Association of umbilical cord serum TARC/CCL17 with childhood allergies: A birth cohort study

BACKGROUND

Early identification of infants at high risk of allergies can improve the efficacy of preventive interventions. However, an established quantifiable risk assessment method in the early postnatal period does not exist. TARC (or CCL17) is a Th2 chemokine used as an activity marker for atopic dermatitis (AD). Therefore, we evaluated the association between cord blood TARC (cTARC) and the development of allergic diseases in childhood.

METHODS

This is a high-risk birth cohort for allergy, consisting of children with a family history of allergy. We collected 263 pairs of maternal and child cord blood samples perinatally and child blood samples at ages 1, 2, and 5 years. TARC and allergen-specific immunoglobulin E levels were measured, and the relationship between allergic diseases was analyzed.

RESULTS

The median cTARC was 989 pg/mL (interquartile range [IQR]: 667-1430 pg/mL). The cTARC levels in children who developed AD were higher than those in children who did not develop AD, and the association strengthened with younger age (median [IQR] at 1 year: 1285 [816-1965] vs. 933 [662-1330] pg/mL, p < 0.01; at 2 years: 1114 [787-1753] vs. 950 [660-1373] pg/mL, p = 0.02). In the multivariate analysis, cTARC was associated with AD, egg white sensitization, food allergy, allergic rhinitis, and Japanese cedar pollen sensitization.

CONCLUSIONS

cTARC was associated with the development of allergic diseases and allergen sensitization in early childhood. These results suggest that, infantile AD-mediated atopic march starts during fetal life, and this immune status is reflected in the cTARC at birth.

PDE4D gene variants and haplotypes are associated with asthma and atopy in Brazilian children

PDE4D (Phosphodiesterase 4D) gene encodes a hydrolase of cyclic AMP. PDE4D genetic variants have been associated with asthma susceptibility. Therefore, this study aimed to investigate the association between PDE4D variants (and haplotypes) with asthma and atopy in a Brazilian population. The study comprised 1,246 unrelated participants from the SCAALA (Social Changes Asthma and Allergy in Latin America) program. Genotyping was performed using the Illumina 2.5 Human Omni bead chip. Multivariate logistic regression was used to investigate the association between PDE4D variants and asthma/atopy phenotypes in PLINK 1.09 software. Twenty-four SNVs in PDE4D were associated with atopy or asthma. The rs6898082 (A) variant increased asthma susceptibility (OR 2.76; CI 99% 1.26-6.03) and was also related to a greater PDE4D expression in the GTEx database. Also, the variant rs6870632 was further associated with asthma in meta-analysis with a replication cohort. In addition, the variants rs75699812 (C), rs8007656 (G), and rs958851 (T) were positively associated with atopy. Moreover, these variants formed an atopy risk haplotype (OR 1.82; CI 99% 1.15-2.88). Also, these variants were related to lower levels of IL-10. Functional in silico assessment showed that some PDE4D SNVs may have an impact on gene regulation and expression. Variants in the PDE4D are positively associated with asthma and allergy markers. It is possible that these variants lead to alteration in PDE4D expression and therefore impact immunity and pulmonary function.

Omega-3 Fatty Acids Interact with DPP10 Region Genotype in Association with Childhood Atopy

Associations of omega-3 fatty acids (n-3) with allergic diseases are inconsistent, perhaps in part due to genetic variation. We sought to identify and validate genetic variants that modify associations of n-3 with childhood asthma or atopy in participants in the Vitamin D Antenatal Asthma Reduction Trial (VDAART) and the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC). Dietary n-3 was derived from food frequency questionnaires and plasma n-3 was measured via untargeted mass spectrometry in early childhood and children aged 6 years old. Interactions of genotype with n-3 in association with asthma or atopy at age 6 years were sought for six candidate genes/gene regions and genome-wide. Two SNPs in the region of DPP10 (rs958457 and rs1516311) interacted with plasma n-3 at age 3 years in VDAART (p = 0.007 and 0.003, respectively) and with plasma n-3 at age 18 months in COPSAC (p = 0.01 and 0.02, respectively) in associationwith atopy. Another DPP10 region SNP, rs1367180, interacted with dietary n-3 at age 6 years in VDAART (p = 0.009) and with plasma n-3 at age 6 years in COPSAC (p = 0.004) in association with atopy. No replicated interactions were identified for asthma. The effect of n-3 on reducing childhood allergic disease may differ by individual factors, including genetic variation in the DPP10 region.

Recent progress in the genetic and epigenetic underpinnings of atopy

In the past 2 years, there continue to be advances in our understanding of the genetic and epigenetic underpinnings of atopy pertaining to disease risk and disease severity. The joint role of genetics and the environment has been emphasized in multiple studies. Combining genetics with family history, biomarkers, and comorbidities is further refining our ability to predict the development of individual atopic diseases as well as the advancement of the atopic march. Polygenic risk scores will be an important next step for the field moving toward clinical translation of the genetic findings thus far. A systems biology approach, as illustrated by studies of the microbiome and epigenome, will be necessary to fully understand disease development and to develop increasingly targeted therapeutics.

Zinc finger protein 33B demonstrates sex interaction with atopy-related markers in childhood asthma

BACKGROUND

Sex differences related to immune responses can influence atopic manifestations in childhood asthma. While genome-wide association studies have investigated a sex-specific genetic architecture of the immune response, gene-by-sex interactions have not been extensively analysed for atopy-related markers including allergy skin tests, IgE and eosinophils in asthmatic children.

METHODS

We performed a genome-wide gene-by-sex interaction analysis for atopy-related markers using whole-genome sequencing data based on 889 trios from the Genetic Epidemiology of Asthma in Costa Rica Study (GACRS) and 284 trios from the Childhood Asthma Management Program (CAMP). We also tested the findings in UK Biobank participants with self-reported childhood asthma. Furthermore, downstream analyses in GACRS integrated gene expression to disentangle observed associations.

RESULTS

Single nucleotide polymorphism (SNP) rs1255383 at 10q11.21 demonstrated a genome-wide significant gene-by-sex interaction (pinteraction=9.08×10-10) for atopy (positive skin test) with opposite direction of effects between females and males. In the UK Biobank participants with a history of childhood asthma, the signal was consistently observed with the same sex-specific effect directions for high eosinophil count (pinteraction=0.0058). Gene expression of ZNF33B (zinc finger protein 33B), located at 10q11.21, was moderately associated with atopy in girls, but not in boys.

CONCLUSIONS

We report SNPs in/near a zinc finger gene as novel sex-differential loci for atopy-related markers with opposite effect directions in females and males. A potential role for ZNF33B should be studied further as an important driver of sex-divergent features of atopy in childhood asthma.

Impact of FOXP3 gene polymorphisms and gene-environment interactions in asthma and atopy in a Brazilian population

BACKGROUND

Polymorphisms in genes related to the activation and development of regulatory T cells (Tregs), such as FOXP3, may be associated with asthma and atopy development. Additionally, environmental factors such as exposure to infections can modify the effect of these associations. This study evaluated the impact of polymorphisms in the FOXP3 on the risk of asthma and atopy as also gene-environment interactions in these outcomes.

METHODS

This study included 1,246 children from the SCAALA program, between 4 and 11 years of age. DNA was extracted from peripheral blood and eight SNPs (rs2280883, rs11465476, rs11465472, rs2232368, rs3761549, rs3761548, rs2232365 and rs2294021) were genotyped using the 2.5 HumanOmni Beadchip from Illumina (San Diego, California, USA) or TaqMan qRT-PCR.

