Maternal and fetal origins of lung disease in adulthood

Prenatal Exposure to Air Pollution and Respiratory Distress in Term Newborns: Results from the MIREC Prospective Pregnancy Cohort

BACKGROUND

Respiratory distress is the leading cause of neonatal morbidity and mortality worldwide, and prenatal exposure to air pollution is associated with adverse long-term respiratory outcomes; however, the impact of prenatal air pollution exposure on neonatal respiratory distress has not been well studied.

OBJECTIVES

We examined associations between prenatal exposures to fine particular matter (PM 2.5 ) and nitrogen dioxide (NO 2 ) with respiratory distress and related neonatal outcomes.

METHODS

We used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a prospective pregnancy cohort (n = 2,001 ) recruited in the first trimester from 10 Canadian cities. Prenatal exposures to PM 2.5 (n = 1,321 ) and NO 2 (n = 1,064 ) were estimated using land-use regression and satellite-derived models coupled with ground-level monitoring and linked to participants based on residential location at birth. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between air pollution and physician-diagnosed respiratory distress in term neonates in hierarchical logistic regression models adjusting for detailed maternal and infant covariates.

RESULTS

Approximately 7 % of newborns experienced respiratory distress. Neonates received clinical interventions including oxygen therapy (6%), assisted ventilation (2%), and systemic antibiotics (3%). Two percent received multiple interventions and 4% were admitted to the neonatal intensive care unit (NICU). Median PM 2.5 and NO 2 concentrations during pregnancy were 8.81   μ g / m 3 and 18.02  ppb , respectively. Prenatal exposures to air pollution were not associated with physician-diagnosed respiratory distress, oxygen therapy, or NICU admissions. However, PM 2.5 exposures were strongly associated with assisted ventilation (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.17 ; 95% CI: 1.02, 1.35), multiple clinical interventions (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.16 ; 95% CI: 1.07, 1.26), and systemic antibiotics, (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.12 ; 95% CI: 1.04, 1.21). These associations were consistent across exposure periods-that is, during prepregnancy, individual trimesters, and total pregnancy-and robust to model specification. NO 2 exposure was associated with administration of systemic antibiotics (OR per 1-ppb increase in NO 2 = 1.03 ; 95% CI: 1.00, 1.06).

DISCUSSION

Prenatal exposures to PM 2.5 increased the risk of severe respiratory distress among term newborns. These findings support the development and prioritization of public health and prenatal care strategies to increase awareness and minimize prenatal exposures to air pollution. https://doi.org/10.1289/EHP12880.

Maternal depressive symptoms during pregnancy and infant wheezing up to 2 years of age

PURPOSE

To determine whether maternal depressive symptoms at multiple time points during pregnancy are associated with infant wheezing in the first 2 years of life to assess etiologically relevant time windows.

METHODS

We included Dutch women participating in the PRIDE Study with delivery in 2013-2019. Maternal depressive symptoms were assessed with the Hospital Anxiety and Depression Scale and Edinburgh Depression Scale at enrollment and in gestational weeks 17 and 34. The International Study of Asthma and Allergies in Childhood questionnaire was used to assess infant wheezing biannually postpartum. Adjusted risk ratios (RRs) and 95% confidence intervals (CIs) were estimated with modified Poisson regression.

RESULTS

Among 5294 pregnancies included, maternal depressive symptoms in gestational weeks 15-22 was associated with any wheezing in the first 2 years of life (RR 1.36, 95% CI 1.04-1.78) and with current wheezing at 12 (RR 1.29, 95% CI 1.03-1.61) and 18 months (RR 1.33, 1.04-1.69). Depressive symptoms in gestational weeks 32-35 seemed to be associated with any wheezing reported at two years (RR 1.27, 95% CI 0.96-1.69) and current wheezing at 12 months (RR 1.28, 95% CI 1.02-1.60). Four trajectories of depressive symptoms were identified. Only the trajectory with increasing symptoms throughout pregnancy seemed to be associated with infant wheezing (RR 1.36, 95% CI 0.97-1.89).

CONCLUSIONS

Maternal depressive symptoms in mid- and late pregnancy may be associated with development of infant wheezing, particularly those with onset in the second half of pregnancy. Research is needed to identify biological pathways and associations with more objective, long-term respiratory morbidity.

Early life exposure to cigarette smoking and adult and old-age male mortality: Evidence from linked US full-count census and mortality data

BACKGROUND

Smoking is a leading cause of premature death across contemporary developed nations, but few longitudinal individual-level studies have examined the long-term health consequences of exposure to smoking.

OBJECTIVE

We examine the effect of fetal and infant exposure to exogenous variation in smoking, brought about by state-level cigarette taxation, on adulthood and old-age mortality (ages 55-73) among cohorts of boys born in the United States during the 1920s and 1930s.

METHODS

We use state-of-the-art methods of record linkage to match 1930 and 1940 US full-count census records to death records, identifying early life exposure to the implementation of state-level cigarette taxes through contemporary sources. We examine a population of 2.4 million boys, estimating age at death by means of OLS regression, with post-stratification weights to account for linking selectivity.

RESULTS

Fetal or infant exposure to the implementation of state cigarette taxation delayed mortality by about two months. Analyses further indicate heterogenous effects that are consistent with theoretical expectations; the largest benefits are enjoyed by individuals with parents who would have been affected most by the tax implementation.

CONCLUSIONS

Despite living in an era of continuously increasing cigarette consumption, cohorts exposed to a reduction in cigarette smoking during early life enjoyed a later age at death. While it is not possible to comprehensively assess the treatment effect on the treated, the magnitude of the effect should not be underestimated, as it is larger than the difference between having parents belonging to the highest and lowest socioeconomic groups.

CONTRIBUTION

The study provides the first estimates of long-run health effects from early life exposure to cigarette smoking.

Maternal diet modulates the infant microbiome and intestinal Flt3L necessary for dendritic cell development and immunity to respiratory infection

Poor maternal diet during pregnancy is a risk factor for severe lower respiratory infections (sLRIs) in the offspring, but the underlying mechanisms remain elusive. Here, we demonstrate that in mice a maternal low-fiber diet (LFD) led to enhanced LRI severity in infants because of delayed plasmacytoid dendritic cell (pDC) recruitment and perturbation of regulatory T cell expansion in the lungs. LFD altered the composition of the maternal milk microbiome and assembling infant gut microbiome. These microbial changes reduced the secretion of the DC growth factor Flt3L by neonatal intestinal epithelial cells and impaired downstream pDC hematopoiesis. Therapy with a propionate-producing bacteria isolated from the milk of high-fiber diet-fed mothers, or supplementation with propionate, conferred protection against sLRI by restoring gut Flt3L expression and pDC hematopoiesis. Our findings identify a microbiome-dependent Flt3L axis in the gut that promotes pDC hematopoiesis in early life and confers disease resistance against sLRIs.

Time series of transcriptome analysis in entire lung development stages provide insights into the origin of NO2 related lung diseases

Lung growth is a critical window, when exposure to various pollutants can disturb the finely-tuned lung development and enhance risk of long-term structural and functional sequelae of lung. In this study, pregnant C57/6 mice were treated with NO2, and lungs of fetus/offspring were collected at different developmental windows and dynamic lung development was determined. The results showed that maternal NO2 exposure suppressed fetal weight, implying that fetal development can be disturbed. The time-series RNA-seq analysis of lungs showed that maternal NO2 exposure induced significant time-dependent changes in the expression profiles of genes associated with lung vein myocardium development in fetus/offspring. Most of these genes in NO2 exposure group were suppressed at middle gestation and at birth. Our results also indicated that the gene expressions of Nkx2.5 in NO2 exposure were suppressed to 0.27- and 0.44-fold of the corresponding Air group at E13.5 and PND1, and restored at later time points. This indicated that the transcription factor Nkx2.5 played an important role in abnormal lung development in fetus/offspring caused by maternal NO2 exposure. Importantly, gene expressions of lung vein myocardium development were related to transcription factors (TFs) and lung functions, and TFs showed similar trends with lung function. These results provide a comprehensive view of the adverse effects of maternal NO2 exposure on fetal lung development by uncovering molecular targets and related signaling pathways at the transcriptional level.

Poor early childhood growth is associated with impaired lung function: Evidence from a Ghanaian pregnancy cohort

OBJECTIVES

Nearly 40% of African children under 5 are stunted. We leveraged the Ghana randomized air pollution and health study (GRAPHS) cohort to examine whether poorer growth was associated with worse childhood lung function.

STUDY DESIGN

GRAPHS measured infant weight and length at birth and 3, 6, 9,12 months, and 4 years of age. At age 4 years, n = 567 children performed impulse oscillometry. We employed multivariable linear regression to estimate associations between birth and age 4 years anthropometry and lung function. Next, we employed latent class growth analysis (LCGA) to generate growth trajectories through age 4 years. We employed linear regression to examine associations between growth trajectory assignment and lung function.

RESULTS

Birth weight and age 4 weight-for-age and height-for-age z-scores were inversely associated with airway resistance (e.g., R5 , or total airway resistance: birth weight β = -0.90 cmH2O/L/s, 95% confidence interval [CI]: -1.64, -0.16 per 1 kg increase; and R20 , or large airway resistance: age 4 height-for-age β = -0.40 cmH2O/L/s, 95% CI: -0.57, -0.22 per 1 unit z-score increase). Impaired growth trajectories identified through LCGA were associated with higher airway resistance, even after adjusting for age 4 body mass index. For example, children assigned to a persistently stunted trajectory had higher R5 (β = 2.71 cmH2O/L/s, 95% CI: 1.07, 4.34) and R20 (β = 1.43 cmH2O/L/s, 95% CI: 0.51, 2.36) as compared to normal.

