Experimental Models of Sarcopenia: Bridging Molecular Mechanism and Therapeutic Strategy

Saururus chinensis (Lour.) Baill. extract promotes skeletal muscle cell differentiation by positively regulating mitochondrial biogenesis and AKT/mTOR signaling in vitro

Promotion of myoblast differentiation by activating mitochondrial biogenesis and protein synthesis signaling pathways provides a potential alternative strategy to balance energy and overcome muscle loss and muscle disorders. Saururus chinensis (Lour.) Baill. extract (SCE) has been used extensively as a traditional herbal medicine and has several physiological activities, including anti‑asthmatic, anti‑oxidant, anti‑inflammatory, anti‑atopic, anticancer and hepatoprotective properties. However, the effects and mechanisms of action of SCE on muscle differentiation have not yet been clarified. In the present study, it was investigated whether SCE affects skeletal muscle cell differentiation through the regulation of mitochondrial biogenesis and protein synthesis in murine C2C12 myoblasts. The XTT colorimetric assay was used to determine cell viability, and myosin heavy chain (MyHC) levels were determined using immunocytochemistry. SCE was applied to C2C12 myotube at different concentrations (1, 5, or 10 ng/ml) and times (1,3, or 5 days). Reverse transcription‑quantitative PCR and western blotting were used to analyze the mRNA and protein expression change of factors related to differentiation, mitochondrial biogenesis and protein synthesis. Treatment of C2C12 cells with SCE at 1,5, and 10 ng/ml did not affect cell viability. SCE promoted C2C12 myotube formation and significantly increased MyHC expression in a concentration‑ and time‑dependent manner. SCE significantly increased the mRNA and protein expression of muscle differentiation‑specific markers, such as MyHC, myogenic differentiation 1, myogenin, Myogenic Factor 5, and β‑catenin, mitochondrial biosynthesis‑related factors, such as peroxisome proliferator‑activated receptor‑gamma coactivator‑1α, nuclear respirator factor‑1, AMP‑activated protein kinase phosphorylation, and histone deacetylase 5 and AKT/mTOR signaling factors related to protein synthesis. SCE may prevent skeletal muscle dysfunction by enhancing myoblast differentiation through the promotion of mitochondrial biogenesis and protein synthesis.

Shining a spotlight on sarcopenia and myosteatosis in liver disease and liver transplantation: Potentially modifiable risk factors with major clinical impact

Muscle-wasting and disease-related malnutrition are highly prevalent in patients with chronic liver diseases (CLD) as well as in liver transplant (LT) candidates. Alterations of body composition (BC) such as sarcopenia, myosteatosis and sarcopenic obesity and associated clinical frailty were tied to inferior clinical outcomes including hospital admissions, length of stay, complications, mortality and healthcare costs in various patient cohorts and clinical scenarios. In contrast to other inherent detrimental individual characteristics often observed in these complex patients, such as comorbidities or genetic risk, alterations of the skeletal muscle and malnutrition are considered as potentially modifiable risk factors with a major clinical impact. Even so, there is only limited high-level evidence to show how these pathologies should be addressed in the clinical setting. This review discusses the current state-of-the-art on the role of BC assessment in clinical outcomes in the setting of CLD and LT focusing mainly on sarcopenia and myosteatosis. We focus on the disease-related pathophysiology of BC alterations. Based on these, we address potential therapeutic interventions including nutritional regimens, physical activity, hormone and targeted therapies. In addition to summarizing existing knowledge, this review highlights novel trends, and future perspectives and identifies persisting challenges in addressing BC pathologies in a holistic way, aiming to improve outcomes and quality of life of patients with CLD awaiting or undergoing LT.

Biomarkers of frailty

Several biomarkers have been proposed to identify frailty, a multisystemic age-related syndrome. However, the complex pathophysiology and the absence of a consensus on a comprehensive and universal definition make it challenging to pinpoint a singular biomarker or set of biomarkers that conclusively characterize frailty. This review delves into the main laboratory biomarkers, placing special emphasis on those associated with various pathways closely tied to the frailty condition, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations and microRNA. Additionally, we provide a summary of different clinical biomarkers encompassing different tools that have been proposed to assess frailty. We further address various imaging biomarkers such as Dual Energy X-ray Absorptiometry, Bioelectrical Impedance analysis, Computed Tomography and Magnetic Resonance Imaging, Ultrasound and D3 Creatine dilution. Intervention to treat frailty, including non-pharmacological ones, especially those involving physical exercise and nutrition, and pharmacological interventions, that include those targeting specific mechanisms such as myostatin inhibitors, insulin sensitizer metformin and with special relevance for hormonal treatments are mentioned. We further address the levels of different biomarkers in monitoring the potential positive effects of some of these interventions. Despite the availability of numerous biomarkers, their performance and usefulness in the clinical arena are far from being satisfactory. Considering the multicausality of frailty, there is an increasing need to assess the role of sets of biomarkers and the combination between laboratory, clinical and image biomarkers, in terms of sensitivity, specificity and predictive values for the diagnosis and prognosis of the different outcomes of frailty to improve detection and monitoring of older people with frailty or at risk of developing it, being this a need in the everyday clinical practice.

Effects of Baduanjin exercise on cognitive frailty, oxidative stress, and chronic inflammation in older adults with cognitive frailty: a randomized controlled trial

Background

Oxidative stress and chronic inflammation play an important role in the pathogenesis process of cognitive frailty (CF). Regular Baduanjin exercise could improve cognitive frailty in older adults, but it is unclear whether the effect of Baduanjin exercise on improving CF is mediated by modulating circulating oxidative stress and inflammatory process.

Method

A total of 102 community-dwelling older adults with CF were recruited and randomly allocated into a 24-week Baduanjin exercise training group or no specific exercise intervention control group at an equal rate. Cognitive function and physical frailty index were assessed using the Montreal Cognitive Assessment (MoCA) and the Edmonton Frail Scale (EFS), as well as the oxidative stress and inflammatory cytokines were measured at baseline and after intervention.

Result

After 24 weeks of intervention, the increased MoCA score (2.51 ± 0.32 points, p < 0.001) and the decreased EFS scores (1.94 ± 0.20 points, p = 0.012) in the Baduanjin group were significantly higher than those in the control group. Serum antioxidant SOD levels were increased by 10.03 ± 4.73 U/mL (p < 0.001), and the prooxidative MDA and 8-iso-PGF2α levels were decreased by -1.08 ± 0.80 nmol/mL (p = 0.030) and -86.61 ± 15.03 ng/L (p < 0.001) in the Baduanjin training group; while inflammatory cytokines IFN-γ, IL-2 and IL-4 levels were increased (1.08 ± 0.33 pg./mL, p = 0.034, 2.74 ± 0.75 pg./mL, p = 0.04 and 1.48 ± 0.35 pg./mL, p = 0.042). In addition, a mediation effect that Baduanjin training improved cognitive ability mediated by an increase of circulating IFN-γ and IL-2 levels were observed in this study.

Conclusion

Regular Baduanjin exercise training could improve the cognitive frailty of the community-dwelling older adults with CF, and modulate oxidative stress and inflammatory processes by reducing circulating pro-oxidative MDA and 8-iso-PGF2α levels and increasing anti-oxidative SOD levels, as well as impacting inflammatory cytokines IFN-γ, IL-2, and IL-4 levels. Nevertheless, the mechanism of Baduanjin exercise mediating oxidative stress and inflammatory processes should be cautious to be explained.

Clinical trial registration

http://www.chictr.org.cn/index.aspx, ChiCTR1800020341.

Physical Activity and Oxidative Stress in Aging

Biological aging, characterized by changes in metabolism and physicochemical properties of cells, has an impact on public health. Environment and lifestyle, including factors like diet and physical activity, seem to play a key role in healthy aging. Several studies have shown that regular physical activity can enhance antioxidant defense mechanisms, including the activity of enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase. However, intense or prolonged exercise can also lead to an increase in reactive oxygen species (ROS) production temporarily, resulting in oxidative stress. This phenomenon is referred to as "exercise-induced oxidative stress". The relationship between physical activity and oxidative stress in aging is complex and depends on various factors such as the type, intensity, duration, and frequency of exercise, as well as individual differences in antioxidant capacity and adaptation to exercise. In this review, we analyzed what is reported by several authors regarding the role of physical activity on oxidative stress in the aging process as well as the role of hormesis and physical exercise as tools for the prevention and treatment of sarcopenia, an aging-related disease. Finally, we reported what has recently been studied in relation to the effect of physical activity and sport on aging in women.

