Patterns of GATA3 and IL13 gene polymorphisms associated with childhood rhinitis and atopy in a birth cohort

Frequency distribution of cytokine and associated transcription factor single nucleotide polymorphisms in Zimbabweans: Impact on schistosome infection and cytokine levels

Cytokines mediate T-helper (TH) responses that are crucial for determining the course of infection and disease. The expression of cytokines is regulated by transcription factors (TFs). Here we present the frequencies of single nucleotide polymorphisms (SNPs) in cytokine and TF genes in a Zimbabwean population, and further relate SNPs to susceptibility to schistosomiasis and cytokine levels. Individuals (N = 850) were genotyped for SNPs across the cytokines IL4, IL10, IL13, IL33, and IFNG, and their TFs STAT4, STAT5A/B, STAT6, GATA3, FOXP3, and TBX21 to determine allele frequencies. Circulatory levels of systemic and parasite-specific IL-4, IL-5, IL-10, IL-13, and IFNγ were quantified via enzyme-linked immunosorbent assay. Schistosoma haematobium infection was determined by enumerating parasite eggs excreted in urine by microscopy. SNP allele frequencies were related to infection status by case-control analysis and logistic regression, and egg burdens and systemic and parasite-specific cytokine levels by analysis of variance and linear regression. Novel findings were i) IL4 rs2070874*T's association with protection from schistosomiasis, as carriage of ≥1 allele gave an odds ratio of infection of 0.597 (95% CIs, 0.421-0.848, p = 0.0021) and IFNG rs2069727*G's association with susceptibility to schistosomiasis as carriage of ≥1 allele gave an odds ratio of infection of 1.692 (1.229-2.33, p = 0.0013). Neither IL4 rs2070874*T nor IFNG rs2069727*G were significantly associated with cytokine levels. This study found TH2-upregulating SNPs were more frequent among the Zimbabwean sample compared to African and European populations, highlighting the value of immunogenetic studies of African populations in the context of infectious diseases and other conditions, including allergic and atopic disease. In addition, the identification of novel infection-associated alleles in both TH1- and TH2-associated genes highlights the role of both in regulating and controlling responses to Schistosoma.

Anaphylaxis: Focus on Transcription Factor Activity

Anaphylaxis is a severe allergic reaction, rapid in onset, and can lead to fatal consequences if not promptly treated. The incidence of anaphylaxis has risen at an alarming rate in past decades and continues to rise. Therefore, there is a general interest in understanding the molecular mechanism that leads to an exacerbated response. The main effector cells are mast cells, commonly triggered by stimuli that involve the IgE-dependent or IgE-independent pathway. These signaling pathways converge in the release of proinflammatory mediators, such as histamine, tryptases, prostaglandins, etc., in minutes. The action and cell targets of these proinflammatory mediators are linked to the pathophysiologic consequences observed in this severe allergic reaction. While many molecules are involved in cellular regulation, the expression and regulation of transcription factors involved in the synthesis of proinflammatory mediators and secretory granule homeostasis are of special interest, due to their ability to control gene expression and change phenotype, and they may be key in the severity of the entire reaction. In this review, we will describe our current understanding of the pathophysiology of human anaphylaxis, focusing on the transcription factors' contributions to this systemic hypersensitivity reaction. Host mutation in transcription factor expression, or deregulation of their activity in an anaphylaxis context, will be updated. So far, the risk of anaphylaxis is unpredictable thus, increasing our knowledge of the molecular mechanism that leads and regulates mast cell activity will enable us to improve our understanding of how anaphylaxis can be prevented or treated.

The association between IL18, FOXP3 and IL13 genes polymorphisms and risk of allergic rhinitis: a meta-analysis

OBJECTIVES

Allergic rhinitis (AR) is a chronic inflammatory disease of nasal mucosa. Loss of function of Th17 cells and regulatory T (Treg) cells plays a role in the pathogenesis of AR. IL18, FOXP3, and IL13 are key genes in the development of AR. However, the genetic associations between IL18, FOXP3 and IL13 genes polymorphisms and AR risk were inconclusive yet.

METHODS

A meta-analysis was performed by searching through Pubmed, EMBASE, web of science and CNKI databases. The ORs and 95%CIs were used to assess the genetic association between the allelic, dominant and recessive models of IL18, FOXP3 and IL13 genes polymorphisms and AR risk.

