Polymorphisms in eosinophil pathway genes, asthma and atopy

SingleNucleotide Polymorphisms as Biomarkers of Mepolizumab and Benralizumab Treatment Response in Severe Eosinophilic Asthma

The most promising treatment options for severe uncontrolled asthma (SUA) have emerged in recent years with the development of monoclonal antibodies for blocking selective targets responsible for the underlying inflammation, such as mepolizumab and benralizumab. However, there is variability in treatment response that is not fully controlled. The variability of the response to mepolizumab and benralizumab could be influenced by single-nucleotide polymorphisms (SNPs), and it would be useful to detect these and use them as predictive biomarkers of response. We conducted a retrospective observational cohort study of 72 Caucasian patients recruited from a tertiary hospital with severe uncontrolled eosinophilic asthma treated with mepolizumab and benralizumab. Polymorphisms in the IL5 (rs4143832, rs17690122), RAD50 (rs11739623, rs4705959), IL1RL1 (rs1420101, rs17026974, rs1921622), GATA2 (rs4857855), IKZF2 (rs12619285), FCGR2A (rs1801274), FCGR2B (rs3219018, rs1050501), FCGR3A (rs10127939, rs396991), FCER1A (rs2251746, rs2427837), FCER1B (rs1441586, rs573790, rs569108), and ZNF415 (rs1054485) genes were analyzed by real-time polymerase chain reaction (PCR) using Taqman probes. The response was analyzed after 12 months of treatment. In patients under mepolizumab treatment, a treatment response defined as a reduction in exacerbations was associated with ZNF415 rs1054485-T (p = 0.042; OR = 5.33; 95% CI = 1.06-30.02), treatment response defined as a reduction in oral corticosteroids use was associated with the number of exacerbations in the previous year (p = 0.029; OR = 3.89; 95% CI = 1.24-14.92), and treatment response defined as improvement in lung function was associated with the age at the beginning of biological therapy (p = 0.002; OR = 1.10; 95% CI = 1.04-1.18), FCER1B rs569108-AA (p < 0.001; OR = 171.06; 95% CI = 12.94-6264.11), and FCER1A rs2427837-A (p = 0.021; OR = 8.61; 95% CI = 1.71-76.62). On the other hand, in patients under benralizumab treatment, treatment response, defined as a reduction in exacerbations, was associated with ZNF415 rs1054485-T (p = 0.073; OR = 1.3 × 108; 95% CI = 1.8 × 10-19-NA), FCER1B rs569108-AA (p = 0.050; OR = 11.51; 95% CI = 1.19-269.78), allergies (p = 0.045; OR = 4.02; 95% CI = 1.05-16.74), and sex (p = 0.028; OR = 4.78; 95% CI = 1.22-20.63); and treatment response defined as improvement in lung function was associated with polyposis (p = 0.027; OR = 9.16; 95% CI = 1.58-91.4), IKZF2 rs12619285-AA (p = 0.019; OR = 9.1; 95% CI = 1.7-75.78), IL5 rs4143832-T (p = 0.017; OR = 11.1; 95% CI = 1.9-112.17), and FCER1B rs1441586-C (p = 0.045; OR = 7.81; 95% CI = 1.16-73.45). The results of this study show the potential influence of the studied polymorphisms on the response to mepolizumab and benralizumab and the clinical benefit that could be obtained by defining predictive biomarkers of treatment response.

