Respiratory morbidity through the first decade of life in a national cohort of children born extremely preterm

Prospective epigenome and transcriptome analyses of cord and peripheral blood from preterm infants at risk of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a prevalent chronic lung disease of prematurity with limited treatment options. To uncover biomarkers of BPD risk, this study investigated epigenetic and transcriptomic signatures of prematurity at birth and during the neonatal period at day 14 and 28. Peripheral blood DNAs from preterm infants were applied to methylation arrays and cell-type composition was estimated by deconvolution. Covariate-adjusted robust linear regression elucidated BPD- and prolonged oxygen (≥ 14 days) exposure-associated CpGs. RNAs from cord and peripheral blood were sequenced, and differentially expressed genes (DEGs) for BPD or oxygen exposure were determined. Estimated neutrophil-lymphocyte ratios in peripheral blood at day 14 in BPD infants were significantly higher than nonBPD infants, suggesting an heightened inflammatory response in developing BPD. BPD-DEGs in cord blood indicated lymphopoiesis inhibition, altered Th1/Th2 responses, DNA damage, and organ degeneration. On day 14, BPD-associated CpGs were highly enriched in neutrophil activation, infection, and CD4 + T cell quantity, and BPD-DEGs were involved in DNA damage, cellular senescence, T cell homeostasis, and hyper-cytokinesis. On day 28, BPD-associated CpGs along with BPD-DEGs were enriched for phagocytosis, neurological disorder, and nucleotide metabolism. Oxygen supplementation markedly downregulated mitochondrial biogenesis genes and altered CpGs annotated to developmental genes. Prematurity-altered DNA methylation could cause abnormal lymphopoiesis, cellular assembly and cell cycle progression to increase BPD risk. Similar pathways between epigenome and transcriptome networks suggest coordination of the two in dysregulating leukopoiesis, adaptive immunity, and innate immunity. The results provide molecular insights into biomarkers for early detection and prevention of BPD.

Respiratory morbidity in preschool and school-age children born very preterm and its association with parents' health-related quality of life and family functioning

The purpose of this study is to describe the prevalence and severity of respiratory symptoms in children born very preterm and to assess their association with parents' health-related quality of life (HRQoL) and family functioning. We conducted a cross-sectional study and recruited children born less than 32 weeks' gestation between January 2006 and December 2019, in the greater Zurich area, Switzerland. Between May and December 2021, parents were invited to complete an online survey for their preterm child and for a control term born (≥ 37 weeks' gestation) sibling aged 1 to 18 years. We used a validated questionnaire to assess respiratory symptoms and the Pediatrics Quality of Life Family Impact Module (PedsQL FIM) to assess parents' HRQoL and family functioning. The survey was completed for 616 very preterm children (99 with bronchopulmonary dysplasia (BPD)) and 180 controls. Girls made up 45% (46% in controls) of the sample, and 63% (60% in controls) of participants were aged 6 to 18 years (school-age). Very preterm children reported a higher risk of respiratory symptoms than controls, especially preschoolers and those with moderate-to-severe BPD. Parents of children with "mild" and "moderate-severe" respiratory symptoms had on average -3.9 (95%CI: -6.6 to -1.1) and -8.2 (-11.2 to -5.2) lower PedsQL FIM total score, respectively, than parents of children with no symptoms. The same pattern was observed after stratifying by age categories.  Conclusions: Our study suggests that respiratory morbidity in very preterm children has a negative impact on parents' HRQoL and family functioning, even beyond the first years of life. What is Known: • The burden of respiratory morbidity associated with very premature birth is high and last far beyond the neonatal period. • Respiratory morbidity contributes to lower health-related quality of life (HRQoL) in parents of very preterm children in early infancy. What is New: • Respiratory morbidity in very preterm children has a negative impact on parents' HRQoL and family functioning beyond the first years of life. • Parents of very preterm children with moderate and severe respiratory symptoms are the ones who report lower scores, both for preschool and school-age children.

Risk of asthma in preterm infants with bronchopulmonary dysplasia: a systematic review and meta-analysis

BACKGROUND

This study aimed to systematically review and meta-analyze the available literature on the association between preterm infant bronchopulmonary dysplasia (BPD) and pre-adulthood asthma.

