Role of Pro-inflammatory Cytokines in Regulation of Skeletal Muscle Metabolism: A Systematic Review

Vascular Impairment, Muscle Atrophy, and Cognitive Decline: Critical Age-Related Conditions

The triad of vascular impairment, muscle atrophy, and cognitive decline represents critical age-related conditions that significantly impact health. Vascular impairment disrupts blood flow, precipitating the muscle mass reduction seen in sarcopenia and the decline in neuronal function characteristic of neurodegeneration. Our limited understanding of the intricate relationships within this triad hinders accurate diagnosis and effective treatment strategies. This review analyzes the interrelated mechanisms that contribute to these conditions, with a specific focus on oxidative stress, chronic inflammation, and impaired nutrient delivery. The aim is to understand the common pathways involved and to suggest comprehensive therapeutic approaches. Vascular dysfunctions hinder the circulation of blood and the transportation of nutrients, resulting in sarcopenia characterized by muscle atrophy and weakness. Vascular dysfunction and sarcopenia have a negative impact on physical function and quality of life. Neurodegenerative diseases exhibit comparable pathophysiological mechanisms that affect cognitive and motor functions. Preventive and therapeutic approaches encompass lifestyle adjustments, addressing oxidative stress, inflammation, and integrated therapies that focus on improving vascular and muscular well-being. Better understanding of these links can refine therapeutic strategies and yield better patient outcomes. This study emphasizes the complex interplay between vascular dysfunction, muscle degeneration, and cognitive decline, highlighting the necessity for multidisciplinary treatment approaches. Advances in this domain promise improved diagnostic accuracy, more effective therapeutic options, and enhanced preventive measures, all contributing to a higher quality of life for the elderly population.

Functional Food Mixture Extricates D-Galactose-Induced Skeletal Muscle Impairment in Rats

Aging-related muscle atrophy/sarcopenia is the most common type of muscle impairment that affects the quality of life. In the current study, we examined the effect of a functional food mixture of amla, turmeric, black pepper, cinnamon, and ginger on D-galactose-induced muscle alterations in rats. Wistar rats were randomly divided into three groups: Control (C), D-galactose (G), and D-galactose + functional food mixture intervention (G + I). Rats in group-G and -G + I were injected with D-galactose (300 mg/kg/day) for 90 days. After 3 months of the experimental period, the rats were sacrificed to collect gastrocnemius muscle. Group-G rats showed elevated levels of inflammatory cytokines (TNFα and NF-kB), atrogenes (atrogin-1 and MuRF1), decreased insulin/IGF1 signaling (decreased AKT phosphorylation), altered mitochondrial dynamics (increased fission and decreased fusion proteins), increased apoptotic mediators (Bax/Bcl-2, and caspase-3), and decreased muscle cell cross-sectional area when compared with group-C (p < 0.05). Interestingly, supplementation with the functional food mixture prevented galactose-induced alterations in the muscle. The observed anti-inflammatory, insulin-sensitizing, mitochondria-protective, and antiapoptotic effects of the functional food could be the underlying mechanisms in displaying positive effects against galactose-induced muscle atrophy and, hence, may be useful for the prevention of age-related muscle disorders.

Skeletal muscle mass and quality in gout patients versus non-gout controls: A computed tomography imaging study

OBJECTIVE

Patients with gout are at elevated risk of multiple vascular and metabolic comorbidities. Whether they are also at risk of sarcopenia, which is known to affect patients with other rheumatic diseases, has not been previously assessed. We examined whether patients with gout have decreased lumbar muscle quality and quantity, indicating an association between gout and sarcopenia.

METHODS

Fifty gout subjects and 25 controls, ages 45-80, underwent computed tomography imaging of the lumbosacral spine. We measured muscle quantity (skeletal muscle area [SMA] and index [SMI]) and quality (skeletal muscle radiation attenuation [SMRA] and intermuscular adipose tissue [IMAT] area and index [IMATI]) of the psoas and erector spinae muscles at the L3 level.

RESULTS

Seventy subjects (45 gout and 25 controls) were included in the analysis. Gout subjects had higher BMI, more kidney disease and hypertension, lower exercise frequency, and higher mean serum urate and creatinine vs. controls. Lumbar SMRA was significantly lower in gout subjects vs. controls, indicating reduced muscle quality. Lumbar IMAT area was significantly higher in gout subjects vs. controls, as was lumbar IMATI, indicating increased muscle adiposity. These differences persisted after adjusting for potential confounders. In contrast, there was no significant difference between gout and control groups in lumbar SMA or lumbar SMI, suggesting that muscle quantity may not be routinely affected by the diagnosis of gout.

CONCLUSIONS

Gout patients exhibit decreased lumbar muscle quality compared with controls, consistent with an association between gout and sarcopenia.

Association between immune cells, inflammatory cytokines, and sarcopenia: Insights from a Mendelian randomization analysis

BACKGROUND

Recent studies have suggested a possible link between sarcopenia, immune dysregulation, and chronic inflammation, although the specific immune components implicated remain unclear. This investigation employs Mendelian Randomization (MR) to explore the reciprocal relationship between immune cells, inflammatory markers, and sarcopenia.

METHOD

We performed two-sample and multivariate MR analyses using publicly accessible genome-wide association studies (GWAS) summary statistics. Our analyses included 731 immune cells, 41 inflammatory cytokines, and sarcopenia related traits (appendicular lean mass [ALM], low hand-grip strength [LHS], and walking pace [WP]), with additional sensitivity analyses conducted to confirm the findings.

RESULTS

After false discovery rate (FDR) correction, significant associations were found between ten immune traits and ALM, with the CD127 marker in the Treg panel showing consistent positive correlation across four sites. In contrast, NKT%lymphocyte negatively correlated with WP (OR = 0.99, P = 0.023). In terms of inflammatory cytokines, macrophage colony-stimulating factor (MCSF) (OR = 1.03, P = 0.024) and hepatocyte growth factor (HGF) (OR = 1.03, P = 0.002) demonstrated positive associations with ALM, while interleukin-16 (IL-16) (OR = 0.99, P = 0.006) was inversely related. The reverse Mendelian randomization analysis found no direct causal links between sarcopenia traits and immune or inflammatory markers. Sensitivity analyses underscored the findings' resilience to pleiotropy, and adjusting for inter-trait dynamics weakened these relationships in the multivariable MR analysis.

CONCLUSION

Our study reveals causal associations between specific immune phenotypes, inflammatory cytokines, and sarcopenia, providing insight into the development of sarcopenia and potential treatment strategies.

