are common findings. Respiratory symptoms in asthma and in lung disease after preterm birth might appear similar, but clinical experience and studies indicate that symptoms secondary to preterm birth reflect a separate disease entity. BHR is a defining feature of asthma, but can also be found in other lung disorders and in subjects without respiratory symptoms. We review different methods to assess BHR, and findings reported from studies that have investigated BHR after preterm birth. The area appeared understudied with relatively few and heterogeneous articles identified, and lack of a pervasive understanding. BHR seemed related to low gestational age at delivery and a neonatal history of bronchopulmonary dysplasia. No studies reported associations between BHR after preterm birth and the markers of eosinophilic inflammatory airway responses typically found in asthma. This should be borne in mind when treating preterm born individuals with BHR and airway symptoms.

Pulmonary function in former very low birth weight preterm infants in the first year of life

BACKGROUND

Pulmonary function in former preterm infants may be compromised during childhood.

OBJECTIVES

To assess pulmonary function in very-low-birth-weight preterm infants at 6-12 months of corrected age and analyze the factors associated with abnormal pulmonary function.

METHODS

Cross-sectional study with preterm infants at 6-12 months of corrected age with birth weight <1500 g. Children with malformations or affected by neuromuscular and respiratory diseases were excluded. Forced expiratory flows were assessed using the chest compression technique, and volumes were measured by total body plethysmography. Pulmonary function parameters in preterm infants were compared to a control group of same-aged children born at term.

RESULTS

We studied 51 preterm and 37 infants born at term. Preterm infants had: gestational age at birth (30.0 ± 2.5 weeks), birth weight (1179 ± 247 g), 27.5% had bronchopulmonary dysplasia, and 45% received mechanical ventilation. Preterm infants had lower median z-scores in comparison to term infants for the following parameters (p < 0.05): FVC (-0.3 vs. 0.7), FEV_0.5 (-0.5 vs. 0.9), FEV_0.5/FVC (-0.6 vs. -0.5), FEF₅₀ (-0.4 vs. 0.9), FEF₇₅ (-0.3 vs. 0.8), FEF₈₅ (-0.1 vs. 0.6) and FEF_25-75 (-0.5 vs. 1.1). No term child had abnormal lung function, compared to 39.2% of preterm infants (p = 0.001). Factors associated with abnormal pulmonary function were lower gestational age at birth, small for gestational age, need for mechanical ventilation and presence of recurrent wheezing.

CONCLUSIONS

Preterms had a high prevalence of abnormal pulmonary function and lower pulmonary function in comparison to term infants. Prematurity, intrauterine growth restriction, respiratory support and recurrent wheezing were associated with abnormal pulmonary function.

Neonatal and Long-Term Consequences of Fetal Growth Restriction

BACKGROUND

Fetal Growth Restriction (FGR) is one of the most common noxious antenatal conditions in humans, inducing a substantial proportion of preterm delivery and leading to a significant increase in perinatal mortality, neurological handicaps and chronic diseases in adulthood. This review summarizes the current knowledge about the postnatal consequences of FGR, with a particular emphasis on the long-term consequences on respiratory, cardiovascular and neurological structures and functions.

RESULT AND CONCLUSION

FGR represents a global health challenge, and efforts are urgently needed to improve our understanding of the critical factors leading to FGR and subsequent insults to the developing organs.

Structural Pulmonary Abnormalities Still Evident in Schoolchildren with New Bronchopulmonary Dysplasia

BACKGROUND

A new pattern of bronchopulmonary dysplasia (BPD) has emerged with the improved survival of preterm children.

OBJECTIVES

Our aim was to characterize structural abnormalities associated with new BPD and to evaluate whether the severity of high-resolution computed tomography (HRCT) changes is associated with lung function.

