Assessing functional performance in the mdx mouse model

LED therapy modulates M1/M2 macrophage phenotypes and mitigates dystrophic features in treadmill-trained mdx mice

The mdx mouse phenotype, aggravated by chronic exercise on a treadmill, makes this murine model more reliable for the study of Duchenne muscular dystrophy (DMD) and allows the efficacy of therapeutic interventions to be evaluated. This study aims to investigate the effects of photobiomodulation by light-emitting diode (LED) therapy on functional, biochemical and morphological parameters in treadmill-trained adult mdx animals. Mdx mice were trained for 30 min of treadmill running at a speed of 12 m/min, twice a week for 4 weeks. The LED therapy (850 nm) was applied twice a week to the quadriceps muscle throughout the treadmill running period. LED therapy improved behavioral activity (open field) and muscle function (grip strength and four limb hanging test). Functional benefits correlated with reduced muscle damage; a decrease in the inflammatory process; modulation of the regenerative muscular process and calcium signalling pathways; and a decrease in oxidative stress markers. The striking finding of this work is that LED therapy leads to a shift from the M1 to M2 macrophage phenotype in the treadmill-trained mdx mice, enhancing tissue repair and mitigating the dystrophic features. Our data also imply that the beneficial effects of LED therapy in the dystrophic muscle correlate with the interplay between calcium, oxidative stress and inflammation signalling pathways. Together, these results suggest that photobiomodulation could be a potential adjuvant therapy for dystrophinopathies.

Endothelial cell signature in muscle stem cells validated by VEGFA-FLT1-AKT1 axis promoting survival of muscle stem cell

Endothelial and skeletal muscle lineages arise from common embryonic progenitors. Despite their shared developmental origin, adult endothelial cells (ECs) and muscle stem cells (MuSCs; satellite cells) have been thought to possess distinct gene signatures and signaling pathways. Here, we shift this paradigm by uncovering how adult MuSC behavior is affected by the expression of a subset of EC transcripts. We used several computational analyses including single-cell RNA-seq (scRNA-seq) to show that MuSCs express low levels of canonical EC markers in mice. We demonstrate that MuSC survival is regulated by one such prototypic endothelial signaling pathway (VEGFA-FLT1). Using pharmacological and genetic gain- and loss-of-function studies, we identify the FLT1-AKT1 axis as the key effector underlying VEGFA-mediated regulation of MuSC survival. All together, our data support that the VEGFA-FLT1-AKT1 pathway promotes MuSC survival during muscle regeneration, and highlights how the minor expression of select transcripts is sufficient for affecting cell behavior.

Probing polypharmacy, ageing and sex effects on physical function using different tests

BACKGROUND

Ageing, sex and polypharmacy affect physical function.

OBJECTIVES

This mouse study investigates how ageing, sex and polypharmacy interact and affect grip strength, balance beam and wire hang, correlating and comparing the different test results between and within subgroups.

METHODS

Young (2.5 months) and old (21.5 months) C57BL/6 J male and female mice (n = 10-6/group) were assessed for physical function at baseline on grip strength, balance beam and wire hang with three trials of 60 s (WH60s) and one trial of 300 s (WH300s). Mice were randomised to control or diet containing a high Drug Burden Index (DBI, total anticholinergic and sedative drug exposure) polypharmacy regimen (metoprolol, simvastatin, citalopram, oxycodone and oxybutynin at therapeutic oral doses). Following 6-8 weeks of treatment, mice were reassessed.

RESULTS

High DBI polypharmacy and control mice both showed age group differences on all tests (p < 0.05). Only control mice showed sex differences, with females outperforming males on the WH60s and balance beam for old mice, WH300s for young mice (p < 0.05). Polypharmacy reduced grip strength in all subgroups (p < 0.05) and only in old females reduced wire hang time and cumulative behaviour and balance beam time and %walked (p < 0.05). Physical function assessments were all correlated with each other, with differences between subgroups (p < 0.05), and mice within subgroups showed interindividual variability in performance.

