Diagnostic value of clinical parameters in the prediction of aspirin-exacerbated respiratory disease in asthma

Aspirin Challenge-Induced Genome-Wide DNA Methylation Profile of Peripheral Blood Lymphocytes in Aspirin-Exacerbated Respiratory Disease

Genetic variation and epigenetic factors are thought to contribute to the development of hypersensitivity to aspirin. DNA methylation fluctuates dynamically throughout the day. To discover new CpG methylation in lymphocytes associated with aspirin-exacerbated respiratory disease (AERD), we evaluated changes in global CpG methylation profiles from before to after an oral aspirin challenge in patients with AERD and aspirin-tolerant asthma (ATA). Whole-genome CpG methylation levels of peripheral blood mononuclear cells were quantified with an Illumina 860K Infinium Methylation EPIC BeadChip array and then adjusted for inferred lymphocyte fraction (ILF) with GLINT and Tensor Composition Analysis. Among the 866,091 CpGs in the array, differentially methylated CpGs (DMCs) were found in 6 CpGs in samples from all 12 patients with asthma included in the study (AERD, n = 6; ATA, n = 6). DMCs were found in 3 CpGs in the 6 ATA samples and in 615 CpGs in the 6 AERD samples. A total of 663 DMCs in 415 genes and 214 intergenic regions differed significantly in the AERD compared with the ATA. In promoters, 126 CpG loci were predicted to bind to 38 transcription factors (TFs), many of which were factors already known to be involved in the pathogenesis of asthma and immune responses. In conclusion, we identified 615 new CpGs methylated in peripheral blood lymphocytes by oral aspirin challenge in AERD but not in ATA. These findings indicate that oral aspirin challenge induces epigenetic changes in ILFs, specifically in AERD patients, possibly via changes in TF binding, which may have epigenetic effects on the development of AERD.

Association of ATP8B3 gene polymorphisms with aspirin-exacerbated respiratory disease in asthmatics

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD), an asthma phenotype, often presents with severe manifestations and it remains widely underdiagnosed because of insufficient awareness of the relationship between the ingestion of nonsteroidal anti-inflammatory drugs, including acetylsalicylic acid (ASA), and asthma exacerbation. Our previous genome-wide association study demonstrated an association between a single nucleotide polymorphism (SNP) of the ATP8B3 gene and the risk of AERD. This study examined AERD-related SNPs of the ATP8B3 gene in a large population.

METHODS

Twenty-five SNPs of ATP8B3 were genotyped with the GoldenGate assay using VeraCode microbeads in 141 asthmatics with AERD and 995 Aspirin-tolerant asthma (ATA). The genotype distribution was analyzed using logistic regression models. The declines in forced expiratory volume in 1 second (FEV1)following an ASA challenge were compared among the genotypes and haplotypes using a type III generalized linear model.

RESULTS

The minor allele frequencies (MAFs) of rs10421558 A>G in the 5'UTR and rs10403288 G>A in the intron were significantly lower in the AERD than the ATA [34.0% vs. 43.8%, OR = 0.66 (0.62-0.92), Pcorr = 0.03 and 28.4% vs. 35.4%, OR = 0.62 (0.59-0.89), Pcorr = 0.016, respectively]. BL1ht5 was significantly higher in the AERD [7.6% vs. 1.6%, OR = 12.23 (0.2-0.51), P = 4.7 × 10 -4 , Pcorr = 0.001]. Among them, rs10421558 A>G and BL1ht5 were associated with the percent decline in FEV1 on the oral ASA challenge test.

CONCLUSION

The minor allele of rs10421558 A>G in the 5'UTR may protect against the development of AERD via the increased production of ATP8B3.

Genome-wide DNA methylation profile of peripheral blood lymphocytes from subjects with nonsteroidal anti-inflammatory drug-induced respiratory diseases

BACKGROUND

Significant changes in CpG methylation have been identified in nasal polyps, which are the main targets of nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (NERD); however, these polyps are composed of various cellular components. In the present study, whole-genome CpG methylation in peripheral blood lymphocytes (PBLs) was analyzed to define the epigenetic changes in lymphocytes, which are the primary immune cells involved in NERD.

MATERIALS AND METHODS

Genomic DNA from peripheral blood mononuclear cells from 27 NERD and 24 aspirin-tolerant asthma (ATA) was subjected to bisulfate conversion and a methylation array. Quantitative CpG methylation, the β-values as a quantitative measure of DNA methylation, in lymphocytes were calculated after adjustments for cellular composition.

RESULTS

Fifty-six hypermethylated and three hypomethylated differentially methylated CpGs (DMCs) in PBLs in the NERD compared with ATA. The top 10 CpG loci predicted the methylation risk score, with a positive predictive value of 91.3%, a negative predictive value of 81.5% and an accuracy of 84.3%. As demonstrated in the nasal polyps, 30 DMCs were predicted to bind to the following 10 transcription factors, ranked in descending order: AP-2alphaA, TFII-1, STAT4, FOXP3, GR, c-Est-1, E2F-1, XBP1, ENKTF-1 and NF-1. Gene ontology analysis identified 13 categories such as regulation of T-helper 17 cell differentiation, including SMAD7 and NFKBIZ. PBLs in NERD contained no DMCs in genes associated with the prostaglandin and leukotriene pathways, which were found in ATA.

CONCLUSION

PBLs in NERD form a unique pattern of DNA CpG methylation, and the combined analysis may provide predictive values for NERD.