Impact of Chinese herbal medicine on sarcopenia in enhancing muscle mass, strength, and function: A systematic review and meta-analysis of randomized controlled trials

Sarcopenia has become important to the public health with the increase in the aging population in society. However, the therapeutic effects of conventional approaches, including pharmacotherapy, exercise, and nutritional intervention, are far from satisfactory. Chinese herbal medicine is a new treatment format with interesting possibilities in sarcopenia has been widely practiced. The study aims to explore the effectiveness of Chinese herbal medicine in sarcopenia. We comprehensively searched the following electronic databases: Medline, EMBASE, APA PsycInfo, Cochrane Library, Web of Science, PubMed, and Chinese database from the establishment of the database to December 2022 (no language restrictions). Randomized controlled clinical studies on the use of Chinese herbal medicine in sarcopenia were selected in compliance with PRISMA guidelines. Review Manager and Stata were used for statistical analysis and the mean difference and standardized mean difference were adopted. Of 277 identified studies, 17 were eligible and included in our analysis (N = 1440 participants). The results showed that Chinese herbal medicine can improve total efficiency (RR = 1.29, 95% CI [1.21, 1.36], p < 0.00001) in sarcopenia and enhance muscle mass (SMD = 1.02, 95% CI [0.55, 1.50], p < 0.0001), and muscle strength measured by grip strength (SMD = 0.66, 95% CI [0.36, 0.96], p < 0.0001), measured by 60°/s knee extension peak TQ (MD = 5.63, 95% CI [-0.30, 11.57], p = 0.06) and muscle function measured by 6-meter walking speed (SMD = 1.34, 95% CI [0.60, 2.08], p = 0.0004), measured by the short physical performance battery of 1.50%, 95% CI (1.05, 1.95), measured by the EuroQoL 5-dimension of (SMD = 0.27, 95% CI [-0.10, 0.65], p = 0.16), suggesting that Chinese herbal medicine alone or combined with conventional treatment has ameliorating effect on sarcopenia. Chinese herbal medicine is a potential therapeutic strategy in sarcopenia. The funnel plot and Egger's test indicated publication bias. To confirm our conclusions, further high-quality studies should be conducted.

Ginsenosides Rh1, Rg2, and Rg3 ameliorate dexamethasone-induced muscle atrophy in C2C12 myotubes

High doses or prolonged use of the exogenous synthetic glucocorticoid dexamethasone (Dex) can lead to muscle atrophy. In this study, the anti-atrophic effects of ginsenosides Rh1, Rg2, and Rg3 on Dex-induced C2C12 myotube atrophy were assessed by XTT, myotube diameter, fusion index, and western blot analysis. The XTT assay results showed that treatment with Rh1, Rg2, and Rg3 enhanced cell viability in Dex-injured C2C12 myotubes. Compared with the control group, the myotube diameter and fusion index were both reduced in Dex-treated cells, but treatment with Rh1, Rg2, and Rg3 increased these parameters. Furthermore, Rh1, Rg2, and Rg3 significantly downregulated the protein expression of FoxO3a, MuRF1, and Fbx32, while also upregulating mitochondrial biogenesis through the SIRT1/PGC-1α pathway. It also prevents myotube atrophy by regulating the IGF-1/Akt/ mTOR signaling pathway. These findings indicate that Rh1, Rg2, and Rg3 have great potential as useful agents for the prevention and treatment of muscle atrophy.

Evidence that tirzepatide protects against diabetes-related cardiac damages

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective antidiabetic drugs with potential cardiovascular benefits. Despite their well-established role in reducing the risk of major adverse cardiovascular events (MACE), their impact on heart failure (HF) remains unclear. Therefore, our study examined the cardioprotective effects of tirzepatide (TZT), a novel glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) receptor agonist.

METHODS

A three-steps approach was designed: (i) Meta-analysis investigation with the primary objective of assessing major adverse cardiovascular events (MACE) occurrence from major randomized clinical trials.; (ii) TZT effects on a human cardiac AC16 cell line exposed to normal (5 mM) and high (33 mM) glucose concentrations for 7 days. The gene expression and protein levels of primary markers related to cardiac fibrosis, hypertrophy, and calcium modulation were evaluated. (iii) In silico data from bioinformatic analyses for generating an interaction map that delineates the potential mechanism of action of TZT.

RESULTS

Meta-analysis showed a reduced risk for MACE events by TZT therapy (HR was 0.59 (95% CI 0.40-0.79, Heterogeneity: r2 = 0.01, I2 = 23.45%, H2 = 1.31). In the human AC16 cardiac cell line treatment with 100 nM TZT contrasted high glucose (HG) levels increase in the expression of markers associated with fibrosis, hypertrophy, and cell death (p < 0.05 for all investigated markers). Bioinformatics analysis confirmed the interaction between the analyzed markers and the associated pathways found in AC16 cells by which TZT affects apoptosis, fibrosis, and contractility, thus reducing the risk of heart failure.

CONCLUSION

Our findings indicate that TZT has beneficial effects on cardiac cells by positively modulating cardiomyocyte death, fibrosis, and hypertrophy in the presence of high glucose concentrations. This suggests that TZT may reduce the risk of diabetes-related cardiac damage, highlighting its potential as a therapeutic option for heart failure management clinical trials. Our study strongly supports the rationale behind the clinical trials currently underway, the results of which will be further investigated to gain insights into the cardiovascular safety and efficacy of TZT.

Diabetes Mellitus Should Be Considered While Analysing Sarcopenia-Related Biomarkers

Sarcopenia is a chronic, progressive skeletal muscle disease characterised by low muscle strength and quantity or quality, leading to low physical performance. Patients with type 2 diabetes mellitus (T2DM) are more at risk of sarcopenia than euglycemic individuals. Because of several shared pathways between the two diseases, sarcopenia is also a risk factor for developing T2DM in older patients. Various biomarkers are under investigation as potentially valuable for sarcopenia diagnosis and treatment monitoring. Biomarkers related to sarcopenia can be divided into markers evaluating musculoskeletal status (biomarkers specific to muscle mass, markers of the neuromuscular junction, or myokines) and markers assuming causal factors (adipokines, hormones, and inflammatory markers). This paper reviews the current knowledge about how diabetes and T2DM complications affect potential sarcopenia biomarker concentrations. This review includes markers recently proposed by the expert group of the European Society for the Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) as those that may currently be useful in phase II and III clinical trials of sarcopenia: myostatin (MSTN); follistatin (FST); irisin; brain-derived neurotrophic factor (BDNF); procollagen type III N-terminal peptide (PIIINP; P3NP); sarcopenia index (serum creatinine to serum cystatin C ratio); adiponectin; leptin; insulin-like growth factor-1 (IGF-1); dehydroepiandrosterone sulphate (DHEAS); C-reactive protein (CRP); interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α). A better understanding of factors influencing these biomarkers' levels, including diabetes and diabetic complications, may lead to designing future studies and implementing results in clinical practice.

Bibliometric and scientometric analysis on biomarkers and molecular mechanisms for physical frailty and sarcopenia

Introduction

The influence of physical frailty and sarcopenia (PFS) on the well-being of older people and continuous pressure on the healthcare systems has prompted a research on the pathophysiology and molecular mechanisms of these conditions. Nonetheless some biomarkers have been suggested as potential markers for PFS none of them have been shown to highlight the complex nature of PFS, which reveals that there is a need for an understanding of the possible biomarker candidates. The aim of this study was to identify the current research hotspots, status, and trends in the field of biomarkers and molecular mechanisms for PFS.

Methods

The bibliometric and scientometric analyses were performed using VOSviewer (version 1.6.18) and open source software platform Cytoscape v.3.9 (for visualizing and constructing a network of keywords). Data of publications (from 1997 to 2023) related to biomarkers and molecular mechanisms of PFS were obtained (in May 2023) from the database of Science Citation Index Expanded of Web of Science, Scopus, and PubMed. The keywords obtained from the Scopus database were used to perform a meaningful keyword analysis. A network of keyword relationships was build using Cytoscape.

Results

In this study, we present biomarker keywords for PFS in relation to other keywords potentially designating processes and mechanisms and reveal the biomarker identities and current contexts in which these biomarker identities are discussed.

Conclusions

Over recent years, scientific interest in the field of PFS has increased and focused on the inflammatory process and probably will be concentrated on myokines (such as cytokines and small proteins) that are synthetized and released by skeletal muscles in response to physical activity. Moreover, proteomic and genetic markers are deeply involved in PFS.

Mouse models of accelerated aging in musculoskeletal research for assessing frailty, sarcopenia, and osteoporosis - A review

Musculoskeletal aging encompasses the decline in bone and muscle function, leading to conditions such as frailty, osteoporosis, and sarcopenia. Unraveling the underlying molecular mechanisms and developing effective treatments are crucial for improving the quality of life for those affected. In this context, accelerated aging models offer valuable insights into these conditions by displaying the hallmarks of human aging. Herein, this review focuses on relevant mouse models of musculoskeletal aging with particular emphasis on frailty, osteoporosis, and sarcopenia. Among the discussed models, PolgA mice in particular exhibit hallmarks of musculoskeletal aging, presenting early-onset frailty, as well as reduced bone and muscle mass that closely resemble human musculoskeletal aging. Ultimately, findings from these models hold promise for advancing interventions targeted at age-related musculoskeletal disorders, effectively addressing the challenges posed by musculoskeletal aging and associated conditions in humans.

