The -590C/T and -34C/T interleukin-4 promoter polymorphisms are not associated with atopic eczema in childhood

Susceptibility to the development of asthma and other atopic diseases is known to have a genetic component. To date, several studies have linked chromosome 5q31 to asthma and atopy in human beings. This region harbors a cluster of cytokine and growth factor genes, IL-4 presenting as a prime atopy candidate gene, inasmuch as it plays a pivotal role in the atopy pathway. Our approach was to identify polymorphisms within the promoter regions of IL-4 and test their association with atopic eczema. Polymorphisms were typed in a cohort of 76 small nuclear families and 25 triads with childhood atopic eczema. The genotypes were used to test for linkage in the presence of association with atopic eczema. A new polymorphism, -34C/T, was identified and studied with a known polymorphism, -590C/T. On its own, each polymorphism showed no association with atopic eczema. The 2 polymorphisms were used to generate haplotypes, and a significant result was found for the -590C/-34C haplotype. However, after Bonferroni correction for multiple testing, the association became nonsignificant. Neither polymorphism predisposes to early-onset atopic eczema by itself, but suggestive linkage was found for the -590C/-34C haplotype in this study.     

Transforming growth factor-β2 polymorphisms are associated with childhood atopic asthma

BACKGROUND: Transforming growth factor (TGF)-beta plays an important role in the regulation of airway inflammation and remodelling in asthma. Recent studies suggest that TGF-beta(2) is a predominant isoform expressed in severe asthma and it is also associated with airway remodelling. OBJECTIVE: To determine whether the polymorphisms in TGF-beta(2) are associated with childhood atopic bronchial asthma in a Japanese population. METHODS: We identified a total of eight polymorphisms and characterized the linkage disequilibrium (LD) mapping of the gene. Three variants in the promoter and 3'UTR were genotyped, and we conducted an association study of TGF-beta(2) (childhood atopic asthma n=297, normal controls n=555). An association analysis of these variants and an expression and functional analysis were performed. RESULTS: 3'UTR 94862T >A was found to be significantly associated with the risk of childhood atopic asthma (P=0.00041). The -109-->ACAA ins promoter variant was also associated with the risk of childhood atopic asthma (P=0.0037). TGF-beta(2) expression was observed in both the normal and asthmatic bronchial epithelium, and both real-time PCR and an ELISA showed a significant basal and TGF-beta(1)-induced TGF-beta(2) expression in the bronchial epithelial cell line BEAS2B. Furthermore, the promoter variant -109-->ACAA ins increased the TGF-beta(2) promoter-reporter activity in BEAS2B cells. CONCLUSIONS: Our data suggest that TGF-beta(2) may therefore be involved in the development of childhood atopic asthma by means of functional genetic polymorphism. The polymorphisms in TGF-beta(2) may become important information for asthma susceptibility in children.     

Childhood atopic asthma: positive association with a polymorphism of IL-4 receptor alpha gene but not with that of IL-4 promoter or Fc epsilon receptor I beta gene

We examined the relative contributions of three representative candidate genes for atopy (Fc epsilon receptor I beta, IL-4, and IL-4 receptor alpha) to the development of atopic asthma. Four polymorphisms of the three candidate genes including Ile50Val and Gln551Arg of IL-4 receptor alpha, -590C/T of IL-4 promoter and Glu237Gly of Fc epsilon receptor I beta were studied in 100 patients with atopic asthma and 100 nonatopic controls in the northern Kyushu area in Japan. Among the four polymorphisms of the three candidate genes, the Ile50 allele of the IL-4 receptor alpha chain gene demonstrated an association with atopic asthma subjects (p = 0.044), especially in patients with onset at 2 years of age or earlier (p = 0.034) and in patients with moderate to severe atopic asthma (p = 0. 031). Gln551Arg of IL-4 receptor alpha, -590C/T of IL-4 promoter and Glu237Gly of Fc epsilon receptor I beta showed no association with atopic asthma. A slight linkage disequilibrium between Ile50Val and Gln551Arg polymorphisms of the IL-4 receptor alpha chain gene was observed in both patients and nonatopic controls. The identification of additional atopy genes in areas with a certain genetic background is essential for genetic diagnosis and to establish new therapeutic modalities for atopic asthma.     

