Lung function response to 12-week treatment with combined inhalation of long-acting beta2 agonist and glucocorticoid according to ADRB2 polymorphism in patients with chronic obstructive pulmonary disease

Transcription Factor E2F1 Regulates the Expression of ADRB2

Adrenergic beta-2-receptor (ADRB2) is highly expressed in various tissue cells, affecting the susceptibility, development, and drug efficacy of diseases such as bronchial asthma and malignant tumor. However, the transcriptional regulatory mechanism of the human ADRB2 gene remains unclear. This study aimed to clarify whether E2F transcription factor 1 (E2F1) was involved in the transcriptional regulation of the human ADRB2 gene. First, the 5' flanking region of the human ADRB2 gene was cloned, and its activity was detected using A549 and BEAS-2B cells. Second, it was found that the overexpression of E2F1 could increase promoter activity by a dual-luciferase reporter gene assay. In contrast, treatment of knockdown of E2F1 significantly resulted in a decrease in its promoter activity. Moreover, mutation of the binding site of E2F1 greatly reduced the potential of human ADRB2 promoter transcriptional activity to be regulated by E2F1 overexpression and knockdown. Additionally, by real-time quantitative PCR and Western blot analysis, we demonstrated that overexpression of E2F1 elevated the ADRB2 mRNA expression and protein levels while si-E2F1 reduced its expression. Finally, the consequence of the chromatin immunoprecipitation assay showed that E2F1 was able to bind to the promoter region of ADRB2 in vivo. These results confirmed that E2F1 upregulated the expression of the human ADRB2 gene.

Clinical course of COPD in patients with Arg16Gly (rs1042713) polymorphism of <em>ADRB2</em> gene

The ADBR2 gene has been studied for its possible relationship with the development and clinical course of chronic obstructive pulmonary disease (COPD), including response to beta-2 agonists, with existing data being contentious on the subject. So, the purpose of this study was to look into the potential impact of the arginine-16-glycine (Arg16Gly) polymorphism on the clinical course and drug utilization in COPD patients. Data show that patients with Arg16Arg have a lower number of hospital admissions for exacerbations (p=0.048), but only in the total number of exacerbations, including those treated out-patients (p=0.086). Each glycine (Gly) copy was associated with a higher number of exacerbations (OR: 0.25; 95% CI: 0.00-055; p=0.048). The number of exacerbations after LABA/LAMA treatment was similar across groups, indicating that all ADRB2 variants responded well to the treatment. Furthermore, there were no statistically significant differences in mMRC and CAT values across all study visits. Interestingly, groups differed in their use of antibiotics (AB) at all visits, with Arg16Arg being associated with the least amount of AB use. There was also a link discovered between clycine copies and increased use of glucocorticoids. As a result, Arg16Gly is involved in the clinical course of COPD as well as the utilization of drug groups. Based on the findings, we can speculate that the cross-talk between the ADRB2 gene and the corticosteroid receptor is altered in patients with the Gly16Gly genotype.

β2-Adrenergic Receptor (ADRB2) Gene Polymorphisms and Risk of COPD Exacerbations: The Rotterdam Study

The role of the β₂-adrenergic receptor (ADRB2) gene in patients with chronic obstructive pulmonary disease (COPD) is unclear. We investigated the association between ADRB2 variants and the risk of exacerbations in COPD patients treated with inhaled β₂-agonists. Within the Rotterdam Study, a population-based cohort study, we followed 1,053 COPD patients until the first COPD exacerbation or end of follow-up and extracted rs1042713 (16Arg > Gly) and rs1042714 (27Gln > Glu) in ADRB2. Exposure to inhaled β₂-agonists was categorised into current, past or non-use on the index date (date of COPD exacerbation for cases and on the same day of follow-up for controls). COPD exacerbations were defined as acute episodes of worsening symptoms requiring systemic corticosteroids and/or antibiotics (moderate exacerbations), or hospitalization (severe exacerbations). The associations between ADRB2 variants and COPD exacerbations were assessed using Cox proportional hazards models, adjusting for age, sex, use of inhaled corticosteroids, daily dose of β₂-agonists, and smoking. In current users of β₂-agonists, the risk of COPD exacerbation decreased by 30% (hazard ratio (HR); 0.70, 95% CI: 0.59-0.84) for each copy of the Arg allele of rs1042713 and by 20% (HR; 0.80, 95% CI: 0.69-0.94) for each copy of the Gln allele of rs1042714. Furthermore, current users carrying the Arg16/Gln27 haplotype had a significantly lower risk (HR; 0.70, 95% CI: 0.59-0.85) of COPD exacerbation compared to the Gly16/Glu27 haplotype. In conclusion, we observed that the Arg16/Gln27 haplotype in ADRB2 was associated with a reduced risk of COPD exacerbation in current users of inhaled β₂-agonists.

