Messages from the German Multicentre Allergy Study

Allergens in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex relationship to allergens. While AD itself is not an allergic reaction and does not necessarily involve allergen sensitization, AD patients show higher rates of sensitization to food and inhalant allergens compared to the general population. Recent evidence refining the "dual allergen exposure hypothesis" demonstrates that early oral exposure to allergens through an intact gastrointestinal barrier typically promotes tolerance, while exposure through compromised skin or respiratory barriers often leads to sensitization. Therefore, the impaired skin barrier function in AD patients increases the risk of transcutaneous sensitization and may interfere with oral tolerance development. Interestingly, AD patients' sensitivity to contact allergens (such as metals and fragrances) is not necessarily higher than that of the general population, which may be related to the inherent properties of these allergens. Personalized allergen testing can help guide appropriate allergen avoidance and reintroduction strategies in AD management. The insights into optimal allergen exposure conditions have also expanded the potential applications of allergen-specific immunotherapy in preventing AD onset in high-risk populations and halting the atopic march.

Whole-cell pertussis vaccine in early infancy for the prevention of allergy in children

BACKGROUND

Atopic diseases are the most common chronic conditions of childhood. The apparent rise in food anaphylaxis in young children over the past three decades is of particular concern, owing to the lack of proven prevention strategies other than the timely introduction of peanut and egg. Due to reported in vitro differences in the immune response of young infants primed with whole-cell pertussis (wP) versus acellular pertussis (aP) vaccine, we systematically appraised and synthesised evidence on the safety and the potential allergy preventive benefits of wP, to inform recommendation for future practice and research.

OBJECTIVES

To assess the efficacy and safety of wP vaccinations in comparison to aP vaccinations in early infancy for the prevention of atopic diseases in children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Embase, and grey literature. The date of the search was 7 September 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) that reported the occurrence of atopic diseases, and RCTs only to assess safety outcomes. To be included studies had to have at least six months follow-up, and involve children under 18 years old, who received a first dose of either wP (experimental intervention) or aP (comparator) before six months of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for eligibility, extracted the data, and assessed risk of bias using standard Cochrane methods. We assessed the certainty of the evidence using GRADE. Our primary outcomes were diagnosis of IgE-mediated food allergy and all-cause serious adverse events (SAEs). Secondary outcomes included: diagnosis of not vaccine-associated anaphylaxis or urticaria, diagnosis of asthma, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and diagnosis of encephalopathy. Due to paucity of RCTs reporting on the atopic outcomes of interest, we assessed a broader outcome domain (cumulative incidence of atopic disease) as specified in our protocol. We summarised effect estimates as risk ratios (RR) and 95% confidence intervals (CI). Where appropriate, we pooled safety data in meta-analyses using fixed-effect Mantel-Haenszel methods, without zero-cell corrections for dichotomous outcomes.

MAIN RESULTS

We identified four eligible studies reporting on atopic outcomes, representing 7333 children. Based on a single trial, there was uncertain evidence on whether wP vaccines affected the risk of overall atopic disease (RR 0.85, 95% CI 0.62 to 1.17) or asthma only (RR 1.04, 95% CI 0.59 to 1.82; 497 children) by 2.5 years old.Three NRSIs were judged to be at serious or critical risk of bias due to confounding, missing data, or both, and were ineligible for inclusion in a narrative synthesis.  We identified 21 eligible studies (137,281 children) that reported the safety outcomes of interest. We judged seven studies to be at high risk of bias and those remaining, at unclear risk.  The pooled RR was 0.94 for all-cause SAEs (95% CI 0.78 to 1.15; I² = 0%; 15 studies, 38,072 children). For every 1000 children primed with a first dose of wP, 11 had an SAE. The corresponding risk with aP was 12 children (95% CI 9 to 13). The 95% CI around the risk difference ranged from three fewer to two more events per 1000 children, and the certainty of the evidence was judged as moderate (downgraded one level for imprecision). No diagnoses of encephalopathy following vaccination were reported (95% CI around the risk difference - 5 to 12 per 100,000 children; seven primary series studies; 115,271 children). The certainty of the evidence was judged as low, since this is a serious condition, and we could not exclude a clinically meaningful difference.

AUTHORS' CONCLUSIONS

There is very low-certainty evidence that a first dose of wP given early in infancy, compared to a first dose of aP, affects the risk of atopic diseases in children. The incidence of all-cause SAEs in wP and aP vaccinees was low, and no cases of encephalopathy were reported. The certainty of the evidence was judged as moderate for all-cause SAEs, and low for encephalopathy. Future studies should use sensitive and specific endpoints of clinical relevance, and should be conducted in settings with high prevalence of IgE-mediated food allergy. Safety endpoints should prioritise common vaccine reactions, parental acceptability, SAEs and their potential relatedness to the dose administered.

IgE sensitization to food allergens and airborne allergens in relation to biomarkers of type 2 inflammation in asthma

BACKGROUND

We have recently reported that sensitization to food allergens and sensitization to airborne allergens had independent associations with increased fraction of exhaled nitric oxide (FeNO) and blood eosinophils in middle-aged adults and in young subjects with asthma.

