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

Comments on 'Association of FcϵRIβ polymorphisms with risk of asthma and allergic rhinitis: evidence based on 29 case-control studies'

Guo et al. (Bioscience Reports (2018) 38, BSR20180177) published a meta-analysis concerning the association between five single nucleotide polymorphisms (SNPs) in the high-affinity IgE receptor β chain (FcεRIβ) gene, namely E237G, -109 C/T, RsaI_in2, RsaI_ex7, and I181L, and risk of asthma and allergic rhinitis based on available 29 case–control studies. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of association of SNPs in FcεRIβ gene with allergic diseases risk. They found that FcεRIβ E237G (237G vs. 237E: OR = 1.28, 95% CI = 1.06–1.53) and −109 C/T (TT vs. CT+CC: OR = 1.58, 95% CI = 1.26–1.98) were risk factors for allergic diseases. Guo et al.’s findings are interesting, but we found that several issues should be clarified after carefully reading the paper. Here, we intended to comment on these data clarifications.

Interleukin 4 gene polymorphism (-589C/T) and the risk of asthma: a meta-analysis and met-regression based on 55 studies

BACKGROUND

Numerous investigations have previously evaluated the association of interleukin (IL) 4 gene polymorphisms and the risk of asthma, conferring inconsistent results. To resolve the incongruent outcomes yielded from different single studies, we conducted the most up-to-date meta-analysis of IL4 gene -589C/T (rs2243250) polymorphism and susceptibility to asthma.

METHODS

A systematic literature search was performed in ISI web of science, Scopus, Medline/PubMed databases prior to September 2020, and the pooled odds ratio (OR) and their corresponding 95% CI were calculated to determine the association strength.

RESULTS

Literature search led to retrieving of 49 publications (55 case-control studies) containing 9572 cases and 9881 controls. It was revealed that IL4 gene -589C/T polymorphism increased the risk of asthma across all genetic models, including dominant model (OR = 1.22), recessive model (OR = 1.17), allelic model (OR = 1.21), and TT vs. CC model (OR = 1.34), but not the CT vs. TT model. The subgroup analysis by age indicated that IL4 gene -589C/T polymorphism was significantly associated with asthma risk in both pediatrics and adults. Additionally, the subgroup analysis by ethnicity revealed significant association in Asian, American, and Europeans. Finally, subgroup analysis by East Asian and non-East Asian populations indicated significant associations.

CONCLUSIONS

The current meta-analysis revealed that IL4 gene -589C/T polymorphism was a susceptibility risk in both pediatrics and adults in the whole and different ethnic groups.

Association of FcεRIβ polymorphisms with risk of asthma and allergic rhinitis: evidence based on 29 case-control studies

Purpose: Accumulating evidence has shown that allergic diseases are caused by a complex interaction of genetic and environmental factors, some single nucleotide polymorphisms (SNPs) existing in high-affinity IgE receptor β chain (FcεRIβ) are potential risk factors for allergic diseases. However, the results have been inconsistent and inconclusive due to the limited statistical power in individual study. Thus, we conducted a meta-analysis to systematically evaluate the association between FcεRIβ SNPs and allergic diseases risk.

Methods: Eligible studies were collected from PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, and WanFang databases. Pooled odd ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to assess the strength of the relationships between five polymorphisms (E237G, -109 C/T, RsaI_in2, RsaI_ex7, and I181L) and the risk of allergic diseases by using five genetic models. In addition, the stability of our analysis was evaluated by publication bias, sensitivity, and heterogeneity analysis.

Results: Overall, a total of 29 case–control studies were included in this meta-analysis. We found that E237G (B vs. A: OR = 1.28, 95% CI = 1.06–1.53, P<0.001, I² = 63.1%) and -109 C/T (BB vs. AA + AB: OR = 1.58, 95%CI = 1.26–1.98, P<0.001, I² = 66.4%) were risk factors for allergic diseases.

Conclusion: Our meta-analysis suggests that polymorphisms in FcεRIβ may be associated with the development of allergic diseases.

Gene Polymorphism of Interleukin-4, Interleukin-4 Receptor and STAT6 in Children with Atopic Dermatitis in Taif, Saudi Arabia

AIM OF STUDY

This work was performed to evaluate the level of IL-4, and to clarify the role of IL-4 gene polymorphism at position cytosine -590-to-thyamine (C-590T), IL-4Rα gene polymorphism at position adenine +4679-to-guanine (A+4679G) [isoleucine-50-valine (I50V)] and STAT6 gene polymorphism at position guanine 2964-to-adenine (G2964A) in Saudi children with non-atopic dermatitis (non-AD) and atopic dermatitis (AD) to identify their role in the pathogenesis of these diseases.

SUBJECTS AND METHODS

This study included 150 children: 50 healthy children as controls, 50 with non-AD, and 50 with AD. They were subjected to full clinical examination, complete blood picture, skin prick test, and determination of serum interleukin-4 (IL-4) and total immunoglobulin-E (IgE) levels. Detection of interleukin-4 gene (C-590T), interleukin-4 receptor alpha gene (A+4679G) (I50V), and STAT6 gene (G2964A) polymorphisms were performed by PCR-based restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There was a significant (P < 0.01) association between genotype and allele frequencies of IL-4Rα (A+4679G) (I50V) polymorphism in the AD group (but not non-AD group). Moreover, there was a significant association between genotype and allele frequencies of the STAT6 (G2946A) polymorphism in the non-AD (P < 0.05) and AD (P < 0.01) groups. On the other hand, there was no significant association between genotype and allele frequencies of the (C-590T) polymorphism in the non-AD group and AD group. There was a significant (P < 0.001) higher total IgE level in patients compared to the controls. Moreover, the mean values of total IgE were significantly different among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively, in all the studied groups. On the other hand, there was no significant difference of serum IL-4 levels among all the studied patients, or among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively.

CONCLUSION

IL-4Rα gene (I50V) and STAT6 gene (G2964) polymorphisms may play a role in development of eczema; however, the IL-4 gene polymorphism (C-590T) had no relationship with susceptibility to the disease among Saudi children.

Interleukin-4 -589C/T Polymorphism is Associated with Increased Pediatric Asthma Risk: A Meta-Analysis

IL4 -589C/T polymorphism has been implicated in susceptibility to pediatric asthma risk. Several studies investigated the association of this polymorphism with pediatric asthma in different populations. However, the results were contradictory. A meta-analysis was conducted to assess the association between IL4 -589C/T polymorphism and pediatric asthma risk. Databases including Pubmed, EMBASE, Chinese National Knowledge Infrastructure (CNKI), and Wangfang were searched to find relevant studies. Odds ratios (ORs) with 95 % confidence intervals (CIs) were used to assess the strength of associations. A significant association was found between IL4 -589C/T polymorphism and pediatric asthma risk (OR=1.53, 95% CI 1.27-1.85). In the subgroup analyses by ethnicity, the significant association was found among Caucasians (OR=1.70, 95% CI 1.38-2.09) and Asians (OR=1.58, 95% CI 1.23-2.04). Our results suggested that IL4 -589C/T polymorphism conferred a risk factor of pediatric asthma.

