The early origins of asthma: who is really at risk?

Atopic children are more susceptible to viral respiratory infection at the age of 2-5 years old

Background: The susceptibility of the atopic population to respiratory infections (RI) has not been fully elucidated. This susceptibility is attributed to the immune dysregulation that characterizes atopic diseases. Although, the exact mechanisms involved are not fully understood, there is evidence that shows that the maturation of innate immunity progresses differently in patients with atopy. Objective: The aim of the study was to evaluate the susceptibility to viral RIs (VRI) based on the number and duration of them in different age groups in subjects with atopy and subjects without atopy. Methods: Seventy-eight subjects (39 healthy and 39 with atopy) were included in the study. All the subjects were evaluated by a specialist and defined as being atopic if they had a clinical history and/or symptoms compatible with any allergic diseases and relevant sensitizations. Epidemiologic data were recorded based on a standardized questionnaire, which included recording habits, conditions, and living environment as well as the history of viral infections during the last year. Results: In our population, children with atopy were found to be more susceptible to viral RIs than children without atopy (p = 0.02), whereas there was no difference in susceptibility between healthy adults and adults with atopy (18-45 years old). More specifically, the atopic age group 2-5 years old showed the higher susceptibility to VRIs. Conclusion: This study provided evidence that children with atopy, especially at ages 2-5 years old, had more numerically and prolonged RIs than did the subjects without atopy. These clinical findings support the hypothesis of distracted maturation of innate immunity in subjects with atopy.

Epigenetic signature of exposure to maternal Trypanosoma cruzi infection in cord blood cells from uninfected newborns

Aims: To assess the epigenetic effects of in utero exposure to maternal Trypanosoma cruzi infection. Methods: We performed an epigenome-wide association study to compare the DNA methylation patterns of umbilical cord blood cells from uninfected babies from chagasic and uninfected mothers. DNA methylation was measured using Infinium EPIC arrays. Results: We identified a differential DNA methylation signature of fetal exposure to maternal T. cruzi infection, in the absence of parasite transmission, with 12 differentially methylated sites in B cells and CD4⁺ T cells, including eight protein-coding genes. Conclusion: These genes participate in hematopoietic cell differentiation and the immune response and may be involved in immune disorders. They also have been associated with several developmental disorders and syndromes.

Maternal prenatal stress and infantile wheeze and asthma: The Osaka Maternal and Child Health Study

OBJECTIVE

Some recent studies suggest that maternal prenatal stress (MPS) increases allergic diseases in the children. However, knowledge on this issue in Asian children are lacking. We investigated the association between MPS and the risks of wheeze and asthma in Japanese infants aged 16-24 months.

METHODS

The present subjects were 763 Japanese mother-child pairs. The first, second, and third surveys based on self-administered questionnaires were performed during pregnancy, between 2 and 9 months postpartum, and from 16 to 24 months postpartum, respectively. Data on MPS was obtained in the first survey, using the Stress Inventory (SI), which constructs 12 specific behavioral patterns as response styles to stressors. Data on wheeze and asthma was obtained in the third survey, where wheeze was based on the International Study of Asthma and Allergies in Childhood criteria and asthma was based on doctors' diagnosis.

RESULTS

There were 169 infants with wheeze (22.1%) and 33 infants with asthma (4.3%), at the time of the third survey. Multiple logistic regression analyses found that a maternal behavioral pattern characterized by chronic irritation and anger was associated with the risk of childhood asthma (adjusted odds ratio [OR] = 1.56, 95% confidence interval [CI]: 1.11 to 2.22), but not wheeze (adjusted OR = 1.02, 95%CI: 0.88 to 1.19), while there was no appreciable association between the other SI scales and the risk of childhood wheeze or asthma.

CONCLUSIONS

The results partly supported the hypothesis that MPS might increase the risk of asthma in their infants in Japanese.

Relevance of the first thousand days of life to the development of wheezing in children aged 6-7 years

INTRODUCTION

The first thousand days of life are a critical stage for the development of respiratory and immune systems. Many events in this period may be associated with wheezing in childhood.

OBJECTIVE

This study aimed to investigate the association between early life determinants and wheezing in children aged 6-7 years.

MATERIALS AND METHODS

Population-based case-control study using early-life related questions. We used the International Study of Asthma and Allergies in Childhood questionnaire to assess wheezing symptoms. Multiple logistic regressions were performed according to a hierarchical framework, considering the complex dynamic of wheezing/asthma and potential interaction between different levels of determination.

RESULTS

A total of 820 children were included, from which 162 reported wheezing symptoms (19.7%). Multivariable analysis identified socioeconomic conditions (OR 2.08, 95% CI 1.08-4.00), family history of asthma (OR 2.28, 95% CI 1.37-3.75), vaginal discharge that required treatment during pregnancy (OR 1.68, 95% CI 1.00-2.83), neonatal hyperbilirubinemia (OR 2.00, 95% CI 1.17-3.42), anemia and intestinal parasitosis in the first two years (OR 2.28, 95% CI 1.22-4.25; OR 1.72, 95% CI 1.02-2.92, respectively) independently associated to wheezing at 6-7 years. Intended pregnancy was associated with reduced wheezing (OR 0.47, 95% CI 0.28-0.77).

CONCLUSIONS

Several factors were associated with wheezing in childhood. Considering that intended pregnancy reduced wheezing and other associated exposures are considered modifiable, these findings may guide the planning of strategies to decrease the susceptibility to asthma symptoms in childhood.

Establishing a three-generation prospective study: Bogalusa daughters

OBJECTIVE

The Developmental Origins of Disease hypothesis has spurred increased interest in how prenatal exposures affect lifelong health, while mechanisms such as epigenetics may explain the multigenerational influences on health. Such factors are not well captured within conventional epidemiologic study designs. We explored the feasibility of collecting information on the offspring and grand-offspring of participants in a long-running study.

DESIGN

The Bogalusa Heart Study is a study, begun in 1973, of life-course cardiovascular health in a semirural population (65% white and 35% black).

MAIN MEASURES

Female participants who had previously provided information on their pregnancies were contacted to obtain contact information for their daughters aged 12 and older. Daughters were then contacted to obtain reproductive histories, and invited for a clinic or lab visit to measure cardiovascular risk factors.

RESULTS

Two hundred seventy-four daughters of 208 mothers were recruited; 81% (223) had a full clinic visit and 19% (51) a phone interview only. Forty-five percent of the daughters were black, and 55% white. Mean and median age at interview was 27, with 15% under the age of 18. The strongest predictors of participation were black race, recent maternal participation in the parent study, and living in or near Bogalusa. Simple correlations for cardiovascular risk factors across generations were between r = 0.19 (systolic blood pressure) and r = 0.39 (BMI, LDL).

CONCLUSION

It is feasible to contact the children of study participants even when participants are adults, and initial information on the grandchildren can also be determined in this manner.