Impact of symptom variability on clinical outcomes in COPD: analysis of a longitudinal cohort

Purpose

We compared clinical characteristics of COPD patients according to symptom variability and evaluated the effect of symptom variability during the first year of enrollment on clinical outcomes of COPD.

Methods

We analyzed COPD patients’ data from the Korean Obstructive Lung Disease (KOLD) cohort. Symptom variability was defined based on the value of standard deviation (SD) of mMRC scores obtained every 3 months during the follow-up period of the first year. Patients were divided into 2 groups: the consistent (SD of mMRC scores =0) and variable (SD of mMRC scores >0) groups. Clinical characteristics and outcomes were compared in terms of symptom variability.

Results

A total of 407 patients were included in the analysis. Patient age was 67.2 years and 97.8% of the subjects were male. Initial mMRC was 1.5 and the SD of mMRC scores during the first year was 0.5. There were 137 subjects (33.7%) in the consistent group and 270 (66.3%) in the variable group. The variable group showed a lower FEV₁ (P=0.019) and a higher mMRC score (P=0.001). The annual incidence of acute exacerbation of COPD (AE-COPD) tended to be higher in the variable group (P=0.078) and that of severe AE-COPD was higher in the variable group than in the consistent group (P=0.002). The variable group showed a higher proportion of annual exacerbators (P=0.001) and frequent exacerbators (P=0.017). In multivariate logistic regression analysis, the variable group was significantly associated with annual exacerbators (OR =1.963, P=0.011) and frequent exacerbators (OR =2.090, P=0.055).

Conclusion

COPD patients with symptom variability may have higher exacerbation risk as well as lower lung function and more severe respiratory symptoms.

Upregulation of microRNA‑16 alters the response to inhaled β‑agonists in patients with asthma though modulating expression of ADRB2

MicroRNAs (miRNAs) are non‑coding RNAs of ~22 nucleotides in length, which serve an important role in numerous diseases. Asthma is a chronic airway inflammatory disease, which is the most common chronic disease among children. The role of miRNA (miR)‑16 in asthma is unclear. The objective of the present study was to examine the underlying molecular mechanism of the involvement of miR‑16 in asthma. A total of 72 volunteers diagnosed with asthma consented to participate in the study, of whom 52 participants were identified to be sensitive to salmeterol and 20 participants were identified to be resistant to salmeterol. Receiver operating characteristic (ROC) curve analysis was performed to compare the expression levels of serum miR‑16 between the sensitive and resistant groups, and to confirm the association between the expression level of serum miR‑16 and forced expiratory volume in 1 sec (FEV1). In silico analysis, a luciferase assay, reverse transcription‑quantitative polymerase chain reaction analysis and western blotting were performed to elucidate the molecular mechanism underlying the role of miR‑16 in asthma. ROC results demonstrated that the serum miR‑16 level may function as a biomarker to predict the response to salmeterol therapy, and the miR‑16 expression level displayed a significant negative correlation with FEV1. According to the in silico analysis, adrenoreceptor β‑2 (ADRB2) was a direct target of miR‑16, and it was further confirmed by luciferase assay that 25 nM miR‑16 mimic had an inhibitory effect on the luciferase activity of the wild‑type ADRB2 3' untranslated region (UTR); the inhibitory effect on the luciferase activity of the wild‑type ADRB2 3'UTR was stronger with 50 nM miR‑16 mimic, and strongest with 75 nM miR‑16 mimic, whereas the luciferase activity of the mutant ADRB2 3'UTR in cells was similar following treatment with 0, 25, 50 or 75 nM miR‑16 mimic. miR‑16 reduced the mRNA and protein expression levels of ADRB2 in a dose‑dependent manner. These results identified that miR‑16 may be used as a predictive biomarker of therapeutic response in asthma.

