Exercise Training and Epigenetic Regulation: Multilevel Modification and Regulation of Gene Expression

Functional nutrition for the health of exercising individuals and elite sportspersons

INTRODUCTION

Elite sportspersons who are involved in high-intensity physical sports indulge in severe training and competition schedules, which exposes them to high levels of inflammatory and oxidative stress, hence it may hamper their health sometimes. Disturbance in the health of sportspersons also induces compromised performances.

THE PREMISE FOR FUNCTIONAL NUTRITION

Functional nutrition is essential for elite sportspersons training for securing both rest and recovery to have proper health and anticipated performance. Apart from serving the energy needs of the sportspersons, the nutrition strategies should provide them with certain metabolic advantages, which provide greater health and immunity, to ensure proper training and competition. The diet of the sportspersons needs to contain appropriate anti-inflammatory and antioxidative nutrients, to ensure to reduction and control of the physiological stress of tissues during high-intensity physical sports, especially during marathon running. Preserving anabolic valence among sportspersons for muscle myokine optimization is an essential aspect of sports nutrition, which secures health and provides excellent performance potential. Preservation and optimization of gut microbiome among sportspersons enhance immune health and performance, through proper gut integrity and enhanced metabolic cascades. As the genes are to be properly expressed for excellent manifestation in protein synthesis and other metabolic signaling, achieving genetic valance through proper nutrition ensures the health of the sportspersons.

CONCLUSION

Functional nutrition seems a very necessary and potent factor in the training and competition aspects of elite sportspersons since nutrition not only provides recovery but also ensures proper health for elite sportspersons.

Genome-wide epigenetic modifications in sports horses during training as an adaptation phenomenon

With his bicentennial breeding history based on athletic performance, the Thoroughbred horse can be considered the equine sport breed. Although genomic and transcriptomic tools and knowledge are at the state of the art in equine species, the epigenome and its modifications in response to environmental stimuli, such as training, are less studied. One of the major epigenetic modifications is cytosine methylation at 5' of DNA molecules. This crucial biochemical modification directly mediates biological processes and, to some extent, determines the organisms' phenotypic plasticity. Exercise indeed affects the epigenomic state, both in humans and in horses. In this study, we highlight, with a genome-wide analysis of methylation, how the adaptation to training in the Thoroughbred can modify the methylation pattern throughout the genome. Twenty untrained horses, kept under the same environmental conditions and sprint training regimen, were recruited, collecting peripheral blood at the start of the training and after 30 and 90 days. Extracted leukocyte DNA was analyzed with the methylation content sensitive enzyme ddRAD (MCSeEd) technique for the first time applied to animal cells. Approximately one thousand differently methylated genomic regions (DMRs) and nearby genes were called, revealing that methylation changes can be found in a large part of the genome and, therefore, referable to the physiological adaptation to training. Functional analysis via GO enrichment was also performed. We observed significant differences in methylation patterns throughout the training stages: we hypothesize that the methylation profile of some genes can be affected early by training, while others require a more persistent stimulus.

Idiopathic inflammatory myopathy and non-coding RNA

Idiopathic inflammatory myopathies (IIMs) are common autoimmune diseases that affect skeletal muscle quality and function. The lack of an early diagnosis and treatment can lead to irreversible muscle damage. Non-coding RNAs (ncRNAs) play an important role in inflammatory transfer, muscle regeneration, differentiation, and regulation of specific antibody levels and pain in IIMs. ncRNAs can be detected in blood and hair; therefore, ncRNAs detection has great potential for diagnosing, preventing, and treating IIMs in conjunction with other methods. However, the specific roles and mechanisms underlying the regulation of IIMs and their subtypes remain unclear. Here, we review the mechanisms by which micro RNAs and long non-coding RNA-messenger RNA networks regulate IIMs to provide a basis for ncRNAs use as diagnostic tools and therapeutic targets for IIMs.

