Associations between total serum IgE levels and the 6 potentially functional variants within the genes IL4, IL13, and IL4RA in German children: the German Multicenter Atopy Study

BACKGROUND: Increased total serum IgE levels are a common characteristic of atopic disorders. Six potentially functional variants, including C-590T in the IL4 gene, C-1055T and Arg130Gln in the IL13 gene, and Ile50Val, Ser478Pro, and Gln551Arg in the IL4RA gene, have been evaluated for their involvement in the control of total serum IgE levels and related atopic disorders, but the results of these studies have been inconsistent. OBJECTIVE: We examined whether these 6 variants had genotypic effects on total serum IgE levels in 823 unrelated German children from a large infant cohort, the German Multicenter Atopy Study. METHODS: Marginal effect models were used for the analyses of the repeated IgE measurements. Weighted linear regression and family-based tests of association were performed to minimize the possibility of spurious effects caused by selection bias or confounding on the basis of ethnic background. RESULTS: There are significant associations between increased total serum IgE levels and 2 variants in the IL13 gene (P <.005 and.0002 for Arg130Gln and C-1055T, respectively). These genetic effects are unlikely to be due to solely linkage disequilibrium between 2 polymorphisms, population stratification, or nonrepresentative samples. In addition, exposure to maternal smoking appears to modify the above effects on total serum IgE levels. However, no statistical association was observed between this quantitative phenotype and the other 4 variants examined. CONCLUSION: These findings suggest that variants C-1055T and Arg130Gln of the IL13 gene might play an important role on total serum IgE production in this study population.     

Eotaxin polymorphisms and serum total IgE levels in children with asthma

BACKGROUND: Eotaxin (chemokine, CC motif, ligand; CCL11) is a potent eosinophil chemoattractant strongly implicated in the pathobiology of asthma. Genetic variation at the CCL11 locus has been correlated with serum total IgE, blood eosinophil counts, and circulating eotaxin protein levels in several case-control asthma studies. Family-based association studies of CCL11 genetic variants have not been reported to date. OBJECTIVE: To evaluate 9 common CCL11 single nucleotide polymorphisms (SNPs) in nuclear families ascertained through patients with asthma participating in the Childhood Asthma Management Program study. METHODS: Single nucleotide polymorphism genotyping was performed by using minisequencing and probe hybridization platforms. Family-based association analysis for asthma and 4 asthma-related intermediate quantitative phenotypes was performed by using FBAT. RESULTS: One SNP, -384A>G, was associated with asthma among African American families (P = .01). CCL11 SNPs and haplotypes were not associated with asthma among white or Hispanic families. Two low-frequency alleles in strong pairwise linkage disequilibrium, -426C and IVS2+199A, were associated with lower serum total IgE levels (P = .0006 and P = .009, respectively) in white families, whereas 2 more common variants, -576C and g.4438C, were associated with higher IgE levels in African American families (P = .01-.04). Haplotype analysis in the white cohort provided additional evidence of association with serum total IgE, implicating 2 haplotypes. No single SNP or haplotype associations were observed with blood eosinophil levels, FEV(1), or airway responsiveness. CONCLUSION: These findings provide further evidence that genetic variation at the CCL11 locus is an important determinant of serum total IgE levels among patients with asthma.     

Relation between frequency of asthma and IgE antibody levels against Dermatophagoides farinae and total serum IgE levels in schoolchildren

The relation between the frequency of wheezing illness and IgE antibody levels against Dermatophagoides farinae (Df) and total IgE levels was examined in 457 randomly selected schoolchildren. From the response to the ATS-DLD-78-C respiratory symptoms questionnaire, 14 subjects (3.1%) were found to have asthma syndrome (recurrent episodes of attacks of shortness of breath with wheezing) and 17 subjects (3.7%), wheezing syndrome (only wheezing). The percentage of the asthma syndrome increased with increasing levels of Df-specific IgE, and there was an intimate correlation between the percentage of asthma syndrome and Df-specific IgE levels (r = 0.97; p less than 0.001), whereas such association was not found between the two (r = -0.19; p greater than 0.5). Similar relations were found between the frequencies of the specific syndromes and total IgE levels. There was a significant correlation between total IgE levels and Df-specific IgE levels in the total population (r = 0.7; p less than 0.001). These results suggest that allergic reaction greatly contributes to the development of asthma in children.     

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.     

Increased total serum IgE levels in patients with asthma and promoter polymorphisms at CTLA4 and FCER1B.

