Vitamin C supplementation for pregnant smoking women and pulmonary function in their newborn infants: a randomized clinical trial

Prenatal Origins of Obstructive Airway Disease: Starting on the Wrong Trajectory?

From the results of well-performed population health studies, we now have excellent data demonstrating that deficits in adult lung function may be present early in life, possibly as a result of developmental disorders, incurring a lifelong risk of obstructive airway diseases such as asthma and chronic obstructive pulmonary disease. Suboptimal fetal development results in intrauterine growth restriction and low birth weight at term (an outcome distinct from preterm complications), which are associated with subsequent obstructive disease. Numerous prenatal exposures and disorders compromise fetal development and these are summarized herein. Various physiological, structural, and mechanical abnormalities may result from prenatal disruption, including changes to airway smooth muscle structure-function, goblet cell biology, airway stiffness, geometry of the bronchial tree, lung parenchymal structure and mechanics, respiratory skeletal muscle contraction, and pulmonary inflammation. The literature therefore supports the need for early life intervention to prevent or correct growth defects, which may include simple nutritional or antioxidant therapy. © 2024 American Physiological Society. Compr Physiol 14:5729-5762, 2024.

Vitamin C supplementation improves placental function and alters placental gene expression in smokers

Maternal smoking during pregnancy (MSDP), driven by nicotine crossing the placenta, causes lifelong decreases in offspring pulmonary function and vitamin C supplementation during pregnancy prevents some of those changes. We have also shown in animal models of prenatal nicotine exposure that vitamin C supplementation during pregnancy improves placental function. In this study we examined whether vitamin C supplementation mitigates the effects of MSDP on placental structure, function, and gene expression in pregnant human smokers. Doppler ultrasound was performed in a subset of 55 pregnant smokers participating in the "Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function" (VCSIP) randomized clinical trial (NCT01723696) and in 33 pregnant nonsmokers. Doppler ultrasound measurements showed decreased umbilical vein Doppler velocity (Vmax) in placebo-treated smokers that was significantly improved in smokers randomized to vitamin C, restoring to levels comparable to nonsmokers. RNA-sequencing demonstrated that vitamin C supplementation to pregnant smokers was associated with changes in mRNA expression in genes highly relevant to vascular and cardiac development, suggesting a potential mechanism for vitamin C supplementation in pregnant smokers to improve some aspects of offspring health.

Presurgical pulmonary function tests in the first few days of life in neonates with congenital heart disease, a pilot study

OBJECTIVE

To compare early pulmonary function tests (PFTs) in neonates with critical congenital heart disease (CHD) compared to a historical reference group.

DESIGN

Infants ≥ 37 weeks gestation with critical CHD were studied within the first few days of life, prior to cardiac surgery, and compared to data from a published reference group of healthy term neonates without CHD, studied at the same institution. Passive respiratory resistance (Rrs) and compliance (Crs) were measured with the single breath occlusion technique following specific acceptance criteria. The study was powered for a 30% difference in Rrs.

RESULTS

PFTs in 24 infants with CHD were compared to 31 historical reference infants. There was no difference in the Rrs between the groups. The infants with CHD had a significantly decreased Crs (1.02 ± 0.26 mL/cmH2O/kg versus 1.32 ± 0.36; (p < 0.05; mean ± SD)).

CONCLUSIONS

Further prospective studies are required to quantify early PFTs in infants with CHD of different phenotypes.

Effect of maternal cigarette smoke exposure on COPD progression in offspring mice

OBJECTIVE

To investigate the impact of maternal smoking on chronic obstructive pulmonary disease (COPD) progression in offspring.

METHODS

Using female C57BL/6 J mice, a maternal cigarette smoke exposure (CSE) model was established. Mice were exposed to cigarette smoke for 2 hours/day, 7 days/week, with a minimum 4-hour interval between exposures. Experimental groups included control (Con), pregnancy exposure (AS), pre-pregnancy exposure (SA), and pre-pregnancy + pregnancy exposure (SS). Lung function tests (Penh, PAU, TVb, EF50, Tr) were conducted on male offspring at 7 weeks. Histopathology, electron microscopy, and protein level changes were examined.

RESULTS

Lung function tests revealed significant impairments in Penh, PAU, TVb, EF50, and Tr in offspring across all exposure scenarios. Specifically, AS experienced significant lung function impairment and mitochondrial dysfunction in offspring, with noticeable pulmonary lesions and increased apoptosis. SA showed similar or even more severe lung function impairment and cellular apoptosis. SS exhibited the most pronounced effects, with the highest levels of lung dysfunction, mitochondrial damage, and apoptosis. Histopathological analysis showed pulmonary lesions in offspring exposed to maternal CSE. Flow cytometry revealed increased apoptosis and reduced mitochondrial membrane potential in offspring lung cells. Electron microscopy confirmed mitochondrial dysfunction. Upregulation of apoptotic proteins and downregulation of anti-apoptotic protein Bcl-2 were found in offspring lung tissue exposed to maternal CSE.

CONCLUSION

Maternal smoking induces impaired lung function, pulmonary lesions, and mitochondrial dysfunction in offspring, regardless of exposure timing and duration. Additionally, it alters expression of apoptosis-related proteins in offspring lung tissue, potentially contributing to COPD susceptibility.

Lung function trajectories from school age to adulthood and their relationship with markers of cardiovascular disease risk

RATIONALE

Lung function in early adulthood is associated with subsequent adverse health outcomes.

OBJECTIVES

To ascertain whether stable and reproducible lung function trajectories can be derived in different populations and investigate their association with objective measures of cardiovascular structure and function.

METHODS

Using latent profile modelling, we studied three population-based birth cohorts with repeat spirometry data from childhood into early adulthood to identify trajectories of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). We used multinomial logistic regression models to investigate early-life predictors of the derived trajectories. We then ascertained the extent of the association between the derived FEV1/FVC trajectories and blood pressure and echocardiographic markers of increased cardiovascular risk and stroke in ~3200 participants at age 24 years in one of our cohorts.

RESULTS

We identified four FEV1/FVC trajectories with strikingly similar latent profiles across cohorts (pooled N=6377): above average (49.5%); average (38.3%); below average (10.6%); and persistently low (1.7%). Male sex, wheeze, asthma diagnosis/medication and allergic sensitisation were associated with trajectories with diminished lung function in all cohorts. We found evidence of an increase in cardiovascular risk markers ascertained by echocardiography (including left ventricular mass indexed to height and carotid intima-media thickness) with decreasing FEV1/FVC (with p values for the mean crude effects per-trajectory ranging from 0.10 to p<0.001). In this analysis, we considered trajectories as a pseudo-continuous variable; we confirmed the assumption of linearity in all the regression models.

CONCLUSIONS

Childhood lung function trajectories may serve as predictors in the development of not only future lung disease, but also the cardiovascular disease and multimorbidity in adulthood.

Maternal use of snus as smokeless tobacco in pregnancy and infant lung function

Background

Smoking in pregnancy has detrimental effects on infant respiratory health, while the effects of other nicotine-containing products on infant lung function are unclear. We aimed to explore if smokeless tobacco such as snus used in pregnancy increased the risk of lower lung function in infancy and if the associations differed by sex.

Methods

From the Scandinavian population-based Preventing Atopic Dermatitis and ALLergies in Children birth cohort, we included 1163 infants with available tidal flow-volume measurements at 3 months of age and maternal self-reported use of nicotine-containing products in pregnancy. The risk of a ratio of time to peak tidal expiratory flow to total expiratory time <25th percentile by any nicotine exposure, snus exclusively and cigarette smoking with or without other nicotine-containing products was explored by regression analyses adjusting for maternal age, education and asthma.

Results

Overall 120 out of 1163 (10.3%) infants were exposed to any nicotine in utero, 71 out of 120 by snus exclusively and 49 out of 120 by smoking, with six also exposed to snus. By pregnancy week 6, 85.8% of mothers reported stopping nicotine use. The risk of lower lung function was higher in children exposed in utero to nicotine-containing products with an odds ratio (OR) of 1.63 (95% confidence interval (CI) 1.02-2.59) with a similar tendency for snus exclusively (OR 1.55, 95% CI 0.88-2.71) and smoking (OR 1.79, 0.84-3.84). Effect estimates were similar after adjusting for covariates. No differences of the effect by sex were observed.

