Smoking exposure and allergic sensitization in children according to maternal allergies

Intrauterine Smoke Exposure, microRNA Expression during Human Lung Development, and Childhood Asthma

Intrauterine smoke (IUS) exposure during early childhood has been associated with a number of negative health consequences, including reduced lung function and asthma susceptibility. The biological mechanisms underlying these associations have not been established. MicroRNAs regulate the expression of numerous genes involved in lung development. Thus, investigation of the impact of IUS on miRNA expression during human lung development may elucidate the impact of IUS on post-natal respiratory outcomes. We sought to investigate the effect of IUS exposure on miRNA expression during early lung development. We hypothesized that miRNA-mRNA networks are dysregulated by IUS during human lung development and that these miRNAs may be associated with future risk of asthma and allergy. Human fetal lung samples from a prenatal tissue retrieval program were tested for differential miRNA expression with IUS exposure (measured using placental cotinine concentration). RNA was extracted and miRNA-sequencing was performed. We performed differential expression using IUS exposure, with covariate adjustment. We also considered the above model with an additional sex-by-IUS interaction term, allowing IUS effects to differ by male and female samples. Using paired gene expression profiles, we created sex-stratified miRNA-mRNA correlation networks predictive of IUS using DIABLO. We additionally evaluated whether miRNAs were associated with asthma and allergy outcomes in a cohort of childhood asthma. We profiled pseudoglandular lung miRNA in n = 298 samples, 139 (47%) of which had evidence of IUS exposure. Of 515 miRNAs, 25 were significantly associated with intrauterine smoke exposure (q-value < 0.10). The IUS associated miRNAs were correlated with well-known asthma genes (e.g., ORM1-Like Protein 3, ORDML3) and enriched in disease-relevant pathways (oxidative stress). Eleven IUS-miRNAs were also correlated with clinical measures (e.g., Immunoglobulin E andlungfunction) in children with asthma, further supporting their likely disease relevance. Lastly, we found substantial differences in IUS effects by sex, finding 95 significant IUS-miRNAs in male samples, but only four miRNAs in female samples. The miRNA-mRNA correlation networks were predictive of IUS (AUC = 0.78 in males and 0.86 in females) and suggested that IUS-miRNAs are involved in regulation of disease-relevant genes (e.g., A disintegrin and metalloproteinase domain 19 (ADAM19), LBH regulator of WNT signaling (LBH)) and sex hormone signaling (Coactivator associated methyltransferase 1(CARM1)). Our study demonstrated differential expression of miRNAs by IUS during early prenatal human lung development, which may be modified by sex. Based on their gene targets and correlation to clinical asthma and atopy outcomes, these IUS-miRNAs may be relevant for subsequent allergy and asthma risk. Our study provides insight into the impact of IUS in human fetal lung transcriptional networks and on the developmental origins of asthma and allergic disorders.

The links between allergen exposure and sensitization in children and adolescents: an overview for the clinician

INTRODUCTION

The links between allergen exposure and sensitization are complex and depend not only on the type of allergen but on various genetic and environmental factors.

AREAS COVERED

This review discusses the link between allergen exposure and atopic sensitization for different types of allergens and the factors that mediate or affect this link. For the purposes of this review search of PubMed was undertaken to identify English language articles using the terms 'sensitization' and 'allergen exposure' and 'children/or adolescents.'

EXPERT OPINION

Regarding food sensitization, the available data for peanuts and eggs suggest that there is a window period between 4 and 6 months of age when the introduction of these foods may limit sensitization and clinically overt allergy to the respective foods. As far as it concerns aeroallergens, it seems that there is a complex and variable relationship between mite exposure and specific sensitization especially if the exposure occurs early in life. Early exposure to dog allergens does not seem to be associated with specific sensitization; regarding cats, the results are still inconsistent. Several factors may mediate the relationship between early exposure to allergens and the development of sensitization or clinical allergy.

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

Background

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

Methods

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

Results

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

Conclusions

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

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

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

Inhibitory effects of nicotine derived from cigarette smoke on thymic stromal lymphopoietin production in epidermal keratinocytes

Thymic stromal lymphopoietin (TSLP) is regarded as the main factor responsible for the pathogenesis of atopic dermatitis (AD). Cigarette smoke is an aggravating factor for allergies, but has been reported to decrease the risk of AD. In the present study, we evaluated the role of nicotine, the main constituent in cigarette smoke extract, and its underlying mechanism of action in the regulation of TSLP expression. We found that nicotine significantly inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced TSLP expression in BALB/c mice and the mouse keratinocyte cell line PAM212. Nicotine inhibition of TSLP production was abolished by pretreatments with α7 nicotinic acetylcholine receptor (α7 nAChR) antagonists, AMP-activated protein kinase (AMPK) inhibitor, and phosphoinositide 3-kinase (PI3K) inhibitors. The same inhibitors abolished inhibition of nuclear factor-κB (NF-κB) activation by nicotine. These results suggest that nicotine inhibits the expression of TSLP by suppressing the activation of NF-κB through the α7 nAChR-PI3K-AMPK signaling pathway.