The Impact of Aerobic Exercise on HDL Quantity and Quality: A Narrative Review

High-density lipoproteins comprise roughly 25-30% of the circulating proteins involved in the transport of lipids in circulation. These particles differ in size and lipid composition. Recent evidence suggests that the quality of HDL particles (which depends on shape, size and the composition of proteins and lipids determining HDL functionality) may be more important than their quantity. The functionality of HDL is mirrored by its cholesterol efflux activity, as well as its antioxidant (including the protection of LDL against oxidation), anti-inflammatory and antithrombotic properties. The results of many studies and meta-analyses imply the beneficial impact of aerobic exercise on HDL-C levels. Physical activity was found to be usually associated with an increase in HDL cholesterol and a decrease in LDL cholesterol and triglycerides. Exercise, apart from inducing quantitative alterations in serum lipids, exerts a beneficial impact on HDL particle maturation, composition and functionality. The Physical Activity Guidelines Advisory Committee Report underlined the importance of establishing a program recommending exercises that enable attainment of maximal advantage at the lowest level of risk. The aim of this manuscript is to review the impact of different types of aerobic exercise (various intensities and durations) on the level and quality of HDL.

MicroRNAs as the Sentinels of Redox and Hypertrophic Signalling

Oxidative stress and inflammation are associated with skeletal muscle function decline with ageing or disease or inadequate exercise and/or poor diet. Paradoxically, reactive oxygen species and inflammatory cytokines are key for mounting the muscular and systemic adaptive responses to endurance and resistance exercise. Both ageing and lifestyle-related metabolic dysfunction are strongly linked to exercise redox and hypertrophic insensitivity. The adaptive inability and consequent exercise intolerance may discourage people from physical training resulting in a vicious cycle of under-exercising, energy surplus, chronic mitochondrial stress, accelerated functional decline and increased susceptibility to serious diseases. Skeletal muscles are malleable and dynamic organs, rewiring their metabolism depending on the metabolic or mechanical stress resulting in a specific phenotype. Endogenous RNA silencing molecules, microRNAs, are regulators of these metabolic/phenotypic shifts in skeletal muscles. Skeletal muscle microRNA profiles at baseline and in response to exercise have been observed to differ between adult and older people, as well as trained vs. sedentary individuals. Likewise, the circulating microRNA blueprint varies based on age and training status. Therefore, microRNAs emerge as key regulators of metabolic health/capacity and hormetic adaptability. In this narrative review, we summarise the literature exploring the links between microRNAs and skeletal muscle, as well as systemic adaptation to exercise. We expand a mathematical model of microRNA burst during adaptation to exercise through supporting data from the literature. We describe a potential link between the microRNA-dependent regulation of redox-signalling sensitivity and the ability to mount a hypertrophic response to exercise or nutritional cues. We propose a hypothetical model of endurance exercise-induced microRNA "memory cloud" responsible for establishing a landscape conducive to aerobic as well as anabolic adaptation. We suggest that regular aerobic exercise, complimented by a healthy diet, in addition to promoting mitochondrial health and hypertrophic/insulin sensitivity, may also suppress the glycolytic phenotype and mTOR signalling through miRNAs which in turn promote systemic metabolic health.

Aerobic Exercise Training-Induced Changes on DNA Methylation in Mild Cognitively Impaired Elderly African Americans: Gene, Exercise, and Memory Study - GEMS-I

BACKGROUND

DNA methylation at CpG sites is a vital epigenetic modification of the human genome affecting gene expression, and potentially, health outcomes. However, evidence is just budding on the effects of aerobic exercise-induced adaptation on DNA methylation in older mild cognitively impaired (MCI) elderly African American (AAs). Therefore, we examined the effects of a 6-month aerobic exercise-intervention on genome-wide DNA methylation in elderly AA MCI volunteers.

