BACKGROUND: Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood. METHODS: We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-analysis. RESULTS: Significant associations with wheeze in the past year were detected in only four genes (IL4R, TLR4, MS4A2, TLR9, P<0.05), with per allele odds ratios generally <1.3. Variants in IL4R and TLR4 were also related to allergen-specific IgE, while polymorphisms in FCER1B (MS4A2) and TLR9 were not. There were also highly significant associations (P<0.001) between SPINK5 variants and visible eczema (but not IgE levels) and between IL13 variants and total IgE. Heterogeneity of effects across centres was rare, despite differences in allele frequencies. CONCLUSIONS: Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

BACKGROUND: Asthma is a complex disease that has genetic and environmental causes. The genetic factors associated with susceptibility to asthma remain largely unknown. METHODS: We carried out a genomewide association study involving children with asthma. The sample included 793 North American children of European ancestry with persistent asthma who required daily inhaled glucocorticoid therapy and 1988 matched controls (the discovery set). We also tested for genomewide association in an independent cohort of 917 persons of European ancestry who had asthma and 1546 matched controls (the replication set). Finally, we tested for an association between 20 single-nucleotide polymorphisms (SNPs) at chromosome 1q31 and asthma in 1667 North American children of African ancestry who had asthma and 2045 ancestrally matched controls. RESULTS: In our meta-analysis of all samples from persons of European ancestry, we observed an association, with genomewide significance, between asthma and SNPs at the previously reported locus on 17q21 and an additional eight SNPs at a novel locus on 1q31. The SNP most strongly associated with asthma was rs2786098 (P=8.55x10(-9)). We observed replication of the association of asthma with SNP rs2786098 in the independent series of persons of European ancestry (combined P=9.3x10(-11)). The alternative allele of each of the eight SNPs on chromosome 1q31 was strongly associated with asthma in the children of African ancestry (P=1.6x10(-13) for the comparison across all samples). The 1q31 locus contains DENND1B, a gene that is expressed by natural killer cells and dendritic cells and that encodes a protein that interacts with the tumor necrosis factor alpha receptor. CONCLUSIONS: We have identified a locus containing DENND1B on chromosome 1q31.3 that is associated with susceptibility to asthma. Copyright 2009 Massachusetts Medical Society.

Summary Background Recent studies indicate that prenatal vitamin D intake may protect against the development of atopic diseases in young children. Vitamin D has been shown to induce tolerogenic antigen-presenting cells such as dendritic cells. Whether the allergy-protective potential of prenatal vitamin D is mediated through such mechanisms is, however, unknown. Objective To evaluate the association between prenatal vitamin D supplementation and tolerogenic antigen-presenting cells in cord blood (CB) as determined by mRNA measurement of immunoglobulin-like transcripts (ILT)3 and ILT4. Methods A prospective multi-centre birth cohort was established in rural areas of five European countries. Information on maternal exposures including vitamin D intake was collected by questionnaires during pregnancy. The gene expression of ILT3 and ILT4 was analysed by real-time PCR in the CB of 927 children. Maternal vitamin D supplementation was assessed in Finland and France (n=349). Results Maternal vitamin D supplementation during pregnancy was associated with an increase in the gene expression of ILT3 (P=0.012) and ILT4 (P<0.001). This association remained significant for ILT4 (P=0.020) and showed a positive trend for the gene expression of ILT3 (P=0.059) after multivariate analysis controlling for various confounders. Conclusions Vitamin D supplementation during pregnancy may increase the mRNA levels of ILT3 and ILT4 in CB. This finding may point towards an early induction of tolerogenic immune responses by maternal vitamin D intake.

