Use of regularly scheduled albuterol treatment in asthma: genotype-stratified, randomised, placebo-controlled cross-over trial

The irreversible component of persistent asthma

Irreversible airflow obstruction or limitation occurs in some patients with asthma, can develop early in life, and becomes more common as asthma becomes more severe. Efforts to understand irreversible airflow obstruction or limitation have been hampered by the lack of a standardized definition of the phenotype and by the lack of appropriate research models. Unfortunately, it appears that currently available asthma treatments do not prevent this important asthma complication. Herein, the evidence of an irreversible component of asthma, its underlying pathology, and the limitations of current asthma treatments are reviewed.

Effect of beta2-adrenergic receptor polymorphism on response to longacting beta2 agonist in asthma (LARGE trial): a genotype-stratified, randomised, placebo-controlled, crossover trial

BACKGROUND

Some studies suggest that patients with asthma who are homozygous for arginine at the 16th amino acid position of the beta2-adrenergic receptor (B16 Arg/Arg) benefit less from treatment with longacting beta2 agonists and inhaled corticosteroids than do those homozygous for glycine (B16 Gly/Gly). We investigated whether there is a genotype-specific response to treatment with a longacting beta2 agonist in combination with inhaled corticosteroid.

METHODS

In this multicentre, randomised, double-blind, placebo-controlled trial, adult patients with moderate asthma were enrolled in pairs matched for forced expiratory volume in 1 s and ethnic origin, according to whether they had the B16 Arg/Arg (n=42) or B16 Gly/Gly (n=45) genotype. Individuals in a matched pair were randomly assigned by computer-generated randomisation sequence to receive inhaled longacting beta2 agonist (salmeterol 50 microg twice a day) or placebo given in a double-blind, crossover design for two 18-week periods. Open-label inhaled corticosteroid (hydrofluoroalkane beclometasone 240 microg twice a day) was given to all participants during the treatment periods. The primary endpoint was morning peak expiratory flow (PEF). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00200967.

FINDINGS

After 18 weeks of treatment, mean morning PEF in Arg/Arg participants was 21.4 L/min (95% CI 11.8-31.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). In Gly/Gly participants, morning PEF was 21.5 L/min (11.0-32.1) higher when participants were assigned to receive salmeterol than when assigned to receive placebo (p<0.0001). The improvement in PEF did not differ between genotypes (difference [Arg/Arg-Gly/Gly] -0.1, -14.4 to 14.2; p=0.99). In Gly/Gly participants, methacholine PC20 (20% reduction in forced expiratory volume in 1 s; a prespecified secondary outcome) was 2.4 times higher when participants were assigned to salmeterol than when assigned to placebo (p<0.0001). Responsiveness to methacholine did not differ between salmeterol and placebo in Arg/Arg participants (p=0.87). The 2.5 times higher genotype-specific difference in responsiveness to methacholine was significant (1.32 doubling dose difference between genotypes, 0.43-2.21, p=0.0038). Seven Arg/Arg participants (placebo, n=5; salmeterol, n=2) and six Gly/Gly participants (placebo, n=3; salmeterol, n=3) had an asthma exacerbation. Five serious adverse events were reported, one each during the pre-match and run-in phases on open-label inhaled corticosteroid, two during double-blind treatment with salmeterol/inhaled corticosteroid, and one during double-blind treatment with placebo/inhaled corticosteroid. None of the serious events was asthma-related or related to study drugs or procedures.

INTERPRETATION

In asthma patients with B16 Arg/Arg and B16 Gly/Gly genotypes, combination treatment with salmeterol and inhaled corticosteroid improved airway function when compared with inhaled corticosteroid therapy alone. These findings suggest that patients should continue to be treated with longacting beta2 agonists plus moderate-dose inhaled corticosteroids irrespective of B16 genotype. Further investigation is needed to establish the importance of the genotype-specific difference in responsiveness to methacholine.

FUNDING

National Institutes of Health.

Beta2-receptor polymorphisms in patients receiving salmeterol with or without fluticasone propionate

RATIONALE

Retrospective pharmacogenetic studies have questioned whether patients with asthma who are arginine homozygous at the beta(2-)adrenergic receptor (position 16) should use long-acting beta-agonists.

OBJECTIVES

To examine whether the response to salmeterol alone or in combination with an inhaled corticosteroid is influenced by beta- receptor polymorphisms.

METHODS

Subjects using only as-needed albuterol were screened and completed two sequential open-label run-in periods (8 wk on as-needed albuterol; 8 wk on as-needed ipratropium). Five hundred forty-four subjects were randomized by Arg16Gly genotype to salmeterol alone or with fluticasone propionate for 16 weeks. Change from baseline in morning peak expiratory flow was the primary endpoint.

MEASUREMENTS AND MAIN RESULTS

Lung function responses were sustained over treatment and no statistically significant changes from baseline between genotypes within treatments were observed. Overall mean changes in morning peak flow for salmeterol with fluticasone propionate were 32.6 L/min (Arg/Arg vs. Gly/Gly, 95% confidence interval [CI], -6.3, 22.1), 25.9 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -7.1, 21.3), and 24.9 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -13.0, 14.6), and for salmeterol alone were 19.4 L/min (Arg/Arg vs. Gly/Gly, 95% CI, -1.7, 21.4), 24.6 L/min (Arg/Arg vs. Arg/Gly, 95% CI, -13.0, 10.6), and 12.4 L/min (Arg/Gly vs. Gly/Gly, 95% CI, -0.2, 22.3) for Arg/Arg, Arg/Gly, and Gly/Gly genotypes, respectively. Other measures of asthma control showed similar responses.

CONCLUSIONS

The results showed no evidence of a pharmacogenetic effect of beta-receptor variation on salmeterol response. Clinical trial registered with www.clinicaltrials.gov (NCT 00102882).

Exercise-induced bronchoconstriction in asthmatic children: a comparative systematic review of the available treatment options

The aim of this article is to critically review the efficacy and safety data from randomized controlled trials (RCTs) using inhaled corticosteroids (ICSs), long- or short-acting beta(2)-adrenoceptor agonists (LABAs, SABAs), parasympatholytics and oral leukotriene receptor antagonists in the management of exercise-induced bronchoconstriction (EIB) in children with persistent asthma (EIA). The studies with sufficient information on patient characteristics and outcomes were chosen using a MEDLINE search. Results from the individual searches were combined and repeated. Studies were also found by reviewing the reference lists of the articles not included in this review. Studies focusing solely on individuals with asthma and other allergic co-morbidities (i.e. a degree of bronchial reversibility) were considered in this review. To make the paper evidence-based, the design and the quality of different studies were assessed employing the Sign criteria (evidence level [EL] and grades of recommendation [GR]). No additional statistical analyses were performed. Most of studies included paediatric patients with underlying EIA. We need to distinguish children with recurrent asthma symptoms in whom EIB is also present (patients with EIA) from asthmatic subjects whose symptoms appear only as a result of exercise (patients with EIB). Further controller treatment is indicated in patients with EIA and further reliever treatment in patients with EIB. ICSs are the first-choice controller drugs for EIA in children with persistent asthma (Sign grade of recommendation [GR]:A). In children with EIA without complete control with ICSs, SABAs (GR:A), leukotriene receptor antagonists (LTRAs) [GR:A] or LABAs (GR:A) may be added to gain control. Treatment with relievers such as SABAs (GR:A), parasympatholytics (GR:B) or, eventually, LABAs (GR:A), administered 10-15 minutes before exercise is the most preferable method of preventing EIB symptoms in children; however, not as monotherapy in children with EIA. The disadvantages and controversy relating to inhaled beta(2)-adrenoceptor agonist use lie in the development of tolerance to their effect when they are used on a regular basis, and the possibility of a resulting underuse of ICSs in patients with EIA. Researchers and guidelines recommend that if any patient requires treatment with a beta(2)-adrenoceptor agonist more than twice weekly, a low dose of ICSs should be administered. Inhaled parasympatholytics may be effective as preventive relievers in some children with EIB or EIA, especially among those with increased vagal activity. LTRAs have a well balanced efficacy-safety profile in preventing the occurrence of EIB symptoms in children. Compared with LABAs, LTRAs produce persistent attenuation of EIB and possess an additional effect with rescue SABA therapy in persistent asthmatic patients with EIA. A disadvantage of LTRAs is a non-response phenomenon. There are still insufficient data on the efficacy-safety profiles of ICS/LABA combination drugs in the treatment of EIA in children to recommend this treatment without caution. Safety profiles of inhaled SABAs, anticholinergics and montelukast in approved dosages seem sufficient enough to recommend use of these drugs in the prevention of EIB symptoms in children. Many researchers agree that treatment of EIA in children should always be individualized.

