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

Interleukin-4 receptor alpha T1432C and A1652G polymorphisms are associated with risk of visceral leishmaniasis

Background:

Immune responses play significant roles in protection against leishmaniasis. Polymorphisms within the interleukin 4 receptor alpha chain (IL-4Rα) gene affect the production of cytokines, which is important for the clearance of many pathogens. The aim of the current study was to identify the relationship between visceral leishmaniasis (VL) infection and polymorphisms at positions T1432C and A1652G of IL-4Rα in an Iranian population.

Materials and Methods:

This cross-sectional study was performed during 2004–2012 and included three groups of participants: VL patients (Group 1, n = 124), seropositive healthy controls (Group 2, n = 101), and seronegative healthy controls (Group 3, n = 55). The IL-4Rα T1432C and A1652G polymorphisms were evaluated using a polymerase chain reaction-restriction fragment length polymorphism technique, and anti-Leishmania antibody titers were determined by using immunofluorescence technique. Alleles and genotypes were compared between groups of the study as well as Groups 1 and 2 based on the titer of antibodies. The validity of the data was analyzed using Hardy–Weinberg equilibrium and one-way analysis of variance, as well as χ² tests.

Results:

The polymorphisms at IL-4Rα positions T1432C and A1652G were significantly associated with active VL infection. These results demonstrated that the IL-4Rα T1432C and A1652G polymorphisms were not associated with anti-Leishmania antibody production.

Conclusion:

Our results indicate that these IL-4Rα polymorphisms may be risk factors for the development of VL.

Current concepts of IgE regulation and impact of genetic determinants

Immunoglobulin E (IgE) mediated immune responses seem to be directed against parasites and neoplasms, but are best known for their involvement in allergies. The IgE network is tightly controlled at different levels as outlined in this review. Genetic determinants were suspected to influence IgE regulation and IgE levels considerably for many years. Linkage and candidate gene studies suggested a number of loci and genes to correlate with total serum IgE levels, and recently genome-wide association studies (GWAS) provided the power to identify genetic determinants for total serum IgE levels: 1q23 (FCER1A), 5q31 (RAD50, IL13, IL4), 12q13 (STAT6), 6p21.3 (HLA-DRB1) and 16p12 (IL4R, IL21R). In this review, we analyse the potential role of these GWAS hits in the IgE network and suggest mechanisms of how genes and genetic variants in these loci may influence IgE regulation.

Mannose-binding lectin genotype and serum levels in patients with chronic and allergic pulmonary aspergillosis

Several studies suggest mannose-binding lectin (MBL) deficiency is associated with various manifestations of aspergillosis. MBL serum levels and function are genetically determined, but levels rise during inflammation. We address the relative frequency of deficient genotypes, the relationship between serum level and genotype and both age and disease manifestations in patients with chronic pulmonary (CPA) and allergic bronchopulmonary aspergillosis (ABPA) and severe asthma with fungal sensitization (SAFS). DNA was extracted from blood samples, and MBL2 genotyping was performed using the INNO-LiPA MBL2 kit. Serum MBL concentrations were determined using ELISA. One hundred and eight patients were evaluated, 70 (65%) with CPA, 38 (35%) with allergic disease (ABPA, SAFS or undefined) and 13 (12%) had both CPA and ABPA. The mean MBL serum level was 1849 μg L(-1) and did not differ between groups. Forty subjects (37%) had exon 1 genotypes producing nonfunctional MBL (A/B, A/C, A/D and O/O), a frequency not different from published normal controls. A/A subjects with CPA had higher levels (2981 μg L(-1)) compared with allergic A/A subjects (2202 μg L(-1)) (pc0.012). No single haplotype, genotype or allele was significantly related to any aspergillosis phenotype. Worse breathlessness was associated with higher MBL levels among A/A subjects (P = 0.009) and conversely nonfunctional genotypes. Mean MBL values were higher in those with an Medical Research Council (MRC) breathlessness score of 5 compared with those with and MRC score of 1 (P = 0.023). A/A allergic subjects (n = 27) in this study were ≈ 11 years younger than allergic A/O subjects (n = 11, P = 0.02). Subjects with worse respiratory status or more severe CPA had higher MBL serum levels (P = 0.023; P = 0.034). Bronchiectasis was not associated with MBL levels in CPA or allergic aspergillosis. MBL genotype and serum level modulate progression of aspergillosis.