Association between promoter polymorphisms of interleukin-4 gene and allergic rhinitis risk: a meta-analysis

The relationship of interleukin-4 (IL-4) C-33T and C-590T (C-589T) gene polymorphisms with allergic rhinitis was analyzed. Data about the case control studies of IL-4 gene promoter polymorphisms [C-33T and C-590T (C-589T)] and their association with allergic diseases and correlation between serum IL-4 levels and allergic rhinitis were retrieved. The Stata 12.0 statistical software was applied to analyze the correlation between IL-4 gene polymorphisms and allergic rhinitis. The meta-analysis result of TT/CC genotype of -590 (-589) polymorphism showed a significant association with allergic diseases [OR=1.93, 95% CI (1.61-2.31), P=0.00]. Meta-analysis of the TT+TC versus CC genotype of IL-4 C-33/T polymorphism revealed significant associations with allergic diseases [OR=3.23, 95% CI (1.13-9.25), P=0.03]. Meanwhile, there was a significant correlation between serum IL-4 levels and allergic rhinitis [OR=2.52, 95% CI=(1.80-3.23), P=0.00]. IL-4 gene -590 TT genotype may increase the risk of allergic rhinitis and the T allele mutation of -33 might be correlated with allergic rhinitis.

Molecular Mechanism of Allergy-Related Gene Regulation and Hematopoietic Cell Development by Transcription Factors

Transcriptional regulation for the genes encoding alpha- and beta-chains of the high-affinity receptor for IgE (FcepsilonRI) have been analyzed in mast cells and regulatory mechanisms are beginning to be elucidated. Transcription factors GATA-1 and PU.1 cooperatively transactivate the alpha-chain gene, and three transcription factors, GATA-1, Oct-1, and MZF-1, are involved in regulation of beta-chain gene expression. No single nucleotide polymorphisms (SNPs) that are functionally related to the allergic diseases have been identified in coding regions of the alpha- and beta-chain genes in a definitive way. However, recent studies on SNPs in the promoter regions have revealed that these genes are probable candidates for new types of allergy-related genes whose transcription levels are affected by transcription factors which discriminate SNPs in the promoters. Another interesting finding on transcription factors functioning in mast cells is that the expression level of PU.1 determines cell fate between mast cells and monocytes.

Association of the MS4A2 gene promoter C-109T or the 7th exon E237G polymorphisms with asthma risk: a meta-analysis

BACKGROUND AND OBJECTIVE

A large number of studies have examined the association between the Membrane-spanning 4 domains, superfamily A, number 2 (MS4A2) gene C-109T (rs1441586) or E237G (rs569108) variants and asthma risk. However, the results are inconsistent and inconclusive. To derive a more precise estimation, a meta-analysis was performed.

METHODS

Meta-analyses were conducted with the data from case-control association studies (24 studies with 4496 asthmatics and 4571 controls for E237G variant and 9 studies including 2005 cases and 1868 control for C-109T polymorphisms, respectively). Random-effects model was used to calculate summary odds ratios (ORs).

RESULTS

For the MS4A2 gene E237G variant, no significant associations with asthma were found in overall population; we observed an elevated risk of atopic asthma among subjects with the 237G allele (OR=1.341, 95% CI: 1.039-1.732 for G versus E and OR=1.374, 95% CI: 1.032-1.828 for EG+GG versus EE) in the stratified meta-analysis. As for the MS4A2 gene C-109T polymorphism, no significant associations with asthma risk were observed in the total population; in subgroup analysis by ethnicity of subjects we found increased asthma risk among Asians carrying T allele (OR=1.140, 95% CI: 1.019-1.276 for T versus C and OR=1.359, 95% CI: 1.029-1.794 for TT versus CC).

CONCLUSIONS

Data indicated that the MS4A2 gene E237G variant may be a risk factor for developing atopic asthma and the promoter -109T allele is a potential risk factor of asthma in Asians.

Association between interleukin-4 receptor α chain (IL4RA) I50V and Q551R polymorphisms and asthma risk: an update meta-analysis

BACKGROUND

The associations between the interleukin-4 receptor α chain (IL4RA) I50V and Q551R polymorphisms and asthma risk remained controversial.

METHODS

We searched the Pubmed, Embase, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases for studies published before February 2013. The strengths of the associations were calculated using odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 50 studies were included in this meta-analysis. There was a significant association between the IL4RA I50V polymorphism and asthma risk in a dominant genetic model (OR = 1.13, 95% CI 1.04-1.23, P = 0.005). The IL4RA Q551R polymorphism was associated with a significantly elevated asthma risk in a recessive genetic model (OR = 1.46, 95% CI 1.22-1.75, P<0.0001). Subgroup analyses found that the IL4RA I50V polymorphism was significantly associated with asthma risk in Asians (OR = 1.72, 95% CI 1.31-2.25, P<0.0001), pediatric asthma risk (OR = 1.50, 95% CI 1.13-1.99, P = 0.005), and atopic asthma risk (OR = 1.88, 95% CI 1.27-2.79, P = 0.002).

CONCLUSIONS

The results of this meta-analysis suggested that the IL4RA I50V and Q551R polymorphisms may be risk factors for developing asthma.

The interleukin-4 -589C/T polymorphism and the risk of asthma: a meta-analysis including 7,345 cases and 7,819 controls

BACKGROUND

A number of studies assessed the association of -589C/T polymorphism in the promoter region of interleukin-4 (IL-4) with asthma in different populations. However, the results were contradictory. A meta-analysis was conducted to investigate the association between polymorphism in the IL-4 and asthma susceptibility.

METHODS

Databases including Pubmed, EMBASE, Wanfang Database, China National Knowledge Infrastructure (CNKI) and Weipu Database were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

RESULTS

Thirty-four studies involving 7345 cases and 7819 controls were included. Overall, significant association between -589C/T polymorphism and asthma was observed for TT+CT vs. CC (OR=1.26; 95% CI 1.12-1.42; P=0.0001; I(2)=26%). In the subgroup analysis by ethnicity, significant associations were found among Asians (OR=1.36; 95% CI 1.07-1.73; P=0.01; I(2)=0%) and Caucasians (OR=1.30; 95% CI 1.09-1.54; P=0.004; I(2)=53%) but not among African Americans (OR=1.20; 95% CI 0.72-2.00; P=0.48; I(2)=48%). In the subgroup analysis by atopic status, no significant association was found among atopic asthma patients (OR=1.20; 95% CI 0.92-1.34; P=0.27; I(2)=6%) and non-atopic asthma patients (OR=0.97; 95% CI 0.73-1.28; P=0.81; I(2)=0%).

CONCLUSIONS

This meta-analysis suggested that the IL-4 -589C/T polymorphism was a risk factor of asthma.

Association between the interleukin-4 gene C-589T and C+33T polymorphisms and asthma risk: a meta-analysis

BACKGROUND AND AIMS

A large number of studies have investigated the correlation between the interleukin (IL)-4 C-589T and C+33T polymorphisms and asthma susceptibility. However, the results are inconsistent. The objective of this study is to explore the association between the IL-4 C-589T and C+33T polymorphisms and asthma risk using meta-analysis.