Zebrafish as an Emerging Model for Sarcopenia: Considerations, Current Insights, and Future Directions

Sarcopenia poses a significant challenge to public health and can severely impact the quality of life of aging populations. Despite extensive efforts to study muscle degeneration using traditional animal models, there is still a lack of effective diagnostic tools, precise biomarkers, and treatments for sarcopenia. Zebrafish models have emerged as powerful tools in biomedical research, providing unique insights into age-related muscle disorders like sarcopenia. The advantages of using zebrafish models include their rapid growth outside of the embryo, optical transparency during early developmental stages, high reproductive potential, ease of husbandry, compact size, and genetic tractability. By deepening our understanding of the molecular processes underlying sarcopenia, we may develop novel diagnostic tools and effective treatments that can improve the lives of aging individuals affected by this condition. This review aims to explore the unique advantages of zebrafish as a model for sarcopenia research, highlight recent breakthroughs, outline potential avenues for future investigations, and emphasize the distinctive contributions that zebrafish models offer. Our research endeavors to contribute significantly to address the urgent need for practical solutions to reduce the impact of sarcopenia on aging populations, ultimately striving to enhance the quality of life for individuals affected by this condition.

Hallmarks of ageing in human skeletal muscle and implications for understanding the pathophysiology of sarcopenia in women and men

Ageing is a complex biological process associated with increased morbidity and mortality. Nine classic, interdependent hallmarks of ageing have been proposed involving genetic and biochemical pathways that collectively influence ageing trajectories and susceptibility to pathology in humans. Ageing skeletal muscle undergoes profound morphological and physiological changes associated with loss of strength, mass, and function, a condition known as sarcopenia. The aetiology of sarcopenia is complex and whilst research in this area is growing rapidly, there is a relative paucity of human studies, particularly in older women. Here, we evaluate how the nine classic hallmarks of ageing: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication contribute to skeletal muscle ageing and the pathophysiology of sarcopenia. We also highlight five novel hallmarks of particular significance to skeletal muscle ageing: inflammation, neural dysfunction, extracellular matrix dysfunction, reduced vascular perfusion, and ionic dyshomeostasis, and discuss how the classic and novel hallmarks are interconnected. Their clinical relevance and translational potential are also considered.

Mass Spectrometry-Based Multiomics Identifies Metabolic Signatures of Sarcopenia in Rhesus Monkey Skeletal Muscle

Sarcopenia is a progressive disorder characterized by age-related loss of skeletal muscle mass and function. Although significant progress has been made over the years to identify the molecular determinants of sarcopenia, the precise mechanisms underlying the age-related loss of contractile function remains unclear. Advances in "omics" technologies, including mass spectrometry-based proteomic and metabolomic analyses, offer great opportunities to better understand sarcopenia. Herein, we performed mass spectrometry-based analyses of the vastus lateralis from young, middle-aged, and older rhesus monkeys to identify molecular signatures of sarcopenia. In our proteomic analysis, we identified proteins that change with age, including those involved in adenosine triphosphate and adenosine monophosphate metabolism as well as fatty acid beta oxidation. In our untargeted metabolomic analysis, we identified metabolites that changed with age largely related to energy metabolism including fatty acid beta oxidation. Pathway analysis of age-responsive proteins and metabolites revealed changes in muscle structure and contraction as well as lipid, carbohydrate, and purine metabolism. Together, this study discovers new metabolic signatures and offers new insights into the molecular mechanisms underlying sarcopenia for the evaluation and monitoring of a therapeutic treatment of sarcopenia.

Vitamin D3 Exerts Beneficial Effects on C2C12 Myotubes through Activation of the Vitamin D Receptor (VDR)/Sirtuins (SIRT)1/3 Axis

The onset of sarcopenia is associated with a decline in vitamin D receptor (VDR) expression, wherein reduced VDR levels contribute to muscle atrophy, while heightened expression promotes muscle hypertrophy. Like VDR, the age-related decline in protein deacetylase sirtuin (SIRT) expression is linked to the development of sarcopenia and age-related muscle dysfunction. This study aimed to investigate whether the VDR agonist 1,25-dihydroxyvitamin D3 (1,25VD3) exerts beneficial effects on muscles through interactions with sirtuins and, if so, the underlying molecular mechanisms. Treatment of 1,25VD3 in differentiating C2C12 myotubes substantially elevated VDR, SIRT1, and SIRT3 expression, enhancing their differentiation. Furthermore, 1,25VD3 significantly enhanced the expression of key myogenic markers, including myosin heavy chain (MyHC) proteins, MyoD, and MyoG, and increased the phosphorylation of AMPK and AKT. Conversely, VDR knockdown resulted in myotube atrophy and reduced SIRT1 and SIRT3 levels. In a muscle-wasting model triggered by IFN-γ/TNF-α in C2C12 myotubes, diminished VDR, SIRT1, and SIRT3 levels led to skeletal muscle atrophy and apoptosis. 1,25VD3 downregulated the increased expression of muscle atrophy-associated proteins, including FoxO3a, MAFbx, and MuRF1 in an IFN-γ/TNF-α induced atrophy model. Importantly, IFN-γ/TNF-α significantly reduced the mtDNA copy number in the C2C12 myotube, whereas the presence of 1,25VD3 effectively prevented this decrease. These results support that 1,25VD3 could serve as a potential preventive or therapeutic agent against age-related muscle atrophy by enhancing the VDR/SIRT1/SIRT3 axis.

Pretreatment Masseter Muscle Volume Predicts Survival in Locally Advanced Nasopharyngeal Carcinoma Patients Treated with Concurrent Chemoradiotherapy

BACKGROUND AND PURPOSE

Muscle loss is a significant indicator of cancer cachexia and is associated with a poor prognosis in cancer patients. Given the absence of comparable studies, the current retrospective study sought to examine the correlation between the total masseter muscle volume (TMMV) before treatment and the survival outcomes in locally advanced nasopharyngeal cancer (LA-NPC) patients who received definitive concurrent chemoradiotherapy (CCRT).

METHODS

A three-dimensional segmentation model was used to determine the TMMV for each patient by analyzing pre-CCRT magnetic resonance imaging. The optimal TMMV cutoff values were searched using receiver operating characteristic (ROC) curve analyses. The primary and secondary endpoints were the relationship between the pre-CCRT TMMV measures and overall survival (OS) and progression-free survival (PFS), respectively.

RESULTS

Ninety-seven patients were included in this study. ROC curve analyses revealed 38.0 cc as the optimal TMMV cutoff: ≤38.00 cc (n = 42) and >38.0 cc (n = 55). Comparisons between the two groups showed that the TMMV>38.0 cc group had significantly longer PFS [Not reached (NR) vs. 28; p < 0.01] and OS (NR vs. 71; p < 0.01) times, respectively. The results of the multivariate analysis demonstrated that the T-stage, N-stage, number of concurrent chemotherapy cycles, and TMMV were independent associates of PFS (p < 0.05 for each) and OS (p < 0.05 for each) outcomes, respectively.

CONCLUSION

The findings of the current retrospective research suggest that pretreatment TMMV is a promising indicator for predicting survival outcomes in LA-NPC patients receiving definitive CCRT.

Silver electroceutical technology to treat sarcopenia

While the world is rapidly transforming into a superaging society, pharmaceutical approaches to treat sarcopenia have hitherto not been successful due to their insufficient efficacy and failure to specifically target skeletal muscle cells (skMCs). Although electrical stimulation (ES) is emerging as an alternative intervention, its efficacy toward treating sarcopenia remains unexplored. In this study, we demonstrate a silver electroceutical technology with the potential to treat sarcopenia. First, we developed a high-throughput ES screening platform that can simultaneously stimulate 15 independent conditions, while utilizing only a small number of human-derived primary aged/young skMCs (hAskMC/hYskMC). The in vitro screening showed that specific ES conditions induced hypertrophy and rejuvenation in hAskMCs, and the optimal ES frequency in hAskMCs was different from that in hYskMCs. When applied to aged mice in vivo, specific ES conditions improved the prevalence and thickness of Type IIA fibers, along with biomechanical attributes, toward a younger skMC phenotype. This study is expected to pave the way toward an electroceutical treatment for sarcopenia with minimal side effects and help realize personalized bioelectronic medicine.