Tobacco smoke exposure and multiplexed immunoglobulin E sensitization in children: a population-based study

BACKGROUND

Although there is evidence that exposure to tobacco smoke is harmful to children's respiratory health, the effects of tobacco smoke exposure on the regulation of immunoglobulin E (IgE)-mediated immune responses to specific allergens remain unclear. This study aimed to investigate the relationship between objectively assessed tobacco smoke exposure and specific IgE profiles for a broad spectrum of allergens in a population setting.

METHODS

Children aged 5-18 years (N = 1315) were assessed using serum cotinine measurement and microarray-based multiplexed detection of specific IgE against 40 allergens.

RESULTS

Serum cotinine levels were positively associated with sensitization to foods (adjusted odds ratio [AOR] = 4.95; 95% CI: 1.59-15.34), cockroaches (AOR = 3.77; 95% CI: 1.49-9.51), and pollen (AOR = 2.84; 95% CI: 1.20-6.73) while the association was borderline significant for animals (AOR = 2.53; 95% CI: 0.92-6.93). No associations were found for sensitization against mites, mold, and latex. When considering the degree of allergic sensitization, serum cotinine levels were positively correlated to the number of sensitization to cockroaches (P = 0.004), pollen (P = 0.006), and foods (P < 0.001), with statistically significant positive dose-response relationships (all P < 0.01). Similar results were observed when summing up specific IgE concentrations for the aforementioned allergen categories.

CONCLUSIONS

The association between tobacco smoke exposure and IgE sensitization to environmental allergens varies for different allergens among children. This study demonstrates that elevated serum cotinine levels are significantly associated with IgE sensitization to cockroaches, grass pollen, and certain foods, with potential dose-dependent relationships.

Airborne pollen levels and drug consumption for seasonal allergic rhinoconjunctivitis: a 10-year study in France

BACKGROUND

Few time-series studies, and none lasting longer than 4 years, have investigated the etiology of treated seasonal allergic rhinoconjunctivitis (SAR) on the basis of anti-allergic medication prescriptions. The aim of this article was to study the short-term relationship between pollen exposure and drug-treated SAR over 10 years in an urban area in central France.

METHODS

A SAR case was defined as the association between an oral antihistamine and a local anti-allergic drug on the same prescription. The relationship between daily changes in pollen concentrations and daily changes in the number of treated SAR cases was analysed using generalized additive models, taking into account confounding factors such as air pollution, weather and days of the week.

RESULTS

Between 2003 and 2012, the total yearly number of treated SAR cases rose from 7265 to 11 315. The relative risk of treated SAR associated with an interquartile increase in pollen concentration increased significantly for Fraxinus, Betula, Carpinus, Platanus, Poaceae and Urticaceae for the whole pollen season, and for Urticaceae in the first semester.

CONCLUSIONS

The prevalence of treated SAR cases rose by about 55% in 10 years. The study not only confirmed the highly allergenic role of Fraxinus, Betula and Poaceae pollens but also showed a relatively unknown association between treated SAR and Carpinus and Platanus pollens, despite their pollen counts being <1% of overall pollen concentration. It also showed robust correlations with Urticaceae pollens, especially during the first semester, suggesting a potential allergenic role of Parietaria pollination in this non-Mediterranean area.

Environmental tobacco smoke exposure and risk of allergic sensitisation in children: a systematic review and meta-analysis

BACKGROUND

Environmental tobacco smoke (ETS) exposure in children is linked with the development of allergic asthma. However, its influence on allergic sensitisation in children has not been conclusively determined.

OBJECTIVE

To systematically review existing evidence of ETS exposure's impact on markers of allergic sensitisation in children.

METHODS

CENTRAL, MEDLINE and EMBASE databases were searched. Included studies assessed following markers of atopic sensitisation: total immunoglobulin E (tIgE) concentrations, at least one specific IgE (sIgE+), and positive skin-prick tests (SPTs+) in ETS-exposed and non-exposed children.

RESULTS

8 studies on the influence of ETS on tIgE concentration (2603 patients), 6 studies on ETS and sIgE+ (9230 participants) and 14 papers on ETS and SPT (14 150 patients) met our inclusion criteria. ETS was shown to raise tIgE concentrations by 27.7 IU/mL (95% CI 7.8 to 47.7; I(2)=58%; results based on 3 studies) and to increase the risk of atopic sensitisation, as assessed by sIgE+ (OR=1.12, 95%CI 1.00 to 1.25; I(2)=54%; results based on 4 studies) and SPT+ (OR=1.15; 95% CI 1.04 to 1.28; I(2)=0%; results based on 10 studies). In a subgroup analysis, this effect was most pronounced in children <7 years (preschoolers) by OR=1.20; (95% CI 1.05 to 1.38) and OR=1.30 (95% CI 1.05 to 1.61), (for sIgE+ and SPT+, respectively).