CONCLUSION

Children with poorer anthropometrics through to age 4 years had higher airway resistance in early childhood. These findings have implications for lifelong lung health, including pneumonia risk in childhood and reduced maximally attainable lung function in adulthood.

Exposure to heat during pregnancy and preterm birth in North Carolina: Main effect and disparities by residential greenness, urbanicity, and socioeconomic status

BACKGROUND

Although previous literature suggested that several factors may be associated with higher risk of adverse health outcomes related to heat, research is limited for birth outcomes.

OBJECTIVES

We investigated associations between exposure to heat/heat waves during the last week of gestation and preterm birth (PTB) in North Carolina (NC) and evaluated effect modification by residential greenness, urbanicity, and socioeconomic status (SES).

METHODS

We obtained individual-level NC birth certificate data for May-September 2003-2014. We estimated daily mean temperature at each maternal residential address using Parameter-elevation Regressions on Independent Slopes Model (PRISM) data. We created 3 definitions of heat waves (daily temperature ≥95th, 97th, 99th percentile for NC warm season temperature, for ≥2 consecutive days). Normalized Difference Vegetation Index (NDVI) was used to assess residential greenness. Community-level modifiers (e.g., income, urbanicity) were considered. We applied Cox proportional hazard models to estimate the association between exposure to heat/heat waves and PTB, controlling for covariates. Stratified analyses were conducted to evaluate whether the association between heat and PTB varied by several individual and community characteristics.

RESULTS

Of the 546,441 births, 8% were preterm. Heat exposure during the last week before delivery was significantly associated with risk of PTB. The hazard ratio for a 1 °C increase in temperature during the last week before delivery was 1.01 (95% CI: 1.00, 1.02). Higher heat-PTB risk was associated with some characteristics (e.g., areas that were urbanized, low SES, or in the Coastal Plain). We also found significant PTB-heat risk in areas with low greenness for urbanized area. For heat waves, we did not find significantly positive associations with PTB.

DISCUSSION

Findings provide evidence that exposure to heat during pregnancy increases risk of PTB and suggest disparities in these risks. Our results have implications for future studies of disparity in heat and birth outcomes associations.

Inducible factors and interaction of pulmonary fibrosis induced by prenatal dexamethasone exposure in offspring rats

This study aimed to investigate the correlation between prenatal dexamethasone exposure (PDE) and susceptibility to pulmonary fibrosis in offspring. Healthy female Wistar rats were given dexamethasone (0.2 mg/kg.d) or an equal volume of normal saline subcutaneously from 9 to 20 days after conception. Some of their female offspring underwent ovariectomy (OV) at 22 weeks after birth. All animals were euthanized at 28 weeks after birth. The morphological changes related to pulmonary fibrosis and extracellular matrix-related gene expression were detected, and Two-way ANOVA analyzed the interaction between PDE and OV. The results showed that adult offspring rats in FD group (female rats with PDE treatment) had early pulmonary fibrosis changes, such as pulmonary interstitial thickening, and increased expression of type IV collagen (COL4), α -smooth muscle actin (α-SMA) and fibronectin (FN) in lung tissues compared with those in FC group (female rats with saline treatment). In addition, adult offspring rats in FDO group (female rats with PDE and OV treatment) showed signs of pulmonary fibrosis, including apparent extracellular matrix deposition, increased lung injury scores (P＜0.01, P＜0.05), and extracellular matrix related gene expression (P＜0.01, P＜0.05), compared with rats in FDS (female rats with PDE treatment alone) or rats in FCO group (female rats with OV treatment alone). Moreover, PDE and OV had an interactive effect on the development of pulmonary fibrosis in female adult offspring. This study first reported the correlation between PDE and susceptibility to pulmonary fibrosis in female offspring rats, as well as the synergistic effect of PDE and OV in this pathological event, which provided a basis for further understanding of the pathogenesis of fetal originated pulmonary fibrosis.

Prematurity and Long-Term Respiratory Morbidity—What Is the Critical Gestational Age Threshold?

Respiratory morbidity is a hallmark complication of prematurity. Children born preterm are exposed to both short- and long-term respiratory morbidity. This study aimed to investigate whether a critical gestational age threshold exists for significant long-term respiratory morbidity. A 23-year, population-based cohort analysis was performed comparing singleton deliveries at a single tertiary medical center. A comparison of four gestational age groups was performed according to the WHO classification: term (≥37.0 weeks, reference group), moderate to late preterm (32.0–36.6 weeks), very preterm (28.0–31.6 weeks) and extremely preterm (24.0–27.6 weeks). Hospitalizations of the offspring up to the age of 18 years involving respiratory morbidities were evaluated. A Kaplan–Meier survival curve was used to compare cumulative hospitalization incidence between the groups. A Cox proportional hazards model was used to control for confounders and time to event. Overall, 220,563 singleton deliveries were included: 93.6% term deliveries, 6% moderate to late preterm, 0.4% very preterm and 0.1% extremely preterm. Hospitalizations involving respiratory morbidity were significantly higher in children born preterm (12.7% in extremely preterm children, 11.7% in very preterm, 7.0% in late preterm vs. 4.7% in term, p < 0.001). The Kaplan–Meier survival curve demonstrated a significantly higher cumulative incidence of respiratory-related hospitalizations in the preterm groups (log-rank, p < 0.001). In the Cox regression model, delivery before 32 weeks had twice the risk of long-term respiratory morbidity. Searching for a specific gestational age threshold, the slope for hospitalization rate was attenuated beyond 30 weeks’ gestation. In our population, it seems that 30 weeks’ gestation may be the critical threshold for long-term respiratory morbidity of the offspring, as the risk for long-term respiratory-related hospitalization seems to be attenuated beyond this point until term.

Can birth weight predict offspring's lung function in adult age? Evidence from two Swedish birth cohorts

BACKGROUND

Associations between birth weight (BW) and adult lung function have been inconsistent and limited to early adulthood. We aimed to study this association in two population-based cohorts and explore if BW, adjusted for gestational age, predicts adult lung function. We also tested adult lung function impairment according to the mis-match hypothesis-small babies growing big as adults.

METHODS

We included 3495 individuals (aged 46.4 ± 5.4 years) from the Malmo Preventive Project (MPP), Sweden, born between 1921 and 1949, and 1401 young to middle-aged individuals (aged 28.6 ± 6.7 years) from the Malmo Offspring Study (MOS) with complete data on BW and gestational age. Adult lung function (forced vital capacity [FVC], forced expiratory volume in one second [FEV1] and the FEV1/FVC-ratio) were analysed as level of impairment (z-score), using multiple linear and logistic regressions.

RESULTS

BW (z-score) did not predict adult lung function in MPP, whereas BW was a significant (p = 0.003) predictor of FEV1 following full adjustment in MOS. For every additional unit increase in BW, children were 0.77 (95% CI 0.65-0.92) times less likely to have impaired adult lung function (FEV1). Moreover, adults born with lower BW (< 3510 g) showed improved lung function (FEV1 and FEV1/FVC in MOS and MPP, respectively) if they achieved higher adult body weight.

CONCLUSIONS

Adults born with lower birth weight, adjusted for gestational age, are more likely to have impaired lung function, seen in a younger birth cohort. Postnatal growth pattern may, however, compensate for low birth weight and contribute to better adult lung function.

Mmp12 Is Upregulated by in utero Second-Hand Smoke Exposures and Is a Key Factor Contributing to Aggravated Lung Responses in Adult Emphysema, Asthma, and Lung Cancer Mouse Models

Matrix metalloproteinase-12 (Mmp12) is upregulated by cigarette smoke (CS) and plays a critical role in extracellular matrix remodeling, a key mechanism involved in physiological repair processes, and in the pathogenesis of emphysema, asthma, and lung cancer. While cigarette smoking is associated with the development of chronic obstructive pulmonary diseases (COPD) and lung cancer, in utero exposures to CS and second-hand smoke (SHS) are associated with asthma development in the offspring. SHS is an indoor air pollutant that causes known adverse health effects; however, the mechanisms by which in utero SHS exposures predispose to adult lung diseases, including COPD, asthma, and lung cancer, are poorly understood. In this study, we tested the hypothesis that in utero SHS exposure aggravates adult-induced emphysema, asthma, and lung cancer.

Methods: Pregnant BALB/c mice were exposed from gestational days 6–19 to either 3 or 10mg/m³ of SHS or filtered air. At 10, 11, 16, or 17weeks of age, female offspring were treated with either saline for controls, elastase to induce emphysema, house-dust mite (HDM) to initiate asthma, or urethane to promote lung cancer. At sacrifice, specific disease-related lung responses including lung function, inflammation, gene, and protein expression were assessed.

Results: In the elastase-induced emphysema model, in utero SHS-exposed mice had significantly enlarged airspaces and up-regulated expression of Mmp12 (10.3-fold compared to air-elastase controls). In the HDM-induced asthma model, in utero exposures to SHS produced eosinophilic lung inflammation and potentiated Mmp12 gene expression (5.7-fold compared to air-HDM controls). In the lung cancer model, in utero exposures to SHS significantly increased the number of intrapulmonary metastases at 58weeks of age and up-regulated Mmp12 (9.3-fold compared to air-urethane controls). In all lung disease models, Mmp12 upregulation was supported at the protein level.