Conclusion

Our study suggests that in utero exposure to not only cigarettes, but also snus, may negatively affect infant lung function.

Nicotine or marijuana vaping exposure during pregnancy and altered immune responses in offspring

Electronic nicotine delivery systems (ENDS) - which include electronic cigarettes or e-cigarettes, or simply e-cigs, and marijuana vaping have become increasingly popular. ENDS devices have been established as one of the tobacco quit methods and promoted to be safer compared to traditional tobacco cigarettes. Emerging evidence demonstrates that e-cigarette and marijuana vape use can be harmful, with potential associations with cancer. Herein, we summarize the level of evidence to date for altered immune response, with a focus on cancer risks in the offspring after maternal use of, or aerosol exposures from, ENDS or marijuana vape during pregnancy. From 27 published articles retrieved from PubMed, we sought to find out identified carcinogens in ENDS aerosols and marijuana vapor, which cross the placental barrier and can increase cancer risk in the offspring. Carcinogens in vaping aerosols include aldehydes, metals, tobacco-specific nitrosamines, tobacco alkaloids, polycyclic aromatic hydrocarbons, and volatile organic compounds. Additionally, there was only one passive vaping exposure case study on a human fetus, which noted that glycerol, aluminum, chromium, nickel, copper, zinc, selenium, and lead crossed from the mother to the offspring's cord blood. The carcinogens (metals) in that study were at lower concentrations compared to the mother's biological matrices. Lastly, we observed that in utero exposures to ENDS-associated chemicals can occur in vital organs such as the lungs, kidneys, brain, bladder, and heart. Any resulting DNA damage increases the risk of tumorigenesis. Future epidemiological studies are needed to examine the effects of passive aerosol exposures from existing and emerging electronic nicotine and marijuana products on developing offspring to cancer.

A meta-analysis of the effects of vitamin C supplementation for pregnant smokers on the pulmonary function of their offspring

BACKGROUND

At present, the need for vitamin C supplementation for pregnant smokers has not been fully studied. This study is aimed at investigating whether vitamin C supplementation for pregnant smoking women can improve the pulmonary function of their offspring.

METHODS

Four databases were searched from inception to April 1, 2023 for studies on the effect of vitamin C supplementation to pregnant smokers on the pulmonary function of their offspring. Meanwhile, the reference lists of relevant studies were manually searched. The risk of bias in the included studies was assessed using the Cochrane Collaboration tool, and the data was analyzed using STATA/SE 17.0.

RESULTS

Four randomized controlled trials (RCTs), all of high quality, were enrolled in this meta-analysis, including 787 pregnant women. The offspring of pregnant smokers who received vitamin C supplementation exhibited improved Forced Expiratory Flow between 25 and 75% (FEF25-75), FEF50, FEF75, and Forced Vital Capacity (FVC) compared to those who did not receive vitamin C supplementation. However, there was no statistically significant difference in Forced Expiratory Volume at 0.5 s (FEV0.5) and the ratio of FEV0.5 to FVC between the offspring of pregnant smokers who received vitamin C and the control group.

CONCLUSION

Vitamin C supplementation for smoking pregnant women may enhance the pulmonary function of their offspring, particularly in FEF25-75, FEF50, FEF75, and FVC. Nevertheless, there are no significant differences in FEV0.5 and the FEV0.5/FVC ratio. These findings suggest that vitamin C supplementation has potential benefits for specific pulmonary function. Further studies are needed to comprehensively assess the effects of vitamin C on pulmonary function in the context of maternal smoking during pregnancy.

Improvements in lung function following vitamin C supplementation to pregnant smokers are associated with buccal DNA methylation at 5 years of age

BACKGROUND

We previously reported in the "Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function" randomized clinical trial (RCT) that vitamin C (500 mg/day) supplementation to pregnant smokers is associated with improved respiratory outcomes that persist through 5 years of age. The objective of this study was to assess whether buccal cell DNA methylation (DNAm), as a surrogate for airway epithelium, is associated with vitamin C supplementation, improved lung function, and decreased occurrence of wheeze.

METHODS

We conducted epigenome-wide association studies (EWAS) using Infinium MethylationEPIC arrays and buccal DNAm from 158 subjects (80 placebo; 78 vitamin C) with pulmonary function testing (PFT) performed at the 5-year visit. EWAS were performed on (1) vitamin C treatment, (2) forced expiratory flow between 25 and 75% of expired volume (FEF25-75), and (3) offspring wheeze. Models were adjusted for sex, race, study site, gestational age at randomization (≤ OR > 18 weeks), proportion of epithelial cells, and latent covariates in addition to child length at PFT in EWAS for FEF25-75. We considered FDR p < 0.05 as genome-wide significant and nominal p < 0.001 as candidates for downstream analyses. Buccal DNAm measured in a subset of subjects at birth and near 1 year of age was used to determine whether DNAm signatures originated in utero, or emerged with age.

RESULTS

Vitamin C treatment was associated with 457 FDR significant (q < 0.05) differentially methylated CpGs (DMCs; 236 hypermethylated; 221 hypomethylated) and 53 differentially methylated regions (DMRs; 26 hyper; 27 hypo) at 5 years of age. FEF25-75 was associated with one FDR significant DMC (cg05814800), 1,468 candidate DMCs (p < 0.001), and 44 DMRs. Current wheeze was associated with 0 FDR-DMCs, 782 candidate DMCs, and 19 DMRs (p < 0.001). In 365/457 vitamin C FDR significant DMCs at 5 years of age, there was no significant interaction between time and treatment.

CONCLUSIONS

Vitamin C supplementation to pregnant smokers is associated with buccal DNA methylation in offspring at 5 years of age, and most methylation signatures appear to be persistent from the prenatal period. Buccal methylation at 5 years was also associated with current lung function and occurrence of wheeze, and these functionally associated loci are enriched for vitamin C associated loci. Clinical trial registration ClinicalTrials.gov, NCT01723696 and NCT03203603.

Presurgical Pulmonary Function Tests in the First Few Days of Life in Neonates with Congenital Heart Disease, A Pilot Study

Objective

To compare early pulmonary function tests (PFTs) in neonates with critical congenital heart disease (CHD) compared to a historical reference group.

Design

Infants > 37 weeks gestation with critical CHD were studied within the first few days of life and prior to cardiac surgery and compared to data from a published reference group. Passive respiratory resistance (Rrs) and compliance (Crs) were measured with the single breath occlusion technique following specific acceptance criteria. The study was powered for a 30% difference in Rrs.

Results

PFTs in 24 infants with CHD were compared to 31 historical reference infants. There was no difference in the Rrs between the groups. The infants with CHD had a significantly decreased Crs (1.02 ± 0.26 mL/cmH2O/kg versus 1.32 ± 0.36; (p < 0.05; mean ± SD)).

Conclusions

Further prospective studies are required to quantify early PFTs in infants with CHD of different phenotypes.

Impact of Climate Change on Dietary Nutritional Quality and Implications for Asthma and Allergy

Asthma and allergic disorders are common in childhood with genetic and environmental determinants of disease that include prenatal nutritional exposures such as long-chain polyunsaturated fatty acids and antioxidants. Global climate change is implicated in asthma and allergic disorder morbidity with potential mechanisms including perturbations of ecosystems. There is support that environmental and climatic changes such as increasing global temperate and carbon dioxide levels affect aquatic and agricultural ecosystems with subsequent alterations in long-chain polyunsaturated fatty acid availability and nutrient quality and antioxidant capacity of certain crops, respectively. This article discusses asthma epidemiology and the influence of global climate change.

Association of serum vitamin C levels with Asthma in adults: results of NHANES 2003-2006 and mendelian randomization study

BACKGROUND

The protective effect of vitamin C as an antioxidant against asthma in adults remains controversial. This study used an observational study and Mendelian randomization (MR) analysis to investigate the association between adult asthma and serum vitamin C levels.

