The role of myokines in muscle health and disease

The Role of FNDC5/Irisin in Cardiovascular Disease

Disorders of cardiomyocyte metabolism play a crucial role in many cardiovascular diseases, such as myocardial infarction, heart failure and ischemia-reperfusion injury. In myocardial infarction, cardiomyocyte metabolism is regulated by mitochondrial changes and biogenesis, which allows energy homeostasis. There are many proteins in cells that regulate and control metabolic processes. One of them is irisin (Ir), which is released from the transmembrane protein FNDC5. Initial studies indicated that Ir is a myokine secreted mainly by skeletal muscles. Further studies showed that Ir was also present in various tissues. However, its highest levels were observed in cardiomyocytes. Ir is responsible for many processes, including the conversion of white adipose tissue (WAT) to brown adipose tissue (BAT) by increasing the expression of thermogenin (UCP1). In addition, Ir affects mitochondrial biogenesis. Therefore, the levels of FNDC5/Ir in the blood and myocardium may be important in cardiovascular disease. This review discusses the current knowledge about the role of FNDC5/Ir in cardiovascular disease.

Interleukin-15 responses to acute and chronic exercise in adults: a systematic review and meta-analysis

Purpose

Interlukin-15 (IL-15) is an inflammatory cytokine that plays a vital role in immunology and obesity-associated metabolic syndrome. We performed this systematic review and meta-analysis to investigate whether exercise promotes circulating IL-15 concentrations in adults.

Methods

We searched PubMed, Web of Science, and Scopus from inception to May, 2023 and identified original studies that investigated the effectiveness of acute and/or chronic exercise on serum/plasma IL-15 levels in adults. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated using random effect models. Subgroup analyses were performed based on type of exercise, and training status, health status and body mass indexes (BMI) of participants.

Results

Fifteen studies involving 411 participants and 12 studies involving 899 participants were included in the acute and chronic exercise analyses, respectively. Our findings showed that acute exercise increased circulating IL-15 concentrations immediately after exercise compared with baseline [SMD=0.90 (95% CI: 0.47 to 1.32), p=0.001], regardless of exercise type and participants' training status. Similarly, acute exercise was also associated with increased IL-15 concentrations even one-hour after exercise [SMD=0.50 (95% CI: 0.00 to 0.99), p=0.04]. Nevertheless, chronic exercise did not have a significant effect on IL-15 concentrations [SMD=0.40 (95% CI: -0.08 to 0.88), p=0.10].

Conclusion

Our results confirm that acute exercise is effective in increasing the IL-15 concentrations immediately and one-hour after exercise intervention, and thereby playing a potential role in improving metabolism in adults.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=445634, identifier CRD42023445634.

Low-intensity pulsed ultrasound mitigates cognitive impairment by inhibiting muscle atrophy in hindlimb unloaded mice

Microgravity leads to muscle loss, usually accompanied by cognitive impairment. Muscle reduction was associated with the decline of cognitive ability. Our previous studies showed that low-intensity pulsed ultrasound (LIPUS) promoted muscle hypertrophy and prevented muscle atrophy. This study aims to verify whether LIPUS can improve cognitive impairment by preventing muscle atrophy in hindlimb unloaded mice. In this study, mice were randomly divided into normal control (NC), hindlimb unloading (HU), hindlimb unloading + LIPUS (HU+LIPUS) groups. The mice in the HU+LIPUS group received a 30 mW/cm2 LIPUS irradiation on gastrocnemius for 20 min/d. After 21 days, LIPUS significantly prevented the decrease in muscle mass and strength caused by tail suspension. The HU+LIPUS mice showed an enhanced desire to explore unfamiliar environments and their spatial learning and memory abilities, enabling them to quickly identify differences between different objects, as well as their social discrimination abilities. MSTN is a negative regulator of muscle growth and also plays a role in regulating cognition. LIPUS significantly inhibited MSTN expression in skeletal muscle and serum and its receptor ActRIIB expression in brain, upregulated AKT and BDNF expression in brain. Taken together, LIPUS may improve the cognitive dysfunction in hindlimb unloaded rats by inhibiting muscle atrophy through MSTN/AKT/BDNF pathway.

Alternations of NF-κB Signaling by Natural Compounds in Muscle-Derived Cancers

The NF-κB-signaling pathway plays a crucial role in cancer progression, including muscle-derived cancers such as rhabdomyosarcoma or sarcoma. Several natural compounds have been studied for their ability to alter NF-κB signaling in these types of cancers. This review paper summarizes the current knowledge on the effects of natural compounds, including curcumin, resveratrol, quercetin, epigallocatechin-3-gallate, and berberine, on NF-κB signaling in muscle-derived cancers. These compounds have been shown to inhibit NF-κB signaling in rhabdomyosarcoma cells through various mechanisms, such as inhibiting the activation of the IKK complex and the NF-κB transcription factor. These findings suggest that natural compounds could be potential therapeutic agents for muscle-derived cancers. However, further research is needed to fully understand their mechanisms of action and potential clinical applications.

Involvement of Matrix Metalloproteinases in COVID-19: Molecular Targets, Mechanisms, and Insights for Therapeutic Interventions

MMPs are enzymes involved in SARS-CoV-2 pathogenesis. Notably, the proteolytic activation of MMPs can occur through angiotensin II, immune cells, cytokines, and pro-oxidant agents. However, comprehensive information regarding the impact of MMPs in the different physiological systems with disease progression is not fully understood. In the current study, we review the recent biological advances in understanding the function of MMPs and examine time-course changes in MMPs during COVID-19. In addition, we explore the interplay between pre-existing comorbidities, disease severity, and MMPs. The reviewed studies showed increases in different MMP classes in the cerebrospinal fluid, lung, myocardium, peripheral blood cells, serum, and plasma in patients with COVID-19 compared to non-infected individuals. Individuals with arthritis, obesity, diabetes, hypertension, autoimmune diseases, and cancer had higher MMP levels when infected. Furthermore, this up-regulation may be associated with disease severity and the hospitalization period. Clarifying the molecular pathways and specific mechanisms that mediate MMP activity is important in developing optimized interventions to improve health and clinical outcomes during COVID-19. Furthermore, better knowledge of MMPs will likely provide possible pharmacological and non-pharmacological interventions. This relevant topic might add new concepts and implications for public health in the near future.

High-intensity circuit training change serum myostatin but not myogenin in adolescents' soccer players: a quasi-experimental study

BACKGROUND

Skeletal muscle contractions due to exercise lead to the secretion of many proteins and proteoglycan peptides called myokines. Myostatin (MSTN) and Myogenin (MyoG) are two of the most important skeletal muscle growth regulatory factors related to myoblast differentiation and muscle hypertrophy. The present study aims at investigating the effects over eight weeks of high-intensity circuit training (HICT) on serum MyoG and MSTN in male soccer players.

METHOD

The present study is a quasi-experimental study on 21 male soccer players (Experimental group: n = 11, Control group: n = 10) (ages 15.0 ± 3.4 years, body mass 55.7 ± 7.8 kg, height 173.3 ± 8.0 cm, Body mass index 18.4 ± 1.9 kg m^-2, maximum oxygen uptake 61.89 ± 3.01 ml kg^-1 and the peak height velocity 14.5 ± 0.3 years). Participants were randomly divided into two groups: training group and a control group. The first resting blood samples were obtained in the morning-fasting state, and the second blood samples were obtained after the maximum aerobic test at pre- and post-HICT.

RESULTS

There were non-significant differences in resting serum values of MyoG (p = 0.309, p > 0.05) but significant differences in resting serum values of MSTN between the training and control groups after eight weeks of HICT (p = 0.003, p < 0.05). No significant differences were observed between groups in the acute response of serum values of MyoG (p = 0.413, p < 0.05) and MSTN (p = 0.465, p < 0.05) to the maximum aerobic test after eight weeks of HICT.

CONCLUSION

These results suggest that eight weeks of HICT can decrease the resting serum values of MSTN but not change the resting serum values of MyoG in male adolescent soccer players. Also, eight weeks of HICT does not affect the acute response of MSTN and MyoG after a maximum aerobic test.

Establishment of quantitative indicators for an efficient treatment on masticatory muscle pain

BACKGROUND

Although several studies have investigated effective treatments for masticatory muscle pain (MMP), no unified conclusion has been drawn regarding the effectiveness of these treatments.

OBJECTIVES

This study aimed to define quantitative indicators for predicting the outcome of MMP treatment.

