Pro: The evidence for a causal role of dust mites in asthma

Use of Electronic Nicotine Delivery Systems and Age of Asthma Onset Among US Adults and Youths

Importance

The association of use of electronic nicotine delivery systems (ENDS) with the age of asthma onset is unknown.

Objective

To explore the association of past 30-day ENDS use with the age of asthma onset in adults and youths who did not have asthma or chronic obstructive pulmonary disease and never used cigarettes.

Design, Setting, and Participants

This cohort study was a secondary analysis of waves 1 to 6 of the US nationally representative Population of Tobacco and Health Study (2013-2021). Eligible participants included adults (≥18 years) and youths (12-17 years) who did not have asthma or chronic obstructive pulmonary disease at the first wave of participation. Data analysis was conducted from September 2022 to April 2024.

Exposure

Past 30-day ENDS use at the first wave of participation in the study preceding the onset of asthma.

Main outcome and measures

Lower and upper age limits were estimated using the age reported at the first wave of participation and the number of weeks between follow-up waves until asthma was first reported or censored. The association of past 30-day ENDS use with the age of asthma onset was estimated using weighted interval-censoring Cox regression. The cumulative hazard function for the age of asthma onset was estimated using interval-censoring survival analysis.

Results

A total of 24 789 participants were included, with 7766 adults (4461 female [weighted percentage, 59.11%] and 3305 male [weighted percentage, 40.89%]), representing 80.0 million adults, and 17 023 youths (8514 female [weighted percentage, 50.60%] and 8496 male [weighted percentage 49.32%]), representing 33.9 million youths. By age 27 years, 6.2 per 1000 adults reported asthma incidence (hazard ratio [HR], 0.62%; 95% CI, 0.46%-0.75%). While controlling for covariates, there was a 252% increased risk of the onset of asthma at earlier ages for adults who used ENDS in the past 30 days vs adults who did not (adjusted HR, 3.52; 95% CI, 1.24-10.02). For youths, there was no association of ENDS use in the past 30 days with age of asthma onset (adjusted HR, 1.79; 95% CI, 0.67-4.77), which could be due to a lack of statistical power.

Conclusion and relevance

In this cohort study, past 30-day ENDS use among adults was associated with earlier ages of asthma onset. These findings suggest that prevention and cessation programs directed to adults who use ENDS are needed to educate the public, protect public health, prevent adverse health outcomes, and motivate users to stop. Furthermore, modifying symptom-screening asthma guidelines, resulting in earlier asthma detection and treatment, may reduce morbidity and mortality due to asthma.

Dual inhibition of airway inflammation and fibrosis by common β cytokine receptor blockade

BACKGROUND

Patients with severe asthma can present with eosinophilic type 2 (T2), neutrophilic, or mixed inflammation that drives airway remodeling and exacerbations and represents a major treatment challenge. The common β (βc) receptor signals for 3 cytokines, GM-CSF, IL-5, and IL-3, which collectively mediate T2 and neutrophilic inflammation.

OBJECTIVE

To determine the pathogenesis of βc receptor-mediated inflammation and remodeling in severe asthma and to investigate βc antagonism as a therapeutic strategy for mixed granulocytic airway disease.

METHODS

βc gene expression was analyzed in bronchial biopsy specimens from patients with mild-to-moderate and severe asthma. House dust mite extract and Aspergillus fumigatus extract (ASP) models were used to establish asthma-like pathology and airway remodeling in human βc transgenic mice. Lung tissue gene expression was analyzed by RNA sequencing. The mAb CSL311 targeting the shared cytokine binding site of βc was used to block βc signaling.

RESULTS

βc gene expression was increased in patients with severe asthma. CSL311 potently reduced lung neutrophils, eosinophils, and interstitial macrophages and improved airway pathology and lung function in the acute steroid-resistant house dust mite extract model. Chronic intranasal ASP exposure induced airway inflammation and fibrosis and impaired lung function that was inhibited by CSL311. CSL311 normalized the ASP-induced fibrosis-associated extracellular matrix gene expression network and strongly reduced signatures of cellular inflammation in the lung.

CONCLUSIONS

βc cytokines drive steroid-resistant mixed myeloid cell airway inflammation and fibrosis. The anti-βc antibody CSL311 effectively inhibits mixed T2/neutrophilic inflammation and severe asthma-like pathology and reverses fibrosis gene signatures induced by exposure to commonly encountered environmental allergens.

TET1 regulates responses to house dust mite by altering chromatin accessibility, DNA methylation, and gene expression in airway epithelial cells

Background

Previous studies have identified TET1 as a potential key regulator of genes linked to asthma. TET1 has been shown to transcriptionally respond to house dust mite extract, an allergen known to directly cause allergic asthma development, and regulate the expression of genes involved in asthma. How TET1 regulates expression of these genes, however, is unknown. TET1 is a DNA demethylase; therefore, most prior research on TET1-based gene regulation has focused on how TET1 affects methylation. However, TET1 can also interact directly with transcription factors and histone modifiers to regulate gene expression. Understanding how TET1 regulates expression to contribute to allergic responses and asthma development thus requires a comprehensive approach. To this end, we measured mRNA expression, DNA methylation, chromatin accessibility and histone modifications in control and TET1 knockdown human bronchial epithelial cells treated or untreated with house dust mite extract.

Results

Throughout our analyses, we detected strong similarities between the effects of TET1 knockdown alone and the effects of HDM treatment alone. One especially striking pattern was that both TET1 knockdown and HDM treatment generally led to decreased chromatin accessibility at largely the same genomic loci. Transcription factor enrichment analyses indicated that altered chromatin accessibility following the loss of TET1 may affect, or be affected by, CTCF and CEBP binding. TET1 loss also led to changes in DNA methylation, but these changes were generally in regions where accessibility was not changing.

Conclusions

TET1 regulates gene expression through different mechanisms (DNA methylation and chromatin accessibility) in different parts of the genome in the airway epithelial cells, which mediates inflammatory responses to allergen. Collectively, our data suggest novel molecular mechanisms through which TET1 regulates critical pathways following allergen challenges and contributes to the development of asthma.

House dust mite allergy: The importance of house dust mite allergens for diagnosis and immunotherapy

House dust mite (HDM) allergy belongs to the most important allergies and affects approximately 65-130 million people worldwide. Additionally, untreated HDM allergy may lead to the development of severe disease manifestations such as atopic dermatitis or asthma. Diagnosis and immunotherapy of HDM allergic patients are well established but are often hampered by the use of mite extracts that are of bad quality and lack important allergens. The use of individual allergens seems to be a promising alternative to natural allergen extracts, since they represent well-defined components that can easily be produced and quantified. However, a thorough characterization of the individual allergens is required to determine their clinical relevance and to identify those allergens that are required for correct diagnosis of HDM allergy and for successful immunotherapy. This review gives an update on the individual HDM allergens and their benefits for diagnosis and immunotherapy of HDM allergic patients.

