Is inflammatory signaling involved in disease-related muscle wasting? Evidence from osteoarthritis, chronic obstructive pulmonary disease and type II diabetes

Exercise following joint distraction inhibits muscle wasting and delays the progression of post-traumatic osteoarthritis in rabbits by activating PGC-1α in skeletal muscle

OBJECTIVE

Muscle wasting frequently occurs following joint trauma. Previous research has demonstrated that joint distraction in combination with treadmill exercise (TRE) can mitigate intra-articular inflammation and cartilage damage, consequently delaying the advancement of post-traumatic osteoarthritis (PTOA). However, the precise mechanism underlying this phenomenon remains unclear. Hence, the purpose of this study was to examine whether the mechanism by which TRE following joint distraction delays the progression of PTOA involves the activation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), as well as its impact on muscle wasting.

METHODS

Quadriceps samples were collected from patients with osteoarthritis (OA) and normal patients with distal femoral fractures, and the expression of PGC-1α was measured. The hinged external fixator was implanted in the rabbit PTOA model. One week after surgery, a PGC-1α agonist or inhibitor was administered for 4 weeks prior to TRE. Western blot analysis was performed to detect the expression of PGC-1α and Muscle atrophy gene 1 (Atrogin-1). We employed the enzyme-linked immunosorbent assay (ELISA) technique to examine pro-inflammatory factors. Additionally, we utilized quantitative real-time polymerase chain reaction (qRT-PCR) to analyze genes associated with cartilage regeneration. Synovial inflammation and cartilage damage were evaluated through hematoxylin-eosin staining. Furthermore, we employed Masson's trichrome staining and Alcian blue staining to analyze cartilage damage.

RESULTS

The decreased expression of PGC-1α in skeletal muscle in patients with OA is correlated with the severity of OA. In the rabbit PTOA model, TRE following joint distraction inhibited the expressions of muscle wasting genes, including Atrogin-1 and muscle ring finger 1 (MuRF1), as well as inflammatory factors such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in skeletal muscle, potentially through the activation of PGC-1α. Concurrently, the production of IL-1β, IL-6, TNF-α, nitric oxide (NO), and malondialdehyde (MDA) in the synovial fluid was down-regulated, while the expression of type II collagen (Col2a1), Aggrecan (AGN), SRY-box 9 (SOX9) in the cartilage, and superoxide dismutase (SOD) in the synovial fluid was up-regulated. Additionally, histological staining results demonstrated that TRE after joint distraction reduced cartilage degeneration, leading to a significant decrease in OARSI scores.TRE following joint distraction could activate PGC-1α, inhibit Atrogin-1 expression in skeletal muscle, and reduce C-telopeptides of type II collagen (CTX-II) in the blood compared to joint distraction alone.

CONCLUSION

Following joint distraction, TRE might promote the activation of PGC-1α in skeletal muscle during PTOA progression to exert anti-inflammatory effects in skeletal muscle and joint cavity, thereby inhibiting muscle wasting and promoting cartilage regeneration, making it a potential therapeutic intervention for treating PTOA.

Loss of HNRNPU in Skeletal Muscle Increases Intramuscular Infiltration of Ly6C Positive Cells, leading to Muscle Atrophy through Activation of NF-κB Signaling

Heterogeneous nuclear ribonucleoprotein U (hnRNPU) is known to play multiple biological roles by regulating transcriptional expression, RNA splicing, RNA stability, and chromatin structure in a tissue-dependent manner. The role of hnRNPU in skeletal muscle development and maintenance has not been previously evaluated. In this study, skeletal muscle specific hnRNPU knock out mice is utilized and evaluated skeletal muscle mass and immune cell infiltration through development. By 4 weeks, muscle-specific hnRNPU knockout mice revealed Ly6C+ monocyte infiltration into skeletal muscle, which preceded muscle atrophy. Canonical NF-kB signaling is activated in a myofiber-autonomous manner with hnRNPU repression. Inducible hnRNPU skeletal muscle knockout mice further demonstrated that deletion of hnRNPU in adulthood is sufficient to cause muscle atrophy, suggesting that hnRNPU's role in muscle maintenance is not during development alone. Treatment with salirasib, to inhibit proliferation of immune cells, prevents muscle atrophy in muscle-specific hnRNPU knock out mice, indicating that immune cell infiltration plays causal role in muscle atrophy of hnRNPU knock out mice. Overall, the findings suggest that loss of hnRNPU triggers muscle inflammation and activates NF-κB signaling in a cell-autonomous manner, culminating in muscle atrophy.

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.

A Retrospective Study of Biological Risk Factors Associated with Primary Knee Osteoarthritis and the Development of a Nomogram Model

Aim

A high percentage of the elderly suffer from knee osteoarthritis (KOA), which imposes a certain economic burden on them and on society as a whole. The purpose of this study is to examine the risk of KOA and to develop a KOA nomogram model that can timely intervene in this disease to decrease patient psychological burdens.

Methods

Data was collected from patients with KOA and without KOA at our hospital from February 2021 to February 2023. Initially, a comparison was conducted between the variables, identifying statistical differences between the two groups. Subsequently, the risk of KOA was evaluated using the Least Absolute Shrinkage and Selection Operator method and multivariate logistic regression to determine the most effective predictive index and develop a prediction model. The examination of the disease risk prediction model in KOA includes the corresponding nomogram, which encompasses various potential predictors. The assessment of disease risk entails the application of various metrics, including the consistency index (C index), the area under the curve (AUC) of the receiver operating characteristic curve, the calibration chart, the GiViTi calibration band, and the model for predicting KOA. Furthermore, the potential clinical significance of the model is explored through decision curve analysis (DCA) and clinical influence curve analysis.

Results

The study included a total of 582 patients, consisting of 392 patients with KOA and 190 patients without KOA. The nomogram utilized age, haematocrit, platelet count, apolipoprotein a1, potassium, magnesium, hydroxybutyrate dehydrogenase, creatine kinase, and estimated glomerular filtration rate as predictors. The C index, AUC, calibration plot, Giviti calibration band, DCA and clinical influence KOA indicated the ability of nomogram model to differentiate KOA.

Conclusion

Using nomogram based on disease risk, high-risk KOA can be identified directly without imaging.