METHODS

Studies examining the association between BPD and asthma in children and adolescents were systematically reviewed, and a meta-analysis was conducted. We searched Scopus, Embase, Web of Science, PubMed, and Cochrane Library from the database inception to March 26, 2022. The pooled odds ratio (OR) estimate was used in our meta-analysis to calculate the correlation between BPD and the probability of developing asthma before adulthood. Stata 12.0 was used to conduct the statistical analysis.

RESULTS

The correlation between asthma and BPD in preterm newborns was examined in nine studies. We used a random effect model to pool the OR estimate. Our results indicated a marked increase in the risk of subsequent asthma in preterm infants with BPD [OR = 1.73, 95% confidence interval (CI) = 1.43-2.09]. Moreover, there was no obvious heterogeneity across the studies (P = 0.617, I² = 0%). The pooled OR remained stable and ranged from 1.65 (95% CI = 1.35-2.01) to 1.78 (95% CI = 1.43-2.21). Regarding publication bias, the funnel plot for asthma risk did not reveal any noticeable asymmetry. We further performed Begg's and Egger's tests to quantitatively evaluate publication bias. There was no evidence of a publication bias for asthma risk (P > |Z| = 0.602 for Begg's test, and P > |t| = 0.991 for Egger's test).

CONCLUSIONS

Our findings indicate that preterm infants with BPD have a much higher risk of developing asthma in the future (OR = 1.73, 95% CI = 1.43-2.09). Preterm infants with BPD may benefit from long-term follow-up.

Long-term burden of respiratory complications associated with extreme prematurity: An analysis of US Medicaid claims

BACKGROUND

Infants born extremely premature (EP) (<28 weeks gestational age) are at high risk of complications, particularly bronchopulmonary dysplasia (BPD), which can develop into chronic lung disease (CLD).

METHODS

The burden of respiratory complications in EP infants up to 2 years corrected age (CA) was evaluated using real-world data from the US Medicaid program. Data recorded between 1997 and 2018 on EP infants without major congenital malformations were collected from Medicaid records of six states. EP infants were divided into three cohorts: BPD, CLD, and without BPD or CLD. The incidence of respiratory conditions, respiratory medication use, and healthcare resource utilization were compared between the BPD cohort and CLD cohort versus the cohort without BPD or CLD, using unadjusted and adjusted generalized linear models.

RESULTS

A total of 4462 EP infants were identified (17.4% of all premature infants in the database). Of these, BPD and CLD were diagnosed in 61.9% and 72.1%, respectively, and 14.5% were diagnosed with neither BPD nor CLD. Compared with infants without BPD or CLD, infants with BPD or CLD had more complications and a longer length of birth hospitalization stay. Respiratory distress syndrome was the most frequently reported complication (94.6%, 92.5%, and 82.3% of EP infants in the BPD, CLD, and without BPD or CLD cohorts, respectively). After the birth hospitalization, respiratory conditions, respiratory medication use, and incidence rates of rehospitalizations, emergency room visits, and outpatient visits were higher for infants with BPD or CLD. Rehospitalization occurred in 50.5%, 51.6%, and 27.3% of EP infants with BPD, CLD, or without BPD or CLD, respectively; most hospitalizations occurred for respiratory-related reasons.

CONCLUSION

In this analysis of a large population of EP infants up to 2 years CA, respiratory conditions were prevalent after the birth hospitalization and were associated with high rates of medication and healthcare resource utilization.

Epigenome-wide association study of bronchopulmonary dysplasia in preterm infants: results from the discovery-BPD program

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a lung disease in premature infants caused by therapeutic oxygen supplemental and characterized by impaired pulmonary development which persists into later life. While advances in neonatal care have improved survival rates of premature infants, cases of BPD have been increasing with limited therapeutic options for prevention and treatment. This study was designed to explore the relationship between gestational age (GA), birth weight, and estimated blood cell-type composition in premature infants and to elucidate early epigenetic biomarkers associated with BPD.