A meta-analysis of Th2 pathway genetic variants and risk for allergic rhinitis

There is a significant genetic contribution to allergic rhinitis (AR). Genetic association studies for AR have been performed, but varying results make it challenging to decipher the overall potential effect of specific variants. The Th2 pathway plays an important role in the immunological development of AR. We performed meta-analyses of genetic association studies of variants in Th2 pathway genes and AR. PubMed and Phenopedia were searched by double extraction for original studies on Th2 pathway-related genetic polymorphisms and their associations with AR. A meta-analysis was conducted on each genetic polymorphism with data meeting our predetermined selection criteria. Analyses were performed using both fixed and random effects models, with stratification by age group, ethnicity, and AR definition where appropriate. Heterogeneity and publication bias were assessed. Six independent studies analyzing three candidate polymorphisms and involving a total of 1596 cases and 2892 controls met our inclusion criteria. Overall, the A allele of IL13 single nucleotide polymorphism (SNP) rs20541 was associated with increased odds of AR (estimated OR=1.2; 95% CI 1.1-1.3, p-value 0.004 in fixed effects model, 95% CI 1.0-1.5, p-value 0.056 in random effects model). The A allele of rs20541 was associated with increased odds of AR in mixed age groups using both fixed effects and random effects modeling. IL13 SNP rs1800925 and IL4R SNP 1801275 did not demonstrate overall associations with AR. We conclude that there is evidence for an overall association between IL13 SNP rs20541 and increased risk of AR, especially in mixed-age populations.

Pathogenesis of allergic bronchopulmonary aspergillosis in cystic fibrosis: current understanding and future directions

Allergic bronchopulmonary aspergillosis (ABPA) is an allergic disease characterized clinically by wheezing, pulmonary infiltrates, bronchiectasis, and fibrosis that affects patients with asthma and cystic fibrosis (CF). Although this disease has been characterized by a Th2 immune response to Aspergillus, the disease has some features such as central bronchiectasis which is not seen in other Th2 driven lung diseases such as atopic asthma. Here we will review the current pathophysiology of ABPA in CF and highlight new molecules that may affect immune responses against Aspergillus and ABPA disease pathogenesis.

Allergies, variants in IL-4 and IL-4R alpha genes, and risk of pancreatic cancer

BACKGROUND

Several studies in epidemiology indicate that risk of pancreatic cancer is reduced in individuals with allergies. Although genes have been identified that are critical in allergic response, polymorphisms in these genes have not been studied in relation to risk of pancreatic cancer. We hypothesized that variants in these genes are related to risk.

METHODS

We investigated the association of allergies and pancreatic cancer in a hospital-based case-control study with 405 cases and 212 controls. In a subgroup of 149 cases and 135 controls, we studied the association of variants in IL-4 (C-589T, G3017T) and IL-4R alpha (Gln576Arg) with allergies and with risk of pancreatic cancer.

RESULTS

We found reduced risk of pancreatic cancer associated with allergies, with adjusted odds ratios of 0.58 (95% CI 0.40-0.84) for any allergies, 0.45 (95% CI 0.29-0.70) for hay fever, and 0.43 (95% CI 0.23-0.80) for animals. The minor allele at each locus studied was associated with reduced risk of allergies in controls, leading us to hypothesize that they would be associated with increased risk of pancreatic cancer. Overall, there was no association between the genotypes studied and risk of pancreatic cancer. In analyses within strata defined by presence or absence of allergies, there were differences in risk associated with genotype for IL-4 G3017T: there was slightly increased risk among those with allergies and reduced risk among those without allergies.

CONCLUSIONS

The consistent association of allergies with risk of pancreatic cancer and these results suggest that associations between variants in genes related to allergic response and pancreatic cancer warrant further study.

Interaction between variants in the interleukin-4 receptor alpha and interleukin-9 receptor genes in childhood wheezing: evidence from a birth cohort study

BACKGROUND

Several polymorphisms in the IL-4 receptor alpha (IL4RA) gene have been associated with asthma and atopy, but with variable success in different populations. Immunologic studies suggest that IL4RA may interact with other cytokines and receptors, and gene-gene interactions have also been observed with respect to asthma. Such interactions have been proposed to explain partly the difficulties in replicating association studies.

METHODS

Using the prospective birth cohort BAMSE, we examined eight single nucleotide polymorphisms (SNPs) and corresponding haplotypes in the IL4RA gene in relation to wheezing and sensitization up to age 4. We also evaluated potential interaction effects (departure from a multiplicative interaction model) between the IL4RA SNPs and four SNPs in the IL-9 receptor (IL9R) gene previously associated with childhood wheezing.