Polymorphisms in the interleukin-4 and interleukin-4 receptor α chain genes confer susceptibility to asthma and atopy in a Caucasian population

BACKGROUND : IL-4 by binding to its receptor (IL-4R) is essential for the development of airway inflammation present in asthma, through the induction of IgE synthesis in B cells and differentiation of T cells to a Th2 phenotype. OBJECTIVE : To investigate the role of four common polymorphisms in the IL-4 (IL4-34CT and IL4-589CT) and IL-4Ralpha chain (IL4RAI50V and IL4RAQ576R) genes in conferring susceptibility to the development of atopy and/or asthma. METHODS : Two polymorphisms in the IL-4 gene promoter, IL4-34CT and IL4-589CT, and two polymorphisms in the IL-4Ralpha chain gene, IL4RAI50V and IL4RAQ576R, have been genotyped using PCR-based methods in 341 asthmatic families and in 184 non-asthmatic adults recruited from the south of England. RESULTS : Case-control analysis did not reveal differences in the distribution of the four polymorphisms between asthmatics and controls. However, the transmission disequilibrium test showed that the IL4-589 T allele was preferentially transmitted to asthmatic children (P=0.036) and that the IL4RAQ576 was preferentially transmitted to children with atopic asthma (P=0.018). Haplotype analysis showed a strong association between the IL4-34T/-589T haplotype and asthma per se (P=0.041), and a strong association between the IL4RA I50/Q576 haplotype and atopic asthma (P=0.006). CONCLUSION : Our data suggest that polymorphisms in the IL-4 and IL-4Ralpha chain genes might play a role both conferring susceptibility to and modulating severity of atopy and asthma.     

Analysis of the inducible nitric oxide synthase gene polymorphisms in Czech patients with atopic diseases

BACKGROUND: Nitric oxide (NO) is an important mediator of physiologic processes in the airways; it plays a significant role in the regulation of the T helper type 1/type 2 balance and contributes to the development of atopic diseases. OBJECTIVE: We analysed several polymorphisms mainly in the promoter region of the inducible NO synthase (NOS2, iNOS) gene and investigated their associations with asthma and/or atopic phenotypes. METHODS: We performed a case-control study in 994 subjects (661 patients with atopic disorders, with subgroups of 304 patients with allergic asthma, and 333 healthy individuals), matched for sex, living in the same geographical area. Screening for polymorphisms was performed by combination of PCR and direct sequencing analysis. RESULTS: We analysed 14 nucleotide sequence variants, seven most common of which were typed in quite large groups of our asthmatic, atopic and control populations. None of these seven frequent polymorphisms was associated with the phenotype bronchial asthma or other atopic diseases. Nevertheless, three from six common promoter polymorphisms showed a significant relation to feather's positivity (P value from 0.01 to 0.03) and the NOS2 608Leu variant was significantly associated with asthma severity [p(corr) = 0.0005; odds ratio (OR) = 5.00, 95% confidence interval (CI): 1.88-13.33]. In haplotype analysis, the most common -2447C/-1659C/-1026G/-0.7del/-277A/Ser608 haplotype was associated with a lower risk of asthma when compared with the common haplotypes with frequency more than 5% (P = 0.01, p(corr) < 0.05; OR = 0.65, 95% CI: 0.56-0.77). CONCLUSION: Our findings suggest that inducible NOS can play a role in atopic disorders, and several polymorphisms in its gene may be important for asthma protection or susceptibility.     

