Allelic association of gene markers on chromosomes 5q and 11q with atopy and bronchial hyperresponsiveness

Interleukin-4 (IL4) and Interleukin-4 receptor (IL4RA) polymorphisms in asthma: a case control study

Background

IL4/IL4RA pathway plays an important role in atopy and asthma. Different polymorphisms in IL4 and IL4RA genes have been described. Particularly, -33C>TIL4 and 576Q>RIL4RA SNPs have been independently associated to atopy and asthma. The purpose of this study was to analyse these polymorphisms in a population of patients with a well-characterized asthma phenotype.

Methods

A total of 212 unrelated Caucasian individuals, 133 patients with asthma and 79 healthy subjects without symptoms or history of asthma or atopy and with negative skin prick tests were recruited. Lung function was measured by spirometry and asthma was specialist physician-diagnosed according to the ATS (American Thoracic Society) criteria and classified following the GINA (Global Initiative for Asthma) guidelines. Skin prick tests were performed according to EAACI recommendations. -33C>TIL4 was studied with TaqMan assay and 576Q>RIL4RA by PCR-RFLP technique. Hardy-Weinberg equilibrium was analysed in all groups. Dichotomous variables were analysed using χ², Fisher exact test, Monte Carlo simulation test and odds ratio test. To model the effects of multiple covariates logistic regression was used.

Results

No statistically significant differences between the group of patients with asthma and the controls were found when the allele and genotype distribution of -33C>TIL4 and 576Q>RIL4RA polymorphisms were compared. However, the T allele of the -33C>TIL4 SNP was more frequent in patients with persistent asthma. Multivariate analysis adjusted for age and sex confirmed that carriers of allele T had an increased risk of persistent asthma (OR:2.77, 95%CI:1.18–6.49; p = 0.019). Analysis of combination of polymorphisms showed that patients carrying both the T allele of -33C>TIL4 and the A allele of 576Q>RIL4RA had an increased risk of asthma. This association was particularly observed in persistent asthma [Fisher's p value = 0.0021, Monte Carlo p value (after 10⁴ simulations) = 0.0016, OR:3.39; 95% CI:1.50–7.66].

Conclusion

Our results show a trend of association between the genetic combination of the T allele of -33C>TIL4 and the A allele of 576Q>RIL4RA with asthma. This genetic variant was more frequently observed in patients with persistent asthma. As long as this study was performed in a small population, further studies in other populations are needed to confirm these results.

Genetics and the Dutch Hypothesis

BACKGROUND

Increasingly, molecular genetic techniques are being used to improve our understanding of a number of common late onset complex disorders, such as hypertension, Alzheimer's disease and noninsulin dependent diabetes mellitus. Molecular genetic approaches have the potential to yield new information about disease pathogenesis that may be of great importance for the development of future treatments.

AIMS

This review discusses the evidence for a genetic contribution to the development of chronic obstructive pulmonary disease (COPD) and specifically focuses on the hypothesis that asthma and COPD share some pathogenic mechanisms as originally proposed in 1960 in a theory that has since become known as the Dutch Hypothesis. In particular we will review the evidence from molecular genetics, both in support of and against the theory.

The association between glutathione S-transferase P1, M1 polymorphisms and asthma in Taiwanese schoolchildren

STUDY OBJECTIVES

Genetic polymorphisms in the glutathione S-transferase P1 gene (GSTP1) and the glutathione S-transferase M1 gene (GSTM1) have been implicated as risk factors for asthma. However, their roles in asthma pathogenesis and the interaction between these two genes have not been extensively investigated. This study, therefore, examined the relationship among GSTP1 and GSTM1 genotypes and childhood asthma, and evaluated their gene-gene interactions.

SETTING

The population from three southern Taiwan communities of a 2001 national survey.

SUBJECTS AND METHODS

Two hundred sixty-six fourth-grade to ninth-grade schoolchildren were recruited for oral mucosa samplings based on questionnaire information. Polymerase chain reaction-based assays were performed to determine GSTP1 and GSTM1 genotypes among asthmatic subjects and nonasthmatic control subjects. Multiple logistic regression was used to adjust for potential confounding factors.

RESULTS

All of the participants were homozygous at the GSTP1 Ala-114 locus. After controlling for age, sex, and atopic eczema, compared with participants carrying any Val-105 allele, children who were homozygotic for GSTP1 Ile-105 had a significantly increased risk of physician-diagnosed asthma (adjusted odds ratio [adjOR], 1.94; 95% confidence interval [CI], 1.08 to 3.59). A positive risk for childhood asthma was also noted on the GSTM1 null genotype but did not reach statistical significance (adjOR, 1.37; 95% CI, 0.80 to 2.38). Among children with GSTM1 present genotypes, GSTP1-105 polymorphisms were associated with the increased risk of asthma. However, the reduced and statistically insignificant asthma risk was observed among those with GSTM1 null genotype.

CONCLUSIONS

We concluded that GSTP1-105 was a predictor for childhood asthma, whereas GSTM1 polymorphism might modify the risk. Our study also suggested a competitive effect for homozygous GSTP1 Ile-105 and GSTM1 null genotypes on childhood asthma.

Lack of association of glutathione S-transferase P1 Ile105Val polymorphism with aspirin-intolerant asthma

BACKGROUND

Glutathion S-transferase P1 (GSTP1), the abundant isoform of glutathione S-transferase in lung epithelium, plays an important role in cellular protection against oxidative stress and toxic foreign chemicals. GSTP1 (Ile105Val) polymorphism has been reported to be associated with asthma related phenotypes such as atopy and bronchial hyperresponsiveness. Therefore we investigated whether this polymorphism may be associated with the development of aspirin-intolerant asthma (AIA).

METHODS

GSTP1 Ile105Val polymorphism was determined using a single based extension method in 88 AIA subjects and compared to 154 aspirin-tolerant asthma (ATA) subjects and 119 normal healthy controls (NC) recruited from the Korean population.

RESULTS

No significant differences in allele and genotype frequencies of the GSTP1 Ilel105Val polymorphism were observed in the three groups (p>0.05). However, minor G allele frequency of the GSTP1 Ilel105Val polymorphism in AIA group (16.5%) tended to be lower than in the NC group (20.6%).

CONCLUSION

These results suggest a lack of association of the GSTPI Ilel105Val gene polymorphism with AIA phenotype in the Korean population [word count: 159].

The Quintiles Prize Lecture 2004. The identification of the adenosine A2B receptor as a novel therapeutic target in asthma

Adenosine is a powerful bronchoconstrictor of asthmatic, but not normal, airways. In vitro studies on isolated human mast cells and basophils revealed that adenosine and selective analogues augmented inflammatory mediator release from mast cells by stimulating A(2) receptors. Pharmacological blockade of mast cell mediator release in vivo also attenuated adenosine-induced bronchoconstriction, as did theophylline, by adenosine A(2) receptor antagonism. Further in vitro studies revealed that the asthmatic response to adenosine is likely to be mediated via the A(2B) subtype which is selectively antagonised by enprofylline. Studies in animal models, especially mice, have shown a close synergistic interaction between adenosine, Th2 and airway remodelling responses. The recent description of A(2B) receptors on human airway smooth muscle cells that mediate cytokine and chemokine release and induce differentiation of fibroblasts into myofibroblasts strengthens the view that adenosine maybe more than an inflammatory mediator in asthma but also participates in airway wall remodelling in this disease. These data have provided a firm basis for developing adenosine A(2B) receptor antagonists as a new therapeutic approach to this disease.

Glutathione S-transferase P1 gene polymorphism and air pollution as interactive risk factors for childhood asthma

BACKGROUND

Polymorphisms at the glutathione S-transferase (GST) P1 locus were associated with asthma-related phenotypes and bronchial hyper-responsiveness.

OBJECTIVE

This study investigated whether GSTP1 genotypes and outdoor air pollution were interactive risk factors on childhood asthma.

METHODS

Four hundred and thirty-six subjects were recruited for oral mucosa samplings from 2853 fourth- to ninth-grade schoolchildren from three districts with different air pollution levels in southern Taiwan. PCR-based assays were performed by oral mucosa DNA to determine GSTP1 genotypes. We also conducted a nested case-control study comprising 61 asthmatic children and 95 controls confirmed by International Study of Asthma and Allergies in Childhood questionnaire results and methacholine challenge test. Multiple logistic regression was used to adjust for potential confounding factors.