Effect of TGF-β1 on eosinophils to induce cysteinyl leukotriene E4 production in aspirin-exacerbated respiratory disease

Cysteinyl leukotriene (cysLT) overproduction and eosinophil activation are hallmarks of aspirin-exacerbated respiratory disease (AERD). However, pathogenic mechanisms of AERD remain to be clarified. Here, we aimed to find the significance of transforming growth factor beta 1 (TGF-β1) in association with cysteinyl leukotriene E4 (LTE4) production, leading to eosinophil degranulation. To evaluate levels of serum TGF-β1, first cohort enrolled AERD (n = 336), ATA (n = 442) patients and healthy control subjects (HCs, n = 253). In addition, second cohort recruited AERD (n = 34) and ATA (n = 25) patients to investigate a relation between levels of serum TGF-β1 and urinary LTE4. The function of TGF-β1 in LTE4 production was further demonstrated by ex vivo (human peripheral eosinophils) or in vivo (BALB/c mice) experiment. As a result, the levels of serum TGF-β1 were significantly higher in AERD patients than in ATA patients or HCs (P = .001; respectively). Moreover, levels of serum TGF-β1 and urinary LTE4 had a positive correlation (r = 0.273, P = .037). In the presence of TGF-β1, leukotriene C4 synthase (LTC4S) expression was enhanced in peripheral eosinophils to produce LTE4, which sequentially induced eosinophil degranulation via the p38 pathway. When mice were treated with TGF-β1, significantly induced eosinophilia with increased LTE4 production in the lung tissues were noted. These findings suggest that higher levels of TGF-β1 in AERD patients may contribute to LTE4 production via enhancing LTC4S expression which induces eosinophil degranulation, accelerating airway inflammation.

Can nasal acetylsalicylic acid challenge predict the severity of non-steroidal anti-inflammatory drugs (NSAIDs)-exacerbated respiratory disease (N-ERD)?

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs)-exacerbated respiratory disease (N-ERD) complicates the clinical course of chronic rhinosinusitis with nasal polyps (CRSwNP) and severe asthma. We aimed to determine the detection rate of NERD in patients with CRSwNP, asthma, and history of NSAID intolerance using nasal challenge with acetylsalicylic acid (ASA) and the relationship between the severities of response to ASA challenges and the grade of N-ERD.

MATERIALS AND METHODS

Three groups of patients were included: CRSwNP with asthma and clinical history of analgesics intolerance (CRSwNP-AAI n = 18), CRSwNP with asthma but without a clinical history of analgesics intolerance (CRSwNP-A n = 20), and CRSwNP without asthma or analgesics intolerance (n = 18). All subjects were challenged nasally with 16 mg ASA and monitored with active anterior rhinomanometry. Rhinological (nasal polyp score), pulmonary (spirometry, Asthma Control Test (ACT), and asthma treatment), and psychometric questionnaire scores were recorded and correlated with rhinomanometric data following nasal challenges (flow depressions and symptom scores).

RESULTS

Nasal ASA challenge detected N-ERD in 96.7% of CRSwNP-AAI patients and 45% of CRSwNP-A patients. No N-ERD was seen in the CRSwNP group. The control grade of asthma measured with ACT scores was significantly lower in the groups CRSwNP-AAI (MV 18.22) and CRSwNP-A (MV 19.75) when compared to the CRSwNP group (MV 24.39) (p = 0.000). In the CRSwNP-AAI group, 11 patients had uncontrolled asthma (61%), and in the CRSwNP-A group, 9 patients had uncontrolled asthma (45%). No correlation was found between rhinology and pulmonary parameters, nasal symptoms, and the severity of nasal ASA challenges. Specific reactions were detectable under the therapy of prednisolone and omalizumab.

CONCLUSION

N-ERD might not always be detected by screening a patient's medical history. Nasal ASA challenges are recommended in patients with CRSwNP and asthma. The nasal challenge with ASA positively confirms the N-ERD diagnosis. Moreover, N-ERD is a differential diagnosis in patients with severe asthma with the need for prednisolone or omalizumab therapy. The severity of the reaction to the ASA challenge in controlled and uncontrolled asthma patients is independent of the grade of N-ERD.
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Associations between TMEM196 polymorphisms and NSAID-exacerbated respiratory disease in asthma

BACKGROUND

We previously found differences in the minor allele frequency (MAF) of single-nucleotide polymorphisms (SNPs) in transmembrane protein 196 (TMEM196) between 995 patients with aspirin-tolerant asthma (ATA) and 141 asthmatic patients with NSAID-exacerbated respiratory disease (NERD). In this study, we statistically analyzed the distributions of the genotypes and haplotypes of these SNPs to determine the exact association between TMEM196 genetic variants and the risk for NERD.

MATERIALS AND METHODS

Lewontin's D' and r values were used to measure linkage disequilibrium between the biallelic loci having MAFs more than 0.05, and haplotypes were inferred using the PHASE algorithm (version 2.0). The genotype distribution was analyzed by logistic regression models using age of onset, smoking status (nonsmoker=0, ex-smoker=1, smoker=2), and BMI as covariates. Regression analysis of the association between SNPs and the risk of NERD was analyzed using SPSS version 12.0 and PLINK version 1.9.

RESULTS

The MAF of rs9886152 C>T was significantly lower in NERD than in ATA [24.8 vs. 34.0%, odds ratio=0.64 (0.48-0.85), P=2.07×10, Pcorr=0.048]. The rate of the rs9886152 C>T minor allele was significantly lower in NERD than in ATA [44.0 vs. 56.4% in the codominant model, P=0.002, Pcorr=0.049, odds ratio=0.64 (0.48-0.85)]. An additional three SNPs (rs9639334 A>G, rs9638765 A>G, and rs2097811 G>A) showed similar associations with the risk of NERD. NERD patients had lower frequencies of the rs9639334 A>G minor allele (51.1 vs. 64.4%, P=0.002, Pcorr=0.043), rs9638765 A>G (49.7 vs. 64.2%, P=0.001, Pcorr=0.017), and rs2097811 G>A (51.1 vs. 64.5%, P=0.002, Pcorr=0.04) compared with ATA patients. Patients homozygous for the minor alleles of the four SNPs showed significantly less of an aspirin-induced decrease in forced expiratory volume in one second compared with those homozygous for the common alleles (P=0.003-0.012).

CONCLUSION

The minor alleles of the four SNPs in TMEM196 may exert a protective effect against the development of NERD and may be useful genetic markers to predict the risk of NERD.

Heterogeneity of NSAID-Exacerbated Respiratory Disease: has the time come for subphenotyping?

PURPOSE OF REVIEW

NSAID-Exacerbated Disease (N-ERD) is a chronic eosinophilic inflammatory disorder of the respiratory tract occurring in patients with asthma and/or rhinosinusitis with nasal polyps, whose symptoms are exacerbated by NSAIDs. The purpose of this review is to provide an update on clinical characteristics, pathophysiology, and management of N-ERD, and to emphasize heterogeneity of this syndrome.

