Effects of vitamin C, vitamin E, zinc gluconate, and selenomethionine supplementation on muscle function and oxidative stress biomarkers in patients with facioscapulohumeral dystrophy: a double-blind randomized controlled clinical trial

The association between dietary vitamins and the risk of sarcopenia in adults aged 20-59: a study based on the NHANES database

Background

Sarcopenia has emerged as a global health concern, but the association between dietary vitamin levels and sarcopenia is not elucidated. This study aims to shed light on the link of 11 dietary vitamins to the risk of sarcopenia in adults at the age of 20-59.

Methods

This cross-sectional study encompassed 2011-2018 data from the National Health and Nutrition Examination Survey (NHANES) for adults aged 20-59. Sarcopenia was defined through the appendicular lean mass to body mass index ratio calculated via Dual-Energy X-ray Absorptiometry (DXA), with sarcopenia determined as a ratio of <0.789 for the male and <0.512 for the female. Multivariate weighted logistic regression assisted in assessing the connection of dietary vitamins with sarcopenia, with results presented as odds ratios (ORs) and 95% confidence intervals (CIs). The dose-response association of various vitamins with sarcopenia was visualized through restricted cubic splines (RCS). Subgroup analyses were carried out to examine the consistency of the aforementioned associations. Sensitivity analysis was performed utilizing propensity score matching (PSM) to adjust for confounding factors and enhance the robustness of the results.

Results

Among the 7,864 participants, 677 (8.6%) had sarcopenia, and 7,187 (91.4%) did not. Multivariate weighted logistic regression and RCS analyses indicated that higher intakes of VA, VB1, VB2, VB3, VB6, VB9, VB12, VC, VE, and VK were notably linked to a lowered risk of sarcopenia (P < 0.05). Among these, VA, VC, and VE exhibited a non-linear negative association with sarcopenia risk (P for non-linear < 0.05), while VB1, VB2, VB3, VB6, VB9, VB12, and VK exhibited a linear negative association (P for non-linear > 0.05). Subgroup analysis yielded largely consistent results. After confounding factors were adjusted through PSM, the results suggest that the intake of VA, VB2, VB6, and VC remains significantly associated with a lowered risk of sarcopenia (P < 0.05).

Conclusion

Higher dietary levels of VA, VB2, VB6, and VC are significantly related to a lower livelihood of sarcopenia. These findings provide new evidence and insights for early dietary interventions aimed at preventing sarcopenia.

The Unexplored Role of Connexin Hemichannels in Promoting Facioscapulohumeral Muscular Dystrophy Progression

DUX4 is typically a repressed transcription factor, but its aberrant activation in Facioscapulohumeral Muscular Dystrophy (FSHD) leads to cell death by disrupting muscle homeostasis. This disruption affects crucial processes such as myogenesis, sarcolemma integrity, gene regulation, oxidative stress, immune response, and many other biological pathways. Notably, these disrupted processes have been associated, in other pathological contexts, with the presence of connexin (Cx) hemichannels-transmembrane structures that mediate communication between the intracellular and extracellular environments. Thus, hemichannels have been implicated in skeletal muscle atrophy, as observed in human biopsies and animal models of Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Dysferlinopathies, suggesting a potentially shared mechanism of muscle atrophy that has not yet been explored in FSHD. Despite various therapeutic strategies proposed to manage FSHD, no treatment or cure is currently available. This review summarizes the current understanding of the mechanisms underlying FSHD progression, with a focus on hormones, inflammation, reactive oxygen species (ROS), and mitochondrial function. Additionally, it explores the potential of targeting hemichannels as a therapeutic strategy to slow disease progression by preventing the spread of pathogenic factors between muscle cells.

Muscle Proteome Analysis of Facioscapulohumeral Dystrophy Patients Reveals a Metabolic Rewiring Promoting Oxidative/Reductive Stress Contributing to the Loss of Muscle Function

Facioscapulohumeral muscular dystrophy (FSHD) is caused by the epigenetic de-repression of the double homeobox 4 (DUX4) gene, leading to asymmetric muscle weakness and atrophy that begins in the facial and scapular muscles and progresses to the lower limbs. This incurable condition can severely impair muscle function, ultimately resulting in a loss of ambulation. A thorough analysis of molecular factors associated with the varying degrees of muscle impairment in FSHD is still lacking. This study investigates the molecular mechanisms and biomarkers in the biceps brachii of FSHD patients, classified according to the FSHD clinical score, the A-B-C-D classification scheme, and global proteomic variation. Our findings reveal distinct metabolic signatures and compensatory responses in patients. In severe cases, we observe pronounced metabolic dysfunction, marked by dysregulated glycolysis, activation of the reductive pentose phosphate pathway (PPP), a shift toward a reductive TCA cycle, suppression of oxidative phosphorylation, and an overproduction of antioxidants that is not matched by an increase in the redox cofactors needed for their function. This imbalance culminates in reductive stress, exacerbating muscle wasting and inflammation. In contrast, mild cases show metabolic adaptations that mitigate stress by activating polyols and the oxidative PPP, preserving partial energy flow through the oxidative TCA cycle, which supports mitochondrial function and energy balance. Furthermore, activation of the hexosamine biosynthetic pathway promotes autophagy, protecting muscle cells from apoptosis. In conclusion, our proteomic data indicate that specific metabolic alterations characterize both mild and severe FSHD patients. Molecules identified in mild cases may represent potential diagnostic and therapeutic targets for FSHD.

The inverse associations between composite-dietary-antioxidant-index and sarcopenia risk in US adults

BACKGROUND

It remains unknown whether composite-dietary-antioxidant-index (CDAI) is associated with the risk of sarcopenia. This study investigated the association of CDAI with sarcopenia risk among general US adults.

METHODS

A total of 10,093 participants were enrolled in the National Health and Nutrition Examination Surveys (NHANES) from 6 survey cycles (2003-2004, 2005-2006, 2011-2012, 2013-2014, 2015-2016 and 2017-2018). Multivariate logistic regression was carried out to examine the relationship between CDAI and the risk of sarcopenia. Restricted cubic spline (RCS) curves were employed to analyze nonlinear relationships.

RESULTS

In a multi-variable logistic regression model adjusting for demographics, lifestyle, economic status and other dietary factors, higher CDAI score was related to a lower risk of sarcopenia among US adults. Compared the highest quartile of CDAI score with the lowest, the OR and 95%CI were 0.49 (0.31-0.75). Furthermore, the RCS demonstrated a linear dose-response relationship between CDAI and sarcopenia (P non-linearity=0.92). These results remained consistent across subgroups stratified by age, sex, physical activity, drinking status, body mass index (BMI), smoking habits, energy intake, and Healthy Eating Index (HEI) score. In addition, the favorable associations of CDAI were primarily attributed to Vitamin E intake.

CONCLUSION

A higher CDAI score was associated with a lower risk of sarcopenia. According to these results, a greater adherence to CDAI may benefit sarcopenia prevention in adults.

Therapeutic Strategy and Clinical Path of Facioscapulohumeral Muscular Dystrophy: Review of the Current Literature

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant genetic disease, which is caused by the mistaken expression of double homeobox protein 4 protein 4 (DUX4) in skeletal muscle. Patients with FSHD are usually accompanied by degenerative changes in the face, shoulders, and upper muscles, gradually accumulating in the lower limb muscles. The severity of patients is quite different, and most patients end up using wheelchairs and losing their self-care ability. At present, the exploration of treatment strategies for FSHD has shifted from relieving symptoms to gene therapy, which brings hope to the future of patients, but the current gene therapy is only in the clinical trial stage. Here, we conducted a comprehensive search of the relevant literature using the keywords FSHD, DUX4, and gene therapy methods including ASOs, CRISPR, and RNAi in the PubMed and Web of Science databases. We discussed the current advancements in treatment strategies for FSHD, as well as ongoing preclinical and clinical trials related to FSHD. Additionally, we evaluated the advantages and limitations of various gene therapy approaches targeting DUX4 aimed at correcting the underlying genetic defect.