RESULTS

A total of 15 articles (6 for FOXP3, 5 for IL18, and 5 for IL13) were enrolled in the present study. No association was detected between the IL18 rs187238, rs1946518, rs360721, FOXP3 rs2232365, rs3761548 and IL13 rs1800925 polymorphisms and AR risk (p > 0.05). Significant associations were observed between the allelic (p = 0.001, OR 1.32, 95% CI 1.12-1.56), dominant (p = 0.005, OR 1.43, 95% CI 1.11-1.83) and recessive models (p = 0.01, OR 1.64, 95% CI 1.13, 2.40) of IL13 rs20541 and AR risk. Subgroup analysis based on ethnicity revealed that the IL13 rs20541 was significantly associated with AR risk in Asian population (allelic model: p = 0.009, OR 1.36, 95% CI 1.13-1.63, dominant model: p = 0.005, OR 1.43, 95% CI 1.11-1.83; recessive model: p = 0.01, OR 1.64, 95% CI 1.13-2.40).

CONCLUSIONS

IL13 rs20541 may contribute to the risk of AR in Asian population. To confirm these results, larger number of case-control study with more subjects is necessary in the future.

Identification of a T follicular helper cell subset that drives anaphylactic IgE

Cross-linking of high-affinity immunoglobulin E (IgE) results in the life-threatening allergic reaction anaphylaxis. Yet the cellular mechanisms that induce B cells to produce IgE in response to allergens remain poorly understood. T follicular helper (T_FH) cells direct the affinity and isotype of antibodies produced by B cells. Although T_FH cell-derived interleukin-4 (IL-4) is necessary for IgE production, it is not sufficient. We report a rare population of IL-13-producing T_FH cells present in mice and humans with IgE to allergens, but not when allergen-specific IgE was absent or only low-affinity. These "T_FH13" cells have an unusual cytokine profile (IL-13^hiIL-4^hiIL-5^hiIL-21^lo) and coexpress the transcription factors BCL6 and GATA3. T_FH13 cells are required for production of high- but not low-affinity IgE and subsequent allergen-induced anaphylaxis. Blocking T_FH13 cells may represent an alternative therapeutic target to ameliorate anaphylaxis.

GATA3 Gene Polymorphisms Associated with Allergic Rhinitis in an Iranian Population

BACKGROUND

The development of allergic rhinitis (AR) is caused by the interaction between genetic predisposition and environmental factors. In this study, the association between GATA3 single nucleotide polymorphisms and AR in an Iranian population was identified.

METHODS

This case-control study was performed on 86 patients with AR and 86 healthy subjects. This study aimed to evaluate a potential association between two GATA3 SNPs, rs1269486 and rs2229360, and AR. Blood samples were collected and DNA was extracted for the evaluation of these SNPs by RFLP-PCR.

RESULTS

A statistically-significant association was found between rs1269486 and AR (P<0.001). The frequencies of the A and GA genotypes were less in patients than in controls. The frequencies of the G allele and the GG genotype were greater in patients than in controls (P < 0.001).

CONCLUSIONS

SNP rs1269486 of GATA3 was associated with AR and sensitivity to aeroallergens in our population. Because of the significance of this gene in AR, studying the association between GATA3 polymorphisms and AR is recommended for other populations.

Variations in T Cell Transcription Factor Sequence and Expression Associated with Resistance to the Sheep Nematode Teladorsagia circumcincta