Conclusion: Our findings revealed that in utero SHS exposures exacerbate lung responses to adult-induced emphysema, asthma, and lung cancer. Our data show that MMP12 is up-regulated at the gene and protein levels in three distinct adult lung disease models following in utero SHS exposures, suggesting that MMP12 is central to in utero SHS-aggravated lung responses.

Hypertensive disorders in pregnancy and risk of asthma in offspring: a systematic review and meta-analysis

OBJECTIVES

The association between hypertensive disorders in pregnancy (HDP) and an increased risk of asthma in offspring remains controversial. No systematic review of this topic has been performed. The aim of this systematic review was to summarise the available evidence regarding the association between HDP and the risk of asthma in offspring.

DESIGN

Systematic review and meta-analysis.

METHODS

On the basis of a prepared protocol, a systematic search of PubMed, EMBASE, the Cochrane Library and Web of Science was performed using a detailed search strategy from the database inception to 17 January 2020. Cohort, case-control and cross-sectional studies published in English reporting the diagnoses of maternal HDP and asthma in offspring were included. The Meta-analysis of Observational Studies in Epidemiology guidelines were followed throughout the study. The estimated pooled ORs of HDP and asthma in offspring were calculated from the studies, and the meta-analysis was performed using random-effects models.

RESULTS

Ten cohort studies involving a total of 6 270 430 participants were included. According to the Newcastle-Ottawa Scale, the overall methodological quality was good since 8 studies were of high quality and 2 studies were of moderate quality. After controlling for potential confounders, HDP was associated with a possible increased risk of asthma in offspring, with a pooled adjusted OR (aOR) of 1.19 (95% CI 1.12 to 1.26). The subgroup analyses according to HDP subgroups, sibling design, study quality, study location, offspring ages, singleton status, exposure assessment, outcome assessment and adjusted factors showed similar results.

CONCLUSIONS

Exposure to HDP may be associated with an increased risk of asthma in offspring. Further research is needed to verify the results and determine whether the observed relationship is causal.

PROSPERO REGISTRATION NUMBER

CRD42020148250.

Impact of gestational electronic cigarette vaping on amino acid signature profile in the pregnant mother and the fetus

Background

Electronic cigarettes (e-cigs) are a form of tobacco product that has become increasingly popular over the past decade. Despite the known health consequences of tobacco product exposure during pregnancy, a substantial number of daily smokers will continue to smoke during pregnancy. Our current knowledge on the effects of e-cig aerosol exposure during pregnancy is limited to a small number of animal studies, which have identified several e-cig aerosol-induced disruptions to the physiology of normal development.

Methods

To further assess the impact of prenatal e-cig aerosol exposure on maternal and fetal health, we examined the amino acid signature profiles in maternal and fetal plasma, as well as in the fetal lungs, a sensitive target organ for prenatal tobacco product exposure. Pregnant Sprague Dawley rats were randomly assigned to one of three groups and were exposed to either e-cig aerosols containing nicotine, e-cig aerosols without nicotine, or room air. Dams were exposed utilizing a state-of-the-art custom engineered e-cig vaping system that is compatible with commercially available e-cig atomizers and enables a translational inhalation delivery method comparable to human vaping.

Results

We determined that gestational exposure to e-cig aerosols results in significant alterations to the amino acid profile in the maternal and fetal compartments, including the fetal lungs. The data shows a targeted disruption to the nitric oxide pathway, branched-chain amino acid metabolism, fetal protein synthesis, and urea cycle.

Conclusion

The data presented herein provides additional support that gestational e-cig aerosol exposure can impact crucial biological processes and exemplifies the need for extensive research on exposure to e-cig aerosols.

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First report of e-cig induced alterations to maternal/fetal amino acid profile.

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Translational vaping paradigm utilizing custom engineered vaping system.

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Analysis of amino acids show gestational e-cig exposure has significant effects.

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Fetal lungs may be a sensitive target to gestational e-cig aerosol exposure.

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Marker of dysregulation in branched-chain amino acid metabolism and urea cycle.

Factors associated with extubation failure in very low birth weight infants: a cohort study in the northeast Brazil

OBJECTIVES

Identifying and understanding the main risk factors associated with extubation failure of very low birthweight (VLBW) infants in different populations can subsequently help in establishing better criteria while taking decision of extubation. The aim of the study was to identify factors associated with extubation failure in VLBW infants.

METHODS

A cohort study of VLBW infants who underwent their first extubation between April 2018 and December 2019 in a Neonatal Intensive Care Unit, Alagoas, Brazil, were included in this study. Extubation failure was defined as reintubation within seven days of extubation. Relative risks of predictive variables different between the extubation success group (ES) and extubation failure group (EF) were estimated with a robust Poisson regression model.

RESULTS

Out of the 112 infants included, 26 (23%) cases exhibited extubation failure. Extremely low birth weight (RR 2.55, 95% CI 1.07, 6.06), mechanical ventilation duration for first extubation greater than seven days (RR 2.66, 95% CI 1.10, 6.45), vaginal delivery (RR 2.07, 95% CI 1.03, 4.18) and maternal chorioamnionitis (RR 4.89, 95% CI 1.26-18.98) remained independently associated with extubation failure. EF had a significant greater need for respiratory support, longer oxygen therapy duration, more bronchopulmonary dysplasia (BPD) and longer length of hospital stay, even when adjusted for confounding variables.

CONCLUSIONS

Extremely low birth weight infants needing mechanical ventilation, wherein the duration for first extubation was longer than seven days, with vaginal delivery and maternal chorioamnionitis failed more frequently at the first attempt of extubation. And this failure increased the risk of BPD and the length of hospital stay.

The effect of maternal protein restriction during perinatal life on the inflammatory response in pediatric rats

Fetal growth restriction can affect health outcomes in postnatal life. This study tested the hypothesis that the response to an inflammatory pulmonary insult is altered in pediatric fetal growth restricted rats. Using a low-protein diet during gestation and postnatal life, growth-restricted male and female rats and healthy control rats were exposed to an inflammatory insult via the intratracheal instillation of heat-killed bacteria. After 6 h, animal lungs were examined for lung inflammation and status of the surfactant system. The results showed that in response to an inflammatory insult, neutrophil infiltration was decreased in both male and female rats in the growth-restricted animals compared with the control rats. The amount of surfactant was increased in the growth-restricted animals compared with the control rats, regardless of the inflammatory insult. It is concluded that fetal growth restriction results in increased surfactant and altered neutrophil responses following pulmonary insult.

Association of Hemoglobin and Hematocrit Levels during Pregnancy and Maternal Dietary Iron Intake with Allergic Diseases in Children: The Japan Environment and Children's Study (JECS)

Few epidemiologic studies have examined the role of maternal iron status in allergic diseases in offspring and findings have been inconsistent. We used a large birth cohort in Japan to explore the association of the markers for maternal iron status (maternal hemoglobin, hematocrit and dietary iron intake during pregnancy) with allergy development in offspring during early childhood. We analyzed information on children age 0–3 years from the Japan Environment and Children’s Study (JECS). We used logistic models and generalized estimating equation models to evaluate the effect of maternal hemoglobin and hematocrit levels and dietary iron intake on allergies in children. Models were also fitted with propensity score-matched datasets. Data were collected for a total of 91,247 mother–child pairs. The prevalence (95% confidence interval) of low hemoglobin and hematocrit was 14.0% (13.7–14.2%) and 12.5% (12.3–12.8%), respectively. After adjusting confounders, low hemoglobin and hematocrit during pregnancy were not associated with childhood allergic outcomes. Findings from models with propensity score-matched datasets also indicated that children born to mothers with low hemoglobin or hematocrit levels during pregnancy did not have a higher risk of developing allergic conditions at 3 years old. We found no meaningful associations between low energy adjusted maternal dietary iron intake and allergies in children. In conclusion, using birth cohort data, we found no evidence supporting an association of low maternal hemoglobin, hematocrit and low dietary iron intake with allergy symptoms during early childhood. Further studies with more suitable proxy markers for blood iron status are needed.

Intrauterine exposure to per- and polyfluoroalkyl substances may harm children's lung function development

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS), such as perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUA), are common persistent environmental organic pollutants. Animal studies have indicated that PFAS influence inflammatory responses and lung development. However, whether prenatal or childhood PFAS exposure affects children's lung function remains unclear. This study aimed to investigate both in utero exposure and childhood exposure to PFAS and the relationships between them and lung function development in childhood.

METHODS

In total, 165 children were recruited from the Taiwan Birth Panel Study (TBPS). Cord blood plasma and children's serum were collected when they were eight years old. PFAS levels were analysed by ultra-high-performance liquid chromatography/tandem mass spectrometry. When these children reached eight years of age, we administered detailed questionnaires and lung function examinations.

RESULTS

The mean concentrations of PFOA, PFOS, PFNA and PFUA in cord blood among the 165 study children were 2.4, 6.4, 6.0, and 15.4 ng/mL, respectively. The mean concentrations in serum from eight-year-olds were 2.7, 5.9, 0.6, and 0.3 ng/mL, respectively. At eight years of age, the mean FEV1 (forced expiratory volume per sec), FVC (forced vital capacity), PEF (peak expiratory flow) and FEV1/FVC values were 1679 mL, 1835 mL, 3846 mL/s and 92.0%, respectively. PFOA, PFOS, PFNA and PFUA levels in cord blood were inversely associated with FEV1, FVC and PEF values. The PFOS concentration in cord blood was the most consistently correlated with decreasing lung function before and after adjusting for confounding factors. The PFOS concentration was also significantly inversely correlated with lung function in subgroups with lower birth weight and allergic rhinitis.

