The response of children with asthma to ambient particulate is modified by tobacco smoke exposure

Association between childhood asthma and history of assisted reproduction techniques: a systematic review and meta-analysis

Genetic and environmental factors during early development may influence lung growth and impact lung function. We performed a meta-analysis of epidemiological studies examining the association between conception history of assisted reproduction techniques (ART) and childhood asthma. We searched PubMed and Embase up to November 2020 for relevant observational studies and synthesized data data under a fixed or random effects model as appropriate. Heterogeneity was assessed using the I² metric. We identified 13 individual studies including 3,226,386 participants. We did not observe a statistically significant association between ART and physician-diagnosed asthma (n = 9, random OR 1.16; 95% CI 0.94-1.43; I² 61%). We observed a statistically significant association between ART and prescription of asthma medications (n = 6, fixed OR 1.27; 95% CI 1.23-1.32; I² 0%). Wheezing was also associated with ART (n = 4, fixed OR 1.71; 95% CI 1.08-2.72; I² 0%). When we combined studies using any asthma definition, a statistically significant association was observed (random OR 1.19; 95% CI 1.05-1.34; I² 80%).Conclusion: The available observational evidence suggests that the risk of asthma is higher among children born after ART. The mechanism and potential sources of bias behind this association are under scrutiny, and further work is needed to establish causality. What is Known: • "Positive" epidemiological signals for the association between assisted reproduction techniques and asthma stemming from large studies were not replicated by subsequent research. • Any available research synthesis effort so far bears no quantitative aspect. What is New: • The available observational evidence suggests that the risk of asthma is higher among children born after ART. • The mechanism and potential sources of bias behind this association are under scrutiny.

Urine Leukotriene E4: Implications as a Biomarker in Chronic Rhinosinusitis

OBJECTIVE

To provide a comprehensive state-of-the-art review of the emerging role of urine leukotriene E4 (uLTE4) as a biomarker in the diagnosis of chronic rhinosinusitis (CRS), aspirin-exacerbated respiratory disease (AERD), and asthma.

DATA SOURCES

Ovid MEDLINE(R), Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus.

REVIEW METHODS

A state-of-the-art review was performed investigating the role of uLTE4 as a diagnostic biomarker, predictor of disease severity, and potential marker of selected therapeutic efficacy.

CONCLUSIONS

uLTE4 has been shown to be a reliable and clinically relevant biomarker for CRS, AERD, and asthma. uLTE4 is helpful in ongoing efforts to better endotype patients with CRS and to predict disease severity.

IMPLICATIONS FOR PRACTICE

Aside from being a diagnostic biomarker, uLTE4 is also able to differentiate aspirin-tolerant patients from patients with AERD and has been associated with objective disease severity in patients with CRS with nasal polyposis. uLTE4 levels have also been shown to predict response to medical therapy, particularly leukotriene-modifying agents.

Joint effects of ambient air pollution and maternal smoking on neonatal adiposity and childhood BMI trajectories in the Healthy Start study

Coexposure to air pollution and tobacco smoke may influence early-life growth, but few studies have investigated their joint effects. We examined the interaction between fetal exposure to maternal smoking and ozone (O₃) or fine particulate matter (PM_2.5) on birth weight, neonatal adiposity, and body mass index (BMI) trajectories through age 3 years.

Methods

Participants were 526 mother-child pairs, born ≥37 weeks. Cotinine was measured at ~27 weeks gestation. Whole pregnancy and trimester-specific O₃ and PM_2.5 were estimated via. inverse-distance weighted interpolation from stationary monitors. Neonatal adiposity (fat mass percentage) was measured via. air displacement plethysmography. Child weight and length/height were abstracted from medical records. Interaction was assessed by introducing cotinine (<31.5 vs. ≥31.5 ng/mL [indicating active smoking]), O₃/PM_2.5 (low [tertiles 1-2] vs. high [tertile 3]), and their product term in linear regression models for birth weight and neonatal adiposity and mixed-effects models for BMI trajectories.

Results

The rate of BMI growth among offspring jointly exposed to maternal smoking and high PM_2.5 (between 8.1 and 12.7 μg/m³) in the third trimester was more rapid than would be expected due to the individual exposures alone (0.8 kg/m² per square root year; 95% CI = 0.1, 1.5; P for interaction = 0.03). We did not detect interactions between maternal smoking and O₃ or PM_2.5 at any other time on birth weight, neonatal adiposity, or BMI trajectories.

Conclusions

Although PM_2.5 was generally below the EPA annual air quality standards of 12.0 μg/m³, exposure during the third trimester may influence BMI trajectories when combined with maternal smoking.

Early-life exposure to submicron particulate air pollution in relation to asthma development in Chinese preschool children

BACKGROUND

Emerging research suggested an association of early-life particulate air pollution exposure with development of asthma in childhood. However, the potentially differential effects of submicron particulate matter (PM; PM with aerodynamic diameter ≤1 μm [PM₁]) remain largely unknown.

OBJECTIVE

This study primarily aimed to investigate associations of childhood asthma and wheezing with in utero and first-year exposures to size-specific particles.

METHODS

We conducted a large cross-sectional survey among 5788 preschool children aged 3 to 5 years in central China. In utero and first-year exposures to ambient PM₁, PM with aerodynamic diameter less than or equal to 2.5 μm, and PM with aerodynamic diameter less than or equal to 10 μm at 1 × 1-km resolution were assessed using machine learning-based spatiotemporal models. A time-to-event analysis was performed to examine associations between residential PM exposures and childhood onset of asthma and wheezing.

RESULTS

Early-life size-specific PM exposures, particularly during pregnancy, were significantly associated with increased risk of asthma, whereas no evident PM-wheezing associations were observed. Each 10-μg/m³ increase in in utero and first-year PM₁ exposure was accordingly associated with an asthma's hazard ratio in childhood of 1.618 (95% CI, 1.159-2.258; P = .005) and 1.543 (0.822-2.896; P = .177). Subgroup analyses suggest that short breast-feeding duration may aggravate PM-associated risk of childhood asthma. Each 10-μg/m³ increase in in utero exposure to PM₁, for instance, was associated with a hazard ratio of 2.260 (1.393-3.666) among children with 0 to 5 months' breast-feeding and 1.156 (0.721-1.853) among those longer breast-fed.