METHODS

A total of 35 studies (31 concerning C-589T polymorphism and asthma risk with 4737 asthmatics and 6389 controls and 14 studies regarding C+33T polymorphism and asthma risk with 2544 asthmatics and 4049 controls) were included in this meta-analysis.

RESULTS

The IL-4 C-589T polymorphism was associated with increased asthma risk in a dominant genetic model (odds ratio [OR] [95% confidence interval (CI)] = 1.284 [1.131-1.459] for TT + TC vs. CC). In the subgroup analyses by ethnicity, age and atopic status of asthmatics, significantly increased risks of asthma were found both in Asians (OR [95% CI] = 1.301 [1.003-1.689]) and Caucasians (OR [95% CI] = 1.314 [1.061-1.628]) and in both adults (OR [95% CI] = 1.299 [1.098-1.537]) and children (OR [95% CI] = 1.464 [1.044-2.052]). As for the C+33T polymorphism, the results showed that it was correlated with elevated asthma risk in a recessive genetic model (OR [95% CI] = 1.744 [1.215-2.504] for TT vs. CT + CC). After stratifying analyses by ethnicity, age and atopic status of asthmatics, significantly increased asthma risks were observed in Asians (OR [95% CI] = 1.223 [1.037-1.442]), Caucasians (OR [95% CI] = 3.036 [1.224-7.529]), and children (OR [95% CI] = 1.300 [1.075-1.573]) in a recessive genetic model.

CONCLUSIONS

This meta-analysis suggests that the IL-4 C-589T and C+33T polymorphisms may be risk factors for asthma.

Association between the interleukin-4, interleukin-13 polymorphisms and asthma: a meta-analysis

A numbers studies had been reported that the polymorphisms in the Interleukin 4 (IL-4) and Interleukin 13 (IL-13) genes were associated with susceptibility to asthma. However, the results were inconsistent and inconclusive. We carried out a meta-analysis of case-control genetic association studies to assess whether the combined data showed this association by using a genetic model-free approach. Thirty studies (total 12,781 asthma and 11,500 controls) for the IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A with asthma were included in the meta-analysis. The results indicated that there were an association between the IL-4 C-33T (P = 0.006) and C-589T (P = 0.04), IL-13 C-1112T (P = 0.002) and G+2044A (P = 0.04) and susceptibility to asthma. And the definition of asthma subgroup meta-analysis demonstrates that the IL-4 C-33T is not associated with nonatopic or atopic, and IL-4 C-589T and IL-13 C-1112T polymorphisms are not associated with atopic. In the ethnicity subgroup meta-analysis, the IL-4 -589T (P = 0.003) and the IL-13 -1112T (P < 0.00001) alleles are associated with asthma among Caucasian, but not on the IL-13 +2044A allele. In conclusion, IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A could be proposed as asthma susceptible SNPs. Further investigation in larger studies and meta-analysis is required.

Interleukin-4 rs2243250 polymorphism is associated with asthma among Caucasians and related to atopic asthma

Published data on the association between interleukin-4 (IL-4) rs2243250 (C-589T) polymorphism and asthma susceptibility are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 17 studies with 3037 asthma patients and 3032 healthy controls were included. Overall, significantly elevated asthma risk was associated with IL-4 T allele when all studies were pooled into the meta-analysis (CT vs. CC: OR=1.187, 95% CI=1.016-1.387; dominant model: OR=1.213, 95% CI=1.046-1.405). In the subgroup analysis by ethnicity, significantly increased risk was only found for Caucasians (TT vs. CC: OR=1.591, 95% CI=1.032-2.452; dominant model: OR=1.292, 95% CI=1.028-1.624). When stratified by asthma type, statistically significantly elevated risk was only found in atopic asthma group (dominant model: OR=1.313, 95% CI=1.033-1.667). Despite some limitations, this meta-analysis suggests that T allele at position -589 of the IL-4 gene promoter region is a low-penetrant risk factor for asthma development especially for Caucasians and atopic type.

Polymorphic variants of interleukin-13 R130Q, interleukin-4 T589C, interleukin-4RA I50V, and interleukin-4RA Q576R in allergic rhinitis: A pilot study

The development of allergic rhinitis is considered to be caused by the complex interactions between genetic predisposition and environmental factors. Polymorphisms in the interleukin (IL)-13/4/4RA pathway have previously been shown to be associated with atopic diseases. The purpose of this study was to determine the association between IL-13 R130Q, IL-4 T589C, IL4 receptor alpha (IL-4RA) I50V, or IL-4RA Q576R polymorphisms and risk of allergic rhinitis in a hospital-based Malaysian population. A case-control pilot study was undertaken and genotyping of these polymorphisms was performed using polymerase chain reaction-restriction fragment length polymorphism on 54 allergic rhinitis patients and 45 healthy individuals. Polymorphism of IL-13 R130Q showed significant difference in genotype (p = 0.048) and allele (p = 0.002) frequencies in allergic rhinitis when compared with healthy controls. Individuals who were GA heterozygotes (adjusted odds ratio [OR(adj)] = 3.567; 95% CI, 1.211-10.509), and carriers of A allele genotype (OR(adj) = 3.686; 95% CI, 1.300-10.451) and A allele (OR(adj) = 3.071; 95% CI, 1.514-6.232) had an elevated risk of developing allergic rhinitis. The genotype and allele frequencies of IL-4 T589C, IL-4RA I50V, and IL-4RA Q576R polymorphisms were not significantly different between the allergic rhinitis patients and normal healthy individuals and did not show an associated risk with allergic rhinitis. Our findings indicate that polymorphic variant of IL-13 R130Q appears to be associated with increased risk for development of allergic rhinitis in a hospital-based Malaysian population but not IL-4 T589C, IL-4RA I50V, and IL-4RA Q576 polymorphisms. Additional studies using larger sample size are required to confirm our findings and its exact role in allergic rhinitis.

Gene-environment interaction between interleukin-4 promoter and molds in childhood asthma

PURPOSE

To assess the role of gene-environment interaction between interleukin (IL)-4 promoter and mold exposure on the development of asthma.

METHODS

We conducted a cohort-based, incident, case-control study. The case group consisted of 188 children with new asthma and the control group (n = 376) was matched for age and gender. The outcome of interest was the development of asthma over the 6-year study period. The studied determinants were three polymorphisms of IL-4 promoter (TT, CT, and CC) and three indicators of exposure including histories of water damage, presence of visible molds, and perceived mold odor in the home.

RESULTS

Apparent joint effects between IL-4 promoter and mold exposure were observed on both additive and multiplicative scales. Specially, the risk of asthma was significantly associated with children carrying the CT genotype and visible mold exposure comparing with those carrying the TT genotype without any exposure indicator (adjusted odds ratio [OR], 2.14; 95% confidence interval [CI], 1.05-4.34; modified Rothman synergy index for directly use of odds and OR [s] = 1.41; P for interaction = .03). A similar tendency was found (s = 1.30; P for interaction = .04) for children who were exposed to mold odor and carried CT genotype (adjusted OR, 1.99; 95% CI, 1.03-4.41).