Predicting treatable traits for long-acting bronchodilators in patients with stable COPD

Purpose

There is currently no measure to predict a treatability of long-acting β-2 agonist (LABA) or long-acting muscarinic antagonist (LAMA) in patients with chronic obstructive pulmonary disease (COPD). We aimed to build prediction models for the treatment response to these bronchodilators, in order to determine the most responsive medication for patients with COPD.

Methods

We performed a prospective open-label crossover study, in which each long-acting bronchodilator was given in a random order to 65 patients with stable COPD for 4 weeks, with a 4-week washout period in between. We analyzed 14 baseline clinical traits, expression profiles of 31,426 gene transcripts, and damaged-gene scores of 6,464 genes acquired from leukocytes. The gene expression profiles were measured by RNA microarray and the damaged-gene scores were obtained after DNA exome sequencing. Linear regression analyses were performed to build prediction models after using factor and correlation analyses.

Results

Using a prediction model for a LABA, traits found associated with the treatment response were post-bronchodilator forced expiratory volume in 1 second, bronchodilator reversibility (BDR) to salbutamol, expression of three genes (CLN8, PCSK5, and SKP2), and damage scores of four genes (EPG5, FNBP4, SCN10A, and SPTBN5) (R²=0.512, p<0.001). Traits associated with the treatment response to a LAMA were COPD assessment test score, BDR, expression of four genes (C1orf115, KIAA1618, PRKX, and RHOQ) and damage scores of three genes (FBN3, FDFT1, and ZBED6) (R²=0.575, p<0.001). The prediction models consisting only of clinical traits appeared too weak to predict the treatment response, with R²=0.231 for the LABA model and R²=0.121 for the LAMA model.

Conclusion

Adding the expressions of genes and damaged-gene scores to the clinical traits may improve the predictability of treatment response to long-acting bronchodilators.

Beta-2-adrenoreceptor polymorphism at position 16 determines the clinical severity of chronic obstructive pulmonary disease

The Arg/Arg homozygosity at codon 16 of the beta-2-adrenoreceptor (ADRB2) gene has been thought to predispose asthma patients to a poorer therapeutic response to beta-2-mimetics, or to worse control of the disease. In contrast, the results of the studies analysing the effect of ADRB2 polymorphisms on the response to beta-2-adrenoreceptor agonists in chronic obstructive pulmonary disease (COPD) patients are sparse and inconclusive. The aim of this research was to verify if p.Arg16Gly (c.46A > G) and p.Gly27Glu (c.79G > C) single nucleotide polymorphisms (SNPs) exert a negative effect on the selected clinical indicators of COPD. The SNPs of the ADRB2 were identified by multiplex allele-specific PCR on DNA isolated from the venous blood leukocytes of 92 patients with stable grade COPD. In addition, all of the patients were asked about the course of COPD during the 12 months preceding the study, including the frequency of exacerbations requiring hospitalisation, the number of antibiotic therapy courses given due to the lower respiratory tract infection, and the number of courses of systemic corticosteroid therapy administered due to the exacerbation of COPD. Arg/Arg homozygotes at codon 16 required at least two courses of antibiotic therapy administered as a result of a lower respiratory tract infection significantly more frequently than carriers of other polymorphic variants of the ADRB2. Moreover, they were the only ones who required three or more courses of corticosteroid therapy due to COPD exacerbation. No significant relationships were observed between the polymorphism at codon 27 and the analysed clinical indicators of COPD severity. These data suggested that Arg/Arg homozygosity at codon 16 of the ADRB2 gene predisposes patients to a clinically more severe course of COPD.

Genetic effects on treatment response of umeclidinium/vilanterol in chronic obstructive pulmonary disease

BACKGROUND

Treatment with long-acting β2-agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) for chronic obstructive pulmonary disease (COPD) is standard, but response varies. We investigated genetic association with treatment response to umeclidinium (UMEC, a LAMA), vilanterol (VI, a LABA), and combination therapy.

METHODS

Data from 17 clinical trials (N = 6075) in patients with COPD receiving once-daily UMEC/VI (125/25mcg or 62.5/25mcg), UMEC (125 or 62.5mcg), VI (25mcg) or placebo were used. Genetic association with change from baseline in trough forced expiratory volume in 1 s (FEV1) ∼24 h post-dosing was assessed for: (i) 3 β2-adrenoceptor (ADRB2) gene variants; (ii) 298 single-nucleotide polymorphisms (SNPs) with prior evidence of associations; (iii) human leukocyte antigen (HLA) alleles and (iv) genome-wide association study (GWAS) SNPs. Other endpoints were (i) reversibility at screening; and at baseline: (ii) FEV1; (iii) forced vital capacity (FVC), and (iv) FEV1/FVC ratio. Using linear regression, the inverse normal transformed residuals were pooled together, first across treatment group, then across studies for each monotherapy, then combination therapy and finally for every treated patient.

