Association between beta-adrenoceptor gene polymorphisms and relative response to beta 2-agonists and anticholinergic drugs in Japanese asthmatic patients

ADRB2 Gene Polymorphisms and Salbutamol Responsiveness in Serbian Children with Asthma

Inhaled β2 adrenergic receptor (β2-AR) agonists are the mainstay of asthma therapy. The β2-AR protein is encoded by the ADRB2 gene and variants within this gene can have significant consequences for modulating the response to asthma therapy. This cross-sectional study performed at the University Children’s Hospital in Belgrade, included 54 children with asthma. The subjects were genotyped for ADRB2 +46A>G (Arg16Gly, rs1042713) and +79C>G (Gln27Glu, rs 1042714) polymorphisms and the association with asthma severity and response to inhaled salbutamol was examined. In Serbian asthmatic children, allele +46A was detected with a frequency of 41.7% and allele +79G was detected with a frequency of 23.1%. Allele +46G was found to be associated with a better response to inhaled salbutamol (p <0.05) and with mild form of asthma (p <0.05). Polymorphism ADRB2 +46A>G may be a determinant of asthma severity and response to salbutamol in children with asthma. We did not find any association of +79C>G polymorphisms with the asthma severity and bronchodilator response to inhaled salbutamol. The results of this study can be potentially useful for personalization of asthma treatment.

B2 adrenergic receptor gene polymorphism effect on childhood asthma severity and response to treatment

BackgroundAlterations of B2 adrenergic receptor (β₂AR) can modulate the severity of asthma and the response to treatment. Therefore, we aimed to evaluate β₂AR gene polymorphism at codons 16 and 27 and their effect on asthma severity and response to treatment in asthmatic children.MethodsCase-control study was conducted on 156 children; 104 of them had bronchial asthma and 52 were healthy children (control group). Subjects of the study underwent history taking, clinical examination, pulmonary function tests, serum IgE level assessment, and identification of β₂AR-16 A46G and β₂AR-27 C79G polymorphism using PCR-Restriction Fragment length polymorphisms (RFLP) test.ResultsThere was a higher frequency of Arg-Gly genotypes (odds ratio (OR)=6.57; confidence interval (CI): 2.42-18.81, P<0.001) and lower frequency of Arg-Arg (OR=4.7; CI: 2.05-10.95, P<0.001) among asthmatic children compared with that among controls at codon 16. The presence or absence of Gly16 or Glu27 either homozygous or heterozygous for both correlated with the grade of asthma severity. The presence of heterozygous Arg-Gly and Gln-Glu gives a better response to drug therapy than the presence of Gly-Gly and Glu-Glu genotypes at codons 16 and 27.ConclusionPolymorphism of β₂AR at codons 16 and 27 correlates with asthma severity and response to treatment in asthmatic children.

Responsiveness to bronchodilator procaterol in COPD as assessed by forced oscillation technique

The aim of this retrospective study was to assess responses to a bronchodilator by forced oscillation technique (FOT) and to relate the results of respiratory impedance (Zrs) to spirometric parameters in patients with chronic obstructive pulmonary disease (COPD). Zrs was measured as a function of frequency from 4 to 36Hz before and after inhalation of procaterol, a short-acting β₂-agonist (n=60). Respiratory resistance (Rrs) and reactance (Xrs) were significantly frequency-dependent, and inspiratory and expiratory phases were different both before and after procaterol inhalation. The Rrs at 4Hz and Xrs at 4-20Hz during a whole breath were significantly improved after procaterol inhalation. The response to procaterol inhalation varied among patients, and changes in Xrs at 4Hz significantly correlated with% change in forced expiratory volume in one second and changes in forced vital capacity. Taken together, Zrs, and specifically Xrs parameters, are sensitive to acute physiological responses to a bronchodilator in COPD.

Muscarinic antagonists in early stage clinical development for the treatment of asthma

INTRODUCTION

Parasympathetic neurons utilize the neurotransmitter acetylcholine to modulate and constrict airway smooth muscles at the muscarinic acetylcholine receptor. Inhaled agents that antagonize the muscarinic (M) acetylcholine receptor, particularly airway M3 receptors, have increasing data supporting use in persistent asthma. Areas covered: Use of inhaled long-acting muscarinic antagonists (LAMA) in asthma is explored. The LAMA tiotropium is approved for maintenance in symptomatic asthma patients despite the use of inhaled corticosteroids (ICS), leukotriene receptor antagonists (LTRA) and/or long-acting beta₂ agonists (LABA). LAMA agents currently approved for chronic obstructive pulmonary disease (COPD) include tiotropium, glycopyrrolate/glycopyrronium, umeclidinium and aclidinium. These agents are reviewed for their pharmacological differences and clinical trials in asthma. Expert opinion: Current guidelines place inhaled LAMAs as adjunctive maintenance therapy in symptomatic asthma not controlled by an ICS and/or a LTRA. LAMA agents will play an increasing role in moderate to severe symptomatic asthma patients. Additional LAMA agents are likely to seek a maintenance indication perhaps as a combined inhaler with an ICS or with an ICS and a LABA. These fixed-dose combination inhalers are being tested in COPD and asthma patients. Once-a-day dosing of inhaled LAMA agents in severe asthma patients will likely become the future standard.