CONCLUSIONS

The results of this study suggest that gene-environment interactions between the IL-4 promoter and an indoor mold problem may play an important role in childhood asthma.

Interleukin-4 receptor polymorphisms in asthma and allergy: relation to different disease phenotypes

AIM

Inheritance and genetic factors are supposed to influence susceptibility to asthma and allergy. We tested if single nucleotide polymorphisms (SNPs) in the IL4R gene were associated with susceptibility to such diseases, or if they were related to the phenotypic presentation of asthma and allergic rhinoconjunctivitis (ARC).

METHODS

Three hundred and nine 12- to 13-year-old children were included. Six SNPs in the IL4R were analysed in response to current allergic disease, and to presentation of specific asthma and ARC phenotypes. Questionnaires were used to determine allergic disease status, and skin prick tests to evaluate sensitization to common airborne allergens.

RESULTS

Less eczema was seen in individuals with the AA-genotype of rs2057768, and less ARC among those with the AA-genotype of rs2107356, especially ARC associated with sensitization to pollen. The AA-genotype of rs2057768 and the TT genotype of rs3024632 were associated with a specific asthma phenotype.

CONCLUSION

Variations within the IL4R gene are associated with allergic diseases in children, preferably with eczema and disease phenotypes of ARC and asthma.

Endogenous suppression of mast cell development and survival by IL-4 and IL-10

Mast cell development is an important component of atopic and chronic inflammatory diseases such as asthma, multiple sclerosis, rheumatoid arthritis, and atherosclerosis. In this study, we found that IL-4 and IL-10 were produced constitutively in cultures of developing mast cells, correlating with mast cell purity. Deletion of either gene increased mast cell numbers and Fc epsilon RI expression during culture in IL-3 + stem cell factor (SCF). By adding exogenous IL-4 and IL-10 to bone marrow (BM) cultures containing IL-3 + SCF, we found that IL-4 + IL-10 suppressed mast cell development through mechanisms not used by either cytokine alone. IL-4 + IL-10 elicited a rapid cell death coincidental with reduced Kit receptor expression and signaling and enhanced mitochondrial damage and caspase activation. IL-4 or IL-10 costimulation, unlike either cytokine alone, altered mast cell ontogeny to yield predominantly macrophages in cultures that typically produce mast cells. This effect was observed consistently with unseparated BM cells, purified mouse BM stem cells, and erythrocyte-depleted human umbilical cord blood cells. These experiments demonstrated a major role for Stat6 and Stat3, but not the Stat3-induced transcriptional repressor Ets variant gene 3. Genetic background was also a critical factor, as BALB/c-derived BM cells were completely resistant to IL-10-mediated killing and expressed lower levels of IL-10R. Collectively, these results support the theory that IL-4 and IL-10 function as endogenous regulators of mast cell progenitor development, consistent with a role in immune homeostasis. Loss of this homeostasis, perhaps via genetic polymorphism, could contribute to the etiology of mast cell-associated disease.

Association between C-589T polymorphisms of interleukin-4 gene promoter and asthma: a meta-analysis

BACKGROUND

A number of studies of genetic epidemiology have assessed the association of C-589T (also referred to as C-590T; rs number, 2243250) polymorphisms in the promoter region of interleukin-4 (IL-4) gene with asthma in different populations. However, the results are inconsistent and inconclusive.

OBJECTIVES

We performed a meta-analysis of the association between C-589T polymorphisms of IL-4 and asthma with the following objectives: to estimate the magnitude of the gene effect and the possible mode of inheritance.

METHODS

A genetic model-free approach was used to perform a meta-analysis. Asthma (atopy status nondefined), nonatopic and atopic asthma subgroups were separately analyzed. Heterogeneity and publication bias were also explored.

RESULTS

Our meta-analysis summarized the evidence regarding the association between C-589T polymorphisms in the promoter region of IL-4 gene and asthma. When all asthma groups were pooled, a significant association of increased asthma risk and T allele was found. In subgroup analysis, our results indicated a significant association and a recessive genetic mode of C-589T polymorphisms of IL-4 with atopic asthma. The CC genotype was about 21 percent less likely to have atopic asthma than the genotype CT and TT. However, C-589T polymorphisms were not significantly associated with nonatopic asthma.

CONCLUSIONS

This meta-analysis suggests there may be an important effect of single nucleotide polymorphisms (SNPs) in the promoter region of IL-4 gene on the pathogenesis of atopic asthma. This warrants further investigation in larger studies and meta-analysis.

A STAT6 gene polymorphism is associated with high infection levels in urinary schistosomiasis

Th2-mediated immunity is critical for human defence against schistosome, and susceptibility to infection is controlled by a major genetic locus, mapped on the 5q31-q33 region comprising the genes IL4, IL5 and IL13. We have reported an association between the rs1800925 polymorphism in the IL13 promoter and infection levels in a Dogon population (693 subjects in Ségué and 148 in Boul), where Schistosoma haematobium is endemic. In the same population, we investigated whether other polymorphisms in genes involved in type 2 cytokine immune response could affect susceptibility to schistosome infection. By logistic regression analysis, we found an association between a single-nucleotide polymorphism (SNP) in the STAT6 gene (rs324013) and infection levels (P=0.04). We confirmed this association in analyses restricted to subjects under 20 years age and living in Boul, the village with the highest levels of infection (P=0.005). We detected an additive effect of the rs324013 and rs1800925 polymorphisms (P=0.011). These SNPs were not strongly correlated with any other tested markers surrounding the two genes. Furthermore, electrophoretic mobility shift assay has shown that both polymorphisms affect transcription factor binding. These results are consistent with the Th2 cytokine pathway enhancing resistance to schistosome infection in humans.

Genetics of asthma: potential implications for reducing asthma disparities

Although genetic factors may partly explain the differences in asthma prevalence, morbidity, and mortality among ethnic groups in the United States, few studies of the genetics of asthma have included members of ethnic minority groups. Only one genome-wide linkage analysis of asthma and/or asthma-related phenotypes (conducted by the Collaborative Study on the Genetics of Asthma) has included any members of ethnic minority populations. The interpretation of the findings of genetic association studies of asthma in ethnic minority groups is complicated by reduced statistical power due to small sample sizes; the failure to correct for multiple comparisons; a lack of homogeneity of the populations studied with regard to area of residence, ancestral background, and/or country of origin; a lack of measurement of relevant environmental exposures; and (for case-control studies of genetic association) a lack of detection and control of potential population stratification. Genetic studies may improve our understanding of asthma and lead to new methods to prevent, diagnose, and treat this disease. Limited study of asthma genetics in ethnic minority populations is unacceptable, as it may prevent these groups from benefiting from future developments in asthma management and thus widen existing disparities in asthma care. Future genetic association studies of asthma among ethnic minorities in the United States should include large samples of populations that have been adequately defined with regard to area of residence, self-designated ancestry, and country of origin. These studies should also include an adequate assessment of potentially relevant environmental exposures and (for case-control association studies) population stratification.