Exploring the Role of Oxidative Stress in Skeletal Muscle Atrophy: Mechanisms and Implications

Skeletal muscle atrophy is a complex physiological process characterized by progressive muscle mass and strength loss. It is associated with various health conditions, including aging, disease, and certain diseases. Emerging research has indicated that oxidative stress plays a significant role in developing and progressing skeletal muscle atrophy. This review article explores the mechanisms by which oxidative stress influences skeletal muscle atrophy and its implications for potential therapeutic interventions. The review begins by providing an overview of skeletal muscle atrophy and the current understanding of its underlying mechanisms, highlighting the intricate balance between protein degradation and synthesis pathways. Subsequently, the concept of oxidative stress is introduced, discussing its sources and the intricate redox signaling pathways present in skeletal muscle cells. This review's main focus is exploring the multifaceted role of oxidative stress in skeletal muscle atrophy. The detrimental effects of excessive reactive oxygen species (ROS) production on cellular components, including proteins, lipids, and deoxyribonucleic acid (DNA), are discussed. In addition, the impact of oxidative stress on key signaling pathways involved in muscle wasting, such as the ubiquitin-proteasome system and autophagy, is examined. Furthermore, the review highlights the implications of oxidative stress in modulating muscle regeneration and the importance of redox balance in maintaining muscle health. Potential therapeutic strategies targeting oxidative stress, such as antioxidant supplementation, exercise interventions, and pharmacological approaches, are also discussed. In conclusion, this review comprehensively explains the intricate relationship between oxidative stress and skeletal muscle atrophy. By elucidating the underlying mechanisms and discussing potential therapeutic interventions, this review aims to contribute to the development of novel strategies for mitigating muscle wasting and improving overall muscle health.

Rice Germ Attenuates Chronic Unpredictable Mild Stress-Induced Muscle Atrophy

Chronic stress leads to hypothalamic-pituitary-adrenal axis dysfunction, increasing cortisol levels. Glucocorticoids (GCs) promote muscle degradation and inhibit muscle synthesis, eventually causing muscle atrophy. In this study, we aimed to evaluate whether rice germ supplemented with 30% γ-aminobutyric acid (RG) attenuates muscle atrophy in an animal model of chronic unpredictable mild stress (CUMS). We observed that CUMS raised the adrenal gland weight and serum adrenocorticotropic hormone (ACTH) and cortisol levels, and these effects were reversed by RG. CUMS also enhanced the expression of the GC receptor (GR) and GC-GR binding in the gastrocnemius muscle, which were attenuated by RG. The expression levels of muscle degradation-related signaling pathways, such as the Klf15, Redd-1, FoxO3a, Atrogin-1, and MuRF1 pathways, were enhanced by CUMS and attenuated by RG. Muscle synthesis-related signaling pathways, such as the IGF-1/AKT/mTOR/s6k/4E-BP1 pathway, were reduced by CUMS and enhanced by RG. Moreover, CUMS raised oxidative stress by enhancing the levels of iNOS and acetylated p53, which are involved in cell cycle arrest, whereas RG attenuated both iNOS and acetylated p53 levels. Cell proliferation in the gastrocnemius muscle was reduced by CUMS and enhanced by RG. The muscle weight, muscle fiber cross-sectional area, and grip strength were reduced by CUMS and enhanced by RG. Therefore, RG attenuated ACTH levels and cortisol-related muscle atrophy in CUMS animals.

Caloric Restriction Combined with Immobilization as Translational Model for Sarcopenia Expressing Key-Pathways of Human Pathology

The prevalence of sarcopenia is increasing while it is often challenging, expensive and time-consuming to test the effectiveness of interventions against sarcopenia. Translational mouse models that adequately mimic underlying physiological pathways could accelerate research but are scarce. Here, we investigated the translational value of three potential mouse models for sarcopenia, namely partial immobilized (to mimic sedentary lifestyle), caloric restricted (CR; to mimic malnutrition) and a combination (immobilized & CR) model. C57BL/6J mice were calorically restricted (-40%) and/or one hindleg was immobilized for two weeks to induce loss of muscle mass and function. Muscle parameters were compared to those of young control (4 months) and old reference mice (21 months). Transcriptome analysis of quadriceps muscle was performed to identify underlying pathways and were compared with those being expressed in aged human vastus lateralis muscle-biopsies using a meta-analysis of five different human studies. Caloric restriction induced overall loss of lean body mass (-15%, p<0.001), whereas immobilization decreased muscle strength (-28%, p<0.001) and muscle mass of hindleg muscles specifically (on average -25%, p<0.001). The proportion of slow myofibers increased with aging in mice (+5%, p<0.05), and this was not recapitulated by the CR and/or immobilization models. The diameter of fast myofibers decreased with aging (-7%, p<0.05), and this was mimicked by all models. Transcriptome analysis revealed that the combination of CR and immobilization recapitulated more pathways characteristic for human muscle-aging (73%) than naturally aged (21 months old) mice (45%). In conclusion, the combination model exhibits loss of both muscle mass (due to CR) and function (due to immobilization) and has a remarkable similarity with pathways underlying human sarcopenia. These findings underline that external factors such as sedentary behavior and malnutrition are key elements of a translational mouse model and favor the combination model as a rapid model for testing the treatments against sarcopenia.

Pain Increases the Risk for Sarcopenia in Community-Dwelling Adults: Results From the English Longitudinal Study of Ageing

BACKGROUND

Pain and sarcopenia are common in older people. Cross-sectional studies have reported a significant association between these two conditions, but cohort studies exploring pain as a potential risk factor for sarcopenia are scarce. Given this background, the aim of the present work was to investigate the association between pain (and its severity) at baseline, and the incidence of sarcopenia over 10 years of follow-up in a large representative sample of the English older adult population.

METHODS

Pain was diagnosed using self-reported information and categorized as mild to severe pain at four sites (low back, hip, knee, and feet). Incident sarcopenia was defined as having low handgrip strength and low skeletal muscle mass during the follow-up period. The association between pain at baseline and incident sarcopenia was assessed using an adjusted logistic regression analysis, and reported as odds ratios (ORs) with their 95% confidence intervals (CIs).

RESULTS

The 4 102 participants without sarcopenia at baseline had a mean ± standard deviation age of 69.7 ± 7.2 years, and they were mainly male (55.6%). Pain was present in 35.3% of the sample. Over 10 years of follow-up, 13.9% of the participants developed sarcopenia. After adjusting for 12 potential confounders, people with pain reported a significantly higher risk of sarcopenia (OR = 1.46: 95% CI: 1.18-1.82). However, only severe pain was significantly associated with incident sarcopenia, without significant differences across the four sites assessed.

CONCLUSIONS

The presence of pain, particularly severe pain, was associated with a significantly higher risk of incident sarcopenia.

Cellular Senescence and Frailty in Transplantation

Purpose of review

To summarizes the literature on cellular senescence and frailty in solid-organ transplantation and highlight the emerging role of senotherapeutics as a treatment for cellular senescence.

Recent findings

Solid-organ transplant patients are aging. Many factors contribute to aging acceleration in this population, including cellular senescence. Senescent cells accumulate in tissues and secrete proinflammatory and profibrotic proteins which result in tissue damage. Cellular senescence contributes to age-related diseases and frailty. Our understanding of the role cellular senescence plays in transplant-specific complications such as allograft immunogenicity and infections is expanding. Promising treatments, including senolytics, senomorphics, cell-based regenerative therapies, and behavioral interventions, may reduce cellular senescence abundance and frailty in patients with solid-organ transplants.

Summary

Cellular senescence and frailty contribute to adverse outcomes in solid-organ transplantation. Continued pursuit of understanding the role cellular senescence plays in transplantation may lead to improved senotherapeutic approaches and better graft and patient outcomes.

Sex-specific alteration in human muscle transcriptome with age

Sarcopenia is a medical condition that progressively develops with age and results in reduced skeletal muscle mass, alteration in muscle composition, and decreased muscle strength. Several clinical studies suggested that sarcopenia disproportionally affects males and females with age. Despite this knowledge, the molecular mechanism governing the pathophysiology is not well understood in a sex-specific manner. In this study, we utilized human gastrocnemius muscles from males and females to identify differentially regulated genes with age. We found 269 genes with at least a twofold expression difference in the aged muscle transcriptome. Among the female muscle samples, there were 239 differentially regulated genes, and the novel protein-coding genes include KIF20A, PIMREG, MTRNR2L6, TRPV6, EFNA2, RNF24, and SFN. In aged male skeletal muscle, there were 166 differentially regulated genes, and the novel-protein coding genes are CENPK, CDKN2A, BHLHA15, and EPHA. Gene Ontology (GO) enrichment revealed glucose catabolism, NAD metabolic processes, and muscle fiber transition pathways that are involved in aged female skeletal muscle, whereas replicative senescence, cytochrome C release, and muscle composition pathways are disrupted in aged male skeletal muscle. Targeting these novels, differentially regulated genes, and signaling pathways could serve as sex-specific therapeutic targets to combat the age-related onset of sarcopenia and promote healthy aging.