Transcriptome Analysis Reveals Altered Expression of Genes Involved in Hypoxia, Inflammation and Immune Regulation in Pdcd10-Depleted Mouse Endothelial Cells

Cerebral cavernous malformations (CCM) are capillary malformations affecting the central nervous system and commonly present with headaches, epilepsy and stroke. Treatment of CCM is symptomatic, and its prevention is limited. CCM are often sporadic but sometimes may be multifocal and/or affect multiple family members. Heterozygous pathogenic variants in PDCD10 cause the rarest and apparently most severe genetic variant of familial CCM. We carried out an RNA-Seq and a Q-PCR validation analysis in Pdcd10-silenced and wild-type mouse endothelial cells in order to better elucidate CCM molecular pathogenesis. Ninety-four differentially expressed genes presented an FDR-corrected p-value < 0.05. A functionally clustered dendrogram showed that differentially expressed genes cluster in cell proliferation, oxidative stress, vascular processes and immune response gene-ontology functions. Among differentially expressed genes, the major cluster fell in signaling related to inflammation and pathogen recognition, including HIF1α and Nos2 signaling and immune regulation. Validation analysis performed on wild-type, Pdcd10-null and Pdcd10-null reconstituted cell lines was consistent with RNA-Seq data. This work confirmed previous mouse transcriptomic data in endothelial cells, which are recognized as a critical tissue for CCM formation and expands the potential molecular signatures of PDCD10-related familial CCM to alterations in inflammation and pathogen recognition pathways.

Genetics and Epigenetics in Allergic Rhinitis

The pathogenesis of allergic rhinitis is associated with genetic, environmental, and epigenetic factors. Genotyping of single nucleotide polymorphisms (SNPs) is an advanced technique in the field of molecular genetics that is closely correlated with genome-wide association studies (GWASs) in large population groups with allergic diseases. Many recent studies have paid attention to the role of epigenetics, including alteration of DNA methylation, histone acetylation, and miRNA levels in the pathogenesis of allergic rhinitis. In this review article, genetics and epigenetics of allergic rhinitis, including information regarding functions and significance of previously known and newly-discovered genes, are summarized. Directions for future genetic and epigenetic studies of allergic rhinitis are also proposed.

Variants in the IL17 pathway genes are associated with atopic asthma and atopy makers in a South American population

BACKGROUND

Asthma is a complex disorder with multiple phenotypes which can influence its severity and response to treatment. The TH17 lymphocytes producing IL-17A and IL17-F cytokines, may have a role on asthma inflammation. The aim of our study was to evaluate the association between genetic variants in IL17 pathway genes with asthma and atopy markers.

MATERIALS AND METHODS

Genotyping was performed using a commercial panel in 1245 participants of SCAALA cohort. The study included 91 SNVs in IL-17 pathway genes. Logistic regressions for asthma and atopy markers were performed using PLINK 1.9. In silico analyses were performed using rSNPbase, RegulomeDB, and Gtex portal for in silico gene expression.

RESULTS AND DISCUSSION

The T allele of rs1974226 in IL17A was positively associated with asthma (OR: 1.37; 95% CI 1.02-1.82). Also, the T allele of rs279548 was positively associated with asthma (OR: 1.30; 95% CI 1.02-1.64), atopy (OR: 1.62; 95% CI 1.05-2.50) and increased expression of the IL17RC in lung and whole blood tissues. The others genetic variants in the IL17 pathways genes were associated with both protection and risk for asthma development as well as with IgE levels.

CONCLUSION

The genetic variants in IL-17-related genes are associated with the atopic asthma phenotype and IgE production.

Genomic mosaicism: A neglected factor that promotes variability in asthma diagnosis

To elucidate the genetic architecture of asthma continues to be a challenge for molecular biologists and medical researchers. However, powerful genomic technologies are at disposal to help decipher complete human genomes; the genetic variability in asthma hinders the discovery of common molecular markers for this disease. In this context, we purpose to explore genomic mosaicism on asthma cells' biology as a strategy to discover key mechanisms, which can complement or re-define asthma diagnosis. Recent evidences showed that genomic mosaicism could be a normal event. In brains, each neuron may harbor hundreds of genetic alterations, which may contribute to neuronal diversity. Thus, can mosaicism be a natural motor of diversity in asthma? Why this genetic event is little described in scientific literature? To discuss these questions, we perform a critical review about the normality of genomic mosaicism; moreover, we examine the difficulty of current experimental approaches to detect different genotypes in cell populations of one individual.

