Circulating exosome-like vesicle and skeletal muscle microRNAs are altered with age and resistance training

Exercise alleviates osteoporosis by regulating the secretion of the Senescent Associated Secretory Phenotype

As the elderly population grows, the number of patients with metabolic bone diseases such as osteoporosis has increased sharply, posing a significant threat to public health and social economics. Although pharmacological therapies for osteoporosis demonstrate therapeutic benefits, their prolonged use is associated with varying degrees of adverse effects. As a non-pharmacological intervention, exercise is widely recognized for its cost-effectiveness, safety, and lack of toxic side effects, making it a recommended treatment for osteoporosis prevention and management. Previous studies have demonstrated that exercise can improve metabolic bone diseases by modulating the Senescent Associated Secretory Phenotype (SASP). However, the mechanisms through which exercise influences SASP remain unclear. Therefore, this review aims to summarize the effects of exercise on SASP and elucidate the specific mechanisms by which exercise regulates SASP to alleviate osteoporosis, providing a theoretical basis for osteoporosis through exercise and developing targeted therapies.

Skeletal muscle growth to combat diabetes and obesity: the potential role of muscle-secreted factors

As the prevalence of obesity and metabolic disease continues to climb, the need for effective therapeutic interventions remains high. The growth of skeletal muscle (SkM) greatly influences systemic metabolism across the whole body, making this tissue an important therapeutic target to combat the rise of metabolic dysfunction. Transgenic rodent models of targeted SkM growth exhibit profound improvements in various remote tissues, including adipose tissue and the liver. It is currently unclear how selective stimulation of SkM growth alters the metabolism of distant tissues; however, evidence suggests that muscle-secreted factors may be involved. Here, we aim to provide basic biomedical researchers with a summary of the current knowledge regarding various muscle-secreted factors regulated by anabolic pathways and proteins in SkM, as well as their systemic metabolic effects, to implicate them in the whole-body metabolic effects of SkM growth. In this review, we also identify several knowledge gaps in this field, future directions of investigation, and implications for therapeutic interventions such as resistance exercise and pharmacology.

Molecular mechanisms and potential interventions during aging-associated sarcopenia

Sarcopenia, a common condition observed in the elderly, presenting a significant public health challenge due to its high prevalence, insidious onset and diverse systemic effects. Despite ongoing research, the precise etiology of sarcopenia remains elusive. Aging-related processes, which included inflammation, oxidative stress, compromised mitochondrial function and apoptosis, have been implicated in its development. Notably, effective pharmacological treatments for sarcopenia are currently lacking, highlighting the necessity for a deeper understanding of its pathogenesis and causative factors to enable proactive interventions. This article is aimed to provide an extensive overview of the pathogenesis of sarcopenia, along with a summary of current treatment and prevention strategies.

Combination of transcriptomics and proteomics for analyzing potential biomarker and molecular mechanism underlying skeletal muscle atrophy

BACKGROUND

The skeletal muscle atrophy is prevalently occurred in numerous chronic disease complications. Despite its important clinical significance, there are currently no therapeutic drugs, so new biomarkers and molecular mechanisms need to be discovered urgently.

METHODS

Transcriptome and proteome sequencing data were collected from normal and skeletal muscle atrophic mice. The differentially expressed genes (DEGs) and proteins (DEPs) were analyzed. Applying PPI analysis to obtain overlapping genes and proteins, which were next subjected to GO and KEGG enrichment analysis. Combined analysis of transcriptomics and proteomics was performed to get key genes that were simultaneously found in GO and KEGG enrichment results. Subsequently, RT-qPCR and immunofluorescence were constructed to verify the expression of screened key genes.

RESULTS

By combination of transcriptomics, proteomics and RT-qPCR results, we identified 14 key genes (Cav1, Col3a1, Dnaja1, Postn, Ptges3, Cd44, Clec3b, Igfbp6, Lamc1, Alb, Itga6, Mmp2, Timp2 and Cd9) that were markedly different in atrophic mice. Single-gene GSEA and immunofluorescence suggested Cd9 was probably the biomarker for skeletal muscle atrophy.

CONCLUSIONS

Our study hinted that Cd9 was potential biomarker and may interfere with skeletal muscle atrophy through process of aerobic respiration, oxidative phosphorylation, and metabolism of amino acids and fatty acids.

