Influence of angiotensinogen and angiotensin-converting enzyme polymorphisms on cardiac hypertrophy and improvement on maximal aerobic capacity caused by exercise training

Sports activities and cardiovascular system change

Sports activity is generally considered to be beneficial to health. The World Health Organization (WHO) recommends physical activity as part of a healthy lifestyle. Sports activities significantly affect the cardiovascular system. A number of studies show that they significantly reduce the risk of cardiovascular disease as well as decrease cardiovascular mortality. This review discusses changes in various cardiovascular parameters in athletes - vagotonia/bradycardia, hypertrophy of heart, ECG changes, blood pressure, and variability of cardiovascular parameters. Because of its relationship to the cardiovascular system, VO2max, which is widely used as an indicator of cardiorespiratory fitness, is also discussed. The review concludes with a discussion of reactive oxygen species (ROS) and oxidative stress, particularly in relation to changes in the cardiovascular system in athletes. The review appropriately summarizes the above issues and points out some new implications.

Marked improvements in cardiac function in postmenopausal women exposed to blood withdrawal plus endurance training

The cardiac phenotype of a substantial fraction of the population, i.e., mature women, is mainly unresponsive to endurance training (ET), the most effective intervention to improve cardiorespiratory fitness. This study assessed whether a novel intervention comprising additional haemodynamic stimuli may overcome the generalized limitations to modify the cardiac phenotype of middle-aged and older women. Fifteen healthy postmenopausal women (52-75 yr) were recruited. Transthoracic echocardiography and central haemodynamics were assessed during incremental cycle ergometry (i) in baseline conditions, (ii) after standard (10%) blood withdrawal and (iii) subsequent 8-week ET. Main outcomes such as left ventricular (LV) function and structure and blood volume (BV) were determined. Phlebotomy induced a 0.5 ± 0.1 l reduction of BV, which was re-established after ET. Decrements in LV end-systolic volume (-27%) and increments in LV ejection fraction (+8%) during exercise as well as improved E/A ratio were detected after ET compared with baseline. In parallel, ET induced a 10% increment in LV mass without a concomitant increase in LV size. In conclusion, postmenopausal women exhibit large improvements in cardiac systolic and diastolic functions along with LV concentric remodelling in response to the sequenced combination of blood withdrawal and ET.

Left ventricular hypertrophy in athletes, a case-control analysis of interindividual variability

BACKGROUND

A variability in cardiac remodeling is observed in athletes regardless of age, sex, body size and sport participated. We sought to investigate whether other individual characteristics could affect the extent of Left ventricular hypertrophy (LVH).

METHODS

From 2120 consecutive Olympic athletes, those with LVH (defined as LV Wall thickness ≥ 13 mm) were matched 1:1 by age, gender, body surface area and type of sport with non-LVH Athletes. Clinical and Echocardiographic variables were compared.

RESULTS

48 athletes with LVH (2.3%) and 48 matched non-LVH athletes were identified. LVH Athletes had higher body weight (90 ± 18 vs 81 ± 11Kg; p = 0.006) body mass index (26 ± 2 vs 24 ± 2 Kg/m2; p < 0.001) and body fat percentage (15 ± 7% vs 12 ± 4%; p = 0.016) compared to non-LVH Athletes. They also had higher systolic (123 ± 1 vs 116 ± 11 mmHg; p = 0.002) and diastolic blood pressure (76 ± 8 vs 71 ± 9 mmHg; p = 0.002). On exercise testing, LVH Athletes reached a lower index workload (3.7 ± 0.9 vs 4.1 ± 0.8 W/Kg; p = 0.013) and a higher peak diastolic blood pressure (79 ± 10 vs 74 ± 11 mmHg; p = 0.012) than those without LVH. Binary logistic regression analysis showed that diastolic blood pressure (OR 1.052; 95% CI from 1.011 to 1.130; p = 0.020) and BMI (OR 1.220; 95% CI from 1.016 to 1.465; p = 0.033) had the strongest association with LVH as categorical variable.

CONCLUSIONS

Our study showed that increased blood pressure at rest and during exercise, together with larger body weight, body mass and fat percentage are associated with a higher degree of LVH, which is not associated with a greater physical performance and therefore possibly disproportionate to the sport activity.