Cost-effectiveness analysis of house dust mite allergen immunotherapy in children with allergic asthma

BACKGROUND

Cost-effectiveness studies evaluating allergen immunotherapy (AIT) in children are limited but needed to drive clinical and policy-making decisions such as reimbursement of new interventions. In this study, we compared the cost effectiveness of subcutaneous (SCIT) and sublingual immunotherapy (SLIT) tablets to the standard of care (SOC) treatment in children with house dust mite-driven (HDM) allergic asthma.

METHODS

We developed a hypothetical Markov model based on the Global Initiative for Asthma (GINA) severity steps to compare the three strategies over a 10-year horizon divided by cycles of 6 months. SOC was used as a reference to calculate the incremental cost-effectiveness ratio (ICER). Deterministic and probabilistic sensitivity analyses were used to assess models' uncertainty. Other scenarios were evaluated to strengthen the presentation of results.

RESULTS

The ICER for SCIT and SLIT tablets was 1281€ and 7717€, respectively. The cost-effectiveness threshold for Portugal was 18,482.80€; both treatment approaches were below this limit. The major contributors to these results were the AIT effects on reducing moderate and severe exacerbations and asthma controller medication. In the sensitivity analysis, SCIT revealed a higher probability of cost-effectiveness than SLIT. When including allergic rhinitis as comorbidity, ICER values reduced markedly, especially for SCIT intervention.

CONCLUSIONS

AIT was cost effective in children with HDM-driven allergic asthma, especially when given by the subcutaneous route. The high probability of cost effectiveness, especially for SCIT, may drive future policy decisions and AIT-prescribing habits. AIT adherence greatly influenced the results highlighting the value of implementing strategies to promote adherence rates.

Novel Approaches for Inhibiting the Indoor Allergen Der f 2 Excreted from House Dust Mites by Todomatsu Oil Produced from Woodland Residues

House dust mite (HDM) is a globally ubiquitous domestic cause of allergic diseases. There is a pressing demand to discover efficient, harmless, and eco-friendly natural extracts to inhibit HDM allergens that are more likely to trigger allergies and challenging to be prevented entirely. This study, therefore, is aimed at assessing the inhibition of the allergenicity of major HDM allergen Der f 2 by todomatsu oil extracted from residues of Abies Sachalinensis. The inhibition was investigated experimentally (using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)) and in silico using molecular docking. The results showed that todomatsu oil inhibits the allergenicity of Der f 2 by reducing its amount instead of the IgG binding capacity of a single protein. Moreover, the compounds in todomatsu oil bind to Der f 2 via alkyl hydrophobic interactions. Notably, most compounds interact with the hydrophobic amino acids of Der f 2, and seven substances interact with CYS27. Contrarily, the principal compounds fail to attach to the amino acids forming the IgG epitope in Der f 2. Interestingly, chemical components with the lowest relative percentages in todomatsu oil show high-affinity values on Der f 2, especially β-maaliene (-8.0 kcal/mol). In conclusion, todomatsu oil has been proven in vitro as a potential effective public health strategy to inhibit the allergenicity of Der f 2.

Immunotherapy for Asthma

Asthma represents one of the biggest global health concerns with increasing prevalence and influence on global health. Several distinct asthma phenotypes have been identified with one of the most common, earliest recognized, and described being the allergic asthma phenotype, in which allergens trigger asthma through mechanisms involving allergen-specific immunoglobulin E (IgE). Allergen-specific immunotherapy (AIT), in the forms of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT), has been used for many decades as a tool for reducing IgE-mediated sensitization and controlling symptoms of allergic disease, most commonly for allergic rhinitis, and it remains the only currently available disease modifying therapy in atopic patients. AIT has been studied for use in mild to moderate allergic asthma. While the data are often inconsistent, and utilize a multitude of different methods, antigens, and outcome measures, in general, AIT may have several beneficial effects on asthma disease control, quality of life, and requirement for medication. These benefits are notable when immunotherapy is used as an adjunct to pharmacologic treatment in carefully selected and monitored patients with mild to moderate persistent asthma. Patients with severe asthma are excluded from these trials. Importantly, patients with asthma, and in particular severe asthma, may have a higher rate of systemic adverse reactions to SCIT, including anaphylaxis, however, these events are overall rare. Future research in the area is needed to definitively assess the benefit of SCIT and SLIT for patients with asthma, comparing outcomes with different methods, addressing the role of AIT in severe asthma, significance of multiallergen AIT in allergic asthma, and safety concerns in asthma.

Large-scale provocation studies identify maladaptive responses to ubiquitous aeroallergens as a correlate of severe allergic rhinoconjunctivitis and asthma

BACKGROUND

Allergic asthma (AA) and allergic rhinoconjunctivitis (ARC) are common comorbid environmentally triggered diseases. We hypothesized that severe AA/ARC reflects a maladaptive or unrestrained response to ubiquitous aeroallergens.

METHODS

We performed provocation studies wherein six separate cohorts of persons (total n = 217) with ARC, with or without AA, were challenged once or more with fixed concentrations of seasonal or perennial aeroallergens in an aeroallergen challenge chamber (ACC).

RESULTS

Aeroallergen challenges elicited fully or partially restrained vs. unrestrained evoked symptom responsiveness, corresponding to the resilient and adaptive vs. maladaptive AA/ARC phenotypes, respectively. The maladaptive phenotype was evoked more commonly during challenge with a non-endemic versus endemic seasonal aeroallergen. In an AA cohort, symptom responses evoked after house dust mite (HDM) challenges vs. recorded in the natural environment were more accurate and precise predictors of asthma severity and control, lung function (FEV1), and mechanistic correlates of maladaptation. Correlates included elevated levels of peripheral blood CD4+ and CD8+ T-cells, eosinophils, and T-cell activation, as well as gene expression proxies for ineffectual epithelial injury/repair responses. Evoked symptom severity after HDM challenge appeared to be more closely related to levels of CD4+ and CD8+ T-cells than eosinophils, neutrophils, or HDM-specific IgE.

CONCLUSIONS

Provocation studies support the concept that resilience, adaptation, and maladaptation to environmental disease triggers calibrate AA/ARC severity. Despite the ubiquity of aeroallergens, in response to these disease triggers in controlled settings (ie, ACC), most atopic persons manifest the resilient or adaptive phenotype. Thus, ARC/AA disease progression may reflect the failure to preserve the resilient or adaptive phenotype. The triangulation of CD8+ T-cell activation, airway epithelial injury/repair processes and maladaptation in mediating AA disease severity needs more investigation.