Particulate matter-associated micronuclei frequencies in maternal and cord blood lymphocytes

Studies associate particulate matter (PM) exposure with pulmonary, cardiovascular, and neurologic diseases. Elevated levels of coarse (PM10) and fine (PM2.5) PM have been reported in the Mexico City metropolitan area during the last two decades. There is limited information if these conditions affect newborns. We associated maternal exposure to PM reported by the monitoring stations considering the place of residence of each participant with the presence of genotoxic damage (cytome analysis) in maternal and umbilical cord blood (UCB) lymphocytes. Eighty-four healthy women in their last quarter of pregnancy met the inclusion criteria. Each volunteer exposure was estimated according to the average PM2.5 and PM10 levels during the last month of gestation. The micronuclei (MN) frequencies in UCB lymphocyte cultures ranged between 0 and 9. They also showed lower cell proliferation indexes than their mothers. There was a strong correlation between the maternal and the UCB MN frequency (ρ = 0.3767, P = 0.0002). Multiple regression analysis including PM10 and PM2.5 levels, maternal age, and occupation, showed a significant and positive association between UCB MN frequency and PM2.5. A statistically significant increase in the MN frequency in both maternal and UCB lymphocytes was observed in samples obtained during the dry season (higher PM levels) as compared with the MN frequency in blood samples obtained during the rainy season (lower PM levels). These results suggest that PM, mainly PM_2.5 , can cross the placenta causing DNA damage in fetal cells which may increase the potential for diseases during childhood or adult life. Environ. Mol. Mutagen. 60:421-427, 2019. © 2019 Wiley Periodicals, Inc.

Air pollutants and early origins of respiratory diseases

Air pollution is a global health threat and causes millions of human deaths annually. The late onset of respiratory diseases in children and adults due to prenatal or perinatal exposure to air pollutants is emerging as a critical concern in human health. Pregnancy and fetal development stages are highly susceptible to environmental exposure and tend to develop a long-term impact in later life. In this review, we briefly glance at the direct impact of outdoor and indoor air pollutants on lung diseases and pregnancy disorders. We further focus on lung complications in later life with early exposure to air pollutants. Epidemiological evidence is provided to show the association of prenatal or perinatal exposure to air pollutants with various adverse birth outcomes, such as preterm birth, lower birth weight, and lung developmental defects, which further associate with respiratory diseases and reduced lung function in children and adults. Mechanistic evidence is also discussed to support that air pollutants impact various cellular and molecular targets at early life, which link to the pathogenesis and altered immune responses related to abnormal respiratory functions and lung diseases in later life.

Thirdhand smoke component can exacerbate a mouse asthma model through mast cells

BACKGROUND

Thirdhand smoke (THS) represents the accumulation of secondhand smoke on indoor surfaces and in dust, which, over time, can become more toxic than secondhand smoke. Although it is well known that children of smokers are at increased risk for asthma or asthma exacerbation if the disease is already present, how exposure to THS can influence the development or exacerbation of asthma remains unknown.

OBJECTIVE

We investigated whether epicutaneous exposure to an important component of THS, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), can influence asthma pathology in a mouse model elicited by means of repeated intranasal challenge with cockroach antigen (CRA).

METHODS

Wild-type mice, α7 nicotinic acetylcholine receptor (nAChR)- or mast cell (MC)-deficient mice, and mice with MCs that lacked α7 nAChRs or were the host's sole source of α7 nAChRs were subjected to epicutaneous NNK exposure, intranasal CRA challenge, or both, and the severity of features of asthma pathology, including airway hyperreactivity, airway inflammation, and airway remodeling, was assessed.

RESULTS

We found that α7 nAChRs were required to observe adverse effects of epicutaneous NNK exposure on multiple features of CRA-induced asthma pathology. Moreover, MC expression of α7 nAChRs contributed significantly to the ability of epicutaneous NNK exposure to exacerbate airway hyperreactivity to methacholine, airway inflammation, and airway remodeling in this model.

CONCLUSION

Our results show that skin exposure to NNK, a component of THS, can exacerbate multiple features of a CRA-induced model of asthma in mice and define MCs as key contributors to these adverse effects of NNK.

Early-life exposure to indoor air pollution or tobacco smoke and lower respiratory tract illness and wheezing in African infants: a longitudinal birth cohort study

BACKGROUND

Indoor air pollution (IAP) and environmental tobacco smoke (ETS) are associated with lower respiratory tract illness (LRTI) or wheezing in children. However, the effect of the timing of these exposures, specifically antenatal versus postnatal, and of alternate fuel sources such as the increasingly used volatile organic compounds have not been well studied. We longitudinally investigated the effect of antenatal or postnatal IAP and ETS on LRTI or wheezing prevalence and severity in African infants.

METHODS

Mother and infant pairs enrolled over a 3-year period in a birth cohort study in two centres in Paarl, South Africa, were followed for the first year of life for LRTI or wheezing illness. We measured exposure to IAP (particulate matter, nitrogen dioxide, sulphur dioxide, carbon monoxide, and volatile organic compounds benzene and toluene) using devices placed in homes, antenatally and postnatally. We measured ETS longitudinally by maternal self-report and by urine cotinine measures. Study staff trained in recognition of LRTI or wheeze documented all episodes, which were categorised according to WHO case definition criteria. We used multivariate logistic and Poisson regressions to explore associations.

FINDINGS

Between March 1, 2012, and March 31, 2015, we enrolled 1137 mothers with 1143 livebirths. Of 1065 infants who attended at least one study visit, 524 episodes of LRTI occurred after discharge with a wheezing prevalence of 0·23 (95% CI 0·21-0·26) episodes per child year. Exposures associated with LRTI were antenatal maternal smoking (incidence rate ratio 1·62, 95% CI 1·14-2·30; p=0·004) or particulate matter (1·43, 1·06-1·95; p=0·008). Subanalyses of LRTI requiring hospitalisation (n=137) and supplemental oxygen (n=69) found antenatal toluene significantly increased the risk of LRTI-associated hospitalisation (odds ratio 5·13, 95% CI 1·43-18·36; p=0·012) and need for supplemental oxygen (13·21, 1·96-89·16; p=0·008). Wheezing illness was associated with both antenatal (incidence rate ratio 2·09, 95% CI 1·54-2·84; p<0·0001) and postnatal (1·27, 95% CI 1·03-1·56; p=0·024) maternal smoking. Antenatally, wheezing was associated with maternal passive smoke exposure (1·70, 1·25-2·31; p=0·001) and, postnatally, with any household member smoking (1·55, 1·17 -2·06; p=0·002).

INTERPRETATION

Antenatal exposures were the predominant risk factors associated with LRTI or wheezing illness. Toluene was a novel exposure associated with severe LRTI. Urgent and effective interventions focusing on antenatal environmental factors are required, including smoking cessation programmes targeting women of childbearing age pre-conception and pregnant women.

FUNDING

Bill & Melinda Gates Foundation, Discovery Foundation, South African Thoracic Society AstraZeneca Respiratory Fellowship, Medical Research Council South Africa, National Research Foundation South Africa, and CIDRI Clinical Fellowship.

Prevalence and factors associated with asthma in students from Montes Claros, Minas Gerais, Brazil

We investigated the prevalence of asthma and factors related to asthma development in schoolchildren aged 6 to 14, living in central and peripheral areas of the city of Montes Claros, Minas Gerais and who were registered with the Family Health Strategy program. Initially, a standard written questionnaire, based on ISAAC (International Study of Asthma and Allergies in Childhood), was administered to collect personal data, information regarding income, asthma prevalence, allergic rhinitis and eczema (N = 1,131). Secondly, a case-control study was performed by grouping the patients as either asthmatic (A; N = 172) or non-asthmatic (NA; N = 379). Potential factors associated with the occurrence of asthma were evaluated using the complementary questionnaire from ISAAC phase II. Skin tests for immediate hypersensitivity (STIH) and parasitological tests were also performed. The odds ratio, estimated by multivariate analysis, indicated that asthma cases were related to kindergarten attendance, household smoking, family history of asthma, rhinitis and positive STIH. It was concluded that, in the studied population, the prevalence of asthma was related to genetic predisposition, in addition to individual history, social demographics, exposure to pollutants such as tobacco smoke and a positive response to allergy testing.

