Novel dinucleotide repeat polymorphism in the first exon of the STAT-6 gene is associated with allergic diseases

RELEVANCE OF CODING VARIATION IN FILAGGRIN AND DOCK8 IN FINNISH PEDIATRIC PATIENTS WITH EARLY-ONSET MODERATE-TO-SEVERE ATOPIC DERMATITIS

Early-onset, persistent atopic dermatitis (AD) is proposed as a distinct subgroup that may have specific genotypic features. FLG gene loss-of-function variants are the best known genetic factors contributing to epidermal barrier impairment and eczema severity. In a cohort of 140 Finnish children with early-onset moderate-to-severe AD, we investigated the effect of coding variation in FLG and 13 other genes with epidermal barrier or immune function through the use of targeted amplicon sequencing and genotyping. A FLG loss-of-function variant (Arg501Ter, Ser761fs, Arg2447Ter, or Ser3247Ter) was identified in 20 of 140 patients showing higher transepidermal water loss values than patients without these variants. Total FLG loss-of-function variant frequency (7.14%) was significantly higher than in the general Finnish population (2.34%). When tested separately, only Arg2447Ter showed a significant association with AD (P = 0.003104). In addition, a modest association with moderate-to-severe pediatric AD was seen for rs12730241 and rs6587667 (FLG2:Gly137Glu). Loss-of-function variants, previously reported pathogenic variants, or statistically significant enrichment of nonsynonymous coding region variants were not found in the 13 candidate genes studied by amplicon sequencing. However, higher IgE and eosinophil counts were found in carriers of potentially pathogenic DOCK8 missense variants, suggesting that the role of DOCK8 variation in AD should be further investigated in larger cohorts.

The translational revolution in atopic dermatitis: the paradigm shift from pathogenesis to treatment

Atopic dermatitis (AD) is the most common inflammatory skin disease, and it is considered a complex and heterogeneous condition. Different phenotypes of AD, defined according to the patient age at onset, race, and ethnic background; disease duration; and other disease characteristics, have been recently described, underlying the need for a personalized treatment approach. Recent advancements in understanding AD pathogenesis resulted in a real translational revolution and led to the exponential expansion of the therapeutic pipeline. The study of biomarkers in clinical studies of emerging treatments is helping clarify the role of each cytokine and immune pathway in AD and will allow addressing the unique immune fingerprints of each AD subset. Personalized medicine will be the ultimate goal of this targeted translational research. In this review, we discuss the changes in the concepts of both the pathogenesis of and treatment approach to AD, highlight the scientific rationale behind each targeted treatment and report the most recent clinical efficacy data.

The JAK/STAT Pathway and Its Selective Inhibition in the Treatment of Atopic Dermatitis: A Systematic Review

In recent years, the broadening understanding of the pathogenesis of atopic dermatitis (AD) has led to the development of novel therapeutic molecules, that target core inflammatory components of the disease. The Janus kinase (JAK)/signal transducer and activation of transcription (STAT) pathway constitutes the principal signaling cascade for a large number of cytokines and growth factors and is involved in intracellular signal transduction and subsequent regulation of gene transcription. Current knowledge suggests that the robust activation of the T-helper (Th)-2 [interleukin (IL)-4, IL-5, IL-13, IL-31] and Th22 (IL-22) immune responses in both skin and serum plays a pivotal role in the immunopathogenesis of AD especially at the acute stage, followed by a variable degree of Th1 (interferon-γ, tumor necrosis factor alpha) and Th17 (IL-17) activation in chronic disease. Of note, most of the aforementioned inflammatory cytokines utilize the JAK/STAT pathway for downstream signal transduction, explaining the emerging role of JAK inhibitors in the therapeutic armamentarium of AD. The present systematic review aims to discuss the involvement of JAK/STAT pathway in the pathogenesis of AD and summarize the clinical data available on the efficacy and safety of JAK inhibitors which have been used in the treatment of AD thus far.

Janus Kinase Inhibitors for the Treatment of Atopic Dermatitis: Focus on Abrocitinib, Baricitinib, and Upadacitinib

Atopic dermatitis (AD) is a clinically heterogenous, inflammatory skin condition with a high impact on patients' daily activities that remains difficult to treat. The knowledge acquired over the last decade on AD pathophysiology and disease burden led to the development of new targeted therapeutic options that enable clinicians to better manage AD patients. The JAK/STAT signaling pathway modulates several immune pathways (T helper (Th)1, Th2, Th17, and Th22 cells) that have been found to be involved in AD pathogenesis. For this reason, JAK inhibitors emerged as a possible therapy for AD. Baricitinib, upadacitinib, and abrocitinib are the three oral JAK inhibitors already approved or in advanced clinical development for this purpose. The results showed that this drug class is highly effective achieving symptomatic relief (itch control) in the short term, as well as improving disease severity in the short and medium term. However, their efficacy should be balanced with possible side effects, that have been reported in clinical trials. More data on the long-term efficacy and safety, as well as from head-to-head comparisons and from real-world setting will be crucial to position oral JAK inhibitors in the AD therapeutic armamentarium.

Potential Metabolic Biomarkers in Adult Asthmatics

Asthma is the most common chronic airway inflammation, with multiple phenotypes caused by complicated interactions of genetic, epigenetic, and environmental factors. To date, various determinants have been suggested for asthma pathogenesis by a new technology termed omics, including genomics, transcriptomics, proteomics, and metabolomics. In particular, the systematic analysis of all metabolites in a biological system, such as carbohydrates, amino acids, and lipids, has helped identify a novel pathway related to complex diseases. These metabolites are involved in the regulation of hypermethylation, response to hypoxia, and immune reactions in the pathogenesis of asthma. Among them, lipid metabolism has been suggested to be related to lung dysfunction in mild-to-moderate asthma. Sphingolipid metabolites are an important mediator contributing to airway inflammation in obese asthma and aspirin-exacerbated respiratory disease. Although how these molecular variants impact the disease has not been completely determined, identification of new causative factors may possibly lead to more-personalized and precise pathway-specific approaches for better diagnosis and treatment of asthma. In this review, perspectives of metabolites related to asthma and clinical implications have been highlighted according to various phenotypes.

Janus Kinase Inhibitors in Dermatology: Part 2: Applications in Psoriasis, Atopic Dermatitis, and Other Dermatoses

Dermatologists' interest in the Janus-associated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been growing as evidence builds to support its key role in the pathogenesis of inflammatory skin diseases. Because certain proinflammatory cytokines use the JAK/STAT pathway for signal transduction, it has become a promising therapeutic target in diseases where selective modulation of the immune system can be useful. We aim to review current knowledge of the JAK/STAT signaling pathway and its role in immune-mediated skin diseases. In the second part of the review we cover the efficacy and safety of oral and topical JAK inhibitors in the treatment of psoriasis, atopic dermatitis, and other skin diseases.