beta2-Adrenergic receptor gene polymorphism is associated with mortality in septic shock

RATIONALE

The CysGlyGln haplotype of the beta(2)-adrenergic receptor gene (ADRB2) is functional and associated with altered responses to adrenergic agonists in patients with asthma. Whether this functional haplotype alters outcome in patients receiving adrenergic agonists in septic shock is unknown.

OBJECTIVES

To determine whether genetic variation of ADRB2 influences outcome in septic shock.

METHODS

Two cohorts of patients with septic shock were studied: a single center (St. Paul's Hospital [SPH]) cohort (n = 589) and the Vasopressin and Septic Shock Trial (VASST) cohort (n = 616). The A allele of the rs1042717 G/A polymorphism is in complete linkage disequilibrium with the CysGlyGln haplotype of ADRB2; therefore, rs1042717 was genotyped. Modulation by norepinephrine and salbutamol of IL-6 production by stimulated in vitro lymphoblastoid cells was measured by genotype.

MEASUREMENTS AND MAIN RESULTS

Patients who had the AA genotype of rs1042717 displayed increased 28-day mortality in SPH (adjusted hazard ratio, 2.23; 95% confidence interval, 1.33-3.72; P = 0.0022), and this result was replicated in VASST (adjusted hazard ratio 2.82; 95% confidence interval, 1.56-5.09; P = 0.0006). This genotypic effect was eliminated in patients treated with acute low-dose corticosteroids. In all patients, the AA genotype was associated with more organ dysfunction. Patients with the AA genotype had a higher heart rate (SPH; P < 0.05; VASST; P < 0.05) and required a higher norepinephrine dose over Days 1 through 3 (VASST; P < 0.05). The AA genotype was associated with decreased norepinephrine and salbutamol inhibition of IL-6 production by stimulated lymphoblastoid cells in vitro (P < 0.05).

CONCLUSIONS

The AA genotype of ADRB2 rs1042717, identifying homozygotes for the CysGlyGln haplotype, was associated with increased mortality and more organ dysfunction in septic shock.

Genetic predictors of response to therapy in childhood asthma

Asthma is a common chronic condition in children, where the response to treatment can be heterogeneous within a population. Genetic variations may partly explain the inconsistent response to asthma treatment between individuals. There is a relatively small but consistent body of literature linking genetic variations to improved response to different classes of asthma treatment, including short- and long-acting beta-agonists, corticosteroids, and leukotriene modifiers. In most cases, the advantage conferred by a single genetic mutation for treatment response is relatively small; the Arg16Gly single nucleotide polymorphism of the beta2-adrenoceptor is the exception to this rule and is associated with a marked difference in response to short-acting beta-agonists. Pharmacogenetic studies have only recently been undertaken in asthmatic individuals, and much more work is required before clinical applications arise. Future genome-wide association (GWA) studies and randomized controlled trials in genetically susceptible populations will determine whether asthma treatment can be tailored to an individual based on their DNA. The aim of the present paper is to review pharmacogenetic studies concerning asthma medications, with a primary focus on studies involving children.

Prevalence of beta-2 adrenergic receptor (beta 2 AR) polymorphisms and its influence on a model used to assess endothelial function using pulse wave analysis (PWA)

BACKGROUND

Pulse wave analysis (PWA) combined with beta(2)-agonist challenge has recently been used to assess endothelial function. beta-2 adrenergic receptor (beta(2)AR) polymorphisms may affect response to beta(2)-agonist. We determined whether beta(2)AR polymorphisms influence endothelial response in our model using PWA and salbutamol.

METHODS

388 healthy Malay subjects (177 males, 211 females) were genotyped for 5 functionally important single nucleotide polymorphisms (SNPs) of beta(2)AR; 298 subjects proceeded with assessment of endothelial function. The parameter augmentation index (AIx) was recorded non-invasively using SphygmoCor. Recording of AIx at baseline was followed by administration of 500 microg sublingual glyceryl trinitrate (GTN). AIx recordings were repeated at 3, 5, 10, 15 and 20 min post-GTN. Subjects then inhaled 400 microg of salbutamol before AIx recordings at 5 min intervals up to 20 min. Maximum changes in AIx after GTN and salbutamol represented endothelium independent and endothelium dependent vasodilatation (EDV) respectively.

RESULTS

Allele frequencies of mutated Gly16, Glu27, Ile164, -20C and -47C were 47%, 6.8%, 0%, 30% and 9.3% respectively. No significant differences in EDV were noted between genotype groups of each studied SNPs.

CONCLUSIONS

Assessment of endothelial function using PWA and salbutamol was not influenced by beta(2)AR polymorphisms.

Genetics terminology for respiratory physicians

Genes affect our susceptibility to almost all diseases, from the rare single gene disorders such as cystic fibrosis to common multifactorial disorders such as asthma. They also influence our response to specific therapies. Scientific advances in genetics, starting with projects such as the mapping of the human genome [International Human Genome Sequencing Consortium. Finishing the euchromatic sequence of the human genome. Nature 2004; 431: 931-945] are likely to improve healthcare in the coming decades. Internationally, government initiatives have been established to address strategies to implement these changes [NHS Genetics White Paper. "Our Inheritance - Our Future": Realising the potential of Genetics in the NHS. UK: Department of Health 2003; Family Health History Initiative. National Human Genome Research Institute and Office of Surgeon General, Department of Health and Human Services. 2004]. A knowledge of basic genetic principles and familiarity with genetic 'jargon' associated with new technologies will be important for those practicing in this era of 'genomic medicine' [Collins FS, Green ED, Guttmacher AE, Guyer MS. A vision for the future of genomics research. Nature 2003; 422; April 24; 835-847]. The aim of this article is to review genetic terminology using examples from paediatric respiratory medicine.