Repurposing Approved Drugs for Sarcopenia Based on Transcriptomics Data in Humans

Sarcopenia, characterized by age-related loss of muscle mass, strength, and decreased physical performance, is a growing public health challenge amid the rapidly ageing population. As there are no approved drugs that target sarcopenia, it has become increasingly urgent to identify promising pharmacological interventions. In this study, we conducted an integrative drug repurposing analysis utilizing three distinct approaches. Firstly, we analyzed skeletal muscle transcriptomic sequencing data in humans and mice using gene differential expression analysis, weighted gene co-expression analysis, and gene set enrichment analysis. Subsequently, we employed gene expression profile similarity assessment, hub gene expression reversal, and disease-related pathway enrichment to identify and repurpose candidate drugs, followed by the integration of findings with rank aggregation algorithms. Vorinostat, the top-ranking drug, was also validated in an in vitro study, which demonstrated its efficacy in promoting muscle fiber formation. Although still requiring further validation in animal models and human clinical trials, these results suggest a promising drug repurposing prospect in the treatment and prevention of sarcopenia.

Association between asymmetric dimethylarginine and sarcopenia in community-dwelling older women

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelium nitric oxide synthesis and causes endothelial dysfunction that may be related to sarcopenia. However, the association between ADMA and sarcopenia has not been studied. We evaluated the correlations between plasma ADMA levels and sarcopenia in community-dwelling older women. In total, 144 community-dwelling older women participated in this study. Plasma ADMA levels were measured using a competitive enzyme-linked immunosorbent assay. Skeletal muscle mass, measured in terms of bioimpedance and grip strength, was used to assess sarcopenia. Plasma ADMA levels were significantly higher in participants with sarcopenia than in those without sarcopenia. Through receiver-operating characteristic curve analysis, the cutoff value of plasma ADMA level for sarcopenia was estimated at 0.57 μM. Sarcopenia was significantly more prevalent in participants with higher plasma ADMA levels than in those with lower plasma ADMA levels. According to logistic regression analysis, the crude odds ratio of higher plasma ADMA levels in participants with sarcopenia was 4.57 (95% confidence interval, 1.82-11.47; p = 0.001). Reductions in the skeletal muscle mass index over 2 years were significantly greater in participants with higher plasma ADMA levels. In conclusion, plasma ADMA levels were significantly associated with sarcopenia in community-dwelling older women.

Reduced energy metabolism contributing to aging of skeletal muscle by serum metabolomics and gut microbiota analysis

AIMS

Sarcopenia is an age-related syndrome characterized by a gradual loss of the muscle mass, strength, and function. It is associated with a high risk of adverse consequences such as poorer quality of life, falls, disability and mortality among the elderly. The aim in this study is to investigate the pathological mechanism of sarcopenia.

MAIN METHODS

The aging of skeletal muscle was investigated by the D-galactose induced accelerated aging model combining with constrained motion. After 10 weeks, muscle function and gastrocnemius muscle index, and morphology of muscle fibers were evaluated, and myostatin, IGF-1 and ATP in skeletal muscle were also determined. Then the mechanism of aging-related skeletal muscle dysfunctions was investigated based on untargeted serum metabolomics and 16S rRNA gene sequencing. Four key metabolites were validated by the D-galactose-induced C2C12 senescent cell model in vitro.

KEY FINDINGS

Results showed that gastrocnemius muscle mass was decreased significantly, morphology of muscle fibers was altered, and muscle function was damaged in the aged group. Furthermore, increased MSTN, and decreased IGF-1 and ATP were also observed in the aging skeletal muscle. Importantly, alteration of the key pathways including riboflavin biosynthesis and energy metabolism contributed to the aging of skeletal muscle. Four key metabolites, including riboflavin, α-ketoglutaric acid and two dicarboxylic acids, which were involved in these metabolic pathways, could promote the proliferation of C2C12 cells.

SIGNIFICANCE

These findings provide novel insights into pathological mechanism of sarcopenia, and will facilitate the development of therapeutic and preventive strategies for sarcopenia.

CT-based assessment of sarcopenia for differentiating wild-type from mutant-type gastrointestinal stromal tumor

Non-invasive prediction for KIT/PDGFRA status in GIST is a challenging problem. This study aims to evaluate whether CT based sarcopenia could differentiate KIT/PDGFRA wild-type gastrointestinal stromal tumor (wt-GIST) from the mutant-type GIST (mu-GIST), and to evaluate genetic features of GIST. A total of 174 patients with GIST (wt-GIST = 52) were retrospectively identified between January 2011 to October 2019. A sarcopenia nomogram was constructed by multivariate logistic regression. The performance of the nomogram was evaluated by discrimination, calibration curve, and decision curve. Genomic data was obtained from our own specimens and also from the open databases cBioPortal. Data was analyzed by R version 3.6.1 and clusterProfiler ( http://cbioportal.org/msk-impact ). There were significantly higher incidence (75.0% vs. 48.4%) and more severe sarcopenia in patients with wt-GIST than in patients with mu-GIST. Multivariate logistic regression analysis showed that sarcopenia score (fitted based on age, gender and skeletal muscle index), and muscle fat index were independent predictors for higher risk of wt-GIST (P < 0.05 for both the training and validation cohorts). Our sarcopenia nomogram achieved a promising efficiency with an AUC of 0.879 for the training cohort, and 0.9099 for the validation cohort with a satisfying consistency in the calibration curve. Favorable clinical usefulness was observed using decision curve analysis. The additional gene sequencing analysis based on both our data and the external data demonstrated aberrant signal pathways being closely associated with sarcopenia in the wt-GIST. Our study supported the use of CT-based assessment of sarcopenia in differentiating the wt-GIST from the mu-GIST preoperatively.

TNF-α contributes to sarcopenia through caspase-8/caspase-3/GSDME-mediated pyroptosis

Sarcopenia has become a leading cause of disability and mortality in the elderly. It has been reported that programmed cell death (PCD) is associated with the development of sarcopenia that is characterized by reduction of muscle fiber size and number. TNF-α is also validated to play a prominent role in sarcopenia through its complex signaling pathways including cell death signaling. However, it is still unclear whether TNF-α contributes to sarcopenia by mediating pyroptosis, one type of PCD. Here, we first established naturally aged mice with sarcopenia model and confirmed an inflammatory state represented by TNF-α in aged mice. Evidence of GSDME-mediated pyroptosis and activation of apoptotic caspase-8/-3 were also found in skeletal muscle cells of aged mice with sarcopenia. We demonstrated that TNF-α triggered GSDME-mediated pyroptosis in myotubes through activating caspase-8 and caspase-3 by using caspase-8 and caspase-3 inhibitors. Comparing the activation of caspase-8 and GSDME expression between TNF Complex IIa and TNF Complex IIb, TNF-α was found to be more inclined to assemble TNF Complex IIb in activating caspase-8 and triggering pyroptosis. Moreover, pyroptotic myotubes were validated to result in decreased expression of MHC1 and finally loss of myotubes by knockdown of GSDME. Our work reveals a novel mechanism that TNF-ɑ/caspase-8/caspase-3/GSDME signaling-mediated pyroptosis contributes to the development of sarcopenia. Caspase-3/GSDME signaling-mediated pyroptosis may be a promising therapeutic target for sarcopenia.

Sarcopenia: Molecular regulatory network for loss of muscle mass and function

Skeletal muscle is the foundation of human function and plays a key role in producing exercise, bone protection, and energy metabolism. Sarcopenia is a systemic disease, which is characterized by degenerative changes in skeletal muscle mass, strength, and function. Therefore, sarcopenia often causes weakness, prolonged hospitalization, falls and other adverse consequences that reduce the quality of life, and even lead to death. In recent years, sarcopenia has become the focus of in-depth research. Researchers have suggested some molecular mechanisms for sarcopenia according to different muscle physiology. These mechanisms cover neuromuscular junction lesion, imbalance of protein synthesis and breakdown, satellite cells dysfunction, etc. We summarize the latest research progress on the molecular mechanism of sarcopenia in this review in order to provide new ideas for future researchers to find valuable therapeutic targets and develop relevant prevention strategies.

Dietary Guanidine Acetic Acid Addition Improved Carcass Quality with Less Back-Fat Thickness and Remarkably Increased Meat Protein Deposition in Rapid-Growing Lambs Fed Different Forage Types

The aim of this study was to investigate whether guanidine acetic acid (GAA) yields a response in rapid-growing lambs depending on forage type. In this study, seventy-two small-tailed Han lambs (initial body weights = 12 ± 1.6 kg) were used in a 120-d feeding experiment after a 7-d adaptation period. A 2 × 3 factorial experimental feeding design was applied to the lambs, which were fed a total mixed ration with two forage types (OH: oaten hay; OHWS: oaten hay plus wheat silage) and three forms of additional GAA (GAA: 0 g/kg; UGAA: Uncoated GAA, 1 g/kg; CGAA: Coated GAA, 1 g/kg). The OH diet had a greater dry matter intake, average daily gain, and hot carcass weight than the OHWS diet. The GAA supplementation increased the final body weight, hot carcass weight, dressing percentage, and ribeye area in the longissimus lumborum. Meanwhile, it decreased backfat thickness and serum triglycerides. Dietary GAA decreased the acidity of the meat and elevated the water-holding capacity in mutton. In addition, the crude protein content in mutton increased with GAA addition. Dietary GAA (UGAA or CGAA) might be an effective additive in lamb fed by different forage types, as it has potential to improve growth performance and meat quality.

