Indoor allergen exposure is a risk factor for sensitization during the first three years of life

Novel Risk Factors for Allergic Rhinitis in Korean Elementary School Children: ARCO-kids Phase II in a Community

Purpose

Allergic rhinitis (AR) is a multifactorial disease whose genetic and environmental risk factors have been studied for decades. Many pediatric studies have pointed out the familial history of allergy, hygiene hypothesis, breast-feeding, pet ownership, and diets as risk factors of AR. However, most of factors are still up for debate. This preliminary report aimed to confirm the known risk factors and find the novel risk factors for AR in the Korean pediatric population.

Methods

A bi-seasonal, winter and summer, study in 2 elementary schools included all students whose parents completed the questionnaire of medical and social histories, quality of life, infant and early-childhood history, and the living styles. Skin prick tests and endoscopic examinations were conducted on all participants.

Results

Among total 1,020 children, 338 participants had AR. The multivariate logistic regression analysis highlighted 6 factors: male gender (OR, 2.10; 95% CI, 1.32-3.33), older age (1.65; 1.03-2.65), previous history of allergic conjunctivitis (14.25; 4.99-40.74), asthma (2.73; 0.96-7.76) and pneumonia (0.39; 0.19-0.82), and an hour increase in daily playing time (0.90; 0.80-1.00).

Conclusions

Lack of pneumonia in early childhood and short playing time are newly found risk factors for Korean pediatric AR in this study confirming male gender, older age and previous history of allergic conjunctivitis and asthma as the risk factors.

Respiratory allergy caused by house dust mites: What do we really know?

The house dust mite (HDM) is a major perennial allergen source and a significant cause of allergic rhinitis and allergic asthma. However, awareness of the condition remains generally low. This review assesses the links between exposure to HDM, development of the allergic response, and pathologic consequences in patients with respiratory allergic diseases. We investigate the epidemiology of HDM allergy to explore the interaction between mites and human subjects at the population, individual, and molecular levels. Core and recent publications were identified by using "house dust mite" as a key search term to evaluate the current knowledge of HDM epidemiology and pathophysiology. Prevalence data for HDM allergen sensitization vary from 65 to 130 million persons in the general population worldwide to as many as 50% among asthmatic patients. Heterogeneity of populations, terminology, and end points in the literature confound estimates, indicating the need for greater standardization in epidemiologic research. Exposure to allergens depends on multiple ecological strata, including climate and mite microhabitats within the domestic environment, with the latter providing opportunity for intervention measures to reduce allergen load. Inhaled mite aeroallergens are unusually virulent: they are able to activate both the adaptive and innate immune responses, potentially offering new avenues for intervention. The role of HDM allergens is crucial in the development of allergic rhinitis and asthma, but the translation of silent sensitization into symptomatic disease is still incompletely understood. Improved understanding of HDMs, their allergens, and their microhabitats will enable development of more effective outcomes for patients with HDM allergy.

Bacterial capsular polysaccharide prevents the onset of asthma through T-cell activation

Over the last four decades, increases in the incidence of immune-mediated diseases in the Western world have been linked to changes in microbial exposure. It is becoming increasingly clear that the normal microbiota in the gut can profoundly alter susceptibility to a wide range of diseases, such as asthma, in which immune homeostasis is disrupted, yet the mechanisms governing this microbial influence remains poorly defined. In this study, we show that gastrointestinal exposure to PSA, a capsular polysaccharide derived from the commensal bacterium Bacteroides fragilis, significantly limits susceptibility to the induction of experimental asthma. We report that direct treatment of mice with PSA generates protection from asthma, and this effect can be given to a naïve recipient by adoptive transfer of CD4(+) T cells from PSA-exposed mice. Remarkably, we found that these PSA-induced T cells are not canonical FoxP3(+) regulatory T cells, but that they potently inhibit both Th1 and Th2 models of asthma in an IL-10-dependent fashion. These findings reveal that bacterial polysaccharides link the microbiota with the peripheral immune system by activating CD4(+)Foxp3(-) T cells upon exposure in the gut, and they facilitate resistance to unnecessary inflammatory responses via the production of IL-10.

Reprint of: Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO2), ozone (O3), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Allergy to furry animals: New insights, diagnostic approaches, and challenges

The prevalence of allergy to furry animals has been increasing, and allergy to cats, dogs, or both is considered a major risk factor for the development of asthma and rhinitis. An important step forward in the diagnosis of allergy to furry animals has been made with the introduction of molecular-based allergy diagnostics. A workshop on furry animals was convened to provide an up-to-date assessment of our understanding of (1) the exposure and immune response to the major mammalian allergens, (2) the relationship of these responses (particularly those to specific proteins or components) to symptoms, and (3) the relevance of these specific antibody responses to current or future investigation of patients presenting with allergic diseases. In this review research results discussed at the workshop are presented, including the effect of concomitant exposures from other allergens or microorganisms, the significance of the community prevalence of furry animals, molecular-based allergy diagnostics, and a detailed discussion of cat and dog components.

Early life environmental predictors of asthma age-of-onset

Prevention strategies that delay the onset of asthma may improve clinical outcomes. To identify early life environmental exposures associated with asthma age-of-onset and potential genetic modifiers of these exposures, we studied 1085 subjects with physician-diagnosed asthma and disease onset at or after age two. Subjects reported retrospectively on their exposure to 17 environmental factors before the age of two. The presence of individual or combinations of these early life exposures was then tested for association with variation in asthma age-of-onset. For exposures significantly associated with age-of-onset, we tested if 26 single nucleotide polymorphisms (SNP) with an established association with allergic disease significantly modified the effect of the exposure. Five environmental exposures were significantly associated with variation in asthma age-of-onset after correction for multiple testing: carpet at home (P = 6 × 10⁻⁵), a serious chest illness (P = 10⁻⁴), father a cigarette smoker (P = 6 × 10⁻⁴) and direct exposure to father's smoking (P = 3 × 10⁻⁴). Individuals with early childhood asthma onset, between the ages of two and six, were 1.4-fold (CI 1.1–1.9) more likely to report having lived in a house with carpet and 2.1-fold (CI 1.3–3.5) more likely to report suffering a serious chest illness before the age of two, than asthmatics with later disease onset. We further found these individual risks to increase to 3.2-fold (CI 1.7–6.0) if carpet exposure and suffering a serious chest illness co-occurred before age two. Paternal smoking exposures were less likely to be reported by asthmatics with early when compared to later disease onset (OR 0.5, CI 0.3–0.7). There were no significant SNP interactions with these environmental exposures after correction for multiple testing. Our results suggest that disease onset in individuals at a high-risk of developing asthma can potentially be delayed by avoiding exposure to carpet at home and preventing serious chest illnesses during the first 2 years of life.

Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO(2)), ozone (O(3)), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Global strategies for reducing the burden from asthma

Asthma is one of the most important chronic diseases in childhood. For several decades, a steady increase in prevalence has been observed worldwide. In the structural collaboration between the Centre for Population Health Services in Edinburgh and the Research Institute CAPHRI of Maastricht we investigated the possibilities for primary prevention of asthma in childhood. We found that a multifaceted approach might be effective in delaying or preventing asthma, whereas a mono-intervention does not seem to have such a protective effect. The most likely explanation is that the development of a multifactorial disease, such as asthma, is extremely difficult, if not impossible, to prevent by eliminating only one risk factor. Underdiagnosis of asthma is still a big problem in primary care. Most patients do not present bronchial symptoms to the general practitioner, even though they have decreased lung function, so they remain unknown and undiagnosed. However, patients who do present with respiratory problems and who have reduced lung function are not always recognised as such. We found that the perception of dyspnoea seems to determine, at least in part, the presentation to the general practitioner with symptoms. These observations show that both the prevention of the development of asthma in early childhood, as well as case finding of asthma in adulthood, do not seem to be very effective in primary care. More research is needed to clarify what steps can be taken to reduce the global burden from asthma.

Association between pet-keeping and asthma in school children

BACKGROUND

The role of pet exposure in childhood asthma and allergy is still controversial. The aim of this study was to investigate the association between pet-keeping during different periods of childhood and asthma and sensitization in school children.

METHODS

One hundred and forty-nine children aged between 7 and 14 years were enrolled in this study. Seventy-four children had current physician-diagnosed asthma, while 75 children did not have asthma. Pet-keeping was investigated by questionnaire. Allergic sensitization to pet allergen was assessed on skin prick tests and specific serum IgE concentration. Logistic regression analysis was performed, taking into account potential confounders.

RESULTS

Early, past and current pet-keeping was not significantly associated with asthma. Neither owning a cat nor dog during childhood was associated with asthma. Early pet-keeping, however, was significantly associated with sensitization to pet allergens (adjusted odds ratio [aOR], 24.11; 95% confidence interval [CI]: 3.28-177.27). Further analysis showed that only early cat-keeping was significantly associated with sensitization to cat allergen (aOR, 51.59; 95%CI: 2.28-1167.07). Keeping a cat or a dog after the first year of life was not associated with sensitization to those allergens.

CONCLUSIONS

Keeping a cat or a dog does not increase risk for asthma. Keeping a cat in the first year of life, however, increases risk of sensitization to cat allergen. Considering that this is a relatively small study, larger, prospective, birth cohort studies are required in Serbia to accurately assess the relationship between pet-keeping, asthma and sensitization.

Immunological parameters associated with the development of allergic rhinitis: a preliminary prospective study

BACKGROUND

Many subjects are sensitized to Japanese cedar pollen but do not develop allergic rhinitis (AR). The aim of this study was to examine the immunologic parameters related to the development of AR in sensitized subjects.

METHODS

The subjects were 33 adults who were sensitized to Japanese cedar pollen, but had not developed as of 2007. Cedar pollen-specific IgE (sIgE) and total IgE (tIgE) in serum, cedar pollen antigen (Cry j 1) Cry j-specific memory Th2 cell clone size, and the Cry j-specific induced regulatory T cell (iTreg) level were examined before and after the season in 2008.

RESULTS

Eight of the 33 subjects developed cedar pollinosis. The sIgE titers before the season in these eight subjects did not differ from those in the subjects who did not develop pollinosis, but the titers after the season were significantly higher in the group that developed pollinosis. The sIgE/tIgE ratio increased in almost all subjects, but the ratio was significantly higher before the season in the subjects who developed pollinosis. Cry j-specific Th2 cells were detected in all subjects, but the clone size only increased in those that developed pollinosis. The Cry j-specific iTreg population did not differ between the two groups.

CONCLUSION

A high sIgE/tIgE ratio before the season may be predictive of development of pollinosis, and an increase in the allergen-specific Th2 clone size during the pollen season could be a biomarker for pollinosis. The role of allergen-specific iTreg cells in the development of pollinosis could not be clarified in this preliminary study.

International consensus on (ICON) pediatric asthma

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Several guidelines and/or consensus documents are available to support medical decisions on pediatric asthma. Although there is no doubt that the use of common systematic approaches for management can considerably improve outcomes, dissemination and implementation of these are still major challenges. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), recently formed by the EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus on (ICON) Pediatric Asthma. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences, thus providing a concise reference. The principles of pediatric asthma management are generally accepted. Overall, the treatment goal is disease control. To achieve this, patients and their parents should be educated to optimally manage the disease, in collaboration with healthcare professionals. Identification and avoidance of triggers is also of significant importance. Assessment and monitoring should be performed regularly to re-evaluate and fine-tune treatment. Pharmacotherapy is the cornerstone of treatment. The optimal use of medication can, in most cases, help patients control symptoms and reduce the risk for future morbidity. The management of exacerbations is a major consideration, independent of chronic treatment. There is a trend toward considering phenotype-specific treatment choices; however, this goal has not yet been achieved.

Associations between socioeconomic position and asthma: findings from a historical cohort

Understanding the association between asthma and socioeconomic position (SEP) is key to identify preventable exposures to prevent inequalities and lessen overall disease burden. We aim to assess the variation in asthma across SEP groups in a historical cohort before the rise in asthma prevalence. Male students participating in a health survey at Glasgow University from 1948 to 1968 (n = 11,274) completed medical history of bronchitis, asthma, hay fever, eczema/urticaria, and reported father’s occupation. A subsample responded to postal follow-up in adulthood (n = 4,101) that collected data on respiratory diseases, early life and adult SEP. Lower father’s occupational class was associated with higher odds of asthma only (asthma without eczema/urticaria or hay fever) (trend adjusted multinomial odds ratio (aMOR) = 1.23, 95 % CI 1.03–1.47) but with lower odds of asthma with atopy (asthma with eczema/urticaria or hay fever) (trend aMOR = 0.66, 95 % CI 0.52–0.83) and atopy alone (trend aMOR = 0.84, 95 % CI 0.75–0.93). Household amenities (<3), in early life was associated with higher odds of adult-onset asthma (onset > 30 years) (OR = 1.48, 95 % CI 1.07–2.05) though this association attenuated after adjusting for age. Adult SEP (household crowding, occupation, income and car ownership) was not associated with adult-onset asthma. Lower father’s occupational class in early life was associated with higher odds of asthma alone but lower odds of asthma with atopy in a cohort that preceded the 1960s rise in asthma prevalence. Different environmental exposures and/or disease awareness may explain this opposed socioeconomic patterning, but it is important to highlight that such patterning was already present before rises in the prevalence of asthma and atopy.

Asthma and COPD - The C/EBP Connection

Asthma and chronic obstructive pulmonary disease (COPD) are the two most prominent chronic inflammatory lung diseases with increasing prevalence. Both diseases are associated with mild or severe remodeling of the airways. In this review, we postulate that the pathologies of asthma and COPD may result from inadequate responses and/or a deregulated balance of a group of cell differentiation regulating factors, the CCAAT/Enhancer Binding Proteins (C/EBPs). In addition, we will argue that the exposure to environmental factors, such as house dust mite and cigarette smoke, changes the response of C/EBPs and are different in diseased cells. These novel insights may lead to a better understanding of the etiology of the diseases and may provide new aspects for therapies.