To cite this article: Weinmayr G, Genuneit J, Nagel G, Björkstén B, van Hage M, Priftanji A, Cooper P, Rijkjärv M-A, von Mutius E, Tsanakas J, Forastiere F, Doekes G, Garrido JB, Suarez-Varela MM, Bråbäck L, Strachan DP, the ISAAC Phase Two Study Group. International variations in associations of allergic markers and diseases in children: ISAAC Phase Two. Allergy 2009; DOI: 10.1111/j.1398-9995.2009.02283.x. Abstract Background: Circulating allergen-specific IgE (sIgE) and skin prick tests (SPT) are used to define atopy. Downregulation of local inflammatory responsiveness has been proposed to explain a low prevalence of positive SPTs in less affluent countries. We analysed the association between SPTs, total and allergen-specific IgE and their relationships to allergic symptoms in centres with diverse living conditions. Methods: Cross-sectional studies of stratified random samples of 8 to 12-year-old children (n = 7461) used the standardized methodology of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC). Symptoms of asthma, rhinitis and eczema were ascertained by parental questionnaires. Skin examination, hypertonic saline bronchial challenge, six aeroallergen SPTs and measurements of serum total IgE and sIgE were performed. Results: In nonaffluent countries, a higher proportion of children with positive SPT had no detectable sIgE (range 37-61%) than in affluent countries (0-37%). Total serum IgE was associated with all disease outcomes among children with both positive SPT and sIgE (P < 0.001), but only with self-reported eczema in children with negative SPTs and negative sIgE. Conclusions: The international pattern of discordance between SPT and sIgE results did not support the downregulation hypothesis. Among children with no evidence of sensitization to common aeroallergens, increased total IgE contributes little to the risk of wheeze and rhinitis in the general population but may play a role in eczema.

The pre- and postnatal environment may represent a window of opportunity for allergy and asthma prevention, and the hygiene hypothesis implies that microbial agents may play an important role in this regard. Using the cowshed-derived bacterium Acinetobacter lwoffii F78 together with a mouse model of experimental allergic airway inflammation, this study investigated the hygiene hypothesis, maternal (prenatal) microbial exposure, and the involvement of Toll-like receptor (TLR) signaling in prenatal protection from asthma. Maternal intranasal exposure to A. lwoffii F78 protected against the development of experimental asthma in the progeny. Maternally, A. lwoffii F78 exposure resulted in a transient increase in lung and serum proinflammatory cytokine production and up-regulation of lung TLR messenger RNA. Conversely, suppression of TLRs was observed in placental tissue. To investigate further, the functional relevance of maternal TLR signaling was tested in TLR2/3/4/7/9(-/-) knockout mice. The asthma-preventive effect was completely abolished in heterozygous offspring from A. lwoffii F78-treated TLR2/3/4/7/9(-/-) homozygous mother mice. Furthermore, the mild local and systemic inflammatory response was also absent in these A. lwoffii F78-exposed mothers. These data establish a direct relationship between maternal bacterial exposures, functional maternal TLR signaling, and asthma protection in the progeny.

BACKGROUND: Traditional farming represents a unique model situation to investigate the relationship of early-life farm-related exposure and allergy protection. OBJECTIVES: To investigate associations between maternal farm exposures and cytokine production in cord blood (CB) mononuclear cells in a prospective multinational birth cohort of 299 farm and 326 nonfarm children and their families. METHODS: Supernatants from phorbol 12-myristate 13-acetate/ionomycin-stimulated CB mononuclear cells were assessed for the production of IFN-gamma, TNF-alpha, IL-5, IL-10, and IL-12. RESULTS: Significantly higher levels of IFN-gamma and TNF-alpha in farm compared with nonfarm children were found, whereas IL-5, IL-10, and IL-12 levels did not differ between study groups. Maternal contact with different farm animal species and barns and consumption of farm-produced butter during pregnancy enhanced the production of proinflammatory CB cytokines, whereas maternal consumption of farm-produced yogurt resulted in significant lower levels of IFN-gamma and TNF-alpha in umbilical blood. CONCLUSION: Maternal exposure to farming activities and farm dairy products during pregnancy modulated cytokine production patterns of offspring at birth.

BACKGROUND: Phase III of the International Study of Asthma and Allergies in Childhood measured the global prevalence of symptoms of asthma, rhinoconjunctivitis, and eczema in children. OBJECTIVE: To investigate the associations between the use of antibiotics in the first year of life and symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old. METHODS: Parents or guardians of children 6 and 7 years old completed written questionnaires on current symptoms and possible risk factors. Prevalence odds ratios (ORs) were estimated by using logistic regression. RESULTS: A total of 193,412 children from 71 centers in 29 countries participated. Reported use of antibiotics in the first year of life was associated with an increased risk of current asthma symptoms (wheezing in the previous 12 months) with an OR (adjusted for sex, region of the world, language, and per capita gross national income) of 1.96 (95% CI, 1.85-2.07); this fell to 1.70 (1.60-1.80) when adjusted for other risk factors for asthma. Similar associations were observed for severe asthma symptoms (OR, 1.82; 95% CI, 1.67-1.98), and asthma ever (OR, 1.94; 95% CI, 1.83-2.06). Use of antibiotics in the first year of life was also associated, but less strongly, with increased risks of current symptoms of rhinoconjunctivitis (OR, 1.56; 95% CI, 1.46-1.66) and eczema (OR, 1.58; 95% CI, 1.33-1.51). CONCLUSION: There is an association between antibiotic use in the first year of life and current symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old. Further research is required to determine whether the observed associations are causal or are a result of confounding by indication or reverse causation.