The IL-4 rs2070874 polymorphism may be associated with the severity of recurrent viral-induced wheeze

BACKGROUND

Childhood recurrent wheezing and consequently asthma corresponds to various phenotypes. Our aim was to link genetic variants of asthma candidate genes to the phenotypes of early onset wheezing.

STUDY DESIGN

We included very young consecutive children presenting with recurrent wheezing who had been evaluated for the severity of wheezing, associated atopic comorbidities, and tested for biomarkers of atopy and inflammation. All were genotyped for 16 single nucleotide polymorphisms (SNPs) linked with asthma or atopy. An unsupervised hierarchical bottom-up method was used for clustering the phenotypes and a multinomial logistic regression was performed for each individual SNP.

RESULTS

We replicated the three phenotypes previously described Trousseau Asthma Program in 317 children aged 21.5 ± 7.9 months: cluster 1 (nonatopic uncontrolled severe wheeze), n = 207, a severe viral-induced wheeze, cluster 2 (atopic multiple trigger wheeze), n = 61, with multiple allergic comorbidities, and cluster 3 (episodic viral wheeze), n = 49, a mild viral-induced wheeze. The TT-genotype of the IL-4 rs2070874 polymorphism was significantly associated with the nonatopic uncontrolled severe wheeze compared to the episodic viral wheeze (OR 7.9; CI95% [2.5-25.3]; P = 0.001).

CONCLUSION

Association between the TT-genotype of IL-4 rs2070874 polymorphism and a severe phenotype of viral-induced wheeze further underlines the role IL-4 plays in the inflammation pathway leading to viral respiratory infections.

Polymorphisms in DENND1B gene are associated with asthma and atopy phenotypes in Brazilian children

Asthma is a heterogeneous disease associated with a complex basis involving environmental factors and individual variabilities. The DENN Domain Containing 1B (DENND1B) gene has an important role on T cell receptor (TCR) down-regulation on Th2 cells and studies have shown that mutations or loss of this factor can be associated with increased Th2 responses and asthma. The aim of this work is to evaluate the association of polymorphisms in the DENND1B with asthma and allergy markers phenotypes in Brazilian children. Genotyping was performed using a commercial panel from Illumina (2.5 Human Omni bead chip) in 1309 participants of SCAALA (Social Change, Asthma, Allergy in Latin American) program. Logistic regressions for asthma and atopy markers were performed using PLINK software 1.9. The analyzes were adjusted for sex, age, helminth infections and ancestry markers. The DENND1B gene was associated with different phenotypes such as severe asthma and atopic markers (specific IgE production, skin prick test and IL-13 production). Among the 166 SNPs analyzed, 72 were associated with asthma and/or allergy markers. In conclusion, polymorphisms in the DENND1B are significantly associated with development of asthma and atopy and these polymorphisms can influence DENND1B expression and consequently, asthma.

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.

IL5RA polymorphisms, smoking and eczema in Japanese women: the Kyushu Okinawa Maternal and Child Health Study

The present case-control study examined the relationship between IL5RA SNPs and eczema in young adult Japanese women. Cases and control subjects were selected from pregnant women who participated in the baseline survey of the Kyushu Okinawa Maternal and Child Health Study, which is an ongoing prebirth cohort study. Cases comprised 188 women with eczema in the previous 12 months as defined according to the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC), regardless of the presence of a doctor's diagnosis of atopic eczema. Control subjects comprised 1130 women without eczema as defined according to the ISAAC criteria who also had not been diagnosed with atopic eczema by a doctor. Compared with the AA genotype of IL5RA SNP rs17881144, the AT genotype, but not the TT genotype, was significantly associated with a decreased risk of eczema. The ATTAGA haplotype and the GTAGCA haplotype of rs17882210, rs3804797, rs334809, rs9831572, rs6771148 and rs17881144 were significantly associated with an increased risk of eczema. In contrast, the GCTGCA haplotype was significantly related to a decreased risk of eczema. Multiplicative interactions between IL5RA SNPs rs334809 and rs17881144 and smoking with respect to eczema were marginally significant (P = 0.07 and 0.07, respectively). This is the first study to show significant associations between IL5RA SNP rs17881144, the ATTAGA haplotype, the GTAGCA haplotype, and the GCTGCA haplotype and eczema. Smoking may modify the relationships between SNPs rs334809 and rs17881144 and eczema.