The pharmacogenetics of asthma treatment

The treatment response to each of the three major classes of asthma medications-beta agonists, leukotriene modifiers, and inhaled corticosteroids-demonstrates substantial interindividual variability. Evidence indicates that this variability is mediated, at least in part, by genetic factors. Pharmacogenetics is the study of the role of heritable factors in the response to pharmacologic therapy. The goal of pharmacogenetics is "predictive medicine," whereby a genetic profile, combined with clinical characteristics, can be used to predict response to medications a priori, allowing for maximal therapeutic response while minimizing side effects. In this review, we discuss the rationale behind conducting asthma pharmacogenetics studies, provide an overview of asthma pharmacogenetic phenotypes, and detail the most important results of asthma pharmacogenetics studies conducted to date. Although no specific predictive tests have been developed thus far, the existing studies serve as strong proof of concept of the applicability of pharmacogenetics in the future management of asthma.

Pharmacotherapy of asthma: regular treatment or on demand?

Some studies have raised the question of the need for chronic controller therapy in mild persistent asthma as suggested by international guidelines. Although the Improving Asthma Control (IMPACT) and Beclomethasone plus Salbutamol (BEST) studies suggest that on-demand therapy in some patients with mild persistent asthma achieves a similar degree of asthma control based on symptoms and functional outcomes, the IMPACT study indicates that regular and on-demand therapy is not equivalent for controlling airway inflammation. Persistent airway inflammation might lead to airway remodelling with onset or worsening of symptoms, deterioration in lung function, and reduced response to pharmacological therapy. However, the relationships between chronic airway inflammation and airway remodelling need to be clarified. Choosing the 'right' pharmacological strategy (regular versus on-demand treatment) for asthma control is currently difficult due to the fact that (1) inflammatory outcome measures were not generally incorporated into asthma clinical trials; (2) the relationships between chronic airway inflammation and airway remodelling are largely unknown; (3) current clinical asthma trials that are generally based on symptomatic and functional outcome measures are too short to assess the impact of regular anti-inflammatory therapy on natural history of asthma; (4) asthma is an heterogeneous disease and different phenotypes of asthma patients likely requiring a different therapeutic approach can be identified, even in the same class of asthma severity. Guidelines for asthma management are valuable tools, although they are necessarily based on a strategy directed to the best outcome in a group of patients. Asthma phenotyping is becoming central for asthma management. The issue of regular versus on-demand treatment of intermittent and mild persistent asthma would be better addressed if considered within an individualized approach to asthma management and assessment. Identification of clinical, functional, morphological and biochemical phenotypes of patients with asthma and its clinical implications is likely to lead to a tailored, individualized, pharmacological therapy and asthma management.

Asthma therapies revisited: what have we learned?

Asthma is a heterogenous disorder related to numerous biologic, immunologic, and physiologic components that generate multiple clinical phenotypes. Further, genetic and environmental factors interact in ways that produce variability in both disease onset and severity and differential expression based on both the age and sex of the patient. Thus, the natural history of asthma is complex in terms of disease expression, remission, relapse, and progression. As such, therapy for asthma is complicated and has been approached from the standpoints of primary, secondary, and tertiary prevention. Presently, asthma cannot be cured but can be controlled in most patients, an indication that most of the success clinical research strategies have realized has been in the area of tertiary prevention. Since for many adult patients with asthma their disease had its roots in early life, much recent research has focused on events during early childhood that can be linked to subsequent asthma development with the hopes of creating appropriate interventions to alter its natural history of expression. These research approaches can be categorized into three questions. Who is the right patient to treat? When is the right time to begin treatment? And finally, what is the appropriate treatment to prescribe?

Demographic data in asthma clinical trials: a systematic review with implications for generalizing trial findings and tackling health disparities

The prevalence of asthma, and the morbidity, adverse events, mortality and healthcare utilisation of asthmatic patients vary widely among racial/ethnic and other socio-demographic groups. Debates over the meanings of race and ethnicity and the strategic need to resolve health inequalities have prompted extensive recommendations for reporting and analyzing racial/ethnic and demographic information in clinical trials. We conducted a systematic review to determine the extent to which race/ethnicity, socio-economic status and other demographic variables are analyzed and reported in publications from randomized controlled trials of asthma interventions. Randomized controlled trials of inhaled corticosteroids and long-acting beta-agonists in asthmatic patients were identified by systematically searching 12 electronic bibliographic databases. We identified peer-reviewed papers reporting 87 relevant trials published during 1985-2006, from which we extracted data on patients' race/ethnicity, ancestry, gender, socio-economic variables and geographical attributes. The proportion of the papers reporting the race/ethnicity of their participants was lower than would be expected by chance and has recently declined. None of the papers included race/ethnicity or gender in statistical analyses or reported socio-economic variables, ancestry, or genetic data for their participants, and few discussed the generalizability of their findings. The frequency of reporting race/ethnicity was statistically significantly lower in trials conducted in the UK than in the US, but 23 of the 87 papers did not identify countries. Despite extensive recommendations in the literature, guidance from health agencies on analyzing and reporting demographic data in clinical trials still appears inconsistent and vague. There remains a need to improve guidance on the representation and analysis of minority populations in asthma clinical trials, in order to encourage transparent reporting of population selection, analysis approaches, and trial generalizability. To assist this process, asthma clinical trials should be based on clear hypotheses that link both to existing demographic evidence and to demographic healthcare goals.

Pharmacogenetics and functional genomics in asthma

Asthma is a complex phenotype caused by a combination of genetic and environmental factors that remain poorly understood. The common variants involved in the pathogenesis of asthma have proved difficult to identify by candidate gene association studies. As a result, few genetic variants influencing clinical response to asthma and allergy medications have been uncovered. Recently, genome-wide association, which is more robust in identifying common predisposition variants, has been applied to disorders such as asthma. As genome-wide associations are hypothesis-free, they raise the possibility of identifying novel biological pathways that could be translated to the future benefit of patients through improved diagnostic and therapeutic measures in the form of personalized medicine. This review addresses both recent advances in the genetics of asthma and their potential in transforming the treatment of the disorder into more individualized care in the near future.

Genetic variants of GSNOR and ADRB2 influence response to albuterol in African-American children with severe asthma

African Americans are disproportionately affected by asthma. Social and economic factors play a role in this disparity, but there is evidence that genetic factors may also influence the development of asthma and response to therapy in African American children. Our hypothesis is that variations in asthma related genes contribute to the observed asthma disparities by influencing the response to asthma-specific therapy. In order to test this hypothesis, we characterized the clinical response to asthma-specific therapy in 107 African American children who presented to the emergency room in status asthmaticus, with a primary outcome indicator of length of time on continuous albuterol. Single locus analysis indicated that genotype variation in glutathione-dependent S-nitrosoglutathione reductase (GSNOR) is associated with a decreased response to asthma treatment in African American children. A post hoc multi-locus analysis revealed that a combination of four single nucleotide polymorphisms (SNPs) within GSNOR, adrenergic receptor beta 2, and carbamoyl phosphate synthetase-1 give a 70% predictive value for lack of response to therapy. This predictive model needs replication in other cohorts of patients with asthma, but suggests gene-gene interactions may have greater significance than that identified with single variants. Our findings also suggest that genetic variants may contribute to the observed population disparities in asthma.

Body mass index and phenotype in subjects with mild-to-moderate persistent asthma

BACKGROUND

Although obesity has been hypothesized to worsen asthma, data from studies of subjects with well-characterized asthma are lacking.

OBJECTIVE

We sought to evaluate the relationship between body mass index (BMI), asthma impairment, and response to therapy.

