Asthma genetics

Main Polymorphisms in Aspirin-Exacerbated Respiratory Disease

Aspirin exacerbated respiratory disease (AERD) is a condition caused by increased bronchoconstriction in people with asthma after taking aspirin or another NSAID. Molecular analysis of the human genome has opened up new perspectives on human polymorphisms and disease. This study was conducted to identify the genetic factors that influence this disease due to its unknown genetic factors. We evaluated research studies, letters, comments, editorials, eBooks, and reviews. PubMed/MEDLINE, Web of Sciences, Cochrane Library, and Scopus were searched for information. We used the keywords polymorphisms, aspirin-exacerbated respiratory disease, asthma, allergy as search terms. This study included 38 studies. AERD complications were associated with polymorphisms in ALOX15, EP2, ADRB2, SLC6A12, CCR3, CRTH2, CysLTs, DPCR1, DPP10, FPR2, HSP70, IL8, IL1B, IL5RA, IL-13, IL17RA, ILVBL, TBXA2R, TLR3, HLA-DRB and HLA-DQ, HLA-DR7, HLA-DP. AERD was associated with heterogeneity in gene polymorphisms, making it difficult to pinpoint specific gene changes. Therefore, diagnosing and treating AERD may be facilitated by examining common variants involving the disease.

[Genetic aspects involved in asthma]

Asthma is an etiologically heterogeneous disease resulting from a complex interaction between genetic. The genetic aspects involved in asthma, which were analyzed from the perspective of the traditional model of multifactorial inheritance, were susceptibility, host factors, and environmental exposures. In the present paper, studies on their family aggregation, concordance in twins, and heritability were analized; as well as the current knowledge about candidate genes, genome wide association studies, and epigenomics contributions and other omic studies that have increased our knowledge about their pathophysiology and environmental interactions.

Airway Microbial Diversity is Inversely Associated with Mite-Sensitized Rhinitis and Asthma in Early Childhood

Microbiota plays an important role in regulating immune responses associated with atopic diseases. We sought to evaluate relationships among airway microbiota, serum IgE levels, allergic sensitization and their relevance to rhinitis and asthma. Microbial characterization was performed using Illumina-based 16S rRNA gene sequencing of 87 throat swabs collected from children with asthma (n = 32) and rhinitis (n = 23), and from healthy controls (n = 32). Data analysis was performed using QIIME (Quantitative Insights Into Microbial Ecology) v1.8. Significantly higher abundance of Proteobacteria was found in children with rhinitis than in the healthy controls (20.1% vs. 16.1%, P = 0.009). Bacterial species richness (Chao1 index) and diversity (Shannon index) were significantly reduced in children with mite sensitization but not in those with food or IgE sensitization. Compared with healthy children without mite sensitization, the mite-sensitized children with rhinitis and asthma showed significantly lower Chao1 and Shannon indices. Moraxella and Leptotrichia species were significantly found in the interaction of mite sensitization with rhinitis and asthma respectively. Airway microbial diversity appears to be inversely associated with sensitization to house dust mites. A modulation between airway dysbiosis and responses to allergens may potentially cause susceptibility to rhinitis and asthma in early childhood.

Results from a community-based trial testing a community health worker asthma intervention in Puerto Rican youth in Chicago

Abstract Objective: Puerto Rican children suffer disproportionately from asthma. Project CURA tested the efficacy of a community health worker (CHW) intervention to improve use of inhaled corticosteroids (ICS) and reduce home asthma triggers in Puerto Rican youth in Chicago.

METHODS

This study employed a behavioral randomized controlled trial design with a community-based participatory research approach. Medications and technique were visually assessed; adherence was determined using dose counters. Home triggers were assessed via self-report, visual inspection and salivary cotinine. All participants received education on core asthma topics and self-management skills. Participants in the CHW arm were offered home education by the CHW in four visits over four months. The attention control arm received four newsletters covering the same topics.

RESULTS

While most of the participants had uncontrolled persistent asthma, <50% had ICS at baseline. In the CHW arms, 67% of participants received the full four-visit intervention. In the Elementary school cohort (n=51), the CHW arm had lower odds of having an ICS (OR=0.2; p=0.02) at 12-months; no differences were seen in other outcomes between arms at any time point. The only significant treatment arm difference in the high school cohort (n=50) was in inhaler technique where the CHW arm performed 18.0% more steps correct at five months (p<0.01) and 14.2% more steps correct at 12 months (p<0.01).

CONCLUSIONS

While this CHW intervention did not increase the number of participants with ICS or reduce home asthma triggers, important lessons were learned including challenges to CHW intervention fidelity and the need for CHWs to partner with clinical providers.

Revisiting the usefulness of thromboxane-A2 modulation in the treatment of bronchoconstriction in asthma

Airway smooth muscle (ASM) is the effector cell in the bronchoconstrictory pathway. It is believed that the bronchoconstriction present in asthma is associated with changes in the airway milieu that affect ASM excitation-contraction coupling and Ca(2+)-handling. Asthmatics also react differently to ventilatory mechanical strain. Deep inspiration (DI), which produces bronchodilation in healthy individuals, is less effective in asthmatics, and even enhances bronchoconstriction in moderate to severely affected patients. Our laboratory has previously studied the mechanotransductory pathway of airway stretch-activated contractions (Rstretch) leading to DI-induced bronchoconstriction. We demonstrated the ability of agonists acting through thromboxane A2 (TxA2) receptors to amplify airway Rstretch responses. Despite the involvement of excitatory prostanoids in bronchoconstriction, clinical trials on treatments targeting TxA2-synthase inhibition and TP-receptor antagonism have produced mixed results. Studies in Western populations produced mostly negative results, whereas studies performed in Asian populations showed mostly positive outcomes. In this review, we discuss the role of TxA2-synthase inhibition and TP-receptor antagonism in the treatment of asthmatics. We present information regarding variations in study designs and the possible role of TP-receptor gene polymorphisms in previous study outcome discrepancies. Perhaps future studies should focus on asthmatic patients with DI-induced bronchoconstriction in particular, planting the seed for the individualized treatments for asthmatics.