A GM-CSF/IL-33 pathway facilitates allergic airway responses to sub-threshold house dust mite exposure

Allergic asthma is a chronic immune-inflammatory disease of the airways. Despite aeroallergen exposure being universal, allergic asthma affects only a fraction of individuals. This is likely related, at least in part, to the extent of allergen exposure. Regarding house dust mite (HDM), we previously identified the threshold required to elicit allergic responses in BALB/c mice. Here, we investigated the impact of an initial immune perturbation on the response to sub-threshold HDM exposure. We show that transient GM-CSF expression in the lung facilitated robust eosinophilic inflammation, long-lasting antigen-specific Th2 responses, mucus production and airway hyperresponsiveness. This was associated with increased IL-33 levels and activated CD11b⁺ DCs expressing OX40L. GM-CSF-driven allergic responses were significantly blunted in IL-33-deficient mice. IL-33 was localized on alveolar type II cells and in vitro stimulation of human epithelial cells with GM-CSF enhanced intracellular IL-33 independently of IL-1α. Likewise, GM-CSF administration in vivo resulted in increased levels of IL-33 but not IL-1α. These findings suggest that exposures to environmental agents associated with GM-CSF production, including airway infections and pollutants, may decrease the threshold of allergen responsiveness and, hence, increase the susceptibility to develop allergic asthma through a GM-CSF/IL-33/OX40L pathway.

Case-control study of rhinoconjunctivitis associated with IL5RA polymorphisms in Japanese women: the Kyushu Okinawa Maternal and Child Health Study

BACKGROUND

Epidemiological research on the relationship between single nucleotide polymorphisms (SNPs) in the IL5RA gene and allergic disorders is limited. We examined the relationship between IL5RA SNPs and risk of rhinoconjunctivitis in young adult Japanese women.

METHODS

Included were 393 women who met the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC) for rhinoconjunctivitis. Controls were 767 women without rhinoconjunctivitis according to the ISAAC criteria who had not been diagnosed with allergic rhinitis by a doctor. Adjustment was made for age, region of residence, presence of older siblings, smoking, and education.

RESULTS

Compared with the CC genotype of SNP rs6771148, the CG genotype, but not the GG genotype, was significantly associated with a reduced risk of rhinoconjunctivitis: the adjusted OR for the CG genotype was 0.76 (95% CI: 0.58-0.99). No evident associations were found between SNPs rs17882210, rs3804797, rs334809, rs9831572, or rs17881144 and rhinoconjunctivitis. The ACTAGA haplotype of rs17882210, rs3804797, rs334809, rs9831572, rs6771148, and rs17881144 was significantly inversely associated with rhinoconjunctivitis (crude OR=0.58, 95% CI: 0.37-0.88) while the GTAGCA haplotype was significantly positively related to rhinoconjunctivitis (crude OR=1.74, 95% CI: 1.14-2.65). No significant interactions affecting rhinoconjunctivitis were observed between any of the six SNPs and smoking.

CONCLUSION

This is the first study to show significant associations between IL5RA SNP rs6771148, the ACTAGA haplotype, and the GTAGCA haplotype and the risk of rhinoconjunctivitis. We did not find evidence for interactions affecting rhinoconjunctivitis between any of the IL5RA SNPs and smoking.

IL3 SNP rs40401 variant is a risk factor for rhinoconjunctivitis in Japanese women: the Kyushu Okinawa maternal and child health study

BACKGROUND

No studies have investigated the relationship between IL3 single nucleotide polymorphism (SNP) rs40401 and allergic rhinitis. We performed a case-control study to examine this issue and to assess interactions between the SNP and smoking or older siblings in young adult Japanese women.

