Specific allergic sensitization in parents and their 18-year-old offspring in the Suburban Detroit Childhood Allergy Study

Parent-specific effects on risk of developing allergic sensitization and asthma in childhood

BACKGROUND

Parent's history of atopic traits increases the risk of the same traits in their children, but mother's history may confer an increased risk compared to father's history.

OBJECTIVE

To investigate parent-specific effects on risk of developing allergic sensitization and asthma in childhood.

METHODS

We included 685 parent-child trios from the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC2010) cohort. Parent's asthma was assessed by structured interviews and child's asthma was diagnosed prospectively at regular visits to the COPSAC clinic until age 6. Specific IgE and total IgE levels were measured in parents and children by age 0.5, 1.5 and 6 years. Associations between parent and child disease traits were analyzed using general estimating equations model adjusted for breastfeeding and maternal smoking during 3rd trimester.

RESULTS

Maternal compared to paternal elevated specific IgE increased the child's risk of elevated specific IgE from 0-6 years: adjusted odds ratio (aOR)mother = 1.49 [1.09-2.03], P = .01 and aORfather = 1.32 [0.96-1.82], P = .08. Maternal elevated total IgE also increased the child's risk of elevated total IgE: adjusted relative risk (aOR)mother = 4.32 [1.51-10.8], P < .01, while a trend was observed for paternal total IgE: aORfather = 2.01 [0.76-4.82], P = .13. Individual time point analyses showed that the maternal effect was strongest in early life, whereas the parental effects were comparable by age 6. A similar parent-specific pattern was observed for the child's risk of asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

The effect of mother's history of atopic traits on the child's risk of developing the same traits in early childhood was stronger than the effect from father's history, which was not evident before age 6. This suggests that maternal non-genetic factors seem to confer an added disease risk to the child, particularly in early life.

Relationships between total and allergen-specific serum IgE concentrations and lung function in young adults

BACKGROUND

Prior studies have shown relationships between serum immunoglobulin E (IgE) and asthma.

OBJECTIVE

To investigate relationships between total and allergen-specific IgE concentrations and lung function in young adults.

METHODS

Measurements of total IgE, allergen-specific IgE to 6 common allergens, and spirometry (forced expiratory volume in one second [FEV(1)], forced vital capacity [FVC], FEV(1)/FVC, and percent change in FEV(1) after bronchodilation) were used to calculate correlations between the logarithmically transformed IgE values and measures of lung function among participants in a birth cohort not selected for risk of allergic disease stratified by current asthma, prior asthma, or no asthma.

RESULTS

The 428 participants were 51.6% female, 93% white, and 18.4 (standard deviation = 0.6) years old. Forty-eight (11.2%) had current asthma, 55 (12.9%) had a history of asthma, and 325 (75.9%) never had asthma. For males with current asthma, correlations between total IgE and FEV(1)% and FVC% were -0.51 (P = .06) and -0.70 (P = .005), respectively. For females with current asthma, the only significant correlation was between total IgE and the FEV(1)/FVC ratio (-0.55, P = .001). After excluding smokers and individuals without detectable allergen-specific IgE, the negative correlations for both males and females remained statistically significant. The correlations among males or females with prior asthma or no history of asthma were minimal and not statistically significant. The sum of the allergen-specific IgEs showed the same pattern of relationships to lung function as did total IgE.

CONCLUSION

Our results show significant negative correlations that vary by gender between both total and allergen-specific IgE and measurements of lung function in young adults with current asthma.