Harnessing opportunities in non-animal asthma research for a 21st-century science

The incidence of asthma is on the increase and calls for research are growing, yet asthma is a disease that scientists are still trying to come to grips with. Asthma research has relied heavily on animal use; however, in light of increasingly robust in vitro and computational models and the need to more fully incorporate the 'Three Rs' principles of Replacement, Reduction and Refinement, is it time to reassess the asthma research paradigm? Progress in non-animal research techniques is reaching a level where commitment and integration are necessary. Many scientists believe that progress in this field rests on linking disciplines to make research directly translatable from the bench to the clinic; a '21st-century' scientific approach to address age-old questions.

A sequence variant on 17q21 is associated with age at onset and severity of asthma

A sequence variant (rs7216389-T) near the ORMDL3 gene on chromosome 17q21 was recently found to be associated with childhood asthma. We sought to evaluate the effect of rs7216389-T on asthma subphenotypes and its correlation with expression levels of neighboring genes. The association of rs7216389-T with asthma was replicated in six European and one Asian study cohort (N=4917 cases N=34 589 controls). In addition, we found that the association of rs7216389-T was confined to cases with early onset of asthma, particularly in early childhood (age: 0-5 years OR=1.51, P=6.89.10(-9)) and adolescence (age: 14-17 years OR=1.71, P=5.47.10(-9)). A weaker association was observed for onset between 6 and 13 years of age (OR=1.17, P=0.035), but none for adult-onset asthma (OR=1.07, P=0.12). Cases were further stratified by sex, asthma severity and atopy status. An association with greater asthma severity was observed among early-onset asthma cases (P=0.0012), but no association with sex or atopy status was observed among the asthma cases. An association between sequence variants and the expression of genes in the 17q21 region was assessed in white blood cell RNA samples collected from Icelandic individuals (n=743). rs7216389 associated with the expression of GSDMB and ORMDL3 genes. However, other sequence variants showing a weaker association with asthma compared with that of rs7216389 were more strongly associated with the expression of both genes. Thus, the contribution of rs7216389-T to the development of asthma is unlikely to operate only through an impact on the expression of ORMDL3 or GSDMB genes.

Allergen-specific subcutaneous immunotherapy in allergic asthma: immunologic mechanisms and improvement

Allergic asthma is a disease characterized by persistent allergen-driven airway inflammation, remodeling, and airway hyperresponsiveness. CD4(+) T-cells, especially T-helper type 2 cells, play a critical role in orchestrating the disease process through the release of the cytokines IL-4, IL-5, and IL-13. Allergen-specific immunotherapy (SIT) is currently the only treatment with a long-term effect via modifying the natural course of allergy by interfering with the underlying immunological mechanisms. However, although SIT is effective in allergic rhinitis and insect venom allergy, in allergic asthma it seldom results in complete alleviation of the symptoms. Improvement of SIT is needed to enhance its efficacy in asthmatic patients. Herein, the immunoregulatory mechanisms underlying the beneficial effects of SIT are discussed with the ultimate aim to improve its treatment efficacy.

A LC-MS-based method for quantification of biomarkers from serum of allergic rats

Allergies are highly complex disorders with clinical manifestations ranging from mild oral, gastrointestinal, recurrent wheezing, and cutaneous symptoms to life-threatening systemic conditions. The levels of arachidonic acid, eicosanoids, histamine, organic acids and valine are considered to have a variety of physiological functions in connection with allergies. In this research, we have developed a RP-LC/MS method to separate and quantitate six different potential endogenous biomarkers, including leukotrieneB₄ (LTB₄), prostaglandinD₂ (PGD₂), arachidonic acid (AA), histamine (HI), lactic acid (LA) and valine (VAL), from serum of rats with ovalbumin (OVA)-induced allergy and normal rats, and the discrepancies between the model group and the control group were compared. The separation was performed on a Prevail C₁₈ column (250 mm × 4.6 mm, 5 μm) with a gradient elution of acetonitrile with 0.1% formic acid (v/v) and 10 mM ammonium formate (adjusted to pH 4.0 with formic acid) at a flow rate of 0.5 mL min⁻¹ The method was validated and shown to be sensitive, accurate (recovery values 76.16–92.57%) and precise (RSD < 10% for all compounds) with a linear range over several orders of magnitude. The method was successfully applied to rat serum and shown to be indicative of the endogenous levels of biomarkers within the rat body. The analysis of the biomarkers can provide insight into the allergic mechanisms associated with related diseases.

A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2

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.

Lack of association between asthma and ABO blood group

ABO is the most important blood group system in transfusion and transplantation practices. Glycosyltransferases are controlled by the ABO system which is helpful in building oligosaccharide structures on the cell surface of erythrocytes and vascular endothelium and in the exocrine secretion system, including the respiratory tract. We analyzed the ABO blood group of 200 children and adults with asthma as well as that of 2000 healthy subjects as controls. The most common blood group among the patients and controls was "O" (43.5% and 43.6%, respectively), followed by B, A, and AB. In the distribution of different blood groups, nonsignificant difference between patients and controls was observed (p = 0.931). We conclude that ABO blood group status has a nonsignificant association with asthma among the population of Mysore, Karnataka, South India.

Multivariate association test using haplotype trend regression

Genetic association analyses with haplotypes may be more powerful than analyses with single markers, under certain conditions. Furthermore, simultaneously considering multiple correlated traits may make use of additional information that would not be considered when analyzing individual traits. In this study, we propose a haplotype based test of association for multivariate quantitative traits in unrelated samples. Specifically, we extend a population based haplotype trend regression (HTR) approach to multivariate scenarios. We mainly focused on bivariate HTR, and the simulation results showed that the proposed method had correct pre-specified type-I error rates. The power of the proposed method was largely influenced by the size and source of correlation between variables, being greatest when correlation of a specific gene was opposite in sign to the residual correlation.

