Effects of in utero and environmental tobacco smoke exposure on lung function in boys and girls with and without asthma

Secondhand Smoke Exposure and Its Impact on Pediatric Lung Function, Aerobic Fitness, and Body Mass: Evidence from a Cross-Sectional Study

BACKGROUND

Several studies have documented the detrimental impacts of secondhand smoke (SHS) exposure to a range of pediatric respiratory conditions, including asthma, bronchitis, and reduced lung function. The aim of the study was to investigate the influence of SHS exposure on lung function, physical fitness, and body mass index (BMI) in children aged 10 to 14 years.

METHODS

This cross-sectional study included children aged 10 to 14 years at the Elementary School "Trilj" in Trilj, Croatia. Data on SHS exposure were collected using a questionnaire. Antropometric and spirometry measurements were performed. Physical fitness was assessed using the shuttle run (BEEP) test.

RESULTS

This study included 157 children, 89 (56.69%) boys and 68 (43.31%) girls. Children exposed to every day SHS in households had significantly lower values of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF) (p < 0.001) and higher z-score BMI levels (p = 0.018) in comparison to unexposed children. Logistic regression showed that children unexposed to SHS had higher odds for better results in the BEEP test (OR 62.45, 95% CI 21.26-179.24, p < 0.001). Children with poorer physical fitness, expressed by lower BEEP score levels, had significantly lower FVC, FEV1, FEV1/FVC, and PEF (p < 0.001).

CONCLUSIONS

Every day SHS exposure in children was associated with poorer lung function, higher BMI, and poorer physical fitness.

The impact of exposure to tobacco smoke and e-cigarettes on asthma-related outcomes: Systematic review informing the EAACI guidelines on environmental science for allergic diseases and asthma

To inform the clinical practice guidelines' recommendations developed by the European Academy of Allergy and Clinical Immunology systematic reviews (SR) assessed using GRADE on the impact of environmental tobacco smoke (ETS) and active smoking on the risk of new-onset asthma/recurrent wheezing (RW)/low lung function (LF), and on asthma-related outcomes. Only longitudinal studies were included, almost all on combustion cigarettes, only one assessing e-cigarettes and LF. According to the first SR (67 studies), prenatal ETS increases the risk of RW (moderate certainty evidence) and may increase the risk of new-onset asthma and of low LF (low certainty evidence). Postnatal ETS increases the risk of new-onset asthma and of RW (moderate certainty evidence) and may impact LF (low certainty evidence). Combined in utero and postnatal ETS may increase the risk of new-onset asthma (low certainty evidence) and increases the risk of RW (moderate certainty evidence). According to the second SR (24 studies), ETS increases the risk of severe asthma exacerbations and impairs asthma control and LF (moderate certainty evidence). According to the third SR (25 studies), active smoking increases the risk of severe asthma exacerbations and of suboptimal asthma control (moderate certainty evidence) and may impact asthma-related quality-of-life and LF (low certainty evidence).

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.

Trends in Smoking Before, During, and After Pregnancy in the United States from 2000 to 2020: Pregnancy Risk Assessment Monitoring System

Objectives: This study used 2000-2020 Pregnancy Risk Assessment Monitoring System data to estimate trends in smoking before, during, and after pregnancy, as well as quitting smoking during pregnancy. Materials and Methods: Weighted prevalence and 95% confidence intervals (CIs) were calculated by year for each smoking-related measure. Annual percent change (APC) and average annual percent change (AAPC) in prevalence were estimated using Joinpoint regression to characterize trends over time. Results: Between 2000 and 2020, significant decreases in the prevalence of smoking before (23.0% to 14.0%; AAPC = -2.3% [95% CI = -2.9% to -1.7%]), during (13.2% to 6.5%; AAPC = -3.4% [95% CI = -4.0% to -2.7%]), and after pregnancy (18.9% to 8.8%; AAPC = -3.6% [95% CI = -4.3% to -2.9%]) were observed. For each measure, the fastest declines occurred largely throughout the 2010s (before: APC = -5.5% [2012-2020]; during: APC = -5.1% [2009-2020]; and after: APC = -6.4% [2012-2020]). The proportion of people who quit smoking during pregnancy significantly increased from 43.2% in 2000 to 53.7% in 2020 (AAPC = 1.0%; 95% CI = 0.2%-1.9%); however, Joinpoint regression detected relatively no change in quitting during pregnancy between 2010 and 2020 (APC = 0.0%; 95% CI = -0.4% to 0.5%). Conclusions: The prevalence of smoking before, during, and after pregnancy has reduced dramatically in the United States between 2000 and 2020, with the fastest declines occurring throughout the second decade of the twenty-first century. However, prevention and cessation efforts are still needed since approximately half of people who smoked before pregnancy continue to smoke during pregnancy.

ERS International Congress 2023: highlights from the Paediatrics Assembly

Respiratory health in children is essential for general wellbeing and healthy development in the short and long term. It is well known that many respiratory diseases in adulthood have their origins in early life, and therefore research on prevention of respiratory diseases and management of children with respiratory diseases will benefit patients during the full life course. Scientific and clinical advances in the field of respiratory health are moving at a fast pace. This article summarises some of the highlights in paediatric respiratory medicine presented at the hybrid European Respiratory Society (ERS) International Congress 2023 which took place in Milan (Italy). Selected sessions are summarised by Early Career Members of the Paediatrics Assembly (Assembly 7) under the supervision of senior ERS officers, and cover a wide range of research areas in children, including respiratory physiology and sleep, asthma and allergy, cystic fibrosis, respiratory infection and immunology, neonatology and intensive care, respiratory epidemiology and bronchology.

Preterm Birth, Developmental Smoke/Nicotine Exposure, and Life-Long Pulmonary Sequelae

This review delineates the main pulmonary issues related to preterm birth, perinatal tobacco/nicotine exposure, and its effects on offspring, focusing on respiratory health and its possible transmission to subsequent generations. We review the extent of the problem of preterm birth, prematurity-related pulmonary effects, and the associated increased risk of asthma later in life. We then review the impact of developmental tobacco/nicotine exposure on offspring asthma and the significance of transgenerational pulmonary effects following perinatal tobacco/nicotine exposure, possibly via its effects on germline epigenetics.

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.

Maternal vitamin D status modifies the effects of early life tobacco exposure on child lung function

BACKGROUND

Prior studies suggest that vitamin D may modify the effects of environmental exposures; however, none have investigated gestational vitamin D and cumulative tobacco smoke exposure (TSE) throughout pregnancy and early life.

OBJECTIVES

This study investigated the effects of early life TSE on child lung function and the modulatory effects of gestational vitamin D on this association.

METHODS

The VDAART (Vitamin D Antenatal Asthma Reduction Trial) recruited nonsmoking pregnant women and followed the mother-child pairs to age 6 years. TSE was assessed with questionnaires and plasma cotinine measurements in the mothers (10-18 and 32-38 gestational weeks) and children (1, 3, and 6 years). Cumulative TSE was calculated from the repeated cotinine measurements. 25-hydroxyvitamin D (25[OH]D) levels were measured at 10-18 and 32-38 gestational weeks. Lung function was assessed at 6 years with spirometry and impulse oscillometry.

RESULTS

Of the 476 mother-child pairs, 205 (43%) had increased cotinine levels at ≥1 time point. Cumulative TSE was associated with decreased FEV1 (β = -0.043 L, P = .018) and increased respiratory resistance at 5 Hz (R5; β = 0.060 kPa/L/s, P = .002). This association persisted in subjects with insufficient (<30 ng/mL) 25(OH)D levels throughout pregnancy (β = 0.077 kPa/L/s, P = .016 for R5) but not among those with sufficient levels throughout pregnancy.