DESIGN

Elderly AA volunteers confirmed MCI assigned into a 6-month program of aerobic exercise (eleven participants) underwent a 40-min supervised-training 3-times/week and controls (eight participants) performed stretch training. Participants had maximal oxygen consumption (VO₂max) test and Genome-wide methylation levels at CpG sites using the Infinium HumanMethylation450 BeadChip assay at baseline and after a 6-month exercise program. We computed false discovery rates (FDR) using Sidak to account for multiplicity of tests and performed quantitative real-time polymerase chain-reaction (qRT-PCR) to confirm the effects of DNA methylations on expression levels of the top 5 genes among the aerobic participants. CpG sites identified from aerobic-exercise participants were similarly analyzed by the stretch group to quantify the effects of exercise-induced methylation changes among the group of stretch participants.

RESULTS

Eleven MCI participants (aerobic: 73% females; mean age 72.3 ± 6.6 years) and eight MCI participants (stretch: 75% female; mean age 70.6 ± 6.7 years) completed the training. Aerobic exercise-training was associated with increases in VO₂max and with global hypo- and hypermethylation changes. The most notable finding was CpG hypomethylation within the body of the VPS52 gene (P = 5.4 × 10^-26), a Golgi-associated protein, involved in intracellular protein trafficking including amyloid precursor protein. qRT-PCR confirmed a nearly twofold increased expression of VPS52. Other top findings with FDR q-value < 10^-5, include hypomethylations of SCARB1 (8.8 × 10^-25), ARTN (6.1 × 10^-25), NR1H2 (2.1 × 10^-18) and PPP2R5D (9.8 × 10^-18).

CONCLUSION

We conclude that genome-wide DNA methylation patterns is associated with exercise training-induced methylation changes. Identification of methylation changes around genes previously shown to interact with amyloid biology, intracellular protein trafficking, and lipoprotein regulations provide further support to the likely protective effect of exercise in MCI. Future studies in larger samples are needed to confirm our findings.

Impact of Physical Activity and Exercise on the Epigenome in Skeletal Muscle and Effects on Systemic Metabolism

Exercise and physical activity induces physiological responses in organisms, and adaptations in skeletal muscle, which is beneficial for maintaining health and preventing and/or treating most chronic diseases. These adaptations are mainly instigated by transcriptional responses that ensue in reaction to each individual exercise, either resistance or endurance. Consequently, changes in key metabolic, regulatory, and myogenic genes in skeletal muscle occur as both an early and late response to exercise, and these epigenetic modifications, which are influenced by environmental and genetic factors, trigger those alterations in the transcriptional responses. DNA methylation and histone modifications are the most significant epigenetic changes described in gene transcription, linked to the skeletal muscle transcriptional response to exercise, and mediating the exercise adaptations. Nevertheless, other alterations in the epigenetics markers, such as epitranscriptomics, modifications mediated by miRNAs, and lactylation as a novel epigenetic modification, are emerging as key events for gene transcription. Here, we provide an overview and update of the impact of exercise on epigenetic modifications, including the well-described DNA methylations and histone modifications, and the emerging modifications in the skeletal muscle. In addition, we describe the effects of exercise on epigenetic markers in other metabolic tissues; also, we provide information about how systemic metabolism or its metabolites influence epigenetic modifications in the skeletal muscle.

Plasma microRNA-320a as a Potential Biomarker of Physiological Changes during Training in Professional Volleyball Players