Secondary mitochondrial dysfunction across the spectrum of hereditary and acquired muscle disorders

Mitochondria form a dynamic network within skeletal muscle. This network is not only responsible for producing adenosine triphosphate (ATP) through oxidative phosphorylation, but also responds through fission, fusion and mitophagy to various factors, such as increased energy demands, oxidative stress, inflammation, and calcium dysregulation. Mitochondrial dysfunction in skeletal muscle not only occurs in primary mitochondrial myopathies, but also other hereditary and acquired myopathies. As such, this review attempts to highlight the clinical and histopathologic aspects of mitochondrial dysfunction seen in hereditary and acquired myopathies, as well as discuss potential mechanisms leading to mitochondrial dysfunction and therapies to restore mitochondrial function.

French National Protocol for diagnosis and care of facioscapulohumeral muscular dystrophy (FSHD)

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common genetically inherited myopathies in adults. It is characterized by incomplete penetrance and variable expressivity. Typically, FSHD patients display asymmetric weakness of facial, scapular, and humeral muscles that may progress to other muscle groups, particularly the abdominal and lower limb muscles. Early-onset patients display more severe muscle weakness and atrophy, resulting in a higher frequency of associated skeletal abnormalities. In these patients, multisystem involvement, including respiratory, ocular, and auditory, is more frequent and severe and may include the central nervous system. Adult-onset FSHD patients may also display some degree of multisystem involvement which mainly remains subclinical. In 95% of cases, FSHD patients carry a pathogenic contraction of the D4Z4 repeat units (RUs) in the subtelomeric region of chromosome 4 (4q35), which leads to the expression of DUX4 retrogene, toxic for muscles (FSHD1). Five percent of patients display the same clinical phenotype in association with a mutation in the SMCHD1 gene located in chromosome 18, inducing epigenetic modifications of the 4q D4Z4 repeated region and expression of DUX4 retrogene. This review highlights the complexities and challenges of diagnosing and managing FSHD, underscoring the importance of standardized approaches for optimal patient outcomes. It emphasizes the critical role of multidisciplinary care in addressing the diverse manifestations of FSHD across different age groups, from skeletal abnormalities in early-onset cases to the often-subclinical multisystem involvement in adults. With no current cure, the focus on alleviating symptoms and slowing disease progression through coordinated care is paramount.

Antioxidant Potential of Exosomes in Animal Nutrition

This review delves into the advantages of exosomes as novel antioxidants in animal nutrition and their potential for regulating oxidative stress. Although traditional nutritional approaches promote oxidative stress defense systems in mammalian animals, several issues remain to be solved, such as low bioavailability, targeted tissue efficiency, and high-dose by-effect. As an important candidate offering regulation opportunities concerned with cellular communication, disease prevention, and physiology regulation in multiple biological systems, the potential of exosomes in mediating redox status in biological systems has not been well described. A previously reported relationship between redox system regulation and circulating exosomes suggested exosomes as a fundamental candidate for both a regulator and biomarker for a redox system. Herein, we review the effects of oxidative stress on exosomes in animals and the potential application of exosomes as antioxidants in animal nutrition. Then, we highlight the advantages of exosomes as redox regulators due to their higher bioavailability and physiological heterogeneity-targeted properties, providing a theoretical foundation and feed industry application. Therefore, exosomes have shown great potential as novel antioxidants in the field of animal nutrition. They can overcome the limitations of traditional antioxidants in terms of dosage and side effects, which will provide unprecedented opportunities in nutritional management and disease prevention, and may become a major breakthrough in the field of animal nutrition.

Muscle strength, quantity and quality and muscle fat quantity and their association with oxidative stress in patients with facioscapulohumeral muscular dystrophy: Effect of antioxidant supplementation

The purpose of this study was to identify causes of quadriceps muscle weakness in facioscapulohumeral muscular dystrophy (FSHD). To this aim, we evaluated quadriceps muscle and fat volumes by magnetic resonance imaging and their relationships with muscle strength and oxidative stress markers in adult patients with FSHD (n = 32) and healthy controls (n = 7), and the effect of antioxidant supplementation in 20 of the 32 patients with FSHD (n = 10 supplementation and n = 10 placebo) (NCT01596803). Compared with healthy controls, the dominant quadriceps strength and quality (muscle strength per unit of muscle volume) were decreased in patients with FSHD. In addition, fat volume was increased, without changes in total muscle volume. Moreover, in patients with FSHD, the lower strength of the non-dominant quadriceps was associated with lower muscle quality compared with the dominant muscle. Antioxidant supplementation significantly changed muscle and fat volumes in the non-dominant quadriceps, and muscle quality in the dominant quadriceps. This was associated with improved muscle strength (both quadriceps) and antioxidant response. These findings suggest that quadriceps muscle strength decline may not be simply explained by atrophy and may be influenced also by the muscle intrinsic characteristics. As FSHD is associated with increased oxidative stress, supplementation might reduce oxidative stress and increase antioxidant defenses, promoting changes in muscle function.

Walking test outcomes in adults with genetic neuromuscular diseases: a systematic literature review of their measurement properties

INTRODUCTION

Neuromuscular diseases (NMDs) include a large group of heterogeneous diseases. NMDs frequently involve gait disorders, which affect quality of life. Several walking tests and tools have been described in the literature, but there is no consensus regarding the use of walking tests and tools in NMDs or of their measurement properties for walking outcomes. The aim of this review is to present an overview of walking tests, including their measurement properties when used in adults with inherited or genetic NMDs. The aim is to help clinicians and researchers choose the most appropriate test for their objective.

EVIDENCE ACQUISITION

A systematic review was conducted after consulting MEDLINE (via PubMed), EMBASE, Science direct, Google Scholar and Cochrane Central Register of Controlled Trials databases for published studies in which walking outcome measurement properties were assessed. The validity, reliability, measurement error and responsiveness properties were evaluated in terms of statistical methods and methodological design qualities using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) guidelines.

EVIDENCE SYNTHESIS

We included 46 studies in NMDs. These studies included 15 different walking tests and a wide variety of walking outcomes, assessed with six types of walking tools. Overall, the 6MWT was the most studied test in terms of measurement properties. The methodological design and statistical methods of most studies evaluating construct validity, reliability and measurement error were "very good." The majority of outcome measurements were valid and reliable. However, studies on responsiveness as minimal important difference or minimal important change were lacking or were found to have inadequate methodological and statistical methods according to the COSMIN guidelines.

CONCLUSIONS

Most walking outcomes were found to be valid and reliable in NMDs. However, in view of the growing number of clinical trials, further studies are needed to clarify additional measurement properties.

The DUX4-HIF1α Axis in Murine and Human Muscle Cells: A Link More Complex Than Expected

FacioScapuloHumeral muscular Dystrophy (FSHD) is one of the most prevalent inherited muscle disorders and is linked to the inappropriate expression of the DUX4 transcription factor in skeletal muscles. The deregulated molecular network causing FSHD muscle dysfunction and pathology is not well understood. It has been shown that the hypoxia response factor HIF1α is critically disturbed in FSHD and has a major role in DUX4-induced cell death. In this study, we further explored the relationship between DUX4 and HIF1α. We found that the DUX4 and HIF1α link differed according to the stage of myogenic differentiation and was conserved between human and mouse muscle. Furthermore, we found that HIF1α knockdown in a mouse model of DUX4 local expression exacerbated DUX4-mediated muscle fibrosis. Our data indicate that the suggested role of HIF1α in DUX4 toxicity is complex and that targeting HIF1α might be challenging in the context of FSHD therapeutic approaches.

Associations of micronutrient dietary patterns with sarcopenia among US adults: a population-based study

Background

Current epidemiological evidence points to an association between micronutrient (MN) intake and sarcopenia, but studies have focused on single MN, and no combined effects on MNs have been reported. The aim of this study was to investigate the relationship between different MN intake patterns and sarcopenia and skeletal muscle mass.

Methods

We performed a population-based cross-sectional study, with a total of 5,256 U.S. adults aged 20-59 years, and we collected total daily MN intake and appendicular skeletal muscle mass measured by Dual-Energy X-ray Absorptiometry (DXA). Principal component analysis (PCA) was used to obtain nutrient patterns and principal component scores based on the intake of 14 MNs, and logistic regression analysis was used to assess the effects of single MN and MN intake patterns on sarcopenia and muscle mass.

