Mediators and Patterns of Muscle Loss in Chronic Systemic Inflammation

Identification of the molecular link: STAT3 is a shared key gene linking postmenopausal osteoporosis and sarcopenia

Aims

This study explored the shared genetic traits and molecular interactions between postmenopausal osteoporosis (POMP) and sarcopenia, both of which substantially degrade elderly health and quality of life. We hypothesized that these motor system diseases overlap in pathophysiology and regulatory mechanisms.

Methods

We analyzed microarray data from the Gene Expression Omnibus (GEO) database using weighted gene co-expression network analysis (WGCNA), machine learning, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to identify common genetic factors between POMP and sarcopenia. Further validation was done via differential gene expression in a new cohort. Single-cell analysis identified high expression cell subsets, with mononuclear macrophages in osteoporosis and muscle stem cells in sarcopenia, among others. A competitive endogenous RNA network suggested regulatory elements for these genes.

Results

Signal transducer and activator of transcription 3 (STAT3) was notably expressed in both conditions. Single-cell analysis pinpointed specific cells with high STAT3 expression, and microRNA (miRNA)-125a-5p emerged as a potential regulator. Experiments confirmed the crucial role of STAT3 in osteoclast differentiation and muscle proliferation.

Conclusion

STAT3 has emerged as a key gene in both POMP and sarcopenia. This insight positions STAT3 as a potential common therapeutic target, possibly improving management strategies for these age-related diseases.

Ubiquitination Insight from Spinal Muscular Atrophy-From Pathogenesis to Therapy: A Muscle Perspective

Spinal muscular atrophy (SMA) is one of the most frequent causes of death in childhood. The disease's molecular basis is deletion or mutations in the SMN1 gene, which produces reduced survival motor neuron protein (SMN) levels. As a result, there is spinal motor neuron degeneration and a large increase in muscle atrophy, in which the ubiquitin-proteasome system (UPS) plays a significant role. In humans, a paralogue of SMN1, SMN2 encodes the truncated protein SMNΔ7. Structural differences between SMN and SMNΔ7 affect the interaction of the proteins with UPS and decrease the stability of the truncated protein. SMN loss affects the general ubiquitination process by lowering the levels of UBA1, one of the main enzymes in the ubiquitination process. We discuss how SMN loss affects both SMN stability and the general ubiquitination process, and how the proteins involved in ubiquitination could be used as future targets for SMA treatment.

Sarcopenia is a risk factor for post-transjugular intrahepatic portosystemic shunt hepatic encephalopathy and mortality: A systematic review and meta-analysis

BACKGROUND/AIMS

Transjugular intrahepatic portosystemic shunt (TIPS) is a commonly performed procedure in patients with liver cirrhosis to treat portal hypertension-related conditions, including variceal bleeding and refractory ascites. However, while the increased risk of hepatic encephalopathy (HE) after TIPS is important to consider when determining whether a patient is a good candidate for TIPS, currently there is no widely used method to predict the development of post-TIPS HE, although the model for end-stage liver disease (MELD) score is used to predict post-TIPS mortality. We conducted a systematic review and meta-analysis to evaluate sarcopenia as a risk factor for HE and mortality in patients undergoing TIPS.

METHODS

A comprehensive search strategy was used to identify reports of post-TIPS HE and mortality in sarcopenia vs. non-sarcopenia patients with liver cirrhosis who received TIPS in March 2023. Open Meta Analyst was used to compute the results.

RESULTS

Twelve studies with 2056 patients met inclusion criteria and were included in the final meta-analysis. Sarcopenia was associated with a significantly higher post-TIPS HE rate than non-sarcopenia (risk ratio [RR]: 1.68, 95% CI: 1.48-1.92, p < 0.00001, I2 = 65%), as well as a significantly higher post-TIPS mortality rate (RR: 1.73, 95% CI: 1.14-2.64, p < 0.00001, I2 = 87%).

CONCLUSION

Patients with sarcopenia have a significantly increased risk of post-TIPS HE and mortality. Presence of sarcopenia should be considered when weighing the risks and benefits of performing TIPS in patients with cirrhosis. Further studies are needed to determine the clinical utility of important risk factors such as sarcopenia on post-TIPS outcomes.

Comparative Efficacy of Various Exercise Therapies and Combined Treatments on Inflammatory Biomarkers and Morphological Measures of Skeletal Muscle among Older Adults with Knee Osteoarthritis: A Network Meta-Analysis

Osteoarthritis is associated with high risks of sarcopenia in older populations. Exercise interventions are promising treatments for musculoskeletal impairments in knee osteoarthritis (KOA). The purpose of this study was to identify the comparative effects of exercise monotherapy and its adjunct treatments on muscle volume and serum inflammation for older individuals with KOA. A literature search in the electronic databases was comprehensively performed from this study's inception until April 2024 to identify relevant randomized controlled trials (RCTs) that reported muscle morphology and inflammation outcomes after exercise. The included RCTs were analyzed through a frequentist network meta-analysis (NMA). The standard mean difference (SMD) with a 95% confidence interval was estimated for treatment effects on muscle morphology and inflammation biomarkers. The relative effects on each main outcome among all treatment arms were compared using surface under the cumulative ranking (SUCRA) scores. The certainty of evidence (CoE) was assessed by the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) ranking system. Probable moderators of the treatment efficacy were investigated by network meta-regression analysis. This study included 52 RCTs (4255 patients) for NMA. Among the 27 identified treatment arms, isokinetic training plus physical modality as well as low-load resistance training plus blood-flow restriction yielded the most optimal treatment for inflammation reduction (-1.89; SUCRA = 0.97; CoE = high) and muscle hypertrophy (SMD = 1.28; SUCRA = 0.94; CoE = high). The patient's age (β = -0.73), the intervention time (β = -0.45), and the follow-up duration (β = -0.47) were identified as significant determinants of treatment efficacy on muscle hypertrophy. Exercise therapy in combination with noninvasive agents exert additional effects on inflammation reduction and muscle hypertrophy compared to its corresponding monotherapies for the KOA population. However, such treatment efficacy is likely moderated by the patient's age, the intervention time, and the follow-up duration.

Association of dietary inflammatory indices with sarcopenia and all-cause mortality in COPD patients

Background

Sarcopenia frequently occurs as a comorbidity in individuals with COPD. However, research on the impact of Appendicular Skeletal Muscle Mass (ASM) on survival in COPD patients is scarce. Moreover, there is a lack of research on the association between dietary pro-inflammatory capacity and sarcopenia in COPD.

Methods

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) covering the years 1999 to 2006 and 2011 to 2018. We aimed to investigate the relationship between the Dietary Inflammatory Index (DII) and sarcopenia prevalence among adults diagnosed with COPD in the United States. Furthermore, we sought to explore the relationship between sarcopenia, ASMI, and all-cause mortality. The study included a total of 1,429 eligible adult participants, divided into four groups based on quartiles of DII, with adjustments for sample weights. Methodologically, we used multivariable logistic regression analyses and to examine the association between DII and sarcopenia. Additionally, we used restricted cubic spline (RCS) tests to evaluate potential non-linear relationships. To assess the effect of sarcopenia on overall all-cause mortality, we used Kaplan-Meier models and Cox proportional hazards models. Moreover, we used RCS analyses to investigate potential non-linear relationships between ASMI and all-cause mortality. Subgroup analyses were conducted to confirm the reliability of our study findings.

Results

In our COPD participant cohort, individuals with higher DII scores were more likely to be female, unmarried, have lower educational attainment, and show lower ASMI. Using multivariable logistic regression models, we found a positive association between the highest quartile of DII levels and sarcopenia incidence [Odds Ratio (OR) 2.37; 95% Confidence Interval (CI) 1.26-4.48; p = 0.01]. However, analysis of RCS curves did not show a non-linear relationship between DII and sarcopenia. Throughout the entire follow-up period, a total of 367 deaths occurred among all COPD patients. Kaplan-Meier survival curves showed a significantly higher all-cause mortality rate among individuals with concurrent sarcopenia (p < 0.0001). Cox proportional hazards model analysis showed a 44% higher risk of all-cause mortality among COPD patients with sarcopenia compared to those without sarcopenia [Hazard Ratio (HR): 1.44; 95% CI 1.05-1.99; p < 0.05]. Additionally, our final RCS analyses revealed a significant non-linear association between ASMI levels and all-cause mortality among COPD patients, with a turning point identified at 8.32 kg/m2. Participants with ASMI levels above this inflection point had a 42% lower risk of all-cause mortality compared to those with ASMI levels below it (HR 0.58; 95% CI 0.48-0.7).

Conclusion

We observed a significant association between concurrent sarcopenia and an increased risk of all-cause mortality in COPD patients within the United States. Moreover, ASMI demonstrated a non-linear association with all-cause mortality, with a critical threshold identified at 8.32 kg/m2. Our findings also revealed an association between DII and the presence of sarcopenia. Consequently, further investigations are warranted to explore the feasibility of dietary DII adjustments as a means to mitigate muscle wasting and enhance the prognosis of COPD.