CONCLUSIONS

Current analysis supports an association between ETS exposure in early childhood and the increased risk of allergic sensitisation. Subgroup meta-analyses demonstrate that younger children suffer the most from detrimental immunomodulating effects of ETS exposure. This study underscores ETS as an important but avoidable risk factor for the development of allergic disease in children.

Determinants of sensitization to allergen in infants and young children

Atopic sensitization is a complex phenomenon that changes dynamically with age throughout childhood; its prevalence increases with age in young children. Additionally, with increasing age, the prevalence of sensitization to inhalant allergens and the prevalence of polysensitization to allergens increase. It is also well established that the development of atopic sensitization is the result of a complex interplay of genetic and environmental factors. However, there is considerable heterogeneity in the literature in terms of the effect of different environmental exposures in young children on the subsequent risk of atopic sensitization and allergic diseases. Previous studies on the relationship, in early life, between pet ownership, sex, exposure to secondhand smoke, exposure to traffic-related air pollution components, and atopic sensitization have yielded different results. Recent studies have highlighted the importance of gene-environment interactions, especially during early childhood, on the risk of subsequent atopic sensitization and allergic diseases. Therefore, pediatricians should consider the genetic and environmental determinants of atopic sensitization in infants and young children when diagnosing and treating patients with allergic diseases. Determining ways in which early exposure to these risk factors in young children may be reduced could be beneficial in preventing the likelihood of developing atopic sensitization.

Persistent effects of maternal smoking during pregnancy on lung function and asthma in adolescents

RATIONALE

The extent to which maternal smoking in pregnancy (MSP) has persisting effects on respiratory health remains uncertain and the mechanisms involved are not fully understood. Alterations in immune function have been proposed as a mechanism contributing to respiratory disease.

OBJECTIVES

To determine whether MSP increases risk of respiratory disorders in adolescence and, if so, whether this occurs by decreased lung function, altered immune function, and/or enhanced atopy.

METHODS

Data on spirometry, bronchial responsiveness, respiratory symptoms, total and allergen-specific IgE and IgG4, immune function, and inflammatory markers were obtained from 1,129 participants in the 14-year follow-up of the Western Australian Pregnancy (Raine) Cohort and related to MSP using regression analyses.

MEASUREMENTS AND MAIN RESULTS

MSP was reported for 21.0% (237 of 1,129) of participants, with 92 (8.1%) reporting current smoking. MSP was associated with some altered immune measures at age 14. MSP was strongly related to reduced lung function in current nonsmokers (forced expiratory flow midexpiratory phase [FEF25-75%], P = 0.016; FEV1/FVC, P = 0.009) and increased risk for current asthma (odds ratio [OR], 1.84; 95% confidence interval [CI], 1.16-2.92; P = 0.01), current wheeze (OR, 1.77; 95% CI, 1.14-2.75; P = 0.011), and exercise-induced wheeze (OR, 2.29; 95% CI, 1.37-3.85; P = 0.002), but not for bronchial hyperresponsiveness or atopy. Adjustment for immune measures and/or lung function in multivariate models did not greatly alter these associations and the increased risks for asthma and wheeze were not modified by sex, atopy, or maternal history of asthma or atopy.

CONCLUSIONS

MSP increases risk of asthma and wheezing in adolescence; mechanisms go beyond reducing lung function and exclude altering immune function or enhancing atopy.

Active or passive exposure to tobacco smoking and allergic rhinitis, allergic dermatitis, and food allergy in adults and children: a systematic review and meta-analysis

BACKGROUND

Allergic rhinitis, allergic dermatitis, and food allergy are extremely common diseases, especially among children, and are frequently associated to each other and to asthma. Smoking is a potential risk factor for these conditions, but so far, results from individual studies have been conflicting. The objective of this study was to examine the evidence for an association between active smoking (AS) or passive exposure to secondhand smoke and allergic conditions.