CONCLUSIONS

Cumulative TSE from pregnancy to childhood is associated with dose- and duration-dependent decreases in child lung function at 6 years even in the absence of reported maternal smoking. Gestational vitamin D may modulate this effect and have therapeutic potential for minimizing the adverse effect of TSE on lung throughout early life.

RANDOMIZED TRIAL

Maternal Vitamin D Supplementation to Prevent Childhood Asthma (VDAART); clinicaltrials.gov identifier: NCT00920621.

Multi-omic association study identifies DNA methylation-mediated genotype and smoking exposure effects on lung function in children living in urban settings

Impaired lung function in early life is associated with the subsequent development of chronic respiratory disease. Most genetic associations with lung function have been identified in adults of European descent and therefore may not represent those most relevant to pediatric populations and populations of different ancestries. In this study, we performed genome-wide association analyses of lung function in a multiethnic cohort of children (n = 1,035) living in low-income urban neighborhoods. We identified one novel locus at the TDRD9 gene in chromosome 14q32.33 associated with percent predicted forced expiratory volume in one second (FEV1) (p = 2.4x10-9; βz = -0.31, 95% CI = -0.41- -0.21). Mendelian randomization and mediation analyses revealed that this genetic effect on FEV1 was partially mediated by DNA methylation levels at this locus in airway epithelial cells, which were also associated with environmental tobacco smoke exposure (p = 0.015). Promoter-enhancer interactions in airway epithelial cells revealed chromatin interaction loops between FEV1-associated variants in TDRD9 and the promoter region of the PPP1R13B gene, a stimulator of p53-mediated apoptosis. Expression of PPP1R13B in airway epithelial cells was significantly associated the FEV1 risk alleles (p = 1.3x10-5; β = 0.12, 95% CI = 0.06-0.17). These combined results highlight a potential novel mechanism for reduced lung function in urban youth resulting from both genetics and smoking exposure.

Prenatal and Postnatal Cigarette Smoke Exposure Is Associated With Increased Risk of Exacerbated Allergic Airway Immune Responses: A Preclinical Mouse Model

Increased exposure to household air pollution and ambient air pollution has become one of the world’s major environmental health threats. In developing and developed countries, environmental cigarette smoke (CS) exposure is one of the main sources of household air pollution (HAP). Moreover, results from different epidemiological and experimental studies indicate that there is a strong association between HAP, specifically CS exposure, and the development of allergic diseases that often persists into later life. Here, we investigated the impact of prenatal and postnatal CS exposure on offspring susceptibility to the development of allergic airway responses by using a preclinical mouse model. Pregnant BALB/c mice were exposed to either CS or air during pregnancy and lactation and in order to induce allergic asthma the offspring were sensitized and challenged with house dust mite (HDM). Decreased lung function parameters, like dynamic compliance and pleural pressure, were observed in PBS-treated offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. Maternal CS exposure significantly increased the HDM-induced airway eosinophilia and neutrophilia in the offspring. Prenatal and postnatal CS exposure increased the frequency of Th2 cells in the lungs of HDM-treated offspring compared to offspring born to air-exposed mothers. Offspring born to CS-exposed mothers showed increased levels of IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid compared to offspring from air-exposed mothers. Ex-vivo restimulation of lung cells isolated from HDM-treated offspring born to CS-exposed mothers also resulted in increased IL-4 production. Finally, serum immunoglobulins levels of HDM-specific IgE and HDM-specific IgG1 were significantly increased upon a HDM challenge in offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. In summary, our results reveal a biological plausibility for the epidemiological studies indicating that prenatal and postnatal CS exposure increases the susceptibility of offspring to allergic immune responses.

Association between Asthma Control and Exposure to Greenness and Other Outdoor and Indoor Environmental Factors: A Longitudinal Study on a Cohort of Asthmatic Children

Achieving and maintaining asthma control (AC) is the main goal of asthma management. Indoor and outdoor environmental factors may play an important role on AC. The aim of this longitudinal study was to evaluate the association between AC and exposure to greenness and other outdoor or indoor environmental factors in a cohort of asthmatic children. This study involved 179 asthmatic children (5-16 years). Parents were interviewed through a modified version of the SIDRIA questionnaire. AC was assessed at each visit. Exposure to greenness was measured using the normalized difference vegetation index (NDVI). A logistic regression model was applied for assessing risk factors for uncontrolled asthma (UA). Low NDVI exposure was a risk factor for UA (OR: 2.662, 95% CI (1.043-6.799)); children exposed to passive smoke during pregnancy had a higher risk of UA than those non-exposed to passive smoke during pregnancy (OR: 3.816, 95% CI (1.114-13.064)); and a unit increase in the crowding index was associated with an increased risk of UA (OR: 3.376, 95% CI (1.294-8.808)). In conclusion, the current study provided a comprehensive assessment of urban-related environmental exposures on asthma control in children, using multiple indicators of greenness and other outdoor or indoor environmental factors.

Gender differences in specific trends of COPD mortality in Croatia

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is one of the most common lower respiratory chronic diseases. The aim of this study was to analyze the COPD mortality trends in Croatia for the period 2010-2019 and to identify possible changes and differences by age group and gender.

STUDY DESIGN AND METHODS

In data analysis were included COPD death cases for the period 2010-2019 defined as ICD-10 code J44.0 - J44.9. Mortality data were obtained from the Croatian Institute of Public Health based on death certificates. To model temporal changes in mortality rates joinpoint regression analysis was carried out.

RESULTS

The number of COPD deaths increased in men from 878 in 2010 to 1083 in 2019 and in women from 520 in 2010 to 737 in 2019. Over the 10-year period, there was a stable age-standardized COPD mortality rate among men and statistically significant increasing age-standardized COPD mortality rate among women at the national level.

CONCLUSIONS

The findings show a narrowing of the gender gap of COPD mortality. Observed higher COPD mortality rates with age in both men and women confirm previous data and imply that the number of COPD deaths will continue to increase in the future. The healthcare system should focus on the improvement of the quality of care and investment in health promotion and prevention programs aimed at reducing risk factors for COPD, especially tobacco smoking, as well as raising awareness and knowledge about COPD as a chronic disease.

Associations between Second-Hand Tobacco Smoke Exposure and Cardiorespiratory Fitness, Physical Activity, and Respiratory Health in Children

BACKGROUND

Cardiorespiratory fitness (CRF) and physical activity (PA) are associated with a plethora of positive health effects. Many UK children fail to meet the recommended level of PA, with an observed decline in CRF levels over recent decades. Second-hand tobacco smoke (SHS) is responsible for a significant proportion of the worldwide burden of disease, but little is understood regarding the impact of SHS exposure on CRF and PA in children. The aim of this study was to test the associations between SHS exposure and CRF, PA, and respiratory health in children.

METHOD

Children (9-11 years) from UK primary schools in deprived areas participated (n = 104, 38 smoking households). Surveys determined household smoking, and exhaled carbon monoxide was used to indicate children's recent SHS exposure. CRF (VO_2peak) was assessed via maximal treadmill protocol using breath-by-breath analysis. Fractional exhaled nitric oxide and spirometry were utilised as indicators of respiratory health.

RESULTS

Linear regression models demonstrated that SHS exposure was negatively associated with allometrically scaled VO_2peak (B = -3.8, p = 0.030) but not PA or respiratory health.

CONCLUSION

The results indicate that SHS is detrimental to children's CRF; given that approximately one-third of children are regularly exposed to SHS, this important finding has implications for both public health and the sport and exercise sciences.

Supernormal lung function and risk of COPD: A contemporary population-based cohort study

BACKGROUND

Investigation of the natural history of chronic obstructive pulmonary disease (COPD) has led to the recognition that individuals with higher than normal lung function may have lower risk of developing COPD. We tested the hypothesis that individuals with supernormal lung function have lower risk of COPD.