CONCLUSIONS

Our study added comparative evidence for increased risk of childhood asthma in relation to early-life PM exposures, highlighting stronger associations with ambient PM₁ than with PM with aerodynamic diameter less than or equal to 2.5 μm and PM with aerodynamic diameter less than or equal to 10 μm.

Impact of long-term exposure to ambient air pollution on the incidence of chronic obstructive pulmonary disease: A systematic review and meta-analysis

BACKGROUND

It is well known that air pollution causes respiratory morbidity and mortality by inducing airway inflammation. However, whether long-term exposure to air pollution is associated with increased incidence of chronic obstructive pulmonary disease (COPD) is controversial.

METHODS

We conducted a systematic review and meta-analysis with a random-effects model to calculate the pooled risk estimates of COPD development per 10 μg/m³ increase in individual air pollutants. PubMed, Embase, and Cochrane Library were searched from the date of their inception to August 2019 to identify long-term (at least three years of observation) prospective longitudinal studies that reported the risk of COPD development due to exposure to air pollutants. The air pollutants studied included particulate matter (PM_2.5 and PM₁₀) and nitrogen dioxide (NO₂).

RESULTS

Of the 436 studies identified, seven met our eligibility criteria. Among the seven studies, six, three, and five had data on PM_2.5, PM₁₀, and NO₂, respectively. The meta-analysis results showed that a 10 μg/m³ increase in PM_2.5 is associated with increased incidence of COPD (pooled HR 1.18, 95% CI 1.13-1.23). We also noted that a 10 μg/m³ increase in NO₂ is marginally associated with increased incidence of COPD (pooled HR 1.07, 95% CI 1.00-1.16). PM₁₀ seems to have no significant impact on the incidence of COPD (pooled HR 0.95, 95% CI 0.83-1.08), although the number of studies was too small. Meta-regression analysis found no significant effect modifiers.

CONCLUSIONS

Long-term exposure to PM_2.5 and NO₂ can be associated with increased incidence of COPD.

Untargeted Urinary Metabolomics and Children's Exposure to Secondhand Smoke: The Influence of Individual Differences

Children’s exposure to secondhand smoke (SHS) is a severe public health problem. There is still a lack of evidence regarding panoramic changes in children’s urinary metabolites induced by their involuntary exposure to SHS, and few studies have considered individual differences. This study aims to clarify the SHS-induced changes in urinary metabolites in preschool children by using cross-sectional and longitudinal metabolomics analyses. Urinary metabolites were quantified by using untargeted ultra high-performance liquid chromatography-mass spectrometry (UPLC^(c)-MS/MS). Urine cotinine-measured SHS exposure was examined to determine the exposure level. A cross-sectional study including 17 children in a low-exposure group, 17 in a medium-exposure group, and 17 in a high-exposure group was first conducted. Then, a before–after study in the cohort of children was carried out before and two months after smoking-cessation intervention for family smokers. A total of 43 metabolites were discovered to be related to SHS exposure in children in the cross-sectional analysis (false discovery rate (FDR) corrected p < 0.05, variable importance in the projection (VIP) > 1.0). Only three metabolites were confirmed to be positively associated with children’s exposure to SHS (FDR corrected p < 0.05) in a follow-up longitudinal analysis, including kynurenine, tyrosyl-tryptophan, and 1-(3-pyridinyl)-1,4-butanediol, the latter of which belongs to carbonyl compounds, peptides, and pyridines. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that 1-(3-pyridinyl)-1,4-butanediol and kynurenine were significantly enriched in xenobiotic metabolism by cytochrome P450 (p = 0.040) and tryptophan metabolism (p = 0.030), respectively. These findings provide new insights into the pathophysiological mechanism of SHS and indicate the influence of individual differences in SHS-induced changes in urinary metabolites in children.

Prenatal and early life exposure to particulate matter, environmental tobacco smoke and respiratory symptoms in Mexican children

BACKGROUND

Exposure to particulate matter <2.5 μm in diameter (PM2.5) and environmental tobacco smoke (ETS) are associated with respiratory morbidity starting in utero. However, their potential synergistic effects have not been completely elucidated. Here, we examined the joint effects of prenatal and early life PM2.5 and prenatal ETS exposure on respiratory outcomes in children.

MATERIAL AND METHODS

We studied 536 mother-child dyads in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study in Mexico City. Exposure to PM2.5 was estimated using residence in pregnancy and child's first year of life with a satellite-based spatio-temporal model. ETS exposure was assessed by caregiver's report of any smoker in the household during the second or third trimester. Outcomes included report of ever wheeze and wheeze in the past 12 months (current wheeze) assessed when children were 6-8 years old considered in separate models. Associations were modeled using distributed lag models (DLM) with daily PM2.5 averages for pregnancy and the first year of life, adjusting for child's sex, birth weight z-score, mother's age and education at enrollment, maternal asthma, season of conception and stratified by prenatal ETS exposure (yes/no).

RESULTS

We identified a sensitive window from gestational week 14 through postnatal week 18 during which PM2.5 was associated with higher risk of ever wheeze at age 6-8 years. We also observed a critical window of PM2.5 exposure between postnatal weeks 6-39 and higher risk of current wheeze. We found significant associations between higher prenatal and early life PM2.5 exposure and higher cumulative risk ratios of ever wheeze (RR:3.76, 95%CI [1.41, 10.0] per 5 μg/m3) and current wheeze in the past year (RR:7.91, 95%CI [1.5, 41.6] per 5 μg/m3) only among children born to mothers exposed to ETS in pregnancy when compared to mothers who were not exposed.

CONCLUSIONS

Exposure to prenatal ETS modified the association between prenatal and early life PM2.5 exposure and respiratory outcomes at age 6-8 years. It is important to consider concurrent chemical exposures to more comprehensively characterize children's environmental risk. Interventions aimed at decreasing passive smoking might mitigate the effects of ambient air pollution.