BACKGROUND: Increasing evidence indicates that total serum IgE levels are largely determined by genetic factors, and we recently established that the -109C/T promoter polymorphism at FCER1B is a genetic factor that affects total serum IgE levels. The gene encoding cytotoxic T lymphocyte antigen 4 (CTLA4) is another candidate factor in high IgE responsiveness, because B7-CD28/CTLA4 interaction can promote the differentiation and development of the T(H)2 lymphocyte subset. OBJECTIVE: We intended to determine whether CTLA4 is associated with increased levels of total serum IgE or with the development of asthma or atopy. METHODS: We performed a case-control study involving 339 patients with asthma and 305 healthy control subjects, of whom 226 of the patients with asthma and 219 of the healthy control subjects had previously been genotyped for the -109C/T promoter polymorphism at FCER1B. In the current study, we genotyped 2 polymorphisms in the CTLA4 gene, one involving the promoter (-318C/T) and the other involving exon 1 (+49A/G), in addition to the FCER1B promoter polymorphism. RESULTS: Patients with asthma who were homozygous for the -318C allele at the CTLA4 promoter region had higher levels of total serum IgE than patients with asthma carrying the -318T allele (P =.00470). The analysis of -318C/T (at CTLA4) and -109C/T (at FCER1B) promoter polymorphisms showed a significant correlation between the combined genotypes and increased levels of total IgE in patients with asthma (P =.000014). In contrast, no correlation between total serum IgE levels and -318C/T or +49A/G genotypes was detected in 305 healthy control subjects. There was no evidence indicating an association between a putative allele for asthma or atopy and alleles at any of the CTLA4 polymorphic loci. CONCLUSION: Our findings suggest that promoter polymorphisms of both CTLA4 and FCER1B are genetic factors that influence total serum IgE levels in patients with asthma. This supports the theory that variance in total serum IgE levels in patients with asthma is determined by mutations in multiple genes, each of which has a relatively small effect on the phenotype.     

A cluster of seven tightly linked polymorphisms in the IL-13 gene is associated with total serum IgE levels in three populations of white children

BACKGROUND: Increased levels of total serum IgE are a strong risk factor for the development of asthma. IgE is also involved in host defenses against parasites and fungi. Linkage of total serum IgE with markers located close to the 3 Mb cluster of cytokine genes in chromosome 5q31 has been reported. IL-4 or IL-13 are regarded as essential for IgE synthesis. OBJECTIVE: We tested whether polymorphisms in the IL-13 gene might explain the linkage between chromosome 5q31 and total serum IgE levels. METHODS: We used denaturing HPLC to detect polymorphisms in overlapping PCR fragments of the IL-13 gene including promoter and 3' untranslated regions. After sequencing was performed to identify the locations of the polymorphisms, PCR and primer-induced restriction site assays were used to genotype subjects in 3 unselected populations. RESULTS: We report here 7 polymorphisms (6 novel) in IL-13. Four of these polymorphisms are tightly linked to a variant in the terminal portion of the coding region of the gene that results in a predicted amino acid change in residue 130 (Arg130Gln). The Gln form is strongly associated (P =.000002) with increased serum IgE levels in 3 different populations comprising a total of 1399 children. Two additional polymorphisms in the promoter region of IL-13 are more loosely linked to Arg130Gln and are also less significantly associated with total serum IgE levels. CONCLUSION: These data suggest that the Arg130Gln polymorphism in IL-13, or others in close linkage with it, is associated with the development of the elevated serum IgE phenotype.     

Associations between specific serum IgE response and 6 variants within the genes IL4, IL13, and IL4RA in German children: the German Multicenter Atopy Study

BACKGROUND: Among many published studies of specific IgE response or atopy, only a few showed positive marginal effects for 6 potentially functional single nucleotide polymorphisms (SNPs; C-590T in the IL4 gene, C-1055T and Arg130Gln in the IL13 gene, and Ile50Val, Ser478Pro, and Gln551Arg in the IL4RA gene). SNPs were commonly considered individually, and therefore the true effect could be masked by other genes or environmental factors. OBJECTIVE: We tested the relationship between these 6 SNPs and sensitization to food, mite, cat, and outdoor allergens in unrelated German children drawn from the Multicenter Atopy Study. Gene-gene and gene-environment interactions were also evaluated. METHODS: Multiple logistic regression models were used for the analyses of 4 sensitization outcomes. RESULTS: The variant C-1055T was significantly associated with increased risk of sensitization to food and outdoor allergens, with odds ratios of 3.49 (95% CI, 1.52-8.02) and 2.27 (95% CI, 1.04-4.94), respectively. The effects of the TT genotype on food sensitization appear to depend on variants in the IL4RA gene, in which marginally significant interaction terms were observed. Significant evidence supported an interaction between exposure to maternal smoking and variant Gln551Arg on risk of cat sensitization. In addition, we found that the effect of variant C-590T on sensitization to mite depended on Der p 1 allergen levels in carpet dust samples. CONCLUSIONS: These findings not only suggested that variants in the IL4, IL13, and IL4RA genes play an important role in controlling specific IgE response but also strengthened our understanding of gene-gene and gene-environment interaction on the development of specific sensitization in this study population.     