Evaluating Children and Adolescents with Suspected Exercise Induced Asthma: Real Life Data

OBJECTIVE

Exercise-induced bronchoconstriction (EIB) occurs frequently in children and adolescents and may be a sign of insufficient asthma control. EIB is often evaluated by respiratory symptoms, spirometry, eNO measurement and methacholine testing (MCT) instead of time consuming exercise test. Aim of this study was to analyse the amount of patients for which an exercise challenge in a cold chamber (ECC) was needed for a clear EIB diagnosis, to characterize EIB phenotypes and the incidence of exercise induced laryngeal obstruction (EILO) in a large cohort of patients with EIB.

METHODS

A retrospective analysis was performed in 595 children and adolescents (mean age 12.1 years) with suspected EIB from January 2014 to December 2018. Complete data sets of skin prick test, spirometry, eNO and MCT were available from 336 patients.

RESULTS

An ECC to confirm the EIB diagnosis was performed in 125 (37.2%) of patients. Three EIB phenotypes were detected: group 1: EIB without allergic sensitization (n=159); group 2: EIB with other than house dust mite (HDM) sensitization (n=87) and group 3: EIB with HDM sensitization (n=90). MCT and eNO showed significant differences between the subgroups: An eNO>46 ppb and/or a MCT<0.1 mg was found in 23.9% vs. 50.6% vs. 57.8% in group 1-3, respectively. Significantly more patients suffered from EILO in group 1 compared to group 2 and 3 (n=13 vs. n=1).

CONCLUSION

EIB without sensitization is as often as EIB with sensitization. In patients without sensitization, EILO has to be considered as a possible cause of symptoms during exercise.

Exposures in the Indoor Environment and Prevalence of Allergic Conditions in the United States of America

Our study examines the association of the presence of mildew, cockroaches, and pets in homes as well as household dust allergens with the prevalence and/or severity of allergic diseases. No study has concurrently assessed home environment exposures in relation to allergic conditions in the general US population. Data from 5409 participants from the 2005–2006 National Health and Nutrition Examination Survey (NHANES) living in their current homes for ≥one year were analyzed. Multivariate logistic regression analyses between home exposures and allergic diseases prevalence and severity were performed. In adjusted analyses, mildew was associated with higher current asthma, allergies, and allergic rhinitis prevalence; endotoxin, with higher current asthma prevalence; and dust Canis familiaris (Can f) 1, with higher allergic rhinitis prevalence. However, presence of cockroaches and dust Dermatophagoides farinae (Der f) 1 were associated, respectively, with lower current asthma and allergies prevalence. Presence of mildew, dust Der f1, Dermatophagoides pteronyssinus (Der p) 1, Felis domesticus (Fel d) 1, and endotoxin were all associated with asthma and/or wheeze severity. Non-atopic asthma was more frequent with mildew and/or musty smell dust and higher dust Fel d1 concentration, while atopic asthma was more prevalent with higher Can f1 and endotoxin concentrations in dust. This study confirms previous relationships and reports novel associations, generating hypotheses for future research.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

Time to onset of improvements in Quality of Life from Temperature-controlled Laminar Airflow (TLA) in severe allergic asthma

BACKGROUND

Allergen avoidance is important in allergic asthma management. Nocturnal treatment with Temperature-controlled Laminar Airflow (TLA; Airsonett^®) has been shown to provide significant reduction of exposure to allergens in the breathing zone, leading to long-term reduction in airway inflammation and improvement in quality of life. Allergic asthma patients uncontrolled on GINA step 4 were found to benefit the most. A frequently asked question from clinicians and funders is related to time to onset (TTO) of improvements for patients using TLA.

METHODS

Asthma Quality of Life Questionnaire (AQLQ) scores were collected in a previous study. TTO of improvements in Quality of Life was analysed for difference (TLA-placebo) in Area-under-Curve using backwards deletion from 12, 9, 6, 3 down to 1 month for the AQLQ total score, the four individual domains and specifically the sleep question.

RESULTS

Patients with uncontrolled asthma on GINA step 4 (n = 87)) reported a statistically significant and clinically relevant (≥0.5 point) improvement in total AQLQ score (0.57; p = 0.009) after 3 months treatment for TLA over placebo. The shortest TTO was within 1 month for the environmental domain (0.68; p = 0.016) and the sleep question (0.771; p = 0.037). TTO for the emotional and symptom domains was 3 months (0.66; p = 0.020 and 0.64; p = 0.014 respectively) and for the activity domain 6 months (0.47; p = 0.036).

CONCLUSION

Nocturnal avoidance of allergens using TLA provided a statistically significant and clinically relevant improvement in total AQLQ score within 3 months in patients in the GINA 4 + ACT<18 group. Questions related to sleep quality may provide the first signal of response already within a month after commencing treatment.

Similar localization of conformational IgE epitopes on the house dust mite allergens Der p 5 and Der p 21 despite limited IgE cross-reactivity

BACKGROUND

Due to high IgE recognition frequency and high allergenic activity, Der p 5 and Der p 21 are clinically important house dust mite (HDM) allergens. The objective of this study was to characterize the immunodominant IgE epitopes of Der p 5 and Der p 21 responsible for their high allergenic activity.

METHODS

A panel of 12 overlapping peptides spanning the Der p 5 and Der p 21 sequence were synthesized to search for sequential IgE epitopes by direct testing for allergic patients' IgE reactivity. Peptide-specific antibodies raised in rabbits were used in inhibition studies for localizing conformational IgE epitopes which were visualized on the surfaces of the allergen structures by molecular modelling. IgE cross-reactivity between the allergens was investigated by IgE inhibition studies.

RESULTS

Immunodominant IgE epitopes defined by allergic patients' IgE on Der p 5 and Der p 21 were primarily of the conformational, discontinuous type including N- and C-terminal portions of the protein. They could be located on each allergen on one area with similar localization, but despite similar structure of the allergens, no relevant IgE cross-reactivity could be detected.

CONCLUSION

Our study shows that Der p 5 and Der p 21 contain a major conformational IgE epitope-containing area located on similar portions of their structure, but they lack relevant IgE cross-reactivity. These data are important for the development of modern allergy vaccines based on defined molecules for allergen-specific immunotherapy of HDM allergy.

Diesel exhaust and house dust mite allergen lead to common changes in the airway methylome and hydroxymethylome

Exposures to diesel exhaust particles (DEP) from traffic and house dust mite (HDM) allergens significantly increase risks of airway diseases, including asthma. This negative impact of DEP and HDM may in part be mediated by epigenetic mechanisms. Beyond functioning as a mechanical barrier, airway epithelial cells provide the first line of immune defense towards DEP and HDM exposures. To understand the epigenetic responses of airway epithelial cells to these exposures, we exposed human bronchial epithelial cells to DEP and HDM and studied genome-wide 5-methyl-cytosine (5mC) and 5-hydroxy-methylcytosine (5hmC) at base resolution. We found that exposures to DEP and HDM result in elevated TET1 and DNMT1 expression, associated with 5mC and 5hmC changes. Interestingly, over 20% of CpG sites are responsive to both exposures and changes in 5mC at these sites negatively correlated with gene expression differences. These 5mC and 5hmC changes are located in genes and pathways related to oxidative stress responses, epithelial function and immune cell responses and are enriched for binding sites of transcription factors (TFs) involved in these pathways. Histone marks associated with promoters, enhancers and actively transcribed gene bodies were associated with exposure-induced DNA methylation changes. Collectively, our data suggest that exposures to DEP and HDM alter 5mC and 5hmC levels at regulatory regions bound by TFs, which coordinate with histone marks to regulate gene networks of oxidative stress responses, epithelial function and immune cell responses. These observations provide novel insights into the epigenetic mechanisms that mediate the epithelial responses to DEP and HDM in airways.