Association between polymorphisms of genes involved in the Renin-Angiotensin-Aldosterone System and the adaptive morphological and functional responses to essential hypertension

Hypertensive cardiac remodeling is illustrated by increased left ventricular (LV) mass index values and/or relative wall thickness (RWT) values >0.42, and functionally by isolated alteration of LV diastole (abnormal relaxation). The aim of the present study was to establish differentiated models of anatomical and functional adaptation to essential hypertension (EHT), in relation to the genetic variants of genes involved in the Renin-Angiotensin-Aldosterone System (RAAS). The M235T-AGT, I/D-ACE, A1166C-R1AngII, A3123C-R2AngII and G83A-REN genotypes were determined using PCR-Restriction Fragment Length Polymorphism in 139 hypertensive subjects. The relationship between the studied RAAS gene polymorphisms with morphological and functional cardiac remodeling was assessed by multiple logistic regression analysis. Patients carrying the C/C, A/C genotypes (A3123C-R2AngII polymorphism) had a 2.72-fold (P=0.033) increased risk of exhibiting an RWT value <0.42; in the multivariate model the risk was 4.02-fold higher (P=0.008). Analysis of LV diastolic dysfunction (LVDD) revealed that hypertensive patients carrying the T/T, M/T genotypes (M235T-AGT polymorphism) had a 2.24-fold (P=0.037) increased risk of developing LVDD and a 2.42-fold increased risk (P=0.039) after adjustment for confounders. Similarly, carriers of the G/G, A/G genotypes (G83A-REN) had a 2.32-fold (P=0.021) increased risk of developing LVDD, and this remained an independent risk factor based on the multivariate model (P=0.033). The results of the present study showed that no particular gene was associated with increased LV mass, but the A3123C-R2AngII polymorphism was associated with a non-concentric type of cardiac response in hypertensive patients. Conversely, the M235T-AGT and G83A-REN polymorphisms were found to be statistically significantly associated with LVDD when assessing abnormal relaxation.

Mapping Robust Genetic Variants Associated with Exercise Responses

This review summarised robust and consistent genetic variants associated with aerobic-related and resistance-related phenotypes. In total we highlight 12 SNPs and 7 SNPs that are robustly associated with variance in aerobic-related and resistance-related phenotypes respectively. To date, there is very little literature ascribed to understanding the interplay between genes and environmental factors and the development of physiological traits. We discuss future directions, including large-scale exercise studies to elucidate the functional relevance of the discovered genomic markers. This approach will allow more rigour and reproducible research in the field of exercise genomics.

Genes to predict VO2max trainability: a systematic review

Background

Cardiorespiratory fitness (VO_2max) is an excellent predictor of chronic disease morbidity and mortality risk. Guidelines recommend individuals undertake exercise training to improve VO_2max for chronic disease reduction. However, there are large inter-individual differences between exercise training responses. This systematic review is aimed at identifying genetic variants that are associated with VO_2max trainability.

Methods

Peer-reviewed research papers published up until October 2016 from four databases were examined. Articles were included if they examined genetic variants, incorporated a supervised aerobic exercise intervention; and measured VO_2max/VO_2peak pre and post-intervention.

Results

Thirty-five articles describing 15 cohorts met the criteria for inclusion. The majority of studies used a cross-sectional retrospective design. Thirty-two studies researched candidate genes, two used Genome-Wide Association Studies (GWAS), and one examined mRNA gene expression data, in addition to a GWAS. Across these studies, 97 genes to predict VO_2max trainability were identified. Studies found phenotype to be dependent on several of these genotypes/variants, with higher responders to exercise training having more positive response alleles than lower responders (greater gene predictor score). Only 13 genetic variants were reproduced by more than two authors. Several other limitations were noted throughout these studies, including the robustness of significance for identified variants, small sample sizes, limited cohorts focused primarily on Caucasian populations, and minimal baseline data. These factors, along with differences in exercise training programs, diet and other environmental gene expression mediators, likely influence the ideal traits for VO_2max trainability.

Conclusion

Ninety-seven genes have been identified as possible predictors of VO_2max trainability. To verify the strength of these findings and to identify if there are more genetic variants and/or mediators, further tightly-controlled studies that measure a range of biomarkers across ethnicities are required.

