Deciphering the underlying mechanisms of the oxidative perturbations and impaired meat quality in Wooden breast myopathy by label-free quantitative MS-based proteomics.

The study aimed to investigate biochemical mechanisms occurred in Wooden breast (WB) chicken meat, with attention to the impact on meat quality. Commercial chicken breasts were classified as Normal (N, n = 12), WB-M (moderate degree; focal hardness on cranial region, n = 12) and WB-S (severe degree; extreme and diffused hardness over the entire surface, n = 12). Samples were analyzed for physico-chemical properties, oxidative damage to lipids and proteins, and discriminating sarcoplasmic proteins by using a Q-Exactive mass spectrometer. WB meat presented impaired composition and functionality and higher levels of lipid and protein oxidation markers than N meat. The proteomic profile of WB-S presents a dynamic regulation of the relevant proteins involved in redox homeostasis, carbohydrate, protein and lipid metabolisms. Proteomics results demonstrate that the physiological and metabolic processes of muscles affected by WB myopathy are involved in combating the inflammatory process and in repairing the damaged tissue by oxidative stress.

Statin protects men but not women with HIV against loss of muscle mass, strength, and physical function: a pilot study.

Statins are cholesterol-lowering drugs commonly used among people with HIV, associated with an increased risk of myopathies. Considering that cardiovascular disease, statin therapy, and sarcopenia are independently prevalent in people with HIV, clarity on the potential benefits or harms of statin therapy on muscle health is useful to provide insight into ways to maximize skeletal muscle health and minimize CVD risk in this population. We aimed to study the effects of statin therapy on strength, muscle mass, and physical function parameters in people with HIV. This was a pilot cross-sectional study. People with HIV on continuous statin therapy (n = 52) were paired 1:1 according to age (people with HIV 53.9 ± 8.2 and people with HIV on statins 53.9 ± 8.4 years), sex, body mass index (Body mass index, people with HIV 28.6 ± 5.3 and people with HIV on statins 28.8 ± 6.3 kg/m2), and race with people with HIV not using statin (n = 52). Participants were evaluated for muscle strength (i.e. handgrip strength), lean and fat body mass (using bioelectric impedance analysis), and physical function (i.e. Short Physical Performance Battery-SPPB). Isokinetic strength and appendicular lean mass (using dual-energy X-ray absorptiometry), more accurate strength and body composition measures, were determined in 38% of the participants. Overall, statin usage does not exacerbated loss of muscle strength (32.2 ± 11.5 vs. 30.3 ± 9.6 kg, p > 0.05) muscle mass (7.6 ± 1.8 vs. 7.7 ± 1.1 kg/m2, p > 0.05), and impaired physical performance (10.1 ± 1.8 vs. 9.7 ± 2.1 points, p > 0.05) of PLWH. When analyzed by sex, men living with HIV on statins usage presented higher appendicular muscle mass (28.4 ± 3.1 vs. 26.2 ± 4.9 kg, p < 0.05) handgrip strength (42.1 ± 8.8 vs. 37.1 ± 8.3 kg, p < 0.05) and physical function through SPPB score (10.9 ± 1.3 vs. 9.5 ± 2.1, p < 0.05) than men living with HIV not on statins treatment. The same protection was not observed in women. This data was demonstrated when muscle mass and strength were determined clinically (i.e. handgrip strength and electrical impedance) and when more precise laboratory measurements of muscle mass and strength were conducted (i.e. isokinetic strength and DXA scans). Statin does not exacerbate muscle wasting, strength loss, or muscle dysfunction among people with HIV. Indeed, statins may protect men, but not woman with HIV against HIV and antiretroviral therapy-induced loss of muscle mass and strength.

Peripheral and respiratory muscle impairment during murine acute lung injury.