Non-Pharmacological Strategies for Managing Sarcopenia in Chronic Diseases

This article focuses on a range of non-pharmacological strategies for managing sarcopenia in chronic diseases, including exercise, dietary supplements, traditional Chinese exercise, intestinal microecology, and rehabilitation therapies for individuals with limited limb movement. By analyzing multiple studies, the article aims to summarize the available evidence to manage sarcopenia in individuals with chronic diseases. The results strongly emphasize the role of resistance training in addressing chronic diseases and secondary sarcopenia. Maintaining the appropriate frequency and intensity of resistance training can help prevent muscle atrophy and effectively reduce inflammation. Although aerobic exercise has limited ability to improve skeletal muscle mass, it does have some positive effects on physical function. Building upon this, the article explores the potential benefits of combined training approaches, highlighting their helpfulness for overall quality of life. Additionally, the article also highlights the importance of dietary supplements in combating muscle atrophy in chronic diseases. It focuses on the importance of protein intake, supplements rich in essential amino acids and omega-3, as well as sufficient vitamin D to prevent muscle atrophy. Combining exercise with dietary supplements appears to be an effective strategy for preventing sarcopenia, although the optimal dosage and type of supplement remain unclear. Furthermore, the article explores the potential benefits of intestinal microecology in sarcopenia. Probiotics, prebiotics, and bacterial products are suggested as new treatment options for sarcopenia. Additionally, emerging therapies such as whole body vibration training, blood flow restriction, and electrical stimulation show promise in treating sarcopenia with limited limb movement. Overall, this article provides valuable insights into non-pharmacological strategies for managing sarcopenia in individuals with chronic diseases. It emphasizes the importance of a holistic and integrated approach that incorporates exercise, nutrition, and multidisciplinary interventions, which have the potential to promote health in the elderly population. Future research should prioritize high-quality randomized controlled trials and utilize wearable devices, smartphone applications, and other advanced surveillance methods to investigate the most effective intervention strategies for sarcopenia associated with different chronic diseases.

The prevalence of sarcopenia in spondyloarthritis patients: a meta-analysis

BACKGROUND

Spondyloarthritis (SpA) is a chronic inflammatory disorder that affects sacroiliac joints and spine, resulting in substantial disability. Sarcopenia, characterized by the loss of muscle mass and function, is a prevalent comorbidity in various chronic diseases. However, the exact prevalence of sarcopenia in SpA patients remains uncertain. The objective of this study is to conduct a systematic review and meta-analysis of the available literature to determine the prevalence of sarcopenia in SpA.

METHODS

A comprehensive search was conducted in EMBASE, MEDLINE, WEB OF SCIENCE, and COCHRANE databases to identify relevant studies published up to 2023. Studies investigating the prevalence of sarcopenia in SpA patients were included. Data on study characteristics, participant demographics, diagnostic criteria for sarcopenia, and prevalence rates were extracted. Meta-analysis was performed using a random-effects model to estimate the overall prevalence of sarcopenia in SpA patients.

RESULTS

A total of 16 studies that met the inclusion criteria were included in the systematic review. These studies encompassed a combined sample size of 999 patients with SpA. The meta-analysis findings revealed that the overall prevalence of sarcopenia in SpA patients was 25.0% (95% confidence interval: 0.127 to 0.352). Furthermore, the prevalence of presarcopenia and severe sarcopenia was found to be 21.0% and 8.7%, respectively. Subgroup analysis was conducted to examine different diagnostic criteria, subtypes, and sex of SpA in relation to sarcopenia.

CONCLUSION

This systematic review and meta-analysis provide a comprehensive overview of the prevalence of sarcopenia in SpA patients. The findings suggest a high prevalence of sarcopenia in SpA patients, emphasizing the need for targeted interventions to prevent and manage sarcopenia. And further research is needed to explore the underlying mechanisms and potential therapeutic strategies for sarcopenia in SpA.

Sarcopenia and Neuroendocrine Neoplasms

PURPOSE OF THE REVIEW

To summarise the current literature regarding the presence of sarcopenia in patients with neuroendocrine neoplasms (NENs). These are uncommon cancers separated into well-differentiated neuroendocrine tumours (NETs) and poorly differentiated neuroendocrine carcinoma (NECs). For the diagnosis of sarcopenia, there needs to be low muscle strength and low muscle quantity/quality.

RECENT FINDINGS

Five studies exist describing either low muscle strength or low muscle quantity in patients with NETs. The studies used different techniques to analyse muscle strength and muscle quantity, included heterogeneous populations, and performed the analysis at different time points following the diagnosis of the NET. Only 2 studies regarding patients with NECs could be found, both included mainly patients with a mixed adenoneuroendocrine carcinoma (MiNEN) and are, therefore, difficult to interpret for patients with a NEC. The main findings of this review are to describe the presence of sarcopenia in patients with NENs. However, results should be interpreted with caution, and future research should focus on the correct technique, homogenous population and same time point.

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.

A model based on adipose and muscle-related indicators evaluated by CT images for predicting microvascular invasion in HCC patients

BACKGROUND AND AIM

The presence of microvascular invasion (MVI) will impair the surgical outcome of hepatocellular carcinoma (HCC). Adipose and muscle tissues have been confirmed to be associated with the prognosis of HCC. We aimed to develop and validate a nomogram based on adipose and muscle related-variables for preoperative prediction of MVI in HCC.

METHODS

One hundred fifty-eight HCC patients from institution A (training cohort) and 53 HCC patients from institution B (validation cohort) were included, all of whom underwent preoperative CT scan and curative resection with confirmed pathological diagnoses. Least absolute shrinkage and selection operator (LASSO) logistic regression was applied to data dimensionality reduction and screening. Nomogram was constructed based on the independent variables, and evaluated by external validation, calibration curve, receiver operating characteristic (ROC) curve and decision curve analysis (DCA).

RESULTS

Histopathologically identified MVI was found in 101 of 211 patients (47.9%). The preoperative imaging and clinical variables associated with MVI were visceral adipose tissue (VAT) density, intramuscular adipose tissue index (IMATI), skeletal muscle (SM) area, age, tumor size and cirrhosis. Incorporating these 6 factors, the nomogram achieved good concordance index of 0.79 (95%CI: 0.72-0.86) and 0.75 (95%CI: 0.62-0.89) in training and validation cohorts, respectively. In addition, calibration curve exhibited good consistency between predicted and actual MVI probabilities. ROC curve and DCA of the nomogram showed superior performance than that of models only depended on clinical or imaging variables. Based on the nomogram score, patients were divided into high (> 273.8) and low (< = 273.8) risk of MVI presence groups. For patients with high MVI risk, wide-margin resection or anatomical resection could significantly improve the 2-year recurrence free survival.

CONCLUSION

By combining 6 preoperative independently predictive factors of MVI, a nomogram was constructed. This model provides an optimal preoperative estimation of MVI risk in HCC patients, and may help to stratify high-risk individuals and optimize clinical decision making.

Association Between Autoimmune Diseases and Sarcopenia: A Two-Sample Mendelian Randomization Study

Purpose

Observational studies have reported that autoimmune diseases are closely related to sarcopenia, but the causalities of autoimmune diseases with sarcopenia have not been established. We conducted this Mendelian randomization (MR) study to reveal the causal associations of overall autoimmune disease and five common autoimmune diseases with sarcopenia-related traits.

Methods

The publicly available summary-level data of autoimmune diseases and three sarcopenia-related traits were used for analysis. The causal effects of autoimmune diseases on sarcopenia-related traits were first identified in discovery samples using the inverse-variance-weighted method as the primary method, and the robustness of results was examined by additional sensitivity analyses. Replication MR analyses were then conducted using replication samples of five autoimmune diseases. Finally, the possibility of reverse causation was assessed by reverse MR analyses.

Results

In both the discovery and replication samples, we identified potential causal effects of rheumatoid arthritis (RA) on appendicular lean mass (ALM) and low grip strength (OR = 0.979, 95% CI: 0.964-0.995 for ALM; OR = 1.042, 95% CI: 1.013-1.072 for low grip strength), but not on walking pace. We also found that inflammatory bowel disease (IBD) and type 1 diabetes (T1D) were only causally negatively associated with ALM in the discovery stage (OR = 0.986, 95% CI: 0.974-0.999 for IBD; OR = 0.987, 95% CI: 0.975-0.999 for T1D), whereas systemic lupus erythematosus, multiple sclerosis, and overall autoimmune disease were not associated with any of the three sarcopenia-related traits. Additionally, reverse MR analysis only found an association between walking pace and overall autoimmune disease, but this association did not remain in the weighted-median method.

Conclusion

This study demonstrates that RA is causally associated with low grip strength and reduced ALM, and that IBD and T1D may be causally negatively related to ALM.