Identification of genes and key pathways underlying the pathophysiological association between sarcopenia and chronic obstructive pulmonary disease

PURPOSE

Chronic obstructive pulmonary disease (COPD) patients are likely to develop sarcopenia, while the exact mechanism underlying the association between sarcopenia and COPD is still not clear. This cohort study aims to explore the genes, signaling pathways, and transcription factors (TFs) that are related to the molecular pathogenesis of sarcopenia and COPD.

METHODS

According to the strict inclusion criteria, two gene sets (GSE8479 for sarcopenia and GSE76925 for COPD) were obtained from the Gene Expression Omnibus (GEO) platform. Overlapping differentially expressed genes (DEGs) in sarcopenia and COPD were detected, and comprehensive bioinformatics analysis was conducted, including functional annotation, enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), construction of a protein-protein interaction (PPI) network, co-expression analysis, identification and validation of hub genes, and TFs prediction and verification.

RESULTS

In total, 118 downregulated and 92 upregulated common DEGs were detected. Functional analysis revealed that potential pathogenesis involves oxidoreductase activity and ferroptosis. Thirty hub genes were detected, and ATP metabolic process and oxidative phosphorylation were identified to be closely related to the hub genes. Validation analysis revealed that SAA1, C3, and ACSS2 were significantly upregulated, whereas ATF4, PPARGC1A, and MCTS1 were markedly downregulated in both sarcopenia and COPD. In addition, six TFs (NFKB1, RELA, IRF7, SP1, MYC, and JUN) were identified to regulate the expression of these genes, and SAA1 was found to be coregulated by NFKB1 and RELA.

CONCLUSION

This study uncovers potential common mechanisms of COPD complicated by sarcopenia. The hub gene SAA1 and the NF-κB signaling pathway could be involved, and oxidative phosphorylation and ferroptosis might be important contributors to this comorbidity.

Genetic causality and site-specific relationship between sarcopenia and osteoarthritis: a bidirectional Mendelian randomization study

Background: Previous studies demonstrated a controversial relationship between sarcopenia (SP) and osteoarthritis (OA) and their genetic causality is unclear. Thus, we conducted a Mendelian randomization (MR) analysis to evaluate the possible causal association between sarcopenia-related traits (appendicular lean mass (ALM), grip strength, usual walking pace) and OA. Method: We used pooled genetic data from the UK Biobank for ALM(n = 450,243), left-hand grip strength (n = 461,026), right-hand grip strength (n = 461,089) and usual walking pace (n = 459,915). Moreover, summary statistics for OA were obtained from the latest study conducted by the Genetics of Osteoarthritis Consortium, including all OA (n = 826,690), hand OA (n = 303,7782), hip OA (n = 353,388) and knee OA (n = 396,054). The primary method for estimating causal effects was the inverse-variance weighted (IVW) method, with the utilizing of false discovery rate adjusted p values (P FDR). Additional MR methods such as MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO), weighted median were employed as supplementary analyses. Results: We discovered ALM (odds ratio (OR) = 1.103, 95% confidence interval (CI) = 1.052-1.156, P FDR = 2.87E-04), hand grip strength (left, IVW OR = 0.823, 95% CI = 0.712 to 0.952, P FDR = 0.020; right, OR = 0.826, 95% CI = 0.718 to 0.950, P FDR = 0.020), and usual walking pace (OR = 0.339, 95% CI = 0.204 to 0.564, P FDR = 2.38E-04) were causally associated with OA risk. In the reverse MR analysis, we identified a causal effect of OA on ALM (β = -0.258, 95% CI = -0.369 to 0.146, P FDR = 0.6.07E-06), grip strength (left, β = -0.064, 95% CI = -0.104 to 0.024, P FDR = 0.002; right, β = -0.055, 95% CI = -0.095 to 0.014, P FDR = 0.008), and usual walking pace (β = -0.104, 95% CI = -0.147 to 0.061, P FDR = 1.61E-05). Conclusion: This present study suggests an obvious causality of SP on OA, with condition exhibiting site-specific effects, while evidence was also provided for the causal effect of OA on SP.

The role of ultra-processed food consumption in protein-energy wasting and sarcopenia development in patients with chronic kidney diseases

BACKGROUND

The effect of ultra-processed foods (UPFs) on chronic kidney disease (CKD) has been studied in some studies. The present study aimed to investigate the association between UPF consumption and the risk of protein-energy wasting (PEW) and sarcopenia in patients with CKD in the Iranian population.

METHODS

The current cross-sectional study included 110 patients with CKD referred to two clinics in Shiraz, Iran. The International Society of Renal Nutrition and Metabolism (ISRNM) criteria and the Asian Working Group for Sarcopenia (AWGS) guideline were considered for the diagnosis of PEW and sarcopenia, respectively. The valid semi-quantitative food frequency questionnaire was used to assess participants' dietary intake. The logistic regression was used to examine the association of UPFs with PEW and sarcopenia.

RESULTS

We observed no significant association between sarcopenia and PEW with UPFs in the crude model. After adjusting for confounders, we observed a significantly higher odds of sarcopenia in the upper versus lower median of UPF intake (odds ratio (OR) = 3.59, 95% confidence interval (CI): 1.02-12.62, P = 0.046).

CONCLUSIONS

Our findings suggest a positive relationship between UPF intake and sarcopenia among CKD patients. Therefore, reducing the intake of UPFs may decrease the odds of sarcopenia in patients suffering from CKD.

Joint pressure stimuli increase quadriceps strength and neuromuscular activity in patients with knee osteoarthritis

The study investigated the effects of periarticular knee pressure stimuli on quadriceps strength and neuromuscular activity in subjects with knee osteoarthritis. Twenty-five subjects with knee osteoarthritis and 25 age-matched healthy controls performed maximal voluntary knee extension tasks on an isometric dynamometer. Three different pressure stimuli (no-pressure, 60-mmHg, 120-mmHg) were applied using a sphygmomanometer via the cuff covering the knee joint. Peak torque and root-mean-square peak of rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) were collected and normalized for the no-pressure condition (nTorque-peak and nRMS-peak). Normalized Torque-peak increased from no-pressure to 60-mmHg and 120-mmHg in patients, which revealed higher nTorque-peak during 60-mmHg (MD: 10.9%, IC95: 1.8%, 20.1%, p = 0.020) and 120-mmHg (MD: 16.0%, IC95: 4.4%, 27.6%, p = 0.008) conditions than healthy subjects. Moreover, nRMS-peak increased from no-pressure to 60-mmHg for RF, from no-pressure to 120-mmHg for RF, VM and VL, and from 60-mmHg to 120 mm-Hg for VL in patients. Patients revealed higher nRMS-peak of RF and VM during 60-mmHg and 120-mmHg conditions than healthy subjects. Periarticular knee pressure stimuli enhanced quadriceps strength and neuromuscular activity in subjects with knee osteoarthritis. This approach may represent a new strength training modality in patients with neuromuscular activation deficits for knee osteoarthritis.