METHODS

Using information from the National Health and Nutrition Examination Survey (NHANES) 2003-2006, we carried out an observational study. A multivariate logistic regression model was employed to examine the connection between adult asthma and serum vitamin C levels. We used the inverse-variance weighted (IVW) method of MR analysis as the primary method to analyze the causal effect of serum vitamin C levels on asthma in adults.

RESULTS

A total of 8,504 participants were included in the observational study, including 639 in the asthma group and 7,865 in the non-asthma group. Before sample weighting, serum vitamin C was associated with a reduced risk of asthma in adults (OR = 0.798, 95% CI: 0.673-0.945, P = 0.009). After sample weighting, serum vitamin C was not associated with adult asthma risk (OR = 0.829, 95% CI: 0.660 ~ 1.042, P = 0.104). MR analysis showed no causal relationship between serum vitamin C and adult asthma in either the UK Biobank (OR = 0.957, 95% CI: 0.871 ~ 1.053, P = 0.370) or FinnGen (OR = 0.973, 95% CI: 0.824 ~ 1.149, P = 0.750) cohorts.

CONCLUSION

Our study did not support a causal association between serum vitamin C levels and adult asthma risk. The relationship between serum vitamin C and adult asthma requires further research.

Fetal pulmonary artery Doppler blood flow velocity measures and early infant lung function. A prospective cohort study

BACKGROUND

Reduced lung function at birth has evident antenatal origins and is associated with an increased risk of wheezing and asthma later in life. Little is known about whether blood flow in the fetal pulmonary artery, may impact postnatal lung function.

OBJECTIVE

Our primary aim was to investigate the potential associations between fetal Doppler blood flow velocity measures in the fetal branch pulmonary artery, and infant lung function by tidal flow-volume (TFV) loops at three months of age in a low-risk population. Our secondary aim was to explore the association between Doppler blood flow velocity measures in the umbilical and middle cerebral arteries, and the same lung function measures.

METHODS

In 256 non-selected pregnancies from the birth cohort study Preventing Atopic Dermatitis and ALLergies in Children (PreventADALL) we performed fetal ultrasound examination with Doppler blood flow velocity measurements at 30 gestational weeks (GW). We recorded the pulsatility index, peak systolic velocity, time-averaged maximum velocity, acceleration time/ejection time ratio, and time velocity integral primarily in the proximal pulmonary artery close to the pulmonary bifurcation. The pulsatility index was measured in the umbilical and middle cerebral arteries and the peak systolic velocity in the middle cerebral artery. The cerebro-placental ratio (ratio between pulsatility index in the middle cerebral and umbilical arteries) was calculated. Infant lung function was assessed using TFV loops in awake, calmly breathing three months old infants. The outcome was the time to peak tidal expiratory flow to expiratory time ratio (t_PTEF/t_E), t_PTEF/t_E <25^th percentile, and tidal volume per kg body weight (V_T/kg). Potential associations between fetal Doppler blood flow velocity measures and infant lung function were assessed using linear and logistic regressions.

RESULTS

The infants were born at median (min - max) 40.3 (35.6 - 42.4) GW, with a mean (SD) birth weight of 3.52 (0.46) kg, and 49.4% were females. The mean (SD) t_PTEF/t_E was 0.39 (0.1) and the 25^th percentile was 0.33. Neither univariable nor multivariable regression models revealed any associations between fetal pulmonary blood flow velocity measures and t_PTEF/t_E, t_PTEF/t_E <25^th percentile, or V_T/kg at three months of age. Similarly, we did not observe associations between Doppler blood flow velocity measures in the umbilical and middle cerebral arteries and infant lung function measures.

CONCLUSION

In a cohort of 256 infants from the general population, fetal third-trimester Doppler blood flow velocity measures in the branch pulmonary, umbilical, and middle cerebral arteries were not associated with infant lung function measures at three months of age.

Pulmonary phenotypes of bronchopulmonary dysplasia in the preterm infant

Bronchopulmonary dysplasia (BPD) remains the most common complication of premature birth, imposing a significant and potentially life-long burden on patients and their families. Despite advances in our understanding of the mechanisms that contribute to patterns of lung injury and dysfunctional repair, current therapeutic strategies remain non-specific with limited success. Contemporary definitions of BPD continue to rely on clinician prescribed respiratory support requirements at specific time points. While these criteria may be helpful in broadly identifying infants at higher risk of adverse outcomes, they do not offer any precise information regarding the degree to which each compartment of the lung is affected. In this review we will outline the different pulmonary phenotypes of BPD and discuss important features in the pathogenesis, clinical presentation, and management of these frequently overlapping scenarios.

Defining and Promoting Pediatric Pulmonary Health: Assessing Lung Function and Structure

Lifelong respiratory health is rooted in the structural and functional development of the respiratory system in early life. Exposures and interventions antenatally through childhood can influence lung development into young adulthood, the life stage with the highest achievable lung function. Because early respiratory health sets the stage for adult lung function trajectories and risk of developing chronic obstructive pulmonary disease, understanding how to promote lung health in children will have far reaching personal and population benefits. To achieve this, it is critical to have accurate and precise measures of structural and functional lung development that track throughout life stages. From this foundation, evaluation of environmental, genetic, metabolic, and immune mechanisms involved in healthy lung development can be investigated. These goals require the involvement of general pediatricians, pediatric subspecialists, patients, and researchers to design and implement studies that are broadly generalizable and applicable to otherwise healthy and chronic disease populations. This National Institutes of Health workshop report details the key gaps and opportunities regarding lung function and structure.

Nutrient Supplementation during the Prenatal Period in Substance-Using Mothers: A Narrative Review of the Effects on Offspring Development

Substance use during pregnancy increases the risk for poor developmental outcomes of the offspring, and for substance-dependent mothers, abstaining from substance use during pregnancy is often difficult. Given the addictive nature of many substances, strategies that may mitigate the harmful effects of prenatal substance exposure are important. Prenatal nutrient supplementation is an emerging intervention that may improve developmental outcomes among substance-exposed offspring. We provide a narrative review of the literature on micronutrient and fatty acid supplementation during pregnancies exposed to substance use in relation to offspring developmental outcomes. We first discuss animal models exposed to ethanol during pregnancy with supplementation of choline, zinc, vitamin E, iron, and fatty acids. We follow with human studies of both alcohol- and nicotine-exposed pregnancies with supplementation of choline and vitamin C, respectively. We identified only 26 animal studies on ethanol and 6 human studies on alcohol and nicotine that supplemented nutrients during pregnancy and reported offspring developmental outcomes. There were no studies that examined nutrient supplementation during pregnancies exposed to cannabis, illicit substances, or polysubstance use. Implementations and future directions are discussed.

Oxygen for the Newborn: Friend or Foe?

Oxygen supplementation is widely used in neonatal care, however, it can also cause toxic effects if not used properly. Therefore, it appears crucial to find a balance in oxygen administration to avoid damage as a consequence of its insufficient or excessive use. Oxygen toxicity is mainly due to the production of oxygen radicals, molecules normally produced in humans and involved in a myriad of physiological reactions. In the neonatal period, an imbalance between oxidants and antioxidant defenses, the so-called oxidative stress, might occur, causing severe pathological consequences. In this review, we focus on the mechanisms of the production of oxygen radicals and their physiological functions in determining a set of diseases grouped together as "free radical diseases in the neonate". In addition, we describe the evolution of the oxygenation target recommendations during neonatal resuscitation and post-stabilization phases with the aim to define the best oxygen administration according to the newest evidence.

The Role of Lung Function in Determining Which Children Develop Asthma

Longitudinal studies have demonstrated that altered indices of airway function, assessed shortly after birth, are a risk factor for the subsequent development of wheezing illnesses and asthma, and that these indices predict airway size and airway wall thickness in adult life. Pre- and postnatal factors that directly alter early airway function, such as extreme prematurity and cigarette smoke, may continue to affect airway function and, hence, the risks for wheeze and asthma. Early airway function and an associated asthma risk may also be indirectly influenced by immune system responses, respiratory viruses, the airway microbiome, genetics, and epigenetics, especially if they affect airway epithelial dysfunction. Few if any interventions, apart from smoking avoidance, have been proven to alter the risks of developing asthma, but vitamin C supplementation to pregnant smokers may help decrease the effects of in utero smoke on offspring lung function. We conclude that airway size and the factors influencing this play an important role in determining the risk for asthma across the lifetime. Progress in asthma prevention is long overdue and this may benefit from carefully designed interventions in well-phenotyped longitudinal birth cohorts with early airway function assessments monitored through to adulthood.