METHODS AND FINDINGS

We retrieved studies published in any language up to June 30th, 2013 by systematically searching Medline, Embase, the five regional bibliographic databases of the World Health Organization, and ISI-Proceedings databases, by manually examining the references of the original articles and reviews retrieved, and by establishing personal contact with clinical researchers. We included cohort, case-control, and cross-sectional studies reporting odds ratio (OR) or relative risk (RR) estimates and confidence intervals of smoking and allergic conditions, first among the general population and then among children. We retrieved 97 studies on allergic rhinitis, 91 on allergic dermatitis, and eight on food allergy published in 139 different articles. When all studies were analyzed together (showing random effects model results and pooled ORs expressed as RR), allergic rhinitis was not associated with active smoking (pooled RR, 1.02 [95% CI 0.92-1.15]), but was associated with passive smoking (pooled RR 1.10 [95% CI 1.06-1.15]). Allergic dermatitis was associated with both active (pooled RR, 1.21 [95% CI 1.14-1.29]) and passive smoking (pooled RR, 1.07 [95% CI 1.03-1.12]). In children and adolescent, allergic rhinitis was associated with active (pooled RR, 1.40 (95% CI 1.24-1.59) and passive smoking (pooled RR, 1.09 [95% CI 1.04-1.14]). Allergic dermatitis was associated with active (pooled RR, 1.36 [95% CI 1.17-1.46]) and passive smoking (pooled RR, 1.06 [95% CI 1.01-1.11]). Food allergy was associated with SHS (1.43 [1.12-1.83]) when cohort studies only were examined, but not when all studies were combined. The findings are limited by the potential for confounding and bias given that most of the individual studies used a cross-sectional design. Furthermore, the studies showed a high degree of heterogeneity and the exposure and outcome measures were assessed by self-report, which may increase the potential for misclassification.

CONCLUSIONS

We observed very modest associations between smoking and some allergic diseases among adults. Among children and adolescents, both active and passive exposure to SHS were associated with a modest increased risk for allergic diseases, and passive smoking was associated with an increased risk for food allergy. Additional studies with detailed measurement of exposure and better case definition are needed to further explore the role of smoking in allergic diseases.

In utero exposure to second-hand smoke aggravates the response to ovalbumin in adult mice

Second-hand smoke (SHS) exposure in utero exacerbates adult responses to environmental irritants. We tested the hypothesis that effects of in utero SHS exposure on modulating physiological and transcriptome responses in BALB/c mouse lungs after ovalbumin (OVA) challenge extend well into adulthood, and that the responses show a sex bias. We exposed BALB/c mice in utero to SHS or filtered air (AIR), then sensitized and challenged all offspring with OVA from 19 to 23 weeks of age. At the end of the adult OVA challenge, we evaluated pulmonary function, examined histopathology, analyzed bronchoalveolar lavage fluid (BALF), and assessed gene expression changes in the lung samples. All groups exhibited lung inflammation and inflammatory cell infiltration. Pulmonary function testing (airway hyperresponsiveness [AHR], breathing frequency [f]) and BALF (cell differentials, Th1/Th2 cytokines) assessments showed significantly more pronounced lung responses in the SHS-OVA groups than in AIR-OVA groups (AHR, f; eosinophils, neutrophils; IFN-γ, IL-1b, IL-4, IL-5, IL-10, IL-13, KC/CXCL1, TNF-α), with the majority of responses being more pronounced in males than in females. SHS exposure in utero also significantly altered lung gene expression profiles, primarily of genes associated with inflammatory responses and respiratory diseases, including lung cancer and lung fibrosis. Altered expression profiles of chemokines (Cxcl2, Cxcl5, Ccl8, Ccl24), cytokines (Il1b, Il6, Il13) and acute phase response genes (Saa1, Saa3) were confirmed by qRT-PCR. In conclusion, in utero exposure to SHS exacerbates adult lung responses to OVA challenge and promotes a pro-asthmatic milieu in adult lungs; further, males are generally more affected by SHS-OVA than are females.

Effects of airborne birch pollen levels on clinical symptoms of seasonal allergic rhinoconjunctivitis

BACKGROUND

Most panel studies focusing on rhinitis and conjunctivitis symptoms and birch pollen have been performed on a linear basis and have not included air pollution and meteorological variables as potential confounders. The objective of this panel study was to assess the relationship between symptoms of seasonal allergic rhinoconjunctivitis and daily airborne birch pollen concentrations, checking with adequate statistical tools the shapes of concentration-response curves and controlling for confounders.

METHODS

The severity of rhinitis, conjunctivitis, and bronchial symptoms was recorded daily in March and April 2010 (3,311 person-days) in 61 seasonal allergic rhinoconjunctivitis patients sensitized to birch. Data were analyzed with generalized additive and generalized estimating equation models to quantify the effects of birch pollens.

RESULTS

The relationship between birch pollen and the percentage of patients with nasal, ocular and bronchial symptoms was linear until birch daily average concentrations of, respectively, 110, 70, and 70 grains/m(3); it reached a plateau thereafter. For an increase of 10 grains/m(3), the OR (95% CI) for nasal, ocular, and bronchial symptoms were, respectively, 1.07 (1.03-1.12), 1.17 (1.08-1.27), and 1.12 (1.03-1.21). At the beginning of the season, no nasal or ocular symptoms were observed below a threshold of 30 grains/m(3).

CONCLUSIONS

Adequate modeling regression shows that the clinical response to natural exposure to birch pollen in sensitized patients varies during Betula pollen season, with a threshold at the beginning of the season, while over the whole season the relationship is linear for nasal, ocular, and bronchial symptoms up to a saturation point, followed by a plateau.