Health effects of concurrent ambient and tobacco smoke-derived particle exposures at low concentrations in children with asthma

Exposure to particulate matter less than 2.5 microns from either ambient pollution (AMB-PM_2.5) or secondhand smoke (SHS-PM_2.5) have been associated with asthma worsening, but there is little information on effects and relative potency with concurrent exposures. We studied health effects of concurrent exposures to AMB-PM_2.5 and SHS-PM_2.5 over a 6-year period in schoolchildren with asthma. Regression calibration with instrumental variables (RCIV) was utilized to estimate effects of personal exposure to low-level SHS and AMB-PM_2.5 on daily albuterol usage and urinary leukotriene E4 (uLTE₄; a biomarker of asthma-related inflammation) using urine cotinine and concentrations from fixed and personal pollution monitors. Each IQR increase in SHS-PM_2.5 exposure was associated with a 6.7% increase (95% CI: 1.0-12.8%) in uLTE₄ on the same day and 9.4% increase (95% CI: -2.6 to 22.7%) in albuterol use the next day, when children were co-exposed to mean levels of AMB-PM_2.5. The dose-response relationship between health outcomes and one pollutant was higher at lower levels of the other pollutant. For example, at lower levels of predicted SHS-PM_2.5 exposure, increases in health outcomes per IQR increase in AMB-PM_2.5 ranged between 2 and 5%, but were negligible at higher SHS-PM_2.5 levels. Comparing at equivalent co-exposure levels, SHS-PM_2.5 was 1.6 times more potent than AMB-PM_2.5 for uLTE₄ (95% CI: 1.1-2.3); estimates for albuterol usage were similar but less significant. Effects at mean co-exposure levels were closer [SHS to AMB-PM_2.5 potency ratio = 1.2 (95% CI: 0.9-1.5) for uLTE₄ and 1.2 (95% CI: 0.7-1.9) for albuterol usage]. In summary, concurrent exposure to relatively low levels of SHS and AMB-PM_2.5 were associated with health outcomes in asthmatic schoolchildren. Dose responses varied with changes in the relative amounts of each pollutant; SHS-PM_2.5 was observed to be more potent than AMB-PM_2.5 when co-exposure levels were equivalent.

Methylation of cysteinyl leukotriene receptor 1 genes associates with lung function in asthmatics exposed to traffic-related air pollution

Air pollution is associated with early declines in lung function and increased levels of asthma-related cysteinyl leukotrienes (CysLT) but a biological pathway linking this rapid response has not been delineated. In this randomized controlled diesel exhaust (DE) challenge study of 16 adult asthmatics, increased exposure-attributable urinary leukotriene E4 (uLTE4, a biomarker of cysteinyl leukotriene production) was correlated (p = 0.04) with declines in forced expiratory volume in 1-second (FEV₁) within 6 hours of exposure. Exposure-attributable uLTE4 increases were correlated (p = 0.02) with increased CysLT receptor 1 (CysLTR1) methylation in peripheral blood mononuclear cells which, in turn, was marginally correlated (p = 0.06) with decreased CysLTR1 expression. Decreased CysLTR1 expression was, in turn, correlated (p = 0.0007) with FEV₁ declines. During the same time period, increased methylation of GPR17 (a negative regulator of CysLTR1) was observed after DE exposure (p = 0.02); this methylation increase was correlated (p = 0.001) with decreased CysLTR1 methylation which, in turn, was marginally correlated (p = 0.06) with increased CysLTR1 expression; increased CysLTR1 expression was correlated (p = 0.0007) with FEV₁ increases. Collectively, these data delineate a potential mechanistic pathway linking increased DE exposure-attributable CysLT levels to lung function declines through changes in CysLTR1-related methylation and gene expression.

Clinical significance of the bronchodilator response in children with severe asthma

BACKGROUND

Our objective was to determine those characteristics associated with reversibility of airflow obstruction and response to maximal bronchodilation in children with severe asthma through the Severe Asthma Research Program (SARP).

METHODS

We performed a cross-sectional analysis evaluating children ages 6 to 17 years with nonsevere asthma (NSA) and severe asthma (SA). Participants underwent spirometry before and after 180 µg of albuterol to determine reversibility (≥12% increase in FEV₁ ). Participants were then given escalating doses up to 720 µg of albuterol to determine their maximum reversibility.

RESULTS

We evaluated 230 children (n = 129 SA, n = 101 NSA) from five centers across the United States in the SARP I and II cohorts. SA (odds ratio [OR], 2.08, 95% confidence interval [CI], 1.05-4.13), second-hand smoke exposure (OR, 2.81, 95%CI, 1.23-6.43), and fractional exhaled nitric oxide (FeNO; OR, 1.97, 95%CI, 1.35-2.87) were associated with increased odds of airway reversibility after maximal bronchodilation, while higher prebronchodilator (BD) FEV₁ % predicted (OR, 0.91, 95%CI, 0.88-0.94) was associated with decreased odds. In an analysis using the SARP III cohort (n = 186), blood neutrophils, immunoglobulin E (IgE), and FEV₁ % predicted were significantly associated with BD reversibility. In addition, children with BD response have greater healthcare utilization. BD reversibility was associated with reduced lung function at enrollment and 1-year follow-up though less decline in lung function over 1 year compared to those without reversibility.

CONCLUSIONS

Lung function, that is FEV₁ % predicted, is a predictor of BD response in children with asthma. Additionally, smoke exposure, higher FeNO or IgE level, and low peripheral blood neutrophils are associated with a greater likelihood of BD reversibility. BD response can identify a phenotype of pediatric asthma associated with low lung function and poor asthma control.

The Role of Leukotrienes as Potential Therapeutic Targets in Allergic Disorders

Leukotrienes (LTs) are lipid mediators that play pivotal roles in acute and chronic inflammation and allergic diseases. They exert their biological effects by binding to specific G-protein-coupled receptors. Each LT receptor subtype exhibits unique functions and expression patterns. LTs play roles in various allergic diseases, including asthma (neutrophilic asthma and aspirin-sensitive asthma), allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and anaphylaxis. This review summarizes the biology of LTs and their receptors, recent developments in the area of anti-LT strategies (in settings such as ongoing clinical studies), and prospects for future therapeutic applications.

Urinary Leukotriene E4 as a Biomarker of Exposure, Susceptibility, and Risk in Asthma: An Update

Measurement of urinary leukotriene E₄ (uLTE₄) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene (CysLT) production and changes in CysLT production. Recent studies have reported on novel LTE4 receptor interactions and genetic polymorphisms causing CysLT variability. The applications of uLTE₄ as a biomarker continue to expand, including evaluation of environmental exposures, asthma severity risk, aspirin sensitivity, predicting atopy in preschool age children, obstructive sleep apnea, and predicting susceptibility to leukotriene receptor antagonists.