METHODS

BMI (in kilograms per meter squared) and asthma phenotypic and treatment response data were extracted from Asthma Clinical Research Network studies. The cross-sectional relationship between BMI and asthma impairment was analyzed, as was the longitudinal relationship between BMI and response to asthma controller therapies.

RESULTS

One thousand two hundred sixty-five subjects with mild-to-moderate persistent asthma were evaluated. Analyses of lean versus overweight/obese asthmatic subjects demonstrated small differences in FEV1 (3.05 vs 2.91 L, P = .001), FEV1/forced vital capacity ratio (mean, 83.5% vs 82.4%; P = .01), rescue albuterol use (1.1 vs 1.2 puffs per day, P = .03), and asthma-related quality of life (5.77 vs 5.59, P = .0004). Overweight/obese asthmatic subjects demonstrated a smaller improvement in exhaled nitric oxide levels with inhaled corticosteroid (ICS) treatment than did lean asthmatic subjects (3.6 vs 6.5 ppb, P = .04). With ICS/long-acting beta-agonist treatment, overweight/obese asthmatic subjects demonstrated smaller improvements in lung function than lean asthmatic subjects, with an 80 mL (P = .04) and 1.7% (P = .02) lesser improvement in FEV1 and FEV1/forced vital capacity ratio, respectively. Significant differences in therapeutic response to leukotriene modifiers between BMI categories were not observed.

CONCLUSIONS

Increased BMI is not associated with clinically significant worsening of impairment in subjects with mild-to-moderate persistent asthma. There is a modest association between increased BMI and reduced therapeutic effect of ICS-containing regimens in this patient population. Prospective studies evaluating the effect of being overweight or obese on treatment response in asthma are warranted.

Polymorphisms of the beta2 adrenoreceptor gene in chronic obstructive pulmonary disease

BACKGROUND

The beta2-adrenergic receptors are cell surface receptors playing a central role in the pharmacological targeting asthma and chronic obstructive pulmonary disease [COPD]. Recent studies suggest that patients who are homozygous for one of the two important polymorphisms of the beta2-adrenergic receptor [ADRB2] gene at codon 16 (arginine to glycine) and 27 (glutamine to glutamate) may have a reduced response to ss2-agonists. Since smoking patients who are Gly16 homozygotes have an increased risk of airway obstruction we hypothesized that beta2-adrenoreceptor gene polymorphisms may be also a cofounder for COPD development and disease severity.

METHODS

We investigated 190 COPD patients and 172 healthy volunteers in a case-control study. DNA was isolated from whole blood and beta2-AR gene polymorphisms Arg/Gly16 and Gln/Glu27 were determined using allele-specific polymerase chain reaction [PCR].

RESULTS

In COPD patients with Gly/Gly16 was found more frequently than in healthy smokers [29.47% COPD versus 18.18% controls, p = 0.026]. All other gene polymorphisms of the ADRB2 gene at codon 16 were equally distributed between groups. ss2-adrenoreceptor gene polymorphisms were neither a cofounder for COPD exacerbations [>or= 3 hospitalizations within the last 3 years] nor for disease severity [FEV1 <or= 30% predicted].

CONCLUSION

Our study suggests that the Gly16 allele of the beta2-AR gene predisposes to COPD development but not for exacerbation rates and disease severity. In contrast, Gln/Glu27 polymorphism was irrelevant in our COPD cohort.

Beta 2-adrenergic polymorphisms and total serum IgE levels in children with asthma from Argentina

BACKGROUND

Beta 2-Adrenergic receptor polymorphisms occurring at amino acid positions 16 (arginine/glycine) and 27 (glutamine/glutamic acid) are known to be functionally relevant. Associations with several asthma-related phenotypes, such as total serum IgE, have been investigated with different results.

OBJECTIVE

To determine the contribution of polymorphisms and haplotypes of beta 2-adrenergic receptor with serum IgE levels in children from Argentina with mild, moderate, and severe asthma.

METHODS

Beta 2-Adrenergic receptor polymorphisms were analyzed in 124 white asthmatic children using polymerase chain reaction during a 3-year period (January 1, 2005, through December 31, 2007). Total serum IgE level was measured by standard methods in all study participants, and age-adjusted values were determined for each individual.

RESULTS

Serum levels of IgE were 4.3-fold higher than age-adjusted normal values in the study population. No association was found in regard to asthma severity. A significant difference of IgE serum levels was observed among polymorphisms at position 16, with the highest IgE level in the arginine/arginine group (P = .04). At position 27, even though median levels of IgE in homozygous glutamine were 2.2 times higher than homozygous glutamic acid, this increase did not reach statistical significance. When the population was stratified according to the most common homozygous haplotypes (arginine-arginine 16/glutamine-glutamine 27, glycine-glycine 16/glutamine-glutamine 27, and glycine-glycine 16/glutamic acid-glutamic acid 27), no association was found in relation to the serum levels of IgE.

CONCLUSIONS

Beta 2-Adrenergic receptor polymorphisms, especially homozygous arginine 16, were associated with higher serum IgE levels in children with asthma. These genetic variants appear to contribute to the IgE level in asthmatic children from Argentina.

Additive role of tiotropium in severe asthmatics and Arg16Gly in ADRB2 as a potential marker to predict response

BACKGROUND

Recent findings have raised new interests about the use of anticholinergics, especially tiotropium, for the treatment of asthma. This study was performed to determine whether an additional improvement in lung function is obtained when tiotropium is administrated in addition to conventional therapies in severe asthmatics, and to identify factors capable of predicting the response to tiotropium, using a pharmacogenetic approach.

METHODS

A total of 138 severe asthmatics on conventional medications and with decreased lung function were randomly recruited. Tiotropium 18 microg was added once a day and lung functions were measured every 4 weeks. Responders were defined as those with an improvement of > or = 15% (or 200 ml) in the forced expiratory volume in 1 s (FEV1) that was maintained for at least 8 successive weeks. Eleven single nucleotide polymorphisms (SNPs) in CHRM1-3 (coding muscarinic receptors one to three) which were identified by re-sequencing, and Arg16Gly and Gln27Glu in ADRB2 (coding beta(2) adrenoreceptor) were scored in 80 of the 138 asthmatics.

RESULTS

Forty-six of the 138 asthmatics (33.3%) responded to tiotropium treatment. Logistic regression analyses (controlled for age, gender, and smoking status) showed that Arg16Gly in ADRB2 [P = 0.003, OR (95% CI) = 0.21 (0.07-0.59) in a minor allele-dominant model] was significantly associated with response to tiotropium.

CONCLUSIONS

As many as 30% of severe asthmatics on conventional medications with reduced lung function were found to respond to adjuvant tiotropium. The presence of Arg16Gly in ADRB2 may predict response to tiotropium.

Effect of beta2-adrenergic receptor polymorphism in asthma control of patients receiving combination treatment

PURPOSE

Combination treatment of inhaled corticosteroid (ICS) plus long-acting beta2-agonist (LABA) is widely used as a maintenance regimen for the management of asthma. This study evaluated the effect of the beta2-adrenergic receptor (ADRB2) polymorphism on lung function and asthma control with regular use of combination treatment of an inhaled ICS plus LABA.