Association of maternal diabetes and child asthma

BACKGROUND

Perinatal programming is an emerging theory for the fetal origins of chronic disease. Maternal asthma and environmental tobacco smoke (ETS) are two of the best-known triggers for the perinatal programming of asthma, while the potential role of maternal diabetes has not been widely studied.

OBJECTIVE

To determine if maternal diabetes is associated with child asthma, and if so, whether it modifies the effects of ETS exposure and maternal asthma.

METHODS

We studied 3,574 Canadian children, aged 7-8 years, enrolled in a population-based birth cohort. Standardized questionnaires were completed by the children's parents, and data were analyzed by multivariable logistic regression.

RESULTS

Asthma was reported in 442 children (12.4%). Compared to those without asthma, asthmatic children were more likely to have mothers (P = 0.003), but not fathers (P = 0.89), with diabetes. Among children without maternal history of diabetes, the likelihood of child asthma was 1.4-fold higher in those exposed to ETS (adjusted odds ratio, 1.40; 95% confidence interval, 1.13-1.73), and 3.6-fold higher in those with maternal asthma (3.59; 2.71-4.76). Among children born to diabetic mothers, these risks were amplified to 5.7-fold (5.68; 1.18-27.37) and 11.3-fold (11.30; 2.26-56.38), respectively. In the absence of maternal asthma or ETS, maternal diabetes was not associated with child asthma (0.65, 0.16-2.56).

CONCLUSION

Our findings suggest that maternal diabetes may contribute to the perinatal programming of child asthma by amplifying the detrimental effects of ETS exposure and maternal asthma.

Arthropod allergens in urban homes

Dust mites, cockroaches, and pets (cats, dogs) are common in homes worldwide, and many species are the source of potent allergens which cause allergic diseases. These diseases are influenced by genetic predisposition and environmental exposure. Generally, the levels of house dust mite (Der p 1 and Der f 1) and cockroach (Bla g 1, Bla g 2) allergens are used as markers of indoor exposure to arthropods.This article reviews the findings of allergens Der p 1, Der f 1, and Bla g 1 in randomly selected urban households in Zagreb (Croatia) measured from 2006 to 2010 and compares them with exposure to arthropod allergens in other countries. In short, house dust mite allergen levels in Croatian homes are low, but exposure is common; Der p 1 was found in 73 % and Der f 1 in 83 % of the households. By contrast, exposure to cockroach allergen Bla g 1 was both low and uncommon (13 %). Exposure to multiple allergens associated with sensitisation and asthma was not frequent in urban homes in Croatia. However, further studies should include monitoring of both arthropod and pet allergens in high-risk populations in inland and coastal Croatia. They should also investigate a complex dose-response relationship between exposure and sensitisation/asthma development, especially in early childhood.

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

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

Early life precursors, epigenetics, and the development of food allergy

Food allergy (FA), a major clinical and public health concern worldwide, is caused by a complex interplay of environmental exposures, genetic variants, gene-environment interactions, and epigenetic alterations. This review summarizes recent advances surrounding these key factors, with a particular focus on the potential role of epigenetics in the development of FA. Epidemiologic studies have reported a number of nongenetic factors that may influence the risk of FA, such as timing of food introduction and feeding pattern, diet/nutrition, exposure to environmental tobacco smoking, prematurity and low birth weight, microbial exposure, and race/ethnicity. Current studies on the genetics of FA are mainly conducted using candidate gene approaches, which have linked more than 10 genes to the genetic susceptibility of FA. Studies on gene-environment interactions of FA are very limited. Epigenetic alteration has been proposed as one of the mechanisms to mediate the influence of early life environmental exposures and gene-environment interactions on the development of diseases later in life. The role of epigenetics in the regulation of the immune system and the epigenetic effects of some FA-associated environmental exposures are discussed in this review. There is a particular lack of large-scale prospective birth cohort studies that simultaneously assess the interrelationships of early life exposures, genetic susceptibility, epigenomic alterations, and the development of FA. The identification of these key factors and their independent and joint contributions to FA will allow us to gain important insight into the biological mechanisms by which environmental exposures and genetic susceptibility affect the risk of FA and will provide essential information to develop more effective new paradigms in the diagnosis, prevention, and management of FA.

Different implications of paternal and maternal atopy for perinatal IgE production and asthma development

Asthma is a hereditary disease associated with IgE-mediated reaction. Whether maternal atopy and paternal atopy have different impacts on perinatal IgE production and asthma development remains unclear. This paper reviews and summarizes the effects of maternal and paternal atopy on the developmental aspects of IgE production and asthma. Maternal atopy affects both pre- and postnatal IgE production, whereas paternal atopy mainly affects the latter. Maternally transmitted genes GSTP1 and FceRI-beta are associated with lung function and allergic sensitization, respectively. In IgE production and asthma development, the maternal influence on gene-environment interaction is greater than paternal influence. Maternal, paternal, and/or postnatal environmental modulation of allergic responses have been linked to epigenetic mechanisms, which may be good targets for early prevention of asthma.