RESULTS

All participants were homozygous at the Ala-114 locus. Although only a marginally significant association existed between the frequency of homozygosity at the Ile-105 locus and asthma when air pollution was not considered, we found a significant gene-environmental interaction between GSTP1-105 alleles and air pollution after adjusting for confounders (P=0.035). Specifically, we found that compared with participants carrying any Val-105 allele in low air pollution, those who are Ile-105 homozygotes in high air pollution district had a significantly increased risk of asthma (adjusted odds ratio (AOR)=5.52, 95% confidence interval (CI)=1.64-21.25). Compared with participants carrying any Val-105 allele, in high air pollution district, children with Ile-105 homozygotes had a significantly increased risk of asthma (AOR=3.79, 95% CI=1.01-17.08), but those who carried two Ile-105 alleles in low or moderate air pollution districts did not show similar tendencies. The risk of asthma also revealed a clear dose-response relationship with outdoor air pollution in children with Ile-105 homozygotes.

CONCLUSION

Our result suggests a gene-environmental interaction between GSTP1-105 genotypes and outdoor air pollution on childhood asthma.

Airway allergen exposure stimulates bone marrow eosinophilia partly via IL-9

Background

Interleukin (IL)-9 is a Th2-derived cytokine with pleiotropic biological effects, which recently has been proposed as a candidate gene for asthma and allergy. We aimed to evaluate the therapeutic effect of a neutralizing anti-IL-9 antibody in a mouse model of airway eosinophilic inflammation and compared any such effect with anti-IL-5 treatment.

Methods

OVA-sensitized Balb/c mice were intraperitoneally pretreated with a single dose (100 μg) of an anti-mouse IL-9 monoclonal antibody (clone D9302C12) or its vehicle. A third group was given 50 μg of a monoclonal anti-mouse IL-5 antibody (TRFK-5) or its vehicle. Animals were subsequently exposed to OVA on five days via airways. Newly produced eosinophils were labelled using 5-bromo-2'-deoxyuridine (BrdU). BrdU⁺ eosinophils and CD34⁺ cell numbers were examined by immunocytochemistry. After culture and stimulation with OVA or PMA+IC, intracellular staining of IL-9 in bone marrow cells from OVA-exposed animals was measured by Flow Cytometry. The Mann-Whitney U-test was used to determine significant differences between groups.

Results

Anti-IL-9 significantly reduced bone marrow eosinophilia, primarily by decrease of newly produced (BrdU⁺) and mature eosinophils. Anti-IL-9 treatment also reduced blood neutrophil counts, but did not affect BAL neutrophils. Anti-IL-5 was able to reduce eosinophil numbers in all tissue compartments, as well as BrdU⁺ eosinophils and CD34⁺ progenitor cells, and in all instances to a greater extent than anti-IL-9. Also, FACS analysis showed that IL-9 is over-expressed in bone marrow CD4⁺ cells after allergen exposure.

Conclusions

Our data shows that a single dose of a neutralizing IL-9 antibody is not sufficient to reduce allergen-induced influx of newly produced cells from bone marrow to airways. However, in response to allergen, bone marrow cells over-express IL-9. This data suggest that IL-9 may participate in the regulation of granulocytopoiesis in allergic inflammation.

The CD14 C-159T polymorphism is not associated with asthma or asthma severity in an Australian adult population

BACKGROUND

CD14 functions as a multifunctional receptor for bacterial cell wall components including endotoxin and lipopolysaccharide and is likely to play a role in the polarisation of T lymphocytes into Th1 and Th2 subsets, thereby influencing the cytokine profile and subsequent IgE production in response to antigen/allergen contact in allergic phenotypes. A functional C-159T polymorphism has been described in the promoter region of the gene and has been associated with increased gene expression, atopy, and non-atopic asthma in different ethnic populations. A study was undertaken to examine the association between the C-159T polymorphism and asthma, asthma severity, and atopy in a large Australian white population.

METHODS

PCR-RFLP analysis was used to characterise the C-159T polymorphism in mild (n = 264), moderate (n = 225) and severe (n = 79) asthmatic patients and non-asthmatic controls (n = 443), including atopic (n = 688) and non-atopic (n = 323) individuals. Association analyses were performed using chi(2) tests.

RESULTS

There was no association between the polymorphism and asthma (p = 0.468) or asthma severity (p = 0.727), and only a very weak association with atopy (p = 0.084). A meta-analysis of all studies conducted to date revealed similar genotypic frequencies in white ethnic populations and confirmed that there was no overall association with atopy (p = 0.52) or asthma (p = 0.23), although there was significant between study heterogeneity (p = 0.01).

CONCLUSIONS

This study confirms that there is no association between the CD14 C-159T polymorphism and asthma or asthma severity and a weak association between this polymorphism and atopy in an adult population.

Maternal glutathione S-transferase GSTP1 genotype is a specific predictor of phenotype in children with asthma

Maternal factors are known to influence the heritability and expression of asthma and atopy. We report the association of maternal, paternal and proband GSTP1 genotype with lung function in 145 Caucasian children with asthma. GSTP1 Val105/Val105 and Ala114/Val114 genotypes in the child were associated with non-significant increases in lung function (forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and the FEV1/FVC ratio). Paternal genotype had no influence on lung function in the child. In contrast, maternal GSTP1 Val105/Val105 genotype was significantly associated with offspring lung function and was strongly predictive of FEV1/FVC (Val105/Val105 105.2%, Ile105/Val105 and Ile105/Ile105 97.9% p=0.006) and maternal GSTP1 Ala114/Val114 genotype was associated with significantly higher FEV1 (Ala114/Val114 109.0%, Ala114/Ala114 99.0% p=0.008), and FEV1/FVC ratios (Ala114/Val114 104.1%, Ala114/Ala114 98.2% p=0.04). The associations between maternal GSTP1 Val105/Val105 genotype and FEV1/FVC and maternal GSTP1 Ala114/Val114 genotype and FEV1 remained significant (p=0.003 and p=0.007) after correction for child and maternal atopic status, passive smoke exposure, smoking during pregnancy, individual and paternal GSTP1 genotype and was independent of transmission to the child. These data support the hypothesis that maternal GSTP1 genotype can act as a specific risk factor which has ex utero consequences for children with asthma. As a child's genotype is not independent of maternal genotype, effects seen in candidate gene studies may be due at least in part to this phenomenon.

Decreased expression of uteroglobin-related protein 1 in inflamed mouse airways is mediated by IL-9

Uteroglobin-related protein 1 (UGRP1) is a secretory protein, highly expressed in epithelial cells of airways. Although an involvement of UGRP1 in the pathogenesis of asthma has been suggested, its function in airways remains unclear. In the present study, a relationship between airway inflammation, UGRP1 expression, and interleukin-9 (IL-9), an asthma candidate gene, was evaluated by using a murine model of allergic bronchial asthma. A severe airway inflammation accompanied by airway eosinophilia and elevation of IL-9 in bronchoalveolar lavage (BAL) fluids was observed after ovalbumin (OVA) challenge to OVA-sensitized mice. In this animal model of airway inflammation, lung Ugrp1 mRNA expression was greatly decreased compared with control mice. A significant inverse correlation between lung Ugrp1 mRNA levels and IL-9 levels in BAL fluid was demonstrated by regression analysis (r = 0.616, P = 0.023). Immunohistochemical analysis revealed a distinct localization of UGRP1 in airway epithelial cells of control mice, whereas UGRP1 staining was patchy and faint in inflamed airways. Intranasal administration of IL-9 to naive mice decreased the level of Ugrp1 expression in lungs. These findings suggest that UGRP1 is downregulated in inflamed airways, such as allergic asthmatics, and IL-9 might be an important mediator for modulating UGRP1 expression.

Glutathione-S-transferase gene polymorphisms (GSTT1, GSTM1, GSTP1) as increased risk factors for asthma

OBJECTIVES

Asthma is a complex multifactorial disease with an obvious genetic predisposition, immunological aberration, and involvement of noxious environmental factors. Polymorphisms of the glutathione-S-transferase (GST) genes are known risk factors for some environmentally-related diseases. In the present study, the hypothesis that polymorphisms in the GSTT1, GSTM1 and GSTP1 genes are associated with atopic and nonatopic asthma was examined.

METHODOLOGY

The study population consisted of 103 unrelated healthy individuals and 101 patients with bronchial asthma (64 atopic, 37 nonatopic). Asthma was diagnosed according to the American Thoracic Society statement. Genotyping of polymorphisms in the GSTT1, GSTM1 and GSTP1 genes was performed using real time polymerase chain reaction with a Light Cycler instrument and hybridization probes in combination with the Light Cycler DNA master hybridization probes kit.

RESULTS

Patients with atopic asthma (34.4%) had a higher prevalence of the GSTT1 null genotype than the nonatopic asthma patients (13.5%; OR = 3.83; 95% CI, 1.24-11.78). Asthma patients (63.4%) had a higher prevalence of the GSTM1 null genotype than the control group (40.8%; OR = 2.34; 95% CI, 1.31-4.20). Subjects with the GSTP1 homozygous Val/Val genotype had a 3.55-fold increased risk of having atopic asthma compared to nonatopic asthma (OR = 3.55; 95% CI, 1.10-12.56).