Quadriceps Strength, Postural Stability, and Pain Mediation in Bilateral Knee Osteoarthritis: A Comparative Analysis with Healthy Controls

Bilateral knee osteoarthritis (OA) poses significant challenges to individuals' functional abilities, including quadriceps strength, postural stability, and pain perception. Understanding the complex relationships among these factors is crucial for enhancing knee OA management strategies. The primary objective of this research is to evaluate and draw comparisons between the strength of the quadriceps and the level of postural stability in two distinct groups: individuals afflicted with bilateral knee OA and those who are healthy. Furthermore, the study seeks to examine the potential correlation between the strength of the quadriceps and the level of postural stability in individuals with knee OA. In addition to this, an investigation into the potential mediating effect of pain on the relationship between these physiological factors will also be conducted. A total of 95 participants with bilateral knee OA and 95 healthy controls were recruited. Quadriceps strength was assessed using dynamometry and postural stability was evaluated through anterior-posterior and medial-lateral sway measurements along with the ellipse area using a force plate. Pain levels were measured using the Visual Analog Scale (VAS). Mediation analysis was employed to explore the role of pain in mediating the relationship between quadriceps strength and postural stability. Statistical analyses included t-tests, Pearson correlation coefficients, and mediation analysis. Knee OA participants exhibited significantly lower quadriceps strength (1.08 Nm/kg ± 0.54) compared to controls (1.54 Nm/kg ± 0.57, p < 0.001). They also demonstrated compromised postural stability with increased anterior-posterior sway (9.86 mm ± 3.017 vs. 2.98 mm ± 1.12, p < 0.001), medial-lateral sway (7.87 mm ± 2.23 vs. 3.12 mm ± 1.34, p < 0.001), and larger ellipse area (935.75 mm2 ± 172.56 vs. 436.19 mm2 ± 135.48, p < 0.001). Negative correlations were observed between quadriceps strength and postural stability variables (r = from -0.43 to -0.51, p < 0.001). Pain significantly mediated the relationship between quadriceps strength and postural stability variables (p < 0.05). This study highlights the associations between quadriceps strength, postural stability, and pain mediation in individuals with bilateral knee OA. Our findings emphasize the need for targeted interventions addressing quadriceps weakness and compromised postural stability. Additionally, the mediation effect of pain underscores the complexity of these relationships, offering insights for more effective management strategies.

Sarcopenia and Sarcopenic Obesity and Osteoarthritis: A Discussion among Muscles, Fat, Bones, and Aging

Aging is a physical procedure for people and nature. Our aging world is expanding because of the life span extension. Aging has a crucial relationship with our body composition (muscles, bones, and adipose tissue), which is characterized by an increase in fat mass and a gradual decrease in muscle mass and strength and bone density. These alterations affect physical performance and impact quality of life enhancing the risk for non-communicable diseases, immobilization, and disability. As far we know, osteoarthritis of lower limbs, sarcopenic obesity, and muscle mass and/or strength loss are treated separately. However, bones, muscles, adipose tissue, and aging appear to have an interconnection through a dialogue as they talk to each other. Health disorders are coming into the surface when this relationship is disrupted. The aim of our study is to search deeper into this interconnection, so that when adipose tissue increases, we have to take a look into the condition of muscle mass, bone, and connective tissue and vice versa, through the assessment of physical performance. Consequently, the triad muscle-bone-adipose tissue disorders by aging should be treated as a single entity.

Differential angiogenesis of bone and muscle endothelium in aging and inflammatory processes

Different tissues have different endothelial features, however, the implications of this heterogeneity in pathological responses are not clear yet. "Inflamm-aging" has been hypothesized as a possible trigger of diseases, including osteoarthritis (OA) and sarcopenia, often present in the same patient. To highlight a possible contribution of organ-specific endothelial cells (ECs), we compare ECs derived from bone and skeletal muscle of the same OA patients. OA bone ECs show a pro-inflammatory signature and higher angiogenic sprouting as compared to muscle ECs, in control conditions and stimulated with TNFα. Furthermore, growth of muscle but not bone ECs decreases with increasing patient age and systemic inflammation. Overall, our data demonstrate that inflammatory conditions in OA patients differently affect bone and muscle ECs, suggesting that inflammatory processes increase angiogenesis in subchondral bone while associated systemic low-grade inflammation impairs angiogenesis in muscle, possibly highlighting a vascular trigger linking OA and sarcopenia.

Enhanced echo intensity in vastus medialis is associated with worsening of functional disabilities and symptoms in patients with knee osteoarthritis: a 3 years longitudinal study

Patients with knee osteoarthritis (OA) experience muscle quality loss, and is characterized by the enhanced echo intensity (EI) of the vastus medialis (VM) muscles and a high extracellular water-to-intracellular water (ECW/ICW) ratio of the thigh. This study aimed to elucidate the association between muscle degeneration and the worsening of functional disabilities and symptoms in patients with KOA over 3 years duration. Thirty-three patients with KOA who completed follow-up over 3 years were included in the analysis. The knee scoring system (KSS) was used to evaluate the functional abilities and symptoms. Based on the 3 years change in KSS scores, patients were classified into progressive or non-progressive groups. Muscle thickness (MT) and EI of the VM were determined using ultrasonography. The ECW/ICW ratio was measured using segmental-bioelectrical impedance spectroscopy. Multivariable logistic regression analyses were conducted with the groups as the dependent variables and VM-MT, VM-EI, and ECW/ICW ratio at baseline as independent variables, including potential confounders. Thirteen (39.4%) patients showed progressive features. VM-EI at baseline was significantly associated with the progression of functional disabilities (adjusted odds ratio [OR] 1.24; 95% confidence interval [CI] 1.03 − 1.50) and symptoms (adjusted OR 1.13; 95% CI 1.01 − 1.25). Enhanced VM-EI was associated with the worsening of functional disabilities and symptoms in patients with KOA over a period of 3 years. Therefore, the assessment of VM-EI using ultrasonography is a useful indicator for predicting the future worsening of KOA.