A deeper insight into the mechanisms responsible for athlete performance that may serve as specific and detailed training indicators is still desired, because conventionally used biomarkers provide limited information about the adaptive processes that occur during exercise. The objective of our study was to assess insulin-like growth factor 1 receptors (IGF1R) gene expression and evaluate plasma concentration of selected microRNAs (miRNAs) during a 10-week training period (sampling times: week 1, 4, 7, and 10) in a group of 12 professional female volleyball players. Circulating miRNAs (miR-223, miR-320a, and miR-486) with established concentration in plasma and documented association with the IGF1 signaling pathway, which is involved in muscle development and recovery, were tested. The levels of analyzed miRNAs, tested by one-way ANOVA, were significantly different between four training periods during a 10-week training cycle (miR-223 p < 0.0001, miR-320a p = 0.00021, miR-486 p = 0.0037, respectively). The levels of IGF1R also appeared to be different (p = 0.00092), and their expression showed a trend to increase between the first and third periods. In the fourth period, the expression decreased, although it was higher compared with the baseline. Correlations between concentration levels of miR-223 and miR-320a (rs = 0.54, p < 0.001), as well as between miR-320a and miR-486 (rs = 0.73, p < 0.001) were also found. In the fourth period, a negative correlation between miR-223 plasma level and leucocyte IGF1R expression was found (rs = -0.63, p = 0.028). Multiple linear regression analysis showed that miR-320a (p = 0.024) and creatine kinase (p = 0.028) had the greatest impact on the expression levels of the IGF1R gene. Future studies are required to define whether these miRNAs, especially miR-320a, as well as IGF1R expression could be useful biomarkers of physiological changes during exercise and to discover their detailed biological roles in mode-specific exercise training adaptations of professional athletes.

Air pollution and DNA methylation in adults: A systematic review and meta-analysis of observational studies

This systematic review and meta-analysis aimed to investigate the association between air pollution and DNA methylation in adults from published observational studies. PubMed, Web of Science and Embase databases were systematically searched for available studies on the association between air pollution and DNA methylation published up to March 9, 2021. Three DNA methylation approaches were considered: global methylation, candidate-gene, and epigenome-wide association studies (EWAS). Meta-analysis was used to summarize the combined estimates for the association between air pollutants and global DNA methylation levels. Heterogeneity was assessed with the Cochran Q test and quantified with the I² statistic. In total, 38 articles were included in this study: 16 using global methylation, 18 using candidate genes, and 11 using EWAS, with 7 studies using more than one approach. Meta-analysis revealed an imprecise but inverse association between exposure to PM_2.5 and global DNA methylation (for each 10-μg/m³ PM_2.5, combined estimate: 0.39; 95% confidence interval: 0.97 - 0.19). The candidate-gene results were consistent for the ERCC3 and SOX2 genes, suggesting hypermethylation in ERCC3 associated with benzene and that in SOX2 associated with PM_2.5 exposure. EWAS identified 201 CpG sites and 148 differentially methylated regions that showed differential methylation associated with air pollution. Among the 307 genes investigated in 11 EWAS, a locus in nucleoredoxin gene was found to be positively associated with PM_2.5 in two studies. Current meta-analysis indicates that PM_2.5 is imprecisely and inversely associated with DNA methylation. The candidate-gene results consistently suggest hypermethylation in ERCC3 associated with benzene exposure and that in SOX2 associated with PM_2.5 exposure. The Kyoto Encyclopedia of Genes and Genomes (KEGG) network analyses revealed that these genes were associated with African trypanosomiasis, Malaria, Antifolate resistance, Graft-versus-host disease, and so on. More evidence is needed to clarify the association between air pollution and DNA methylation.

Ultra performance liquid chromatography-tandem mass spectrometry assay for the quantification of RNA and DNA methylation

Previous studies have reported that nucleic acid methylation is a critical element in cardiovascular disease, and most studies mainly focused on sequencing and biochemical research. Here we developed an Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method for the quantification analysis of the dissociative epigenetic modified nucleosides (5mdC, 5mrC, m⁶A) in Myocardial Infarction (MI) SD rats from different periods (1 week, 4 weeks, 8 weeks) after the surgery. The samples for analysis were obtained from heart tissue and blood of the rats. All the quantification results are compared with the sham-operated group. Total RNA and DNA were isolated by enzymatic hydrolytic methods before the UPLC-MS/MS analysis. The statistical analysis demonstrates the dynamic changes of modified nucleosides in MI rats, and it showed good specificity, accuracy, stability and less samples were needed in the method. In this paper, we discovered that the concentration of 5mdC, 5mrC, m⁶A from heart tissue significantly increased at 8 weeks after the surgery. Furthermore, UPLC-MS/MS helps us observe the similar change of the concentration of those 3 methylated biomarkers in peripheral blood after 8 weeks. The result shows that the dynamic process of those 3 methylated biomarkers in peripheral blood is related to the content of methylated biomarkers from the heart tissue. Based on the scientific evidence available, we proved that the methylation of genetic materials in peripheral blood is similar to myocardial infarction tissue. The relation between them indicates that peripheral blood could be a promising alternative to the heart tissue which monitor the level of methylation and MI diagnosis-aided.