CONCLUSIONS

These results suggest that the GSTT1 and GSTM1 null genotypes and the GSTP1 Val/Val polymorphism may play important roles in asthma pathogenesis. It is possible that intermediate electrophilic metabolites, arising in the first phase of detoxification, are not metabolized by GST enzymes in asthmatic patients and are not excreted. These intermediate metabolites may damage cells and generate oxidative stress, and so contribute to the pathogenesis of asthma.

A comprehensive evaluation of IL4 variants in ethnically diverse populations: association of total serum IgE levels and asthma in white subjects

BACKGROUND

The role of variation in the IL4 gene in asthma and allergy susceptibility is controversial. This cytokine is important in IgE isotype switching and the regulation of allergic inflammation; however, published studies have not delineated the specific role of variation in this gene in allergic disorders.

OBJECTIVE

We sought to identify single nucleotide polymorphisms (SNPs) in IL4 and to evaluate the association of SNPs and haplotypes with asthma and allergic phenotypes (total serum IgE) in white, African American, and Hispanic asthmatic populations.

METHODS

Sixteen individuals were resequenced, and 19 SNPs were identified; 2 novel and 17 SNPs were previously reported. Eleven of the SNPs were used to evaluate association in the 3 groups.

RESULTS

Nine polymorphisms were associated with total serum IgE levels in white subjects (.0012 < or = P < or =.034), and 5 of these were also associated with asthma in this population (.010 < or = P < or =.031). Three common haplotypes were observed, and all were associated with either high or low serum IgE levels in white subjects (.00008 < or = P < or =.004). Inspection of the haplotypes revealed that 3017 G/T in intron 2 was the only SNP concordant with serum IgE levels (G allele with lower levels and T allele with higher levels).

CONCLUSIONS

After a comprehensive genetic evaluation, our data suggest that the 3017 G/T variant or the haplotype it identifies influences IL4's ability to modulate total serum IgE levels. Inconsistencies with previously reported IL4 associations might be due to population differences in allele frequencies, the extent of linkage disequilibrium with this SNP or haplotype, or both.

Genetic variants of FcepsilonRIbeta and Il-4 and atopy in a Polish population

BACKGROUND

Atopy results from the interaction between genetic and environmental factors. The aim of our study was to clarify the association between the FcRIint2 polymorphic variant, the Glu237Gly mutation in exon 7 of FcepsilonRIbeta and (-590 C/T) Il-4 gene promoter polymorphism with atopy in a randomized Polish sample.

SUBJECTS AND METHODS

Unrelated subjects aged 18-45 years who were residents of an urban area (Lodz, Poland) were included in the study: 98 patients with asthma and/or allergic rhinitis, and 87 non-atopic, non-asthmatic controls. We used common criteria for atopy and asthma. Atopic status was determined by positive skin prick tests (SPT) and IgE levels. The severity of asthma was assessed in spirometric measurements; SPTs to house dust mite (HDM) and mixed grass pollen (MGP) were performed. Total and specific IgE were measured in each subject. Genotypic analysis was performed by PCR for FcRIint2 and (590 C/T) Il-4 gene promoter polymorphism and ARMS-PCR was performed for the Glu237Gly mutation.

RESULTS

We found a statistically significant association between atopy and FcRIint2 variant polymorphism (OR = 2.96), a correlation between positive skin prick tests to MGP and raised MGP-specific IgE concentrations in patients bearing this variant (OR = 4.0). We did not observe that the FcRIint2 variant was associated with positive SPTs to HDM or high levels of HDM-specific IgE (OR = 1.0). The intronic variant of FcepsilonRIbeta was strongly correlated with elevated total serum IgE (OR = 4.74). No statistically significant association was found between atopy and the Glu237Gly mutation of FcepsilonRIbeta(OR = 1.36) or (-590 C/T) Il-4 gene promoter polymorphism (OR = 0.88).

CONCLUSIONS

The results suggest that FcRIint2 polymorphism is related to atopy and may influence its development.

Development and validation of school-based asthma and allergy screening questionnaires in a 4-city study

BACKGROUND

Asthma and allergies are commonly undiagnosed in children. Schools provide settings for potentially accessing almost all children for asthma and allergy screening.

OBJECTIVE

To evaluate the feasibility and validity of using a questionnaire-based screening tool to identify undiagnosed asthma and respiratory allergies in children in kindergarten to grade 6.

METHODS

A student questionnaire (SQ) and a parent questionnaire (PQ) were developed, administered in 4 diverse communities, and validated against standardized clinical assessments. Children without diagnosed asthma and representing a range of symptoms participated in a validation study that consisted of independent, standardized, clinical assessments. Sensitivity, specificity, and predictive values for questionnaire items were evaluated against expert consensus designations.

RESULTS

A total of 190 children (age range, 7-13 years) completed the validation study. Affirmative responses to individual questions from either the SQ or PQ regarding asthma and allergy were modestly to moderately predictive of the clinical assessments (odds ratios, generally 2.5-5.0). When considering a positive asthma screen as affirmative responses to 3 of the best 7 SQ asthma questions, the odds ratio for asthma was 9.3 (95% confidence interval, 4.1-21.1), with 80% sensitivity and 70% specificity. Considering the allergy screen as positive based on affirmative response to either of the 2 SQ allergy questions yielded 81% sensitivity and 42% specificity.

CONCLUSIONS

Either a 9-item SQ or a 10-item PQ can be used in diverse settings to screen for asthma and respiratory allergies. The SQ, obtained by directly screening students, may provide a sensitive approach for detecting children with previously undiagnosed asthma and allergies.

An update on bronchopulmonary dysplasia: is there a relationship to the development of childhood asthma?

There appears to be some interesting commonalities between asthma and BPD. The prevalence of both conditions is on the rise, both conditions tend to cluster in families, and they share wheezing phenotypes, i.e., mild-moderate reversible airway obstruction and a similar degree of response to pharmacological provocation. Furthermore, significant overlap exists with regard to the presence of elevated concentrations of airway inflammatory mediators concurrent with reduced levels of anti-inflammatory activity, in serum and BAL fluid, as well as histological evidence for airway 'remodelling'. Both BPD and asthma are characterized by increased smooth muscle contraction, and in asthma, the smooth muscle may be involved in the primary development of the asthmatic phenotype. Since wheezing is a common finding among children with BPD, an interesting question is whether BPD is a phenotypic variant of asthma?

Involvement of IL-9 in the bronchial phenotype of patients with nasal polyposis

BACKGROUND

Nasal polyposis (NP) is frequently associated with asthma. In this disease, asymptomatic bronchial hyperresponsiveness (BHR) is thought to precede the development of asthma. IL-9 and its receptor have been reported as candidate genes for asthma and to be associated with BHR.

OBJECTIVE

The objective of this study was to assess the contribution of 11-9 to the pathogenesis of BHR in NP by comparing the expression of IL-9 and its receptor in bronchial biopsy specimens from three groups of patients with NP: NP without BHR, NP with asymptomatic BHR, and NP with BHR and asthma.

METHODS

Bronchial biopsy specimens were examined in terms of cellular infiltration and in terms of expression of IL-9 protein and mRNA as well as of its receptor by using immunohistochemistry and in situ hybridization.

RESULTS

Patients with NP with asthma as compared with the two other groups exhibited an increased bronchial infiltration of basophils, eosinophils, and T cells that correlated with the asthma score. The two groups of patients with NP with BHR showed an increased expression in IL-9 protein and mRNA as well as an increase in the expression of IL-9R mRNA at the epithelial level. These modifications were inversely correlated with the airway responsiveness to methacholine, producing a 20% fall in FEV1. There was a close association between IL-9+ cells, IL-5 mRNA expression, and eosinophil infiltration that correlated with each other.

CONCLUSIONS

These results suggest an important role for IL-9 in the pathogenesis of BHR and a causal relation between IL-9 and the development of bronchial eosinophilia in asthma.

Molecular analysis of sequence variants in the Fcepsilon receptor I beta gene and IL-4 gene promoter in Italian atopic families

BACKGROUND

The genetic variants in the Fcepsilon receptor I beta gene (Glu237Gly) and the T allele of the (C590T) polymorphism of interleukin (IL)-4 gene promoter were reported to be associated with atopy. But the data of the studies in different populations are contrasting with one another.