CONCLUSIONS

Our cohort study revealed that the concentrations of PFOA, PFOS, PFNA and PFUA were higher in cord blood than in serum from eight-year-olds. Some trends were also noted between intrauterine PFOS exposure and children's decreasing FEV1, FVC and PEF, especially in subgroups with lower birth weight and allergic rhinitis. Therefore, intrauterine PFAS exposure, especially PFOS, may play a vital role in lung development.

Study Protocol for Preventing Early-Onset Pneumonia in Young Children Through Maternal Immunisation: A Multi-Centre Randomised Controlled Trial (PneuMatters)

Background: Preventing and/or reducing acute lower respiratory infections (ALRIs) in young children will lead to substantial short and long-term clinical benefits. While immunisation with pneumococcal conjugate vaccines (PCV) reduces paediatric ALRIs, its efficacy for reducing infant ALRIs following maternal immunisation has not been studied. Compared to other PCVs, the 10-valent pneumococcal-Haemophilus influenzae Protein D conjugate vaccine (PHiD-CV) is unique as it includes target antigens from two common lower airway pathogens, pneumococcal capsular polysaccharides and protein D, which is a conserved H. influenzae outer membrane lipoprotein. Aims: The primary aim of this randomised controlled trial (RCT) is to determine whether vaccinating pregnant women with PHiD-CV (compared to controls) reduces ALRIs in their infants' first year of life. Our secondary aims are to evaluate the impact of maternal PHiD-CV vaccination on different ALRI definitions and, in a subgroup, the infants' nasopharyngeal carriage of pneumococci and H. influenzae, and their immune responses to pneumococcal vaccine type serotypes and protein D. Methods: We are undertaking a parallel, multicentre, superiority RCT (1:1 allocation) at four sites across two countries (Australia, Malaysia). Healthy pregnant Australian First Nation or Malaysian women aged 17-40 years with singleton pregnancies between 27⁺⁶ and 34⁺⁶ weeks gestation are randomly assigned to receive either a single dose of PHiD-CV or usual care. Treatment allocation is concealed. Study outcome assessors are blinded to treatment arms. Our primary outcome is the rate of medically attended ALRIs by 12-months of age. Blood and nasopharyngeal swabs are collected from infants at birth, and at ages 6- and 12-months (in a subset). Our planned sample size (n = 292) provides 88% power (includes 10% anticipated loss to follow-up). Discussion: Results from this RCT potentially leads to prevention of early and recurrent ALRIs and thus preservation of lung health during the infant's vulnerable period when lung growth is maximum. The multicentre nature of our study increases the generalisability of its future findings and is complemented by assessing the microbiological and immunological outcomes in a subset of infants. Clinical Trial Registration: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374381, identifier: ACTRN12618000150246.

The impact of maternal protein restriction during perinatal life on the response to a septic insult in adult rats

Although abundant evidence exists that adverse events during pregnancy lead to chronic conditions, there is limited information on the impact of acute insults such as sepsis. This study tested the hypothesis that impaired fetal development leads to altered organ responses to a septic insult in both male and female adult offspring. Fetal growth restricted (FGR) rats were generated using a maternal protein-restricted diet. Male and female FGR and control diet rats were housed until 150-160 d of age when they were exposed either a saline (control) or a fecal slurry intraperitoneal (Sepsis) injection. After 6 h, livers and lungs were analyzed for inflammation and, additionally, the amounts and function of pulmonary surfactant were measured. The results showed increases in the steady-state mRNA levels of inflammatory cytokines in the liver in response to the septic insult in both males and females; these responses were not different between FGR and control diet groups. In the lungs, cytokines were not detectable in any of the experimental groups. A significant decrease in the relative amount of surfactant was observed in male FGR offspring, but this was not observed in control males or in female animals. Overall, it is concluded that FGR induced by maternal protein restriction does not impact liver and lung inflammatory response to sepsis in either male or female adult rats. An altered septic response in male FGR offspring with respect to surfactant may imply a contribution to lung dysfunction.

Prenatal and early-life exposure to the Great Chinese Famine increased the risk of tuberculosis in adulthood across two generations

Global food security is a major driver of population health, and food system collapse may have complex and long-lasting effects on health outcomes. We examined the effect of prenatal exposure to the Great Chinese Famine (1958-1962)-the largest famine in human history-on pulmonary tuberculosis (PTB) across consecutive generations in a major center of ongoing transmission in China. We analyzed >1 million PTB cases diagnosed between 2005 and 2018 in Sichuan Province using age-period-cohort analysis and mixed-effects metaregression to estimate the effect of the famine on PTB risk in the directly affected birth cohort (F1) and their likely offspring (F2). The analysis was repeated on certain sexually transmitted and blood-borne infections (STBBI) to explore potential mechanisms of the intergenerational effects. A substantial burden of active PTB in the exposed F1 cohort and their offspring was attributable to the Great Chinese Famine, with more than 12,000 famine-attributable active PTB cases (>1.23% of all cases reported between 2005 and 2018). An interquartile range increase in famine intensity resulted in a 6.53% (95% confidence interval [CI]: 1.19-12.14%) increase in the ratio of observed to expected incidence rate (incidence rate ratio, IRR) in the absence of famine in F1, and an 8.32% (95% CI: 0.59-16.6%) increase in F2 IRR. Increased risk of STBBI was also observed in F2. Prenatal and early-life exposure to malnutrition may increase the risk of active PTB in the exposed generation and their offspring, with the intergenerational effect potentially due to both within-household transmission and increases in host susceptibility.

Prenatal exposure to VOCs and NOx and lung function in preschoolers

BACKGROUND

Several studies have shown that exposure to air pollutants affects lung growth and development and can result in poor respiratory health in early life.

METHODS

We included a subsample of 772 Mexican preschoolers whose mothers participated in a Prenatal Omega-3 fatty acid Supplements, GRowth, And Development birth cohort study with the aim to evaluate the impact of prenatal exposure to volatile organic compounds and nitrogen oxides on lung function measured by oscillation tests. The preschoolers were followed until 5 years of age. Anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. Information on sociodemographic and health characteristics was obtained during follow up. Prenatal exposure to volatile organic compounds and nitrogen oxides was evaluated using a land use regression models and the association between them was tested using a lineal regression and longitudinal linear mixed effect models adjusting for potential confounders.

RESULTS

Overall, the mean (standard deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during the follow-up period was 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), and -4.6 hPa s L^-1 (1.6), respectively. We found a significantly positive association between respiratory resistance (β_Rrs6  = 0.011; 95%CI: 0.001, 0.023) (P < .05) and prenatal exposure to nitrogen dioxide and a marginally negatively association between respiratory reactance (β_Xrs6  = -11.40 95%CI: -25.26, 1.17 and β_Xrs8  = -11.91 95%CI: -26.51, 1.43) (P = .07) and prenatal exposure to xylene.

CONCLUSION

Prenatal exposure to air pollutants was significantly associated with the alteration of lung function measured by oscillation tests in these preschool children.

Advancing Therapeutic Development for Pulmonary Morbidities Associated with Preterm Birth

Chronic pulmonary and respiratory conditions associated with preterm birth are incompletely characterized, complicating long-term treatment and development of more effective therapies. Stakeholders face challenges in the development of validated, clinically meaningful endpoints that adequately measure morbidities and predict or represent health outcomes for preterm neonates. We propose in this paper a research agenda, informed by the input of experts from a 2018 workshop we convened on this topic, to advance endpoint and treatment development. We discuss the necessity of further evaluation of existing endpoints and the improved characterization of disease endotypes. We also discuss key steps to the development of optimized short- and long-term endpoints that can be linked to meaningful health outcomes. Finally, we discuss the importance of limiting variability in data collection and the application of new clinical trial endpoints as well as the critical nature of multi-stakeholder collaboration to advancing therapeutic development for this vulnerable patient population.

Early childhood malnutrition trajectory and lung function at preadolescence

OBJECTIVE

Chronic undernutrition is a common phenomenon in Bangladesh. However, information is grossly lacking to report the correlation between chronic undernutrition trajectory and lung function in children. The aim of the current study was to understand the association between early-childhood chronic undernutrition trajectory and lung function at preadolescence.

DESIGN

The current study is a part of the 9-year follow-up of a large-scale cohort study called the Maternal and Infant Nutrition Interventions in Matlab.

SETTINGS

The current study was conducted in Matlab, a sub-district area of Bangladesh that is located 53 km south of the capital, Dhaka.

PARTICIPANTS

A total of 517 children participated in lung function measured with a spirometer at the age of 9 years. Weight and height were measured at five intervals from birth till the age of 9 years.

RESULTS

Over half of the cohort have experienced a stunting undernutrition phenomenon up to 9 years of age. Children who were persistently or intermittently stunted showed lower forced expiratory volume (ml/s) than normal-stature children (P < 0·05). Children who exhibited catch-up growth throughout 4·5 years from the stunted group showed similar lung function with normal counterparts, and a better lung function than in children with the same growth velocity or who had faltering growth. In the multivariable models, similar associations were observed in children who experienced catch-up growth than their counterparts after adjusting for covariates.

CONCLUSION

Our data suggest that catch-up growth in height during early childhood is associated with a better lung function at preadolescence.