Advanced glycation end products in skeletal muscle health and sarcopenia: A systematic review of observational studies

BACKGROUND

Advanced glycation end products (AGEs) and AGEs receptor (RAGE) may play a role in sarcopenia. This systematic review evaluated the associations between AGEs measured in tissues (skin) by autofluorescence (SAF) and/or circulation (blood, urine) and muscle health outcomes (strength, mass, function) and sarcopenia in observational studies.

METHODS

MEDLINE, Embase, Scopus and Web of Science were searched for studies reporting associations between AGEs and muscle-related outcomes in community-dwelling adults aged ≥ 30 years (until March 2022).

RESULTS

Fourteen cross-sectional and one prospective study were included in the narrative summary. SAF was negatively associated with muscle strength, mass, and physical functioning in adults aged ≥ 30 years (four studies), and muscle mass (three studies), strength, and sarcopenia (one study) in adults aged ≥ 65 years. Circulating AGEs were negatively associated with muscle strength and physical functioning (four studies) and predicted the risk of walking disability (one prospective study), and sarcopenia (one study) in older adults. The role of RAGE in muscle health was inconclusive.

CONCLUSIONS

SAF and circulating AGEs were negatively associated with muscle-related outcomes in adults aged ≥ 30 years in cross-sectional studies. This finding should be confirmed in well-designed prospective studies investigating sarcopenia, as AGEs represent a potentially modifiable target for intervention.

Is dexamethasone-induced muscle atrophy an alternative model for naturally aged sarcopenia model?

Background

Primary sarcopenia is usually known as age-related skeletal muscle loss; however, other factors like endocrine, lifestyle and inflammation can also cause muscle loss, known as secondary sarcopenia. Although many studies have used different sarcopenia animal models for exploring the underlying mechanism and therapeutic approaches for sarcopenia, limited study has provided evidence of the relevance of these animal models. This study aims to investigate the similarity and difference in muscle qualities between primary and secondary sarcopenia mice models, using naturally aged mice and dexamethasone-induced mice.

Methods

21-month-old mice were used as naturally aged primary sarcopenia mice and 3-month-old mice received daily intraperitoneal injection of dexamethasone (20 mg/ kg body weight) for 10 days were used as secondary sarcopenia model. This study provided measurements for muscle mass and functions, including Dual-energy X-ray absorptiometry (DXA) scanning, handgrip strength test and treadmill running to exhaustion test. Besides, muscle contraction, muscle fibre type measurements and gene expression were also performed to provide additional information on muscle qualities.

Results

The results suggest two sarcopenia animal models shared a comparable decrease in forelimb lean mass, muscle fibre size, grip strength and muscle contraction ability. Besides, the upregulation of protein degradation genes was also observed in two sarcopenia animal models. However, only primary sarcopenia mice were identified with an early stage of mtDNA deletion.

Conclusion

Collectively, this study evaluated that the dexamethasone-induced mouse model could be served as an alternative model for primary sarcopenia, according to the comparable muscle mass and functional changes. However, whether dexamethasone-induced mice can be used as an animal model when studying the molecular mechanisms of sarcopenia needs to be carefully evaluated.

The translational potential of this article

The purpose of sarcopenia research is to investigate appropriate treatments for reversing the loss of skeletal muscle mass and functions. Using animal models for the preclinical study could predict the safety and efficacy of the treatments. This study compared the typical age-related sarcopenia mice model and dexamethasone-induced secondary sarcopenia mice to provide evidence of the pathological and functional changes in the mice models.

Molecular Mechanisms to Target Cellular Senescence in Aging and Disease

Cellular senescence is a state of irreversible cell cycle arrest in response to several stressors, including DNA damage, increased cellular oxidative stress, telomere shortening, oncogene activation, and a deep epigenetic remodeling [...].

Complementary combination of biomarkers for diagnosis of sarcopenia in C57BL/6J mice

AIMS

The objective of this study is to provide a reliable strategy for the diagnosis of sarcopenia based on a complementary combination of biomarkers from various approaches.

MATERIAL AND METHODS

A total of 30 C57BL/6J mice were used for the experiment, in which 15 young mice (YM) at 24 weeks old and 15 aged mice (AM) at 88 weeks old. Extracted features-based digital biomarkers from the electromyography activity of tibialis anterior muscles were evaluated by using receiver operating characteristic analysis. Extracted tissular proteins and circulating hormones based chemical biomarkers were investigated by using immunoblotting and enzyme-linked immunosorbent assay.

KEY FINDINGS

In terms of digital biomarkers, the feature-based classification of mice groups showed good performance (Feature A: AUC = 0.986, accuracy = 0.928) and (Feature B: AUC = 0.999, accuracy = 0.990). On the other hand, muscle-specific protein levels based chemical biomarkers (e.g. MuRF1, FoxO1, and perilipin2) were observed significantly increase with age. Pro-inflammatory cytokines based biomarkers extracted from muscle tissue and circulating plasma (e.g. TNF-α, IL-6, and IL-8) were significantly higher in case of AM group compared to YM group. Circulating hormone-based chemical biomarkers (e.g. cortisol/DHEA ratio and cathepsin D) presented a significant increase in concentrations with age. Circulating neurotransmitter based biomarkers (e.g. acetylcholine, serotonin, and histamine) also increased significantly in concentrations from YM to AM.

SIGNIFICANCE

A complementary combination of digital and chemical biomarkers covers multiple domains of sarcopenia to provide an effective strategy for the early diagnosis of sarcopenia.

Toe Grip strength declines earlier than hand grip strength and knee extension strength in community-dwelling older men: a cross sectional study

Background

The aim of this study is to examine the age-related changes in the toe grip strength and its differences from hand grip strength and knee extension strength using cross-sectional data.

Methods

Of participants aged 65 years over who underwent health checkups for lifestyle-related diseases in 2018, 307 men and women met the criteria. Toe grip strength, hand grip strength, and knee extension strength were also measured as optional tests. The participants were divided into five groups categorized by every 5 years of age (Group 65–85). The data were analyzed with multiple comparisons using the linear mixed multilevel model to examine the following categories: association between age and muscle strength, differences in the pattern of change, and gender, using the 65–69 years group as a reference.

Results

In men, there were interaction effects between the factors of age and muscle, but in women there were not. Toe grip strength was significantly lower in Group 70, 75, 80, and 85 in men, lower in Group 85 than in 65 in women. Hand grip strength was significantly lower in Group 85 than in 65 in both men and women. There was no significant difference in knee extension strength among the age groups for both men and women.

Conclusions

The decline in toe grip strength may occur earlier and in a different pattern from hand grip strength and knee extension strength in men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00584-x.

Suppressive Effects of Turmeric Extract on Muscle Atrophy in Dexamethasone-Treated Mice and Myotubes

Sarcopenia is the decline in skeletal muscle mass, strength, and functions, which decreases the quality of life in elderly people. This study investigated the suppressive effect of turmeric (Curcuma longa) extract (TE) on muscle atrophy in dexamethasone (DEX)-treated mice and C2C12 myotubes. DEX treatment significantly decreased the muscle weight and significantly increased Fbxo32 and Murf1 expression in mice, and these changes were suppressed by the supplementation of an AIN-93 based diet with 2% TE. A similar pattern was observed in FBXO32 and MuRF1 protein expression. In C2C12 myotubes, DEX treatment significantly increased FBXO32 and MuRF1 gene and protein expression, and these increases were significantly suppressed by TE supplementation at a concentration of 200 µg/mL. Furthermore, one of the five TE fractions, which were separated by high-performance liquid chromatography had a similar effect with TE supplementation. The present study proposes the suppressive effect of turmeric on sarcopenia.

The non-modifiable factors age, gender, and genetics influence resistance exercise

Muscle mass and force are key for movement, life quality, and health. It is well established that resistance exercise is a potent anabolic stimulus increasing muscle mass and force. The response of a physiological system to resistance exercise is composed of non-modifiable (i.e., age, gender, genetics) and modifiable factors (i.e., exercise, nutrition, training status, etc.). Both factors are integrated by systemic responses (i.e., molecular signaling, genetic responses, protein metabolism, etc.), consequently resulting in functional and physiological adaptations. Herein, we discuss the influence of non-modifiable factors on resistance exercise: age, gender, and genetics. A solid understanding of the role of non-modifiable factors might help to adjust training regimes towards optimal muscle mass maintenance and health.