Relation between total serum IgE levels and IgE antibody production in rats.

Five different rat strains were immunized with 100 microgram ovalbumin and 1 mg Al (OH)3. A good correlation was found between the total serum IgE level of a rat strain before immunization and the IgE antibody production. Good IgE antibody-producing strains had high total serum IgE levels and vice versa. A discordance between the evolution of the total serum IgE level after immunization and the changes in IgE antibody level was found in all strains.     

Causes of variation in serum IgE levels in normal populations

Serum IgE was measured in 326 individuals 5 years of age and older who were members of families of both black and white populations. IgE levels were higher in blacks than in whites and much higher in children than in adults. No marked change with age was detected in children 5 to 15 years of age, but IgE levels decreased rapidly with increasing age after 15. Secretors of ABH substances had higher IgE levels than nonsecretors, but sex, blood group systems ABO, MN, and Rh had no effect on IgE levels. Levels varied widely from person to person and showed almost continuous frequency distributions. Comparisons among relatives revealed that, in the populations under study, from 40% to 50% of the total variation was accounted for by genetic variation. The basis of variation in IgE levels appears to be polygenic, that is, in addition to environmental factors many genes may contribute to the end product. Levels of IgE appeared to be independent of those of the other 4 classes of inmunoglobulins.     

Polymorphisms in IL13, total IgE, eosinophilia, and asthma exacerbations in childhood

BACKGROUND: It is unclear whether single nucleotide polymorphisms (SNPs) in the gene for IL-13 (IL13) influence asthma severity and/or asthma morbidity. OBJECTIVES: To examine the relation between IL13 SNPs and asthma-related phenotypes in 2 independent populations. METHODS: We used family-based methods to test for association between SNPs in IL13 and asthma-related phenotypes in Costa Rican children with asthma. We attempted to reproduce significant findings in white (non-Hispanic) children with asthma in the Childhood Asthma Management Program (CAMP). RESULTS: In Costa Rica and in CAMP, the A allele (Gln) of IL13 coding SNP (rs20541) was significantly associated with increased eosinophil count (P < .011 in both studies) and increased serum total IgE (P < .054 in both studies). The T allele of IL13 promoter SNP (rs1800925) was inversely associated with asthma exacerbations in Costa Rica (P = .069). Although this SNP (rs1800925) was not associated with asthma exacerbations among all white children in CAMP, it was associated with increased risk of asthma exacerbations among children on inhaled corticosteroids (P = .02). CONCLUSION: Polymorphisms in IL13 were significantly associated with serum total IgE and eosinophil count in 2 populations. IL13 polymorphisms may also be associated with asthma exacerbations, and this effect may be dependent on medication use. Our study is the first to report a potential negative interaction between a genetic polymorphism and response to inhaled corticosteroids. CLINICAL IMPLICATIONS: Polymorphisms in IL13 are associated with serum total IgE and eosinophil count and may be associated with asthma exacerbations.     

哮喘家系成员血清总IgE的遗传学分析

目的 探讨哮喘家系成员血清总IgE的遗传方式。方法 收集哮喘遗传家系，用酶联免疫吸附测定方法检测哮喘家系成员病人和正常人的血清总IgE，并取无哮喘家族史和无过敏家族史的正常人作为对照组，进行总IgE的遗传分析。结果 哮喘家系成员的血清总IgE分布是双形态分布，父母一方及其子女IgE超常的占56％，父母双方及其子女IgE超常的占50％。结论 总IgE可能是以单基因遗传控制为主，且总IgE的超常(H)可能是因常染色体显性遗传伴不完全外显。     

Association of a disintegrin and metalloprotease 33 (ADAM33) gene with asthma in ethnically diverse populations