The role of allergy immunotherapy in the treatment of asthma

PURPOSE OF REVIEW

Asthma and allergic rhinitis are two of the most widespread chronic medical conditions. Asthma, a condition which encompasses chronic inflammation of the lower airway resulting in expiratory obstruction, may represent an end phase along the allergic disease spectrum ultimately stemming initially from nasal allergic rhinitis and bronchial hyper-reactivity. The purpose of this review was to evaluate the available published literature over the past 12 months regarding the role of allergy immunotherapy in the treatment of asthma.

RECENT FINDINGS

Recent clinical trials, systematic reviews, and meta-analyses have demonstrated that allergen-specific immunotherapy (ASI), especially sublingual immunotherapy for as short as 12 months, may help improve asthma symptoms and reduce medication usage. However, studies have not demonstrated overall improvement in pulmonary function tests despite improvement in symptoms. Barriers to asthmatic patients initiating and maintaining ASI include lack of payment by health insurer, inconvenience, and potentially worsening asthma exacerbations/symptoms for patients with severe disease.

SUMMARY

ASI may change the natural course of allergic asthma by reducing the risk of acute respiratory exacerbations and symptoms. Additional studies are necessary to examine whether early treatment of allergy sensitivities with ASI may ultimately prevent the progression to asthma.

Secreted PLA2 group X orchestrates innate and adaptive immune responses to inhaled allergen

Phospholipase A2 (PLA2) enzymes regulate the formation of eicosanoids and lysophospholipids that contribute to allergic airway inflammation. Secreted PLA2 group X (sPLA2-X) was recently found to be increased in the airways of asthmatics and is highly expressed in airway epithelial cells and macrophages. In the current study, we show that allergen exposure increases sPLA2-X in humans and in mice, and that global deletion of Pla2g10 results in a marked reduction in airway hyperresponsiveness (AHR), eosinophil and T cell trafficking to the airways, airway occlusion, generation of type-2 cytokines by antigen-stimulated leukocytes, and antigen-specific immunoglobulins. Further, we found that Pla2g10-/- mice had reduced IL-33 levels in BALF, fewer type-2 innate lymphoid cells (ILC2s) in the lung, less IL-33-induced IL-13 expression in mast cells, and a marked reduction in both the number of newly recruited macrophages and the M2 polarization of these macrophages in the lung. These results indicate that sPLA2-X serves as a central regulator of both innate and adaptive immune response to proteolytic allergen.

Long-term effects of allergen-specific subcutaneous immunotherapy for house dust mite induced allergic rhinitis

Background:

Allergic rhinitis is strongly associated with the presence of house dust mites. This study investigated the long-term effects of allergen-specific immunotherapy. Allergen-specific immunotherapy was applied over three years. The study was based on a 10-year follow up of patients with allergic rhinitis.

Methods:

The study was conducted between 2001 and 2015. Skin prick test results and symptom scores were evaluated before (26 patients) and after 3 years (20 patients) of allergen-specific immunotherapy (using data from a previously published study), and 10 years after allergen-specific immunotherapy had ended (20 of 26 patients).

Results:

The symptom scores before allergen-specific immunotherapy were significantly higher than those obtained after 3 years of allergen-specific immunotherapy and 10 years after allergen-specific immunotherapy (p < 0.0175). There were no significant differences between the scores obtained at 3 years and 10 years after allergen-specific immunotherapy (p > 0.0175).

Conclusion:

Subcutaneous immunotherapy is an effective treatment for house dust mite induced allergic rhinitis.

House dust mite allergy: Its innate immune response and immunotherapy

Over the past few decades, allergic diseases have become increasingly prevalent worldwide. House dust mite (HDM) is the most important domestic source for allergic diseases such as allergic rhinitis, asthma and atopic dermatitis. Dermatophagoides pteronyssinus (Der p) is the major environmental allergen in southeast Asia because of the humid and warm environment is suitable for its growth. In the recent year, role of HDM allergen in allergic inflammation through innate immune system has been well studied. Toll-like receptors (TLRs), protease-activated receptors (PARs) and DC-SIGN could be activated by different HDM major allergens and proinflammatory cytokines also be upregulated. Treatment efficacy for HDM allergy is unsatisfied to the patients and the medication is limited. Immunotherapy provided an alternative option for treating HDM allergy through targeted to the mechanisms of allergic reaction and represented a long-term symptoms relief. Gene specific immunotherapy was currently being developed and it could decrease allergic inflammation and improve the efficacy of treatment. In this report, we reviewed recent studies about the role of HDM allergy in innate immune system and its immunotherapy. Understanding the HDM allergen induced signal transduction pathway and developed allergen specific immunotherapy could help physicians to create precise diagnosis and solve unmet need in HDM allergy.

Clinical evaluation for sublingual immunotherapy with Dermatophagoides farinae drops in adult patients with allergic asthma

PURPOSE

The efficacy and safety of sublingual immunotherapy (SLIT) in house dust mite-induced allergic asthma (AA) have yet to be firmly established, especially in adult patients. Our objective is to evaluate the efficacy of SLIT with Dermatophagoides farinae drops in adult patients with AA.

METHODS

One hundred and thirty-four adult patient data with house dust mite (HDM)-induced AA who had been treated for 2 years were collected. These patient data that we collected were divided into the SLIT group (n = 85) and control group (n = 49). All patients were treated with low to moderate dose of inhaled glucocorticoid and long-acting β2 agonists. Patients in the SLIT group were further treated with D. farinae drops. Clinical scores including the total asthma symptom score (TASS), total asthma medicine score (TAMS), asthma control test (ACT), and peak flow percentage (PEF%) were assessed before treatment and at yearly visits. The presence of adverse events (AEs) were recorded once a month.

RESULTS

Before treatment, the PEF% in the SLIT group was significantly lower than that in the control group (p < 0.05). After 2 years, both treatments were effective in the clinical scores when compared with baseline values (all p < 0.001). Meanwhile, the SLIT group showed significantly lower TASS and TAMS (all p < 0.001) and higher ACT (p < 0.001) and PEF% (p < 0.05) when compared with the control group. No severe systemic AEs were reported.