MATERIALS AND METHODS

In total, patients aged 20-70 years were recruited and divided into the MMP (n = 24) and control (n = 36) groups, based on the presence of MMP according to the Diagnostic Criteria for Temporomandibular Disorders. At pretreatment, the MMP group was assessed using quantitative indicators such as subjective pain levels, pain duration, graded chronic pain scale (GCPS), and perceived stress scale (PSS). Salivary alpha-amylase (sAA) and interleukin-6 (IL-6) levels were analyzed. The masticatory muscle palpation score and the range of mouth opening were measured. At posttreatment, subjective pain levels, mouth opening, and treatment/medication duration were examined. The PSS and sAA levels were assessed in the control group.

RESULTS

sAA levels in the MMP group were significantly higher than those in the control group (p < .05). The masseter muscle palpation score (MPS) showed a positive correlation with IL-6 levels (ρ = 0.503, p < .05) and a negative correlation with nonsteroidal anti-inflammatory drug (NSAID) treatment period (ρ = -0.462, p < .05). The temporalis muscle palpation score (TPS) was positively correlated with pain duration and GCPS grade (ρ = 0.483, p < .05, and ρ = 0.445, p < .05, respectively).

CONCLUSIONS

Treatment with NSAIDs was effective in the MMP group with high MPS and IL-6 levels, but not in the MMP group with high TPS, pain duration, and GCPS grade.

Reactive Oxygen and Nitrogen Species (RONS) and Cytokines-Myokines Involved in Glucose Uptake and Insulin Resistance in Skeletal Muscle

Insulin resistance onset in skeletal muscle is characterized by the impairment of insulin signaling, which reduces the internalization of glucose, known as glucose uptake, into the cell. Therefore, there is a deficit of intracellular glucose, which is the main source for energy production in the cell. This may compromise cellular viability and functions, leading to pathological dysfunction. Skeletal muscle fibers continuously generate reactive oxygen and nitrogen species (RONS). An excess of RONS produces oxidative distress, which may evoke cellular damage and dysfunction. However, a moderate level of RONS, which is called oxidative eustress, is critical to maintain, modulate and regulate cellular functions through reversible interactions between RONS and the components of cellular signaling pathways that control those functions, such as the facilitation of glucose uptake. The skeletal muscle releases peptides called myokines that may have endocrine and paracrine effects. Some myokines bind to specific receptors in skeletal muscle fibers and might interact with cellular signaling pathways, such as PI3K/Akt and AMPK, and facilitate glucose uptake. In addition, there are cytokines, which are peptides produced by non-skeletal muscle cells, that bind to receptors at the plasma membrane of skeletal muscle cells and interact with the cellular signaling pathways, facilitating glucose uptake. RONS, myokines and cytokines might be acting on the same signaling pathways that facilitate glucose uptake in skeletal muscle. However, the experimental studies are limited and scarce. The aim of this review is to highlight the current knowledge regarding the role of RONS, myokines and cytokines as potential signals that facilitate glucose uptake in skeletal muscle. In addition, we encourage researchers in the field to lead and undertake investigations to uncover the fundamentals of glucose uptake evoked by RONS, myokines, and cytokines.

Physical Exercise Restrains Cancer Progression through Muscle-Derived Factors

Simple Summary

The benefits of physical exercise against cancer onset and progression, as well as the adverse effects of physical inactivity have changed the way that we utilize exercise for cancer patients. Nevertheless, although guidelines of various scientific societies and organizations propose exercise as a complementary intervention during cancer therapies, the exact cellular and molecular mechanisms by which exercise acts against cancer have not yet been elucidated. In the present review, we analyze the factors which either are secreted from skeletal muscle or are regulated by exercise and can restrain cancer evolution. We also describe the exercise-induced factors that counteract severe side effects of cancer treatment, as well as the ways that muscle-derived factors are delivered to the target cells.

Abstract

A growing body of in vitro and in vivo studies suggests that physical activity offers important benefits against cancer, in terms of both prevention and treatment. However, the exact mechanisms implicated in the anticancer effects of exercise remain to be further elucidated. Muscle-secreted factors in response to contraction have been proposed to mediate the physical exercise-induced beneficial effects and be responsible for the inter-tissue communications. Specifically, myokines and microRNAs (miRNAs) constitute the most studied components of the skeletal muscle secretome that appear to affect the malignancy, either directly by possessing antioncogenic properties, or indirectly by mobilizing the antitumor immune responses. Moreover, some of these factors are capable of mitigating serious, disease-associated adverse effects that deteriorate patients’ quality of life and prognosis. The present review summarizes the myokines and miRNAs that may have potent anticancer properties and the expression of which is induced by physical exercise, while the mechanisms of secretion and intercellular transportation of these factors are also discussed.

The effect of exercise on cytokines: implications for musculoskeletal health: a narrative review

The physiological effects of physical exercise are ubiquitously reported as beneficial to the cardiovascular and musculoskeletal systems. Exercise is widely promoted by medical professionals to aid both physical and emotional wellbeing; however, mechanisms through which this is achieved are less well understood. Despite numerous beneficial attributes, certain types of exercise can inflict significant significant physiological stress. Several studies document a key relationship between exercise and immune activation. Activation of the innate immune system occurs in response to exercise and it is proposed this is largely mediated by cytokine signalling. Cytokines are typically classified according to their inflammatory properties and evidence has shown that cytokines expressed in response to exercise are diverse and may act to propagate, modulate or mitigate inflammation in musculoskeletal health. The review summarizes the existing literature on the relationship between exercise and the immune system with emphasis on how exercise-induced cytokine expression modulates inflammation and the immune response.

Combined Administration of Andrographolide and Angiotensin- (1-7) Synergically Increases the Muscle Function and Strength in Aged Mice

BACKGROUND

Sarcopenia is a progressive and generalized skeletal muscle disorder characterized by muscle weakness, loss of muscle mass, and decline in the capacity of force generation. Aging can cause sarcopenia. Several therapeutic strategies have been evaluated to prevent or alleviate this disorder. One of them is angiotensin 1-7 [Ang-(1-7)], an anti-atrophic peptide for skeletal muscles that regulates decreased muscle mass for several causes, including aging. Another regulator of muscle mass and function is andrographolide, a bicyclic diterpenoid lactone that decreases the nuclear factor kappa B (NF-κB) signaling and attenuates the severity of some muscle diseases.

OBJECTIVE

Evaluate the effect of combined administration of Ang-(1-7) with andrographolide on the physical performance, muscle strength, and fiber´s diameter in a murine model of sarcopenia by aging.

METHODS

Aged male mice of the C57BL/6J strain were treated with Andrographolide, Ang-(1-7), or combined for three months. The physical performance, muscle strength, and fiber´s diameter were measured.

RESULTS

The results showed that aged mice (24 months old) treated with Ang-(1-7) or Andrographolide improved their performance on a treadmill test, muscle strength, and their fiber´s diameter compared to aged mice without treatment. The combined administration of Ang-(1-7) with andrographolide to aged mice has an enhanced synergically effect on physical performance, muscle strength, and fiber´s diameter.

CONCLUSION

Our results indicated that in aged mice, the effects of andrographolide and Ang-(1-7) on muscle function, strength, and fiber´s diameter are potentiated.

Myopathy Associated With Dermatan Sulfate-Deficient Decorin and Myostatin in Musculocontractural Ehlers-Danlos Syndrome: A Mouse Model Investigation

Carbohydrate sulfotransferase 14 (CHST14) encodes dermatan 4-O-sulfotransferase 1, a critical enzyme for dermatan sulfate (DS) biosynthesis. Musculocontractural Ehlers-Danlos syndrome (mcEDS) is associated with biallelic pathogenic variants of CHST14 and is characterized by malformations and manifestations related to progressive connective tissue fragility. We identified myopathy phenotypes in Chst14-deficient mice using an mcEDS model. Decorin is a proteoglycan harboring a single glycosaminoglycan chain containing mainly DS, which are replaced with chondroitin sulfate (CS) in mcEDS patients with CHST14 deficiency. We studied the function of decorin in the skeletal muscle of Chst14-deficient mice because decorin is important for collagen-fibril assembly and has a myokine role in promoting muscle growth. Although decorin was present in the muscle perimysium of wild-type (Chst14+/+ ) mice, decorin was distributed in the muscle perimysium as well as in the endomysium of Chst14-/- mice. Chst14-/- mice had small muscle fibers within the spread interstitium; however, histopathological findings indicated milder myopathy in Chst14-/- mice. Myostatin, a negative regulator of protein synthesis in the muscle, was upregulated in Chst14-/- mice. In the muscle of Chst14-/- mice, decorin was downregulated compared to that in Chst14+/+ mice. Chst14-/- mice showed altered cytokine/chemokine balance and increased fibrosis, suggesting low myogenic activity in DS-deficient muscle. Therefore, DS deficiency in mcEDS causes pathological localization and functional abnormalities of decorin, which causes disturbances in skeletal muscle myogenesis.