Etiological relationships in atopy: a review of twin studies

The genetics of asthma and atopy has been studied frequently in twin populations from various parts of the world. However, emphasis has been put on univariate analysis of questionnaire data, whereas clinical and intermediate traits only sporadically have been studied, especially in multivariate settings. This review focuses on multivariate twin studies of atopy and related traits. We conclude that the genetic liability to most atopic traits is significantly correlated but that trait-specific genes also play a role. Previous studies have estimated the genetic correlation between upper and lower respiratory allergic symptoms, that is, asthma and hay fever, to be between .47 and .95. Furthermore, atopic traits share a portion of their genetic determinants with other complex disorders like obesity and behavioral traits. A correlation of about .3 and .34 has been reported between genes associated with asthma and obesity, and between genes associated with asthma and depression, respectively. We emphasize that multivariate methods applied to twin studies, especially when genetic marker information is available, provide a valuable framework within which complex etiological mechanisms underlying atopy can be disentangled.

Association of interleukin-18 gene polymorphism with asthma in Chinese patients

Like other allergic diseases, asthma results from multiple conditions. Asthmatic beginning and severity are mediated by both environmental and genetic factors. In asthma studies, important work is realization of the genetic background and identification of genetic factors resulting in asthma development and phenomena. Here, we investigated whether interleukin (IL)-18 single nucleotide polymorphisms (SNPs) are involved in Chinese asthma patients. IL-18 (IL-18) SNP was detected by polymerase chain reaction (PCR)-based restriction analysis in 201 patients with asthma and 60 normal controls. Significant differences were found in the genotype distribution of IL-18 SNP between asthma patients and controls (P=0.000003). Allelic frequency of the IL-18 gene distinguished asthma patients from controls (P=0.000066). The results revealed a significant difference between asthma patients and normal controls in IL-18 SNP and a statistical correlation between IL-18 polymorphisms (105A/C) and asthma formation. We concluded that Chinese who carry the C/C homozygote of the IL-18-105A/C gene polymorphism in coding regions may have a higher risk of developing asthma.

Glutathione S-transferase P1, maternal smoking, and asthma in children: a haplotype-based analysis

BACKGROUND

Glutathione S-transferase P1 (GSTP1) plays a role in a spectrum of respiratory diseases; however, the effects of sequence variation across the entire locus in asthma pathogenesis have yet to be determined.

OBJECTIVES

This study was designed to investigate whether sequence variations in the GSTP1 coding and promoter regions are associated with asthma and wheezing outcomes and to determine whether variants affect susceptibility to maternal smoking.

METHODS

Four haplotype tagging SNPs were selected that accounted for 83% of the common haplotypic variation in GSTP1. The associations of GSTP1 variants with asthma and wheezing were assessed among white children in the Children's Health Study (CHS).

RESULTS

The Ile105Val allele and a SNP in the upstream promoter region (SNP1: rs6591255, putative transcription factor 1 binding site) were associated with asthma and wheezing outcomes, an association observed in two cohorts of the CHS recruited in different years. Haplotypes that included both the promoter SNP (i.e., rs6591255) and the 105 Val variant were associated with an increased risk for asthma in non-Hispanic whites. Using SNP- and haplotype-based approaches, the effect of maternal smoking on wheezing was largest in children with the Ile105Val allele.

CONCLUSIONS

Variants in both the promoter and coding regions of the GSTP1 locus may contribute to the occurrence of childhood asthma and wheezing and may increase susceptibility to adverse effects of tobacco-smoke exposure.

Association between obesity and asthma in a twin cohort

BACKGROUND

Obesity is linked to asthma in a yet poorly understood manner. We examined the relationship between obesity and asthma in a population-based sample of twins.

METHODS

From the cohorts born between 1953 and 1982, who were enrolled in The Danish Twin Registry, a total of 29 183 twin individuals participated in a nationwide questionnaire study, where data on height, weight and asthma were collected. Latent factor models of genetic and environmental effects were fitted using maximum likelihood methods.

RESULTS

The age-adjusted risk of asthma was increased both in obese females, OR = 1.96 (1.45-2.64), P < or = 0.001 and in obese males, OR = 1.59 (1.08-2.33), P = 0.02. According to best-fitting models, the heritability for obesity was 81% in males and 92% in females, whereas the heritability for asthma was 78% and 68% in males and females respectively. The age-adjusted genetic liabilities to obesity and asthma were significantly correlated only in females, r = 0.28 (0.16-0.38).

CONCLUSIONS

Obese subjects have an increased risk for asthma, which in females seems partly because of common genes.

[Asthma genetic factors]

Asthma is a chronic inflammatory airways disease, with a rising prevalence, particularly in childhood, and is considered an important public health problem. Its familial transmission is recognised, while the description and identification of the genes implicated in this disease are a challenge. In this revision paper the authors give a comprehensive explanation of the associated genes as well as the laboratorial methods that allow their identification.

Relationship between urinary cysteinyl leukotriene E4 levels and clinical response to antileukotriene treatment in patients with asthma

The aim of this study was to investigate and identify the relationship between urinary cysteinyl leukotriene E(4) levels and clinical response to antileukotriene treatment in patients with asthma. Forty-eight patients with stable mild to moderate asthma were treated with montelukast in a four-week trail. Asthmatic symptom score, beta(2)-agonist usage, percentage of eosinophil, total serum IgE concentration, forced expiratory volume in the first second (FEV(1)), peak expiratory flow rate (PEFR), and urinary leukotriene E(4) (uLTE(4)) were measured before and after treatment. Clinical response was assessed by the improvement of asthma symptom scores, beta(2)-agonist usage, and FEV(1). Responders were defined as patients who had to fit the following three criteria: a reduction of more than 20% in mean symptom score; a reduction of more than 20% in beta(2)-agonist usage, and a mean improvement of FEV(1) of more than 10% from baseline value. Others were classified as nonresponders. Logistic analysis was used to access the various clinical factors correlated with the clinical response. There were 25 responders and 23 nonresponders. The mean uLTE(4) level from the responders was higher than that from the nonresponders (224.5 +/- 34.4 vs. 175.3 +/- 37.1 pg/mg creatinine, p < 0.05). There was a significant correlation between the clinical response and the uLTE(4) level but not demographic features, percentage of eosinophils, serum IgE concentration, or spirometry (p > 0.05). Subjects with a uLTE(4) level of >/= 200 pg/mg creatinine were 3.5 times more likely to respond to montelukast than those with less than 200 pg/mg creatinine (95% confidence interval [CI] = 1.7-15.8). The uLTE(4) level is closely correlated with antileukotriene treatment. uLTE(4) is a good biomarker for selecting this drug to treat asthma.