OBJECTIVE

To investigate the relation between IgE sensitization and several type 2 inflammation biomarkers in adult asthmatics.

METHODS

FeNO, urinary eosinophil-derived neurotoxin (U-EDN), serum eosinophil cationic protein (S-ECP) and periostin were measured in 396 asthmatics, aged 17-76 years, from the Swedish GA2LEN study. Sensitization to airborne allergens was examined with skin prick tests (≥3 mm wheal) and sensitization to food allergens with measurement of specific IgE (≥0.35 kU/L).

RESULTS

Asthmatics sensitized to food allergens had higher FeNO, 22.3 ppb (18.6, 26.7) vs 16.1 ppb (14.2, 18.2) (P = .005), S-ECP, 17.7 mg/L (14.8, 21.1) vs 12.8 mg/L (10.9, 14.9) (P = .01), and periostin, 73.7 (67.5, 80.3) ng/mL vs 59.9 (55.8, 64.2) ng/mL (P = .003), than non-sensitized subjects. Periostin levels in this group were also significantly higher than in the group sensitized only to airborne allergens (P = .01). Sensitization to food allergens related independently to FeNO (P = .02), S-ECP (P = .006) and periostin (P = .004), whereas sensitization only to airborne allergens related only to FeNO (P = .02) after adjustments for age, sex, height, weight and smoking history. FeNO correlated weakly with S-ECP (r = .17, P < .001), periostin (r = .19, P < .001) and U-EDN (0.16, P < .001). S-ECP also correlated weakly with U-EDN (r = .12, P = .02). None of the correlations between the remaining pairs of markers of type 2 inflammation were significant.

CONCLUSIONS & CLINICAL RELEVANCE

Sensitization to food allergens related to several local and systemic type 2 inflammation markers, such as FeNO, S-ECP and periostin. Assessing the profile of allergic sensitization, including to food allergens, might improve the understanding and interpretation of inflammatory markers and potentially improve asthma management.

Treatment of Allergic Rhinitis as a Strategy for Preventing Asthma

PURPOSE OF REVIEW

To evaluate the impact of allergic rhinitis (AR) on the development of asthma and to update readers on recent literature suggesting that early treatment of allergic subjects with immunotherapy may prevent asthma onset.

RECENT FINDINGS

AR is frequently associated with asthma, leading to the concept that these two conditions are different aspects of the same disease. There is increasing evidence that AR precedes the onset of asthmatic symptoms and current treatment strategies are beneficial in symptom control with no impact prevention. There is limited knowledge about the risk factors responsible for the progression of AR to asthma, though recent data supports the notion that it is possible to prevent asthma onset by allergen immunotherapy. Despite significant advances in specific immunotherapy (SIT) therapy strengthening its efficacy in AR and possible prevention of progression to asthma, the adoption of this therapeutic strategy is still restricted in comparison to therapies directed towards treatment of AR symptoms. Unlike corticosteroids and other symptomatic therapies, the benefit of SIT treatment in allergic individuals has been shown to prevent the development of allergic conditions. Hence, large well-conducted randomized clinical trials with long-term efficacy of SIT are required to confirm or refute the concept that SIT may abrogate the progression of AR to asthma in patients.

Early-life home environment and risk of asthma among inner-city children

BACKGROUND

Environmental exposures in early life appear to play an important role in the pathogenesis of childhood asthma, but the potentially modifiable exposures that lead to asthma remain uncertain.

OBJECTIVE

We sought to identify early-life environmental risk factors for childhood asthma in a birth cohort of high-risk inner-city children.

METHODS

We examined the relationship of prenatal and early-life environmental factors to the occurrence of asthma at 7 years of age among 442 children.

RESULTS

Higher house dust concentrations of cockroach, mouse, and cat allergens in the first 3 years of life were associated with lower risk of asthma (for cockroach allergen: odds ratio per interquartile range increase in concentration, 0.55; 95% CI, 0.36-0.86; P < .01). House dust microbiome analysis using 16S ribosomal RNA sequencing identified 202 and 171 bacterial taxa that were significantly (false discovery rate < 0.05) more or less abundant, respectively, in the homes of children with asthma. A majority of these bacteria were significantly correlated with 1 of more allergen concentrations. Other factors associated significantly positively with asthma included umbilical cord plasma cotinine concentration (odds ratio per geometric SD increase in concentration, 1.76; 95% CI, 1.00-3.09; P = .048) and maternal stress and depression scores.

CONCLUSION

Among high-risk inner-city children, higher indoor levels of pet or pest allergens in infancy were associated with lower risk of asthma. The abundance of a number of bacterial taxa in house dust was associated with increased or decreased asthma risk. Prenatal tobacco smoke exposure and higher maternal stress and depression scores in early life were associated with increased asthma risk.

Is there a march from early food sensitization to later childhood allergic airway disease? Results from two prospective birth cohort studies

BACKGROUND

The march from early aeroallergen sensitization to subsequent respiratory allergy is well established, but it is unclear whether early life food sensitization precedes and further increases risk of allergic airway disease.

OBJECTIVE

To assess the association between food sensitization in the first 2 years of life and subsequent asthma and allergic rhinitis by age 10-12 years.