Prenatal tobacco smoke exposure and risk of brain abnormalities on magnetic resonance imaging at term in infants born very preterm

BACKGROUND

Prenatal tobacco smoke exposure and preterm birth are associated with abnormal brain and neurodevelopmental outcomes in infants. Studies that can disentangle indirect mediating effects from direct effects of prenatal tobacco smoke exposure on sensitive early brain magnetic resonance imaging biomarkers in very preterm infants are needed.

OBJECTIVE

This study aimed to determine whether prenatal tobacco smoke exposure in preterm infants posed any direct effects on magnetic resonance imaging-determined global brain abnormality score and secondary measures of brain abnormalities after removing any indirect mediating effects of preterm birth on neurostructural outcomes.

STUDY DESIGN

We examined brain magnetic resonance imaging findings collected at 39 to 44 weeks postmenstrual age from a prospective cohort of 395 infants born very preterm (gestational age of ≤32 weeks). The primary outcome was global brain abnormality score, and the secondary outcomes were global efficiency of structural connectome, diffuse white matter abnormality volume, total brain tissue volume, total gray and white matter volumes, and cerebellar volume. Maternal reports of smoking during pregnancy were obtained. We performed multivariable linear regression analyses to examine the association between prenatal tobacco smoke exposure and our magnetic resonance imaging outcomes, controlling for prospectively collected confounders. Moreover, we performed a mediation analysis to estimate the direct effects of prenatal tobacco smoke exposure on brain abnormalities and any indirect effects through preterm birth.

RESULTS

Overall, 12.6% of infants had prenatal tobacco smoke exposure. Infants with prenatal tobacco smoke exposure had a higher median global brain abnormality score than nonexposed infants (7 [interquartile range, 0-41] vs 5 [interquartile range, 0-34]; P≤.001); the findings remained significant (P<.001) after controlling for antenatal confounders. Global efficiency (P<.001), diffuse white matter volume (P=.037), and total brain tissue volume (P=.047) were significantly different between TSE groups in multivariable analyses. On mediation analysis, preterm birth mediated between 0% and 29% of the indirect effect of prenatal tobacco smoke exposure on several measures of brain abnormality outcomes. Thus, prenatal tobacco smoke exposure had a direct adverse effect between 71% and 100% on brain injury or abnormal development.

CONCLUSION

Our study has identified multiple adverse effects of prenatal tobacco smoke exposure on sensitive and objective measures of neonatal brain injury and abnormal development; most cases seemed to be a direct effect of prenatal tobacco smoke exposure on fetal brain development. The results underscored the significant adverse neurostructural effects of prenatal tobacco smoke exposure to tobacco smoke pollutants.

Perioperative Improvement in Pulmonary Function in Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

The objective of this study was to compare serial changes in pulmonary function in contemporary infants with congenital diaphragmatic hernia managed with a gentle ventilation approach.

STUDY DESIGN

Observational cohort, single-center study of infants ≥35^0/7 weeks gestation at delivery with congenital diaphragmatic hernia. Functional residual capacity (FRC), passive respiratory compliance, and passive respiratory resistance were measured presurgical and postsurgical repair and within 2 weeks of discharge. A 1-way analysis of variance for repeated measures was used to evaluate the change in FRC, passive respiratory compliance, and passive respiratory resistance over these repeated measures.

RESULTS

Twenty-eight infants were included in the analysis with a mean gestational age of 38.3 weeks and birth weight of 3139 g. We found a significant increase in FRC across the 3 time points (mean in mL/kg [SD]: 10.9 [3.6] to 18.5 [5.2] to 24.2 [4.4]; P < .0001). There was also a significant increase in passive respiratory compliance and decrease in passive respiratory resistance. In contrast to a previous report, there were survivors in the current cohort with a preoperative FRC of <9 mL/kg. The mean FRC measured at discharge was in the range considered within normal limits. Sixteen infants had prenatal measurements of the lung-to-head ratio, but there was no relationship between the lung-to-head ratio and preoperative or postoperative FRC measurements.

CONCLUSIONS

Infants with congenital diaphragmatic hernia demonstrate significant increases in FRC and improvements in respiratory mechanics measured preoperatively and postoperatively and at discharge. We speculate these improvements are due to the surgical resolution of the mechanical obstruction to lung recruitment and that after achieving preoperative stability, repair should not be delayed given these demonstrable postoperative improvements.

Asthma Management in Children

Asthma is a common, complex heterogeneous disease often beginning in early life and is characterized by reversible airflow obstruction. The phenotypic differences that exist in children with asthma may impact underlying comorbid conditions and pharmacologic treatment choices. Prenatal factors for increased risk of asthma could include maternal diet and the maternal microbiome. Evidence also suggests that postnatal microbial exposures and colonization contribute to the risk of allergic diseases and asthma. After confirming the diagnosis, asthma management in children centers on 3 broad areas: pharmacologic treatment, treatment of underlying comorbidities, and education of the patient and caregivers on the importance of adherence and device technique. Moreover, social determinants of health significantly impact on symptom burden and treatment response.

Effect of Vitamin C Supplementation for Pregnant Smokers on Offspring Airway Function and Wheeze at Age 5 Years: Follow-up of a Randomized Clinical Trial

Importance

Vitamin C supplementation (500 mg/d) for pregnant smokers has been reported to increase offspring airway function as measured by forced expiratory flow (FEF) through age 12 months; however, its effects on airway function at age 5 years remain to be assessed.

Objective

To assess whether vitamin C supplementation in pregnant smokers is associated with increased and/or improved airway function in their offspring at age 5 years and whether vitamin C decreases the occurrence of wheeze.

Design, Setting, and Participants

This study followed up the Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) double-blind, placebo-controlled randomized clinical trial conducted at 3 centers in the US (in Oregon, Washington, and Indiana) between 2012 and 2016. Investigators and participants remain unaware of the treatment assignments. Forced expiratory flow measurements at age 5 years were completed from 2018 to 2021.

Interventions

Pregnant smokers were randomized to vitamin C (500 mg/d) or placebo treatment.

Main Outcomes and Measures

The primary outcome was the prespecified measurement of FEF between 25% and 75% expired volume (FEF25-75) by spirometry at age 5 years. Secondary outcomes included FEF measurements at 50% and 75% of expiration (FEF50 and FEF75), forced expiratory volume in 1 second (FEV1), and occurrence of wheeze.

Results

Of the 251 pregnant smokers included in this study, 125 (49.8%) were randomized to vitamin C and 126 (50.2%) were randomized to placebo. Of 213 children from the VCSIP trial who were reconsented into this follow-up study, 192 (90.1%) had successful FEF measurements at age 5 years; 212 (99.5%) were included in the analysis of wheeze. Analysis of covariance demonstrated that offspring of pregnant smokers allocated to vitamin C compared with placebo had 17.2% significantly higher mean (SE) measurements of FEF25-75 at age 5 years (1.45 [0.04] vs 1.24 [0.04] L/s; adjusted mean difference, 0.21 [95% CI, 0.13-0.30]; P < .001). Mean (SE) measurements were also significantly increased by 14.1% for FEF50 (1.59 [0.04] vs 1.39 [0.04] L/s; adjusted mean difference, 0.20 [95% CI, 0.11-0.30]; P < .001), 25.9% for FEF75 (0.79 [0.02] vs 0.63 [0.02] L/s; 0.16 [95% CI, 0.11-0.22]; P < .001), and 4.4% for FEV1 (1.13 [0.02] vs 1.09 [0.02] L; 0.05 [95% CI, 0.01-0.09]; P = .02). In addition, offspring of pregnant smokers randomized to vitamin C had significantly decreased wheeze (28.3% vs 47.2%; estimated odds ratio, 0.41 [95% CI, 0.23-0.74]; P = .003).