Results

We defined three MN intake patterns by PCA: (1) adherence to VitB-mineral, high intake of vitamin B and minerals; (2) adherence to VitAD-Ca-VB12, high intake of vitamin A, vitamin D, calcium and vitamin B12; and (3) adherence to Antioxidant Vit, high intake of antioxidant vitamins A, C, E, and K. These three nutrient patterns explained 73.26% of the variance of the population. A negative association was observed between most single MN intakes and sarcopenia, and after adjusting for confounders, adherence to the highest tertile of the three nutrient patterns was associated with a lower risk of sarcopenia and relatively higher skeletal muscle mass compared to the lowest adherence. In subgroup analysis, MN intake patterns were significantly correlated with sarcopenia in middle-aged females.

Conclusion

Nutritional patterns based on MN intake were significantly related to sarcopenia, indicating that MNs interact with each other while exerting their individual functions, and that MN dietary patterns may provide promising strategies for preventing the loss of muscle mass, with further prospective studies warranted in the future.

Facioscapulohumeral Muscular Dystrophy European Patient Survey: Assessing Patient Reported Disease Burden and Preferences in Clinical Trial Participation

Background

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disorder characterized by progressive muscle weakness leading to permanent disability. There are no curative treatments, however, there are several upcoming clinical trials testing new therapies in FSHD.

Objective

This study aimed to explore the disease burden and patient preferences of people with FSHD to ensure that clinical trials can be designed to include outcome measures that are relevant and important to patients.

Methods

A survey was developed with a steering committee clinicians and physiotherapists with relevant experience in the disease, patient representatives, a registry expert and industry consultants. Themes of the survey included; participant demographics, disease progression and impact on function, factors encouraging or discouraging clinical trial participation, and positive outcomes of a clinical trial.

Results

1147 participants responded to the online survey, representing 26 countries across Europe and a range of disease severities. The study highlighted the key symptoms causing concern for FSHD patients - muscle weakness and mobility issues - reflecting what participants want targeted for future therapies. The need for clear information and communication throughout clinical trials was emphasised. Factors most encouraging trial participation included access to new investigational therapies, access to trial results and benefits for the FSHD community. Factors most discouraging trial participation included travel related issues and fear of side effects.

Conclusions

The results from this study identify the patient reported burden of FSHD and should provide researchers and industry with areas of therapeutic research that would be meaningful to patients, as well as supporting the development of patient centric outcome measures in clinical trials.

MATR3 is an endogenous inhibitor of DUX4 in FSHD muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common neuromuscular disorders and has no cure. Due to an unknown molecular mechanism, FSHD displays overlapping manifestations with the neurodegenerative disease amyotrophic lateral sclerosis (ALS). FSHD is caused by aberrant gain of expression of the transcription factor double homeobox 4 (DUX4), which triggers a pro-apoptotic transcriptional program resulting in inhibition of myogenic differentiation and muscle wasting. Regulation of DUX4 activity is poorly known. We identify Matrin 3 (MATR3), whose mutation causes ALS and dominant distal myopathy, as a cellular factor controlling DUX4 expression and activity. MATR3 binds to the DUX4 DNA-binding domain and blocks DUX4-mediated gene expression, rescuing cell viability and myogenic differentiation of FSHD muscle cells, without affecting healthy muscle cells. Finally, we characterize a shorter MATR3 fragment that is necessary and sufficient to directly block DUX4-induced toxicity to the same extent as the full-length protein. Collectively, our data suggest MATR3 as a candidate for developing a treatment for FSHD.

Facioscapulohumeral Muscular Dystrophy is Associated With Altered Myoblast Proteome Dynamics

Proteomic studies in facioscapulohumeral muscular dystrophy (FSHD) could offer new insight into disease mechanisms underpinned by post-transcriptional processes. We used stable isotope (deuterium oxide; D2O) labeling and peptide mass spectrometry to investigate the abundance and turnover rates of proteins in cultured muscle cells from two individuals affected by FSHD and their unaffected siblings (UASb). We measured the abundance of 4420 proteins and the turnover rate of 2324 proteins in each (n = 4) myoblast sample. FSHD myoblasts exhibited a greater abundance but slower turnover rate of subunits of mitochondrial respiratory complexes and mitochondrial ribosomal proteins, which may indicate an accumulation of "older" less viable mitochondrial proteins in myoblasts from individuals affected by FSHD. Treatment with a 2'-O-methoxyethyl modified antisense oligonucleotide targeting exon 3 of the double homeobox 4 (DUX4) transcript tended to reverse mitochondrial protein dysregulation in FSHD myoblasts, indicating the effect on mitochondrial proteins may be a DUX4-dependent mechanism. Our results highlight the importance of post-transcriptional processes and protein turnover in FSHD pathology and provide a resource for the FSHD research community to explore this burgeoning aspect of FSHD.

Advances in nutritional supplementation for sarcopenia management

Sarcopenia is a syndrome characterized by a decline in muscular mass, strength, and function with advancing age. The risk of falls, fragility, hospitalization, and death is considerably increased in the senior population due to sarcopenia. Although there is no conclusive evidence for drug treatment, resistance training has been unanimously recognized as a first-line treatment for managing sarcopenia, and numerous studies have also pointed to the combination of nutritional supplementation and resistance training as a more effective intervention to improve quality of life for people with sarcopenia. People with both malnutrition and sarcopenia have a higher mortality rate, so identifying people at risk of malnutrition and intervening early is extremely important to avoid sarcopenia and its associated problems. This article provides important information for dietary interventions in sarcopenia by summarizing the discoveries and developments of nutritional supplements such as protein, leucine, β-hydroxy-β-methylbutyric acid, vitamin D, vitamin C, vitamin E, omega-3 fatty acids, creatine, inorganic nitrate, probiotics, minerals, collagen peptides, and polyphenols in the management of sarcopenia.

Treatment of Facioscapulohumeral Muscular Dystrophy (FSHD): A Systematic Review

Facioscapulohumeral muscular dystrophy (FSHD) is the third most common type of muscular dystrophy. This disease presents as a slowly progressive asymmetric muscle weakness that involves the facial, scapular, and upper arm muscles mainly. Currently, there is no established consensus on this disease treatment in terms of medications. We assessed the response to the treatment of the drugs utilized in clinical trials by performing a systematic literature review in English using the preferred reporting items for systematic reviews (PRISMA) and meta-analyses. We only used human clinical trials in patients diagnosed with FSHD that received consistent pharmacological treatment. We included 11 clinical trials that fulfilled our criteria. We concluded that albuterol had statistically significant results in three out of four clinical trials, with improved elbow flexors muscle strength. Vitamin C, vitamin E, zinc gluconate, and selenomethionine showed significant improvement in the maximal voluntary contraction and endurance limit time of quadriceps muscle. At the same time, diltiazem and MYO-029 demonstrate no improvement in function, strength, or muscle mass. Losmapimod, currently in phase I of the ReDUX4 trial, showed promising results. Peradventure, more clinical trials are still needed to address this subject. Nevertheless, this review provides a clear and concise update on the treatment for this disease.

Influence of DUX4 Expression in Facioscapulohumeral Muscular Dystrophy and Possible Treatments

Facioscapulohumeral muscular dystrophy (FSHD) represents the third most common form of muscular dystrophy and is characterized by muscle weakness and atrophy. FSHD is caused by the altered expression of the transcription factor double homeobox 4 (DUX4), which is involved in several significantly altered pathways required for myogenesis and muscle regeneration. While DUX4 is normally silenced in the majority of somatic tissues in healthy individuals, its epigenetic de-repression has been linked to FSHD, resulting in DUX4 aberrant expression and cytotoxicity in skeletal muscle cells. Understanding how DUX4 is regulated and functions could provide useful information not only to further understand FSHD pathogenesis, but also to develop therapeutic approaches for this disorder. Therefore, this review discusses the role of DUX4 in FSHD by examining the possible molecular mechanisms underlying the disease as well as novel pharmacological strategies targeting DUX4 aberrant expression.

Cystatin C for kidney function assessment in patients with facioscapulohumeral muscular dystrophy

BACKGROUND AND AIMS

Muscle mass (MM) impairment observed in facioscapulohumeral muscular dystrophy (FSHD) may bias estimated glomerular filtration rate (eGFR) based on creatinine (eGFRcreat). eGFR based on cystatin C (eGFRcys), produced by all nucleated cells, should be an interesting alternative. Main objectives were to compare eGFRcreat and eGRFcys for chronic kidney disease (CKD) staging and for annual eGFR evolution. Secondary objective was to analyse creatinine, cystatin C with measured MM.