Janus Kinase Inhibitors in Dermatology: Part 2: Applications in Psoriasis, Atopic Dermatitis, and Other Dermatoses

Dermatologists' interest in the Janus-associated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been growing as evidence builds to support its key role in the pathogenesis of inflammatory skin diseases. Because certain proinflammatory cytokines use the JAK/STAT pathway for signal transduction, it has become a promising therapeutic target in diseases where selective modulation of the immune system can be useful. We aim to review current knowledge of the JAK/STAT signaling pathway and its role in immune-mediated skin diseases. In the second part of the review we cover the efficacy and safety of oral and topical JAK inhibitors in the treatment of psoriasis, atopic dermatitis, and other skin diseases.

JAK Inhibitors for Atopic Dermatitis: An Update

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases. AD is driven by barrier dysfunction and abnormal immune activation of T helper (Th) 2, Th22, and varying degrees of Th1 and Th17 among various subtypes. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) and spleen tyrosine kinase (SYK) pathways are involved in signaling of several AD-related cytokines, such as IFN-γ, IL-4, IL-13, IL-31, IL-33, IL-23, IL-22, and IL-17, mediating downstream inflammation and barrier alterations. While AD is primarily Th2-driven, the clinical and molecular heterogeneity of AD endotypes highlights the unmet need for effective therapeutic options that target more than one immune axis and are safe for long-term use. The JAK inhibitors, which target different combinations of kinases, have overlapping but distinct mechanisms of action and safety profiles. Several topical and oral JAK inhibitors have been shown to decrease AD severity and symptoms. A review of the JAK and SYK inhibitors that are currently undergoing evaluation for efficacy and safety in the treatment of AD summarizes available data on a promising area of therapeutics and further elucidates the complex molecular interactions that drive AD.

The Genetics and Epigenetics of Atopic Dermatitis-Filaggrin and Other Polymorphisms

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by a combination of genetic and environmental factors. Genetic evidences depict a complex network comprising by epidermal barrier dysfunctions and dysregulation of innate and adaptive immunity in the pathogenesis of AD. Mutations in the human filaggrin gene (FLG) are the most significant and well-replicated genetic mutation associated with AD, and other mutations associated with epidermal barriers such as SPINK5, FLG-2, SPRR3, and CLDN1 have all been linked to AD. Gene variants may also contribute to the abnormal innate and adaptive responses found in AD, including mutations in PRRs and AMPs, TSLP and TSLPR, IL-1 family cytokines and receptors genes, vitamin D pathway genes, FCER1A, and Th2 and other cytokines genes. GWAS and Immunochip analysis have identified a total of 19 susceptibility loci for AD. Candidate genes at these susceptibility loci identified by GWAS and Immunochip analysis also suggest roles for epidermal barrier functions, innate and adaptive immunity, interleukin-1 family signaling, regulatory T cells, the vitamin D pathway, and the nerve growth factor pathway in the pathogenesis of AD. Increasing evidences show the modern lifestyle (i.e., the hygiene hypothesis, Western diet) and other environmental factors such as pollution and environmental tobacco smoke (ETS) lead to the increasing prevalence of AD with the development of industrialization. Epigenetic alterations in response to these environmental factors, including DNA methylation and microRNA related to immune system and skin barriers, have been found to contribute to the pathogenesis of AD. Genetic variants and epigenetic alteration might be the key tools for the molecular taxonomy of AD and provide the background for the personalized management.

The function of activatable cell-penetrating peptides in human intrahepatic bile duct epithelial cells

This study aimed to investigate the function of Activatable Cell-Penetrating Peptides (ACPP) in detecting the changes of human intrahepatic bile duct epithelial cell(hIBDEC). ACPP, which target matrix metalloproteinases, were constructed. All were labeled with FITC and Gd-DTPA at the N-terminal. Fluorescence microscopy was used to observe the fluorescence intensity inside hIBDEC after stimulating with different concentrations of LPS and incubating with different concentrations of ACPP to determine the optimal concentration range for LPS stimulation and the optimal concentration for FITC-ACPP effect. Flow cytometry and magnetic resonance imaging were used to detect fluorescence signal intensity and nuclear magnetic resonance signal intensity, respectively, after stimulating with different concentrations of LPS. LPS stimulation time and ACPP incubation time were also evaluated, and variance analysis was conducted to analyze intracellular signal change characteristics for every group. Activatable Cell-Penetrating Peptides (ACPP), which were marked with FITC and Gd-DTPA had target-penetrating activity. The intracellular signal intensity gradually increased with the increase in LPS stimulation time and ACPP incubation time within a certain range; however, it did not increase with the increase of LPS concentration. ACPP can be used for imaging hIBDEC with epithelial-mesenchymal transition.

Genetic and epigenetic studies of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory disease caused by the complex interaction of genetic, immune and environmental factors. There have many recent discoveries involving the genetic and epigenetic studies of AD.

METHODS

A retrospective PubMed search was carried out from June 2009 to June 2016 using the terms "atopic dermatitis", "association", "eczema", "gene", "polymorphism", "mutation", "variant", "genome wide association study", "microarray" "gene profiling", "RNA sequencing", "epigenetics" and "microRNA". A total of 132 publications in English were identified.

RESULTS

To elucidate the genetic factors for AD pathogenesis, candidate gene association studies, genome-wide association studies (GWAS) and transcriptomic profiling assays have been performed in this period. Epigenetic mechanisms for AD development, including genomic DNA modification and microRNA posttranscriptional regulation, have been explored. To date, candidate gene association studies indicate that filaggrin (FLG) null gene mutations are the most significant known risk factor for AD, and genes in the type 2 T helper lymphocyte (Th2) signaling pathways are the second replicated genetic risk factor for AD. GWAS studies identified 34 risk loci for AD, these loci also suggest that genes in immune responses and epidermal skin barrier functions are associated with AD. Additionally, gene profiling assays demonstrated AD is associated with decreased gene expression of epidermal differentiation complex genes and elevated Th2 and Th17 genes. Hypomethylation of TSLP and FCER1G in AD were reported; and miR-155, which target the immune suppressor CTLA-4, was found to be significantly over-expressed in infiltrating T cells in AD skin lesions.

CONCLUSIONS

The results suggest that two major biologic pathways are responsible for AD etiology: skin epithelial function and innate/adaptive immune responses. The dysfunctional epidermal barrier and immune responses reciprocally affect each other, and thereby drive development of AD.

