O Polimorfismo Genético do Receptor Beta-Adrenérgico Tipo 1 Ser49Gly é Preditor de Morte em Pacientes Brasileiros com Insuficiência Cardíaca / Ser49Gly Beta1-Adrenergic Receptor Genetic Polymorphism as a Death Predictor in Brazilian Patients with Heart Failure

Resumo Fundamento O papel do polimorfismo genético do receptor beta1-adrenérgico Ser49Gly (PG-Rβ1-Ser49Gly) como preditor de eventos na insuficiência cardíaca (IC) não está definido para a população brasileira. Objetivos Avaliar a relação entre PG-Rβ1-Ser49Gly e desfechos clínicos em indivíduos com IC com fração de ejeção reduzida. Métodos Análise secundária de prontuários de 178 pacientes e identificação das variantes do PG-Rβ1-Ser49Gly, classificadas como Ser-Ser, Ser-Gly e Gly-Gly. Avaliar sua relação com evolução clínica. Foi adotado nível de significância de 5%. Resultados As médias da coorte foram: seguimento clínico, 6,7 anos; idade, 64,4 anos; 63,5% de homens e 55,1% brancos. A etiologia da IC foi predominantemente isquêmica (31,5%), idiopática (23,6%) e hipertensiva (15,7%). O perfil genético teve a seguinte distribuição: 122 Ser-Ser (68,5%), 52 Ser-Gly (28,7%), e 5 Gly-Gly (2,8%). Houve relação significativa entre esses genótipos e a classe funcional da New York Heart Association (NYHA) ao final do acompanhamento (p = 0,014) com o Gly-Gly associado a NYHA menos avançada. Com relação aos desfechos clínicos, houve associação significativa (p = 0,026) entre mortalidade e PG-Rβ1-Ser49Gly: o número de óbitos em pacientes com Ser-Gly (12) ou Gly-Gly (1) foi menor que com Ser-Ser (54). O alelo Gly teve um efeito protetor independente mantido após análise multivariada e foi associado à redução na chance de óbito de 63% (p = 0,03; odds ratio 0,37 - IC 0,15 a 0,91). Conclusão A presença do PG-Rβ1 Gly-Gly associou-se a melhor evolução clínica avaliada pela classe funcional da NYHA e foi preditor de menor risco de mortalidade, independentemente de outros fatores, em seguimento de 6,7 anos. (Arq Bras Cardiol. 2020; 114(4):616-624)

Abstract Background The role of Ser49Gly beta1-adrenergic receptor genetic polymorphism (ADBR1-GP-Ser49Gly) as a predictor of death in heart failure (HF) is not established for the Brazilian population. Objectives To evaluate the association between ADBR1-GP-Ser49Gly and clinical outcomes in individuals with HF with reduced ejection fraction. Methods Secondary analysis of medical records of 178 patients and genotypes of GPRβ1-Ser49Gly variants, classified as Ser-Ser, Ser-Gly and Gly-Gly. To evaluate their association with clinical outcome. A significance level of 5% was adopted. Results Cohort means were: clinical follow-up 6.7 years, age 63.5 years, 64.6% of men and 55.1% of whites. HF etiologies were predominantly ischemic (31.5%), idiopathic (23.6%) and hypertensive (15.7%). The genetic profile was distributed as follows: 122 Ser-Ser (68.5%), 52 Ser-Gly (28.7%) and 5 Gly-Gly (2.8%). There was a significant association between these genotypes and mean NYHA functional class at the end of follow-up (p = 0.014) with Gly-Gly being associated with less advanced NYHA. In relation to the clinical outcomes, there was a significant association (p = 0.026) between mortality and GPRβ1-Ser49Gly: the number of deaths in patients with Ser-Gly (12) or Gly-Gly (1) was lower than in those with Ser-Ser (54). The Gly allele had an independent protective effect maintained after multivariate analysis and was associated with a reduction of 63% in the risk of death (p = 0.03; Odds Ratio 0.37 - CI 0.15-0.91). Conclusion The presence of β1-AR-GP Gly-Gly was associated with better clinical outcome evaluated by NYHA functional class and was a predictor of lower risk of mortality, regardless of other factors, in a 6.7-year of follow-up. (Arq Bras Cardiol. 2020; 114(4):613-615)

