RESUMO
Reversibility of airway obstruction in response to ß2-agonists is highly variable among asthmatics, which is partially attributed to genetic factors. In a genome-wide association study of acute bronchodilator response (BDR) to inhaled albuterol, 534 290 single-nucleotide polymorphisms (SNPs) were tested in 403 white trios from the Childhood Asthma Management Program using five statistical models to determine the most robust genetic associations. The primary replication phase included 1397 polymorphisms in three asthma trials (pooled n=764). The second replication phase tested 13 SNPs in three additional asthma populations (n=241, n=215 and n=592). An intergenic SNP on chromosome 10, rs11252394, proximal to several excellent biological candidates, significantly replicated (P=1.98 × 10(-7)) in the primary replication trials. An intronic SNP (rs6988229) in the collagen (COL22A1) locus also provided strong replication signals (P=8.51 × 10(-6)). This study applied a robust approach for testing the genetic basis of BDR and identified novel loci associated with this drug response in asthmatics.
Assuntos
Agonistas de Receptores Adrenérgicos beta 2/uso terapêutico , Asma/tratamento farmacológico , Broncodilatadores/uso terapêutico , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Adolescente , Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Asma/genética , Broncodilatadores/administração & dosagem , Criança , Pré-Escolar , Ensaios Clínicos como Assunto , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto JovemRESUMO
A pro-asthmatic culture milieu and ß2-agonist (isoproterenol) were previously shown to regulate the expression of select transcription factors (TFs) within human airway epithelial and smooth muscle cells. This study tests 1116 single-nucleotide polymorphisms (SNPs) across 98 of these TF genes for association with bronchodilator response (BDR) in asthma patients. Genotyping was conducted using the Illumina HumanHap550v3 Beadchip in 403 non-Hispanic White asthmatic children and their parents. SNPs were evaluated for association with BDR using family and population-based analyses. Forty-two SNPs providing P-values <0.1 in both analyses were then genotyped in three adult asthma trials. One SNP 5' of the thyroid hormone receptor-ß gene was associated with BDR in the childhood population and two adult populations (P-value=0.0012). This investigation identified a novel locus for inter-individual variability in BDR and represents a translation of a cellular drug-response study to potential personalization of clinical asthma management.
Assuntos
Asma/genética , Células Epiteliais/metabolismo , Miócitos de Músculo Liso/metabolismo , Receptores beta dos Hormônios Tireóideos/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Asma/tratamento farmacológico , Asma/patologia , Biomarcadores Farmacológicos/metabolismo , Broncodilatadores/administração & dosagem , Broncodilatadores/efeitos adversos , Criança , Pré-Escolar , Células Epiteliais/patologia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Estudos de Associação Genética , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Miócitos de Músculo Liso/patologia , Polimorfismo de Nucleotídeo Único , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Although the association of angiotensin I-converting enzyme inhibitors (ACEis) with a negatively charged membrane is thought to be responsible for hypersensitivity reactions (HSRs) during hemodialysis, we hypothesize that these complications are due to changes in plasma aminopeptidase P (APP) activity and genotype. To test this hypothesis, we measured plasma APP activity in 14 patients who suffered HSR (HSR+) while dialyzed with an AN69 membrane and simultaneously treated with an ACEi. APP activity was also studied in a control group (n=39) dialyzed under the same conditions, but who did not suffer any side effect (HSR-). We found significantly decreased plasma APP activity (P=0.013) in HSR+ subjects as well as altered degradation of endogenous des-Arginine(9)-bradykinin, with a significantly lower beta value (P<0.001). The same analytical approach was taken in 171 relatives of HSR+ patients. Variance component analysis suggested that genetic differences may explain 61% of the phenotypic variability of plasma APP activity (P<0.001) and the kinetic parameters that characterized kinin degradation. We also showed that the C-2399A single-nucleotide polymorphism at the XPNPEP2 locus was a significant predictor of APP activity in the 39 HSR- controls (P=0.029). Furthermore, a recessive genetic model for the A allele disclosed a significant difference in mean APP activity by genotype (P<0.001). Finally, our study defined the nonspecific inhibition of recombinant APP by some ACEis. In conclusion, this paper highlights the complexity of HSR in hemodialysis, suggesting, as with angioedema, that these rare, but life-threatening adverse events are governed by several metabolic and genetic factors.