Molecular Mechanisms of Cutaneous Inflammatory Disorder: Atopic Dermatitis

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease resulting from interactions between genetic susceptibility and environmental factors. The pathogenesis of AD is poorly understood, and the treatment of recalcitrant AD is still challenging. There is accumulating evidence for new gene polymorphisms related to the epidermal barrier function and innate and adaptive immunity in patients with AD. Newly-found T cells and dendritic cell subsets, cytokines, chemokines and signaling pathways have extended our understanding of the molecular pathomechanism underlying AD. Genetic changes caused by environmental factors have been shown to contribute to the pathogenesis of AD. We herein present a review of the genetics, epigenetics, barrier dysfunction and immunological abnormalities in AD with a focus on updated molecular biology.

Unravelling the complex genetic background of atopic dermatitis: from genetic association results towards novel therapeutic strategies

Atopic dermatitis (AD) is a chronic inflammatory skin disease arising from complex interaction between genetic and environmental factors. As the starting point of the so-called "atopic march", e.g. the progression towards allergic asthma in some but not all affected children, AD has come into focus for potential disease-modifying strategies. To elucidate the genetic factors influencing AD development, linkage, association as well as genome-wide association studies have been performed over the last two decades. The results suggest that besides variation in immune-mediated pathways, an intact skin barrier function plays a key role in AD development. Mutations in the gene encoding filaggrin, a major structural protein in the epidermis, have been consistently associated with AD, especially the early-onset persistent form of disease, and are regarded as the most significant known risk factor for AD development to date. Additionally, variation in some other genes involved in skin integrity and barrier function have shown association with AD. However, the known genetic risk factors can only explain a small part of the heritability at the moment. Whole-exome or whole-genome sequencing studies have not been reported yet, but will probably soon evaluate the influence of rare variations for AD development. Additionally, large multi-centre studies comprehensively incorporating gene-gene and gene-environment interactions as well as epigenetic mechanisms might further elucidate the genetic factors underlying AD pathogenesis and, thus, open the way for a more individualized treatment in the future.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Absence of the adaptor protein Shb potentiates the T helper type 2 response in a mouse model of atopic dermatitis

Aberrant regulation of T helper (Th) cell maturation is associated with a number of autoimmune conditions, including allergic disorders and rheumatoid arthritis. The Src homology domain protein B (Shb) adaptor protein was recently implicated as a regulator of Th cell differentiation. Shb is an integral component of the T-cell receptor (TCR) signalling complex and in the absence of Shb the TCR is less responsive to stimulation, resulting in the preferential development of Th2 responses under conditions of in vitro stimulation. In the present study, we extend those observations to an in vivo situation using a murine model of atopic dermatitis. Shb knockout mice develop more pronounced symptoms of atopic dermatitis with increased localized oedema, epidermal hyperplasia and IgE production. Dermal infiltration of mast cells, eosinophils, CD4(+) Th cells and F4/80(+) macrophages was also significantly increased in Shb-deficient mice. This correlated with elevated transcription of the hallmark Th2 cytokines interleukin-4 and interleukin-5. The loss of Shb therefore alters TCR signalling ability, thereby favouring the development of Th2-driven inflammation and exacerbating symptoms of allergy.

Wheezing and itching: The requirement for STAT proteins in allergic inflammation

The development of allergic inflammation requires the orchestration of gene expression from the inflamed tissue and from the infiltrating immune cells. Since many of the cytokines that promote allergic inflammation signal through hematopoietin family receptors, the Signal Transducer and Activator of Transcription (STAT) family have obligate roles in pro-allergic cytokine-induced gene regulation in multiple cell types. In this review, we summarize work defining the contribution of each of the STAT family members to the development of allergic inflammation, using data from mouse models of allergic inflammation, studies on patient samples and correlations with single nucleotide polymorphisms in STAT genes.

Association of STAT6 variants with asthma risk: a systematic review and meta-analysis

A large number of studies have reported that the genetic variants in STAT6 gene may be implicated in susceptibility to asthma, but with inconsistent results. Therefore, the aim of this meta-analysis was to determine the likelihood of developing asthma for the individuals with different STAT6 variants. The database including Pubmed, Embase and CNKI (Chinese National Knowledge Infrastructure) were searched to find the relevant papers. Data were extracted by two independent reviewers and the odds radios (ORs) were pooled with 95% confidence intervals (CIs), using random effect or fixed effect models as appropriate, to indicate the risk of asthma for different STAT6 variants. The heterogeneity and bias were tested for each pooled result. Data from 19 studies were pooled that reported associations of rs324015, rs71802646 and rs324011 in STAT6 gene with asthma risk. The results demonstrated that 13GT and short GT in rs71802646 were both associated with increased risk of asthma in overall analysis (OR = 1.26 for 13GT and 1.30 for short GT). Further, subgroup analysis showed an increased risk of asthma in Asian population with 13GT (OR = 1.21), 14GT (OR = 1.97) and short GT (OR = 1.27). Besides, 13GT, 14GT and short GT all contributed to higher risk of atopic asthma, with OR 1.50, 2.21 and 1.65 respectively. However, rs324015 (G>A) appeared to be associated with decreased risk for atopic asthma (with OR = 0.83, 0.68 and 0.79 for A, AA and AA+AG respectively). Both overall and subgroup analyses indicated no effect of rs324011 on asthma risk. In conclusion, our meta-analyses suggest that short GT repeats of rs71802646 in STAT6 contribute to higher risk for asthma, while rs324015 may have a protective effect on atopic asthma.

The involvement of the JAK-STAT signaling pathway in chronic inflammatory skin disease atopic dermatitis

Atopic dermatitis (AD), a common chronic inflammatory skin disease, is characterized by inflammatory cell skin infiltration. The JAK-STAT pathway has been shown to play an essential role in the dysregulation of immune responses in AD, including the exaggeration of Th2 cell response, the activation of eosinophils, the maturation of B cells, and the suppression of regulatory T cells (Tregs). In addition, the JAK-STAT pathway, activated by IL-4, also plays a critical role in the pathogenesis of AD by upregulating epidermal chemokines, pro-inflammatroy cytokines, and pro-angiogenic factors as well as by downregulating antimicrobial peptides (AMPs) and factors responsible for skin barrier function. In this review, we will highlight the recent advances in our understanding of the JAK-STAT pathway in the pathogenesis of AD.

The correlation analysis of two common polymorphisms in STAT6 gene and the risk of asthma: a meta-analysis

Background

Several studies have reported that the GT dinucleotide repeat length polymorphism and the G2964A polymorphism in signal transducer and activator of transcriptional factor 6 gene are associated with asthma susceptibility, but others have conflicting results. Our meta-analysis aimed to elucidate the emerging paradigms.