Re-examining the association between residential exposure to magnetic fields from power lines and childhood asthma in the Danish National Birth Cohort

Background

A study reported an increased risk of asthma in children whose mothers were exposed to magnetic field (MF) levels above 0.2 μT during pregnancy. We re-examined this association using data from mothers and children in the Danish National Birth Cohort (DNBC).

Methods

This study included 92,676 singleton-born children and their mothers from the DNBC. MF exposure from power lines was estimated for all residences where the mothers lived during pregnancy and for all children from birth until the end of follow up. Exposure was categorized into 0 μT, 0.1 μT, and ≥ 0.2 μT for analysis. Definitive and possible asthma cases were identified using data from three independent data sources: 1) mothers’ reports, 2) a national hospitalization register, 3) a national prescription drug register. We calculated hazard ratios (HR) and 95% confidence intervals (CI) for the association between the highest level of exposure during pregnancy and asthma in children, adjusting for several potential confounding factors. We also examined the sensitivity of the risk estimates to changes in exposure and outcome definitions.

Results

No differences or trends in the risk of asthma development were detected between children with different levels of MF exposure regardless of the asthma case definition or outcome data source. For definitive cases, the HR (95% CI) for those with any exposure was 0.72 (0.27–1.92), and it was 0.41 (0.06–2.92) for those exposed to ≥ 0.2 μT. Adjustments for confounding and variations in the exposure definition did not appreciably alter the results.

Conclusion

We did not find evidence that residential exposure to MF during pregnancy or early childhood increased the risk of childhood asthma. This interpretation is in line with the lack of an established biological mechanism directly linking MF exposure to asthma, but high exposure was very rare in this cohort.

Maternal obesity and childhood wheezing and asthma

Obesity represents one of the major public health problems worldwide, with an increased prevalence also among women of reproductive age. Maternal pre-pregnancy overweight and obesity are important risk factors for a number of maternal and foetal/neonatal complications. The objective of this review is to provide an overview of the most recent evidence regarding the associations between pre-pregnancy overweight/obesity and wheezing and asthma in childhood. Potential mechanisms, mediators and confounding factors involved in these associations are also discussed. Despite the relatively large body of studies examining these associations and taking into account main confounders and potential mediators, the causal relationship between maternal obesity and wheezing and asthma in childhood is still uncertain. This uncertainty is not trivial, as any prevention strategy aimed at reducing the burden of these conditions would necessarily imply better understanding of the factors that are in the causal chain.

Air pollution during pregnancy and lung development in the child

Air pollution exposure has increased extensively in recent years and there is considerable evidence that exposure to particulate matter can lead to adverse respiratory outcomes. The health impacts of exposure to air pollution during the prenatal period is especially concerning as it can impair organogenesis and organ development, which can lead to long-term complications. Exposure to air pollution during pregnancy affects respiratory health in different ways. Lung development might be impaired by air pollution indirectly by causing lower birth weight, premature birth or disturbed development of the immune system. Exposure to air pollution during pregnancy has also been linked to decreased lung function in infancy and childhood, increased respiratory symptoms, and the development of childhood asthma. In addition, impaired lung development contributes to infant mortality. The mechanisms of how prenatal air pollution affects the lungs are not fully understood, but likely involve interplay of environmental and epigenetic effects. The current epidemiological evidence on the effect of air pollution during pregnancy on lung function and children's respiratory health is summarized in this review. While evidence for the adverse effects of prenatal air pollution on lung development and health continue to mount, rigorous actions must be taken to reduce air pollution exposure and thus long-term respiratory morbidity and mortality.

Indoor air risk factors for schoolchildren's health in Portuguese homes: Results from a case-control survey

Allergic diseases have been on the rise in many countries over the past few decades and indoor exposure may be a possible cause. An overall investigation of children's health status and residential indoor air pollutants known or suspected to affect respiratory health was conducted in the homes of primary schoolchildren during winter in Porto, Portugal. In a case-control study (30 case children with asthma and 38 controls) and over a 1-wk monitoring period, air sample collection was conducted in children's bedrooms for the analysis of 12 volatile organic compounds (VOC), aldehydes, particulate matter (PM)2.5, PM10, bacteria, and fungi. Home exposures to indoor pollutants are similar for children with and without asthma, except for d-limonene. For both groups, most VOC were present at low concentrations (median < 5 µg/m(3)) and below the respective World Health Organization (WHO) guidelines. Concentrations of PM2.5, PM10, and bacteria were frequently higher than WHO/reference values (80, 25, and 60% of all studied dwellings, respectively). Concentrations of carbon dioxide (CO2) exceeding 1000 ppm were encountered in 60% of the homes. Although this study does not provide evidence of causative factors for asthmatic status, the postulation that poor indoor air quality in homes heightens the risk of allergic symptoms development among children is conceivable.

Increased seroprevalence of Enterovirus 71 IgE antibodies in asthmatic compared with non-asthmatic children

BACKGROUND

Asthma is a common pediatric chronic inflammatory airway disease. Respiratory viral infections are frequent infectious triggers for exacerbations of asthma.

OBJECTIVE

We sought to determine whether Enterovirus 71 (EV71), a ubiquitous virus that causes systemic inflammatory responses in children but is not a known respiratory pathogen, can also serve as an infectious trigger for asthma.

METHODS

Specific EV71 IgE and IgM antibodies (Abs), total serum IgE, and IL-2 and IL-4 cytokine levels in serum of asthmatic and non-asthmatic children (N = 42, ages 5-19; N = 35, ages 1-20, respectively) were measured (ELISA).

RESULTS

Asthmatic children had higher EV71 IgE Ab levels than non-asthmatic (P < 0.001). Non-asthmatic children had significantly higher EV71 IgM Ab levels than asthmatic (P < 0.001). Despite low serum IgE levels of non-asthmatic, compared with asthmatic (P < 0.001), the non-asthmatic children produced significantly more IL-2 and IL-4 than asthmatic (P < 0.001; P < 0.001). The ages of the asthmatics, but not the non-asthmatics had a significant effect on the levels of EV 71 IgE Abs (P = 0.02; P = 0.356). A test of difference between these two slopes was significant. However, the ages of the non-asthmatic, but not the asthmatic children had a significant effect on the levels of EV 71 IgM Abs; a test of difference between these two slopes was significant.

CONCLUSIONS

Increased specific EV71 IgE Ab responses may indicate that EV71 infection may also be an infectious trigger in asthma. However, the role of specific EV71 IgM Abs, Th2 cytokines, and age in non-asthmatic children should be further studied.

Whole-Genome Saliva and Blood DNA Methylation Profiling in Individuals with a Respiratory Allergy

The etiology of respiratory allergies (RA) can be partly explained by DNA methylation changes caused by adverse environmental and lifestyle factors experienced early in life. Longitudinal, prospective studies can aid in the unravelment of the epigenetic mechanisms involved in the disease development. High compliance rates can be expected in these studies when data is collected using non-invasive and convenient procedures. Saliva is an attractive biofluid to analyze changes in DNA methylation patterns. We investigated in a pilot study the differential methylation in saliva of RA (n = 5) compared to healthy controls (n = 5) using the Illumina Methylation 450K BeadChip platform. We evaluated the results against the results obtained in mononuclear blood cells from the same individuals. Differences in methylation patterns from saliva and mononuclear blood cells were clearly distinguishable (PAdj<0.001 and |Δβ|>0.2), though the methylation status of about 96% of the cg-sites was comparable between peripheral blood mononuclear cells and saliva. When comparing RA cases with healthy controls, the number of differentially methylated sites (DMS) in saliva and blood were 485 and 437 (P<0.05 and |Δβ|>0.1), respectively, of which 216 were in common. The methylation levels of these sites were significantly correlated between blood and saliva. The absolute levels of methylation in blood and saliva were confirmed for 3 selected DMS in the PM20D1, STK32C, and FGFR2 genes using pyrosequencing analysis. The differential methylation could only be confirmed for DMS in PM20D1 and STK32C genes in saliva. We show that saliva can be used for genome-wide methylation analysis and that it is possible to identify DMS when comparing RA cases and healthy controls. The results were replicated in blood cells of the same individuals and confirmed by pyrosequencing analysis. This study provides proof-of-concept for the applicability of saliva-based whole-genome methylation analysis in the field of respiratory allergy.