CONCLUSION

Age, sex and polypharmacy have variable effects on different tests, and behavioural measures are useful adjuvants to assessing performance. There was considerable within-group variability in change in measures over time. These findings can inform design and sample size of future studies.

Tolperisone hydrochloride improves motor functions in Parkinson's disease via MMP-9 inhibition and by downregulating p38 MAPK and ERK1/2 signaling cascade

The mitogen-activated protein kinase (MAPK) signaling pathway, particularly the p38 MAPK and ERK1/2, has been implicated in the pathogenesis of Parkinson's disease (PD). Recent studies have shown that MAPK signaling pathway can influence the expression of matrix metalloproteinase 9 (MMP-9), known for its involvement in various physiological and pathological processes, including neurodegenerative diseases. This study explores the modulation of MMP-9 expression via the MAPK/ERK signaling cascade and its potential therapeutic implications in the context of PD-associated motor dysfunction. Here, tolperisone hydrochloride (TL), a muscle relaxant that blocks voltage-gated sodium and calcium channels, was used as a treatment to observe its effect on MAPK signaling and MMP-9 expression. Rotenone (RT) exposure in mice resulted in a significant reduction in substantia nigra and primary motor cortex neurons, which were further evidenced by impairments in motor function. When TL was administered, neuron count was restored (89.0 ± 4.78 vs 117.0 ± 4.46/mm2), and most of the motor dysfunction was alleviated. Mechanistically, TL reduced the protein expression of phospho-p38MAPK (1.06 fold vs 1.00 fold) and phospho-ERK1/2 (1.16 fold vs 1.02 fold), leading to the inhibition of MAPK signaling, as well as reduced MMP-9 concentrations (2.76 ± 0.10 vs 1.94 ± 0.10 ng/mL) in the process of rescuing RT-induced neuronal cell death and motor dysfunction. Computational analysis further revealed TL's potential inhibitory properties against MMP-9 along with N and L-type calcium channels. These findings shed light on TL's neuroprotective effects via MMP-9 inhibition and MAPK signaling downregulation, offering potential therapeutic avenues for PD-associated motor dysfunction.

The slow-release adiponectin analog ALY688-SR modifies early-stage disease development in the D2.mdx mouse model of Duchenne muscular dystrophy

Fibrosis is associated with respiratory and limb muscle atrophy in Duchenne muscular dystrophy (DMD). Current standard of care partially delays the progression of this myopathy but there remains an unmet need to develop additional therapies. Adiponectin receptor agonism has emerged as a possible therapeutic target to lower inflammation and improve metabolism in mdx mouse models of DMD but the degree to which fibrosis and atrophy are prevented remain unknown. Here, we demonstrate that the recently developed slow-release peptidomimetic adiponectin analog, ALY688-SR, remodels the diaphragm of murine model of DMD on DBA background (D2.mdx) mice treated from days 7-28 of age during early stages of disease. ALY688-SR also lowered interleukin-6 (IL-6) mRNA but increased IL-6 and transforming growth factor-β1 (TGF-β1) protein contents in diaphragm, suggesting dynamic inflammatory remodeling. ALY688-SR alleviated mitochondrial redox stress by decreasing complex I-stimulated H2O2 emission. Treatment also attenuated fibrosis, fiber type-specific atrophy, and in vitro diaphragm force production in diaphragm suggesting a complex relationship between adiponectin receptor activity, muscle remodeling, and force-generating properties during the very early stages of disease progression in murine model of DMD on DBA background (D2.mdx) mice. In tibialis anterior, the modest fibrosis at this young age was not altered by treatment, and atrophy was not apparent at this young age. These results demonstrate that short-term treatment of ALY688-SR in young D2.mdx mice partially prevents fibrosis and fiber type-specific atrophy and lowers force production in the more disease-apparent diaphragm in relation to lower mitochondrial redox stress and heterogeneous responses in certain inflammatory markers. These diverse muscle responses to adiponectin receptor agonism in early stages of DMD serve as a foundation for further mechanistic investigations.NEW & NOTEWORTHY There are limited therapies for the treatment of Duchenne muscular dystrophy. As fibrosis involves an accumulation of collagen that replaces muscle fibers, antifibrotics may help preserve muscle function. We report that the novel adiponectin receptor agonist ALY688-SR prevents fibrosis in the diaphragm of D2.mdx mice with short-term treatment early in disease progression. These responses were related to altered inflammation and mitochondrial functions and serve as a foundation for the development of this class of therapy.