METHODS

Cord blood DNA from preterm neonates that went on to develop BPD (n = 14) or not (non-BPD, n = 93) was applied to Illumina 450 K methylation arrays. Blood cell-type compositions were estimated using DNA methylation profiles. Multivariable robust regression analysis elucidated CpGs associated with BPD risk. cDNA microarray analysis of cord blood RNA identified differentially expressed genes in neonates who later developed BPD.

RESULTS

The development of BPD and the need for oxygen supplementation were strongly associated with GA (BPD, p < 1.0E-04; O2 supplementation, p < 1.0E-09) and birth weight (BPD, p < 1.0E-02; O2 supplementation, p < 1.0E-07). The estimated nucleated red blood cell (NRBC) percent was negatively associated with birth weight and GA, positively associated with hypomethylation of the tobacco smoke exposure biomarker cg05575921, and high-NRBC blood samples displayed a hypomethylation profile. Epigenome-wide association study (EWAS) identified 38 (Bonferroni) and 275 (false discovery rate 1%) differentially methylated CpGs associated with BPD. BPD-associated CpGs in cord blood were enriched for lung maturation and hematopoiesis pathways. Stochastic epigenetic mutation burden at birth was significantly elevated among those who developed BPD (adjusted p = 0.02). Transcriptome changes in cord blood cells reflected cell cycle, development, and pulmonary disorder events in BPD.

CONCLUSIONS

While results must be interpreted with caution because of the small size of this study, NRBC content strongly impacted DNA methylation profiles in preterm cord blood and EWAS analysis revealed potential insights into biological pathways involved in BPD pathogenesis.

Bronchopulmonary dysplasia

Bronchopulmonary dysplasia is the most frequent adverse outcome of prematurity. Before implementation of antenatal steroids and surfactant therapy, bronchopulmonary dysplasia was mostly characterized by fibrotic, scarred, and hyper-inflated lungs due to pulmonary injury following mechanical ventilation and oxygen toxicity. With advances in neonatal medicine, this "old" bronchopulmonary dysplasia has changed to a "new" bronchopulmonary dysplasia characterized by an arrest in lung growth, leading to alveolar simplification and pulmonary vascular dysangiogenesis. While the old definition was based on the need for oxygen supplementation at a postnatal age of 28 days or at a corrected gestational age of 36 weeks, the newer definition looks at the mode of respiratory support required (eg, invasive versus noninvasive) and is then graded as mild, moderate, or severe. Patients with bronchopulmonary dysplasia may present with significantly impaired pulmonary function, reactive airway disease, or exercise intolerance. Over time, these patients may develop asthma or chronic obstructive pulmonary disease. The most serious long-term complication is the development of pulmonary vascular disease and pulmonary hypertension. Medical treatment often includes diuretics, steroids, bronchodilators, or oxygen supplementation and in the presence of pulmonary hypertension medication to decrease the pulmonary vascular resistance. Perioperative anesthetic risk is increased in children with pulmonary hypertension. These patients might require additional diagnostic imaging and plans for increased resource allocation such as postoperative intensive care admission.

Murine Neonatal Oxidant Lung Injury: NRF2-Dependent Predisposition to Adulthood Respiratory Viral Infection and Protection by Maternal Antioxidant

NRF2 protects against oxidant-associated airway disorders via cytoprotective gene induction. To examine if NRF2 is an important determinant of respiratory syncytial virus (RSV) susceptibility after neonate lung injury, Nrf2-deficient (Nrf2^−/−) and wild-type (Nrf2^+/+) mice neonatally exposed to hyperoxia were infected with RSV. To investigate the prenatal antioxidant effect on neonatal oxidative lung injury, time-pregnant Nrf2^−/− and Nrf2^+/+ mice were given an oral NRF2 agonist (sulforaphane) on embryonic days 11.5–17.5, and offspring were exposed to hyperoxia. Bronchoalveolar lavage and histopathologic analyses determined lung injury. cDNA microarray analyses were performed on placenta and neonatal lungs. RSV-induced pulmonary inflammation, injury, oxidation, and virus load were heightened in hyperoxia-exposed mice, and injury was more severe in hyperoxia-susceptible Nrf2^−/− mice than in Nrf2^+/+ mice. Maternal sulforaphane significantly alleviated hyperoxic lung injury in both neonate genotypes with more marked attenuation of severe neutrophilia, edema, oxidation, and alveolarization arrest in Nrf2^−/− mice. Prenatal sulforaphane altered different genes with similar defensive functions (e.g., inhibition of cell/perinatal death and inflammation, potentiation of angiogenesis/organ development) in both strains, indicating compensatory transcriptome changes in Nrf2^−/− mice. Conclusively, oxidative injury in underdeveloped lungs NRF2-dependently predisposed RSV susceptibility. In utero sulforaphane intervention suggested NRF2-dependent and -independent pulmonary protection mechanisms against early-life oxidant injury.