No linkage or association of five polymorphisms in the interleukin‐4 receptor α gene with atopic asthma in Italian families

The literature contains conflicting reports on the association of common variants of the interleukin (IL)‐4 receptor alpha (IL4RA) gene with atopic asthma. The purpose of the present study was to investigate the linkage and association of several gene polymorphisms with atopic asthma in a large series of well‐characterized individuals. Analysis of five polymorphisms (I50V, E375A, C406R, S478P and Q551R) of the IL4RA gene was performed in 823 individuals from 182 families with atopic asthmatic children from north‐east Italy. The subjects were tested for clinical asthma, total serum IgE level, skin prick test positivity to common aeroallergens, and bronchial hyperresponsiveness to methacholine. The frequency of the polymorphisms was similar to that reported for other populations. The 375, 406, 478 and 551 polymorphisms were in linkage disequilibrium, as previously reported. No linkage or transmission disequilibrium was observed in the families between any mutation and any of the phenotypes investigated. No multipoint haplotype was associated with any phenotype. In conclusion, the IL4RA gene does not seem to play an important role in genetic predisposition to atopic asthma in the population tested.     

Polymorphisms in the novel gene acyloxyacyl hydroxylase (AOAH) are associated with asthma and associated phenotypes

BACKGROUND: The gene encoding acyloxyacyl hydroxylase (AOAH), an enzyme that hydrolyzes secondary fatty acyl chains of LPS, is localized on chromosome 7p14-p12, where evidence for linkage to total IgE (tIgE) concentrations and asthma has been previously reported. OBJECTIVE: We hypothesized that variants in AOAH are associated with asthma and related phenotypes. Because both AOAH and soluble CD14 respond to LPS, we tested for gene-gene interaction. METHODS: We investigated the association between 28 single nucleotide polymorphisms throughout the AOAH gene and asthma, concentrations of tIgE, the ratio of IL-13/IFN-gamma, and soluble CD14 levels among 125 African Caribbean, multiplex asthmatic pedigrees (n = 834). Real-time PCR was used to assess whether AOAH cDNA expression differed with AOAH genotype. RESULTS: Significant effects were observed for all 4 phenotypes and AOAH markers in 3 distinct regions (promoter, introns 1-6, and the intron 12/exon 13 boundary/intron 13 region) by means of single-marker and haplotype analyses, with the strongest evidence for a 2-single-nucleotide-polymorphism haplotype and log[tIgE] (P = .006). There was no difference in AOAH expression levels by AOAH genotype for any of the markers. Comparing genotypic distributions at both the AOAH marker rs2727831 and CD14(-260)C >T raises the possibility of gene-gene interaction (P = .006-.036). CONCLUSION: Our results indicate that polymorphisms in markers within the AOAH gene are associated with risk of asthma and associated quantitative traits (IgE and cytokine levels) among asthmatic subjects and their families in Barbados, and there is an interactive effect on tIgE and asthma concentrations between an AOAH marker and the functional CD14(-260)C >T polymorphism. CLINICAL IMPLICATIONS: AOAH is a novel innate immunity candidate gene associated with asthma and related phenotypes in an African ancestry population.     

Upregulating promoter polymorphisms of RANTES relate to atopic dermatitis

It has been reported that a functional polymorphism in the promoter of the RANTES gene (-403G/A) is associated with atopic dermatitis in a German population. Although there are several reports on the association of RANTES promoter polymorphisms (-403G/A and -28C/G) with asthma, the association of these polymorphisms with atopic dermatitis has not yet been confirmed in other populations. We therefore aimed to test whether the RANTES promoter polymorphisms relate to atopic dermatitis in a well-defined Japanese population. We conducted an association study of upregulating promoter polymorphisms of RANTES (-403G/A and -28C/G) in 389 patients with atopic dermatitis and 177 healthy control subjects. There was a significant association between the upregulating variant of RANTES -28G and atopic dermatitis, while -403A variant showed a significant association with atopic dermatitis with high IgE productivity. These results support a role for RANTES promoter polymorphisms in susceptibility to atopic dermatitis.     