Genetic aspects of the etiology and treatment of asthma

This article provides a clinical review of the genetic aspects of the etiology and treatment of asthma for pediatric practitioners who are experienced in asthma diagnosis and management but lack expertise in genetics and immunology. Asthma is caused by the interaction of genetic susceptibility with environmental factors. The asthmatic response is characterized by elevated production of IgE, cytokines, and chemokines; mucus hypersecretion; airway obstruction; eosinophilia; and enhanced airway hyperreactivity to spasmogens. The genes most clearly associated with asthma include disintegrin and metalloprotease ADAM-33, dipeptidyl peptidase 10, PHD finger protein 11, and the prostanoid DP1 receptor. Within a few years, practitioners may apply sophisticated knowledge of cell and molecular biology to expand pharmacotherapeutic approaches and to personalize diagnosis and management.

Asthma, genes, and air pollution

OBJECTIVE

The objective of this article is to evaluate genetic risks associated with the pulmonary response to air pollutants, including particulates and ozone.

METHODS

A comprehensive review of articles related to the genetics of asthma with particular attention to air pollution was conducted through a search of the National Library of Medicine's PubMed database.

RESULTS

Asthma, which affects over 15 million people in the United States, is characterized by inflammation leading to reversible airflow obstruction. Triggered by exposure to numerous occupational and environmental agents, asthma has long been considered to occur more frequently in families, with upwards of a 50% higher rate in the offspring of parents with asthma. Asthma genetic studies have used two major methods: mapping techniques that pinpoint gene loci and studies that identify genes and polymorphisms associated with various asthma mechanisms such as inflammatory mediators. The most consistently replicated chromosomal regions associated with asthma have been chromosomes 2q, 5q, 6p, 12 q, and 13q. Because the formation of reactive oxygen species is a major aspect of the inflammatory process of asthma, genetic aberrations associated with antioxidants such as glutathione S-transferase (GST) may shed light on reasons why some people with asthma seem more at risk of exacerbations as a result of air pollution. People with a polymorphism at the GSTP 1 locus, which codes for GST, one of a family of pulmonary antioxidants, have higher rates of asthma. Children in Mexico City with the GSTM1 null genotype demonstrated significant ozone-related decrements in lung function. Animal studies support the key role of antioxidants in reducing the inflammatory response associated with exposure to diesel exhaust particles.

CONCLUSIONS

Oxidative stress is a key mechanism underlying the toxic effects of exposure to some types of air pollution. Asthmatics with the null genotype for the antioxidant, GST, seem more at risk of the pulmonary effects of air pollution.

Improving asthma research in an inner-city Latino neighborhood with community health workers

This study tests the feasibility of a partnership between an academic medical center and community health workers to perform mutually beneficial research investigating asthma in an urban Latino neighborhood. Community heath workers participated in the study design, instrument development, implementation, and analysis. The 103 participants recruited by the community health workers were primarily Mexican with very low education and acculturation levels. After the 1-year enrollment period, the community health workers described the challenges of data collection and gave explanations for the access to care outcomes. This academic-community partnership showed that community health workers can be effective research partners.

Policy implications of genetic information on regulation under the Clean Air Act: the case of particulate matter and asthmatics

The U.S. Clean Air Act (CAA) explicitly guarantees the protection of sensitive human subpopulations from adverse health effects associated with air pollution exposure. Identified subpopulations, such as asthmatics, may carry multiple genetic susceptibilities to disease onset and progression and thus qualify for special protection under the CAA. Scientific advances accelerated as a result of the groundbreaking Human Genome Project enable the quantification of genetic information that underlies such human variability in susceptibility and the cellular mechanisms of disease. In epidemiology and regulatory toxicology, genetic information can more clearly elucidate human susceptibility essential to risk assessment, such as in support of air quality regulation. In an effort to encourage the incorporation of genomic information in regulation, the U.S. Environmental Protection Agency (EPA) has issued an Interim Policy on Genomics. Additional research strategy and policy documents from the National Academy of Science, the U.S. EPA, and the U.S. Department of Health and Human Services further promote the expansion of asthma genetics research for human health risk assessment. Through a review of these government documents, we find opportunities for the inclusion of genetic information in the regulation of air pollutants. In addition, we identify sources of information in recent scientific research on asthma genetics relevant to regulatory standard setting. We conclude with recommendations on how to integrate these approaches for the improvement of regulatory health science and the prerequisites for inclusion of genetic information in decision making.

Asthma pharmacogenomics

It is expected that future treatments will be preceded by genetic tests to prescribe the most effect asthma medication while lowering the risk of adverse side effects. However, it will not be necessary to describe all the genetic determinants affecting drug response to apply pharmacogenomics to asthma therapy. Whether pharmacogenomics becomes common practice may not depend on the availability of tests, but on factors such as affordability, ease of application, and ease of interpreting the results.

IgE generation and mast cell effector function in mice deficient in IL-4 and IL-13

IL-4 and IL-13 are potent cytokines that drive production of IgE, which is critical to the development of atopic disease. In this study, we directly compared IgE generation and IgE-dependent mast cell effector function in mouse strains lacking IL-4, IL-13, IL-4 + IL-13, or their common receptor component, IL-4Ralpha. Although serum IgE was undetectable under resting conditions in most animals deficient in one or both cytokines, peritoneal mast cells from mice lacking IL-4 or IL-13 had only partial reductions in surface IgE level. In contrast, peritoneal mast cells from IL-4/13(-/-) and IL-4Ralpha(-/-) animals were severely deficient in surface IgE, and showed no detectable degranulation following treatment with anti-IgE in vitro. Surprisingly, however, intradermal challenge with high concentrations of anti-IgE Ab induced an ear-swelling response in these strains, implying some capacity for IgE-mediated effector function in tissue mast cells. Furthermore, upon specific immunization with OVA, both IL-4/IL-13(-/-) and IL-4Ralpha(-/-) mice produced detectable levels of serum IgE and Ag-specific IgG1, and generated strong ear-swelling responses to intradermal administration of anti-IgE. These findings suggest that a mechanism for IgE production exists in vivo that is independent of IL-4 or IL-13.