METHODS

Included were 393 women who met the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC) for rhinoconjunctivitis. Controls were 767 women without rhinoconjunctivitis according to the ISAAC criteria who had not been diagnosed with allergic rhinitis by a doctor.

RESULTS

Compared with women with the TT genotype of SNP rs40401, those with the CC genotype had a significantly increased risk of rhinoconjunctivitis: the adjusted OR was 1.52 (95% CI: 1.05-2.19). This positive relationship was significant under the additive model: the adjusted OR was 1.23 (95% CI: 1.02-1.47). The positive association fell just short of the significance level under the dominant or recessive model. There was no significant interaction between SNP rs40401 and smoking with respect to rhinoconjunctivitis. Compared with subjects with the TT or TC genotype of IL3 SNP rs40401 who had one or more older siblings, those with the CC genotype who had no older siblings had a 2.33-fold increased risk of rhinoconjunctivitis; nevertheless, the interaction was not significant.

CONCLUSION

This is the first study to show a significant positive association between IL3 SNP rs40401 variant and the risk of rhinoconjunctivitis. We could not find evidence for interactions between SNP rs40401 and smoking or older siblings affecting rhinoconjunctivitis.

IL-5 Promoter Polymorphism Enhances IgE Responses to Staphylococcal Superantigens in Adult Asthmatics

Interleukin 5 (IL-5) is a key cytokine involved in the induction of T-helper type 2 (Th2) responses in the asthmatic airway. We investigated IL-5 genetic polymorphisms associated with asthma phenotypes, including IgE responses to staphylococcal enterotoxins A and B (SEA and SEB, respectively), in asthmatics. Adult asthmatics (n=310) and normal controls (n=160) were enrolled in the present study. Serum total and specific IgE to SEA and SEB were measured. Two IL-5 polymorphisms, -746A>G and +4499T>G, were genotyped using the primer-extension method. There were no significant differences in genotype or haplotype frequencies of these polymorphisms between the two groups. Asthmatics carrying the AG/GG genotype at -746A>G had a significantly higher prevalence of serum specific IgE to SEA (P=0.008), higher total IgE levels (P=0.014), and lower PC20 methacholine levels (P=0.002) compared to those with the AA genotype. These findings suggest that the IL-5 promoter polymorphism at -746A>G enhances serum total and specific IgE responses to SEA, which may augment airway hyperresponsiveness in adult asthmatics.

Elevated eosinophil protein X in urine from healthy neonates precedes development of atopy in the first 6 years of life

RATIONALE

Biomarkers predicting development of atopic disease are needed for targeted preventive measures and to study if disease pathology may be active before onset of symptoms.

OBJECTIVES

To investigate whether eosinophil protein X, leukotriene-C4/D4/E4, and 11β-prostaglandin (PG) F2α (PGD2 metabolite) assessed in urine from healthy at-risk neonates precede development of atopic disease during the first 6 years of life.

METHODS

We measured eosinophil protein X (n = 369), leukotriene-C4/D4/E4 (n = 367), and 11β-PGF2α (n = 366) in urine from 1-month-old children participating in the Copenhagen Prospective Studies on Asthma in Childhood birth cohort. Clinical data on development of allergic sensitization, allergic rhinitis, nasal eosinophilia, blood eosinophilia, eczema, troublesome lung symptoms (significant cough or wheeze or dyspnea), and asthma were collected prospectively until age 6 years. Associations between urinary biomarkers and development of atopic traits were investigated using general estimating equations, logistic regression, and Cox regression.