METHODS

HRCT scans were performed on 21 schoolchildren with a history of new BPD (mild, n = 9; moderate, n = 4; and severe, n = 8) with a mean age of 12.7 years (range: 8.7-16.7). Scans were interpreted by 2 radiologists using a structured scoring system. Spirometry (forced expiratory volume in 1 s [FEV1] and maximum mid-expiratory flow [MMEF]) and the diffusion capacity of the lung for carbon monoxide (DLCO) were measured.

RESULTS

At least 1 HRCT abnormality was evident in 17 children (81%), including linear-to-triangular subpleural opacities (71%), air trapping (29%), mosaic perfusion (24%), peribronchial thickening (14%), and emphysema (14%). The HRCT score was higher in the severe BPD group (11.50; 95% CI 2.86-20.14) than in the mild or moderate BPD group (1.39; 95% CI 0.24-2.54, and 2.75; 95% CI 0.28-5.22, respectively). HRCT scores were inversely related to FEV1 (β -4.23; 95% CI -6.97 to -1.49, p = 0.004) and MMEF (β -3.45; 95% CI -6.10 to -0.80, p = 0.013) but not to DLCO. The duration of the initial mechanical ventilation was associated with HRCT scores (p = 0.014).

CONCLUSIONS

Structural lung abnormalities are common among schoolchildren with a history of new BPD, resembling abnormalities described in the presurfactant era. HRCT abnormalities are associated with the duration of early mechanical ventilation and the severity of BPD and they are correlated with spirometry.

Lung microRNA deregulation associated with impaired alveolarization in rats after intrauterine growth restriction

Intrauterine growth restriction (IUGR) was recently described as an independent risk factor of bronchopulmonary dysplasia, the main respiratory sequelae of preterm birth. We previously showed impaired alveolarization in rat pups born with IUGR induced by a low-protein diet (LPD) during gestation. We conducted a genome-wide analysis of gene expression and found the involvement of several pathways such as cell adhesion. Here, we describe our unbiased microRNA (miRNA) profiling by microarray assay and validation by qPCR at postnatal days 10 and 21 (P10 and P21) in lungs of rat pups with LPD-induced lung-alveolarization disorder after IUGR. We identified 13 miRNAs with more than two-fold differential expression between control lungs and LPD-induced IUGR lungs. Validated and predicted target genes of these miRNAs were related to “tissue repair” at P10 and “cellular communication regulation” at P21. We predicted the deregulation of several genes associated with these pathways. Especially, E2F3, a transcription factor involved in cell cycle control, was expressed in developing alveoli, and its mRNA and protein levels were significantly increased at P21 after IUGR. Hence, IUGR affects the expression of selected miRNAs during lung alveolarization. These results provide a basis for deciphering the mechanistic contributions of IUGR to impaired alveolarization.

Antenatal Determinants of Bronchopulmonary Dysplasia and Late Respiratory Disease in Preterm Infants

RATIONALE

Mechanisms contributing to chronic lung disease after preterm birth are incompletely understood.

OBJECTIVES

To identify antenatal risk factors associated with increased risk for bronchopulmonary dysplasia (BPD) and respiratory disease during early childhood after preterm birth, we performed a prospective, longitudinal study of 587 preterm infants with gestational age less than 34 weeks and birth weights between 500 and 1,250 g.

METHODS

Data collected included perinatal information and assessments during the neonatal intensive care unit admission and longitudinal follow-up by questionnaire until 2 years of age.

MEASUREMENTS AND MAIN RESULTS

After adjusting for covariates, we found that maternal smoking prior to preterm birth increased the odds of having an infant with BPD by twofold (P = 0.02). Maternal smoking was associated with prolonged mechanical ventilation and respiratory support during the neonatal intensive care unit admission. Preexisting hypertension was associated with a twofold (P = 0.04) increase in odds for BPD. Lower gestational age and birth weight z-scores were associated with BPD. Preterm infants who were exposed to maternal smoking had higher rates of late respiratory disease during childhood. Twenty-two percent of infants diagnosed with BPD and 34% of preterm infants without BPD had no clinical signs of late respiratory disease during early childhood.