METHODS

We used data from two independent cohorts: the high-risk Melbourne Atopic Cohort Study (MACS) (n = 620) and the population-based LISAplus (n = 3094). Food sensitization was assessed at 6, 12, and 24 months in MACS and 24 months in LISAplus. Multiple logistic regressions were used to estimate associations between sensitization to food only, aeroallergen only, or both and allergic airway disease.

RESULTS

When compared to non-sensitized children, sensitization to food only at 12 months in MACS and 24 months in LISAplus was associated with increased risk of current asthma (aOR = 2.2; 95% CI 1.1, 4.6 in MACS and aOR = 4.9; 2.4, 10.1 in LISAplus). Similar results were seen for allergic rhinitis. Additionally, cosensitization to food and aeroallergen in both cohorts at any tested point was a stronger predictor of asthma (at 24 months, aOR = 8.3; 3.7, 18.8 in MACS and aOR = 14.4; 5.0, 41.6 in LISAplus) and allergic rhinitis (at 24 months, aOR = 3.9; 1.9, 8.1 in MACS and aOR = 7.6; 3.0, 19.6 in LISAplus).

CONCLUSIONS

In both cohorts, food sensitization (with or without aeroallergen sensitization) in the first two years of life increased the risk of subsequent asthma and allergic rhinitis. These findings support the role of early life food sensitization in the atopic march and suggest trials to prevent early onset have the potential to reduce the development of allergic airways disease.

Inflammation and infections in asthma

INTRODUCTION

Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition.

OBJECTIVE

To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations.

METHODS

We included 131 articles for the final review according to their relevance with the subject.

RESULTS

There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other.

CONCLUSION

The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.

Age at onset of asthma and allergen sensitization early in life

BACKGROUND

Epidemiological evidence indicates that the age at onset of asthma and allergen sensitization in early life is decreasing in people from Western countries. To explore latent trends, we conducted a retrospective examination of the age at onset of asthma and specific IgE antibodies against inhalant allergens in Japanese asthmatic children.

METHODS

We conducted a case series study of 103 consecutive children with atopic type of asthma (aged 2 years to 16 years, mean age 9.4 ± 3.4 years). Diagnoses of asthma and allergic rhinitis were defined according to Japanese guidelines. The onset of asthma and allergic rhinitis was also defined as any report of asthma and allergic rhinitis confirmed by a physician. Allergen sensitization was evaluated as specific serum IgE levels for 9 common inhalant allergens in peripheral blood. Atopic type of asthma was defined as a being positive for at least one aeroallergen.

RESULTS

Mean age at asthma onset was 2.3 ± 1.9 years, which is slightly lower than that of previous reports, including those published in Japan. A high prevalence rate of up to 80% was found for perennial antigens including Dermatophagoides spp. and house dust, as reported previously. Notably, some of the children aged at 1 year tested positive for these allergens.

CONCLUSIONS

The age at onset of asthma seems to be decreasing in comparison with previous reports. Furthermore, the age at onset of allergen sensitization against inhalant allergens appears to follow this trend.

Preventing progression of allergic rhinitis to asthma

The prevalence of allergic rhinitis (AR) is on the increase and this condition is frequently associated with asthma, thus leading to the concept that these two conditions are different aspects of the same disease. There is now accumulating evidence that AR often precedes the onset of asthmatic symptoms. This notion has important implications, not only for the diagnosis and management of these common allergic conditions but also for the potential progression of disease. Very little is known about the risk factors responsible for the progression of AR to asthma; current treatment options can control symptoms but do not prevent or cure the disease. However, there are recent data supporting the notion that it is possible to prevent new asthma cases by modifying the immune response and clinical outcome with allergen immunotherapy. This review article evaluates the impact of AR on the development of asthma, examines putative predictors for the progression of AR to asthma, and reviews recent, promising literature suggesting that early treatment of allergic individuals with immunotherapy may aid in asthma prevention.

Association of breastfeeding with asthma in young Aboriginal children in Canada

BACKGROUND

Few studies have investigated the factors associated with asthma in young Aboriginal children.

OBJECTIVE

To characterize the association of demographic, environmental and early life factors with asthma in young Aboriginal children in Canada.

METHODS

The 2006 Aboriginal Children's Survey was conducted among off-reserve Aboriginal children zero to six years of age to obtain information on Aboriginal children's development and well-being. The prevalence of asthma in Aboriginal children was obtained from the parental report of asthma as diagnosed by a health care professional.

RESULTS

The prevalence of reported asthma among off-reserve Aboriginal children zero to six years of age (n=14,170) was 9.4%. Asthma prevalence in both exclusively breastfed children (6.8%) and ever but not exclusively breastfed children (9.0%) was significantly lower than that in nonbreastfed children (11.0%). In the multiple logistic regression analysis, exclusive breastfeeding was protective of asthma compared with nonbreastfeeding (OR 0.59 [95% CI 0.44 to 0.78]). Older age groups, male sex, having two or more older siblings, low birth weight, day care attendance and ear infection were significant risk factors for asthma.