Systemically Administered Homing Peptide Targets Dystrophic Lesions and Delivers Transforming Growth Factor-β (TGFβ) Inhibitor to Attenuate Murine Muscular Dystrophy Pathology

Muscular dystrophy is a progressively worsening and lethal disease, where accumulation of functionality-impairing fibrosis plays a key pathogenic role. Transforming growth factor-β1 (TGFβ1) is a central signaling molecule in the development of fibrosis in muscular dystrophic humans and mice. Inhibition of TGFβ1 has proven beneficial in mouse models of muscular dystrophy, but the global strategies of TGFβ1 inhibition produce significant detrimental side effects. Here, we investigated whether murine muscular dystrophy lesion-specific inhibition of TGFβ1 signaling by the targeted delivery of therapeutic decorin (a natural TGFβ inhibitor) by a vascular homing peptide CAR (CARSKNKDC) would reduce skeletal muscle fibrosis and pathology and increase functional characteristics of skeletal muscle. We demonstrate that CAR peptide homes to dystrophic lesions with specificity in two muscular dystrophy models. Recombinant fusion protein consisting of CAR peptide and decorin homes selectively to sites of skeletal muscle damage in mdxDBA2/J and gamma-sarcoglycan deficient DBA2/J mice. This targeted delivery reduced TGFβ1 signaling as demonstrated by reduced nuclear pSMAD staining. Three weeks of targeted decorin treatment decreased both membrane permeability and fibrosis and improved skeletal muscle function in comparison to control treatments in the mdxD2 mice. These results show that selective delivery of decorin to the sites of skeletal muscle damage attenuates the progression of murine muscular dystrophy.

Nuances between sedentary behavior and physical inactivity: cardiometabolic effects and cardiovascular risk

OBJECTIVE

The aim of this study was to highlight the differences between the cardiometabolic effects and the cardiovascular risk of physical inactivity and sedentary behavior.

METHODS

A narrative bibliographic review was conducted. In the research, national and international articles were selected from the PubMed, SciELO, and LILACS databases using the descriptors "sedentary lifestyle, cardiovascular risk, physical inactivity, sedentary behavior, and cardiovascular risks."

DISCUSSION

Both physical inactivity and sedentary behavior are related to metabolic and organic changes, promoting a chronic proinflammatory state, cardiac remodeling, increased body adiposity, and skeletal muscle dysfunction. It is possibly stated that both of them result in a higher risk of developing chronic diseases, resulting in higher global and cardiovascular morbidity and mortality, with nuances in their intrinsic effects.

CONCLUSIONS

It is inferred that both physical inactivity and sedentary behavior are cardiovascular risk factors that can be modified with the correct clinical approach. It is necessary to differentiate physically inactive individuals from those with a high number of sedentary behaviors. These concepts need better clinical applicability to improve the prevention of primary and secondary cardiovascular risks.

Cytokines and inflammatory mediators as promising markers of polymyositis/dermatomyositis

PURPOSE OF REVIEW

Idiopathic inflammatory myopathies (IIMs), known also as myositis, represent challenging group of heterogeneous muscle disorders characterized by symmetric proximal muscle weakness and evidence of muscle inflammation. The purpose of this review is to provide important updates on cytokines and inflammatory mediators related to myositis.

RECENT FINDINGS

In the past 5 years, multiple studies brought a fresh insight into the pathogenesis of myositis by introducing new factors or further characterizing the role of the well established mediators in myositis. Among the mediators reviewed in this article, special attention was paid to interferons, C-X-C motif chemokine ligand 10, interleukin-18 and the IL23/Th17 axis. Some of the recent work has also focused on the nontraditional cytokines, such as adipokines, myokines, S100 proteins, High Mobility Group Box 1 or B-cell activating factor and on several anti-inflammatory mediators. Moreover, microRNAs and their potential to reflect the disease activity or to regulate the inflammatory processes in myositis have recently been subject of intensive investigation. Some of the above-mentioned mediators have been proposed as promising clinical biomarkers or therapeutic targets for myositis.

SUMMARY

Several recent studies contributed to a better understanding of the pathogenesis of myositis and highlighted the clinical significance of certain inflammatory mediators. Application of these new findings may help to develop innovative approaches for patients' phenotyping, disease activity monitoring and potentially novel therapies.

Caffeine protects against stress-induced murine depression through activation of PPARγC1α-mediated restoration of the kynurenine pathway in the skeletal muscle

Exercise prevents depression through peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α)-mediated activation of a particular branch of the kynurenine pathway. From kynurenine (KYN), two independent metabolic pathways produce neurofunctionally different metabolites, mainly in somatic organs: neurotoxic intermediate metabolites via main pathway and neuroprotective end product, kynurenic acid (KYNA) via the branch. Elevated levels of KYN have been found in patients with depression. Herein, we investigated whether and how caffeine prevents depression, focusing on the kynurenine pathway. Mice exposed to chronic mild stress (CMS) exhibited depressive-like behaviours with an increase and decrease in plasma levels of pro-neurotoxic KYN and neuroprotective KYNA, respectively. However, caffeine rescued CMS-exposed mice from depressive-like behaviours and restored the plasma levels of KYN and KYNA. Concomitantly, caffeine induced a key enzyme converting KYN into KYNA, namely kynurenine aminotransferase-1 (KAT1), in murine skeletal muscle. Upon caffeine stimulation murine myotubes exhibited KAT1 induction and its upstream PGC-1α sustainment. Furthermore, a proteasome inhibitor, but not translational inhibitor, impeded caffeine sustainment of PGC-1α, suggesting that caffeine induced KAT1 by inhibiting proteasomal degradation of PGC-1α. Thus, caffeine protection against CMS-induced depression may be associated with sustainment of PGC-1α levels and the resultant KAT1 induction in skeletal muscle, and thereby consumption of pro-neurotoxic KYN.

Skeletal Muscle in ALS: An Unappreciated Therapeutic Opportunity?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the selective degeneration of upper and lower motor neurons and by the progressive weakness and paralysis of voluntary muscles. Despite intense research efforts and numerous clinical trials, it is still an incurable disease. ALS had long been considered a pure motor neuron disease; however, recent studies have shown that motor neuron protection is not sufficient to prevent the course of the disease since the dismantlement of neuromuscular junctions occurs before motor neuron degeneration. Skeletal muscle alterations have been described in the early stages of the disease, and they seem to be mainly involved in the “dying back” phenomenon of motor neurons and metabolic dysfunctions. In recent years, skeletal muscles have been considered crucial not only for the etiology of ALS but also for its treatment. Here, we review clinical and preclinical studies that targeted skeletal muscles and discuss the different approaches, including pharmacological interventions, supplements or diets, genetic modifications, and training programs.

Sleep Deprivation Interferes with JAK/STAT Signaling Pathway and Myogenesis in the Masseter Muscle of Rats

OBJECTIVES

The aim of the study was to study the Janus kinase/tyrosine kinase-activated transduction factor (JAK/STAT) signaling pathway and myogenesis on the masseter muscle after sleep deprivation and to investigate the role of stress in this scenario.

SUBJECTS AND METHODS

A total of 18 male Wistar rats were divided into the following groups: control (n = 6): animals were not submitted to any procedures, and paradoxical sleep deprivation and vehicle (PSD + V; n = 6): animals were subjected to PSD for 96 h and (PSD + MET; n = 6): animals were subjected to PSD for 96 h with administration of metyrapone. Paradoxical sleep deprivation was performed by the modified multiple platforms method. Histopathological analysis, histomorphometry, and immunohistochemistry were performed.

RESULTS

The results showed the presence of inflammatory infiltrate in the PSD + V and PSD + MET groups and atrophy. Histomorphometry showed that the cellular profile area decreased, while cellular density increased in both experimental groups. Expression of p-STAT 3, MyoD, and MyoG increased in the PSD + V group, while the PSD + MET group showed increased expression of IL-6 and p-STAT 3.

CONCLUSION

Our results suggest that sleep deprivation induces an inflammatory response and atrophy in the masseter muscle of rats.

Effect of Various Exercise Regimens on Selected Exercise-Induced Cytokines in Healthy People

Different forms of physical activity—endurance, resistance or dynamic power—stimulate cytokine release from various tissues to the bloodstream. Receptors for exercise-induced cytokines are present in muscle tissue, adipose tissue, liver, brain, bones, cardiovascular system, immune system, pancreas, and skin. They have autocrine, paracrine and endocrine activities. Many of them regulate the myocyte growth and differentiation necessary for muscle hypertrophy and myogenesis. They also modify energy homeostasis, lipid, carbohydrate, and protein metabolism, regulate inflammation and exchange information (crosstalk) between remote organs. So far, interleukin 6 and irisin have been the best studied exercise-induced cytokines. However, many more can be grouped into myokines, hepatokines and adipomyokines. This review focuses on the less known exercise-induced cytokines such as myostatin, follistatin, decorin, brain-derived neurotrophic factor, fibroblast growth factor 21 and interleukin 15, and their relation to various forms of exercise, i.e., acute vs. chronic, regular training in healthy people.