RECENT FINDINGS

Growing evidence indicates that N-ERD, which has been considered a separate asthma phenotype, is heterogenous, and can be divided in several subphenotypes varying in clinical characteristics. Pathophysiology of N-ERD is complex and extends beyond abnormalities in the arachidonic acid metabolism. Heterogeneity of pathophysiological mechanisms underlying development of airway inflammation seems to be associated with variability in response to both anti-inflammatory and disease-specific treatments (e.g., with aspirin after desensitization).

SUMMARY

Progress in understanding of the pathophysiology of N-ERD leads to discovery and validation of new biomarkers facilitating diagnosis and predicting the response to treatment of the chronic inflammation underlying upper (CRSwNP) and lower airway (asthma) symptoms. Better characterization of the immunophysiopathological heterogeneity of N-ERD (identification of endotypes) may allow more personalized, endotype-driven approach to treatment in the future.

Clinical Implications of Single Nucleotide Polymorphisms in Diagnosis of Asthma and its Subtypes

For the past three decades, a large number of genetic studies have been performed to examine genetic variants associated with asthma and its subtypes in hopes of gaining better understanding of the mechanisms underlying disease pathology and to identify genetic biomarkers predictive of disease outcomes. Various methods have been used to achieve these objectives, including linkage analysis, candidate gene polymorphism analysis, and genome-wide association studies (GWAS); however, the degree to which genetic variants contribute to asthma pathogenesis has proven to be much less significant than originally expected. Subsequent application of GWAS to well-defined phenotypes, such as occupational asthma and non-steroidal anti-inflammatory drugexacerbated respiratory diseases, has overcome some of these limitations, although with only partial success. Recently, a combinatorial analysis of single nucleotide polymorphisms (SNPs) identified by GWAS has been used to develop sets of genetic markers able to more accurately stratify asthma subtypes. In this review, we discuss the implications of the identified SNPs in diagnosis of asthma and its subtypes and the progress being made in combinatorial analysis of genetic variants.

Complementary Participation of Genetics and Epigenetics in Development of NSAID-exacerbated Respiratory Disease

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) has attracted a great deal of attention because of its association with severe asthma. However, it remains widely underdiagnosed in asthmatics as well as the general population. Upon pharmacological inhibition of cyclooxygenase 1 by NSAIDs, production of anti-inflammatory prostaglandin E2 and lipoxins ceases, while release of proinflammatory cysteinyl leukotrienes increases. To determine the underlying mechanisms, many studies have attempted to elucidate the genetic variants, such as single nucleotide polymorphisms, responsible for alterations of prostaglandins and leukotrienes, but the results of these genetic studies could not explain the whole genetic pathogenesis of NERD. Accordingly, the field of epigenetics has been introduced as an additional contributor to genomic alteration underlying the development of NERD. Recently, changes in CpG methylation, as one of the epigenetic components, have been identified in target tissues of NERD. This review discusses in silico analyses of both genetic and epigenetic components to gain a better understanding of their complementary roles in the development of NERD. Although the molecular mechanisms underlying NERD pathogenesis remain poorly understood, genetic and epigenetic variations play significant roles. Our results enhance the understanding of the genetic and epigenetic mechanisms involved in the development of NERD and suggest new approaches toward better diagnosis and management.

Single nucleotide polymorphisms in TNF are associated with susceptibility to aspirin-exacerbated respiratory disease but not to cytokine levels: a study in Mexican mestizo population

AIM

To evaluate the association of three single nucleotide polymorphisms in TNF and one in LTA in Mexican patients with aspirin-exacerbated respiratory disease (AERD) and the correlation of those single nucleotide polymorphisms with serum levels of TNF-α.

PATIENTS & METHODS

Case-control study including 133 patients with AERD, 135 patients with asthma (aspirin-tolerant asthmatics) and 182 healthy subjects.

RESULTS

GA genotype of rs1800629 in TNF was found to be associated with the risk of developing AERD (p < 0.05; odds ratio = 2.36) and by dominant model (p < 0.05; odds ratio = 2.51). Furthermore, there was a difference in the serum levels between the aspirin-tolerant asthmatics group and the other groups (p < 0.001).

CONCLUSION

The GA genotype of rs1800629 is associated with genetic susceptibility to AERD, but it does not correlate to protein serum levels.

Diagnostic Accuracy of Urinary LTE4 Measurement to Predict Aspirin-Exacerbated Respiratory Disease in Patients with Asthma

BACKGROUND

Patients with aspirin-exacerbated respiratory disease (AERD) are distinguished from patients with aspirin-tolerant asthma (ATA) by significantly higher baseline concentrations of urinary leukotriene E₄ (uLTE₄). However, an overlap between the individual values of the groups exists.

OBJECTIVE

The objective of this study was to estimate the discriminative value of uLTE₄ concentration in differentiating between patients with AERD and patients with ATA and evaluate the diagnostic accuracy of uLTE₄ measurement alone and added to clinical parameters to predict AERD diagnosis in patients with asthma.

METHODS

Clinical data were collected from questionnaires. Spirometry, skin prick tests, total IgE, and blood eosinophilia were evaluated. ULTE₄ concentrations were measured in morning urine samples by enzyme-linked immune assay (ELISA).

RESULTS

Patients with AERD (n = 247) had significantly higher uLTE₄ concentrations than those with ATA (n = 239). The uLTE₄ concentration of 800.0 pg/mg creatinine as measured by ELISA on a spot sample best discriminated the 2 groups (area under the curve 0.7; 95% confidence interval 0.66-0.74, sensitivity 49%, specificity 81%). The positive predictive value and negative predictive value (NPV), after considering the prevalence of AERD in the population of asthmatics, were 16% and 96%, respectively. Nasal polyps, upper airway symptoms, nasal corticosteroid treatment, asthma exacerbations, forced expiratory volume in the 1 second predicted, and age of asthma onset were independent predictors of AERD diagnosis. The addition of elevated uLTE₄ concentration to the set of clinical parameters enhanced slightly the prediction of AERD diagnosis beyond the level predicted by clinical parameters (P = .036).