CONCLUSIONS

The prevalence of asthma among young Aboriginal children zero to six years of age living off reserve was slightly lower than that reported for all other Canadian children. Breastfeeding, especially exclusively breastfeeding, was protective of asthma in Aboriginal children, which is consistent with what has been observed in non-Aboriginal children in Canada. Public health interventions intended for reducing asthma incidence in young Aboriginal children should include breastfeeding promotion programs.

Predicting persistence of asthma in preschool wheezers: crystal balls or muddy waters?

Since preschool wheezing is the common expression of several heterogeneous disorders, identification of children at risk for persistent asthma is particularly challenging. To date, efforts to predict the outcome of preschool wheeze have mainly relied on predictive rules consisting of simple clinical and laboratory parameters. Among these tools, the asthma predictive index (API) has been introduced in international guidelines and position papers and is recommended for use in clinical practice. This article reviews the currently available asthma predictive models focusing on their validity and performance characteristics. Although these tools are generally simple and easy to apply, they suffer important intrinsic and practical limitations and they have been insufficiently validated to allow for widespread use in clinical settings. We also present evidence that their ability to predict the long-term outcome of preschool wheeze is limited in general populations, and even poorer in high-risk children in which prediction of asthma persistence might have important clinical and prognostic implications. Due to the complex and multifactorial nature of asthma, prediction of asthma persistence based on simple clinical models is practically impossible.

Exposure assessment in cohort studies of childhood asthma

BACKGROUND

The environment is suspected to play an important role in the development of childhood asthma. Cohort studies are a powerful observational design for studying exposure-response relationships, but their power depends in part upon the accuracy of the exposure assessment.

OBJECTIVE

The purpose of this paper is to summarize and discuss issues that make accurate exposure assessment a challenge and to suggest strategies for improving exposure assessment in longitudinal cohort studies of childhood asthma and allergies.

DATA SYNTHESIS

Exposures of interest need to be prioritized, because a single study cannot measure all potentially relevant exposures. Hypotheses need to be based on proposed mechanisms, critical time windows for effects, prior knowledge of physical, physiologic, and immunologic development, as well as genetic pathways potentially influenced by the exposures. Modifiable exposures are most important from the public health perspective. Given the interest in evaluating gene-environment interactions, large cohort sizes are required, and planning for data pooling across independent studies is critical. Collection of additional samples, possibly through subject participation, will permit secondary analyses. Models combining air quality, environmental, and dose data provide exposure estimates across large cohorts but can still be improved.

CONCLUSIONS

Exposure is best characterized through a combination of information sources. Improving exposure assessment is critical for reducing measurement error and increasing power, which increase confidence in characterization of children at risk, leading to improved health outcomes.

Inflammatory markers in childhood asthma

The major characteristic of asthma is persistent airway inflammation that fails to resolve spontaneously. Dysregulation of pro- and anti-inflammatory mechanisms is responsible for the development of chronic inflammation. The inflammatory reaction is mediated by numerous cells and their mediators. Detection and quantification of airway inflammation in children are subject to many requirements, e.g., use of biologic samples obtained in a non-invasive way; use of standardized analytical methods to determine biomarkers that can identify inflammation processes (inflammation itself, oxidative stress, apoptosis and remodelling); determining the role of systemic inflammation; assessment of correlation of various biomarkers of inflammation with clinical parameters and their diagnostic efficacy; providing a tool(s) to monitor diseases, and to evaluate adequacy of therapy; and predicting the clinical course of inflammation and prognosis of asthma. Using standardized analyses, it is now possible to determine direct markers of local inflammation, i.e., fractional nitric oxide (marker of oxidative stress) in exhaled breath, pH (marker of acid stress) in breath condensate, and indirect markers in blood/serum, i.e., eosinophil granulocytes (indicating migration), eosinophil cationic protein (marker of activated eosinophil granulocytes) and C-reactive protein (marker of systemic inflammation). However, none of these biomarkers are specific for asthma. Further standardization of the known pulmonary biomarkers of local inflammation and identification of new ones will allow for longitudinal follow-up of inflammation in children with asthma.

Eczema in early life: genetics, the skin barrier, and lessons learned from birth cohort studies

Eczema is a chronic inflammatory disorder of the skin that affects up to 30% of children. It often afflicts infants in the first few months of life and can be the first indicator of the atopic march. Recent results from birth cohort studies have uncovered novel information regarding genetic and environmental factors that promote the development of eczema. Birth cohort studies provide an optimal study design to elucidate these associations and prospectively track longitudinal data including exposure assessment and health outcomes from birth into early life and childhood. This is especially relevant for eczema given the age specific emergence of this disease. In this review, we will provide a general overview of pediatric eczema and discuss the important findings in the literature with respect to genetics and environmental exposures, highlighting those derived from birth cohort studies. Additionally, we will review how these relate to the atopic march, the hygiene hypothesis and the integrity of the skin barrier.