Factors associated with recurrent wheezing in the first year of life among premature newborns from Neonatal Intensive Care Units

Abstract Objectives: to determine the prevalence and factors associated with recurrent wheezing in the first year of life among premature newborns from Neonatal Intensive Care Units, in the city of Montes Claros, northern Minas Gerais. Methods: cross-sectional study, with data collection from medical records of a follow-up clinic, interviews with mothers and, eventually, search in hospital records. Bivariate analyzes were carried out between sociodemographic and clinical characteristics and recurrent wheezing. Variables associated up to the level of 20% were analyzed by binary logistic regression, and associations defined by the Odds Ratio and respective 95% confidence intervals. Only variables associated with a 5% significance level were maintained in the final model of logistic regression. Results: among 277 infants studied, about one fifth (21.3%) were extremely low birth weight preterm and more than half (60.7%) had birth weight below 1500 grams. The prevalence of recurrent wheezing was 14.4% (CI95% = 10.3-18.4). Mechanical ventilation (OR = 2.12; CI95% = 1.09-4.76; p = 0.030) and oxygen therapy time ≥ 15 days (OR = 2.49; CI95%= 1.12-5.00; p = 0.010) were the risk factors for the event. Conclusions: there is a high prevalence of recurrent wheezing in the evaluated group and the associated variables reiterate the risk of prolonged oxygen therapy and mechanical ventilation for premature newborns.

ERK1/2 Signaling Pathway Activated by EGF Promotes Proliferation, Transdifferentiation, and Migration of Cultured Primary Newborn Rat Lung Fibroblasts

Background

Bronchopulmonary dysplasia (BPD) is a common and serious complication in premature infants. Lung fibroblasts (LFs) are present in the extracellular matrix and participate in pulmonary development in response to BPD. The aim of this study was to investigate the effect of extracellular signal-regulated kinase (ERK) on LFs cultured from newborn rats. Material and Methods. Primary LFs were isolated and treated with epidermal growth factor (EGF, 20 ng/mL) in the presence or absence of an ERK inhibitor, PD98059 (10 μmol/L). Phosphorylated ERK1/2 (p-ERK1/2) protein levels were determined using immunocytochemistry, western blotting, and real-time reverse transcription quantitative (RT–q)PCR. LF proliferation was examined by flow cytometry and a cell counting kit-8 assay. LF transdifferentiation was examined by protein and mRNA expression of α-smooth muscle actin (α-SMA) by immunocytochemistry, western blotting, and RT–qPCR. LF migration was examined by the transwell method.

Results

Phosphorylated ERK1/2, which was activated by EGF, promoted LF proliferation by accelerating cell-cycle progression from the G1 to S phase. After treatment with PD98059, the expression of p-ERK1/2 in LFs, cellular proliferation, and the percentage of cells in S phase were significantly decreased. Phosphorylated ERK1/2 also promoted the differentiation of LFs into myofibroblasts through increased α-SMA synthesis and migration.

Conclusion

The activation of ERK promotes proliferation, transdifferentiation, and migration of lung fibroblasts from newborn rats.

Comorbidity patterns and socioeconomic inequalities in children under 15 with medical complexity: a population-based study

Background

Children with medical complexity (CMC) denotes the profile of a child with diverse acute and chronic conditions, making intensive use of the healthcare services and with special health and social needs. Previous studies show that CMC are also affected by the socioeconomic position (SEP) of their family. The aim of this study is to describe the pathologic patterns of CMC and their socioeconomic inequalities in order to better manage their needs, plan healthcare services accordingly, and improve the care models in place.