Outdoor air pollution and asthma in children

BACKGROUND

Asthma, a chronic inflammatory disease of the airways, is associated with reversible airway obstruction and hyperresponsiveness to triggers; clinical symptoms include wheezing, episodic cough, shortness of breath, and increased mucous production. Ambient or outdoor environmental exposure to ozone, particulate matter, sulfur dioxide, and nitrogen oxides has been well documented to exacerbate asthma. Children appear to be most vulnerable to the harmful effects of ambient air pollutants. As their lungs are not completely developed, children may experience greater exposure to environmental pollutants than adults and the higher doses of varied composition may remain in their lungs for a greater duration. Altogether, the negative effects of air pollutants on pulmonary function place children at a greater risk of air pollutant-induced exacerbation of asthma for the duration of their lives.

OBJECTIVES

The aim of this review was to assess recently published literature regarding the influence of air pollution on asthma in children.

METHODS

For this work, we reviewed articles found in PubMed using the key words "outdoor air pollution, asthma, and children" which were published between 2006 and 2009. Only those articles that had a full version available in PubMed were analyzed.

RESULTS

We reviewed studies published between 2006 and 2009 examining the effect of outdoor air pollution on asthma in children. In total, we evaluated 25 articles; of these, 9 were published in 2006, 3 in 2007, 8 in 2008, and 5 in 2009. Of these 25 studies, 1 was a clinical trial, 6 were cross-sectional, 4 were case-control (2 with a case-crossover design), 12 were cohort prospective, and 2 were cohort retrospective studies with varied follow-up times ranging from 10 days to 7 years. The ages of children also differed, ranging from birth to 18 years of age.

CONCLUSIONS

All studies reviewed in this work indicate that outdoor air pollution affects the appearance and exacerbation of asthma in children. Although these findings are of great interest, the limitations of noted works make future investigations of the effect of air pollution on asthma in children essential.

Allergic Rhinitis and Secondhand Tobacco Smoke: A Population-based Study

Background

Allergic rhinitis (AR) is a common disease that affects approximately one-fifth of the U.S. population. Few studies have evaluated the association between secondhand tobacco smoke (SHS) exposure and the impacts on symptom severity in AR. In this study, we evaluated the association of SHS and AR in a community-based study of adult nonsmokers.

Methods

In Washington County, Maryland, 83 subjects with AR (physician diagnosed or reported skin test positive), and 117 nonallergic subjects from the same community were recruited and interviewed. A validated questionnaire was used to assess past and present SHS exposure as well as disease-specific quality of life.

Results

SHS was reported in 34/83 allergic subjects. Compared with AR subjects with no SHS exposure, subjects with AR and SHS were more likely to report a family history of chronic sinusitis (p = 0.04) and use nasal decongestants (p = 0.012). There was also a borderline association with reporting more severe nasal obstruction (p = 0.14) and nasal drainage (p = 0.08). Compared with nonallergic subjects, allergic subjects were more likely to report longer SHS exposure currently (adjusted mean difference = 1.6 hours/week; p = 0.01) and 20 years ago (adjusted mean difference = 2.9 hours/week; p = 0.03).

Conclusion

Past and current SHS may be a risk factor for AR. Allergic subjects with SHS exposure were more likely to use nasal decongestants and to report more severe nasal symptoms such as nasal obstruction and nasal drainage than nonexposed allergic subjects.

Exposure to secondhand tobacco smoke enhances respiratory symptoms and responses to animals in 8,819 children in kindergarten: results from 25 districts in northeast China

BACKGROUND

Experimental data suggest that asthma exacerbation by allergens is enhanced by exposure to environmental tobacco smoke (ETS); however, there is little supporting epidemiologic evidence. To our knowledge, few studies have assessed respiratory symptoms and allergies in this context.

OBJECTIVES

To evaluate whether the association of exposure to animals (indicators of allergen and endotoxin exposure) with asthma-related symptoms is modified by ETS exposure in Chinese children.

METHODS

A cross-sectional study of 8,819 children in kindergarten was conducted in 25 districts in northern China. Information on respiratory health and exposure to indoor allergens was obtained using a standard questionnaire from the American Thoracic Society.

RESULTS

Among the children with ETS exposure in utero, the effects of exposure to animals were significant with respect to persistent cough [adjusted odds ratio (OR) 1.83; 95% confidence interval (CI) 1.12-2.99] and persistent phlegm (adjusted OR 2.40; 95% CI 1.28-4.54). The combined effect of in utero ETS exposure and animal exposure on doctor-diagnosed asthma was approximately as expected on the basis of their independent effects on an additive scale. There was no interaction between animal exposure and ETS exposure in the first 2 years of life or current ETS exposure.