Perinatal gene-gene and gene-environment interactions on IgE production and asthma development

Atopic asthma is a complex disease associated with IgE-mediated immune reactions. Numerous genome-wide studies identified more than 100 genes in 22 chromosomes associated with atopic asthma, and different genetic backgrounds in different environments could modulate susceptibility to atopic asthma. Current knowledge emphasizes the effect of tobacco smoke on the development of childhood asthma. This suggests that asthma, although heritable, is significantly affected by gene-gene and gene-environment interactions. Evidence has recently shown that molecular mechanism of a complex disease may be limited to not only DNA sequence differences, but also gene-environmental interactions for epigenetic difference. This paper reviews and summarizes how gene-gene and gene-environment interactions affect IgE production and the development of atopic asthma in prenatal and childhood stages. Based on the mechanisms responsible for perinatal gene-environment interactions on IgE production and development of asthma, we formulate several potential strategies to prevent the development of asthma in the perinatal stage.

Allergic rhinitis and quality of life in children

Allergic rhinitis is a respiratory disease caused by an inflammatory process related to IgE mediated reaction versus allergens to which the subject is sensitized. Allergic rhinitis is not an isolated disease because the nasal mucosa inflammation involves paranasal sinuses and lower airways, thus worsening the asthmatic symptoms. Recently, a new classification of allergic rhinitis based on the duration and severity of clinical symptoms has been proposed. This classification takes into consideration both the quality of life and the possible impact of the symptoms on school, work and free-time activities. Children&#x0027;s quality of life is severely compromised by frequent night awakenings, easy fatigue, defects of language and irritability, which can have a negative influence on learning abilities. Allergic rhinitis has a negative impact on the quality of life of the whole family because it can cause interference on social life, and financial costs.

Impact of environmental controls on childhood asthma

Exposure to allergens early in life can lead to sensitization and the development of childhood asthma. It is thought that increased exposure with the advent of modern housing is likely contributing to the rise in prevalence of childhood asthma during the past few decades. The progression from allergen exposure to sensitization and asthma development has been noted with respect to dust mites, pets, cockroach, mouse, mold, tobacco smoke, endotoxin, and air pollution, although some have found a protective effect with pet and endotoxin exposure. Recent studies have shown that allergen remediation may be beneficial in reducing asthma morbidity and development, although there is also some evidence to the contrary. Examples of allergen remediation that have been studied include the use of dust mite-impermeable covers, high-efficiency particulate air filtration, integrated pest management, home repairs, ventilation improvement, and pet removal. Several multifaceted, randomized controlled trials have shown that reducing multiple early allergen exposures with environmental controls is associated with a decreased risk of asthma.

Prevalence of asthma and allergies in 13- to 14-year-old adolescents and the frequency of risk factors in carriers of current asthma in Taubaté, São Paulo, Brazil

BACKGROUND

The objectives of this study were to determine the prevalence of asthma and allergies in 13- to 14-year-old adolescents in the city of Taubaté, São Paulo, Brazil using the INTERNATIONAL STUDY OF ASTHMA AND ALLERGIES IN CHILDHOOD (ISAAC) questionnaire and to describe the presence of risk factors in current asthma carriers.

METHODS

We used a cross-sectional study involving 920 adolescents who completed the ISAAC questionnaire and answered additional questions regarding smoking and the presence of pets and/or insects at home.

RESULTS

The mean prevalence rate of "current asthma" was 15.3% and "asthma ever" was 6.8%. The mean prevalence rate of "current rhinitis" was 36.6% and "rhinitis ever" 37.6%. The prevalence of "eczema ever" was 16.2%. The frequency of active smoking was low (0.7%), and the presence of indoor animals (34%) and of insects (55.1%) was high.

CONCLUSIONS

The prevalence of "current asthma" was twice as high as that of "asthma ever". There was no association between risk factors studied and current asthma.

The significance of environmental exposure on the progression of allergic diseases

In addition to strong genetic influences on atopic sensitization and disease development in infancy and childhood, a number of environmental factors modulate clinical and immunological phenotypes early in life and even prenatally. These factors include gastrointestinal or skin exposure to food allergens; respiratory exposure to indoor and outdoor allergens; presence of environmental pollutants such as tobacco smoke; and exposure to microbial compounds.

Effect of an air cleaner with electrostatic filter on the removal of airborne house dust mite allergens

PURPOSE

The effects of air cleaners on the removal of airborne indoor allergens, especially house dust mites (HDM), are still controversial. The objective of this study is to evaluate the effect of an air cleaner with an electrostatic filter on the removal of airborne mite allergens.

MATERIALS AND METHODS

A dried HDM culture medium that contained mite body particles and excretions was dispersed in a chamber equipped with an electrostatic air cleaner. The number of airborne particles was recorded continuously by a dust spectrometer for 60 minutes. Airborne particles in the chamber were collected on a sampling filter at a flow rate of 10 L/min and the Der f 1 concentration in the filter extracts was measured by two-site ELISA.

RESULTS

The air cleaner efficiently removed airborne HDM particles. The air cleaner removed airborne HDM particles (size 2-12.5 µm) 11.4 ± 2.9 fold (cleaner operating for 15 minutes), 5.4 ± 0.7 fold (cleaner operating for 30 minutes), and 2.4 ± 0.2 fold (cleaner operating for 60 minutes) more than the removal of HDM particles by natural settle down. Removal kinetics differed according to the particle size of the airborne particles. The air cleaner decreased the concentration of Der f 1 in the extraction of airborne particles collected on the air sampling filter by 60.3%.

CONCLUSION

The electrostatic air cleaner can remove airborne HDM allergens and may be useful as a supplementary environmental control tool for HDM sensitized respiratory allergic patients.

Childhood asthma and early life exposure to indoor allergens, endotoxin and beta(1,3)-glucans

BACKGROUND

Divergent results have been reported regarding early life exposure to indoor environmental agents and the risk of asthma and allergic sensitization later in life.

OBJECTIVE

To assess whether early exposure to indoor allergens, beta(1,3)-glucans and endotoxin modifies the risk of allergic diseases at 10 years of age.

METHODS

The concentrations of mite, cat and dog allergens, endotoxin and beta(1,3)-glucans were determined in dust from the homes of 260 two-year-old children with lung function measured at birth (tidal flow volume loops) in the Environment and Childhood Asthma study in Oslo. At 10 years, the health status was assessed in a follow-up study including a structured interview of the parents and an extended clinical examination.

RESULTS

Cat and dog keeping at 2 years of age was reported in 6.5% and 5.5% of the families, respectively. Mite allergens were detected in only 4/260 dust samples. The adjusted odds ratio for asthma at age 10 was 1.20 (95% confidence interval: 1.01-1.43) and 1.22 (1.02-1.46) for bronchial hyperresponsiveness (BHR) per 10 microg/g dust increase in cat allergen exposure at 2 years of age. No association was seen with allergic sensitization. Moreover, endotoxin and beta(1,3)-glucan exposure did not modify the risk of asthma or allergic sensitization. None of the measured environmental factors were associated with lung function at 10 years of age or a relative change in lung function from birth.

CONCLUSION

In a community with a low prevalence of pet keeping and low mite allergen levels, exposure to cat allergens early in life increased the risk of late childhood asthma and BHR, but not the risk of allergic sensitization. No risk modification was seen for dog allergens, endotoxin and beta(1,3)-glucans.