Gene regulation could be attributed to TCF3 and other key transcription factors in the muscle of pubertal heifers

Puberty is a whole-body event, driven by the hypothalamic integration of peripheral signals such as leptin or IGF-1. In the process of puberty, reproductive development is simultaneous to growth, including muscle growth. To enhance our understanding of muscle function related to puberty, we performed transcriptome analyses of muscle samples from six pre- and six post-pubertal Brahman heifers (Bos indicus). Our aims were to perform differential expression analyses and co-expression analyses to derive a regulatory gene network associate with puberty. As a result, we identified 431 differentially expressed (DEx) transcripts (genes and non-coding RNAs) when comparing pre- to post-pubertal average gene expression. The DEx transcripts were compared with all expressed transcripts in our samples (over 14,000 transcripts) for functional enrichment analyses. The DEx transcripts were associated with "extracellular region," "inflammatory response" and "hormone activity" (adjusted p < .05). Inflammatory response for muscle regeneration is a necessary aspect of muscle growth, which is accelerated during puberty. The term "hormone activity" may signal genes that respond to progesterone signalling in the muscle, as the presence of this hormone is an important difference between pre- and post-pubertal heifers in our experimental design. The DEx transcript with the highest average expression difference was a mitochondrial gene, ENSBTAG00000043574 that might be another important link between energy metabolism and puberty. In the derived co-expression gene network, we identified six hub genes: CDC5L, MYC, TCF3, RUNX2, ATF2 and CREB1. In the same network, 48 key regulators of DEx transcripts were identified, using a regulatory impact factor metric. The hub gene TCF3 was also a key regulator. The majority of the key regulators (22 genes) are members of the zinc finger family, which has been implicated in bovine puberty in other tissues. In conclusion, we described how puberty may affect muscle gene expression in cattle.

Skeletal muscle effects of two different 10-week exercise regimens, voluntary wheel running, and forced treadmill running, in mice: A pilot study

Physical activity and exercise induce a complex pattern of adaptation reactions in a broad variety of tissues and organs, particularly the cardiovascular and the musculoskeletal systems. The underlying mechanisms, however, specifically the molecular changes that occur in response to training, are still incompletely understood. Animal models help to systematically elucidate the mechanisms of exercise adaptation. With regard to endurance-based running exercise in mice, two basic regimens have been established: forced treadmill running (FTR), usually consisting of several sessions per week, and voluntary wheel running (VWR). However, the effects of these two programs on skeletal muscle molecular adaptation patterns have never been directly compared. To address this issue, in a pilot study, we analyzed the effects of two ten-week training regimens in juvenile, male, C57BL/6 mice: moderate-intensity forced treadmill running three-times-a-week, employing a protocol that has been widely used in similar studies before, and voluntary wheel running. Our data suggest that there are similarities, but also characteristic differences in the molecular responses of different skeletal muscle species to the two training regimens. In particular, we found that VWR induces a significant fiber type shift toward more type IIX fibers in the slow, oxidative soleus muscle (p = .0053), but not in the other three muscles analyzed. In addition, while training-induced expression patterns of the two metabolic markers Ppargc1a, encoding Pgc-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and Nr4a3 (nuclear receptor subfamily 4 group A member 3) were roughly similar, downregulation of the Mstn (myostatin) gene and the "atrogene" Fbox32 could only be observed in response to VWR in specific muscles, such as in the gastrocnemius (p = .0015 for Mstn) and in the tibialis anterior (p = .0053 for Fbox32) muscles, suggesting that molecular adaptation reactions to the two training regimens show distinct characteristics.

Levels of Interleukin-6 in Saliva, but Not Plasma, Correlate with Clinical Metrics in Huntington's Disease Patients and Healthy Control Subjects

Growing evidence suggests that inflammatory responses, in both the brain and peripheral tissues, contribute to disease pathology in Huntington's disease (HD), an inherited, progressive neurodegenerative disorder typically affecting adults in their 30-40 s. Hence, studies of inflammation-related markers in peripheral fluids might be useful to better characterize disease features. In this study, we measured levels of C-reactive protein (CRP), Interleukin-6 (IL-6), interleukin 1 beta (IL-1B), and alpha-amylase (AA) in saliva and plasma from n = 125 subjects, including n = 37 manifest HD patients, n = 36 premanifest patients, and n = 52 healthy controls, using immunoassays. We found increases in salivary levels of IL-6, IL-1B and CRP across different disease groups and increased levels of IL-6 in the plasma of HD patients as compared to premanifest patients and controls. The levels of salivary IL-6 were significantly correlated with each of the other salivary markers, as well as with IL-6 levels measured in plasma. Further, salivary IL-6 and IL-1B levels were significantly positively correlated with Total Motor Score (TMS) and chorea scores and negatively correlated with Total Functional Capacity (TFC) in HD patients, whereby in healthy control subjects, IL-6 was significantly negatively correlated with Montreal Cognitive Assessment (MoCA) and the Symbol Digit Modalities test (SDM). Interestingly, the plasma levels of IL-6 did not show similar correlations to any clinical measures in either HD or control subjects. These findings suggest that salivary IL-6 is particularly relevant as a potential non-invasive biomarker for HD symptoms. The advent of an effective, dependable salivary biomarker would meet the urgent need for a less invasive means of identifying and monitoring HD disease progression.

Electroacupuncture Mimics Exercise-Induced Changes in Skeletal Muscle Gene Expression in Women With Polycystic Ovary Syndrome

CONTEXT

Autonomic nervous system activation mediates the increase in whole-body glucose uptake in response to electroacupuncture but the mechanisms are largely unknown.

OBJECTIVE

To identify the molecular mechanisms underlying electroacupuncture-induced glucose uptake in skeletal muscle in insulin-resistant overweight/obese women with and without polycystic ovary syndrome (PCOS).

DESIGN/PARTICIPANTS

In a case-control study, skeletal muscle biopsies were collected from 15 women with PCOS and 14 controls before and after electroacupuncture. Gene expression and methylation was analyzed using Illumina BeadChips arrays.

RESULTS

A single bout of electroacupuncture restores metabolic and transcriptional alterations and induces epigenetic changes in skeletal muscle. Transcriptomic analysis revealed 180 unique genes (q < 0.05) whose expression was changed by electroacupuncture, with 95% of the changes towards a healthier phenotype. We identified DNA methylation changes at 304 unique sites (q < 0.20), and these changes correlated with altered expression of 101 genes (P < 0.05). Among the 50 most upregulated genes in response to electroacupuncture, 38% were also upregulated in response to exercise. We identified a subset of genes that were selectively altered by electroacupuncture in women with PCOS. For example, MSX1 and SRNX1 were decreased in muscle tissue of women with PCOS and were increased by electroacupuncture and exercise. siRNA-mediated silencing of these 2 genes in cultured myotubes decreased glycogen synthesis, supporting a role for these genes in glucose homeostasis.

CONCLUSION

Our findings provide evidence that electroacupuncture normalizes gene expression in skeletal muscle in a manner similar to acute exercise. Electroacupuncture might therefore be a useful way of assisting those who have difficulties performing exercise.

Altered miRNA and mRNA Expression in Sika Deer Skeletal Muscle with Age

Studies of the gene and miRNA expression profiles associated with the postnatal late growth, development, and aging of skeletal muscle are lacking in sika deer. To understand the molecular mechanisms of the growth and development of sika deer skeletal muscle, we used de novo RNA sequencing (RNA-seq) and microRNA sequencing (miRNA-seq) analyses to determine the differentially expressed (DE) unigenes and miRNAs from skeletal muscle tissues at 1, 3, 5, and 10 years in sika deer. A total of 51,716 unigenes, 171 known miRNAs, and 60 novel miRNAs were identified based on four mRNA and small RNA libraries. A total of 2,044 unigenes and 11 miRNAs were differentially expressed between adolescence and juvenile sika deer, 1,946 unigenes and 4 miRNAs were differentially expressed between adult and adolescent sika deer, and 2,209 unigenes and 1 miRNAs were differentially expressed between aged and adult sika deer. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that DE unigenes and miRNA were mainly related to energy and substance metabolism, processes that are closely associate with the growth, development, and aging of skeletal muscle. We also constructed mRNA–mRNA and miRNA–mRNA interaction networks related to the growth, development, and aging of skeletal muscle. The results show that mRNA (Myh1, Myh2, Myh7, ACTN3, etc.) and miRNAs (miR-133a, miR-133c, miR-192, miR-151-3p, etc.) may play important roles in muscle growth and development, and mRNA (WWP1, DEK, UCP3, FUS, etc.) and miRNAs (miR-17-5p, miR-378b, miR-199a-5p, miR-7, etc.) may have key roles in muscle aging. In this study, we determined the dynamic miRNA and unigenes transcriptome in muscle tissue for the first time in sika deer. The age-dependent miRNAs and unigenes identified will offer insights into the molecular mechanism underlying muscle development, growth, and maintenance and will also provide valuable information for sika deer genetic breeding.