Reported associations between asthma and acute lymphoblastic leukemia: insights from a hybrid simulation study

Numerous studies have reported a protective association between asthma and acute lymphoblastic leukemia (ALL), but the causal structure of this association remains unclear. We present a hybrid simulation to examine the compatibility of this association with uncontrolled confounding by infection or another unmeasured factor. We generated a synthetic cohort using inputs on the interrelations of asthma, ALL, infections, and other suggested risk factors from the literature and the Danish National Birth Cohort. We computed odds ratios (ORs) between asthma and ALL in the synthetic cohort with and without adjustment for infections and other (including unmeasured) confounders. Only if infection was an extremely strong risk factor for asthma (OR of 10) and an extremely strong protective factor against ALL (OR of 0.1) was the asthma-ALL association compatible with the literature (OR of 0.78). Similarly, strong uncontrolled confounding by an unmeasured factor could downwardly bias the asthma-ALL association, but not enough to replicate findings in the literature. This investigation illustrates that the reported protective association between asthma and ALL is unlikely to be entirely due to uncontrolled confounding by infections or an unmeasured confounder alone. Simulation can be used to advance our understanding of risk factors for rare outcomes as demonstrated by this study.

Allergens, air pollutants, and childhood allergic diseases

BACKGROUND

The synergistic effect of allergens and air pollutants on the risk of allergic diseases is unclear.

OBJECTIVE

To evaluate the joint effect of outdoor pollutants and indoor allergens on the risk of allergic diseases.

METHODS

We enrolled 2661 kindergarten children from the CEAS cohort. Data on allergic diseases and environmental exposure were collected. Skin prick tests were performed. Individual exposure to air pollution was estimated using a geographic information system with the mean concentration of air pollutants. Multiple logistic regression analysis was performed to estimate the association between air pollutants, allergen exposure and the risk of allergic diseases with adjustments for potential confounders.

RESULTS

Overall, 12.6% of the children had asthma, 30.0% had allergic rhinitis (AR), and 14.4% had atopic dermatitis (AD). Mite sensitization significantly increased the risk of AD, AR, and asthma (OR (95%CI) 2.15 (1.53-3.03), 1.94 (1.46-2.58), and 2.31 (1.63-3.29), respectively). Exposure to PM10, PM(2.5), CO, and O(3) was associated with asthma (OR (95% CI) 1.39 (1.03-1.87), 1.45 (1.07-1.97), 1.36 (1.01-1.83), and 0.68 (0.51-0.92), respectively). PM(2.5) may have increased the risk of AR (OR (95% CI) 1.54 (1.03-2.32). Mite sensitization showed a synergistic effect with PM(2.5) on the development of asthma (p < 0.001). Moreover, mite allergens may modify the effect of air pollutants on allergic diseases.

CONCLUSION

Dust mites and PM(2.5) play an important role on the risk of asthma and AR. Exposure to PM(2.5) and mite allergens had a synergistic effect on the development of asthma. Avoiding co-exposure to allergens and air pollutants is important.

Rationale, design and methods for the 22 year follow-up of the Western Australian Pregnancy Cohort (Raine) Study

BACKGROUND

Young adulthood is a critical life period for health and health behaviours. Related measurements collected before and after birth, and during childhood and adolescence can provide a life-course analysis of important factors that contribute to health and behaviour in young adulthood. The Western Australian Pregnancy Cohort (Raine) Study has collected a large number of such measurements during the fetal, perinatal, infancy, childhood and adolescence periods and plans to relate them to common health issues and behaviours in young adults, including spinal pain, asthma, sleep disorders, physical activity and sedentary behaviour and, work absenteeism and presenteeism. The aim of this paper is to describe the rationale, design and methods of the 22 year follow-up of the Raine Study cohort.

METHODS/DESIGN

The Raine Study is a prospective cohort study. Participants still active in the cohort (n = 2,086) were contacted around the time of their 22nd birthday and invited to participate in the 22 year follow-up. Each was asked to complete a questionnaire, attend a research facility for physical assessment and an overnight sleep study, wear activity monitors for a week, and to maintain a sleep and activity diary over this week. The questionnaire was broad and included questions related to sociodemographics, medical history, quality of life, psychological factors, lifestyle factors, spinal pain, respiratory, sleep, activity and work factors. Physical assessments included anthropometry, blood pressure, back muscle endurance, tissue sensitivity, lung function, airway reactivity, allergic status, 3D facial photographs, cognitive function, and overnight polysomnography.

DISCUSSION

Describing the prevalence of these health issues and behaviours in young adulthood will enable better recognition of the issues and planning of health care resources. Providing a detailed description of the phenotype of these issues will provide valuable information to help educate health professionals of the needs of young adults. Understanding the life-course risk factors of health issues and behaviours in young adulthood will have important health planning implications, supporting the development of targeted interventions to improve current health status and reduce the onset and development of further ill-health across adulthood.

Predicting risk for childhood asthma by pre-pregnancy, perinatal, and postnatal factors

BACKGROUND

Symptoms of atopic disease start early in human life. Predicting risk for childhood asthma by early-life exposure would contribute to disease prevention. A birth cohort study was conducted to investigate early-life risk factors for childhood asthma and to develop a predictive model for the development of asthma.

METHODS

National representative samples of newborn babies were obtained by multistage stratified systematic sampling from the 2005 Taiwan Birth Registry. Information on potential risk factors and children's health was collected by home interview when babies were 6 months old and 5 yr old, respectively. Backward stepwise regression analysis was used to identify the risk factors of childhood asthma for predictive models that were used to calculate the probability of childhood asthma.

RESULTS

A total of 19,192 children completed the study satisfactorily. Physician-diagnosed asthma was reported in 6.6% of 5-yr-old children. Pre-pregnancy factors (parental atopy and socioeconomic status), perinatal factors (place of residence, exposure to indoor mold and painting/renovations during pregnancy), and postnatal factors (maternal postpartum depression and the presence of atopic dermatitis before 6 months of age) were chosen for the predictive models, and the highest predicted probability of asthma in 5-yr-old children was 68.1% in boys and 78.1% in girls; the lowest probability in boys and girls was 4.1% and 3.2%, respectively.

CONCLUSIONS

This investigation provides a technique for predicting risk of childhood asthma that can be used to developing a preventive strategy against asthma.