Prevalence and factors linked to allergic rhinitis in 10 and 11-year-old children in Almería. Isaac Phase II, Spain

BACKGROUND

Allergic rhinitis affects 10-30% of children in developed countries and has increased in frequency over the last few decades, probably due to changes in the environment and life style.

AIM

To assess the prevalence, severity, and factors linked to rhinitis in 10 and 11-year-old children from Almeria (Spain).

METHODS

As part of ISAAC II, a cross-sectional survey was conducted among a representative sample of 1143 schoolchildren in spring and autumn of 2001, using homologated questionnaires and skin-prick testing.

RESULTS

The overall prevalence of rhinitis and rhinoconjunctivitis were 38.9% and 24.8%, respectively, 17.9% had medically diagnosed rhinitis. During the previous year symptoms disturbed daily activities and school attendance in some measure in 40% and 26% of children with rhinitis, respectively. The risk factors found in the multiple logistic regression analysis were atopy (OR 2.57; 95% CI 1.92-3.42); cat contact at home during first year of life (OR 2.4 95% CI 1.13-5.12); prior medical diagnosis of asthma (OR 2.2; 95% CI 1.22-4.02); nocturnal cough in absence of colds (OR 1.9; 95% CI 1.25-2.97); diagnosis of rhinitis in one of the parents (OR 1.8; 95% CI 1.31-2.59); wheezing at any time (OR 1.6; 95% CI 1.18-2.28); and nursery school attendance (OR 1.5; 95% CI 1.21-2.5).

CONCLUSIONS

The prevalence of rhinitis found is superior to that of other centres participating in the ISAAC Phases I and II, and coexists with asthma and eczema in many children. The independent risk factors associated to rhinitis are in accordance with previous reports.

Contact to cat or dog, allergies and parental education

Whether or not associations between animal contact and allergy/atopy are homogeneous across social strata has not yet been investigated. The aim of this study was to estimate the association between animal contact (cat, dog) and allergy/atopy in 6-yr-old school beginners, stratified by parental educational level. A total of 30794, 6-yr old children participated in cross-sectional studies between 1991 and 2000 in Germany. Allergic sensitization to common aeroallergens and symptoms and diagnoses of atopic diseases (asthma, eczema, hay fever) were the dependent variables. Contact with dog/cat were the independent variables. Logistic regression was used to adjust for confounding. Analyses were stratified for parental education. Prevalences of hay fever, eczema, specific sensitization to pollen and house dust mite increased, while the prevalence of contact to cat and dog decreased with parental educational level. Globally significant positive associations between cat contact and sensitization to cat (interaction significant) and between dog contact and wheezing remained significant in the highest and medium/highest educational strata respectively. A globally significant inverse association between cat contact and hay fever remained significant in the highest educational stratum only. The inverse association of contact to dog with eczema was globally significant, but not in the strata. When estimating the associations between animal contact and allergy/atopy in children, effect modification by social status should be considered. Cat contact seems to increase the odds of sensitization to cat only in children whose parents have a high level of education.

Dietary antioxidant intake, allergic sensitization and allergic diseases in young children

BACKGROUND

Allergic diseases have risen in prevalence over recent decades. The aetiology remains unclear but is likely to be a result of changing lifestyle and/or environment. A reduction in antioxidant intake, consequent to reduced intake of fresh fruits and vegetables, has been suggested as a possible cause.

OBJECTIVE

To investigate whether dietary antioxidant intake at age 5 was related to atopy at 5 and 8 years of age amongst children in an unselected birth cohort.

METHODS

Children were followed from birth. Parents completed a validated respiratory questionnaire and children were skin prick tested at 5 and 8 years of age. Serum IgE levels were measured at age 5. At age 5, antioxidant intake was assessed using a semi-quantitative food frequency questionnaire (FFQ). A nutrient analysis program computed nutrient intake, and frequency counts of foods high in the antioxidant vitamins A, C and E were assessed.

RESULTS

Eight hundred and sixty-one children completed both the respiratory and FFQ. Beta-carotene intake was associated with reduced risk of allergic sensitization at age 5 [0.80 (0.68-0.93)] and 8 [0.81 (0.70-0.94)]. In addition, beta-carotene intake was negatively associated with total IgE levels (P = 0.002). Vitamin E intake was associated with an increased risk of allergic sensitization [1.19 (1.02-1.39)], only at age 5. There was no association between antioxidant intakes and wheeze or eczema.

CONCLUSION

Increased beta-carotene intake was associated with a reduced risk of allergic sensitization and lower IgE levels, in 5- and 8-year-old children. Dietary antioxidants may play a role in the development of allergic sensitization.

Useful tools for the management of atopic dermatitis

Eczema, frequently named atopic dermatitis, is the most frequent chronic skin disease of early childhood, with a high prevalence in industrialized countries and a relapsing-remitting course that is responsible for a serious burden on affected children and their families. Even though most facets of this disease are nowadays well known and numerous guidelines are available, some confusion still exists regarding certain aspects. First, several names have been proposed for the disorder. We suggest that the name and definition adopted by the World Allergy Organization should be used: 'eczema,' divided into 'atopic,' when an allergic sensitization can be demonstrated, and 'non-atopic,' in the absence of sensitization. Several diagnostic criteria have been proposed, but at present the two most reliable are the 2003 revision by the American Academy of Dermatology of the Hanifin-Rajka criteria, and those by Williams revised in 2005. To date, 20 different clinical scores have been published to assess the severity; however, only the EASI (Eczema Area and Severity Index), the SCORAD (SCORing Atopic Dermatitis), and the POEM (Patient-Oriented Eczema Measure) seem to have been adequately validated and are recommended for use in clinical practice and trials. The diagnostic tests to identify associated allergy or sensitization include skin-prick tests, determination of the specific IgE in serum using different assays, and atopy patch tests; in the case of suspected food allergy, a food challenge may be necessary to define the diagnosis. To evaluate quality of life, tools exist that allow both the child's and family's impairment to be considered. In addition, several algorithms exist to help decide therapy on a step-wise basis. However, such guidelines and algorithms represent only an aid to the physician and not an obligatory directive, since the ultimate judgment regarding any therapy must be performed by the physician and tailored to individual needs. A clear and validated definition of eczema control would permit better monitoring of the disease, similar to the situation with asthma in recent years. Finally, the review examines the role of special textiles in diminishing Staphylococcus aureus skin superinfection, of house dust-mite avoidance measures, and of educational programs for patients and their families, which may all help improve eczema.

Messages from the Aalst Allergy Study

BACKGROUND

The prevalence of sensitization and allergic disease has increased significantly worldwide. The aim of the "Aalst Allergy Study" was to document prevalences of sensitization and allergic symptoms, and to evaluate the effect of personal and environmental influences on these prevalences in an unbiased Belgian pediatric population.

METHODS

A cross-sectional study was performed in an unbiased population of 2021 Belgian schoolchildren (3.4-14.8 years). Skin prick testing with the most common aeroallergens was performed. Allergic symptoms as well as potential risk factors for sensitization and allergic disease were documented by a parental questionnaire.