The natural history of allergic rhinitis in childhood

The distinction between 'seasonal' and 'perennial' allergic rhinitis (AR) is not always adequate. The 'Allergic Rhinitis and its Impact on Asthma' (ARIA) work group suggested a new classification for AR based on severity and duration of symptoms. Our primary aim was to describe the natural history and burden of AR according to the new ARIA criteria in a population-based birth cohort study of children up to 13 yr. We defined symptoms as 'severe' (impairment of daily activities) or 'mild' (no impairment) and 'persistent' (duration > 1 month) or 'intermittent' (<or=1 month) using annual questionnaires. Serum immunoglobulin E to five common aero-allergens was determined at six time points. We analyzed complete follow-up data from 467 children (54% boys). The 12-month prevalence of AR quadrupled from 6% (at age 3 yr) to 24% (at age 13 yr) in children with non-allergic parents and more than tripled from 13% (3 yr) to 44% (13 yr) in children with at least one allergic parent. Half or more of the children with AR had 'severe persistent' symptoms. At age 13, these children were significantly more often sensitized than those with 'mild persistent' disease: 91% vs. 70% (p = 0.015). Sensitization to aero-allergens (adjusted OR 18.9; 95%CI 9.3-38.4) and having 2 parents with allergy (3.1; 1.1-9.3) were significantly associated with AR. According to the ARIA criteria, the impact of AR seems to be substantial; the vast majority of affected children suffered persistently for periods of 2 months or more annually, and most of the children with persistent AR were impaired in their daily activities.

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.

Food allergy is associated with an increased risk of asthma

BACKGROUND

The atopic march is well documented, but the interrelationship of food allergy (FA) and asthma is not well understood.

OBJECTIVE

The aim of this study was to examine the strength of the association and temporal relationships between FA and asthma.

METHODS

This analysis included 271 children >or=6 years (older group) and 296 children <6 years (younger group) from a family-based FA cohort in Chicago, IL. Asthma was determined by parental report of physician diagnosis. FA status was determined based on the type and timing of clinical symptoms after ingestion of a specific food, and results of prick skin test (Multi-Test II) and allergen-specific IgE (Phadia ImmunoCAP). Analyses were carried out using logistic regression accounting for important covariates and auto-correlations among siblings. Kaplan-Meier curves were used to compare the time to onset of asthma with the FA status.

RESULTS

Symptomatic FA was associated with asthma in both older [odds ratio (OR)=4.9, 95% confidence interval (CI): 2.5-9.5] and younger children (OR=5.3, 95% CI: 1.7-16.2). The association was stronger among children with multiple or severe food allergies, especially in older children. Children with FA developed asthma earlier and at higher prevalence than children without FA (Cox proportional hazard ratio=3.7, 95% CI: 2.2-6.3 for children >or=6 years, and hazard ratio=3.3, 95% CI: 1.1-10 for children <6 years of age). No associations were seen between asymptomatic food sensitization and asthma.

CONCLUSIONS

Independent of markers of atopy such as aeroallergen sensitization and family history of asthma, there was a significant association between FA and asthma. This association was even stronger in subjects with multiple food allergies or severe FA.

Early exposure and sensitization to cat and dog: different effects on asthma risk after wheezing in infancy

Birth cohort studies have suggested that early exposure to furred pets protects from later asthma and allergy. The aim of the present study was to evaluate the association between exposure or sensitization to cat or dog in infancy, and later asthma and allergy assessed at the median ages of 4.0, 7.2 and 12.3 yr, in children who have wheezed at <24 months of age. Exposure to cat and dog in infancy was assessed by interviewing the parents. The child was considered as sensitized, if the allergen-specific IgE to cat or to dog was >or=0.35 kU/l, or if there was a positive skin test response. When the 20 children with persistent childhood asthma (doctor-diagnosed asthma at all three control visits) were compared with the other 61 children, an early exposure to dog (OR = 0.14, p = 0.034)) decreased the asthma risk and an early sensitization to cat (OR = 5.92, p = 0.008) and dog (OR = 9.33, p = 0.001) increased the asthma risk. There were less cat and dog keeping in atopic families and the effect of sensitization was, but the effect of exposure was not, robust to adjustments in multivariate analyses. The present study demonstrates, in a long-term follow-up after early wheezing, that early sensitization to cat and dog increases the risk of later asthma but early exposure to cat or dog has no such effect. Dog keeping was less frequent in atopic families, which may explain that the protective effect of early exposure to dog was lost in multivariate analyses.

iPAC: an initiative to fight the burden of allergies in children

Allergies and asthma are common diseases in most parts of the world. Together, they represent a major burden on global health, as well as on health costs. However, efficient preventive measures are still lacking, and treatments are mostly symptomatic. The pathogenesis of the "allergic marathon'', the progression of the disease throughout childhood into adulthood is only partly understood. In addition, treatment protocols addressing the pathogenesis of the disease are not available to all patients, either due to economical reasons, or to insufficient efficacy or safety of the procedures. This editorial introduces a supplement dedicated to identify directions and means to fight the burden of allergies in childhood. This initiative is coordinated by iPAC (international Pediatric Allergy and Asthma Consortium).