Acute respiratory distress syndrome is associated with skeletal muscle compromise, which decreases survival and impairs functional capacity. A comparative analysis of peripheral and respiratory muscles' atrophy and dysfunction in acute lung injury (ALI) has not been performed. We aimed to evaluate diaphragmatic and peripheral muscle mass and contractility in an ALI animal model. ALI was induced in C57BL/6 mice by intratracheal lipopolysaccharides instillation. Muscle mass and in vitro contractility were evaluated at different time points in hindlimb soleus (slow-twitch) and extensor digitorum longus (EDL, fast-twitch), as well as in the main respiratory muscle diaphragm. Myogenic precursor satellite cell-specific transcription factor Pax7 expression was determined by Western blot. Lung injury was associated with atrophy of the three studied muscles, although it was more pronounced and persistent in the diaphragm. Specific contractility was reduced during lung injury in EDL muscle but restored by the time lung injury has resolved. Specific force was not affected in soleus and diaphragm. A persistent increase in Pax7 expression was detected in diaphragm and EDL muscles after induction of ALI, but not in soleus muscle. Different peripheral and respiratory skeletal muscles are distinctly affected during the course of ALI. Each of the studied muscles presented a unique pattern in terms of atrophy development, contractile dysfunction and Pax7 expression.

The functional and molecular effects of problematic alcohol consumption on skeletal muscle: a focus on athletic performance.

Background: Chronic alcohol misuse is associated with alcoholic myopathy, characterized by skeletal muscle weakness and atrophy. Moreover, there is evidence that sports-related people seem to exhibit a greater prevalence of problematic alcohol consumption, especially binge drinking (BD), which might not cause alcoholic myopathy but can negatively impact muscle function and amateur and professional athletic performance.Objective: To review the literature concerning the effects of alcohol consumption on skeletal muscle function and structure that can affect muscle performance.Methodology: We examined the currently available literature (PubMed, Google Scholars) to develop a narrative review summarizing the knowledge about the effects of alcohol on skeletal muscle function and exercise performance, obtained from studies in human beings and animal models for problematic alcohol consumption.Results: Exercise- and sport-based studies indicate that alcohol consumption can negatively affect muscle recovery after vigorous exercise, especially in men, while women seem less affected. Clinical studies and pre-clinical laboratory research have led to the knowledge of some of the mechanisms involved in alcohol-related muscle dysfunction, including an imbalance between anabolic and catabolic pathways, reduced regeneration, increased inflammation and fibrosis, and deficiencies in energetic balance and mitochondrial function. These pathological features can appear not only under chronic alcohol misuse but also in other alcohol consumption patterns.Conclusions: Most laboratory-based studies use chronic or acute alcohol exposure, while episodic BD, the most common drinking pattern in amateur and professional athletes, is underrepresented. Nevertheless, alcohol consumption negatively affects skeletal muscle health through different mechanisms, which collectively might contribute to reduced sports performance.

Evidence that Oxidative Disbalance and Mitochondrial Dysfunction are Involved in the Pathophysiology of Fatty Acid Oxidation Disorders.

Mitochondrial fatty acid ß-oxidation disorders (FAODs) are a group of about 20 diseases which are caused by specific mutations in genes that codify proteins or enzymes involved in the fatty acid transport and mitochondrial ß-oxidation. As a consequence of these inherited metabolic defects, fatty acids can not be used as an appropriate energetic source during special conditions, such as prolonged fasting, exercise or other catabolic states. Therefore, patients usually present hepatopathy, cardiomyopathy, severe skeletal myopathy and neuropathy, besides biochemical features like hypoketotic hypoglycemia, metabolic acidosis, hypotony and hyperammonemia. This set of symptoms seems to be related not only with the energy deficiency, but also with toxic effects provoked by fatty acids and carnitine derivatives accumulated in the tissues of the patients. The understanding of the mechanisms by which these metabolites provoke tissue injury in FAODs is crucial for the developmental of novel therapeutic strategies that promote increased life expectancy, as well as improved life quality for patients. In this sense, the objective of this review is to present evidence from the scientific literature on the role of oxidative damage and mitochondrial dysfunction in the pathogenesis of the most prevalent FAODs: medium-chain acyl-CoA dehydrogenase (MCAD), long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and very long-chain acyl-CoA dehydrogenase (VLCAD) deficiencies. It is expected that the findings presented in this review, obtained from both animal model and patients studies, may contribute to a better comprehension of the pathophysiology of these diseases.