MATERIALS AND METHODS

43 Korean asthmatics who were symptomatic despite regular ICS use for at least 3 months were enrolled. For a 2-week run-in period, they received ICS (budesonide 800 microg/day) plus terbutaline (5 microg prn). as needed. During the 24-week active treatment period, they received budesonide 160 microg and formoterol 4.5 microg b.i.d. as maintenance and rescue medication. Pulmonary function and quality of life scores were monitored every 8 weeks; morning/evening peak expiratory flow meter (PEFR) was recorded daily. Patients were genotyped for ADRB2 Arg16Gly using single base extension methodology.

RESULTS

During the run-in period, there were no significant between-group differences in lung function; after 8 weeks of active treatment, Arg/Arg patients had significantly higher forced expiratory volume in 1 secord (FEV(1)) and maximal mid-expiratory flow (MMEF) (p = 0.023 and p = 0.021, respectively), and better asthma control and quality of life after 24 weeks (p = 0.016 and p = 0.028, respectively). During treatment, there was a greater improvement in morning/evening PEFR in Arg/Arg patients.

CONCLUSION

Asthmatic patients with the Arg/Arg genotype at codon 16 of ADRB2 achieve better asthma control with long-term regular use of combined budesonide and formoterol treatment, suggesting that the ADRB2 genotype may dictate choice of treatment strategy.

Pharmacogenetic characterization of indacaterol, a novel beta 2-adrenoceptor agonist

BACKGROUND AND PURPOSE

Indacaterol is a novel beta(2)-adrenoceptor agonist in development for the treatment of chronic obstructive pulmonary disease. The aim of this study was to investigate the comparative pharmacology of indacaterol in recombinant cells expressing the common polymorphic variants of the human beta(2)-adrenoceptor and in human primary airway smooth muscle (ASM) cells.

EXPERIMENTAL APPROACH

Chinese hamster ovarian-K1 cell lines expressing high and low levels of the common human beta(2)-adrenoceptor variants were generated [Gly16-Glu27-Val34-Thr164(GEVT), RQVT, GQVT] and also the rare GQVI variant. Human primary ASM cells were isolated from explants of trachealis muscle. Adenosine-3',5'-cyclic-monophosphate production was used as an outcome measure.

KEY RESULTS

In both the low- and high-expression recombinant GEVT 'wild type' cell lines indacaterol is a high-efficacy agonist. Salmeterol and formoterol were identified as low- and high-efficacy agonists, respectively, and showed similar potencies to indacaterol irrespective of the beta(2)-adrenoceptor genotype. The I164 variant cell line was associated with a reduced capacity to generate adenosine-3',5'-cyclic-monophosphate in response to beta(2)-adrenoceptor agonist. In the human primary ASM cells indacaterol gave a maximal response intermediate between that of salmeterol and formoterol.

CONCLUSIONS AND IMPLICATIONS

These data demonstrate that indacaterol is a high-efficacy agonist in recombinant cell systems but acts with lower efficacy in human primary ASM cells. No marked genotype-dependent effects were observed for common variants; however, changes in I164 receptor activity were identified, which were dependent on the level of expression of beta(2)-adrenoceptors.

Acute and chronic lung function responses to salmeterol and salmeterol plus fluticasone propionate in relation to Arg16Gly beta(2)-adrenergic polymorphisms

OBJECTIVE

There is conflicting clinical evidence describing the response to long-acting beta-agonist (LABA) bronchodilators for patients with Arg16Gly beta(2)-adrenergic receptor (ADRB2 ) genotype differences. Furthermore, the role of inhaled corticosteroids (ICS) in modulating Arg16Gly clinical responses is not well understood. The objective of this study was to investigate the effects of Arg16Gly polymorphism on the 12 hour post-dose bronchodilator response to the LABA salmeterol (SAL) or SAL plus fluticasone propionate (FSC) on first administration and following 12 weeks of treatment.

RESEARCH DESIGN AND METHODS

Genotyping was retrospectively performed in patients with persistent asthma randomized to SAL or FSC who were participating in three similar double-blind clinical trials of 12 week duration. The primary outcome was area under the curve (AUC) for 12 hour serial FEV(1) by treatment and Arg16Gly genotype, recorded on Day 1 and Week 12. In addition, other single nucleotide polymorphisms (SNPs) associated with asthma outcomes we assessed at positions -47, +79 and +491 as well as common ADRB2 haplotypes.

RESULTS

No statistically significant associations between Arg16Gly genotypes and serial FEV(1) clinical responses to SAL and FSC were observed following acute assessment. In addition, the FEV(1) response was preserved following 12 weeks of treatment with SAL and FSC and was not altered by Arg16Gly genotypes analyzed. These results may not be generalizable to other ethnic groups since they are derived predominantly from Caucasians.

CONCLUSIONS

In subjects with persistent asthma, the ADRB2 Arg16Gly polymorphism does not alter lung function responses to SAL or FSC over the 12 hour dosing interval following acute and chronic dosing.

Overview of pharmacogenetics

Pharmacogenetics is the study of relationships between genetic variation and inter-individual differences with respect to drug response. As the field has matured over the past 15 years, a remarkable diversity of pathways, variation types, and mechanisms have been found to be relevant pharmacogenetic factors. Today, pharmacogenetics is becoming more important in pharmacology for target validation, lead optimization, and understanding of idiosyncratic toxicity. This unit provides an overview of the history of pharmacogenetics and current research applications in drug discovery, as well as a discussion of research quality issues relevant for human subjects research in the pharmacogenetics laboratory.

Safety of long-acting beta2-agonists in the treatment of asthma

Several studies suggested an association between the regular use of beta2-agonists and asthma deaths. Whether this association represents adverse effects of beta -agonist use or is entirely due to disease severity is a matter of ongoing debate. Previous literature indicates that confounding by poor asthma control may explain the apparent deleterious effects of inhaled beta2-agonists. Tolerance to nonbronchodilator effects of beta2-agonists may account for the increase in reactivity to indirect bronchoconstrictor challenges and explain why some studies have demonstrated enhanced bronchoconstriction in patients with asthma after regular beta 2-agonist therapy. Nonetheless, the salmeterol multi-centre asthma research trial (SMART) found more asthma deaths (13 vs 3) and life-threatening asthma events (37 vs 22) in the salmeterol-treated asthmatic patients, although it was documented that among African-Americans, 5 times as many deaths and near-deaths from asthma occurred in those given salmeterol than in those given placebo, and among patients with asthma not using an inhaled corticosteroid (ICS) as a preventive (controller) medication, again more deaths and near-deaths from asthma occurred in those given salmeterol than in those given placebo. Only 38% of the African-Americans who participated in the study used an ICS. As a result of the findings from the SMART, FDA issued a public health advisory to highlight that long-acting beta2-agonists (LABAs) should not be the first medicine used to treat asthma. LABAs should be added to the asthma treatment plan only if other medicines, including the use of low-or-medium dose ICSs, do not control asthma. However, despite all of the concerns raised by the SMART, inhaled beta2-agonists remain the most effective bronchodilators available for the immediate relief of asthma symptoms and, as such, remain an important component of asthma management. Obviously, there are concerns about LABA treatment as monotherapy for asthma. Patients with asthma should be initiated and maintained on sufficiently high doses of ICSs and only patients whose asthma cannot be controlled should receive additional LABAs on a regular basis.

Pharmacogenetics of asthma

PURPOSE OF REVIEW

Patient response to the asthma drug classes, bronchodilators, inhaled corticosteroids and leukotriene modifiers, are characterized by a large degree of heterogeneity, which is attributable in part to genetic variation. Herein, we review and update the pharmacogenetics and pharmaogenomics of common asthma drugs.