MATERIAL AND METHODS

During 4 years, 159 FSHD patients having one or more creatinine and cystatin C measurements (total samples: n=379), with MM determination by bio-impedancemetry during their follow-up were included. eGFR were determined with CKD-Epi and EKFC equations.

RESULTS

On first examination samples, mean eGFRcys was significantly lower than mean eGFRcreat of 25.5 and 17.9 ml/min/1.73m² using CKD-Epi and EKFC equations, respectively. 53.5% (CKD-Epi) and 59.1% (EKFC) of agreement were obtained when using eGFRcys instead of eGFRcreat with reclassifications occurring mainly towards more severe stages. Age was correlated with cystatin C but not with creatinine, MM was correlated with creatinine but not with cystatin C. eGFR decreases >1 ml/min/1.73m² were more important when using eGFRcys instead of eGFRcreat (CKD-Epi: 37.5 vs 15.4%, p<0.001; EKFC: 34.6 vs 20.2%, p<0.01).

CONCLUSION

Cystatin C which is independent of MM appears as a promising candidate biomarker for CKD diagnosis and follow-up in FSHD patient.

Nutritional Status of Patients with Facioscapulohumeral Muscular Dystrophy

In patients with facioscapulohumeral muscular dystrophy (FSHD), a rare genetic neuromuscular disease, reduced physical performance is associated with lower blood levels of vitamin C, zinc, selenium, and increased oxidative stress markers. Supplementation of vitamin C, vitamin E, zinc, and selenium improves the quadriceps' physical performance. Here, we compared the nutritional status of 74 women and 85 men with FSHD. Calorie intake was lower in women with FSHD than in men. Moreover, we assessed vitamin C, vitamin E, zinc, copper, and selenium intakes in diet and their concentrations in the plasma. Vitamin E, copper, and zinc intake were lower in women with FSHD than in men, whereas plasma vitamin C, copper levels, and copper/zinc ratio were higher in women with FSHD than in men. The dietary intake and plasma concentrations of the studied vitamins and minerals were not correlated in both sexes. A well-balanced and varied diet might not be enough in patients with FSHD to correct the observed vitamin/mineral deficiencies. A low energy intake is a risk factor for suboptimal intake of proteins, vitamins, and minerals that are important for protein synthesis and other metabolic pathways and that might contribute to progressive muscle mass loss. Antioxidant supplementation and higher protein intake seem necessary to confer protection against oxidative stress and skeletal muscle mass loss.

Vitamin E and Metabolic Health: Relevance of Interactions with Other Micronutrients

A hundred years have passed since vitamin E was identified as an essential micronutrient for mammals. Since then, many biological functions of vitamin E have been unraveled in both cell and animal models, including antioxidant and anti-inflammatory properties, as well as regulatory activities on cell signaling and gene expression. However, the bioavailability and physiological functions of vitamin E have been considerably shown to depend on lifestyle, genetic factors, and individual health conditions. Another important facet that has been considered less so far is the endogenous interaction with other nutrients. Accumulating evidence indicates that the interaction between vitamin E and other nutrients, especially those that are enriched by supplementation in humans, may explain at least some of the discrepancies observed in clinical trials. Meanwhile, increasing evidence suggests that the different forms of vitamin E metabolites and derivates also exhibit physiological activities, which are more potent and mediated via different pathways compared to the respective vitamin E precursors. In this review, possible molecular mechanisms between vitamin E and other nutritional factors are discussed and their potential impact on physiological and pathophysiological processes is evaluated using published co-supplementation studies.

ANT1 overexpression models: Some similarities with facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disorder characterized by progressive muscle weakness. Adenine nucleotide translocator 1 (ANT1), the only 4q35 gene involved in mitochondrial function, is strongly expressed in FSHD skeletal muscle biopsies. However, its role in FSHD is unclear. In this study, we evaluated ANT1 overexpression effects in primary myoblasts from healthy controls and during Xenopus laevis organogenesis. We also compared ANT1 overexpression effects with the phenotype of FSHD muscle cells and biopsies. Here, we report that the ANT1 overexpression-induced phenotype presents some similarities with FSHD muscle cells and biopsies. ANT1-overexpressing muscle cells showed disorganized morphology, altered cytoskeletal arrangement, enhanced mitochondrial respiration/glycolysis, ROS production, oxidative stress, mitochondrial fragmentation and ultrastructure alteration, as observed in FSHD muscle cells. ANT1 overexpression in Xenopus laevis embryos affected skeletal muscle development, impaired skeletal muscle, altered mitochondrial ultrastructure and led to oxidative stress as observed in FSHD muscle biopsies. Moreover, ANT1 overexpression in X. laevis embryos affected heart structure and mitochondrial ultrastructure leading to cardiac arrhythmia, as described in some patients with FSHD. Overall our data suggest that ANT1 could contribute to mitochondria dysfunction and oxidative stress in FSHD muscle cells by modifying their bioenergetic profile associated with ROS production. Such interplay between energy metabolism and ROS production in FSHD will be of significant interest for future prospects.

FSHD Therapeutic Strategies: What Will It Take to Get to Clinic?

Facioscapulohumeral muscular dystrophy (FSHD) is arguably one of the most challenging genetic diseases to understand and treat. The disease is caused by epigenetic dysregulation of a macrosatellite repeat, either by contraction of the repeat or by mutations in silencing proteins. Both cases lead to chromatin relaxation and, in the context of a permissive allele, pathogenic misexpression of DUX4 in skeletal muscle. The complex nature of the locus and the fact that FSHD is a toxic, gain-of-function disease present unique challenges for the design of therapeutic strategies. There are three major DUX4-targeting avenues of therapy for FSHD: small molecules, oligonucleotide therapeutics, and CRISPR-based approaches. Here, we evaluate the preclinical progress of each avenue, and discuss efforts being made to overcome major hurdles to translation.

Interplay between mitochondrial reactive oxygen species, oxidative stress and hypoxic adaptation in facioscapulohumeral muscular dystrophy: Metabolic stress as potential therapeutic target

Facioscapulohumeral muscular dystrophy (FSHD) is characterised by descending skeletal muscle weakness and wasting. FSHD is caused by mis-expression of the transcription factor DUX4, which is linked to oxidative stress, a condition especially detrimental to skeletal muscle with its high metabolic activity and energy demands. Oxidative damage characterises FSHD and recent work suggests metabolic dysfunction and perturbed hypoxia signalling as novel pathomechanisms. However, redox biology of FSHD remains poorly understood, and integrating the complex dynamics of DUX4-induced metabolic changes is lacking. Here we pinpoint the kinetic involvement of altered mitochondrial ROS metabolism and impaired mitochondrial function in aetiology of oxidative stress in FSHD. Transcriptomic analysis in FSHD muscle biopsies reveals strong enrichment for pathways involved in mitochondrial complex I assembly, nitrogen metabolism, oxidative stress response and hypoxia signalling. We found elevated mitochondrial ROS (mitoROS) levels correlate with increases in steady-state mitochondrial membrane potential in FSHD myogenic cells. DUX4 triggers mitochondrial membrane polarisation prior to oxidative stress generation and apoptosis through mitoROS, and affects mitochondrial health through lipid peroxidation. We identify complex I as the primary target for DUX4-induced mitochondrial dysfunction, with strong correlation between complex I-linked respiration and cellular oxygenation/hypoxia signalling activity in environmental hypoxia. Thus, FSHD myogenesis is uniquely susceptible to hypoxia-induced oxidative stress as a consequence of metabolic mis-adaptation. Importantly, mitochondria-targeted antioxidants rescue FSHD pathology more effectively than conventional antioxidants, highlighting the central involvement of disturbed mitochondrial ROS metabolism. This work provides a pathomechanistic model by which DUX4-induced changes in oxidative metabolism impair muscle function in FSHD, amplified when metabolic adaptation to varying O2 tension is required.