Effects of Tofacitinib on Muscle Remodeling in Experimental Rheumatoid Sarcopenia

Sarcopenia is a frequent comorbidity of rheumatoid arthritis (RA). Clinical trials have shown that JAK inhibitors (JAKi) produce an asymptomatic increase in serum creatine kinase (CK) in RA, suggesting an impact on muscle. We evaluated the effect of JAKi in muscle remodeling in an experimental RA model. Antigen-induced arthritis (experimental RA, e-RA) was performed in 14 rabbits. Seven rabbits received tofacitinib (TOFA, orally 10 mg/kg/day). Animals were euthanized one day after the last ovalbumin injection, and muscles were prepared for histology, RT-PCR, and WB. C-reactive protein (CRP) and Myostatin (MSTN) serum concentration were determined by ELISA. Creatine and creatine kinase (CK) were analyzed. An increase in body weight as well as tibialis anterior cross-sectional area and diameter was observed in e-RA+TOFA vs. e-RA. e-RA decreased type II fibers and increased the myonuclei number, with all reverted by TOFA. TOFA did not modify CRP levels, neither did MSTN. TOFA significantly reduced IL-6, atrogin-1, and MuRF-1 compared with e-RA. e-RA+TOFA showed higher CK and lower creatine levels compared with e-RA. No differences in PAX-7 were found, while TOFA prevented the increase in MyoD1 in e-RA. Our model reflects the features of rheumatoid sarcopenia in RA. JAKi increased muscle mass through attenuating IL-6/JAK/STAT activation, decreasing atrogenes, and restoring muscle differentiation markers. These data together with an increase in CK support the role of CK as a valuable marker of muscle gain following JAKi treatment.

Possible relationship between the gut leaky syndrome and musculoskeletal injuries: the important role of gut microbiota as indirect modulator

This article aims to examine the evidence on the relationship between gut microbiota (GM), leaky gut syndrome and musculoskeletal injuries. Musculoskeletal injuries can significantly impair athletic performance, overall health, and quality of life. Emerging evidence suggests that the state of the gut microbiota and the functional intestinal permeability may contribute to injury recovery. Since 2007, a growing field of research has supported the idea that GM exerts an essential role maintaining intestinal homeostasis and organic and systemic health. Leaky gut syndrome is an acquired condition where the intestinal permeability is impaired, and different bacteria and/or toxins enter in the bloodstream, thereby promoting systemic endotoxemia and chronic low-grade inflammation. This systemic condition could indirectly contribute to increased local musculoskeletal inflammation and chronificate injuries and pain, thereby reducing recovery-time and limiting sport performance. Different strategies, including a healthy diet and the intake of pre/probiotics, may contribute to improving and/or restoring gut health, thereby modulating both systemically as local inflammation and pain. Here, we sought to identify critical factors and potential strategies that could positively improve gut microbiota and intestinal health, and reduce the risk of musculoskeletal injuries and its recovery-time and pain. In conclusion, recent evidences indicate that improving gut health has indirect consequences on the musculoskeletal tissue homeostasis and recovery through the direct modulation of systemic inflammation, the immune response and the nociceptive pain.

Post-translational regulation of muscle growth, muscle aging and sarcopenia

Skeletal muscle makes up 30-40% of the total body mass. It is of great significance in maintaining digestion, inhaling and exhaling, sustaining body posture, exercising, protecting joints and many other aspects. Moreover, muscle is also an important metabolic organ that helps to maintain the balance of sugar and fat. Defective skeletal muscle function not only limits the daily activities of the elderly but also increases the risk of disability, hospitalization and death, placing a huge burden on society and the healthcare system. Sarcopenia is a progressive decline in muscle mass, muscle strength and muscle function with age caused by environmental and genetic factors, such as the abnormal regulation of protein post-translational modifications (PTMs). To date, many studies have shown that numerous PTMs, such as phosphorylation, acetylation, ubiquitination, SUMOylation, glycosylation, glycation, methylation, S-nitrosylation, carbonylation and S-glutathionylation, are involved in the regulation of muscle health and diseases. This article systematically summarizes the post-translational regulation of muscle growth and muscle atrophy and helps to understand the pathophysiology of muscle aging and develop effective strategies for diagnosing, preventing and treating sarcopenia.

Rheumatoid sarcopenia: loss of skeletal muscle strength and mass in rheumatoid arthritis

Sarcopenia, a disorder that involves the generalized loss of skeletal muscle strength and mass, was formally recognized as a disease by its inclusion in the International Classification of Diseases in 2016. Sarcopenia typically affects older people, but younger individuals with chronic disease are also at risk. The risk of sarcopenia is high (with a prevalence of ≥25%) in individuals with rheumatoid arthritis (RA), and this rheumatoid sarcopenia is associated with increased likelihood of falls, fractures and physical disability, in addition to the burden of joint inflammation and damage. Chronic inflammation mediated by cytokines such as TNF, IL-6 and IFNγ contributes to aberrant muscle homeostasis (for instance, by exacerbating muscle protein breakdown), and results from transcriptomic studies have identified dysfunction of muscle stem cells and metabolism in RA. Progressive resistance exercise is an effective therapy for rheumatoid sarcopenia but it can be challenging or unsuitable for some individuals. The unmet need for anti-sarcopenia pharmacotherapies is great, both for people with RA and for otherwise healthy older adults.

The Role of Regulated Programmed Cell Death in Osteoarthritis: From Pathogenesis to Therapy

Osteoarthritis (OA) is a worldwide chronic disease that can cause severe inflammation to damage the surrounding tissue and cartilage. There are many different factors that can lead to osteoarthritis, but abnormally progressed programmed cell death is one of the most important risk factors that can induce osteoarthritis. Prior studies have demonstrated that programmed cell death, including apoptosis, pyroptosis, necroptosis, ferroptosis, autophagy, and cuproptosis, has a great connection with osteoarthritis. In this paper, we review the role of different types of programmed cell death in the generation and development of OA and how the different signal pathways modulate the different cell death to regulate the development of OA. Additionally, this review provides new insights into the radical treatment of osteoarthritis rather than conservative treatment, such as anti-inflammation drugs or surgical operation.

Value of neutrophil-to-lymphocyte ratio for diagnosing sarcopenia in patients undergoing maintenance hemodialysis and efficacy of Baduanjin exercise combined with nutritional support

Objective

To investigate the value of neutrophil-to-lymphocyte ratio (NLR) for diagnosing sarcopenia in patients undergoing maintenance hemodialysis (MHD) and efficacy of Baduanjin exercise combined with nutritional support on MHD patients with sarcopenia.

Methods

A total of 220 patients undergoing MHD in MHD centers were selected, among which 84 had occurred with sarcopenia confirmed by measurements from the Asian Working Group for Sarcopenia. Data were collected for analyzing the influencing factors that lead to the onset of sarcopenia in MHD patients with the use of one-way analysis of variance and multivariate logistic regression. The role of NLR in the diagnosis of sarcopenia was explored, and its correlation with relevant diagnostic measurement performance such as grip strength, gait speed and skeletal muscle mass index was analyzed. In the end, some 74 patients with sarcopenia that qualify for further intervention and observation standards were divided into observation group (Baduanjin exercise plus nutritional support) and control group (nutritional support only), which were both intervened for 12 weeks. A total of 68 patients finished all interventions, with 33 patients in the observation group and 35 in the control group. The grip strength, gait speed, skeletal muscle mass index as well as the NLR were compared between the two groups.

Results

With the employment of multivariate logistic regression analysis, it was found that age, hemodialysis duration and NLR were risk factors for the onset of sarcopenia in MHD patients (P < 0.05). The area under ROC curve for NLR of MHD patients with sarcopenia was 0.695, and NLR was negatively correlated with a biochemical indicator-human blood albumin (P < 0.05). NLR was also negatively correlated with patient's grip strength, gait speed and skeletal muscle mass index, with the same correlation found in sarcopenia patients (all P < 0.05). After intervention, patient's grip strength and gait speed were both higher, and the NLR lower in the observation group than those in the control group (P < 0.05).

Conclusion

The occurrence of sarcopenia in MHD patients is associated with patient's age, hemodialysis duration and NLR. Therefore, it has been concluded that NLR has certain values in the diagnosis of sarcopenia in patients undergoing MHD. Moreover, the muscular strength can be enhanced and inflammation decreased in sarcopenia patients through nutritional support and physical exercise, i.e., Bajinduan exercise.

Effects of a Pedometer-Based Walking Home Program Plus Resistance Training on Inflammatory Cytokines and Depression in Thai Older People with Sarcopenia: A Three-Arm Randomized Controlled Trial

OBJECTIVE

To examine the effects of daily walking steps plus resistive exercise on chronic inflammatory markers and depressive symptoms in older adults with sarcopenia.

METHODS

Ninety men and women aged over 60 years were enrolled and divided into 60 and 30 adults with and without sarcopenia, respectively. Older individuals were screened for sarcopenia using the Asian Working Group for Sarcopenia in 2019. A simple random sample was conducted to divide the older adults with sarcopenia into two groups: control and intervention. Thirty older adults with sarcopenia were assigned to perform 12 weeks of step walking (>7500 steps) daily for 5 days/week plus resistance exercise with an elastic band twice/week; the control groups (i.e., no sarcopenia and sarcopenia) performed routine daily life Changes in depression and expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were measured before and after the 12-week intervention program. Two-way mixed ANOVA models were computed for group and interaction effects for each variable.