Streptococcal quorum sensing peptide CSP-7 contributes to muscle inflammation and wasting

Muscle wasting diseases, such as cancer cachexia and age-associated sarcopenia, have a profound and detrimental impact on functional independence, quality of life, and survival. Our understanding of the underlying mechanisms is currently limited, which has significantly hindered the development of targeted therapies. In this study, we explored the possibility that the streptococcal quorum sensing peptide Competence Stimulating Peptide 7 (CSP-7) might be a previously unidentified contributor to clinical muscle wasting. We found that CSP-7 selectively triggers muscle cell inflammation in vitro, specifically the release of IL-6. Furthermore, we demonstrated that CSP-7 can traverse the gastrointestinal barrier in vitro and is present in the systemic circulation in humans in vivo. Importantly, CSP-7 was associated with a muscle wasting phenotype in mice in vivo. Overall, our findings provide new mechanistic insights into the pathophysiology of muscle inflammation and wasting.

Transcriptome-based deep learning analysis identifies drug candidates targeting protein synthesis and autophagy for the treatment of muscle wasting disorder

Sarcopenia, the progressive decline in skeletal muscle mass and function, is observed in various conditions, including cancer and aging. The complex molecular biology of sarcopenia has posed challenges for the development of FDA-approved medications, which have mainly focused on dietary supplementation. Targeting a single gene may not be sufficient to address the broad range of processes involved in muscle loss. This study analyzed the gene expression signatures associated with cancer formation and 5-FU chemotherapy-induced muscle wasting. Our findings suggest that dimenhydrinate, a combination of 8-chlorotheophylline and diphenhydramine, is a potential therapeutic for sarcopenia. In vitro experiments demonstrated that dimenhydrinate promotes muscle progenitor cell proliferation through the phosphorylation of Nrf2 by 8-chlorotheophylline and promotes myotube formation through diphenhydramine-induced autophagy. Furthermore, in various in vivo sarcopenia models, dimenhydrinate induced rapid muscle tissue regeneration. It improved muscle regeneration in animals with Duchenne muscular dystrophy (DMD) and facilitated muscle and fat recovery in animals with chemotherapy-induced sarcopenia. As an FDA-approved drug, dimenhydrinate could be applied for sarcopenia treatment after a relatively short development period, providing hope for individuals suffering from this debilitating condition.

Effects of Particulate Matter Inhalation during Exercise on Oxidative Stress and Mitochondrial Function in Mouse Skeletal Muscle

Particulate matter (PM) has deleterious consequences not only on the respiratory system but also on essential human organs, such as the heart, blood vessels, kidneys, and liver. However, the effects of PM inhalation on skeletal muscles have yet to be sufficiently elucidated. Female C57BL/6 or mt-Keima transgenic mice were randomly assigned to one of the following four groups: control (CON), PM exposure alone (PM), treadmill exercise (EX), or PM exposure and exercise (PME). Mice in the three-treatment group were subjected to treadmill running (20 m/min, 90 min/day for 1 week) and/or exposure to PM (100 μg/m3). The PM was found to exacerbate oxidative stress and inflammation, both at rest and during exercise, as assessed by the levels of proinflammatory cytokines, manganese-superoxide dismutase activity, and the glutathione/oxidized glutathione ratio. Furthermore, we detected significant increases in the levels of in vivo mitophagy, particularly in the PM group. Compared with the EX group, a significant reduction in the level of mitochondrial DNA was recorded in the PME group. Moreover, PM resulted in a reduction in cytochrome c oxidase activity and an increase in hydrogen peroxide generation. However, exposure to PM had no significant effect on mitochondrial respiration. Collectively, our findings in this study indicate that PM has adverse effects concerning both oxidative stress and inflammatory responses in skeletal muscle and mitochondria, both at rest and during exercise.

Effects of Horse Meat Hydrolysate on Oxidative Stress, Proinflammatory Cytokines, and the Ubiquitin-Proteasomal System of C2C12 Cells

Sarcopenia, the age-related muscle atrophy, is a serious concern as it is associated with frailty, reduced physical functions, and increased mortality risk. Protein supplementation is essential for preserving muscle mass, and horse meat can be an excellent source of proteins. Since sarcopenia occurs under conditions of oxidative stress, this study aimed to investigate the potential anti-muscle atrophy effect of horse meat hydrolysate using C2C12 cells. A horse meat hydrolysate less than 3 kDa (A4<3kDa) significantly increased the viability of C2C12 myoblasts against H2O2-induced cytotoxicity. Exposure of C2C12 myoblasts to lipopolysaccharide led to an elevation of cellular reactive oxygen species levels and mRNA expression of proinflammatory cytokines, including tumor necrosis factor-α and interleukin 6, and these effects were attenuated by A4<3kDa treatment. Additionally, A4<3kDa activated protein synthesis-related proteins through the protein kinase B/mechanistic target of rapamycin pathway, while decreasing the expression of activity and degradation-related proteins, such as Forkhead box O3, muscle RING finger protein-1, and Atrogin-1 in dexamethasone-treated C2C12 myotubes. Therefore, the natural material A4<3kDa has the potential ofprotecting against muscle atrophy, while further in vivo study is needed.

Energy Regulation in Inflammatory Sarcopenia by the Purinergic System

The purinergic system has a dual role: the maintenance of energy balance and signaling within cells. Adenosine and adenosine triphosphate (ATP) are essential for maintaining these functions. Sarcopenia is characterized by alterations in the control of energy and signaling in favor of catabolic pathways. This review details the association between the purinergic system and muscle and adipose tissue homeostasis, discussing recent findings in the involvement of purinergic receptors in muscle wasting and advances in the use of the purinergic system as a novel therapeutic target in the management of sarcopenia.

Salbutamol ameliorates skeletal muscle wasting and inflammatory markers in streptozotocin (STZ)-induced diabetic rats

Diabetes accelerates muscle atrophy, leading to the deterioration of skeletal muscles. This study aimed to assess the potential of the β2-adrenoceptor agonist, salbutamol (SLB), to alleviate muscle atrophy in streptozotocin (STZ)-induced diabetic rats. Male Sprague Dawley rats were randomized into four groups (n=6): control, SLB, STZ (55 mg/kg, single i.p.), and STZ + SLB (6 mg/kg, orally for 4 weeks). After the final SLB dose, animals underwent tests to evaluate muscle strength and coordination, including forelimb grip strength, wire-hanging, actophotometer, rotarod, and footprint assessments. Rats were then sacrificed, and serum and gastrocnemius (GN) muscles were collected for further analysis. Serum evaluations included proinflammatory markers (tumor necrosis factor α, interleukin-1β, interleukin-6), muscle markers (creatine kinase, myostatin), testosterone, and lipidemic markers. Muscle oxidative stress (malonaldehyde, protein carbonyl), antioxidants (glutathione, catalase, superoxide dismutase), and histology were also performed. Additionally, 1H nuclear magnetic resonance serum profiling was conducted. SLB notably enhanced muscle grip strength, coordination, and antioxidant levels, while reduced proinflammatory markers and oxidative stress in STZ-induced diabetic rats. Reduced serum muscle biomarkers, increased testosterone, restored lipidemic levels, and improved muscle cellular architecture indicated SLB's positive effect on muscle condition in diabetic rats. Metabolomics profiling revealed that the STZ group significantly increased the phenylalanine-to-tyrosine ratio (PTR), lactate-to-pyruvate ratio (LPR), acetate, succinate, isobutyrate, and histidine. SLB administration restored these perturbed serum metabolites in the STZ-induced diabetic group. In conclusion, salbutamol significantly protected against skeletal muscle wasting in STZ-induced diabetic rats.