The influence of genetic polymorphisms on performance and cardiac and hemodynamic parameters among Brazilian soccer players

This study investigated whether ACTN3 R577X, AMPD1 C34T, I/D ACE, and M235T AGT polymorphisms can affect performance tests such as jumping, sprinting, and endurance in 220 young male athletes from professional minor league soccer team from São Paulo Futebol Clube, Brazil. I/D ACE and M235T AGT polymorphisms were also analyzed according to cardiac and hemodynamic parameters. Athletes were grouped or not by age. DNA from saliva and Taqman assays were used for genotyping 220 athletes and the results were associated with performance tests. Ventricle mass, ventricle end-diastolic diameter, end-diastolic volume, and ejection fraction were assessed by echocardiogram. Arterial pressure, heart rate, and oximetry were assessed by a cardioscope. The main results of this study were that athletes who carried RR/RX (ACTN3) and DD (ACE) genotypes presented better performance during jump and sprint tests. On the other hand, athletes with ID/II genotype presented better results during endurance test, while AGT genotypes did not seem to favor the athletes during the evaluated physical tests. CC genotype (AMPD1) only favored the athletes during 10-m sprint test. Although there are environmental interactions influencing performance, the present results suggest that RR/RX ACTN3 and ACE DD genotypes may benefit athletes in activities that require strength and speed, while II ACE genotype may benefit athletes in endurance activities. This information could help coaches to plan the training session to improve the athletes’ performance.

Current Progress in Sports Genomics

Understanding the genetic architecture of athletic performance is an important step in the development of methods for talent identification in sport. Research concerned with molecular predictors has highlighted a number of potentially important DNA polymorphisms contributing to predisposition to success in certain types of sport. This review summarizes the evidence and mechanistic insights on the associations between DNA polymorphisms and athletic performance. A literature search (period: 1997-2014) revealed that at least 120 genetic markers are linked to elite athlete status (77 endurance-related genetic markers and 43 power/strength-related genetic markers). Notably, 11 (9%) of these genetic markers (endurance markers: ACE I, ACTN3 577X, PPARA rs4253778 G, PPARGC1A Gly482; power/strength markers: ACE D, ACTN3 Arg577, AMPD1 Gln12, HIF1A 582Ser, MTHFR rs1801131 C, NOS3 rs2070744 T, PPARG 12Ala) have shown positive associations with athlete status in three or more studies, and six markers (CREM rs1531550 A, DMD rs939787 T, GALNT13 rs10196189 G, NFIA-AS1 rs1572312 C, RBFOX1 rs7191721 G, TSHR rs7144481 C) were identified after performing genome-wide association studies (GWAS) of African-American, Jamaican, Japanese, and Russian athletes. On the other hand, the significance of 29 (24%) markers was not replicated in at least one study. Future research including multicenter GWAS, whole-genome sequencing, epigenetic, transcriptomic, proteomic, and metabolomic profiling and performing meta-analyses in large cohorts of athletes is needed before these findings can be extended to practice in sport.

Association of rs699 (M235T) polymorphism in the AGT gene with power but not endurance athlete status

Thus far, genetic studies of the renin-angiotensin system (RAS) with respect to athletic performance or athlete status have mainly focused on the angiotensin-converting enzyme gene and its insertion/deletion polymorphism. The aim of this study was to investigate the functional rs699 (M235T) polymorphism in angiotensinogen (AGT), the second most important gene of the RAS, for association with athletic status and level of performance. The study included 123 endurance athletes and 100 power-oriented athletes, who were classified as elite or sub-elite according to competitive achievements at the international level, and 354 unrelated sedentary control subjects. The M235T genotype and allele distributions differed significantly between power and endurance athletes (p < 0.0001 and p < 0.0002, genotypes and alleles, respectively) and between power athletes and control subjects (p < 0.0001 and p < 0.0002, genotypes and alleles, respectively). The frequency of the CC genotype in the power athlete group was 2.2 times higher and 3.1 times higher than in the control and endurance groups, respectively. No difference was found in M235T allele distribution between elite and sub-elite athletes, either in power- or endurance-oriented athletes. We conclude that the CC genotype of the M235T polymorphism is overrepresented in Polish power athletes, suggesting that the AGT M235T variant is associated with power athletes' status.

Exercise capacity after coarctation repair relates to the c.46A > G genomic polymorphism of the ss2-adrenoreceptor and the c.704T > C angiotensinogen polymorphism

BACKGROUND

Even after excellent repair of aortic coarctation without restenosis there are limitations in exercise capacity at long-term follow-up. This study was performed to assess the contribution of inherited genomic polymorphisms to exercise capacity in patients without restenosis.