CONCLUSIONS

SLIT with D. farinae drops plus pharmacotherapy is more effective than routine drug treatment in adult patients with AA.

Specific immunotherapy for rhinitis and asthma with a subcutaneous hypoallergenic high-dose house dust mite extract: results of a 9-month therapy

AIM

Effectiveness of a 9-month specific immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract to reduce allergic symptoms as perceived by patients and physicians was assessed.

PATIENTS & METHODS

An observational, retrospective, multicenter study was carried out in patients diagnosed with asthma and/or rhinitis caused by house dust mites having started specific immunotherapy with Acaroid(®). Primary end point was perceived effectiveness.

RESULTS

A total of 409 patients were included. According to physician-completed visual analogue scale, a 58.1% clinical improvement was observed. Patient-completed visual analogue scale showed a 69.8% clinical improvement. The need for unscheduled/emergency healthcare, as an indication of poor quality of life, showed a significant reduction.

CONCLUSION

Our results confirm in a real-world setting the findings from randomized clinical trials of high-dose house dust mites allergoid immunotherapy with a subcutaneous hypoallergenic high-dose house dust mite extract.

IgE in the diagnosis and treatment of allergic disease

Traditionally, the concept of allergy implied an abnormal response to an otherwise benign agent (eg, pollen or food), with an easily identifiable relationship between exposure and disease. However, there are syndromes in which the relationship between exposure to the relevant allergen and the "allergic" disease is not clear. In these cases the presence of specific IgE antibodies can play an important role in identifying the relevant allergen and provide a guide to therapy. Good examples include chronic asthma and exposure to perennial indoor allergens and asthma related to fungal infection. Finally, we are increasingly aware of forms of food allergy in which the relationship between exposure and the disease is delayed by 3 to 6 hours or longer. Three forms of food allergy with distinct clinical features are now well recognized. These are (1) anaphylactic sensitivity to peanut, (2) eosinophilic esophagitis related to cow's milk, and (3) delayed anaphylaxis to red meat. In these syndromes the immunology of the response is dramatically different. Peanut and galactose α-1,3-galactose (alpha-gal) are characterized by high- or very high-titer IgE antibodies for Ara h 2 and alpha-gal, respectively. By contrast, eosinophilic esophagitis is characterized by low levels of IgE specific for milk proteins with high- or very high-titer IgG4 to the same proteins. The recent finding is that patients with alpha-gal syndrome do not have detectable IgG4 to the oligosaccharide. Thus the serum results not only identify relevant antigens but also provide a guide to the nature of the immune response.

Der p 11 is a major allergen for house dust mite-allergic patients suffering from atopic dermatitis

House dust mites (HDMs) belong to the most potent indoor allergen sources worldwide and are associated with allergic manifestations in the respiratory tract and the skin. Here we studied the importance of the high-molecular-weight group 11 allergen from Dermatophagoides pteronyssinus (Der p 11) in HDM allergy. Sequence analysis showed that Der p 11 has high homology to paramyosins from mites, ticks, and other invertebrates. A synthetic gene coding for Der p 11 was expressed in Escherichia coli and rDer p 11 purified to homogeneity as folded, alpha-helical protein as determined by circular dichroism spectroscopy. Using antibodies raised against rDer p 11 and immunogold electron microscopy, the allergen was localized in the muscle beneath the skin of mite bodies but not in feces. IgE reactivity of rDer p 11 was tested with sera from HDM-allergic patients from Europe and Africa in radioallergosorbent test-based dot-blot assays. Interestingly, we found that Der p 11 is a major allergen for patients suffering from atopic dermatitis (AD), whereas it is only a minor allergen for patients suffering from respiratory forms of HDM allergy. Thus, rDer p 11 might be a useful serological marker allergen for the identification of a subgroup of HDM-allergic patients suffering from HDM-associated AD.

Efficacy of sublingual immunotherapy for house dust mite allergic rhinitis

In the present study, we investigated the outcomes of sublingual immunotherapy (SLIT) in house dust mite-induced allergic rhinitis (HDM-AR) patients. In this prospective, multicentric study, 186 patients with AR who had positive skin prick test results for HDMs were included. The patients were administered SLIT using Staloral 300 for 1 year. Evaluation of the patients regarding symptom scores, clinical findings and Rhinitis Quality of Life Questionnaire (RQLQ) scores was performed at baseline, and then at 6 and 12 months of therapy. Our results showed that, for all of the evaluated items (symptom scores, clinical findings and RQLQ scores), 12-month values were significantly lower than those at 6 months and baseline. Similarly, 6-month values were significantly lower than those at baseline. There were no complications in any of our patients. SLIT for HDM-AR is a treatment modality that can be used safely. We obtained better results than expected, and the treatment showed a positive psychological effect; the patients believed that SLIT was the final step of treatment and, which made them feel better.

House dust mite sublingual immunotherapy is safe and appears to be effective in moderate, persistent asthma

BACKGROUND

The efficacy and safety of sublingual immunotherapy in house dust mite-induced asthma have yet to be firmly established. We report the results of a double-blind, placebo-controlled, randomized clinical trial performed in mainland China.

METHODS

After a three-month baseline period, 484 asthmatic adults were randomized 2 : 1 to 12 months of daily treatment with either an aqueous, standardized, 300 index of reactivity mixture of Dermatophagoides pteronyssinus and Dermatophagoides farinae extracts or a placebo. The primary efficacy criterion was well-controlled asthma for at least 16 of the last 20 weeks of treatment.

RESULTS

In the active (n = 308) and placebo (n = 157) groups, well-controlled asthma was achieved by 85.4% and 81.5% of the patients, respectively (P = 0.244). A subsequent post hoc analysis by asthma severity revealed significant clinical benefits in actively treated subjects with moderate, persistent asthma at baseline [401-800 μg budesonide/day (n = 175)], with greater achievement of well-controlled asthma (80.5% and 66.1% for the active treatment and placebo groups, respectively; P = 0.021) and totally controlled asthma (54.0% and 33.9%, respectively, P = 0.008), a higher percentage of patients with an asthma control questionnaire score < 0.75 (56.6% and 40.0%, respectively; P = 0.039) and a greater mean reduction in inhaled corticosteroid use (218.5 μg and 126.2 μg, respectively; P = 0.004). The active vs placebo differences in disease control and corticosteroid use were not significant for mild, persistent asthma. No treatment-related serious adverse events were reported.

CONCLUSIONS

Sublingual mite allergen immunotherapy was well tolerated in adult asthmatics and effectively controlled disease in patients with moderate (but not mild) persistent asthma (ClinicalTrials.gov: NCT00660452).

Sensitization to food and inhalant allergens in relation to age and wheeze among children with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is common in children; however, persistence of AD with or without asthma is less common. Longitudinal studies remain limited in their ability to characterize how IgE antibody responses evolve in AD, and their relationship with asthma.