Dact1 is expressed during chicken and mouse skeletal myogenesis and modulated in human muscle diseases.

Vertebrate skeletal muscle development and repair relies on the precise control of Wnt signaling. Dact1 (Dapper/Frodo) is an important modulator of Wnt signaling, interacting with key components of the various Wnt transduction pathways. Here, we characterized Dact1 mRNA and protein expression in chicken and mouse fetal muscles in vivo and during the differentiation of chick primary and mouse C2C12 myoblasts in vitro. We also performed in silico analysis to investigate Dact1 gene expression in human myopathies, and evaluated the Dact1 protein structure to seek an explanation for the accumulation of Dact1 protein aggregates in the nuclei of myogenic cells. Our results show for the first time that in both chicken and mouse, Dact1 is expressed during myogenesis, with a strong upregulation as cells engage in terminal differentiation, cell cycle withdrawal and cell fusion. In humans, Dact1 expression was found to be altered in specific muscle pathologies, including muscular dystrophies. Our bioinformatic analyses of Dact1 proteins revealed long intrinsically disordered regions, which may underpin the ability of Dact1 to interact with its many partners in the various Wnt pathways. In addition, we found that Dact1 has strong propensity for liquid-liquid phase separation, a feature that explains its ability to form nuclear aggregates and points to a possible role as a molecular 'on'-'off' switch. Taken together, our data suggest Dact1 as a candidate, multi-faceted regulator of amniote myogenesis with a possible pathophysiological role in human muscular diseases.

Role of Matricellular CCN Proteins in Skeletal Muscle: Focus on CCN2/CTGF and Its Regulation by Vasoactive Peptides.

The Cellular Communication Network (CCN) family of matricellular proteins comprises six proteins that share conserved structural features and play numerous biological roles. These proteins can interact with several receptors or soluble proteins, regulating cell signaling pathways in various tissues under physiological and pathological conditions. In the skeletal muscle of mammals, most of the six CCN family members are expressed during embryonic development or in adulthood. Their roles during the adult stage are related to the regulation of muscle mass and regeneration, maintaining vascularization, and the modulation of skeletal muscle fibrosis. This work reviews the CCNs proteins' role in skeletal muscle physiology and disease, focusing on skeletal muscle fibrosis and its regulation by Connective Tissue Growth factor (CCN2/CTGF). Furthermore, we review evidence on the modulation of fibrosis and CCN2/CTGF by the renin-angiotensin system and the kallikrein-kinin system of vasoactive peptides.

Pinpointing oxidative stress behind the white striping myopathy: depletion of antioxidant defenses, accretion of oxidized proteins and impaired proteostasis.

BACKGROUND: This study aimed to investigate the molecular mechanisms involved in the onset of the white striping (WS) myopathy with particular attention to the role of oxidative stress and protein oxidation in the loss of meat quality. RESULTS: It was found that WS-M (moderate degree; white stripes <1 mm thickness) and WS-S (severe degree; white stripes >1 mm thickness) breast presented higher pH, hardness, redness, lipid, and collagen content, and lower lightness than normal breast. Compared with the latter, WS-S had a more severe loss of protein thiols (70.7% less thiols than in N), reduced activity of antioxidant enzymes such as catalase (23 versus 40 U g-1 ), glutathione peroxidase (0.21 versus 0.54 U g-1 ), and superoxide dismutase (56 versus 73 U g-1 ), and consequently, had greater accretion of thiobarbituric acid reactive substances (0.64 versus 0.22 mg MDAkg-1 muscle), allysine (3.1 versus 1.9 nmol mg-1 protein) and Schiff base structures (645 versus 258 fluorescent units). The analysis of sarcoplasmic proteins revealed that muscles severely affected by the myopathy suffered a chronic impairment of physiological (upregulation of sarcoplasmic reticulum Ca2+ ATPase, sarcalumenin and calsequestrin-2) and metabolic processes (downregulation of pyruvate kinase, creatine kinase, and l-lactate dehydrogenase). CONCLUSION: The overexpression of ribonuclease / angiogenin inhibitor 1 and Kelch-like proteins in WS chicken breasts indicates altered protein turnover plausibly mediated by oxidative stress and accumulation of oxidized proteins. © 2020 Society of Chemical Industry.