RESULTS

The prevalence of sensitization to the most common aeroallergens and the prevalence of allergic diseases (eczema, asthma and rhinoconjunctivitis) were in line with the data in the literature. The association of current allergic symptoms with sensitization was only significant in the children aged > or =6 years. Age, gender, body mass index, bedroom environment and exposure to pets were the factors significantly associated with sensitization and allergic symptoms.

CONCLUSIONS

Our study corroborates the reported prevalences of sensitization and allergic diseases. Moreover the study illustrates the complexity of the search for factors involved in the process of sensitization and allergic disease. The impact of different potential causative factors is not only influenced by mutual interactions of these factors, but also by the existence of distinct subtypes of disease.

Genetic and environmental contributions to allergen sensitization in a Chinese twin study

BACKGROUND

Allergic disease is on the rise worldwide. Effective prevention of allergic disease requires comprehensive understanding of the factors that contribute to its intermediate phenotypes, such as sensitization to common allergens.

OBJECTIVE

To estimate the degree of genetic and environmental contributions to sensitization to food and aeroallergens.

METHODS

Sensitization was defined as a positive skin prick test to an allergen. We calculated the zygosity-specific concordance rates and odds ratios (ORs) for sensitization to food and aeroallergens in 826 Chinese twin pairs [472 monozygotic (MZ) and 354 dizygotic (DZ)] aged 12-28 years. We also applied structural equation modelling procedures to estimate genetic and environmental influences on sensitization.

RESULTS

The concordance rates and risk of sensitization in one twin given the presence vs. the absence of sensitization in the other twin were higher in MZ twins than those in DZ twins. However, a large number of MZ twins were discordant in sensitization to common allergens. These observations suggest both genetic and environmental factors influence sensitization. Consistently, the estimated heritability and individual environmental components of the liability to sensitization ranged from 0.51 to 0.68 and 0.32 to 0.49, respectively, based on the best-fitted structural equation model. We also observed high phenotypic correlations between sensitization to two aeroallergens (cockroach and dust mite: 0.83) and two food allergens (peanut and shellfish: 0.58), but only moderate correlations for the pairs between sensitization to a food and an aeroallergen (0.31-0.46). The shared genetic and environmental factors between paired sensitizations contribute to the observed correlations.

CONCLUSION

We demonstrated that sensitization to common food and aeroallergens were influenced by both genetic and environmental factors. Moreover, we found that paired allergen sensitizations might share some common sets of genes and environmental factors. This study underscores the need to further delineate unique and/or pleiotropic genetic and environmental factors for allergen sensitization.

Mite sensitization among Latina women in New York, where dust-mite allergen levels are typically low

In New York (NY), Latinos often have greater asthma morbidity than other ethnicities, and dust-mite sensitization is common despite low allergen levels. We investigated mite allergen exposure and sensitization in atopic and/or asthmatic women, the majority being Puerto Rican. Women (n = 274) recruited for a birth cohort study were visited postnatally. Dust from their homes was analyzed for mite allergens (Der f 1, Der p 1, and Blo t 5). Serum was analyzed for total and allergen-specific IgE. Thirty-seven percent were sensitized to Dermatophagoides pteronyssinus, 34% to Dermatophagoides farinae, and 21% to Blomia tropicalis. Only 5% of NY homes had levels of Der f 1 >2 microg/g; none had Blo t 5 or Der p 1 above this level. Caribbean or Latin American birthplace (a proxy for childhood exposure) was not associated with mite sensitization. Sensitization to D. pteronyssinus and D. farinae was associated with a report of doctor-diagnosed asthma [Odds ratio (OR) = 3.27, P = 0.003; OR = 2.81, P = 0.010, respectively]; sensitization to any mite was associated with asthma medication use in the past 12 months (OR = 3.12, P = 0.004). These associations held even after adjustment for cockroach, mouse, and cat sensitization.

PRACTICAL IMPLICATIONS

Despite the low concentrations of mite allergen in our community, many of the women in the atopically enriched cohort were sensitized to mites, even Blomia tropicalis which is typically found only in tropical environments.

Cat sensitization according to cat window of exposure in adult asthmatics

BACKGROUND

In adults, there is limited information on tolerance to cat, which may be reflected by high IgG4 without IgE sensitization. Early exposure to cat may play a critical role.

OBJECTIVE

The aim was to assess among adults the association of Fel d 1 IgG4, Fel d 1 IgE, skin prick test (SPT) response to cat and pet-related symptoms in relation to exposure to cat considering the period of exposure.

METHODS

SPT response to cat, specific IgE and IgG4 to Fel d 1 were assessed in 167 asthmatics recruited in chest clinics (40 years of age in average) from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA). Childhood and/or current exposure to cat were studied retrospectively.

RESULTS

IgG4 was higher in relation to current cat exposure (0.53 vs. 0.09 ng/mL; P<0.001) and higher in women than in men. The period of cat exposure was significantly related to Fel d 1 IgE, the IgE/IgG4 pattern and cat weal size. The lowest values of Fel d 1 IgE, cat weal size, pet-related nasal or respiratory symptoms were observed in those with both childhood and current exposure as well as the highest proportion of the IgE-/IgG4+ pattern observed in 1.4%, 4.0%, 38.1% and 12.5% of those with -/-, +/-, +/+, -/+ childhood/current exposure, respectively.

CONCLUSIONS

Adult asthmatics exposed to cats since childhood present an immunologic pattern with high IgG4 and low IgE. Continuous exposure may maintain a state of immunological tolerance to cat.

Relationships among prenatal aeroallergen exposure and maternal and cord blood IgE: project ACCESS

BACKGROUND

Whereas some evidence suggests that antigen sensitization may begin prenatally, the influence of maternal allergen exposure during pregnancy has not been fully elucidated.

OBJECTIVES

We examined the relationship between prenatal maternal aeroallergen exposure and cord blood total IgE and the potential mediating/indirect effect of maternal immune response.

METHODS

This study was performed in 301 mother-infant pairs enrolled in the Asthma Coalition on Community, Environment, and Social Stress (ACCESS) project, a study examining the effects of prenatal and early life social and physical environmental exposures on urban asthma risk. Dust samples collected prenatally from mothers' bedrooms were analyzed for cockroach and dust mite allergens. Cord blood was analyzed for total IgE, and maternal serum collected during pregnancy for total and specific IgE. We assessed the relationship between prenatal exposure and cord blood total IgE and the potential mediation effect adjusting for maternal age, race, education, smoking status, and dust collection season; and child's sex and season of birth.

RESULTS

In multivariate models, elevated prenatal dust mite levels (>0.2 microg/g) increased cord blood IgE concentrations by 29% (P = .08), and continuous dust mite concentration was associated with a significant nonlinear increase in cord blood IgE (P = .02). Elevated prenatal exposure to cockroach allergen (>2 U/g) was not associated with cord blood IgE, but showed a significant indirect relationship through maternal total IgE (beta = 0.23; 95% CI, 0.08-0.41).

CONCLUSION

These results demonstrate that maternal prenatal exposure to household allergens may affect cord blood IgE, albeit the underlying mechanism may be allergen-specific.