RESULTS

The rs2232368 (Allele T) was positively associated with asthma symptoms (OR=1.95, CI=1.04 to 3.66, p = 0.040) and skin prick test (SPT) reactivity to aeroallergens (OR=2.31, CI=1.16 to 4.59, p = 0.017). The rs3761549 (Allele T) was positively associated with SPT reactivity (OR=1.44, CI=1.03 to 2.02, p = 0.034). The rs2280883 (Allele C) was negatively associated with specific IgE to aeroallergens (OR=0.83, CI=0.70 to 0.99, p = 0.040). Furthermore, the rs2280883 played a protective role in the development of atopy only in individuals seropositive to Epstein-Barr virus (EBV) infection (OR=0.74, CI=0.60 to 0.92, p = 0.003 and OR=0.74; 95% CI=0.61-0.91, p = 0.007 for SPT and slgE respectively), but not in individuals without EBV infection.

CONCLUSION

Polymorphisms in the FOXP3 gene were associated with the risk of atopy and asthma development in our population. In addition, EBV infection had an effect modifier of the observed association for rs2280883 variant.

Genome-wide association study identifies BTNL2 associated with atopic asthma in children

Asthma is a heterogeneous disease characterized by chronic airway inflammation with a genetic predisposition. Butyrophilin-like 2 (BTNL2) is a member of the immunoglobulin superfamily that plays an important role in regulating T cell activation and immune homeostasis. Here, we aimed to investigate the association of the genetic variants of BTNL2 with childhood asthma and asthma-related traits by utilizing extreme asthma phenotypes and employing a genome-wide association study. Our study included 243 children with well-defined moderate to severe atopic asthma and 134 healthy children with no history of allergic diseases and allergic sensitization. DNA from these subjects was genotyped using AxiomTM Genome-Wide Array Plates. Although no single nucleotide polymorphisms (SNPs) reached a genome-wide threshold of significance, 3 SNPs, rs3817971, rs41355746, and rs41441651, at BTNL2 were significantly associated with moderate to severe atopic asthma after performing Bonferroni correction. These SNPs were also associated with the risk of allergic sensitization toward house dust mites and the presence and degree of bronchial hyperresponsiveness. Thus, we identified that BTNL2 was associated with atopic moderate to severe persistent asthma in Korean children, and this may play an important role in disease development and susceptibility.

Thymic stromal lymphopoietin, skin barrier dysfunction, and the atopic march

OBJECTIVE

Atopic dermatitis often precedes the development of other atopic diseases, and the atopic march describes this temporal relationship in the natural history of these diseases. Although the pathophysiological mechanisms that underlie this relationship are poorly understood, epidemiologic and genetic data have suggested that the skin might be an important route of sensitization to allergens.

DATA SOURCES

Review of recent studies on the role of skin barrier defects in systemic allergen sensitization.

STUDY SELECTIONS

Recent publications on the relationship between skin barrier defects and expression of epithelial cell-derived cytokines.

RESULTS

Animal models have begun to elucidate on how skin barrier defects can lead to systemic allergen sensitization. Emerging data now suggest that epithelial cell-derived cytokines, such as thymic stromal lymphopoietin, drive the progression from atopic dermatitis to asthma and food allergy. Skin barrier defects can lead to induction of epithelial cell-derived cytokines, which in turn leads to the initiation and maintenance of allergic inflammation and the atopic march.

CONCLUSION

Development of new biologic drug targeting type 2 cytokines provides novel therapeutic interventions for atopic dermatitis.

Variants in the CYSLTR2 are associated with asthma, atopy markers and helminths infections in the Brazilian population

BACKGROUND

Asthma is a chronic disease of the airways and its most common phenotype is characterized by a T2 type response with IgE production and inflammatory mediators in response to common allergens. Cysteinyl leukotrienes (CysLTs), LTC4, LTD4 and LTE4, are mediators known to possess important proinflammatory action. CysLTs can bind to the Cysteinyl leukotriene receptor type 2 (CysLTR2) and activate an inflammatory. Polymorphisms in CysLTR2 have been associated with asthma and atopy, although the mechanism is not clear.

OBJECTIVE

To evaluate the association between genetic polymorphisms in CYSLTR2 with asthma phenotypes, atopy markers and helminth infection.

METHODS

Genotyping was performed using a panel Illumina and carried out in 1245 participants of SCAALA program (Social Change, Asthma, Allergy in Latin American). Logistic regressions for asthma, helminth infections (Trichuris trichiura and Ascaris lumbricoides) and allergy markers (skin tests and IgE production) were performed using PLINK 1.9 software adjusted for sex, age, helminth infection and ancestry markers.

RESULTS

The G allele of rs1323556 was negatively associated with asthma in the additive model (OR 0.74, 95% CI 0.59-0.93) and in the dominant model (OR 0.71, 95% CI 0.53-0.74). The G allele of rs1575464 was also negatively associated with asthma in two genetic models, additive (OR 0.77, 95% CI 0.62-0.96) and dominant (OR 0.73, 95% CI 0.55-0.97). The G allele of rs61735175 was positively associated with asthma severity in the additive model (OR 1.72, 95% CI 1.07-2.77) and in the dominant model (OR 1.77, 95% CI 1.09-2.85). Five SNVs were associated with atopy markers and four SNVs were associated with helminth infections.

CONCLUSION

Polymorphisms in the CYSLTR2 gene are associated with asthma, atopy markers and helminth infection in Brazilian individuals, which may lead to protection or risk for such conditions, however, more studies are needed to evaluate the functional of this variants here in described.

Association between asthma control and Interleukin-17F expression levels in adult patients with atopic asthma

OBJECTIVES

To investigate the correlation between Interleukin 17 (IL-17F) and the level of asthma control.

METHODS

This is a cross-sectional study of 40 subjects who were diagnosed with atopic asthma. All participants were recruited from the Allergy and Immunology Clinic, Prof. R.D. Kandou General Hospital, Manado, Indonesia, between April 2015 and April 2016. Total serum IL-17F measured by using Enzyme-Linked Immunosorbent Assay methods; and mRNA IL-17F was obtained by using real-time reverse transcriptase polymerase chain reaction. Level of asthma control was quantified by using asthma control test (ACT) scoring system. The correlation between IL-17F, mRNA, and level of asthma control was analyzed by using Pearson's correlation coefficient (r).

RESULTS

There is a strong positive correlation between IL-17F serum level and Nathan's ACT-score (r=0.969) which is statistically significant (p less than 0.001). Analysis of the correlation between mRNA IL-17F serum level and Nathan's ACT-score revealed a strong positive correlation (r=0.963), which is statistically significant (p less than 0.001).

CONCLUSION

These findings suggest that IL-17F plays an important role in asthma control. However, the role played by IL-17F in asthma pathogenesis are still questions to be answered.