METHODS

A group of 25 Italian nuclear families were studied. In each family at least two allergic subjects were present. The allergic children were 65 and the allergic relatives were 35. One hundred and three nonallergic unrelated controls included outpatiens with no history of atopy. The (C590T) promoter polymorphism of the IL-4 and the genetic variant Glu237Gly of Fcepsilon RI beta genes were analysed by the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

A significant difference was observed in the genotype frequency at codon 237 of the Fcepsilon RI beta gene between allergic children and nonatopic control (P < 0.01) and in the allergic relatives (P < 0.001). In the children, the Glu237Gly polymorphism was also associated with elevated circulating levels of immunoglobulin E. The -590C/T allele of IL-4 promoter gene showed no association with atopy.

CONCLUSIONS

In our study, the Glu237Gly polymorphism of the Fcepsilon RI beta gene was associated with atopy. Our results have not pointed out an association between the (C590T) promoter polymorphism of the IL-4 gene and atopy. These data suggest the potential role of the Fc RI beta gene in the development of the allergy.

Nasal mucosal gene expression in patients with allergic rhinitis with and without nasal polyps

BACKGROUND

Nasal polyps are a common problem that is difficult to diagnose and treat, in part because the cause of nasal polyposis is unknown. Although information on the pathogenesis of polyposis is lacking, there are reports suggesting that a genetic predisposition underlies this disorder.

OBJECTIVE

We sought to better understand the basis of nasal polyposis associated with allergic rhinitis. We hypothesize that the expression of unique genes is associated with the nasal polyposis phenotype.

METHODS

We examined 12000 human genes transcribed in the nasal mucosa of patients with allergic rhinitis with and without nasal polyps. Biopsy specimens of the mucosa of patients with and without polyps were obtained after the patients refrained from the use of topical or systemic steroid therapy for 2 weeks.

RESULTS

Thirty-four genes were differentially expressed between the patient groups, including those for inflammatory molecules and putative growth factors. The greatest differential expression identified by the array analysis was for a group of genes associated with neoplasia, including mammaglobin, a gene transcribed 12-fold higher in patients with polyps compared with control patients with rhinitis alone. Quantitative RT-PCR confirmed this differential expression and documented that the number of mammaglobin mRNA copies is actually 64-fold greater in tissues of patients with polyps versus control patients. The specificity of mammaglobin protein expression was evaluated by means of immunohistochemistry, which showed specific staining in nasal polyp mucosal goblet cells only in patients with polyps.

CONCLUSION

These data suggest that nasal polyposis involves deregulated cell growth, using gene activation in some ways similar to a neoplasm. In addition, mammaglobin, a gene of unknown function associated with breast neoplasia, might be related to polyp growth.

The association of maternal but not paternal genetic variation in GSTP1 with asthma phenotypes in children

Maternal factors including atopy and smoking during pregnancy are associated with asthma risk during childhood. Suggested mechanisms include transmission of specific maternal alleles and maternal influences on the intrauterine environment. We have previously shown that polymorphism in glutathione S-transferase, GSTP1 is associated with airway hyperresponsiveness (AHR) and atopy in adults. We now hypothesise that GSTP1 genotypes in the mother and child, but not the father, mediate asthma phenotypes in the child. One hundred and forty-five Caucasian families were recruited via an asthmatic proband aged 7-18 years. Atopy and asthma were assessed using a questionnaire, skin prick testing, serum IgE, spirometry and methacholine challenge (PC20, dose-response slope--DRS). GSTP1 genotyping was determined using PCR. GSTP1 Val105/Val105 genotype in the child was associated with a reduced risk of atopy (P = 0.038) and AHR (PC20, P = 0.046; DRS, P = 0.032). In mothers (P = 0.014) but not fathers (P = 0.623), Val105/Val105 was associated with a reduced risk of AHR in the child. We have identified, for the first time, an association between maternal genotype and the child's asthma phenotype that appears not to be due to transmission of specific maternal alleles. This preliminary data supports the view of in utero effects of maternal genotype and adds new insights into the possible mechanisms by which maternal factors may influence development of childhood asthma.

A complete screening of the IL4 gene: novel polymorphisms and their association with asthma and IgE in childhood

BACKGROUND

IL-4, a cytokine with immunomodulatory functions, is involved in the upregulation of IgE production characteristic of asthma and allergy. Thus far, 2 single nucleotide polymorphisms (SNPs) in the promoter (C-589T) and 5' untranslated region (C-33T) of the IL4 gene have been identified. Polymorphism C-589T was reported to influence total serum IgE levels and bronchial hyperresponsiveness. However, no study has investigated the putative existence of further SNPs in exons, introns, and flanking regions of the IL4 gene.

OBJECTIVE

A complete screening of the IL4 gene and its flanking regions for new polymorphisms was performed. Large-scale association studies in 1120 German schoolchildren were conducted to determine the effect of all polymorphisms present in the IL4 gene on the phenotypic expression of atopic diseases.

METHODS

Denaturing HPLC and standard sequencing techniques were performed to detect novel polymorphisms in 33 unrelated subjects unselected for atopic diseases. Linkage disequilibrium was assessed for all polymorphisms in the IL4 gene, and association studies were performed.

RESULTS

A total of 16 polymorphisms were identified in the IL4 gene, 14 of which were not reported previously. The pattern of linkage disequilibrium observed in IL4 could not be explained by physical distance. A significant association between a cluster of polymorphisms in strong linkage disequilibrium with each other and a physician's diagnosis of asthma and total serum IgE levels was found.

CONCLUSION

These results indicate a possible involvement of SNPs in the IL4 gene in the development of asthma and the regulation of total serum IgE.

Mouse model of airway remodeling: strain differences

We found that continuous eosinophilic inflammation after repeated antigen instillation into the nose was observed only in A/J mice, not in three other strains. Histologic analysis of tissues from A/J mice revealed features typical of airway remodeling, i.e., airway wall thickening and increased collagen depositions were observed after 12 weeks' antigen exposure. Persistent airway hyperresponsiveness (AHR) was observed in chronically antigen-exposed A/J mice. Eosinophilic inflammation, collagen deposition, and airway wall thickening were all less marked in BALB/c mice than in A/J mice, and no AHR was observed in the former strain. In C57BL/6 and C3H/HeJ mice, eosinophilic inflammation, airway wall thickening, and AHR were not observed at all, although slightly increased collagen deposition was observed. Thus, we found that these changes were strain-dependent. On the other hand, in A/J mice inhalational antigen challenge after ovalbumin/alum immunization led only to a transient increase in eosinophils and to less airway wall thickening, indicating the importance of the protocol used. Use of A/J mice and giving antigen by instillation via the nose is to be recommended for studies of the mechanisms underlying asthma. In particular, useful qualitative and quantitative information relating to the structural and histologic changes in the lungs may be obtainable using this model.

Gene polymorphisms within the immune system that may underlie drug allergy

Drug allergy encompasses a broad spectrum of different diseases. It occurs in some individuals, whereas it does not occur in many others. This suggests, among others, the involvement of hereditary factors, and thus of gene polymorphisms. Since drug metabolising enzymes as well as the immune system itself may be responsible for drug allergy, gene polymorphisms are relevant in both systems. While already some information exists on gene polymorphisms of drug metabolising enzymes that result in drug allergy, little information is available on gene polymorphisms within the immune system that result in such allergy. This review sets out to provide an avenue for future research aimed at discovering such polymorphisms. To this end, immune mechanisms that underlie drug allergy will be discussed. A pivotal mechanism underlying several types of drug allergy, immediate-type (type I) hypersensitivity, is also a hallmark of asthma, and therefore drug allergy and asthma share a range of candidate genes. Research on asthma has come relatively far in establishing associations of disease with polymorphisms in these genes. Therefore, these polymorphisms and their associations with asthma will be discussed. These studies on asthma provide us with lessons on how to conduct such studies on drug allergy.

The C-159T polymorphism in the CD14 promoter is associated with serum total IgE concentration in atopic Chinese children

Activation of macrophages through CD14 by microbes is crucial in inducing immunity by type 1 T helper cells. A C-to-T polymorphism at position -159 of CD14 was associated with serum total IgE level in Caucasians but not in Japanese subjects. The objective of this study is to determine whether this polymorphic marker is associated with atopy and asthma phenotypes in Chinese children. Restriction fragment length polymorphism was used to characterize CD14/-159 genotypes. Microparticle immunoassay was used to measure serum total IgE level; fluorescent enzyme immunoassay was performed to measure serum concentrations of specific IgE to aeroallergens; and enzyme-linked immunosorbent assay was used to measure serum levels of soluble CD14 (sCD14). Lung function in asthmatics was assessed by spirometry. Two hundred and fifty-eight patients and 92 control children were recruited. Their mean serum total IgE concentrations were 331 and 74 kIU/l, respectively (p < 0.0001). Atopy, defined as the presence of at least one allergen-specific IgE in serum, was found in 220 (85%) patients and in 41 (45%) controls (p < 0.0001). Serum sCD14 levels were significantly associated with CD14/-159 genotypes (p = 0.004). Atopic subjects with CC genotype in CD14/-159 had the highest serum total IgE levels compared with CT and TT genotypes, with the respective mean values being 661, 427 and 380 kIU/l (p = 0.015). Similarly, a higher proportion of subjects with CC genotype had increased serum total IgE concentration (p = 0.039). This polymorphic marker was not associated with asthma or aeroallergen sensitization in our cohort. Our results suggest that the C-159T of CD14 was associated with serum total IgE concentration in atopic Chinese children.