Outcome Measures in Facioscapulohumeral Muscular Dystrophy Clinical Trials

Facioscapulohumeral muscular dystrophy (FSHD) is a debilitating muscular dystrophy with a variable age of onset, severity, and progression. While there is still no cure for this disease, progress towards FSHD therapies has accelerated since the underlying mechanism of epigenetic derepression of the double homeobox 4 (DUX4) gene leading to skeletal muscle toxicity was identified. This has facilitated the rapid development of novel therapies to target DUX4 expression and downstream dysregulation that cause muscle degeneration. These discoveries and pre-clinical translational studies have opened new avenues for therapies that await evaluation in clinical trials. As the field anticipates more FSHD trials, the need has grown for more reliable and quantifiable outcome measures of muscle function, both for early phase and phase II and III trials. Advanced tools that facilitate longitudinal clinical assessment will greatly improve the potential of trials to identify therapeutics that successfully ameliorate disease progression or permit muscle functional recovery. Here, we discuss current and emerging FSHD outcome measures and the challenges that investigators may experience in applying such measures to FSHD clinical trial design and implementation.

RIPK3-mediated cell death is involved in DUX4-mediated toxicity in facioscapulohumeral dystrophy

BACKGROUND

Facioscapulohumeral dystrophy (FSHD) is caused by mutations leading to the aberrant expression of the DUX4 transcription factor in muscles. DUX4 was proposed to induce cell death, but the involvement of different death pathways is still discussed. A possible pro-apoptotic role of DUX4 was proposed, but as FSHD muscles are characterized by necrosis and inflammatory infiltrates, non-apoptotic pathways may be also involved.

METHODS

We explored DUX4-mediated cell death by focusing on the role of one regulated necrosis pathway called necroptosis, which is regulated by RIPK3. We investigated the effect of necroptosis on cell death in vitro and in vivo experiments using RIPK3 inhibitors and a RIPK3-deficient transgenic mouse model.

RESULTS

We showed in vitro that DUX4 expression causes a caspase-independent and RIPK3-mediated cell death in both myoblasts and myotubes. In vivo, RIPK3-deficient animals present improved body and muscle weights, a reduction of the aberrant activation of the DUX4 network genes, and an improvement of muscle histology.

CONCLUSIONS

These results provide evidence for a role of RIPK3 in DUX4-mediated cell death and open new avenues of research.

DUX4 Role in Normal Physiology and in FSHD Muscular Dystrophy

In the last decade, the sequence-specific transcription factor double homeobox 4 (DUX4) has gone from being an obscure entity to being a key factor in important physiological and pathological processes. We now know that expression of DUX4 is highly regulated and restricted to the early steps of embryonic development, where DUX4 is involved in transcriptional activation of the zygotic genome. While DUX4 is epigenetically silenced in most somatic tissues of healthy humans, its aberrant reactivation is associated with several diseases, including cancer, viral infection and facioscapulohumeral muscular dystrophy (FSHD). DUX4 is also translocated, giving rise to chimeric oncogenic proteins at the basis of sarcoma and leukemia forms. Hence, understanding how DUX4 is regulated and performs its activity could provide relevant information, not only to further our knowledge of human embryonic development regulation, but also to develop therapeutic approaches for the diseases associated with DUX4. Here, we summarize current knowledge on the cellular and molecular processes regulated by DUX4 with a special emphasis on FSHD muscular dystrophy.

Key points for the development of antioxidant cocktails to prevent cellular stress and damage caused by reactive oxygen species (ROS) during manned space missions

Exposure to microgravity and ionizing radiation during spaceflight missions causes excessive reactive oxygen species (ROS) production that contributes to cellular stress and damage in astronauts. Average spaceflight mission time is expected to lengthen as humanity aims to visit other planets. However, longer missions or spaceflights will undoubtedly lead to an increment in microgravity, ionizing radiation and ROS production. Strategies to minimize ROS damage are necessary to maintain the health of astronauts, future space colonists, and tourists during and after spaceflight missions. An antioxidant cocktail formulated to prevent or mitigate ROS damage during space exploration could help maintain the health of space explorers. We propose key points to consider when developing an antioxidant cocktail. We discuss how ROS damages our body and organs, the genetic predisposition of astronauts to its damage, characteristics and evidence of the effectiveness of antioxidants to combat excess ROS, differences in drug metabolism when on Earth and in space that could modify antioxidant effects, and the characteristics and efficacy of common antioxidants. Based on this information we propose a workflow for assessing astronaut resistance to ROS damage, infight monitoring of ROS production, and an antioxidant cocktail. Developing an antioxidant cocktail represents a big challenge to translate current medical practices from an Earth setting to space. The key points presented in this review could promote the development of different antioxidant formulations to maintain space explorers' health in the future.

Pathomechanisms and biomarkers in facioscapulohumeral muscular dystrophy: roles of DUX4 and PAX7

Facioscapulohumeral muscular dystrophy (FSHD) is characterised by progressive skeletal muscle weakness and wasting. FSHD is linked to epigenetic derepression of the subtelomeric D4Z4 macrosatellite at chromosome 4q35. Epigenetic derepression permits the distal-most D4Z4 unit to transcribe DUX4, with transcripts stabilised by splicing to a poly(A) signal on permissive 4qA haplotypes. The pioneer transcription factor DUX4 activates target genes that are proposed to drive FSHD pathology. While this toxic gain-of-function model is a satisfying "bottom-up" genotype-to-phenotype link, DUX4 is rarely detectable in muscle and DUX4 target gene expression is inconsistent in patients. A reliable biomarker for FSHD is suppression of a target gene score of PAX7, a master regulator of myogenesis. However, it is unclear how this "top-down" finding links to genomic changes that characterise FSHD and to DUX4. Here, we explore the roles and interactions of DUX4 and PAX7 in FSHD pathology and how the relationship between these two transcription factors deepens understanding via the immune system and muscle regeneration. Considering how FSHD pathomechanisms are represented by "DUX4opathy" models has implications for developing therapies and current clinical trials.

Hypoxia and Hypoxia-Inducible Factor Signaling in Muscular Dystrophies: Cause and Consequences

Muscular dystrophies (MDs) are a group of inherited degenerative muscle disorders characterized by a progressive skeletal muscle wasting. Respiratory impairments and subsequent hypoxemia are encountered in a significant subgroup of patients in almost all MD forms. In response to hypoxic stress, compensatory mechanisms are activated especially through Hypoxia-Inducible Factor 1 α (HIF-1α). In healthy muscle, hypoxia and HIF-1α activation are known to affect oxidative stress balance and metabolism. Recent evidence has also highlighted HIF-1α as a regulator of myogenesis and satellite cell function. However, the impact of HIF-1α pathway modifications in MDs remains to be investigated. Multifactorial pathological mechanisms could lead to HIF-1α activation in patient skeletal muscles. In addition to the genetic defect per se, respiratory failure or blood vessel alterations could modify hypoxia response pathways. Here, we will discuss the current knowledge about the hypoxia response pathway alterations in MDs and address whether such changes could influence MD pathophysiology.

Stimulation of myogenesis by ascorbic acid and capsaicin

Myogenesis is a complex process regulated by several factors. This study evaluated the functional interaction between vitamin C and a high dose of capsaicin (a potential endoplasmic reticulum (ER) stress inducer) on myogenesis. After the induction of differentiation, treatment with ascorbic acid or ascorbic acid phosphate (AsAp) alone had minimal effects on myogenesis in C2C12 cells. However, treatment with capsaicin (300 μM) in undifferentiated C2C12 cells increased the expression levels of genes related to ER stress as well as oxidative stress. Myogenesis was effectively enhanced in C2C12 cells treated with a combination of capsaicin (300 μM) for one day before differentiation stimulation and AsAp for four days post-differentiation; subsequently, thick and long myotubes formed, and the expression levels of myosin heavy chain (MYH) 1/2 and Myh1, Myh4, and Myh7 increased. Considering that mild ER stress stimulates myogenesis, AsAp may elicit myogenesis through the alleviation of oxidative stress-induced negative effects in capsaicin-pretreated cells. The enhanced expression of Myh1 and Myh4 coincided with the expression of Col1a1, a type I collagen, suggesting that the fine-tuning of the myogenic cell microenvironment is responsible for efficient myogenesis. Our results indicate that vitamin C is a potential stimulator of myogenesis in cells, depending on the cell context.