Shuang-Huang-Lian injection induces an immediate hypersensitivity reaction via C5a but not IgE

Among traditional Chinese medicine injections, intravenous Shuang-Huang-Lian (IV-SHL) has the highest incidence of injection-induced immediate hypersensitivity reactions (IHRs). The precise mechanisms of IV-SHL-induced IHRs remain ambiguous. In this study, we investigated the mechanisms of SHL injection (SHLI)-induced IHRs. Our data showed that serum total IgE and mouse mast cell protease 1 (MMCP1) levels were higher in the SHLI antiserum; however, these effects of SHLI disappeared in the antibiotic-treated mice. SHLI caused intraplantar vasopermeability and shock during the first local or systemic injection. SHLI-induced nonallergic IHRs were attributed to its intermediate fraction F2 (the extract of Lonicerae Japonicae Flos and Fructus forsythiae), and could be blocked by antagonists for histamine or C5a, rather than PAF or C3a. Eight constituents of F2 were able to directly activate C5 to promote local vasopermeability at the mg/mL level. In conclusion, SHLI-induced IHRs are not mediated by IgE. SHLI or its F2 can directly activate blood C5. Subsequently, C5a is likely to provoke histamine release from its effector cells (e.g., mast cells and basophils), indicating that histamine is a principal effector of IHRs induced by SHLI.

IL-4RA gene expression in PBMC with regard to place of living and atopy status

BACKGROUND

IL-4 and IL-4RA are key factors in allergic inflammation. IL-4 stimulates both IgE production and Th2 lymphocyte differentiation. Increased levels of IL-4 and IL-4RA have been shown in allergic patients. Genetic analyses have confirmed that polymorphisms within the IL-4RA gene influence the risk of allergy and can change the expression of the protein. Due to gene-environment interactions, this process is also likely to be modified by environmental exposure.

OBJECTIVES

The aim of the study was to evaluate the IL-4RA gene expression in peripheral blood mononuclear cells (PBMC) from atopic and non-atopic subjects with regard to place of living (urban vs rural).

MATERIAL AND METHODS

We enrolled 38 subjects into the study, 18 of whom were atopic. Atopy was estimated according to the results of a skin prick test. PBMC were isolated from whole blood, total RNA was extracted and reverse transcribed into cDNA. We performed real-time PCR to measure gene expression, the ACTB gene was chosen as a reference and the delta-delta Ct (ΔΔCT) method was applied for relative quantification. The Mann-Whitney U test was used for statistics.

RESULTS

We did not observe any statistically significant differences in the gene expression profile between atopic and non-atopic subjects regardless of their place of living. However, a trend was observed for atopic rural inhabitants to have lower levels of IL-4RA gene expression than atopic subjects living in the town.

CONCLUSIONS

The regulation of IL-4RA gene expression is complex and probably influenced by both genetic and environmental factors, such as farming exposures, which could provide the counterbalance to atopy.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Association of CD14 -159 (-260C/T) polymorphism and asthma risk: an updated genetic meta-analysis study

BACKGROUND

It has been reported that the cluster of differentiation 14 (CD14) gene -159C/T variant may be associated with asthma risk. However, some studies yielded conflicting results. Therefore, a comprehensive meta-analysis was designed to assess the precise association.

METHODS

A systematic search in PubMed, Embase (Ovid), China National Knowledge Internet (CNKI), and Wan fang databases was conducted up to August 15, 2015. Odds ratio (OR) and 95% confidence interval (CI) were used to pool the effect size. We used I to assess heterogeneity, and a funnel plot and Egger test to assess publication bias.

RESULTS

In total, 34 studies involving 15,641 subjects were included in this meta-analysis. There was a statistically significant association between CD14 -159C/T polymorphism and asthma risk observed in dominant model (TT+TC vs CC: OR = 0.86, 95% CI = 0.77-0.97, P = 0.012) and codominant model (TC vs CC: OR = 0.88, 95% CI = 0.78-0.99, P = 0.035) in adults. However, there may be no significant association between CD14 159C/T and atopic and nonatopic asthma risk.

CONCLUSION

In summary, the overall results suggested that the CD14 -159C/T variant may decrease the risk of asthma susceptibility in adults. However, no significant association between CD14 159C/T and atopic and nonatopic asthma susceptibility was identified. More studies with larger sample size are needed to validate the findings from this study.

Gene expression profiling of asthma phenotypes demonstrates molecular signatures of atopy and asthma control

BACKGROUND

Recent studies have used cluster analysis to identify phenotypic clusters of asthma with differences in clinical traits, as well as differences in response to therapy with anti-inflammatory medications. However, the correspondence between different phenotypic clusters and differences in the underlying molecular mechanisms of asthma pathogenesis remains unclear.

OBJECTIVE

We sought to determine whether clinical differences among children with asthma in different phenotypic clusters corresponded to differences in levels of gene expression.

METHODS

We explored differences in gene expression profiles of CD4(+) lymphocytes isolated from the peripheral blood of 299 young adult participants in the Childhood Asthma Management Program study. We obtained gene expression profiles from study subjects between 9 and 14 years of age after they participated in a randomized, controlled longitudinal study examining the effects of inhaled anti-inflammatory medications over a 48-month study period, and we evaluated the correspondence between our earlier phenotypic cluster analysis and subsequent follow-up clinical and molecular profiles.

RESULTS

We found that differences in clinical characteristics observed between subjects assigned to different phenotypic clusters persisted into young adulthood and that these clinical differences were associated with differences in gene expression patterns between subjects in different clusters. We identified a subset of genes associated with atopic status, validated the presence of an atopic signature among these genes in an independent cohort of asthmatic subjects, and identified the presence of common transcription factor binding sites corresponding to glucocorticoid receptor binding.

CONCLUSION

These findings suggest that phenotypic clusters are associated with differences in the underlying pathobiology of asthma. Further experiments are necessary to confirm these findings.

Distinguishing benign from pathologic TH2 immunity in atopic children

BACKGROUND

Although most children with asthma and rhinitis are sensitized to aeroallergens, only a minority of sensitized children are symptomatic, implying the underlying operation of efficient anti-inflammatory control mechanisms.

OBJECTIVE

We sought to identify endogenous control mechanisms that attenuate expression of IgE-associated responsiveness to aeroallergens in sensitized children.

METHODS

In 3 independent population samples we analyzed relationships between aeroallergen-specific IgE and corresponding allergen-specific IgG (sIgG) and associated immunophenotypes in atopic children and susceptibility to asthma and rhinitis, focusing on responses to house dust mite and grass.

RESULTS

Among mite-sensitized children across all populations and at different ages, house dust mite-specific IgG/IgE ratios (but not IgG4/IgE ratios) were significantly lower in children with asthma compared with ratios in those without asthma and lowest among the most severely symptomatic. This finding was mirrored by relationships between rhinitis and antibody responses to grass. Depending on age/allergen specificity, 20% to 40% of children with allergen-specific IgE (sIgE) of 0.35 kU/L or greater had negative skin test responses, and these children also expressed the high sIgG/sIgE immunophenotype. sIgG1 from these children inhibited allergen-induced IgE-dependent basophil activation in a dose-dependent fashion. Profiling of aeroallergen-specific CD4(+) TH memory responses revealed positive associations between sIgG/sIgE ratios and IL-10-dependent gene signatures and significantly higher IL-10/TH2 cytokine (protein) ratios among nonsymptomatic children.

CONCLUSION

In addition to its role in blocking TH2 effector activation in the late-phase allergic response, IL-10 is a known IgG1 switch factor. We posit that its production during allergen-induced memory responses contributes significantly to attenuation of inflammation through promoting IgG1-mediated damping of the FcεRI-dependent acute-phase reaction. sIgG1/sIgE balance might represent a readily accessible therapeutic target for asthma/rhinitis control.