RESULTS

Of 6075 patients, 1849 received UMEC/VI, 1390 received UMEC, 1795 received VI, and 1041 received placebo. None of the ADRB2 variants, HLA alleles or GWAS variants tested were associated with treatment response or baseline endpoints. Four SNPs in FAM13A (rs7671167, rs2869967, rs1964516, rs1903003) were significantly associated with baseline FEV1/FVC ratio (p < 3 × 10(-5)) after adjusting for multiple testing.

CONCLUSIONS

No genetic association was found with treatment response to UMEC or VI when administered as monotherapies or in combination.

Implications of Emphysema and Lung Function for the Development of Pneumonia in Patients with Chronic Obstructive Pulmonary Disease

Background

Chronic obstructive pulmonary disease (COPD) is sometimes complicated with pneumonia, but little is known about the risk factors that promote the development of pneumonia in COPD. These risk factors were evaluated in the present study.

Methods

The data of 324 patients with COPD from a prospective multi-center observational cohort with obstructive lung disease were evaluated retrospectively. To identify risk factors for the development of pneumonia in COPD, the clinical and radiological data at enrollment and the time to the first episode of pneumonia were analyzed by Cox proportional hazard analysis.

Results

The median follow-up time was 1,099 days and 28 patients (8.6%) developed pneumonia. The Cox analysis showed that post-bronchodilator forced expiratory volume in one second (FEV₁, % of predicted) and the computed tomography (CT) emphysema extent (inspiratory V950) were independent risk factors for the development of pneumonia (post-bronchodilator FEV₁: hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.94–1.00; p=0.048 and inspiratory V950: HR, 1.04; 95% CI, 1.01–1.07; p=0.01).

Conclusion

Emphysema severity measured by CT and post-bronchodilator FEV1 are important risk factors for the development of pneumonia in COPD.

Outcome of Inhaler Withdrawal in Patients Receiving Triple Therapy for COPD

Background

The purpose of this study was to document outcomes following withdrawal of a single inhaler (step-down) in chronic obstructive pulmonary disease (COPD) patients on triple therapy (long-acting muscarinic antagonist and a combination of long-acting β2-agonists and inhaled corticosteroid), which a common treatment strategy in clinical practice.

Methods

Through a retrospective observational study, COPD patients receiving triple therapy over 2 years (triple group; n=109) were compared with those who had undergone triple therapy for at least 1 year and subsequently, over 9 months, initiated inhaler withdrawal (step-down group, n=39). The index time was defined as the time of withdrawal in the stepdown group and as 1 year after the start of triple therapy in the triple group.

Results

Lung function at the index time was superior and the previous exacerbation frequency was lower in the stepdown group than in the triple group. Step-down resulted in aggravating disease symptoms, a reduced overall quality of life, decreasing exercise performance, and accelerated forced expiratory volume in 1 second (FEV₁) decline (54.7±15.7 mL/yr vs. 10.7±7.1 mL/yr, p=0.007), but there was no observed increase in the frequency of exacerbations.

Conclusion

Withdrawal of a single inhaler during triple therapy in COPD patients should be conducted with caution as it may impair the exercise capacity and quality of life while accelerating FEV₁ decline.

Pharmacogenomics of long-acting β2-agonists

INTRODUCTION

Long-acting β2-agonists are an effective class of drugs, when combined with inhaled corticosteroids, for reducing symptoms and exacerbations in patients with asthma that is not adequately controlled by inhaled corticosteroids alone. However, because this class of drugs has been associated with severe adverse events, including hospitalization and death in small numbers of patients, efforts to identify a pharmacogenetic profile for patients at risk has been diligently investigated.

AREAS COVERED

The PubMed search engine of the National Library of Medicine was used to identify English-language and non-English language articles published from 1947 to March 2015 pertinent to asthma, pharmacogenomics, and long-acting β2-agonists. Keywords and topics included: asthma, asthma control, long-acting β2-agonists, salmeterol, formoterol, pharmacogenetics, and pharmacogenomics. This strategy was also used for the Cochrane Library Database and CINAHL. Reference types were randomized controlled trials, reviews, and editorials. Additional publications were culled from reference lists. The publications were reviewed by the authors and those most relevant were used to support the topics covered in this review.