Muscle Redox Signaling: Engaged in Sickness and in Health.

Even though physical activity is known to perturb the redox homeostasis and create a pro-oxidative muscular environment, robust evidence has confirmed precise, powerful, and beneficial effects of regular physical activity on health. Physical exercise can activate redox-sensitive intracellular signaling pathways via reactive oxygen species (ROS)-related pathways leading to modification of muscle function through genomic and nongenomic mechanisms. However, ROS-mediated signaling also has deleterious effects on skeletal muscle function, which has been observed in several pathological conditions, such as cancer, obesity, and diabetes, among others. One of the most challenging issues debated on this topic is that of the levels of redox signaling that promote either beneficial or harmful effects to our bodies. This Forum discusses the latest progress in muscle redox signaling with emphasis on muscle physiology and physiopathology. Antioxid. Redox Signal. 33, 539-541.

ß2 -adrenoceptor activation improves skeletal muscle autophagy in neurogenic myopathy.

ß2 -adrenoceptor agonists improve autophagy and re-establish proteostasis in cardiac cells; therefore, suggesting autophagy as a downstream effector of ß2 -adrenoceptor signaling pathway. Here, we used the pharmacological and genetic tools to determine the autophagy effect of sustained ß2 -adrenoceptor activation in rodents with neurogenic myopathy, which display impaired skeletal muscle autophagic flux. Sustained ß2 -adrenoceptor activation using Formoterol (10 µg kg-1  day-1 ), starting at the onset of neurogenic myopathy, prevents disruption of autophagic flux in skeletal muscle 14 days after sciatic nerve constriction. These changes are followed by reduction of the cytotoxic protein levels and increased skeletal muscle cross-sectional area and contractility properties. Of interest, sustained administration of Formoterol at lower concentration (1 µg kg-1  day-1 ) induces similar improvements in skeletal muscle autophagic flux and contractility properties in neurogenic myopathy, without affecting the cross-sectional area. Sustained pharmacological inhibition of autophagy using Chloroquine (50 mg kg-1  day-1 ) abolishes the beneficial effects of ß2 -adrenoceptor activation on the skeletal muscle proteostasis and contractility properties in neurogenic myopathy. Further supporting an autophagy mechanism for ß2 -adrenoceptor activation, skeletal muscle-specific deletion of ATG7 blunts the beneficial effects of ß2 -adrenoceptor on skeletal muscle proteostasis and contractility properties in neurogenic myopathy in mice. These findings suggest autophagy as a critical downstream effector of ß2 -adrenoceptor signaling pathway in skeletal muscle.

Impairment of mitochondrial bioenergetics and permeability transition induction caused by major long-chain fatty acids accumulating in VLCAD deficiency in skeletal muscle as potential pathomechanisms of myopathy.

cis-5-Tetradecenoic (cis-5) and myristic (Myr) acids predominantly accumulate in patients affected by very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. They commonly manifest myopathy with muscular pain and rhabdomyolysis, whose underlying mechanisms are poorly known. Thus, in the present study we investigated the effects of cis-5 and Myr on mitochondrial bioenergetics and Ca2+ homeostasis in rat skeletal muscle. cis-5 and Myr decreased ADP-stimulated (state 3) and CCCP-stimulated (uncoupled) respiration, especially when mitochondria were supported by NADH-linked as compared to FADH2-linked substrates. In contrast, these fatty acids increased resting respiration (state 4). Similar effects were observed in skeletal muscle fibers therefore validating the data obtained with isolated mitochondria. Furthermore, cis-5 and Myr markedly decreased mitochondrial membrane potential and Ca2+ retention capacity that were avoided by cyclosporin A plus ADP and ruthenium red, indicating that cis-5 and Myr induce mitochondrial permeability transition (MPT). Finally, docosanoic acid did not disturb mitochondrial homeostasis, indicating selective effects for Myr and cis-5. Taken together, our findings indicate that major long-chain fatty acids accumulating in VLCAD deficiency behave as metabolic inhibitors, uncouplers of oxidative phosphorylation and MPT inducers. It is presumed that these pathomechanisms contribute to the muscular symptoms and rhabdomyolysis observed in patients affected by VLCAD deficiency.