Asthma: Gln27Glu and Arg16Gly polymorphisms of the beta2-adrenergic receptor gene as risk factors

Background

Asthma is caused by both environmental and genetic factors. The ADRB2 gene, which encodes the beta 2-adrenergic receptor, is one of the most extensively studied genes with respect to asthma prevalence and severity. The Arg16Gly (+46A > G) and Gln27Glu (+79C > G) polymorphisms in the ADRB2 gene cause changes in the amino acids flanking the receptor ligand site, altering the response to bronchodilators and the risk of asthma through complex pathways. The ADRB2 polymorphisms affect beta-adrenergic bronchodilator action and are a tool to identify at-risk populations.

Objective

To determine the frequency of these two polymorphisms in allergic asthma patients and healthy subjects and to correlate these data with the occurrence and severity of asthma.

Methods

Eighty-eight allergic asthma patients and 141 healthy subjects were included in this study. The ADRB2 polymorphisms were analyzed using the amplification-refractory mutation system – polymerase chain reaction (ARMS-PCR) technique. The statistical analysis was performed with the SPSS 21.0 software using the Fisher’s Exact and χ² tests.

Results

The ADRB2 polymorphisms were associated with asthma occurrence. The Arg16Arg, Gln27Gln and Gln27Glu genotypes were risk factors; the odds ratios were 6.782 (CI = 3.07 to 16.03), 2.120 (CI = 1.22 to 3.71) and 8.096 (CI = 3.90 to 17.77), respectively. For the Gly16Gly and Glu27Glu genotypes, the odds ratios were 0.312 (CI = 0.17 to 0.56) and 0.084 (CI = 0.04 to 0.17), respectively. The haplotype analysis showed that there were associations between the following groups: Arg16Arg-Gln27Gln (OR = 5.108, CI = 1.82 to 16.37), Gly16Gly-Glu27Glu (OR = 2.816, CI = 1.25 to 6.54), Arg16Gly-Gln27Glu (OR = 0.048, CI = 0.01 to 0.14) and Gly16Gly-Gln27Glu (OR = 0.1036, CI = 0.02 to 0.39). The polymorphism Gln27Glu was associated with asthma severity, as the Gln27Gln genotype was a risk factor for severe asthma (OR = 2.798, CI = 1.099 to 6.674) and the Gln27Glu genotype was a protective factor for mild (OR = 3.063, CI = 1.037 to 9.041) and severe (OR = 0.182, CI = 0.048 to 0.691) asthma.

Conclusions

The Arg16Gly and Gln27Glu polymorphisms in the ADRB2 gene are associated with asthma presence and severity.

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.

The role of vitamin D in asthma

Vitamin D metabolites are important immune-modulatory hormones and are able to suppress Th2-mediated allergic airway disease. Some genetic factors that may contribute to asthma are regulated by vitamin D, such as vitamin D receptor (VDR), human leukocyte antigen genes (HLA), human Toll-like receptors (TLR), matrix metalloproteinases (MMPs), a disintegrin and metalloprotein-33 (ADAM-33), and poly(ADP-ribosyl) polymerase- 1 (PARP-1). Vitamin D has also been implicated in asthma through its effects on the obesity, bacillus Calmettee Guérin (BCG) vaccination and high vitamin D level, vitamin D supplement, checkpoint protein kinase 1 (Chk1), plasminogen activator inhibitor-1 (PAI-1) and gamma delta T cells (gdT). Vitamin D plays a role in asthma and exerts its action through either genomic and/or non-genomic ways.

Relationship between polymorphisms in the 5' leader cistron, positions 16 and 27 of the adrenergic β2 receptor gene and asthma in a Han population from southwest China

BACKGROUND AND OBJECTIVE

Adrenergic β2 receptors (ADRB2) play an important role in regulating pulmonary function. Many previous studies have investigated possible associations between polymorphisms in the ADRB2 gene and asthma, but have yielded conflicting results. Furthermore, little is known regarding the possible role of the Arg19Cys polymorphism in susceptibility to asthma among Chinese.