Polimorfismos beta1-adrenérgico associados com Fibrilação Atrial na Insuficiência Cardíaca Sistólica / Beta1-adrenergic receptor polymorphisms associated with atrial fibrillation in systolic heart failure

FUNDAMENTO: O sistema nervoso simpático apresenta grande importância na patogênese da fibrilação atrial na insuficiência cardíaca sistólica. A identificação de polimorfismos no gene ADBR1 do receptor beta1-adrenérgico representa um importante passo no conhecimento dessa patogênese. OBJETIVO: Este estudo analisou a associação entre os dois polimorfismos funcionais do gene ADBR1 do receptor beta1-adrenérgico, Ser49Gly e Arg389Gly, e a presença da fibrilação atrial em pacientes com insuficiência cardíaca sistólica. MÉTODOS: Estudo caso-controle com 144 pacientes portadores de insuficiência cardíaca sistólica, dos quais 24 com fibrilação atrial (casos) e 120 sem fibrilação atrial (controles). O DNA genômico foi extraído de leucócitos do sangue periférico e os genótipos dos polimorfismos Ser49Gly e Arg389Gly foram identificados em todos os indivíduos por PCR/RFLP (polymerase chain reaction / restriction fragment length polymorphism). RESULTADOS: A média etária foi 59 ± 13 anos, 70% dos pacientes eram do sexo masculino, 42% apresentavam causa isquêmica e 74% apresentavam hipertensão arterial sistêmica. Os genótipos Ser49Ser e Arg389Arg apresentaram associação significativa com fibrilação atrial (p = 0,005 e p = 0,01; respectivamente). Por meio de regressão logística, ambos ajustados para o tamanho do átrio esquerdo e idade, mantiveram associação significativa (Arg389Arg - odds ratios: 2,78; intervalo de confiança de 95% = 1,02 - 7,56 e Ser49Ser - odds ratios: 8,02; intervalo de confiança de 95% = 1,02 - 63,82). CONCLUSÃO: Ambos os genótipos associaram-se com fibrilação atrial nos pacientes estudados, porém apenas o polimorfismo Ser49Gly apresentava-se em equilíbrio de Hardy-Weinberg.

BACKGROUND: The sympathetic nervous system is of great importance in the pathogenesis of atrial fibrillation in systolic heart failure. The identification of polymorphisms in the beta1-adrenergic receptor gene (ADBR1) represents an important step in understanding this pathogenesis. OBJECTIVE: This study assessed the association between the two functional polymorphisms of the beta1-adrenergic receptor gene (ADBR1), Ser49Gly and Arg389Gly, and the presence of atrial fibrillation in patients with systolic heart failure. METHODS: Case-control study with 144 patients with systolic heart failure, including 24 with atrial fibrillation (cases) and 120 without atrial fibrillation (controls). Genomic DNA was extracted from peripheral blood leukocytes and the genotypes of Ser49Gly and Arg389Gly polymorphisms were identified in all individuals by PCR/RFLP (polymerase chain reaction / restriction fragment length polymorphism). RESULTS: Mean age was 59 ± 13 years, 70% of patients were males, 42% had ischemic causes and 74% had hypertension. Genotypes Ser49Ser and Arg389Arg were significantly associated with atrial fibrillation (p = 0.005 and p = 0.01, respectively). After logistic regression, both adjusted for left atrial size and age, the significant association persisted (Arg389Arg - odds ratios: 2.78, 95% confidence interval = 1.02 to 7.56 and Ser49Ser - odds ratios: 8.02, 95% confidence interval = 1.02 to 63.82). CONCLUSION: Both genotypes were associated with atrial fibrillation in patients; however, only Ser49Gly polymorphism was is in Hardy-Weinberg equilibrium.