Methods

We searched PUBMED, EMBASE, ISI web of knowledge, Chinese National Knowledge Infrastructure, and Wanfang databases. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to evaluate the strength of association. We applied Bonferroni step-down and Benjamini-Hochberg step-up methods to adjust the values for multiple comparisons.

Results

A total of 12 individual studies in 11 articles were included in the meta-analysis. For GT repeat polymorphism, the S allele had approximately 45% increased risk of asthma (S vs. L: OR = 1.45, 95% CI = 1.22–1.71, P_UNCORRECTED <0.001, P_Bon <0.001, P_FDR <0.001). Further analysis indicated that GT₁₃ and GT₁₄ contributed to asthma risk, whereas GT₁₅ and GT₁₆ were protective (GT₁₃ vs. GT₁₅: OR = 1.38, 95% CI = 1.16–1.65, P_{UNCORRECTED =}0.001, P_Bon =0.005, P_FDR =0.002). Similar results were obtained in the subgroup analysis of Asian population. G2964A polymorphism analysis showed that the AA genotype moderately increased the risk of asthma by 47% compared with the GG genotype (OR = 1.47, p = 0.068) in Chinese population, whereas the 2964A allele moderately increased the risk of asthma in Chinese population by 18% (2964A vs. 2964G: OR = 1.18, p = 0.08). However, none of the associations reached statistically significant levels particularly after correction for multiple testing.

Conclusions

This meta-analysis suggests that S allele (GT₁₃ and GT₁₄) of the GT repeat polymorphism confers significant risks to asthma. However, the G2964A polymorphism does not have an association with the susceptibility to asthma.

STAT6 and lung inflammation

Lung inflammation has many etiologies, including diseases of Th2-type immunity, such as asthma and anti-parasitic responses. Inflammatory diseases of the lung involve complex interactions among structural cells (airway epithelium, smooth muscle, and fibroblasts) and immune cells (B and T cells, macrophages, dendritic cells, and innate lymphoid cells). Signal transducer and activator of transcription 6 (STAT6) has been demonstrated to regulate many pathologic features of lung inflammatory responses in animal models including airway eosinophilia, epithelial mucus production, smooth muscle changes, Th2 cell differentiation, and IgE production from B cells. Cytokines IL-4 and IL-13 that are upstream of STAT6 are found elevated in human asthma and clinical trials are underway to therapeutically target the IL-4/IL-13/STAT6 pathway. Additionally, recent work suggests that STAT6 may also regulate lung anti-viral responses and contribute to pulmonary fibrosis. This review will focus on the role of STAT6 in lung diseases and mechanisms by which STAT6 controls immune and structural lung cell function.

STAT6 - polymorphisms, haplotypes and epistasis in relation to atopy and asthma

BACKGROUND

STAT6 has an important role in the IL-4 / IL-13 signalling pathway. Genome - wide association studies have shown that particular polymorphism (SNP) or haplotype variants of STAT6 as well as epigenetic gene modifications are associated with IgE level and asthma in childhood.

METHODS

A review of the available literature was performed to map out the function and signalling pathway of STAT6, studies of STAT6 SNPs association with susceptibility to asthma and atopy, covering the years 1997 - 2012 were summarized, and the value of epigenetic and epistatic influences on STAT6 and their relevance to the development of the studied phenotype (atopy or asthma) were determined.

RESULTS

There are 2 SNPs (rs71802646 and rs320411) with clinical association and proven functional effect on STAT6 expression. The effect of STAT6 SNPs cumulates in haplotypes and more potently during interaction with SNPs in the genes from the signalling pathway (IL4, IL4Ra, and IL13). Expression of STAT6 is also influenced by DNA methylation. Atopy is traditionally believed to be maternally inherited but there is one report about paternally overtransmitted STAT6 haplotype (TCA haplotype, built from rs324011, rs3024974 and rs4559 SNPs).

CONCLUSIONS

STAT6 polymorphisms and their combinations have an important influence on IgE level and development of asthma. However, the interaction between SNPs in the IL-4 / IL-13 signalling pathway is of greater impact. Hypermethylation of the STAT6 promoter is also significant in the regulation of STAT6 expression and this fact opens possibilities for targeting therapy in asthma.

Production of a human neutralizing monoclonal antibody and its crystal structure in complex with ectodomain 3 of the interleukin-13 receptor α1

Gene deletion studies in mice have revealed critical roles for IL (interleukin)-4 and -13 in asthma development, with the latter controlling lung airways resistance and mucus secretion. We have now developed human neutralizing monoclonal antibodies against human IL-13Rα1 (IL-13 receptor α1) subunit that prevent activation of the receptor complex by both IL-4 and IL-13. We describe the crystal structures of the Fab fragment of antibody 10G5H6 alone and in complex with D3 (ectodomain 3) of IL-13Rα1. Although the structure showed significant domain swapping within a D3 dimer, we showed that Arg(230), Phe(233), Tyr(250), Gln(252) and Leu(293) in each D3 monomer and Ser(32), Asn(102) and Trp(103) in 10G5H6 Fab are the key interacting residues at the interface of the 10G5H6 Fab-D3 complex. One of the most striking contacts is the insertion of the ligand-contacting residue Leu(293) of D3 into a deep pocket on the surface of 10G5H6 Fab, and this appears to be a central determinant of the high binding affinity and neutralizing activity of the antibody.

Factors that predict the clinical reactivity and tolerance in children with cow's milk allergy

BACKGROUND

Specific IgE (sIgE) may be used for the diagnosis of cow's milk allergy (CMA) and as a guide to perform food challenge tests in patients with CMA. The effect of genetic variants on the prognosis of food allergy is largely unknown.

OBJECTIVE

To examine the performance of sIgE analysis and the utility of the genetic variants of CD14, STAT6, IL13, IL10, SPINK5, and TSLP in predicting the clinical course in children with CMA.

METHODS

Serum sIgE levels of 94 children who underwent open food challenges and 54 children with anaphylaxis due to cow's milk (CM) were retrospectively analyzed between January 2002 and May 2009. The genetic polymorphisms were determined in 72 children.

RESULTS

A total of 148 children were followed up for a median of 3.5 years, and 42 of the 94 challenge results were positive. The probability curves with 95% decision points were 2.8 kU/L for younger than 1 year, 11.1 for younger than 2 years, 11.7 for younger than 4 years, and 13.7 for younger than 6 years. Sixty-six children outgrew CMA during follow-up. Children with initial an CM sIgE level less than 6 kU/L outgrew CMA earlier than children with an initial CM sIgE level of 6 kU/L or higher (P < .001). The age of tolerance development for CM was significantly higher in children with the GG genotype at rs324015 of the STAT6 gene compared with those with the AA+AG genotype (2 years [range, 1.5-3.9 years] vs 1.2 years [range, 1.0-2.2 years]) (P = .02).