Early-life exposure to combustion-derived particulate matter causes pulmonary immunosuppression

Elevated levels of combustion-derived particulate matter (CDPM) are a risk factor for the development of lung diseases such as asthma. Studies have shown that CDPM exacerbates asthma, inducing acute lung dysfunction and inflammation; however, the impact of CDPM exposure on early immunological responses to allergens remains unclear. To determine the effects of early-life CDPM exposure on allergic asthma development in infants, we exposed infant mice to CDPM and then induced a mouse model of asthma using house dust mite (HDM) allergen. Mice exposed to CDPM+HDM failed to develop a typical asthma phenotype including airway hyper-responsiveness, T-helper type 2 (Th2) inflammation, Muc5ac expression, eosinophilia, and HDM-specific immunoglobulin (Ig) compared with HDM-exposed mice. Although HDM-specific IgE was attenuated, total IgE was twofold higher in CDPM+HDM mice compared with HDM mice. We further demonstrate that CDPM exposure during early life induced an immunosuppressive environment in the lung, concurrent with increases in tolerogenic dendritic cells and regulatory T cells, resulting in the suppression of Th2 responses. Despite having early immunosuppression, these mice develop severe allergic inflammation when challenged with allergen as adults. These findings demonstrate a mechanism whereby CDPM exposure modulates adaptive immunity, inducing specific antigen tolerance while amplifying total IgE, and leading to a predisposition to develop asthma upon rechallenge later in life.

Asthma screening of inner city and urban elementary school-aged children

OBJECTIVE

Currently, in the United States there is a lack of a standardized method to effectively screen school children with undiagnosed or poorly controlled asthma. The purpose of this proof-of-concept study was to assess the use of the American College of Allergy, Asthma, and Immunology's (ACAAI) Asthma Screening Questionnaire to identify elementary school-age children at risk for asthma (undiagnosed) or poorly controlled asthma.

METHODS

Children in grades 3-5 from one urban and two suburban schools completed ACAAI's 14 question asthma screening questionnaire and had their peak expiratory flow (PEF) measured. Children were considered to have a positive asthma screen and be at risk for having undiagnosed or poorly controlled asthma if they answered 'yes' to more than three questions. Children were referred to a physician if they had a positive asthma screen, a previous history of asthma, or a low PEF.

RESULTS

Of the 86 participants, 52 were identified as being at risk for asthma. The number was higher among children attending an urban versus suburban school (p = 0.04). The sensitivity and specificity of the screening questionnaire for identifying asthma risk were 90% and 66%, respectively, when the number of 'yes' responses for a positive screen was increased from three to five of 14 questions.

CONCLUSIONS

The ACAAI's Asthma Screening Questionnaire identified 52 children at risk for undiagnosed or poorly controlled asthma. Our findings support the need to validate this questionnaire to be used in conjunction with PEFR for identifying elementary school children at risk for asthma.

Viral bronchiolitis in children: a common condition with few therapeutic options

Even though bronchiolitis is a disease that has been recognized for many years, there are still few therapeutic strategies beyond supportive therapies. Bronchiolitis is the most frequent cause of hospital admission in children less than 1 year of age. The incidence is estimated to be about 150° million cases a year worldwide, and 2-3% of these cases require hospitalization. It is acknowledged that viruses cause bronchiolitis, but most of the studies focus on RSV. The RSV causes a more severe form of bronchiolitis in children with risk factors including prematurity, cardiovascular disease and immunodeficiency. Other viruses involved in causing bronchiolitis include RV, hMPV, hBoV and co-infections. The RV seems to be associated with a less severe acute disease, but there is a correlation between the early infection and subsequent wheezing bronchitis and asthma in later childhood and adulthood. The supportive therapies used are intravenous fluids and oxygen supplement administered by nasal cannula or CPAP in most complicated patients. Additional pharmacological therapies include epinephrine, 3% hypertonic saline and corticosteroids. The Epinephrine seems to have the greatest short-term benefits and reduces the need of hospital admission, whereas hypertonic saline and corticosteroids seem to reduce the length of hospital stay. As bronchiolitis is such a prevalent disease in children and RV seems to play an important role, perhaps more studies should center around the RV's contribution to the initial disease and following pathology.

Prenatal and childhood infections: implications for the development and treatment of childhood asthma

Bacterial and viral infections occur early and recurrently in life and thereby impose a substantial disease burden. Besides causing clinical symptoms, a potential role of infection in the development of the asthma syndrome later in life has also been suggested. However, whether bacterial and viral infections unmask host factors in children at risk of asthma or whether they directly cause asthma remains unclear; both viewpoints could be justified, but the underlying mechanisms are complex and poorly understood. Recently, the role of the bacterial microbiome has been emphasised. But data are still sparse and future studies are needed for definitive conclusions to be made. In this Review, we discuss present knowledge of viruses and bacteria that infect and colonise the respiratory tract and mucosal surfaces, including their timepoint of action, host factors related to infection, and their effect on childhood asthma. Childhood asthma could be the result of a combination of altered host susceptibility and infectious agents.

A prospective study of the impact of air pollution on respiratory symptoms and infections in infants

RATIONALE

There is increasing evidence that short-term exposure to air pollution has a detrimental effect on respiratory health, but data from healthy populations, particularly infants, are scarce.

OBJECTIVES

To assess the association of air pollution with frequency and severity of respiratory symptoms and infections measured weekly in healthy infants.

METHODS

In a prospective birth cohort of 366 infants of unselected mothers, respiratory health was assessed weekly by telephone interviews during the first year of life (19,106 total observations). Daily mean levels of particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3) were obtained from local monitoring stations. We determined the association of the preceding week's pollutant levels with symptom scores and respiratory tract infections using a generalized additive mixed model with an autoregressive component. In addition, we assessed whether neonatal lung function influences this association and whether duration of infectious episodes differed between weeks with normal PM10 and weeks with elevated levels.

MEASUREMENTS AND MAIN RESULTS

We found a significant association between air pollution and respiratory symptoms, particularly in the week after respiratory tract infections (risk ratio, 1.13 [1.02-1.24] per 10 μg/m(3) PM10 levels) and in infants with premorbid lung function. During times of elevated PM10 (>33.3 μg/m(3)), duration of respiratory tract infections increased by 20% (95% confidence interval, 2-42%).

CONCLUSIONS

Exposure to even moderate levels of air pollution was associated with increased respiratory symptoms in healthy infants. Particularly in infants with premorbid lung function and inflammation, air pollution contributed to longer duration of infectious episodes with a potentially large socioeconomic impact.

Early lung development: lifelong effect on respiratory health and disease

Interest in the contribution of changes in lung development during early life to subsequent respiratory morbidity is increasing. Most evidence of an association between adverse intrauterine factors and structural effects on the developing lung is from animal studies. Such evidence has been augmented by epidemiological studies showing associations between insults to the developing lung during prenatal and early postnatal life and adult respiratory morbidity or reduced lung function, and by physiological studies that have elucidated mechanisms underlying these associations. The true effect of early insults on subsequent respiratory morbidity can be understood only if the many prenatal and postnatal factors that can affect lung development are taken into account. Adverse factors affecting lung development during fetal life and early childhood reduce the attainment of maximum lung function and accelerate lung function decline in adulthood, initiating or worsening morbidity in susceptible individuals. In this Review, we focus on factors that adversely affect lung development in utero and during the first 5 years after birth, thereby predisposing individuals to reduced lung function and increased respiratory morbidity throughout life. We focus particularly on asthma and COPD.