Fungi and allergic lower respiratory tract diseases

Asthma is a common disorder that in 2009 afflicted 8.2% of adults and children, 24.6 million persons, in the United States. In patients with moderate and severe persistent asthma, there is significantly increased morbidity, use of health care support, and health care costs. Epidemiologic studies in the United States and Europe have associated mold sensitivity, particularly to Alternaria alternata and Cladosporium herbarum, with the development, persistence, and severity of asthma. In addition, sensitivity to Aspergillus fumigatus has been associated with severe persistent asthma in adults. Allergic bronchopulmonary aspergillosis (ABPA) is caused by A fumigatus and is characterized by exacerbations of asthma, recurrent transient chest radiographic infiltrates, coughing up thick mucus plugs, peripheral and pulmonary eosinophilia, and increased total serum IgE and fungus-specific IgE levels, especially during exacerbation. The airways appear to be chronically or intermittently colonized by A fumigatus in patients with ABPA. ABPA is the most common form of allergic bronchopulmonary mycosis (ABPM); other fungi, including Candida, Penicillium, and Curvularia species, are implicated. The characteristics of ABPM include severe asthma, eosinophilia, markedly increased total IgE and specific IgE levels, bronchiectasis, and mold colonization of the airways. The term severe asthma associated with fungal sensitization (SAFS) has been coined to illustrate the high rate of fungal sensitivity in patients with persistent severe asthma and improvement with antifungal treatment. The immunopathology of ABPA, ABPM, and SAFS is incompletely understood. Genetic risks identified in patients with ABPA include HLA association and certain T(H)2-prominent and cystic fibrosis variants, but these have not been studied in patients with ABPM and SAFS. Oral corticosteroid and antifungal therapies appear to be partially successful in patients with ABPA. However, the role of antifungal and immunomodulating therapies in patients with ABPA, ABPM, and SAFS requires additional larger studies.

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.

Mold allergen sensitization in adult asthma according to integrin β3 polymorphisms and Toll-like receptor 2/+596 genotype

BACKGROUND

Integrin β3 (ITGB3) and Toll-like receptor 2 (TLR2) are candidate genes for asthma and sensitization to mold allergens. Integrin β3 forms a complex with TLR2, and this biological interaction is required for the response of monocytes to TLR2 agonists such as fungal glucan.

OBJECTIVE

To study whether genetic interaction between single nucleotide polymorphisms (SNPs) in genes encoding the TLR2-ITGB3 complex enhances susceptibility to mold sensitization.

METHODS

Association analysis was conducted in 1243 adults (524 with asthma) who participated in the follow-up of the Epidemiological Study on the Genetics and Environment of Asthma. Allergic sensitization to mold allergens was determined by skin prick testing. Association of mold sensitization with 14 ITGB3 SNPs was tested under an additive genetic model. Interaction between ITGB3 SNPs and TLR2/+596, which was previously shown to be associated with asthma, was studied.

RESULTS

A positive skin prick test to mold was found in 115 subjects with asthma (22.0%) and in 61 subjects without asthma (8.5%). The ITGB3 rs2056131 A allele was associated with mold sensitization in subjects with asthma with an odds ratio (95% CI) of 0.60 (0.43-0.83; P = .001). Ten other ITGB3 SNPs were significantly associated with mold sensitization in TLR2/+596TT subjects with asthma (P = .03-.002), whereas much weaker associations were found in carriers of the TLR2/+596 C allele (P = .60-.04). Interaction between TLR2/+596 and these ITGB3 SNPs was statistically significant (P interaction = .05-.001).

CONCLUSION

TLR2/+596 genotype may influence the association between ITGB3 SNPs and mold sensitization in adults with asthma.

Are specific allergen sensitivities inherited?

A family history of an allergic condition is a well-accepted risk factor for the development of an allergic condition in an individual, particularly for allergic disorders such as asthma, eczema, and allergic rhinitis. However, the question of whether specific allergen sensitization is inherited requires a complicated answer, as environmental exposure plays an important role in the development of allergen-specific IgE. This article summarizes the findings of recent studies in the literature regarding what is known about the inheritance of specific allergens. Overall, properly collected and analyzed data appear to both support and refute the hypothesis that specific allergen sensitization is inherited, even when attempting to account for the complexities of varying study methodologies and the evaluation of diverse populations and communities.