METHODS

We followed 108,246 adults from the Copenhagen General Population Study recruited between 2003 and 2015 for clinical COPD outcomes until 2018. A subset of 16,892 attended another examination approximately 10 years later, allowing to investigate lung function decline and COPD development (forced expiratory volume in 1 se (FEV₁)/forced vital capacity (FVC)<0·70 and FEV₁<80% predicted with chronic respiratory symptom). Supernormal lung function was defined as FEV₁>upper limit of normal (ULN).

FINDINGS

At baseline, 3944(4%) had supernormal lung function, 91,938(85%) normal lung function, and 12,364(11%) had below normal lung function. Individuals with baseline supernormal versus normal lung function had higher FEV₁ decline but did not differ in FEV₁/FVC decline. None had COPD at 10 years in those with supernormal lung function, while 3% had in those with normal lung function. Early-life risk factors associated with COPD development and smoking exposure in different stages of life were less common in individuals with supernormal lung function. Compared to individuals with normal lung function, multivariable adjusted hazard ratios in those with supernormal lung function were 0·19(95% confidence interval:0·08-0·46) for acute obstructive lung disease hospitalisations, 0·56(0·45-0·69) for pneumonia hospitalisations, and 0·81(0·72-0·91) for all-cause mortality.

INTERPRETATION

Supernormal lung function is associated with lower risk of developing COPD.

FUNDING

Herlev and Gentofte Hospital and Lundbeck Foundation.

Effect of prenatal and postnatal exposure to tobacco in the development of acute bronchiolitis in the first two years of life

INTRODUCTION

Environmental exposure to tobacco increases the risk of respiratory disease in infants. However, the impact of maternal smoking on the development of acute bronchiolitis has hardly been assessed. The aim of this study was to determine the incidence of acute bronchiolitis and to analyse the effect of prenatal and postnatal maternal smoking on the development of this disease.

PATIENTS AND METHODS

A prospective, observational study was performed on healthy newborns from a third level hospital born between October 2015 and February 2016. Questionnaires were completed by the mothers at discharge from maternity and followed-up for two years. These collected information about prenatal and postnatal smoking, lifestyle, family and personal history, and the development of bronchiolitis. A bivariate and multivariate logistic regression analysis was performed.

RESULTS

A total of 223 newborns were included, of whom 13.9% were exposed to tobacco smoking during gestation, 21.4% in the postnatal period, and 12.4% in both times. The incidence of bronchiolitis was 28.7% at one year of life, and 34.5% at two years. The multivariate analysis demonstrated that the prenatal and postnatal exposure to tobacco is an independent risk factor for the development of bronchiolitis (OR 4.38; 95% CI; 1.63-11.76), while prolonged breastfeeding is a protective factor (OR 0.13; 95% CI; 0.04-0.48). Other factors that were statistically significant were: atopic dermatitis (OR 2.91; 95% CI; 1.26-6.73), and gestational age (OR 1.42; 95% CI; 1.08-1.88).

CONCLUSIONS

Children exposed to prenatal and postnatal maternal smoking have a higher risk of suffering bronchiolitis. Reducing the smoking habit in women that intend to become pregnant must be a priority in preventive medicine.

Effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children - observational study

Background

Second-hand smoking or environmental tobacco smoke is a critical health risk. Children are the most vulnerable to second-hand smoking because of their small bronchial ducts, less developed immunity, and low-physical activity.

Objectives

The purpose of this study was to ascertain the effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children.

Methods

This observational study included forty-six school-aged children, their age was 8–15 years, assigned to three groups; 2 study groups and 1 control group (n=15). The study groups comprised of 16 football players, and of 15 cyclists. Lung functions were evaluated recording forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow using digital spirometer.

Results

All measures were recorded in definite values and the children were also classified into second-hand smoking (SH), or non-exposed to tobacco smoking (NE). The findings presented a significant increase (p<0.05) of the study groups in forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow solely for the non-exposed children. However, there were non-significant differences between the cyclists and football players or between the passive smoking children and non-exposed children in any of the two study groups (p>0.05).

Conclusion

The outcomes of this study suggest beneficial influences of the sports activity on the lung functions, without different influences of the cyclists and football players on the lung functions.

Sex-specific effects of in utero and adult tobacco smoke exposure

Tobacco smoke has harmful effects on a multiorgan level. Exposure to smoke, whether in utero or environmental, significantly increases susceptibility. This susceptibility has been identified to be divergent between males and females. However, there remains a distinct lack of thorough research into the relationship between sex and exposure to tobacco. Females tend to generate a more significant response than males during adulthood exposure. The intrauterine environment is meticulously controlled, and exposure to tobacco presents a significant factor that contributes to poor health outcomes and susceptibility later in life. Analysis of these effects in relation to the sex of the offspring is yet to be holistically reviewed and summarized. In this review, we will delineate the time-dependent relationship between tobacco smoke exposure and sex-specific disease susceptibility. We further outline possible biological mechanisms that may contribute to the identified pattern.

A prenatally disrupted airway epithelium orchestrates the fetal origin of asthma in mice

BACKGROUND

Prenatal challenges such as maternal stress perception increase the risk and severity of asthma during childhood. However, insights into the trajectories and targets underlying the pathogenesis of prenatally triggered asthma are largely unknown. The developing lung and immune system may constitute such targets.

OBJECTIVE

Here we have aimed to identify the differential sex-specific effects of prenatal challenges on lung function, immune response, and asthma severity in mice.

METHODS

We generated bone marrow chimeric (BMC) mice harboring either prenatally stress-exposed lungs or a prenatally stress-exposed immune (hematopoietic) system and induced allergic asthma via ovalbumin. Next-generation sequencing (RNA sequencing) of lungs and assessment of airway epithelial barrier function in ovalbumin-sensitized control and prenatally stressed offspring was also performed.

RESULTS

Profoundly enhanced airway hyperresponsiveness, inflammation, and fibrosis were exclusively present in female BMC mice with prenatally stress-exposed lungs. These effects were significantly perpetuated if both the lungs and the immune system had been exposed to prenatal stress. A prenatally stress-exposed immune system alone did not suffice to increase the severity of these asthma features. RNA sequencing analysis of lungs from prenatally stressed, non-BMC, ovalbumin-sensitized females unveiled a deregulated expression of genes involved in asthma pathogenesis, tissue remodeling, and tight junction formation. It was also possible to independently confirm a tight junction disruption. In line with this, we identified an altered perinatal and/or postnatal expression of genes involved in lung development along with an impaired alveolarization in female prenatally stressed mice.

CONCLUSION

Here we have shown that the fetal origin of asthma is orchestrated by a disrupted airway epithelium and further perpetuated by a predisposed immune system.

Glutathione S-Transferase Genotype Protects against In Utero Tobacco-linked Lung Function Deficits

Rationale: In utero tobacco exposure is associated with reduced lung function from infancy. Antioxidant enzymes from the glutathione S-transferase (GST) family may protect against these lung function deficits.Objectives: To assess the long-term effect of in utero smoke exposure on lung function into adulthood, and to assess whether GSTT1 and GSTM1 active genotypes have long-term protective effects on lung function.Methods: In this longitudinal study based on a general population (n = 253), lung function was measured during infancy and at 6, 11, 18, and 24 years. GSTM1 and GSTT1 genotype was analyzed in a subgroup (n = 179). Lung function was assessed longitudinally from 6 to 24 years (n = 199).Measurements and Main Results: Exposure to maternal in utero tobacco was associated with lower FEV₁ and FVC longitudinally from 6 to 24 years (mean difference, -3.87% predicted, P = 0.021; -3.35% predicted, P = 0.035, respectively). Among those homozygous for the GSTM1-null genotype, in utero tobacco exposure was associated with lower FEV₁ and FVC compared with those with no in utero tobacco exposure (mean difference, -6.2% predicted, P = 0.01; -4.7% predicted, P = 0.043, respectively). For those with GSTM1 active genotype, there was no difference in lung function whether exposed to maternal in utero tobacco or not. In utero tobacco exposure was associated with deficits in lung function among those with both GSTT1-null and GSTT1-active genotypes.Conclusions: Certain GST genotypes may have protective effects against the long-term deficits in lung function associated with in utero tobacco exposure. This offers potential preventative targets in antioxidant pathways for at-risk infants of smoking mothers.