Potential health effects from non-specific stimulation of the immune function in early age: the example of BCG vaccination

There is increasing, but still inconsistent evidence that vaccinations and childhood infections may play a role in the normal maturation of the immune system, and in the development and balance of immune regulatory pathways, both of which might impact health later in life. This review covers the epidemiological evidence regarding the role of Bacillus Calmette-Guérin (BCG) vaccination on the following inflammatory or autoimmune diseases: asthma and allergic diseases, Crohn's disease (CD), insulin-dependent diabetes mellitus (IDDM), and specific cancers. The literature is more comprehensive for asthma and allergic diseases, with 16 studies reporting the absence of an association while seven rather suggest a protective effect of BCG. We found insufficient evidence on CD to conclude at this point. Overall, the evidence for IDDM based on four studies leans towards no association, although some effects were observed in population subsets. Five epidemiological investigations provide evidence on a possible link with cancer incidence or mortality at various sites, with indications of both increased and decreased risks. Given the potential public health implications, it is imperative to acquire a better understanding of how BCG vaccination could influence the development of such chronic health conditions in the population.

Prevalence of asthma and risk factors for asthma-like symptoms in Aboriginal and non-Aboriginal children in the northern territories of Canada

BACKGROUND

Few studies have investigated the prevalence and risk factors of asthma in Canadian Aboriginal children.

OBJECTIVE

To determine the prevalence of asthma and asthma-like symptoms, as well as the risk factors for asthma-like symptoms, in Aboriginal and non-Aboriginal children living in the northern territories of Canada.

METHODS

Data on 2404 children, aged between 0 and 11 years, who participated in the North component of the National Longitudinal Survey of Children and Youth were used in the present study. A child was considered to have an asthma-like symptom if there was a report of ever having had asthma, asthma attacks or wheeze in the past 12 months.

RESULTS

After excluding 59 children with missing information about race, 1399 children (59.7%) were of Aboriginal ancestry. The prevalence of asthma was significantly lower (P<0.05) in Aboriginal children (5.7%) than non-Aboriginal children (10.0%), while the prevalence of wheeze was similar between Aboriginal (15.0%) and non-Aboriginal (14.5%) children. In Aboriginal children, infants and toddlers had a significantly greater prevalence of asthma-like symptoms (30.0%) than preschool-aged children (21.5%) and school-aged children (11.5%). Childhood allergy and a mother's daily smoking habit were significant risk factors for asthma-like symptoms in both Aboriginal and non-Aboriginal children. In addition, infants and toddlers were at increased risk of asthma-like symptoms in Aboriginal children. In analyses restricted to specific outcomes, a mother's daily smoking habit was a significant risk factor for current wheeze in Aboriginal children and for ever having had asthma in non-Aboriginal children.

CONCLUSIONS

Asthma prevalence appears to be lower in Aboriginal children than in non-Aboriginal children. The association between daily maternal smoking and asthma-like symptoms, which has been mainly reported for children living in urban areas, was observed in Aboriginal and non-Aboriginal children living in northern and remote communities in Canada.

Use of Phadiatop Infant in diagnosis of specific sensitization in young children with wheeze or eczema

Wheezing and eczema are common symptoms in young children and it is important to disclose sensitization for correct management. The objective of this study was to assess the diagnostic values of Phadiatop Infant, an in vitro test for graded determination of immunoglobulin E (IgE) antibodies to food and inhalant allergens. One-hundred and forty-nine children (median age 1.4 yr) with symptoms of wheezing (51%) eczema (28%) or a combination of both (21%) were classified as atopic or non-atopic based on case history, atopic history, physical examination and determination of IgE antibodies. The clinical performance of Phadiatop Infant was evaluated for 145 children against this classification in a blinded manner to the allergist. Fifty-one children were classified as atopic of which Phadiatop Infant identified 49. Ninety-four were non-atopic of which the test identified 90. This resulted in a sensitivity of 96%, a specificity of 96%, a positive and a negative predictive value of 94% and 98%, respectively. Logistic regression showed that probability had to be assessed as atopic increased with increasing Phadiatop Infant values. These results suggest that Phadiatop Infant can be recommended as an adjunct to the clinical information in the differential diagnosis on IgE-mediated allergy in young children. The test thus provides an opportunity for early correct diagnosis and identification of subjects at risk for whom intervention may be necessary.

Natural history of asthma: persistence versus progression-does the beginning predict the end?

Environmental exposures during the early years and airway obstruction that develops during this time, in conjunction with genetic susceptibility, are important factors in the development of persistent asthma in childhood. Established risk factors for childhood asthma include frequent wheezing during the first 3 years, a parental history of asthma, a history of eczema, allergic rhinitis, wheezing apart from colds, and peripheral blood eosinophilia, as well as allergic sensitization to aeroallergens and certain foods. Risk factors for the development of asthma in adulthood remain ill defined. Moreover, reasons for variability in the clinical course of asthma--persistence in some individuals and progression in others--remain an enigma. The distinction between disease persistence and disease progression suggests that these are different entities or phenotypes. There is currently no consensus on whether disease progression requires either airway inflammation or airway remodeling or the combination of the two. For patients with irreversible airway obstruction, inflammation might, in part, be necessary but perhaps not entirely sufficient to induce the irreversible component, some of which could be attributed to alterations in the structure of the bronchial wall. Intervening with intermittent or daily inhaled corticosteroids in high-risk infants and children does not prevent disease progression or impaired lung growth. These findings, however, might not apply to adults, and further study in adults is needed to determine the effect of inhaled corticosteroid therapy on disease progression.