RECENT FINDINGS

Early studies suggest that bronchodilator reversibility and asthma worsening in patients on continuous short-acting and long-acting beta-agonists are related to the Gly16Arg genotype for the ADRB2. More recent studies including genome-wide association studies implicate variants in other genes contribute to bronchodilator response heterogeneity and fail to replicate asthma worsening associated with continuous beta-agonist use. Genetic determinants of the safety of long-acting beta-agonist require further study. Variants in CRHR1, TBX21, and FCER2 contribute to variability in response for lung function, airways responsiveness, and exacerbations in patients taking inhaled corticosteroids. Variants in ALOX5, LTA4H, LTC4S, ABCC1, CYSLTR2, and SLCO2B1 contribute to variability in response to leukotriene modifiers.

SUMMARY

Identification of novel variants that contribute to response heterogeneity supports future studies of single nucleotide polymorphism discovery and include gene expression and genome-wide association studies. Statistical models that predict the genomics of response to asthma drugs will complement single nucleotide polymorphism discovery in moving toward personalized medicine.

A new focus on assessing and treating asthma control in the African-American community: a call to action

Asthma continues to be a highly prevalent disease characterized by significant morbidity, unnecessary mortality, and substantial cost to the health care system. After decades of increasing prevalence, the number of current asthmatics in recent years has plateaued at approximately 22 million people in the United States. An additional 10 million Americans have a past history of asthma that is not active. The burden of asthma is higher among African Americans than in any other racial or ethnic group in America. The African-American community continues to experience a disproportional increase in asthma prevalence, morbidity, and mortality. The educational initiatives stemming from the newly revised National Heart Lung and Blood Institute (NHLBI) guidelines provide the opportunity to address the increased burden of asthma in the African American community. These new guidelines, released in August 2007, focus on asthma control as the primary goal of therapy, routine monitoring of asthma control, and use of asthma control assessments to direct treatment. The present review discusses the following: I. The impact of health disparities on outcomes of African Americans with asthma, II. The barriers that prevent asthmatic patients from achieving optimal control, III. The unique factors that challenge practitioners and patients in achieving optimal asthma control in the African American Community, IV. The impact of good asthma control and the need for patients and clinicians to assess asthma control in with a standardized assessment tool, and V. Strategic initiatives and the role of the End The Attacks NOW program in improving outcomes for African American patients with asthma.

Beta2-adrenergic receptor polymorphisms affect response to treatment in children with severe asthma exacerbations

BACKGROUND

beta(2)-adrenergic receptor (AR) agonists are the mainstay of treatment for severe asthma exacerbations, one of the most common causes of critical illness in children. Genotypic differences in the beta(2)-AR gene, particularly at amino acid positions 16 and 27, have been shown to affect the response to beta(2)-AR agonist therapy. Our hypothesis is that genotypic differences contribute to patient response to beta(2)-AR agonist treatment during severe asthma exacerbations in children.

METHODS

Children admitted to the hospital ICU for a severe asthma exacerbation between 2002 and 2005 were located, and genetic samples were obtained from saliva. Children hospitalized during this period were treated with a protocol that titrated beta(2)-AR therapy (first nebulized, then IV) according to a validated clinical asthma score.

RESULTS

Thirty-seven children hospitalized during the study period were enrolled into the study. At amino acid position 16 in the beta(2)-AR gene, 13 children were homozygous for the glycine (Gly) allele (Gly/Gly), 8 were homozygous for the arginine (Arg) allele (Arg/Arg), and 16 were heterozygous (Arg/Gly). Despite similar clinical asthma scores on hospital admission, the children with the Gly/Gly genotype had significantly shorter hospital ICU length of stay and duration of continuously nebulized albuterol therapy and were significantly less likely to require IV beta(2)-AR therapy than those with Arg/Arg or Arg/Gly genotypes. No association existed among polymorphisms at amino acid position 27 and response to beta(2)-AR therapy.

CONCLUSIONS

In this cohort of children with severe asthma exacerbations, children whose genotypes were homozygous for Gly at amino acid position 16 of the beta(2)-AR gene had a more rapid response to beta(2)-AR agonist treatment. The beta(2)-AR genotype appears to influence the response to therapy in this population.

A polymorphism of G-protein coupled receptor kinase5 alters agonist-promoted desensitization of beta2-adrenergic receptors

Beta-agonist treatment of asthma displays substantial interindividual variation, which has prompted polymorphism discovery and characterization of beta2-adrenergic (beta2AR) signaling genes. beta2AR function undergoes desensitization during persistent agonist exposure because of receptor phosphorylation by G-protein coupled receptor kinases (GRKs). GRK5 was found to be highly expressed in airway smooth muscle, the tissue target for beta-agonists. The coding region is polymorphic at codon 41, where Gln can be substituted by Leu (minor allele), but almost exclusively in those of African descent. In transfected cells, GRK5-Leu41 evoked a greater degree of agonist-promoted desensitization of adenylyl cyclase compared with GRK5-Gln41. Consistent with this functional effect, agonist-promoted beta2AR phosphorylation was greater in cells expressing GRK5-Leu41, as was the rate of agonist-promoted receptor internalization. In studies with mutated beta2AR lacking PKA-phosphorylation sites, this phenotype was confirmed as being GRK-specific. So, GRK5-Leu41 represents a gain-of-function polymorphism that evokes enhanced loss-of-function of beta2AR during persistent agonist exposure, and thus may contribute to beta-agonist variability in asthma treatment of African-Americans.

Pediatric asthma and related allergic and nonallergic diseases: patient-oriented evidence-based essentials that matter

Asthma is the most common medical diagnosis among hospitalized children. In the USA, asthma has accounted for approximately 15% of nonsurgical admissions to hospital in the pediatric age group. Asthma is also one of the leading causes for emergency care requirements, one of the leading causes for missed school, and a cause for considerable morbidity, disability and occasional mortality at all ages. Despite these discouraging statistics, convincing data indicate that this failure of asthma management is not the result of inadequate therapeutic potential, but instead represents ineffective delivery of medical care. Management of asthma and its major co-morbidities, allergic and nonallergic rhinitis, and atopic dermatitis requires a knowledge of the alternative therapies, natural history, and educational techniques for providing patients and families with the ability to manage these troublesome chronic disorders.

Update on the pathogenesis and management of childhood asthma

PURPOSE OF REVIEW

To review and summarize trends in the current literature in childhood asthma with implications for current management and future research.

RECENT FINDINGS

There have been several articles in the last year that address the pathogenesis and pharmacogenomics of asthma. Recent consensus guidelines have been published that emphasize a stepwise approach to management, which will be briefly reviewed here. Several publications have proposed novel treatments to attempt to attenuate asthmatic lower airway inflammation. In terms of measuring this inflammation, a portable exhaled nitric oxide analyzer has been developed.

SUMMARY

Evidence shows that various early life exposures (high house dust mite levels, early antibiotic use) may predispose susceptible individuals to the development of asthma, but the early introduction of solid foods, even so-called allergenic foods, does not appear to be one of these factors. Newly identified pharmacogenomic markers may be the first step in tailoring each asthmatic patient's therapy on the basis of genotype, and management tailored specifically toward each patient's level of airway inflammation is already coming into wider clinical use. Several novel treatments for asthma have shown promise in early studies. On the basis of the most recent evidence, the National Education and Prevention Program's Guidelines for the Diagnosis and Management of Asthma is a comprehensive, stepwise management guide for asthma.