Polymorphisms in the IL-4, IL-4 receptor alpha chain, TNF-alpha, and lymphotoxin-alpha genes and risk of asthma in Hong Kong Chinese adults

BACKGROUND

Susceptibility to the development of asthma and other atopic diseases is known to be associated with genetic components. However, association studies with interleukin-4 (IL-4), IL-4 receptor alpha subunit (IL-4R alpha), tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha (LT-alpha) genes were inconclusive, as both positive and negative results were obtained in several populations studied. We aimed to investigate the association of the polymorphisms for IL-4 (C-589T), IL-4R alpha (Gln576Arg), TNF-alpha (G-308A) and LT-alpha (A252G) genes as candidates and asthma in adult Hong Kong Chinese population.

METHODS

The association study was conducted in an age- and smoking status-matched case-control design in asthma patients (n = 292) and healthy controls (n = 292) using polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

No significant differences were found in allele and genotype frequencies of all four genes between patients and controls. After stratification by atopic status, the heterozygous AG genotype of LT-alpha (A252G) was found to increase risk of asthma in atopic population [odds ratio (OR) = 2.00, 95% CI 1.09-3.67, p = 0.024]. When stratified by smoking status, we found increased risk of asthma with subjects carrying the heterozygous AG and homozygous GG genotypes of LT-alpha in ever-smokers (OR = 2.73, 95% CI 1.11-6.69, p = 0.028 for heterozygotes; OR = 3.34, 95% CI 1.16-9.62, p = 0.026 for homozygotes).

CONCLUSION

Our results suggest that the variability of LT-alpha genotypes may have potential implications for individual susceptibility to asthma in atopic or in ever-smoking Chinese adults in Hong Kong.

Artificial neural network predictive model for allergic disease using single nucleotide polymorphisms data

The purpose of this study was to develop a novel diagnostic prediction method for allergic diseases from the data of single nucleotide polymorphisms (SNPs) using an artificial neural network (ANN). We applied the prediction method to four allergic diseases, such as atopic dermatitis (AD), allergic conjunctivitis (AC), allergic rhinitis (AR) and bronchial asthma (BA), and verified its predictive ability. Almost all the learning data were precisely predicted. Regarding the evaluation data, the learned ANN model could correctly predict a diagnosis with more than 78% accuracy. We also analyzed the SNP data using multiple regression analysis (MRA). Using the MRA model, less than 10% of patients with the above allergic diseases were correctly diagnosed, while this figure was more than 75% for persons without allergic diseases. From these results, it was shown that the ANN model was superior to the MRA model with respect to predictive ability of allergic diseases. Moreover, we used two different methods to convert the genetic polymorphism data into numerical data. Using both methods, diagnostic predictions were quite precise and almost the same predictive abilities were observed. This is the first study showing the application and usefulness of an ANN for the prediction of allergic diseases based on SNP data.

Cytokines, allergy, and asthma

PURPOSE OF REVIEW

This review examines recent articles on the relationship of cytokines to allergy and asthma with particular emphasis on immune mechanisms involved in disease development in early life.

RECENT FINDINGS

It was previously proposed that reduced microbial exposure in early life is responsible for a shift of the Th1/Th2 balance in the immune system towards the proallergenic Th2 response. This Th1/Th2 imbalance results in the clinical expression of allergy and/or asthma. In recent years, accumulating data from mice and humans have identified Th2 cytokines [interleukin (IL)-4, IL-13, and IL-5] as major contributors to allergy and asthma. Interestingly, the Th1 cytokine interferon-gamma has recently been shown to act concurrently with Th2 cytokines in maintaining the chronic inflammatory response in allergic diseases, particularly in asthmatic airways. Most recently, evidence suggests that suppression of T-regulatory cells may contribute to the underlying immune mechanisms involved in allergy and asthma.

SUMMARY

An enhanced Th2 immune response and the elaboration of cytokines such as IL-4, IL-13, and IL-5 contribute to the induction of allergy and asthma. Interferon-gamma, a Th1 cytokine, acts in conjunction with Th2 (IL-4, IL-13, and IL-5) in maintaining chronic allergic inflammation. The mechanisms leading to an enhanced Th2 response are still controversial. Th2-dominated immune responses may result from immune suppression of T-regulatory cells as well as Th1 cells. Understanding early-life immune mechanisms responsible for atopic diseases, specifically how cytokines of T-regulatory cells act to balance the Th1 and Th2 immune response, continues to be a fruitful area of research.

A_16_C haplotype in the FcepsilonRIbeta gene confers a higher risk for atopic asthma in the Indian population

We conducted a case-control study aimed at identifying polymorphisms and haplotypes in the FcepsilonRIbeta gene associated with asthma and its associated phenotypes such as serum IgE levels. A G/A polymorphism in intron 2, a (CA)n repeat polymorphism in intron 5, and a C/T polymorphism in 3'-UTR, encompassing a length of 8.74 Kb, were genotyped, and haplotypes were generated for unrelated patients and healthy volunteers in two independent cohorts. A significant association was observed at the level of alleles and genotypes studied with asthma independently in the two cohorts (p < 0.05). A change in CC_AA genotype combination to a non-CC_AA genotype was associated with reduced risk for asthma. Interestingly, a three-locus haplotype, A_16_C, was found to be significantly associated with asthma (p = 10(-5) in cohort A and p = 0.004 in cohort B). On the other hand, the haplotype G_18_T was found to be negatively associated with asthma (p = 0.007 in cohort A and p = 0.0004 in cohort B). This is the first study identifying a haplotype A_16_C that predisposes individuals to asthma in the Indian population.

Effects of common atopy-associated amino acid substitutions in the IL-4 receptor alpha chain on IL-4 induced phenotypes

The human IL-4 receptor alpha chain gene (IL4R) is highly polymorphic and controversial reports have been published with respect to the association of different single nucleotide polymorphisms (SNPs) with atopy markers. Here we analyzed the functional and associational relevance of common IL4R coding SNPs. Transfection of B cell lines expressing the IL-4R variant V75+R576 did not result in enhanced IL-4 induced CD23 expression compared to cell lines expressing the wild type IL-4R alpha chain. Transfection of the IL-4R variant P503 into a murine T cell line did not influence IL-4 induced T-cell proliferation compared to wild type constructs. Analysis of six IL4R coding SNPs (I75V, E400A, C431R, S436L, S503P, Q576R) and common haplotypes (frequency >/=0.05%) in blood donors (n=300) did not indicate a significant association with elevated serum IgE level. Moreover, the most informative IL4R coding SNPs (I75V, C431R, Q576R) and related two- and three-point haplotypes (frequency >/=0.05%) were analyzed in a second, extended group of blood donors (n=689). Again, no significant association with elevated serum IgE was detectable. We conclude that common coding SNPs in the IL4R gene are unlikely to contribute significantly to increased IgE levels and variations outside the coding region may influence atopy susceptibility.

A comprehensive analysis of interleukin-4 receptor polymorphisms and their association with atopy and IgE regulation in childhood

BACKGROUND

The interleukin (IL) 4/IL13 pathway is involved in the regulation of IgE production associated with atopic diseases. Numerous polymorphisms have been identified in the coding region of the IL4 receptor alpha chain (IL4Ra) and previous association studies have shown conflicting results. Based on their putative functional role, polymorphisms A148G, T1432C and A1652G, located in the coding region of IL4Ra, were selected for association and haplotype studies in a large German population sample (n = 1,120).