CONCLUSIONS

We conclude that maternal smoking and hypertension increase the odds for developing BPD after preterm birth, and that maternal smoking is strongly associated with increased odds for late respiratory morbidities during early childhood. These findings suggest that in addition to the BPD diagnosis at 36 weeks, other factors modulate late respiratory outcomes during childhood. We speculate that measures to reduce maternal smoking not only will lower the risk for preterm birth but also will improve late respiratory morbidities after preterm birth.

Structural and functional ventilatory impairment in infants with severe bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is the most frequent serious complication in preterm infants. We aimed to describe lung structure and ventilatory function of preterm infants with severe BPD and explored the association between early postnatal growth and these outcomes.

METHODS

We included preterm infants born ≤32 weeks gestational age (GA) with severe BPD. Lung structure was assessed on chest CT with the PRAGMA-BPD scoring system and ventilatory function by polysomnography (PSG) at 6 months corrected age. Postnatal growth was assessed by weight measured at birth, and at 2 and 6 months corrected age.

RESULTS

We included 49 infants (median [IQR] GA of 25.7 [24.6-26.3] weeks and mean [SD] birth weight of 760 [210] g). A 95.5% of the chest CT scans showed architectural distortion of the lung, and an oxygen desaturation index (ODI) >5 was found in 74% of the infants. An increase in GA of 1 week was associated with higher total and normal lung volume (β coefficient [95% CI]: 1.86 [0.15, 3.57] and 2.03 [0.41, 3.65]), less hypoattenuation (-4.3 [-7.70, -0.90]%) and lower ODI (-36.7 [-64.2, -9.10]%). Higher weight at 6 months was independently associated with higher total and normal lung volume, and with less severe desaturations. Increased weight gain between 2 and 6 months of corrected age was associated with less severe desaturations during sleep (β coefficient [95% CI]: 2.09 [0.49, 3.70]).

CONCLUSION

Most preterm infants with severe BPD have structural lung abnormalities and impaired ventilatory function early in life, partly explained by birth characteristics and infant growth.

Novel role of NPY in neuroimmune interaction and lung growth after intrauterine growth restriction

Individuals with intrauterine growth restriction (IUGR) are at risk for chronic lung disease. Using a rat model, we showed in our previous studies that altered lung structure is related to IL-6/STAT3 signaling. As neuropeptide Y (NPY), a coneurotransmitter of the sympathetic nervous system, regulates proliferation and immune response, we hypothesized that dysregulated NPY after IUGR is linked to IL-6, impaired myofibroblast function, and alveolar growth. IUGR was induced in rats by isocaloric low-protein diet; lungs were analyzed on embryonic day (E) 21, postnatal day (P) 3, P12, and P23. Finally, primary neonatal lung myofibroblasts (pnF) and murine embryonic fibroblasts (MEF) were used to assess proliferation, apoptosis, migration, and IL-6 expression. At E21, NPY and IL-6 expression was decreased, and AKT/PKC and STAT3/AMPKα signaling was reduced. Early reduction of NPY/IL-6 was associated with increased chord length in lungs after IUGR at P3, indicating reduced alveolar formation. At P23, however, IUGR rats exhibited a catch-up of body weight and alveolar growth coupled with more proliferating myofibroblasts. These structural findings after IUGR were linked to activated NPY/PKC, IL-6/AMPKα signaling. Complementary, IUGR-pnF showed increased survival, impaired migration, and reduced IL-6 compared with control-pnF (Co-pnF). In contrast, NPY induced proliferation, migration, and increased IL-6 synthesis in fibroblasts. Additionally, NPY^-/- mice showed reduced IL-6 signaling and less proliferation of lung fibroblasts. Our study presents a novel role of NPY during alveolarization: NPY regulates 1) IL-6 and lung STAT3/AMPKα signaling, and 2) proliferation and migration of myofibroblasts. These new insights in pulmonary neuroimmune interaction offer potential strategies to enable lung growth.