Conclusions and Relevance

In this follow-up study of offspring of pregnant smokers randomized to vitamin C vs placebo, vitamin C supplementation during pregnancy resulted in significantly increased airway function of offspring at age 5 years and significantly decreased the occurrence of wheeze. These findings suggest that vitamin C supplementation for pregnant smokers may decrease the effects of smoking in pregnancy on childhood airway function and respiratory health.

Trial Registration

ClinicalTrials.gov Identifier: NCT03203603.

Prematurity-associated wheeze: current knowledge and opportunities for further investigation

Prematurity-associated wheeze is a common complication of preterm birth, with significant impact on the health and healthcare utilization of former preterm infants. This wheezing phenotype remains poorly understood and difficult to predict. This review will discuss the current state of the literature on prematurity-associated wheeze. We will discuss etiology and pathophysiology, and offer two conceptual models for the pathogenesis of this complex condition. This review will also identify current methods of ascertainment, and discuss the strengths and limitations of each. We will explore research-backed approaches to prevention and management, and finally suggest both pre-clinical and clinical avenues for investigation. An in-depth understanding of prematurity-associated wheeze will aid clinicians in its diagnosis and management, and inspire scientists to pursue much-needed further study into causes and prevention of this common and impactful condition. IMPACT: There is no recent, concise review on the current state of research on prematurity-associated wheeze, which is a rapidly evolving area of study. This article highlights causal models of wheeze, methods of ascertainment, management strategies for the clinician, and opportunities for further research for the physician scientist.

Long-term expiratory airflow of infants born moderate-late preterm: A systematic review and meta-analysis

BACKGROUND

Moderate-late preterm (MLP; 32 to <37 weeks' gestation) birth is associated with reduced expiratory airflow during child, adolescent and adult years. However, some studies have reported only minimal airflow limitation and hence it is unclear if clinical assessment in later life is warranted. Our aim was to compare maximal expiratory airflow in children and adults born MLP with term-born controls, and with expected norms.

METHODS

We systematically reviewed studies reporting z-scores for spirometric indices (forced expired volume in 1 second [FEV₁], forced vital capacity [FVC], FEV₁/FVC ratio and forced expiratory flow at 25-75% of FVC [FEF_25-75%]) from participants born MLP aged five years or older, with or without a term-born control group from 4 databases (MEDLINE, CINAHL, Embase, Emcare). Publications were searched for between the 22^nd of September 2021 to the 29^th of September 2021. A meta-analysis of eligible studies was conducted using a random effects model. The study protocol was published in PROSPERO (CRD #42021281518).

FINDINGS

We screened 4970 articles and identified 18 relevant studies, 15 of which were eligible for meta-analysis (8 with term-born controls and 7 without). Compared with controls, MLP participants had lower z-scores (mean difference [95% confidence interval] I²) for FEV₁: -0.22 [-0.35, -0.09] 49.3%, FVC: -0.23 [-0.4, -0.06] 71.8%, FEV₁/FVC: -0.11 [-0.20 to -0.03] 9.3% and FEF_25-75%: -0.27 [-0.41 to -0.12] 21.9%. Participants born MLP also had lower z-scores, on average, when compared with a z-score of 0 (mean [95% CI] I²) for FEV₁: -0.26 [-0.40 to -0.11] 85.2%, FVC: -0.18 [-0.34 to -0.02] 88.3%, FEV₁/FVC: -0.24 [-0.43 to -0.05] 90.5% and FEF_25-75%: -0.33 [-0.54 to -0.20] 94.7%.

INTERPRETATION

Those born MLP had worse expiratory airflows than those born at term, and compared with norms, although reductions were modest. Clinicians should be aware that children and adults born MLP may be at higher risk of obstructive lung disease compared with term-born peers.

FUNDING

This work is supported by grants from the National Health and Medical Research Council (Centre of Research Excellence #1153176, Project grant #1161304); Medical Research Future Fund (Career Development Fellowship to J.L.Y Cheong #1141354) and from the Victorian Government's Operational Infrastructure Support Programme. C. Du Berry's PhD candidature is supported by the Melbourne Research Scholarship and the Centre of Research Excellence in Newborn Medicine.

Cigarette smoke-induced trophoblast cell ferroptosis in rat placenta and the effects of L-arginine intervention

Cigarette smoke (CS) disrupts placental development, and impairs fetal health and maternal fertility, thus resulting in low birth weight, premature delivery, and spontaneous abortion; however, the underlying mechanisms remain unclear. This study investigated the mechanism through which CS impairs placental trophoblast cell viability and function. An in vivo study in pregnant rats exposed to CS indicated that CS- exposure decreased antioxidant factors expression and blocked NRF2 activation in the placenta. Anti-ferroptosis regulators expression was downregulated, and pro-ferroptosis regulators expression was upregulated in placentas from CS-exposed rats. Further analysis revealed that cigarette smoke extract (CSE) led to peroxins downregulation and decreased the number of peroxisomes. An in vitro study in HTR-8/SVneo(HTR-8) cells showed that CSE led to free iron and ROS accumulation, and subsequently induced lipid peroxidation and cell death. Ferroptosis inhibitors and the antioxidant L-arginine (ARG) partially inhibited CSE-induced cell death. ARG partially alleviated the toxic effects of CSE by promoting antioxidant factors expression in placenta and suppressing HTR-8 cell ferroptosis. Knockdown of PEX14, a peroxisome biogenesis marker, led to the downregulation of multiple PEXs, thus increasing intracellular H₂O₂ levels and inducing HTR-8 cell ferroptosis. These findings demonstrated that ferroptosis is responsible for CSE-induced trophoblast cell death and suggest that peroxisome dysfunction is involved in CSE-induced ferroptosis. Therefore, CSE-induced ferroptosis may serve as a potential therapeutic target for preventing adverse pregnancy outcomes.

Dietary Factors Associated with Asthma Development: A Narrative Review and Summary of Current Guidelines and Recommendations

Asthma is a complex disease, caused by a combination of genetic and environmental factors. The prevalence of asthma is increasing too rapidly to be attributable to genetic factors alone. Thus, environmental factors are becoming increasingly recognized as the cause of asthma. Modifying these environmental factors may be a simple approach for asthma prevention. To date, dietary intervention is an interesting modifiable factor because it can be implemented at the population level. The modification of systemic inflammation, oxidation, and microbial composition might be a mechanistic basis for prevention. This review summarizes the mechanistic basis and evidence from clinical studies on the association between dietary factors and asthma development. We also summarize the recommendations from many organizations and regional guidelines to assist the practicing physician to improve patient care.

In utero exposures to mint-flavored JUUL aerosol impair lung development and aggravate house dust mite-induced asthma in adult offspring mice

There are few reports concerning electronic nicotine delivery system (ENDS) use during pregnancy and no studies on asthma in prenatally JUUL-exposed offspring. Here, we tested the hypothesis that in utero JUUL exposure causes unfavorable birth outcomes and lasting pulmonary health effects in adult offspring. BALB/c dams were exposed to either air or mint-flavored JUUL aerosol, 1-hr/d, 20 consecutive days during gestation. Offspring were sacrificed on post-natal day (PND) 0 or at 11-week of age, following house dust mite (HDM) challenge. Gene expression was assessed in the uterine/placental tissue of the dams and lung responses were assessed in offspring at PND0 and at 11 weeks of age. JUUL-exposed offspring exhibited decreased body weights and lengths at PND0. These birth outcomes were accompanied by dysregulation of 54 genes associated with hypoxia and oxidative stress in the uterine/placental tissues of JUUL-exposed dams, as well as 24 genes in the lungs of the offspring related to Wnt signaling, plus 9 genes related to epigenetics, and 7 genes related to inflammation. At 11 weeks of age, JUUL + HDM exposed mice exhibited pulmonary inflammation when compared to their respective air + HDM controls. Additionally, the JUUL + HDM exposure dysregulated several genes associated with allergies and asthma. Further, the JUUL + HDM females showed decreased methylation of the promoter region of the Il10ra gene. Taken together, our mouse model shows that inhalation of JUUL aerosols during pregnancy affects the intrauterine environment, impairs lung development, and heightens the effects of allergic airway responses later in life.