Methods

Cross-sectional study with latent class analysis (LCA) of the CMC population under the age of 15 in Catalonia in 2016, using administrative data. LCA was used to define multimorbidity classes based on the presence/absence of 57 conditions. All individuals were assigned to a best-fit class. Each comorbidity class was described and its association with SEP tested. The Adjusted Morbidity Groups classification system (Catalan acronym GMA) was used to identify the CMC. The main outcome measures were SEP, GMA score, sex, and age distribution, in both populations (CMC and non-CMC) and in each of the classes identified.

Results

71% of the CMC population had at least one parent with no employment or an annual income of less than €18,000. Four comorbidity classes were identified in the CMC: oncology (36.0%), neurodevelopment (13.7%), congenital and perinatal (19.8%), and respiratory (30.5%). SEP associations were: oncology OR 1.9 in boys and 2.0 in girls; neurodevelopment OR 2.3 in boys and 1.8 in girls; congenital and perinatal OR 1.7 in boys and 2.1 in girls; and respiratory OR 2.0 in boys and 2.0 in girls.

Conclusions

Our findings show the existence of four different patterns of comorbidities in CMC and a significantly high proportion of lower SEP children in all classes. These results could benefit CMC management by creating more efficient multidisciplinary medical teams according to each comorbidity class and a holistic perspective taking into account its socioeconomic vulnerability.

Predicting physical activity in a national cohort of children born extremely preterm

Predicting physical activity in a national cohort of children born extremely preterm.

OBJECTIVES

To compare physical activity among school-aged children born extremely preterm or with extremely low birthweight (EP/ELBW) to term-born children, and to identify early predictors for physical inactivity in the EP/ELBW-children.

METHODS

A national cohort born during 1999-2000 at gestational age < 28 weeks or birthweight <1000 g and term-born controls were assessed. EP/ELBW-children without neurodevelopmental disabilities were labeled "healthy". At five years, we examined the EP/ELBW-children's motor, mental and intellectual functioning using the Movement Assessment Battery for Children (MABC), The Strength and Difficulties Questionnaire (SDQ) and The Wechsler Preschool and Primary Scale of Intelligence-revised. At 11 years, the parents reported their children's physical activity (PA) in questionnaires.

RESULTS

Information was obtained from 231/372 EP/ELBW and 57/61 term-born children. At 11 years, EP/ELBW-children had fewer exercise events per week, were less engaged in team sports, had lower endurance, lower sports proficiency, and were less vigorous during PA than term-born children (p < 0.05). Low sports proficiency in the healthy EP/ELBW-children at 11 years was predicted (odds ratio; 95% confidence interval) by abnormal MABC-score (3.0; 1.0 to 8.7), and abnormal SDQ-score (4.0; 1.6 to 10.0) at 5 years. Lower endurance at PA was predicted by abnormal MABC-score (2.6; 1.0 to 6.6), abnormal SDQ-score (3.0; 1.4 to 6.5), and borderline intellectual functioning (4.2; 1.8 to 10.1).

CONCLUSIONS

Eleven-year-old EP/ELBW-children were less physically active than term-born. In healthy EP/ELBW-children, impaired motor coordination, borderline intellectual functioning and behavioral problems at 5 years of age predicted unfavorable PA habits at 11 years.

Lifelong pulmonary sequelae of bronchopulmonary dysplasia

PURPOSE OF REVIEW

To summarize the current literature evaluating long-term pulmonary morbidity among surviving very preterm infants with bronchopulmonary dysplasia (BPD).

RECENT FINDINGS

BPD predisposes very preterm infants to adverse respiratory signs and symptoms, greater respiratory medication use, and more frequent need for rehospitalization throughout early childhood. Reassuringly, studies also indicate that older children and adolescents with BPD experience, on average, similar functional status and quality of life when compared to former very preterm infants without BPD. However, measured deficits in pulmonary function may persist in those with BPD and indicate an increased susceptibility to early-onset chronic obstructive pulmonary disease during adulthood. Moreover, subtle differences in exercise tolerance and activity may put survivors with BPD at further risk of future morbidity in later life.