MEASUREMENTS AND MAIN RESULTS

Eosinophil protein X in the urine of the asymptomatic 1-month-old neonates was significantly associated with development of allergic sensitization (odds ratio, 1.49; 95% confidence interval [CI], 1.08–1.89), nasal eosinophilia (odds ratio, 3.2; 95% CI, 1.2–8.8), and eczema (hazard ratio, 1.4; 95% CI, 1.0–2.0), but not with allergic rhinitis, asthma, or blood eosinophilia. Neither leukotriene-C4/D4/E4 nor 11β-PGF2α was associated with any of the atopic phenotypes.

CONCLUSIONS

Eosinophil protein X in urine from asymptomatic neonates is a biomarker significantly associated with later development of allergic sensitization, nasal eosinophilia, and eczema during the first 6 years of life. These findings suggest activation of eosinophil granulocytes early in life before development of atopy-related symptoms.

CD14 gene polymorphism is not associated with asthma but rather with bronchial obstruction and hyperreactivity in Slovenian children with non-atopic asthma

BACKGROUND

Though the associations of CD14 with asthma have already been studied, the results of different independent studies are in conflict, mostly due to differences in the pathogenesis of varying asthma sub-phenotypes. The aim of our study was to perform an association analysis of promoter single nucleotide polymorphism (SNP) -159C/T (rs2569190) in the CD14 gene for Slovenian children with asthma.

METHODS

We analyzed SNP -159C/T in a group of all asthmatics, and separately in a group of atopic and non-atopic asthmatics. We also analyzed the influence of SNP -159C/T on clinical parameters and the response to therapy with inhaled corticosteroids. We have genotyped 247 children with asthma and a median age of 11 years (interquartile range, 5 years), and 158 healthy controls with a median age of 13 years (interquartile range, 5 years). We performed genotyping using a polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis.

RESULTS

We found that SNP -159C/T in CD14 is not associated with asthma in Slovenian children. However, non-atopic asthmatics with CT or TT genotypes have a lower FEV1/FVC ratio as a measure of bronchial obstruction (87.4%, compared to 91.8% in patients with the CC genotype, p = 0.017). Non-atopic asthmatics with CC or CT genotypes also have increased bronchial hyperreactivity measured by PC20 of methacholine (0.41 mg/ml, compared to 1.50 mg/ml in patients with a TT genotype, p = 0.018).

CONCLUSIONS

Our results suggest that CD14 is associated with asthma severity in Slovenian children with non-atopic asthma.

Association of functional polymorphisms in promoter regions of IL5, IL6 and IL13 genes with development and prognosis of autoimmune thyroid diseases

To clarify the association of genetic producibility of interleukin (IL)-5, IL-6 and IL-13, which are secreted by T helper type 2 (Th2), with the development and prognosis of autoimmune thyroid disease (AITD), we genotyped IL5-746C/T, IL6-572C/G and IL13-1112C/T polymorphisms, which are functional polymorphisms in the promoter regions of the genes regulating these cytokines. Fifty-seven patients with intractable Graves' disease (GD), 52 with GD in remission, 52 with severe Hashimoto's disease (HD), 56 with mild HD and 91 healthy controls were examined in this study. The IL13-1112T allele, which correlates with higher producibility of IL-13, was more frequent in patients with GD in remission than in those with intractable GD [P=0·009, odds ratio (OR)=3·52]. The IL5-746T allele, which may correlate with lower levels of IL-5, was more frequent in patients with GD in remission than controls (P=0·029, OR=2·00). The IL6-572G allele carriers (CG and GG genotypes), which have higher producibility of IL-6, were more frequent in AITD patients (P=0·033, OR=1·75), especially in GD in remission (P=0·031, OR=2·16) and severe HD (P=0·031, OR=2·16) than in controls. Interestingly, both allele and genotype frequencies of Th2 cytokine genes were similar between GD and HD patients. In conclusion, functional polymorphisms in the genes encoding Th2 cytokines are associated differently with the development and prognosis of AITD from each other.