DNA methylation loci associated with atopy and high serum IgE: a genome-wide application of recursive Random Forest feature selection

BACKGROUND

The prevalence of allergic diseases are increasing worldwide, emphasizing the need to elucidate their pathogeneses. The aims of this study were to use a two-stage design to identify DNA methylation levels at cytosine-phosphate-guanine (CpG) sites across the genome associated with atopy and high serum immunoglobulin E (IgE), then to replicate our findings in an independent cohort.

METHODS

Atopy was assessed via skin prick tests and high serum IgE. Methylation levels were measured from whole blood using the Illumina Infinium HumanMethylation450 BeadChip from 18-year-old women (n = 245) and men (n = 122) in the Isle of Wight birth cohort. After data cleaning and processing, and removing probes with possible single nucleotide polymorphisms, DNA methylation levels from 254,460 CpG sites from the 245 women were subjected to recursive Random Forest feature selection for stage 1. The sites selected from stage 1 were tested in stage 2 for associations with atopy and high IgE levels (>200 kU/L) via logistic regression adjusted for predicted cell-type proportions and sex. Sites significantly associated with atopy in stage 2 underwent replication tests in the independent Swedish birth cohort BAMSE (n = 464).

RESULTS

In stage 1, 62 sites were selected, of which 22 were associated with atopy in stage 2 (P-value range 6.5E-9 to 1.4E-5) and 12 associated with high IgE levels (P-value range 1.1E-5 to 7.1E-4) at the Bonferroni adjusted alpha (0.05/62 = 0.0008). Of the 19 available sites, 13 were replicated.

CONCLUSIONS

We identified 13 novel epigenetic loci associated with atopy and high IgE that could serve as candidate loci for future studies; four were within genes with known roles in the immune response (cg04983687 in the body of ZFPM1, cg18219873 in the 5'UTR of PRG2, cg27469152 in the 3'UTR of EPX, and cg09332506 in the body of COPA).

IL-10 and IL-17F Promoter Single Nucleotide Polymorphism and Asthma: A Case-Control Study in South India

BACKGROUND

Several studies have assessed the association between IL-17F and IL-10 promoter polymorphisms and asthma, but the results were conflicting. Furthermore, few studies have evaluated the association of cytokine polymorphisms with asthma and its clinical phenotypes.

OBJECTIVE

This study was conducted to evaluate the association of IL-10 (interleukin 10) and IL-17F (interleukin 17F) promoter polymorphisms (rs1800871, rs1800896 and rs1889570) with asthma and its clinical phenotypes including severity, atopic status, spirometric parameters, and response to treatment in south Indian population. A sub-study was conducted to assess cytokine levels in subjects with different gene variants.

METHODS

IL-10 and IL-17F polymorphisms were genotyped in 419 asthmatic patients and 393 controls using Mass ARRAY.

RESULTS

Our results showed an association between IL-10 SNPs and mild asthma. No association was found with any of three SNPs in moderate to severe asthma. Comparison of genotype distribution of IL-17F rs1887570 AA variant among atopic and non-atopic patients showed significant difference (p = 0.024). Correlation analysis of IL-10 and IL-17F SNPs to clinical variables showed a positive correlation between IL-17F rs1887570 AA and number of allergen sensitized (rs = 0.142, p = 0.004). Significant improvement in lung function was observed after 2 months of ICS (Inhaled corticosteroids) and LABA (long acting β2 agonist) treatment in all subjects with no statistically significant difference among SNPs variants. Cytokines levels were similar in different SNP variants.

CONCLUSION

We observed an association between IL-10 rs1800871 and rs1800896 SNPs and mild asthma, as well as IL-17F rs1887570 AA variant and number of allergens sensitized.

Association between Variants in Atopy-Related Immunologic Candidate Genes and Pancreatic Cancer Risk

Background

Many epidemiology studies report that atopic conditions such as allergies are associated with reduced pancreas cancer risk. The reason for this relationship is not yet understood. This is the first study to comprehensively evaluate the association between variants in atopy-related candidate genes and pancreatic cancer risk.

Methods

A population-based case-control study of pancreas cancer cases diagnosed during 2011-2012 (via Ontario Cancer Registry), and controls recruited using random digit dialing utilized DNA from 179 cases and 566 controls. Following an exhaustive literature review, SNPs in 180 candidate genes were pre-screened using dbGaP pancreas cancer GWAS data; 147 SNPs in 56 allergy-related immunologic genes were retained and genotyped. Logistic regression was used to estimate age-adjusted odd ratio (AOR) for each variant and false discovery rate was used to adjust Wald p-values for multiple testing. Subsequently, a risk allele score was derived based on statistically significant variants.

Results

18 SNPs in 14 candidate genes (CSF2, DENND1B, DPP10, FLG, IL13, IL13RA2, LRP1B, NOD1, NPSR1, ORMDL3, RORA, STAT4, TLR6, TRA) were significantly associated with pancreas cancer risk. After adjustment for multiple comparisons, two LRP1B SNPs remained statistically significant; for example, LRP1B rs1449477 (AA vs. CC: AOR=0.37, 95% CI: 0.22-0.62; p (adjusted)=0.04). Furthermore, the risk allele score was associated with a significant reduction in pancreas cancer risk (p=0.0007).

Conclusions

Preliminary findings suggest certain atopy-related variants may be associated with pancreas cancer risk. Further studies are needed to replicate this, and to elucidate the biology behind the growing body of epidemiologic evidence suggesting allergies may reduce pancreatic cancer risk.

Th9 cell development requires a BATF-regulated transcriptional network

T helper 9 (Th9) cells are specialized for the production of IL-9, promote allergic inflammation in mice, and are associated with allergic disease in humans. It has not been determined whether Th9 cells express a characteristic transcriptional signature. In this study, we performed microarray analysis to identify genes enriched in Th9 cells compared with other Th subsets. This analysis defined a transcriptional regulatory network required for the expression of a subset of Th9-enriched genes. The activator protein 1 (AP1) family transcription factor BATF (B cell, activating transcription factor–like) was among the genes enriched in Th9 cells and was required for the expression of IL-9 and other Th9-associated genes in both human and mouse T cells. The expression of BATF was increased in Th9 cultures derived from atopic infants compared with Th9 cultures from control infants. T cells deficient in BATF expression had a diminished capacity to promote allergic inflammation compared with wild-type controls. Moreover, mouse Th9 cells ectopically expressing BATF were more efficient at promoting allergic inflammation than control transduced cells. These data indicate that BATF is a central regulator of the Th9 phenotype and contributes to the development of allergic inflammation.

[Effects of thymic stromal lymphopoietin (TSLP) genotypes on asthma phenotypes defined by the atopy cluster -influence of smoking habits-]

INTRODUCTION

We have previously reported that a distinct sensitization pattern was associated with thymic stromal lymphopoietin (TSLP) genotype. The aim of this study is to identify the characteristics of asthma phenotypes determined by a cluster analysis of IgE responsiveness and the relationship between these phenotypes and TSLP genotypes.

PATIENTS AND METHODS

We studied 297 patients of adult asthma and 1571 non-asthmatic healthy adults from Ibaraki, a prefecture in central Japan and Kamishihoro, a cedar-free, birch-dominant town in northern Japan. Levels of total serum IgE and specific IgE antibodies towards 14 major inhaled allergens were measured. With the use of these measures, cluster analysis was applied to classify the phenotypes of adult asthma. We also examined the genetic effects of 2 TSLP functional single nucleotide polymorphism (SNPs) on the development of each asthma phenotype using multinomial logistic regression analysis.