Interaction of Glutathione S-Transferase M1, T1, and P1 Genes With Early Life Tobacco Smoke Exposure on Lung Function in Adolescents

BACKGROUND

Glutathione S-transferase (GST) genes are involved in the management of oxidative stress in the lungs. We aimed to determine whether they modify the associations between early life smoke exposure and adverse lung health outcomes.

METHODS

The Melbourne Atopy Cohort study (a high-risk birth cohort) enrolled 620 children and followed them prospectively from birth. We recorded perinatal tobacco smoke exposure, asthma, and lung function at 12 (59%) and 18 years (66%) and genotyped for GSTM1, GSTT1, and GSTP1 (69%).

RESULTS

GST genotypes were found to interact with tobacco smoke exposure on lung function outcomes (P interaction ≤ .05). Only among children with GSTT1 null genotypes was exposure to mother's, father's, or parental tobacco smoke in early life associated with an increased risk of reductions in prebronchodilator (BD) FEV₁ and FVC at both 12 and 18 years. These associations were not seen in children with GSTT1 present. Similarly, only among children with GSTM1 null genotypes was exposure to father's or parental smoking associated with reductions in pre- and post-BD FEV₁ and FVC at 18 years. Only among children with Ile/Ile genotypes of GSTP1 was exposure to mother's smoking associated with increased risk of reduced FEV₁ at 18 years, but this was not the case among children with Val/Val or Ile/Val genotypes.

CONCLUSIONS

Our study provides evidence of interaction between early tobacco smoke exposure and GST genotypes on lung function. Carriers of GST null mutations and GSTP1 Ile/Ile alleles may be more susceptible when exposed to tobacco smoke in early life. These findings support stronger recommendations to protect all infants from tobacco smoke exposure.

TRIAL REGISTRY

Australian and New Zealand Clinical Trials Registry; No.: ACTRN12609000734268; URL: http://www.anzctr.org.au/.

The impact of perinatal nicotine exposure on fetal lung development and subsequent respiratory morbidity

Maternal smoking during pregnancy remains as a significant public health crisis as it did decades ago. Although its prevalence is decreasing in high-income countries, it has worsened globally, along with a concerning emergence of electronic-cigarette usage within the last two decades. Extensive epidemiologic and experimental evidence exists from both human and animal studies, demonstrating the detrimental long-term pulmonary outcomes in the offspring of mothers who smoke during pregnancy. Even secondhand and thirdhand smoke exposure to the developing lung might be as or even more harmful than firsthand smoke exposure. Furthermore, these effects are not limited only to the exposed progeny, but can also be transmitted transgenerationally. There is compelling evidence to support that the majority of the effects of perinatal smoke exposure on the developing lung, including the transgenerational transmission of asthma, is mediated by nicotine. Nicotine exposure induces cell-specific molecular changes in lungs, which offers a unique opportunity to prevent, halt, and/or reverse the resultant damage through targeted molecular interventions. Experimentally, the proposed interventions, such as administration of peroxisome proliferator-activated receptor gamma (PPARγ) agonists can not only block but also potentially reverse the perinatal nicotine exposure-induced respiratory morbidity in the exposed offspring. However, the development of a safe and effective intervention is still many years away. In the meantime, electropuncture at specific acupoints appears to be emerging as a more practical and safe physiologic approach to block the harmful pulmonary consequences of perinatal nicotine exposure.

The child with an incessant dry cough

Cough is a forced expulsive manoeuvre, usually against a closed glottis and is associated with a characteristic sound that is easily recognised. It is a protective reflex against aspiration and to clear airway secretions. In children cough is extremely common and when prolonged it is often a cause for concern for parents, resulting in a high proportion of attendances to primary and secondary care. There are many causes of cough which may be divided into productive or non-productive in character. As there are many guidelines for the management of productive or 'wet' cough the focus of this paper will be to discuss some of the main causes, investigations and management options for 'dry' cough. Dry coughing suggests airway irritation and or inflammation (without excessive extra secretion formation) and is predominantly the result of an acute viral respiratory infection that may last up to 3-4 weeks.

Epigenetic impacts of maternal tobacco and e-vapour exposure on the offspring lung

In utero exposure to tobacco products, whether maternal or environmental, have harmful effects on first neonatal and later adult respiratory outcomes. These effects have been shown to persist across subsequent generations, regardless of the offsprings' smoking habits. Established epigenetic modifications induced by in utero exposure are postulated as the mechanism underlying the inherited poor respiratory outcomes. As e-cigarette use is on the rise, their potential to induce similar functional respiratory deficits underpinned by an alteration in the foetal epigenome needs to be explored. This review will focus on the functional and epigenetic impact of in utero exposure to maternal cigarette smoke, maternal environmental tobacco smoke, environmental tobacco smoke and e-cigarette vapour on foetal respiratory outcomes.

Life Cycle of Childhood Asthma: Prenatal, Infancy and Preschool, Childhood, and Adolescence

Asthma is a heterogeneous developmental disorder influenced by complex interactions between genetic susceptibility and exposures. Wheezing in infancy and early childhood is highly prevalent, with a substantial minority of children progressing to established asthma by school age, most of whom are atopic. Adolescence is a time of remission of symptoms with persistent lung function deficits. The transition to asthma in adulthood is not well understood.

Perinatal exposure to environmental tobacco smoke is associated with changes in DNA methylation that precede the adult onset of lung disease in a mouse model

Prenatal and early-life environmental tobacco smoke (ETS) exposure can induce epigenetic alterations associated with inflammation and respiratory disease. The objective of this study was to address the long-term epigenetic consequences of perinatal ETS exposure on latent respiratory disease risk, which are still largely unknown. C57BL/6 mice were exposed to prenatal and early-life ETS; offspring lung pathology, global DNA, and gene-specific methylation were measured at two adult ages. Significant alterations in global DNA methylation and promoter methylation of IFN-γ and Thy-1 were found in ETS-exposed offspring at 10-12 and 20 weeks of age. These sustained epigenetic alterations preceded the onset of significant pulmonary pathologies observed at 20 weeks of age. This study suggests that perinatal ETS exposure induces persistent epigenetic alterations in global DNA, as well as IFN-γ and Thy-1 promoter methylation that precede the adult onset of fibrotic lung pathology. These epigenetic findings could represent potential biomarkers of latent respiratory disease risk.