Influence of COPD systemic environment on the myogenic function of muscle precursor cells in vitro

Background:

Loss of muscle mass and function are well-recognized systemic manifestations of chronic obstructive pulmonary disease (COPD). Acute exacerbations, in turn, significantly contribute to upgrade these systemic comorbidities. Involvement of myogenic precursors in muscle mass maintenance and recovery is poorly understood. The aim of the present study was to investigate the effects of the vascular systemic environment from stable and exacerbated COPD patients on the myogenic behavior of human muscle precursor cells (MPC) in vitro.

Methods:

Serum from healthy controls and from stable and exacerbated COPD patients (before and after Methylprednisolone treatment) was used to stimulate human MPC cultures. Proliferation analysis was assessed through BrdU incorporation assays. MPC differentiation was examined through real-time RT-PCR, western blot and immunofluorescence analysis.

Results:

Stimulation of MPCs with serum obtained from stable COPD patients did not affect myogenic precursor cell function. The vascular systemic environment during an acute exacerbation exerted a mitotic effect on MPCs without altering myogenic differentiation outcome. After Methylprednisolone treatment of acute exacerbated COPD patients, however, the mitotic effect was further amplified, but it was followed by a deficient differentiation capacity. Moreover, these effects were prevented when cells were co-treated with the glucocorticoid receptor antagonist Mifepristone.

Conclusion:

Our findings suggest that MPC capacity is inherently preserved in COPD patients, but is compromised after systemic administration of MP. This finding strengthens the concept that glucocorticoid treatment over the long term can negatively impact myogenic stem cell fate decisions and interfere with muscle mass recovery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02203-6.

Skeletal Myosteatosis is Associated with Systemic Inflammation and a Loss of Muscle Bioenergetics in Stable COPD

Background

Common features among patients with more advanced chronic obstructive pulmonary disease (COPD) are systemic inflammation and a loss of both muscle mass and normal muscle composition. In the present study, we investigated COPD subjects to better understand how thigh muscle fat infiltration (MFI) and energy metabolism relate to each other and to clinical features of COPD with emphasis on systemic inflammation.

Methods

Thirty-two Caucasians with stable COPD were investigated using questionnaires, lung function tests, blood analysis and magnetic resonance imaging (MRI) for analysis of body- and thigh muscle composition. Bioenergetics in the resting thigh muscle, expressed as the PCr/Pi ratio, were analysed using ³¹phosphorus magnetic resonance spectroscopy (³¹P-MRS).

Results

Based on the combination of the MFI adjusted for sex (MFI_a) and the thigh fat-tissue free muscle volume, expressed as the deviation from the expected muscle volume of a matched virtual control group (FFMV_vcg), all COPD subjects displayed abnormally composed thigh muscles. Clinical features of increased COPD severity, including a decrease of blood oxygenation (r = −0.44, p < 0.05) and FEV₁/FVC ratio, reflecting airway obstruction (r = −0.53, p < 0.01) and an increase of COPD symptoms (r = 0.37, p < 0.05) and breathing frequency at rest (r = 0.41, p < 0.05), were all associated with a raise of the PCr/Pi ratio in the thigh muscle. Increased MFI_a of the thigh muscle correlated positively with markers of systemic inflammation (white blood cell count, r = 0.41, p < 0.05; fibrinogen, r = 0.44, p < 0.05), and negatively with weekly physical activity (r = −0.40, p < 0.05) and the PCr/Pi ratio in the resting thigh muscle (r = −0.41, p < 0.05).

Conclusion

The present study implies a link between systemic inflammation, excessive MFI and a loss of bioenergetics in subjects with stable COPD.

ω-3 polyunsaturated fatty acid supplementation improves postabsorptive and prandial protein metabolism in patients with chronic obstructive pulmonary disease: a randomized clinical trial

BACKGROUND

Disturbances in protein metabolism and impaired muscle health have been observed in chronic obstructive pulmonary disease (COPD). The ω-3 (n-3) PUFAs EPA and DHA are known for their anti-inflammatory and muscle health-enhancing properties.

OBJECTIVES

We examined whether daily EPA + DHA supplementation can improve daily protein homeostasis in patients with COPD by reducing postabsorptive whole-body protein breakdown (PB) and enhancing the anabolic response to feeding in a dose-dependent way.

METHODS

Normal-weight participants with moderate to severe COPD (n = 32) received daily for 4 wk, according to a randomized double-blind placebo controlled 3-group design, a high dose (3.5 g, n = 10) of EPA + DHA, a low dose (2.0 g, n = 10) of EPA + DHA, or placebo (olive oil, n = 12) via gel capsules. At pre- and postintervention, stable isotope tracers were infused to assess postabsorptive netPB [postabsorptive PB - protein synthesis (PS)] and the anabolic response (prandial netPS = prandial PS-PB) to a protein meal. In addition, muscle mass and function were measured.

RESULTS

Plasma phosphatidylcholine EPA and DHA concentrations were higher after 4 wk of supplementation in both EPA + DHA groups (P < 0.004), and there was a trend toward higher values for plasma EPA after the high compared with the low dose of EPA + DHA (P = 0.065). Postabsorptive PB was lower after 4 wk of the high dose of EPA + DHA, whereas netPB was lower independent of the dose of EPA + DHA (low dose, P = 0.037; high dose, P = 0.026). Prandial netPS was increased only after the high dose of EPA + DHA (P = 0.03). Extremity lean mass but not muscle function was increased, independent of the EPA + DHA dose (P < 0.05).

CONCLUSIONS

Daily n-3 PUFA supplementation for 4 wk induces a shift toward a positive daily protein homeostasis in patients with COPD in part in a dose-dependent way. Daily doses up to 3.5 g EPA and DHA are still well tolerated and lead to protein gain in these patients. This trial was registered at clinicaltrials.gov as NCT01624792.