A humanized knock-in Col6a1 mouse recapitulates a deep-intronic splice-activating variant

Antisense therapeutics such as splice-modulating antisense oligonucleotides (ASOs) are promising tools to treat diseases caused by splice-altering intronic variants. However, their testing in animal models is hampered by the generally poor sequence conservation of the intervening sequences between human and other species. Here we aimed to model in the mouse a recurrent, deep-intronic, splice-activating, COL6A1 variant, associated with a severe form of Collagen VI-related muscular dystrophies (COL6-RDs), for the purpose of testing human-ready antisense therapeutics in vivo. The variant, c.930+189C>T, creates a donor splice site and inserts a 72-nt-long pseudoexon, which, when translated, acts in a dominant-negative manner, but which can be skipped with ASOs. We created a unique humanized mouse allele (designated as "h"), in which a 1.9 kb of the mouse genomic region encoding the amino-terminus (N-) of the triple helical (TH) domain of collagen a1(VI) was swapped for the human orthologous sequence. In addition, we also created an allele that carries the c.930+189C>T variant on the same humanized knock-in sequence (designated as "h+189T"). We show that in both models, the human exons are spliced seamlessly with the mouse exons to generate a chimeric mouse-human collagen a1(VI) protein. In homozygous Col6a1 h+189T/h+189T mice, the pseudoexon is expressed at levels comparable to those observed in heterozygous patients' muscle biopsies. While Col6a1h/h mice do not show any phenotype compared to wildtype animals, Col6a1 h/h+189T and Col6a1 h+189T/h+189T mice have smaller muscle masses and display grip strength deficits detectable as early as 4 weeks of age. The pathogenic h+189T humanized knock-in mouse allele thus recapitulates the pathogenic splicing defects seen in patients' biopsies and allows testing of human-ready precision antisense therapeutics aimed at skipping the pseudoexon. Given that the COL6A1 N-TH region is a hot-spot for COL6-RD variants, the humanized knock-in mouse model can be utilized as a template to introduce other COL6A1 pathogenic variants. This unique humanized mouse model thus represents a valuable tool for the development of antisense therapeutics for COL6-RDs.

Nesting behavior is associated with body weight and grip strength loss in mice suffering from experimental arthritis

Objective animal health evaluation is essential to determine welfare and discomfort in preclinical in vivo research. Body condition scores, body weight, and grimace scales are commonly used to evaluate well-being in murine rheumatoid arthritis (RA) and osteoarthritis experiments. However, nest-building, a natural behavior in mice, has not yet been evaluated in wild type (WT) or genetically modified rodents suffering from collagen antibody-induced arthritis (CAIA). To address this, we analyzed nesting behavior in WT mice, calcitonin gene-related peptide alpha-deficient (αCGRP-/-) mice, and calcitonin receptor-deficient (Calcr-/-) mice suffering from experimental RA compared to healthy control (CTRL) groups of the same genotypes. CAIA was induced in 10-12-week-old male mice, and clinical parameters (body weight, grip strength, clinical arthritis score, ankle size) as well as nesting behavior were assessed over 10 or 48 days. A slight positive association between the nest score and body weight and grip strength was found for animals suffering from CAIA. For the clinical arthritis score and ankle size, no significant associations were observed. Mixed model analyses confirmed these associations. This study demonstrates that clinical effects of RA, such as loss of body weight and grip strength, might negatively affect nesting behavior in mice. Assessing nesting behavior in mice with arthritis could be an additional, non-invasive and thus valuable health parameter in future experiments to monitor welfare and discomfort in mice. During severe disease stages, pre-formed nest-building material may be provided to animals suffering from arthritis.