Asthma phenotypes in Niue Islanders

OBJECTIVE

The aim of this study was to identify asthma phenotypes in patients of Niue Island ancestry that might be suitable for susceptibility gene mapping studies.

METHODOLOGY

Two hundred and sixteen Niue Islanders with physician-diagnosed asthma that was not secondary to other medical conditions were recruited through community organisations. Fifty-one of the subjects with asthma were resident on Niue Island and 165 in New Zealand. Each subject was interviewed and tested for atopy, serum [IgE] (5% quantile, median, 95% quantile) and lung function.

RESULTS

There were two groups of subjects defined by an age of onset of asthma less than 12 years of age (childhood-onset, boys:girls 64:65) and greater than 12 years of age (adult-onset, men:women 11:76). A positive response (wheal > 3 mm) to at least one aeroallergen was seen in 181 patients, with 168/181 (92.8%) responding to house dust mite. Twenty-eight subjects with asthma were non-atopic (no detectable wheal) and the atopy status of seven subjects with asthma could not be determined (wheal < 3 mm). In childhood-onset asthma, serum IgE levels were higher (P < 0.0001) in subjects with atopic than in subjects with non-atopic asthma. In adult-onset asthma, serum IgE levels were higher (P < 0.0001) in subjects with atopic asthma than in either subjects with non-atopic asthma or matched non-atopic subjects without asthma. The asthma phenotypes in Niue Island and New Zealand residents were similar.

CONCLUSIONS

Both atopic and non-atopic asthma phenotypes exist in Niue Islanders resident in Niue and New Zealand. The potential for mapping asthma susceptibility genes in this isolated population is discussed.

Allergic diseases and asthma in relation to serum immunoglobulins and salivary immunoglobulin A in pre-school children: a follow-up community-based study

BACKGROUND

We have previously reported an association between low IgA and allergic manifestations in early childhood (0-2 years) and have now followed our cohort for an additional 2 years.

OBJECTIVE

To evaluate in a longitudinal community-based cohort study the association between maturation of Ig production and allergic manifestations in the first 4 years of life.

METHODS

A cohort of 161 randomly selected children was followed from birth to the age of 42-48 months and evaluated at 18-23 months (EV1; n = 179) and again at the age of 42-48 months (EV2; n = 161). Diagnoses were made with the help of a clinical questionnaire, physical examination and skin prick tests (SPTs) to 10 common allergens. Serum immunoglobulins were measured at EV1 and EV2, and salivary IgA (sal-IgA) at EV2.

RESULTS

Serum IgA, IgE, IgG1, IgG2 and IgG4 increased from 2 to 4 years of age (P < 0.001) and their levels showed close correlations (P < or = 0.01 for most comparisons). Children with one or more positive SPTs had lower serum IgA (P = 0.004) and IgG4 (P = 0.05) at EV2 than those who did not respond, and children who developed allergic rhinitis between EV1 and EV2 had low sal-IgA (P = 0.006) and IgG3 (P < 0.05) at EV2. Atopic eczema was associated with low sal-IgA at EV2, and children who developed eczema between EV1 and EV2 had significantly lower sal-IgA than those who recovered after EV1 (P = 0.02).

CONCLUSION

Allergic manifestations in predisposed children may be influenced by the rate of maturation of immunological components that counteract sensitization or inhibit effector mechanisms of allergy.

Identification of polymorphisms in the human glucocorticoid receptor gene (NR3C1) in a multi-racial asthma case and control screening panel

The glucocorticoid receptor (GR) gene (NR3C1) maps to 5q31, a region genetically linked to asthma. In this study, NR3C1 exons 1A, 1B, and exons 1C to 9 (alpha and beta) were sequenced in a screening panel of asthmatics and unaffected controls from US Caucasian, African American, US Hispanic, and Dutch Caucasian populations to identify polymorphisms for genetic association studies. Eight polymorphisms were identified in exon 1A, but none were located in putative transcription regulatory sites. Thirty-four polymorphisms were identified in exons 1B to 9 (alpha and beta), 17 of which were novel. Eight coding polymorphisms were identified (4 non-synonymous). One novel mutation (Ala229Thr) was identified in a Hispanic individual. Linkage disequilibrium (LD) was strongest between polymorphisms spanning intron 2 to exon 9beta. This data shows the variability of NR3C1 polymorphism frequencies between racial groups and confirms that NR3C1 non-synonymous coding polymorphisms are generally rare in mild/moderate asthmatics and unaffected controls.

Polymorphism of the mast cell chymase gene (CMA1) promoter region: lack of association with asthma but association with serum total immunoglobulin E levels in adult atopic dermatitis

BACKGROUND

Mast cell chymase has the potential to be an important mediator of inflammation and remodelling in the asthmatic lung. Previous studies have examined association between promoter polymorphism of the chymase gene (CMA1) and allergic phenotypes but the significance of this polymorphism is unclear. We have examined association of a CMA1 variant in relation to asthma in a large UK Caucasian family cohort.

METHODS

A polymorphism of the CMA1 gene promoter (-1903G/A) was genotyped in 341 asthmatic families and in 184 non-asthmatic adults recruited from the UK PCR-RFLP based genotyping. Association with asthma diagnosis, atopy, specific and total IgE, and atopy and asthma severity was examined.

RESULTS

Case-control studies did not reveal a significant difference in allele frequency between asthmatics and controls. A significant association was found between CMA1 genotypes and total IgE levels in subjects with self-reported eczema that remained significant after correction for multiple testing (median total serum IgE GG 297 kU/L, GA 144 kU/L, AA 48.4 kU/L, Pc=0.0032).