Multiobjective grammar-based genetic programming applied to the study of asthma and allergy epidemiology

Background

Asthma and allergies prevalence increased in recent decades, being a serious global health problem. They are complex diseases with strong contextual influence, so that the use of advanced machine learning tools such as genetic programming could be important for the understanding the causal mechanisms explaining those conditions. Here, we applied a multiobjective grammar-based genetic programming (MGGP) to a dataset composed by 1047 subjects. The dataset contains information on the environmental, psychosocial, socioeconomics, nutritional and infectious factors collected from participating children. The objective of this work is to generate models that explain the occurrence of asthma, and two markers of allergy: presence of IgE antibody against common allergens, and skin prick test positivity for common allergens (SPT).

Results

The average of the accuracies of the models for asthma higher in MGGP than C4.5. IgE were higher in MGGP than in both, logistic regression and C4.5. MGGP had levels of accuracy similar to RF, but unlike RF, MGGP was able to generate models that were easy to interpret.

Conclusions

MGGP has shown that infections, psychosocial, nutritional, hygiene, and socioeconomic factors may be related in such an intricate way, that could be hardly detected using traditional regression based epidemiological techniques. The algorithm MGGP was implemented in c ++ and is available on repository: http://bitbucket.org/ciml-ufjf/ciml-lib.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2233-z) contains supplementary material, which is available to authorized users.

Prenatal particulate matter exposure and mitochondrial dysfunction at the maternal-fetal interface: Effect modification by maternal lifetime trauma and child sex

BACKGROUND

Prenatal ambient fine particulate matter (PM_2.5) and maternal chronic psychosocial stress have independently been linked to changes in mithochondrial DNA copy number (mtDNAcn), a marker of mitochondrial response and dysfunction. Further, overlapping research shows sex-specific effects of PM_2.5 and stress on developmental outcomes. Interactions among PM_2.5, maternal stress, and child sex have not been examined in this context.

METHODS

We examined associations among exposure to prenatal PM_2.5, maternal lifetime traumatic stressors, and mtDNAcn at birth in a sociodemographically diverse pregnancy cohort (N=167). Mothers' daily exposure to PM_2.5 over gestation was estimated using a satellite-based spatio-temporally resolved prediction model. Lifetime exposure to traumatic stressors was ascertained using the Life Stressor Checklist-Revised; exposure was categorized as high vs. low based on a median split. Quantitative real-time polymerase chain reaction (qPCR) was used to determine mtDNAcn in placenta and cord blood leukocytes. Bayesian Distributed Lag Interaction regression models (BDLIMs) were used to statistically model and visualize the PM_2.5 timing-dependent pattern of associations with mtDNAcn and explore effect modification by maternal lifetime trauma and child sex.

RESULTS

Increased PM_2.5 exposure across pregnancy was associated with decreased mtDNAcn in cord blood (cumulative effect estimate=-0.78; 95%CI -1.41, -0.16). Higher maternal lifetime trauma was associated with reduced mtDNAcn in placenta (β=-0.33; 95%CI -0.63, -0.02). Among women reporting low trauma, increased PM_2.5 exposure late in pregnancy (30-38weeks gestation) was significantly associated with decreased mtDNAcn in placenta; no significant association was found in the high trauma group. BDLIMs identified a significant 3-way interaction between PM_2.5, maternal trauma, and child sex. Specifically, PM_2.5 exposure between 25 and 40weeks gestation was significantly associated with increased placental mtDNAcn among boys of mothers reporting high trauma. In contrast, PM_2.5 exposure in this same window was significantly associated with decreased placental mtDNAcn among girls of mothers reporting low trauma. Similar 3-way interactive effects were observed in cord blood.

CONCLUSIONS

These results indicate that joint exposure to PM_2.5 in late pregnancy and maternal lifetime trauma influence mtDNAcn at the maternal-fetal interface in a sex-specific manner. Additional studies will assist in understanding if the sex-specific patterns reflect distinct pathophysiological processes in addition to mitochondrial dysfunction.

Maternal exposure to ambient air pollution and fetal growth in North-East Scotland: A population-based study using routine ultrasound scans

BACKGROUND

Maternal ambient air pollution exposure is associated with reduced birthweight. Few studies have examined the effect on growth in utero and none have examined the effect of exposure to particulates less than 2.5µm (PM_2.5) and possible effect modification by smoking status.

OBJECTIVES

Examine the effect of maternal exposure to ambient concentrations of PM₁₀, PM_2.5 and nitrogen dioxide (NO₂) for in utero fetal growth, size at birth and effect modification by smoking status.

METHODS

Administratively acquired second and third trimester fetal measurements (bi-parietal diameter, femur length and abdominal circumference), birth outcomes (weight, crown heel length and occipito-frontal circumference) and maternal details were obtained from routine fetal ultrasound scans and maternity records (period 1994-2009). These were modelled against residential annual pollution concentrations (calendar year mean) adjusting for covariates and stratifying by smoking status.

RESULTS

In the whole sample (n=13,775 pregnancies), exposure to PM₁₀, PM_2.5 and NO₂ was associated with reductions in measurements at birth and biparietal diameter from late second trimester onwards. Among mothers who did not smoke at all during pregnancy (n=11,075), associations between biparietal diameter and pollution exposure remained significant but were insignificant among those who did smoke (n=2700). Femur length and abdominal circumference were not significantly associated with pollution exposure.

CONCLUSIONS

Fetal growth is strongly associated with particulates exposure from later in second trimester onwards but the effect appears to be subsumed by smoking. Typical ambient exposures in this study were relatively low compared to other studies and given these results, it may be necessary to consider reducing recommended "safe" ambient air exposures.

Mycoplasma pneumoniae and health outcomes in children with asthma

BACKGROUND

Acute infections with Mycoplasma pneumoniae (Mp) have been associated with worsening asthma in children. Mp can be present in the respiratory tract for extended periods; it is unknown whether the long-term persistence of Mp in the respiratory tract affects long-term asthma control.

OBJECTIVE

To determine the effect of Mp on asthma control.