EXPERT OPINION

Children, who carry the ADRB2 Arg16Arg genotype, may be at greater risk than adults for severe adverse events. Rare ADRB2 variants appear to provide better clues for identifying the at-risk population of asthmatics.

Three-month treatment response and exacerbation in chronic obstructive pulmonary disease

The aim of this study was to investigate relationships between acute exacerbation and Forced Expiratory Volume 1 second (FEV1) improvement after treatment with combined long-acting beta-agonist (LABA) and inhaled corticosteroid (ICS) in patients with chronic obstructive pulmonary disease (COPD). A total of 137 COPD patients were classified as responders or nonresponders according to FEV1 improvement after 3 months of LABA/ICS treatment in fourteen referral hospitals in Korea. Exacerbation occurrence in these two subgroups was compared over a period of 1 yr. Eighty of the 137 COPD patients (58.4%) were classified as responders and 57 (41.6%) as nonresponders. Acute exacerbations occurred in 25 patients (31.3%) in the responder group and in 26 patients (45.6%) in the nonresponder group (P=0.086). FEV1 improvement after LABA/ICS treatment was a significant prognostic factor for fewer acute exacerbations in a multivariate Cox proportional hazard model adjusted for age, sex, FEV1, smoking history, 6 min walk distance, body mass index, exacerbation history in the previous year, and dyspnea scale.Three-month treatment response to LABA/ICS might be a prognostic factor for the occurrence of acute exacerbation in COPD patients.

Study Design and Outcomes of Korean Obstructive Lung Disease (KOLD) Cohort Study

Background

The Korean Obstructive Lung Disease (KOLD) Cohort Study is a prospective longitudinal study of patients with chronic obstructive pulmonary disease (COPD), asthma, or other unclassified obstructive lung diseases. It was designed to develop new classification models and biomarkers that predict clinically relevant outcomes for patients with obstructive lung diseases.

Methods

Patients over 18 years old who have chronic respiratory symptoms and airflow limitations or bronchial hyper-responsiveness were enrolled at 17 centers in South Korea. After a baseline visit, the subjects were followed up every 3 months for various assessments.

Results

From June 2005 to October 2013, a total of 477 subjects (433 [91%] males; 381 [80%] diagnosed with COPD) were enrolled. Analyses of the KOLD Cohort Study identified distinct phenotypes in patients with COPD, and predictors of therapeutic responses and exacerbations as well as the factors related to pulmonary hypertension in COPD. In addition, several genotypes were associated with radiological phenotypes and therapeutic responses among Korean COPD patients.

Conclusion

The KOLD Cohort Study is one of the leading long-term prospective longitudinal studies investigating heterogeneity of the COPD and is expected to provide new insights for pathogenesis and the long-term progression of COPD.

Pharmacogenetics of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex genetic disease that develops as a result of the interaction of multiple susceptibility genes and environmental factors. Major therapeutic approaches include smoking cessation, treatment with bronchodilators and corticosteroid therapy. The goal of understanding the genetic defects in patients with COPD will be not only to redefine the disease phenotypes based on the genetic information, but also to alternatively approach patients based on the understanding of COPD pathogenesis, which will lead to improved clinical outcomes. Although there is no single ideal phenotype for COPD pharmacogenetic studies, thus far, most pharmacogenetics studies have focused on the role of variants in the β2-adrenergic receptor gene on bronchodilator response. The inconclusive results yielded by these studies highlight many of the difficulties researchers face in assessing the influence of genetic variants and in translating this to clinically relevant outcomes.

Phenotyping the heterogeneity of chronic obstructive pulmonary disease

COPD (chronic obstructive pulmonary disease) is a heterogeneous disease associated with significant morbidity and mortality. Current diagnostic criteria based on the presence of fixed airflow obstruction and symptoms do not integrate the complex pathological changes occurring within lung, do not define different airway inflammatory patterns, nor do they define different physiological changes or differences in structure as can be defined by imaging. Over recent years, there has been interest in describing this heterogeneity and using this information to subgroup patients into COPD phenotypes. Most approaches to phenotyping have considered disease at a single scale and have not integrated information from different scales (e.g. organ-whole person, tissue-organ, cell-tissue and gene-cell) of disease to provide multi-dimensional phenotypes. Integration of disease biology with clinical expression is critical to improve understanding of this disease. When combined with biostatistical modelling, this information may lead to identification of new drug targets, new end points for clinical trials and targeted treatment for subgroups of COPD patients. It is hoped this will ultimately improve COPD outcomes and represent a move towards personalised medicine. In the present review, we will consider these aspects of multi-dimensional phenotyping in more detail.