RESULTS

The cluster analysis identified four distinct clinical phenotypes of asthma, including "Dust mite dominant" (A, N=82), "Multiple pollen" (B, N=14), "Cedar dominant" (C, N=44), and "Low reactivity" (D, N=154). Asthma phenotype A consisted of younger patients with elevated IgE levels and decreased pulmonary function. Asthma phenotype B was characterized by sensitization by many pollen allergens. Asthma phenotype C was not formed in Kamishihoro. Asthma phenotype D was a group of older women who are less atopic. In current or past smokers, both TSLP SNPs (rs2289276 and rs3860933) were associated with the asthma phenotype D (odds ratio 2.11 [1.36-3.30] and 2.11 [1.34-3.33], respectively).

CONCLUSION

In patients with adult asthma who are less atopic, the genetic polymorphisms of TSLP may have some important roles in the development of the disease in smokers.

[Association between unplanned pregnancy and adolescence onset asthma]

BACKGROUND

The association between asthma and pregnancy has been documented previously. The relationship between unplanned pregnancy and onset asthma in adolescence has not been studied.

OBJECTIVE

To determine the association between unplanned pregnancy and adolescence onset asthma.

MATERIAL AND METHODS

A cross-sectional study was done gathering information about asthma, unplanned pregnancy, family atopy and active or passive smoking in 3,130 adolescents aged 13-19 years. Asthma diagnosis was established through a selfquestionnaire based on the International Study of Asthma and Allergy in Childhood. Odds ratios for asthma were determined using logistic regression model and chi-squared test.

RESULTS

Mean age of the participants was 16.37 ± 1.93 years. The prevalence of active smoking was 16.1%, of passive smoking 40% and of family atopy 9.8%. From the pregnant adolescents (785), 59.5% reported had planned not to have a child before pregnancy. Prevalence of wheezing during the year prior to the study was 9.3% and of wheezing during the pregnancy 2%. The prevalence of adolescence onset asthma was 5.4%. The age of initiation of asthma in the adolescence was 14.75 ± 1.60 years. The analysis showed that unplanned pregnancy has a slight risk for the development of asthma during adolescence. (Crude OR=1.03; CI 95% 1.02-1.05; p=0.000).

CONCLUSION

Unplanned pregnancy, family atopy, active smoking and smoking friends are associated with the onset-asthma in the adolescence.

Impaired innate interferon induction in severe therapy resistant atopic asthmatic children

Deficient type I interferon-β and type III interferon-λ induction by rhinoviruses has previously been reported in mild/moderate atopic asthmatic adults. No studies have yet investigated if this occurs in severe therapy resistant asthma (STRA). Here, we show that compared with non-allergic healthy control children, bronchial epithelial cells cultured ex vivo from severe therapy resistant atopic asthmatic children have profoundly impaired interferon-β and interferon-λ mRNA and protein in response to rhinovirus (RV) and polyIC stimulation. Severe treatment resistant asthmatics also exhibited increased virus load, which negatively correlated with interferon mRNA levels. Furthermore, uninfected cells from severe therapy resistant asthmatic children showed lower levels of Toll-like receptor-3 mRNA and reduced retinoic acid inducible gene and melanoma differentiation-associated gene 5 mRNA after RV stimulation. These data expand on the original work, suggesting that the innate anti-viral response to RVs is impaired in asthmatic tissues and demonstrate that this is a feature of STRA.

Molecular chimerism in IgE-mediated allergy: B-and T-cell tolerance toward highly immunogenic exogenous antigens

Specific immunotherapy is the only curative treatment currently available for IgE-mediated allergy and preventive strategies are lacking altogether. We have recently reported that molecular chimerism induces durable tolerance in experimental models of allergy, thus potentially providing a new approach for the treatment and prevention of allergic diseases. Molecular chimerism is a gene-therapy approach for tolerance induction toward defined disease-causing antigens. In proof-of-concept studies, we introduced a clinically relevant grass pollen allergen into hematopoietic stem cells and transplanted those modified cells into preconditioned syngeneic mice. Long-lasting and robust tolerance toward the allergen was achieved. In our most recent studies published in Clinical and Experimental Allergy we demonstrated that milder, non-myeloablative conditioning is sufficient to induce tolerance. Our results revealed that, in contrast to other rodent models of chimerism, persistent microchimerism suffices to induce lasting tolerance at the T cell, B cell and effector cell levels in IgE-mediated allergy. This article addendum provides a summary of the recent paper and its implications.

DNA methylation profiles of airway epithelial cells and PBMCs from healthy, atopic and asthmatic children

BACKGROUND

Allergic inflammation is commonly observed in a number of conditions that are associated with atopy including asthma, eczema and rhinitis. However, the genetic, environmental or epigenetic factors involved in these conditions are likely to be different. Epigenetic modifications, such as DNA methylation, can be influenced by the environment and result in changes to gene expression.

OBJECTIVES

To characterize the DNA methylation pattern of airway epithelial cells (AECs) compared to peripheral blood mononuclear cells (PBMCs) and to discern differences in methylation within each cell type amongst healthy, atopic and asthmatic subjects.

METHODS

PBMCs and AECs from bronchial brushings were obtained from children undergoing elective surgery for non-respiratory conditions. The children were categorized as atopic, atopic asthmatic, non-atopic asthmatic or healthy controls. Extracted DNA was bisulfite treated and 1505 CpG loci across 807 genes were analyzed using the Illumina GoldenGate Methylation Cancer Panel I. Gene expression for a subset of genes was performed using RT-PCR.

RESULTS

We demonstrate a signature set of CpG sites that are differentially methylated in AECs as compared to PBMCs regardless of disease phenotype. Of these, 13 CpG sites were specific to healthy controls, 8 sites were only found in atopics, and 6 CpGs were unique to asthmatics. We found no differences in the methylation status of PBMCs between disease phenotypes. In AECs derived from asthmatics compared to atopics, 8 differentially methylated sites were identified including CpGs in STAT5A and CRIP1. We demonstrate STAT5A gene expression is decreased whereas CRIP1 gene expression is elevated in the AECs from asthmatic compared to both healthy and atopic subjects.

DISCUSSION

We characterized a cell specific DNA methylation signature for AECs compared to PBMCs regardless of asthmatic or atopic status. Our data highlight the importance of understanding DNA methylation in the epithelium when studying the epithelial contribution to asthma.

Genome-wide prediction of childhood asthma and related phenotypes in a longitudinal birth cohort

BACKGROUND

Childhood wheezing and asthma vary greatly in clinical presentation and time course. The extent to which phenotypic variation reflects heterogeneity in disease pathways is unclear.

OBJECTIVE

We sought to assess the extent to which single nucleotide polymorphisms (SNPs) associated with childhood asthma in a genome-wide association study are predictive of asthma-related phenotypes.

METHODS

In 8365 children from a population-based birth cohort, the Avon Longitudinal Study of Parents and Children, allelic scores were derived based on between 10 and 215,443 SNPs ranked according to the inverse of the P value for their association with physician-diagnosed asthma in an independent genome-wide association study (6176 cases and 7111 control subjects). We assessed the predictive value of allelic scores for asthma-related outcomes at age 7 to 9 years (physician's diagnosis, longitudinal wheezing phenotypes, and measurements of pulmonary function, bronchial responsiveness, and atopy).