This study used selected lambs that varied in their resistance to the gastrointestinal parasite Teladorsagia circumcincta. Infection over 12 weeks identified susceptible (high adult worm count, AWC; high fecal egg count, FEC; low body weight, BW; low IgA) and resistant sheep (no/low AWC and FEC, high BW and high IgA). Resistance is mediated largely by a Th2 response and IgA and IgE antibodies, and is a heritable characteristic. The polarization of T cells and the development of appropriate immune responses is controlled by the master regulators, T-bet (TBX21), GATA-3 (GATA3), RORγt (RORC2) and RORα (RORA); and several inflammatory diseases of humans and mice are associated with allelic or transcript variants of these transcription factors. This study tested the hypothesis that resistance of sheep to T. circumcincta is associated with variations in the structure, sequence or expression levels of individual master regulator transcripts. We have identified and sequenced one variant of sheep TBX21, two variants of GATA3 and RORC2 and five variants of RORA from lymph node mRNA. Relative RT-qPCR analysis showed that TBX21, GATA3 and RORC2 were not significantly differentially-expressed between the nine most resistant (AWC, 0; FEC, 0) and the nine most susceptible sheep (AWC, mean 6078; FEC, mean 350). Absolute RT-qPCR on all 45 animals identified RORVv5 as being significantly differentially-expressed (p = 0.038) between resistant, intermediate and susceptible groups; RORCv2 was not differentially-expressed (p = 0.77). Spearman’s rank analysis showed that RORAv5 transcript copy number was significantly negatively correlated with parameters of susceptibility, AWC and FEC; and was positively correlated with BW. RORCv2 was not correlated with AWC, FEC or BW but was significantly negatively correlated with IgA antibody levels. This study identifies the full length RORA variant (RORAv5) as important in controlling the protective immune response to T. circumcincta infection in sheep.

Lineage-affiliated transcription factors bind the Gata3 Tce1 enhancer to mediate lineage-specific programs

The transcription factor GATA3 is essential for the genesis and maturation of the T cell lineage, and GATA3 dysregulation has pathological consequences. Previous studies have shown that GATA3 function in T cell development is regulated by multiple signaling pathways and that the Notch nuclear effector, RBP-J, binds specifically to the Gata3 promoter. We previously identified a T cell-specific Gata3 enhancer (Tce1) lying 280 kb downstream from the structural gene and demonstrated in transgenic mice that Tce1 promoted T lymphocyte-specific transcription of reporter genes throughout T cell development; however, it was not clear if Tce1 is required for Gata3 transcription in vivo. Here, we determined that the canonical Gata3 promoter is insufficient for Gata3 transcriptional activation in T cells in vivo, precluding the possibility that promoter binding by a host of previously implicated transcription factors alone is responsible for Gata3 expression in T cells. Instead, we demonstrated that multiple lineage-affiliated transcription factors bind to Tce1 and that this enhancer confers T lymphocyte-specific Gata3 activation in vivo, as targeted deletion of Tce1 in a mouse model abrogated critical functions of this T cell-regulatory element. Together, our data show that Tce1 is both necessary and sufficient for critical aspects of Gata3 T cell-specific transcriptional activity.

Association of interleukin-13 SNP rs20541 with allergic rhinitis risk: a meta-analysis

Studies investigating the association between interleukin-13 (IL-13) single nucleotide polymorphism (SNP) rs20541 and allergic rhinitis (AR) risk have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible association of IL-13 SNP rs20541 with AR risk. Eight studies were included in the present meta-analysis (2153 cases and 3931 controls). The combined results based on all studies showed that IL-13 SNP rs20541 was associated with increased AR risk (Gln versus Arg: odds ratio (OR)=1.18, 95% confidence interval (CI)=1.08-1.30; Gln/Gln versus Arg/Arg: OR=1.52, 95% CI=1.20-1.92; Arg/Gln+Gln/Gln versus Arg/Arg: OR=1.19, 95% CI=1.06-1.33; Gln/Gln versus Arg/Gln+Arg/Arg: OR=1.42, 95% CI=1.13-1.79). When stratifying for race, IL-13 SNP rs20541 exhibited increased AR risk in Asians (Gln versus Arg: OR=1.20, 95% CI=1.06-1.36; Gln/Gln versus Arg/Arg: OR=1.57, 95% CI=1.17-2.12; Arg/Gln+Gln/Gln versus Arg/Arg: OR=1.22, 95% CI=1.04-1.44; Gln/Gln versus Arg/Gln+Arg/Arg: OR=1.45, 95% CI=1.09-1.93), while no significant association was detected in Caucasians (Gln versus Arg: OR=1.28, 95% CI=0.93~1.78; Gln/Gln versus Arg/Arg: OR=1.42, 95% CI=0.96-2.11; Arg/Gln+Gln/Gln versus Arg/Arg: OR=1.35, 95% CI=0.89-2.05; Gln/Gln versus Arg/Gln+Arg/Arg: OR=1.37, 95% CI=0.93-2.02). This meta-analysis supported that IL-13 SNP rs20541 was associated with AR, particularly in Asians.