Effects of Lactobacillus curvatus HY7602-Fermented Antlers in Dexamethasone-Induced Muscle Atrophy

This study assessed the improvements yielded by Lactobacillus curvatus HY7602-fermented antlers (FA) in dexamethasone-induced muscle atrophy and the effects of bioactive compounds increased by fermentation. Dexamethasone-treated C2C12 myoblast cells were treated with FA and non-fermented antlers (NFA). FA showed inhibitory effects on muscle protein degradation in the C2C12 cells. Hsb:ICR mice were orally administered saline (control(CON) and dexamethasone only (DEX)), oxymetholone (DEX+OXY), NFA (DEX+NFA), and FA (DEX+FA) via gavage. Before the end of the experiment, dexamethasone was intraperitoneally (IP) injected into the mice, except in the control group, to induce muscle atrophy. Compared with the DEX group, the DEX+FA group exhibited a significant prevention in the reduction of hindlimb strength, calf thickness, calf muscle weight, and the cross-sectional area of muscle fibers (p < 0.05). The FA-induced improvements in muscle atrophy were associated with a decreased gene expression of protein degradation and growth inhibition, and an increased gene expression of protein synthesis and growth factors. Sialic acid, a bioactive compound associated with muscles, was increased by 51.41% after fermentation and suppressed the expression of protein degradation genes in the C2C12 cells. L. curvatus HY7602-fermented antlers with increased sialic acid after fermentation may therefore be useful for preventing and improving muscle atrophy.

Beneficial effects of whey protein peptides on muscle loss in aging mice models

Aging-related muscle loss is a hallmark of aging and is the cause of some negative outcomes. An optimized diet and supplements have a positive effect in slowing down the process of muscle loss. D-galactose(d-gal) has been used widely to develop aging model. This study explored the beneficial effects of whey protein peptides (WPPs) on sarcopenia in d-gal-induced aging mice. A total of 72 SPF male C57BL/6N mice were used in this study. Sixty mice were modeled by injected intraperitoneally with d-gal (100 mg/kg body weight for 6 weeks), and the other 12 mice were used as control, and injected with the same amount of normal saline. After 6 weeks, the modeled mice were randomly divided into the model control group, whey protein group (1.5 g/kg^*bw), and three WPPs intervention groups (0.3 g/kg^*bw, 1.5 g/kg^*bw, 3.0 g/kg^*bw), according to serum malondialdehyde (MDA) level. The test samples were orally given to mice by daily garaged. During the 30 days intervention period, the model control group, whey protein group, and WPPs group continued receiving intraperitoneal injections of d-gal, whereas the control group continued receiving intraperitoneal injections of normal saline. The results showed that WPPs could significantly improve the grip strength of aged mice. WPPs could significantly increase lean mass of aged mice and increase muscle weight of gastrocnemius and extensor digitorum longus. WPPs could significantly increase the level of insulin-like growth factor-1 (IGF-1) and reduce level of interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF-α) in serum. WPPs could affect the muscle fiber size in d-gal-induced aging mice. Its specific mechanism may be related to the activation of IGF-1/Akt/mTOR protein synthesis signaling pathway and reduction of the level of inflammation. These results indicate that WPPs can improve aging-related sarcopenia. Compared with whey protein, WPPs supplement seems a better form for sarcopenia.

Protein Biomarkers in Blood Reflect the Interrelationships Between Stroke Outcome, Inflammation, Coagulation, Adhesion, Senescence and Cancer

The most important predictors for outcomes after ischemic stroke, that is, for health deterioration and death, are chronological age and stroke severity; gender, genetics and lifestyle/environmental factors also play a role. Of all these, only the latter can be influenced after the event. Recurrent stroke may be prevented by antiaggregant/anticoagulant therapy, angioplasty of high-grade stenoses, and treatment of cardiovascular risk factors. Blood cell composition and protein biomarkers such as C-reactive protein or interleukins in serum are frequently considered as biomarkers of outcome. Here we aim to provide an up-to-date protein biomarker signature that allows a maximum of mechanistic understanding, to predict health deterioration following stroke. We thus surveyed protein biomarkers that were reported to be predictive for outcome after ischemic stroke, specifically considering biomarkers that predict long-term outcome (≥ 3 months) and that are measured over the first days following the event. We classified the protein biomarkers as immune‑inflammatory, coagulation-related, and adhesion-related biomarkers. Some of these biomarkers are closely related to cellular senescence and, in particular, to the inflammatory processes that can be triggered by senescent cells. Moreover, the processes that underlie inflammation, hypercoagulation and cellular senescence connect stroke to cancer, and biomarkers of cancer-associated thromboembolism, as well as of sarcopenia, overlap strongly with the biomarkers discussed here. Finally, we demonstrate that most of the outcome-predicting protein biomarkers form a close-meshed functional interaction network, suggesting that the outcome after stroke is partially determined by an interplay of molecular processes relating to inflammation, coagulation, cell adhesion and cellular senescence.

Effect of Physical Activity/Exercise on Oxidative Stress and Inflammation in Muscle and Vascular Aging

Functional status is considered the main determinant of healthy aging. Impairment in skeletal muscle and the cardiovascular system, two interrelated systems, results in compromised functional status in aging. Increased oxidative stress and inflammation in older subjects constitute the background for skeletal muscle and cardiovascular system alterations. Aged skeletal muscle mass and strength impairment is related to anabolic resistance, mitochondrial dysfunction, increased oxidative stress and inflammation as well as a reduced antioxidant response and myokine profile. Arterial stiffness and endothelial function stand out as the main cardiovascular alterations related to aging, where increased systemic and vascular oxidative stress and inflammation play a key role. Physical activity and exercise training arise as modifiable determinants of functional outcomes in older persons. Exercise enhances antioxidant response, decreases age-related oxidative stress and pro-inflammatory signals, and promotes the activation of anabolic and mitochondrial biogenesis pathways in skeletal muscle. Additionally, exercise improves endothelial function and arterial stiffness by reducing inflammatory and oxidative damage signaling in vascular tissue together with an increase in antioxidant enzymes and nitric oxide availability, globally promoting functional performance and healthy aging. This review focuses on the role of oxidative stress and inflammation in aged musculoskeletal and vascular systems and how physical activity/exercise influences functional status in the elderly.

Protective Effect of Delta-Like 1 Homolog Against Muscular Atrophy in a Mouse Model

BACKGRUOUND

Muscle atrophy is caused by an imbalance between muscle growth and wasting. Delta-like 1 homolog (DLK1), a protein that modulates adipogenesis and muscle development, is a crucial regulator of myogenic programming. Thus, we investigated the effect of exogenous DLK1 on muscular atrophy.

METHODS

We used muscular atrophy mouse model induced by dexamethasone (Dex). The mice were randomly divided into three groups: (1) control group, (2) Dex-induced muscle atrophy group, and (3) Dex-induced muscle atrophy group treated with DLK1. The effects of DLK1 were also investigated in an in vitro model using C2C12 myotubes.

RESULTS

Dex-induced muscular atrophy in mice was associated with increased expression of muscle atrophy markers and decreased expression of muscle differentiation markers, while DLK1 treatment attenuated these degenerative changes together with reduced expression of the muscle growth inhibitor, myostatin. In addition, electron microscopy revealed that DLK1 treatment improved mitochondrial dynamics in the Dex-induced atrophy model. In the in vitro model of muscle atrophy, normalized expression of muscle differentiation markers by DLK1 treatment was mitigated by myostatin knockdown, implying that DLK1 attenuates muscle atrophy through the myostatin pathway.

CONCLUSION

DLK1 treatment inhibited muscular atrophy by suppressing myostatin-driven signaling and improving mitochondrial biogenesis. Thus, DLK1 might be a promising candidate to treat sarcopenia, characterized by muscle atrophy and degeneration.

Black Ginseng Ameliorates Cellular Senescence via p53-p21/p16 Pathway in Aged Mice

Simple Summary

The goal of this study was to examine if BG impacts the aging process, specifically cellular senescence, using in vitro and aged mouse models. Primary mouse embryonic fibroblasts (MEFs) and aged mice (18 months old) showed that BG supplementation retarded cellular senescence. Of note, BG-supplemented aged mice had remarkedly altered hepatic genes involved in the aging process as it caused less activation of the canonical senescence pathway. These observations demonstrated that BG positively impacts the age-related phenotype by controlling the expression of cellular senescence in the liver and other metabolic organs such as skeletal muscle and white adipose tissue.

Abstract

Cellular senescence, one of the hallmarks of aging, refers to permanent cell cycle arrest and is accelerated during the aging process. Black ginseng (BG), prepared by a repeated steaming and drying process nine times from fresh ginseng (Panax ginseng C.A. Meyer), is garnering attention for herbal medicine due to its physiological benefits against reactive oxygen species (ROS), inflammation, and oncogenesis, which are common cues to induce aging. However, which key nodules in the cellular senescence process are regulated by BG supplementation has not been elucidated yet. In this study, we investigated the effects of BG on cellular senescence using in vitro and aged mouse models. BG-treated primary mouse embryonic fibroblasts (MEFs) in which senescence was triggered by ionizing radiation (IR) expressed less senescence-associated β-galactosidase (SA-β-gal)-positive stained cells. In our aged mice (18 months old) study, BG supplementation (300 mg/kg) for 4 weeks altered hepatic genes involved in the aging process. Furthermore, we found BG supplementation downregulated age-related inflammatory genes, especially in the complement system. Based on this observation, we demonstrated that BG supplementation led to less activation of the canonical senescence pathway, p53-dependent p21 and p16, in multiple metabolic organs such as liver, skeletal muscle and white adipose tissue. Thus, we suggest that BG is a potential senolytic candidate that retards cellular senescence.