RESULTS

Scores based on the 46 highest-ranked SNPs were associated with the symptom-based phenotypes early onset persistent wheeze (P< 10(-11); area under the receiver operating characteristic curve [AUC], 0.59) and intermediate-onset wheeze (P< 10(-3); AUC, 0.58). Among lower-ranked SNPs (ranks, 21,545-46,416), there was evidence for associations with diagnosed asthma (P< 10(-4); AUC, 0.54) and atopy (P< 10(-5); AUC, 0.55). We found little evidence of associations with transient early wheezing, reduced pulmonary function, or nonasthma phenotypes.

CONCLUSION

The genetic origins of asthma are diverse, and some pathways are specific to wheezing syndromes, whereas others are shared with atopy and bronchial hyperresponsiveness. Our study also provides evidence of etiologic differences among wheezing syndromes.

AGR2 is induced in asthma and promotes allergen-induced mucin overproduction

Mucins are gel-forming proteins that are responsible for the characteristic viscoelastic properties of mucus. Mucin overproduction is a hallmark of asthma, but the cellular requirements for airway mucin production are poorly understood. The endoplasmic reticulum (ER) protein anterior gradient homolog 2 (AGR2) is required for production of the intestinal mucin MUC2, but its role in the production of the airway mucins MUC5AC and MUC5B is not established. Microarray data were analyzed to examine the relationship between AGR2 and MUC5AC expression in asthma. Immunofluorescence was used to localize AGR2 in airway cells. Coimmunoprecipitation was used to identify AGR2-immature MUC5AC complexes. Agr2(-/-) mice were used to determine the role of AGR2 in allergic airway disease. AGR2 localized to the ER of MUC5AC- and MUC5B-producing airway cells and formed a complex with immature MUC5AC. AGR2 expression increased together with MUC5AC expression in airway epithelium from "Th2-high" asthmatics. Allergen-challenged Agr2(-/-) mice had greater than 50% reductions in MUC5AC and MUC5B proteins compared with allergen-challenged wild-type mice. Impaired mucin production in Agr2(-/-) mice was accompanied by an increase in the proportion of mucins contained within the ER and by evidence of ER stress in airway epithelium. This study shows that AGR2 increases with mucin overproduction in individuals with asthma and in mouse models of allergic airway disease. AGR2 interacts with immature mucin in the ER and loss of AGR2 impairs allergen-induced MUC5AC and MUC5B overproduction.

Protein-protein interaction network analysis of children atopic asthma

BACKGROUND

Asthma prevalence has increased very considerably in recent decades such that it is now one of the commonest chronic disorders in the world. In this present study, We constructed a protein-protein interaction (PPI) network by mapped the differentially expressed genes (DEGs) to the PPI data and performed Gene Ontology (GO) enrichment analysis of the PPI network. We aimed to explore the pathogenesis of atopic asthma by bioinformatics methods.

MATERIALS AND METHODS

To explore the pathogenesis of atopic asthma by bioinformatics methods, we obtained the global gene expression profile of pediatric asthmatic epithelium GSE18965 from Gene Expression Omnibus (GEO), and identified the differentially expressed genes between healthy nonatopic samples and atopic asthmatic samples

RESULTS

Total 12 DEGs were selected. Furthermore, we constructed a protein-protein interaction network by mapped the DEGs to the PPI data and performed Gene Ontology enrichment analysis of the PPI network. Total 15 GO terms were enriched and the enriched terms can be generally classified into two groups: cell cycle and immunity.

CONCLUSIONS

Our results confirmed the role of cell proliferation and immune system in the pathogenesis of atopic asthma. Besides, our PPI network is useful in investigating the complex interacting mechanisms of transcription factors and their regulated genes in atopic asthma.

[Genesis of food allergy in infancy]

Food allergy originates from physiological fetal Th2 polarization. The normal shift towards Th1 dominance during the first months of life is defective in the atopic infant. Several factors are critical for the development of food allergy. The influence of genetic factors has been shown by familial aggregation studies, and numerous candidate genes have been identified Gene polymorphisms interact with the environment, contributing to fetal programming Heritable epigenetic modifications occur rapidly in response to environmental factors and may explain the recent increase in food allergies and other atopic diseases. Atmospheric agents and the maternal diet during pregnancy may either increase or decrease the risk. Birth conditions, the intestinal microbiota, age at which food diversification begins, and exposure to food allergens and pollutants by inhalation, ingestion and skin contact may all contribute to the onset of food allergy in infancy. Partial prophylaxis is now within reach. Preventive information must be provided to families at high risk of atopy in their offspring.

Genetic variant rs4982958 at 14q11.2 is associated with allergic rhinitis in a Chinese Han population running title: 14q11.2 is a susceptibility locus for allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is one of the most common diseases caused by the combined effects of intrinsic factors (susceptibility genes and immunological status) and the external environment. Analyses of ascendant family history of atopic disease suggest that AR and atopic dermatitis might share a similar genetic background.

OBJECTIVE

To conduct a case-control study in a Chinese Han population to evaluate the potential influence of single nucleotide polymorphisms (SNPs) at FLG, 5q22.1, 11q13.5, 14q11.2 and 20q13.33 on AR.

METHODS

Ten SNPs--rs11204971 and rs3126085 at FLG, rs10067777, rs7701890, rs13360927, and rs13361382 at 5q22.1, rs6010620 at 20q13.33, rs7936562 and rs7124842 at 11q13.5, and rs4982958 at 14q11.2 were genotyped in 363 cases and 668 controls using the Sequenom MassArray system. Data were analyzed with PLINK 1.07 software.

RESULTS

The T allele of rs4982958 at 14q11.2 was observed to be significantly associated with AR (P = .002, OR = 0.73, P(Bonferront) = .02). Genotype-based association testing revealed that the recessive model might provide the best fit for rs4982958 (P(Bonferroni) = .01). In subphenotype analyses, the rs4982958 T allele was also significantly associated with persistent AR (P = .01) and more than 2 positive skin prick tests (P = .038).

CONCLUSION

We identified a novel susceptibility locus 14q11.2 for AR that might bear candidate genes conferring susceptibility to AR and affecting disease phenotypes.

Association between tuberculosis and atopy: role of the CD14-159C/T polymorphism

BACKGROUND

The development of allergic hypersensitivity depends on both genetic and environmental factors. Different amounts of microbial products could affect patients with atopy and different genotypes.

OBJECTIVE

We aimed to evaluate the role of varying degrees of exposure to infection by Mycobacterium tuberculosis (tuberculosis) in atopic patients and analyze the association with genetic factors.

METHODS

We performed CD14-159C/T genotyping in atopic patients (n=118) and healthy individuals (n=62) and recorded the following variables: rural lifestyle, exposure to persons with tuberculosis, bacille Calmette-Guerin (BCG) vaccination, tuberculin skin test (TST), skin prick test, and phenotypes of atopy. Blood samples were analyzed for soluble-CD14 (sCD14), interferon (IFN) y, total immunoglobulin (Ig) E, and eosinophil levels. A score was used to identify the likelihood of exposure to tuberculosis.