Power of a reproducing kernel-based method for testing the joint effect of a set of single-nucleotide polymorphisms

This study explored a semi-parametric method built upon reproducing kernels for estimating and testing the joint effect of a set of single nucleotide polymorphisms (SNPs). The kernel adopted is the identity-by-state kernel that measures SNP similarity between subjects. In this article, through simulations we first assessed its statistical power under different situations. It was found that in addition to the effect of sample size, the testing power was impacted by the strength of association between SNPs and the outcome of interest, and by the SNP similarity among the subjects. A quadratic relationship between SNP similarity and testing power was identified, and this relationship was further affected by sample sizes. Next we applied the method to a SNP-lung function data set to estimate and test the joint effect of a set of SNPs on forced vital capacity, one type of lung function measure. The findings were then connected to the patterns observed in simulation studies and further explored via variable importance indices of each SNP inferred from a variable selection procedure.

Interaction between IL13 genotype and environmental factors in the risk for allergic rhinitis in Korean children

BACKGROUND

The prevalence of allergic rhinitis (AR) is increasing worldwide. Allergic diseases develop in susceptible subjects when they are exposed to specific environmental factors.

OBJECTIVE

We analyzed changes in the prevalence of AR and identified genetic and environmental factors in early childhood that affect risk.

METHODS

We used the International Study of Asthma and Allergies in Childhood questionnaire to collect data on AR, allergies, and environmental exposures from 4554 elementary school students from 5 areas of Seoul, Korea, in 2008. We also obtained DNA from 1050 subjects from 1 area of Seoul for genotype analysis of IL13.

RESULTS

We identified genetic and environmental factors during infancy and early childhood that increased the risk for current AR (resulting in a diagnosis of AR and AR symptoms in the past 12 months) in elementary school-aged children. These included allergic disease in parents and antibiotic use in infants, allergic disease in parents and exposure of infants to mold, and allergic disease in parents and moving an infant to a newly built house. The risk of current AR also increased in subjects with GA or AA at nucleotide 2044 in IL13 who had been exposed to mold in the home during infancy (adjusted odds ratio, 3.27; 95% CI, 1.75-6.11) compared with subjects who had GG at this position and had not been exposed to mold (adjusted odds ratio, 3.27; 95% CI, 1.75-6.11).

CONCLUSION

The prevalence of AR is increasing in Korean children. Children with a family history of allergic disease and exposure to specific environmental risk factors during infancy are more likely to have AR. Children with GA or AA at IL13(+2044) are at increased risk for AR when exposed to mold in the home during the first year of life.

Association of interleukin-13 SNP rs1800925 with allergic rhinitis risk: a meta-analysis based on 1,411 cases and 3169 controls

Studies investigating the association between interleukin-13 (IL-13) single nucleotide polymorphism (SNP) rs1800925 and allergic rhinitis risk have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible association of IL-13 SNP rs1800925 with allergic rhinitis risk. The relevant studies were identified through a search of PubMed, Embase, ISI Web of Knowledge and Chinese National Knowledge Infrastructure until December 2011 and selected on the basis of the established inclusion criteria for publications. Five studies were included in the present meta-analysis (1411 cases and 3169 controls). The combined results based on all studies showed that IL-13 SNP rs1800925 was not associated with increased allergic rhinitis risk (T versus C: odds ratio (OR)=1.06, 95% confidence interval (CI)=0.94-1.20; C/T versus C/C: OR=1.12, 95% CI=0.97-1.29; T/T versus C/C: OR=1.00, 95% CI=0.69-1.44; C/T+T/T versus CC: OR=1.10, 95% CI=0.96-1.27; T/T versus C/C+C/T: OR=0.91, 95% CI=0.64-1.31). This meta-analysis supported that IL-13 SNP rs1800925 was not associated with allergic rhinitis.

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.

Association study on IL4, IL13 and IL4RA polymorphisms in mite-sensitized persistent allergic rhinitis in a Chinese population

Background

The IL4, IL13, and IL4 receptor α chain (IL4RA) genes are candidate genes for atopic diseases. We hypothesized that the polymorphisms in these genes are associated with persistent allergic rhinitis (PER).