Non-Coding RNAs in the Transcriptional Network That Differentiates Skeletal Muscles of Sedentary from Long-Term Endurance- and Resistance-Trained Elderly

In a previous study, the whole transcriptome of the vastus lateralis muscle from sedentary elderly and from age-matched athletes with an exceptional record of high-intensity, life-long exercise training was compared-the two groups representing the two extremes on a physical activity scale. Exercise training enabled the skeletal muscle to counteract age-related sarcopenia by inducing a wide range of adaptations, sustained by the expression of protein-coding genes involved in energy handling, proteostasis, cytoskeletal organization, inflammation control, and cellular senescence. Building on the previous study, we examined here the network of non-coding RNAs participating in the orchestration of gene expression and identified differentially expressed micro- and long-non-coding RNAs and some of their possible targets and roles. Unsupervised hierarchical clustering analyses of all non-coding RNAs were able to discriminate between sedentary and trained individuals, regardless of the exercise typology. Validated targets of differentially expressed miRNA were grouped by KEGG analysis, which pointed to functional areas involved in cell cycle, cytoskeletal control, longevity, and many signaling pathways, including AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), which had been shown to be pivotal in the modulation of the effects of high-intensity, life-long exercise training. The analysis of differentially expressed long-non-coding RNAs identified transcriptional networks, involving lncRNAs, miRNAs and mRNAs, affecting processes in line with the beneficial role of exercise training.

The Regulation of Fat Metabolism During Aerobic Exercise

Since the lipid profile is altered by physical activity, the study of lipid metabolism is a remarkable element in understanding if and how physical activity affects the health of both professional athletes and sedentary subjects. Although not fully defined, it has become clear that resistance exercise uses fat as an energy source. The fatty acid oxidation rate is the result of the following processes: (a) triglycerides lipolysis, most abundant in fat adipocytes and intramuscular triacylglycerol (IMTG) stores, (b) fatty acid transport from blood plasma to muscle sarcoplasm, (c) availability and hydrolysis rate of intramuscular triglycerides, and (d) transport of fatty acids through the mitochondrial membrane. In this review, we report some studies concerning the relationship between exercise and the aforementioned processes also in light of hormonal controls and molecular regulations within fat and skeletal muscle cells.

Maternal physical activity significantly alters the placental transcriptome

INTRODUCTION

Maternal lifestyle, in particular physical activity (PA), influences many of the physiological adaptations during pregnancy associated with feto-placental development and growth. There is limited to no information on the link between PA during pregnancy and the molecular mechanisms governing placental function. The aim of this study was to investigate the molecular mechanisms through which maternal PA may influence placental function.

METHODS

The level of PA was measured by accelerometry and gene expression was measured in term placenta with custom polymerase chain reaction (PCR) arrays and microarray analysis followed by a pathway analyses on significantly differentially expressed genes (DEGs).

RESULTS

Microarray analysis showed 43 significantly DEGs between active and non-active participants. RT-qPCR validation of a sub-sample of DEGs revealed significant changes in the level of expression between active and non-active moms (student's t-test, p < 0.05, n = 11). Genes involved in transport of water (p = 0.00236) and uptake of glycerol (p = 0.00219) were enriched in active moms. PA was also associated with the alteration of alternative splicing patters. The most consistent splicing changes were observed for AQP9 where active moms lacked exon 2.

DISCUSSION

Variations in maternal PA influences placental gene. We show significant expression changes of genes that are involved in transport and localization between active and non-active women. Most notably, the expression of the aquaporin family of genes (e.g. AQP1 and AQP9) were found to be significantly higher in the placentas of active women suggesting an adaptive response for the transport of water and glycerol in this population.