Silk Peptide Ameliorates Sarcopenia through the Regulation of Akt/mTOR/FoxO3a Signaling Pathways and the Inhibition of Low-Grade Chronic Inflammation in Aged Mice

As populations around the world age, interest in healthy aging is growing. One of the first physical changes that occurs with aging is the loss of muscle mass and strength, termed sarcopenia. Sarcopenia limits the activity of older people, reduces their quality of life, and increases the likelihood of their developing disease. In the present study, we aimed to evaluate the effects of the ingestion of acid-hydrolyzed silk peptide (SP) on the muscle mass and strength of mice of >22 months of age with naturally occurring sarcopenia, and to identify the mechanisms involved. The daily administration of SP for 8 weeks increased the activation of the Akt/mTOR/FoxO3a signaling pathways and increased the muscle mass and strength of the old mice. In addition, SP inhibited oxidative stress and inflammation in muscle, which are direct causes of sarcopenia. Therefore, SP represents a promising potential treatment for sarcopenia that may improve the healthy lifespan and quality of life of older people.

Dipyridamole activates adenosine A2B receptor and AMPK/cAMP signaling and promotes myogenic differentiation of myoblastic C2C12 cells

Introduction: Sarcopenia is defined as a loss of muscle mass and strength. ATP homeostasis is crucial during myogenesis. We determined how the purinergic system modulates myogenesis using dipyridamole (blocks adenosine taken up by the cells) and tenofovir (inhibits ATP release) in a myoblast cell line. Methods: C2C12 cells were differentiated in the presence/absence of tenofovir/dipyridamole, with/without the A2B selective inhibitor PSB-603. Extra-/intracellular nucleotides were examined via HPLC. The expression of muscle differentiation proteins (Pax7, Mif5, MyoD, MyoG, and MHC), PKA/CREB, adenosine receptors (A1, A2A, A2B, and A3), ATP-channel pannexin-1 and the P2X7 receptor was analyzed via WB and RT-PCR. cAMP and AMPK activation was measured. Results: Tenofovir increased intracellular ATP and reduced extracellular adenosine, decreasing Pax7 expression and increasing MHC expression prematurely. Dipyridamole increased intracellular AMP and extracellular adenosine, counteracting the premature myogenesis promoted by tenofovir. All adenosine receptors were expressed during differentiation with dipyridamole, increasing A2B expression. Tenofovir maintained inactive AMPK and decreased cAMP levels, as well as PKAα and pCREB expression, which were recovered with dipyridamole. Discussion: Adenosine and ATP act as mediators in muscle myogenesis. The blockade of ATP release by tenofovir promotes premature myogenesis, with dipyridamole counteracting the premature differentiation promoted by tenofovir via the adenosine A2B receptor and cAMP/AMPK pathways. Therefore, dipyridamole might be of interest as a therapeutic approach in sarcopenia.

Role of nutrition in patients with coexisting chronic obstructive pulmonary disease and sarcopenia

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases in the elderly population and is characterized by persistent respiratory symptoms and airflow obstruction. During COPD progression, a variety of pulmonary and extrapulmonary complications develop, with sarcopenia being one of the most common extrapulmonary complications. Factors that contribute to the pathogenesis of coexisting COPD and sarcopenia include systemic inflammation, hypoxia, hypercapnia, oxidative stress, protein metabolic imbalance, and myocyte mitochondrial dysfunction. These factors, individually or in concert, affect muscle function, resulting in decreased muscle mass and strength. The occurrence of sarcopenia severely affects the quality of life of patients with COPD, resulting in increased readmission rates, longer hospital admission, and higher mortality. In recent years, studies have found that oral supplementation with protein, micronutrients, fat, or a combination of nutritional supplements can improve the muscle strength and physical performance of these patients; some studies have also elucidated the possible underlying mechanisms. This review aimed to elucidate the role of nutrition among patients with coexisting COPD and sarcopenia.

Hesperidin Ameliorates Sarcopenia through the Regulation of Inflammaging and the AKT/mTOR/FoxO3a Signaling Pathway in 22-26-Month-Old Mice

Faced with a globally aging society, the maintenance of health and quality of life in older people is very important. The age-related loss of muscle mass and strength, known as sarcopenia, severely reduces quality of life and increases the risks of various diseases. In this study, we investigated the inhibitory effect of hesperidin (HES) on inflammaging, with the intention of evaluating its potential use as a treatment for sarcopenia. We studied 22-26-month-old mice, corresponding to humans aged ≥70 years, with aging-related sarcopenia, and young mice aged 3-6 months. The daily administration of HES for 8 weeks resulted in greater muscle mass and strength and increased the fiber size of the old mice. HES also restored the immune homeostasis that had been disrupted by aging, such as the imbalance in M1/M2 macrophage ratio. In addition, we found that HES ameliorated the sarcopenia by regulating AKT/mammalian target of rapamycin/forkhead box 3a signaling through an increase in insulin-like growth factor (IGF)-1 expression in the old mice. Therefore, HES represents a promising candidate inhibitor of sarcopenia in older people, and its effects are achieved through the maintenance of immune homeostasis.

Effects of biologic and target synthetic disease-modifying anti-rheumatic drugs on sarcopenia in spondyloarthritis and rheumatoid arthritis: a systematic review and meta-analysis