Evidence based recommendations for an optimal prenatal supplement for women in the US: vitamins and related nutrients

The blood levels of most vitamins decrease during pregnancy if un-supplemented, including vitamins A, C, D, K, B1, B3, B5, B6, folate, biotin, and B12. Sub-optimal intake of vitamins from preconception through pregnancy increases the risk of many pregnancy complications and infant health problems. In the U.S., dietary intake of vitamins is often below recommended intakes, especially for vitamin D, choline and DHA. Many studies suggest that insufficient vitamin intake is associated with a wide range of pregnancy complications (anemia, Cesarean section, depression, gestational diabetes, hypertension, infertility, preeclampsia, and premature rupture of membranes) and infant health problems (asthma/wheeze, autism, low birth weight, congenital heart defects, intellectual development, intrauterine growth restriction, miscarriage, neural tube defects, orofacial defects, and preterm birth). The primary goal of this paper is to review the research literature and propose evidence-based recommendations for the optimal level of prenatal supplementation for each vitamin for most women in the United States. A secondary goal was to compare these new recommendations with the levels of vitamins in over 180 commercial prenatal supplements. The analysis found that prenatal supplements vary widely in content, often contained only a subset of essential vitamins, and the levels were often below our recommendations. This suggests that increasing prenatal vitamin supplementation to the levels recommended here may reduce the incidence of many pregnancy complications and infant health problems which currently occur.

Epigenetic regulation of immune function in asthma

Asthma is a common complex respiratory disease characterized by chronic airway inflammation and partially reversible airflow obstruction resulting from genetic and environmental determinants. Because epigenetic marks influence gene expression and can be modified by both environmental exposures and genetic variation, they are increasingly recognized as relevant to the pathogenesis of asthma and may be a key link between environmental exposures and asthma susceptibility. Unlike changes to DNA sequence, epigenetic signatures are dynamic and reversible, creating an opportunity for not only therapeutic targets but may serve as biomarkers to follow disease course and identify molecular subtypes in heterogeneous diseases such as asthma. In this review, we will examine the relationship between asthma and 3 key epigenetic processes that modify gene expression: DNA methylation, modification of histone tails, and noncoding RNAs. In addition to presenting a comprehensive assessment of the existing epigenetic studies focusing on immune regulation in asthma, we will discuss future directions for epigenetic investigation in allergic airway disease.

Strategies for Prevention or Treatment of Tobacco and Cannabis Use Disorder

Tobacco and cannabis use in pregnancy are associated with increased adverse perinatal and long-term offspring outcomes. Products for both have evolved with various forms available on the market, challenging accurate counseling of risks and quantification of tobacco and cannabis usage during the perinatal period. Health care providers are recommended to screen for any type of use, provide consistent messaging of harms of tobacco and cannabis use in pregnancy, and offer individualized interventions. The journey to cessation can be complicated by barriers and triggers, lack of social supports, and mental health challenges that should be addressed to prevent relapse and withdrawals.

Ascorbic Acid and the Premature Infant

Little information exists about the plasma target nutritional needs of the >15 million premature infants <37 weeks gestation. Investigating ascorbic acid’s (AscA) role in infant health, our study details the relationship of infant characteristics and maternal health on infant plasma AscA level (pAscA) during postnatal development. Furthermore, we determined pAscA influence during the first week of life (EpAscA) with later infant morbidities. We hypothesize that pAscA is influenced by gestational organ immaturity, as well as maternal factors, with EpAscA associated with greater morbidity risk. We conducted a prospective longitudinal observational study of pAscA, demographics and hospital course detailed in infants ≤34 weeks. Sixty-three subjects were included, with >200 urine and plasma data points analyzed. Maternal smoking, exposure to magnesium sulfate (MgSO4) and advancing gestational and postnatal age were associated with lower pAscA. Non-white infants and those ≤30 weeks that developed bronchopulmonary dysplasia or retinopathy of prematurity had lower pAscA. Prenatal smoking, MgSO4, birth gestational age and race negatively influence pAscA. These results show prenatal and postnatal developmental factors influencing initial pAscA and metabolism, potentially setting the stage for organ health and risk for disease. Assessment of dietary targets may need adjustment in this population.

Maternal diet during pregnancy and risk of allergic diseases in children up to 7-9 years old from Polish Mother and Child Cohort study

BACKGROUND

The impact of maternal diet during pregnancy on the risk of allergic diseases in childhood is an increasing scientific and public health concern. We evaluated the associations of maternal type of diet and essential elements and vitamins intake during pregnancy with offspring allergic and respiratory outcomes.

METHODS

The study population included 557 mother-child pairs from Polish Mother and Child Cohort (REPRO_PL). Based on the Food Frequency Questionnaire filled in between the 20th-24th week of pregnancy, overall maternal diet was evaluated as the difference between the Prudent Dietary Pattern (PDP) score and Western Dietary Pattern (WDP) score ((PDP-WDP) score) and maternal achievement of dietary recommendations (estimated average requirement, EAR) for essential elements and vitamins was assessed. Children's health examination at age of 1, 2, and 7-9 years covered the following symptoms: infections, wheezing/asthma, food allergy, allergic rhinitis, and atopic dermatitis. At age of 7-9 years, children underwent spirometry and skin-prick tests.

RESULTS

Children of the mothers who were not achieving adequate intake of vitamin C during pregnancy had a higher risk of wheezing and having more than two infections within the first two years of life comparing to those who met EAR (OR = 2.6, p = 0.05, and OR = 2.3, p = 0.04, respectively). Inadequate intake of vitamin E during pregnancy was related to a higher risk of atopic dermatitis (OR = 2.7, p = 0.04), whereas inadequate intake of magnesium during pregnancy was associated with the risk of wheezing in the offspring at age of two years (OR = 3.7, p = 0.03). A lower (PDP-WDP) score during pregnancy (indicating unhealthier diet) was associated with a higher risk of infections (OR = 1.5, p = 0.007) but a lower risk of atopic dermatitis (OR = 0.7, p = 0.02) at age of 7-9 years.

CONCLUSIONS

These results may contribute to the body of evidence for the impact of maternal diet during pregnancy for children's optimal health, however further studies are needed before drawing conclusions and recommendations for clinical practice.

Pathogenesis of chronic obstructive pulmonary disease: understanding the contributions of gene-environment interactions across the lifespan

The traditional view of chronic obstructive pulmonary disease (COPD) as a self-inflicted disease caused by tobacco smoking in genetically susceptible individuals has been challenged by recent research findings. COPD can instead be understood as the potential end result of the accumulation of gene-environment interactions encountered by an individual over the life course. Integration of a time axis in pathogenic models of COPD is necessary because the biological responses to and clinical consequences of different exposures might vary according to both the age of an individual at which a given gene-environment interaction occurs and the cumulative history of previous gene-environment interactions. Future research should aim to understand the effects of dynamic interactions between genes (G) and the environment (E) by integrating information from basic omics (eg, genomics, epigenomics, proteomics) and clinical omics (eg, phenomics, physiomics, radiomics) with exposures (the exposome) over time (T)-an approach that we refer to as GETomics. In the context of this approach, we argue that COPD should be viewed not as a single disease, but as a clinical syndrome characterised by a recognisable pattern of chronic symptoms and structural or functional impairments due to gene-environment interactions across the lifespan that influence normal lung development and ageing.

When inflammation meets lung development-an update on the pathogenesis of bronchopulmonary dysplasia

Even more than 50 years after its initial description, bronchopulmonary dysplasia (BPD) remains one of the most important and lifelong sequelae following premature birth. Tremendous efforts have been undertaken since then to reduce this ever-increasing disease burden but a therapeutic breakthrough preventing BPD is still not in sight. The inflammatory response provoked in the immature lung is a key driver of distorted lung development and impacts the formation of alveolar, mesenchymal, and vascular structures during a particularly vulnerable time-period. During the last 5 years, new scientific insights have led to an improved pathomechanistic understanding of BPD origins and disease drivers. Within the framework of current scientific progress, concepts involving disruption of the balance of key inflammatory and lung growth promoting pathways by various stimuli, take center stage. Still today, the number of efficient therapeutics available to prevent BPD is limited to a few, well-established pharmacological interventions including postnatal corticosteroids, early caffeine administration, and vitamin A. Recent advances in the clinical care of infants in the neonatal intensive care unit (NICU) have led to improvements in survival without a consistent reduction in the incidence of BPD. Our update provides latest insights from both preclinical models and clinical cohort studies and describes novel approaches to prevent BPD.