Parents' smoking habit and prevalence of atopic eczema in 6-7 and 13-14 year-old schoolchildren in Spain. ISAAC phase III

BACKGROUND AND AIMS

Atopic eczema (AE) is the most frequent inflammatory skin disease in childhood in the western world. Several studies have reported a significant increase of prevalence in recent decades and the environmental factors implicated in its aetiology, including environmental tobacco smoke. This study aims to investigate the possible association of AE prevalence in Spanish schoolchildren aged 6-7 and 13-14 years in relation to their parents' smoking habits.

METHODS

We conducted a cross-sectional population-based study with 6-7 year-old (n = 27805) and 13-14 year-old (n = 31235) schoolchildren from 10 Spanish centres. AE prevalence was assessed using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and the Spanish Academy of Dermatology criteria, used in Spain to diagnose AE.

RESULTS

An association was found in school-children aged 6-7 (adjusted for gender, presence of asthma, presence of rhinitis, siblings and mother's level of education) between AE being clinically diagnosed with the mother's smoking habit (RPRa 1.40, 1.10-1.78) and there being more than 2 smokers at home (RPRa 1.34, 1.01-1.78). Regarding the presence of itchy rash, an association was observed with fathers who smoke (RPRa 1.40, 1.13-1.72). Among the 13-14 year-olds, no association was observed in relation to either clinically diagnosed AE or the appearance of itchy rash with parents' smoking habit.

CONCLUSIONS

Our results indicate the risk for children of being exposed to environmental tobacco smoke in terms of AE, especially when they are younger.

The role of indoor allergens in the development of asthma

PURPOSE OF REVIEW

Asthma prevalence has markedly increased over the past 30 years. Although atopy and exposure to environmental allergens are known to exacerbate asthma, recent literature supports a causal role of indoor allergens in disease development.

RECENT FINDINGS

High-risk birth cohorts continue to point to atopy as the main risk factor for developing asthma. Exposure to perennial allergens has also been linked to the development of asthma, though with less consistency. Intervention at the level of allergen exposure and allergic immune response is promising.

SUMMARY

The current model of atopic asthma, the predominant phenotype, incorporates genetic and environmental factors in the development of disease. Although genetic factors are less malleable, the environmental component lends itself to analysis and modification.For many, the development of asthma starts with allergen exposure leading to atopic sensitization and subsequent disease. Several studies support the progression from exposure to sensitization with the potential of extremely high levels of exposure leading to tolerance. Likewise, the progression from atopy to asthma is well documented,especially in genetically predisposed children. Recent intervention trials confirm these findings and begin to show promise for the prevention of asthma by interrupting the allergen exposure==>allergen sensitization==>atopic asthma pathway.

Environmental exposures and respiratory morbidity among very low birth weight infants at 1 year of life

INTRODUCTION

Preterm infants have a substantially increased risk of developing respiratory illnesses. The goal of this study was to consider the impact of modifiable postnatal exposures on respiratory morbidity among a cohort of very low birth weight (VLBW) infants.

OBJECTIVES

(1) Assess the rates of respiratory morbidity and exposure to indoor respiratory triggers in a population of VLBW infants at 1 year; (2) determine the association between exposures and respiratory morbidity.

METHODS

We enrolled 124 VLBW infants into a prospective cohort study. Parents were called at 1 year to assess respiratory outcomes and environmental exposures. We used bivariate and multivariate analyses to assess the relationship between environmental exposures and acute care for respiratory illnesses.

RESULTS

At 1 year, 9% of infants had physician-diagnosed asthma, 47% required >or=1 acute visit and 11% required hospitalisation for respiratory illness. The majority of infants (82%) were exposed to at least one indoor respiratory trigger. Infants living with a smoker (61% vs 40%) and infants exposed to pests (62% vs 39%) were more likely than unexposed infants to require acute care for respiratory problems. In a multivariate regression controlling for demographics, birth weight, bronchopulmonary dysplasia, and family history of asthma or allergies, both living with a smoker (OR 2.62; CI 1.09 to 6.29) and exposure to pests (OR 4.41; CI 1.22 to 15.94) were independently associated with the need for acute care for respiratory illnesses.

CONCLUSIONS

In this sample, respiratory morbidity and exposure to triggers were common. VLBW infants may benefit from interventions that decrease exposure to respiratory triggers.

Strategies for primary prevention of atopy in children

In recent decades, the prevalence of atopic diseases such as asthma, hayfever, food allergy, and atopic dermatitis has been steadily increasing. Unfortunately, more advances have been made in secondary prevention of symptoms and exacerbations than in primary prevention. One barrier to adopting prevention strategies is uncertainty regarding the cause of atopy. A genetic predisposition has been well documented. However, other factors, including diet, environment, infections, medications, and gastrointestinal flora, all play a role in the development of atopic disease. Modifying these factors holds promise for stopping the atopic march in the future. This paper reviews advances that have been made in the primary prevention of atopic disease.

Balance between early life tolerance and sensitization in allergy: dependence on the timing and intensity of prenatal and postnatal allergen exposure of the mother

Allergens can be maternally transferred to the fetus or neonate, though it is uncertain how this initial allergen exposure may impact the development of allergy responses. To evaluate the roles of timing and level of maternal allergen exposure in the early life sensitization of progeny, female BALB/c mice were given ovalbumin (OVA) orally during pregnancy, lactation or weekly at each stage to investigate the immunoglobulin E (IgE) antibody production and cellular responsiveness of their offspring. Exposure to OVA during pregnancy was also evaluated in OVA-specific T-cell receptor (TCR) transgenic (DO11.10) mice. The effect of prenatal antigen exposure on offspring sensitization was dependent on antigen intake, with low-dose OVA inducing tolerance followed by neonatal immunization that was sustained even when pups were immunized when 3 weeks old. These offspring received high levels of transforming growth factor-beta via breastfeeding. High-dose exposure during the first week of pregnancy or perinatal period induced transient inhibition of IgE production following neonatal immunization; although for later immunization IgE production was enhanced in these offspring. Postnatal maternal antigen exposure provided OVA transference via breastfeeding, which consequently induced increased offspring susceptibility to IgE antibody production according to week post-birth. The effect of low-dose maternal exposure during pregnancy was further evaluated using OVA transgenic TCR dams as a model. These progeny presented pronounced entry of CD4(+) T cells into the S phase of the cell cycle with a skewed T helper type 2 response early in life, revealing the occurrence of allergen priming in utero. The balance between tolerance and sensitization depended on the amount and timing of maternal allergen intake during pregnancy.

Anti-cockroach and anti-mouse IgE are associated with early wheeze and atopy in an inner-city birth cohort

BACKGROUND

The relationships between cockroach and mouse allergen exposure, anti-cockroach and anti-mouse IgE, and wheeze, rhinitis, and atopic dermatitis in children as young as age 3 years are of public health importance but have not been thoroughly evaluated.

OBJECTIVE

We hypothesized that inner-city children might have anti-cockroach and anti-mouse IgE by age 3 years, and their presence would be associated with respiratory and atopic symptoms.

METHODS

Children were followed prospectively from birth through age 3 years (n = 404). Residential levels of cockroach and mouse allergens, sera levels of anti-cockroach and anti-mouse IgE, and parental report of wheeze, rhinitis, and atopic dermatitis were measured.