Association analysis of polymorphisms in IL-3, IL-4, IL-5, IL-9, and IL-13 with Graves' disease

BACKGROUND

Graves' disease (GD) is a common autoimmune disorder with genetic predisposition. There is strong evidence that the Chr.5q31-33 region, which contains the immune response cytokine genes [interleukin (IL)-3, IL-4, IL-5, IL-9, and IL-13], is linked to autoimmune thyroid disorders in Chinese and Japanese populations. The aim of the present study is to elucidate whether the single nucleotide polymorphisms (SNP) and the interaction of variants in the 5 genes are associated with the development of GD and Graves' ophthalmopathy (GO).

MATERIALS AND METHODS

GD patients (no.=751), with 190 of GO patients and healthy control subjects (no.=748) were included in this study. Six SNP [rs40401 (IL-3), rs2070874 (IL-4), rs2069812 (IL-5), rs1859430 (IL-9), rs2069868 (IL-9), and rs20541 (IL-13)] were genotyped by SNPstream Genotyping System.

RESULTS

There was a significant increase of C allele of rs40401 in GD [odds ratio (OR)=1.18 [95% confidence interval (CI): 1.02-1.36], pallele=0.028] and GO [OR=1.30 (95%CI: 1.04-1.63), pallele=0.022] patients compared with those in the controls. The C allele of the rs2069812 was also significantly associated with GD [OR=1.22 (95%CI: 1.04-1.44), pallele=0.015] and GO [OR=1.45 (95%CI: 1.13-1.86), pallele=0.003] patients. Haplotype analysis showed a predominant increase of the 2 SNP (rs40401-rs2069812, CC) and all the 6 SNP (CCCCCC) haplotype in GD (OR=1.70, OR=3.70, respectively) and even stronger in GO (OR=2.18, OR=7.01, respectively) patients.

CONCLUSIONS

The results suggested that the polymorphism of IL-3 (rs40401) and IL-5 (rs2069812) were associated with GD and GO susceptibility in Chinese population. The interaction of 6-locus from the 5 genes might confer higher risk for GD and GO than single risk allele.

N-acetyltransferase 2 (NAT2) polymorphism in patients with atopic asthma

BACKGROUND AND AIMS

Allergic asthma is a chronic inflammatory disorder of the airways where, on exposure to allergens, the body mounts an immune response. The etiology of asthma is complex and multifactorial. Rapid and slow acetylators reflect the genetically determined variation in the elimination of xenobiotics. Recent advances have demonstrated the importance of genetic and environmental factors in the development of atopic asthma. Hepatic arylamine N-acetyltransferase 2 (NAT2) takes part in the detoxification of some drugs and arylamine xenobiotics. The aim of the present study was to determine the NAT2 polymorphism in patients with atopic asthma.

METHODS

In the study, 184 unrelated asthmatic patients and 181 healthy controls were included. The mutations at positions 481T, 803G, 590A and 857A of the NAT2 gene were determined by a polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP).

RESULTS

The frequency of homozygous fast acetylators did not differ significantly between patients and controls. Compared with the control population, the significant prevalence of slow acetylators in the group of patients with atopic asthma was observed. There was a statistically significant prevalence of subjects with NAT2*5/NAT2*5 and NAT2*5/NAT2*6 genotypes. The risk of an atopic asthma development was 3.4 times greater in slow than in fast acetylators (OR = 3.3657; p <0.000001, 95% CI = 2.1282-5.3228).

CONCLUSIONS

These results suggest that NAT2 polymorphism may be involved in the pathogenesis of atopic asthma.

Asthma symptoms and airway narrowing in children growing up in an urban versus rural environment

The development of asthma and allergy appears to be the result of gene-environment interaction. Potential environmental risk factors such as outdoor and indoor air pollution, infections, allergen exposure, diet, and lifestyle patterns may trigger respiratory symptoms and compromise lung function in children. Specific features of urban and rural lifestyle may constitute distinct risk factors but may also coexist within certain socioeconomic levels. Children of rural environments are at lower risk for asthma and aeroallergen sensitization. The protective effect has been associated with close contact with large animals, but the genetic factor also plays a contributory role. Children with prolonged exposure to urban environment are at increased risk of reduced lung function and those that reside in polluted areas exhibit slower lung growth. It is possible that polluted urban environment per se facilitates subclinical small airway disease. Evidence to date supports a strong relation between residential area as a potential risk factor for childhood asthma symptoms and airway obstruction and a western type of socioeconomic development.