SIGNIFICANCE

The present study holds the subsequent significance: Frist, we investigated biomarkers for skeletal muscle atrophy using multi-omics approach. A total of 14 genes were markedly different in skeletal muscle atrophic mice. We finally found Cd9 is a potential biomarker for skeletal muscle atrophy. Our work presents novel biomarkers and potential regulatory mechanisms for the early detection and intervention of muscle atrophy.

Recent Advances of Exosomes Derived from Skeletal Muscle and Crosstalk with Other Tissues

Skeletal muscle plays a crucial role in movement, metabolism, and energy homeostasis. As the most metabolically active endocrine organ in the body, it has recently attracted widespread attention. Skeletal muscle possesses the ability to release adipocytokines, bioactive peptides, small molecular metabolites, nucleotides, and other myogenic cell factors; some of which have been shown to be encapsulated within small vesicles, particularly exosomes. These skeletal muscle exosomes (SKM-Exos) are released into the bloodstream and subsequently interact with receptor cell membranes to modulate the physiological and pathological characteristics of various tissues. Therefore, SKM-Exos may facilitate diverse interactions between skeletal muscle and other tissues while also serving as biomarkers that reflect the physiological and pathological states of muscle function. This review delves into the pivotal role and intricate molecular mechanisms of SKM-Exos and its derived miRNAs in the maturation and rejuvenation of skeletal muscle, along with their intercellular signaling dynamics and physiological significance in interfacing with other tissues.

Emerging Targets and Treatments for Sarcopenia: A Narrative Review

BACKGROUND

Sarcopenia is characterized by the progressive loss of skeletal muscle mass, strength, and function, significantly impacting overall health and quality of life in older adults. This narrative review explores emerging targets and potential treatments for sarcopenia, aiming to provide a comprehensive overview of current and prospective interventions.

METHODS

The review synthesizes current literature on sarcopenia treatment, focusing on recent advancements in muscle regeneration, mitochondrial function, nutritional strategies, and the muscle-microbiome axis. Additionally, pharmacological and lifestyle interventions targeting anabolic resistance and neuromuscular junction integrity are discussed.

RESULTS

Resistance training and adequate protein intake remain the cornerstone of sarcopenia management. Emerging strategies include targeting muscle regeneration through myosatellite cell activation, signaling pathways, and chronic inflammation control. Gene editing, stem cell therapy, and microRNA modulation show promise in enhancing muscle repair. Addressing mitochondrial dysfunction through interventions aimed at improving biogenesis, ATP production, and reducing oxidative stress is also highlighted. Nutritional strategies such as leucine supplementation and anti-inflammatory nutrients, along with dietary modifications and probiotics targeting the muscle-microbiome interplay, are discussed as potential treatment options. Hydration and muscle-water balance are emphasized as critical in maintaining muscle health in older adults.

CONCLUSIONS

A combination of resistance training, nutrition, and emerging therapeutic interventions holds potential to significantly improve muscle function and overall health in the aging population. This review provides a detailed exploration of both established and novel approaches for the prevention and management of sarcopenia, highlighting the need for further research to optimize these strategies.

Research Progress on the Effect and Mechanism of Exercise Intervention on Sarcopenia Obesity

With the increasingly severe situation of obesity and population aging, there is growing concern about sarcopenia obesity (SO). SO refers to the coexistence of obesity and sarcopenia, which imposes a heavier burden on individuals and society compared to obesity or sarcopenia alone. Therefore, comprehending the pathogenesis of SO and implementing effective clinical interventions are vital for its prevention and treatment. This review uses a comprehensive literature search and analysis of PubMed, Web of Science, and CNKI databases, with search terms including "Sarcopenic obesity", "exercise", "cytokines", "inflammation", "mitochondrial quality control", and "microRNA", covering relevant studies published up to July 2024. The results indicate that the pathogenesis of SO is complex, involving mechanisms like age-related changes in body composition, hormonal alterations, inflammation, mitochondrial dysfunction, and genetic and epigenetic factors. Regarding exercise interventions for SO, aerobic exercise can reduce fat mass, resistance exercise can increase skeletal muscle mass and strength, and combined exercise can achieve both, making it the optimal intervention for SO. The potential mechanisms by which exercise may prevent and treat SO include regulating cytokine secretion, inhibiting inflammatory pathways, improving mitochondrial quality, and mediating microRNA expression. This review emphasizes the effectiveness of exercise interventions in mitigating sarcopenic obesity through comprehensive analysis of its multifactorial pathogenesis and the mechanistic insights into exercise's therapeutic effects. Understanding these mechanisms informs targeted therapeutic strategies aimed at alleviating the societal and individual burdens associated with SO.