OBJECTIVE

To use a cross-sectional study design of children with active AD to analyse age-related differences in IgE antibodies and relation to wheeze.

METHODS

IgE antibodies to food and inhalant allergens were measured in children with active AD (5 months to 15 years of age, n = 66), with and without history of wheeze.

RESULTS

Whereas IgE antibodies to foods persisted at a similar prevalence and titre throughout childhood, IgE antibodies to all aeroallergens rose sharply into adolescence. From birth, the chance of sensitization for any aeroallergen increased for each 12-month increment in age (OR ≥ 1.21, P < 0.01), with the largest effect observed for dust mite (OR = 1.56, P < 0.001). A steeper age-related rise in IgE antibody titre to dust mite, but no other allergen was associated with more severe disease. Despite this, sensitization to cat was more strongly associated with wheeze (OR = 4.5, P < 0.01), and linked to Fel d 1 and Fel d 4, but not Fel d 2. Comparison of cat allergic children with AD to those without, revealed higher IgE levels to Fel d 2 and Fel d 4 (P < 0.05), but not Fel d 1.

CONCLUSIONS AND CLINICAL RELEVANCE

Differences in sensitization to cat and dust mite among young children with AD may aid in identifying those at increased risk for disease progression and development of asthma. Early sensitization to cat and risk for wheeze among children with AD may be linked to an increased risk for sensitization to a broader spectrum of allergen components from early life. Collectively, our findings argue for early intervention strategies designed to mitigate skin inflammation in children with AD.

An evidence-based analysis of house dust mite allergen immunotherapy: a call for more rigorous clinical studies

BACKGROUND

According to meta-analyses and reviews, subcutaneous allergen immunotherapy (SCIT) and sublingual allergen immunotherapy (SLIT) are beneficial in patients with allergic rhinitis (AR) and allergic asthma (AA) induced by house dust mites (HDMs). However, the reported effect sizes have varied greatly from one study to another.

OBJECTIVE

We sought to perform an evidence-based medicine assessment of commercially available SCIT and SLIT formulations in patients with HDM-induced AA and HDM-induced AR.

METHODS

We searched for double-blind, placebo-controlled randomized clinical trials and analyzed study designs, doses, regimens, patient-reported outcomes, safety reporting, and compliance.

RESULTS

Forty-four studies met our inclusion criteria. Some studies tested both SLIT and SCIT or scored both AA and AR outcomes; therefore we reviewed 35 treatment arms in patients with AA (20 for SCIT and 15 for SLIT) and 23 treatment arms in patients with AR (7 for SCIT and 16 for SLIT). The treatment duration ranged from 6 weeks to 3 years. For SCIT, the dose of Der p 1 major allergen (when reported) ranged from 7 to 30 μg for maintenance doses and 60 to 420 μg for cumulative doses. For SLIT, the doses of Der p 1 (when reported) were 0.8 to 70 μg for maintenance doses and 60 to 23,695 μg for cumulative doses. Safety data were often absent or poorly reported. A statistically significant active versus placebo symptom score was observed more frequently for SCIT than for SLIT.

CONCLUSION

There is no consensus on basic treatment parameters (eg, dose and duration) in HDM SCIT and SLIT. There is an urgent need for rigorous, long-term, double-blind, placebo-controlled randomized clinical trials with an efficacy criterion that reflects the particular features of HDM-induced allergic disease.

A distinct sensitization pattern associated with asthma and the thymic stromal lymphopoietin (TSLP) genotype

BACKGROUND

Atopy is a phenotypically heterogeneous condition, and the extent to which atopy accounts for asthma is controversial. In this study, we aimed to identify the presence of distinct sensitization patterns to common inhaled allergens and their association with asthma, allergic rhinitis and TSLP genotypes.

METHODS

We studied 1683 adults from Tsukuba, a city in central Japan and 297 adults from Kamishihoro, a cedar-free, birch-dominant town in northern Japan. Levels of total serum IgE and specific IgE antibodies towards 14 major inhaled allergens were measured. With the use of these measures, cluster analysis was applied to classify the subjects' sensitization patterns. We also examined the genetic effects of 2 TSLP functional SNPs on the development of each sensitization pattern.

RESULTS

In the Tsukuba study, cluster analysis identified four clusters, including "Dust mite dominant", "Multiple pollen", "Cedar dominant", and "Low reactivity". In the Kamishihoro study, "Dust mite dominant", "Multiple pollen" and "Low reactivity" clusters were also identified, but a "Cedar dominant" cluster was not formed. The association with asthma was strongest for the "Dust mite dominant" cluster in both the Tsukuba and the Kamishihoro studies. In never smokers, both SNPs were associated with the "Dust mite dominant" cluster (OR > 1.2). In contrast, in current or past smokers, these alleles were inversely associated with the "Multiple pollen" cluster (OR < 0.5).

CONCLUSIONS

Cluster analysis identified the presence of distinct sensitization patterns to common inhaled allergens. TSLP may cause asthma by promoting innate allergic responses to indoor allergens and this contribution is significantly modified by smoking.

Impact of atopy on asthma and allergic rhinitis in the cohort for reality and evolution of adult asthma in Korea

PURPOSE

Atopy is an important cause of asthma. Few data on the prevalence of atopy or comparisons with clinical characteristics of asthma in Korean patients have been published. We evaluated the effects of atopy on clinical profiles and airway inflammation in Korean asthmatics.

METHODS

We retrospectively enrolled 1,492 asthmatics from the Cohort for Reality and Evolution of Adult Asthma in Korea (COREA) cohort who had undergone skin prick tests for aeroallergens. The patients' clinical characteristics, lung function, PC20, and sputum and blood inflammatory cell counts were compared based on the presence or absence of atopy. Atopy was defined as one or more positive reactions (A/H ratio >1) on a skin prick test.

RESULTS

Among 11 aeroallergens, house dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus) were the most prevalent cause of a positive skin prick test. As compared with non-atopic asthmatics, atopic asthmatics showed early onset of the disease. Atopic patients with asthma had a higher FEV1, FVC, and FEV1/FVC as compared with non-atopic patients with asthma. In addition, asthmatics without atopy had more uncontrolled asthma (P=0.001) and severe rhinitis (P<0.05) as compared with atopic asthmatics. Smoking, as measured in pack years, was higher in the non-atopic asthmatics than in the atopic asthmatics. The erythrocyte sedimentation rate was higher in non-atopic asthmatics than in the atopic asthmatics and patients with non-atopic asthma had a higher sputum neutrophil count than did those with atopic asthma.

CONCLUSIONS

Our data indicate that atopic asthmatics had an early onset of disease and high IgE levels, while the non-atopic asthmatics had decreased lung function and a high sputum neutrophil count, suggesting that a different approach is needed to treat atopic asthma.