Effects of ambient air pollution from municipal solid waste landfill on children's non-specific immunity and respiratory health

This cross-sectional study investigated the association between air pollutant (AP) and respiratory health of 951 children residing near a municipal solid waste (MSW) landfill in Northern China. Results showed that students in non-exposure areas had significantly higher levels of lysozyme, secretory immunoglobulin A (SIgA), and better lung capacity than students in exposure areas (p < .05). Multiple regression model analysis indicated that lysozyme levels exhibited a consistent negative association with methane (CH₄: β = -76.3, 95% CI -105 to -47.7) and sulfuretted hydrogen (H₂S: β = -11.7, 95% CI -20.2 to -3.19). In addition, SIgA levels were negatively associated with H₂S (β = -68.9, 95% CI -97.9 to -39.9) and ammonia (NH₃: β = -30.3, 95% CI -51.7 to -8.96). Among all AP, H₂S and sulfur dioxide (SO₂) were the most robustly related with reduced lung function. H₂S exposure was negatively associated with six lung function indices, 1-s forced expiratory volume (FEV1%), mean forced expiratory flow between 25% and 75% (MMF), maximum voluntary ventilation (MVV), and forced expiratory flow at 25%, 50%, and 75% of the pulmonary volume (FEF25, FEF50, FEF75); and SO₂ was negatively associated with FEV1%, MVV, FEF25, FEF50 and FEF75. Our results suggested that AP exposure was negatively associated with more lung function parameters in boys than in girls. In conclusion, our findings suggested that children living adjacent to landfill sites were more likely to have deficient non-specific immunity and impaired lung function.

Sex-specific lung functional changes in adult mice exposed only to second-hand smoke in utero

Background

An increasing number of epidemiological and experimental studies have associated exposure to second-hand smoke (SHS) during pregnancy with adverse outcomes in newborns. As we have previously shown in mice, in utero exposure to SHS at critical stages of fetal development, results in altered lung responses and increased disease susceptibility upon re-exposure to irritants (SHS or ovalbumin) in adulthood. In this study, we asked whether the in utero SHS exposure alone is sufficient to alter lung structure and function in adult mice.

Methods

Pregnant BALB/c mice were exposed from days 6 to 19 of pregnancy to 10 mg/m³ of SHS or HEPA-filtered air. Male and female offspring (n = 13–15/group) were sacrificed at 15 weeks of age. We measured lung function with non-invasive and invasive methods, performed lung morphometric analysis on trichrome-stained lung tissue samples, and assessed lung gene expression via RNA sequencing and protein assays.

Results

In utero SHS exposure significantly increased mean linear intercept and decreased the surface area per unit volume of the lungs in both males and females, indicating perturbation in alveolar developmental processes. Tidal volume, minute volume and inspiratory capacity were significantly decreased compared with the controls only in male mice exposed in utero to SHS, suggesting that males are more sensitive than females to an SHS insult during lung development. This also suggests that in our model, lung structure changes may be necessary but are not sufficient to impair lung function. SERPINA1A, the mouse ortholog of human α1-antitrypsin, deficiency of which is a known genetic risk factor for emphysema, was down-regulated at the protein level in the in utero SHS-exposed mice. Additionally, DNMT3A protein expression was dysregulated, indicating that DNA methylation occurred in the lungs.

Conclusions

Our results indicate that in utero SHS exposure alone alters both lung function and structure well into adulthood (15 weeks) in male mice. Furthermore, lung function alterations in this model are sex-specific, with males being more susceptible to in utero SHS effects. Overall, our data suggest that in utero SHS exposure alone can predispose to adult lung diseases.

Prenatal exposure to tobacco smoke sex dependently influences methylation and mRNA levels of the Igf axis in lungs of mouse offspring

Prenatal smoke exposure is a risk factor for abnormal lung development and increased sex-dependent susceptibility for asthma and chronic obstructive pulmonary disease (COPD). Birth cohort studies show genome-wide DNA methylation changes in children from smoking mothers, but evidence for sex-dependent smoke-induced effects is limited. The insulin-like growth factor (IGF) system plays an important role in lung development. We hypothesized that prenatal exposure to smoke induces lasting changes in promoter methylation patterns of Igf1 and Igf1r, thus influencing transcriptional activity and contributing to abnormal lung development. We measured and compared mRNA levels along with promoter methylation of Igf1 and Igf1r and their protein concentrations in lung tissue of 30-day-old mice that had been prenatally exposed to cigarette smoke (PSE) or filtered air (control). Body weight at 30 days after birth was measured as global indicator of normal development. Female PSE mice showed lower mRNA levels of Igf1 and its receptor (Igf1: P = 0.05; Igf1r: P = 0.03). Furthermore, CpG-site-specific methylation changes were detected in Igf1r in a sex-dependent manner and the body weight of female offspring was reduced after prenatal exposure to smoke, while protein concentrations were unaffected. Prenatal exposure to smoke induces a CpG-site-specific loss of Igf1r promoter methylation, which can be associated with body weight. These findings highlight the sex-dependent and potentially detrimental effects of in utero smoke exposure on DNA methylation and Igf1 and Igf1r mRNA levels. The observations support a role for Igf1 and Igf1r in abnormal development.

Pulmonary Effects of Maternal Smoking on the Fetus and Child: Effects on Lung Development, Respiratory Morbidities, and Life Long Lung Health

Maternal smoking during pregnancy is the largest preventable cause of abnormal in-utero lung development. Despite well known risks, rates of smoking during pregnancy have only slightly decreased over the last ten years, with rates varying from 5-40% worldwide resulting in tens of millions of fetal exposures. Despite multiple approaches to smoking cessation about 50% of smokers will continue to smoke during pregnancy. Maternal genotype plays an important role in the likelihood of continued smoking during pregnancy and the degree to which maternal smoking will affect the fetus. The primary effects of maternal smoking on offspring lung function and health are decreases in forced expiratory flows, decreased passive respiratory compliance, increased hospitalization for respiratory infections, and an increased prevalence of childhood wheeze and asthma. Nicotine appears to be the responsible component of tobacco smoke that affects lung development, and some of the effects of maternal smoking on lung development can be prevented by supplemental vitamin C. Because nicotine is the key agent for affecting lung development, e-cigarette usage during pregnancy is likely to be as dangerous to fetal lung development as is maternal smoking.

Early smoke exposure is associated with asthma and lung function deficits in adolescents

OBJECTIVE

Early life tobacco smoke exposure may influence asthma, lung function and lung function growth into adolescence. We aimed to determine the associations between perinatal smoke exposure and asthma and lung function up to 18 years of age.

METHODS

We prospectively recorded perinatal parental smoking and measured respiratory outcomes at 12 and 18 years in the Melbourne Atopy Cohort Study (MACS), a longitudinal birth cohort. Multiple logistic regression was used to analyse the associations between perinatal smoke exposure and asthma at 12 (n = 370) and 18 years (n = 411). Multiple linear regression was used to investigate the relationship between perinatal smoking and: lung function (12 and 18 years) and lung function growth (between 12 and 18 years).

RESULTS

At 18 years, girls exposed to parental smoking during the perinatal period had increased odds of asthma (OR: 3.45, 95%CI: 1.36, 8.77), reduced pre-bronchodilator Forced expiratory volume in one-second (FEV₁) (-272 ml/s; -438, -107); FEV₁/ forced vital capacity (FVC) (-0.038; -0.065, -0.010); mid expiratory flow (MEF_25-75) (-430 ml/s; -798, -61), and reduced post-bronchodilator FEV₁/FVC (-0.028, -0.053, -0.004). No associations were found for boys (pre-bronchodilator FEV₁ 26ml/s; -202, 255; FEV₁/FVC 0.018; -0.013, 0.049).

CONCLUSIONS

Perinatal smoke may affect risk of asthma, reduce lung function and lung function growth in adolescence. Girls appear to be more susceptible than boys.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Prenatal Versus Postnatal Tobacco Smoke Exposure and Intensive Care Use in Children Hospitalized With Bronchiolitis

OBJECTIVE

Among children hospitalized with bronchiolitis, we examined the associations between in utero exposure to maternal cigarette smoking, postnatal tobacco smoke exposure, and risk of admission to the intensive care unit (ICU).