Interleukin-9 induces mucous cell metaplasia independent of inflammation

Interleukin-9 (IL-9) has been strongly implicated in the pathogenesis of asthma, including the overproduction of mucus, in humans and in animal models. We evaluated the inflammatory changes associated with the upregulation of mucus production by examining the time course of inflammation after daily intratracheal IL-9 administration to naive C57Bl6 mice for 9 d. IL-9 induced an asthmatic phenotype, which in general took several days to develop, as assessed by the measurement of airway hyperresponsiveness, pulmonary inflammation, and serum immunoglobulin E. However, within 24 h of a single dose of IL-9, muc5ac mRNA upregulation occurred, and increased numbers of periodic acid Schiff/Alcian blue-positive mucous cells appeared. This response occurred before the development of an inflammatory cell influx and was the result of epithelial metaplasia. It seemed that IL-9 evoked mucous cell metaplasia independent of IL-13 because mRNA tissue evaluation indicated that muc5ac upregulation preceded any increase in IL-13 mRNA expression or detectable levels of IL-13 in the brochoalveolar lavage fluid. Therefore, the upregulation of IL-13 by IL-9 may be responsible for the amplification of mucus production but is not required for its initiation. IL-9 seems to directly stimulate mucous cell metaplasia without the requirement of inflammatory cell influx.

Chronic obstructive pulmonary disease is associated with the -1055 IL-13 promoter polymorphism

IL-13 is strongly implicated in the development of asthma and chronic obstructive pulmonary disease (COPD). We previously identified an IL-13 promoter polymorphism (-1055 C to T) that is associated with allergic asthma. We now report an increased frequency of the -1055 T allele in COPD patients compared to healthy controls (P=0.002) and compared to a second control group consisting of smoking individuals with normal lung function (P=0.01). A closely linked IL-13 exon polymorphism is present at normal allelic frequencies (P=0.3 and 0.4, respectively). In addition, we observed a normal distribution of two IL-4 polymorphisms at positions -590 and +33 (P=0.2 and 0.9, respectively). These results could implicate a functional role for the IL-13 promoter polymorphism in the enhanced risk to develop COPD.

Asthma

Asthma is one of the commonest chronic diseases of affluent societies. The striking increase in prevalence of asthma over recent decades and the rarity of this disease in less affluent populations confirms the importance of environmental factors in the cause of asthma--although which environmental factors are responsible is still not clear. Family studies show that genetic factors are also important in determining individual susceptibility to asthma, with results of genetic studies suggesting that there are many genes with moderate effects rather than a few major genes. Asthmatic airways show inflammation and remodelling, with CD4+ helper cells, mast cells, and eosinophils characterising the inflammatory response. Inhaled corticosteroids remain the cornerstone of treatment with the addition of long-acting beta agonists as the next step if symptoms continue. Leukotriene antagonists, the only new drugs to reach the market in the past decade, have modest effects. However, a better understanding of the mechanisms underlying asthma and the genetic and environmental factors that predispose individuals to asthma should lead to better preventative strategies and new therapeutic approaches.

Anti-interleukin-9 antibody treatment inhibits airway inflammation and hyperreactivity in mouse asthma model

Numerous in vitro and in vivo studies in both animals and patients with asthma have shown that interleukin (IL)-9 is an important inflammatory mediator in asthma. To examine the effects of IL-9 antagonism on airway inflammation, ovalbumin-sensitized BALB/c mice were intravenously given anti-IL-9 antibody or an isotype-matched control antibody 30 minutes before challenge with aerosolized ovalbumin. Airway response to methacholine was measured, and samples of bronchoalveolar lavage fluid (BALF) were obtained 24 hours after the last antigen challenge. Lung tissue was harvested and examined histopathologically. After ovalbumin challenge, there were significant increases in airway hyperreactivity, the numbers of inflammatory cells in lung, and IL-4, IL-5, and IL-13 production in BALF. Treatment with anti-IL-9 antibody significantly prevented airway hyperreactivity in response to methacholine inhalation. Blockade of IL-9 reduced the numbers of eosinophils (0.3 +/- 0.1 x 10(5) and 23.6 +/- 0.5 x 10(5)/ml, anti-IL-9 antibody/control immunoglobulin G) and lymphocytes (0.2 +/- 0.2 x 10(5) and 0.8 +/- 0.1 x 10(5)/ml) in BALF. Anti-IL-9 antibody treatment also reduced the concentrations of IL-4 (from 70.6 +/- 4.6 to 30.8 +/- 5.2 pg/ml), IL-5 (from 106.4 +/- 12 to 54.4 +/- 6.6 pg/ml), and IL-13 (from 44.2 +/- 7.6 to 30.1 +/- 5.5 pg/ml) in BALF. Macrophage-derived cytokine expression in the airways was also decreased by IL-9 blockade. Taken together, our findings emphasize the importance of IL-9 in the pathogenesis of asthma and suggest that blockade of IL-9 may be a new therapeutic strategy for bronchial asthma.

Upregulation of IL-13 concentration in vivo by the IL13 variant associated with bronchial asthma

BACKGROUND

A substantial body of evidence exists to support the pivotal role of IL-13 in the pathogenesis of bronchial asthma. We recently found that a variant of the IL13 gene (Arg110Gln) is genetically associated with bronchial asthma, which is concordant with animal experiments using IL-13 in the development of asthma.

OBJECTIVE

To address whether the Gln110 variant of IL13 influences IL-13 function, contributing to the pathogenesis of bronchial asthma, we studied the functional properties of the variant.

METHODS

We generated 2 types of recombinant IL-13 proteins, the amino acids of which at 110 were arginine or glutamine, and analyzed the binding affinities with the IL-13 receptors, as well as the stability of the proteins. We further compared the relationship between the genotype and serum levels of IL-13.

RESULTS

The variant showed a lower affinity with the IL-13 receptor alpha2 chain, a decoy receptor, causing less clearance. The variant also demonstrated an enhanced stability in both human and mouse plasma. We further identified that asthmatic patients homozygous for the Gln110 variant have higher serum levels of IL-13 than those without the variant.

CONCLUSION

These results suggested that the variant might act as a functional genetic factor of bronchial asthma with a unique mechanism to upregulate local and systemic IL-13 concentration in vivo.

Elevated expression of interleukin-9 mRNA in the bronchial mucosa of atopic asthmatics and allergen-induced cutaneous late-phase reaction: relationships to eosinophils, mast cells and T lymphocytes

BACKGROUND

Interleukin-9 is a T cell-derived Th2-type cytokine that has been linked to airway hyper-responsiveness, mucus hypersecretion and mast cell infiltration in animal models. We recently demonstrated the potential for IL-9 to act in human eosinophil development and survival.

OBJECTIVES

The aims of this study were: (i) to compare IL-9 mRNA expression in bronchial biopsies between atopic asthmatics and normal controls, (ii) to investigate kinetic expression of IL-9 mRNA in skin biopsies after allergen challenge; and (iii) to relate IL-9 expression to infiltration of eosinophils, mast cell and T lymphocytes in local tissue.

METHODS

Bronchial biopsies were obtained from atopic asthmatics (n = 12) and normal non-asthmatics (n = 12) at baseline. Skin biopsies were obtained from atopic subjects (n = 11) at 1, 3, 6, 24, 48 and 72 h after allergen challenge. Diluent challenge sites at 24 h were used as controls. IL-9 mRNA was identified using the technique of in situ hybridization. The numbers of eosinophils, mast cells and T cells were evaluated by immunohistochemistry.

RESULTS

The numbers of IL-9 mRNA(+) cells present in the bronchial mucosa were significantly greater in atopic asthmatics than those in normal controls (P = 0.003). The numbers of eosinophils, but not mast cells, were also significantly higher in asthmatics (P < 0.005). The numbers of IL-9 mRNA(+) cells present in the airway of asthmatics significantly correlated with the numbers of eosinophils (r = 0.623, P = 0.03), but not mast cells or T cells. Compared with diluent challenge, the numbers of IL-9 mRNA(+) cells were significantly elevated at all allergen-challenged sites in the skin, with maximal signals at 48 h (P < 0.005). At 72 h, the numbers of IL-9 mRNA(+) cells significantly correlated with the numbers of eosinophils (r = 0.707, P = 0.015).