CONCLUSIONS

A set of typical clinical parameters has a superior accuracy in prediction of AERD diagnosis than the measurement of uLTE₄ concentration alone. The addition of uLTE₄ concentration to clinical parameters slightly enhances the prediction of AERD diagnosis, especially due to a high NPV.

Identification of phenotypic clusters of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease

BACKGROUND

Clinical presentation of nonsteroidal anti-inflammatory drugs exacerbated respiratory disease (NERD) is found to be heterogeneous. This study classified phenotypic clusters to determine NERD subtypes.

METHODS

We performed two-step cluster analysis using urticaria, chronic rhinosinusitis (CRS), and atopy, in a NERD cohort comprising 302 patients. Asthma exacerbation was defined as receiving at least one burst of intravenous steroid treatment and/or at least two bursts of oral steroid use (≥ 45 mg/3 days) per year. The possession rate of anti-asthmatic medications was estimated during the follow-up period.

RESULTS

There were four subtypes: subtype 1 (NERD with CRS/atopy and no urticaria), subtype 2 (NERD with CRS and no urticaria/atopy), subtype 3 (NERD without CRS/urticaria), and subtype 4 (NERD with urticaria). Significant differences were found between the four subtypes in the female proportion, baseline FEV1%, serum total IgE level, and sputum/peripheral eosinophil count. A higher frequency of asthma exacerbations was noted in subtype 1 compared to subtype 3. The possession rates of medium- to high-dose inhaled corticosteroids/long-acting beta₂ -agonists showed significant differences among the four subtypes. Metabolomic analysis showed that the four subtypes of NERD had a higher serum leukotriene E4 (LTE4) level than those with aspirin-tolerant asthma. The patients with subtypes 1 and 3 had a higher urine LTE4 level than those with subtype 2.

CONCLUSION

We found four distinct subtypes with different clinical/biochemical findings and asthma exacerbations in a NERD cohort. These findings suggest that stratified strategies by applying subtype classification may help achieve better outcomes in the management of NERD.

Association of interleukin-25 levels with development of aspirin induced respiratory diseases

BACKGROUND

Aspirin-exacerbated respiratory diseases (AERD) are caused by ingestion of non-steroidal anti-inflammatory drugs and are characterized by acute bronchospasms and marked infiltration of eosinophils, the latter being attributable to altered synthesis of cysteinyl leukotrienes (LT) and prostaglandins (PG). Recently, the innate Th2 response is revealed to induce eosinophil infiltration in allergic inflammation, however the role of the innate Th2 response has not been studies in AERD. Thus, we evaluated the relationship between the innate Th2 cytokines including IL-25, thymic stromal lymphopoietin (TSLP) and IL-33 and the development of AERD.

METHODS AND MATERIALS

Plasma IL-25, IL-33, and TSLP levels were measured before and after aspirin challenge in subjects with AERD (n = 25) and aspirin-tolerant asthma (ATA, n = 25) by enzyme-linked immunosorbent assay (ELISA). Pre and post-aspirin challenge levels of LTC4 and PGD2 were measured using ELISA.

RESULTS

Basal plasma IL-25 levels were significantly higher in AERD group than in normal controls and in ATA group (p = 0.025 and 0.031, respectively). IL-33 and TSLP levels were comparable in the AERD and ATA groups. After the aspirin challenge, the IL-25 levels were markedly decreased in the ATA group (p = 0.024), while not changed in the AERD group. The post-challenge IL-25 levels of all asthmatic subjects were significantly correlated with aspirin challenge - induced declines in FEV1 (r = 0.357, p = 0.011), but not with basal and post challenge LTC4 and PGD2 levels.

CONCLUSIONS

IL-25 is associated with bronchospasm after aspirin challenge, possibly via mechanisms other than altered LTC4 and PGD2 production.

Aspirin-intolerant asthma in the population: prevalence and important determinants

BACKGROUND

Population-based studies on aspirin-intolerant asthma (AIA) are very few, and no previous population study has investigated risk factors for the condition.

OBJECTIVE

To investigate the prevalence and risk factors of AIA in the general population.

METHODS

A questionnaire on respiratory health was mailed to 30,000 randomly selected subjects aged 16-75 years in West Sweden, 29,218 could be traced and 18,087 (62%) responded. The questionnaire included questions on asthma, respiratory symptoms, aspirin-induced dyspnoea and possible determinants.

RESULTS

The prevalence of AIA was 0.5%, 0.3% in men and 0.6% in women (P = 0.014). Sick leave, emergency visits due to asthma and all investigated lower respiratory symptoms were more common in AIA than in aspirin-tolerant asthma (ATA). Obesity was a strong risk factor for AIA (BMI > 35: odds ratio (OR) 12.1; 95% CI 2.49-58.5), and there was a dose-response relationship between increasing body mass index (BMI) and risk of AIA. Obesity, airborne occupational exposure and visible mould at home were considerably stronger risk factors for AIA than for ATA. Current smoking was a risk factor for AIA (OR 2.55; 95% CI 1.47-4.42), but not ATA.

CONCLUSION

Aspirin-intolerant asthma identified in the general population was associated with a high burden of symptoms, uncontrolled disease and a high morbidity. Increasing BMI increased the risk of AIA in a dose-response manner. A number of risk factors, including obesity and current smoking, were considerably stronger for AIA than for ATA.

Development of a genetic marker set to diagnose aspirin-exacerbated respiratory disease in a genome-wide association study

We developed a genetic marker set of single nucleotide polymorphisms (SNPs) by summing risk scores of 14 SNPs showing a significant association with aspirin-exacerbated respiratory disease (AERD) from our previous 660 W genome-wide association data. The summed scores were higher in the AERD than in the aspirin-tolerant asthma (ATA) group (P=8.58 × 10(-37)), and were correlated with the percent decrease in forced expiratory volume in 1 s after aspirin challenge (r(2)=0.150, P=5.84 × 10(-30)). The area under the curve of the scores for AERD in the receiver operating characteristic curve was 0.821. The best cutoff value of the summed risk scores was 1.01328 (P=1.38 × 10(-32)). The sensitivity and specificity of the best scores were 64.7% and 85.0%, respectively, with 42.1% positive and 93.4% negative predictive values. The summed risk score may be used as a genetic marker with good discriminative power for distinguishing AERD from ATA.