METHODS

We performed a 16-center, prospective cohort study of hospitalized children aged <2 years with a physician admitting diagnosis of bronchiolitis. For 3 consecutive years, from November 1, 2007 until March 31, 2010, site teams collected data from participating families, including information about prenatal maternal smoking and postnatal tobacco exposure. Analyses used chi-square, Fisher's exact, and Kruskal-Wallis tests and multivariable logistic regression.

RESULTS

Among 2207 enrolled children, 216 (10%) had isolated in utero exposure to maternal smoking, 168 (8%) had isolated postnatal tobacco exposure, and 115 (5%) experienced both. Adjusting for age, sex, race, birth weight, viral etiology, apnea, initial severity of retractions, initial oxygen saturation, oral intake, and postnatal tobacco exposure, children with in utero exposure to maternal smoking had greater odds of being admitted to the ICU (adjusted odds ratio [aOR] 1.51, 95% confidence interval [CI] 1.14-2.00). Among children with in utero exposure to maternal smoking, those with additional postnatal tobacco exposure had a greater likelihood of ICU admission (aOR 1.95, 95% CI 1.13-3.37) compared to children without postnatal tobacco smoke exposure (aOR 1.47, 95% CI 1.05-2.04).

CONCLUSIONS

Maternal cigarette smoking during pregnancy puts children hospitalized with bronchiolitis at significantly higher risk of intensive care use. Postnatal tobacco smoke exposure may exacerbate this risk. Health care providers should incorporate this information into counseling messages.

Maternal smoking in pregnancy and its influence on childhood asthma

Maternal smoking in pregnancy (MSP) is a large modifiable risk factor for pregnancy related mortality and morbidity and also the most important known modifiable risk factor for asthma. This review summarises the effects of MSP throughout infancy, childhood and adolescence with regards to asthma (development and severity). Firstly, the direct damage caused by nicotine on fetal lung development, fetal growth and neuronal differentiation is discussed, as well as the indirect effects of nicotine on placental functioning. Secondly, the effects of MSP on later immune functioning resulting in increased infection rate are summarised and details are given on the effects of MSP modulating airway hyperreactivity, reducing lung function and therefore increasing asthma morbidity. Furthermore, epigenetic effects are increasingly being recognised. These can also result in transgenerational detrimental effects induced by cigarette smoke. In summary, the causal relationship between MSP and asthma development is well documented and presents a major health problem for generations to come. The high prevalence of MSP is alarming and epigenetic effects of nicotine on immune functioning potentiate this danger. A considerable part of the increase in asthma prevalence worldwide is due to MSP.

Heavy Cigarette Smokers in a Chinese Population Display a Compromised Permeability Barrier

Cigarette smoking is associated with various cutaneous disorders with defective permeability. Yet, whether cigarette smoking influences epidermal permeability barrier function is largely unknown. Here, we measured skin biophysical properties, including permeability barrier homeostasis, stratum corneum (SC) integrity, SC hydration, skin surface pH, and skin melanin/erythema index, in cigarette smokers. A total of 99 male volunteers were enrolled in this study. Smokers were categorized as light-to-moderate (<20 cigarettes/day) or heavy smokers (≥20 cigarettes/day). An MPA5 was used to measure SC hydration and skin melanin/erythema index on the dorsal hand, forehead, and cheek. Basal transepidermal water loss (TEWL) and barrier recovery rates were assessed on the forearm. A Skin-pH-Meter pH900 was used to measure skin surface pH. Our results showed that heavy cigarette smokers exhibited delayed barrier recovery after acute abrogation (1.02% ± 13.06 versus 16.48% ± 6.07), and barrier recovery rates correlated negatively with the number of daily cigarettes consumption (p = 0.0087). Changes in biophysical parameters in cigarette smokers varied with body sites. In conclusion, heavy cigarette smokers display compromised permeability barrier homeostasis, which could contribute, in part, to the increased prevalence of certain cutaneous disorders characterized by defective permeability. Thus, improving epidermal permeability barrier should be considered for heavy cigarette smokers.

Sex and the lung: Observations, hypotheses, and future directions

Sex-related differences in a variety of lung diseases in infants and young children are reviewed, including respiratory distress syndrome, and chronic lung disease of prematurity, lower respiratory tract illnesses and wheezing, asthma, diffuse, and interstitial lung diseases, and cystic fibrosis. Differences in anatomy and physiology, such as airway size, airway muscle bulk, airway reactivity, airway tone, and cough reflexes may explain much of these sex differences. Better understanding of sex-related lung differences could help personalize respiratory treatment.

Environmental Pollution and the Developing Lung

In this review, we discuss the impact of environmental tobacco smoke and particulate and gaseous air pollutants derived from fossil fuel combustion on a particularly vulnerable population, infants and children. Indoor and outdoor air pollutants exacerbate chronic respiratory diseases and lower respiratory tract infections. However, there is an even more alarming impact of antenatal air pollution exposures. There are several reports in rodents and monkeys that maternal exposure to tobacco smoke or fossil fuel-generated air pollutants causes in utero growth retardation, lung remodeling, and immune cell activation which increase the risk for asthma or the risk of morbidity with respiratory infections. Importantly, epidemiologic studies confirm that maternal exposure to air pollutants decreases lung function in infants and children which may persist to young adulthood. Thus, environmental air pollutants contribute to childhood origins of chronic obstructive lung disease by changing the capacity for normal lung development and repair, by promoting early lung inflammation which increases the susceptibility to pollution-triggered symptomatic lung disease in adulthood, and by limiting the capacity for later adaptive/repair responses to environmental and infectious insults.

Grandmother's smoking when pregnant with the mother and asthma in the grandchild: the Norwegian Mother and Child Cohort Study

BACKGROUND

A trans-generational influence of prenatal tobacco smoke exposure on asthma development has been proposed but the evidence remains sparse.

METHODS

We examined the grandmother's smoking when pregnant with the mother in relation to asthma outcomes in the grandchild (current asthma at 36 months (N=53 169, cases=3013), current asthma at 7 years (N=25 394, cases=1265) and dispensed asthma medications at 7 years in the Norwegian Prescription Database (N=45 607, cases=1787)) within the Norwegian Mother and Child Cohort Study (MoBa). We calculated adjusted RR (adj. RR) and 95% CIs using log binomial regression.

RESULTS

A total of 23.5% of mothers reported that their mother smoked when pregnant with them. The grandmother's smoking when pregnant with the mother was positively associated with asthma at 36 months (adj. RR 1.15 (95% CI 1.06 to 1.24)), asthma at 7 years (adj. RR 1.21 (95% CI 1.07 to 1.37)) and dispensed asthma medications at 7 years (adj. RR 1.15 (95% CI 1.04 to 1.26)). This positive association did not differ significantly by the mother's smoking status when pregnant with the child (p values for multiplicative interaction >0.1).

CONCLUSIONS

The grandmother's smoking when pregnant with the mother increased the risk of asthma in the grandchild independent of the mother's smoking status. However, given limited information on the grandmother's socioeconomic status, asthma status and other factors, unmeasured confounding may be present.

Genetics of allergic diseases

Genome-wide association studies (GWAS) have been employed in the field of allergic disease, and significant associations have been published for nearly 100 asthma genes/loci. An outcome of GWAS in allergic disease has been the formation of national and international collaborations leading to consortia meta-analyses, and an appreciation for the specificity of genetic associations to sub-phenotypes of allergic disease. Molecular genetics has undergone a technological revolution, leading to next-generation sequencing strategies that are increasingly employed to hone in on the causal variants associated with allergic diseases. Unmet needs include the inclusion of diverse cohorts and strategies for managing big data.

Prenatal tobacco smoke exposure is associated with childhood DNA CpG methylation

Background

Smoking while pregnant is associated with a myriad of negative health outcomes in the child. Some of the detrimental effects may be due to epigenetic modifications, although few studies have investigated this hypothesis in detail.