CONCLUSIONS

This study provides evidence that animal and ETS exposure increases the risk of asthma-related symptoms in children in kindergarten. ETS exposure in utero did modify the effect of animal exposure on persistent phlegm and persistent cough but not on doctor-diagnosed asthma among children.

Early exposure to secondhand tobacco smoke and the development of allergic diseases in 4 year old children in Malmö, Sweden

Background

Earlier studies have shown an association between secondhand tobacco smoke and allergy development in children. Furthermore, there is an increased risk of developing an allergy if the parents have an allergy. However, there are only few studies investigating the potential synergistic effect of secondhand tobacco smoke and allergic heredity on the development of an allergy.

Methods

The study was population-based cross-sectional with retrospective information on presence of secondhand tobacco smoke during early life. The study population consisted of children who visited the Child Health Care (CHC) centres in Malmö for their 4-year health checkup during 2006-2008 and whose parents answered a self-administered questionnaire (n = 4,278 children). The questionnaire was distributed to parents of children registered with the CHC and invited for the 4-year checkup during the study period.

Results

There was a two to four times increased odds of the child having an allergy or having sought medical care due to allergic symptoms if at least one parent had an allergy, while there were rather small increased odds related to presence of secondhand smoke during the child's first month in life or at the age of 8 months. However, children with heredity for allergies and with presence of secondhand tobacco smoke during their first year in life had highly increased odds of developing an allergy and having sought medical care due to allergic symptoms at 4 years of age. Thus, there was a synergistic effect enhancing the independent effects of heredity and exposure to secondhand tobacco smoke on allergy development.

Conclusions

Children with a family history of allergies and early exposure to secondhand tobacco smoke is a risk group that prevention and intervention should pay extra attention to. The tobacco smoke effect on children is an essential and urgent question considering it not being self chosen, possibly giving life lasting negative health effects and being possible to reduce.

Clinical aspects of pediatric food allergy and failed oral immune tolerance

Food allergy seems to represent a new spectrum of disease that has elicited significant community concern and extended waiting lists for allergists and gastroenterologists alike. The apparent rise in prevalence of IgE-mediated food allergy (and associated risk of anaphylaxis) has been postulated to result from effects of a "modern lifestyle" but as yet clear environmental risk factors have not yet emerged. Family history seems to contribute to risk suggesting that gene-environment interactions will be important for identifying a subpopulation with increased susceptibility to any identified lifestyle effects. Non-IgE-mediated food allergy (including food-induced enteropathies and colitides, eosinophilic esophagitis, and Crohn's disease) with potentially similar environmental triggers resulting in diverse immune dysregulatory mechanisms. The evidence underpinning the putative rise in food allergy is discussed and potential mechanisms of disease explored. Clinical aspects of various food allergic conditions including non-IgE-mediated food allergy are outlined.

Epidemiology and burden of rhinitis and rhinoconjunctivitis in 9- to 11-year-old children

BACKGROUND

Rhinoconjunctivitis (RC) is regarded as the most common chronic disease of childhood; however, the currently available epidemiological studies on prevalence, burden, and risk factors of RC are insufficient. This analysis aimed to investigate potential risk factors, symptom frequency, and burden of RC.

METHODS

Using the International Study of Asthma and Allergies in Childhood Phase II questionnaires, 6963 elementary school children aged 9-11 years were surveyed in five different city centers of Turkey. All participants were skin-prick tested with common aeroallergens.

RESULTS

The prevalence of ever rhinitis, physician-diagnosed rhinitis, current rhinitis, and current RC were 51.6, 31.0, 43.5, and 23.1%, respectively; 19.8% of children with RC symptoms were atopic to at least one allergen. Among students with RC symptoms, 42.2, 23.9, 35.8, and 28.2% reported moderate-severe interference of daily activities, at least 1 day of absence from school, visit to a health care professional, and any drug usage for rhinitis, respectively. Nasal decongestants and oral antihistamines were the most frequently used treatment. Approximately 70% of RC patients reported perennial symptoms and 42.8% were classified as mild to intermittent. Multivariate logistic regression analysis revealed family history of asthma and/or allergic rhinitis (odds ratio [OR] = 1.863; confidence interval, [CI] = 1.583-2.191; p < 0.001), living in a house with mold and dampness in the 1st year of life (OR = 1.651; CI = 1.356-2.01; p < 0.001), maternal smoking in pregnancy (OR = 1.425; CI = 1.089-1.864; p = 0.011), low monthly income (OR = 1.685; CI = 1.422-1.998; p = 0.001), current wheezing (OR = 2.543; CI = 2.151-3.006; p = 0.001), and current atopic eczema (OR = 2.503; CI = 1.96-3.196; p = 0.001) as significant risk factors for current RC.