CONCLUSION

These data suggest that CMA1 promoter polymorphism does not contribute to asthma susceptibility or severity but may be involved in regulating IgE levels in patients with eczema.

New drugs for asthma

Asthma is a major and increasing global health problem and, despite major advances in therapy, many patients' symptoms are not adequately controlled. Treatment with combination inhalers, which contain a corticosteroid and long-acting beta(2) adrenoceptor agonist, is the most effective current therapy. There is therefore a search for new therapies, particularly safe and effective oral treatments and those that are more efficacious in severe asthma. New therapies in development include mediator antagonists and inhibitors of cytokines, although these therapies might be too specific to be very effective. New anti-inflammatory therapies include corticosteroids and inhibitors of phosphodiesterase-4, p38 mitogen-activated protein kinase and nuclear factor-kappaB. The prospects for a curative treatment are on the horizon.

Influence of male sex and parental allergic disease on childhood wheezing: role of interactions

BACKGROUND

Boys have been reported to be more susceptible to childhood wheezing, whereas girls are more susceptible later in life. This difference might be related to both genetic and environmental factors.

OBJECTIVE

To investigate the influence of male sex and parental allergic disease on the development of childhood wheezing.

METHODS

Infants (n=4089) born in Stockholm were recruited in a prospective study, BAMSE. Data on parental allergic diseases were obtained from questionnaires answered at the children's birth and on symptoms of wheezing at 1, 2 and 4 years of age. Sensitization to inhalant allergens and lung function was investigated at the age of 4 years.

RESULTS

Children were classified as having recurrent, transient (n=266), early-onset persistent (n=319) and late-onset wheezing (n=195). Boys were over-represented in all groups of wheezing (odds ratio, OR=1.4-1.5) and both maternal and paternal allergic disease was of importance for the wheezing outcomes. A dominating influence from maternal allergic disease was only seen in children with persistent wheezing. An interaction exceeding additivity was found between male sex and parental allergic disease, particularly in children with persistent wheezing (OR=2.9 and 95% confidence interval, CI 95% 2.1-4.0 for boys with any parental history vs. OR=1.4, CI 95% 1.0-2.1 for girls). Interaction between male sex and parental allergic disease was also observed in children who wheezed at the age of 4 years and were sensitized to inhalant allergens.

CONCLUSION

Our data suggest an interaction between male sex and parental allergic disease in childhood wheezing, which may represent a sex-specific genetic influence.

[Efficacy of immunotherapy in the treatment of asthma]

Specific immunotherapy consists of the administration of allergen extracts to patients with allergic disease to achieve clinical tolerance to the causative allergens. Currently, it is the only etiologic treatment for respiratory allergy. A World Health Organization opinion paper published in 1997 defines immunotherapy as "the only form of treatment able to modify the natural course of allergic diseases". In patients with allergic rhinitis, several studies suggest that immunotherapy can modify the natural history of respiratory allergy by preventing the development of asthma in children with this disease. Numerous studies demonstrate its efficacy in IgE-mediated asthma and particularly in mild-to-moderate asthma. When complete avoidance of the allergen cannot be achieved with measures that allow the patient to lead a normal life, pharmacological treatment can help to control symptoms, but symptoms immediately return when treatment is interrupted. However, asthma care can be improved by allergen-specific treatment; immunotherapy may shift the immune response from an allergic pattern toward a more protective response, producing persistent improvement with reduction of symptoms and the need for pharmacological treatment. Numerous comparative studies with specific immunotherapy vs. placebo or pharmacological treatment have demonstrated the efficacy of this treatment and its advantages in control of the disease. Specific immunotherapy induces favorable clinical, biological and functional modifications in the course of allergic asthma. Significant improvement in clinical manifestations has been demonstrated, even with levels of allergen exposure higher than those at the beginning of treatment. This improvement is associated with a reduced need for antiinflammatory and bronchodilator treatment. Moreover, specific bronchial reactivity shows a clear improvement with disappearance of delayed response and a clear increase in the threshold for immediate response to the allergen. Reduction in nonspecific bronchial hyperreactivity and improvement in exercise-induced asthma are also observed. Several studies recommend an optimal duration of specific immunotherapy for allergic asthma of between 3 and 5 years to achieve maximal therapeutic efficacy. A direct relationship between treatment duration and the persistence of its effects has been observed. Moreover, the treatment is more effective when started early. The possible adverse effects related to systemic reactions should be borne in mind. Although these effects are infrequent, maximal precautions should be taken when administering this treatment. Immunotherapy is contraindicated in cases of severe asthma, heart disease, autoimmune disease and associated severe neoplastic processes. However, all the beneficial effects of immunotherapy are conditioned by an accurate and early etiological diagnosis confirming the causative allergen. The availability of high-quality allergen extracts is essential to obtain the desired effect. Inappropriate patient selection for this treatment is the main cause of its failure. The integral treatment of allergic asthma includes environmental measures, patient education, pharmacological treatment and, whenever possible, immunotherapy.

Increased levels of hypoxia-sensitive proteins in allergic airway inflammation

In this study we investigated the alterations in protein levels that are induced by allergic eosinophilic lung inflammation. Lung tissue eosinophilia and sequestration of inflammatory cells in airspaces were provoked by systemic sensitization with ovalbumin followed by repeated inhalation challenge with aerosolized ovalbumin. Proteome alterations in lung tissue and bronchoalveolar lavage fluid, respectively, were examined by two-dimensional gel electrophoresis followed by identification of proteins by mass spectrometry. Several proteins were markedly increased in inflamed tissue. In particular, several proteins that are known to be associated with hypoxia were elevated, for example, glycolytic enzymes, glucose-regulated protein 78 kD, prolyl-4-hydroxylase, peroxiredoxin 1, and arginase. Out of the identified proteins, Ym2 displayed the clearest increase, present at high levels in animals with lung eosinophilia, while being undetectable in control subjects. Furthermore, the levels of cathepsin S were markedly increased in inflamed tissue. Taken together, this study identifies a number of marker proteins associated with the pathogenesis of allergic lung inflammation and indicates a link between allergic airway inflammation and induction of hypoxia-related gene products.