Laboratory medicine: health evaluation in elite athletes

The need to evaluate the health status of an athlete represents a crucial aim in preventive and protective sports science in order to identify the best diagnostic strategy to improve performance and reduce risks related to physical exercise. In the present review we aim to define the main biochemical and haematological markers that vary significantly during and after sports training to identify risk factors, at competitive and professional levels and to highlight the set up of a specific parameter's panel for elite athletes. Moreover, we also intend to consider additional biomarkers, still under investigation, which could further contribute to laboratory sports medicine and provide reliable data that can be used by athlete's competent staff in order to establish personal attitudes and prevent sports injuries.

Long Non-Coding RNA DUXAP8 Facilitates Cell Viability, Migration, and Glycolysis in Non-Small-Cell Lung Cancer via Regulating HK2 and LDHA by Inhibition of miR-409-3p

Purpose

Long non-coding RNAs (lncRNAs) were confirmed to play important roles in human cancers. In this study, we explored the functional role of lncRNA double homeobox A pseudogene 8 (DUXAP8) in non-small-cell lung cancer (NSCLC).

Methods

Real-time quantitative PCR (RT-qPCR) was used to detect DUXAP8 and microRNA-409-3p (miR-409-3p) expression. CCK-8, cell colony formation assay, and Transwell migration assay were performed to measure cell growth and migration, respectively. The expression of the relative proteins was detected by Western blot. Cell glycolysis was determined by glucose uptake, adenosine triphosphate (ATP) concentration, lactate generation, extracellular acidification rate and oxygen consumption rate assays. Bioinformatics analysis and dual-luciferase reporter assay were used to measure the interaction among DUXAP8, miR-409-3p, hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA). In vivo, subcutaneous tumor formation assay was performed in the nude mice.

Results

DUXAP8 was highly expressed in NSCLC, while miR-409-3p was downregulated. High expression of DUXAP8 was positively related to the grade division and negatively associated with the 5-year survival rate of NSCLC patients. Downregulated DUXAP8 significantly suppressed cell growth, metastasis and glycolysis. Besides, DUXAP8 sponged miR-409-3p to promote HK2 and LDHA expression. DUXAP8 promoted cell viability, migration and glycolysis by regulating miR-409-3p/HK2/LDHA axis. Moreover, DUXAP8 downregulation markedly inhibited tumor growth in vivo.

Conclusion

Our findings demonstrated that DUXAP8 served as an oncogene in the progression of NSCLC.

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.

Physical Exercise and Epigenetic Modifications in Skeletal Muscle

Physical activity and sports play major roles in the overall health status of humans. It is well known that regular exercise helps to lower the risk for a broad variety of health problems, such as cardiovascular disease, type 2 diabetes, and cancer. Being physically active induces a wide variety of molecular adaptations, for example fiber type switches or other metabolic alterations, in skeletal muscle tissue. These adaptations are based on exercise-induced changes to the skeletal muscle transcriptome. Understanding their nature is crucial to improve the development of exercise-based therapeutic strategies. Recent research indicates that specifically epigenetic mechanisms, i.e., pathways that induce changes in gene expression patterns without altering the DNA base sequence, might play a major role in controlling skeletal muscle transcriptional patterns. Epigenetic mechanisms include DNA and histone modifications, as well as expression of specific microRNAs. They can be modulated by environmental factors or external stimuli, such as exercise, and eventually induce specific and fine-tuned changes to the transcriptional response. In this review, we highlight current knowledge on epigenetic changes induced in exercising skeletal muscle, their target genes, and resulting phenotypic changes. In addition, we raise the question of whether epigenetic modifications might serve as markers for the design and management of optimized and individualized training protocols, as prognostic tools to predict training adaptation, or even as targets for the design of "exercise mimics".