Immune cell profile in infants' lung tissue

Little is known about the normal immune cell profile in the lungs of infants without pulmonary disease. Normal lung samples obtained at autopsy of 10 infants that died either due to incidental or inflicted causes or non-pulmonary diseases were stained for antibodies against B and T lymphocytes, macrophages, NK cells, cytotoxic cells, dendritic cells and mast cells. Cells were quantified in the airway epithelial layer, inner layer (between the epithelium and the outer smooth muscle border), outer layer (between the outer smooth muscle border and the external limits of the airway) and alveolar septa. Basement membrane or alveolar septa lengths were assessed by image analysis. Results were expressed as cells/mm. The median age of patients was 6.8 months, ranging from 11 to 840 days. The inner layer of the airways was the region with the smallest density of cells. There was a predominance of cells related to the innate immunity such as CD56+, Granzyme B+ and CD68+ cells in the epithelial layer and alveolar parenchyma. The outer layer and the lung parenchyma presented the highest cellular density. There were very few CD4+ T cells or dendritic cells in most of the lung compartments. The numbers of CD3+ T and granzyme B+ cells correlated positively with age. There was a compartmentalization of immune cells along airways and parenchyma, which may be related to the development of innate and acquired lung defense mechanisms.

Modifiable exposures to air pollutants related to asthma phenotypes in the first year of life in children of the EDEN mother-child cohort study

Background

Studies have shown diverse strength of evidence for the associations between air pollutants and childhood asthma, but these associations have scarcely been documented in the early life. The purpose of this study was to evaluate the impacts of various air pollutants on the development of asthma phenotypes in the first year of life.

Methods

Adjusted odds ratios were estimated to assess the relationships between exposures to air pollutants and single and multi-dimensional asthma phenotypes in the first year of life in children of the EDEN mother-child cohort study (n = 1,765 mother-child pairs). The Generalized Estimating Equation (GEE) model was used to determine the associations between prenatal maternal smoking and in utero exposure to traffic-related air pollution and asthma phenotypes (data were collected when children were at birth, and at 4, 8 and 12 months of age). Adjusted Population Attributable Risk (aPAR) was estimated to measure the impacts of air pollutants on health outcomes.

Results

In the first year of life, both single and multi-dimensional asthma phenotypes were positively related to heavy parental smoking, traffic-related air pollution and dampness, but negatively associated with contact with cats and domestic wood heating. Adjusted odds ratios (aORs) for traffic-related air pollution were the highest [1.71 (95% Confidence Interval (CI): 1.08-2.72) for ever doctor-diagnosed asthma, 1.44 (95% CI: 1.05-1.99) for bronchiolitis with wheezing, 2.01 (95% CI: 1.23-3.30) for doctor-diagnosed asthma with a history of bronchiolitis]. The aPARs based on these aORs were 13.52%, 9.39%, and 17.78%, respectively. Results persisted for prenatal maternal smoking and in utero exposure to traffic-related air pollution, although statistically significant associations were observed only with the asthma phenotype of ever bronchiolitis.

Conclusions

After adjusting for potential confounders, traffic-related air pollution in utero life and in the first year of life, had a greater impact on the development of asthma phenotypes compared to other factors.

Toll-like receptor 7 gene deficiency and early-life Pneumovirus infection interact to predispose toward the development of asthma-like pathology in mice

BACKGROUND

Respiratory tract viruses are a major environmental risk factor for both the inception and exacerbations of asthma. Genetic defects in Toll-like receptor (TLR) 7-mediated signaling, impaired type I interferon responses, or both have been reported in asthmatic patients, although their contribution to the onset and exacerbation of asthma remains poorly understood.

OBJECTIVE

We sought to determine whether Pneumovirus infection in the absence of TLR7 predisposes to bronchiolitis and the inception of asthma.

METHODS

Wild-type and TLR7-deficient (TLR7(-/-)) mice were inoculated with the rodent-specific pathogen pneumonia virus of mice at 1 (primary), 7 (secondary), and 13 (tertiary) weeks of age, and pathologic features of bronchiolitis or asthma were assessed. In some experiments infected mice were exposed to low-dose cockroach antigen.

RESULTS

TLR7 deficiency increased viral load in the airway epithelium, which became sloughed and necrotic, and promoted an IFN-α/β(low), IL-12p70(low), IL-1β(high), IL-25(high), and IL-33(high) cytokine microenvironment that was associated with the recruitment of type 2 innate lymphoid cells/nuocytes and increased TH2-type cytokine production. Viral challenge of TLR7(-/-) mice induced all of the cardinal pathophysiologic features of asthma, including tissue eosinophilia, mast cell hyperplasia, IgE production, airway smooth muscle alterations, and airways hyperreactivity in a memory CD4(+) T cell-dependent manner. Importantly, infections with pneumonia virus of mice promoted allergic sensitization to inhaled cockroach antigen in the absence but not the presence of TLR7.

CONCLUSION

TLR7 gene defects and Pneumovirus infection interact to establish an aberrant adaptive response that might underlie virus-induced asthma exacerbations in later life.

Particulate matter containing environmentally persistent free radicals and adverse infant respiratory health effects: a review

The health impacts of airborne particulate matter (PM) are of global concern, and the direct implications to the development/exacerbation of lung disease are immediately obvious. Most studies to date have sought to understand mechanisms associated with PM exposure in adults/adult animal models; however, infants are also at significant risk for exposure. Infants are affected differently than adults due to drastic immaturities, both physiologically and immunologically, and it is becoming apparent that they represent a critically understudied population. Highlighting our work funded by the ONES award, in this review we argue the understated importance of utilizing infant models to truly understand the etiology of PM-induced predisposition to severe, persistent lung disease. We also touch upon various mechanisms of PM-mediated respiratory damage, with a focus on the emerging importance of environmentally persistent free radicals (EPFRs) ubiquitously present in combustion-derived PM. In conclusion, we briefly comment on strengths/challenges facing current PM research, while giving perspective on how we may address these challenges in the future.

Foetal exposure to maternal stressful events increases the risk of having asthma and atopic diseases in childhood

BACKGROUND

The natural history of asthma and atopic diseases begins in utero. Studies investigating the influence of foetal exposure to maternal stressful life events during pregnancy (SLEP) on asthma and atopic diseases are lacking.

AIM

To test whether the children of mothers who had experienced SLEP are at an increased risk for asthma, atopic eczema and allergic rhinitis.

METHODS

The association between maternal SLEP (at least one among: divorce, mourning or loss of the job) and the occurrence of asthma and atopic diseases in childhood was studied in a population (n = 3854) of children, aged 3-14 yrs, living in Northern Italy. The parents filled in a standardized questionnaire about the children's health and the events occurred to their mothers during pregnancy.

RESULTS

Three hundred and thirty-three (9%) of the mothers experienced SLEP. Their children had a statistically significantly higher lifetime prevalence of wheezing (31.6% vs. 23.1%), asthma (8.9% vs. 5.6%), allergic rhinitis (10.9% vs. 7.3%) and atopic eczema (29.7% vs. 21.1%) than those of mothers without SLEP. After adjusting for potential confounders, the foetal exposure to SLEP was positively associated with wheezing (OR: 1.41, 95% CI: 1.03-1.94), asthma (OR: 1.71, 95% CI: 1.02-2.89), allergic rhinitis (OR: 1.75, 95% CI: 1.08-2.84) and atopic eczema (OR: 1.53, 95% CI: 1.11-2.10).

CONCLUSION

The children of mothers who had experienced SLEP were at a moderately increased risk of having wheezing, asthma, eczema and allergic rhinitis during their childhood. Maternal stress during pregnancy might enhance the expression of asthma and atopic phenotypes in children.

Environmental exposures and respiratory outcomes in children

Asthma is a complex condition where genetic and environmental interactions occur at critical periods in development. The focus of this review was the role of environmental exposures on asthma causation. Selected studies published in 2010 and 2011 were reviewed to illustrate the challenge in relating environmental exposure(s) on asthma causation and also to focus on some exposures currently thought to be important to asthma pathogenesis. Challenges in understanding how environmental exposures may translate into asthma causation are summarised. Inhaled and ingested exposures are described, including microbial products, swimming pools, diet and antenatal tobacco exposure. A final synthesis summarises what is currently understood about childhood asthma causation and what advice might be given to parents and governments interested in reducing asthma risk.