Diabetic Muscular Atrophy: Molecular Mechanisms and Promising Therapies

Diabetes mellitus (DM) is a typical chronic disease that can be divided into 2 types, dependent on insulin deficiency or insulin resistance. Incidences of diabetic complications gradually increase as the disease progresses. Studies in diabetes complications have mostly focused on kidney and cardiovascular diseases, as well as neuropathy. However, DM can also cause skeletal muscle atrophy. Diabetic muscular atrophy is an unrecognized diabetic complication that can lead to quadriplegia in severe cases, seriously impacting patients' quality of life. In this review, we first identify the main molecular mechanisms of muscle atrophy from the aspects of protein degradation and synthesis signaling pathways. Then, we discuss the molecular regulatory mechanisms of diabetic muscular atrophy, and outline potential drugs and treatments in terms of insulin resistance, insulin deficiency, inflammation, oxidative stress, glucocorticoids, and other factors. It is worth noting that inflammation and oxidative stress are closely related to insulin resistance and insulin deficiency in diabetic muscular atrophy. Regulating inflammation and oxidative stress may represent another very important way to treat diabetic muscular atrophy, in addition to controlling insulin signaling. Understanding the molecular regulatory mechanism of diabetic muscular atrophy could help to reveal new treatment strategies.

Pioglitazone and Risk of Chronic Obstructive Pulmonary Disease in Patients with Type 2 Diabetes Mellitus: A Retrospective Cohort Study

Background

Pioglitazone’s effect on chronic obstructive pulmonary disease (COPD) has rarely been studied.

Purpose

This retrospective observational study investigated whether the use of pioglitazone would affect the risk of COPD in patients with type 2 diabetes mellitus.

Patients and Methods

The Taiwan’s National Health Insurance database was used to enroll 9487 matched pairs of ever users and never users of pioglitazone based on propensity score from a cohort of 350,536 patients. The enrolled patients had a new diagnosis of type 2 diabetes mellitus between 1999 and 2008 and were not having a diagnosis of COPD before January 1, 2009. They were then followed up for COPD, starting from January 1, 2009 until December 31, 2011. Diagnosis of COPD was based on the codes of 491 for chronic bronchitis and 492 for emphysema based on the International Classification of Diseases, Ninth Revision, Clinical Modification. Cox regression was used to estimate hazard ratios. The interactions between pioglitazone and COPD risk factors including pneumonia, pulmonary tuberculosis and tobacco abuse were also investigated.

Results

In 9487 never users and 9487 ever users of pioglitazone, the case numbers of incident COPD were 359 and 295, respectively. The respective incidence rates of COPD were 1484.73 and 1167.61 per 100,000 person-years. The overall hazard ratio (95% confidence interval) for COPD that compared ever to never users was 0.778 (0.667–0.908). The hazard ratios for the tertiles of cumulative duration of pioglitazone therapy (cutoffs: <11.0, 11.0–19.6 and >19.6 months) to never users were 0.904 (0.729–1.121), 0.727 (0.578–0.914) and 0.715 (0.570–0.896), respectively. No interactions between pioglitazone and COPD risk factors including pneumonia, pulmonary tuberculosis and tobacco abuse were noted.

Conclusion

Pioglitazone use is associated with a significantly lower risk of COPD.

Ultrasonic Elastography of the Rectus Femoris, a Potential Tool to Predict Sarcopenia in Patients With Chronic Obstructive Pulmonary Disease

Purpose: Skeletal muscle dysfunction is common in patients with chronic obstructive pulmonary disease (COPD) and is associated with a poor prognosis. Abnormal muscle quantity of the lower limbs is a manifestation of skeletal muscle dysfunction in patients with COPD. Shear wave ultrasound elastography (SWE) is a novel and possible tool to evaluate qualitative muscle parameters. This study explores the feasibility of SWE to measure the stiffness of the rectus femoris and evaluates its value in predicting sarcopenia in patients with COPD.

Methods: Ultrasound examination of the rectus femoris was performed to determine the mean elasticity index (SWE_mean), cross-sectional area (RF_csa), and thickness (RF_thick) using grayscale ultrasonography (US) and SWE in 53 patients with COPD and 23 age-matched non-COPD healthy controls. The serum levels of circulating biomarkers (GDF15, resistin, and TNF-α) were measured using ELISA. The definition of sarcopenia followed the guidelines from the Asian Working Group for Sarcopenia. Receiver operating characteristic (ROC) curve analysis of the SWE_mean, RF_thick, and RF_csa was used to evaluate their predictive ability for sarcopenia.

Results: The intraobserver and interobserver repeatability of SWE performance was excellent (all correlation coefficients > 0.95; p < 0.05). The SWE_mean of the rectus femoris in patients with COPD (8.98 ± 3.12 kPa) was decreased compared with that in healthy controls (17.00 ± 5.14 kPa) and decreased with advanced global initiative for chronic obstructive lung disease (GOLD) stage. Furthermore, SWE_mean was found to be independent of sex, height, and body mass, and a lower SWE_mean in patients with COPD was positively associated with reduced pulmonary function, worse physical function, poor exercise tolerance, decreased muscle strength, and worse dyspnea index score. The correlation between physical function [five-repetition sit-to-stand test (5STST)], muscle function, and SWE_mean was higher than those of RF_thick and RF_csa. In addition, SWE_mean was negatively correlated with serum GDF15 levels (r = −0.472, p < 0.001), serum resistin levels (r = −0.291, p = 0.035), and serum TNF-α levels (r = −0.433, p = 0.001). Finally, the predictive power of SWE_mean [area under the curve (AUC): 0.863] in the diagnosis of sarcopenia was higher than that of RF_thick (AUC: 0.802) and RF_csa (AUC: 0.816).

Conclusion: Compared with grayscale US, SWE was not affected by the patient’s height, weight, or BMI and better represented skeletal muscle function and physical function. Furthermore, SWE is a promising potential tool to predict sarcopenia in patients with COPD.

Skeletal muscle wasting: the estrogen side of sexual dimorphism

The importance of defining sex differences across various biological and physiological mechanisms is more pervasive now than it has been over the past 15-20 years. As the muscle biology field pushes to identify small molecules and interventions to prevent, attenuate, or even reverse muscle wasting, we must consider the effect of sex as a biological variable. It should not be assumed that a therapeutic will affect males and females with equal efficacy or equivalent target affinities under conditions where muscle wasting is observed. With that said, it is not surprising to find that we have an unclear or even a poor understanding of the effects of sex or sex hormones on muscle wasting conditions. Although recent investigations are beginning to establish experimental approaches that will allow investigators to assess the impact of sex-specific hormones on muscle wasting, the field still needs rigorous scientific tools that will allow the community to address critical hypotheses centered around sex hormones. The focus of this review is on female sex hormones, specifically estrogens, and the roles that these hormones and their receptors play in skeletal muscle wasting conditions. With the overall review goal of assembling the current knowledge in the area of sexual dimorphism driven by estrogens with an effort to provide insights to interested physiologists on necessary considerations when trying to assess models for potential sex differences in cellular and molecular mechanisms of muscle wasting.