Stable reference genes for expression studies in breast muscle of normal and white striping-affected chickens.

The normalization with proper reference genes is a crucial step to obtain accurate mRNA expression levels in quantitative PCR (qPCR) studies. Therefore, in this study, 10 reference candidate genes were evaluated to determine their stability in normal pectoralis major muscle of broilers and those counterparts affected with White Striping (WS) myopathy at 42 days age. Four different tools were used for ranking the most stable genes: GeNorm, NormFinder, BestKeeper and Comparative Ct (ΔCt), and a general ranking was performed using the RankAggreg tool to select the best reference genes among all tools. From the 10 genes evaluated in the breast muscle of broilers, 8 were amplified. Most of the algorithms/tools indicated the same two genes, RPL30 and RPL5, as the most stable in the broilers breast muscle. In addition, there was agreement among the tools for the least stable genes: MRPS27, GAPDH and RPLP1 in the broilers breast muscle. Therefore, it is interesting to note that even with different tools for evaluating gene expression, there was consensus on the most and least stable genes. These results indicate that the Ribosomal protein L30 (RPL30) and Ribosomal protein L5 (RPL5) can be recommended for accurate normalization in qPCR studies with chicken pectoralis major muscle affected with White Striping and other myopathies.

Periodontal Disease Impairs Muscle Recovery by Modulating the Recruitment of Leukocytes.

The purpose of this study is to analyze the impact of periodontal disease (PD) associated with physical exercise on inflammatory mediators and muscle repair. Twenty-four Wistar rats were divided into four groups: control (SH), healthy trained (TH), sedentary with PD (SP), and trained with PD (TP). PD was induced in groups SP and TP while the trained groups performed treadmill exercises for 8 weeks. For the analysis of IL-6, IL-10, TNF-α, and leukocyte count, we collected blood samples. Cryolesions were induced in the tibialis anterior and gastrocnemius, which were analyzed for morphological changes. The presence of PD modified leukocyte counts, while exercise showed an additive role. PD increased levels of IL-6, IL-10, and TNF-α, and physical exercise changed only values of IL-10. The association between physical exercise and PD was responsible for an increased concentration of leukocytes in the region of the inflammation. Serum levels of inflammatory markers were modified by PD and, when combined with exercise, may negatively modulate inflammation. The association between PD and physical exercise showed the most significant changes in the number of inflammatory cells and may negatively influence the process of muscle repair.

Effects of mesenchymal stromal cells on type 1 diabetes mellitus rat muscles.

INTRODUCTION: Type 1 diabetes mellitus (DM) causes marked skeletal muscle atrophy. Mesenchymal stromal cells (MSC) are an attractive therapy to avoid diabetic complications because of their ability to modify the microenvironment at sites of tissue injury. The objective of this study was to evaluate the effects of MSC transplantation on muscle adaptation caused by diabetes. METHODS: DM was induced by streptozotocin (STZ), and the diabetic animals received systemic MSC transplantation. The von Frey test and footprint analysis were used to assess sensation and sensory motor performance, respectively. Tibialis anterior muscles were investigated by morphology; molecular markers atrogin-1/muscle RING-finger protein-1, nuclear factor κB/p38 mitogen-activated protein kinase, tumor necrosis-like weak inducer of apoptosis/fibroblast growth factor-inducible 14, myostatin, myogenic differentiation 1, and insulin-like growth factor 1 were also assessed. RESULTS: MSC transplantation improved sensation and walking performance and also decreased muscle fibrosis in DM rats by modulating atrogenes but did not prevent muscle atrophy. DISCUSSION: MSCs can reduce muscle and functional complications that result from type 1 DM in rats. Muscle Nerve 58: 583-591, 2018.

Metabolite accumulation in VLCAD deficiency markedly disrupts mitochondrial bioenergetics and Ca2+ homeostasis in the heart.