IL-5 and thromboxane A2 receptor gene polymorphisms are associated with decreased pulmonary function in Korean children with atopic asthma

BACKGROUND: Asthmatic airways undergo chronic inflammatory cell infiltration by T cells and eosinophils, which results in sustained airway hyperresponsiveness. IL-5 is important for eosinophil-induced airway inflammation and airway hyperresponsiveness. Thromboxane A2 and its receptor, TBXA2R, are involved in constriction of respiratory smooth muscles and may play a role in thickening and remodeling of airways, which contributes to the severity of asthma. The relationship between IL-5 and TBXA2R gene polymorphisms and pulmonary function in children with asthma has rarely been examined. OBJECTIVE: To determine whether IL-5 (T-746C) and TBXA2R (T924C) gene polymorphisms are associated with asthma phenotype and pulmonary function in Korean children with atopic and nonatopic asthma. METHODS: We conducted an association study between known polymorphisms of IL-5 (T-746C) and TBXA2R (T924C) and asthma phenotype and the parameters of atopy and pulmonary function in atopic and nonatopic Korean children with asthma. The subjects were 240 atopic children with asthma, 70 nonatopic children with asthma, and 106 nonatopic healthy children. Asthma phenotypes and bronchial responsiveness to methacholine were determined by a physician. IL-5 and TBXA2R gene polymorphisms were determined by genotyping by using PCR-RFLP assays. RESULTS: The genotype frequencies of IL-5 and TBXA2R polymorphisms did not differ between healthy controls and atopic or nonatopic children with asthma. A significant association was observed between the IL-5 polymorphism and forced expiratory flow at 25% to 75% of forced vital capacity (FEF 25-75% ; %; P = .002), and between the TBXA2R polymorphism and FEV 1 (%; P = .035) and FEF 25-75% (%; P = .042) in children with atopic asthma, whereas no such association between the polymorphisms and lung function was observed in nonatopic or control children. In atopic children with asthma, we identified a significant gene-gene interaction in that the combination of the IL-5 (T-746C) and TBXA2R (T924C) mutant alleles was shown to be associated with reduced pulmonary function as determined by FEF 25-75% (%) measurement. CONCLUSION: The current study indicates that IL-5 (T-746C) and TBXA2R (T924C) polymorphisms alone are associated with spirometric markers of asthma severity, whereas they are not associated with presence of asthma per se. In addition, the data suggest that an interaction between IL-5 and TBXA2R genes may contribute to the severity of asthma, especially atopic asthma. These results suggest that IL-5 and TBXA2R genes may be disease-modifying genes in Korean children with atopic asthma.     

Association of TNF haplotypes with asthma, serum IgE levels, and correlation with serum TNF-alpha levels

Both biochemical and genetic evidence have implicated the genes for TNF-alpha (TNFA) and lymphotoxin-alpha (LTA) in atopic asthma. Here, we report for the first time the association of their genotypes and haplotypes with atopic asthma in Indian populations. We genotyped seven single nucleotide polymorphisms, encompassing the two genes, in patients and control subjects in two independent cohorts. Serum TNF-alpha levels of selected individuals were measured and correlated with genotypes and haplotypes. The A allele of the TNFA-863C > A polymorphism was associated with reduced risk of asthma (P = 0.002 and 0.007 in Cohorts A and B, respectively), reduced TsIgE levels (P = 0.0024 and P = 0.0029 in Cohorts A and B, respectively), and reduced serum TNF-alpha levels (P < 0.05). A marginal association was also observed for LTA_NcoI polymorphism with asthma and TsIgE levels. Furthermore, analysis using HAPLO. STATS showed significant differences in the major haplotype frequencies (> 3%) between patients and control subjects (P = 0.002 and P = 0.006 for Cohorts A and B, respectively). Individually, the haplotype GATCCG was the most frequent in patients (P = 0.0029 and P = 0.0025 for Cohorts A and B, respectively), and was associated with high TsIgE and serum TNF-alpha levels, whereas AACACG was the most frequent in the control subjects (P = 0.0032 and P = 0.022 for Cohorts A and B, respectively), and was associated with low TsIgE and serum TNF-alpha levels. We also report here that the C > A substitution at position -863 of the TNFA influences the binding of nuclear proteins in electrophoretic mobility shift assay experiments. Thus, the TNFA-863C > A polymorphism in the promoter region of TNFA may influence TNF-alpha expression and affect TsIgE levels and susceptibility to asthma.     