The influence of age and gender on sensitization to aero-allergens

Boys run a higher risk for atopy than girls but this gender difference is less pronounced in adulthood. The underlying mechanisms and the exact timing of this decrease in male/female ratio remain unclear. The aim of this study was to evaluate the effect of age and gender on sensitization in schoolchildren. A cross-sectional study was performed in an unbiased community population of 2021 Belgian schoolchildren, aged 3.4-14.8 yr. The overall sensitization and the sensitization for mites, mixed grass pollens and tree pollens increased significantly with increasing age. Male sex was strongly associated with sensitization (OR(adj) 2.0, 98% CI 1.6-2.4). Male predominance was more obvious in children under the age of 8 yr. After the age of 8 male predominance persisted, but a significant increase in sensitized females occurred. Our data demonstrate a significant increase in prevalence of sensitization with age and a significant decrease in male/female ratio of sensitization after the age of 8 yr, although a male predominance persists. These data are the first published data ever that document this change in male/female ratio in sensitization at this age.

The prevalence, cost and basis of food allergy across Europe

The development of effective management strategies to optimize the quality of life for allergic patients is currently hampered by a lack of good quality information. Estimates of how many individuals suffer from food allergy and the major foods involved vary widely and inadequacies of in vitro diagnostics make food challenges the only reliable means of diagnosis in many instances. The EuroPrevall project brings together a multidisciplinary partnership to address these issues. Cohorts spanning the main climatic regions of Europe are being developed in infants through a birth cohort, community surveys in school-age children and adults and an outpatient clinic study. Confirmatory double-blind placebo-controlled food challenge diagnosis is being undertaken using foods as they are eaten with titrated doses to allow no-effect and lowest-observable effect levels for allergenic foods to be determined. The cohorts will also facilitate validation of novel in vitro diagnostics through the development of the EuroPrevall Serum Bank. Complementary studies in Ghana, western Siberia, India and China will allow us to gain insights into how different dietary patterns and exposure to microorganisms affect food allergies. New instruments to assess the socioeconomic impact of food allergy are being developed in the project and their application in the clinical cohorts will allow, for the first time, an assessment to be made of the burden this disease places on allergy sufferers and their communities.

Local genetic and environmental factors in asthma disease pathogenesis: chronicity and persistence mechanisms

While asthma is an inflammatory disorder of the airways usually associated with atopy, an important additional component is involvement of the epithelium and underlying mesenchyme acting as a trophic unit (EMTU). In addition to allergens, a wide range of environmental factors interact with the EMTU, such as virus infections, environmental tobacco smoke and pollutants, to initiate tissue damage and aberrant repair responses that are translated into remodelling of the airways. While candidate gene association studies have revealed polymorphic variants that influence asthmatic inflammation, positional cloning of previously unknown genes is identifying a high proportion of novel genes in the EMTU. Dipeptidyl peptidase (DPP) 10 and disintegrin and metalloproteinase (ADAM)33 are newly identified genes strongly associated with asthma that are preferentially expressed in the airway epithelium and underlying mesenchyme, respectively. Also of increasing importance is the recognition that genes associated with asthma and atopy have important interactions with the environment through epigenetic mechanisms that influence their expression. This type of research will not only identify biomarkers of different types of asthma across the full range of phenotypic expression, but will also identify novel therapeutic targets that could influence the natural history of the heterogenes lung disease.

Correlation between asthma severity and serum IgE in asthmatic children sensitized to Dermatophagoides pteronyssinus

BACKGROUND

We undertook this study to test the possible correlation between serum concentration of total and specific IgE antibodies and asthma severity in asthmatic children sensitized to the house dust mite Dermatophagoides pteronyssinus.

METHODS

The study included 157 asthmatic children aged 5-15 years (8 +/- 3 years). Clinical diagnosis was based on personal and family history, physical examination, pulmonary function testing and skin tests. Asthma severity was determined according to GINA guidelines. In vitro tests included serum concentration of total and specific IgE.

RESULTS

All asthmatic children had elevated serum concentration of total IgE. The children with elevated serum concentration of total IgE also showed an increased serum concentration of specific IgE. Asthma of higher higher severity was present in patients with total IgE concentration >288.0 kIU/L (AUC = 0.736) and specific IgE to Dermatophagoides pteronyssinus >44.1 kIUA/L (AUC = 0.843). Intermittent asthma was present in 76.9% of children with specific IgE concentration <44.1 kIUA/L. The positive predictive value suggested with 79.2% probability that a child with a concentration of specific IgE to Dermatophagoides pteronyssinus >44.1 kIUA/L would have a more severe form of asthma.

CONCLUSIONS

Asthmatic children with higher asthma severity have a higher serum concentration of both total IgE (>288.0 kIU/L) and specific IgE to Dermatophagoides pteronyssinus (>44.1 kIUA/L), respectively.

Cut-off values for total serum immunoglobulin E between non-atopic and atopic children in north-west Croatia

BACKGROUND

The aim of this study was to determine cut-off values for total serum immunoglobulin E (IgE) between non-atopic and atopic children with respiratory symptoms. Children of 0-16 years of age were evaluated for respiratory symptoms of >4-week duration.