CONCLUSION

Along with the high prevalence of RC in childhood, underdiagnosis and undertreatment of the disease are also frequent. The socioeconomic burden of the disease can be reduced by increasing awareness and proper diagnosis/treatment.

Between a cough and a wheeze: dendritic cells at the nexus of tobacco smoke-induced allergic airway sensitization

Exposure to cigarette smoke represents a major risk factor for the development of asthma. Enhanced sensitization toward allergens has been observed in humans and laboratory animals exposed to cigarette smoke. Pulmonary dendritic cells (DCs) are crucially involved in sensitization toward allergens and play an important role in the development of T helper (Th)2-mediated allergic airway inflammation. We propose the concept that aberrant DC activation forms the basis for the deviation of the lung's default tolerogenic response toward allergic inflammation when harmless antigens are concomittantly inhaled with tobacco smoke. This review will summarize evidence suggesting that tobacco smoke can achieve this effect by providing numerous triggers of innate immunity, which can profoundly modulate airway DC biology. Tobacco smoke can affect the airway DC network either directly or indirectly by causing the release of DC-targeted mediators from the pulmonary tissue environment, resulting in the induction of a Th2-oriented pathological immune response. A thorough knowledge of the molecular pathways involved may open the door to novel approaches in the treatment of asthma.

Update on allergies in pregnancy, lactation, and early childhood

The factors responsible for the induction of allergic disease at an early age have not been completely identified. Therefore a major research focus is their identification to elaborate recommendations for prevention of sensitization in high-risk or atopic children. This review analyzes known or suspected reasons for sensitization in pregnant women and infants from both clinical and experimental animal studies. Recent studies and meta-analyses could not confirm the protective effect of an allergen-poor diet on the part of the mother during pregnancy and lactation. Likewise, the type of bottle feeding or the introduction of solid food into the child's diet might not significantly influence the development of atopy, allergy, or asthma in the child's life. Disappointingly, the few preventive measures remaining to reduce the risk of allergic sensitization and atopic diseases in mother and child are the avoidance of smoking and alcohol consumption during pregnancy and lactation and the avoidance of the impairment of gastric function. Further studies are urgently needed to address the influence of certain foods and nutrients, as well as environmental factors, for prevention of allergic diseases in the low- or high-risk infant.

Early-life environment, developmental immunotoxicology, and the risk of pediatric allergic disease including asthma

Incidence of childhood allergic disease including asthma (AD-A) has risen since the mid-20th century with much of the increase linked to changes in environment affecting the immune system. Childhood allergy is an early life disease where predisposing environmental exposures, sensitization, and onset of symptoms all occur before adulthood. Predisposition toward allergic disease (AD) is among the constellation of adverse outcomes following developmental immunotoxicity (DIT; problematic exposure of the developing immune system to xenobiotics and physical environmental factors). Because novel immune maturation events occur in early life, and the pregnancy state itself imposes certain restrictions on immune functional development, the period from mid-gestation until 2 years after birth is one of particular concern relative to DIT and AD-A. Several prenatal-perinatal risk factors have been identified as contributing to a DIT-mediated immune dysfunction and increased risk of AD. These include maternal smoking, environmental tobacco smoke, diesel exhaust and traffic-related particles, heavy metals, antibiotics, environmental estrogens and other endocrine disruptors, and alcohol. Diet and microbial exposure also significantly influence immune maturation and risk of allergy. This review considers (1) the critical developmental windows of vulnerability for the immune system that appear to be targets for risk of AD, (2) a model in which the immune system of the DIT-affected infant exhibits immune dysfunction skewed toward AD, and (3) the lack of allergy-relevant safety testing of drugs and chemicals that could identify DIT hazards and minimize problematic exposure of pregnant women and children.

Prenatal factors and the development of asthma

PURPOSE OF REVIEW

There is increasing evidence that both prenatal and perinatal events influence both allergic diseases and early-life respiratory morbidity.

RECENT FINDINGS

Studies in the last year have suggested that in-utero exposures including tobacco smoke exposure, dietary exposures including vitamin D, and prenatal infection and exposure to microbial products may modulate both atopy and respiratory disease. There have been studies revealing gene x environment interactions between inflammatory pathway genes and in-utero smoke exposure. There have also been studies which have revealed that prenatal exposure to endotoxin may be protective. On the other hand, a recent study also suggested that chorioamnionitis may increase the risk of recurrent wheezing in combination with preterm birth. Finally, two separate large cohort studies evaluated maternal diet in pregnancy and suggested that vitamin D levels may be protective against asthma and wheezing.

SUMMARY

There is epidemiological evidence for multiple prenatal factors impacting early-life respiratory morbidity. The mechanisms of these factors need further investigation and may act via various pathways which include effects on lung development, allergic and nonallergic inflammation, and airway remodeling. It remains to be determined if some of these early-life factors which predispose to wheezing will all translate into increased risk of asthma.