Dipeptidyl-peptidase 10 as a genetic biomarker for the aspirin-exacerbated respiratory disease phenotype

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is an endotype of severe and eosinophilic adult asthma characterized by chronic rhinosinusitis with nasal polyps and hypersensitivity to aspirin and/or nonsteroidal anti-inflammatory drugs. A genetic contribution of dipeptidyl-peptidase 10 (DPP10) to asthma susceptibility and lung function decline has been reported. However, little is known about the role of DPP10 in the pathogenesis of AERD.

OBJECTIVE

To identify genetic variants of DPP10 that confer susceptibility to AERD or severe asthma.

METHODS

A case-control association study of DPP10 gene polymorphisms was performed in 3 groups of patients: 274 with AERD, 272 with aspirin-tolerant asthma, and 99 normal healthy controls. The rs17048175 single-nucleotide polymorphism was targeted based on a preliminary genomewide association study using an Affymetrix genomewide human single-nucleotide polymorphism array in a Korean population. DPP10, 15-hydroxyeicosatetraenoic acid, and YKL-40/chitinase-3-like protein were measured by enzyme-linked immunosorbent assay in sera taken from the study subjects.

RESULTS

There was a significant association between rs17048175 and the AERD phenotype, but not with aspirin-tolerant asthma. The DPP10 level was significantly higher in sera from patients with AERD compared with patients with aspirin-tolerant asthma and control subjects (P = .021 and P < .001, respectively). In addition, there was a significant difference of serum DPP10 level according to the single-nucleotide polymorphism (P = .001). Serum DPP10 level showed a strong correlation with 15-hydroxyeicosatetraenoic acid (r = 0.226, P = .017) and YKL-40 (r = 0.364, P = .004).

CONCLUSION

This study suggests a genetic contribution of rs17048175 to DPP10 in eosinophilic inflammation induction in the airways and to AERD susceptibility.

Exonic variants associated with development of aspirin exacerbated respiratory diseases

Aspirin-exacerbated respiratory disease (AERD) is one phenotype of asthma, often occurring in the form of a severe and sudden attack. Due to the time-consuming nature and difficulty of oral aspirin challenge (OAC) for AERD diagnosis, non-invasive biomarkers have been sought. The aim of this study was to identify AERD-associated exonic SNPs and examine the diagnostic potential of a combination of these candidate SNPs to predict AERD. DNA from 165 AERD patients, 397 subjects with aspirin-tolerant asthma (ATA), and 398 normal controls were subjected to an Exome BeadChip assay containing 240K SNPs. 1,023 models (2¹⁰-1) were generated from combinations of the top 10 SNPs, selected by the p-values in association with AERD. The area under the curve (AUC) of the receiver operating characteristic (ROC) curves was calculated for each model. SNP Function Portal and PolyPhen-2 were used to validate the functional significance of candidate SNPs. An exonic SNP, exm537513 in HLA-DPB1, showed the lowest p-value (p = 3.40×10⁻⁸) in its association with AERD risk. From the top 10 SNPs, a combination model of 7 SNPs (exm537513, exm83523, exm1884673, exm538564, exm2264237, exm396794, and exm791954) showed the best AUC of 0.75 (asymptotic p-value of 7.94×10⁻²¹), with 34% sensitivity and 93% specificity to discriminate AERD from ATA. Amino acid changes due to exm83523 in CHIA were predicted to be “probably damaging” to the structure and function of the protein, with a high score of ‘1’. A combination model of seven SNPs may provide a useful, non-invasive genetic marker combination for predicting AERD.

An update on the pathogenesis of the upper airways in aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

The key features of aspirin-exacerbated respiratory diseases (AERDs) include chronic, severe asthma and a high prevalence (60-80%) of chronic rhinosinusitis with nasal polyps, all of which are exacerbated by exposure to aspirin and other NSAIDs. Although the pathogenic mechanisms of AERD are not completely understood, repeated instances have shown intense eosinophilic infiltrations of upper and lower airway mucosa, and dysregulation of arachidonate metabolisms. Here, recent updates on the pathogenic mechanisms of chronic rhinosinusitis with nasal polyps in aspirin-exacerbated respiratory diseases are summarized.

RECENT FINDINGS

Intense eosinophilic infiltration is closely related to the elevated production of cytokines and chemokines such as IL-5 and eotaxin. The response of local immunoglobulin E to staphylococcal enterotoxins contributes to eosinophilic inflammation in nasal polyp tissue. Other characteristics include the overproduction of cysteinyl leukotrienes and increased expression of cysteinyl leukotriene receptor-1, reduced production of prostaglandin E2, and the down-regulation of cyclooxygenase-2 and E-prostanoid receptor subtype-2. A recent gene expression profiling study has also suggested that periostin is the most up-regulated gene in the nasal polyp tissue of AERD patients.

SUMMARY

Chronic rhinosinusitis with nasal polyps is a major comorbid condition of AERD patients that is closely associated with severe asthmatic symptoms. Significant pathologic findings in nasal polyp tissues include intense eosinophilic inflammation, which is caused by elevated production of eosinophil-related cytokines and chemokines, specific immunoglobulin E responses to staphylococcal enterotoxins, and altered arachidonic acid metabolism. This could affect the current treatments and methodologies that are used to control asthma, leading to a more severe and intractable AERD phenotype.

Prostaglandin E2 receptors in asthma and in chronic rhinosinusitis/nasal polyps with and without aspirin hypersensitivity

Chronic rhinosinusitis with nasal polyps (CRSwNP) and asthma frequently coexist and are always present in patients with aspirin exacerbated respiratory disease (AERD). Although the pathogenic mechanisms of this condition are still unknown, AERD may be due, at least in part, to an imbalance in eicosanoid metabolism (increased production of cysteinyl leukotrienes (CysLTs) and reduced biosynthesis of prostaglandin (PG) E2), possibly increasing and perpetuating the process of inflammation. PGE2 results from the metabolism of arachidonic acid (AA) by cyclooxygenase (COX) enzymes, and seems to play a central role in homeostasis maintenance and inflammatory response modulation in airways. Therefore, the abnormal regulation of PGE2 could contribute to the exacerbated processes observed in AERD. PGE2 exerts its actions through four G-protein-coupled receptors designated E-prostanoid (EP) receptors EP1, EP2, EP3, and EP4. Altered PGE2 production as well as differential EP receptor expression has been reported in both upper and lower airways of patients with AERD. Since the heterogeneity of these receptors is the key for the multiple biological effects of PGE2 this review focuses on the studies available to elucidate the importance of these receptors in inflammatory airway diseases.