Hypertensive disorders of pregnancy and risk of asthma in offspring: protocol for a systematic review and meta-analysis

INTRODUCTION

Hypertensive disorders of pregnancy (HDP), one of the most common obstetrical complications, has been reported to have a controversial relationship with the increased risk of asthma in offspring. No systematic review of this topic has been performed. The aim of this systematic review will be to summarise the available evidence examining the association between HDP and the risk of asthma in offspring.

METHODS AND ANALYSIS

We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-analysis of Observational Studies in Epidemiology guidelines. A systematic search of the PubMed, Embase, Cochrane and Web of Science databases will be performed using a detailed search strategy from database inception through 31 December 2019. Cohort, case-control and cross-sectional studies that report a diagnosis of maternal HDP and asthma in offspring will be included. Studies will be limited to the English language and include only human participants. Two independent reviewers will conduct the study selection, data extraction and risk of bias assessments using a standardised data extraction form. A meta-analysis will be performed to calculate overall pooled estimates using the generic inverse variance method. The data will be synthesised by either fixed-effect or random effects models according to heterogeneity tests. All analyses will be performed in Stata 14 and RevMan 5.3. High-quality evidence of the relationship between HDP and the risk of asthma in exposed offspring will be identified through the synthesis of current studies. In addition, the results of subgroup analyses and related secondary outcomes will be reported. The following will be concluded: (i) whether HDP increases the risk of asthma in offspring, (ii) whether HDP affects the severity of asthma in exposed offspring and (iii) whether possible differences in the risk of asthma among different HDP subgroups exist.

ETHICS AND DISSEMINATION

There is no requirement for ethics approval because the meta-analysis and systematic review will be based on published data. It is anticipated that the dissemination of results will take place at conferences and through publication in a peer-reviewed journal.

Pulmonary Consequences of Prenatal Inflammatory Exposures: Clinical Perspective and Review of Basic Immunological Mechanisms

Chorioamnionitis, a potentially serious inflammatory complication of pregnancy, is associated with the development of an inflammatory milieu within the amniotic fluid surrounding the developing fetus. When chorioamnionitis occurs, the fetal lung finds itself in the unique position of being constantly exposed to the consequent inflammatory meditators and/or microbial products found in the amniotic fluid. This exposure results in significant changes to the fetal lung, such as increased leukocyte infiltration, altered cytokine, and surfactant production, and diminished alveolarization. These alterations can have potentially lasting impacts on lung development and function. However, studies to date have only begun to elucidate the association between such inflammatory exposures and lifelong consequences such as lung dysfunction. In this review, we discuss the pathogenesis of and fetal immune response to chorioamnionitis, detail the consequences of chorioamnionitis exposure on the developing fetal lung, highlighting the various animal models that have contributed to our current understanding and discuss the importance of fetal exposures in regard to the development of chronic respiratory disease. Finally, we focus on the clinical, basic, and therapeutic challenges in fetal inflammatory injury to the lung, and propose next steps and future directions to improve our therapeutic understanding of this important perinatal stress.

No. 364-Antenatal Corticosteroid Therapy for Improving Neonatal Outcomes

OBJECTIVE

To assess the benefits and risks of antenatal corticosteroid therapy for women at risk of preterm birth or undergoing pre-labour Caesarean section at term and to make recommendations for improving neonatal and long-term outcomes.

OPTIONS

To administer or withhold antenatal corticosteroid therapy for women at high risk of preterm birth or women undergoing pre-labour Caesarean section at term.

OUTCOMES

Perinatal morbidity, including respiratory distress syndrome, intraventricular hemorrhage, bronchopulmonary dysplasia, infection, hypoglycemia, somatic and brain growth, and neurodevelopment; perinatal mortality; and maternal morbidity, including infection and adrenal suppression.

INTENDED USERS

Maternity care providers including midwives, family physicians, and obstetricians.

TARGET POPULATION

Pregnant women.

EVIDENCE

Medline, PubMed, Embase, and the Cochrane Library were searched from inception to September 2017. Medical Subject Heading (MeSH) terms and key words related to pregnancy, prematurity, corticosteroids, and perinatal and neonatal mortality and morbidity were used. Statements from professional organizations including that of the National Institutes of Health, the American College of Obstetricians and Gynecologists, the Society for Maternal Fetal Medicine, the Royal College of Obstetricians and Gynaecologists, and the Canadian Pediatric Society were reviewed for additional references. Randomized controlled trials conducted in pregnant women evaluating antenatal corticosteroid therapy and previous systematic reviews on the topic were eligible. Evidence from systematic reviews of non-experimental (cohort) studies was also eligible.

VALIDATION METHODS

This Committee Opinion has been reviewed and approved by the Maternal-Fetal Medicine Committee of the SOGC and approved by SOGC Council.

BENEFITS, HARMS, AND/OR COSTS

A course of antenatal corticosteroid therapy administered within 7 days of delivery significantly reduces perinatal morbidity/mortality associated with preterm birth between 24 + 0 and 34 + 6 weeks gestation. When antenatal corticosteroid therapy is given more than 7 days prior to delivery or after 34 + 6 weeks gestation, the adverse effects may outweigh the benefits. Evidence on long-term effects is scarce, and potential neurodevelopment harms are unquantified in cases of late preterm, term, and repeated exposure to antenatal corticosteroid therapy.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to evaluate the need for a complete or partial update of the guideline. If important evidence is published prior to the 5-year time point, an update will be issued to reflect new knowledge and recommendations.

SPONSORS

The guideline was developed with resources provided by the Society of Obstetricians and Gynaecologists of Canada with support from the Canadian Institutes of Health Research (APR-126338).

SUMMARY STATEMENTS

RECOMMENDATIONS: Gestational Age Considerations Agents, Dosage, Regimen, and Target Timing Subpopulations and Special Consideration.

Maternal protein restriction during perinatal life affects lung mechanics and the surfactant system during early postnatal life in female rats

Limited information is available on how fetal growth retardation (FGR) affects the lung in the neonatal period in males and females. This led us to test the hypothesis that FGR alters lung mechanics and the surfactant system during the neonatal period. To test this hypothesis a model of FGR was utilized in which pregnant rat dams were fed a low protein diet during both the gestation and lactation period. We subsequently analyzed lung mechanics using a FlexiVent ventilator in male and female pups at postnatal day 7 and 21. Lung lavage material was obtained at postnatal day 1, 7 and 21, and was used for analysis of the surfactant system which included measurement of the pool size of surfactant and its subfraction as well as the surface tension reducing ability of the surfactant. The main result of the study was a significantly lower lung compliance and higher tissue elastance which was observed in FGR female offspring at day 21 compared to control offspring. In addition, female LP offspring exhibited lower surfactant pool sizes at postnatal day 1compared to controls. These changes were not observed in the male offspring. It is concluded that FGR has a different impact on pulmonary function and on surfactant in female, as compared to male, offspring.

Impacts of high temperature on adverse birth outcomes in Seoul, Korea: Disparities by individual- and community-level characteristics

BACKGROUND

Few studies have examined temperature's effect on adverse birth outcomes and relevant effect modifiers.

OBJECTIVES

We investigated associations between heat and adverse birth outcomes and how individual and community characteristics affect these associations for Seoul, Korea, 2004-2012.

METHODS

We applied logistic regression to estimate associations between heat index during pregnancy, 4 weeks before delivery, and 1 week before delivery and risk of preterm birth and term low birth weight. We investigated effect modification by individual (infant's sex, mother's age, and mother's educational level) and community characteristics (socioeconomic status (SES) and percentage of green areas near residence at the gu level, which is similar to borough in Western countries). We also evaluated associations by combinations of individual- and community-level SES.

RESULTS

Heat exposure during whole pregnancy was significantly associated with risk of preterm birth. An interquartile (IQR) increase (5.5 °C) in heat index during whole pregnancy was associated with an odds ratio (OR) of 1.033 (95% CI 1.005, 1.061) with NO2 adjustment, and 1.028 (95% CI 0.998, 1.059) with PM10 adjustment, for preterm birth. We also found significant associations with heat exposure during 4 weeks before delivery and 1 week before delivery on preterm birth. We did not observe significant associations with term low birth weight. Higher risk of heat on preterm birth was associated with some individual characteristics such as infants with younger or older mothers and lower community-level SES. For combinations of individual- and community-level SES, the highest and most significant estimated effect was found for infants with low educated mothers living in low SES communities, with suggestions of effects of both individual-and community-level SES.

CONCLUSIONS

Our findings have implications for evaluating impacts of high temperatures on birth outcomes, estimating health impacts of climate change, and identifying which subpopulations and factors are most relevant for disparities in this association.

Bronchiectasis

Bronchiectasis refers to abnormal dilatation of the bronchi. Airway dilatation can lead to failure of mucus clearance and increased risk of infection. Pathophysiological mechanisms of bronchiectasis include persistent bacterial infections, dysregulated immune responses, impaired mucociliary clearance and airway obstruction. These mechanisms can interact and self-perpetuate, leading over time to impaired lung function. Patients commonly present with productive cough and recurrent chest infections, and the diagnosis of bronchiectasis is based on clinical symptoms and radiological findings. Bronchiectasis can be the result of several different underlying disorders, and identifying the aetiology is crucial to guide management. Treatment is directed at reducing the frequency of exacerbations, improving quality of life and preventing disease progression. Although no therapy is licensed for bronchiectasis by regulatory agencies, evidence supports the effectiveness of airway clearance techniques, antibiotics and mucolytic agents, such as inhaled isotonic or hypertonic saline, in some patients. Bronchiectasis is a disabling disease with an increasing prevalence and can affect individuals of any age. A major challenge is the application of emerging phenotyping and endotyping techniques to identify the patient populations who would most benefit from a specific treatment, with the goal of better targeting existing and emerging treatments and achieving better outcomes.