CONCLUSION

Elevated expression of IL-9 in allergic inflammation may contribute to local eosinophil infiltration and survival in asthma and other allergic atopic diseases.

Thromboxane A2 receptor gene polymorphism is associated with the serum concentration of cat-specific immunoglobulin E as well as the development and severity of asthma in Chinese children

Thromboxane A2 and its receptor (TBXA2R) are involved in the constriction of vascular and respiratory smooth muscles. The T924C polymorphism in the TBXA2R gene was recently found to be associated with asthma in Japanese adults but not in children. Its relationship with atopy or asthma severity in children has not been defined. To investigate this further, we first assessed the severity of asthma in Chinese children using a standardized questionnaire modified from the Disease Severity Score and spirometric evaluation. Then, peripheral blood was analyzed for serum total and aeroallergen-specific immunoglobulin E (IgE) levels, and TBXA2R T924C genotypes were determined by restriction fragment length polymorphism (RFLP) analysis. One-hundred and fifty three asthmatic patients and 57 control children were recruited, of respective mean ages 9.9 and 11.0 years (p = 0.07). The mean logarithmic serum total IgE concentration was 2.57 and 2.09, respectively, for the asthmatic group and control group (p < 0.0001). Atopy was detected in 132 (86%) asthmatics and 33 (58%) controls. A significant association was observed between T924C and the diagnosis of atopic asthma (p = 0.044; odds ratio: 1.84). In addition, those asthmatics homozygous for the mutant allele in T924C had a lower forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) (p = 0.032 and 0.002, respectively). Among our asthmatic patients, the TBXA2R T924C polymorphism correlated with the concentration of cat-specific IgE in serum (p = 0.046). Nonetheless, this gene marker did not show an association with the serum total IgE concentration or any clinical indicator of asthma severity. In conclusion, our results suggest that the T924C marker in the TBXA2R gene is associated, in Chinese children, with an increased susceptibility of developing atopic asthma. This marker is also associated with the extent of allergic sensitization to cat, as well as with reduced FEV1 and FVC values.

What we know about the genetics of asthma at the beginning of the 21st century

The understanding of the genetic controls that lead to the development of asthma is essential to its proper diagnosis and management. As we enter the 21st century, the goals of genetic research in asthma and allergies will be to: 1) identify genetic factors, 2) define environmental cofactors, 3) characterize how genes and the environment work together to cause disease, 4) develop treatment and prevention measures, including drugs designed for the individual's genetic make-up.

Pulmonary overexpression of IL-9 induces Th2 cytokine expression, leading to immune pathology

IL-9 is a pleiotropic cytokine with multiple functions on many cell types involved in the pathology of human asthma. The constitutive overexpression of IL-9 in the lungs of transgenic mice resulted in an asthma-like phenotype. To define the contribution of IL-9 to lung inflammation we generated transgenic mice in which lung-specific expression of the IL-9 transgene is inducible by doxycycline. Transgene induction resulted in lymphocytic and eosinophilic infiltration of the lung, airway epithelial cell hypertrophy with mucus production, and mast cell hyperplasia, similar to that seen in mice that constitutively expressed IL-9 in their lungs. Various cytokines, including IL-4, IL-5, and IL-13, were expressed in the lung in response to IL-9. Blockade of IL-4 or IL-5 following IL-9 induction reduced airway eosinophilia without affecting mucus production. In contrast, neutralization of IL-13 completely abolished both lung inflammation and mucus production. These findings suggest that pathologic changes in the lung require additional signals beyond IL-9, provided by IL-4, IL-5, and IL-13, to develop fully.

Interactions between genes and environmental factors in asthma and atopy: new developments

Asthma and associated phenotypes are complex traits most probably caused by an interaction of multiple disease susceptibility genes and environmental factors. Major achievements have occurred in identifying chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma, atopic dermatitis, IgE levels and response to asthma therapy. The aims of this review are to explain the methodology of genetic studies of multifactorial diseases, to summarize chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma and associated traits, to list genetic alterations that may alter response to asthma therapy, and to outline genetic factors that may render individuals more susceptible to asthma and atopy due to environmental changes.

Factor analysis of asthma and atopy traits shows 2 major components, one of which is linked to markers on chromosome 5q

BACKGROUND

A variety of definitions of asthma and atopy traits have been used in genetic studies. The variables used may be correlated, increasing the likelihood of type I error.

OBJECTIVE

We sought to clarify and quantify phenotypes that may be characterized by related traits. Principal components and factor analysis were applied to the correlation matrix of asthma and atopy traits before linkage analysis.

METHODS

Factor analysis was performed on 468 Hispanic and non-Hispanic white children enrolled in the Tucson Children's Respiratory Study, with complete information on 24 items, including skin test response to 7 allergens, total serum IgE levels, presence or absence of asthma attacks, wheezing episodes, hay fever, and cough. Factor score coefficients were then applied to all siblings (n = 877), and quantitative factor scores were derived. Single-point and multipoint nonparametric sib-pair analyses were performed to assess linkage to markers on chromosome 5q31-33. Analyses were also performed for individual items.

RESULTS

Two main factors were identified: Factor I had high loadings on atopic items, including skin test responses, IgE, and hay fever, and Factor II had high loadings that included asthma diagnosis, wheezing, cough, and Alternaria species skin test response. Factors I and II were correlated at an r value of 0.19. For the quantitative factor scores, significant single-point linkage (P < .0001) was demonstrated only for atopic Factor I, and a peak multipoint LOD score of 2.7 was seen for marker D5S479. Multipoint LOD scores for individual items were 1.1 or less.

CONCLUSION

These analyses suggest evidence for a locus or loci mapping to chromosome 5q31-33 associated with this composite atopic phenotype.

A polymorphism in the coding region of interleukin-13 gene is associated with atopy but not asthma in Chinese children

BACKGROUND

Interleukin (IL)-13 is an important cytokine secreted from type 2 helper T lymphocytes. It is essential for modulating IgE synthesis by human B cells. Previous studies showed that polymorphisms in the IL-13 gene were associated with serum total IgE or allergic asthma. The relationship of this marker with sensitization to individual aeroallergens has not been evaluated.

OBJECTIVE

We tested whether a polymorphism in the coding region of the IL-13 gene is associated with asthma and atopy in asthmatic children in Hong Kong.

METHODS

We used restriction fragment length polymorphism to detect R130Q genotype in Chinese children with asthma and control subjects. Serum total IgE was measured by microparticle immunoassay and specific IgE to common aeroallergens was measured using fluorescent enzyme immunoassay. Pulmonary function studies were performed using spirometry.

RESULTS

One hundred and fifty-seven patients and 54 control children were recruited. Their mean serum total IgE concentrations were 994 kIU/L and 473 kIU/L, respectively (P < 0.0001). Atopy as defined by > or = 1 positive RAST was found in 141 patients and 32 control children. The GlnGln form of the R130Q polymorphism in the IL-13 gene was associated with serum total IgE (P = 0.005) as well as specific IgE to Der p 1 (P = 0.021), mixed cockroaches (P = 0.03) and dog (P = 0.003) but not with physician-diagnosed asthma (P = 0.621). In addition, the R130Q polymorphism did not correlate with subjective or objective indicators of asthma severity in our patients.

CONCLUSION

Our results suggest that the R130Q polymorphism of the IL-13 gene is associated with elevated serum total and allergen-specific IgE but not asthma in Chinese children.

Ethnic differences in asthma and associated phenotypes: collaborative study on the genetics of asthma

BACKGROUND

In the Collaborative Study on the Genetics of Asthma, 314 families with 2584 subjects were characterized for asthma and allergy.

OBJECTIVE

The purpose of this investigation was to examine clinical heterogeneity observed in asthma and allergic characteristics among 3 ethnic groups (African American, white, and Hispanic family members).

METHODS

Pulmonary function parameters and asthma associated phenotypes were compared among the ethnic groups.

RESULTS

In comparison with the other groups, African American sibling pairs had a significantly lower baseline FEV(1) percent of predicted (P =.0001) and a higher rate of skin test reactivity to cockroach allergen (P =.0001); Hispanic sibling pairs had significantly more skin reactivity overall (P =.001); and white sibling pairs had significantly lower total serum IgE (P <.05). In addition, there were significantly more relatives with asthma among the African American families than among the white and the Hispanic families (P =.001).