RESULTS

The odds of early wheeze were significantly higher among children who had IgE to cockroach (odds ratio [OR], 3.3; 95% CI, 1.8-6.2), mouse (OR, 4.6; 95% CI, 2.3-9.0), or both (OR, 9.7; 95% CI, 3.4-27.3). The odds of rhinitis or atopic dermatitis were also higher among children with IgE to cockroach, mouse, or both. Higher IgE class to cockroach and mouse was associated with wheeze and atopic dermatitis (tests for trend, P < .002).

CONCLUSIONS

Children age 2 to 3 years who have anti-cockroach and anti-mouse IgE are at increased risk of wheeze and atopy. Moreover, a dose-response relationship was found between higher IgE class and increased prevalence of wheeze, rhinitis, or atopic dermatitis. These findings indicate the importance of reducing exposure to cockroach and mouse allergens for susceptible children.

Meta-analysis of determinants for pet ownership in 12 European birth cohorts on asthma and allergies: a GA2LEN initiative

BACKGROUND

Studies on pet ownership as a risk or protective factor for asthma and allergy show inconsistent results. This may be on account of insufficient adjustment of confounding factors.

AIM

The objective of this study was to describe determinants of cat and dog ownership in European families with and without allergies.

METHODS

Within the EU-funded network of excellence GA(2)LEN, we performed meta-analyses with data from 12 ongoing European birth cohort studies on asthma and allergy. Each of the birth cohort studies enrolled between 485 and 4089 children. Pet ownership, allergic status (asthma, allergic rhinitis, eczema) of parents and siblings, parental education, access to ground floor, and number of people living at home were assessed by questionnaires.

RESULTS

Among the 25 056 families from seven European countries cats (14.9%) were more common than dogs (12.0%). Allergic family history significantly reduced the odds to own a cat (adjusted combined random-effect OR 0.91; 95% CI 0.85-0.99), or dog (0.90; 0.86-0.94). A higher parental educational level had even more pronounced effects on cat (0.84; 0.71-0.98), and dog ownership (0.61; 0.54-0.70). Elder siblings reduced the odds to own cats, but not dogs. Convenient ground access significantly increased the odds, whereas crowding at home was not associated with cat or dog ownership.

CONCLUSIONS

The chances to own a cat or dog were significantly reduced in allergic families, in parents with a higher educational level, and in homes without convenient ground access. In addition to parental allergies, social and housing factors should be considered as potential confounders in studies on pet exposure and allergic diseases.

Risk factors of childhood asthma in Sao Jose do Rio Preto, Sao Paulo, Brazil

BACKGROUND

Epidemiological studies have shown increased prevalence of asthma over the last decades and a considerable variation in these rates between different countries, mainly developed. Changes in lifestyle of different populations could explain the increasing prevalence of asthma and its different rates in different communities.

OBJECTIVES

A case-control study was conducted to investigate some risks factors associated to asthma in schoolchildren in São José do Rio Preto, São Paulo, Brazil.

CASUISTIC AND METHODS

A total of 3793 self-administered written questionnaire (WQ) was filled in by parents of 6-7-year-old schoolchildren, applying the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. Additionally, was added a supplementary WQ evaluating risk factors: gender, personal history of rhinitis and atopic eczema, familial history of atopy, older siblings, day care, breastfeeding, and exposure to pets and to cigarette smoking. Children whose parents responded affirmatively to question 'Has your child had wheezing in the past 12 monthsquest;' were identified as having current asthma.

RESULTS

The prevalence of current asthma was 18.3%. In multivariate analysis the following risk factors were associated with asthma: rhinitis (OR = 10.6; 95% CI = 8.27-13.56), atopic eczema (OR = 1.54; 95% CI = 1.00-2.35), father with asthma (OR = 3.49; 95% CI = 1.83-6.67), mother with asthma (OR = 1.84; 95% CI = 1.11-3.05), current exposure to pets (OR = 1.83; 95% CI = 1.45-2.32) and passive tobacco smoking exposure (OR = 1.43; 95% CI = 1.12-1.83).

CONCLUSIONS

Our results show that genetic background, environmental factors and the presence of co-morbidities such as rhinitis and atopic eczema are associated to the genesis of asthma in Brazilian schoolchildren.

Primary asthma prevention: is it possible?

Asthma, which typically begins in childhood and is the most common chronic disease of childhood, has reached epidemic proportions. Asthma is associated with gene-environment interactions, and there is consensus that a "window of opportunity" exists early in life when environmental factors may influence its development. This review considers biologic and sociologic factors in the development of allergy and asthma. Meta-analysis of studies demonstrates that monoallergen reduction does not impact asthma prevention. However, multifaceted allergen reduction studies have shown clinical benefit. We propose that allergic diseases, including asthma, represent a dysfunctional interaction with our environment and that the increasing prevalence of asthma and allergy herald increased population risk for the development of other inflammatory and autoimmune diseases. Better understanding of the complex factors for asthma and allergies may provide insight into many other chronic complex diseases.

Dust mite exposure modifies the effect of functional IL10 polymorphisms on allergy and asthma exacerbations

BACKGROUND

The allergenicity of dust mite exposure might be dependent on variants in the gene for IL-10 (IL10).

OBJECTIVES

To evaluate whether dust mite exposure modifies the effect of single nucleotide polymorphisms (SNPs) in IL10 on allergy and asthma exacerbations.

METHODS

We genotyped 6 SNPs in IL10 in 417 Costa Rican children and 503 white children in the Childhood Asthma Management Program (CAMP) with asthma and their parents. We used family-based and population-based approaches to test for interactions between IL10 SNPs and dust mite allergen on serum IgE to dust mite in Costa Rica and on asthma exacerbations in Costa Rica and CAMP.

RESULTS

Dust mite exposure significantly modified the relation between 3 SNPs in IL10 (rs1800896, rs3024492, and rs3024496) and IgE to dust mite in Costa Rica (P for interaction, .0004 for SNP rs1800896). For each of these SNPs, homozygosity for the minor allele was associated with increased levels of IgE to dust mite with increased dust mite exposure. Homozygosity for the minor allele of each of the 3 SNPs was associated with increased risk of occurrence (approximately 3-fold to 39-fold increase) and frequency of asthma exacerbations among children exposed to > or = 10 microg/g dust mite allergen in Costa Rica. Similar results were obtained for 2 of these SNPs (rs1800896 and rs3024496) among white children in CAMP.

CONCLUSION

Our findings suggest that dust mite allergen levels modify the effect of IL10 SNPs on allergy and asthma exacerbations and may partly explain conflicting findings in this field.

Gene-environment interaction in the onset of eczema in infancy: filaggrin loss-of-function mutations enhanced by neonatal cat exposure

BACKGROUND

Loss-of-function variants in the gene encoding filaggrin (FLG) are major determinants of eczema. We hypothesized that weakening of the physical barrier in FLG-deficient individuals may potentiate the effect of environmental exposures. Therefore, we investigated whether there is an interaction between FLG loss-of-function mutations with environmental exposures (pets and dust mites) in relation to the development of eczema.