RESULTS

Changes in depressive symptom scores (Δ2.86 ± 0.92) and TNF-α levels (Δ22.16 ± 2.30) were observed in the intervention group after the 12-week program. In addition, an interaction effect between the intervention (Δ4.04 ± 3.10) and control groups (Δ8.10 ± 4.88) was found for the symptoms of depression.

CONCLUSION

Older people with sarcopenia who accumulated >7,500 steps/day, 5 days/week plus resistive elastic band twice /week show improvements in inflammation and depressive symptoms.

CLINICAL IMPLICATIONS

Encourage physical activity had a positive effect on reducing inflammation and depression among older people with sarcopenia.

Nonalcoholic fatty liver disease and accelerated loss of skeletal muscle mass: A longitudinal cohort study

BACKGROUND AND AIMS

Whether subjects with NAFLD are at increased risk of sarcopenia is not well established.

APPROACH AND RESULTS

This is a cohort study of 52,815 men and women of 20 years of age or older who underwent at least two health check-up exams with bioelectrical impedance analysis and abdominal ultrasound imaging. Bioelectrical impedance analysis was used to calculate appendicular skeletal muscle mass (ASM). NAFLD was assessed by ultrasonography, and its severity was assessed by the NAFLD fibrosis score (NFS). We estimated the 5-year change in ASM comparing participants with and without NAFLD at baseline using mixed linear models. The 5-year change in ASM in participants without and with NAFLD was -225.2 g (95% CI -232.3, -218.0) and -281.3 g (95% CI -292.0, -270.6), respectively (p < 0.001). In multivariable adjusted analysis, the difference in 5-year change in ASM comparing participants with and without NAFLD was -39.9 g (95% CI -53.1, -26.8). When participants with NAFLD were further divided by NAFLD severity, ASM loss was much faster in participants with NAFLD with intermediate to high NFS than in those with low NFS.

CONCLUSIONS

Participants with NAFLD were at increased risk of sarcopenia, indicated by faster loss of skeletal muscle mass. Patients with NAFLD may need screening and early intervention to mitigate skeletal muscle mass loss.

A Guide to the Postmortem Investigation of Starvation in Adults

ABSTRACT

Starvation is a rare cause of death in developed countries and is a complex multifaceted pathological process. To complicate the forensic investigation of starvation further, many medical conditions independent of starvation may cause wasting. This article provides one of the first comprehensive guides to the postmortem investigation of starvation in adults, with reference tables on organ-specific macroscopic and microscopic features, as well as features for excluding alternative causes of wasting. The eclectic literature on this complex topic is summarized in an accessible and easily referenced format, including mechanisms of death and ancillary postmortem investigations.

Inflammaging: The ground for sarcopenia?

Sarcopenia is a progressive skeletal muscle disease that occurs most commonly in the elderly population, contributing to increased costs and hospitalization. Exercise and nutritional therapy have been proven to be effective for sarcopenia, and some drugs can also alleviate declines in muscle mass and function due to sarcopenia. However, there is no specific pharmacological treatment for sarcopenia at present. This review will mainly discuss the relationship between inflammaging and sarcopenia. The increased secretion of proinflammatory cytokines with aging may be because of cellular senescence, immunosenescence, alterations in adipose tissue, damage-associated molecular patterns (DAMPs), and gut microbes due to aging. These sources of inflammaging can impact the sarcopenia process through direct or indirect pathways. Conversely, sarcopenia can also aggravate the process of inflammaging, creating a vicious cycle. Targeting sources of inflammaging can influence muscle function, which could be considered a therapeutic target for sarcopenia. Moreover, not only proinflammatory cytokines but also anti-inflammatory cytokines can influence muscle and inflammation and participate in the progression of sarcopenia. This review focuses on the effects of TNF-α, IL-6, and IL-10, which can be detected in plasma. Therefore, clearing chronic inflammation by targeting proinflammatory cytokines (TNF-α, IL-1, IL-6) and the inflammatory pathway (JAK/STAT, autophagy, NF-κB) may be effective in treating sarcopenia.

Unpacking determinants and consequences of food insecurity for insulin resistance among people living with HIV: Conceptual framework and protocol for the NOURISH-OK study

Background:

Over the past four decades, advances in HIV treatment have contributed to a longer life expectancy for people living with HIV (PLWH). With these gains, the prevention and management of chronic co-morbidities, such as diabetes, are now central medical care goals for this population. In the United States, food insecurity disproportionately impacts PLWH and may play a role in the development of insulin resistance through direct and indirect pathways. The Nutrition to Optimize, Understand, and Restore Insulin Sensitivity in HIV for Oklahoma (NOURISH-OK) will use a novel, multi-level, integrated framework to explore how food insecurity contributes to insulin resistance among PLWH. Specifically, it will explore how food insecurity may operate as an intermediary risk factor for insulin resistance, including potential linkages between upstream determinants of health and downstream consequences of poor diet, other behavioral risk factors, and chronic inflammation.

Methods/design:

This paper summarizes the protocol for the first aim of the NOURISH-OK study, which involves purposeful cross-sectional sampling of PLWH (n=500) across four levels of food insecurity to test our conceptual framework. Developed in collaboration with community stakeholders, this initial phase involves the collection of anthropometrics, fasting blood samples, non-blood biomarkers, 24-hour food recall to estimate the Dietary Inflammatory Index (DII^®) score, and survey data. A 1-month, prospective observational sub-study (total n=100; n=25 for each food security group) involves weekly 24-hour food recalls and stool samples to identify temporal associations between food insecurity, diet, and gut microbiome composition. Using structural equation modeling, we will explore how upstream risk factors, including early life events, current discrimination, and community food access, may influence food insecurity and its potential downstream impacts, including diet, other lifestyle risk behaviors, and chronic inflammation, with insulin resistance as the ultimate outcome variable. Findings from these analyses of observational data will inform the subsequent study aims, which involve qualitative exploration of significant pathways, followed by development and testing of a low-DII^® food as medicine intervention to reverse insulin resistance among PLWH (ClinicalTrials.gov Identifier: NCT05208671).

Discussion:

The NOURISH-OK study will address important research gaps to inform the development of food as medicine interventions to support healthy aging for PLWH.

Molecular Mechanisms of Inflammation in Sarcopenia: Diagnosis and Therapeutic Update

Sarcopenia is generally an age-related condition that directly impacts the quality of life. It is also related to chronic diseases such as metabolic dysfunction associated with diabetes and obesity. This means that everyone will be vulnerable to sarcopenia at some point in their life. Research to find the precise molecular mechanisms implicated in this condition can increase knowledge for the better prevention, diagnosis, and treatment of sarcopenia. Our work gathered the most recent research regarding inflammation in sarcopenia and new therapeutic agents proposed to target its consequences in pyroptosis and cellular senescence. Finally, we compared dual X-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and ultrasound (US) as imaging techniques to diagnose and follow up on sarcopenia, indicating their respective advantages and disadvantages. Our goal is for the scientific evidence presented here to help guide future research to understand the molecular mechanisms involved in sarcopenia, new treatment strategies, and their translation into clinical practice.

OA foundations - experimental models of osteoarthritis

Osteoarthritis (OA) is increasingly recognised as a disease of diverse phenotypes with variable clinical presentation, progression, and response to therapeutic intervention. This same diversity is readily apparent in the many animal models of OA. However, model selection, study design, and interpretation of resultant findings, are not routinely done in the context of the target human (or veterinary) patient OA sub-population or phenotype. This review discusses the selection and use of animal models of OA in discovery and therapeutic-development research. Beyond evaluation of the different animal models on offer, this review suggests focussing the approach to OA-animal model selection on study objective(s), alignment of available models with OA-patient sub-types, and the resources available to achieve valid and translatable results. How this approach impacts model selection is discussed and an experimental design checklist for selecting the optimal model(s) is proposed. This approach should act as a guide to new researchers and a reminder to those already in the field, as to issues that need to be considered before embarking on in vivo pre-clinical research. The ultimate purpose of using an OA animal model is to provide the best possible evidence if, how, when and where a molecule, pathway, cell or process is important in clinical disease. By definition this requires both model and study outcomes to align with and be predictive of outcomes in patients. Keeping this at the forefront of research using pre-clinical OA models, will go a long way to improving the quality of evidence and its translational value.