From sweat to hope: The role of exercise-induced extracellular vesicles in cancer prevention and treatment

The benefits of regular physical exercise on cancer prevention, as well as reducing fatigue, treatment side effects and recurrence, and improving quality of life and overall survival of cancer patients, are increasingly recognised. Initial studies showed that the concentration of extracellular vesicles (EVs) increases during physical activity and that EVs carry biologically active cargo. These EVs are released by blood cells, skeletal muscle and other organs involved in exercise, thus suggesting that EVs may mediate tissue crosstalk during exercise. This possibility triggered a great interest in the study of the roles of EVs in systemic adaptation to exercise and in their potential applications in the prevention and treatment of various diseases, including cancer. This review presents studies exploring the concentration and molecular cargo of EVs released during exercise. Furthermore, we discuss putative stimuli that may trigger EV release from various cell types, the biological functions and the impact of exercise-induced EVs on cancer development and progression. Understanding the interplay between exercise, EVs, and cancer biology may offer insights into novel therapeutic strategies and preventive measures for cancer.

Extracellular vesicles may provide an alternative detoxification pathway during skeletal muscle myoblast ageing

Skeletal muscle (SM) acts as a secretory organ, capable of releasing myokines and extracellular vesicles (SM-EVs) that impact myogenesis and homeostasis. While age-related changes have been previously reported in murine SM-EVs, no study has comprehensively profiled SM-EV in human models. To this end, we provide the first comprehensive comparison of SM-EVs from young and old human primary skeletal muscle cells (HPMCs) to map changes associated with SM ageing. HPMCs, isolated from young (24 ± 1.7 years old) and older (69 ± 2.6 years old) participants, were immunomagnetically sorted based on the presence of the myogenic marker CD56 (N-CAM) and cultured as pure (100% CD56+) or mixed populations (MP: 90% CD56+). SM-EVs were isolated using an optimised protocol combining ultrafiltration and size exclusion chromatography (UF + SEC) and their biological content was extensively characterised using Raman spectroscopy (RS) and liquid chromatography mass spectrometry (LC-MS). Minimal variations in basic EV parameters (particle number, size, protein markers) were observed between young and old populations. However, biochemical fingerprinting by RS highlighted increased protein (amide I), lipid (phospholipids and phosphatidylcholine) and hypoxanthine signatures for older SM-EVs. Through LC-MS, we identified 84 shared proteins with functions principally related to cell homeostasis, muscle maintenance and transcriptional regulation. Significantly, SM-EVs from older participants were comparatively enriched in proteins involved in oxidative stress and DNA/RNA mutagenesis, such as E3 ubiquitin-protein ligase TTC3 (TTC3), little elongation complex subunit 1 (ICE1) and Acetyl-CoA carboxylase 1 (ACACA). These data suggest SM-EVs could provide an alternative pathway for homeostasis and detoxification during SM ageing.

Myogenic microRNAs as Therapeutic Targets for Skeletal Muscle Mass Wasting in Breast Cancer Models

Breast cancer is the type of cancer with the highest prevalence in women worldwide. Skeletal muscle atrophy is an important prognostic factor in women diagnosed with breast cancer. This atrophy stems from disrupted skeletal muscle homeostasis, triggered by diminished anabolic signalling and heightened inflammatory conditions, culminating in an upregulation of skeletal muscle proteolysis gene expression. The importance of delving into research on modulators of skeletal muscle atrophy, such as microRNAs (miRNAs), which play a crucial role in regulating cellular signalling pathways involved in skeletal muscle protein synthesis and degradation, has been recognised. This holds true for conditions of homeostasis as well as pathologies like cancer. However, the determination of specific miRNAs that modulate skeletal muscle atrophy in breast cancer conditions has not yet been explored. In this narrative review, we aim to identify miRNAs that could directly or indirectly influence skeletal muscle atrophy in breast cancer models to gain an updated perspective on potential therapeutic targets that could be modulated through resistance exercise training, aiming to mitigate the loss of skeletal muscle mass in breast cancer patients.