METHODS

We enrolled 31 pediatric subjects 3 to 10 years of age with persistent asthma who completed up to 8 visits over a 24-month period. We detected Mp by antigen capture and polymerase chain reaction. Primary outcome measurements included symptom scores, quality of life, medication scores, oral corticosteroid use, health care usage, school absences, and exhaled breath condensate pH.

RESULTS

Low levels of Mp community-acquired respiratory distress syndrome toxin were detected in 20 subjects (64.5%) at enrollment. Subjects with Mp positivity at a given visit had a .579 probability of remaining Mp positive at the subsequent visit, whereas those with Mp negativity had a .348 probability of becoming Mp positive at the following visit. The incidence of Mp overall was higher in the spring and summer months. Overall, we found no significant relation between the detection of Mp and worse outcome measurements at the same visit or at subsequent visits.

CONCLUSION

The long-term persistence of Mp in the respiratory tract is common in children with asthma. However, the detection of Mp was not associated significantly with worse asthma symptoms, quality of life, health care usage, school absences, or exhaled breath condensate pH in this pediatric asthma cohort.

Within-microenvironment exposure to particulate matter and health effects in children with asthma: a pilot study utilizing real-time personal monitoring with GPS interface

BACKGROUND

Most particulate matter (PM) and health studies in children with asthma use exposures averaged over the course of a day and do not take into account spatial/temporal variability that presumably occurs as children move from home, into transit and then school microenvironments. The objectives of this work were to identify increases in morning PM exposure occurring within home, transit and school microenvironments and determine their associations with asthma-related inflammation and rescue medication use.

METHODS

In 2007-2008, thirty Denver-area schoolchildren with asthma performed personal PM exposure monitoring using a real-time sensor integrated with a geographic information system (GIS) to apportion exposures to home, transit and school microenvironments. Concurrently, daily monitoring of the airway inflammatory biomarker urinary leukotriene E4 (uLTE₄) and albuterol usage was performed.

RESULTS

Mean PM exposures each morning were relatively well correlated between microenvironments for subject samples (0.3 < r < 0.8), thus limiting use of this exposure metric to attribute health effects to PM exposure in specific microenvironments. Within-microenvironment increases in exposure, such as would be characterized by one or a series of transient spikes or a sustained increase in concentration (exposure event), however, were not strongly correlated between microenvironments (|r| < 0.25). On days when children were exposed to a ≥ 5μg/m³ exposure event during transit, they demonstrated a 24.0 % increase in uLTE₄ (95 % CI: 1.5 %, 51.5 %) and a 9.7 % (-5.9 %, 27.9 %) increase in albuterol usage compared to days without transit exposure events. Associations between exposure events and health outcomes in home and school microenvironments tended to be positive as well, but weaker than for transit.

CONCLUSIONS

School children with asthma moving across morning microenvironments experience spatially heterogeneous PM exposures with potentially varying health effects.

Regression calibration with instrumental variables for longitudinal models with interaction terms, and application to air pollution studies

In this paper, we derive forms of estimators and associated variances for regression calibration with instrumental variables in longitudinal models that include interaction terms between two unobservable predictors and interactions between these predictors and covariates not measured with error; the inclusion of the latter interactions generalize results we previously reported. The methods are applied to air pollution and health data collected on children with asthma. The new methods allow for the examination of how the relationship between health outcome leukotriene E4 (LTE₄, a biomarker of inflammation) and two unobservable pollutant exposures and their interaction are modified by the presence or absence of upper respiratory infections. The pollutant variables include secondhand smoke and ambient (outdoor) fine particulate matter. Simulations verify the accuracy of the proposed methods under various conditions.

Prenatal Particulate Matter/Tobacco Smoke Increases Infants' Respiratory Infections: COCOA Study

Purpose

To investigate whether prenatal exposure to indoor fine particulate matter (PM_2.5) and environmental tobacco smoke (ETS) affects susceptibility to respiratory tract infections (RTIs) in infancy, to compare their effects between prenatal and postnatal exposure, and to determine whether genetic factors modify these environmental effects.

Methods

The study population consisted of 307 birth cohort infants. A diagnosis of RTIs was based on parental report of a physician's diagnosis. Indoor PM_2.5 and ETS levels were measured during pregnancy and infancy. TaqMan was used for genotyping of nuclear factor erythroid 2-related factor (Nrf2) (rs6726395), glutathione-S-transferase-pi (GSTP) 1 (rs1695), and glutathione-S-transferase-mu (GSTM) 1. Microarrays were used for genome-wide methylation analysis.

Results

Prenatal exposure to indoor PM_2.5 increased the susceptibility of lower RTIs (LRTIs) in infancy (adjusted odds ratio [aOR]=2.11). In terms of combined exposure to both indoor PM_2.5 and ETS, prenatal exposure to both pollutants increased susceptibility to LRTIs (aOR=6.56); however, this association was not found for postnatal exposure. The Nrf2 GG (aOR=23.69), GSTM1 null (aOR=8.18), and GSTP1 AG or GG (aOR=7.37) genotypes increased the combined LRTIs-promoting effects of prenatal exposure to the 2 indoor pollutants. Such effects of prenatal indoor PM_2.5 and ETS exposure were not found for upper RTIs.

Conclusions

Prenatal exposure to both indoor PM_2.5 and ETS may increase susceptibility to LRTIs. This effect can be modified by polymorphisms in reactive oxygen species-related genes.

A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years

OBJECTIVES

Childhood asthma is a complex condition where many environmental factors are implicated in causation. The aim of this study was to complete a systematic review of the literature describing associations between environmental exposures and the development of asthma in young children.

SETTING

A systematic review of the literature up to November 2013 was conducted using key words agreed by the research team. Abstracts were screened and potentially eligible papers reviewed. Papers describing associations between exposures and exacerbation of pre-existing asthma were not included. Papers were placed into the following predefined categories: secondhand smoke (SHS), inhaled chemicals, damp housing/mould, inhaled allergens, air pollution, domestic combustion, dietary exposures, respiratory virus infection and medications.

PARTICIPANTS

Children aged up to 9 years.

PRIMARY OUTCOMES

Diagnosed asthma and wheeze.