Impact of Sarcopenia and Myosteatosis in Non-Cirrhotic Stages of Liver Diseases: Similarities and Differences across Aetiologies and Possible Therapeutic Strategies

Sarcopenia is defined as a loss of muscle strength, mass and function and it is a predictor of mortality. Sarcopenia is not only a geriatric disease, but it is related to several chronic conditions, including liver diseases in both its early and advanced stages. Despite the increasing number of studies exploring the role of sarcopenia in the early stages of chronic liver disease (CLD), its prevalence and the relationship between these two clinical entities are still controversial. Myosteatosis is characterized by fat accumulation in the muscles and it is related to advanced liver disease, although its role in the early stages is still under researched. Therefore, in this narrative review, we firstly aimed to evaluate the prevalence and the pathogenetic mechanisms underlying sarcopenia and myosteatosis in the early stage of CLD across different aetiologies (mainly non-alcoholic fatty liver disease, alcohol-related liver disease and viral hepatitis). Secondly, due to the increasing prevalence of sarcopenia worldwide, we aimed to revise the current and the future therapeutic approaches for the management of sarcopenia in CLD.

The potential roles of JAK/STAT signaling in the progression of osteoarthritis

Osteoarthritis (OA) is an age-related chronic progressive degenerative disease that induces persistent pain and disabilities. The development of OA is a complex process, and the risk factors are various, including aging, genetics, trauma and altered biomechanics. Inflammation and immunity play an important role in the pathogenesis of OA. JAK/STAT pathway is one of the most prominent intracellular signaling pathways, regulating cell proliferation, differentiation, and apoptosis. Inflammatory factors can act as the initiators of JAK/STAT pathway, which is implicated in the pathophysiological activity of chondrocyte. In this article, we provide a review on the importance of JAK/STAT pathway in the pathological development of OA. Potentially, JAK/STAT pathway becomes a therapeutic target for managing OA.

Associations between Circulating Inflammatory Biomarkers and Indicators of Muscle Health in Older Men and Women

Systemic inflammation is believed to contribute to declining muscle health during aging. The present study aims to examine associations between indicators of muscle health and pro- and anti-inflammatory biomarkers in older men and women, while also considering the impacts of physical activity and protein intake. An assessment of skeletal muscle index (SMI) by bioelectrical impedance analysis, handgrip strength, and 5-sit-to-stand time, using standardized procedures, was conducted in a population of older men (n = 90) and women (n = 148) aged 65–70 years. The inflammatory biomarkers C-reactive protein (CRP), fibrinogen, interleukin (IL)-6, IL-10, IL-18, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1α were assessed in blood samples. Data were analyzed and stratified according to biological sex using multiple linear regression models. In older women, SMI was inversely associated with the pro-inflammatory markers CRP (β = −0.372; p < 0.05), fibrinogen (β = −0.376; p < 0.05), and IL-6 (β = −0.369; p < 0.05). Importantly, these associations were independent of abdominal adiposity (waist circumference), protein intake, physical activity level, as well as any adherence to muscle strengthening guidelines (≥2 sessions/week). In contrast, no corresponding associations were observed in men. In conclusion, our findings indicate the detrimental influence of a pro-inflammatory environment on muscle health regardless of important lifestyle-related factors in older women. However, the lack of such associations in older men highlights the importance of considering biological sex when examining the complex interaction between the systemic inflammatory environment and muscle health.

Role of L3-PMI in prognostic evaluation of patients with acute-on-chronic liver failure related to hepatitis B cirrhosis

BACKGROUND

Sarcopenia has received widespread attention in patients with end-stage liver disease since it is an independent risk factor for death and is closely related to the prognosis of the patients. However, there is still a lack of unified detection methods and diagnostic criteria for sarcopenia.

AIM

To evaluate the relationship between the third lumbar psoas muscle index (L3-PMI) and clinical indicators in patients with acute-on-chronic liver failure (ACLF) associated with hepatitis B cirrhosis and its role in prognostic evaluation.

METHODS

A retrospective study was performed on 140 patients who were hospitalized at the Department of Hepatology, Tianjin Third Central Hospital from January 2014 to December 2017, met the ACLF diagnostic criteria for hepatitis B cirrhosis, and had abdominal CT data. The same researcher manually tracked the level of the lower edge of the third lumbar vertebra on the CT images of the patient's abdomen, measured the maximum anteroposterior and transverse diameters of the psoas major on both sides, and calculated the psoas major index. The relationship of L3-PMI with clinical characteristics and prognosis was then analyzed.

RESULTS

The 140 patients were divided into a survival group with 102 cases and a death group with 38 cases according to their 90-d survival status. The L3-PMI value of patients in the death group was 4.89 cm²/m² ± 1.42 cm²/m², significantly lower than that of patients in the survival group (5.94 cm²/m² ± 1.24 cm²/m²; P < 0.001). There was no statistical difference between the two groups in PLT, ALB, ALT, AST, SCr, or eGFR (P > 0.05). The WBC, INR, and MELD scores of the death group were significantly higher than those of the survival group, while the serum sodium was significantly lower than that of the survival group (P < 0.05). In addition, 33 ACLF patients with hepatic encephalopathy (HE) had an L3-PMI value of 5.17 cm²/m² ± 1.49 cm²/m², which was significantly lower than that of 107 patients without HE (P = 0.020). Among all ACLF patients, there were 120 males and 20 females. The L3-PMI value of the male group (5.92 cm²/m² ± 1.23 cm²/m²) was significantly higher than that of the female group (4.03 cm²/m² ± 0.92 cm²/m²; P < 0.05). The ROC curve of L3-PMI for predicting death by gender was plotted. The area under the ROC curve for males was 0.726, the cut-off value was 5.02, and the sensitivity and specificity were 85% and 50%, respectively. The area under the ROC curve for females was 0.774, the cut-off value was 4.60, and the sensitivity and specificity were 50% and 100%, respectively.

CONCLUSION

L3-PMI has important clinical application value for evaluating the prognosis of ACLF patients related to hepatitis B liver cirrhosis.

Autoimmune Rheumatic Diseases and Vascular Function: The Concept of Autoimmune Atherosclerosis

Autoimmune rheumatic diseases (AIRDs) with unknown etiology are increasing in incidence and prevalence. Up to 5% of the population is affected. AIRDs include rheumatoid arthritis, system lupus erythematosus, systemic sclerosis, and Sjögren's syndrome. In patients with autoimmune diseases, the immune system attacks structures of its own body, leading to widespread tissue and organ damage, which, in turn, is associated with increased morbidity and mortality. One third of the mortality associated with autoimmune diseases is due to cardiovascular diseases. Atherosclerosis is considered the main underlying cause of cardiovascular diseases. Currently, because of finding macrophages and lymphocytes at the atheroma, atherosclerosis is considered a chronic immune-inflammatory disease. In active inflammation, the liberation of inflammatory mediators such as tumor necrotic factor alpha (TNFa), interleukine-6 (IL-6), IL-1 and other factors like T and B cells, play a major role in the atheroma formation. In addition, antioxidized, low-density lipoprotein (LDL) antibodies, antinuclear antibodies (ANA), and rheumatoid factor (RF) are higher in the atherosclerotic patients. Traditional risk factors like gender, age, hypercholesterolemia, smoking, diabetes mellitus, and hypertension, however, do not alone explain the risk of atherosclerosis present in autoimmune diseases. This review examines the role of chronic inflammation in the etiology-and progression-of atherosclerosis in autoimmune rheumatic diseases. In addition, discussed here in detail are the possible effects of autoimmune rheumatic diseases that can affect vascular function. We present here the current findings from studies that assessed vascular function changes using state-of-the-art techniques and innovative endothelial function biomarkers.

Low hand grip strength is associated with worse functional capacity and higher inflammation in people receiving maintenance hemodialysis

OBJECTIVES

To evaluate the associations of hand grip strength (HGS) with body composition, functional capacity, muscle quality, and inflammatory markers in people receiving maintenance hemodialysis.

METHODS

This is a cross-sectional study in people receiving maintenance hemodialysis. HGS was measured by hydraulic dynamometer on the upper limb without fistula. Participants were stratified into low or adequate HGS, based on population-specific cutoff points. Body composition was assessed by dual-energy X-ray absorptiometry, and functional capacity by the Short Physical Performance Battery and timed up-and-go tests. In addition, serum creatinine, interleukin-6 (IL-6), IL-10, tumor necrosis factor-α, and ultra-sensitive C-reactive protein (us-CRP) were measured before the dialysis session.

RESULTS

A total of 67 participants (41.8% women, 58.2% male; ages 54.1 ± 11.7 y) were included. Those with low HGS had worse functional capacity than those with adequate HGS (timed up-and-go test, 10.7 ± 1.0 versus 8.5 ± 0.8 sec, respectively; P < 0.001). IL-6 and us-CRP were higher in those with low HGS than their counterparts (IL-6: 2.7 ± 0.3 versus 1.9 pg/mL, P = 0.03; us-CRP: 14.8 ± 3.0 versus 4.7 ± 1.9 mg/L, P = 0.03). Multiple linear regression analysis showed that appendicular lean mass, us-CRP, age, sex, and seven-point subjective global assessment score were associated with HGS.

CONCLUSIONS

Participants with low HGS showed higher inflammation and lower functional capacity. In addition to muscle mass, inflammation and nutritional status also affect HGS.<END ABSTRACT>.