Methylation of adrenergic 1 receptor is a potential epigenetic mechanism controlling antihypertensive response to metoprolol.

Although metoprolol is used to treat hypertension, clinical responses are variable and unpredictable. Evidence suggests that adrenergic 1 receptor (ADRB1, designated Adrb1 in rodents) gene polymorphisms influence the level of blood pressure response to this drug therapy, but their presence can not predict the response of the individual patient. The question exists whether epigenetic modifications, such as DNA methylation could cause changes in the gene’s expression that are a determining factor in metoprolol’s efficacy. The aim of this study was to verify whether DNA methylation could change the expression of the ADRB1 gene, and epigenetic modification could explain why individuals with identical ADRB1 gene polymorphisms have different antihypertensive responses to metoprolol. H9c2 rat myocardial cells in vitro were randomly divided into 5-aza-2'-deoxycytidine (decitabine)-treated (0.5 to 10.0 μM) and control groups. For the in vivo experiments, 45 spontaneously hypertensive rats (SHRs) were divided into metoprolol-treated and control groups, and after a 4-week intervention myocardia were harvested. Genomic methylation-sensitive PCR was used to assess the methylation status of the Adrb1 promoter after DNA extraction from H9c2 cells and SHR myocardia. Real-time fluorescent quantitative RT-PCR was used to determine levels of Adrb1 mRNA. In H9c2 cells, the least degree of methylation was observed in the 5.0 μM decitabine treated group. Prolonged exposure of cells to 5.0 μM decitabine resulted in downregulating methylation of the Adrb1 promoter. Increased levels of Adrb1 mRNA of the 5.0 μM group demonstrated that this concentration resulted in the highest expression. Accordingly, DNA methylation resulted in the downregulation of Adrb1 transcription. In vivo, the lower level of methylation of the Adrb1 promoter from SHR myocardial samples demonstrated a better antihypertensive effect by metoprolol. The expression of Adrb1 mRNA in the effective group of SHRs was significantly upregulated. In conclusion, as shown in both H9c2 cells and SHRs, downregulated methylation of the Adrb1 promoter is likely to improve the antihypertensive efficacy of metoprolol.

Polymorphic variants of β1 adrenergic receptor gene (Ser49Gly & Arg389Gly) in healthy Tamilian volunteers.

Background & objectives: Several studies reported the polymorphisms of β1-adrenergic receptor gene in healthy volunteers and its influence on cardiovascular disorders. We investigated the genotype and allele frequencies of Ser49Gly and Arg389Gly polymorphism in healthy volunteers of South Indian Tamilian population vis-à-vis other major ethnic groups. Methods: The genetic variants were determined by using Taqman 5’ nuclease assay- real time PCR analysis in 533 normal healthy volunteers (18-60 yr; M=290; F=243). The allelic discrimination analysis was done by 7700 SDS software. Results: The estimated genotype and allele frequencies of Ser49Gly and Arg389Gly polymorphism were compared with other major populations. The frequencies of the variant alleles Gly49 and Gly389 were 15.1 and 25.8 per cent respectively. Interpretation & conclusions: Our study shows that interethnic variation exists in the polymorphisms of β1-adrenergic receptor gene and the results generated in this study might serve as a genetic marker for further studies in Tamilian (South India) population.

Investigations into the presence of functional ß1, ß2 and ß3-adrenoceptors in urothelium and detrusor of human bladder

Purpose: We investigated the presence of functional ß1, ß2 and ß3-adrenoceptor in urothelium and detrusor muscle of human bladder through in vitro pharmacology of selective ß3 adrenoceptor agonist solabegron. Materials and Methods: Expression of these adrenoceptors in surgically separated human urothelium and detrusor muscle were investigated using RT-PCR. The effects of activating these receptors were studied by determining the relaxation produced by ß-adrenoceptors agonist in pre-contracted human detrusor strips. Results: The results confirmed the presence of mRNA for ß1, ß2 and ß3-adrenoceptor in both human urothelium and detrusor. In an in vitro functional bladder assay, Solabegron and other agonists for ß-adrenoceptors such as procaterol and isoproterenol evoked potent concentration-dependent relaxation of isolated human bladder strips with pD2 values of 8.73 ± 0.19, 5.08 ± 0.48 and 6.28 ± 0.54, respectively. Conclusions: Selective ß3-adrenoceptor agonist may be a potential new treatment for the overactive bladder OAB syndrome. Existence of ß3-adrenoceptor mRNA exists in the urothelium in addition to the detrusor muscle suggest multiple site of actions for the ß3-adrenoceptor in the lower urinary tract.