Sarcopenia is a syndrome defined by generalized and progressive loss of skeletal muscle mass, strength, and function. Besides affecting elderly population, it is actually common among inflammatory rheumatic diseases (IRD) patients. We performed a systematic literature review with a meta-analysis to investigate the influence of biologic and target synthetic disease-modifying anti-rheumatic drugs (bDMARDs/tsDMARDs) on sarcopenia in IRD. A systematic search has been performed on Pubmed, Scopus, and Web of science. Studies characteristics were collected. Assessment tools were body composition (total lean mass (TLM) and percentage, appendicular skeletal mass (ASM), fat-free mass and index (FFM and FFMI), skeletal mass index (SMI) and segmental lean mass (SLM)), and muscle strength and physical performance tests. Treatment effect defined the difference in change from baseline to the end of follow-up treatment was divided by the pooled SD of the difference. Twenty-two studies on 778 patients receiving bDMARDs/tsDMARDs and 157 controls were reviewed. They investigated rheumatoid arthritis (RA) (N = 14), spondyloarthritis (SpA) (N = 6), psoriatic arthritis (N = 1), and both RA and SpA (N = 1). tsDMARDs were used in one study with no effect on sarcopenia. Ten studies demonstrated that bDMARDs increased significantly muscle measures in 347 patients (44.6%) with a significant increase in TLM (6/15 studies; 57.4%), FFMI (4/6 studies; 59.9%), ASM (2/5 studies; 17.6%), SMI (2/5 studies; 18.1%), and SLM (2/2 studies; 3.6%). bDMARDs showed also a positive effect on handgrip strength in 1/3 of studies (45.2%) and on physical performance in 1/2 of studies (61%). In 1/5 of comparative studies, IRD patients on bDMARDs showed significantly higher increase of TLM in comparison to controls naïve bDMARDs. Regarding diagnosis, positive effect of bDMARDs was seen in 67.4% in SpA versus 49.3% in RA, with a significant increase of TLM, ASM and FFMI in 59.4%, 100%, and 65.2% in SpA versus 54.9%, 24.1%, and 54.8% in RA, respectively. Meta-analysis assessed the effect of bDMARD on TLM in 10 studies. There was no statistically significant difference [SMD - 0.10 (95% Confidence Interval - 0.26 - 0.06; tau² = 0). Heterogeneity across studies was null, and the 95% confidence interval (index of precision) was equal to the 95% predictive interval. The first systematic literature review showed that bDMARDs have a significant improve effect in nearly half of RA and SpA patients on muscle mass and muscle strength, assessed separately. However, the meta-analysis concluded that bDMARDs have no significant effect on TLM.

An Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to the MSG-Induced Obesity Model

The model of obesity induced by monosodium glutamate cytotoxicity on the hypothalamic nuclei is widely used in the literature. However, MSG promotes persistent muscle changes and there is a significant lack of studies that seek to elucidate the mechanisms by which damage refractory to reversal is established. This study aimed to investigate the early and chronic effects of MSG induction of obesity upon systemic and muscular parameters of Wistar rats. The animals were exposed to MSG subcutaneously (4 mg·g^-1 b.w.) or saline (1.25 mg·g^-1 b.w.) daily from PND01 to PND05 (n = 24). Afterwards, in PND15, 12 animals were euthanized to determine the plasma and inflammatory profile and to assess muscle damage. In PND142, the remaining animals were euthanized, and samples for histological and biochemical analyses were obtained. Our results suggest that early exposure to MSG reduced growth, increased adiposity, and inducted hyperinsulinemia and a pro-inflammatory scenario. In adulthood, the following were observed: peripheral insulin resistance, increased fibrosis, oxidative distress, and a reduction in muscle mass, oxidative capacity, and neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty restoring in the muscle profile is related to the metabolic damage established early on.

Evidence of the Autophagic Process during the Fish Immune Response of Skeletal Muscle Cells against Piscirickettsia salmonis

Autophagy is a fundamental cellular process implicated in the health of the cell, acting as a cytoplasmatic quality control machinery by self-eating unfunctional organelles and protein aggregates. In mammals, autophagy can participate in the clearance of intracellular pathogens from the cell, and the activity of the toll-like receptors mediates its activation. However, in fish, the modulation of autophagy by these receptors in the muscle is unknown. This study describes and characterizes autophagic modulation during the immune response of fish muscle cells after a challenge with intracellular pathogen Piscirickettsia salmonis. For this, primary cultures of muscle cells were challenged with P. salmonis, and the expressions of immune markers il-1β, tnfα, il-8, hepcidin, tlr3, tlr9, mhc-I and mhc-II were analyzed through RT-qPCR. The expressions of several genes involved in autophagy (becn1, atg9, atg5, atg12, lc3, gabarap and atg4) were also evaluated with RT-qPCR to understand the autophagic modulation during an immune response. In addition, LC3-II protein content was measured via Western blot. The challenge of trout muscle cells with P. salmonis triggered a concomitant immune response to the activation of the autophagic process, suggesting a close relationship between these two processes.

Resistance Training Improves Sleep and Anti-Inflammatory Parameters in Sarcopenic Older Adults: A Randomized Controlled Trial

Sleep and exercise have an important role in the development of several inflammation-related diseases, including sarcopenia. Objective: To investigate the effects of 12 weeks of resistance exercise training on sleep and inflammatory status in sarcopenic patients. Methods: A randomized controlled trial comparing resistance exercise training (RET) with a control (CTL) was conducted. Outcomes were obtained by physical tests, polysomnography, questionnaires, isokinetic/isometric dynamometry tests, and biochemical analysis. Results: Time to sleep onset (sleep latency) was reduced in the RET group compared to the CTL group (16.09 ± 15.21 vs. 29.98 ± 16.09 min; p = 0.04) after the intervention. The percentage of slow-wave sleep (N3 sleep) was increased in the RET group (0.70%, CI: 7.27−16.16 vs. −4.90%, CI: 7.06−16.70; p = 0.04) in an intention to treat analysis. Apnea/hour was reduced in the RET group (16.82 ± 14.11 vs. 7.37 ± 7.55; p = 0.001) and subjective sleep quality was improved compared to the CTL (−1.50; CI: 2.76−6.14 vs. 0.00; CI: 1.67−3.84 p = 0.02) in an intention-to-treat analysis. Levels of interleukin-10 (IL-10) (2.13 ± 0.80 vs. 2.51 ± 0.99; p < 0.03) and interleukin-1 receptor antagonist (IL-1ra) (0.99 ± 0.10 vs. 0.99 ± 0.10 ng/mL; p < 0.04; delta variation) were increased in the RET group. Conclusions: RET improves sleep parameters linked to muscle performance, possibly due to an increase in anti-inflammatory markers in older sarcopenic patients.

In silico investigation of molecular networks linking gastrointestinal diseases, malnutrition, and sarcopenia

Malnutrition (MN) is a common primary or secondary complication in gastrointestinal diseases. The patient’s nutritional status also influences muscle mass and function, which can be impaired up to the degree of sarcopenia. The molecular interactions in diseases leading to sarcopenia are complex and multifaceted, affecting muscle physiology, the intestine (nutrition), and the liver at different levels. Although extensive knowledge of individual molecular factors is available, their regulatory interplay is not yet fully understood. A comprehensive overall picture of pathological mechanisms and resulting phenotypes is lacking. In silico approaches that convert existing knowledge into computationally readable formats can help unravel mechanisms, underlying such complex molecular processes. From public literature, we manually compiled experimental evidence for molecular interactions involved in the development of sarcopenia into a knowledge base, referred to as the Sarcopenia Map. We integrated two diseases, namely liver cirrhosis (LC), and intestinal dysfunction, by considering their effects on nutrition and blood secretome. We demonstrate the performance of our model by successfully simulating the impact of changing dietary frequency, glycogen storage capacity, and disease severity on the carbohydrate and muscle systems. We present the Sarcopenia Map as a publicly available, open-source, and interactive online resource, that links gastrointestinal diseases, MN, and sarcopenia. The map provides tools that allow users to explore the information on the map and perform in silico simulations.