METHODS

Genotyping was performed using allele-specific PCR and restriction-enzyme-based assays. Haplotypes were estimated, and population-derived IgE percentiles (50% IgE >60 IU/ml, 66% IgE >115 IU/ml and 90% IgE >457 IU/ml) were calculated as outcome variables in a haplotype trend regression analysis.

RESULTS

In our population, only polymorphism T1432C showed a trend for a protective effect against atopic rhinitis (odds ratio, OR: 0.52, 95% confidence interval, CI: 0.26-1.02, p = 0.05). When haplotypes were calculated, one haplotype was significantly associated with elevated serum IgE levels at the 50th percentile (OR 1.60, 95% CI 1.08-2.37, p = 0.02).

CONCLUSIONS

These data indicate that IL4Ra polymorphisms, although suggested to be functionally relevant by in vitro studies, have only a minor influence on IgE regulation in our large population sample.

Polymorphisms in the FcεRIβ Promoter Region Affecting Transcription Activity: A Possible Promoter-Dependent Mechanism for Association between FcεRIβ and Atopy

The beta subunit of the high-affinity IgE receptor (FcepsilonRI) plays an important role in IgE-mediated allergic reactions as an amplifier for cell surface expression and signal transduction of FcepsilonRI. FcepsilonRIbeta is presumed to be one of the genes linked with atopic diseases. However, the validity of the associations previously found between single nucleotide polymorphisms (SNPs) in FcepsilonRIbeta and atopic diseases is questionable. In the present study, we found correlation between the SNP of FcepsilonRIbeta at +6960A/G, resulting in a Glu237Gly amino acid substitution, and the cell surface expression level of FcepsilonRI on blood basophils, although it has been shown that the Glu237Gly mutation itself does not affect the surface expression or function of FcepsilonRI. We additionally found four SNPs in the promoter region of FcepsilonRIbeta, among which -426T/C and -654C/T were tightly linked with +6960A/G. Reporter plasmids carrying the -426C and -654T promoter displayed higher transcriptional activity than those carrying the -426T and -654C promoter. We found that transcription factor YY1 preferentially bound and transactivated the -654T promoter. Furthermore, expression of FcepsilonRI beta-chain mRNA in basophils from individuals who have the minor heterozygous genotype was significantly higher than that of the major homozygous genotype. These results suggest that the SNPs in the FcepsilonRIbeta promoter are causally linked with atopy via regulation of FcepsilonRI expression.

Interleukin 3 (IL3) polymorphisms associated with decreased risk of asthma and atopy

Cytokines, having central functions in immunological and inflammatory process, are always expected to play important roles in the pathogenesis of various diseases, such as asthma. Genetic polymorphisms of those cytokine and cytokine receptor genes are the focus of genetic association studies. In an effort to identify gene(s) whose variant(s) are involved in the development of asthma, we examined the genetic effects of 19 single nucleotide polymorphisms in eight cytokine and cytokine receptor genes, including IL1A, IL1B, IL2, IL3, IL4, IL8, IL10, and IL5RA, on asthma and atopy. Nineteen single nucleotide polymorphisms in eight cytokine and cytokine receptor genes were genotyped using the single-base extension method in a Korean asthma cohort (n = 723). Logistic regression and multiple regressions were used for statistical analyses controlling for smoking, age, and gender as covariables. Genetic association analysis of polymorphisms revealed that one exonic (exon 1), IL3 + 79T > C ( Ser27Pro), showed significant association with the risk of asthma and atopy. The Pro allele had shown dominant and protective effects on development of asthma in nonatopic subjects (P = 0.002) and also showed significant association with the risk of atopy in normal control subjects (P = 0.007). This information about the genetic association of important genes with asthma might provide valuable insights into strategies for the pathogenesis of asthma and atopy.

Association of IL4 gene polymorphisms with asthma in North Indians

BACKGROUND

Asthma is a complex airway disorder, and a number of genetic loci have been found to be associated with asthma. The 5q31-33 region is one of the most important loci linked to asthma and atopic disorders. However, association studies with candidate genes in this region, such as IL4, were inconclusive, as both positive and negative results were obtained in several populations studied. The aim of our case-control study was to determine the association between IL4 and asthma in North Indians.

PATIENTS AND METHODS

Polymorphisms in the promoter and a dinucleotide repeat in the 2nd intron in IL4 were genotyped by sequencing and GeneScan analysis, respectively, in ethnically matched, unrelated patients (n = 171) and controls (n = 128), following the guidelines of the American Thoracic Society.

RESULTS

The proximal promoter region of the IL4 gene was found to be invariant. Previously reported polymorphisms, -590 C/T and +33 C/T, were found to be absent in our population. The chi2 test using only large expected cell counts (more than 5% of the sample size) showed a significant association between allele size and disease status (chi2 = 38.08, d.f. = 6, p < 0.05). In addition, a significant difference was observed for the allele and genotype frequencies (p < 0.0005 and p = 0.0009, respectively) in the patient and the control groups using the Fisher-Freeman-Halton test.

CONCLUSION

Our studies indicate that the promoter of the IL4 gene is invariant in our population. The case-control studies on the CA repeat polymorphism in the 2nd intron of the IL4 gene have shown interesting results and indicate the need for further family-based studies.

Genetic variation in immunoregulatory pathways and atopic phenotypes in infancy

BACKGROUND

Asthma is a chronic respiratory disease that often originates in early childhood. Although candidate gene studies have identified many potential asthma susceptibility genes in adult populations, few have studied associations with immune phenotypes in the first year that might be early clinical markers of asthma.

OBJECTIVE

The aim of this study was to assess the contribution of genetic variation to cytokine response profiles and atopic phenotypes in the first year of life in the Childhood Origin of Asthma cohort.

METHODS

Two hundred seven European American children participating in the Childhood Origin of Asthma study were genotyped for 61 single nucleotide polymorphisms in 35 genes involved in immune regulation. We examined the relationship between these single nucleotide polymorphisms and PHA-induced cytokine (IL-5, IL-10, IL-13, and IFN-gamma) response profiles at birth and at year 1, respiratory syncytial virus-induced wheezing and atopic dermatitis in the first year of life, and total IgE levels, peripheral blood eosinophil counts, and allergic sensitization at age 1 year. The data were analyzed by using censored regression for quantitative measurements and logistic regression for qualitative phenotypes.

RESULTS

The 237Gly allele of the high-affinity IgE receptor beta chain (FCER1B) and a silent substitution in the nitric oxide synthase (NOS)2A gene were associated with reduced IL-13 responses in cord blood (P = .0025 and P = .0062, respectively). A significant gene-gene interaction between FCER1B 237Gly and NOS2A D346D was detected, with individuals carrying the minor allele for both polymorphisms having the lowest cord blood IL-13 levels. Furthermore, the IL13 110Gln allele showed an association with increased IgE levels at year 1 (P = .0026), and the colony-stimulating factor 2 (CSF2) 117Thr allele showed an association with a greater increase in IL-5 responses during the first year (P = .0092). The TGF-beta1 (TGFB1) -509T allele was associated with respiratory syncytial virus-related wheezing in the first year (P = .0005). None of the polymorphisms included in this study were associated with atopic dermatitis during the first year or a positive RAST result at 1 year of age.