Healthy blood, healthy brain: a window into understanding and treating neurodegenerative diseases

Our limited understanding of complex neurodegenerative disorders has held us back on the development of efficient therapies. While several approaches are currently being considered, it is still unclear what will be most successful. Among the latest and more novel ideas, the concept of blood or plasma transfusion from young healthy donors to diseased patients is gaining momentum and attracting attention beyond the scientific arena. While young or healthy blood is enriched with protective and restorative components, blood from older subjects may accumulate neurotoxic agents or be impoverished of beneficial factors. In this commentary, we present an overview of the compelling evidence collected in various animal models of brain diseases (e.g., Alzheimer, Parkinson, Huntington) to the actual clinical trials that have been conducted to test the validity of blood-related treatments in neurodegenerative diseases and argue in favor of such approach.

Non-coding RNAs in exercise immunology: A systematic review

Regular physical exercise has been recognized as a potent modulator of immune function, with its effects including enhanced immune surveillance, reduced inflammation, and improved overall health. While strong evidence exists that physical exercise affects the specific expression and activity of non-coding RNAs (ncRNAs) also involved in immune system regulation, heterogeneity in individual study designs and analyzed exercise protocols exists, and a condensed list of functional, exercise-dependent ncRNAs with known targets in the immune system is missing from the literature. A systematic review and qualitative analysis was used to identify and categorize ncRNAs participating in immune modulation by physical exercise. Two combined approaches were used: (a) a systematic literature search for "ncRNA and exercise immunology", (b) and a database search for microRNAs (miRNAs) (miRTarBase and DIANA-Tarbase v8) aligned with known target genes in the immune system based on the Reactome database, combined with a systematic literature search for "ncRNA and exercise". Literature searches were based on PubMed, Web of Science, and SPORTDiscus; and miRNA databases were filtered for targets validated by in vitro experimental data. Studies were eligible if they reported on exercise-based interventions in healthy humans. After duplicate removal, 95 studies were included reporting on 164 miRNAs, which were used for the qualitative synthesis. Six studies reporting on long-noncoding RNAs (lncRNAs) or circular RNAs were also identified. Results were analyzed using ordering tables that included exercise modality (endurance/resistance exercise), acute or chronic interventions, as well as the consistency in reported change between studies. Evaluation criteria were defined as "validated" with 100% of ≥3 independent studies showing identical direction of regulation, "plausible" (≥80%), or "suggestive" (≥70%). For resistance exercise, upregulation of miR-206 was validated while downregulation of miR-133a appeared plausible. For endurance exercise, 15 miRNAs were categorized as validated, with 12 miRNAs being consistently elevated and 3 miRNAs being downregulated, most of them after acute exercise training. In conclusion, our approach provides evidence that miRNAs play a major role in exercise-induced effects on the innate and adaptive immune system by targeting different pathways affecting immune cell distribution, function, and trafficking as well as production of (anti-)inflammatory cytokines. miRNAs miR-15, miR-29c, miR-30a, miR-142/3, miR-181a, and miR-338 emerged as key players in mediating the immunomodulatory effects of exercise predominantly after acute bouts of endurance exercise.

Exosomal miR206 Secreted From Growing Muscle Promotes Angiogenic Response in Endothelial Cells

BACKGROUND

Resistance exercise is beneficial in patients with lower extremity arterial disease. Muscle-derived exosomes contain many types of signaling molecules, including microRNAs (miRNAs). Here, we tested the hypothesis that exosomal miRNAs secreted by growing muscles promote an angiogenic response in endothelial cells (ECs).

METHODS AND RESULTS

Skeletal muscle-specific conditional Akt1 transgenic (Akt1-TG) mice, in which skeletal muscle growth can be induced were used as a model of resistance training. Remarkable skeletal muscle growth was observed in mice 2 weeks after gene activation. The protein amount in exosomes secreted by growing muscles did not differ between Akt1-TG and control mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway frequency analysis of 4,665 target genes, identified using an miRNA array miRNAs, revealed a significant increase in Akt and its downstream signaling pathway genes. Among the upregulated miRNAs, miR1, miR133, and miR206 were significantly upregulated in the serum of Akt1-TG mice. miR206 was also increased in insulin-like growth factor (IGF)-1-stimulated hypertrophied myotubes. Exogenous supplementation of exosomal miR206 to human umbilical vein ECs promoted angiogenesis, as assessed using the spheroid assay, and increased the expression of angiogenesis-related transcripts.