SUMMARY

Despite advances in neonatal respiratory care, a diagnosis of BPD continues to be associated with significant pulmonary morbidity over the first two decades of life. Long-term longitudinal studies are needed to determine if recent survivors of BPD will also be at increased risk of debilitating pulmonary disease in adulthood.

Voice and Exercise Related Respiratory Symptoms in Extremely Preterm Born Children After Neonatal Patent Ductus Arteriosus

Objective: To investigate voice characteristics and exercise related respiratory symptoms in extremely preterm born 11-year-old children, focusing particularly on associations with management of a patent ductus arteriosus (PDA). Study design: Prospective follow-up of all children born in Norway during 1999-2000 at gestational age <28 weeks or with birthweight <1,000 g. Neonatal data were obtained prospectively on custom-made registration forms completed by neonatologists. Voice characteristics and exercise related respiratory symptoms were obtained at 11 years by parental questionnaires. Result: Questionnaires were returned for 228/372 (61%) eligible children, of whom 137 had no history of PDA. PDA had been noted in 91 participants, of whom 36 had been treated conservatively, 21 with indomethacin, and 34 with surgery. Compared to the children treated with indomethacin or conservatively, the odds ratio (95% confidence interval) for the surgically treated children were 3.4 (1.3; 9.2) for having breathing problems during exercise, 16.9 (2.0; 143.0) for having a hoarse voice, 4.7 (1.3; 16.7) for a voice that breaks when shouting, 4.6 (1.1; 19.1) for a voice that disturbs singing, and 3.7 (1.1; 12.3) for problems shouting or speaking loudly. The significance of surgery per se was uncertain since the duration of mechanical ventilation was associated with the same outcomes. Conclusion: Extremely preterm born children with a neonatal history of PDA surgery had more problems with voice and breathing during exercise in mid-childhood than those whose PDA had been handled otherwise. The study underlines the causal heterogeneity of exercise related respiratory symptoms in preterm born children.

Early Life Supraphysiological Levels of Oxygen Exposure Permanently Impairs Hippocampal Mitochondrial Function

Preterm infants requiring prolonged oxygen therapy often develop cognitive dysfunction in later life. Previously, we reported that 14-week-old young adult mice exposed to hyperoxia as newborns had spatial and learning deficits and hippocampal shrinkage. We hypothesized that the underlying mechanism was the induction of hippocampal mitochondrial dysfunction by neonatal hyperoxia. C57BL/6J mouse pups were exposed to 85% oxygen or room air from P2-P14. Hippocampal proteomic analysis was performed in young adult mice (14 weeks). Mitochondrial bioenergetics were measured in neonatal (P14) and young adult mice. We found that hyperoxia exposure reduced mitochondrial ATP-linked oxygen consumption and increased state 4 respiration linked proton leak in both neonatal and young adult mice while complex I function was decreased at P14 but increased in young adult mice. Proteomic analysis revealed that hyperoxia exposure decreased complex I NDUFB8 and NDUFB11 and complex IV 7B subunits, but increased complex III subunit 9 in young adult mice. In conclusion, neonatal hyperoxia permanently impairs hippocampal mitochondrial function and alters complex I function. These hippocampal mitochondrial changes may account for cognitive deficits seen in children and adolescents born preterm and may potentially be a contributing mechanism in other oxidative stress associated brain disorders.

Sleep problems, behavioural problems and respiratory health in children born extremely preterm: a parental questionnaire study

OBJECTIVE

To explore whether children born extremely preterm (EPT) with different types of sleep problems had more behavioural and respiratory health problems than EPT children without sleep problems.

DESIGN

Prospective, nationwide, questionnaire-based study. At 11 years of age, parents reported on four current sleep problems: difficulty falling asleep or frequent awakenings, snoring, daytime sleepiness and not recommended sleep duration (<9 hours). Behavioural problems were assessed by parents and teachers with the Strengths and Difficulties Questionnaire (SDQ). Parents assessed respiratory symptoms with the International Study of Asthma and Allergies in Childhood questionnaire and described use of asthma medication.