ADRB2 polymorphisms and budesonide/formoterol responses in COPD

BACKGROUND

Effects of β(2)-adrenergic receptor gene (ADRB2) polymorphism on therapeutic responses to long-acting β(2)-adrenergic agonists have not been evaluated in long-term COPD trials. We aimed to investigate the effects of the ADRB2 Gly16Arg polymorphism on response to formoterol alone or in combination with the inhaled corticosteroid budesonide in patients with COPD.

METHODS

Patients ≥ 40 years of age with moderate to very severe COPD from the 12-month trial I (NCT00206167) or the 6-month trial II (NCT00206154) were randomly assigned to bid budesonide/formoterol pressurized metered-dose inhaler (pMDI) 320/9 μg or 160/9 μg, budesonide pMDI 320 μg + formoterol dry powder inhaler 9 μg (trial II), budesonide pMDI 320 μg (trial II), formoterol dry powder inhaler 9 μg, or placebo. The effect of Gly16Arg on predose FEV(1) and 1-h postdose FEV(1), exacerbations, diary variables, and adverse events were analyzed.

RESULTS

No significant interaction between genotype and treatment response was observed for predose (P ≥ .197) or postdose FEV(1) (P ≥ .125) in either pharmacogenetic study (n = 2,866). The number of COPD exacerbations per patient-treatment year was low and similar across genotypes for the active treatment groups (both studies). Percentages of patients with adverse events were similar across Gly16Arg genotype groups for each treatment.

CONCLUSION

Therapeutic response and tolerability to long-term treatment with formoterol alone or in combination with budesonide was not modified by ADRB2 Gly16Arg genotype in two large independent pharmacogenetic studies in patients with moderate to very severe COPD.

A pharmacogenetic study of ADRB2 polymorphisms and indacaterol response in COPD patients

Genetic variation in the ADRB2 gene has been hypothesized to have a role in differential response to beta-agonist (BA) therapy in asthma. However, study results have been inconsistent and the issue remains controversial. Furthermore, the impact of ADRB2 genetic variation on BA response in chronic obstructive pulmonary disease (COPD) patients has not been thoroughly studied. We carried out a large pharmacogenetic analysis testing for an association between common ADRB2 polymorphisms and indacaterol response in COPD patients. A total of 648 indacaterol-treated patients enrolled in two large randomized phase III studies were genotyped for the most commonly studied polymorphisms in the ADRB2 gene: Gly16Arg, Gln27Glu, Thr164Ile, and a variant in the 5' untranslated region (rs1042711). Our analysis showed little evidence for the association between these ADRB2 variants and indacaterol response, suggesting that ADRB2 genetic variation is unlikely to have a major role in differential response to indacaterol treatment in COPD patients.

Response patterns to bronchodilator and quantitative computed tomography in chronic obstructive pulmonary disease

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) show different spirometric response patterns to bronchodilator, such that some patients show improvement principally in expiratory flow (forced expiratory volume in 1 s; FEV(1)), whereas others respond by improvement of lung volume (forced vital capacity; FVC). The mechanisms of these different response patterns to bronchodilator remain unclear. We investigated the associations between bronchodilator responsiveness and quantitative computed tomography (CT) indices in patients with COPD.

METHODS

Data on a total of 101 patients with stable COPD were retrospectively analysed. Volume and flow responses to bronchodilator were assessed by FVC and FEV(1) changes before and after inhalation of salbutamol (400 μg). Volumetric CT was performed to quantify emphysema, air trapping and large airway thickness. Emphysema was assessed by the volume fraction of the lung under -950 Hounsfield units (HU; V(950)) at full inspiration and air trapping by the ratio of mean lung density (MLD) at full expiration and inspiration. Airway wall thickness and wall area percentage (WA%; defined as wall area/[wall area + lumen area] × 100), were measured near the origin of right apical and left apico-posterior bronchus.