RESULTS

Almost all the study participants had had a BCG vaccination, and half had a positive TST result. No differences were observed between atopic patients with high/low tuberculosis scores and CD14 genotypes in terms of atopic phenotypes, allergen sensitization, and levels of total IgE, sCD14, and IFN-y. However, the frequency of asthma was higher in atopic patients with a high tuberculosis score and was not associated with CD14 genotypes. Eosinophil counts in blood were higher in atopic patients with a high tuberculosis score and CC+CT genotypes.

CONCLUSIONS

These results suggest that the C allele of the CD14-159C/T polymorphism has a marked effect on eosinophil levels in atopic patients with increased exposure to tuberculosis. In addition, the degree of exposure to tuberculosis in atopic patients may modify the development of asthma.

Interaction between filaggrin null mutations and tobacco smoking in relation to asthma

BACKGROUND

The mechanisms underlying the association between filaggrin (FLG) deficiency and asthma are not known. It has been hypothesized that FLG deficiency leads to enhanced percutaneous exposure to environmental substances that might trigger immune responses. We hypothesized that interactions between FLG deficiency and environmental exposures play a role in asthma development.

OBJECTIVE

We sought to investigate possible interactions between FLG null mutations and tobacco smoking in relation to asthma.

METHODS

A total of 3471 adults from a general population sample participated in a health examination. Lung function and serum specific IgE levels to inhalant allergens were measured, and information on asthma and smoking was obtained by means of questionnaire. Participants were genotyped for the 2 most common FLG null mutations in white subjects: R501X and 2282del4. Another Danish population was used for replication.

RESULTS

The FLG null mutation genotype was significantly associated with a higher prevalence of asthma and decreased FEV(1)/forced vital capacity ratio. In logistic regression analyses with asthma as the outcome, a significant interaction was found between FLG null mutations and smoking status (P = .02). This interaction was confirmed, although it was not statistically significant, in another Danish population study. Interactions between FLG genotype and cumulated smoking exposure were found in relation to asthma (P = .03) and decreased FEV(1)/forced vital capacity ratio (P = .03). A 3-way interaction was found among FLG genotype, smoking, and asthma, suggesting that the FLG-smoking interaction mainly played a role in nonatopic subjects.

CONCLUSION

FLG null mutations modified the effects of smoking on the risk of asthma. This finding might have implications for risk stratification of the population.

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.

Genetic association analyses of atopic illness and proinflammatory cytokine genes with type 1 diabetes

BACKGROUND

The genetic basis of the autoimmune disease type 1 diabetes (T1D) has now been largely determined, so now we can compare these findings with emerging genetic knowledge of disorders and phenotypes that have been negatively or positively associated with T1D historically. Here, we assessed the role in T1D of variants previously reported to be associated with atopic diseases and epithelial barrier function, profilaggrin (FLG), and those that affect the expression levels of the proinflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-1β, interferon (IFN)γ and IL-18.

METHODS

We genotyped single nucleotide polymorphisms (SNPs): -105/rs28665122 in SELS or SEPS1 (selenoprotein), three single nucleotide polymorphisms in IL18 (-105/rs360717, +183/rs5744292 and +1467/rs574456) and R501X/rs61816761 in FLG, the major locus associated with atopic dermatitis and predisposing to asthma, in a minimum of 6743 T1D cases and 7864 controls.

RESULTS

No evidence of T1D association was found for any of the SNPs we genotyped at FLG, SELS or IL18 (p≥0.03), nor with haplotypes of IL18 (p=0.82). Review of previous T1D genome-wide association results revealed that four (human leucocyte antigen (HLA), gasdermin B/ORM1 (Saccharomyces cerevisiae)-like/gasdermin B/, GSDMB/ORMDL3/GSDMA and IL2RB) of ten loci recently reported to be associated with asthma were associated with T1D (p≤0.005).

CONCLUSIONS

These results show that there are shared genetic associations for atopy-related traits and T1D, and this might help in the future to understand the mechanisms, pathways and environmental factors that underpin the rapid rise in incidence of both disorders in children.

Identification of IL6R and chromosome 11q13.5 as risk loci for asthma

BACKGROUND

We aimed to identify novel genetic variants affecting asthma risk, since these might provide novel insights into molecular mechanisms underlying the disease.

METHODS

We did a genome-wide association study (GWAS) in 2669 physician-diagnosed asthmatics and 4528 controls from Australia. Seven loci were prioritised for replication after combining our results with those from the GABRIEL consortium (n=26,475), and these were tested in an additional 25,358 independent samples from four in-silico cohorts. Quantitative multi-marker scores of genetic load were constructed on the basis of results from the GABRIEL study and tested for association with asthma in our Australian GWAS dataset.

FINDINGS

Two loci were confirmed to associate with asthma risk in the replication cohorts and reached genome-wide significance in the combined analysis of all available studies (n=57,800): rs4129267 (OR 1·09, combined p=2·4×10(-8)) in the interleukin-6 receptor (IL6R) gene and rs7130588 (OR 1·09, p=1·8×10(-8)) on chromosome 11q13.5 near the leucine-rich repeat containing 32 gene (LRRC32, also known as GARP). The 11q13.5 locus was significantly associated with atopic status among asthmatics (OR 1·33, p=7×10(-4)), suggesting that it is a risk factor for allergic but not non-allergic asthma. Multi-marker association results are consistent with a highly polygenic contribution to asthma risk, including loci with weak effects that might be shared with other immune-related diseases, such as NDFIP1, HLA-B, LPP, and BACH2.

INTERPRETATION

The IL6R association further supports the hypothesis that cytokine signalling dysregulation affects asthma risk, and raises the possibility that an IL6R antagonist (tocilizumab) may be effective to treat the disease, perhaps in a genotype-dependent manner. Results for the 11q13.5 locus suggest that it directly increases the risk of allergic sensitisation which, in turn, increases the risk of subsequent development of asthma. Larger or more functionally focused studies are needed to characterise the many loci with modest effects that remain to be identified for asthma.

FUNDING

National Health and Medical Research Council of Australia. A full list of funding sources is provided in the webappendix.

Rhinitis phenotypes correlate with different symptom presentation and risk factor patterns of asthma

BACKGROUND

Asthma and rhinitis frequently coexist, but no population study has previously determined the relationship between nasal comorbidities and symptom expression and risk factors of asthma.

METHODS

In 2008, a postal questionnaire on respiratory health was sent to 30,000 randomly selected subjects aged 16-75 years in West Sweden; 29218 could be traced and 18,087 (62%) responded. The questionnaire included questions on asthma, rhinitis, chronic rhinosinusitis, respiratory symptoms and possible determinants.

RESULTS

Prevalence of allergic rhinitis in asthma was 63.9% and of asthma in allergic rhinitis 19.8%. Prevalence of chronic rhinosinusitis in asthma was 8.4% and of asthma in chronic rhinosinusitis 24.4%. Asthma subjects with chronic rhinitis, or chronic rhinosinusitis, had more symptoms of asthma and bronchitis than those without rhinitis (p < 0.001). There was an obvious trend of higher ORs for various environmental exposures including occupational exposure to dust, gases and fumes (OR 2.32 vs. OR 1.44), visible mould at home (OR 1.72 vs. OR 1.27) and water damage at home (OR 1.82 vs. OR 1.06) for asthma with chronic rhinosinusitis than for asthma with allergic rhinitis. Family history of allergy yielded a higher OR for asthma with allergic rhinitis than with asthma with chronic rhinosinusitis (OR 7.15 vs. OR 4.48).