BACKGROUND: Asthma is a complex genetic disease characterized by reversible intermittent airway obstruction and respiratory symptoms primarily caused by acute and chronic bronchial inflammation. Recently, a gene potentially involved in airway remodeling, a disintegrin and metalloprotease 33 (ADAM33), was implicated in asthma susceptibility. OBJECTIVE: We sought to determine whether polymorphisms in ADAM33 are associated with asthma or closely related phenotypes in 4 different asthma populations. METHODS: Eight single nucleotide polymorphisms (SNPs) were evaluated in the 3' portion of ADAM33 in 4 unique asthma populations (African American, US white, US Hispanic, and Dutch white). These SNPs were previously reported to be associated with asthma in white populations from the United States and United Kingdom. RESULTS: Significant associations were observed with at least one SNP and asthma in each population (P =.0009-.04). Related phenotypes that included total serum IgE levels and skin test responsiveness were also associated (P =.003-.05). However, no single SNP was associated across all populations. Additionally, haplotype analysis revealed that no single haplotype accounted for asthma susceptibility risk, although potential risk haplotypes existed within some of the populations. CONCLUSION: Replication of the original ADAM33 findings in these 4 additional asthma populations suggests that this gene (and perhaps others that interact with it) is important in the development and pathogenesis of asthma.     

Association of Eotaxin gene family with asthma and serum total IgE

The Eotaxin gene family (Eotaxin1, Eotaxin2 and Eotaxin3) recruits and activates CCR3-bearing cells such as eosinophils, mast cells and Th2 lymphocytes that play a major role in allergic disorders. To date, the effect of polymorphisms of Eotaxin genes on asthma phenotypes has not been thoroughly examined. In our research, we sequenced whole regions of the Eotaxin gene family to identify polymorphisms, which may be involved in the development of asthma and total serum IgE. We have identified 37 SNPs in the Exotaxin gene family (Exotaxin1, 2 and 3), and 17 common polymorphic sites were selected for genotyping in our asthma cohort (n=721). Statistical analysis revealed that the EOT2+1265A>G G* allele showed significantly lower frequency in asthmatics than in normal healthy controls (0.14 versus 0.23, P=0.002), and that distribution of the EOT2+1265A>G G* allele-containing genotypes was also much lower in asthmatics (26.3 versus 40.8%, P=0.003). In addition, a non-synonymous SNP in Eotaxin1, EOT1+123Ala>Thr showed significant association with total serum IgE levels (P=0.002-0.02). The effect of EOT1+123Ala>Thr on total serum IgE appeared in a gene-dose-dependent manner. Our findings suggest that the development of asthma may be associated with EOT2+1265A>G polymorphisms, and the susceptibility to high IgE production may be attributed to the EOT1+123Ala>Thr polymorphism. Eotaxin variation/haplotype information identified in this study might provide valuable insights into strategies for the control of asthma.     

Common variants in FCER1A influence total serum IgE levels from cord blood up to six years of life

Background:  In a recent genome wide scan, a functional promoter variant (rs2251746) in the gene encoding the alpha chain of the high affinity receptor for immunoglobulin E (IgE) (FCER1A) was identified as major determinant of serum IgE levels.
Objective:  The aim of this study was to investigate the role of rs2251746 on total IgE levels measured at different stages of life from birth (cord blood) up to the age of 6 and to evaluate its interaction with the environmental influences in two German birth cohorts.
Method:  Data from two German birth cohorts were analysed ( n  = 1043 for the LISA cohort and n  = 1842 for the GINI cohort). In the studies, total serum IgE was measured from cord blood, and blood samples taken at the age of 2/3 and 6 years. In a subgroup of the LISA study, house dust samples were collected at age of 3 months and the amount of endotoxin was determined. Random effect models were used to analyse the longitudinal health outcomes.
Results:  In the two cohorts, the heterozygote and the rare homozygote of rs2251746 was consistently associated with lower total IgE levels from birth up to the age of 6 years with an allele-dose effect ( P  < 0.02 for blood samples taken at each time point in both cohorts). No interaction between the two FCER1A encoding gene and environmental exposures including endotoxin, worm infestation and day care centre attendance during early childhood were observed.
Conclusion:  Common variants in FCER1A strongly influence basal IgE production independently from environmental stimuli. These effects can be observed already in cord blood pointing to altered gene expression in foetus.     

Association of Eotaxin gene family with asthma and serum total IgE

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A hexanucleotide repeat upstream of eotaxin gene promoter is associated with asthma, serum total IgE and plasma eotaxin levels

Background

Eotaxin (CCL11) is a small protein produced in the lungs of patients with asthma, and is a potent chemoattractant for eosinophils.