We studied the effects of the major long-chain fatty acids accumulating in very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency, namely cis-5-tetradecenoic acid (Cis-5) and myristic acid (Myr), on important mitochondrial functions in isolated mitochondria from cardiac fibers and cardiomyocytes of juvenile rats. Cis-5 and Myr at pathological concentrations markedly reduced mitochondrial membrane potential (ΔΨm ), matrix NAD(P)H pool, Ca2+ retention capacity, ADP- (state 3) and carbonyl cyanide 3-chlorophenyl hydrazine-stimulated (uncoupled) respiration, and ATP generation. By contrast, these fatty acids increased resting (state 4) respiration (uncoupling effect) with the involvement of the adenine nucleotide translocator because carboxyatractyloside significantly attenuated the increased state 4 respiration provoked by Cis-5 and Myr. Furthermore, the classical inhibitors of mitochondrial permeability transition (MPT) pore cyclosporin A plus ADP, as well as the Ca2+ uptake blocker ruthenium red, fully prevented the Cis-5- and Myr-induced decrease in ΔΨm in Ca2+ -loaded mitochondria, suggesting, respectively, the induction of MPT pore opening and the contribution of Ca2+ toward these effects. The findings of the present study indicate that the major long-chain fatty acids that accumulate in VLCAD deficiency disrupt mitochondrial bioenergetics and Ca2+ homeostasis, acting as uncouplers and metabolic inhibitors of oxidative phosphorylation, as well as inducers of MPT pore opening, in the heart at pathological relevant concentrations. It is therefore presumed that a disturbance of bioenergetics and Ca2+ homeostasis may contribute to the cardiac manifestations observed in VLCAD deficiency.

Effects of leucine supplementation and resistance training on myopathy of diabetic rats.

Leucine supplementation and resistance training positively influence the protein translation process and the cell signaling mTOR (mammalian target of rapamycin) pathway that regulates muscle protein balance and muscle remodeling, and thus may be therapeutic to diabetic myopathy. However, the effect of a combined intervention has not been well studied. Forty male Wistar rats were divided into five groups, control (C), diabetic control (D), diabetic + trained (DT), diabetic + L-leucine (DL), diabetic + L-leucine + trained (DLT). The supplementation of 5% leucine in chow, and resistance training were conducted for 8 weeks postweaning of rats. The extensor digitorum longus was used to assess signaling proteins involved in muscle protein synthesis, and the gastrocnemius and soleus were used for determination of muscle weight. Blood samples were collected for biochemical assays. Strength and ambulation tests were employed to evaluate motor performance. Results showed that both leucine supplementation and resistance training elevated the activity of mTOR-p70S6K in diabetic rats (P < 0.05). Moreover, though leucine supplementation in combination with resistance training demonstrated synergistic effects on p70S6K (P < 0.05), both treatments were capable of recovering motor performance (P < 0.05). In conclusion, 5% leucine supplementation combined with resistance training has the potential to attenuate muscle loss and motor performance decrements in diabetic rats, at least in part through increased protein synthesis.

Expression of anti-SRP19 antibody in muscle tissues from patients with autoimmune necrotizing myopathy.

This study aimed to investigate the role of anti-SRP19 antibody in muscle tissues of patients with autoimmune necrotizing myopathy. Immunohistochemistry staining was used to determine the expression of anti-SRP19 antibodies in muscle tissues of autoimmune necrotizing myopathy patients. Results demonstrated that anti-SRP19 antibody was expressed in 71.4% (20/28) of muscle tissue specimens from patients with autoimmune necrotizing myopathy. Anti-SRP19 antibody expression was mainly localized in cytoplasm of necrotic muscle fibers surrounding the small blood vessels and interstitial cells. There were no significant differences in the age, course of disease, muscle, and creatine kinase levels between patients with positive or negative expression of anti-SRP19 antibodies. The expression levels of anti-SRP19, serum anti-nuclear antibodies, as well as anti-Ro-52, anti- SSA, anti-Sm, and anti-Jo-1 antibodies were not significantly different among groups. This study demonstrates that anti-SRP19 antibody is highly expressed in muscle tissues of patients with autoimmune necrotizing myopathy, and suggests that this protein may be involved in the origin and progression of the disease.