Uteroglobin-related protein 1(UGRP1) gene polymorphisms and atopic asthma in the Indian population

BACKGROUND: The secretory protein, uteroglobin-related protein 1 (UGRP1), is mainly expressed in the lung and trachea and has recently been implicated in asthma. The -112 G to A transition in the promoter was reported to be associated with asthma in the Japanese population. However, this has not been replicated in other studies. The aim of this study was to find the association of UGRP1 gene polymorphisms with atopic asthma in the Indian population using a case-control (NP=165, NC=160) and a family-based (60 trios) design. METHODS: Polymorphisms in the promoter region and the first exon and first intron of the UGRP1 gene were determined by direct sequencing. RESULTS: The previously identified G-112A and C222A polymorphisms were found to be in complete linkage disequilibrium (LD) (D'=1) in our population. However, no new polymorphism has been identified in this region. When G-112A polymorphism was analyzed in the cases and controls, no significant difference was observed either at the allele (p=0.68) or at the genotype (p=0.83) levels. Moreover, in our family-based study, we observed no significant deviation of allelic transmission from random proportions (p=0.41). Similarly, when we analyzed our genotypic results for serum total IgE levels, no significant association was observed, in both case-control as well as family-based designs. CONCLUSIONS: Our results suggest that the G-112A and C222A polymorphisms do not play a significant role in the genetic predisposition of UGRP1 gene in atopic asthma in the Indian population.     

Mutation screening of interferon regulatory factor 1 gene (IRF-1) as a candidate gene for atopy/asthma.

BACKGROUND: IL-4 gene cluster on chromosome 5 contains several candidate genes for atopy and asthma. Several independent studies have shown evidence for linkage between the markers flanking IL-4 gene cluster and asthma and/or asthma-related traits. Interferon regulatory factor 1 (IRF-1) is located approximately 300 kb telomeric to IL-4 and recent study reveals that IRF-1 deficiency results in an elevated production of Th2-related cytokines and a compensatory decrease in the expression of native cell- and Th1-related cytokines. OBJECTIVE: To determine if there are any mutations associated with the development of atopy and asthma present in the coding exons and 5' flanking region of the IRF-1 gene. METHODS AND RESULTS: We have screened the promoter and coding regions of the IRF-1 gene in atopic asthmatics and controls by SSCP method. We found three novel nuclear variants (the -300G/T and 4396 A/G polymorphisms and the 6355G > A rare variant) in the IRF-1 gene. No variants causing amino acid alterations of IRF-1 were detected. The -300G/T polymorphism was in nearly complete linkage disequilibrium with the 4396 A/G polymorphism. An association between the 4396 A > G polymorphism and atopy/asthma was examined by transmission disequilibrium test in 81 asthmatic families. Either of 4396 A or 4396G alleles was not significantly preferentially transmitted to atopy- or asthma-affected children. CONCLUSION: The IRF-1 gene is less likely to play a substantial role in the development of atopy and asthma in the Japanese population.     