CONCLUSION

The decision points of sIgE obtained in different age groups may help to determine the likelihood of clinical reactivity more precisely. The results suggest that sIgE levels and STAT6 gene variants may be important determinants to predict longer persistence of CMA.

Effects of acupuncture and moxibustion in a mouse model of allergic rhinitis

OBJECTIVE

In this study, the authors examined the effects of acupuncture and moxibustion on the expression of various inflammatory cells and mediators in the nasal mucosa of an allergic rhinitis (AR) animal model.

STUDY DESIGN

Randomized controlled animal study.

SETTING

Animal laboratory in a Dongguk University.

SUBJECTS AND METHODS

Twenty-eight BALB/c mice were divided into 4 groups: control, levocetirizine (Lcz), moxibustion (Mox), and acupuncture (Acu). To induce AR, mice were intraperitoneally sensitized to ovalbumin (OVA) and challenged with intranasal OVA. At 7 days following the final sensitization and every day for a further 7 days, the Lcz group was orally administered levocetirizine (50 mg/kg), the Mox group was subjected to 5 seconds of moxibustion stimulation at the juncture of the medial canthus and nostril, and the Acu group was subjected to 30 seconds of acupuncture stimuli at the same point. The authors measured the degree of positive reaction to substance P, STAT6, nuclear factor kappa B (NFκB), and iNOS via immunohistochemical staining of the nasal mucosa.

RESULTS

The degree of positive reaction to substance P, STAT6, NFκB, and iNOS was markedly decreased in the treatment groups compared to that in the control group. Notably, the above indices were most significantly decreased in the Acu group, followed by the Mox group and then the Lcz group (P = .000).

CONCLUSION

In an allergic rhinitis animal model, acupuncture and moxibustion are shown to exhibit an antiallergic effect and exert their effects by reducing the expression of substance P, STAT6, NFκB, and iNOS.

Modulation of specific and allergy-related immune responses by helminths

Helminths are master regulators of host immune responses utilising complex mechanisms to dampen host protective Th2-type responses and favour long-term persistence. Such evasion mechanisms ensure mutual survival of both the parasite and the host. In this paper, we present recent findings on the cells that are targeted by helminths and the molecules and mechanisms that are induced during infection. We discuss the impact of these factors on the host response as well as their effect in preventing the development of aberrant allergic inflammation. We also examine recent findings on helminth-derived molecules that can be used as tools to pinpoint the underlying mechanisms of immune regulation or to determine new anti-inflammatory therapeutics.

Genetic studies of the etiology of asthma

Asthma is a heterogeneous disease for which a strong genetic basis is firmly established. Although the generally accepted definition includes three domains of symptoms (variable airway obstruction, airway hyper-responsiveness, and airway inflammation), there is general agreement that, rather than being a single disease entity, asthma consists of related, overlapping syndromes. A considerable proportion of asthma is IgE-mediated, but the observation that not all individuals with asthma are atopic adds to the heterogeneity. Although a genetic basis for asthma is undeniable, elucidation of polymorphisms that are "causal" is greatly hampered by variability in the clinical phenotype, which is likely due to the multiple molecular mechanisms underlying the complex pathological processes involved in disease development and progression. One objective of this review is to consider progress that has been made to date in gene discovery in the field of asthma, with a focus on the evolution of molecular genetic methods that have led to the discoveries thus far, and with a particular focus on the major advances owed to the published genome-wide association studies (GWAS) on asthma to date. A second objective is to consider a Darwinian approach toward understanding the genetic underpinnings of asthma, including evidence supporting a modified Hygiene Hypothesis, which suggests that there are co-associations between asthma risk polymorphisms and polymorphisms associated with another IgE-mediated disease, schistosomiasis. The overall conclusion is that the huge research efforts and expense committed to asthma genetics have changed the perception about disease etiology in general and the functional relevance of the asthma genes identified thus far in particular.

IL-13 is a novel therapeutic target in allergic asthma

Evaluation of: Bree A, Schlerman FJ, Wadanoli M et al. IL-13 blockade reduces lung inflammation after Ascaris suum challenge in cynomolgus monkeys. J. Allergy Clin. Immunol. 119, 1251-1257 (2007). There is abundant evidence supporting IL-13 as having a central role in the pathology of allergic asthma. IL-13 induces immunological responses relevant to allergic asthma and exerts effects on airway structural cells, leading to remodeling and enhanced contractility of airway smooth muscle. This paper evaluates the results from a recent preclinical study in cynomolgus monkeys, showing that treatment with an antibody to IL-13 significantly attenuates airway inflammation induced by segmental allergen challenge. Efficacy of anti-IL-13 in proof-of-concept human studies will be critical to evaluate the potential of this therapy for treatment of allergic asthma.

Gene expression patterns and susceptibility to allergic responses

Allergic diseases are due to hypersensitive immune responses against otherwise innocuous allergens, and involve the dysregulated expression of numerous genes in cells from both the innate and adaptive immune systems. Allergic diseases are characterized by the enhanced production of type 2 T helper (Th2) cytokines, including interleukin-4, -5 and -13. These cytokines induce many of the pathophysiologic hallmarks of allergy, and their expression is tightly regulated at the level of gene transcription by both positively and negatively-acting transcription factors. In this review, the authors summarize data indicating that some of these factors represent checkpoints in the development of allergic diseases. Th2 gene expression is also controlled at the level of chromatin remodeling, and the implications of chromatin-based Th2 gene regulation in allergic disorders is also discussed. The differentiation of Th2 cells from naive precursors is critically dependent upon instruction received from dendritic cells, although the precise signals involved in this process are not well understood. Current thinking regarding some of the environmental cues interpreted by dendritic cells during allergen encounter, and how they promote Th2 responses will be reviewed. Understanding the cross-talk between dendritic cells and T cells holds great promise for deciphering the dysregulated immune response in allergy.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.

Immune and genetic aspects of asthma, allergy and parasitic worm infections: evolutionary links

There are important parallels in the immunobiology of allergy and asthma, and of the human host's response to parasitic worms. Th-2 immune actions with 'weep and sweep' mucosal biology are common to both - pathological in the first and protective in the second. Common up-regulating genetic variants of Th-2 immunity, notably in IL13 and STAT6, predict increased risk of asthma and allergy, but diminished intensity of infection by Ascaris and Schistosoma. Endemic exposures of humans to parasitic worms may have been one evolutionary force selecting for genetic variants that promote asthma and allergy.