Pharmacogenetic response to albuterol among asthmatics

Pharmacogenetics offers to individualize asthma treatment by identifying genetic variants associated with drug efficacy or adverse events. Several studies have focused on pharmacogenetic associations with albuterol, the most commonly prescribed medication for asthma worldwide. However, pharmacogenetic associations have varied within and between studies and across populations. Herein, we focus on pharmacogenetic associations between genetic variants in the beta(2)-adrenergic receptor gene and bronchodilator response to albuterol among subjects with asthma.

Achieving asthma control in practice: understanding the reasons for poor control

Achieving asthma control remains an elusive goal for the majority of patients worldwide. Ensuring a correct diagnosis of asthma is the first step in assessing poor symptom control; this requires returning to the basics of history taking and physical examination, in conjunction with lung function measurement when appropriate. A number of factors may contribute to sub-optimal asthma control. Concomitant rhinitis, a common co-pathology and contributor to poor control, can often be identified by asking a simple question. Smoking too has been identified as a cause of poor asthma control. Practical barriers such as poor inhaler technique must be addressed. An appreciation of patients' views and concerns about maintenance asthma therapy can help guide discussion to address perceptual barriers to taking maintenance therapy (doubts about personal necessity and concerns about potential adverse effects). Further study into, and a greater consideration of, factors and patient characteristics that could predict individual responses to asthma therapies are needed. Finally, more clinical trials that enrol patient populations reflecting the real world diversity of patients seen in clinical practice, including wide age ranges, presence of comorbidities, current smoking, and differing ethnic origins, will contribute to better individual patient management.

Genetic landscape of the people of India: a canvas for disease gene exploration

Analyses of frequency profiles of markers on disease or drug-response related genes in diverse populations are important for the dissection of common diseases. We report the results of analyses of data on 405 SNPs from 75 such genes and a 5.2 Mb chromosome, 22 genomic region in 1871 individuals from diverse 55 endogamous Indian populations. These include 32 large (>10 million individuals) and 23 isolated populations, representing a large fraction of the people of India. We observe high levels of genetic divergence between groups of populations that cluster largely on the basis of ethnicity and language. Indian populations not only overlap with the diversity of HapMap populations, but also contain population groups that are genetically distinct. These data and results are useful for addressing stratification and study design issues in complex traits especially for heterogeneous populations.

Endogenous Gs-coupled receptors in smooth muscle exhibit differential susceptibility to GRK2/3-mediated desensitization

Although G protein-coupled receptor (GPCR) kinases (GRKs) have been shown to mediate desensitization of numerous GPCRs in studies using cellular expression systems, their function under physiological conditions is less well understood. In the current study, we employed various strategies to assess the effect of inhibiting endogenous GRK2/3 on signaling and function of endogenously expressed G s-coupled receptors in human airway smooth muscle (ASM) cells. GRK2/3 inhibition by expression of a Gbetagamma sequestrant, a GRK2/3 dominant-negative mutant, or siRNA-mediated knockdown increased intracellular cAMP accumulation mediated via beta-agonist stimulation of the beta-2-adrenergic receptor (beta 2AR). Conversely, neither 5'-( N-ethylcarboxamido)-adenosine (NECA; activating the A2b adenosine receptor) nor prostaglandin E2 (PGE 2; activating EP2 or EP4 receptors)-stimulated cAMP was significantly increased by GRK2/3 inhibition. Selective knockdown using siRNA suggested the majority of PGE 2-stimulated cAMP in ASM was mediated by the EP2 receptor. Although a minor role for EP3 receptors in influencing PGE 2-mediated cAMP was determined, the GRK2/3-resistant nature of EP2 receptor signaling in ASM was confirmed using the EP2-selective agonist butaprost. Somewhat surprisingly, GRK2/3 inhibition did not augment the inhibitory effect of the beta-agonist on mitogen-stimulated increases in ASM growth. These findings demonstrate that with respect to G s-coupled receptors in ASM, GRK2/3 selectively attenuates beta 2AR signaling, yet relief of GRK2/3-dependent beta 2AR desensitization does not influence at least one important physiological function of the receptor.

Racial disparities in asthma-related health outcomes in severe or difficult-to-treat asthma

BACKGROUND

The underlying reasons for racial disparities in asthma morbidity are not well understood. Multivariate epidemiologic studies evaluating the presence and extent of racial differences in a large cohort of adults with severe or difficult-to-treat asthma are lacking.

OBJECTIVE

To analyze an extensive array of clinical and patient-reported outcomes, using multivariate analysis with a sequential approach, to explain racial differences in asthma-related outcomes in one of the largest cohorts of difficult-to-treat asthmatic patients.

METHODS

Black and white patients (> or = 18-years-old at baseline) were included (n = 2,128). Differences between the 2 racial groups were assessed using several outcome measures at month 12. Assessments were adjusted for confounding variables using a sequence of statistical models.

RESULTS

Most patients were white (88.6%). Blacks were slightly younger, less educated, and more likely to live in urban areas than whites. Blacks were more likely to have severe asthma and to be treated with 3 or more long-term controllers. Poorer quality of life, more asthma control problems, and higher risk of emergency department visits were observed in blacks compared with whites; differences were not explained by adjustment for broad sets of confounding variables. Differences in asthma-related health outcomes remained statistically significant after adjusting for asthma severity.

CONCLUSIONS

Asthma is a serious health problem in blacks and is not explained by differences in demographics, severity, or other health conditions.

Potential adverse effects of bronchodilators in the treatment of airways obstruction in older people: recommendations for prescribing

Asthma and chronic obstructive pulmonary disease (COPD) are common disorders that are associated with increasing morbidity and mortality in older people. Bronchodilators are used widely in patients with these conditions, but even when used in inhaled form can have systemic as well as local effects. Older people experience more adverse drug effects because of pharmacodynamic and pharmacokinetic changes and particularly drug-drug and drug-disease interactions. Cardiovascular disease is common in older people and beta-adrenoceptor agonists (beta-agonists) have inotropic and chronotropic effects that can increase arrhythmias and cardiomyopathy. They can also worsen or induce myocardial ischaemia and cause electrolyte disturbances that contribute to arrhythmias. Tremor is a well known distressing adverse effect of beta-agonist administration. Long-term beta-agonist use can be associated with tolerance, poor disease control, sudden life-threatening exacerbations and asthma-related deaths. Functional beta2-adrenoceptors are present in osteoblasts, and chronic use of beta-agonists has been implicated in osteoporosis. Inhaled anticholinergics are usually well tolerated but may cause dry mouth, which can be troublesome in older people. Pupillary dilatation, blurred vision and acute glaucoma can occur from escape of droplets from loosely fitting nebulizer masks. Although ECG changes have not been seen in randomized controlled trials of long-acting inhaled anticholinergics, supraventricular tachycardias have been observed in a 5-year randomized controlled trial of ipratropium bromide. Paradoxical bronchoconstriction can occur with inhaled anticholinergics as well as with beta-agonists, but tolerance has not been reported with anticholinergics. Anticholinergic drugs also cause central effects, most notably impairment of cognitive function, and these effects have been noted with inhaled agents. Use of theophylline is limited by its adverse effects, which range from commonly occurring gastrointestinal symptoms to palpitations, arrhythmias and reports of myocardial infarction. Seizures have been reported, but are rare. Theophylline is metabolized primarily by the liver, and commonly interacts with other medications. Its concentration in plasma should be monitored closely, especially in older people. Although many clinical trials have been conducted on bronchodilators in obstructive airways disease, the results of these clinical trials need to be interpreted with caution as older people are often under-represented and subjects with co-morbidities actively excluded from these trials.