Objective

To investigate the association of the potential functional polymorphisms in IL4, IL13, and IL4RA with PER induced by house dust mites in a Chinese population.

Methods

Using the TaqMan method, we genotyped six single nucleotide polymorphisms (SNPs) including C-590T in IL4, C-1055T and Arg130Gln in IL13, and Ile50Val, Ser478Pro and Gln551Arg in IL4RA, in a case-control study of 265 patients with PER and 275 healthy controls.

Results

We found that the CT/CC genotypes in IL4 C-590T were associated with a significantly decreased risk of mite-sensitized PER [adjusted odds ratio (OR)  = 0.64, 95% confidence interval (CI) 0.45–0.92], compared to the TT genotype. Furthermore, PER patients with CT/CC genotypes had significantly lower serum levels of total IgE than those with TT genotype (P = 0.001). However, there was no significant association of the IL13 and IL4RA polymorphisms with mite-sensitized PER (P>0.05).

Conclusions

Our results suggest that the C-590T polymorphism in IL4 may contribute to the susceptibility to mite-sensitized PER in a Chinese population.

Association pattern of interleukin-1 receptor-associated kinase-4 gene polymorphisms with allergic rhinitis in a Han Chinese population

OBJECTIVE

Interleukin-1 receptor-associated kinase-4 (IRAK-4) encodes a kinase that is essential for NF-kB activation in Toll-like receptor and T-cell receptor signaling pathways, indicating a possible crosstalk between innate and acquired immunities. We attempted to determine whether the polymorphisms in the Interleukin-1 receptor-associated kinase-4 (IRAK-4) gene are associated with allergic rhinitis (AR) in the Han Chinese population.

METHODS

A population of 379 patients with AR and 333 healthy controls was studied. Blood was drawn for DNA extraction and total serum immunoglobulin E (IgE). A total of 11 single nucleotide polymorphisms (SNPs) in IRAK-4 were selected and individually genotyped.

RESULTS

Significant allelic differences between cases and controls were obtained for the SNP of rs3794262 in the IRAK-4 gene. In the stratified analysis for gender, two SNPs (rs4251431 and rs6582484) in males appeared as significant associations. Subgroup analysis for the presence of different allergen sensitivities displayed associations only in the house dust mite-allergic cohorts (rs3794262, rs4251481). None of the selected SNPs in IRAK-4 was associated with total IgE level. The haplotype analysis indicated GCCTGCGA was significantly associated with AR. The SNP-SNP interaction information analysis indicated that the selected sets of polymorphisms had no synergistic effect.

CONCLUSIONS

Our findings did not support the potential contribution of the IRAK-4 gene to serum IgE levels. However, the results demonstrated a gender- and allergen-dependant association pattern between polymorphisms in IRAK-4 and AR in Chinese population.

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.

Risks of exposure to occupational asthmogens in atopic and nonatopic asthma: a case-control study in Taiwan

RATIONALE

Asthma is often work-related and can be classified as atopic or nonatopic on the basis of its pathogenesis. Few studies have reported an association between exposure to occupational asthmogens and asthma with and without atopy.

OBJECTIVES

We investigated, in adults with asthma, whether occupational exposure to asthmogens influenced the risk of having atopic or nonatopic asthma, and their level of lung function.

METHODS

We recruited 504 hospital-based adults with current asthma, 504 community-based control subjects, and 504 hospital-based control subjects in southern Taiwan. Asthma with atopy was defined as having asthma in combination with an increase in total IgE (≥100 U/ml) or a positive Phadiatop test (≥0.35 Pharmacia arbitrary unit/L) (Pharmacia ImmunoCAP; Pharmacia, Uppsala, Sweden). Occupational exposure to asthmogens was assessed with an asthma-specific job exposure matrix.

MEASUREMENTS AND MAIN RESULTS

We found a significant association between atopic asthma and exposure to high molecular weight asthmogens (adjusted odds ratio [AOR], 4.0; 95% confidence interval [CI], 1.8-8.9). Nonatopic asthma was significantly associated with exposure to low molecular weight asthmogens (AOR, 2.6; 95% CI, 1.6-4.3), including industrial cleaning agents and metal sensitizers. Agriculture was associated with both atopic and nonatopic asthma (AOR, 7.8; 95% CI, 2.8-21.8; and AOR, 4.1; 95% CI, 1.3-13.0, respectively). The ratio of FEV₁ to FVC in the high-risk group was significantly lower than in the no-risk group (P = 0.026) in currently employed patients with asthma.