CONCLUSION

These data suggest that variations in genes involved in immune regulation are associated with biologic and clinical phenotypes in the first year of life that might increase the risk for the subsequent development of childhood asthma.

IL-10 Inhibits FcεRI Expression in Mouse Mast Cells

FcepsilonRI expression and function is a central aspect of allergic disease. Using bone marrow-derived mouse mast cell populations, we have previously shown that the Th2 cytokine IL-4 inhibits FcepsilonRI expression and function. In the current study we show that the Th2 cytokine IL-10 has similar regulatory properties, and that it augments the inhibitory effects of IL-4. FcepsilonRI down-regulation was functionally significant, as it diminished inflammatory cytokine production and IgE-mediated FcepsilonRI up-regulation. IL-10 and IL-4 reduced FcepsilonRI beta protein expression without altering the alpha or gamma subunits. The ability of IL-4 and IL-10 to alter FcepsilonRI expression by targeting the beta-chain, a critical receptor subunit known to modulate receptor expression and signaling, suggests the presence of a Th2 cytokine-mediated homeostatic network that could serve to both initiate and limit mast cell effector function.

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

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

Genetic analyses in asthma: current concepts and future directions

Asthma is a complex genetic disorder with a heterogeneous phenotype, largely attributed to the interactions among many genes and between these genes and the environment. Numerous loci and candidate genes have been reported to show linkage and association of asthma and the asthma-associated phenotypes, atopy, elevated immunoglobulin E (IgE) levels, and bronchial hyper-responsiveness to alleles of microsatellite markers and single nucleotide polymorphisms (SNPs) within specific cytokine/chemokine, and IgE regulating genes. While many studies reporting these observations are compelling, only one asthma gene conferring high risk has been mapped. In this review, we present studies that support linkage and/or associations to the various genetic loci and genes in asthma. The first genome-wide scan for linkage to quantitative traits underlying asthma identified linkage on chromosome 4q, 6, 7, 11q, 13q and 16. A genome scan in American families from three racial groups revealed linkage to chromosome 2q, 5q, 6p, 12q, 13q and 14q. A two-stage scan in Hutterite families from the US found linkage on chromosome 5q, 12q, 19q and 21q. A screen in German families identified linkage to asthma on chromosome 2q, 6p, 9 and 12q and a two-stage genome scan in French families found replicated linkage on chromosomes 1p, 12q and 17q. A study of asthma in Finland showed linkage to high IgE on 7q14. Apart from a European linkage study of 199 families with atopic dermatitis, which demonstrated significant linkage to chromosome 3q21, three other studies have reported linkage results of genome-wide significance, including a linkage study in 175 Icelandic asthma families (14q24), a study in 533 Chinese families with bronchial hyper-responsiveness (chromosome 2) and a study in 47 Japanese families with mite-sensitive atopic asthma (5q31), suggesting that these regions may harbor genes contributing to the development of asthma and allergies. While significant progress has been made in the field of asthma genetics in the past decade, the clinical implications of the genes and genetic variations within the numerous candidate asthma genes that have been found to associate with the expression of the asthmatic phenotype, remain undetermined.

Present status on the genetic studies of asthma

Asthma, one of the most common chronic diseases, is a complex and heterogeneous disorder. The results of genome screens for asthma-related traits in 11 different populations identified at least 18 regions of the genome that probably house asthma/atopy genes. The most consistently replicated regions are on chromosomes 2q, 5q, 6p, 12q and 13q. Positional cloning projects are ongoing in laboratories around the world to identify the asthma susceptibility loci in these regions. In addition, many candidate genes have been associated with asthma phenotypes, such as the genes in the IL-4/IL-13 pathway.

Polymorphisms of transforming growth factor-beta1 and transforming growth factor-beta1 type II receptor genes are associated with acute graft-versus-host disease in children with HLA-matched sibling bone marrow transplantation

The aim of this study was to determine whether the gene polymorphisms of Th1/Th2 and immunoregulatory cytokines were associated with aGVHD in Japanese children receiving allogeneic bone marrow transplantation (allo BMT). We investigated polymorphisms of genes encoding interleukin (IL)-4, IL-4 receptor (IL-4 R), IL-10, transforming growth factor (TGF)-beta1, TGF-beta1 type II receptor (TGF-beta1 RII), interferon (IFN)-gamma, IFN-gamma type 2 receptor (IFN-gamma R2), and IFN regulatory factor (IRF)-1. Sixty-seven patients were treated with allo BMT from HLA-identical siblings, and aGVHD was observed in 38. TGF-beta1 codon 10 leucine (Leu) /proline (Pro) polymorphism in donors was associated with the development of aGVHD. Patients having donors with the Pro allele had aGVHD more frequently than those without Pro allele (30/45 vs 8/20, odds ratio = 3.00; P = 0.04). TGF-beta1 RII 1167 C/T polymorphism in recipients was also associated with the development of aGVHD. The incidence was significantly higher in recipients with T allele than in those without T allele (21/27 vs 16/35, odds ratio = 4.16; P = 0.01). In conclusion, genetic backgrounds of TGF-beta1 and TGF-beta1 RII may be involved in the development of aGVHD in HLA-matched sibling BMT in Japanese children.

Analysis of association and linkage for the interleukin-4 and interleukin-4 receptor b;alpha; regions in Swedish atopic dermatitis families

BACKGROUND

Atopic dermatitis (AD) is caused by genetic and environmental factors that interact to determine disease susceptibility and severity. Several lines of evidence suggest that the IL-4 gene and the IL-4-receptor alpha (IL-4Ralpha) gene are involved in the development of atopic diseases.

OBJECTIVE

The objective of this study was to evaluate the possible involvement of the chromosomal regions 5q31 and 16p12, which include the genes coding for the IL-4 and the IL-4Ralpha in AD.

METHODS

We conducted linkage analysis and association studies using the microsatellite markers D16S298 and D16S403 and a single nucleotide polymorphism in the promoter region of the IL-4 gene (- 590C/T) in 406 Swedish families with at least two siblings affected with AD, in total 1514 individuals.

RESULTS AND CONCLUSION

We report linkage (P < 0.005) to the - 590C/T polymorphism in the promoter of the IL-4 gene for the semiquantitative trait severity score of AD. Neither linkage nor association was found to the IL-4Ralpha chromosomal region.