Exercise therapy for sarcopenia in rheumatoid arthritis: A meta-analysis and meta-regression of randomized controlled trials

OBJECTIVE

Rheumatoid arthritis and age are associated with high sarcopenia risk. Exercise is an effective treatment for preventing muscle mass loss in older adult populations. It remains unclear whether exercise affects muscle mass in people with rheumatoid arthritis. Thus, this meta-analysis investigated the effect of exercise on muscle mass gain in patients with rheumatoid arthritis.

DATA SOURCES

PubMed, EMBASE, the Cochrane Library, the Physiotherapy Evidence Database (PEDro), the China Knowledge Resource Integrated Database, and Google Scholar were systematically searched until June 2021.

METHODS

The present study was conducted according to the guidelines recommended by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Randomized controlled trials (RCTs) that reported the effects of exercise on muscle mass for rheumatoid arthritis were identified. The included RCTs were subject to meta-analysis and risk of bias assessment. Subgroup and random-effects meta-regression analyses were performed to identify any heterogeneity (I²) of treatment effects across studies.

RESULTS

We included nine RCTs with a median PEDro score of 6/10 (range: 4/10-8/10). The weighted mean effect size for muscle mass was 0.77 (95% CI: 0.30-1.24; P = 0.001; I² = 77%). Meta-regression analyses indicated that the disease duration significantly explained variance of treatment effects across studies (β = -0.006, R² = 69.7%, P = 0.005).

CONCLUSIONS

Exercise therapy effectively increased muscle mass in patients with rheumatoid arthritis. Treatment effects may be attenuated in those who have had rheumatoid arthritis for a relatively long time.

The Dietary Inflammatory Index Is Associated with Low Muscle Mass and Low Muscle Function in Older Australians

Age-associated chronic, low grade systemic inflammation has been recognised as an important contributing factor in the development of sarcopenia; importantly, diet may regulate this process. This cross-sectional study examined the association of diet-related inflammation with components of sarcopenia. Participants (n = 809) aged 60–95 years from the Geelong Osteoporosis Study were studied. Body composition was measured by dual energy X-ray absorptiometry. In this study, low appendicular lean mass (ALM/height², kg/m²) was defined as T-score < −1 and low muscle function as Timed-Up-and-Go >10 s over 3 m (TUG > 10). Dietary inflammatory index (DII^®) scores, based on specific foods and nutrients, were computed using dietary data collected from a food frequency questionnaire. Associations between DII scores and low muscle mass and low muscle function, alone and combined, were determined using linear and logistic regression. After adjusting for covariates, higher DII score was associated with lower ALM/height² (β −0.05, standard error (SE) 0.02, p = 0.028), and higher natural log-transformed (ln) (TUG) (β 0.02, standard error 0.01, p = 0.035) and higher likelihood for these components combined (odds ratio 1.33, 95% confidence interval 1.05 to 1.69, p = 0.015). A pro-inflammatory diet, as indicated by higher DII score, is associated with lower muscle mass, poorer muscle function and increased likelihood for the combination of low muscle mass and low muscle function. Further studies investigating whether anti-inflammatory dietary interventions could reduce the risk of sarcopenia are needed.

Revisiting the clinical usefulness of C-reactive protein in the set of cancer cachexia

Cancer cachexia is a highly complex multifactorial disorder that is often misdiagnosed, leading to suboptimal health outcomes. Indeed, cachexia is a concern in cancer, typifying lower response to treatment and risk of death. Thus, efforts have been made to better understand the molecular basis of this syndrome, envisioning to improve its diagnosis and management.

C-reactive protein (CRP) has been reported to be consistently increased in the circulation of patients with body wasting associated to chronic diseases. However, the role of CRP in the pathogenesis of cachexia remains elusive. Several hypotheses have been advanced but most of experimental findings support an indirect effect on the activation of muscle proteolysis, mostly through its interplay with pro-inflammatory cytokines. Herein, we overview the contribution of CRP to body wasting and its putative biomarker value for the diagnosis and follow-up of the therapeutic management of cachexia.

Magnetization of mesenchymal stem cells using magnetic liposomes enhances their retention and immunomodulatory efficacy in mouse inflamed skeletal muscle

Sarcopenia, an age-related reduction in skeletal muscle mass and strength, is mainly caused by chronic inflammation. Because mesenchymal stem cells (MSCs) have the capacity to both promote myogenic cell differentiation and suppress inflammation, they are a promising candidate for sarcopenia treatment. In this study, to achieve the long-term retention of MSCs in skeletal muscle, we prepared magnetized MSCs using magnetic anionic liposome/atelocollagen complexes that we had previously developed, and evaluated their retention efficiency and immunomodulatory effects in mouse inflamed skeletal muscle. Mouse MSCs were efficiently magnetized by incubation with magnetic anionic liposome/atelocollagen complexes for 30 min under a magnetic field. The magnetized MSCs differentiated normally into osteoblasts and adipocytes. Additionally, non-magnetized MSCs and magnetized MSCs increased IL-6 and inducible nitric oxide synthase mRNA expression and decreased TNF-α and IL-1β mRNA expression in C2C12 mouse skeletal muscle myotubes through paracrine effects. Moreover, magnetized MSCs were significantly retained in cell culture plates and mouse skeletal muscle after their local injection in the presence of a magnetic field. Furthermore, magnetized MSCs significantly increased IL-6 and IL-10 mRNA expression and decreased TNF-α and IL-1β mRNA expression in inflamed skeletal muscle. These results suggest that magnetized MSCs may be useful for effective sarcopenia treatment.

A roadmap to target interleukin-6 in osteoarthritis

Joint inflammation is present in the majority of OA patients and pro-inflammatory mediators, such as IL-6, are actively involved in disease progression. Increased levels of IL-6 in serum or synovial fluid from OA patients correlate with disease incidence and severity, with IL-6 playing a pivotal role in the development of cartilage pathology, e.g. via induction of matrix-degrading enzymes. However, IL-6 also increases expression of anti-catabolic factors, suggesting a protective role. Until now, this dual role of IL-6 is incompletely understood and may be caused by differential effects of IL-6 classic vs trans-signalling. Here, we review current evidence regarding the role of IL-6 classic- and trans-signalling in local joint pathology of cartilage, synovium and bone. Furthermore, we discuss targeting of IL-6 in experimental OA models and provide future perspective for OA treatment by evaluating currently available IL-6 targeting strategies.

Exercise mimetics and JAK inhibition attenuate IFN-γ-induced wasting in engineered human skeletal muscle

Chronic inflammatory diseases often lead to muscle wasting and contractile deficit. While exercise can have anti-inflammatory effects, the underlying mechanisms remain unclear. Here, we used an in vitro tissue-engineered model of human skeletal muscle ("myobundle") to study effects of exercise-mimetic electrical stimulation (E-stim) on interferon-γ (IFN-γ)-induced muscle weakness. Chronic IFN-γ treatment of myobundles derived from multiple donors induced myofiber atrophy and contractile loss. E-stim altered the myobundle secretome, induced myofiber hypertrophy, and attenuated the IFN-γ-induced myobundle wasting and weakness, in part by down-regulating JAK (Janus kinase)/STAT1 (signal transducer and activator of transcription 1) signaling pathway amplified by IFN-γ. JAK/STAT inhibitors fully prevented IFN-γ-induced myopathy, confirming the critical roles of STAT1 activation in proinflammatory action of IFN-γ. Our results reveal a previously unknown mechanism of the cell-autonomous anti-inflammatory effects of muscle exercise and establish the utility of human myobundle platform for studies of inflammatory muscle disease and therapy.

Low-dose aspirin and COX inhibition in human skeletal muscle

Skeletal muscle health has been shown to benefit from regular consumption of cyclooxygenase (COX)-inhibiting drugs. Aspirin, especially at low doses, is one of the most commonly consumed COX inhibitors, yet investigations of low-dose aspirin effects on skeletal muscle are nonexistent. The goal of this study was to examine the efficacy of low-dose aspirin on skeletal muscle COX production of the inflammatory regulator prostaglandin (PG)E₂ at rest and after exercise. Skeletal muscle biopsies (vastus lateralis) were taken from eight individuals [4 men, 4 women; 25 ± 1 yr; 81.4 ± 3.4 kg; maximal oxygen consumption (V̇o_2max): 3.33 ± 0.21 L/min] before and 3.5 h after 40 min of cycling at 70% of V̇o_2max for the measurement of ex vivo PGE₂ production. Muscle strips were incubated in Krebs-Henseleit buffer (control) or supplemented with one of two aspirin concentrations that reflected blood levels after a low (10 µM; typical oral dose: 75-325 mg) or standard (100 µM; typical oral dose: 975-1,000 mg) dose. Low (-22 ± 5%)- and standard (-28 ± 5%)-dose aspirin concentrations both reduced skeletal muscle PGE₂ production, independent of exercise (P < 0.05). There was no difference in PGE₂ suppression between the two doses (P > 0.05). In summary, low-dose aspirin levels are sufficient to inhibit the COX enzyme in skeletal muscle and significantly reduce production of PGE₂, a known regulator of skeletal muscle health. Aerobic exercise does not appear to alter the inhibitory efficacy of aspirin. These findings may have implications for the tens of millions of individuals who chronically consume low-dose aspirin.NEW & NOTEWORTHY This study demonstrated that even low-dose aspirin concentrations can significantly reduce the prostaglandin (PG)E₂/cyclooxygenase (COX) pathway activity in human skeletal muscle and this effect is not altered during the recovery period following aerobic exercise. These findings are noteworthy since aspirin is one of the most commonly consumed drugs in the world and nonaspirin COX-inhibiting drugs have been shown to regulate skeletal muscle health in sedentary and exercise-training individuals.