Role of sarcopenia risk in predicting COVID-19 severity and length of hospital stay in older adults: a prospective cohort study

Sarcopenia is more common in the elderly and causes adverse outcomes with increased morbidity and mortality. This prospective cohort study assessed the association of sarcopenia risk with the severity of COVID-19 at the time of admission and during hospitalisation and the length of hospital stay. Two hundred patients (aged ≥ 60 years) who were hospitalised for COVID-19 were enrolled using consecutive sampling between 29 December 2020 and 20 May 2021. The sarcopenia score of the patients was assessed using the Strength, Assistance in walking, Rising from a chair, Climbing stairs, and Falls questionnaire. The severity of COVID-19 was determined using the modified National Early Warning Score (m-NEWS) system for 2019 n-CoV-infected patients at admission (T1), day three (T2) and at discharge (T3). Data were analysed using SPSS, version 22 and STATA, version 14. Of the 165 patients included, thirty four (20·6 %) were at risk of sarcopenia. The length of hospital stay was slightly longer in patients with sarcopenia risk, but the difference was not significant (P = 0·600). The adjusted OR of respiratory rate (RR) > 20 /min at T1 for the sarcopenia risk group was 6·7-times higher than that for the non-sarcopenic group (P = 0·002). According to generalised estimating equations, after adjusting for confounding factors, the m-NEWS score was 5·6 units higher in patients at risk of sarcopenia (P < 0·001). Sarcopenia risk could exacerbate COVID-19 severity and increase RR at admission, as well as the need for oxygen therapy at discharge.

Skeletal muscle oxidative stress and inflammation in aging: Focus on antioxidant and anti-inflammatory therapy

With aging, the progressive loss of skeletal muscle will have negative effect on multiple physiological parameters, such as exercise, respiration, thermoregulation, and metabolic homeostasis. Accumulating evidence reveals that oxidative stress and inflammation are the main pathological characteristics of skeletal muscle during aging. Here, we focus on aging-related sarcopenia, summarize the relationship between aging and sarcopenia, and elaborate on aging-mediated oxidative stress and oxidative damage in skeletal muscle and its critical role in the occurrence and development of sarcopenia. In addition, we discuss the production of excessive reactive oxygen species in aging skeletal muscle, which reduces the ability of skeletal muscle satellite cells to participate in muscle regeneration, and analyze the potential molecular mechanism of ROS-mediated mitochondrial dysfunction in aging skeletal muscle. Furthermore, we have also paid extensive attention to the possibility and potential regulatory pathways of skeletal muscle aging and oxidative stress mediate inflammation. Finally, in response to the abnormal activity of oxidative stress and inflammation during aging, we summarize several potential antioxidant and anti-inflammatory strategies for the treatment of sarcopenia, which may provide beneficial help for improving sarcopenia during aging.

Physiological Systems in Promoting Frailty

Frailty is a complex syndrome affecting a growing sector of the global population as medical developments have advanced human mortality rates across the world. Our current understanding of frailty is derived from studies conducted in the laboratory as well as the clinic, which have generated largely phenotypic information. Far fewer studies have uncovered biological underpinnings driving the onset and progression of frailty, but the stage is set to advance the field with preclinical and clinical assessment tools, multiomics approaches together with physiological and biochemical methodologies. In this article, we provide comprehensive coverage of topics regarding frailty assessment, preclinical models, interventions, and challenges as well as clinical frameworks and prevalence. We also identify central biological mechanisms that may be at play including mitochondrial dysfunction, epigenetic alterations, and oxidative stress that in turn, affect metabolism, stress responses, and endocrine and neuromuscular systems. We review the role of metabolic syndrome, insulin resistance and visceral obesity, focusing on glucose homeostasis, adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and nicotinamide adenine dinucleotide (NAD+ ) as critical players influencing the age-related loss of health. We further focus on how immunometabolic dysfunction associates with oxidative stress in promoting sarcopenia, a key contributor to slowness, weakness, and fatigue. We explore the biological mechanisms involved in stem cell exhaustion that affect regeneration and may contribute to the frailty-associated decline in resilience and adaptation to stress. Together, an overview of the interplay of aging biology with genetic, lifestyle, and environmental factors that contribute to frailty, as well as potential therapeutic targets to lower risk and slow the progression of ongoing disease is covered. © 2022 American Physiological Society. Compr Physiol 12:1-46, 2022.

Sarcopenia in Non-Dialysis Chronic Kidney Disease Patients: Prevalence and Associated Factors

Background

Sarcopenia is related to morbidity and mortality in non-dialysis Chronic Kidney Disease (ND-CKD) patients; however, the pathophysiology of sarcopenia remains unclear. The study aimed to assess the prevalence and factors associated with sarcopenia in ND-CKD individuals.

Methods

We cross-sectionally evaluated 139 prevalent ND-CKD patients attending our outpatient clinic at Hospital das Clínicas of the Federal University of Pernambuco, between April and October 2019. Patients older than 18 years old and at G3-G5 CKD stages were included. Hand grip strength, Muscle Mass appendicular Index, and Gait Speed (GS) were defined by the standards of the European Working Group on Sarcopenia in Older People 2 guideline.

Results

Sarcopenia prevalence was 20.9% and severe sarcopenia 2.9%. Sarcopenic were mostly found in elderly ones (64.8 ± 13.5 years vs. 54.9 ± 12.8 years, p < 0.001), revealing lower body mass index [26.1 (6.8) vs. 28.6 (6.2), p = 0.023], lower phase angle (PhA) [4.50 (1.10) vs. 5.60 (1.20), p < 0.001] and lower GS [1.00 (0.50) vs. 1.40 (0.4), p < 0.001]. They also presented lower serum creatinine levels [2.40 (1.50) vs. 3.0 (1.8), p = 0.032], lower Albumin-to-Creatinine Ratio [72.60 (1008.30) vs. 342.30 (1172.1), p = 0.039] and Hemoglobin levels [11.45 (1.8) vs. 12.60 (2.40), p = 0.003], and higher levels of C-reactive protein [0.2 (0.80) vs. 0.03 (0.3), p = 0.045] compared to non-sarcopenic. Under Poisson Multivariate Model, PhA [Relative precision (RP): 0.364, Confidence Interval (CI) (95%):0.259-0.511, p < 0.001], Interleukin six (IL-6) [RP: 1.006, CI (95%):1.001-1.01, p = 0.02] and serum creatinine levels [RP: 0.788, CI (95%): 0.641-0.969, p = 0.024] were associated with sarcopenia.

Conclusions

Sarcopenia predominance was identified in our ND-CKD population, and was associated with lower PhA values, higher IL-6 levels, and lower serum creatinine levels.