RESULTS

14,691 abstracts were identified, 207 papers reviewed and 135 included in the present review of which 15 were systematic reviews, 6 were meta-analyses and 14 were intervention studies. There was consistent evidence linking exposures to SHS, inhaled chemicals, mould, ambient air pollutants, some deficiencies in maternal diet and respiratory viruses to an increased risk for asthma (OR typically increased by 1.5-2.0). There was less consistent evidence linking exposures to pets, breast feeding and infant dietary exposures to asthma risk, and although there were consistent associations between exposures to antibiotics and paracetamol in early life, these associations might reflect reverse causation. There was good evidence that exposures to house dust mites (in isolation) was not associated with asthma risk. Evidence from observational and intervention studies suggest that interactions between exposures were important to asthma causation, where the effect size was typically 1.5-3.0.

CONCLUSIONS

There are many publications reporting associations between environmental exposures and modest changes in risk for asthma in young children, and this review highlights the complex interactions between exposures that further increase risk.

Applicability of the environmental relative moldiness index for quantification of residential mold contamination in an air pollution health effects study

The Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS) investigated the impact of exposure to traffic-related air pollution on the respiratory health of asthmatic children in Detroit, Michigan. Since indoor mold exposure may also contribute to asthma, floor dust samples were collected in participants homes (n = 112) to assess mold contamination using the Environmental Relative Moldiness Index (ERMI). The repeatability of the ERMI over time, as well as ERMI differences between rooms and dust collection methods, was evaluated for insights into the application of the ERMI metric. ERMI values for the standard settled floor dust samples had a mean ± standard deviation of 14.5 ± 7.9, indicating high levels of mold contamination. ERMI values for samples collected from the same home 1 to 7 months apart (n = 52) were consistent and without systematic bias. ERMI values for separate bedroom and living room samples were highly correlated (r = 0.69, n = 66). Vacuum bag dust ERMI values were lower than for floor dust but correlated (r = 0.58, n = 28). These results support the use of the ERMI to evaluate residential mold exposure as a confounder in air pollution health effects studies.

Parameters of lung inflammation in asthmatic as compared to healthy children in a contaminated city

Background

The impact of air pollution on the respiratory system has been estimated on the basis of respiratory symptoms and lung function. However; few studies have compared lung inflammation in healthy and asthmatics children exposed to high levels of air pollution. The aim of the study was to elucidate the modulatory effect of air pollution on Cysteinyl-leukotrienes (Cys-LTs) levels in exhaled breath condensate (EBC) among healthy and asthmatic children.

Methods

We performed a cross-sectional comparative study. Children between 7–12 years of age, asthmatics and non-asthmatics, residents of a city with high levels of PM₁₀ were included. In all cases, forced spirometry, Cys-LTs levels in EBC, and the International Study of Asthma and Allergies in Childhood questionnaire were evaluated. We also obtained average of PM₁₀, CO, SO₂ and O₃ levels during the period of the study by the State Institute of Ecology.

Results

We studied 103 children (51 asthmatics and 52 non-asthmatics). Cys-LTs levels were higher in asthmatics than in non-asthmatics (77.3 ± 21.6 versus 60.3 ± 26.8 pg/ml; p = 0.0005). Also, Cys-LTs levels in children with intermittent asthma were lower than in children with persistent asthma (60.4 ± 20.4 versus 84.7 ± 19.2 pg/ml; p = 0.0001). In the multiple regression model, factors associated with levels of Cys-LTs were passive smoking (β = 13.1, p 0.04) and to be asthmatic (β = 11.5, p 0.03).

Conclusions

Cys-LTs levels are higher in asthmatic children than in healthy children in a contaminated city and its levels are also associated with passive smoking.

Environmental changes, microbiota, and allergic diseases

During the last few decades, the prevalence of allergic disease has increased dramatically. The development of allergic diseases has been attributed to complex interactions between environmental factors and genetic factors. Of the many possible environmental factors, most research has focused on the most commonly encountered environmental factors, such as air pollution and environmental microbiota in combination with climate change. There is increasing evidence that such environmental factors play a critical role in the regulation of the immune response that is associated with allergic diseases, especially in genetically susceptible individuals. This review deals with not only these environmental factors and genetic factors but also their interactions in the development of allergic diseases. It will also emphasize the need for early interventions that can prevent the development of allergic diseases in susceptible populations and how these interventions can be identified.

Outdoor air pollution and asthma

Traffic and power generation are the main sources of urban air pollution. The idea that outdoor air pollution can cause exacerbations of pre-existing asthma is supported by an evidence base that has been accumulating for several decades, with several studies suggesting a contribution to new-onset asthma as well. In this Series paper, we discuss the effects of particulate matter (PM), gaseous pollutants (ozone, nitrogen dioxide, and sulphur dioxide), and mixed traffic-related air pollution. We focus on clinical studies, both epidemiological and experimental, published in the previous 5 years. From a mechanistic perspective, air pollutants probably cause oxidative injury to the airways, leading to inflammation, remodelling, and increased risk of sensitisation. Although several pollutants have been linked to new-onset asthma, the strength of the evidence is variable. We also discuss clinical implications, policy issues, and research gaps relevant to air pollution and asthma.

Associations between environmental exposures and asthma control and exacerbations in young children: a systematic review

OBJECTIVE

To complete a systematic review of the literature describing associations between all environmental exposures and asthma symptoms and exacerbations in children up to mean age of 9 years.

DESIGN

Systematic review.

SETTING

Reference lists of identified studies and reviews were searched for all articles published until November 2013 in electronic databases (MEDLINE, EMBASE, CINAHL, Cochrane Controls Trials Register).

PARTICIPANTS

Studies were selected which examined a link between exposure to environmental factors and asthma symptoms and exacerbations where the study participants were children with a mean age of ≤9 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Indices of asthma symptoms, control and exacerbations.

RESULTS

A total of 27 studies were identified including eight where inhaled allergens and four where environmental tobacco smoke (ETS) were the exposures of interest. There was evidence that exposure to allergen, ETS, poor air quality and unflued heaters had a modest magnitude of effect (ORs between 2 and 3). There was also evidence of interactions observed between exposures such as allergen and ETS.

CONCLUSIONS

Exposure to inhaled allergens, ETS, unflued heaters and poor air quality has an important effect on exacerbations in young children with asthma and should be minimised or, ideally, avoided. Better understanding of the effect of exposure to damp housing, air conditioning and dietary factors plus interactions between environmental exposures associated with exacerbations is required.