Moving Bronchopulmonary Dysplasia Research from the Bedside to the Bench

Although advances in the respiratory management of extremely preterm infants have led to improvements in survival, this progress has not yet extended to a reduction in the incidence of bronchopulmonary dysplasia (BPD). BPD is a complex multifactorial condition that primarily occurs due to disturbances in the regulation of normal pulmonary airspace and vascular development. Preterm birth and exposure to invasive mechanical ventilation also compromises large airway development, leading to significant morbidity and mortality. Although both predisposing and protective genetic and environmental factors have been frequently described in the clinical literature, these findings have had limited impact on the development of effective therapeutic strategies. This gap is likely because the molecular pathways that underlie these observations are yet not fully understood, limiting the ability of researchers to identify novel treatments that can preserve normal lung development and/or enhance cellular repair mechanisms. In this review article, we will outline various well-established clinical observations whilst identifying key knowledge gaps that need to be filled with carefully designed pre-clinical experiments. We will address these issues by discussing controversial topics in the pathophysiology, the pathology and the treatment of BPD, including an evaluation of existing animal models that have been used to answer important questions.

Time-Specific Factors Influencing the Development of Asthma in Children

Susceptibility to asthma is complex and heterogeneous, as it involves both genetic and environmental insults (pre- and post-birth) acting in a critical window of development in early life. According to the Developmental Origins of Health and Disease, several factors, both harmful and protective, such as nutrition, diseases, drugs, microbiome, and stressors, interact with genotypic variation to change the capacity of the organism to successfully adapt and grow in later life. In this review, we aim to provide the latest evidence about predictive risk and protective factors for developing asthma in different stages of life, from the fetal period to adolescence, in order to develop strategic preventive and therapeutic interventions to predict and improve health later in life. Our study shows that for some risk factors, such as exposure to cigarette smoke, environmental pollutants, and family history of asthma, the evidence in favor of a strong association of those factors with the development of asthma is solid and widely shared. Similarly, the clear benefits of some protective factors were shown, providing new insights into primary prevention. On the contrary, further longitudinal studies are required, as some points in the literature remain controversial and a source of debate.

Molecular regulation of lung maturation in near-term fetal sheep by maternal daily vitamin C treatment in late gestation

BACKGROUND

In the fetus, the appropriate balance of prooxidants and antioxidants is essential to negate the detrimental effects of oxidative stress on lung maturation. Antioxidants improve respiratory function in postnatal life and adulthood. However, the outcomes and biological mechanisms of antioxidant action in the fetal lung are unknown.

METHODS

We investigated the effect of maternal daily vitamin C treatment (200 mg/kg, intravenously) for a month in late gestation (105-138 days gestation, term ~145 days) on molecular regulation of fetal lung maturation in sheep. Expression of genes and proteins regulating lung development was quantified in fetal lung tissue. The number of surfactant-producing cells was determined by immunohistochemistry.

RESULTS

Maternal vitamin C treatment increased fetal lung gene expression of the antioxidant enzyme SOD-1, hypoxia signaling genes (HIF-2α, HIF-3α, ADM, and EGLN-3), genes regulating sodium movement (SCNN1-A, SCNN1-B, ATP1-A1, and ATP1-B1), surfactant maturation (SFTP-B and ABCA3), and airway remodeling (ELN). There was no effect of maternal vitamin C treatment on the expression of protein markers evaluated or on the number of surfactant protein-producing cells in fetal lung tissue.

CONCLUSIONS

Maternal vitamin C treatment in the last third of pregnancy in sheep acts at the molecular level to increase the expression of genes that are important for fetal lung maturation in a healthy pregnancy.

IMPACT

Maternal daily vitamin C treatment for a month in late gestation in sheep increases the expression of gene-regulating pathways that are essential for normal fetal lung development. Following late gestation vitamin C exposure in a healthy pregnancy, an increase in lung gene but not protein expression may act as a mechanism to aid in the preparation for exposure to the air-breathing environment after birth. In the future, the availability/development of compounds with greater antioxidant properties than vitamin C or more specific targets at the site of oxidative stress in vivo may translate clinically to improve respiratory outcomes in complicated pregnancies at birth.

Primary Prevention of Pediatric Asthma through Nutritional Interventions

Asthma is the most common chronic non-communicable disease in children, the pathogenesis of which involves several factors. The increasing burden of asthma worldwide has emphasized the need to identify the modifiable factors associated with the development of the disease. Recent research has focused on the relationship between dietary factors during the first 1000 days of life (including pregnancy)—when the immune system is particularly vulnerable to exogenous interferences—and allergic outcomes in children. Specific nutrients have been analyzed as potential targets for the prevention of childhood wheeze and asthma. Recent randomized controlled trials show that vitamin D supplementation during pregnancy, using higher doses than currently recommended, may be protective against early childhood wheezing but not school-age asthma. Omega-3 fatty acid supplementation during pregnancy and infancy may be associated with a reduced risk of childhood wheeze, although the evidence is conflicting. Data from observational studies suggest that some dietary patterns during pregnancy and infancy might also influence the risk of childhood asthma. However, the quality of the available evidence is insufficient to allow recommendations regarding dietary changes for the prevention of pediatric asthma. This review outlines the available high-quality evidence on the role of prenatal and perinatal nutritional interventions for the primary prevention of asthma in children and attempts to address unmet areas for future research in pediatric asthma prevention.

Hair and nail nicotine levels of mothers and their infants as valid biomarkers of exposure to intrauterine tobacco smoke

INTRODUCTION

Tobacco use remains the single most modifiable cause of adverse pregnancy outcomes. It is crucial to be able to accurately quantify the burden of tobacco exposure on both the mother and fetus to have better measures of efficacy with interventions being studied.

METHODS

This is a descriptive and exploratory study conducted within a randomized controlled trial. Pregnant smoking and non-smoking women were followed from ≤22 weeks' gestation through delivery with monthly maternal smoking questionnaires, urine cotinine levels, and collection of maternal and infant hair and nail samples, at delivery. Nicotine was extracted and measured (ng/mg) using high-performance liquid chromatography with electrochemical detection.

RESULTS

Forty-six mother-infant dyads (34 pregnant smokers and 12 pregnant non-smokers) had successful completion of maternal and infant hair and nails samples. The median hair nicotine levels of the smoking mothers and their infants was significantly higher than those of the non-smokers (1.015 vs 0.037 ng/ mg, p<0.05 for the mothers; 0.445 vs 0.080 ng/mg, p<0.01 for the infants). Similarly, the median nail nicotine levels for smoking mothers and their infants were significantly higher than the non-smokers (2.130 vs 0.056 ng/mg, p<0.01 for the mothers; 0.594 vs 0.132 ng/mg, p<0.05 for the infants). We found a moderate but significant correlation between maternal hair and nail nicotine (r=0.64, p<0.001), infant hair and nail nicotine (r=0.64; p<0.001), maternal and infant hair nicotine (r=0.61, p<0.001), and maternal and infant nail nicotine levels (r=0.58, p<0.001).

CONCLUSIONS

Our study shows that both infant hair and nail nicotine levels are valid biomarkers of intrauterine tobacco smoke exposure, and can be used to identify prenatal smoke exposure, correlating well with the level of maternal nicotine exposure.

Nicotine replacement therapy and e-cigarettes in pregnancy and infant respiratory outcomes

BACKGROUND

Nicotine replacement therapy (NRT) and e-cigarettes are recommended to pregnant women who wish to stop smoking. Albeit eliminating other harmful components of cigarettes, those alternatives still expose the developing fetus to nicotine. The lungs may be particularly vulnerable to damage by nicotine as there is widespread nicotinic-acetylcholine receptor expression in the lungs. There is, however, a paucity of information about the effect of NRT and e-cigarette use in pregnancy on infant respiratory outcomes.

AIMS

To explore the effect of NRT and e-cigarettes on the developing lung.

STUDY DESIGN

A literature search was undertaken to examine the use and safety of nicotine-replacement strategies in pregnancy, with a focus on infant respiratory outcomes. This included experimental studies investigating the effect of isolated "gestational" nicotine on the developing lung.