Osteosarcopenia and trabecular bone score in patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate the prevalence of osteosarcopenia and the association of osteosarcopenia with trabecular bone score (TBS) in a group of patients with type 2 diabetes mellitus(T2DMG) compared with a paired control group (CG).

METHODS

Cross-sectional study with men and women ≥ 50 years recruited by convenience. Patients in both groups answered questionnaires and underwent evaluation of bone mineral density (BMD), handgrip strength (HGS), and TBS. The T2DMG also underwent a gait speed (GS) test. Sarcopenia was defined as low lean mass plus low HGS or GS according to the Foundation for the National Institute of Health Sarcopenia Project, and osteosarcopenia was deemed present when sarcopenia was associated with osteopenia, osteoporosis, or low-energy trauma fractures.

RESULTS

The T2DMG (n = 177) and CG (n = 146) had, respectively, mean ages of 65.1 ± 8.2 years and 68.8 ± 11.0 years and 114 (64.4%) and 80 (54.7%) women. T2DMG versus the CG had higher rates of osteosarcopenia (11.9% versus 2.14%, respectively, p = 0.010), sarcopenia (12.9% versus 5.4%, respectively, p < 0.030), and fractures (29.9% versus 18.5%, respectively, p = 0.019), and lower HGS values (24.4 ± 10.3 kg versus 30.9 ± 9.15 kg, respectively, p < 0.001), but comparable BMD values. Mean TBS values were 1.272 ± 0.11 and 1.320 ± 0.12, respectively (p = 0.001). On multivariate analysis, age, greater waist circumference, fractures, and osteoporosis increased the risk of degraded TBS. Osteosarcopenia was associated with diabetes complications (p = 0.03), calcium and vitamin D supplementation (p = 0.01), and all components of osteosarcopenia diagnosis (p < 0.05).

CONCLUSION

Compared with the CG, the T2DMG had a higher prevalence of osteosarcopenia, sarcopenia, and fractures and lower bone quality assessed by TBS.

Are oxidative stress biomarkers and respiratory muscles strength associated with COPD-related sarcopenia in older adults?

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) often present with sarcopenia, a condition marked by the loss in quality and quantity of muscle mass that can affect the strength of respiratory muscles. COPD and sarcopenia are also independently associated with oxidative stress. This study aimed to investigate whether oxidative stress biomarkers and respiratory muscle strength are associated with sarcopenia in COPD patients.

METHODS

In a cross-sectional study, 86 elderly subjects, including subjects with and without COPD were assessed for body composition, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) and oxidative stress parameters [substances reactive to thiobarbituric acid (TBARS), ferric reducing ability of plasma (FRAP), superoxide dismutase (SOD), and catalase (CAT)].

RESULTS

The sample was mainly composed by males (72.1%) and eutrophic subjects. COPD-related sarcopenia was evidenced in 51.1% (22/43) of subjects with COPD. The highest TBARS and CAT, and lower MIP and MEP were associated with a high probability of having COPD-related sarcopenia. In the multivariate analysis, TBARS (OR: 4.89, 95% CI 1.52 to 15.54, p = 0.006), CAT (OR: 1.22, 95% CI 1.03 to 1.45, p = 0.020) and MEP (OR: 0.97, 95% CI 0.95 to 0.99, p = 0.020) were independent determinants of COPD-related sarcopenia.

CONCLUSION

The increase in oxidative stress-related factors and the reduction of respiratory muscle strength are associated with COPD-related sarcopenia.

Elevated serum pentosidine is independently associated with the high prevalence of sarcopenia in Chinese middle-aged and elderly men with type 2 diabetes mellitus

AIMS/INTRODUCTION

Sarcopenia has recently been recognized as another complication associated with diabetes, but its early screening still lacks clinical markers. Here, we aimed to investigate the relationship between serum levels of pentosidine, which is an advanced glycation end-product, and sarcopenia in Chinese middle-aged and elderly men with type 2 diabetes mellitus and evaluate whether pentosidine could be used as a kind of screening maker.

MATERIALS AND METHODS

A total of 182 male type 2 diabetes mellitus patients aged ≥50 years were selected in the cross-sectional study for whole-body dual-energy X-ray measurement and calculating the appendicular skeletal muscle mass index. At the same time, handgrip strength and gait speed were assessed. According to the updated consensus on Asian sarcopenia in 2019, the patients were divided into the sarcopenia group (n = 83) and non-sarcopenia group (n = 99). Serum pentosidine levels in the two groups were detected using enzyme-linked immunosorbent assay.

RESULTS

Serum pentosidine was significantly higher in the sarcopenia group (191.27 pmol/mL) than in the non-sarcopenia group (34.93 pmol/mL). Serum pentosidine was negatively correlated with appendicular skeletal muscle mass index and handgrip strength (r = -0.30 and -0.25, respectively; P < 0.05), but not gait speed. The prevalence of sarcopenia increased as the quartile of serum pentosidine increased (P < 0.05). The association between pentosidine and the prevalence of sarcopenia was still significant after additional adjustments (odds ratio 1.01, P < 0.05).

CONCLUSIONS

Pentosidine is an independent risk factor for sarcopenia in Chinese middle-aged and elderly men with type 2 diabetes mellitus. The detection of serum pentosidine levels in clinics might be helpful for the monitoring of type 2 diabetes mellitus complicated with sarcopenia.

Cannabinoid receptor 1 expression is higher in muscle of old vs. young males, and increases upon resistance exercise in older adults

Aged skeletal muscle undergoes metabolic and structural alterations eventually resulting in a loss of muscle strength and mass, i.e. age-related sarcopenia. Therefore, novel targets for muscle growth purposes in elderly are needed. Here, we explored the role of the cannabinoid system in muscle plasticity through the expression of muscle cannabinoid receptors (CBs) in young and old humans. The CB1 expression was higher (+ 25%; p = 0.04) in muscle of old (≥ 65 years) vs. young adults (20-27 years), whereas CB2 was not differently expressed. Furthermore, resistance exercise tended to increase the CB1 (+ 11%; p = 0.055) and CB2 (+ 37%; p = 0.066) expression in muscle of older adults. Interestingly, increases in the expression of CB2 following resistance exercise positively correlated with changes in key mechanisms of muscle homeostasis, such as catabolism (FOXO3a) and regenerative capacity (Pax7, MyoD). This study for the first time shows that CB1 is differentially expressed with aging and that changes in CB2 expression upon resistance exercise training correlate with changes in mediators that play a central role in muscle plasticity. These data confirm earlier work in cells and mice showing that the cannabinoid system might orchestrate muscle growth, which is an incentive to further explore CB-based strategies that might counteract sarcopenia.