Associations and interactions of genetic polymorphisms in innate immunity genes with early viral infections and susceptibility to asthma and asthma-related phenotypes

BACKGROUND

The innate immune system is essential for host survival because of its ability to recognize invading pathogens and mount defensive responses.

OBJECTIVES

We sought to identify genetic associations of innate immunity genes with atopy and asthma and interactions with early viral infections (first 12 months of life) in a high-risk birth cohort.

METHODS

Three Canadian family-based studies and 1 Australian population-based case-control study (n = 5565) were used to investigate associations of 321 single nucleotide polymorphisms (SNPs) in 26 innate immunity genes with atopy, asthma, atopic asthma, and airway hyperresponsiveness. Interactions between innate immunity genes and early viral exposure to 3 common viruses (parainfluenza, respiratory syncytial virus, and picornavirus) were examined in the Canadian Asthma Primary Prevention Study by using both an affected-only family-based transmission disequilibrium test and case-control methods.

RESULTS

In a joint analysis of all 4 cohorts, IL-1 receptor 2 (IL1R2) and Toll-like receptor 1 (TLR1) SNPs were associated with atopy after correction for multiple comparisons. In addition, an NFKBIA SNP was associated with atopic asthma. Six SNPs (rs1519309 [TLR3], rs740044 [ILIR2], rs4543123 [TLR1], rs5741812 [LBP], rs917998 [IL18RAP], and rs3136641 [NFKBIB]) were significant (P < .05, confirmed with 30,000 permutations) in both the combined analysis of main genetic effects and SNP-virus interaction analyses in both case-control and family-based methods. The TLR1 variant (rs4543123) was associated with both multiple viruses (respiratory syncytial virus and parainfluenza virus) and multiple phenotypes.

CONCLUSION

We have identified novel susceptibility genes for asthma and related traits and interactions between these genes and early-life viral infections.

Air pollution during pregnancy and neonatal outcome: a review

There is increasing evidence of the adverse impact of prenatal exposure to air pollution. This is of particular interest, as exposure during pregnancy--a crucial time span of important biological development--may have long-term implications. The aims of this review are to show current epidemiological evidence of known effects of prenatal exposure to air pollution and present possible mechanisms behind this process. Harmful effects of exposure to air pollution during pregnancy have been shown for different birth outcomes: higher infant mortality, lower birth weight, impaired lung development, increased later respiratory morbidity, and early alterations in immune development. Although results on lower birth weight are somewhat controversial, evidence for higher infant mortality is consistent in studies published worldwide. Possible mechanisms include direct toxicity of particles due to particle translocation across tissue barriers or particle penetration across cellular membranes. The induction of specific processes or interaction with immune cells in either the pregnant mother or the fetus may be possible consequences. Indirect effects could be oxidative stress and inflammation with consequent hemodynamic alterations resulting in decreased placental blood flow and reduced transfer of nutrients to the fetus. The early developmental phase of pregnancy is thought to be very important in determining long-term growth and overall health. So-called "tracking" of somatic growth and lung function is believed to have a huge impact on long-term morbidity, especially from a public health perspective. This is particularly important in areas with high levels of outdoor pollution, where it is practically impossible for an individual to avoid exposure. Especially in these areas, good evidence for the association between prenatal exposure to air pollution and infant mortality exists, clearly indicating the need for more stringent measures to reduce exposure to air pollution.

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.

Lung effects of inhaled corticosteroids in a rhesus monkey model of childhood asthma

BACKGROUND

The risks for infants and young children receiving inhaled corticosteroid (ICS) therapy are largely unknown. Recent clinical studies indicate that ICS therapy in pre-school children with symptoms of asthma result in decreased symptoms without influencing the clinical disease course, but potentially affect postnatal growth and development. The current study employs a primate experimental model to identify the risks posed by ICS therapy.

OBJECTIVE

To (1) establish whether ICS therapy in developing primate lungs reverses pulmonary pathobiology associated with allergic airway disease (AAD) and (2) define the impact of ICS on postnatal lung growth and development in primates.

METHODS

Infant rhesus monkeys were exposed, from 1 through 6 months, to filtered air (FA) with house dust mite allergen and ozone using a protocol that produces AAD (AAD monkeys), or to FA alone (Control monkeys). From three through 6 months, the monkeys were treated daily with ICS (budesonide) or saline.

RESULTS

Several AAD manifestations (airflow restrictions, lavage eosinophilia, basement membrane zone thickening, epithelial mucin composition) were reduced with ICS treatment, without adverse effects on body growth or adrenal function; however, airway branching abnormalities and intraepithelial innervation were not reduced. In addition, several indicators of postnatal lung growth and differentiation: vital capacity, inspiratory capacity, compliance, non-parenchymal lung volume and alveolarization, were increased in both AAD and Control monkeys that received ICS treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Incomplete prevention of pathobiological changes in the airways and disruption of postnatal growth and differentiation of airways and lung parenchyma in response to ICS pose risks for developing primate lungs. These responses also represent two mechanisms that could compromise ICS therapy's ability to alter clinical disease course in young children.

Microbes and asthma: the missing cellular and molecular links

PURPOSE OF REVIEW

In this review, we describe the 'state-of-the-art' in our knowledge of asthma and what gaps exist, which can be exploited in the future for effective translation of our knowledge from the bench or population studies to diagnosis and therapy.

RECENT FINDINGS

The advent of microbiome research has expanded the potential role of microbes in asthma. There has been a significant increase in our understanding of the pathologic, genetic, cellular and molecular mechanisms of asthma. Nonetheless, the contribution of microbes to the genesis, exacerbation and treatment of asthma are poorly understood.

SUMMARY

Asthma is a complex chronic disease of the lung whose incidence is growing at all ages despite the progress that has been made in the areas of diagnosis and treatment of asthma. The complexity is partly due to the environmental insults such as allergens and microbial infections that play differential roles in the pathogenesis of childhood vis-à-vis elderly asthma. Microbes may play important roles in the exacerbation of asthma and hence in the comorbidities due to asthma, and also in the causation of asthma.

Preschool wheeze - impact of early fish introduction and neonatal antibiotics

AIM

The aim of this study was to analyse the risk factors for preschool wheeze with special reference to the early introduction of fish and early antibiotic treatment. To avoid reverse causation regarding antibiotics, we focused on the influence of broad-spectrum antibiotics given during the first week of life.

METHODS

Data were obtained from a prospective, longitudinal study of a cohort of children born in western Sweden where 50% of the birth cohort was randomly selected. The parents answered questionnaires at 6 and 12 months and at 4.5 years of age. The response rate at 4.5 years was 83% (4496 of 5398 questionnaires distributed).

RESULTS

In the multivariate analysis, broad-spectrum antibiotics in the first week increased the risk of recurrent wheeze (≥ 3 episodes) during the last 12 months at age 4.5 years (adjusted OR 2.2; 95% CI 1.3-3.8) and multiple-trigger wheeze (aOR, 2.8; 1.3-6.1). The introduction of fish before the age of 9 months reduced the risk of recurrent wheeze (aOR, 0.6; 0.4-0.8).

CONCLUSION

Treatment with broad-spectrum antibiotics during the first week of life increased the risk of recurrent wheeze and multiple-trigger wheeze at preschool age. The early introduction of fish reduced the risk of recurrent wheeze.