Polymorphisms in interleukin-4-related genes in patients with minimal change nephrotic syndrome

Minimal change nephrotic syndrome (MCNS) in children is frequently associated with allergy and immunoglobulin E production. T helper subtype 2 cytokines, such as interleukin (IL)-4 and IL-13, may have an important role in the development of atopy. We investigated the association of genetic variations of IL-4 receptor alpha chain (IL-4Ralpha), IL-13 and signal transducer and activator of transcription 6 (STAT6) genes with MCNS. We analyzed these polymorphisms in 85 Japanese children (55 males, 30 females) with MCNS and 127 healthy controls with neither allergic nor renal diseases. Genomic DNA was extracted from peripheral blood leukocytes. The single nucleotide polymorphisms of IL-4Ralpha (Ile50Val) and IL-13 (R130Q) were detected by primer-specific polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism analysis, respectively. GT repeat polymorphism in STAT6 gene exon 1 was investigated by fragment length analysis. A significant difference in allelic frequencies in the STAT6 gene was detected between the MCNS and control groups. There was no significant difference between the two groups for genetic variations of IL-4Ralpha and IL-13 genes. We found a significant difference in IL-4Ralpha gene polymorphism between MCNS subgroups divided according to the number of relapses. These results suggested that the genetic variation in the first exon of the STAT6 gene may be associated with a predisposition to MCNS and that the genetic variation in the IL-4Ralpha gene may be associated with its clinical course.

STAT2*C related genotypes and allele but not TLR4 and CD40 gene polymorphisms are associated with higher susceptibility for asthma

Objective: Asthma is caused by a complex interaction between multiple genes and environmental factors. Herein we aimed to investigate whether signal transducer and activator of transcription (STAT2), toll-like receptors 4 (TLRs4) and CD40-related polymorphisms are associated with asthma susceptibility.

Design: Children were divided: (1) asthma (n=117); (2) normal controls (n=60). The polymorphisms of STAT2, TLR4 and CD40 polymorphism were analyzed by PCR-RFLP genotyping. Genotypes, allelic frequencies and association of haplotypes in both groups were compared.

Results: STAT2*C related genotypes, but not TLR4 and CD40 polymorphism, are associated with higher susceptibility for asthma. Distributions of STAT2*CC/CG/GG and C/G allele in both groups are: (1) 0/11.1/88.9 % and 5.6/94.4%; (2) 0/1.7/98.3% and 0.8/99.2% (p<0.05). Proportions of TLR4*rs10983755 AA/AG/GG and rs1927914 CC/CT/TT homozygote are: (1) 35.1/8.5/56.4% and 9.4/56.4/34.2%; (2) 35/8.3/56.7% and 16.7/48.3/35% (non-difference). Proportions of CD40*rs1883832 CC/CT/TT, rs3765459 AA/AG/GG, and rs4810485 TT/GT/GG are: (1) 29.9/53/17.1%, 6.8/47.9/45.3 and 18.8/62.4/18.8%; (2) 36.7/41.7/21.6%, 1.6/46.7/ 51.7 and 15/51.7/33.3% (non-difference). Haplotype analyses for TLR4 and CD40 genes revealed their non-association and non-additional effect upon asthma susceptibilities.

Conclusion: STAT2*C related genotypes and alleles are associated with asthma susceptibilities and pathogenesis. There were non-association and non-additional effects of TLR4/CD40 gene polymorphisms and haplotypes upon asthma risk.

The cytoplasmic C2A domain of synaptotagmin shows sequence specific interaction with its own mRNA

Synaptotagmin-1 (Syt1) is essential in Ca(2+)-dependent neurotransmitter release, but its expression regulation is unknown. Here we report that the cytoplasmic Syt1 fragment forms ribonucleoprotein complex by interacting with the 3' untranslated region (3(')UTR) of its own mRNA. Two protein-binding domains, GU(15) repeat and GUCAAUG, within the Syt 3'UTR and the C2 domains in Syt1, especially C2A, are essential in this ribonucleoprotein complex formation. Furthermore, in in vitro assay the translation efficiency of Syt1 mRNA was downregulated in presence of 3'UTR. These results demonstrate for the fist time that the soluble fraction of Syt1 can interact with its own mRNA in a highly sequence specific manner.

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.

[Asthma genetic factors]

Asthma is a chronic inflammatory airways disease, with a rising prevalence, particularly in childhood, and is considered an important public health problem. Its familial transmission is recognised, while the description and identification of the genes implicated in this disease are a challenge. In this revision paper the authors give a comprehensive explanation of the associated genes as well as the laboratorial methods that allow their identification.

Polymorphisms of interleukin (IL)-4 receptor alpha and signal transducer and activator of transcription-6 (Stat6) are associated with increased IL-4Ralpha-Stat6 signalling in lymphocytes and elevated serum IgE in patients with Graves' disease

Activated interleukin (IL)-4Ralpha stimulates production of IgE through signal transducer and activator of transcription-6 (Stat6) activation in lymphocytes. Genetic studies have shown an association between polymorphisms in the genes encoding IL-4Ralpha and Stat6 and elevated serum IgE in patients with atopic disease. Some authors, including us, have reported an association of Graves' disease and elevated serum IgE. To analyse the relationship between IL-4Ralpha and Stat6 polymorphisms and elevated serum IgE in patients with Graves' disease, 169 patients with Graves' disease were studied. We investigated whether these polymorphisms affect IL-4Ralpha-Stat6 signalling in cultured human lymphocytes. A high frequency of both the Ile50 polymorphism in IL-4Ralpha and 13GT repeat variants of the Stat6 gene was observed in patients with Graves' disease and elevated serum IgE (Ile50 allele; P < 0.05, 13GT allele; P < 0.01 versus controls) but not in subjects with normal IgE. Cultured human lymphocytes with the Ile50 IL-4Ralpha polymorphism and the 13GT repeat variant of Stat6 showed increased IL-4 (and/or IL-13)-induced Stat6 activation (2.7-fold; P < 0.05 and 2.2-fold; P < 0.05, respectively). These findings suggest that polymorphisms in the IL-4Ralpha and Stat6 genes play an important role in elevation of serum IgE through increased Stat6 action in patients with Graves' disease.

Polymorphisms of STAT-6, STAT-4 and IFN-gamma genes and the risk of asthma in Chinese population

BACKGROUND

Asthma is a complex disease resulting from multiple gene-gene and gene-environment interactions. Study on gene-gene interactions could provide insight into the pathophysiologic mechanisms of the disease.

OBJECTIVES

We investigated the single nucleotide polymorphisms and interactions among three different loci in three candidate genes (STAT-6 G2964A, STAT-4 T90089C and IFN-gamma T874A) in 95 Chinese asthmatic subjects and 95 matched controls to determine the possible associations with asthma.