Plasma omega-3 is not associated with appendicular muscle mass index in young and middle-aged individuals: Results from NHANES 2011-2012

The aim of this study was to evaluate the association between plasma omega-3 (ω-3) and appendicular muscle mass index (AMMI) in young and middle-aged individuals; and also to evaluate whether these associations are sex-specific. A cross-sectional study was performed evaluating 1037 individuals aged 20 to 59 years from a sub-sample of the National Health and Nutrition Examination Survey (NHANES) 2011-2012. Plasma ω-3 was evaluated by gas chromatography-mass spectrometry and lean mass was assessed by dual-energy x-ray absorptiometry (DXA). Total plasma ω-3, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA) were not associated with AMMI in total sample, men and women after adjustments for confounders. Plasma ω-3 and its subtypes were not associated with AMMI in a subanalysis evaluating young (20 to 44 y) and middle-aged (45 to 59 y) individuals separately. In conclusion, plasma ω-3 fatty acids are not associated with AMMI in young and middle-aged individuals regardless of sex.

Comparison of quadriceps muscle size and quality in adults with cystic fibrosis with different severities of cystic fibrosis transmembrane conductance regulator protein dysfunction

Background

Cystic fibrosis (CF) is characterized by CF transmembrane conductance regulator (CFTR) dysfunction. CFTR protein is expressed in human skeletal muscle; however, its impact on skeletal muscle is unknown. The objectives of this study were to compare quadriceps muscle size and quality between adults with various severities of CFTR protein dysfunction.

Methods

We conducted a prospective, cross-sectional study comparing 34 adults with severe versus 18 with mild CFTR protein dysfunction, recruited from a specialized CF centre. Ultrasound images of rectus femoris cross-sectional area (RF-CSA) and quadriceps layer thickness for muscle size, and rectus femoris echogenicity (RF-ECHO) (muscle quality) were obtained. Multivariable linear regression models were developed using purposeful selection technique.

Results

People with severe CFTR protein dysfunction had larger RF-CSA by 3.22 cm², 95% CI (1.03, 5.41) cm², p=.0049], after adjusting for oral corticosteroid use and Pseudomonas aeruginosa colonization. However, a sensitivity analysis indicated that the result was influenced by the specific confounders being adjusted for in the model. We did not find any significant differences in quadriceps layer thickness or RF-ECHO between the two groups.

Conclusion

We found no differential impact of the extent of diminished CFTR protein activity on quadriceps muscle size or quality in our study cohort. Based on these findings, CFTR mutation status cannot be used differentiate leg muscle size or quality in people with CF.

Overview of sialylation status in human nervous and skeletal muscle tissues during aging

Sialic acids (Sias) are a large and heterogeneous family of electronegatively charged nine-carbon monosaccharides containing a carboxylic acid and are mostly found as terminal residues in glycans of glycoproteins and glycolipids such as gangliosides. They are linked to galactose or N-acetylgalactosamine via α2,3 or α2,6 linkage, or to other Sias via α2,8 or more rarely α2,9 linkage, resulting in mono, oligo and polymeric forms. Given their characteristics, Sias play a crucial role in a multitude of human tissue biological processes in physiological and pathological conditions, ranging from development and growth to adult life until aging. Here, we review the sialylation status in human adult life focusing on the nervous and skeletal muscle tissues, which both display significant structural and functional changes during aging, strongly impacting on the whole human body and, therefore, on the quality of life. In particular, this review highlights the fundamental roles played by different types of glycoconjugates Sias in several cellular biological processes in the nervous and skeletal muscle tissues during adult life, also discussing how changes in Sia content during aging may contribute to the physiological decline of physical and nervous functions and to the development of age-related degenerative pathologies. Based on our current knowledge, further in-depth investigations could help to develop novel prophylactic strategies and therapeutic approaches that, by maintaining and/or restoring the correct sialylation status in the nervous and skeletal muscle tissues, could contribute to aging slowing and the prevention of age-related pathologies.

Inflammation and sarcopenia: A focus on circulating inflammatory cytokines

Sarcopenia is an aged-related syndrome that is progressive and can be accelerated by other concomitant disease states. Sarcopenia, characterized by loss of skeletal muscle mass, reduced muscle strength, and/or reduced physical performance, is one of the main reasons for limitation of daily activities in the elderly. It is associated with an increased incidence of many adverse events, such as dysfunction, falls, weakness, hospitalization, disability and even death. Sarcopenia justifies one of the most widely accepted theories that low-grade chronic inflammation associated with aging, known as inflammatory aging, is important to the pathogenesis of many age-related diseases. Currently, the diagnosis of sarcopenia is based on a comprehensive assessment of three aspects: muscle mass, muscle strength and physical performance. The measurement of muscle mass is complicated, as the measurement of muscle strength and gait speed is easily affected by the physical conditions of the subjects. This makes the measurements inaccurate and prospective, and it is difficult to achieve continuous, purposeful monitoring. In addition, serum levels of inflammatory cytokines change as inflammatory states develop in the elderly population. This manuscript focuses on the correlation between serum inflammatory cytokines and sarcopenia in recent years, plus the possible underlying mechanisms.

Out of Control: The Role of the Ubiquitin Proteasome System in Skeletal Muscle during Inflammation

The majority of critically ill intensive care unit (ICU) patients with severe sepsis develop ICU-acquired weakness (ICUAW) characterized by loss of muscle mass, reduction in myofiber size and decreased muscle strength leading to persisting physical impairment. This phenotype results from a dysregulated protein homeostasis with increased protein degradation and decreased protein synthesis, eventually causing a decrease in muscle structural proteins. The ubiquitin proteasome system (UPS) is the predominant protein-degrading system in muscle that is activated during diverse muscle atrophy conditions, e.g., inflammation. The specificity of UPS-mediated protein degradation is assured by E3 ubiquitin ligases, such as atrogin-1 and MuRF1, which target structural and contractile proteins, proteins involved in energy metabolism and transcription factors for UPS-dependent degradation. Although the regulation of activity and function of E3 ubiquitin ligases in inflammation-induced muscle atrophy is well perceived, the contribution of the proteasome to muscle atrophy during inflammation is still elusive. During inflammation, a shift from standard- to immunoproteasome was described; however, to which extent this contributes to muscle wasting and whether this changes targeting of specific muscular proteins is not well described. This review summarizes the function of the main proinflammatory cytokines and acute phase response proteins and their signaling pathways in inflammation-induced muscle atrophy with a focus on UPS-mediated protein degradation in muscle during sepsis. The regulation and target-specificity of the main E3 ubiquitin ligases in muscle atrophy and their mode of action on myofibrillar proteins will be reported. The function of the standard- and immunoproteasome in inflammation-induced muscle atrophy will be described and the effects of proteasome-inhibitors as treatment strategies will be discussed.