RESULTS

We found no main effect of the IL4RA SNPs alone and only weak associations to wheezing and sensitization when haplotypes were considered. Gene-gene interactions between several IL4RA and IL9R SNPs with regard to wheezing were observed (P=0.009), especially between IL4RA Q576R (rs1801275) and IL9R rs731476 (P=0.005). An interaction was also seen between IL4RA and IL9R haplotypes.

CONCLUSION

Variants in the IL4RA gene alone may not exert any major influence on susceptibility to asthma-related diseases in childhood, but in combination with other genes, such as IL9R, IL4RA may be an important gene for disease susceptibility.

Ethnicity-specific gene-gene interaction between IL-13 and IL-4Ralpha among African Americans with asthma

RATIONALE

Genes in the interleukin (IL)-4/IL-13/IL-4Ralpha pathway have been shown to be associated with asthma and related phenotypes in some populations, but not in others. Furthermore, interaction between these genes has been shown to affect asthma in white and Chinese populations.

OBJECTIVES

To determine whether there are IL-4/IL-13 and IL-4Ralpha gene-gene interactions that are associated with asthma in African Americans.

METHODS

Eighteen single-nucleotide polymorphisms (SNPs) in IL-4, IL-13, and IL-4Ralpha genes were genotyped in 264 African Americans with asthma and 176 healthy control subjects. We tested the SNPs for genetic associations and gene-gene interactions with asthma, baseline lung function, bronchodilator drug response, and total serum IgE levels.

MEASUREMENTS AND MAIN RESULTS

We identified 94 SNPs in IL-4, IL-13, and IL-4Ralpha genes by directly sequencing these genes in 24 African-American subjects with asthma. Seventeen SNPs were analyzed for association with asthma and related phenotypes. We found no evidence of association in the IL-4 gene. One SNP in the IL-13 gene (A-646G, rs2069743) and two SNPs in the IL-4Ralpha gene (A+4679G, rs1805010, and C+22656T, rs1805015) showed association with lung function (both baseline and post-bronchodilator). Although the association between individual SNPs and asthma-related phenotypes differed from previous studies performed in white and Chinese populations, significant gene-gene interaction was found between the IL-13 (A-646G) and IL-4Ralpha (A+4679G) SNPs for baseline lung function among African-American subjects with asthma.

CONCLUSIONS

Gene-gene interaction between the IL-13 and IL-4Ralpha genes may play an important role in asthma among African Americans.

Influence of SNPs in cytokine-related genes on the severity of food allergy and atopic eczema in children

Although many single nucleotide polymorphism (SNP) studies have reported an association of atopy, allergic diseases and total serum immunoglobulin E (IgE) levels, almost all of these studies sought risk factors for the onset of these allergic diseases. Furthermore, many studies have analyzed a single gene and hardly any have analyzed environmental factors. In these analyses, the results could be masked and the effects of other genes and environmental factors may be decreased. Here, we described the correlation between four genes [interleukin (IL)-4 (C-590T), IL-4 receptor (A1652G), FCER1B (G6842A) and STAT6 (G2964A)] in connection with IgE production; the role of IL-10 (C-627A) as a regulatory cytokine of allergy; and the severity of food allergy (FA) and atopic eczema (AE) in 220 Japanese allergic children. In addition to these SNPs, environmental factors, i.e., patient's attitude, indoor environment, and so on, were also investigated in this study. Our study was retrospective, and the correlation was analyzed by our defined clinical scores divided into three terms: worst symptoms, recent symptoms and general amelioration at the most recent examination during the disease course. Our results indicated that IL-10 AA, the genotype with lower IL-10 production, is associated with higher IgE levels in the serum (p < 0.0001, estimate; 0.912). Marginal liver abnormalities were observed in the subject group with both FA and AE (p < 0.1191, estimate; 0.1490). Our defined clinical scores enabled evaluation of various aspects of disease severity. Based on the scores, while no single SNP selected in this study determined severity, the combination of the SNP with laboratory data and environmental factors appeared to determine severity.