Household mold and dust allergens: exposure, sensitization and childhood asthma morbidity

BACKGROUND

Few studies address concurrent exposures to common household allergens, specific allergen sensitization and childhood asthma morbidity.

OBJECTIVE

To identify levels of allergen exposures that trigger asthma exacerbations in sensitized individuals.

METHODS

We sampled homes for common indoor allergens (fungi, dust mites (Der p 1, Der f 1), cat (Fel d 1), dog (Can f 1) and cockroach (Bla g 1)) for levels associated with respiratory responses among school-aged children with asthma (N=1233) in a month-long study. Blood samples for allergy testing and samples of airborne fungi and settled dust were collected at enrollment. Symptoms and medication use were recorded on calendars. Combined effects of specific allergen sensitization and level of exposure on wheeze, persistent cough, rescue medication use and a 5-level asthma severity score were examined using ordered logistic regression.

RESULTS

Children sensitized and exposed to any Penicillium experienced increased risk of wheeze (odds ratio [OR] 2.12 95% confidence interval [CI] 1.12, 4.04), persistent cough (OR 2.01 95% CI 1.05, 3.85) and higher asthma severity score (OR 1.99 95% CI 1.06, 3.72) compared to those not sensitized or sensitized but unexposed. Children sensitized and exposed to pet allergen were at significantly increased risk of wheeze (by 39% and 53% for Fel d 1>0.12 μg/g and Can f 1>1.2 μg/g, respectively). Increased rescue medication use was significantly associated with sensitization and exposure to Der p 1>0.10 μg/g (by 47%) and Fel d 1>0.12 μg/g (by 32%).

CONCLUSION

Asthmatic children sensitized and exposed to low levels of common household allergens Penicillium, Der p 1, Fel d 1 and Can f 1 are at significant risk for increased morbidity.

The translational repressor T-cell intracellular antigen-1 (TIA-1) is a key modulator of Th2 and Th17 responses driving pulmonary inflammation induced by exposure to house dust mite

T-cell intracellular antigen-1 (TIA-1) is a translational repressor that dampens the production of proinflammatory cytokines and enzymes. In this study we investigated the role of TIA-1 in a mouse model of pulmonary inflammation induced by exposure to the allergenic extract (Df) of the house dust mite Dermatophagoides farinae. When intranasally challenged with a low dose of Df, mice lacking TIA-1 protein (Tia-1(-/-)) showed more severe airway and tissue eosinophilia, infiltration of lung bronchovascular bundles, and goblet cell metaplasia than wild-type littermates. Tia-1(-/-) mice also had higher levels of Df-specific IgE and IgG(1) in serum and ex vivo restimulated Tia-1(-/-) lymph node cells and splenocytes transcribed and released more Th2/Th17 cytokines. To evaluate the site of action of TIA-1, we studied the response to Df in bone marrow chimeras. These experiments revealed that TIA-1 acts on both hematopoietic and non-hematopoietic cells to dampen pulmonary inflammation. Our results identify TIA-1 as a negative regulator of allergen-mediated pulmonary inflammation in vivo. Thus, TIA-1 might be an important player in the pathogenesis of bronchial asthma.

Galactose-α-1,3-galactose-specific IgE is associated with anaphylaxis but not asthma

RATIONALE

IgE antibodies to the mammalian oligosaccharide galactose-α-1,3-galactose (α-gal) are common in the southeastern United States. These antibodies, which are induced by ectoparasitic ticks, can give rise to positive skin tests or serum assays with cat extract.

OBJECTIVES

To evaluate the relationship between IgE antibodies to α-gal and asthma, and compare this with the relationship between asthma and IgE antibodies to Fel d 1 and other protein allergens.

METHODS

Patients being investigated for recurrent anaphylaxis, angioedema, or acute urticaria underwent spirometry, exhaled nitric oxide, questionnaires, and serum IgE antibody assays. The results were compared with control subjects and cohorts from the emergency department in Virginia (n = 130), northern Sweden (n = 963), and rural Kenya (n = 131).

MEASUREMENTS AND MAIN RESULTS

Patients in Virginia with high-titer IgE antibodies to α-gal had normal lung function, low levels of exhaled nitric oxide, and low prevalence of asthma symptoms. Among patients in the emergency department and children in Kenya, there was no association between IgE antibodies to α-gal and asthma (odds ratios, 1.04 and 0.75, respectively). In Sweden, IgE antibodies to cat were closely correlated with IgE antibodies to Fel d 1 (r = 0.83) and to asthma (P < 0.001).

CONCLUSIONS

These results provide a model of an ectoparasite-induced specific IgE response that can increase total serum IgE without creating a risk for asthma, and further evidence that the main allergens that are causally related to asthma are those that are inhaled.

The indoor air and asthma: the role of cat allergens

PURPOSE OF REVIEW

The objective is to discuss recent progress in our understanding of the role of the indoor environment in asthma, focusing on the special role of cat allergens.

RECENT FINDINGS

Sensitization to Fel d 1 is the dominant event in inhalant responses to cat; however, there are also IgE responses to the lipocalin (Fel d 4), to cat albumin (Fel d 2), and to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) on cat IgA (Fel d 5w) and other molecules. The dose response and routes of sensitization for these allergens are now thought to be diverse. It is important to remember that exposure outside a house with a cat is sufficient to cause sensitization. Furthermore, the only solid evidence about a role in asthma relates to Fel d 1. Recently, it has been shown that tolerance associated with early exposure to cats can persist to age 18 and that IgE to alpha-gal (on cat IgA) is not related to asthma. In addition, a recent study of anti-IgE reinforces the evidence that IgE antibodies to indoor allergens make a major contribution to asthma severity.

SUMMARY

Exposure to Fel d 1 in a home with a cat is far higher than the levels necessary to induce an allergic (IgE antibody) response. In keeping with that, children may develop tolerance, which can be long-lived. In addition, there is increasing evidence that IgE antibodies to an inhalant allergen, such as Fel d 1, dust mite, or cockroach, are causally related to lung inflammation and asthma.

Molecular determinants for antibody binding on group 1 house dust mite allergens

House dust mites produce potent allergens, Der p 1 and Der f 1, that cause allergic sensitization and asthma. Der p 1 and Der f 1 are cysteine proteases that elicit IgE responses in 80% of mite-allergic subjects and have proinflammatory properties. Their antigenic structure is unknown. Here, we present crystal structures of natural Der p 1 and Der f 1 in complex with a monoclonal antibody, 4C1, which binds to a unique cross-reactive epitope on both allergens associated with IgE recognition. The 4C1 epitope is formed by almost identical amino acid sequences and contact residues. Mutations of the contact residues abrogate mAb 4C1 binding and reduce IgE antibody binding. These surface-exposed residues are molecular targets that can be exploited for development of recombinant allergen vaccines.

Does allergen avoidance work?