OUTCOME MEASURES

Respiratory outcomes in animal studies and infants.

RESULTS

Animal studies investigating the effect of gestational nicotine exposure on fetal lung development demonstrated abnormal lung growth; including abnormal airway branching and alveolar development. Consequently, offspring display altered pulmonary mechanics, including both increased respiratory rate and airway resistance. These findings mirror respiratory pathology observed in infants born to smoking mothers. Human trials of NRT and e-cigarette use in pregnancy have not identified adverse perinatal outcomes regarding reduced birthweight or prematurity, but have not considered infant and childhood respiratory outcomes.

CONCLUSIONS

Nicotine can impair fetal lung development, leading to concerns regarding the safety of NRT and e-cigarettes in pregnancy. Studies have yet to explore the impact of these nicotine-containing products on infant respiratory outcomes.

Prenatal and Postnatal Household Air Pollution Exposures and Pneumonia Risk: Evidence From the Ghana Randomized Air Pollution and Health Study

BACKGROUND

Nearly 40% of the world's population is exposed daily to household air pollution. The relative impact of prenatal and postnatal household air pollution exposure on early childhood pneumonia, a leading cause of mortality, is unknown.

RESEARCH QUESTION

Are prenatal or postnatal household air pollution, or both, associated with pneumonia risk in the first year of life?

STUDY DESIGN AND METHODS

The Ghana Randomized Air Pollution and Health Study enrolled 1,414 nonsmoking, pregnant women before 24 weeks' gestation with prospective follow-up to the child's age of 1 year. We measured 72-h personal household air pollution exposures, indexed by carbon monoxide (CO), four times prenatally and three times postnatally. Weekly fieldworker surveillance identified ill-appearing children for physician pneumonia assessment. We used quasi-Poisson models to examine associations between prenatal and postnatal CO and physician-diagnosed pneumonia and severe pneumonia. Sex-specific effects were examined.

RESULTS

Of the 1,306 live births, 1,141 infants were followed up with 55,605 child-weeks of fieldworker surveillance. The estimated risk for pneumonia and severe pneumonia in the first year of life increased by 10% (relative risk [RR], 1.10; 95% CI, 1.04-1.16) and 15% (RR, 1.15; 95% CI, 1.03-1.28), respectively, per 1-part per million (ppm) increase in average prenatal CO exposure and by 6% (RR, 1.06; 95% CI, 0.99-1.13) per 1-ppm increase in average postnatal CO exposure. Sex-stratified analyses suggest that in girls, higher prenatal CO exposure was associated with pneumonia risk, while no association was seen in boys.

INTERPRETATION

Prenatal household air pollution exposure increased risk of pneumonia and severe pneumonia in the first year of life. Clean-burning interventions may be most effective when begun prenatally.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01335490; URL: www.clinicaltrials.gov.

Pulmonary Function Tests in Very Low Birth Weight Infants Screened for Pulmonary Hypertension: A Pilot Study

OBJECTIVE

To compare pulmonary function tests (PFTs), specifically respiratory system resistance (Rrs) and compliance (Crs), in very low birth weight (VLBW) infants with and without pulmonary hypertension.

STUDY DESIGN

Infants were included who underwent PFTs at 34-38 weeks postmenstrual age (PMA) as part of our pulmonary hypertension screening guidelines for infants born at ≤1500 g requiring respiratory support at ≥34 weeks PMA. One pediatric cardiologist reviewed and estimated right ventricular or pulmonary arterial pressure and defined pulmonary hypertension as an estimated pulmonary arterial pressure or right ventricular pressure greater than one-half the systemic pressure. Rrs and Crs were measured with the single breath occlusion technique and functional residual capacity with the nitrogen washout method according to standardized criteria.

RESULTS

Twelve VLBW infants with pulmonary hypertension and 39 without pulmonary hypertension were studied. Those with pulmonary hypertension had significantly lower birth weight and a trend toward a lower gestational age. There were no other demographic differences between the groups. The infants with pulmonary hypertension had significantly higher Rrs (119 vs 78 cmH₂O/L/s; adjusted P = .012) and significantly lower Crs/kg (0.71 vs 0.92 mL/cmH₂O/kg; P = .04).

CONCLUSIONS

In this pilot study of VLBW infants screened for pulmonary hypertension at 34-38 weeks PMA, those with pulmonary hypertension had significantly increased Rrs and decreased Crs compared with those without pulmonary hypertension. Additional studies are needed to further phenotype infants with evolving BPD and pulmonary hypertension.

Impact of vitamin C supplementation on placental DNA methylation changes related to maternal smoking: association with gene expression and respiratory outcomes

BACKGROUND

Maternal smoking during pregnancy (MSDP) affects development of multiple organ systems including the placenta, lung, brain, and vasculature. In particular, children exposed to MSDP show lifelong deficits in pulmonary function and increased risk of asthma and wheeze. Our laboratory has previously shown that vitamin C supplementation during pregnancy prevents some of the adverse effects of MSDP on offspring respiratory outcomes. Epigenetic modifications, including DNA methylation (DNAm), are a likely link between in utero exposures and adverse health outcomes, and MSDP has previously been associated with DNAm changes in blood, placenta, and buccal epithelium. Analysis of placental DNAm may reveal critical targets of MSDP and vitamin C relevant to respiratory health outcomes.

RESULTS

DNAm was measured in placentas obtained from 72 smokers enrolled in the VCSIP RCT: NCT03203603 (37 supplemented with vitamin C, 35 with placebo) and 24 never-smokers for reference. Methylation at one CpG, cg20790161, reached Bonferroni significance and was hypomethylated in vitamin C supplemented smokers versus placebo. Analysis of spatially related CpGs identified 93 candidate differentially methylated regions (DMRs) between treatment groups, including loci known to be associated with lung function, oxidative stress, fetal development and growth, and angiogenesis. Overlap of nominally significant differentially methylated CpGs (DMCs) in never-smokers versus placebo with nominally significant DMCs in vitamin C versus placebo identified 9059 candidate "restored CpGs" for association with placental transcript expression and respiratory outcomes. Methylation at 274 restored candidate CpG sites was associated with expression of 259 genes (FDR < 0.05). We further identified candidate CpGs associated with infant lung function (34 CpGs) and composite wheeze (1 CpG) at 12 months of age (FDR < 0.05). Increased methylation in the DIP2C, APOH/PRKCA, and additional candidate gene regions was associated with improved lung function and decreased wheeze in offspring of vitamin C-treated smokers.

CONCLUSIONS

Vitamin C supplementation to pregnant smokers ameliorates changes associated with maternal smoking in placental DNA methylation and gene expression in pathways potentially linked to improved placental function and offspring respiratory health. Further work is necessary to validate candidate loci and elucidate the causal pathway between placental methylation changes and outcomes of offspring exposed to MSDP. Clinical trial registration ClinicalTrials.gov, NCT01723696. Registered November 6, 2012. https://clinicaltrials.gov/ct2/show/record/NCT01723696 .

Spirometry: A practical lifespan predictor of global health and chronic respiratory and non-respiratory diseases

OBJECTIVES

1. To review and discuss available evidence supporting that spirometry is an overlooked global health marker, that could be used regularly through the lifespan to monitor human health and predict risk of chronic respiratory and other chronic non-communicable diseases (NCDs). 2. To discuss the challenges and opportunities that this proposal faces.Summary of key data. First, spirometry is essential to assess and monitor respiratory health. Second, spirometry adds prognostic value to other well-accepted health markers used in clinical practice, such as blood pressure, body mass index, glucose and blood lipids, by identifying individuals at risk, not only of respiratory diseases, but also of other NCDs, particularly cardiovascular and metabolic disorders.

CONCLUSION

Although we acknowledge that research gaps still exist, we propose that spirometry assessed during childhood, adolescence and early and late adulthood can be a reproducible, non-invasive, safe and affordable global health marker to identify individuals in the general population at risk of respiratory and non-respiratory NCDs. In this context, spirometry may act as the caged canaries that miners used to carry into mines to alert them of dangerous accumulations of gases, thus providing an early warning and save lives.