As Long as the Breath Lasts: In Utero Exposure to Ramadan and the Occurrence of Wheezing in Adulthood

While prenatal exposure to Ramadan has been shown to be negatively associated with general physical and mental health, studies on specific organs remain scarce. In this study, we explored whether Ramadan exposure during pregnancy affects the occurrence of wheezing, a main symptom of obstructive airway disease. Using data from the Indonesian Family Life Survey collected between 1997 and 2008 (waves 2-4), we compared wheezing occurrence among adult Muslims who had been in utero during Ramadan with that in adult Muslims who had not been in utero during Ramadan. Wheezing prevalence was higher among adult Muslims who had been in utero during Ramadan, independent of the pregnancy phase in which the exposure to Ramadan occurred. Moreover, this association tended to increase with age, being strongest among those aged about 45 years or older. This is in line with fetal programming theory, suggesting that impacts of in utero exposures often manifest only after reproductive age. Particularly strong associations were detected for smokers. The respiratory system of prenatally exposed Muslims thus seems to perform worse in mitigating later ex utero harmful influences such as smoking. This study suggests that exposure to Ramadan during pregnancy may have lasting consequences for adult lung functionality.

Bronchiectasis in children: diagnosis and treatment

Bronchiectasis is conventionally defined as irreversible dilatation of the bronchial tree. Bronchiectasis unrelated to cystic fibrosis is an increasingly appreciated cause of chronic respiratory-related morbidity worldwide. Few randomised controlled trials provide high-level evidence for management strategies to treat the children affected by bronchiectasis. However, both decades-old and more recent studies using technological advances support the notion that prompt diagnosis and optimal management of paediatric bronchiectasis is particularly important in early childhood. Although considered to be of a non-reversible nature, mild bronchiectasis determined by radiography might be reversible at any age if treated early, and the lung function decline associated with disease progression could then be halted. Although some management strategies are extrapolated from cystic fibrosis or adult-based studies, or both, non-cystic fibrosis paediatric-specific data to help diagnose and manage these children still need to be generated. We present current knowledge and an updated definition of bronchiectasis, and review controversies relating to the management of children with bronchiectasis, including applying the concept of so-called treatable traits.

N° 364 - La Corticothérapie Prénatale Pour Améliorer Les Issues Néonatales

OBJECTIF

Évaluer les avantages et les risques de la corticothérapie prénatale chez les femmes qui présentent un risque d'accouchement prématuré ou qui subissent une césarienne à terme avant début de travail, et formuler des recommandations visant l'amélioration des issues néonatales et des issues à long terme.

OPTIONS

Administrer ou ne pas administrer une corticothérapie prénatale aux femmes qui présentent un risque élevé d'accouchement prématuré ou qui subissent une césarienne avant travail à terme. RéSULTATS: Morbidité périnatale, notamment le syndrome de détresse respiratoire, l'hémorragie intraventriculaire, la dysplasie bronchopulmonaire, l'infection, l'hypoglycémie, ainsi que les troubles de la croissance somatique et cérébrale et du neurodéveloppement; mortalité périnatale; et morbidité maternelle, notamment l'infection et la suppression surrénalienne.

UTILISATEURS CIBLES

Fournisseurs de soins de maternité, notamment les sages-femmes, les médecins de famille et les obstétriciens.

POPULATION CIBLE

Femmes enceintes. ÉVIDENCE: Nous avons interrogé les bases de données Medline, PubMed et Embase ainsi que la Bibliothèque Cochrane, de leur création au mois de septembre 2017. Nous nous sommes servis de Medical Subjet Headings (MeSH) et de mots clés en lien avec la grossesse, la prématurité, les corticostéroïdes ainsi que la mortalité et la morbidité périnatales et néonatales. Nous avons également consulté les déclarations d'organismes professionnels tels que les National Institutes of Health, l'American College of Obstetricians and Gynecologists, la Society for Maternal-Fetal Medicine, le Royal College of Obstetricians and Gynaecologists et la Société canadienne de pédiatrie pour obtenir des références additionnelles. Les essais cliniques randomisés évaluant la corticothérapie prénatale menés sur des femmes enceintes et les revues systématiques antérieures sur le sujet étaient admissibles, tout comme les données venant de revues systématiques d'études non expérimentales (études de cohorte).

VALEURS

La présente opinion de comité a été révisée et approuvée par le Comité de médecine fœto-maternelle de la SOGC, et approuvée par le Conseil de la SOGC. AVANTAGES, INCONVéNIENTS ET COûTS: L'administration d'une corticothérapie prénatale dans les sept jours précédant l'accouchement réduit significativement la morbidité et la mortalité périnatales associées à la naissance prématurée survenant entre 24+0 et 34+6 semaines de grossesse. Si la corticothérapie prénatale est administrée plus de sept jours avant l'accouchement ou après 34+6 semaines de grossesse, les effets indésirables peuvent surpasser les avantages. Les données probantes sur l'impact à long terme de la corticothérapie prénatale sont rares. Par ailleurs, les effets neurodéveloppementaux néfastes potentiels de l'exposition répétée à la corticothérapie prénatale ou de l'administration de corticostéroïdes en période préterme tardive ou à terme n'ont pas été quantifiés. MIS-à-JOUR à LA DIRECTIVE: Une revue des données probantes sera menée cinq ans après la publication de la présente directive clinique afin d'évaluer si une mise à jour complète ou partielle s'impose. Si de nouvelles données probantes importantes sont publiées avant la fin de ces cinq ans, une mise à jour tenant compte des nouvelles connaissances et recommandations sera publiée.

COMMANDITAIRES

La présente directive clinique a été élaborée à l'aide de ressources fournies par la Société des obstétriciens et gynécologues du Canada et avec l'appui des Instituts de recherche en santé du Canada (APR-126338). MOTS CLéS: Corticothérapie prénatale, maturation fœtale, prématurité, période préterme tardive, césarienne avant travail DÉCLARATION SOMMAIRES: RECOMMANDATIONS: Considérations relatives à l'âge gestationnel.

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.

Adolescent age is an independent risk factor for abnormal spirometry among people living with HIV in Kenya

OBJECTIVES

As life expectancy of people living with HIV (PLWH) improves in low-income and middle-income countries (LMICs), the spectrum of HIV-related pulmonary complications may reflect a greater burden of chronic lung diseases as in high-income countries. We determined whether the risk of abnormal spirometry was greater among adolescent compared with adult PLWH at the Coptic Hope Center for Infectious Diseases in Nairobi, Kenya, and evaluated the role of other cofactors for abnormal spirometry.

DESIGN

We prospectively enrolled adolescent and adult PLWH for this cross-sectional study.

METHODS

Data collection included standardized questionnaires, clinical assessment, and prebronchodilator and postbronchodilator spirometry. Adolescents additionally underwent noncontrast chest computed tomography. Multivariable logistic regression determined associations of adolescent age with abnormal spirometry, adjusting for cofactors.

RESULTS

Of 427 PLWH, 21 (40%) adolescents and 64 (17%) adults had abnormal spirometry. Among adolescents, 80% had abnormal chest CTs, and 79% had at least one respiratory symptom. Adolescent age (adjusted odds ratio 3.22; 95% confidence interval 1.48-6.98) was independently associated with abnormal spirometry, adjusting for recent CD4, HIV clinical stage, low BMI, indoor kerosene use, smoking pack-years, and prior pulmonary tuberculosis. Additional important cofactors for abnormal spirometry included prior pulmonary tuberculosis (3.15; 1.70-5.58), kerosene use (1.77; 1.04-3.04) and smoking pack-years (1.05; 1.00-1.10). Adolescent age, prior pulmonary tuberculosis, and smoking pack-years were significantly associated with airflow limitation.

CONCLUSION

Adolescent age was independently associated with increased risk of abnormal spirometry, particularly airflow limitation. Studies to improve prevention, detection, and management of chronic lung disease across the lifespan among PLWH are needed in LMICs.

Impact of gestational nicotine exposure on intrauterine and fetal infection in a rodent model

We investigated the interaction between prenatal nicotine exposure and intrauterine infection using established rat models. Beginning at gestation day (GD) 6, dams were continuously infused with either saline or 6 mg/kg/day nicotine (Nic). At GD 14, dams received either sterile broth or 10⁵ colony-forming units Mycoplasma pulmonis (MP), resulting in four treatment groups: control (4 dams, 33 fetal units); MP only (5 dams, 55 fetal units); Nic only (5 dams, 61 fetal units), and Nic + MP (7 dams, 82 fetal units). At GD 18, nicotine exposure significantly increased (P ≤ 0.02) the percentage of amniotic fluids and fetuses infected by MP but did not impact colonization rates of maternal sites. Nicotine exposure significantly reduced the numbers of MP in the placenta required for high microbial loads (≥10⁴ color-changing units) in the amniotic fluid (P < 0.01). Fetal inflammatory response lesions were most extensive in the Nic only and Nic + MP groups (P < 0.0001). Control and MP only placentas were interleukin (IL)10-dominant, consistent with an M2/Th2 environment. Placentas exposed to nicotine shifted to a neutral environment, with equivalent levels of interferon gamma (IFNG) and IL10. Both IL6 and tumor necrosis factor (TNF) levels in amniotic fluid were highly elevated when both nicotine and infection were present. Our study suggests that prenatal exposure to nicotine increases the risk for intrauterine infection, lowers the infectious dose required to breach the placental barrier and infect the amniotic fluid and fetus, and alters the pathology and inflammatory profile associated with maternal and fetal sites.