[Aspirin hypersensitivity: characteristics and diagnostic approach]

INTRODUCTION

In routine medical practice, the diagnosis of aspirin hypersensitivity (AH) remains difficult. No clinical feature or biomarker is available to reliably confirm this diagnosis and oral provocation tests (OPT) are rarely performed.

AIM

To compare asthmatics with and without AH.

METHOD

The clinical characteristics of 21 asthmatics with and 24 without AH respectively were determined. AH was defined by a positive OPT. A full blood count was done before and 24 hours after the OPT.

RESULTS

The medical history was associated with a weak sensitivity (52%) and a good specificity (96%) for assessing the diagnosis of AH. There was a higher prevalence of AH in women, and a higher frequency of allergic rhinitis in AH, but no characteristic was useful to facilitate the diagnosis of AH in asthmatic patients. Our results demonstrate higher values of platelets in AH patients. Following OPT, in AH patients only, a decrease in blood eosinophils and an increase in neutrophils was observed.

CONCLUSIONS

These results confirm that the diagnosis of AH is challenging, with the history having only weak sensitivity. The observation that fluctuations in eosinophils and neutrophils occur following OPT in AH patients only warrants further investigations and suggests a rapid pro-inflammatory role for aspirin.

Association analysis of member RAS oncogene family gene polymorphisms with aspirin intolerance in asthmatic patients

Member RAS oncogene family (RAB1A), a member of the RAS oncogene family, cycles between inactive GDP-bound and active GTP-bound forms regulating vesicle transport in exocytosis. Thus, functional alterations of the RAB1A gene may contribute to aspirin intolerance in asthmatic sufferers. To investigate the relationship between single-nucleotide polymorphisms (SNPs) in the RAB1A gene and aspirin-exacerbated respiratory disease (AERD), asthmatics (n=1197) were categorized into AERD and aspirin-tolerant asthma (ATA). All subjects were diagnosed as asthma on the basis of the Global Initiative for Asthma (GINA) guidelines. AERD was defined as asthmatics showing 15% or greater decreases in forced expiratory volume in one second (FEV(1)) or naso-ocular reactions by the oral acetyl salicylic acid (ASA) challenge (OAC) test. In total, eight SNPs were genotyped. Logistic regression analysis identified that the minor allele frequency of +14444 T>G and +41170 C>G was significantly higher in the AERD group (n=181) than in the ATA group (n=1016) (p=0.0003-0.03). Linear regression analysis revealed a strong association between the SNPs and the aspirin-induced decrease in FEV(1) (p=0.0004-0.004). The RAB1A gene may play a role in the development of AERD in asthmatics and the genetic polymorphisms of the gene have the potential to be used as an indicator of this disease.

Association analysis of tapasin polymorphisms with aspirin-exacerbated respiratory disease in asthmatics

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by the development of airway obstruction in asthmatic individuals following the ingestion of aspirin or other nonsteroidal anti-inflammatory drugs. TAPBP (TAP-binding protein, tapasin) is upregulated by eicosanoids, which act as potent inflammatory molecules in aspirin-related reactions. Thus, functional alterations in the TAPBP gene may contribute toward AERD.

OBJECTIVES

We examined the relationship between the single nucleotide polymorphisms on the TAPBP gene and AERD.

MATERIALS AND METHODS

A group of asthmatic patients (n=1252) underwent the oral aspirin challenge. Oral aspirin challenge reactions were categorized into two groups as follows: 15% or greater decreases in forced expiratory volume in 1 s or naso-ocular and skin reactions (AERD), or 15% or less decreases in forced expiratory volume in 1 s without naso-ocular and skin reactions (aspirin-tolerant asthma). Five single nucleotide polymorphisms of the TAPBP gene were genotyped.

RESULTS

Logistic regression analysis showed that the minor allele frequencies of TAPBP rs2071888 C>G (Thr260Arg) on exon 4 (P>0.05), which was in absolute linkage disequilibrium with rs1059288 T>C on 3'UTR, were significantly higher in the AERD group than in the aspirin-tolerant asthma group, and the P values remained significant after multiple comparisons (Pcorr=0.006, odds ratio: 1.37, 95% confidence interval: 1.11-1.69, additive model; Pcorr=0.009, odds ratio: 1.52, 95% confidence interval: 1.14-2.03, dominant model). Alpha-helical wheel plotting showed that 260Arg had greater hydrophilic helical property than 260Thr.

CONCLUSION

TAPBP polymorphisms may play a role in the development of AERD.

Plasma apolipoprotein H levels are different between aspirin induced respiratory diseases and aspirin tolerant asthma

Aspirin-exacerbated respiratory disease (AERD) has attracted a great deal of attention because of its association with increased asthma severity. To identify plasma biomarkers for the prediction of AERD, the six most abundant plasma proteins (albumin, IgG, antitrypsin, IgA, transferrin, and haptoglobin) in pooled plasma samples were removed using a multiple affinity removal system column. Two-dimensional gel electrophoresis (2DE) was used for differential display proteomic analysis of the pooled plasma. Proteins were identified by matrix assisted laser desorption ionization time-of-flight (MALDI-TOF)/TOF. Enzyme-linked immunosorbent assay (ELISA) was performed to identify and quantify apolipoprotein H (Apo H) in plasma from subjects with AERD and aspirin-tolerant asthma (ATA). Eight protein spots showed differences in relative intensity between pooled plasma from subjects with AERD (n = 8) and those with ATA (n = 8). MALDI-TOF/TOF analysis showed decreases in the levels of alpha-fibrinogen precursor, Apo H, fibrin beta, and proapolipoprotein in AERD as compared with ATA, and increases in chain A human complement component C3, 90-kDa heat shock protein, complement component C4a, and kininogen-1 isoform 2. Apo H concentrations were significantly increased in plasma from subjects with ATA than those with AERD and normal controls, as measured by ELISA (P < 0.01). AERD is characterized by changes in the levels of proteins involved in the coagulation and complement pathways. In addition, Apo H is up-regulated in ATA compared to AERD and normal controls, suggesting that Apo H may be involved in different pathogenesis of ATA from AERD.