Myokines in skeletal muscle physiology and metabolism: Recent advances and future perspectives

Myokines are molecules produced and secreted by skeletal muscle to act in an auto-, para- and endocrine manner to alter physiological function of target tissues. The growing number of effects of myokines on metabolism of distant tissues provides a compelling case for crosstalk between skeletal muscle and other tissues and organs to regulate metabolic homoeostasis. In this review, we summarize and discuss the current knowledge regarding the impact on metabolism of several canonical and recently identified myokines. We focus specifically on myostatin, β-aminoisobutyric acid, interleukin-15, meteorin-like and myonectin, and discuss how these myokines are induced and regulated as well as their overall function. We also review how these myokines may serve as potential prognostic biomarkers that reflect whole-body metabolism and how they may be attractive therapeutic targets for treating muscle and metabolic diseases.

Inflammatory Effects of High and Moderate Intensity Exercise-A Systematic Review

Background: Exercise leads to a robust inflammatory response mainly characterized by the mobilization of leukocytes and an increase in circulating inflammatory mediators produced by immune cells and directly from the active muscle tissue. Both positive and negative effects on immune function and susceptibility to minor illness have been observed following different training protocols. While engaging in moderate activity may enhance immune function above sedentary levels, excessive amounts of prolonged, high-intensity exercise may impair immune function. Thus, the aim of the present review was to clarify the inflammatory effects in response to different exercise intensities. Methods: Search was performed on PubMed and was completed on July 31st, 2017. The studies were eligible if they met the predefined inclusion criteria: a) observational or interventional studies, b) conducted in healthy adults (18-65 years), c) written in Portuguese, English or Spanish, d) including moderate and/or intense exercise. Eighteen articles were included. The specific components that were examined included circulating blood levels of cytokines, leukocytes, creatine kinase (CK) and C-reactive protein (CRP). The methodological quality of the included studies was assessed. Results: Most of the intervention studies showed changes in the assessed biomarkers, although these changes were not consistent. White blood cells (WBC) had an increase immediately after intensive exercise (> 64% VO_2max), without alteration after moderate exercise (46-64% VO_2max). The results suggested an elevation of the pro-inflammatory cytokines, namely IL-6, followed by an elevation of IL-10 that were more evident after intense exercise bouts. CRP increased both after intense and moderate exercise, with peak increases up to 28 h. CK increased only after intensive and long exercising. Conclusion: In summary, intense long exercise can lead, in general, to higher levels of inflammatory mediators, and thus might increase the risk of injury and chronic inflammation. In contrast, moderate exercise or vigorous exercise with appropriate resting periods can achieve maximum benefit.

Neuromuscular Electrical Stimulation: A New Therapeutic Option for Chronic Diseases Based on Contraction-Induced Myokine Secretion

Myokines are peptides known to modulate brain neuroplasticity, adipocyte metabolism, bone mineralization, endothelium repair and cell growth arrest in colon and breast cancer, among other processes. Repeated skeletal muscle contraction induces the production and secretion of myokines, which have a wide range of functions in different tissues and organs. This new role of skeletal muscle as a secretory organ means skeletal muscle contraction could be a key player in the prevention and/or management of chronic disease. However, some individuals are not capable of optimal physical exercise in terms of adequate duration, intensity or muscles involved, and therefore they may be virtually deprived of at least some of the physiological benefits induced by exercise. Neuromuscular electrical stimulation (NMES) is emerging as an effective physical exercise substitute for myokine induction. NMES is safe and efficient and has been shown to improve muscle strength, functional capacity, and quality of life. This alternative exercise modality elicits hypertrophy and neuromuscular adaptations of skeletal muscles. NMES stimulates circulating myokine secretion, promoting a cascade of endocrine, paracrine, and autocrine effects. We review the current evidence supporting NMES as an effective physical exercise substitute for inducing myokine production and its potential applications in health and disease.

Functional and Structural Adaptations of Skeletal Muscle in Long-Term Juvenile Dermatomyositis: A Controlled Cross-Sectional Study

OBJECTIVE

To compare muscle strength and endurance of the knee extensors between patients with long-term juvenile dermatomyositis (DM) and controls and between patients with active disease and those with inactive disease, and to explore associations between strength/endurance and 1) clinical parameters, 2) physical activity, and 3) humoral/structural adaptation in the skeletal muscle of patients.

METHODS

In a cross-sectional study (44 patients and 44 age- and sex-matched controls), we tested isometric muscle strength (peak torque, in Nm) and dynamic muscle endurance (total work, in Joules) of the knee extensors, physical activity (measured by accelerometer), and serum myokine levels (by enzyme-linked immunosorbent assay). Patients were examined with validated tools (clinical muscle tests and measures of disease activity/damage and inactive disease) and using magnetic resonance imaging of the thigh muscles, which included evaluation of the quadriceps cross-sectional area (CSA). Needle biopsy samples of the vastus lateralis muscle (obtained from 12 patients ages ≥18 years) were assessed by histochemistry.

RESULTS

After a mean ± SD disease duration of 21.8 ± 11.8 years, peak torque was lower in patients with juvenile DM compared to controls (mean difference 29 Nm, 95% confidence interval 13-46; P = 0.001). Similarly, total work of the knee extensors was lower in patients compared to controls (median 738J [interquartile range 565-1,155] versus 1,249J [interquartile range 815-1,665]; P < 0.001). Both peak torque and total work were lower in patients with active juvenile DM compared to those with inactive disease (both P < 0.019); in analyses controlled for quadriceps CSA, only total work remained lower in patients with active disease. Moreover, peak torque and total work correlated with findings from clinical muscle tests in patients with active disease (r = 0.57-0.84). Muscle biopsy results indicated that the fiber type composition was different, but capillary density was similar, between patients with active disease and those with inactive disease.

CONCLUSION

In patients with long-term juvenile DM, both muscle strength and endurance of the knee extensors were lower when compared to matched controls, and also lower in patients with active disease compared to those with inactive disease. Our results indicate a need for more sensitive muscle tests in this clinical setting. We hypothesize that impaired muscle endurance in patients with active juvenile DM may be influenced by structural/functional adaptations of muscle tissue independent of muscle size.

Stem Cells from a Female Rat Model of Type 2 Diabetes/Obesity and Stress Urinary Incontinence Are Damaged by In Vitro Exposure to its Dyslipidemic Serum, Predicting Inadequate Repair Capacity In Vivo

Female stress urinary incontinence (FSUI) is prevalent in women with type 2 diabetes/obesity (T2D/O), and treatment is not optimal. Autograph stem cell therapy surprisingly has poor efficacy. In the male rat model of T2D/O, it was demonstrated that epigenetic changes, triggered by long-term exposure to the dyslipidemic milieu, led to abnormal global transcriptional signatures (GTS) of genes and microRNAs (miR), and impaired the repair capacity of muscle-derived stem cells (MDSC). This was mimicked in vitro by treatment of MDSC with dyslipidemic serum or lipid factors. The current study aimed to predict whether these changes also occur in stem cells from female 12 weeks old T2D/O rats, a model of FSUI. MDSCs from T2D/O (ZF4-SC) and normal female rats (ZL4-SC) were treated in vitro with either dyslipidemic serum (ZFS) from late T2D/O 24 weeks old female Zucker fatty (ZF) rats, or normal serum (ZLS) from 24 weeks old female Zucker lean (ZL) rats, for 4 days and subjected to assays for fat deposition, apoptosis, scratch closing, myostatin, interleukin-6, and miR-GTS. The dyslipidemic ZFS affected both female stem cells more severely than in the male MDSC, with some gender-specific differences in miR-GTS. The changes in miR-GTS and myostatin/interleukin-6 balance may predict in vivo noxious effects of the T2D/O milieu that might impair autograft stem cell (SC) therapy for FSUI, but this requires future studies.