Implication of Oxidative Stress in Fetal Programming of Cardiovascular Disease

Lifestyle and genetic background are well known risk factors of cardiovascular disease (CVD). A third contributing factor is suboptimal fetal development, due to nutrient or oxygen deprivation, placental insufficiency, or exposure to toxic substances. The fetus adapts to adverse intrauterine conditions to ensure survival; the immediate consequence is low birth weight (LBW) and the long-term effect is an increased susceptibility to develop CVD in adult life. This process is known as Developmental Origins of Health and Disease (DOHaD) or fetal programming of CVD. The influence of fetal life for the future cardiovascular health of the individual has been evidenced by numerous epidemiologic studies in populations suffering from starvation during intrauterine life. Furthermore, experimental animal models have provided support and enabled exploring the underlying mechanisms. Oxidative stress seems to play a central role in fetal programming of CVD, both in the response of the feto-placental unit to the suboptimal intrauterine environment and in the alterations of physiologic systems of cardiovascular control, ultimately leading to disease. This review aims to summarize current knowledge on the alterations in oxidative balance in response to fetal stress factors covering two aspects. Firstly, the evidence from human studies of the implication of oxidative stress in LBW induced by suboptimal conditions during intrauterine life, emphasizing the role of the placenta. In the second part we summarize data on specific redox alterations in key cardiovascular control organs induced by exposure to known stress factors in experimental animals and discuss the emerging role of the mitochondria.

Effect of omega-3 fatty acids supplementation during pregnancy on lung function in preschoolers: a clinical trial

RATIONALE

Prenatal omega-3 fatty acids improve alveolarization, diminish inflammation, and improve pulmonary growth, but it is unclear whether these outcomes translate into improved postnatal lung function.

OBJECTIVE

We assessed the effect of prenatal supplementation with docosahexaenoic acid (DHA) on offspring lung function through 60 months of age.

METHODS

We included a cohort of 772 Mexican preschoolers whose mothers participated in a clinical trial (NCT00646360) of supplementation with DHA or a placebo from week 18-22 of gestation through delivery.

MEASUREMENTS

The children were followed after birth and anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. The effect of DHA was tested using a longitudinal mixed effect models.

RESULTS

Overall, mean (Standard Deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during follow up period were 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), -4.6 (1.6), respectively. There were no significant differences in pulmonary function by treatment group. DHA did not affect the average lung function or the trajectories through 60 months.

CONCLUSIONS

Prenatal DHA supplementation did not influence pulmonary function in this cohort of Mexican preschoolers.

Maternal hemoglobin and hematocrit levels during pregnancy and childhood lung function and asthma. The Generation R Study

OBJECTIVE

To examine the associations of maternal hemoglobin and hematocrit levels during pregnancy with childhood lung function and asthma, and whether adverse pregnancy outcomes and atopic predisposition modify the associations.

METHODS

In a population-based prospective cohort study among 3672 subjects, we measured maternal hemoglobin and hematocrit levels in early pregnancy, and lung function by spirometry and current asthma by questionnaire at age 10 years.

RESULTS

Higher maternal hematocrit levels, both continuously and categorized into clinical cut-offs, were associated with lower forced expiratory flow at 75% of forced vital capacity (FEF₇₅ ) in children (Z-score (95%CI): -0.04 (-0.07, -0.01), per increase of 1 SDS in hematocrit level; Z-score (95%CI) difference: -0.11 (-0.20, -0.03) compared with normal hematocrit levels, respectively), taking lifestyle and socio-economic factors into account. Adverse pregnancy outcomes and atopic predisposition did not modify the results. No associations of maternal hemoglobin and hematocrit with current asthma were observed.

CONCLUSION

Higher maternal hematocrit levels during pregnancy are associated with lower childhood lung function but not with risk of asthma. Adverse pregnancy outcomes and atopic predisposition do not modify these associations. Underlying mechanisms need to be further studied.

Effects of air pollution on infant and children respiratory mortality in four large Latin-American cities

OBJECTIVES

Air pollution is an important public health concern especially for children who are particularly susceptible. Latin America has a large children population, is highly urbanized and levels of pollution are substantially high, making the potential health impact of air pollution quite large. We evaluated the effect of air pollution on children respiratory mortality in four large urban centers: Mexico City, Santiago, Chile, and Sao Paulo and Rio de Janeiro in Brazil.

METHODS

Generalized Additive Models in Poisson regression was used to fit daily time-series of mortality due to respiratory diseases in infants and children, and levels of PM₁₀ and O₃. Single lag and constrained polynomial distributed lag models were explored. Analyses were carried out per cause for each age group and each city. Fixed- and random-effects meta-analysis was conducted in order to combine the city-specific results in a single summary estimate.

RESULTS

These cities host nearly 43 million people and pollution levels were above the WHO guidelines. For PM₁₀ the percentage increase in risk of death due to respiratory diseases in infants in a fixed effect model was 0.47% (0.09-0.85). For respiratory deaths in children 1-5 years old, the increase in risk was 0.58% (0.08-1.08) while a higher effect was observed for lower respiratory infections (LRI) in children 1-14 years old [1.38% (0.91-1.85)]. For O₃, the only summarized estimate statistically significant was for LRI in infants. Analysis by season showed effects of O₃ in the warm season for respiratory diseases in infants, while negative effects were observed for respiratory and LRI deaths in children.

DISCUSSION

We provided comparable mortality impact estimates of air pollutants across these cities and age groups. This information is important because many public policies aimed at preventing the adverse effects of pollution on health consider children as the population group that deserves the highest protection.

Normalisation of surfactant protein -A and -B expression in the lungs of low birth weight lambs by 21 days old

Intrauterine growth restriction (IUGR) induced by placental restriction (PR) in the sheep negatively impacts lung and pulmonary surfactant development during fetal life. Using a sheep model of low birth weight (LBW), we found that there was an increase in mRNA expression of surfactant protein (SP)-A, -B and -C in the lung of LBW lambs but no difference in the protein expression of SP-A or -B. LBW also resulted in increased lysosome-associated membrane glycoprotein (LAMP)-3 mRNA expression, which may indicate an increase in either the density of type II Alveolar epithelial cells (AEC) or maturity of type II AECs. Although there was an increase in glucocorticoid receptor (GR) and 11β-hydroxysteroid dehydrogenase (11βHSD)-1 mRNA expression in the lung of LBW lambs, we found no change in the protein expression of these factors, suggesting that the increase in SP mRNA expression is not mediated by increased GC signalling in the lung. The increase in SP mRNA expression may, in part, be mediated by persistent alterations in hypoxia signalling as there was an increase in lung HIF-2α mRNA expression in the LBW lamb. The changes in the hypoxia signalling pathway that persist within the lung after birth may be involved in maintaining SP production in the LBW lamb.

Early pregnancy intrauterine fetal exposure to maternal smoking and impact on fetal telomere length

BACKGROUND

Reduced telomere length, or its accelerated attrition, has been implicated in aging, mortality, and several human diseases, including respiratory diseases. Age dependent manifestation of telomere-mediated disease during life span indicates the role of developmental stage in these diseases and highlights the importance of fetal developmental process in utero and at earlier life stages. Environmental determinants during developmental and later stages of life could affect telomere length. Smoke exposure as one of these significant determinants have been investigated in association with telomere length in neonates at time of delivery, children and adults.

OBJECTIVE

We sought to investigate whether intrauterine fetal exposure to tobacco smoking characterized by placenta cotinine levels during early weeks of pregnancy might be associated with shorter relative telomere length (T/S ratio) as compared to fetuses without exposure to tobacco smoking.

STUDY DESIGN

207 Human placenta and epithelial lung samples were used for both fetal lung telomere length assessment and measurement of placental cotinine levels. Tissues were obtained from two NICHD-supported tissue retrieval programs with registries for elective abortions, the University of Washington Center for Birth Defects Research (Seattle, WA) and the University of Maryland Brain and Tissue Bank for Developmental Disorders (Baltimore, MD). Cotinine levels (ng/g total placental tissue) were determined in whole cell extracts prepared from human placenta samples to characterize and confirm the cotinine exposure status associated with maternal smoking. Relative telomere length (T/S ratio) in genomic DNA extracted from fetal lung tissue was measured by use of quantitative real-time polymerase chain reaction. Multivariable linear regression was used to investigate the relationship between fetal Telomere-to-Single Copy (T/S) ratio and tobacco exposure.

RESULTS

The estimated post-conception ages for included samples in the study ranged from 54 to 137days (7-19 weeks of gestation); 47.37% of fetal samples had female sex. Of the samples included in the analysis 96 and 111 fetal samples with and without intrauterine tobacco smoking exposure were distinguished. While T/S ratio was not different between those with and without smoking exposure (1.24±0.41 and 1.27±0.48, respectively; P=0.70), a significant effect modification of post-conception age on the relationship of intrauterine smoke exposure on fetal T/S ratio was observed (adjusted coefficient=-0.008, 95% CI: -0.016, -0.0004). The smoke exposure status was associated with T/S ratio after 93-day post conception (adjusted coefficient=-0.29, 95% CI: -0.53, -0.052).