Meta-analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative

BACKGROUND

Several cross-sectional studies during the past 10 years have observed an increased risk of allergic outcomes for children living in damp or mouldy environments.

OBJECTIVE

The objective of this study was to investigate whether reported mould or dampness exposure in early life is associated with the development of allergic disorders in children from eight European birth cohorts.

METHODS

We analysed data from 31 742 children from eight ongoing European birth cohorts. Exposure to mould and allergic health outcomes were assessed by parental questionnaires at different time points. Meta-analyses with fixed- and random-effect models were applied. The number of the studies included in each analysis varied based on the outcome data available for each cohort.

RESULTS

Exposure to visible mould and/or dampness during first 2 years of life was associated with an increased risk of developing asthma: there was a significant association with early asthma symptoms in meta-analyses of four cohorts [0-2 years: adjusted odds ratios (aOR), 1.39 (95% CI, 1.05-1.84)] and with asthma later in childhood in six cohorts [6-8 years: aOR, 1.09 (95% CI, 0.90-1.32) and 3-10 years: aOR, 1.10 (95% CI, 0.90-1.34)]. A statistically significant association was observed in six cohorts with symptoms of allergic rhinitis at school age [6-8 years: aOR, 1.12 (1.02-1.23)] and at any time point between 3 and 10 years [aOR, 1.18 (1.09-1.28)].

CONCLUSION

These findings suggest that a mouldy home environment in early life is associated with an increased risk of asthma particularly in young children and allergic rhinitis symptoms in school-age children.

Maternal intake of fatty acids during pregnancy and allergies in the offspring

Fatty acids (FA) are known to have a number of immunological effects and, accordingly, may play a role in the development of allergic diseases. We investigated the effect of maternal intake of FA during pregnancy on the risk of allergic rhinitis, wheeze and atopic eczema in children aged 5 years. The present study analysed data from the Finnish Type 1 Diabetes Prediction and Prevention Nutrition Study, a population-based birth cohort study with a 5-year follow-up. Complete information on maternal diet (assessed by a validated FFQ) and International Study of Asthma and Allergies in Childhood-based allergic outcomes was available for 2441 children. Cox proportional regression and logistic regression were used for the analyses. After adjusting for potential confounding variables, high maternal consumption of butter and butter spreads (hazard ratio (HR) 1.33; 95 % CI 1.03, 1.71) and higher ratio of n-6:n-3 FA (HR 1.37; 95 % CI 1.07, 1.77) during pregnancy were associated with an increased risk of allergic rhinitis in the offspring by 5 years of age. High maternal intakes of total PUFA (HR 0.71; 95 % CI 0.52, 0.96) and α-linolenic FA (HR 0.73; 95 % CI 0.54, 0.98) were associated with a decreased risk of allergic rhinitis. However, these results lost their significance after adjustment for multiple comparisons. Overall, our data suggest that maternal consumption of butter, the ratio of n-6:n-3 FA and intake of PUFA and α-linolenic FA during pregnancy may be potential determinants of allergic rhinitis in the offspring.

Potential role of antioxidant food supplements, preservatives and colorants in the pathogenesis of allergy and asthma

A significant increase in the incidence of allergy and asthma has been observed during the past decades. The background of this phenomenon has not been well explained, but changes in lifestyle and habits are heavily discussed as contributing factors. Among these is a too clean environment, which may predispose individuals to increased sensitivity to allergic responses. Also the increase in dietary supplements including preservatives and colorants may contribute to this. In vitro, we and others have shown in freshly isolated human peripheral blood mononuclear cells that antioxidant compounds like vitamins C and E as well as food preservatives and colorants exert significant suppressive effects on the Th1 immune activation cascade. The effects observed may be based on the interaction of antioxidant compounds with proinflammatory cascades involving important signal transduction elements such as nuclear factor-κB. Although only obtained in vitro, these results show an anti-inflammatory property of compounds which could shift the Th1-Th2-type immune balance towards Th2-type immunity. This review article discusses the potential role of increased use of antioxidant food supplements as well as preservatives and colorants in the increase in allergy and asthma in the Western world.

Role of innate immunity in the development of allergy and asthma

PURPOSE OF REVIEW

Asthma is essentially a developmental disease, in which the normal growth and development of the respiratory and immune systems are affected by environmental exposures acting on underlying genetic predispositions. The purpose of this review is to examine the role of innate immunity in the lungs in the development of allergy and asthma.

RECENT FINDINGS

Both the innate and adaptive arms of the immune system are immature at birth and undergo prolonged periods of postnatal maturation. As such, they are vulnerable to adverse environmental exposures, both before and after birth. Both genetic predispositions and environmentally induced epigenetic changes in gene expression are likely to contribute to the risk of asthma; however, the relative contributions are unclear. Increasing interest is focused on deficient innate responses of the respiratory epithelium to viral infections and how these may increase the risk of asthma. However, definitive proof that these are primary and not secondary effects is lacking. Although most research has concentrated on the role of respiratory viral infections in increasing the asthma risk, the recent suggestion that the lung has a resident bacteriome and potentially important viral-bacterial interactions in the lungs broadens research scope in this area.

SUMMARY

Classic risk factors for asthma include a family history of asthma and allergies, early and persistent allergic sensitization and viral lower-respiratory infections in early life. However, these factors do not fully explain the risk. Perhaps, the resident pulmonary microbiome and the immune response that this generates during respiratory viral infections will provide the 'missing link' in the epidemiology.

Maternal and childhood asthma: risk factors, interactions, and ramifications

Asthma is emerging as a premier example of a health risk that can largely be molded by the status of the mother and the environmental conditions encountered during sensitive windows of prenatal and early childhood development. While genetic background, allergic status of parents, and predisposition for atopy and inflammation play a role, early-life environmental conditions can completely alter the course of immune and respiratory system development. Environmentally induced alterations that (1) maintain the Th2 bias seen during gestation, (2) block the maturation of innate immune cells and (3) create inflammatory dysfunction in the infant provide the foundation for childhood asthma. No single risk factor can fully explain the increased prevalence of asthma in recent decades but it is assumed that the rapid increase is due to environmental and/or epigenetic changes. Well-established and suspected environmental risk factors cover all categories of early life interactions from diet, exposure to environmental contaminants and drugs, maternal and neonatal infections, hygiene, timing of vaccinations and even the mode of birth delivery. Because asthma is connected to the risk of several comorbid chronic conditions, the benefit of asthma risk reduction and prevention is greater than initially may be apparent. This review discusses strategies to optimize preventative and therapeutic options across life stages.

Early life environment and developmental immunotoxicity in inflammatory dysfunction and disease

Components of the innate immune system such as macrophages and dendritic cells are instrumental in determining the fate of immune responses and are, also, among the most sensitive targets of early life environmental alterations including developmental immunotoxicity (DIT). DIT can impede innate immune cell maturation, disrupt tissue microenvironment, alter immune responses to infectious challenges, and disrupt regulatory responses. Dysregulation of inflammation, such as that observed with DIT, has been linked with an increased risk of chronic inflammatory diseases in both children and adults. In this review, we discuss the relationship between early-life risk factors for innate immune modulation and promotion of dysregulated inflammation associated with chronic inflammatory disease. The health risks from DIT-associated inflammation may extend beyond primary immune dysfunction to include an elevated risk of several later-life, inflammatory-mediated diseases that target a wide range of physiological systems and organs. For this reason, determination of innate immune status should be an integral part of drug and chemical safety evaluation.