Redox Homeostasis in Muscular Dystrophies

In recent years, growing evidence has suggested a prominent role of oxidative stress in the pathophysiology of several early- and adult-onset muscle disorders, although effective antioxidant treatments are still lacking. Oxidative stress causes cell damage by affecting protein function, membrane structure, lipid metabolism, and DNA integrity, thus interfering with skeletal muscle homeostasis and functionality. Some features related to oxidative stress, such as chronic inflammation, defective regeneration, and mitochondrial damage are shared among most muscular dystrophies, and Nrf2 has been shown to be a central player in antagonizing redox imbalance in several of these disorders. However, the exact mechanisms leading to overproduction of reactive oxygen species and deregulation in the cellular antioxidants system seem to be, to a large extent, disease-specific, and the clarification of these mechanisms in vivo in humans is the cornerstone for the development of targeted antioxidant therapies, which will require testing in appropriately designed clinical trials.

Analysis of genes regulated by DUX4 via oxidative stress reveals potential therapeutic targets for treatment of facioscapulohumeral dystrophy

Muscles of patients with facioscapulohumeral dystrophy (FSHD) are characterized by sporadic DUX4 expression and oxidative stress which is at least partially induced by DUX4 protein. Nevertheless, targeting oxidative stress with antioxidants has a limited impact on FSHD patients, and the exact role of oxidative stress in the pathology of FSHD, as well as its interplay with the DUX4 expression, remain unclear. Here we set up a screen for genes that are upregulated by DUX4 via oxidative stress with the aim to target these genes rather than the oxidative stress itself. Immortalized human myoblasts expressing DUX4 (MB135-DUX4) have an increased level of reactive oxygen species (ROS) and exhibit differentiation defects which can be reduced by treating the cells with classic (Tempol) or mitochondria-targeted antioxidants (SkQ1). The transcriptome analysis of antioxidant-treated MB135 and MB135-DUX4 myoblasts allowed us to identify 200 genes with expression deregulated by DUX4 but normalized upon antioxidant treatment. Several of these genes, including PITX1, have been already associated with FSHD and/or muscle differentiation. We confirmed that PITX1 was indeed deregulated in MB135-DUX4 cells and primary FSHD myoblasts and revealed a redox component in PITX1 regulation. PITX1 silencing partially reversed the differentiation defects of MB135-DUX4 myoblasts. Our approach can be used to identify and target redox-dependent genes involved in human diseases.

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Double homeobox transcription factor DUX4 misregulates hundreds of genes and induces oxidative stress in human myoblasts.

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ROS, notably those of mitochondrial origin, contribute to the differentiation defects in myoblasts expressing DUX4.

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A subset of genes is deregulated by DUX4 indirectly, via oxidative stress.

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A strategy to identify the genes deregulated by DUX4 via oxidative stress was developed.

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PITX1 is deregulated by DUX4 via oxidative stress and can be targeted to improve myogenesis in DUX4-expressing myoblasts.

Facioscapulohumeral muscular dystrophy: genetics, gene activation and downstream signalling with regard to recent therapeutic approaches: an update

Whilst a disease-modifying treatment for Facioscapulohumeral muscular dystrophy (FSHD) does not exist currently, recent advances in complex molecular pathophysiology studies of FSHD have led to possible therapeutic approaches for its targeted treatment. Although the underlying genetics of FSHD have been researched extensively, there remains an incomplete understanding of the pathophysiology of FSHD in relation to the molecules leading to DUX4 gene activation and the downstream gene targets of DUX4 that cause its toxic effects. In the context of the local proximity of chromosome 4q to the nuclear envelope, a contraction of the D4Z4 macrosatellite induces lower methylation levels, enabling the ectopic expression of DUX4. This disrupts numerous signalling pathways that mostly result in cell death, detrimentally affecting skeletal muscle in affected individuals. In this regard different options are currently explored either to suppress the transcription of DUX4 gene, inhibiting DUX4 protein from its toxic effects, or to alleviate the symptoms triggered by its numerous targets.

Nitrosative Redox Homeostasis and Antioxidant Response Defense in Disused Vastus lateralis Muscle in Long-Term Bedrest (Toulouse Cocktail Study)

Increased oxidative stress by reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a major determinant of disuse-induced muscle atrophy. Muscle biopsies (thigh vastus lateralis, VL) obtained from healthy male subjects enrolled in the Toulouse Cocktail bedrest (BR) study were used to assess efficacy of an antioxidant cocktail (polyphenols, omega-3, vitamin E, and selenium) to counteract the increased redox homeostasis and enhance the antioxidant defense response by using label-free LC–MS/MS and NITRO-DIGE (nitrosated proteins), qPCR, and laser confocal microscopy. Label-free LC–MS/MS indicated that treatment prevented the redox homeostasis dysregulation and promoted structural remodeling (TPM3, MYH7, MYBPC, MYH1, MYL1, HRC, and LUM), increment of RyR1, myogenesis (CSRP3), and skeletal muscle development (MUSTN1, LMNA, AHNAK). These changes were absent in the Placebo group. Glycolysis, tricarboxylic acid cycle (TCA), oxidative phosphorylation, fatty acid beta-oxidation, and mitochondrial transmembrane transport were normalized in treated subjects. Proteins involved in protein folding were also normalized, whereas protein entailed in ion homeostasis decreased. NITRO-DIGE analysis showed significant protein nitrosylation changes for CAT, CA3, SDHA, and VDAC2 in Treatment vs. Placebo. Similarly, the nuclear factor erythroid 2-related factor 2 (Nrf-2) antioxidant response element (Nrf-2 ARE) signaling pathway showed an enhanced response in the Treatment group. Increased nitrosative redox homeostasis and decreased antioxidant defense response were found in post-BR control (Placebo, n = 10) vs. the antioxidant cocktail treated group (Treatment, n = 10). Taken together, increased nitrosative redox homeostasis and muscle deterioration during BR-driven physical inactivity were prevented, whereas decreased antioxidant nitrosative stress defense response was attenuated by Treatment suggesting positive effects of the nutritional intervention protocol in bedrest.

Current Therapeutic Approaches in FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies. Over the last decade, a consensus was reached regarding the underlying cause of FSHD allowing—for the first time—a targeted approach to treatment. FSHD is the result of a toxic gain-of-function from de-repression of the DUX4 gene, a gene not normally expressed in skeletal muscle. With a clear therapeutic target, there is increasing interest in drug development for FSHD, an interest buoyed by the recent therapeutic successes in other neuromuscular diseases. Herein, we review the underlying disease mechanism, potential therapeutic approaches as well as the state of trial readiness in the planning and execution of future clinical trials in FSHD.

Therapeutic Approaches in Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common types of muscular dystrophy, affecting roughly one in 8000 individuals. The complex underlying genetics and poor mechanistic understanding has caused a bottleneck in therapeutic development. Until the discovery of DUX4 and its causal role in FSHD, most trials were untargeted with limited results. Emerging approaches can learn from these early trials to increase their chance of success. Here, we explore the evolution of FSHD clinical trials from nonspecific anabolic or anti-inflammatory/oxidant strategies to cutting-edge molecular therapies targeting DUX4, and we discuss the importance of clinical outcome measures. With combined advances across multiple facets of FSHD research, the field is now poised to accelerate the process of therapeutic discovery and testing.

Promising Perspective to Facioscapulohumeral Muscular Dystrophy Treatment: Nutraceuticals and Phytochemicals

Facioscapulohumeral Muscular Dystrophy (FSHD) is in the top three list of all dystrophies with an approximate 1:8000 incidence. It is not a life-threatening disease; however, the progression of the disease extends over being wheelchair bound. Despite some drug trials continuing, including DUX4 inhibition, TGF-ß inhibition and resokine which promote healthier muscle, there is not an applicable treatment option for FSHD today. Still, there is a need for new agents to heal, stop or at least slow down muscle wasting. Current FSHD studies involving nutraceuticals as vitamin C, vitamin E, coenzyme Q10, zinc, selenium, and phytochemicals as curcumin or genistein, daidzein flavonoids provide promising treatment strategies. In this review, we present the clinical and molecular nature of FSHD and focus on nutraceuticals and phytochemicals that may alleviate FSHD. In the light of the association of impaired pathophysiological FSHD pathways with nutraceuticals and phytochemicals according to the literature, we present both studied and novel approaches that can contribute to FSHD treatment.