METHODS

Genotyping of the gene polymorphisms was performed by means of PCR-SSCP analysis. Genotype-phenotype associations were examined in dominant and recessive genetic models using logistic regression. The method of multifactor dimensionality reduction was used to analyze gene-gene interactions.

RESULTS

No statistically significant difference was found in the distribution of the STAT-6 G2964A polymorphisms between asthmatic patients and controls in this case-control study. The STAT-4 T90089C polymorphisms were significantly associated with asthma in the dominant model (p=0.007). As for the IFN-gamma T874A, the significant associations were found in both dominant model (p=0.004) and recessive model (p=0.006). A significant gene-gene interaction was found among STAT-6, STAT-4 and IFN-gamma on the risk of asthma. In the best 3-locus model, the odds ratio for the high-risk to the low-risk group was 6.9 (95% CI, 3.5-13.7; p<0.0001).

CONCLUSIONS

Our findings suggest that STAT-4 T90089C and IFN-gamma T874A polymorphisms might be the genetic factors for the risk of asthma in the Chinese population. In addition, the significant interactions among STAT-6 G2964A, STAT-4 T90089C and IFN-gamma T874A may increase an individual's susceptibility and contribute to the pathogenesis of asthma.

Genetic haplotypes of Th-2 immune signalling link allergy to enhanced protection to parasitic worms

Parasitic worm infection, allergy and asthma involve increased IgE production, eosinophil activity, mucus secretion and smooth muscle reactivity, effected through Th-2 immune signalling. These pathological features of allergic disorder, common in developed countries, appear to be protective features in resistance to parasitic worm infections prevalent in many developing countries. We investigated how genetic variation in the Th-2 signalling transduction molecule STAT6 relates to these clinical disorders, using immune phenotyping by serum IgE levels and haplotyping nine STAT6 genetic variants in a rural Chinese population, where Ascaris infection is prevalent, and an urban UK population where Ascaris is largely unknown but asthma and allergy are prevalent. We show for the first time that STAT6 haplotypes relate clearly to IgE levels, allergy and worm burden. The haplotypes segregated into two groups: those with raised IgE/low worm burden tended to have increased risk of allergic disorder, whereas low IgE/high worm burden tended to have a reduced risk of allergies. By estimating the mean worm burden for each haplotype in China and the relative risk of asthma for the matching haplotype in the UK, we draw a cross-population comparison and show a negative correlation between worm burden and expected risk of asthma. These data imply that the origin of common up-regulating variants of Th-2 signalling, involving STAT6, promotes asthma and allergy in developed countries, whereas in developing countries it protects against parasitic worm infections. Selective evolutionary mechanisms, driven by parasitic worm infection, may underlie the genetic contribution to risk of allergy and asthma in humans.

Family studies and positional cloning of genes for asthma and related phenotypes

Although it is not yet known how many genes may contribute to the susceptibility or the severity of asthma and related phenotypes, genome-wide screens and positional cloning techniques have been successful in identifying contributing genes in multiple populations. The results of these studies provide additional insight into the molecular mechanisms responsible for the development of a variety of phenotypes. Replication with additional populations--particularly in large-scale studies--has been used to distinguish between false positive results or population-specific effects or to further quantify the conferred risk. Even when individual markers do not replicate in multiple population, association of the same region or gene has been useful in directing future studies. As further understanding of linkage disequilibrium patterns within the genome has allowed greater efficiency for genetic studies, advances in high-throughput genotyping technology, genetic analysis methodologies, and a more in-depth understanding of clinical phenotypes has made genome-wide studies more accessible and cost-effective. In the future, identification of function variants with clinical relevance may be used to influence the diagnosis and treatment of asthma.

Signal transducer and activator of transcription 6 (STAT6) and attention-deficit hyperactivity disorder: A speculative hypothesis

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by hyperactivity, impulsiveness and inattention that begins in childhood. The underlying pathogenesis of this disorder is still unknown, although pharmacological, genetic and neuroimaging studies suggest that dopamine transportation may be implicated in the pathogenesis of ADHD. Signal transducer and activator of transcription 6 (STAT6), similar to other members of the signal transducer and activator of transcription family of proteins, is an important molecule in the induction and regulation of the immune response. Animal studies have demonstrated that STAT6 is highly expressed in the CNS, especially in the developing brain. Recent studies have demonstrated that STAT6-deficient mice exhibit increased locomotor activity and decreased levels of dopamine transporter expression in the striatum, when compared with the wild-type. From these findings, and evidence from other studies, it can be proposed that STAT6 may be implicated in the pathogenesis of ADHD. Several proposals to test this hypothesis are suggested; attempts to prove the STAT6-ADHD hypothesis may provide a new direction that elucidates the pathogenesis of and a treatment for ADHD.

The human protein translin specifically binds single-stranded microsatellite repeats, d(GT)n, and G-strand telomeric repeats, d(TTAGGG)n: a study of the binding parameters

We have previously identified in human fibroblasts a multisubunit protein (designated PGB) that specifically bound single-stranded G-rich microsatellite DNA sequences. PGB was later found to be identical, or closely related to translin, an octameric protein that bound single-stranded DNA consisting of sequences flanking chromosomal translocations. Here, we report that recombinant translin binds single-stranded microsatellite repeats, d(GT)n, and G-strand telomeric repeats, d(TTAGGG)n, with higher affinities (Kdis approximately = 2 nM and Kdis approximately = 12.5 nM, respectively, in 100 mM NaCl and 25 degrees C) than the affinity with which it binds a prototypical sequence flanking translocation sites (Kdis approximately = 23 nM). Translin also binds d(GT)n and d(TTAGGG)n overhangs linked to double-stranded DNA with equilibrium constants in the nanomolar range. Formation of DNA quadruplexes by the d(TTAGGG)n repeats inhibits their binding to translin. A further study of the binding parameters revealed that the minimal length of d(GT)n and d(TTAGGG)n oligonucleotides that a translin octamer can bind is 11 nucleotides, but that such oligonucleotides containing up to 30 nucleotides can bind only a single translin octamer. However, the oligonucleotides d(GT)27 and d(TTAGGG)9 bind two octamers with negative cooperativity. Translin does not detectably bind single-stranded d(GT)n sequences embedded within double-stranded DNA. Based on our data, we propose that translin might be involved in the control of recombination at d(GT)n.d(AC)n microsatellites and in telomere maintenance.

A signal transducer and activator of transcription 6 haplotype influences the regulation of serum IgE levels

BACKGROUND

Because of its central role in the IL-4/IL-13 pathway, the intracellular signaling molecule signal transducer and activator of transcription 6 ( STAT6 ) may be crucial for IgE production in asthma and allergy.