CONCLUSION

Although different environmental backgrounds should be considered, these clinical differences could be due to differences in genetic susceptibility among the ethnic groups, such as those suggested by our previous genome screen.

Il-9 stimulates release of chemotactic factors from human bronchial epithelial cells

Interleukin (IL)-9 is a T helper 2 cytokine implicated as a candidate gene and contributor to human asthma. We hypothesized that the inflammatory potential of bronchial epithelium is affected by its local environment and explored this hypothesis with respect to the effect of IL-9 on bronchial epithelium. We investigated the response of primary and immortalized human bronchial epithelial cells to IL-9 stimulation with respect to the release of T-cell chemoattractant factors. In response to IL-9, the HBE4-E6/E7 cell line, but not BEAS-2B cells, released the T-cell chemoattractants IL-16 and regulated on activation, normal T cells expressed and secreted (RANTES) in a dose-dependent fashion. We found a similar dose response to IL-9 in primary cells from bronchial brushings of healthy subjects and that nearly all of the T-cell chemoattraction was attributable to IL-16 and RANTES. Reverse transcriptase/polymerase chain reaction of BEAS-2B, HBE4-E6/E7, and primary cells from two subjects revealed messenger RNA for IL-9 receptor (IL-9R) alpha but not in BEAS-2B cells. Fluorescence-activated cell sorter analysis of HBE4-E6/E7 and primary cells confirmed surface expression of the IL-9 receptor. Costimulation of both cell types with IL-9 and antibody to either gamma-common chain or IL-9Ralpha completely blocked the release of T-cell chemoattractant activity, confirming the primary role of a functioning IL-9 receptor for IL-9 signaling in HBE4-E6/E7 and primary bronchial epithelial cells. We conclude that IL-9 is a stimulus for airway epithelial cell release of T-cell chemoattractant factors, which in turn may modulate the immune response in allergic airway inflammation.

Identification and association of polymorphisms in the interleukin-13 gene with asthma and atopy in a Dutch population

Asthma and atopy are related conditions that may share similar genetic susceptibility. Linkage studies have identified a region on chromosome 5q that contains biologic candidates for both asthma and atopy phenotypes, including several proinflammatory cytokines. Interleukin (IL)-13, one of the candidate genes in the region, is directly involved in the regulation of immunoglobulin E and has been associated with both asthma and atopy. We sought to identify new polymorphisms in the IL-13 gene, and evaluated the involvement of a subset of these variants in asthma and atopy in a case-control study using probands and spouses from a Dutch asthma family study. IL-13 was sequenced in 20 probands and 20 unaffected spouses, and 10 polymorphisms were identified, four novel and six previously reported. Three single nucleotide (nt) polymorphisms (SNPs) were detected in the 5'-promoter region, two in intron 1, and five in exon 4. Only one of the exon 4 SNPs resulted in an amino-acid change (Arg130Gln). We analyzed three SNPs in IL-13 in an extended group of 184 probands and their spouses: one in the promoter region (-1111), the Arg130Gln (nt position 4257), and a 3' untranslated region SNP (nt position 4738). The most significant associations were observed to asthma (P = 0.005), bronchial hyperresponsiveness (P = 0.003), and skin-test responsiveness (P = 0.03) with the -1111 promoter. These results provide evidence that variation in the IL-13 gene is involved in the pathogenesis of asthma and atopy. Further investigation is required to determine which specific alleles or combination of alleles contribute to these phenotypes, and the possible downstream effects of the resulting change in IL-13 levels or activity.

New insights into the role of cytokines in asthma

Asthma is a triad of intermittent airway obstruction, bronchial smooth muscle cell hyperreactivity to bronchoconstrictors, and chronic bronchial inflammation. From an aetiological standpoint, asthma is a heterogeneous disease, but often appears as a form of immediate hypersensitivity. Many patients with asthma have other manifestations of atopy, such as rhinitis or eczema. Even among non-atopic patients with asthma, the pathophysiology of airway constriction is similar, raising the hypothesis that alternative mechanisms of mast cell degranulation may underlie the disease. The primary inflammatory lesion of asthma consists of accumulation of CD4(+) T helper type 2 (TH2) lymphocytes and eosinophils in the airway mucosa. TH2 cells orchestrate the asthmatic inflammation through the secretion of a series of cytokines, particularly interleukin 4 (IL-4), IL-13, IL-5, and IL-9. IL-4 is the major factor regulating IgE production by B cells, and is required for optimal TH2 differentiation. However, blocking IL-4 is not sufficient to inhibit the development of asthma in experimental models. In contrast, inhibition of IL-13, another TH2 cytokine whose signal transduction pathway overlaps with that of IL-4, completely blocks airway hyperreactivity in mouse asthma models. IL-5 is a key factor for eosinophilia and could therefore be responsible for some of the tissue damage seen in chronic asthma. IL-9 has pleiotropic activities on allergic mediators such as mast cells, eosinophils, B cells and epithelial cells, and might be a good target for therapeutic interventions. Finally, chemokines, which can be produced by many cell types from inflamed lungs, play a major role in recruiting the mediators of asthmatic inflammation. Genetic studies have demonstrated that multiple genes are involved in asthma. Several genome wide screens point to chromosome 5q31--33 as a major susceptibility locus for asthma and high IgE values. This region includes a cluster of cytokine genes, and genes encoding IL-3, IL-4, IL-5, IL-9, IL-13, granulocyte macrophage colony stimulating factor, and the beta chain of IL-12. Interestingly, for some of these cytokines, a linkage was also established between asthma and their receptor. Another susceptibility locus has been mapped on chromosome 12 in a region that contains other potential candidate cytokine genes, including the gene encoding interferon gamma, the prototypical TH1 cytokine with inhibitory activities for TH2 lymphocytes. Taken together, both experimental and genetic studies point to TH2 cytokines, such as IL-4, IL-13, IL-5, and IL-9, as important targets for therapeutic applications in patients with asthma.

Sensitization to common allergens and its association with allergic disorders at age 4 years: a whole population birth cohort study

BACKGROUND

Atopy is defined as the genetic propensity to develop immunoglobulin E antibodies in response to exposure to allergens and assessed by skin prick test responses to common allergens. Although it is generally agreed that atopy is an important risk factor for allergic diseases such as asthma, rhinitis, and eczema, the extent to which atopy accounts for these diseases is controversial.

OBJECTIVE

We aim to describe the prevalence of sensitization to common allergens and investigate the degree of association of atopy (as defined by positive skin prick test to 1 or more common allergens) to asthma, rhinitis, and eczema in a birth cohort at the age of 4 years.

METHODS

A birth cohort of 1456 children was recruited over a 14-month period (1989-1990). These children have been seen previously at 1 and 2 years of age. At 4 years, 1218 children were reviewed and an interview was administered or postal questionnaire was completed for the presence of allergic diseases (asthma, rhinitis, and eczema). Additionally, in 981 children, skin prick tests with a battery of 12 common allergens were performed. Allergens were house dust mite (Dermatophagoides pteronyssimus), grass pollen mix, cat, dog, Alternaria alternata, Cladosporium herbarum, cow's milk, hen's egg, soya, cod, wheat, and peanut. A mean wheal diameter of at least 3 mm greater than the negative control was taken as positive. This analysis is confined to the 981 (67% of the original population) who also had skin prick tests to the standard battery. chi(2) tests were used to test the univariate association between each allergic disease and positive skin test. Multiple logistic regression analysis was performed to obtain the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the independent effect of sensitization to each allergen on allergic disease, adjusting for the effect of sensitization to other allergens. To ascertain how much of allergic disease is attributable to atopy, we estimated the population-attributable risk. This was calculated with the formula: P(R - 1) where R is the OR for the allergic disease under consideration and P is the proportion of atopy in children with that disease.