Fruit of Schisandra chinensis and its bioactive component schizandrin B ameliorate obesity-induced skeletal muscle atrophy

Schisandra chinensis fruit (Omiza in Korean), used for the production tea or liquor, and is known to enhance skeletal muscle function. However, the effect of Omiza extract (OM) on obesity-induced skeletal muscle atrophy remains unclear. This study investigated the effect of OM on skeletal muscle mass and performance in obese mice. OM increased skeletal muscle weight, size and improved skeletal muscle performance. Further, it also suppressed obesity-induced increases in proinflammatory cytokines, MuRF1, and Atrogin1 in mouse skeletal muscle and enhanced the expression of MHC and the phosphorylation of AKT/mTOR signaling molecules, thereby suppressing myostatin expression and regulating Smad-FOXO signaling. Schizandrin B, a major component of OM inhibited palmitic acid induced atrophy in C2C12 cells via Smad-FOXO regulation, suggesting that it partially contributed to the effects of OM against obesity-induced muscle atrophy. Taken together, OM may have the potential to prevent and treat obesity-induced muscle atrophy.

Beneficial Effects of Walnut Oligopeptides on Muscle Loss in Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice: Focusing on Mitochondrial Function

Aging-related muscle loss is a hallmark of aging and is the cause of some negative outcomes. An optimized diet and supplements have a positive effect in slowing down the process of muscle loss. This study was designed to evaluate the beneficial effects of walnut oligopeptides (WOPs) on aging-related muscle loss and explore the possible underlying mechanism in Senescence-Accelerated Mouse Prone 8 (SAMP8) Mice. SAMP8 mice were randomly divided into four groups (n = 15/group), including one group which was the SAMP8 age control group and three groups those were WOP intervention groups. Meanwhile, Senescence Accelerated Resistant Mouse 1 (SAMR1) mice (n = 12), which had normal senescence rates, were used as model controls. During the six-month intervention period, the age control and normal control groups were given sterilized water, while the three WOP intervention groups were given WOP solution with low (110 mg/kg·bw), medium (220 mg/kg·bw) and high concentrations (440 mg/kg·bw), respectively. The results showed that WOPs could significantly increase muscle mass and improve physical performance (wire hang and catwalk behavioral tests) in aging mice. Moreover, WOPs could significantly reduce the levels of IL-1β, IL-6 and TNF-α in serum and gastrocnemius tissues and increase the mitochondrial DNA content, as well as the expression levels of AMPK, PGC-1α, NRF-1 and TFAM in the gastrocnemius muscle of aging mice, which was speculated to be the specific mechanism related to mitochondrial function improvement and inflammation reduction. These results indicate that WOPs can improve aging-related muscle loss, in term of both muscle mass and physical performance, and WOP supplements seems to be potentially effective in elderly individuals.

Identification of the shared gene signatures and pathways between sarcopenia and type 2 diabetes mellitus

Background

Sarcopenia is characterized by the age-associated loss of skeletal muscle mass and strength that develops progressively and plays an important role in the disability of the elderly. It has received growing attention over the last decade and has been implicated as both a cause and consequence of type 2 diabetes mellitus (T2DM). The existence of T2DM could increase the risk of developing sarcopenia through multiple mechanisms including advanced glycation end-product accumulation. Meanwhile, sarcopenia would alter glucose disposal and may contribute to the development and progression of T2DM due to reduced muscle mass.

Methods

We implemented transcriptomic analysis of skeletal muscle biopsy specimens in sarcopenia patients and proliferating myoblasts or differentiated myotubes from individuals with T2DM. Related microarray data were selected from Gene Expression Omnibus (GEO) to screen the genes, which were differentially expressed for sarcopenia and T2DM. Multiple combinatorial statistical methods and bioinformatics tools were used to analyze the common DEGs. Meanwhile, functional enrichment analysis was also carried out. Furthermore, we constructed the protein-protein interaction (PPI), as well as transcription factor (TF)-gene interactions network and TF-miRNA coregulatory network. Finally, based on the common DEGs, drug compounds were speculated using the Drug Signatures database (DSigDB).

Results

A total of 1765 and 2155 DEGs of sarcopenia and T2DM were screened, respectively. 15 common genes (LXN, CIB2, PEA15, KANK2, FGD1, NMRK1, PLCB1, SEMA4G, ADARB1, UPF3A, CSTB, COL3A1, CD99, ETV3, FJX1) correlated with sarcopenia and T2DM simultaneously were then identified, and 3 genes (UPF3A, CSTB and PEA15) of them were regarded as hub genes. Functional enrichment analysis revealed several shared pathways between two diseases. In addition, according to the TF-gene interactions network and TF-miRNA coregulatory network, part of TF and miRNA may be identified as key regulator in sarcopenia and T2DM at the same time (e.g., CREM and miR-155). Notably, drug compounds for T2DM and sarcopenia were also suggested, such as coenzyme Q10.

Conclusion

This study revealed that sarcopenia and T2DM may share similar pathogenesis and provided new biological targets and ideas for early diagnosis and effective treatment of sarcopenia and T2DM.

Sarcopenia in rheumatic disorders: what the radiologist and rheumatologist should know

Sarcopenia is defined as the loss of muscle mass, strength, and function. Increasing evidence shows that sarcopenia is common in patients with rheumatic disorders. Although sarcopenia can be diagnosed using bioelectrical impedance analysis or DXA, increasingly it is diagnosed using CT, MRI, and ultrasound. In rheumatic patients, CT and MRI allow "opportunistic" measurement of body composition, including surrogate markers of sarcopenia, from studies obtained during routine patient care. Recognition of sarcopenia is important in rheumatic patients because sarcopenia can be associated with disease progression and poor outcomes. This article reviews how opportunistic evaluation of sarcopenia in rheumatic patients can be accomplished and potentially contribute to improved patient care.

Probiotic supplementation attenuates age-related sarcopenia via the gut-muscle axis in SAMP8 mice

BACKGROUND

Age-related muscle dysfunctions are common disorders resulting in poor quality of life in the elderly. Probiotic supplementation is a potential strategy for preventing age-related sarcopenia as evidence suggests that probiotics can enhance muscle function via the gut-muscle axis. However, the effects and mechanisms of probiotics in age-related sarcopenia are currently unknown. In this study, we examined the effects of Lactobacillus casei Shirota (LcS), a probiotic previously reported to improve muscle function in young adult mice.

METHODS

We administered LcS (1 × 10⁸ or 1 × 10⁹  CFU/mouse/day) by oral gavage to senescence-accelerated mouse prone-8 mice for 12 weeks (16- to 28-week-old). Sixteen-week-old and 28-week-old SMAP8 mice were included as non-aged and aged controls, respectively. Muscle condition was evaluated using dual-energy X-ray absorptiometry for muscle mass, holding impulse and grip strength tests for muscle strength, and oxygen consumption rate, gene expressions of mitochondrial biogenesis, and mitochondrial number assays for mitochondria function. Inflammatory cytokines were determined using enzyme-linked immunosorbent assay. Gas chromatography-mass spectrometry was utilized to measure the short-chain fatty acid levels. The gut microbiota was analysed based on the data of 16S rRNA gene sequencing of mouse stool.

RESULTS

The LcS supplementation reduced age-related declines in muscle mass (>94.6%, P < 0.04), strength (>66% in holding impulse and >96.3% in grip strength, P < 0.05), and mitochondrial function (P < 0.05). The concentration of short-chain fatty acids (acetic, isobutyric, butyric, penic, and hexanoic acid) was recovered by LcS (>65.9% in the mice given high dose of LcS, P < 0.05) in the aged mice, and LcS attenuated age-related increases in inflammation (P < 0.05) and reactive oxygen species (>89.4%, P < 0.001). The high dose of LcS supplementation was also associated with distinct microbiota composition as indicated by the separation of groups in the beta-diversity analysis (P = 0.027). LcS supplementation altered predicted bacterial functions based on the gut microbiota. Apoptosis (P = 0.026), p53 signalling (P = 0.017), and non-homologous end-joining (P = 0.031) were significantly reduced, whereas DNA repair and recombination proteins (P = 0.043), RNA polymerase (P = 0.008), and aminoacyl-tRNA biosynthesis (P = 0.003) were increased. Finally, the genera enriched by high-dose LcS [linear discriminant analysis (LDA) score > 2.0] were positively correlated with healthy muscle and physiological condition (P < 0.05), while the genera enriched in aged control mice (LDA score > 2.0) were negatively associated with healthy muscle and physiological condition (P < 0.05).

CONCLUSIONS

Lactobacillus casei Shirota represents an active modulator that regulates the onset and progression of age-related muscle impairment potentially via the gut-muscle axis.