Genetic Networks Underlying Natural Variation in Basal and Induced Activity Levels in Drosophila melanogaster

Exercise is recommended by health professionals across the globe as part of a healthy lifestyle to prevent and/or treat the consequences of obesity. While overall, the health benefits of exercise and an active lifestyle are well understood, very little is known about how genetics impacts an individual's inclination for and response to exercise. To address this knowledge gap, we investigated the genetic architecture underlying natural variation in activity levels in the model system Drosophila melanogaster Activity levels were assayed in the Drosophila Genetics Reference Panel fly strains at baseline and in response to a gentle exercise treatment using the Rotational Exercise Quantification System. We found significant, sex-dependent variation in both activity measures and identified over 100 genes that contribute to basal and induced exercise activity levels. This gene set was enriched for genes with functions in the central nervous system and in neuromuscular junctions and included several candidate genes with known activity phenotypes such as flightlessness or uncoordinated movement. Interestingly, there were also several chromatin proteins among the candidate genes, two of which were validated and shown to impact activity levels. Thus, the study described here reveals the complex genetic architecture controlling basal and exercise-induced activity levels in D. melanogaster and provides a resource for exercise biologists.

Effects of aerobic and inspiratory training on skeletal muscle microRNA-1 and downstream-associated pathways in patients with heart failure

BACKGROUND

The exercise intolerance in chronic heart failure with reduced ejection fraction (HFrEF) is mostly attributed to alterations in skeletal muscle. However, the mechanisms underlying the skeletal myopathy in patients with HFrEF are not completely understood. We hypothesized that (i) aerobic exercise training (AET) and inspiratory muscle training (IMT) would change skeletal muscle microRNA-1 expression and downstream-associated pathways in patients with HFrEF and (ii) AET and IMT would increase leg blood flow (LBF), functional capacity, and quality of life in these patients.

METHODS

Patients age 35 to 70 years, left ventricular ejection fraction (LVEF) ≤40%, New York Heart Association functional classes II-III, were randomized into control, IMT, and AET groups. Skeletal muscle changes were examined by vastus lateralis biopsy. LBF was measured by venous occlusion plethysmography, functional capacity by cardiopulmonary exercise test, and quality of life by Minnesota Living with Heart Failure Questionnaire. All patients were evaluated at baseline and after 4 months.

RESULTS

Thirty-three patients finished the study protocol: control (n = 10; LVEF = 25 ± 1%; six males), IMT (n = 11; LVEF = 31 ± 2%; three males), and AET (n = 12; LVEF = 26 ± 2%; seven males). AET, but not IMT, increased the expression of microRNA-1 (P = 0.02; percent changes = 53 ± 17%), decreased the expression of PTEN (P = 0.003; percent changes = -15 ± 0.03%), and tended to increase the p-AKT^ser473 /AKT ratio (P = 0.06). In addition, AET decreased HDAC4 expression (P = 0.03; percent changes = -40 ± 19%) and upregulated follistatin (P = 0.01; percent changes = 174 ± 58%), MEF2C (P = 0.05; percent changes = 34 ± 15%), and MyoD expression (P = 0.05; percent changes = 47 ± 18%). AET also increased muscle cross-sectional area (P = 0.01). AET and IMT increased LBF, functional capacity, and quality of life. Further analyses showed a significant correlation between percent changes in microRNA-1 and percent changes in follistatin mRNA (P = 0.001, rho = 0.58) and between percent changes in follistatin mRNA and percent changes in peak VO₂ (P = 0.004, rho = 0.51).

CONCLUSIONS

AET upregulates microRNA-1 levels and decreases the protein expression of PTEN, which reduces the inhibitory action on the PI3K-AKT pathway that regulates the skeletal muscle tropism. The increased levels of microRNA-1 also decreased HDAC4 and increased MEF2c, MyoD, and follistatin expression, improving skeletal muscle regeneration. These changes associated with the increase in muscle cross-sectional area and LBF contribute to the attenuation in skeletal myopathy, and the improvement in functional capacity and quality of life in patients with HFrEF. IMT caused no changes in microRNA-1 and in the downstream-associated pathway. The increased functional capacity provoked by IMT seems to be associated with amelioration in the respiratory function instead of changes in skeletal muscle. ClinicalTrials.gov (Identifier: NCT01747395).