CONCLUSIONS

Exosomal miR206 is upregulated in the blood of Akt1-TG mice and in IGF-stimulated cultured myotubes. Exogenous supplementation of miR206 promoted an angiogenic response in ECs. Our data suggest that miR206 secreted from growing muscles acts on ECs and promotes angiogenesis.

The role of non-coding RNAs in muscle aging: regulatory mechanisms and therapeutic potential

Muscle aging is a complex physiological process that leads to the progressive decline in muscle mass and function, contributing to debilitating conditions in the elderly such as sarcopenia. In recent years, non-coding RNAs (ncRNAs) have been increasingly recognized as major regulators of muscle aging and related cellular processes. Here, we comprehensively review the emerging role of ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in the regulation of muscle aging. We also discuss how targeting these ncRNAs can be explored for the development of novel interventions to combat age-related muscle decline. The insights provided in this review offer a promising avenue for future research and therapeutic strategies aimed at improving muscle health during aging.

Converging protective pathways: Exploring the linkage between physical exercise, extracellular vesicles and oxidative stress

Physical Exercise (EXR) has been shown to have numerous beneficial effects on various systems in the human body. It leads to a decrease in the risk of mortality from chronic diseases, such as cardiovascular disease, cancer, metabolic and central nervous system disorders. EXR results in improving cardiovascular fitness, cognitive function, immune activity, endocrine action, and musculoskeletal health. These positive effects make EXR a valuable intervention for promoting overall health and well-being in individuals of all ages. These beneficial effects are partially mediated by the role of the regular EXR in the adaptation to redox homeostasis counteracting the sudden increase of ROS, the hallmark of many chronic diseases. EXR can trigger the release of numerous humoral factors, e.g. protein, microRNA (miRs), and DNA, that can be shuttled as cargo of Extracellular vesicles (EVs). EVs show different cargo modification after oxidative stress stimuli as well as after EXR. In this review, we aim to highlight the main studies on the role of EVs released during EXR and oxidative stress conditions in enhancing the antioxidant enzymes pathway and in the decrease of oxidative stress environment mediated by their cargo.

Exercise metabolism and adaptation in skeletal muscle

Viewing metabolism through the lens of exercise biology has proven an accessible and practical strategy to gain new insights into local and systemic metabolic regulation. Recent methodological developments have advanced understanding of the central role of skeletal muscle in many exercise-associated health benefits and have uncovered the molecular underpinnings driving adaptive responses to training regimens. In this Review, we provide a contemporary view of the metabolic flexibility and functional plasticity of skeletal muscle in response to exercise. First, we provide background on the macrostructure and ultrastructure of skeletal muscle fibres, highlighting the current understanding of sarcomeric networks and mitochondrial subpopulations. Next, we discuss acute exercise skeletal muscle metabolism and the signalling, transcriptional and epigenetic regulation of adaptations to exercise training. We address knowledge gaps throughout and propose future directions for the field. This Review contextualizes recent research of skeletal muscle exercise metabolism, framing further advances and translation into practice.

Neuromuscular electrical stimulation enhances the ability of serum extracellular vesicles to regenerate aged skeletal muscle after injury

Exercise promotes healthy aging of skeletal muscle. This benefit may be mediated by youthful factors in the circulation released in response to an exercise protocol. While numerous studies to date have explored soluble proteins as systemic mediators of rejuvenating effect of exercise on tissue function, here we showed that the beneficial effect of skeletal muscle contractile activity on aged muscle function is mediated, at least in part, by regenerative properties of circulating extracellular vesicles (EVs). Muscle contractile activity elicited by neuromuscular electrical stimulation (NMES) decreased intensity of expression of the tetraspanin surface marker, CD63, on circulating EVs. Moreover, NMES shifted the biochemical Raman fingerprint of circulating EVs in aged animals with significant changes in lipid and sugar content in response to NMES when compared to controls. As a demonstration of the physiological relevance of these EV changes, we showed that intramuscular administration of EVs derived from aged animals subjected to NMES enhanced aged skeletal muscle healing after injury. These studies suggest that repetitive muscle contractile activity enhances the regenerative properties of circulating EVs in aged animals.