Elevation of Eosinophil-Derived Neurotoxin in Plasma of the Subjects with Aspirin-Exacerbated Respiratory Disease: A Possible Peripheral Blood Protein Biomarker

Aspirin-exacerbated respiratory disease (AERD) remains widely underdiagnosed in asthmatics, primarily due to insufficient awareness of the relationship between aspirin ingestion and asthma exacerbation. The identification of aspirin hypersensitivity is therefore essential to avoid serious aspirin complications. The goal of the study was to develop plasma biomarkers to predict AERD. We identified differentially expressed genes in peripheral blood mononuclear cells (PBMC) between subjects with AERD and those with aspirin-tolerant asthma (ATA). The genes were matched with the secreted protein database (http://spd.cbi.pku.edu.cn/) to select candidate proteins in the plasma. Plasma levels of the candidate proteins were then measured in AERD (n = 40) and ATA (n = 40) subjects using an enzyme-linked immunosorbent assay (ELISA). Target genes were validated as AERD biomarkers using an ROC curve analysis. From 175 differentially expressed genes (p-value <0.0001) that were queried to the secreted protein database, 11 secreted proteins were retrieved. The gene expression patterns were predicted as elevated for 7 genes and decreased for 4 genes in AERD as compared with ATA subjects. Among these genes, significantly higher levels of plasma eosinophil-derived neurotoxin (RNASE2) were observed in AERD as compared with ATA subjects (70(14.62∼311.92) µg/ml vs. 12(2.55∼272.84) µg/ml, p-value <0.0003). Based on the ROC curve analysis, the AUC was 0.74 (p-value = 0.0001, asymptotic 95% confidence interval [lower bound: 0.62, upper bound: 0.83]) with 95% sensitivity, 60% specificity, and a cut-off value of 27.15 µg/ml. Eosinophil-derived neurotoxin represents a novel biomarker to distinguish AERD from ATA.

A genetic effect of IL-5 receptor α polymorphism in patients with aspirin-exacerbated respiratory disease

Persistent eosinophil activation in both the upper and lower airway mucosa is a central feature of aspirin-exacerbated respiratory disease (AERD). Eosinophil activation and survival are profoundly influenced by interleukin 5 (IL-5) and its receptor, IL-5R. In patients susceptible to allergic disorders, IL-5 receptor α (IL5RA) polymorphisms have been reported; however, an association with AERD remains unclear. We hypothesize that IL5RA polymorphisms may contribute to eosinophil activation in AERD patients. We recruited 139 AERD patients, 171 aspirin-tolerant asthma patients and 160 normal controls. IL5RA polymorphisms (−5993G>A, −5567C>G and −5091G>A) were genotyped and functional activity of polymorphism was assessed by luciferase reporter assay and electrophoretic mobility shift assay (EMSA). There was no significant difference in the genotype frequency of the three polymorphisms among the three groups. AERD patients carrying the AA genotype at −5993G>A had a significantly higher presence of serum-specific immunoglobulin E (IgE) to staphylococcal enterotoxin A (P=0.008) than those with the GG/GA genotype. In vitro, the −5993A allele had a higher promoter activity compared with the −5993G allele in human mast cell (HMC-1; P=0.030) and human promyelocytic leukemia (HL-60; P=0.013) cells. In EMSA, a −5993A probe produced a specific shifted band than the −5993G had. These findings suggest that a functional polymorphism in IL5RA may contribute to eosinophil and mast cell activation along with specific IgE responses to staphylococcal enterotoxin A in AERD patients.

Association of single nucleotide polymorphisms on Interleukin 17 receptor A (IL17RA) gene with aspirin hypersensitivity in asthmatics

AIM

To investigate the association of single nucleotide polymorphisms (SNP) on IL17RA gene with Aspirin Exacerbated Respiratory Disease (AERD) and the functional effect of these variants on expression of IL17RA gene products.

MATERIAL & METHODS

15 SNPs of IL17RA gene were analyzed in 825 normal controls and 143 subjects with AERD and 411 with aspirin-tolerant asthma (ATA) and functionally characterized using measurement of protein and m-RNA expression.

RESULT

Minor alleles frequencies of the three SNPs (-1075 A>G, -947 A>G, -50 C>T) and one haplotype (BL1_ht1) were significantly lower in AERD compared to those in ATA (p(corr)=0.002-0.03). IL17RA protein expression and mRNA amount in CD14(+) peripheral blood monocytes and mononuclear cells were significantly increased in subjects carrying the common alleles homozygote compared with those carrying the minor alleles.

CONCLUSIONS

The minor alleles of the three SNPs may decrease the risk of AERD via attenuation of IL17RA gene expression.

Aspirin-intolerant asthma in the Korean population: prevalence and characteristics based on a questionnaire survey

BACKGROUND

Aspirin-intolerant asthma is a unique clinical syndrome characterized by acute bronchoconstriction following the administration of aspirin and/or non-steroidal anti-inflammatory drugs.

OBJECTIVE

We assessed the prevalence and investigated the demographic and clinical characteristics of adult patients with aspirin-intolerant asthma in Korea.

METHODS

Using an adult asthma cohort (COREA) from 11 university hospitals in Korea, we analyzed the prevalence of aspirin-intolerant asthma, defined as a positive response to the question: "Have you ever experienced dyspnea and cough after taking an aspirin or any NSAID (cold medicine)?" Demographic and clinical characteristics were compared between patients with aspirin-intolerant asthma and aspirin-tolerant asthma.

RESULTS

Aspirin-intolerant asthma was reported in 68 (5.8%) of 1173 adult asthmatics (age 15-84). Patients with aspirin-intolerant asthma had a lower mean age (43.9 ± 13.4 vs. 49.0 ± 15.6, P = 0.003) and a higher prevalence of rhinosinusitis (77.9% vs. 61.7%, P = 0.012) and atopic dermatitis (16.2% vs. 5.7%, P = 0.001) than aspirin-tolerant asthma patients. There were no significant differences in lung function, asthma severity or the use of asthma controllers. However, aspirin-intolerant asthma was associated with greater use of healthcare services over a lifetime and over the past 12 months. Aspirin-intolerant asthma was significantly associated with emergency room visits over the past 12 months (P = 0.029, OR 2.19, 95% CI 1.08-4.42).