SETTING

Norway.

PATIENTS

EPT children.

MAIN OUTCOME MEASURES

Specified sleep problems, behavioural problems and respiratory health.

RESULTS

Data were obtained from 216 of 372 (58 %) of eligible children. All four specified sleep problems were associated with significantly higher parent-reported SDQ total-score (OR 1.1 for all), and except for not recommended sleep duration, also with higher teacher-reported SDQ total-score (OR 1.1 for all). Daytime sleepiness was strongly associated with wheezing last 12 months (OR 3.4), disturbed sleep due to wheezing (OR 3.9), wheeze during or after exercise (OR 2.9), use of inhaled corticosteroids or oral leukotriene modifiers (OR 3.4) and use of bronchodilators (OR 3.9). Snoring was associated with wheezing during or after exercise (OR 2.8) and current asthma (OR 4.2).

CONCLUSION

EPT children with different types of sleep problems had more behavioural and respiratory health problems than EPT children without sleep problems.

Risk factors for chronic lung disease and asthma differ among children born extremely preterm

OBJECTIVES

To evaluate the hypothesis that chronic lung disease of prematurity (CLD) is a risk factor for asthma in children born extremely preterm, and the hypothesis that the risk factors for CLD are similar to those for asthma.

METHODS

A retrospective analysis was performed using data collected prospectively from 882 children born before the 28th week of gestation between 2002 and 2004 who returned for follow-up at ages 12 and 24 months and 10 years. We created time-oriented logistic regression models to compare risk factors for CLD, defined as need for supplemental oxygen at 36 weeks postmenstrual age, and parent-reported asthma at 10 years of age.

RESULTS

CLD diagnosed during neonatal admission was associated with bronchodilator use at 12 months and 24 months (P < 0.001), but not with an asthma diagnosis at 10 years (Odds Ratio 1.3; 95% confidence interval 0.98-1.8). While risk factors for CLD include lower gestational age (OR 2.7; 1.5-4.7) and fetal growth restriction (OR 2.3; 1.4-3.7), risk factors for asthma include mother's eligibility for public insurance (Medicaid) (OR 1.8; 1.1-2.8), and higher weight gain velocity during the first year (OR 1.5; 1.02-2.2) and between the 2nd and 10th year (OR 1.7; 1.2-2.4).

CONCLUSIONS

Among children born extremely preterm, the diagnosis of CLD and its antecedents were associated with transient preschool wheezing, but not with asthma. Post-NICU factors, such as growth velocity and socioeconomic disadvantage, appear to have stronger associations with asthma than exposures during NICU admission.

Supraphysiological Levels of Oxygen Exposure During the Neonatal Period Impairs Signaling Pathways Required for Learning and Memory

Preterm infants often require prolonged oxygen supplementation and are at high risk of neurodevelopmental impairment. We recently reported that adult mice exposed to neonatal hyperoxia (postnatal day [P] 2 to 14) had spatial navigation memory deficits associated with hippocampal shrinkage. The mechanisms by which early oxidative stress impair neurodevelopment are not known. Our objective was to identify early hyperoxia-induced alterations in hippocampal receptors and signaling pathways necessary for memory formation. We evaluated C57BL/6 mouse pups at P14, exposed to either 85% oxygen or air from P2 to 14. We performed targeted analysis of hippocampal ligand-gated ion channels and proteins necessary for memory formation, and global bioinformatic analysis of differentially expressed hippocampal genes and proteins. Hyperoxia decreased hippocampal mGLU7, TrkB, AKT, ERK2, mTORC1, RPS6, and EIF4E and increased α3, α5, and ɤ2 subunits of GABA_A receptor and PTEN proteins, although changes in gene expression were not always concordant. Bioinformatic analysis indicated dysfunction in mitochondria and global protein synthesis and translational processes. In conclusion, supraphysiological oxygen exposure reduced proteins necessary for hippocampus-dependent memory formation and may adversely impact hippocampal mitochondrial function and global protein synthesis. These early hippocampal changes may account for memory deficits seen in preterm survivors following prolonged oxygen supplementation.