PATIENTS AND METHODS

122 patients aged 17-72 years, 46 female, 76 male, seen 2-27 years after repair of aortic coarctation with a residual brachial-ankle-gradient ≤20 mmHg were investigated. Genomic polymorphism of angiotensin converting enzyme (ACE I/D), angiotensinogen (AGT, c.704C > T), angiotensin II receptor type 1 (AGTR1, c.1166A > C), endothelin 1 (EDN1, EDN1/ex5-c.5665G > T), G protein (GNB3, c.825C > T), and two polymorphisms each of the ß1-adrenoreceptor (ADRB1, c.145G > A and c.1165C > G), ß2-adrenoreceptor (ADRB2, c.46A > G and c.79C > G), and endothelial NO synthase (NOS3, intron 4 I/D and NOS3, c.894G > T) were determined by PCR amplification and fragment length analysis. Exercise capacity was determined by an upright bicycle exercise test.

RESULTS

Only the c.46A > G polymorphism of the ADRB2 (p = 0.024) and the c.704T > C AGT polymorphism (p = 0.042) were positively correlated with peak workload. Patients with one or especially two polymorphic alleles showed a significant higher exercise performance compared with those patients homozygous for the wild type.

CONCLUSIONS

In contrast to a previous study in heart failure patients, after coarctation repair adults had a better exercise capacity with the G allele of the ß2-receptor c.46A > G polymorphism. Therefore, the exercise capacity of coarctation patients does not profit from an enhanced down regulation of their beta receptors.

Genética, performance física humana e doping genético: o senso comum versus a realidade científica

Atletas de elite são reconhecidos como fenômenos esportivos e o potencial para atingir níveis superiores de performance no esporte está parcialmente sob o controle de genes. A excelência atlética é essencialmente multifatorial e determinada por complexas interações entre fatores ambientais e genéticos. Existem aproximadamente 10 milhões de variantes genéticas dispersas por todo o genoma humano e uma parcela destas variantes têm demonstrado influenciar a responsividade ao treinamento físico. Os fenótipos de performance física humana parecem ser altamente poligênicos e alguns estudos têm comprovado a existência de raras combinações genotípicas em atletas. No entanto, os mecanismos pelos quais genes se interagem para amplificar a performance física são desconhecidos. O conhecimento sobre os genes que influenciam a treinabilidade somado ao potencial uso indevido dos avanços da terapia gênica, como a possível introdução de genes em células de atletas, fez surgir o termo doping genético, um novo e censurado método de amplificação da performance física, além dos limites fisiológicos. Aumentos na hipertrofia muscular esquelética e nos níveis de hematócrito estão sendo conseguidos através da manipulação da expressão de genes específicos, mas a grande parte das impressionáveis alterações foi obtida em experimentação com animais de laboratório. A compreensão dos resultados científicos envolvendo genética, performance física humana e doping genético é uma difícil tarefa. Com o propósito de evitar a contínua má interpretação e propagação de conceitos errôneos, esta revisão, intencionalmente, vem discutir as evidências científicas produzidas até o momento sobre o tema, permitindo a compreensão do atual "estado da arte"

Exercise training improves muscle vasodilatation in individuals with T786C polymorphism of endothelial nitric oxide synthase gene

Allele T at promoter region of the eNOS gene has been associated with an increase in coronary disease mortality, suggesting that this allele increases susceptibility for endothelial dysfunction. In contrast, exercise training improves endothelial function. Thus, we hypothesized that: 1) Muscle vasodilatation during exercise is attenuated in individuals homozygous for allele T, and 2) Exercise training improves muscle vasodilatation in response to exercise for TT genotype individuals. From 133 preselected healthy individuals genotyped for the T786C polymorphism, 72 participated in the study: TT ( n = 37; age 27 ± 1 yr) and CT+CC ( n = 35; age 26 ± 1 yr). Forearm blood flow (venous occlusion plethysmography) and blood pressure (oscillometric automatic cuff) were evaluated at rest and during 30% handgrip exercise. Exercise training consisted of three sessions per week for 18 wk, with intensity between anaerobic threshold and respiratory compensation point. Resting forearm vascular conductance (FVC, P = 0.17) and mean blood pressure ( P = 0.70) were similar between groups. However, FVC responses during handgrip exercise were significantly lower in TT individuals compared with CT+CC individuals (0.39 ± 0.12 vs. 1.08 ± 0.27 units, P = 0.01). Exercise training significantly increased peak VO2 in both groups, but resting FVC remained unchanged. This intervention significantly increased FVC response to handgrip exercise in TT individuals ( P = 0.03), but not in CT+CC individuals ( P = 0.49), leading to an equivalent FVC response between TT and CT+CC individuals (1.05 ± 0.18 vs. 1.59 ± 0.27 units, P = 0.27). In conclusion, exercise training improves muscle vasodilatation in response to exercise in TT genotype individuals, demonstrating that genetic variants influence the effects of interventions such as exercise training.