CONCLUSIONS

In adults with asthma, occupational exposure to high and low molecular weight asthmogens appears to produce differential risks for atopic and nonatopic asthma.

Polymorphisms in IL13 pathway genes in asthma and chronic obstructive pulmonary disease

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are chronic respiratory diseases involving an interaction between genetic and environmental factors. Interleukin-13 (IL13) has been suggested to have a role in both asthma and COPD. We investigated whether single nucleotide polymorphisms (SNPs) in the IL13 pathway may contribute to the susceptibility and severity of asthma and COPD in adults.

METHODS

Twelve SNPs in IL13 pathway genes -IL4, IL13, IL4RA, IL13RA1, IL13RA2 and STAT6- were genotyped in subjects with asthma (n = 299) and in subjects with COPD or healthy smokers (n = 992). Genetic association was evaluated using genotype and allele models for asthma severity, atopy phenotypes and COPD susceptibility. Linear regression was used to determine the effects of polymorphism on baseline lung function (FEV(1), FEV(1)/FVC).

RESULTS

In asthmatics, three IL13 SNPs - rs1881457(-1512), rs1800925(-1111) and rs20541(R130Q) - were associated with atopy risk. One SNP in IL4RA1 [rs1805010(I75V)] was associated with asthma severity, and several IL13 SNPs showed borderline significance. IL13 SNPs rs1881457(-1512) and rs1800925(-1111) were associated with better FEV(1) and FEV(1)/FVC in asthmatics. IL13 SNPs rs2066960(intron 1), rs20541(R130Q) and rs1295685(exon 4) were associated with COPD risk and lower baseline lung function in the recessive model. In females, but not in males, rs2250747 of the IL13RA1 gene was associated with COPD and lower FEV(1).

CONCLUSION

These data suggest that IL13 SNPs (promoter and coding region) and, to a lesser extent, IL4RA SNPs may contribute to atopy and asthma. We also provide tentative evidence that IL13 SNPs in the coding region may be of significance in COPD susceptibility.

Inhibition of acidic mammalian chitinase by RNA interference suppresses ovalbumin-sensitized allergic asthma

Asthma, a chronic helper T cell type 2-mediated inflammatory disease, is characterized by airway hyperresponsiveness and inflammation. Growing evidence suggests that increased expression of acidic mammalian chitinase (AMCase) may play a role in the pathogenesis of asthma. In the present study, we sought to develop an RNA interference approach to suppress allergic asthma in mice through silencing of AMCase expression. Mice sensitized with ovalbumin (OVA) were intratracheally administered a recombinant adeno-associated virus expressing short hairpin RNA (rAAV-shRNA) against AMCase. In OVA-sensitized mice, the development of allergic symptoms was significantly associated with elevated AMCase expression. After administration of rAAV-shRNA, there was a significant reduction of AMCase expression in the lung and in bronchoalveolar lavage fluid (BALF) cells of sensitized mice. Sensitized mice receiving rAAV-shRNA showed a significant improvement in allergic symptoms, including airway hyperresponsiveness (AHR), eosinophil infiltration, eotaxin, interleukin-13 secretion in BALF, and serum OVA-specific IgE level. Our data suggest the hyperexpression of AMCase in asthma can be suppressed by rAAV-mediated shRNA. Silencing AMCase expression by shRNA may be a promising therapeutic strategy in asthma.

TLR-related pathway analysis: novel gene-gene interactions in the development of asthma and atopy

BACKGROUND

The toll-like receptor (TLR)-related pathway is important in host defence and may be crucial in the development of asthma and atopy. Numerous studies have shown associations of TLR-related pathway genes with asthma and atopy phenotypes. So far it has not been investigated whether gene-gene interactions in this pathway contribute to atopy and asthma development.