Regression calibration for models with two predictor variables measured with error and their interaction, using instrumental variables and longitudinal data

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured-with-error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) - outdoor fine particulate matter and cigarette smoke - and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE 4 , outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory.

Suplatast tosilate ameliorates airway hyperreactivity and inflammation through inhibition of the GATA‑3/IL‑5 signaling pathway in asthmatic rats

Airway hyperreactivity and inflammation are important factors in the aggravation of lung function. Suplatast tosilate (IPD) is a novel and unique anti‑asthma clinical compound. However, the mechanisms of IPD action in the inhibition of asthma remain to be elucidated. The present study aimed to investigate the role of the GATA binding protein 3 (GATA‑3)/interleukin (IL)‑5 signaling pathway in IPD‑induced inhibition of asthma. Sprague‑Dawley rats were sensitized by intraperitoneal injection with ovalbumin (OVA) to establish an animal model of asthma. IPD was administered continuously (C‑IPD) or at a later stage (L‑IPD). Budesonide (BUD) was used as a positive control. Airway resistance and the expression of genes at the mRNA and protein levels were measured. Morphological changes in lung tissue and the percentage of eosinophils (EOS) in peripheral blood were observed and correlation analysis was performed. The results revealed that sensitization by OVA significantly increased airway resistance and the percentage of EOS in peripheral blood and induced significant inflammatory changes in lung tissue, as demonstrated by thick epithelium, goblet cell hyperplasia and submucosal cell infiltration. In addition, sensitization by OVA was found to markedly upregulate IL‑5 mRNA and protein expression. Airway resistance was found to positively correlate with the expression of IL‑5 in the rat lung tissues. Sensitization by OVA was also observed to markedly enhance GATA‑3 protein expression and GATA‑3 levels were found to positively correlate with airway resistance and IL‑5 levels. Similar to the effect of BUD, treatment with C‑IPD or L‑IPD was found to significantly attenuate OVA‑induced increases in airway resistance and the percentage of EOS in peripheral blood. Notably, treatment with C‑IPD or L‑IPD markedly reduced the OVA-induced expression of IL‑5 and GATA‑3. In the present study, IPD intervention was demonstrated to ameliorate airway hyperreactivity and inflammation and the mechanisms may involve inhibition of the GATA‑3/IL‑5 signaling pathway.

Programming of respiratory health in childhood: influence of outdoor air pollution

PURPOSE OF REVIEW

This overview highlights recent experimental and epidemiological evidence for the programming effects of outdoor air pollution exposures during early development on lung function and chronic respiratory disorders, such as asthma and related allergic disorders.

RECENT FINDINGS

Air pollutants may impact anatomy and/or physiological functioning of the lung and interrelated systems. Programming effects may result from pollutant-induced shifts in a number of molecular, cellular, and physiological states and their interacting systems. Specific key regulatory systems susceptible to programming may influence lung development and vulnerability to respiratory diseases, including both central and peripheral components of neuroendocrine pathways and autonomic nervous system (ANS) functioning which, in turn, influence the immune system. Starting in utero, environmental factors, including air pollutants, may permanently organize these systems toward trajectories of enhanced pediatric (e.g., asthma, allergy) as well as adult disease risk (e.g., chronic obstructive pulmonary disease). Evidence supports a central role of oxidative stress in the toxic effects of air pollution. Additional research suggests xenobiotic metabolism and subcellular components, such as mitochondria are targets of ambient air pollution and play a role in asthma and allergy programming. Mechanisms operating at the level of the placenta are being elucidated. Epigenetic mechanisms may be at the roots of adaptive developmental programming.

SUMMARY

Optimal coordinated functioning of many complex processes and their networks of interaction are necessary for normal lung development and the maintenance of respiratory health. Outdoor air pollution may play an important role in early programming of respiratory health and is potentially amenable to intervention.

Respiratory health effects of ambient air pollution: an update

There is new evidence for ambient air pollution (AAP) leading to an increased incidence of respiratory diseases in adults. Research has demonstrated that co-exposures have the potential to dramatically augment the effects of AAP and lower the threshold of effect of a given pollutant. Interactions between genes related to oxidative stress and AAP seem to significantly alter the effect of AAP on an individual and population basis. A better definition of vulnerable populations may bolster local or regional efforts to remediate AAP. Advances in genetic research tools have the potential to identify candidate genes that can guide further research.

Maternal smoking affects lung function and airway inflammation in young children with multiple-trigger wheeze

BACKGROUND

Exposure to tobacco smoke is a well-known risk factor for childhood asthma and reduced lung function, but the effect on airway inflammation in preschool-aged children is unclear.

OBJECTIVE

To examine the effect of parental smoking on lung function and fractional concentration of exhaled nitric oxide (Feno) in relation to both parental reports and children's urine cotinine concentrations in preschool-aged children with multiple-trigger wheeze.

METHODS

A total of 105 3- to 7-year-old children with multiple-trigger wheeze and lung function abnormalities were recruited. Lung function was assessed by impulse oscillometry, and Feno measurements were performed. Exposure to tobacco smoke was determined by parental reports and measurement of children's urinary cotinine concentrations.

RESULTS

Forty-three percent of the children were exposed to environmental tobacco smoke according to parental reports. The Feno level was significantly higher in children with a smoking mother (n = 27) than in children with a nonsmoking mother (23.4 vs 12.5 ppb, P = .006). The Feno level expressed as z score and the cotinine level correlated significantly (P = .03). Respiratory resistance at 5 Hz was higher in children exposed to maternal smoking than in others (0.99 vs 0.88 kPas/L, P = .005). Urinary cotinine concentrations reflected well parental reports on their daily smoking and increased relative to the number of cigarettes smoked in the family (P < .01). Atopy was found in 75% of the children, but it was not associated with the Feno value (P = .65).

CONCLUSION

Maternal smoking was associated with increased Feno value and poorer lung function in steroid-naive preschool children with multiple-trigger wheeze. Larger controlled trials are needed to generalize the results.

Urinary leukotriene E4 as a biomarker of exposure, susceptibility and risk in asthma

Measurement of urinary leukotriene E(4) (uLTE(4)) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene production and changes in cysteinyl leukotriene production. Recent studies have reported on novel uLTE(4) receptor interactions, and new applications for uLTE(4), as a biomarker of environmental exposure to tobacco smoke and ambient air pollution, a predictor of risk for asthma exacerbations related to tobacco smoke, and a marker of susceptibility to leukotriene receptor antagonists.