Gene–gene interactions of IL13 and IL4RA variants in immediate allergic reactions to betalactam antibiotics

OBJECTIVES

Immediate reactions - particularly anaphylactic ones - to betalactams are the most common adverse reactions to antibiotics mediated by a specific immunologic mechanism. The genetic risk factors influencing these mechanisms are poorly known. We aimed to evaluate the association between immediate allergic reactions to betalactams and the polymorphisms of IL13 (R130Q and -1055C>T variants) and IL4RA (I50V, S478P, and Q551R variants).

METHODS

We determined these gene variants in 210 patients and 265 age-paired and gender-paired control subjects from Italy.

RESULTS

The combination of the less frequent allele of the IL13 R130Q polymorphism with any of the predominant homozygous genotypes of the three polymorphisms of IL4RA was more significantly associated with the risk of betalactam allergy (P=0.0006, 0.0077, and 0.0041, respectively) than any polymorphism considered alone (P=0.1745, 0.0268, 0.1812, 0.0152, respectively). The same associations were observed with serum IgE levels (IL13/IL4RA variant combinations: P=0.0009, 0.0007, 0.0020, respectively and each variant: P=0.0201, 0.0021, 0.0531, and 0.0417, respectively). The combination of IL4RA variants with -1055 C>T polymorphism produced similar associations.

CONCLUSION

Our data suggest that these combinations of IL13 and IL4RA variants are predictors of immediate allergic reactions to betalactams through a mechanism related to IgE production.

Cytokine gene polymorphisms and atopic disease in two European cohorts. (ECRHS-Basel and SAPALDIA)

BACKGROUND

Atopy and allergic phenotypes are biologically characterized by an imbalanced T helper cell response skewed towards a type 2 (TH2) immune response associated with elevated serum immunoglobulin E (IgE) levels. Polymorphisms in cytokine genes might modulate regulation of the TH1/TH2 balance. We thus aimed at reproducing our previous findings from a European study population on the association of various cytokine polymorphisms with self-reported hay fever as well as increased total and specific IgE levels in two comparable study populations.

METHODS

Two prospective Caucasian cohorts were used. In the Basel center of the European Community Respiratory Health Survey (ECRHS, n = 418) ten distinct cytokine polymorphisms of putative functional relevance were genotyped. In the Swiss cohort Study on Air Pollution And Lung Disease In Adults (SAPALDIA, n = 6003) two cytokine polymorphisms were genotyped. The associations of these polymorphisms with atopy were estimated by covariance and logistic regression analysis.

RESULTS

We confirmed IL4, IL10, IL6 and IL18 as candidate genes for atopic health outcomes. In the large, well-characterized SAPALDIA cohort the IL6(-174G>C) and IL18(-137G>C) polymorphisms were associated with circulating total IgE concentrations in subjects with hay fever. The IL18(-137G>C) polymorphism was also associated with the prevalence of hay fever.

CONCLUSION

Comprehensive characterization of genetic variation in extended cytokine candidate gene regions is now needed. Large study networks must follow to investigate the association of risk patterns defined by genetic predisposing and environmental risk factors with specific atopic phenotypes.

IL-4/IL-13 pathway genetics strongly influence serum IgE levels and childhood asthma

BACKGROUND

IgE production, a hallmark of asthma and atopic disease, may be under genetic control. Genes of the IL-4 and IL-13 pathway, central for IgE regulation, have so far only been assessed in studies of single gene effects.

OBJECTIVE

Here we analyzed combined extended haplotypes involving IL-4, IL-13, their shared receptor chain IL-4Ralpha, and the intracellular signal transducer and activator of transcription, STAT6, to assess the combined effect of single nucleotide polymorphisms in this important immunological signaling pathway.

METHODS

We genotyped a large cross-sectional population of 1120 children age 9 to 11 years for 18 polymorphisms in the respective genes of the IL-4/IL-13 pathway. One polymorphism per gene was selected because of its putative functional role, and extended haplotypes were built in a stepwise procedure where gene-by-gene interactions were assessed by using a Cordell model.

RESULTS

Combining polymorphisms in all 4 major pathway genes in a stepwise procedure, the risk for high serum IgE levels increased 10.8-fold (P = .02) and the risk for the development of asthma increased by a factor of 16.8-fold (P = .005) compared with the maximum effect of any single polymorphism. Significant interactions in a model with additive and dominant effects, for both pair and triplet combinations for asthma (lowest P = .005), and for pairs of polymorphisms in IgE regulation were observed (lowest P = .054).

CONCLUSION

These data indicate that only the combined analyses of genetic alterations in the IL-4/IL-13 pathway reveal its actual significance to the development of atopy and childhood asthma.