METHODS

One hundred and sixty-nine haplotype tagging single nucleotide polymorphisms (SNPs) of 29 genes (i.e. membrane and intracellular receptors, TLR4 or lipopolysaccharide-binding/facilitating proteins, adaptors, interleukin-1 receptor associated kinases, kinases, chaperone molecules, transcription factors and inhibitors) were analysed for single- and multilocus associations with atopy [total and specific immunglobulin E (IgE) at 1-2 and 6-8 years] and asthma (6-8 years). A total of 3062 Dutch children from the birth cohorts PIAMA, PREVASC and KOALA (Allergenic study) were investigated. Chi-squared test, logistic regression and the data mining approach multifactor dimensionality reduction method (MDR) were used in analysis.

RESULTS

Several genes in the TLR-related pathway were associated with atopy and/or asthma [e.g. IL1RL1, BPI, NOD1, NOD2 and MAP3K7IP1]. Multiple, single associations were found with the phenotypes under study. MDR analysis showed novel, significant gene-gene interactions in association with atopy and asthma phenotypes (e.g. IL1RL1 and TLR4 with sIgE to indoor allergens and IRAK1, NOD1 and MAP3K7IP1 with asthma). Interestingly, gene-gene interactions were identified with SNPs that did not have an effect on their own.

CONCLUSION

Our unbiased approach provided suggestive evidence for interaction between several TLR-related pathway genes important in atopy and/or asthma development and pointed to novel genes.

HLX1 gene variants influence the development of childhood asthma

BACKGROUND

Major transcription factors controlling T(H)1 and T(H)2 development, such as T-box transcription factor and GATA3, might be centrally involved in asthma and atopic diseases. Only recently, the homeobox transcription factor H.20-like homeobox 1 (HLX1), interacting closely with T-box transcription factor, has been identified as an important regulator of T(H)1 differentiation and suppressor of T(H)2 commitment.

OBJECTIVE

We investigated whether genetic variations in the HLX1 gene exist and whether these could affect the development of childhood asthma.

METHODS

The HLX1 gene was resequenced in 80 chromosomes. Associations between identified polymorphisms, asthma, and atopic diseases were investigated in German children (total n = 3099) from the cross-sectional International Study of Asthma and Allergy in Childhood phase II. Functional properties of polymorphisms were studied by using luciferase reporter gene assays and electrophoretic mobility shift assays in T cells. All statistical analyses were performed with SAS/Genetics software (SAS Institute, Inc, Cary, NC).

RESULTS

Nineteen polymorphisms were identified in the HLX1 gene, and 2 tagging single nucleotide polymorphisms representing 7 polymorphisms were associated with childhood asthma in our study population. Two promoter polymorphisms, C-1407T and C-742G, contained in 1 tagging block were associated with asthma (odds ratio, 1.44; 95% CI, 1.11-1.86; P = .0061), significantly decrease promoter transactivation, and disrupt specificity protein-transcription factor binding in in vitro experiments.

CONCLUSIONS

Our data suggest that polymorphisms in the HLX1 gene increase the risk for childhood asthma. On the cellular level, altered binding of specificity protein-transcription factors to the HLX1 promoter and subsequent changes in HLX1 gene expression might contribute to these effects.

Epigenetic regulation of Th2 cytokine expression in atopic diseases

The immune response to allergens starts with stimulation of a naïve T helper (Th) cell and its differentiation into a Th2 cell, expressing the cytokines interleukin (IL)-4, IL-5 and IL-13 responsible for the allergic response. The initial pattern of cytokine expression is retained during restimulation and division of the Th2 cell to create a population of specific allergen-responsive memory Th2 cells. Both, the coordinate cytokine expression and the inherited cytokine memory are specified by epigenetic mechanisms. Th2-specific changes in chromatin configuration at the Th2 locus act locally to open DNA, allowing recruitment of transcriptional machinery and rapid induction of cytokine expression. Induction of the transcription factor GATA3 is critical to this process. Loss of DNA methylation at the Th2 locus during differentiation from a naïve Th cell correlates to increased histone acetylation, consistent with the expression of IL-4, IL-5 and IL-13. The silencing of the Th2 locus in Th1 cells was associated with repressive histone methylation. These data indicate the formation of a 'poised' chromatin configuration at the Th2 locus that in combination with specific transcription factors specifies the cytokine repertoire in daughter cells and allows the immediate, rapid induction of cytokines by those cells in response to allergen.