Candidate genes for atopic asthma: current results from genome screens

Atopic asthma is one of the most common childhood diseases in developed countries. Asthma is characterized by reversible airway obstruction, bronchial hyper-responsiveness, and airway inflammation. Atopy in childhood is considered the strongest predisposing factor for asthma. The etiology of asthma is complex and is thought to involve the interaction of multiple genes and a variety of environmental factors such as allergens and viral and bacterial infections. To identify genes conferring susceptibility for asthma and atopy, many genome-wide screens for asthma and its associated traits have now been carried out, and genetic linkage has been consistently identified in several regions. Several independent genome-wide screens found regions of linkage with asthma on chromosomes 5, 6, 11, 12, 13, 16 and 19, identifying candidate susceptibility genes including FCER1B, the IL-4 gene cluster, TNFalpha, HLA loci and others. However, the evidence for linkage is still only suggestive for most regions. In an effort to clarify the mechanism underlying the development of asthma, further studies utilizing new technologies and data from the Human Genome Project are ongoing. It is hoped that this accumulation of data will lead to improved genetic testing and assist in the development of new drugs.

Asthma and IL-4 receptor alpha gene variants

Linkage of allergy to chromosome 16 has been described in several studies, together with a positive association with interleukin 4 receptor alpha gene variants. Our aim was to replicate these findings in a sample of German and Swedish families recruited through sib-pairs affected by bronchial asthma. None of the markers showed linkage with the main phenotype of asthma or with total serum IgE. Seropositivity to D. pteronyssinus showed borderline significance in a region flanking the IL4Ralpha location. Single nucleotide polymorphisms (SNPs) leading to the protein exchanges I50V, E375A, C406R, S478P and Q551R in the IL-4 receptor alpha were examined for allele sharing in sibs with asthma. Multiple regression analysis was performed for association with total serum IgE and specific IgE. Allele sharing of IL4Ralpha SNPs in asthmatic children was not significantly increased for any of the examined SNPs except for the intracytoplasmatic polymorphism 551R (0.79 vs. 0.84 expected, P = 0.044). The variants 50V, 478P and 551R were associated with slightly increased, and 375A and 406R with decreased total IgE levels, all at a non-significant level. None of the examined IL4Ralpha variants were correlated to asthma severity. In summary, a single gene effect of IL4Ralpha variants or any other gene on chromosome 16 could not be shown in this selected population of children with asthma. As there could be interactions with multiple genetic and environmental factors, IL4Ralpha could still be involved in asthma pathogenesis.

Polymorphisms for interleukin-4 (IL-4) -590 promoter, IL-4 intron3, and tumor necrosis factor alpha -308 promoter: non-association with endometriosis

Interleukin-4 (IL-4) is a cytokine with anti-inflammatory properties. Tumor necrosis factor alpha (TNF-alpha), a pluripotent proinflammatory cytokine, plays an important role in the process of numerous inflammatory and autoimmune diseases. We aimed to investigate whether gene polymorphisms for the IL-4 -590 promoter, IL-4 intron3 and TNFalpha -308 promoter could be used as markers of susceptibility in endometriosis. The subjects, 226 premenopausal Taiwan Chinese women with surgically diagnosed endometriosis and nonendometriosis, were divided into two groups: 1) endometriosis (n = 120) and 2) nonendometriosis (n = 106). Polymorphisms for the IL-4 -590 promoter, IL-4 intron3, and TNFalpha -308 G-to-A promoter were detected by polymerase chain reaction (PCR). Genotypes and allelic frequencies for these gene polymorphisms in both groups were compared. We observed no significant differences in genotype distribution and allele frequency of the IL-4 -590 promoter, IL-4 intron3, and TNFalpha gene polymorphism between both groups. The proportions of the -590*C homozygote/heterozygote/-590* T homozygote for the IL-4 promoter in both groups were 1.6/31.6/66.6% in group 1, and 5.8/33.0/61.2% in group 2. The proportions of the RP1 homozygote/heterozygote/RP2 homozygote for IL-4 intron3 in both groups were 62.5/34.1/2.5% (group 1), and 64.1/32.0/3.9% (group 2). The proportions of -308*A homozygote/heterozygote/-308*G homozygote for the TNFalpha promoter in both groups were 7.5/20.8/71.7% (group 1), and 7.5/17/75.5% (group 2). We concluded that there is no association between endometriosis and the IL-4 and TNFalpha gene polymorphisms. The IL-4 -590 promoter, IL-4 intron3, and TNFalpha -308 G-to-A polymorphisms are not useful markers for predicting susceptibility to endometriosis.

Association of IFN-gamma and IFN regulatory factor 1 polymorphisms with childhood atopic asthma

BACKGROUND

IFN-gamma and related molecules play important roles in the differentiation and function of TH2 cells.

OBJECTIVE

We sought to determine whether IFNG and related genes contribute to any susceptibility to atopic asthma, a representative TH2-dominant disorder.

METHODS

We investigated the association of IFNG (CA repeat polymorphism within the first intron), IRF1 (GT repeat polymorphism within the intron 7), IFNGR1 (Val 14 Met), and IFNGR2 (Gln 64 Arg) gene polymorphisms with atopic asthma in the Japanese child population.

RESULTS

A significant association (P =.0018) was observed between IFNG gene polymorphism and atopic asthma. The tendency was more prominent in patients with age of onset of 3 years or younger (P =.0004) or patients with a family history of allergic diseases (P =.0038). Furthermore, there was a significant association between IRF1 gene whole-allele distribution and atopic asthma (P =.044). The tendency was more prominent in patients with onset at 3 years of age or less (P =.0058). On the other hand, IFNGR1 and IFNGR2 gene polymorphisms showed no association with atopic asthma.

CONCLUSION

These results suggested that among IFNG and related genes, IFNG and IRF1 genes confer genetic susceptibility to atopic asthma in Japanese children.

Using single nucleotide polymorphisms as a means to understanding the pathophysiology of asthma

Asthma is the most common chronic childhood disease in the developed nations, and is a complex disease that has high social and economic costs. Studies of the genetic etiology of asthma offer a way of improving our understanding of its pathogenesis, with the goal of improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect specific polymorphisms in genetic loci contributing to asthma susceptibility. Concomitantly, the technology for detecting single nucleotide polymorphisms (SNPs) has undergone rapid development, extensive catalogues of SNPs across the genome have been constructed, and SNPs have been increasingly used as a method of investigating the genetic etiology of complex human diseases. This paper reviews both current and potential future contributions of SNPs to our understanding of asthma pathophysiology.

Mechanisms of food allergy

The prevalence of food allergy continues to rise, particularly in 'westernized' societies; it has been linked to the 'hygiene hypothesis' and the increased diversity of food consumption worldwide. The pathogenic mechanisms and Th1/Th2 paradigm are being closely examined with respect to the occurrence of inflammatory and injury/repair responses at different mucosal sites. Genetically modified plants as potential food sources and allergenicity are current topics of controversy.

Genomic approaches to understanding asthma

Asthma is the most common chronic childhood disease in developed nations, and it is a complex disease that has high social and economic costs. Asthma and its associated intermediate phenotypes are under a substantial degree of genetic control. The genetic aetiology of asthma offers a means of better understanding its pathogenesis and, thus, improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect genetic loci contributing to asthma susceptibility, and extensive candidate gene studies and a number of whole-genome screens have been undertaken. This article reviews the current state of knowledge of the genetics of asthma, with a focus on genomic approaches to understanding allergic diseases.