RESULTS

Among quantitative CT indices, the CT emphysema index (V(950 insp)) showed a significant negative correlation with postbronchodilator FEV(1) change (R = -0·213, P = 0·004), and the CT air-trapping index correlated positively with postbronchodilator FVC change(R = 0·286, P≤0·001). Multiple linear regression analysis showed that CT emphysema index had independent association with postbronchodilator FEV(1) change and CT air-trapping index with postbronchodilator FVC change.

CONCLUSION

The degrees of emphysema and air trapping may contribute to the different response patterns to bronchodilator in patients with COPD.

Predictors of pulmonary function response to treatment with salmeterol/fluticasone in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease and responses to therapies are highly variable. The aim of this study was to identify the predictors of pulmonary function response to 3 months of treatment with salmeterol/fluticasone in patients with COPD. A total of 127 patients with stable COPD from the Korean Obstructive Lung Disease (KOLD) Cohort, which were prospectively recruited from June 2005 to September 2009, were analyzed retrospectively. The prediction models for the FEV(1), FVC and IC/TLC changes after 3 months of treatment with salmeterol/fluticasone were constructed by using multiple, stepwise, linear regression analysis. The prediction model for the FEV(1) change after 3 months of treatment included wheezing history, pre-bronchodilator FEV(1), post-bronchodilator FEV(1) change and emphysema extent on CT (R = 0.578). The prediction models for the FVC change after 3 months of treatment included pre-bronchodilator FVC, post-bronchodilator FVC change (R = 0.533), and those of IC/ TLC change after 3 months of treatment did pre-bronchodilator IC/TLC and post-bronchodilator FEV(1) change (R = 0.401). Wheezing history, pre-bronchodilator pulmonary function, bronchodilator responsiveness, and emphysema extent may be used for predicting the pulmonary function response to 3 months of treatment with salmeterol/fluticasone in patients with COPD.

Probable role of Beta 2-adrenergic receptor gene haplotype in toluene diisocyanate-induced asthma

PURPOSE

A genetic polymorphism of the beta 2-adrenergic receptor is a major factor associated with the asthmatic phenotype. The association of this polymorphism with toluene diisocyanate (TDI)-induced asthma has not been investigated. We examined 103 TDI-induced asthma patients (TDI-OA), 60 asymptomatic exposed controls (AEC), and 263 unexposed healthy controls (NC) in order to identify beta 2-adrenergic receptor gene (ADRB2) polymorphisms and the possible association with TDI-induced asthma.

METHODS

Single nucleotide polymorphisms (SNPs) of ADRB2 were genotyped by direct sequencing. Serum-specific IgE and IgG levels were measured using an enzyme-linked immunosorbent assay. Phenotypes and clinical patient parameters were compared.

RESULTS

SNPs were identified (-47 T>C, -20 T>C, Arg16Gly A>G, Gln27Glu C>G, Leu134Leu G>A, Arg175Arg C>A) during ADRB2 screening (from -231 to 793 bp). No significant differences in allelic and genotypic frequencies were noted for any of the six ADRB2 SNPs. The Arg16Gly A>G, Leu134Leu G>A, and Arg175Arg C>A SNPs and haplotype 1 [TTACGC] were significantly associated with specific IgE antibodies to the TDI-human serum albumin (HSA) conjugate in TDI-exposed subjects (P<0.05). Exposed workers with the ADRB2 ht1/ht1 homozygote had a significantly higher TDI-HSA conjugate-specific IgE sensitization rate than did those with the null ht1 haplotype (odds ratio, 15.40; 95% confidence interval, 1.81-131.06).

CONCLUSIONS

ADRB2 polymorphisms may affect IgE-specific sensitization to TDI-HSA conjugate in TDI-exposed workers.

Pharmacogenetics of chronic obstructive pulmonary disease: challenges and opportunities

Similar to other common chronic diseases, chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder with multiple disease subtypes. Candidate gene studies have found genetic associations for COPD-related phenotypes that may be relevant for pharmacogenetics studies, including lung function decline and COPD exacerbations. However, few COPD pharmacogenetics studies have been completed. Most studies have focused on the role of variants in the beta(2)-adrenergic receptor gene on bronchodilator response, but the findings have been inconclusive. Candidate gene studies highlight the concept that genes for COPD susceptibility may also be relevant in COPD pharmacogenetics. Currently, there are no clinical applications of pharmacogenetics to COPD therapy, but the use of pharmacogenetics to determine initial smoking cessation therapy may be closer to clinical application.