TMEM65 regulates NCLX-dependent mitochondrial calcium efflux

The balance between mitochondrial calcium (mCa2+) uptake and efflux regulates ATP production, but if perturbed causes energy starvation or mCa2+ overload and cell death. The mitochondrial sodium-calcium exchanger, NCLX, is a critical route of mCa2+ efflux in excitable tissues, such as the heart and brain, and animal models support NCLX as a promising therapeutic target to limit pathogenic mCa2+ overload. However, the mechanisms that regulate NCLX activity remain largely unknown. We used proximity biotinylation proteomic screening to identify the NCLX interactome and define novel regulators of NCLX function. Here, we discover the mitochondrial inner membrane protein, TMEM65, as an NCLX-proximal protein that potently enhances sodium (Na+)-dependent mCa2+ efflux. Mechanistically, acute pharmacologic NCLX inhibition or genetic deletion of NCLX ablates the TMEM65-dependent increase in mCa2+ efflux. Further, loss-of-function studies show that TMEM65 is required for Na+-dependent mCa2+ efflux. Co-fractionation and in silico structural modeling of TMEM65 and NCLX suggest these two proteins exist in a common macromolecular complex in which TMEM65 directly stimulates NCLX function. In line with these findings, knockdown of Tmem65 in mice promotes mCa2+ overload in the heart and skeletal muscle and impairs both cardiac and neuromuscular function. We further demonstrate that TMEM65 deletion causes excessive mitochondrial permeability transition, whereas TMEM65 overexpression protects against necrotic cell death during cellular Ca2+ stress. Collectively, our results show that loss of TMEM65 function in excitable tissue disrupts NCLX-dependent mCa2+ efflux, causing pathogenic mCa2+ overload, cell death and organ-level dysfunction, and that gain of TMEM65 function mitigates these effects. These findings demonstrate the essential role of TMEM65 in regulating NCLX-dependent mCa2+ efflux and suggest modulation of TMEM65 as a novel strategy for the therapeutic control of mCa2+ homeostasis.

CRISPR-Cas9 correction in the DMD mouse model is accompanied by upregulation of Dp71f protein

Duchenne muscular dystrophy (DMD) is a severe hereditary disease caused by a deficiency in the dystrophin protein. The most frequent types of disease-causing mutations in the DMD gene are frameshift deletions of one or more exons. Precision genome editing systems such as CRISPR-Cas9 have shown potential to restore open reading frames in numerous animal studies. Here, we applied an AAV-CRISPR double-cut strategy to correct a mutation in the DMD mouse model with exon 8-34 deletion, encompassing the N-terminal actin-binding domain. We report successful excision of the 100-kb genomic sequence, which includes exons 6 and 7, and partial improvement in cardiorespiratory function. While corrected mRNA was abundant in muscle tissues, only a low level of truncated dystrophin was produced, possibly because of protein instability. Furthermore, CRISPR-Cas9-mediated genome editing upregulated the Dp71f dystrophin isoform on the sarcolemma. Given the previously reported Dp71-associated muscle pathology, our results question the applicability of genome editing strategies for some DMD patients with N-terminal mutations. The safety and efficacy of CRISPR-Cas9 constructs require rigorous investigation in patient-specific animal models.