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

Recent reports suggest that beta(2)-adrenergic receptor (ADRB2) genotypes are associated with therapeutic responses to beta(2) agonists in asthmatics. However, few studies have investigated therapeutic responses to beta(2) agonists in chronic obstructive pulmonary disease (COPD) patients. This study investigated immediate bronchodilator response and lung function responses following a 12-week treatment with a long-acting beta(2) agonist combined with a steroid inhaler in patients with COPD with various ADRB2 genotypes. One hundred four patients with chronic obstruction were genotyped for codon 16 and 27 polymorphisms of the ADRB2 gene. The immediate bronchodilator response to beta(2)-agonist treatment was evaluated after inhalation of 400 microg salbutamol. In addition, long-term response was evaluated using observed change in spirometric values before and after the treatment with salmeterol (50 microg) combined with fluticasone propionate (500 microg) inhalation twice daily for 12 weeks. In terms of codon 16 variants, the immediate bronchodilator response to salbutamol was 6.4 +/- 0.8% (% predicted value) in Arg/Arg patients, 4.9 +/- 0.7% in Arg/Gly patients, and 5.8 +/- 1.2% in Gly/Gly patients (p = 0.418). The FEV(1) changes following the 12-week treatment were 7.0 +/- 1.2% in Arg/Arg patients, 3.0 +/- 1.5% in Arg/Gly patients, and 7.2 +/- 1.2% in Gly/Gly patients (p = 0.229). Similarly, there was no difference between codon 27 variants in terms of immediate bronchodilator response or FEV1 changes after 12 weeks of treatment. We were unable to demonstrate an association between ADRB2 genotype and the effect on lung function of 12-week treatment with combined long-acting beta(2) agonist and glucocorticoid inhalation or on the immediate bronchodilator response to a short-acting beta(2) agonist in patients with COPD.

Exercise-induced bronchospasm in children

This review will encompass definition, history, epidemiology, pathogenesis, diagnosis, and management of exercise -induced bronchospasm in the pediatric individual with and without known asthma. Exercise induced asthma is the conventional term for transient airway narrowing in a known asthma in association with strenuous exercise usually lasting 5-10 minutes with a decline in pulmonary function by at least 10%. Exercise induced asthma will be referred to as exercise induced bronchospasm in an asthmatic. Exercise-induced bronchospasm (EIB ) is the same phenomenon in an individual without known asthma. EIB can be seen in healthy individuals including children as well as defense recruits and competitive or elite athletes. The diagnosis with objective exercise challenge methods in conjunction with history is delineated. Management is characterized with pharmacotherapy and non pharmacotherapeutic measures for underlying asthma as well as exercise induced bronchospasm and inhalant allergy. Children can successfully participate in all sports if asthma is properly managed.

Asthma 2008: targeting immunoglobulin E to achieve disease control

Traditionally, practice guidelines have recommended a step-wise approach to treatment based on asthma severity and lung function. However, increasing evidence suggests that asthma may not be adequately controlled in many patients with moderate-to-severe disease despite aggressive therapy, and that regularly evaluating the level of asthma control achieved in individual patients may be more effective than disease severity in guiding treatment decisions. This is reflected in updated asthma guidelines from the National Asthma Education and Prevention Program, which advocate regular assessment of asthma control in terms of the current impairment and future risk associated with the disease. Guideline-recommended options for patients with persistent, moderate-to-severe immunoglobulin E (IgE)-mediated asthma have recently been enhanced by the inclusion of omalizumab. This change is based on growing evidence for the central role of IgE in airway inflammation and asthma and the clinical effectiveness of blocking IgE with omalizumab, a recombinant humanized monoclonal antibody. Omalizumab significantly reduced asthma exacerbations and improved lung function and symptoms in randomized controlled studies of patients inadequately controlled on inhaled corticosteroids plus long-acting beta(2)-agonist therapy; these benefits for reducing asthma impairment and risk were maintained during steroid dose reductions. Omalizumab is well tolerated, although patients should be monitored for possible rare anaphylactic reactions.

Interactions between glutathione S-transferase P1, tumor necrosis factor, and traffic-related air pollution for development of childhood allergic disease

BACKGROUND

Air pollutants may induce airway inflammation and sensitization due to generation of reactive oxygen species. The genetic background to these mechanisms could be important effect modifiers.

OBJECTIVE

Our goal was to assess interactions between exposure to air pollution and single nucleotide polymorphisms (SNPs) in the beta2-adrenergic receptor (ADRB2), glutathione S-transferase P1 (GSTP1), and tumor necrosis factor (TNF) genes for development of childhood allergic disease.

METHODS

In a birth cohort originally of 4,089 children, we assessed air pollution from local traffic using nitrogen oxides (traffic NO(x)) as an indicator based on emission databases and dispersion modeling and estimated individual exposure through geocoding of home addresses. We measured peak expiratory flow rates and specific IgE for inhalant and food allergens at 4 years of age, and selected children with asthma symptoms up to 4 years of age (n = 542) and controls (n = 542) for genotyping.

RESULTS

Interaction effects on allergic sensitization were indicated between several GSTP1 SNPs and traffic NO(x) exposure during the first year of life (p(nominal) < 0.001-0.06). Children with Ile105Val/Val105Val genotypes were at increased risk of sensitization to any allergen when exposed to elevated levels of traffic NO(x) (for a difference between the 5th and 95th percentile of exposure: odds ratio = 2.4; 95% confidence interval, 1.0-5.3). In children with TNF-308 GA/AA genotypes, the GSTP1-NO(x) interaction effect was even more pronounced. We observed no conclusive interaction effects for ADRB2.

CONCLUSION

The effect of air pollution from traffic on childhood allergy appears to be modified by GSTP1 and TNF variants, supporting a role of genes controlling the antioxidative system and inflammatory response in allergy.

Beta2-adrenoceptor polymorphisms predict response to beta2-agonists in children with acute asthma

The aim of this study was to determine the influence of single nucleotide polymorphisms in the beta(2)-adrenoceptor gene, on the response to inhaled beta(2)-agonists in children with acute asthma. We hypothesised that children with polymorphisms that generate enhanced receptor downregulation in vitro, Gly16 and Gln27, would have a slower response to beta(2)-agonist therapy during acute asthma. One hundred and forty-eight children with acute asthma were recruited and genotyped for beta(2)Arg16Gly and beta(2)Gln27Glu. For Gln27Glu, individuals Gln27Gln took longest to stretch out to 1, 2 and 4 hourly beta(2)-agonists, followed by heterozygotes who were intermediate and Glu27Glu who responded most rapidly (1 hourly: 2.6 hr vs. 2.0 vs. 1.4, p = 0.02; 2 hourly: 10.6 hr vs. 10.7 vs. 6.8, p = 0.07; 4 hourly: 29.8 hr vs. 28.5 vs. 24.3, p = 0.30). The ability to prospectively identify children who respond less effectively to beta (2)-agonists during an acute asthma attack has the potential to allow the generation of genotype-specific treatment pathways.