CONCLUSION

Based on histories, the prevalence of aspirin-intolerant asthma is 5.8% among adult asthma patients in Korea. Aspirin-intolerant asthma is associated with lower age, higher prevalence of rhinosinusitis and atopic dermatitis, and more frequent exacerbations.

Genome-wide association study of aspirin-exacerbated respiratory disease in a Korean population

Aspirin-exacerbated respiratory disease (AERD) is a nonallergic clinical syndrome characterized by a severe decline in forced expiratory volume in one second (FEV1) following the ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin. The effects of genetic variants have not fully explained all of the observed individual differences to an aspirin challenge despite previous attempts to identify AERD-related genes. In the present study, we performed genome-wide association study (GWAS) and targeted association study in Korean asthmatics to identify new genetic factors associated with AERD. A total of 685 asthmatic patients without AERD and 117 subjects with AERD were used for the GWAS of the first stage, and 996 asthmatics without AERD and 142 subjects with AERD were used for a follow-up study. A total of 702 SNPs were genotyped using the GoldenGate assay with the VeraCode microbead. GWAS revealed the top-ranked variants in 3' regions of the HLA-DPB1 gene. To investigate the detailed genetic effects of an associated region with the risk of AERD, a follow-up targeted association study with the 702 single nucleotide polymorphisms (SNPs) of 14 genes was performed on 802 Korean subjects. In a case-control analysis, HLA-DPB1 rs1042151 (Met105Val) shows the most significant association with the susceptibility of AERD (p = 5.11 × 10(-7); OR = 2.40). Moreover, rs1042151 also shows a gene dose for the percent decline of FEV1 after an aspirin challenge (p = 2.82 × 10(-7)). Our findings show that the HLA-DPB1 gene polymorphism may be the most susceptible genetic factor for the risk of AERD in Korean asthmatics and confirm the importance of HLA-DPB1 in the genetic etiology of AERD.

A highly sensitive and specific genetic marker to diagnose aspirin-exacerbated respiratory disease using a genome-wide association study

The aim of the present study was to develop a diagnostic set of single-nucleotide polymorphisms (SNPs) for discriminating aspirin-exacerbated respiratory disease (AERD) from aspirin-tolerant asthma (ATA) using the genome-wide association study (GWAS) data; the GWAS data were filtered according to p-values and odds ratios (ORs) using PLINK software, and the 10 candidate SNPs most closely associated with AERD were selected, based on 100 AERD and 100 ATA subjects. Using multiple logistic regression and receiver-operating characteristic (ROC) curve analysis, eight SNPs were chosen as the best model for distinguishing between AERD and ATA. The relative risk for AERD in each subject was calculated based on the relative risk of each of the eight SNPs. Ten of the original 109,365 SNPs highly associated (filtered with p<0.001 and ORs) with the risk for AERD were selected. A combination model of the eight SNPs among the 10 SNPs showed the highest area under the ROC curve of 0.9. The overall relative risk for AERD based on the eight SNPs was significantly different between the AERD and ATA groups (p=2.802E-21), and the sensitivity and specificity were 78% and 88%, respectively. The candidate set of eight SNPs may be useful in predicting the risk for AERD.

Aspirin sensitivity and chronic rhinosinusitis with polyps: a fatal combination

Aspirin-exacerbated respiratory disease (AERD) refers to aspirin sensitivity, chronic rhinosinusitis (CRS), nasal polyposis, asthma, eosinophil inflammation in the upper and lower airways, urticaria, angioedema, and anaphylaxis following the ingestion of NSAIDs. Epidemiologic and pathophysiological links between these diseases are established. The precise pathogenesis remains less defined, even though there is some progress in the understanding of several molecular mechanisms. Nevertheless, these combinations of diseases in patients classified by AERD constitute a fatal combination and may be difficult to treat with standard medical and surgical interventions. This paper reviews in brief the epidemiology, clinical features, diagnosis, molecular pathogenesis, and specific therapies of patients classified by AERD and postulates future attempts to gain new insights into this disease.

Association analysis of formyl peptide receptor 2 (FPR2) polymorphisms and aspirin exacerbated respiratory diseases

Aspirin-exacerbated respiratory diseases (AERD) are associated with the metabolism of arachidonic acid. FPR2 (formyl peptide receptor2) is a high-affinity ligand receptor for potent anti-inflammatory lipid metabolites: lipoxins. Thus, functional alterations of the FPR2 may contribute to AERD. We investigated the relationship between single-nucleotide polymorphisms (SNPs) in the FPR2 and AERD. Asthmatics were categorized into AERD <15% decreases in forced expiratory volume in one second (FEV(1)), and/or naso-ocular reactions after oral aspirin challenge (n=170) and aspirin-tolerant asthma (ATA, n=268). In all, 11 SNPs were genotyped. FPR2 protein expressions on CD14-positive monocytes in peripheral blood were measured using flow cytometric analysis. We performed RT-PCR of the FPR2 mRNA expressed by peripheral blood mononuclear cells. Logistic regression analysis showed that the minor allele frequency of FPR2 -4209T>G (rs1769490) in intron 2 was significantly lower in the AERD group (n=170) than in the ATA group (n=268) (P=0.006, P(corr)=0.04, recessive model). The decline of FEV(1) after aspirin challenge was significantly lower in the subjects with GG homozygotes of FPR2 -4209T>G than those with the other genotypes (P=0.0002). Asthmatic homozygotes for FPR2 -4209T>G minor allele exhibited significantly higher FPR2 protein expression in CD14-positive monocytes than did those with the common allele of FPR2 -4209T>G allele (P=0.01). There was no difference in the expression of the wild form and the exon 2 deleted variant form of FPR2 gene according to the genotypes of FPR2 -4209T>G. The minor allele at FPR2 -4209T>G may have a protective role against the development of AERD, via increase of FPR2 protein expression in inflammatory cells.