Asthma, allergy, and upper airway disease

The practitioner must be aware of the strong interrelationship between asthma, allergy, eczema, otitis media, viral upper respiratory infection, and sinusitis. When allergy, eczema, otitis media (particularly after the age of 2 years), viral upper respiratory infection, or sinusitis is present in a patient, asthma must be considered as possible sequelae. If a patient has symptoms of intermittent or persistent asthma, consideration must be given to the presence of allergy, eczema, otitis media, viral upper respiratory infection, or sinusitis as comorbid conditions or possible triggers for the asthma symptoms. Failure to evaluate the entire upper and lower airway for these interrelated conditions will result in incomplete treatment and incomplete symptom relief [61]. This article reviews the strong association between diseases of the upper and lower airway [62,63]. Treatment and control of upper airway symptoms is essential for control of asthma symptoms. Control of allergy, eczema, otitis, sinusitis, and viral symptoms result in improved outcomes for asthma patients. Reduction of these asthma triggers and comorbid conditions is also likely to reduce asthma medication requirements while improving symptoms status.

Pathophysiology and diagnosis of asthma

The process of asthma includes swelling, bronchoconstriction, and excess mucus production driven by the redundant nature of the inflammatory process. Untreated or undertreated, this process has the potential to cause airway remodeling and the permanent loss of pulmonary function. It is essential that all health care professionals involved in the care of patients with asthma have as their major goal the treatment and prevention of the inflammatory process.

Fine-scale mapping of type I allergy candidate loci suggests central susceptibility genes on chromosomes 3q, 4q and Xp

BACKGROUND

Type I allergy globally affects an increasing number of individuals with the consequence of considerable personal morbidity and socio-economic costs. Identification of disease susceptibility genes would render enormous medical perspectives in terms of improved diagnosis, treatment and prevention. Like for other complex disorders, achievement of the knowledge necessary depends on confirmation of reported genomic candidate regions.

METHODS

We performed a two-stage fine-scale linkage analysis in 11 selected candidate regions on chromosome 3p, 3q, 4p, 4q, 5q, 6p, 9p, 12q, 12qter, 18q and Xp. We analysed 97 polymorphic markers in 424 individuals from 100 sib-pair families and evaluated the data for five phenotypes: Allergic asthma, atopic dermatitis, allergic rhinitis and total and specific immunoglobulin E.

RESULTS

The highest maximum likelihood scores (MLS) were obtained on chromosomes 3q (MLS = 2.69), 4p (MLS = 2.34), 4q (MLS = 2.75), 6p (MLS = 2.22), 12qter (MLS = 2.15) and Xp (MLS = 2.23). All five phenotypes showed MLS >/= 2 in one or more of the candidate regions.

CONCLUSIONS

Susceptibility genes in the 3q, 4q and Xp regions may play a central role in the inheritance of allergic disease, as positive results were obtained for all five phenotypes in these three regions.

Association studies for asthma and atopic diseases: a comprehensive review of the literature

Hundreds of genetic association studies on asthma-related phenotypes have been conducted in different populations. To date, variants in 64 genes have been reported to be associated with asthma or related traits in at least one study. Of these, 33 associations were replicated in a second study, 9 associations were not replicated either in a second study or a second sample in the same study, and 22 associations were reported in just a single published study. These results suggest the potential for a great amount of heterogeneity underlying asthma. However, many of these studies are methodologically limited and their interpretation hampered by small sample sizes.

Analysis of risk factors for recurrent airway obstruction in North American horses: 1,444 cases (1990-1999)

OBJECTIVE

To identify risk factors for recurrent airway obstruction (RAO) among horses examined at veterinary teaching hospitals in North America.

DESIGN

Retrospective case-control study.

ANIMALS

1,444 horses with RAO and 1,444 control horses examined for other reasons.

PROCEDURE

The Veterinary Medical Database was searched for records of horses in which RAO was diagnosed. A control group was identified by randomly selecting a horse with a diagnosis other than RAO that matched the institution and year of admission for each of the horses with RAO. Information obtained included hospital, admission year and month, age, sex, breed, and discharge status. The association between risk factors and diagnosis of RAO was estimated with logistic regression models.

RESULTS

The risk of RAO increased significantly with age, with horses > or = 7 years old being 6 to 7 times as likely to have RAO as were horses < or = 4 years old. Thoroughbreds were 3 times as likely to have RAO as were ponies. Horses were 1.6 and 1.5 times as likely to be examined because of RAO during winter and spring, respectively, than they were during summer.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that RAO was more likely to be diagnosed in females, horses > or = 4 years old, and Thoroughbreds and that RAO has a seasonal distribution.

Association between interleukin-18 gene polymorphism 105A/C and asthma

BACKGROUND

IL-18 has been shown to exert anti-allergic or allergy-promoting activities, but the existence of genetic polymorphisms in the coding regions of IL-18 gene has not been demonstrated.

OBJECTIVE

The aim of this study was to investigate whether polymorphism is present in the coding regions of the IL-18 gene and, if so, to further analyse the association between polymorphism and asthma in a case-control study.

METHODS

We screened the coding regions of the IL-18 gene for polymorphisms by using PCRsingle-stranded conformation polymorphism and direct sequencing of PCR products, followed by analysis of the association between polymorphism and asthma.

RESULTS

We identified one polymorphism (105A/C) in the coding regions. The frequency of the 105A allele was significantly higher in asthmatic patients than in controls (P<0.01; odds ratio (OR)=1.83 (1.37-2.26)). Significant linkage disequilibrium was observed between the 105A/C and -137G/C polymorphisms in the 5' flanking region of the IL-18 gene (D=0.58, P<0.0001). However, in asthmatic patients the 105A allele was not associated with either total serum IgE or IL-18 levels.

CONCLUSION

The 105A/C polymorphism of the IL-18 gene may be associated with the pathogenesis of asthma.