CONCLUSIONS

Our results demonstrate a significant association of smoke exposure in utero at early pregnancy with shortened fetal relative telomere length in the developing lung and suggest that the detrimental effect of smoking exposure on future disease sequelae may start at the early stages of pregnancy.

miR-29b supplementation decreases expression of matrix proteins and improves alveolarization in mice exposed to maternal inflammation and neonatal hyperoxia

Even with advances in the care of preterm infants, chronic lung disease or bronchopulmonary dysplasia (BPD) continues to be a significant pulmonary complication. Among those diagnosed with BPD, a subset of infants develop severe BPD with disproportionate pulmonary morbidities. In addition to decreased alveolarization, these infants develop obstructive and/or restrictive lung function due to increases in or dysregulation of extracellular matrix proteins. Analyses of plasma obtained from preterm infants during the first week of life indicate that circulating miR-29b is suppressed in infants that subsequently develop BPD and that decreased circulating miR-29b is inversely correlated with BPD severity. Our mouse model mimics the pathophysiology observed in infants with severe BPD, and we have previously reported decreased pulmonary miR-29b expression in this model. The current studies tested the hypothesis that adeno-associated 9 (AAV9)-mediated restoration of miR-29b in the developing lung will improve lung alveolarization and minimize the deleterious changes in matrix deposition. Pregnant C3H/HeN mice received an intraperitoneal LPS injection on embryonic day 16 and newborn pups were exposed to 85% oxygen from birth to 14 days of life. On postnatal day 3, AAV9-miR-29b or AAV9-control was administered intranasally. Mouse lung tissues were then analyzed for changes in miR-29 expression, alveolarization, and matrix protein levels and localization. Although only modest improvements in alveolarization were detected in the AAV9-miR29b-treated mice at postnatal day 28, treatment completely attenuated defects in matrix protein expression and localization. Our data suggest that miR-29b restoration may be one component of a novel therapeutic strategy to treat or prevent severe BPD in prematurely born infants.

Bronchopulmonary Dysplasia and Perinatal Characteristics Predict 1-Year Respiratory Outcomes in Newborns Born at Extremely Low Gestational Age: A Prospective Cohort Study

OBJECTIVE

To assess the utility of clinical predictors of persistent respiratory morbidity in extremely low gestational age newborns (ELGANs).

STUDY DESIGN

We enrolled ELGANs (<29 weeks' gestation) at ≤7 postnatal days and collected antenatal and neonatal clinical data through 36 weeks' postmenstrual age. We surveyed caregivers at 3, 6, 9, and 12 months' corrected age to identify postdischarge respiratory morbidity, defined as hospitalization, home support (oxygen, tracheostomy, ventilation), medications, or symptoms (cough/wheeze). Infants were classified as having postprematurity respiratory disease (PRD, the primary study outcome) if respiratory morbidity persisted over ≥2 questionnaires. Infants were classified with severe respiratory morbidity if there were multiple hospitalizations, exposure to systemic steroids or pulmonary vasodilators, home oxygen after 3 months or mechanical ventilation, or symptoms despite inhaled corticosteroids. Mixed-effects models generated with data available at 1 day (perinatal) and 36 weeks' postmenstrual age were assessed for predictive accuracy.

RESULTS

Of 724 infants (918 ± 234 g, 26.7 ± 1.4 weeks' gestational age) classified for the primary outcome, 68.6% had PRD; 245 of 704 (34.8%) were classified as severe. Male sex, intrauterine growth restriction, maternal smoking, race/ethnicity, intubation at birth, and public insurance were retained in perinatal and 36-week models for both PRD and respiratory morbidity severity. The perinatal model accurately predicted PRD (c-statistic 0.858). Neither the 36-week model nor the addition of bronchopulmonary dysplasia to the perinatal model improved accuracy (0.856, 0.860); c-statistic for BPD alone was 0.907.

CONCLUSION

Both bronchopulmonary dysplasia and perinatal clinical data accurately identify ELGANs at risk for persistent and severe respiratory morbidity at 1 year.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01435187.

Oxidative injury of the pulmonary circulation in the perinatal period: Short- and long-term consequences for the human cardiopulmonary system

Development of the pulmonary circulation is a complex process with a spatial pattern that is tightly controlled. This process is vulnerable for disruption by various events in the prenatal and early postnatal periods. Disruption of normal pulmonary vascular development leads to abnormal structure and function of the lung vasculature, causing neonatal pulmonary vascular diseases. Premature babies are especially at risk of the development of these diseases, including persistent pulmonary hypertension and bronchopulmonary dysplasia. Reactive oxygen species play a key role in the pathogenesis of neonatal pulmonary vascular diseases and can be caused by hyperoxia, mechanical ventilation, hypoxia, and inflammation. Besides the well-established short-term consequences, exposure of the developing lung to injurious stimuli in the perinatal period, including oxidative stress, may also contribute to the development of pulmonary vascular diseases later in life, through so-called "fetal or perinatal programming." Because of these long-term consequences, it is important to develop a follow-up program tailored to adolescent survivors of neonatal pulmonary vascular diseases, aimed at early detection of adult pulmonary vascular diseases, and thereby opening the possibility of early intervention and interfering with disease progression. This review focuses on pathophysiologic events in the perinatal period that have been shown to disrupt human normal pulmonary vascular development, leading to neonatal pulmonary vascular diseases that can extend even into adulthood. This knowledge may be particularly important for ex-premature adults who are at risk of the long-term consequences of pulmonary vascular diseases, thereby contributing disproportionately to the burden of adult cardiovascular disease in the future.

Infants' indoor and outdoor residential exposure to benzene and respiratory health in a Spanish cohort

Benzene exposure represents a potential risk for children's health. Apart from being a known carcinogen for humans (group 1 according to IARC), there is scientific evidence suggesting a relationship between benzene exposure and respiratory problems in children. But results are still inconclusive and inconsistent. This study aims to assess the determinants of exposure to indoor and outdoor residential benzene levels and its relationship with respiratory health in infants. Participants were 1-year-old infants (N = 352) from the INMA cohort from Valencia (Spain). Residential benzene exposure levels were measured inside and outside dwellings by means of passive samplers in a 15-day campaign. Persistent cough, low respiratory tract infections and wheezing during the first year of life, and covariates (dwelling traits, lifestyle factors and sociodemographic data) were obtained from parental questionnaires. Multiple Tobit regression and logistic regression models were performed to assess factors associated to residential exposure levels and health associations, respectively. Indoor levels were higher than outdoor ones (1.46 and 0.77 μg/m³, respectively; p < 0.01). A considerable percentage of dwellings, 42% and 21% indoors and outdoors respectively, surpassed the WHO guideline of 1.7 μg/m³ derived from a lifetime risk of leukemia above 1/100 000. Monitoring season, maternal country of birth and parental tobacco consumption were associated with residential benzene exposure (indoor and outdoors). Additionally, indoor levels were associated with mother's age and type of heating, and outdoor levels were linked with zone of residence and distance from industrial areas. After adjustment for confounding factors, no significant associations were found between residential benzene exposure levels and respiratory health in infants. Hence, our study did not support the hypothesis for the benzene exposure effect on respiratory health in children. Even so, it highlights a public health concern related to the personal exposure levels, since a considerable number of children surpassed the abovementioned WHO guideline for benzene exposure.

Airway remodeling in asthma: what really matters

Airway remodeling is generally quite broadly defined as any change in composition, distribution, thickness, mass or volume and/or number of structural components observed in the airway wall of patients relative to healthy individuals. However, two types of airway remodeling should be distinguished more clearly: (1) physiological airway remodeling, which encompasses structural changes that occur regularly during normal lung development and growth leading to a normal mature airway wall or as an acute and transient response to injury and/or inflammation, which ultimately results in restoration of a normal airway structures; and (2) pathological airway remodeling, which comprises those structural alterations that occur as a result of either disturbed lung development or as a response to chronic injury and/or inflammation leading to persistently altered airway wall structures and function. This review will address a few major aspects: (1) what are reliable quantitative approaches to assess airway remodeling? (2) Are there any indications supporting the notion that airway remodeling can occur as a primary event, i.e., before any inflammatory process was initiated? (3) What is known about airway remodeling being a secondary event to inflammation? And (4), what can we learn from the different animal models ranging from invertebrate to primate models in the study of airway remodeling? Future studies are required addressing particularly pheno-/endotype-specific aspects of airway remodeling using both endotype-specific animal models and “endotyped” human asthmatics. Hopefully, novel in vivo imaging techniques will be further advanced to allow monitoring development, growth and inflammation of the airways already at a very early stage in life.

[Methods for establishing animal model of bronchopulmonary dysplasia and their evaluation]

With the development of treatment, the survival rate of premature infants has significantly increased, especially extremely premature infants and very low birth weight infants. This has led to an increase in incidence of bronchopulmonary dysplasia (BPD) year by year. BPD has been one of the most common respiratory system diseases in premature infants, especially the small premature infants. Arrested alveolar development is an important cause of BPD. Therefore, the mechanism of arrested alveolar development and the intervention measures for promoting alveolar development are the focuses of research on BPD. Selecting the appropriate animal model of BPD is the key to obtaining meaningful results in the basic research on BPD. Based on above, several common methods for establishing an animal model of BPD and the corresponding changes in pathophysiology are summarized and evaluated in order to provide a reference for selecting the appropriate animal model in studies on the pathogenesis, pathophysiology, and prevention and control strategies of BPD.

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

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