Objectives

To characterize site-specific epigenetic modifications conferred by prenatal smoking exposure within asthmatic children.

Methods

Using Illumina HumanMethylation27 microarrays, we estimated the degree of methylation at 27,578 distinct DNA sequences located primarily in gene promoters using whole blood DNA samples from the Childhood Asthma Management Program (CAMP) subset of Asthma BRIDGE childhood asthmatics (n = 527) ages 5–12 with prenatal smoking exposure data available. Using beta-regression, we screened loci for differential methylation related to prenatal smoke exposure, adjusting for gender, age and clinical site, and accounting for multiple comparisons by FDR.

Results

Of 27,578 loci evaluated, 22,131 (80%) passed quality control assessment and were analyzed. Sixty-five children (12%) had a history of prenatal smoke exposure. At an FDR of 0.05, we identified 19 CpG loci significantly associated with prenatal smoke, of which two replicated in two independent populations. Exposure was associated with a 2% increase in mean CpG methylation in FRMD4A (p = 0.01) and Cllorf52 (p = 0.001) compared to no exposure. Four additional genes, XPNPEP1, PPEF2, SMPD3 and CRYGN, were nominally associated in at least one replication group.

Conclusions

These data suggest that prenatal exposure to tobacco smoke is associated with reproducible epigenetic changes that persist well into childhood. However, the biological significance of these altered loci remains unknown.

Respiratory outcomes for the tiniest or most immature infants

Extremely low birth weight (<1000 g birth weight) or extremely preterm (<28 weeks of gestation) infants are surviving in greater numbers as neonatal care advances. Many of these survivors, especially those who develop bronchopulmonary dysplasia, have more respiratory ill health in the first years after discharge home, reduced respiratory function and impaired exercise capacity throughout childhood and into adulthood compared with term-born controls. It is important to establish the long-term respiratory outcomes for the tiniest or most immature survivors as they grow older, since they may contribute disproportionately to rates of chronic obstructive pulmonary disease and respiratory ill-health in adulthood.

The genomic origins of asthma

Lung function tracks from the earliest age that it can be reliably measured. Genome wide association studies suggest that most variants identified for common complex traits are regulatory in function and active during fetal development. Fetal programming of gene expression during development is critical to the formation of a normal lung. An understanding of how fetal developmental genes related to diseases of the lungs and airways is a critical area for research. This review article considers the developmental origins hypothesis, the stages of normal lung development and a variety of environmental exposures that might influence the developmental process: in utero cigarette smoke exposure, vitamin D and folate. We conclude with some information on developmental genes and asthma.

The effects of low-level environmental tobacco smoke exposure on pulmonary function tests in preschool children with asthma

OBJECTIVES

Though parents of children with asthma smoke, they often avoid smoking in their homes or near their children, thus limiting exposure. It is not known if such low-level environmental tobacco smoke (ETS) results in measurable exposure or affects lung function. The objectives of this study were to measure urinary cotinine in preschool children with asthma, and to examine the relationship between low-level ETS exposure and pulmonary function tests (PFTs).

METHODS

Preschool children with asthma were enrolled. Parents completed questionnaires on ETS exposure and asthma control, urinary cotinine concentrations were measured and PFTs were compared between subjects with and without recent ETS exposure.

RESULTS

Forty one subjects were enrolled. All parents denied smoking in their home within the last 2 weeks, but 14 (34%) parents admitted to smoking outside their homes or away from their children. Fifteen (37%; 95%CI: 23-53) of the children had urinary cotinine levels ≥1 ng/ml, of which seven (17%; 95%CI: 8-32) had levels ≥5 ng/ml. FEV1 and FEV0.5 were lower in subjects with a urinary cotinine level ≥5 ng/ml as compared to those with levels <1 ng/ml or between 1 and 5 ng/ml; both at baseline and after inhalation of albuterol. Five of seven subjects with urinary cotinine levels ≥5 ng/ml had FEV0.5 less than 65% of predicted values. There were no significant differences in IOS measures.

CONCLUSIONS

Despite parental denial of smoking near their children, preschool children may be exposed to ETS. Such low-level ETS exposure may affect lung function, possibly in a dose-dependent manner.

Environmental tobacco smoke and airway obstruction in children with sickle cell anemia

BACKGROUND

The contribution of environmental tobacco smoke (ETS) exposure to pulmonary morbidity in children with sickle cell anemia (SCA) is poorly understood. We tested the hypothesis that children with SCA and ETS exposure would have an increased prevalence of obstructive lung disease and respiratory symptoms compared with children with SCA and no ETS exposure.

METHODS

Parent reports of ETS and respiratory symptom frequency were obtained for 245 children with SCA as part of a multicenter prospective cohort study. One hundred ninety-six children completed pulmonary function testing. Multivariable regression models were used to evaluate the associations between ETS exposure at different time points (prenatal, infant [birth to 2 years], preschool [2 years to first grade], and current) and lung function and respiratory symptoms.

RESULTS

Among the 245 participants, a high prevalence of prior (44%) and current (29%) ETS exposure was reported. Of the 196 children who completed pulmonary function testing, those with parent-reported infant and current ETS exposure were more likely to have airway obstruction (defined as an FEV1/FVC ratio below the lower limit normal) compared with unexposed children (22.0% vs 3.1%, P &lt; .001). Those with ETS exposure also had a lower forced expiratory flow, midexpiratory phase/FVC ratio (0.82 vs 0.97, P = .001) and were more likely to have evidence of bronchodilator responsiveness (23% vs 11%, P = .03). Current and prior ETS exposure and in utero smoke exposure were associated with increased frequency of respiratory symptoms.

CONCLUSIONS

ETS exposure is associated with evidence of lower airway obstruction and increased respiratory symptoms in SCA.

Long-term exposure to PM10 and NO2 in association with lung volume and airway resistance in the MAAS birth cohort

BACKGROUND

Findings from previous studies on the effects of air pollution exposure on lung function during childhood have been inconsistent. A common limitation has been the quality of exposure data used, and few studies have modeled exposure longitudinally throughout early life.

OBJECTIVES

We sought to study the long-term effects of exposure to particulate matter with an aerodynamic diameter ≤ 10 μm (PM10) and to nitrogen dioxide (NO2) on specific airway resistance (sR(aw)) and forced expiratory volume in 1 sec (FEV1) before and after bronchodilator treatment. Subjects were from the Manchester Asthma and Allergy Study (MAAS) birth cohort (n = 1,185).

METHODS

Spirometry was performed during clinic visits at ages 3, 5, 8, and 11 years. Individual-level PM10 and NO2 exposures were estimated from birth to 11 years of age through a microenvironmental exposure model. Longitudinal and cross-sectional associations were estimated using generalized estimating equations and multivariable linear regression models.

RESULTS

Lifetime exposure to PM10 and NO2 was associated with significantly less growth in FEV1 (percent predicted) over time, both before (-1.37%; 95% CI: -2.52, -0.23 for a 1-unit increase in PM10 and -0.83%; 95% CI: -1.39, -0.28 for a 1-unit increase in NO2) and after bronchodilator treatment (-3.59%; 95% CI: -5.36, -1.83 and -1.20%; 95% CI: -1.97, -0.43, respectively). We found no association between lifetime exposure and sR(aw) over time. Cross-sectional analyses of detailed exposure estimates for the summer and winter before 11 years of age and lung function at 11 years indicated no significant associations.

CONCLUSIONS

Long-term PM10 and NO2 exposures were associated with small but statistically significant reductions in lung volume growth in children of elementary-school age.