Role of Protein Arginine Methyltransferases and Inflammation in Muscle Pathophysiology

Arginine methylation mediated by protein arginine methyltransferases (PRMTs) is a post-translational modification of both histone and non-histone substrates related to diverse biological processes. PRMTs appear to be critical regulators in skeletal muscle physiology, including regeneration, metabolic homeostasis, and plasticity. Chronic inflammation is commonly associated with the decline of skeletal muscle mass and strength related to aging or chronic diseases, defined as sarcopenia. In turn, declined skeletal muscle mass and strength can exacerbate chronic inflammation. Thus, understanding the molecular regulatory pathway underlying the crosstalk between skeletal muscle function and inflammation might be essential for the intervention of muscle pathophysiology. In this review, we will address the current knowledge on the role of PRMTs in skeletal muscle physiology and pathophysiology with a specific emphasis on its relationship with inflammation.

Evaluation of body composition using computed tomography in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND/AIMS

Measures of body composition, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and skeletal muscle area (SMA), are considered important prognostic factors in chronic diseases. The association of these measures with auto-inflammatory disorders, such as anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV), remains unclear. We investigated the clinical significance of VAT, SAT, and SMA in patients with AAV.

METHODS

Patients with AAV subjected to chest computed tomography (CT), abdominal CT, or positron emission tomography-CT on diagnosis of AAV were evaluated. Quantitative assessment of VAT, SAT, and SMA was performed at the third lumbar vertebral level and computed by summing the pixel attenuation for tissue-specific Hounsfield units in the corresponding region. Associations of VAT, SAT, and SMA with clinical and laboratory data and clinical outcome measures were evaluated.

RESULTS

Of the 117 patients, 61 (52.1%) were classified as having microscopic polyangiitis, 28 (23.9%) as granulomatosis with polyangiitis, and 28 (23.9%) as eosinophilic granulomatosis with polyangiitis. VAT significantly correlated with age, weight, body mass index (BMI), and Birmingham Vasculitis Activity Score, whereas SAT correlated with weight, BMI, and creatinine levels. A significant association was found between SMA and age, height, weight, BMI, and the Five-Factor Score. Cox proportional hazards analysis showed that creatinine levels (odds ratio [OR], 1.346; 95% confidence interval [CI], 1.034 to 1.753; p = 0.027) and high VAT (OR, 7.137; 95% CI, 1.343-37.946; p = 0.021) were independently associated with all-cause mortality during follow-up.

CONCLUSION

Evaluation of VAT using CT is useful for estimating disease activity and all-cause mortality in patients with AAV.

The controversy on the beneficial effect of phytoestrogens in diabetic treatment in postmenopausal women

Phytoestrogens have been identified as a natural, plant-based alternative to synthetically derived estrogens, to supplement the absence of endogenous estrogens in post-menopausal women, and attenuate the progression of pathologies and side-effects associated with menopause. The increased availability of these plant's derived compounds as diet or nutritional supplements makes their ingestion and consumption easier and more accessible as compared to pharmacological alternatives. Further, phytoestrogen intake has shown beneficial effects as estrogens alternatives in attenuating severe complications in diseases such as type 2 diabetes, metabolic syndrome, NAFLD, and obesity. However, in many cases phytoestrogen effectiveness remains largely circumstantial or just anecdotal as significant uncertainties on the relative abundance of different phytoestrogens in a given diet, the need for conversion to an active principle through the gut microbiome, the possibility of an effect threshold, the synergistic effect of different phytoestrogens possible due to different modality of actions still persist. The present article aims at highlighting the main issues and concerns plaguing the field as well as some of the possible causes of inconsistencies observed in the various nutritional and clinical studies attempted so far.

Association of adipocytokine IL-1A and IL-6 genes with intramuscular fat content and fatty acid composition in pigs

Several adipocytokines are involved in inflammatory and immune responses as well as regulated fat deposition and lipid metabolism in mammals. This study aimed to verify the polymorphisms of the porcine interleukin 1A (IL-1A) and interleukin 6 (IL-6) genes and to assess their association with intramuscular fat (IMF) content and fatty acid (FA) composition in commercial crossbred pigs. Two single nucleotide polymorphisms (SNPs) of the porcine IL-1A g.43722547A>G and IL-6 g.91508173C>T loci were found to be segregating in these crossbred pigs. Furthermore, the porcine IL-1A g.43722547A>G polymorphism was found to be significantly associated with myristic, palmitic, palmitoleic, and eicosadienoic acid levels. Moreover, the porcine IL-6 g.91508173C>T polymorphism was significantly associated with IMF content and homolinolenic acid levels. These results suggest that the polymorphisms of the porcine IL-1A and IL-6 genes correlated with lipid content and FA composition and confirmed the importance of the adipocytokine IL-1A and IL-6 genes as candidate genes for fatty acid composition in the muscles of pigs.

Basic Science of Frailty-Biological Mechanisms of Age-Related Sarcopenia

Aging is associated with loss of function across organ systems, contributing to systemic frailty. Loss of skeletal muscle mass and function, in particular, is a major source of frailty in older adults, severely impacting quality of life. Some loss of muscle mass and strength with aging is inevitable, and sarcopenia, the severe loss of muscle mass with aging, is common. Sarcopenia is determined in part by genetics but can be modified by lifestyle choices. The pathophysiologic underpinnings of sarcopenia are complex and multifactorial. In this review, the causes of sarcopenia are surveyed at the systems, cell, subcellular, and molecular levels with emphasis on the interplay between these various causes of this degenerative disease process.

Proteodynamics and aging of eukaryotic cells

All aspects of each protein existence in the eukaryotic cells, starting from the pre-translation events, through translation, multiple different post-translational modifications, functional life and eventual proteostatic removal after loss of functionality and changes in physico-chemical properties, can be collectively called the proteodynamics. With aging, passing of time as well as accumulating effects of exposures, interactions and wearing-off lead to problems at each of the above mentioned stages, eventually leading to general malfunction of the proteome. This work briefly reviews and summarizes current knowledge concerning this important topic.

The Acute Effects of 5 Fluorouracil on Skeletal Muscle Resident and Infiltrating Immune Cells in Mice