Epigenetic changes in healthy human skeletal muscle following exercise- a systematic review

Exercise training is continually challenging whole-body homeostasis, leading to improvements in performance and health. Adaptations to exercise training are complex and are influenced by both environmental and genetic factors. Epigenetic factors regulate gene expression in a tissue-specific manner and constitute a link between the genotype and the environment. Moreover, epigenetic factors are emerging as potential biomarkers that could predict the response to exercise training. This systematic review aimed to identify epigenetic changes that have been reported in skeletal muscle following exercise training in healthy populations. A literature search of five databases (PUBMED, MEDLINE, CINHAL, SCOPUS and SportDiscuss) was conducted in November 2018. Articles were included if they examined epigenetic modifications (DNA methylation, histone modifications and non-coding RNAs) in skeletal muscle, following either an acute bout of exercise, an exercise intervention in a pre/post design, or a case/control type of study. Twenty-two studies met the inclusion criteria. Several epigenetic markers including DNA methylation of genes known to be differentially expressed after exercise and myomiRs were reported to be modified after exercise. Several epigenetic marks were identified to be altered in response to exercise, with potential influence on skeletal muscle metabolism. However, whether these epigenetic marks play a role in the physiological impact of exercise is unclear. Exercise epigenetics is still a very young research field, and it is expected that in the future the causality of such changes will be elucidated via the utilization of emerging experimental models able to target the epigenome.

Physical Activity, Global DNA Methylation, and Breast Cancer Risk: A Systematic Literature Review and Meta-analysis

The extent to which physical activity reduces breast cancer risk through changes in global DNA methylation is unknown. We systematically identified studies that investigated the association between: (i) physical activity and global DNA methylation; or (ii) global DNA methylation and breast cancer risk. Associations were quantified using random-effects models. Heterogeneity was investigated through subgroup analyses and the Q-test and I ² statistics. Twenty-four studies were reviewed. We observed a trend between higher levels of physical activity and higher levels of global DNA methylation [pooled standardized mean difference = 0.19; 95% confidence interval (CI), -0.03-0.40; P = 0.09] which, in turn, had a suggestive association with a reduced breast cancer risk (pooled relative risk = 0.70; 95% CI, 0.49-1.02; P = 0.06). In subgroup analyses, a positive association between physical activity and global DNA methylation was observed among studies assessing physical activity over long periods of time (P = 0.02). Similarly, the association between global DNA methylation and breast cancer was statistically significant for prospective cohort studies (P = 0.007). Despite the heterogeneous evidence base, the literature suggests that physical activity reduces the risk of breast cancer through increased global DNA methylation. This study is the first to systematically overview the complete biologic pathway between physical activity, global DNA methylation, and breast cancer. Cancer Epidemiol Biomarkers Prev; 27(11); 1320-31. ©2018 AACR.

Cardiovascular Adaptations Induced by Resistance Training in Animal Models

In the last 10 years the number of studies showing the benefits of resistance training (RT) to the cardiovascular system, have grown. In comparison to aerobic training, RT-induced favorable adaptations to the cardiovascular system have been ignored for many years, thus the mechanisms of the RT-induced cardiovascular adaptations are still uncovered. The lack of animal models with comparable protocols to the RT performed by humans hampers the knowledge. We have used squat-exercise model, which is widely used by many others laboratories. However, to a lesser extent, other models are also employed to investigate the cardiovascular adaptations. In the subsequent sections we will review the information regarding cardiac morphological adaptations, signaling pathway of the cardiac cell, cardiac function and the vascular adaptation induced by RT using this animal model developed by Tamaki et al. in 1992. Furthermore, we also describe cardiovascular findings observed using other animal models of RT.