METHODS

Children were divided into two groups: non-atopic children (n=3355) who were non-IgE-sensitized with undetectable allergen-specific IgE (<0.35 kIU(A)/L), and atopic children (n=4620) who were sensitized to > or =1 allergens (specific IgE > or =0.35 kIU(A)/L). Upper and lower centiles were determined and cut-off values calculated using receiver operating characteristic (ROC) analysis.

RESULTS

Serum total IgE increased with age in both groups, although at a variable level and rate, and reached a plateau at 9 and 10 years in non-atopic and atopic children, respectively. Atopic children had on average 14-fold higher serum total IgE compared to non-atopic children. In both groups, the median was lower than the corresponding mean and the distribution skewness was always positive (group I, 0.87; group II, 0.91). In almost all age groups, the 95th percentile for non-atopic children corresponded to the calculated cut-off values, whereas the 10th percentile for atopic children corresponded to the respective cut-off values only until the age of 8 years, after which greater differences between the cut-off values and the 10th percentile were recorded. Cut-off values for total serum IgE in children up to 16 years were determined with diagnostic sensitivity, specificity and area under the ROC curve of 96%, 91% and 0.950, respectively.

CONCLUSIONS

The 95th percentile for total IgE in non-atopic children and the 10th percentile in atopic children could be taken as cut-off values in children up to 8 years of age, after which significant percentile discrepancies between non-atopic and atopic children were recorded. Since atopic subjects show a more irregular centile distribution, cut-off values are best determined by ROC analysis.

Atopic disease in childhood

A child with atopy produces IgE antibodies after exposure to common environmental allergens. The atopic diseases (eczema, asthma and rhinoconjunctivitis) are clinical syndromes each defined by a group of symptoms and signs. Not all children with atopy will have atopic disease or develop symptoms after exposure to an allergen. Both genetic and environmental factors determine the development of atopic disease. The presence of specific IgE antibodies to environmental allergens is determined with skin prick or radioallergosorbent testing in children with atopy. Test results should be interpreted in the context of the clinical history and further investigations (eg, allergen avoidance or challenge). Management of atopic disease is frequently symptomatic, but it is important to avoid identified allergen triggers. Immunotherapy may be considered in selected school-age children with severe rhinoconjunctivitis. Preventing atopic disease in high-risk infants and hindering progression of disease in children with established disease are the areas of active research.

Differential diagnosis of IgE-mediated allergy in young children with wheezing or eczema symptoms using a single blood test

BACKGROUND

Allergy-like symptoms are common in young children, but the case history and physical examination cannot identify the underlying origins of overlapping symptom profiles.

OBJECTIVE

To evaluate a blood test, Phadiatop Infant (Pharmacia Diagnostics AB, Uppsala, Sweden), for differentiating the capability of IgE-mediated disease in young children with recurrent wheezing, eczema, or both.

METHODS

One hundred forty-seven children (mean age, 2.0 years) were consecutively referred to 2 allergy centers by their primary care physician for recurrent wheezing, eczema, or both. The allergist's clinical evaluation included medical history, physical examination, skin prick testing with inhalant and food allergens, and specific IgE determinations in blood. The accuracy of Phadiatop Infant was evaluated in a masked manner against the allergist's final diagnosis.

RESULTS

Sixty-nine children had wheezing, 69 had eczema, and 9 had both symptoms. Sixty-one children were clinically diagnosed as having IgE-mediated allergy, 78 as having non-IgE-associated disease, and 8 as having an inconclusive diagnosis. Fifty-six of the 61 children with IgE-mediated allergy had positive Phadiatop Infant test results, and 64 of 78 without the condition had negative results. Sensitivity was 92% and specificity was 82%, with positive and negative predictive values of 80% and 93%, respectively. Thirteen children with a positive Phadiatop Infant test result and a negative final diagnosis were retested after 2 years; 12 of them were diagnosed as having IgE-mediated allergy using a masked evaluation.

CONCLUSIONS

The Phadiatop Infant blood test discriminates between IgE- and non-IgE-mediated symptoms in children younger than 4 years.

Dietary treatment of childhood atopic eczema/dermatitis syndrome (AEDS)

OBJECTIVE

This review summarizes the research and clinical evidence in favour of dietary intervention aimed at eliminating allergenic foods in the management of atopic eczema/dermatitis syndrome (AEDS).

DATA SOURCES

The data source was PubMed, using a search algorithm selecting for clinical studies of AEDS, diet therapy and food allergy in all children to October 2003. Also included is a commentary based on the authors' clinical experience in the allergy unit of a university hospital in Italy.

RESULTS

Fourteen prospective studies matched the entry criteria. Diverse trial designs, diagnostic criteria, types of dietary intervention and length of observation periods precluded meta-analytic methods. Allergenic food exclusion claimed efficacy in 13 of the 14 studies and was most useful in infants, in patients with elevated immunoglobulin E levels and/or multiple food sensitization and in patients with a diagnosis of food allergy.

CONCLUSION

Dietary intervention in the form of an elimination diet is efficacious in children with AEDS when a specific diagnosis of food allergy has been made. Diagnostic evaluation of food allergy should be performed in all children with eczema, particularly in younger children and those with severe forms of the disease.