Effects of parental and household smoking on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm infants and the potential impact of RSV prophylaxis

OBJECTIVE

To assess the impact of household smoking and palivizumab prophylaxis on the risk of respiratory syncytial virus (RSV) hospitalisation in late-preterm (32-35 weeks' gestational age) infants.

METHODS

Familial smoking and other RSV risk factor data from the FLIP, FLIP-2 and IMpact studies and datasets from France, Germany and Italy, together with palivizumab prophylaxis data from the FLIP-2 and IMpact studies, were analysed using cross-correlation and Bayesian meta-analytical modelling employing Markov Chain Monte Carlo sampling.

RESULTS

There were 2.35 times (95% confidence interval [CI] 1.37-4.02) as many hospitalisations amongst infants from smoking compared with those from non-smoking families. Among non-prophylaxed infants, there were 2.53 times (95% CI 1.27-4.94) as many RSV hospitalisations from smoking than from non-smoking families and that excess hospitalisation was reduced to 1.03 times (95% CI 0.38-2.99) amongst prophylaxed infants. Familial smoking correlates significantly (p < 0.01) with other RSV risk factors: positive correlation with number of school-age siblings, history of family atopy, family wheeze and gestational age; negative correlation with birth weight and breast feeding.

CONCLUSIONS

Late-preterm infants from smoking families appear to be at heightened risk for severe RSV infection requiring hospitalisation of which the risk may be reduced with RSV prophylaxis.

In utero exposure to second-hand smoke aggravates adult responses to irritants: adult second-hand smoke

In utero exposure to second-hand smoke (SHS) is associated with exacerbated asthmatic responses in children. We tested the hypothesis that in utero SHS will aggravate the lung responses of young adult mice re-exposed to SHS. We exposed Balb/c mice in utero to SHS (S) or filtered air (AIR; A), and re-exposed the male offspring daily from 11-15 weeks of age to either SHS (AS and SS) or AIR (AA and SA). After the adult exposures, we analyzed samples of bronchoalveolar lavage fluid (BALF), examined the results of histopathology, and assessed pulmonary function and gene expression changes in lung samples. In SS mice, compared with the other three groups (AA, AS, and SA), we found decreases in breathing frequency and increases in airway hyperresponsiveness (AHR), as well as low but significantly elevated concentrations of BALF proinflammatory cytokines (IL-1b, IL-6, and keratinocyte-derived chemokine). Lung morphometric analyses revealed enlarged airspaces and arteries in SA and SS mice compared with their in utero AIR counterparts, as well as increased collagen deposition in AS and SS mice. Unique gene expression profiles were found for in utero, adult, and combined exposures, as well as for mice with elevated AHR responses. The profibrotic metalloprotease genes, Adamts9 and Mmp3, were up-regulated in the SS and AHR groups, suggesting a role for in utero SHS exposure on the adult development of chronic obstructive pulmonary disease. Our results indicate that in utero exposures to environmentally relevant concentrations of SHS alter lung structure more severely than do adult SHS exposures of longer duration. These in utero exposures also aggravate AHR and promote a profibrotic milieu in adult lungs.

Prospective multicenter study of children with bronchiolitis requiring mechanical ventilation

OBJECTIVE

To identify factors associated with continuous positive airway pressure (CPAP) and/or intubation for children with bronchiolitis.

METHODS

We performed a 16-center, prospective cohort study of hospitalized children aged <2 years with bronchiolitis. For 3 consecutive years from November 1 until March 31, beginning in 2007, researchers collected clinical data and a nasopharyngeal aspirate from study participants. We oversampled children from the ICU. Samples of nasopharyngeal aspirate were tested by polymerase chain reaction for 18 pathogens.

RESULTS

There were 161 children who required CPAP and/or intubation. The median age of the overall cohort was 4 months; 59% were male; 61% white, 24% black, and 36% Hispanic. In the multivariable model predicting CPAP/intubation, the significant factors were: age <2 months (odds ratio [OR] 4.3; 95% confidence interval [CI] 1.7-11.5), maternal smoking during pregnancy (OR 1.4; 95% CI 1.1-1.9), birth weight <5 pounds (OR 1.7; 95% CI 1.0-2.6), breathing difficulty began <1 day before admission (OR 1.6; 95% CI 1.2-2.1), presence of apnea (OR 4.8; 95% CI 2.5-8.5), inadequate oral intake (OR 2.5; 95% CI 1.3-4.3), severe retractions (OR 11.1; 95% CI 2.4-33.0), and room air oxygen saturation <85% (OR 3.3; 95% CI 2.0-4.8). The optimism-corrected c-statistic for the final model was 0.80.

CONCLUSIONS

In this multicenter study of children hospitalized with bronchiolitis, we identified several demographic, historical, and clinical factors that predicted the use of CPAP and/or intubation, including children born to mothers who smoked during pregnancy. We also identified a novel subgroup of children who required mechanical respiratory support <1 day after respiratory symptoms began.

Unraveling the relationship between aeroallergen sensitization, gender, second-hand smoke exposure, and impaired lung function

BACKGROUND

Contradictory findings on the differential effects of second-hand smoke (SHS) on lung function in girls and boys may result from masked relationships between host and environmental factors. Allergic sensitization may augment the relationship between SHS and decreased lung function, although its role in relation to the inconsistent gender differences in children has not been elucidated.

HYPOTHESIS

We hypothesize that there will be differences between boys and girls related to early-life allergic sensitization and exposure to SHS on pulmonary function later in childhood.

METHODS

Participants in this study (n = 486) were drawn from the Cincinnati Childhood Allergy and Air Pollution (CCAAPS) birth cohort study consisting of 46% girls. Allergic sensitization was assessed by skin prick test (SPT) to 15 aeroallergens at ages 2, 4, and 7, while pulmonary function and asthma diagnosis occurred at age 7. SHS exposure was measured by hair cotinine at ages 2 and/or 4. Gender differences of SHS exposure on pulmonary function among children with positive SPTs at ages 2, 4, and 7 as well as first- and higher-order interactions were examined by multiple linear regression. Interactions significant in the multivariate models were also examined via stratification. Comparisons within and between stratified groups were assessed by examining the slope of the parameter estimates/beta coefficients and associated p-values and confidence intervals.

RESULTS

Increased cotinine levels were significantly associated with decreases in FEV(1) (-0.03 l, p < 0.05), peak expiratory flow (-0.07 l/s, p < 0.05), and FEF (25-75%) (-0.06 l/s, p < 0.01). The interaction between cotinine and sensitization at age 2 was borderline significant (p = 0.10) in the FEF(25-75%) model and showed an exposure response effect according to the number of positive SPTs at age 2; zero (-0.06 l/s, p < 0.01), one (-0.09 l/s, p < 0.05), or two or more positive SPTs (-0.30 l/s, p < 0.01). Despite increased polysensitization among boys, the association between cotinine and FEF(25-75%) among girls, with two or more positive SPTs at age 2, showed the greatest deficits in FEF(25-75%) (-0.34 l/s vs. -0.05 l/s and -0.06 l/s for non-sensitized girls and boys, respectively. Girls with two or more positive SPTs showed a twofold greater decrease in FEF(25-5%) (-0.34 l/s; 95% CI: -0.55, -0.13) compared to boys with the same degree of allergic sensitization (-0.18 l/s; 95% CI: -0.41, 0.06), although this difference was not statistically significant.

CONCLUSIONS

Reductions in lung function were observed among children exposed to SHS, and the number of aeroallergen-positive SPTs at age 2 modifies this relationship. Girls experiencing early childhood allergic sensitization and high SHS exposure are at greater risk of decreased lung function later in childhood compared to non-sensitized girls and boys and demonstrate greater deficits compared to boys with similar degrees of sensitization.