Air pollution, fetal and infant tobacco smoke exposure, and wheezing in preschool children: a population-based prospective birth cohort

BACKGROUND

Air pollution is associated with asthma exacerbations. We examined the associations of exposure to ambient particulate matter (PM10) and nitrogen dioxide (NO2) with the risk of wheezing in preschool children, and assessed whether these associations were modified by tobacco smoke exposure.

METHODS

This study was embedded in the Generation R Study, a population-based prospective cohort study among 4,634 children. PM10 and NO2 levels were estimated for the home addresses using dispersion modeling. Annual parental reports of wheezing until the age of 3 years and fetal and infant tobacco smoke exposure was obtained by questionnaires.

RESULTS

Average annual PM10 or NO2 exposure levels per year were not associated with wheezing in the same year. Longitudinal analyses revealed non-significant tendencies towards positive associations of PM10 or NO2 exposure levels with wheezing during the first 3 years of life (overall odds ratios (95% confidence interval): 1.21 (0.79, 1.87) and 1.06 (0.92, 1.22)) per 10 μg/m3 increase PM10 and NO2, respectively). Stratified analyses showed that the associations were stronger and only significant among children who were exposed to both fetal and infant tobacco smoke (overall odds ratios 4.54 (1.17, 17.65) and 1.85 (1.15, 2.96)) per 10 μg/m3 increase PM10 and NO2, respectively (p-value for interactions <0.05).

CONCLUSIONS

Our results suggest that long term exposure to traffic-related air pollutants is associated with increased risks of wheezing in children exposed to tobacco smoke in fetal life and infancy. Smoke exposure in early life might lead to increased vulnerability of the lungs to air pollution.

Advances in pediatric asthma in 2012: moving toward asthma prevention

Last year's "Advances in pediatric asthma: moving forward" concluded the following: "Now is also the time to utilize information recorded in electronic medical records to develop innovative disease management plans that will track asthma over time and enable timely decisions on interventions in order to maintain control that can lead to disease remission and prevention." This year's summary will focus on recent advances in pediatric asthma on modifying disease activity, preventing asthma exacerbations, managing severe asthma, and risk factors for predicting and managing early asthma, as indicated in Journal of Allergy and Clinical Immunology publications in 2012. Recent reports continue to shed light on methods to improve asthma management through steps to assess disease activity, tools to standardize outcome measures in asthma, genetic markers that predict risk for asthma and appropriate treatment, and interventions that alter the early presentation of asthma to prevent progression. We are well on our way to creating a pathway around wellness in asthma care and also to use new tools to predict the risk for asthma and take steps to not only prevent asthma exacerbations but also to prevent the early manifestations of the disease and thus prevent its evolution to severe asthma.

Secondhand smoke in combination with ambient air pollution exposure is associated with increasedx CpG methylation and decreased expression of IFN-γ in T effector cells and Foxp3 in T regulatory cells in children

BACKGROUND

Secondhand smoke (SHS) and ambient air pollution (AAP) exposures have been associated with increased prevalence and severity of asthma and DNA modifications of immune cells. In the current study, we examined the association between SHS and AAP with DNA methylation and expression of interferon-gamma (IFN-γ) and forkhead box protein 3 (Foxp3) in T cell populations.

METHODS

Subjects 7-18 years old were recruited from Fresno (high AAP; n = 62) and Stanford, CA (low AAP; n = 40) and divided into SHS-exposed (Fresno: n = 31, Stanford: n = 6) and non-SHS-exposed (nSHS; Fresno: n = 31, Stanford: n = 34) groups. T cells purified from peripheral blood were assessed for levels of DNA methylation and expression of IFN-γ (in effector T cells) or Foxp3 (in regulatory T cells).

RESULTS

Analysis showed a significant increase in mean % CpG methylation of IFN-γ and Foxp3 associated with SHS exposure (IFN-γ: FSHS 62.10%, FnSHS 41.29%, p < 0.05; SSHS 46.67%, SnSHS 24.85%, p < 0.05; Foxp3: FSHS 74.60%, FnSHS 54.44%, p < 0.05; SSHS 62.40%, SnSHS 18.41%, p < 0.05) and a significant decrease in mean transcription levels of both genes (IFN-γ: FSHS 0.75, FnSHS 1.52, p < 0.05; SHS 2.25, nSHS 3.53, p < 0.05; Foxp3: FSHS 0.75, FnSHS 3.29, p < 0.05; SSHS 4.8, SnSHS 7.2, p < 0.05). AAP was also associated with hypermethylation (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05) and decreased transcription of both genes (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05). Average methylation between AAP- and SHS-only exposures was not significantly different (IFN-γ: p = 0.15; Foxp3: p = 0.27), nor was Foxp3 expression (p = 0.08); IFN-γ expression was significantly decreased in AAP-only subjects (p < 0.05).

CONCLUSIONS

Exposures to SHS and AAP are associated with significant hypermethylation and decreased expression of IFN-γ in Teffs and Foxp3 in Tregs. Relative contributions of each exposure to DNA modification and asthma pathogenesis warrant further investigation.

Respiratory viral infections in children with asthma: do they matter and can we prevent them?

BACKGROUND

Asthma is a major public health problem with a huge social and economic burden affecting 300 million people worldwide. Viral respiratory infections are the major cause of acute asthma exacerbations and may contribute to asthma inception in high risk young children with susceptible genetic background. Acute exacerbations are associated with decreased lung growth or accelerated loss of lung function and, as such, add substantially to both the cost and morbidity associated with asthma.

DISCUSSION

While the importance of preventing viral infection is well established, preventive strategies have not been well explored. Good personal hygiene, hand-washing and avoidance of cigarette smoke are likely to reduce respiratory viral infections. Eating a healthy balanced diet, active probiotic supplements and bacterial-derived products, such as OM-85, may reduce recurrent infections in susceptible children. There are no practical anti-viral therapies currently available that are suitable for widespread use.

SUMMARY

Hand hygiene is the best measure to prevent the common cold. A healthy balanced diet, active probiotic supplements and immunostimulant OM-85 may reduce recurrent infections in asthmatic children.