BACKGROUND: Allergic inflammation can trigger neuronal dysfunction and structural changes in the airways and the skin. Levels of brain-derived neurotrophic factor (BDNF) are strongly up regulated at the location of allergic inflammation. AIM: We systematically investigated whether polymorphisms in the BDNF gene influence the development or severity of asthma and atopic diseases. METHODS: The BDNF gene was screened for mutations in 80 chromosomes. Genotyping of six BDNF tagging polymorphisms was performed in a cross-sectional study population of 3099 children from Dresden and Munich (age 9-11 years, ISAAC II). Furthermore, polymorphisms were also investigated in an additional 655 asthma cases analysed with a random sample of 767 children selected from ISAAC II. Associations were calculated via chi-square test and anova using SAS Genetics and spss. RESULTS: We identified nine polymorphisms with minor allele frequency >or=0.03, one of them leading to an amino acid change from Valine to Methionine. In the cross-sectional study population, no significant association was found with asthma or any atopic disease. However, when more severe asthma cases from the MAGIC study were analysed, significant asthma effects were observed with rs6265 (odds ratio 1.37, 95% confidence interval 1.14-1.64, P = 0.001), rs11030101 (OR 0.82, 95%CI 0.70-0.95, P = 0.009) and rs11030100 (OR 1.19, 95%CI 1.00-1.42, P = 0.05). CONCLUSIONS: As in previous studies, effects of BDNF polymorphisms on asthma remain controversial. The data may suggest that BDNF polymorphisms contribute to severe forms of asthma.

Background: The number of allergens to be tested in order to identify sensitized patients is important in order to have the most cost-effective approach in epidemiological studies. Objective: To define the minimal number and the type of skin prick test (SPT) allergens required to identify a patient as sensitized using results of the new Pan-European GA(2)LEN skin prick test study. Method: In a large Pan-European multicenter (17 centers in 14 countries) patient based study, a standardized panel of 18 allergens has been prick tested using a standardized procedure. Conditional approach allowed to determine the allergens selection. Result: Among the 3034 patients involved, 1996 (68.2%) were sensitized to at least one allergen. Overall, eight allergens (grass pollen, Dermatophagoides pteronyssinus, birch pollen, cat dander, Artemisia, olive pollen, Blatella and Alternaria) allowed to identified more than 95% of sensitized subjects. However, differences were observed between countries, two allergens being sufficient for Switzerland (grass pollen and cat dander) as opposed to nine for France (grass pollen, Dermatophagoides pteronyssinus, olive pollen, cat dander, Blatella, cypress, dog dander, alder and [Artemisia or Alternaria]). According to country, up to 13 allergens were needed to identify all sensitized subjects. Conclusion: Eight to ten allergens allowed the identification of the majority of sensitized subjects. For clinical care of individual patients, the whole battery of 18 allergens is needed to appropriately assess sensitization across Europe.

BACKGROUND: Skin prick testing is the standard for diagnosing IgE-mediated allergies. A positive skin prick reaction, however, does not always correlate with clinical symptoms. A large database from a Global Asthma and Allergy European Network (GA(2)LEN) study with data on clinical relevance was used to determine the clinical relevance of sensitizations against the 18 most frequent inhalant allergens in Europe. The study population consisted of patients referred to one of the 17 allergy centres in 14 European countries (n = 3034, median age = 33 years). The aim of the study was to assess the clinical relevance of positive skin prick test reactions against inhalant allergens considering the predominating type of symptoms in a pan-European population of patients presenting with suspected allergic disease. METHODS: Clinical relevance of skin prick tests was recorded with regard to patient history and optional additional tests. A putative correlation between sensitization and allergic disease was assessed using logistic regression analysis. RESULTS: While an overall rate of >or=60% clinically relevant sensitizations was observed in all countries, a differential distribution of clinically relevant sensitizations was demonstrated depending on type of allergen and country where the prick test was performed. Furthermore, a significant correlation between the presence of allergic disease and the number of sensitizations was demonstrated. CONCLUSION: This study strongly emphasizes the importance of evaluating the clinical relevance of positive skin prick tests and calls for further studies, which may, ultimately, help increase the positive predictive value of allergy testing.