Caffeine-stimulated muscle IL-6 mediates alleviation of non-alcoholic fatty liver disease

Caffeine intake is associated with a reduced risk developing non-alcoholic fatty liver disease (NAFLD), but the underlying molecular mechanisms remain to be fully elucidated. We report here that caffeine markedly improved high fat diet-induced NAFLD in mice resulting in a 10-fold increase in circulating IL-6 levels, leading to STAT3 activation in the liver. Interestingly, the expression of IL-6 mRNA was not increased in the liver, but increased substantially in the muscles of caffeine-treated mice. Caffeine was found to stimulate IL-6 production in cultured myotubes but not in hepatocytes, adipocytes, or macrophages. The inhibition of p38/MAPK abrogated caffeine-induced IL-6 production in muscle cells. Caffeine failed to improve NAFLD in IL-6 and hepatocyte-specific STAT3 knockout mice, indicating that the IL-6/STAT3 pathway is vital for the hepatoprotective effects of caffeine in NAFLD. The possibility that IL-6/STAT3-mediated hepatic autophagosome induction and hepatocytic oxygen consumption are involved in the anti-NAFLD effects of caffeine cannot be excluded, based on the findings presented here. Our results reveal that caffeine ameliorates NAFLD via crosstalk between muscle IL-6 production and liver STAT3 activation.

The regulation of skeletal muscle fatigability and mitochondrial function by chronically elevated interleukin-6

NEW FINDINGS

What is the central question of this study? Interleukin-6 has been associated with muscle mass and metabolism in both physiological and pathological conditions. A causal role for interleukin-6 in the induction of fatigue and disruption of mitochondrial function has not been determined. What is the main finding and its importance? We demonstrate that chronically elevated interleukin-6 increased skeletal muscle fatigability and disrupted mitochondrial content and function independent of changes in fibre type and mass.

ABSTRACT

Interleukin-6 (IL-6) can initiate intracellular signalling in skeletal muscle by binding to the IL-6-receptor and interacting with the transmembrane gp130 protein. Circulating IL-6 has established effects on skeletal muscle mass and metabolism in both physiological and pathological conditions. However, the effects of circulating IL-6 on skeletal muscle function are not well understood. The purpose of this study was to determine whether chronically elevated systemic IL-6 was sufficient to disrupt skeletal muscle force, fatigue and mitochondrial function. Additionally, we examined the role of muscle gp130 signalling during overexpression of IL-6. Systemic IL-6 overexpression for 2 weeks was achieved by electroporation of an IL-6 overexpression plasmid or empty vector into the quadriceps of either C57BL/6 (WT) or skeletal muscle gp130 knockout (KO) male mice. Tibialis anterior muscle in situ functional properties and mitochondrial respiration were determined. Interleukin-6 accelerated in situ skeletal muscle fatigue in the WT, with a 18.5% reduction in force within 90 s of repeated submaximal contractions and a 7% reduction in maximal tetanic force after 5 min. There was no difference between fatigue in the KO and KO+IL-6. Interleukin-6 reduced WT muscle mitochondrial respiratory control ratio by 36% and cytochrome c oxidase activity by 42%. Interleukin-6 had no effect on either KO respiratory control ratio or cytochrome c oxidase activity. Interleukin-6 also had no effect on body weight, muscle mass or tetanic force in either genotype. These results provide evidence that 2 weeks of elevated systemic IL-6 is sufficient to increase skeletal muscle fatigability and decrease muscle mitochondrial content and function, and these effects require muscle gp130 signalling.

A Comparative Peptidomic Characterization of Cultured Skeletal Muscle Tissues Derived From db/db Mice

As an important secretory organ, skeletal muscle has drawn attention as a potential target tissue for type 2 diabetic mellitus (T2DM). Recent peptidomics approaches have been applied to identify secreted peptides with potential bioactive. However, comprehensive analysis of the secreted peptides from skeletal muscle tissues of db/db mice and elucidation of their possible roles in insulin resistance remains poorly characterized. Here, we adopted a label-free discovery using liquid chromatography tandem mass spectrometry (LC-MS/MS) technology and identified 63 peptides (42 up-regulated peptides and 21 down-regulated peptides) differentially secreted from cultured skeletal muscle tissues of db/db mice. Analysis of relative molecular mass (Mr), isoelectric point (pI) and distribution of Mr vs pI of differentially secreted peptides presented the general feature. Furthermore, Gene ontology (GO) and pathway analyses for the parent proteins made a comprehensive functional assessment of these differential peptides, indicating the enrichment in glycolysis/gluconeogenesis and striated muscle contraction processes. Intercellular location analysis pointed out most precursor proteins of peptides were cytoplasmic or cytoskeletal. Additionally, cleavage site analysis revealed that Lysine (N-terminal)-Alanine (C-terminal) and Lysine (N-terminal)-Leucine (C-terminal) represents the preferred cleavage sites for identified peptides and proceeding peptides respectively. Mapped to the precursors' sequences, most identified peptides were observed cleaved from creatine kinase m-type (KCRM) and fructose-bisphosphate aldolase A (Aldo A). Based on UniProt and Pfam database for specific domain structure or motif, 44 peptides out of total were positioned in the functional motif or domain from their parent proteins. Using C2C12 myotubes as cell model in vitro, we found several candidate peptides displayed promotive or inhibitory effects on insulin and mitochondrial-related pathways by an autocrine manner. Taken together, this study will encourage us to investigate the biologic functions and the potential regulatory mechanism of these secreted peptides from skeletal muscle tissues, thus representing a promising strategy to treat insulin resistance as well as the associated metabolic disorders.

Effect of high-intensity interval training on muscle remodeling in rheumatoid arthritis compared to prediabetes

Background

Sarcopenic obesity, associated with greater risk of cardiovascular disease (CVD) and mortality in rheumatoid arthritis (RA), may be related to dysregulated muscle remodeling. To determine whether exercise training could improve remodeling, we measured changes in inter-relationships of plasma galectin-3, skeletal muscle cytokines, and muscle myostatin in patients with RA and prediabetes before and after a high-intensity interval training (HIIT) program.

Methods

Previously sedentary persons with either RA (n = 12) or prediabetes (n = 9) completed a 10-week supervised HIIT program. At baseline and after training, participants underwent body composition (Bod Pod^®) and cardiopulmonary exercise testing, plasma collection, and vastus lateralis biopsies. Plasma galectin-3, muscle cytokines, muscle interleukin-1 beta (mIL-1β), mIL-6, mIL-8, muscle tumor necrosis factor-alpha (mTNF-α), mIL-10, and muscle myostatin were measured via enzyme-linked immunosorbent assays. An independent cohort of patients with RA (n = 47) and age-, gender-, and body mass index (BMI)-matched non-RA controls (n = 23) were used for additional analyses of galectin-3 inter-relationships.

Results

Exercise training did not reduce mean concentration of galectin-3, muscle cytokines, or muscle myostatin in persons with either RA or prediabetes. However, training-induced alterations varied among individuals and were associated with cardiorespiratory fitness and body composition changes. Improved cardiorespiratory fitness (increased absolute peak maximal oxygen consumption, or VO₂) correlated with reductions in galectin-3 (r = −0.57, P = 0.05 in RA; r = −0.48, P = 0.23 in prediabetes). Training-induced improvements in body composition were related to reductions in muscle IL-6 and TNF-α (r < −0.60 and P <0.05 for all). However, the association between increased lean mass and decreased muscle IL-6 association was stronger in prediabetes compared with RA (Fisher r-to-z P = 0.0004); in prediabetes but not RA, lean mass increases occurred in conjunction with reductions in muscle myostatin (r = −0.92; P <0.05; Fisher r-to-z P = 0.026). Subjects who received TNF inhibitors (n = 4) or hydroxychloroquine (n = 4) did not improve body composition with exercise training.

Conclusion

Exercise responses in muscle myostatin, cytokines, and body composition were significantly greater in prediabetes than in RA, consistent with impaired muscle remodeling in RA. To maximize physiologic improvements with exercise training in RA, a better understanding is needed of skeletal muscle and physiologic responses to exercise training and their modulation by RA disease–specific features or pharmacologic agents or both.

Trial registration

ClinicalTrials.gov Identifier: NCT02528344. Registered on August 19, 2015.

Potential clinical treatment of colitis with cardiotrophin-1

In a recent issue of Clinical Science, Prieto-Vicente et al. [Clin. Sci. (2018) 132, 985-1001] have smartly demonstrated a potential new use of cardiotrophin-1 (CT-1) to treat and palliate an inflammatory bowel disease such as ulcerative colitis. In that work, authors report that in ulcerative colitic mice, administration of exogenous recombinant CT-1 (rCT-1) promotes lower colon damage and lower disease activity index, reducing systemic levels of tumor necrosis factor α (TNF-α) and also diminishing TNF-α expression in colon together with the reduction in other common inflammation markers. Besides, in vivo rCT-1 administration induces activation of several molecular pathways, including nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT)-3, and abolishes bacterial translocation from intestine to other organs, including mesenteric ganglia, lungs, and spleen. Additionally, these results were nicely corroborated in CT-1 depleted mice; in which colon damage and ulcerative colitis severity were greater compared with the wild-type counterparts. All together, these results suggested that CT-1 could be a promising new therapeutic approach for treating inflammatory bowel disease, particularly ulcerative colitis. However, further studies are required to determine its major mechanisms of action and the potential efficacy of CT-1 in human inflammatory bowel diseases.