Antagonistic effects of nano-selenium on broilers hepatic injury induced by Cr(VI) poisoning in AMPK pathway

Cr (chromium, with common valence states of III and VI) is one of the common broiler feed additives. Liver injury and metabolic disorders could be caused by Cr_(VI) (hexavalent chromium) poisoning in broilers. Oxidative damage and metabolic disorders of organisms caused by heavy metals could be antagonized by nano-Se (nano-selenium). Nano-Se was chosen to study the antagonism of Cr_(VI) poisoning in broilers. AMPK (Adenosine 5^,-monophosphate-activated protein kinase) is known as a "cell energy regulator" and plays a key regulatory role in carbohydrate and lipid metabolism. AMPK pathway and ACACA/CPT1A two genes were selected to study the prevention and treatment of nano-Se on Cr_(VI) poisoning in broilers and its molecular mechanism. For this purpose, 180 1-day-old AA (Arbor Acres) broilers were selected and randomly divided into 6 groups (n = 30) for further testing. After feeding as planned for 35 days, the livers of such broilers were taken for further examination including histopathological examination, differential gene expression analysis, and further validation on both mRNA and protein levels using related techniques like RT-qPCR, western blot, and immunohistochemistry (IHC). The histopathological examination suggested that the liver cells of the Cr_(VI) poisoning group were more severely injured than the nano-Se addition group. RT-qPCR results showed that the relative expression of ACACA gene in the Cr_(VI) poisoning group was significantly increased (P < 0.05), while the CPT1A gene's expression was significantly decreased (P < 0.01). Those results were reversed in the nano-Se addition group. Western blot results were consistent with RT-qPCR and both suggested antagonism of nano-Se on Cr_(VI). Through morphological and histopathological observation, as well as the measurement of the mRNA and protein expression levels of ACACA and CPT1A genes in AMPK pathway, it was confirmed that nano-Se has certain preventive and protective effects on Cr_(VI) poisoning in broiler chickens. Furthermore, the adverse effects of Cr_(VI) on carbohydrate and lipid metabolism in broilers can be antagonized by nano-Se through AMPK pathway. A new method and experimental basis were provided to the future study of Cr_(VI) poisoning in broilers.

Early-Onset Infantile Facioscapulohumeral Muscular Dystrophy: A Timely Review

Facioscapulohumeral muscular dystrophy (FSHD)-the worldwide third most common inherited muscular dystrophy caused by the heterozygous contraction of a 3.3 kb tandem repeat (D4Z4) on a chromosome with a 4q35 haplotype-is a progressive genetic myopathy with variable onset of symptoms, distribution of muscle weakness, and clinical severity. While much is known about the clinical course of adult FSHD, data on the early-onset infantile phenotype, especially on the progression of the disease, are relatively scarce. Contrary to the classical form, patients with infantile FSHD more often have a rapid decline in muscle wasting and systemic features with multiple extramuscular involvements. A rough correlation between the phenotypic severity of FSHD and the D4Z4 repeat size has been reported, and the majority of patients with infantile FSHD obtain a very short D4Z4 repeat length (one to three copies, EcoRI size 10-14 kb), in contrast to the classical, slowly progressive, form of FSHD (15-38 kb). With the increasing identifications of case reports and the advance in genetic diagnostics, recent studies have suggested that the infantile variant of FSHD is not a genetically separate entity but a part of the FSHD spectrum. Nevertheless, many questions about the clinical phenotype and natural history of infantile FSHD remain unanswered, limiting evidence-based clinical management. In this review, we summarize the updated research to gain insight into the clinical spectrum of infantile FSHD and raise views to improve recognition and understanding of its underlying pathomechanism, and further, to advance novel treatments and standard care methods.

The prospects of targeting DUX4 in facioscapulohumeral muscular dystrophy

PURPOSE OF REVIEW

Facioscapulohumeral muscular dystrophy (FSHD) is a neuromuscular disorder, which is caused by incomplete repression of the transcription factor double homeobox 4 (DUX4) in skeletal muscle. To date, there is no DUX4-targeting treatment to prevent or delay disease progression. In the present review, we summarize developments in therapeutic strategies with the focus on inhibiting DUX4 and DUX4 target gene expression.

RECENT FINDINGS

Different studies show that DUX4 and its target genes can be repressed with genetic therapies using diverse strategies. Additionally, different small compounds can reduce DUX4 and its target genes in vitro and in vivo.

SUMMARY

Most studies that show DUX4 repression by genetic therapies have only been tested in vitro. More efforts should be made to test them in vivo for clinical translation. Several compounds have been shown to prevent DUX4 and target gene expression in vitro and in vivo. However, their efficiency and specificity has not yet been shown. With emerging clinical trials, the clinical benefit from DUX4 repression in FSHD will likely soon become apparent.

Associations between dietary patterns and physical fitness among Chinese elderly

OBJECTIVE

To explore the relationship between dietary patterns and physical fitness among older Chinese (≥60 years) individuals.

DESIGN

Cross-sectional survey. Dietary data were collected by a simplified semi-quantitative FFQ. The 30-s Chair Stand test (30sCST), 30-s Arm Curl test (30sACT), 8-foot Time Up-and-Go test (8fTUAGT) and 6-min Walking test (6mWT) were used to assess physical fitness. Dietary patterns were obtained by factor analysis. The association between dietary patterns and physical fitness was explored by multiple logistic regression.

SETTING

Six communities (villages) of three districts in Liaocheng City (Shandong Province, China).

PARTICIPANTS

A total of 596 residents were recruited from April to May 2017.

RESULTS

Among 556 residents who were finally enrolled, 196 were men (35 %) and 360 were women (65 %). Three dietary patterns were identified: 'Western', 'Vegetarian' and 'Modern'. The 30sACT revealed that men in the fourth quartile of the Western pattern were less likely to be classified in the 'high-level' group, but men in the fourth quartile of the Vegetarian pattern were classified in the high-level group. The 6mWT revealed that men in the fourth quartile of the Modern pattern were classified in the high-level group. These associations were independent of confounding factors.

CONCLUSIONS

Adherence to the Vegetarian pattern and Modern pattern may be protective factors for maintaining good physical fitness in older Chinese individuals. The Western pattern may lead to poor physical fitness in this population.

Therapeutic Strategies Targeting DUX4 in FSHD

Facioscapulohumeral muscular dystrophy (FSHD) is a common muscle dystrophy typically affecting patients within their second decade. Patients initially exhibit asymmetric facial and humeral muscle damage, followed by lower body muscle involvement. FSHD is associated with a derepression of DUX4 gene encoded by the D4Z4 macrosatellite located on the subtelomeric part of chromosome 4. DUX4 is a highly regulated transcription factor and its expression in skeletal muscle contributes to multiple cellular toxicities and pathologies ultimately leading to muscle weakness and atrophy. Since the discovery of the FSHD candidate gene DUX4, many cell and animal models have been designed for therapeutic approaches and clinical trials. Today there is no treatment available for FSHD patients and therapeutic strategies targeting DUX4 toxicity in skeletal muscle are being actively investigated. In this review, we will discuss different research areas that are currently being considered to alter DUX4 expression and toxicity in muscle tissue and the cell and animal models designed to date.

Cellular Stress in the Pathogenesis of Muscular Disorders-From Cause to Consequence

Cellular stress has been considered a relevant pathogenetic factor in a variety of human diseases. Due to its primary functions by means of contractility, metabolism, and protein synthesis, the muscle cell is faced with continuous changes of cellular homeostasis that require rapid and coordinated adaptive mechanisms. Hence, a prone susceptibility to cellular stress in muscle is immanent. However, studies focusing on the cellular stress response in muscular disorders are limited. While in recent years there have been emerging indications regarding a relevant role of cellular stress in the pathophysiology of several muscular disorders, the underlying mechanisms are to a great extent incompletely understood. This review aimed to summarize the available evidence regarding a deregulation of the cellular stress response in individual muscle diseases. Potential mechanisms, as well as involved pathways are critically discussed, and respective disease models are addressed. Furthermore, relevant therapeutic approaches that aim to abrogate defects of cellular stress response in muscular disorders are outlined.