METHODS

This case-control association study involved 238 patients with asthma and 265 healthy subjects from a Han population in southwest China. For all subjects, the 5' leader cistron Arg19Cys, Arg16Gly and Gln27Glu polymorphisms in the ADRB2 gene were characterized by direct sequencing. Genotype, allele and haplotype frequencies were determined. In addition, to evaluate the association between the ADRB2 polymorphisms and lung function, bronchodilator response to inhaled β2 agonists (400 µg of albuterol) was assessed in the asthmatic patients.

RESULTS

There were no significant differences in genotype or allele frequencies for the three ADRB2 polymorphisms between the two cohorts. The Arg19/Arg16/Gln27 haplotype was more frequent among asthmatic patients than control subjects (odds ratio 2.24, 95% confidence interval (CI): 1.05-4.73, P=0.04). Moreover, the Arg19/Cys19 genotype was associated with a lower FEV₁% (mean difference -4.5, 95% CI: -12.5 to 3.6, P=0.02) and FEV₁/FVC (mean difference 8.9, 95% CI: 8.5-9.4, P=0.01). The bronchodilator response to albuterol was also marginally lower in individuals who were homozygous for the Arg19 genotype (mean difference 4.2, 95% CI: 3.7-4.8, P=0.03).

CONCLUSIONS

The Arg19/Cys19 genotype was an independent risk factor for lower FEV₁% and FEV₁/FVC. Asthmatic patients with the Arg19/Arg19 genotype showed decreased responsiveness to albuterol. Furthermore, the Arg19/Arg16/Gln27 haplotype may contribute to increased susceptibility to asthma in the Chinese population.

Pharmacogenetics of β2-agonists

Short-acting β2-agonists (SABAs) and long-acting β2-agonists (LABAs) are both important for treatment of asthma and chronic obstructive pulmonary disease (COPD) because of their bronchodilator and bronchoprotective effects. However, the use of these agonists, at least for asthma, has generated some controversy because of their association with increased mortality. Pharmacogenetics is the study of genetically determined variation in response to medications, which might prove useful for target therapies in highly responsive patients, especially for more expensive therapies or those with increased risk of side effects. Variation in response to both SABAs and LABAs has been observed in patients with polymorphisms in the β2 adrenoceptor gene (ADRB2). This review summarizes results from various studies on the possible relationship between ADRB2 polymorphisms and the bronchodilator or bronchoprotective effects of inhaled β2-agonists. By assessing the ADRB2 genotype, the hope is that it will be possible to predict the responsiveness to chronic administration of β2-agonists. Genetic testing, however, is of limited usefulness at this stage for ADRB2 because the common variants identified thus far account for only a small proportion of the variation observed for given responses. Carefully performed and adequately powered clinical trials continue to be important for achieving the goal of pharmacogenetic approaches to therapy.

Arg16Gly β2-adrenergic receptor gene polymorphism in Japanese patients with aspirin-exacerbated respiratory disease

BACKGROUND

There has been no report that investigated β(2)-adrenergic receptor (ADRB2) gene polymorphism in patients with aspirin-exacerbated respiratory disease (AERD).

METHODS

DNA in the specimens in three groups of study subjects classified patients with AERD, patients with aspirin-tolerant asthma (ATA) and normal controls was extracted, and the target DNA sequence of the ADRB2 was amplified using a set of primers to generate an amplicon of 219 bp in length. Allelic discrimination assay for single nucleotide polymorphisms relating to the ADRB2 gene expression was carried out by using a previously described single nucleotide polymorphism detective system, sequence-specific thermal-elution chromatography.

RESULTS

The frequency of the Gly variant allele in patients with AERD was significantly lower than that in patients with ATA (p = 0.007), and the odds ratio (OR) of AERD to ATA associated with wild-type ArgArg homozygote was 3.300. Frequencies of wild-type ArgArg homozygote are significantly higher than those of variant-type ArgGly/GlyGly genotype in patients with AERD compared with those with ATA (p < 0.001, OR = 3.153). In patients with AERD, frequencies of wild-type ArgArg homozygote in both female and male patients are significantly higher than those of variant-type ArgGly/GlyGly genotype in male patients compared with those with ATA (p < 0.001, OR = 5.128 and p = 0.007, OR = 4.367, respectively). Also, in patients with AERD, frequencies of wild-type ArgArg homozygote in female patients are significantly higher than those of variant-type ArgGly/GlyGly genotype in female patients compared with those with ATA (p = 0.002, OR = 2.825).

CONCLUSIONS

We were the first to analyze Arg16Gly ADRB2 gene polymorphism in Japanese patients with AERD, and showed that Arg16Gly ADRB2 gene polymorphism in Japanese patients with AERD is different from that in the patients with ATA.