Sarcopenia: Etiology, Nutritional Approaches, and miRNAs

Sarcopenia, an age-related decline in skeletal muscle mass and function, dramatically affects the quality of life. Although there is a consensus that sarcopenia is a multifactorial syndrome, the etiology and underlying mechanisms are not yet delineated. Moreover, research about nutritional interventions to prevent the development of sarcopenia is mainly focused on the amount and quality of protein intake. The impact of several nutrition strategies that consider timing of food intake, anti-inflammatory nutrients, metabolic control, and the role of mitochondrial function on the progression of sarcopenia is not fully understood. This narrative review summarizes the metabolic background of this phenomenon and proposes an integral nutritional approach (including dietary supplements such as creatine monohydrate) to target potential molecular pathways that may affect reduce or ameliorate the adverse effects of sarcopenia. Lastly, miRNAs, in particular those produced by skeletal muscle (MyomiR), might represent a valid tool to evaluate sarcopenia progression as a potential rapid and early biomarker for diagnosis and characterization.

Does the Interaction between Local and Systemic Inflammation Provide a Link from Psychology and Lifestyle to Tissue Health in Musculoskeletal Conditions?

Musculoskeletal conditions are known to involve biological, psychological, social and, often, lifestyle elements. However, these domains are generally considered in isolation from each other. This siloed approach is unlikely to be adequate to understand the complexity of these conditions and likely explains a major component of the disappointing effects of treatment. This paper presents a hypothesis that aims to provide a foundation to understand the interaction and integration between these domains. We propose a hypothesis that provides a plausible link between psychology and lifestyle factors with tissue level effects (such as connective tissue dysregulation/accumulation) in musculoskeletal conditions that is founded on understanding the molecular basis for interaction between systemic and local inflammation. The hypothesis provides plausible and testable links between mind and body, for which empirical evidence can be found for many aspects. We present this hypothesis from the perspective of connective tissue biology and pathology (fibrosis), the role of inflammation locally (tissue level), and how this inflammation is shaped by systemic inflammation through bidirectional pathways, and various psychological and lifestyle factors via their influence on systemic inflammation. This hypothesis provides a foundation for new consideration of the development and refinement of personalized multidimensional treatments for individuals with musculoskeletal conditions.

Enhanced echo intensity and a higher extracellular water-to-intracellular water ratio are helpful clinical signs for detecting muscle degeneration in patients with knee osteoarthritis

OBJECTIVES

Enhanced muscle echo intensity (EI) with ultrasound imaging and a higher extracellular water-to-intracellular water (ECW/ICW) ratio with segmental-bioelectrical impedance spectroscopy (S-BIS) represent muscle quality loss. This study aimed to clarify quadriceps muscle degeneration characteristics, focusing on muscle quality changes in patients with knee osteoarthritis (OA).

METHOD

Forty-one women with knee OA (mean age, 71.4±6.0 years) and 27 healthy women (mean age, 75.6±4.9 years) participated. Ultrasonography was used to evaluate the muscle thickness (MT) and the EI of each quadriceps compartment. The ECW/ICW ratio was obtained by S-BIS. MT, EI, and ECW/ICW ratio differences between the two groups were tested using univariate analysis of variance, adjusting for age and body mass index. Logistic regression analyses were performed with the group as the dependent variable, and the MT and EI of the vastus medialis (VM) and the ECW/ICW ratio as independent variables.

RESULTS

Patients with knee OA had a significant decrease in VM MT, enhanced VM, and vastus intermedius EIs and a higher ECW/ICW ratio compared with healthy participants. Logistic regression analysis showed that the VM EI (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.06-1.35) and the ECW/ICW ratio were independently associated with knee OA (OR, 1.19; 95% CI, 1.00-1.42).

CONCLUSIONS

VM EI and the ECW/ICW ratio, rather than VM MT, characterised quadriceps muscle degeneration in patients with knee OA. Therefore, enhanced EI and a higher ECW/ICW ratio are helpful clinical signs for detecting muscle degeneration in patients with knee OA. Key Points •Echo intensity (EI) of the vastus medialis and the extracellular-to-intracellular water (ECW/ICW) ratio significantly increased in patients with knee osteoarthritis OA). •Enhanced EI and a higher ECW/ICW ratio are useful clinical signs for detecting muscle degeneration in patients with knee OA.

Omega-3 Supplementation Improves Isometric Strength But Not Muscle Anabolic and Catabolic Signaling in Response to Resistance Exercise in Healthy Older Adults

Old skeletal muscle exhibits decreased anabolic sensitivity, eventually contributing to muscle wasting. Besides anabolism, also muscle inflammation and catabolism are critical players in regulating the old skeletal muscle's sensitivity. Omega-3 fatty acids (ω-3) are an interesting candidate to reverse anabolic insensitivity via anabolic actions. Yet, it remains unknown whether ω-3 also attenuates muscle inflammation and catabolism. The present study investigates the effect of ω-3 supplementation on muscle inflammation and metabolism (anabolism/catabolism) upon resistance exercise (RE). Twenty-three older adults (65-84 years; 8♀) were randomized to receive ω-3 (~3 g/d) or corn oil (placebo [PLAC]) and engaged in a 12-week RE program (3×/wk). Before and after intervention, muscle volume, strength, and systemic inflammation were assessed, and muscle biopsies were analyzed for markers of anabolism, catabolism, and inflammation. Isometric knee-extensor strength increased in ω-3 (+12.2%), but not in PLAC (-1.4%; pinteraction = .015), whereas leg press strength improved in both conditions (+27.1%; ptime < .001). RE, but not ω-3, decreased inflammatory (p65NF-κB) and catabolic (FOXO1, LC3b) markers, and improved muscle quality. Yet, muscle volume remained unaffected by RE and ω-3. Accordingly, muscle anabolism (mTORC1) and plasma C-reactive protein remained unchanged by RE and ω-3, whereas serum IL-6 tended to decrease in ω-3 (pinteraction = .07). These results show that, despite no changes in muscle volume, RE-induced gains in isometric strength can be further enhanced by ω-3. However, ω-3 did not improve RE-induced beneficial catabolic or inflammatory adaptations. Irrespective of muscle volume, gains in strength (primary criterion for sarcopenia) might be explained by changes in muscle quality due to muscle inflammatory or catabolic signaling.