METHODS AND FINDINGS

We used data obtained in early life in a high-risk birth cohort in Denmark and replicated the findings in an unselected birth cohort in the United Kingdom. Primary outcome was age of onset of eczema; environmental exposures included pet ownership and mite and pet allergen levels. In Copenhagen (n = 379), FLG mutation increased the risk of eczema during the first year of life (hazard ratio [HR] 2.26, 95% confidence interval [CI] 1.27-4.00, p = 0.005), with a further increase in risk related to cat exposure at birth amongst children with FLG mutation (HR 11.11, 95% CI 3.79-32.60, p < 0.0001); dog exposure was moderately protective (HR 0.49, 95% CI 0.24-1.01, p = 0.05), but not related to FLG genotype. In Manchester (n = 503) an independent and significant association of the development of eczema by age 12 mo with FLG genotype was confirmed (HR 1.95, 95% CI 1.13-3.36, p = 0.02). In addition, the risk increased because of the interaction of cat ownership at birth and FLG genotype (HR 3.82, 95% CI 1.35-10.81, p = 0.01), with no significant effect of the interaction with dog ownership (HR 0.59, 95% CI 0.16-2.20, p = 0.43). Mite-allergen had no effects in either cohort. The observed effects were independent of sensitisation.

CONCLUSIONS

We have demonstrated a significant interaction between FLG loss-of-function main mutations (501x and 2282del4) and cat ownership at birth on the development of early-life eczema in two independent birth cohorts. Our data suggest that cat but not dog ownership substantially increases the risk of eczema within the first year of life in children with FLG loss-of-function variants, but not amongst those without. FLG-deficient individuals may need to avoid cats but not dogs in early life.

In vivo-to-in silico iterations to investigate aeroallergen-host interactions

BACKGROUND

Allergic asthma is a complex process arising out of the interaction between the immune system and aeroallergens. Yet, the relationship between aeroallergen exposure, allergic sensitization and disease remains unclear. This knowledge is essential to gain further insight into the origin and evolution of allergic diseases. The objective of this research is to develop a computational view of the interaction between aeroallergens and the host by investigating the impact of dose and length of aeroallergen exposure on allergic sensitization and allergic disease outcomes, mainly airway inflammation and to a lesser extent lung dysfunction and airway remodeling.

METHODS AND PRINCIPAL FINDINGS

BALB/C mice were exposed intranasally to a range of concentrations of the most pervasive aeroallergen worldwide, house dust mite (HDM), for up to a quarter of their lifespan (20 weeks). Actual biological data delineating the kinetics, nature and extent of responses for local (airway inflammation) and systemic (HDM-specific immunoglobulins) events were obtained. Mathematical equations for each outcome were developed, evaluated, refined through several iterations involving in vivo experimentation, and validated. The models accurately predicted the original biological data and simulated an extensive array of previously unknown responses, eliciting two- and three-dimensional models. Our data demonstrate the non-linearity of the relationship between aeroallergen exposure and either allergic sensitization or airway inflammation, identify thresholds, behaviours and maximal responsiveness for each outcome, and examine inter-variable relationships.

CONCLUSIONS

This research provides a novel way to visualize allergic responses in vivo and establishes a basic experimental platform upon which additional variables and perturbations can be incorporated into the system.

Determination of mite allergens in house dust using the enzyme immunoassay

The aim of this study was to determine the level of two major mite allergens Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1) in 30 urban homes in Zagreb, Croatia, using the enzyme immunoassay with two monoclonal antibodies which has been established as the reference method for indoor allergen analysis. Dust samples were taken by vacuuming a carpeted area and collected on cellulose filters. The ranges of Der p 1 and Der f 1 were (0.1-12.5) microg g-1 (median 0.32 microg g-1) and (0.1-31.2) microg g-1 (median 0.35 microg g-1), respectively. Der p 1 and Der f 1 (>2 microg g-1) associated with increased risk of sensitization to mite allergens were found in approximately 16% homes for each allergen. The sum of allergen (Der p 1 + Der f 1) exceeded the lower threshold in 27% of homes. Analytical evaluation of the ELISA assay showed satisfactory results for precision (intra-assay CV <6.9%, inter-assay CV<13.3%), accuracy (91% to 93%), and sensitivity (2 ng mL-1). The ELISA assay for the measurement of dust mite allergens demonstrated very good analytical characteristics for routine laboratory use, and will provide the essential basis for our future studies of various indoor allergens.

Prevalence and associated factors of allergic rhinitis and atopic dermatitis in children

Allergic disorders are the chronic diseases of greatest pediatric morbidity, affecting over 25 % of the pediatric population. Indeed, this situation has been referred to as an "allergic epidemic". In comparison with asthma, atopic dermatitis and allergic rhinitis have been less extensively investigated, although this does not mean that they should be regarded as minor disorders but rather as alterations that affect the quality of life of the patients and their families, which generate considerable direct and indirect costs. Despite an important research effort, the reason for this allergic epidemic is not well known. These are multifactor disorders without a single causal agent, in which the most important component is the genetic predisposition of the patient (atopy), modulated by environmental factors, exposure to allergens, infections and irritants, among others. A confounding element is the fact that the concept of allergic diseases encompasses phenotypes of rhinitis, atopic dermatitis or asthma in which no IgE-mediated atopic mechanism is demonstrated, and which can manifest in a way similar to true allergic phenotypes. Differentiation between the two is difficult to establish on the basis of self-administered questionnaires alone, in the absence of a precise etiological diagnosis. The present article reviews the numerous factors suggested to be responsible for the increase in allergic diseases recorded in the last few decades, and for the differences in prevalence observed among centres. For most of these factors the results published in the literature are contradictory, in some cases due to a lack of control of the associated interacting or confounding factors. Consensus exists for only some of these causal factors, such as the established parallelism between the increase in allergic diseases and the reduction in infectious processes on one hand, and the increase in particles generated by diesel fuel combustion on the other. In addition, the implicated factors could act differently (and in some cases even antagonically) upon atopy and on the different disease phenotypes, thereby complicating the study of these interactions even further.

Early exposure to pets: good or bad?

Although pet exposure is known to trigger or worsen allergy symptoms and asthma in patients sensitized to pets, data from recent years has shown that pet exposure in early childhood may actually prevent the development of allergic sensitization and allergic diseases including allergic rhinitis, asthma, and atopic dermatitis. The concept of a protective pet effect remains controversial because these findings have not been duplicated in all studies. Moreover, some studies suggest that pet exposure promotes allergic disease. The protective pet effect may be influenced by multiple factors including type of pet; timing, duration, and intensity of exposure; and genetic factors. The mechanisms behind the protective pet effect remain under investigation but may include alterations in immune development, pet-specific tolerance, and exposure to innate immune stimuli.

The challenge of asthma in adolescence

The adolescents with asthma are a distinct group of patients with different problems and needs compared to children and adults. Specific issues of asthma in adolescence are the variability of the clinical spectrum, the presence of particular risk factors for the persistence of symptoms, underdiagnosis and undertreatment of the disease. Refusal of the sick role, denial of symptoms, carelessness about dangerous inhalation exposure, erratic self-medication, overexertion without taking precautions against exercise-induced asthma, and a poor relationship between patients, their families, and often doctors are the main obstacles to successful management of asthma in this critical age. There are also major problems of compliance for these patients. The goal of optimal quality of life will be achieved only if the physician thoroughly understands the adolescent's needs and provides optimal care.