RESULTS

Children who were skin prick-tested at 4 years were similar in most characteristics to the rest of the population, except that they had a higher prevalence of allergic disease. Allergic disorders (asthma, rhinitis, and eczema) were present in 276 (28.1%) of 981. One hundred ninety-two (19.6%) children were atopic (positive reaction to 1 or more allergens). Sensitization to inhalant allergens was relatively common (19.2%) as compared with food allergens (3.5%). House dust mite (11.9%), grass pollen (7.8%), and cat (5.8%) were the most common positive reactions. A test to the 4 most common allergens (house dust mite, grass pollen, cat, and A alternata) could detect 94% of the atopic children. Sensitization to the 4 most common allergens was strongly associated with the presence of allergic disorders. There was a graded effect with the potent allergens, such as house dust mite, having the greatest impact. For example, 50% of children sensitized to house dust mite had asthma as opposed to 44% sensitized to cat, 42% sensitized to grass pollen, and 32% sensitized to A alternata. Overall, 68.4% of children sensitized to house dust mite had asthma, eczema, and/or rhinitis. The respective figures for grass pollen, cat, and A alternata were 64.9%, 66.7%, and 57.4%. The proportion of children sensitized to cat was not higher in households with cat ownership (households with cats: 5.1% [19/374]; households without cats: 6.2% [36/580]; not significant [NS]). Similarly, no difference was seen in sensitization to dog in households with and without dogs (households with dogs: 1.8% [5/282]; households without dogs: 2.8% [19/673]; NS). Boys were atopic more often than girls at this age (male: 112 of 497 [22.5%] vs female: 80 of 484 [16.5%]; OR: 1.47, 95% CI: 1.07-2.02). Male preponderance was observed with most allergens, but this was statistically significant only for house dust mite (male: 75/497 [15.1%] vs female: 42/484 [8.7%]; OR: 1.87; CI: 1.25-2.79) and grass pollen (male: 51/497 [10.3%] vs female: 26/484 [5.4%]; OR: 2.01; CI: 1.23-3.29). An independent effect of allergen sensitization on asthma was observed only with house dust mite with an OR of 8.07 (CI: 4.60-14.14). The highest independent risk for rhinitis was sensitization to grass pollen (OR: 5.02; CI: 2.21-11.41), and for eczema, sensitization to peanut (OR: 4.65; CI: 1.02-21.34). The majority of children (98/192) were sensitized to >1 allergen. A graded effect was observed with the risk of allergic disease in the child increasing with the number of positive skin prick test reactions. This effect was consistent throughout the spectrum of allergic diseases (asthma, eczema, and rhinitis). (ABSTRACT TRUNCATED)

Pathophysiological mechanisms of asthma. Application of cell and molecular biology techniques

Asthma is a common increasing and relapsing disease that is associated with genetic and environmental factors such as respiratory viruses and allergens. It causes significant morbidity and mortality. The changes occurring in the airways consist of a chronic eosinophilic and lymphocytic inflammation, together with epithelial and structural remodeling and proliferation, and altered matrix proteins, which underlie airway wall narrowing and bronchial hyperresponsiveness (BHR). Several inflammatory mediators released from inflammatory cells such as histamine and cysteinyl-leukotrienes induce bronchoconstriction, mucus production, plasma exudation, and BHR. Increased expression of T-helper 2 (Th2)-derived cytokines such as interleukin-4 and 5 (IL-4, 5) have been observed in the airway mucosa, and these may cause IgE production and terminal differentiation of eosinophils. Chemoattractant cytokines (chemokines) such as eotaxin may be responsible for the chemoattraction of eosinophils to the airways. The initiating events are unclear but may be genetically determined and may be linked to the development of a Th2-skewed allergen-specific immunological memory. The use of molecular biology techniques on tissues obtained from asthmatics is increasing our understanding of the pathophysiology of asthma. With the application of functional genomics and the ability to transfer or delete genes, important pathways underlying the cause if asthma will be unraveled. The important outcome of this is that new preventive and curative treatments may ensue.

Genomewide screen and identification of gene-gene interactions for asthma-susceptibility loci in three U.S. populations: collaborative study on the genetics of asthma

The genomewide screen to search for asthma-susceptibility loci, in the Collaborative Study on the Genetics of Asthma (CSGA), has been conducted in two stages and includes 266 families (199 nuclear and 67 extended pedigrees) from three U.S. populations: African American, European American, and Hispanic. Evidence for linkage with the asthma phenotype was observed for multiple chromosomal regions, through use of several analytical approaches that facilitated the identification of multiple disease loci. Ethnicity-specific analyses, which allowed for different frequencies of asthma-susceptibility genes in each ethnic population, provided the strongest evidence for linkage at 6p21 in the European American population, at 11q21 in the African American population, and at 1p32 in the Hispanic population. Both the conditional analysis and the affected-sib-pair two-locus analysis provided further evidence for linkage, at 5q31, 8p23, 12q22, and 15q13. Several of these regions have been observed in other genomewide screens and linkage or association studies, for asthma and related phenotypes. These results were used to develop a conceptual model to delineate asthma-susceptibility loci and their genetic interactions, which provides a promising basis for initiation of fine-mapping studies and, ultimately, for gene identification.

Role of IL-9 in the pathophysiology of allergic diseases

Considerable evidence from both human and animal studies indicates that CD4(+) cells are the predominant cell type involved in the regulation of airway inflammation through the expression of T(H)2-type cytokines. The effects of T(H)2-type cytokines, particularly IL-4 and IL-5, on inflammatory and structural cells in airways have been studied in great detail. They were shown to be important for inflammatory cell maturation, activation and proliferation, IgE production, chemokine expression, mucus secretion, and bronchial hyperresponsiveness. Recent work has shown the potential importance of another T(H)2-type cytokine, IL-9. The development of transgenic mice overexpressing IL-9 has suggested a key role for this cytokine in the development of the asthmatic phenotype, including eosinophilic inflammation, bronchial hyperresponsiveness, elevated IgE levels, and increased mucus secretion. IL-9 has been shown to act on many cell types involved in asthma, including T cells, B cells, mast cells, eosinophils, neutrophils, and epithelial cells, and thus might be important in the pathophysiology of allergic asthma.

Rationale for the development of recombinant human CC10 as a therapeutic for inflammatory and fibrotic disease

CC10/uteroglobin is a remarkable protein whose physiological roles have only recently been explored in vivo. Both transgenic mice that have been rendered deficient and humans that have been characterized as deficient in this protein exhibit tendencies toward inflammatory, fibrotic, and oncologic disease, demonstrating the potential of the protein as a therapeutic agent. The protein itself is an excellent candidate for clinical development because of its inherent physical properties. It is relatively small, resistant to proteases, stable to extremes of heat and pH, and can be produced by recombinant methods. The physiological roles of this multifunctional protein continue to be uncovered as research progresses in vitro, in animals, and eventually in humans. The pathways through which CC10 mediates its effects, its receptors, and other family members will be a rich source of exciting research, as well as potential diagnostic and therapeutic agents. This paper is an introductory, noncomprehensive review of some of the scientific and medical rationale in support of CC10-based therapies in selected clinical applications.

Susceptibility genes in asthma and allergy

Genome-wide screens for asthma and atopy susceptibility loci have been completed in six population samples. Despite the extensive clinical heterogeneity associated with these phenotypes, 20 chromosomal regions show evidence of linkage (P < 0.01) in three or more population samples. Thus, this survey suggests that at least 20 independent loci influence susceptibility to asthma, atopy, or associated phenotypes and indicates that the genetics of these phenotypes are truly complex. Ongoing studies are aimed at identifying the specific gene or genes in these regions that confer susceptibility to asthma or atopy.

Linkage and allelic association of chromosome 5 cytokine cluster genetic markers with atopy and asthma associated traits

Linkage and association of polymorphic markers in the chromosome 5q31-q33 cytokine cluster to atopy and asthma associated phenotypes have been reported by a number of groups. To investigate this region, 29 polymorphic markers were used to genotype a combined set of 233 families. These markers were ordered based upon the genetic data, supplemented by published genetic and physical maps. Significant two-point linkage was observed for asthma (most significant marker IRF1, P = 0.0002) and atopy (CD14SNP, P = 0.0001). Allelic association was observed between D5S463 and atopy (P = 0.002) and the skin prick test index (P = 0.04). The data support the possibility of three asthma/atopy loci in the 5q31-q33 region, each with a relatively small effect.

IL4-R1 (5q31-q33) and FcepsilonRI-betaca (11q13) markers and atopy: a case/control study in a spanish population

BACKGROUND

Rhinoconjunctivitis and bronchial asthma are atopic diseases with a high prevalence in the Canary Islands (Spain). Given that the most prevalent allergen is the house-dust mite Dermatophagoides pteronyssinus, early detection of genetically susceptible subjects would allow the application of preventive measures. The objective was to investigate the possible association of IL4-R1 (chromosome 5q31-q33) and FcepsilonRI-betaca (chromosome 11q13) markers with the atopic disease in our population.

METHODS

We performed a case/control study in which patients were recruited on the basis of diagnosis of rhinoconjunctivitis and/or bronchial asthma, and positive skin prick test to D. pteronyssinus. Analysis of IL4-R1 and FcepsilonRI-betaca microsatellites was carried out by PCR and electrophoresis in acrylamide gels.

RESULTS

We have not found evidence of association between IL4-R1 and FcepsilonRI-betaca markers and atopic disease in our population. In addition, these markers have shown a high percentage of homozygosis.

CONCLUSIONS

IL4-R1 and FcepsilonRI-betaca markers have not proved to be useful genetic markers for linkage or association studies in our population.