Voluntary exercise does not improve muscular properties or functional capacity during C26-induced cancer cachexia in mice

Exercise training is considered as a potential intervention to counteract muscle degeneration in cancer cachexia. However, evidence to support such intervention is equivocal. Therefore, we investigated the effect of exercise training, i.e. voluntary wheel running, on muscle wasting, functional capacity, fiber type composition and vascularization during experimental cancer cachexia in mice. Balb/c mice were injected with PBS (CON) or C26 colon carcinoma cells to induce cancer cachexia (C26). Mice had free access to a running wheel in their home cage (CON_EX and C26_EX, n = 8-9) or were sedentary (CON_S and C26_S, n = 8-9). Mice were sacrificed 18 days upon tumor cell injection. Immunohistochemical analyes were performed on m. gastrocnemius and quadriceps, and ex vivo contractile properties were assessed in m. soleus and extensor digitorum longus (EDL). Compared with CON, C26 mice exhibited body weight loss (~ 20 %), muscle atrophy (~ 25 %), reduced grip strength (~ 25 %), and lower twitch and tetanic force (~ 20 %) production in EDL but not in m. soleus. Furthermore, muscle of C26 mice were characterizd by a slow-to-fast fiber type shift (type IIx fibers: +57 %) and increased capillary density (~ 30 %). In C26 mice, wheel running affect neither body weight loss, nor muscle atrophy or functional capacity, nor inhibited tumor growth. However, wheel running induced a type IIb to type IIa fiber shift in m. quadriceps from both CON and C26, but not in m. gastrocnemius. Wheel running does not exacerbate muscular degeneration in cachexic mice, but, when voluntary, is insufficient to improve the muscle phenotype.

Role of acute exacerbations in skeletal muscle impairment in COPD

Introduction: Muscle impairments are prevalent in COPD and have adverse clinical implications in terms of physical performance capacity, disease burden, quality of life and even mortality. During acute exacerbations of COPD (AECOPDs) the respiratory symptoms worsen and this might also apply to the muscle impairments. Areas covered: This report includes a review of both clinical and pre-clinical peer-reviewed literature of the past 20 years found in PubMed providing a comprehensive view on the role of AECOPD in muscle dysfunction in COPD, the putative underlying mechanisms and the treatment perspectives. Expert opinion: The contribution of AECOPD and its recurrent nature to muscle impairment in COPD cannot be ignored and can be attributed to the acutely intensifying and converging disease-related drivers of muscle deterioration, in particular disuse, systemic inflammation and corticosteroid treatment. The search for novel treatment options should focus on the AECOPD-enhanced drivers of muscle dysfunction as well as on the underlying, mainly catabolic, mechanisms. Considering the impact of AECOPD on muscle function, and that of muscle impairment on the recurrence of exacerbations, counteracting muscle deterioration in AECOPD provides an unprecedented therapeutic opportunity.

Photo-Oxidative Degradation Mitigated the Developmental Toxicity of Polyamide Microplastics to Zebrafish Larvae by Modulating Macrophage-Triggered Proinflammatory Responses and Apoptosis

Microplastics (MPs) are ubiquitous in the environment and pose substantial threats to the water ecosystem. However, the impact of natural aging of MPs on their toxicity has rarely been considered. This study found that visible light irradiation with hydrogen peroxide at environmentally relevant concentration for 90 days significantly altered the physicochemical properties and mitigated the toxicity of polyamide (PA) fragments to infantile zebrafish. The size of PA particles was reduced from ∼8.13 to ∼6.37 μm, and nanoparticles were produced with a maximum yield of 5.03%. The end amino groups were volatilized, and abundant oxygen-containing groups (e.g., hydroxyl and carboxyl) and carbon-centered free radicals were generated, improving the hydrophilicity and colloidal stability of degraded MPs. Compared with pristine PA, the depuration of degraded MPs mediated by multixenobiotics resistance was much quicker, leading to markedly lower bioaccumulation in fish and weaker inhibition on musculoskeletal development. By integrating transcriptomics and transgenic zebrafish [Tg(lyz:EGFP)] tests, differences in macrophages-triggered proinflammatory effects, apoptosis via IL-17 signaling pathway, and antioxidant damages were identified as the underlying mechanisms for the attenuated toxicity of degraded MPs. This work highlights the importance of natural degradation on the toxicity of MPs, which has great implications for risk assessment of MPs.

Rehabilitation Nutrition for Injury Recovery of Athletes: The Role of Macronutrient Intake

An adequate and balanced diet is of utmost importance in recovery and rehabilitation. "Rehabilitation nutrition" for injury recovery of athletes is similar to sports nutrition, except for the differences that concern the prevention of the risk or presence of sarcopenia, malnutrition, or dysphagia. Rehabilitation nutrition also aims, combined with training, to an adequate long-term nutritional status of the athlete and also in physical condition improvement, in terms of endurance and resistance. The aim of this paper is to define the proper nutrition for athletes in order to hasten their return to the sports after surgery or injury. Energy intake should be higher than the energy target in order to fight sarcopenia-that is 25-30 kcal/kg of body weight. Macro- and micro-nutrients play an important role in metabolism, energy production, hemoglobin synthesis, lean mass and bone mass maintenance, immunity, health, and protection against oxidative damage. Nutritional strategies, such as supplementation of suboptimal protein intake with leucine are feasible and effective in offsetting anabolic resistance. Thus, maintaining muscle mass, without gaining fat, becomes challenging for the injured athlete. A dietary strategy should be tailored to the athlete's needs, considering amounts, frequency, type and, most of all, protein quality. During rehabilitation, simultaneous carbohydrates and protein intake can inhibit muscle breakdown and muscle atrophy. The long-term intake of omega-3 fatty acids enhances anabolic sensitivity to amino acids; thus, it may be beneficial to the injured athlete. Adequate intakes of macronutrients can play a major role supporting athletes' anabolism.