Myokines, physical activity, insulin resistance and autoimmune diseases

Myokines are peptides produced and released by myocytes of muscle fibers that influence physiology of muscle and other organs and tissues. They are involved in mediating the beneficial effects that exercise has on health. More than one hundred have been identified and among them are IL6, myostatin, irisin, mionectin and decorin. Physical inactivity leads to an altered response of the secretion of myokines and resistance to them; this leads to a pro-inflammatory state that favors sarcopenia and fat accumulation, promoting the development of cardiovascular diseases, insulin resistance, and diabetes mellitus type 2. Some myokines, including irisin, are responsible for the improvement that exercise produces in many chronic diseases such as type 2 diabetes and cardiovascular diseases, some types of cancer and many autoimmune diseases such as idiopathic inflammatory myopathy, rheumatoid arthritis, systemic lupus erythematosus and inflammatory bowel disease.

Novel Trajectories of Bromocriptine Antidiabetic Action: Leptin-IL-6/ JAK2/p-STAT3/SOCS3, p-IR/p-AKT/GLUT4, PPAR-γ/Adiponectin, Nrf2/PARP-1, and GLP-1

Bromocriptine (BC), a sympatholytic dopaminergic D2 receptor agonist, has been comprehensively used in clinic to treat Parkinson’s disease (PD) and prolactinomas. Besides, BC represents a novel therapeutic option in type 2 diabetes (T2DM); however, the precise mechanisms are not completely unveiled. Hence, the objective of the current work is to clarify the potential molecular pathways of the insulin sensitizing effect of BC in the skeletal muscle of diabetic rats and to evaluate its possible interaction with sitagliptin (SG) as an add-on therapy. Here experimental model impersonates unhealthy dietary habit and T2DM was adopted, in which rats were fed high caloric diet of fat and fructose for 6 weeks followed by a single sub-diabetogenic dose of streptozotocin (STZ) (35 mg/kg; HF/Fr/STZ). Diabetic rats were treated with BC, SG at two dose levels (SG10 and SG20) and combination of BC + SG10 for 2 weeks. BC successfully corrected glucose/lipid profile, as well as leptin and GLP-1. On the muscular molecular level, BC curtailed the inflammatory signal IL-6/JAK2/p-STAT3/SOCS3, while enhanced the PPAR-γ/adiponectin signaling, resulting in activation of the insulin signaling pathway (p-IR/p-AKT/GLUT4). Moreover, BC confirmed its antioxidant capabilities by altering Nrf2 and PARP-1; the study also highlighted novel mechanisms for SG as well. On almost all tested parameters/pathways, the combination regimen surpassed each drug alone to reach a comparable level to the high dose of SG. In conclusion, our finding shed some light on novel anti-diabetic mechanisms of BC. The study also points to the potential use of BC as an adds-on to standard anti-diabetic therapies.

Current Classification and Management of Inflammatory Myopathies

Inflammatory disorders of the skeletal muscle include polymyositis (PM), dermatomyositis (DM), (immune mediated) necrotizing myopathy (NM), overlap syndrome with myositis (overlap myositis, OM) including anti-synthetase syndrome (ASS), and inclusion body myositis (IBM). Whereas DM occurs in children and adults, all other forms of myositis mostly develop in middle aged individuals. Apart from a slowly progressive, chronic disease course in IBM, patients with myositis typically present with a subacute onset of weakness of arms and legs, often associated with pain and clearly elevated creatine kinase in the serum. PM, DM and most patients with NM and OM usually respond to immunosuppressive therapy, whereas IBM is largely refractory to treatment. The diagnosis of myositis requires careful and combinatorial assessment of (1) clinical symptoms including pattern of weakness and paraclinical tests such as MRI of the muscle and electromyography (EMG), (2) broad analysis of auto-antibodies associated with myositis, and (3) detailed histopathological work-up of a skeletal muscle biopsy. This review provides a comprehensive overview of the current classification, diagnostic pathway, treatment regimen and pathomechanistic understanding of myositis.

Transcriptional profiling reveals extraordinary diversity among skeletal muscle tissues

Skeletal muscle comprises a family of diverse tissues with highly specialized functions. Many acquired diseases, including HIV and COPD, affect specific muscles while sparing others. Even monogenic muscular dystrophies selectively affect certain muscle groups. These observations suggest that factors intrinsic to muscle tissues influence their resistance to disease. Nevertheless, most studies have not addressed transcriptional diversity among skeletal muscles. Here we use RNAseq to profile mRNA expression in skeletal, smooth, and cardiac muscle tissues from mice and rats. Our data set, MuscleDB, reveals extensive transcriptional diversity, with greater than 50% of transcripts differentially expressed among skeletal muscle tissues. We detect mRNA expression of hundreds of putative myokines that may underlie the endocrine functions of skeletal muscle. We identify candidate genes that may drive tissue specialization, including Smarca4, Vegfa, and Myostatin. By demonstrating the intrinsic diversity of skeletal muscles, these data provide a resource for studying the mechanisms of tissue specialization.

About 40% of our weight is formed of skeletal muscles, the hundreds of muscles in our bodies that can be voluntarily controlled by our nervous system. At the moment, the research community largely sees all these muscles as a single group whose tissues are virtually interchangeable.

Yet, skeletal muscles have highly diverse origins, shapes and roles. For example, our diaphragm is a long muscle that contracts slowly and rhythmically so we can draw breaths, while tiny muscles in our eyes generate the short and precise movements of our eyeballs. Different skeletal muscles also respond in distinct ways to injuries, drugs and diseases. This suggests that these muscles may be diverse at the genetic level.

While all the cells in our body have the same genetic information, exactly which genes are turned on and off (or ‘expressed’) changes between types of cells. On top of this ‘on or off’ regulation, the level of expression of a gene – how active it is – can also differ. However, the studies that examine the differences in gene expression between tissues usually overlook skeletal muscles.

Here, Terry et al. use genetic techniques to measure how genes are expressed in over 20 types of muscle in mice and rats. The results show that the expression levels of over 50% of all the animals’ genes vary between muscles. In fact, any two types of muscles express on average 13% of their genes differently from each other. The analyses yield further unexpected findings. For example, the expression levels in a muscle in the foot that helps to flex the rodents’ toes are more similar to those found in eye muscles than to the ones observed in limb muscles. These conclusions indicate that skeletal muscles are a widely diverse family of tissues.

The research community will be able to use the data collected by Terry et al. to explore further the origins and the consequences of the differences between skeletal muscles. This could help researchers to understand why specific groups of muscles are more susceptible to disease, or react differently to a drug. This knowledge could also be exploited to refine approaches in tissue engineering, which aims to replace damaged muscles in the body.

The 2017 hormone therapy position statement of The North American Menopause Society

The 2017 Hormone Therapy Position Statement of The North American Menopause Society (NAMS) updates the 2012 Hormone Therapy Position Statement of The North American Menopause Society and identifies future research needs. An Advisory Panel of clinicians and researchers expert in the field of women's health and menopause was recruited by NAMS to review the 2012 Position Statement, evaluate new literature, assess the evidence, and reach consensus on recommendations, using the level of evidence to identify the strength of recommendations and the quality of the evidence. The Panel's recommendations were reviewed and approved by the NAMS Board of Trustees.Hormone therapy (HT) remains the most effective treatment for vasomotor symptoms (VMS) and the genitourinary syndrome of menopause (GSM) and has been shown to prevent bone loss and fracture. The risks of HT differ depending on type, dose, duration of use, route of administration, timing of initiation, and whether a progestogen is used. Treatment should be individualized to identify the most appropriate HT type, dose, formulation, route of administration, and duration of use, using the best available evidence to maximize benefits and minimize risks, with periodic reevaluation of the benefits and risks of continuing or discontinuing HT.For women aged younger than 60 years or who are within 10 years of menopause onset and have no contraindications, the benefit-risk ratio is most favorable for treatment of bothersome VMS and for those at elevated risk for bone loss or fracture. For women who initiate HT more than 10 or 20 years from menopause onset or are aged 60 years or older, the benefit-risk ratio appears less favorable because of the greater absolute risks of coronary heart disease, stroke, venous thromboembolism, and dementia. Longer durations of therapy should be for documented indications such as persistent VMS or bone loss, with shared decision making and periodic reevaluation. For bothersome GSM symptoms not relieved with over-the-counter therapies and without indications for use of systemic HT, low-dose vaginal estrogen therapy or other therapies are recommended.This NAMS position statement has been endorsed by Academy of Women's Health, American Association of Clinical Endocrinologists, American Association of Nurse Practitioners, American Medical Women's Association, American Society for Reproductive Medicine, Asociación Mexicana para el Estudio del Climaterio, Association of Reproductive Health Professionals, Australasian Menopause Society, Chinese Menopause Society, Colegio Mexicano de Especialistas en Ginecologia y Obstetricia, Czech Menopause and Andropause Society, Dominican Menopause Society, European Menopause and Andropause Society, German Menopause Society, Groupe d'études de la ménopause et du vieillissement Hormonal, HealthyWomen, Indian Menopause Society, International Menopause Society, International Osteoporosis Foundation, International Society for the Study of Women's Sexual Health, Israeli Menopause Society, Japan Society of Menopause and Women's Health, Korean Society of Menopause, Menopause Research Society of Singapore, National Association of Nurse Practitioners in Women's Health, SOBRAC and FEBRASGO, SIGMA Canadian Menopause Society, Società Italiana della Menopausa, Society of Obstetricians and Gynaecologists of Canada, South African Menopause Society, Taiwanese Menopause Society, and the Thai Menopause Society. The American College of Obstetricians and Gynecologists supports the value of this clinical document as an educational tool, June 2017. The British Menopause Society supports this Position Statement.