Aim

To elucidate the role of eotaxin in asthma by an association study of functional and novel eotaxin polymorphisms in case–control and family‐based study designs.

Methods

Eotaxin +67G/A, –384A/G and –426C/T single‐nucleotide polymorphisms and a hexanucleotide (GAAGGA)_n repeat 10.9 kb upstream of the gene were genotyped in a cohort of age, sex and ethnically matched patients with asthma (n = 235) and healthy controls (n = 239), and also in a study population of 230 families with asthma recruited from north/northwest India. Total serum IgE (TsIgE) and plasma eotaxin levels were measured using ELISA.

Results

+67G/A polymorphism was found to be significantly associated with asthma in case–control (p = 0.009) and family‐based studies (p = 0.006). Its functional role, as it was correlated with plasma eotaxin levels (p = 0.006), was also demonstrated. Further, –384C/T single‐nucleotide polymorphism was found to be significantly associated with log₁₀ TsIgE (p = 0.016 in case–control and p = 0.018 in families) and eotaxin levels (p = 0.007). Most interestingly, for the first time, a highly significant association of the newly studied (GAAGGA)_n hexanucleotide repeat with asthma (p = 3×10⁻⁶), log₁₀TsIgE (p = 0.006) and eotaxin levels (p = 0.004) was observed. G_A_C_8 was also identified as an important risk haplotype associated with high TsIgE and plasma eotaxin levels.

Conclusions

This study provides further evidence that eotaxin polymorphisms are associated with the development of asthma by regulating eotaxin levels and reinforces towards the scanning of other chemokine genes present at 17q21 locus for their association with asthma and related phenotypes.Eosinophils play a major role in the pathogenesis of allergic diseases including asthma by releasing various granular proteins, reactive NO, cytokines and chemokines at the site of inflammation, thus causing tissue damage.¹ Interplay between chemokines and their receptors are considered to be crucial for the trafficking of eosinophil and other lymphocytes from the circulation to the bronchoalveolar spaces of the patients with asthma.² Eotaxin (chemokine, CC motif, ligand; CCL11) is a predominant eosinophil chemoattractant, which binds to chemokine receptor 3.^3,4 Chemokine receptor 3 is also present on the Th2 CD4⁺ lymphocytes, basophils, dendritic cells and mast cells.^5,6 Thus, the role of eotaxin in asthma is not confined to eosinophil migration and activation only, but extended to many other effector cells involved in disease pathogenesis. It has also been observed that along with interleukin 5, eotaxin prolongs the viability of eosinophils.⁷ Eotaxin mRNA and protein are found to be elevated in the induced sputum, bronchial epithelium and airways of the patients with moderate to severe asthma.^8,9,10 Bronchoalveolar lavage fluid of the patients with asthma also showed increased levels of eotaxin after allergen inhalation.¹¹ In addition, higher plasma eotaxin levels have been observed in subjects with symptoms of acute asthma and airflow obstruction than subjects with stable asthma. Plasma eotaxin levels have been correlated with severity of asthma even in the presence of steroid treatment.^12,13Eotaxin gene is present on chromosome 17q21.1, where linkage with asthma and related phenotypes has been previously reported in various ethnic populations.^14,15 Previous studies on eotaxin gene polymorphisms and asthma remain inconclusive as most of them failed to establish a strong association.^{16,17,18,19,20} However, in few other studies, eotaxin single‐nucleotide polymorphisms (SNPs) have been correlated significantly with asthma‐associated phenotypes including lung function, serum IgE, circulating blood eosinophils, eosinophil migration and activation, and plasma eotaxin levels.^{16,17,18,21,22} Studies have also been undertaken to demonstrate the functional implication of various promoter and exonic variants of the eotaxin.^20,22 Notably, the variant and the direction of association are inconsistent across different ethnic populations owing to some inherent reasons. However, no such studies have yet been undertaken in an ethnically divergent Indian population.Importantly, the 17q11–17q21 chromosomal region harbours many other important chemokines including RANTES, MCP1, MCP3 and so on, and also the gene for inducible nitric oxide synthase. Recently, we have reported the association of the gene for inducible nitric oxide synthase microsatellite repeats with asthma and related phenotypes in an Indian population, demonstrating the importance of 17q region in asthma predisposition.²³ The results of our previous study and the well‐documented role of eotaxin in asthma prompted us to undertake an association study of eotaxin gene with asthma and associated phenotypes in case–control and family‐based study designs. We have also measured the plasma eotaxin level and attempted to correlate it with eotaxin gene variants.