OBJECTIVE

We analyzed the association between polymorphisms in the STAT6 gene and the regulation of serum IgE levels. Methods In a population of 1120 German schoolchildren (age 9-11 years), we genotyped 6 previously identified polymorphisms spanning the STAT6 gene by using the matrix-assisted laser desorption ionization-time of flight mass spectrometry method. 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 modeled as outcome variables in haplotype-trend regression analysis.

RESULTS

Polymorphisms located in intron 2 (C2892T) and the 3' untranslated region (T12888C) significantly and consistently contributed to elevated total serum IgE levels. One STAT6 haplotype showed increased odds ratios of 1.58 (95% CI, 1.08-2.32; P = .020), 1.82 (95% CI, 1.19-2.77; P = .006), and 3.92 (95% CI, 1.93-7.96; P = .0002) for elevated IgE levels at percentiles 50%, 66%, and 90%, respectively. Because C2892T is located within a nuclear factor kappaB transcription factor binding site, a functional role of this polymorphism is very likely.

CONCLUSION

The data indicate that within the IL-4/IL-13 pathway, genetic variants in the STAT6 gene significantly contribute to the regulation of serum IgE levels.

An asthma-associated genetic variant of STAT6 predicts low burden of ascaris worm infestation

Th-2 immune mechanisms are involved in the pathology of asthma and in the protective immune response to parasitic worms. Common upregulating genetic variants of Th-2 immune signalling are risk factors for asthma, and we tested whether they may confer a counteradvantage in protecting against parasitic worms. We examined the intensity of infection by the parasitic worm, Ascaris lumbricoides, by microsopic counting of ascaris eggs in the stool of 614 schoolchildren from an area of endemic ascaris infection in China. We investigated the relationship between the intensity of ascaris infection and common, asthma-associated genetic variants of Th-2 and Th-1 immune signalling. Ascaris egg counts per gram of stool (epg), mean 1068 epg, ranged from barely detectable (<240 epg) to heavy (approximately 9600 epg) in a skewed distribution. Logistic regression, after exploratory discriminant analysis, showed a major association between a common genetic variant of the 3'-UTR regulatory elements of the signal transducer and transactivating factor (STAT6) (P=0.0002) and egg counts, at the 77 th centile. Linear regression after log transformation of egg counts confirmed a highly significant association with this STAT6 variant (P=0.001). Thus, a common, asthma-associated, genetic variant of the pivotal transduction and transactivating factor for Th-2 immune signalling, STAT6, predicts increased resistance to ascaris worm infection. The evolution of enhanced resistance to parasitic worm infection, through human genetic variation in Th-2 immune signalling, may represent one origin for asthma.

Signal transducer and activator of transcription 6 haplotypes and asthma in the Indian population

In this paper, we report for the first time the results of an investigation on the association of signal transducer and activator of transcription 6 (STAT6) with asthma in the Indian population. A novel polymorphic CA-repeat in the proximal promoter region [R1] and a previously identified CA-repeat in the 5'-untranslated region [R3] were genotyped, and haplotypes [R1_R3] were generated using PHASE software. The 16 repeat allele at the R1 locus was positively associated (P = 0.01) with asthma. The 15 and 16 repeat alleles at the R3 locus were positively (P < 10(-4)) and negatively (P < 10(-5)) associated with asthma, respectively. Further, the 17_15 (P = 0.0031) and 16_15 (P = 0.001) haplotypes were found to be positively associated with asthma, whereas 17_14, 24_16, and 23_16 were negatively associated (P < 10(-5)). It appears that the R3 and R1 loci together play a bigger role in asthma than either of them alone, and the R3 locus has a larger effect than the R1 locus. Although alleles at the R1 locus appeared to be associated with total serum immunoglobulin E level, the genotypes showed no association, and the R3 locus showed no effect. As no exonic variants of STAT6 are known as yet, repeat polymorphisms in the regulatory regions and their haplotypes could be important in deciphering the genetic role of STAT6 in asthma and atopy.

Differential activation of signal transducer and activator of transcription 6 in B cells from allergic children and their non-allergic siblings

BACKGROUND

The germline (GL) epsilon promoter is regulated by IL-4 and is essential for class switching to IgE. IL-4-induced gene expression is largely mediated through activation of latent transcription factor STAT6 (signal transducer and activator of transcription 6).

OBJECTIVE

We investigated whether increased levels of IgE in allergic individuals may be associated with alteration in the level or activation of STAT6 and subsequent increase in GL epsilon promoter activity.

METHODS

Electrophoretic mobility shift assay and Western blotting assays were used to investigate the level of expression and activation of STAT6 in Epstein-Barr virus (EBV)-transformed B cell lines from children with birch pollen allergy and their non-allergic siblings. The activity of the GL epsilon promoter was tested in a transient transfection assay.

RESULTS

STAT6 was expressed at the same level in all B cell lines tested. In two out of five sibling pairs STAT6 was activated by IL-4 more efficiently in the allergic individuals but in the three other pairs the opposite was found. In transient transfections, no difference in IL-4-induced GL epsilon promoter function was detected, although basal promoter activity varied between allergic and healthy siblings in two out of five pairs.

CONCLUSIONS

We demonstrate for the first time that upon IL-4 signalling STAT6 transcription factor activation differs in B cells from different individuals. Although we did not find any association between STAT6 activation and allergy, we do not exclude a possibility that stronger activation of this transcription factor is associated with an expression of allergic phenotype.

Linkage and association of childhood asthma with the chromosome 12 genes

Several studies have shown linkage of chromosome region 12q13-24 to bronchial asthma and related phenotypes in ethnically diverse populations. In the Japanese population, a genome-wide study failed to show strong evidence of linkage of this region. Chromosome 12 genes that showed association with the disease in at least one report include: the signal transducer and activator of transcription 6 gene ( STAT6), the nitrogen oxide synthetase 1 gene ( NOS1), the interferon gamma gene ( IFNG), and the activation-induced cytidine deaminase gene ( AICDA). To evaluate the linkage between chromosome 12 and childhood asthma in the Japanese population, we performed sib-pair linkage analysis on childhood asthma families using 18 microsatellite markers on chromosome 12. To investigate association between chromosome 12 candidate genes and asthma, distributions of alleles and genotypes of repeat polymorphisms of STAT6, NOS1, and IFNG were compared between controls and patients. Single nucleotide polymorphism of AICDA was also investigated. Chromosome region 12q24.23-q24.33 showed suggestive linkage to asthma. The NOS1 intron 2 GT repeat and STAT6 exon 1 GT repeat were associated with asthma. Neither the IFNG intron 1 CA repeat nor 465C/T of AICDA showed any association with asthma. Our results suggest that NOS1 and STAT6 are asthma-susceptibility genes and that chromosome region 12q24.23-q24.33 contains other susceptibility gene(s).