A machine learning-based clinical tool for diagnosing myopathy using multi-cohort microarray expression profiles

BACKGROUND

Myopathies are a heterogenous collection of disorders characterized by dysfunction of skeletal muscle. In practice, myopathies are frequently encountered by physicians and precise diagnosis remains a challenge in primary care. Molecular expression profiles show promise for disease diagnosis in various pathologies. We propose a novel machine learning-based clinical tool for predicting muscle disease subtypes using multi-cohort microarray expression data.

MATERIALS AND METHODS

Muscle tissue samples originating from 1260 patients with muscle weakness. Data was curated from 42 independent cohorts with expression profiles in public microarray gene expression repositories, which represent a broad range of patient ages and peripheral muscles. Cohorts were categorized into five muscle disease subtypes: immobility, inflammatory myopathies, intensive care unit acquired weakness (ICUAW), congenital, and chronic systemic disease. The data contains expression data on 34,099 genes. Data augmentation techniques were used to address class imbalances in the muscle disease subtypes. Support vector machine (SVM) models were trained on two-thirds of the 1260 samples based on the top selected gene signature using analysis of variance (ANOVA). The model was validated in the remaining samples using area under the receiver operator curve (AUC). Gene enrichment analysis was used to identify enriched biological functions in the gene signature.

RESULTS

The AUC ranges from 0.611 to 0.649 in the observed imbalanced data. Overall, using the augmented data, chronic systemic disease was the best predicted class with AUC 0.872 (95% confidence interval (CI): 0.824-0.920). The least discriminated classes were ICUAW with AUC 0.777 (95% CI: 0.668-0.887) and immobility with AUC 0.789 (95% CI: 0.716-0.861). Disease-specific gene set enrichment results showed that the gene signature was enriched in biological processes including neural precursor cell proliferation for ICUAW and aerobic respiration for congenital (false discovery rate q-value < 0.001).

CONCLUSION

Our results present a well-performing molecular classification tool with the selected gene markers for muscle disease classification. In practice, this tool addresses an important gap in the literature on myopathies and presents a potentially useful clinical tool for muscle disease subtype diagnosis.

Soluble Whey Protein Hydrolysate Ameliorates Muscle Atrophy Induced by Immobilization via Regulating the PI3K/Akt Pathway in C57BL/6 Mice

Sarcopenia, a loss of skeletal muscle mass and function, is prevalent in older people and associated with functional decline and mortality. Protein supplementation is necessary to maintain skeletal muscle mass and whey protein hydrolysates have the best nutrient quality among food proteins. In the first study, C57BL/6 mice were subjected to immobilization for 1 week to induce muscle atrophy. Then, mice were administered with four different whey protein hydrolysates for 2 weeks with continuous immobilization. Among them, soluble whey protein hydrolysate (WP-S) had the greatest increase in grip strength, muscle weight, and cross-sectional area of muscle fiber than other whey protein hydrolysates. To investigate the molecular mechanism, we conducted another experiment with the same experimental design. WP-S significantly promoted the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway and inhibited the PI3K/Akt/forkhead box O (FoxO) pathway. In addition, it increased myosin heavy chain (MyHC) expression in both the soleus and quadriceps and changed MyHC isoform expressions. In conclusion, WP-S attenuated muscle atrophy induced by immobilization by enhancing the net protein content regulating muscle protein synthesis and degradation. Thus, it is a necessary and probable candidate for developing functional food to prevent sarcopenia.

Sarcopenia in aging, obesity, and cancer

Sarcopenia, defined as loss of muscle mass, strength and physical performance, is a hallmark of aging and is invariably associated with perturbation of amino acid metabolism, increased muscle protein catabolism relative to anabolism, and loss of muscle fibers. Sarcopenia may be associated with general loss of body mass, or it may also occur along with obesity [sarcopenic obesity (SO)]. Although sarcopenia is associated with multiple comorbidities in older adults, its effects may even be more severe in patients with malignant disease where it has been shown to contribute to poor surgical outcomes, increased chemotherapy toxicity associated with both cytotoxic and targeted agents, as well as adversely impacting survival. While development of sarcopenia is a common age-related phenomenon, the associated catabolic processes appear to be promoted by physical inactivity, inadequate nutrition, and systemic low-grade inflammation, as well as intrinsic muscle and molecular changes, including mitochondrial dysfunction and impaired muscle stem cell regenerative capacity. Increased physical activity and adequate protein intake can reduce incidence and severity of sarcopenia in cancer patients, but many older cancer patients do not meet physical activity and nutrition recommendations, and cancer treatment can make it more difficult to make favorable lifestyle changes. Sarcopenia is discussed in terms of its adverse clinical consequences in older subjects and particularly, in older patients with cancer. Contributions of lifestyle, molecular, and cellular factors are likewise reviewed with suggestions for interventions to improve sarcopenia and its comorbid sequalae.

Supplement Use in Patients Undergoing Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To assess whether a standardized dietary supplementation can help to decrease postoperative muscle atrophy and/or improve rehabilitation outcomes in patients who underwent anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). MEDLINE, Scopus, and Cochrane Library databases were searched, and articles that examined protein or amino acid, vitamin, or any other type of supplementation in ACLR were reviewed. Two independent reviewers conducted the search using pertinent Boolean operations.

RESULTS

A total of 1818 articles were found after our database search. Ten studies fulfilled our inclusion criteria and only assessed patients undergoing ACLR. Four studies assessed protein-based supplementation. One study assessed creatine as a supplement. Four studies assessed vitamin-based supplementation. One study assessed testosterone supplementation. Protein and amino acid supplementation showed potential benefits; multiple authors demonstrated a combination of improved achievement of rehabilitation benchmarks, graft maturation, muscular hypertrophic response, and peak dynamic muscle strength. When we examined creatine, vitamin, or hormone-based protocols, none demonstrated results, suggesting these factors may attenuate muscle atrophy after surgery. Vitamin C and E demonstrated potentially increased local inflammation in skeletal muscle, which runs contrary to the belief that antioxidant vitamin-based supplementation may decrease the inflammatory response that plays a role in the post injury/operative period.

CONCLUSIONS

Protein-based supplementation may play a role in mitigating muscle atrophy associated with ACLR, as multiple authors demonstrated a combination of improved achievement of rehabilitation benchmarks, thigh hypertrophic response, and peak dynamic muscle strength. However, based on current literature, it is not possible to recommend a specific protein-based supplementation protocol at this time for patients undergoing ACLR. Limited evidence suggests no benefit for creatine, vitamin, or hormone-based protocols.

LEVEL OF EVIDENCE

II, a systematic review of level I-II studies.

Sarcopenia Is Associated With Development of Acute-on-Chronic Liver Failure in Decompensated Liver Cirrhosis Receiving Transjugular Intrahepatic Portosystemic Shunt

Muscle mass has been shown to be a prognostic marker in patients with liver cirrhosis. Transversal psoas muscle thickness normalized by height (TPMT/height) obtained by routine computed tomography is a simple surrogate parameter for sarcopenia. TPMT/height, however, is not sex specific, which might play a role in risk stratification. Its association with acute-on-chronic liver failure (ACLF) has not been established yet. ACLF is associated with systemic inflammatory dysregulation. This study aimed at evaluating the role of sarcopenia in ACLF development of patients with decompensated cirrhosis receiving transjugular intrahepatic portosystemic shunt (TIPS) using sex-specific TPMT/height.

Muscle, Bone, and Fat Crosstalk: the Biological Role of Myokines, Osteokines, and Adipokines

PURPOSE OF REVIEW

Skeletal muscle and bone are connected anatomically and physiologically, and play a crucial role in human locomotion and metabolism. Historically, the coupling between muscle and bone has been viewed in light of mechanotransduction, which dictates that the mechanical forces applied to muscle are transmitted to the skeleton to initiate bone formation. However, these organs also communicate through the endocrine system, orchestrated by a family of cytokines namely myokines (derived from myocytes) and osteokines (derived from bone cells). A third player in this biochemical crosstalk is adipose tissue and the secretion of adipokines (derived from adipocytes). In this review, we discuss the bidirectional effects of myokines and osteokines on muscle and bone metabolism, and the impact of adipokines on both of these secretory organs.

