Influence of polymorphisms of the beta-2 adrenergic receptor on the presence of exercise-induced bronchospasm in adolescents

Cássio Leandro Mühe Consentino,Lupe Furtado-Alle,Larissa Rosa Da Silva,Wendell Arthur Lopes,Luciane Viater Tureck,Gerusa Einsfeld Milano,Leilane Lazarotto,Cláudia Regina Cavaglieri,Neiva Leite

doi:10.1016/j.rppede.2015.06.021

Abstract

ObjectiveTo determine the influence of polymorphisms of the beta-2 adrenergic receptor (ADRB2) in triggering exercise-induced bronchospasm (EIB) in adolescents. MethodsThe subjects were divided into two groups: present EIB (EIB+) (n=45) and absent EIB (EIB−) (n=115). The bronchial provocation test with exercise was performed with a protocol that consisted of walking/running for at least eight minutes at high intensity, i.e., >85% of maximum heart rate, considering EIB+ as a 10% decrease in forced expiratory volume in one second (FEV1). The genotyping of the ADRB2 gene was performed by the Taqman method, using the Step One Plus system. Independent t-test, Mann–Whitney and Chi-square tests, as well as Spearman's correlation coefficient were used for the statistical analysis. ResultsAge, body weight, height, FEV1, FVC and FEV1/FVC ratio were lower in the EIB+ group when compared to EIB− (p<0.05). There were no significant differences in the proportion of the allele at position 27 and Arg16Gly and Gln27Glu genotypes between the EIB+ and EIB− groups (p=0.26; p=0.97 and p=0.43, respectively). However, there was a trend toward statistical significance regarding the greater proportion of the Gly16 allele for the EIB+ when compared to the EIB− group (p=0.08). ConclusionsThe presence of polymorphisms associated with the Glu27 allele and Arg16Gly and Gln27Glu genotypes had no influence on EIB. However, the statistical trend toward greater frequency of the Gly16 allele in individuals with EIB+ can be considered evidence of the influence of polymorphisms of the ADBR2 gene on EIB in adolescents.

Highlights

Exercise-induced bronchospasm (EIB) is defined as temporary narrowing of the airways that occurs after strenuous exercise in up to 90% of asthmatic individuals[1] and in almost 20% of individuals with no history of respiratory disease.[2]
Differences were observed for the variables age, body weight, height, FEV1 and forced vital capacity (FVC) in liters and in the FEV1/FVC ratio, being lower in the EIB+ group
There was a trend toward statistical significance for a greater proportion of polymorphisms at allele 16 in the EIB+ group when compared to the EIB− (p=0.08) (Table 2)

Summary

Introduction

Exercise-induced bronchospasm (EIB) is defined as temporary narrowing of the airways that occurs after strenuous exercise in up to 90% of asthmatic individuals[1] and in almost 20% of individuals with no history of respiratory disease.[2]. The Arg16Gly and Gln27Glu polymorphisms of the ADRB2 gene have been associated with asthma symptoms,[7] including reduction in the pulmonary function and in the bronchodilation response to medication, as they have negative influence on the bronchodilator effect,[13] a therapeutic resource that is part of pre-exercise EIB prevention.[14]

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Conclusion