Interacción entre los polimorfismos del receptor ß1 y ß2 adrenérgico como predictor de riesgo de insuficiencia cardiaca crónica / Interactions between ß1 and ß2 adrenergic receptor polymorphisms as risk factors for chronic heart failure

Background: ß adrenergic receptors (AR) are highly polymorphic and important regulators of cardiovascular homeostasis. Among these, ß1 and ß2 AR regulate cardiac contractility and frequency and are important pharmacological targets. Aim: To evaluate genotype and gene-gene interaction between ß1-AR Arg389Gly and ß2-AR ArglSGly GlnZ7Gly and Thrl 64Ile polymorphisms, as risk factors for HF. Material and methods: Eighty chronic HF patients and eighty-eight controls matched by age and sex were genotyped for ß1 -AR Arg389Gly ß2-AR ArgWGly, GlnZ7Glu and Thr164Ile polymorphisms. Results: The presence of ß2-AR Glu afiele was a risk predictor for HF (odds ratio (OR) =2.81; 95 percent confidence intervals (CI) =1.49-5.31). Interactions that increased the risk for HF were found in patients carrying at least one of the ß2-AR Glu and ß2-AR Gly allele (OR =3.81; 95 percent CI =1.50-0.70) and ß2-AR Glu and ß1 -AR Gly allele combination (OR =5.51; 95 percent CI =2.19-13.86). Furthermore, the frequency of ß2-AR Glu allele was higher among patients with a history ofacute myocardial infarction (with infarction: 0.534, without: 0.313, p =0.01). Conclusions: ß2-AR Glu allele could be a risk predictor for HF. This risk could be enhanced by the additional presence of ß2-AR GlyW or ß1-AR Arg389 alleles. The frequency of ß2-AR Gln27 Glu allele was higher among patients with a history of myocardial infarction.

Neurohumoral activation in heart failure: the role of adrenergic receptors

A insuficiência cardíaca (IC) é a via final comum da maioria das doenças cardiovasculares e uma das maiores causas de morbi-mortalidade. O desenvolvimento do estágio final da IC freqüentemente envolve um insulto inicial do miocárdio, reduzindo o débito cardíaco e levando ao aumento compensatório da atividade do sistema nervoso simpático (SNS). Existem evidências de que apesar da exposição aguda ser benéfica, exposições crônicas a elevadas concentrações de catecolaminas, liberadas pelo terminal nervoso simpático e pela glândula adrenal, são tóxicas ao tecido cardíaco e levam a deterioração da função cardíaca. Em nível molecular observa-se que a hiperatividade do SNS está associada a alterações na sinalização intracelular mediada pelos receptores beta-adrenérgicos. Sabe-se que tanto a densidade como a função dos receptores beta-adrenérgicos estão diminuídas na IC, assim como outros mecanismos intracelulares subjacentes à estimulação da via receptores beta-adrenérgicos. Nesta revisão, apresentaremos uma breve descrição da via de sinalização dos receptores beta-adrenérgicos no coração normal e as conseqüências da hiperatividade do SNS na IC. Daremos ênfase ao potencial miopático de diversos componentes da cascata de sinalização dos receptores beta-adrenérgicos discutindo estudos realizados com animais geneticamente modificados. Finalmente, discorreremos sobre o impacto clínico do conhecimento dos polimorfismos para o gene do receptor beta-adrenérgico para um melhor entendimento da progressão da IC.