5 fluorouracil (5FU) has been a first-choice chemotherapy drug for several cancer types (e.g., colon, breast, head, and neck); however, its efficacy is diminished by patient acquired resistance and pervasive side effects. Leukopenia is a hallmark of 5FU; however, the impact of 5FU-induced leukopenia on healthy tissue is only becoming unearthed. Recently, skeletal muscle has been shown to be impacted by 5FU in clinical and preclinical settings and weakness and fatigue remain among the most consistent complaints in cancer patients undergoing chemotherapy. Monocytes, or more specifically macrophages, are the predominate immune cell in skeletal muscle which regulate turnover and homeostasis through removal of damaged or old materials as well as coordinate skeletal muscle repair and remodeling. Whether 5FU-induced leukopenia extends beyond circulation to impact resident and infiltrating skeletal muscle immune cells has not been examined. The purpose of the study was to examine the acute effects of 5FU on resident and infiltrating skeletal muscle monocytes and inflammatory mediators. Male C57BL/6 mice were given a physiologically translatable dose (35 mg/kg) of 5FU, or PBS, i.p. once daily for 5 days to recapitulate 1 dosing cycle. Our results demonstrate that 5FU reduced circulating leukocytes, erythrocytes, and thrombocytes while inducing significant body weight loss (>5%). Flow cytometry analysis of the skeletal muscle indicated a reduction in total CD45+ immune cells with a corresponding decrease in total CD45+CD11b+ monocytes. There was a strong relationship between circulating leukocytes and skeletal muscle CD45+ immune cells. Skeletal muscle Ly6cHigh activated monocytes and M1-like macrophages were reduced with 5FU treatment while total M2-like CD206+CD11c- macrophages were unchanged. Interestingly, 5FU reduced bone marrow CD45+ immune cells and CD45+CD11b+ monocytes. Our results demonstrate that 5FU induced body weight loss and decreased skeletal muscle CD45+ immune cells in association with a reduction in infiltrating Ly6cHigh monocytes. Interestingly, the loss of skeletal muscle immune cells occurred with bone marrow cell cycle arrest. Together our results highlight that skeletal muscle is sensitive to 5FU's off-target effects which disrupts both circulating and skeletal muscle immune cells.

Pharmacological blockade of TNFα prevents sarcopenia and prolongs survival in aging mice

Sarcopenia is a hallmark of aging. Inflammation due to increased generation of cytokines such as TNFα, IL-1β and IL-6 has been implicated in the pathogenesis of sarcopenia. In skeletal muscle of C57BL/6 mice from 12 until 28 months of age, we observed a progressive reduction of myofiber cross sectional area, loss of type II fibers and infiltration by inflammatory cells. Muscle strength decreased in parallel. Pharmacological TNFα blockade by weekly subcutaneous injection of Etanercept from 16 to 28 months of age prevented atrophy and loss of type II fibers, with significant improvements in muscle function and mice lifespan. The effects on leukocyte recruitment were limited. These results provide a proof of principle that endogenous TNFα is sufficient to cause sarcopenia and to reduce animal survival, and open a novel perspective on novel potential pharmacological treatment strategies based on TNFα blockade to prevent the noxious events associated with aging.

Protective role of mitoquinone against impaired mitochondrial homeostasis in metabolic syndrome

Mitochondria control various processes in cellular metabolic homeostasis, such as adenosine triphosphate production, generation and clearance of reactive oxygen species, control of intracellular Ca²⁺ and apoptosis, and are thus a critical therapeutic target for metabolic syndrome (MetS). The mitochondrial targeted antioxidant mitoquinone (MitoQ) reduces mitochondrial oxidative stress, prevents impaired mitochondrial dynamics, and increases mitochondrial turnover by promoting autophagy (mitophagy) and mitochondrial biogenesis, which ultimately contribute to the attenuation of MetS conditions, including obesity, insulin resistance, hypertension and cardiovascular disease. The regulatory effect of MitoQ on mitochondrial homeostasis is mediated through AMPK and its downstream signaling pathways, including MTOR, SIRT1, Nrf2 and NF-κB. However, there are few reviews focusing on the critical role of MitoQ as a therapeutic agent in the treatment of MetS. The purpose of this review is to summarize the mitochondrial role in the pathogenesis of MetS, especially in obesity and type 2 diabetes, and discuss the effect and underlying mechanism of MitoQ on mitochondrial homeostasis in MetS.

An open-label, single-center pilot study to test the effects of an amino acid mixture in older patients admitted to internal medicine wards

OBJECTIVE

Older patients are frequently subjected to prolonged hospitalization and extended bed rest, with a negative effect on physical activity and caloric intake. This results in a consistent loss of muscle mass and function, which is associated with functional decline and high mortality. The aim of this study was to investigate the effect of 1 wk of oral amino acid (AA) supplementation in older patients subjected to low mobility during hospitalization.

METHODS

Hospitalized older patients (69-87) were included in the control group (n = 50) or were administered 25 g of AA mixture (n = 44) twice daily throughout 7 d of low mobility. We collected data related to length of stay as primary outcome measure. In-hospital mortality, 90-d postdischarge mortality, 90-d postdischarge rehospitalization, and falls also were considered. Moreover, variations of anthropometric measures, body composition and muscle architecture/strength, circulating interleukins, and oxidative stress markers between the beginning and the end of the supplementation period were analyzed as secondary outcomes.

RESULTS

Similar values were reported between the two groups regarding age (76.6 ± 6.8 versus 79 ± 7.2 y old), body weight (61.5 ± 14.3 versus 62.1 ± 16.1 kg), and body mass index (28.7 ± 4.15 versus 28.1 ± 3.62 kg/m²). Although no difference in terms of in-hospital, 90-d postdischarge, or overall mortality rate was observed between the two groups, a reduction in length of stay, 90-d postdischarge hospitalization, and falls was observed in the AA supplementation group rather than in controls. Furthermore, the AA mixture limited muscle architecture/strength impairment and circulating oxidative stress, which occurred during hospitalization-related bed rest. The latter data was associated with increased circulating levels of anti-inflammatory cytokines interleukin-4 and -10.

CONCLUSIONS

These results suggest that the AA mixture limits several alterations associated with low mobility in older hospitalized patients, such as length of stay, 90-d postdischarge hospitalization, and falls, preventing the loss of muscle function, as well as the increase of circulating interleukins and oxidative stress markers.

Transcriptomic response of rainbow trout (Oncorhynchus mykiss) skeletal muscle to Flavobacterium psychrophilum

Flavobacterium psychrophilum is the etiologic agent of rainbow trout fry syndrome (RTFS). This pathogen infects a wide variety of salmonid species during freshwater stages, causing significant losses in the aquaculture industry. Rainbow trout (Oncorhynchus mykiss) infected with F. psychrophilum, presents as the main external clinical sign ulcerative lesions and necrotic myositis in skeletal muscle. We previously reported the in vitro cytotoxic activity of F. psychrophilum on rainbow trout myoblast, however little is known about the molecular mechanisms underlying the in vivo pathogenesis in skeletal muscle. In this study, we examined the transcriptomic profiles of skeletal muscle tissue of rainbow trout intraperitoneally challenged with low infection dose of F. psychrophilum. Using high-throughput RNA-seq, we found that 233 transcripts were up-regulated, mostly associated to ubiquitin mediated proteolysis and apoptosis. Conversely, 189 transcripts were down-regulated, associated to skeletal muscle contraction. This molecular signature was consistent with creatine kinase activity in plasma and oxidative damage in skeletal muscle. Moreover, the increased caspase activity suggests as a whole skeletal muscle atrophy induced by F. psychrophilum. This study offers an integrative analysis of the skeletal muscle response to F. psychrophilum infection and reveals unknown aspects of its pathogenesis in rainbow trout.