Irisin and myostatin responses to acute high-intensity interval exercise in humans

Background The purpose of this study was to investigate irisin and myostatin responses to acute high-intensity interval exercise. Materials and methods Ten male professional kick-boxers aged between 18 and 24 years and 10 sedentary males with similar age and body weight participated in the present study. Participants performed 4 × 30-s Wingate test separated with 4 min of rest. Blood samples were taken immediately before and after exercise, and 3 and 6 h of recovery. Results and conclusion At rest, irisin levels were higher in the kick-boxers (p < 0.05). Immediately after the exercise, irisin levels were decreased in both groups (p < 0.05). A trend toward a return to baseline appeared after 3 h of recovery in the kick-boxers (p < 0.05). At rest, myostatin concentrations were not different between the groups (p > 0.05). Immediately after the exercise, myostatin levels were increased in both groups (p < 0.05). A trend toward a return to baseline appeared after 3 h of recovery in the kick-boxers (p < 0.05). Acute high-intensity interval exercise decreased irisin levels and increased myostatin levels.

Comparison of muscle/lean mass measurement methods: correlation with functional and biochemical testing

DXA-measured lean mass is often used to assess muscle mass but has limitations. Thus, we compared DXA lean mass with two novel methods-bioelectric impedance spectroscopy and creatine (methyl-d3) dilution. The examined methodologies did not measure lean mass similarly and the correlation with muscle biomarkers/function varied.

INTRODUCTION

Muscle function tests predict adverse health outcomes better than lean mass measurement. This may reflect limitations of current mass measurement methods. Newer approaches, e.g., bioelectric impedance spectroscopy (BIS) and creatine (methyl-d3) dilution (D3-C), may more accurately assess muscle mass. We hypothesized that BIS and D3-C measured muscle mass would better correlate with function and bone/muscle biomarkers than DXA measured lean mass.

METHODS

Evaluations of muscle/lean mass, function, and serum biomarkers were obtained in older community-dwelling adults. Mass was assessed by DXA, BIS, and orally administered D3-C. Grip strength, timed up and go, and jump power were examined. Potential muscle/bone serum biomarkers were measured. Mass measurements were compared with functional and serum data using regression analyses; differences between techniques were determined by paired t tests.

RESULTS

Mean (SD) age of the 112 (89F/23M) participants was 80.6 (6.0) years. The lean/muscle mass assessments were correlated (.57-.88) but differed (p < 0.0001) from one another with DXA total body less head being highest at 37.8 (7.3) kg, D3-C muscle mass at 21.1 (4.6) kg, and BIS total body intracellular water at 17.4 (3.5) kg. All mass assessment methods correlated with grip strength and jump power (R = 0.35-0.63, p < 0.0002), but not with gait speed or repeat chair rise. Lean mass measures were unrelated to the serum biomarkers measured.

CONCLUSIONS

These three methodologies do not similarly measure muscle/lean mass and should not be viewed as being equivalent. Functional tests assessing maximal muscle strength/power (grip strength and jump power) correlated with all mass measures whereas gait speed was not. None of the selected serum measures correlated with mass. Efforts to optimize muscle mass assessment and identify their relationships with health outcomes are needed.

NF-kB and Inflammatory Cytokine Signalling: Role in Skeletal Muscle Atrophy

Atrophy is a classical hallmark of an array of disorders that affect skeletal muscle, ranging from inherited dystrophies, acquired inflammatory myopathies, ageing (sarcopenia) and critical illness (sepsis). The loss of muscle mass and function in these instances is associated with disability, poor quality of life and in some cases mortality. The mechanisms which underpin muscle atrophy are complex; however, significant research has demonstrated an important role for inflammatory cytokines such as tumour necrosis factor-alpha (TNF-α), mediated by the generation of reactive oxygen species (ROS) in muscle wasting. Moreover, activation of the transcription factor nuclear factor kappa B (NF-κB) is a key lynchpin in the overall processes that mediate muscle atrophy. The significance of NF-κB as a key regulator of muscle atrophy has been emphasised by several in vivo studies, which have demonstrated that NF-κB-targeted therapies can abrogate muscle atrophy. In this chapter, we will summarise current knowledge on the role of cytokines (TNF-α) and NF-κB in the loss of muscle mass and function and highlight perspectives towards future research and potential therapies to combat muscle atrophy.

Myokines related to leukocyte recruitment are down-regulated in osteosarcoma

Myokines are cytokines that are secreted by muscle cells during exercises, muscle development and pathology. Studies have shown that expression of some individual myokines was altered in tumors. However, comprehensive analyses of myokines' expression in osteosarcoma (OS), the most common malignant tumor in musculoskeletal system, have not been performed. In this study, we analyzed the expression of 35 myokines in osteosarcoma, peritumoral skeletal muscle, and cancellous bone by qRT-PCR. Heatmap analysis based on the expression pattern of these myokines revealed that OS is more likely derived from cancellous bone than peritumoral skeletal muscle. Thus, we compared the expression of myokines between OS and cancellous bone to reveal a potential role of myokines in OS development. Our results showed that expression of 19 myokines in OS was significantly lower than that in cancellous bone. KEGG signaling pathway analysis showed that these 19 myokines are involved in several important signaling pathways, one of which was associated with leukocyte recruitment in TNF-α signaling. We verified that expression of these leukocyte recruitment-related myokines were down-regulated in OS cell line MNNG compared to those in human BMSC. Downregulation of the myokines related to leukocyte recruitment suggests that escaping from host immune system may help the occurrence of osteosarcoma.

Exercise Inhibits the Effects of Smoke-Induced COPD Involving Modulation of STAT3

PURPOSE

Evaluate the participation of STAT3 in the effects of aerobic exercise (AE) in a model of smoke-induced COPD.

METHODS

C57Bl/6 male mice were divided into control, Exe, COPD, and COPD+Exe groups. Smoke were administered during 90 days. Treadmill aerobic training begun on day 61 until day 90. Pulmonary inflammation, systemic inflammation, the level of lung emphysema, and the airway remodeling were evaluated. Analysis of integral and phosphorylated expression of STAT3 by airway epithelial cells, peribronchial leukocytes, and parenchymal leukocytes was performed.

RESULTS

AE inhibited smoke-induced accumulation of total cells (p < 0.001), lymphocytes (p < 0.001), and neutrophils (p < 0.001) in BAL, as well as BAL levels of IL-1β (p < 0.001), CXCL1 (p < 0.001), IL-17 (p < 0.001), and TNF-α (p < 0.05), while increased the levels of IL-10 (p < 0.001). AE also inhibited smoke-induced increases in total leukocytes (p < 0.001), neutrophils (p < 0.05), lymphocytes (p < 0.001), and monocytes (p < 0.01) in blood, as well as serum levels of IL-1β (p < 0.01), CXCL1 (p < 0.01), IL-17 (p < 0.05), and TNF-α (p < 0.01), while increased the levels of IL-10 (p < 0.001). AE reduced smoke-induced emphysema (p < 0.001) and collagen fiber accumulation in the airways (p < 0.001). AE reduced smoke-induced STAT3 and phospho-STAT3 expression in airway epithelial cells (p < 0.001), peribronchial leukocytes (p < 0.001), and parenchymal leukocytes (p < 0.001).

CONCLUSIONS

AE reduces smoke-induced COPD phenotype involving STAT3.