Lim K, Jaiswal JK, Chen YW. Membrane Repair Deficit in Facioscapulohumeral Muscular Dystrophy

Deficits in plasma membrane repair have been identified in dysferlinopathy and Duchenne Muscular Dystrophy, and contribute to progressive myopathy. Although Facioscapulohumeral Muscular Dystrophy (FSHD) shares clinicopathological features with these muscular dystrophies, it is unknown if FSHD is characterized by plasma membrane repair deficits. Therefore, we exposed immortalized human FSHD myoblasts, immortalized myoblasts from unaffected siblings, and myofibers from a murine model of FSHD (FLExDUX4) to focal, pulsed laser ablation of the sarcolemma. Repair kinetics and success were determined from the accumulation of intracellular FM1-43 dye post-injury. We subsequently treated FSHD myoblasts with a DUX4-targeting antisense oligonucleotide (AON) to reduce DUX4 expression, and with the antioxidant Trolox to determine the role of DUX4 expression and oxidative stress in membrane repair. Compared to unaffected myoblasts, FSHD myoblasts demonstrate poor repair and a greater percentage of cells that failed to repair, which was mitigated by AON and Trolox treatments. Similar repair deficits were identified in FLExDUX4 myofibers. This is the first study to identify plasma membrane repair deficits in myoblasts from individuals with FSHD, and in myofibers from a murine model of FSHD. Our results suggest that DUX4 expression and oxidative stress may be important targets for future membrane-repair therapies.

Induction of a local muscular dystrophy using electroporation in vivo: an easy tool for screening therapeutics

Intramuscular injection and electroporation of naked plasmid DNA (IMEP) has emerged as a potential alternative to viral vector injection for transgene expression into skeletal muscles. In this study, IMEP was used to express the DUX4 gene into mouse tibialis anterior muscle. DUX4 is normally expressed in germ cells and early embryo, and silenced in adult muscle cells where its pathological reactivation leads to Facioscapulohumeral muscular dystrophy. DUX4 encodes a potent transcription factor causing a large deregulation cascade. Its high toxicity but sporadic expression constitutes major issues for testing emerging therapeutics. The IMEP method appeared as a convenient technique to locally express DUX4 in mouse muscles. Histological analyses revealed well delineated muscle lesions 1-week after DUX4 IMEP. We have therefore developed a convenient outcome measure by quantification of the damaged muscle area using color thresholding. This method was used to characterize lesion distribution and to assess plasmid recirculation and dose–response. DUX4 expression and activity were confirmed at the mRNA and protein levels and through a quantification of target gene expression. Finally, this study gives a proof of concept of IMEP model usefulness for the rapid screening of therapeutic strategies, as demonstrated using antisense oligonucleotides against DUX4 mRNA.

Consequences of epigenetic derepression in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD), a common hereditary myopathy, is caused either by the contraction of the D4Z4 macrosatellite repeat at the distal end of chromosome 4q to a size of 1 to 10 repeat units (FSHD1) or by mutations in D4Z4 chromatin modifiers such as Structural Maintenance of Chromosomes Hinge Domain Containing 1 (FSHD2). These two genotypes share a phenotype characterized by progressive and often asymmetric muscle weakening and atrophy, and common epigenetic alterations of the D4Z4 repeat. All together, these epigenetic changes converge the two genetic forms into one disease and explain the derepression of the DUX4 gene, which is otherwise kept epigenetically silent in skeletal muscle. DUX4 is consistently transcriptionally upregulated in FSHD1 and FSHD2 skeletal muscle cells where it is believed to exercise a toxic effect. Here we provide a review of the recent literature describing the progress in understanding the complex genetic and epigenetic architecture of FSHD, with a focus on one of the consequences that these epigenetic changes inflict, the DUX4-induced immune deregulation cascade. Moreover, we review the latest therapeutic strategies, with particular attention to the potential of epigenetic correction of the FSHD locus.

Exercise-Related Oxidative Stress as Mechanism to Fight Physical Dysfunction in Neuromuscular Disorders

Neuromuscular diseases (NMDs) are a group of often severely disabling disorders characterized by dysfunction in one of the main constituents of the motor unit, the cardinal anatomic-functional structure behind force and movement production. Irrespective of the different pathogenic mechanisms specifically underlying these disease conditions genetically determined or acquired, and the related molecular pathways involved in doing that, oxidative stress has often been shown to play a relevant role within the chain of events that induce or at least modulate the clinical manifestations of these disorders. Due to such a putative relevance of the imbalance of redox status occurring in contractile machinery and/or its neural drive in NMDs, physical exercise appears as one of the most important conditions able to positively interfere along an ideal axis, going from a deranged metabolic cell homeostasis in motor unit components to the reduced motor performance profile exhibited by the patient in everyday life. If so, it comes out that it would be important to identify a proper training program, suitable for load and type of exercise that is able to improve motor performance in adaptation and response to such a homeostatic imbalance. This review therefore analyzes the role of different exercise trainings on oxidative stress mechanisms, both in healthy and in NMDs, also including preclinical studies, to elucidate at which extent these can be useful to counteract muscle impairment associated to the disease, with the final aim of improving physical functions and quality of life of NMD patients.

Facioscapulohumeral Muscular Dystrophies

PURPOSE OF REVIEW

Facioscapulohumeral muscular dystrophy (FSHD) is a common muscular dystrophy affecting both pediatric and adult patients. This article reviews the phenotype and pathophysiology of the disease as well as the recent efforts in clinical outcome measures and clinical trials.

RECENT FINDINGS

As the name implies, FSHD involves weakness of facial muscles, muscles that fix the scapula, and muscles overlying the humerus (biceps and triceps). The distinctive phenotype of FSHD occurs secondary to two different genetic mechanisms. FSHD type 1 (FSHD1) is due to a deletion on chromosome 4q, leading to hypomethylation and derepression of DUX4. FSHD type 2 (FSHD2) is due to mutations in SMCHD1 with resulting hypomethylation of the same subtelomeric region of chromosome 4q and derepression of DUX4. Understanding the central role of DUX4 has opened up the possibility of disease-modifying treatments. In preparation for clinical trials of novel agents, researchers are in the process of validating a number of clinical trial outcome measures including MRI, the 6-minute walk test, the FSHD Composite Outcome Measure, reachable workspace, electrical impedance myography, and the FSHD Health Index.

SUMMARY

The treatment of FSHD is currently supportive only. While past clinical trials in FSHD have been largely disappointing, novel agents in development, including antisense oligonucleotides, gene therapy, and small molecules, hold promise for future meaningful therapies.

PAX7 target gene repression is a superior FSHD biomarker than DUX4 target gene activation, associating with pathological severity and identifying FSHD at the single-cell level

Facioscapulohumeral muscular dystrophy (FSHD) is a prevalent, incurable skeletal myopathy. The condition is linked to hypomethylation of the D4Z4 macrosatellite repeat at chromosome 4q35, leading to epigenetic derepression of the transcription factor DUX4; coupled with a permissive 4qA haplotype supplying a poly(A) signal. DUX4 may drive FSHD pathology via both induction of target genes and inhibition of the function of the myogenic master regulator PAX7. Biomarkers for FSHD have focused on DUX4 target gene expression. We have, however, reported that PAX7 target gene repression is a hallmark of FSHD skeletal muscle. Here we demonstrate that PAX7 target gene repression is an equivalent biomarker to DUX4 target gene expression when considering RNA-Sequencing data from magnetic resonance imaging-guided muscle biopsies. Moreover, PAX7 target gene repression correlates with active disease, independent to DUX4 target gene expression. PAX7 target genes are also repressed in RNA-Sequencing data from single cells, representing a significantly better biomarker of FSHD cells than DUX4 target gene expression. Importantly, PAX7 target gene repression is a significant biomarker in the majority of FSHD cells that are DUX4 target gene negative, and on which the DUX4 biomarker is indiscriminate. To facilitate the evaluation of validated biomarkers we provide a simple tool that outputs biomarker values from a normalized expression data matrix. In summary, PAX7 target gene repression in FSHD correlates with disease severity, independently of DUX4 target gene expression. At the single-cell level, PAX7 target gene repression can efficiently discriminate FSHD cells, even when no DUX4 target genes are detectable.