Study of gene-gene interactions for endophenotypic quantitative traits in Chinese asthmatic children

BACKGROUND

Asthma is a complex disease resulting from interactions between multiple genes and environmental factors. Study of gene-gene interactions could provide insight into the pathophysiology of asthma.

METHODS

We investigated the interactions among 18 single-nucleotide polymorphisms in eight candidate genes for plasma total immunoglobulin E (IgE) concentration and peripheral blood (PB) eosinophil count in 298 Chinese asthmatic children and 175 controls. Generalized multifactor dimensionality reduction and generalized linear model were used to analyze gene-gene interactions for the quantitative traits.

RESULTS

A significant interaction was found between R130Q in IL13 and I50V in IL4RA for plasma total IgE concentration, with a cross-validation (CV) consistency of nine of 10 and a prediction error of 41.1% (P = 0.013). Plasma total IgE concentration was significantly higher in the high-risk than the low-risk groups (P < 0.0001). For PB eosinophil count, significant interaction was found between C-431T in TARC and RsaI_in2 in FCERIB, with a CV consistency of nine of 10 and a prediction error of 40.2% (P = 0.009). PB eosinophil count was significantly higher in the high-risk group than the low-risk groups (P < 0.0001). Generalized linear model also revealed significant gene-gene interaction for the above two endophenotypes with P = 0.013 for plasma total IgE concentration and P = 0.029 for PB eosinophil count respectively.

CONCLUSIONS

Our data suggest significant interactions between IL13 and IL4RA for plasma total IgE concentration, and this is the first report to show significant interaction between TARC and FCERIB for PB eosinophil count in Chinese asthmatic children.

Discovering susceptibility genes for asthma and allergy

Asthma and asthma-related traits are complex diseases with strong genetic and environmental components. Rapid progress in asthma genetics has led to the identification of several candidate genes that are associated with asthma-related traits. Typically the phenotypic impact of each of these genes, including the ones most often replicated in association studies, is mild, but larger effects may occur when multiple variants synergize within a permissive environmental context. Despite the achievements made in asthma genetics formidable challenges remain. The development of novel, powerful tools for gene discovery, and a closer integration of genetics and biology, should help to overcome these challenges.

Analysis of the 5q31 33 locus shows an association between single nucleotide polymorphism variants in the IL-5 gene and symptomatic infection with the human blood fluke, Schistosoma japonicum

Genetic studies of human susceptibility to Schistosoma (blood fluke) infections have previously identified a genetic locus determining infection intensity with the African species, Schistosoma mansoni, in the 5q31-33 region of the human genome that is known to contain the Th2 immune response cluster, including the genes encoding the IL-4, IL-5, and IL-13 cytokines. These cytokines are key players in inflammatory immune responses and have previously been implicated in human susceptibility to infection with the Asian species, S. japonicum. In a nested case control study, we genotyped 30 HapMap tagging single nucleotide polymorphisms (SNPs) across these three genes in 159 individuals identified as putatively susceptible to reinfection with S. japonicum and in 133 putatively resistant individuals. A third group comprising 113 individuals demonstrating symptomatic infection was also included. The results provided no significant association at a global level between reinfection predisposition and any of the individual SNPs or haplotype blocks. However, two tagging SNPs in IL-5 demonstrated globally significant association with susceptibility to symptomatic infection. They were in strong linkage disequilibrium with each other and were found to belong to the same haplotype block that also provided a significant association after permutation testing. This haplotype was located in the 3'-untranslated region of IL-5, suggesting that variants in this region of IL-5 may modulate the immune response in these individuals with symptomatic infection.