Competing functions encoded in the allergy-associated F(c)epsilonRIbeta gene

Allergic reactions are triggered via crosslinking of the high-affinity receptor for immunoglobulin E, F(c)epsilonRI. In humans, F(c)epsilonRI is expressed as a tetramer (alphabetagamma(2)) and a trimer (alphagamma(2)). The beta subunit is an amplifier of F(c)epsilonRI surface expression and signaling. Here, we show that as a consequence of alternative splicing, the F(c)epsilonRIbeta gene encodes two proteins with opposing and competing functions. One isoform is the full-length classical beta, the other a novel truncated form, beta(T). In contrast to beta, beta(T) prevents F(c)epsilonRI surface expression by inhibiting alpha chain maturation. Moreover, beta(T) competes with beta to control F(c)epsilonRI surface expression in vitro. We propose that the relative abundance of the products of the beta gene may control the level of F(c)epsilonRI surface expression and thereby influence susceptibility to allergic diseases.

Advances in allergy management

Our understanding of the pathophysiology of allergy has moved to the molecular level, while study of epidemiology and genetics has revealed risks of developing allergies based on environmental and genetic profiles, and pharmacoeconomic data have enabled accurate measurement of the immense burden of allergic disease. These advances in allergy research have affected its management, particularly the search for new antiallergy therapies. New therapies should intervene in the systemic allergy inflammatory cascade and provide clinical efficacy that extends to multiple allergic disease states. In addition, these new therapies should present no additional safety issues, offer improvements over existing therapies, and have an impact on disease-impaired quality of life. In vitro studies show that desloratadine, a new, once-daily, nonsedating, selective histamine H1-receptor antagonist, blocks the systemic allergy cascade at multiple points. Desloratadine 5 mg once daily relieves the symptoms of chronic idiopathic urticaria and of both seasonal (SAR) and perennial allergic rhinitis. In patients with concomitant asthma and SAR, asthma symptoms are relieved and beta2-agonist medication use is decreased by desloratadine. Unlike many other second-generation histamine H1-receptor antagonists, desloratadine provides the added benefit of efficacy against nasal obstruction in SAR. Desloratadine improves quality of life by decreasing the impact of allergic symptoms on sleep and on daily activities.

Genetic evidence for interaction of the 5q31 cytokine locus and the CARD15 gene in Crohn disease

A common haplotype spanning 250 kb in the cytokine gene cluster on chromosome 5q31 has recently been reported to be strongly associated with Crohn disease (CD) in Canadian families. We have replicated this finding by both the transmission-disequilibrium test (TDT) (P=.016) and in a case-control association study (P=.008) in a large European cohort of patients with CD, although the increase in disease risk was small (odds ratio 1.49 for homozygotes, 95% CI 1.11-2.0). No association was detected in families or individuals with ulcerative colitis (UC). Stratification of offspring with CD in the TDT sample by mutation status in the CD susceptibility gene CARD15 showed that the association with the 5q31 risk haplotype was present only in offspring with at least one of the known CARD15 disease susceptibility alleles (P=.044). The 5q31 risk haplotype frequency was 53.1% in unrelated individuals with CD who had one or two CARD15 mutations versus 43.7% in control subjects (P=.0001) but was not significantly elevated in individuals with CD who had no CARD15 mutations (45.4%, P=.41). Kaplan-Meier survival analysis of age at disease onset showed a significantly earlier onset in homozygotes for the 5q31 risk haplotype (P=.0019). These findings suggest that genetic variants at the 5q31 (IBD5) locus may hasten the onset of Crohn disease and cooperate with CARD15 in disease causation.

Atopic asthma and TNF-308 alleles: linkage disequilibrium and association analyses

The association of a tumor necrosis factor -308 allele (TNF2) to asthma has been reported in some studies but not in others. The aim of this study was to test this association in a population recruited on the basis of allergy to Parietaria. In the study population, asthma was positively associated to HLA-DRB1*03 (p = 0.01) and to the haplotype TNF2/DRB1*03 (p = 0.02). In the parent subgroup, the proportion of asthmatics was increased in patients with TNF2 (p = 0.01), but the primary association of asthma was to the haplotype TNF2/DRB1*1104 (p = 0.005). The study population was subdivided according to prick skin test (ST) positivity to Lolium, Parietaria, and D. pteronyssinus. Asthma was associated to HLA-DRB1*03 and to the haplotype TNF2/DRB1*03 (p = 0.0015 and 0.0001, respectively) in patients ST positive to Lolium, and to the haplotype TNF2/DRB1*1104 (p = 0.025) in patients ST positive to Parietaria. The transmission disequilibrium test detected excess transmission of HLA-DRB1*03 and of the haplotype TNF2/DRB1*03 (p = 0.03 and 0.04, respectively) to siblings with asthma and ST positivity to Lolium and of HLA-DRB1*1104 and of the haplotype TNF2/DRB1*1104 (p = 0.04 and 0.015, respectively) to siblings with asthma and ST positivity to Parietaria. Taken together, these observations indicate that the haplotypes TNF2/DRB1*03 and TNF2/*B1*1104 contain alleles controlling atopic asthma in patients with sensitization to Lolium and Parietaria, respectively. This suggests that the association of asthma to TNF2 reflects linkage disequilibrium with genes influencing specific immune response.

Use of multivariate linkage analysis for dissection of a complex cognitive trait

Replication of linkage results for complex traits has been exceedingly difficult, owing in part to the inability to measure the precise underlying phenotype, small sample sizes, genetic heterogeneity, and statistical methods employed in analysis. Often, in any particular study, multiple correlated traits have been collected, yet these have been analyzed independently or, at most, in bivariate analyses. Theoretical arguments suggest that full multivariate analysis of all available traits should offer more power to detect linkage; however, this has not yet been evaluated on a genomewide scale. Here, we conduct multivariate genomewide analyses of quantitative-trait loci that influence reading- and language-related measures in families affected with developmental dyslexia. The results of these analyses are substantially clearer than those of previous univariate analyses of the same data set, helping to resolve a number of key issues. These outcomes highlight the relevance of multivariate analysis for complex disorders for dissection of linkage results in correlated traits. The approach employed here may aid positional cloning of susceptibility genes in a wide spectrum of complex traits.