Allergic rhinitis affects a large portion of the population. Patients are frequently sensitized to indoor allergens. The most important contributors are house dust mites, pets, and fungi. In very controlled environments where allergen exposure is significantly reduced, individuals have been shown to have clinical improvement in allergic rhinitis and/or asthma symptoms. Achieving sufficient exposure reduction in the home has proven difficult. Nonetheless, evidence exists that demonstrates exposure avoidance can be useful as an adjunct to other therapies, such as pharmacotherapy and immunotherapy, for the treatment of allergic rhinitis.

Comparison in asthma and allergy prevalence in the two major cities in Greece: the ISAAC phase II survey

BACKGROUND

Variability in the prevalence of allergic diseases has been detected not only between different countries, but also between cities with similar national and different socio-economic or climatic characteristics. The aim of this study was to determine the prevalence of childhood asthma and allergies and which factors are associated with them, in the two largest Greek cities, Athens and Thessaloniki.

METHODS

Two thousand and twenty-three Greek 9-10-year-old schoolchildren from Athens (Central Greece) and Thessaloniki (North Greece, more humid), were included in ISAAC-II study. All participants followed the ISAAC-II protocol by questionnaire, skin prick testing and flexural dermatitis examination.

RESULTS

Compared with Athens, the prevalence of current wheezing (8.4% vs. 5.7%, p=0.002), lifetime asthma (11.5% vs. 7.7%, p=0.004), atopic current asthma (3.2% vs. 1.6%, p=0.02), allergic rhinitis (8.2% vs. 5.2%, p=0.007), and hay fever (21.7% vs. 12.5%, p<0.001) were higher in Thessaloniki. The overall sensitisation rate was also higher in Thessaloniki than in Athens (25.2% vs. 16%, p<0.001) with more prevalent sensitising due to the perennial allergens (D. pteronyssinus, D. farinae, Alternaria tenuis) and cat dander. Perennial allergens sensitisation was a risk factor for current asthma in both cities.

CONCLUSION

A higher prevalence of asthma symptoms, allergic rhinitis, and sensitisation rate was detected in Greek schoolchildren living in Thessaloniki compared to those in Athens. Allergy to mites and mould was more prevalent in Thessaloniki. The more humid weather of Thessaloniki may be implicated.

House dust mite sensitization in toddlers predicts current wheeze at age 12 years

BACKGROUND

Identification of children at risk of developing asthma provides a window of opportunity for risk-reducing interventions. Allergen sensitization might identify high-risk children.

OBJECTIVE

We sought to determine whether skin prick tests (SPTs) to individual allergens up to age 2 years predict wheeze at age 12 years.

METHODS

In a birth cohort of 620 children oversampled for familial allergy, sensitization was assessed by using SPTs (monosensitized, polysensitized, or either) to 6 allergens at ages 6, 12, and 24 months. Wheeze and eczema were recorded 18 times during the first 2 years. Current wheeze was recorded at age 12 years. Adjusted associations were evaluated by multiple logistic regression.

RESULTS

A positive SPT to house dust mite (HDM) at age 1 or 2 years predicted wheeze at age 12 years (adjusted odds ratio: 1 year, 3.31 [95% CI 1.59-6.91]; 2 years, 6.37 [95% CI, 3.48-11.66]). Among wheezy 1-year-olds, those who were HDM sensitized had a 75% (95% CI, 51% to 91%) probability of wheeze at age 12 years compared with a 36% (95% CI, 23% to 50%) probability among those not sensitized. Among eczematous 1-year-olds, those who were HDM sensitized had a 67% (95% CI, 45% to 84%) probability of wheeze at age 12 years compared with a 35% (95% CI, 25% to 45%) probability among those not sensitized. Among 1-year-old children with both eczema and wheeze, the probability of wheeze at age 12 years was 64% (95% CI, 35% to 87%) if HDM sensitized and 50% (95% CI, 26% to 74%) if not.

CONCLUSION

HDM sensitization at age 1 or 2 years in wheezing and eczematous children at increased familial allergy risk predicts asthma and may inform management of these high-risk groups.

Serum IgE reactivity profiling in an asthma affected cohort

BACKGROUND

Epidemiological evidence indicates that atopic asthma correlates with high serum IgE levels though the contribution of allergen specific IgE to the pathogenesis and the severity of the disease is still unclear.

METHODS

We developed a microarray immunoassay containing 103 allergens to study the IgE reactivity profiles of 485 asthmatic and 342 non-asthmatic individuals belonging to families whose members have a documented history of asthma and atopy. We employed k-means clustering, to investigate whether a particular IgE reactivity profile correlated with asthma and other atopic conditions such as rhinitis, conjunctivitis and eczema.

RESULTS

Both case-control and parent-to-siblings analyses demonstrated that while the presence of specific IgE against individual allergens correlated poorly with pathological conditions, particular reactivity profiles were significantly associated with asthma (p<10E-09). An artificial neural network (ANN)-based algorithm, calibrated with the profile reactivity data, correctly classified as asthmatic or non-asthmatic 78% of the individual examined. Multivariate statistical analysis demonstrated that the familiar relationships of the study population did not affect the observed correlations.

CONCLUSIONS

These findings indicate that asthma is a higher-order phenomenon related to patterns of IgE reactivity rather than to single antibody reactions. This notion sheds new light on the pathogenesis of the disease and can be readily employed to distinguish asthmatic and non-asthmatic individuals on the basis of their serum reactivity profile.

Indoor allergen exposure, sensitization, and development of asthma in a high-risk birth cohort

Contradictory findings have been observed for the association of house dust mite (HDM), cat, and dog allergen exposure with sensitization and asthma. We sought to determine the relationship between exposures to these allergens, at various points during early childhood, and specific sensitization and asthma at age 7 in a high-risk birth cohort. As part of a multi-faceted Canadian intervention program for the primary prevention of asthma in high-risk infants, children were assessed by pediatric allergists at age 7 for asthma and underwent allergy skin prick testing. House dust samples were analyzed for HDM, cat, and dog allergen levels at several time points during years 1 and 7 of life. Multiple logistic regression analyses were carried out for the combined cohort and separately for the control and intervention groups. Exposure to a higher level of HDM allergen in year 1 or year 7 was associated with a higher risk of year 7 sensitization to HDM but not asthma. Exposure to higher levels of cat allergen in year 1 or year 7 did not affect the risk of year 7 sensitization to cat or asthma. Dog ownership, or exposure to higher levels of dog allergen in year 1 or year 7, did not affect the risk of year 7 sensitization to dog; however, year 7 dog allergen exposure (intervention group only) or ownership was associated with increased year 7 asthma risk. Our findings suggest that in high-risk children, there are allergen-specific associations of exposure with sensitization and with asthma; early life-elevated HDM exposure was associated with risk of sensitization but not asthma while the opposite was true for dog exposure.