CONCLUSION

Considerable overlap between asthma and nasal comorbidities was documented, confirming a close relationship between nasal disease and asthma. Allergic rhinitis, chronic rhinitis and chronic rhinosinusitis were associated with different risk factor patterns and symptom expression of asthma. Thus, different nasal comorbidities may reflect different phenotypes of asthma.

Loss-of-function mutations within the filaggrin gene and atopic dermatitis

Atopic dermatitis (AD) is a chronic relapsing eczematous skin disorder that is frequently associated with elevated serum IgE levels and a personal or family history of AD, allergic rhinitis and/or asthma. Filaggrin is a major constituent of the stratum corneum (SC) and contributes to keratin filament aggregation. Its breakdown products form natural moisturizing factor, which plays a central role in hydration of the SC. Sequence analysis and epidemiological studies indicate that loss-of-function mutations in the filaggrin gene known to cause the autosomal dominant scaly skin disorder ichthyosis vulgaris are major genetic predisposing factors of AD. Mutations in filaggrin are also associated with atopic asthma. These findings established the 'filaggrin hypothesis,' which states that AD can be triggered by the chronic exposure of barrier-disrupted skin to percutaneous antigens due to abnormalities in filaggrin. In this chapter, we summarize the genome-wide screening of AD susceptibility loci, filaggrin biochemistry and recent epidemiological studies on filaggrin mutations and allergic diseases. We also summarize recent advances in the study of skin barrier mechanisms and filaggrin-associated skin barrier abnormalities in animal models. Taken together, these findings provide novel perspectives on the pathophysiology of AD and effective therapeutic methods for the treatment and/or prevention of AD through the modification of skin barrier dysfunction.

Tests and estimates (transmission disequilibrium test) for allelic association of CCR5delta32 with asthma in high-risk families

OBJECTIVE

To examine the possible associations between CCR5delta32 and asthma and related phenotypes in high-risk families.

METHODS

A total of 154 families (453 individuals), with at least two affected children with physician-diagnosed asthma (PDA) and atopy defined as one or more skin prick test to common inhaled allergen (SPT wheal > or = 3 mm), were studied. Samples were genotyped using PCR assay and tested for possible associations by TDT and PDT and case control analyses.

RESULTS

Overall allelic frequency for CCR5delta32 was 26.1%, and both TDT and PDT demonstrated similar nonsignificant associations (p=0.123) and (p=0.088). Analysis by the clinical categories of non atopic and atopic asthma and presence or absence of atopy without asthma failed to identify any significant associations. However there were strong associations of the mutant allele with the phenotypes of negative SPT, PC 20 less than 8 mg/ml, baseline FEV1 greater than the population median (83.5% predicted) and serum IgE less than 100 IU/l for child probands but only for negative SPT in unrelated parents.

CONCLUSION

Non-significant association was seen with family based association tests (FBATs). The strong associations with the asthma related phenotypes in child probands support previous observations that CCR5 is in linkage disequilibrium with CCR2 or CCR3.

The absence of VPAC2 leads to aberrant antibody production in Aspergillus fumigatus sensitized and challenged mice

Vasoactive intestinal peptide (VIP) facilitates a "pro-allergy" phenotype when signaling through its G protein-coupled receptor, VPAC(2). We have shown that VPAC(2) knock-out (KO) mice developed an allergic phenotype marked by eosinophilia and elevated serum IgE. Therefore, we hypothesized that the humoral response to allergen challenge in these mice was T(H)2 dominant similar to wild-type (WT) C57BL/6 mice. Antibody responses in WT and KO mice were measured after Aspergillus fumigatus conidia inhalation. In contrast to previous reports, basal levels of serum IgG(2a) and IgA were significantly higher in naïve VPAC(2) KO animals. Antibody availability in the serum as well as the bronchoalveolar lavage fluid after fungal challenge was dominated by the pro-inflammatory isotype IgG(2a) and the mucosal isotype, IgA. IgA localizing cells dominated in the peribronchovascular areas of allergic KO mice while IgE immune complexes were found in WT allergic lungs. This research shows for the first time that VPAC(2) has a significant effect on antibody regulation, in the context of allergy.

Atopy, asthma, and lung function in relation to folate and vitamin B(12) in adults

BACKGROUND

Recent studies suggested low serum folate and impaired folate metabolism as potential risk factors for development of asthma and atopic disease, but the results are inconsistent. The aim of this study was to investigate the relations of markers of folate and vitamin B₁₂ (B₁₂) deficiency with different phenotypes of asthma and atopy.

METHODS

A random sample of 6784 persons from a general population aged 30-60 years participated in a health examination in 1999-2001, and 4516 (66.6%) of those also participated in a follow-up examination 5 years later. The examinations included spirometry, measurements of serum folate and B₁₂, specific IgE to inhalant allergens, total IgE, and genotyping of the MTHFR-C677T polymorphism - a genetic marker of impaired folate metabolism. Information about dietary intake of folate and B₁₂, asthma diagnosis, and airway symptoms was obtained by questionnaires.

RESULTS

Low serum folate levels and the TT genotype of the MTHFR-C677T polymorphism were associated with increased prevalence of self-reported doctor-diagnosed asthma [odds ratio (OR) 1.37, 95% confidence interval (CI) 1.05-1.79 and OR 1.52; 95% CI 1.12-2.06, respectively] and attacks of shortness of breath (OR 1.43, 95% CI 1.14-1.79 and OR 1.47; 95% CI: 1.14-1.91, respectively). We found no significant associations with lung function or atopic outcomes. Serum levels of B₁₂ and dietary intake of folate and B₁₂ were not associated with asthma or atopy.

CONCLUSIONS

We found that two objective markers of folate deficiency were associated with self-reported doctor-diagnosed asthma and attacks of shortness of breath, but not with lung function or atopy.

X-chromosome Forkhead Box P3 polymorphisms associate with atopy in girls in three Dutch birth cohorts

BACKGROUND

The Forkhead Box P3 (FOXP3) gene, located on the X-chromosome, encodes a transcription factor that directs T cells toward a regulatory phenotype. Regulatory T cells may suppress development of atopy. We evaluated whether single-nucleotide polymorphisms (SNPs) of FOXP3 are associated with atopy development in childhood.

METHODS

Seven SNPs in FOXP3 were genotyped in 3062 children (51% boys) participating in the Allergenic study, which consists of three Dutch birth cohorts (PIAMA, PREVASC and KOALA). Association of FOXP3 SNPs with total serum IgE and sensitisation (presence of specific serum IgE to egg, milk, and indoor, i.e. house-dust mite, cat, and/or dog allergens) was investigated at ages 1, 2, 4, and 8. Analysis of variance and logistic regression were performed, stratified for gender.

RESULTS

Our most consistent finding was observed for sensitisation to egg and indoor allergens. In girls, five FOXP3 SNPs (rs5906761, rs2294021, rs2294019, rs6609857 and rs3761548) were significantly associated with sensitisation to egg at ages 1 and 2 and with sensitisation to indoor allergens at age 2 (P < 0.05), but not at 4 and 8, a finding that was observed across the three cohorts. Rs5906761 and rs2294021 were associated with remission of sensitisation to food allergens in boys, as tested in the PIAMA cohort.

CONCLUSION

This is the first study showing across three cohorts that X-chromosomal FOXP3 genotypes may contribute to development of sensitisation against egg and indoor allergens in girls in early childhood. In addition, an association with remission of sensitisation to food allergens existed in boys only.