RECENT FINDINGS

Several myokines, notably, IL6, irisin, IGF-1, BDNF, myostatin, and FGF2 exert anabolic/catabolic effects on bone, while the osteokines osteocalcin and sclerostin have shown to induce muscle anabolism and catabolism, respectively. Adipokines, such as leptin, resistin, adiponectin, and TNFα (released from adipose tissue), can also modulate muscle and bone metabolism. Contrarily, exercise-mediated release of lipolytic myokines (IL6, irisin, and LIF) stimulates thermogenesis by promoting the browning of adipocytes. Myokines, osteokines, and adipokines exert autocrine/paracrine effects locally as well as through the endocrine system, to regulate muscle, bone, and fat metabolism. Reductions in physical activity and increases in energy intake, both linked with aging, leads to adipocyte hypertrophy and the recruitment of immunological cells (macrophages). In turn, this releases pro-inflammatory adipokines which induces chronic low-grade inflammation (LGI), a key player in the pathology of several diseases. However, exercise-induced stimulation of bioactive cytokines, through muscle-bone-fat crosstalk, increases muscle anabolism, bone formation, mitochondrial biogenesis, glucose utilization, and fatty acid oxidation, and attenuates chronic LGI.

Translation Regulation by eIF2α Phosphorylation and mTORC1 Signaling Pathways in Non-Communicable Diseases (NCDs)

Non-communicable diseases (NCDs) are medical conditions that, by definition, are non-infectious and non-transmissible among people. Much of current NCDs are generally due to genetic, behavioral, and metabolic risk factors that often include excessive alcohol consumption, smoking, obesity, and untreated elevated blood pressure, and share many common signal transduction pathways. Alterations in cell and physiological signaling and transcriptional control pathways have been well studied in several human NCDs, but these same pathways also regulate expression and function of the protein synthetic machinery and mRNA translation which have been less well investigated. Alterations in expression of specific translation factors, and disruption of canonical mRNA translational regulation, both contribute to the pathology of many NCDs. The two most common pathological alterations that contribute to NCDs discussed in this review will be the regulation of eukaryotic initiation factor 2 (eIF2) by the integrated stress response (ISR) and the mammalian target of rapamycin complex 1 (mTORC1) pathways. Both pathways integrally connect mRNA translation activity to external and internal physiological stimuli. Here, we review the role of ISR control of eIF2 activity and mTORC1 control of cap-mediated mRNA translation in some common NCDs, including Alzheimer’s disease, Parkinson’s disease, stroke, diabetes mellitus, liver cirrhosis, chronic obstructive pulmonary disease (COPD), and cardiac diseases. Our goal is to provide insights that further the understanding as to the important role of translational regulation in the pathogenesis of these diseases.

Preclinical insights into the gut-skeletal muscle axis in chronic gastrointestinal diseases

Muscle wasting represents a constant pathological feature of common chronic gastrointestinal diseases, including liver cirrhosis (LC), inflammatory bowel diseases (IBD), chronic pancreatitis (CP) and pancreatic cancer (PC), and is associated with increased morbidity and mortality. Recent clinical and experimental studies point to the existence of a gut‐skeletal muscle axis that is constituted by specific gut‐derived mediators which activate pro‐ and anti‐sarcopenic signalling pathways in skeletal muscle cells. A pathophysiological link between both organs is also provided by low‐grade systemic inflammation. Animal models of LC, IBD, CP and PC represent an important resource for mechanistic and preclinical studies on disease‐associated muscle wasting. They are also required to test and validate specific anti‐sarcopenic therapies prior to clinical application. In this article, we review frequently used rodent models of muscle wasting in the context of chronic gastrointestinal diseases, survey their specific advantages and limitations and discuss possibilities for further research activities in the field. We conclude that animal models of LC‐, IBD‐ and PC‐associated sarcopenia are an essential supplement to clinical studies because they may provide additional mechanistic insights and help to identify molecular targets for therapeutic interventions in humans.

Emerging Strategies Targeting Catabolic Muscle Stress Relief

Skeletal muscle wasting represents a common trait in many conditions, including aging, cancer, heart failure, immobilization, and critical illness. Loss of muscle mass leads to impaired functional mobility and severely impedes the quality of life. At present, exercise training remains the only proven treatment for muscle atrophy, yet many patients are too ill, frail, bedridden, or neurologically impaired to perform physical exertion. The development of novel therapeutic strategies that can be applied to an in vivo context and attenuate secondary myopathies represents an unmet medical need. This review discusses recent progress in understanding the molecular pathways involved in regulating skeletal muscle wasting with a focus on pro-catabolic factors, in particular, the ubiquitin-proteasome system and its activating muscle-specific E3 ligase RING-finger protein 1 (MuRF1). Mechanistic progress has provided the opportunity to design experimental therapeutic concepts that may affect the ubiquitin-proteasome system and prevent subsequent muscle wasting, with novel advances made in regards to nutritional supplements, nuclear factor kappa-light-chain-enhancer of activated B cells (NFB) inhibitors, myostatin antibodies, β2 adrenergic agonists, and small-molecules interfering with MuRF1, which all emerge as a novel in vivo treatment strategies for muscle wasting.

Physiological stress markers, mental health and objective physical function

OBJECTIVE

The observed poorer physical function in persons with mental disorders could partly be due to dysregulation in physiological stress systems. However, an integrated picture of the role of physiological stress systems on objective physical function is lacking. This study examined the association of multiple physiological stress systems with objective physical function, and explored whether these stress systems contribute to the relationship between depression/anxiety and poorer physical function.

METHODS

Data of 2860 persons of the Netherlands Study of Depression and Anxiety was used. Physical function was indicated by hand grip strength assessed using a hand-held dynamometer and lung function assessed using a peak flow meter. Inflammatory markers (CRP, IL-6, TNF-α), salivary cortisol (cortisol awakening response (AUCg, AUCi), evening cortisol) and ANS markers (heartrate, PEP, RSA) were determined. Depression/anxiety disorders were determined using psychiatric interviews. Linear regression analyses were adjusted for sociodemographics, health and lifestyle factors.

RESULTS

Higher inflammation levels were associated with lower hand grip strength (B_CRP = -0.21(SE = 0.06), p < .001) and lower lung function (B_CRP = -2.07(SE = 0.66), p = .002), B_TNF-α = -3.35(SE = 1.42), p = .022). Higher salivary cortisol levels were associated with lower lung function (B_{evening cortisol} = -2.22(SE = 0.59), p < .001). The association, in women, between depression/anxiety disorders and poorer physical function did not significantly diminish after adjustment for physiological stress markers.

CONCLUSION

This large cohort study showed that stress system dysfunction (especially the immune-inflammatory system and HPA-axis) contributes to poorer objective physical function. Stress system dysfunction did not explain the poorer physical function observed in persons with depression/anxiety disorders, suggesting that other pathways are involved to explain that association.

Myokines: The endocrine coupling of skeletal muscle and bone

Bone and skeletal muscle are integrated organs and their coupling has been considered mainly a mechanical one in which bone serves as attachment site to muscle while muscle applies load to bone and regulates bone metabolism. However, skeletal muscle can affect bone homeostasis also in a non-mechanical fashion, i.e., through its endocrine activity. Being recognized as an endocrine organ itself, skeletal muscle secretes a panel of cytokines and proteins named myokines, synthesized and secreted by myocytes in response to muscle contraction. Myokines exert an autocrine function in regulating muscle metabolism as well as a paracrine/endocrine regulatory function on distant organs and tissues, such as bone, adipose tissue, brain and liver. Physical activity is the primary physiological stimulus for bone anabolism (and/or catabolism) through the production and secretion of myokines, such as IL-6, irisin, IGF-1, FGF2, beside the direct effect of loading. Importantly, exercise-induced myokine can exert an anti-inflammatory action that is able to counteract not only acute inflammation due to an infection, but also a condition of chronic low-grade inflammation raised as consequence of physical inactivity, aging or metabolic disorders (i.e., obesity, type 2 diabetes mellitus). In this review article, we will discuss the effects that some of the most studied exercise-induced myokines exert on bone formation and bone resorption, as well as a brief overview of the anti-inflammatory effects of myokines during the onset pathological conditions characterized by the development a systemic low-grade inflammation, such as sarcopenia, obesity and aging.

Sarcopenic Obesity in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a public health epidemic that is projected to double over the next two decades. Despite the high prevalence of HFpEF, there are currently no FDA approved therapies for health-related outcomes in this clinical syndrome making it one the greatest unmet needs in cardiovascular medicine. Aging and obesity are hallmarks of HFpEF and therefore there is a high incidence of sarcopenic obesity (SO) associated with this syndrome. The presence of SO in HFpEF patients is noteworthy as it is associated with co-morbidities, worsened cardiovascular health, hospitalizations, quality of life, and mortality. Furthermore, SO plays a central role in exercise intolerance, the most commonly reported clinical symptom of this condition. The aim of this review is to provide insights into the current knowledge pertaining to the contributing pathophysiological mechanisms and clinical outcomes associated with HFpEF-related SO. Current and prospective therapies to address SO in HFpEF, including lifestyle and pharmaceutical approaches, are discussed. The urgent need for future research aimed at better understanding the multifaceted physiological contributions to SO in HFpEF and implementing interventional strategies to specifically target SO is highlighted.