Association between a C+33T polymorphism in the IL-4 promoter region and total serum IgE levels

Susceptibility to asthma and other atopic diseases is known to be associated with elevated total IgE levels. Several investigators have linked the interleukin-4 (IL-4) gene and nearby markers located on chromosome 5q to elevated total IgE levels. A single nucleotide polymorphism in the IL-4 gene promoter region (C+33T) has recently been identified. As part of an effort to identify genetic variants contributing to the susceptibility to elevated total serum IgE levels, an association analysis of a newly identified promoter polymorphism (C+33T) with total serum IgE levels was conducted. The study was conducted using 240 Japanese subjects (120 asthmatics and 120 healthy controls). The IL-4 C+33T polymorphism was genotyped by PCR-restriction fragment length polymorphism analysis. The frequency of the T allele was 0.675 in asthmatic subjects and 0.671 in healthy controls. An ANOVA model adjusted for age, sex and disease status suggested a genetic association of C+33T polymorphism with elevated total serum IgE levels (P < 0.05). The data suggest that IL-4 promoter C+33T polymorphism may be one of the genetic polymorphisms that explain genetic linkage or association between elevated total serum IgE levels and markers on chromosome 5q.     

Gene–gene interaction between IL-13 and IL-13Rα1 is associated with total IgE in Korean children with atopic asthma

Interleukin (IL)-13, which is essential for IgE synthesis, mediates its effects by binding with a receptor composed of IL-4Rα and IL-13Rα1. We investigated the effects of IL-13 and IL-13Rα1 polymorphisms in Korean children with asthma, and whether these have been associated with IgE production. We enrolled 358 atopic asthmatic, 111 non-atopic asthmatic, and 146 non-atopic healthy children. IL-13 and IL-13Rα1 genotypes were identified using the PCR-RFLP method. There was an association between the asthma susceptibility and homozygosity for risk allele of IL-13 G+2044A. In children with atopic asthma, risk alleles in IL-13 (A−1512C and C−1112T) and IL-13Rα1 (A+1398G) showed increased total IgE (P=0.012, 0.015 and 0.017, respectively). Three-loci haplotype analysis for IL-13 showed that the haplotype composed of −1512C, −1112T and +2044A was associated with higher total IgE than other tested haplotypes in children with atopic asthma (P=0.003). The gene–gene interaction between risk alleles of each IL-13 promoter polymorphism and IL-13Rα1 polymorphism was associated with higher total IgE in children with atopic asthma (P=0.002, 0.010). These findings indicate that the IL-13 G+2044A is associated with asthma development and the IL-13 and IL-13Rα1 polymorphisms may interact to enhance IgE production.Hyo-Bin Kim, and Yong-Chul Lee contributed equally to this work. This work was supported by grants from the Asan Institute for Life Science (2005-091) and the National Research Laboratory Program, Korea Science and Engineering Foundation and by Korea Research Foundation Grants funded by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF-2005-201-E00014), Republic of Korea.     

Association study of the C3 gene with adult and childhood asthma

Bronchial asthma (BA) is a multifactorial disorder, the development of which is affected by both environmental and genetic factors. The complement system plays an important role in immunological response against invading microorganisms. It has been shown that complement-C3-deficient mice have reduced inflammation of asthmatic airways. Previously, we reported the association of four single nuclear proteins (SNPs) in the exons of the C3 gene with childhood and adult BA. The C3 gene, however, is a large gene, and functional SNPs associated with susceptibility to BA have not yet been identified. We analyzed 26 SNPs in the C3 gene and its promoter region to narrow down the regions showing association with childhood and adult BA. Childhood and adult atopic BA patients and healthy child and adult controls were recruited from urban cities in Japan and genotyped. In SNP analysis, an SNP (SNP24, rs11569562) located in intron 31 of the C3 gene was associated with adult BA [corrected P (Pcor) = 0.030]. In linkage disequilibrium (LD) block 4 spanning exons 24-41, the frequency of the CCC haplotype in adult BA was significantly higher than that in adult controls (Pcor = 0.038). Neither the SNP nor the haplotype showing association with adult BA demonstrated a significant association with serum total immunoglobulin E (IgE) level in BA patients and controls. Our results suggest that LD block 4 confers susceptibility to adult BA with mechanisms relevant to the effector phase of allergic inflammation.