Impact of short-term, pharmacological CARM1 inhibition on skeletal muscle mass, function, and atrophy in mice

Coactivator-associated arginine methyltransferase 1 (CARM1) catalyzes the methylation of arginine residues on target proteins critical for health and disease. The purpose of this study was to characterize the effects of short-term, pharmacological CARM1 inhibition on skeletal muscle size, function, and atrophy. Adult mice (n = 10 or 11/sex) were treated with either a CARM1 inhibitor (150 mg/kg EZM2302; EZM) or vehicle (Veh) via oral gavage for 11-13 days and muscle mass, function, and exercise capacity were assessed. In addition, we investigated the effect of CARM1 suppression on unilateral hindlimb denervation (DEN)-induced muscle atrophy (n = 8/sex). We report that CARM1 inhibition caused significant reductions in the asymmetric dimethylation of known CARM1 substrates but no change in CARM1 protein or mRNA content in skeletal muscle. Reduced CARM1 activity did not affect body or muscle mass, however, we observed a decrease in exercise capacity and muscular endurance in male mice. CARM1 methyltransferase activity increased in the muscle of Veh-treated mice following 7 days of DEN, and this response was blunted in EZM-dosed mice. Skeletal muscle mass and myofiber cross-sectional area were significantly reduced in DEN compared with contralateral, non-DEN limbs to a similar degree in both treatment groups. Furthermore, skeletal muscle atrophy and autophagy gene expression programs were elevated in response to DEN independent of CARM1 suppression. Collectively, these results suggest that short-term, pharmacological CARM1 inhibition in adult animals affects muscle performance in a sex-specific manner but does not impact the maintenance and remodeling of skeletal muscle mass during conditions of neurogenic muscle atrophy.NEW & NOTEWORTHY Short-term pharmacological inhibition of coactivator-associated arginine methyltransferase 1 (CARM1) was effective at significantly reducing CARM1 methyltransferase function in skeletal muscle. CARM1 inhibition did not impact muscle mass, but exercise capacity was impaired, particularly in male mice, whereas morphological and molecular signatures of denervation-induced muscle atrophy were largely maintained in animals administered the inhibitor. Altogether, the role of CARM1 in neuromuscular biology remains complex and requires further investigation of its therapeutic potential in muscle-wasting conditions.

A G1528C Hadha knock-in mouse model recapitulates aspects of human clinical phenotypes for long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a fatty acid oxidation disorder (FAOD) caused by a pathogenic variant, c.1528 G > C, in HADHA encoding the alpha subunit of trifunctional protein (TFPα). Individuals with LCHADD develop chorioretinopathy and peripheral neuropathy not observed in other FAODs in addition to the more ubiquitous symptoms of hypoketotic hypoglycemia, rhabdomyolysis and cardiomyopathy. We report a CRISPR/Cas9 generated knock-in murine model of G1528C in Hadha that recapitulates aspects of the human LCHADD phenotype. Homozygous pups are less numerous than expected from Mendelian probability, but survivors exhibit similar viability with wildtype (WT) littermates. Tissues of LCHADD homozygotes express TFPα protein, but LCHADD mice oxidize less fat and accumulate plasma 3-hydroxyacylcarnitines compared to WT mice. LCHADD mice exhibit lower ketones with fasting, exhaust earlier during treadmill exercise and develop a dilated cardiomyopathy compared to WT mice. In addition, LCHADD mice exhibit decreased visual performance, decreased cone function, and disruption of retinal pigment epithelium. Neurological function is affected, with impaired motor function during wire hang test and reduced open field activity. The G1528C knock-in mouse exhibits a phenotype similar to that observed in human patients; this model will be useful to explore pathophysiology and treatments for LCHADD in the future.

Prolonged voluntary wheel running reveals unique adaptations in mdx mice treated with microdystrophin constructs ± the nNOS-binding site

We tested the effects of prolonged voluntary wheel running on the muscle function of mdx mice treated with one of two different microdystrophin constructs. At 7 weeks of age mdx mice were injected with a single dose of AAV9-CK8-microdystrophin with (gene therapy 1, GT1) or without (gene therapy 2, GT2) the nNOS-binding domain and were assigned to one of four gene therapy treated groups: mdxRGT1 (run, GT1), mdxGT1 (no run, GT1), or mdxRGT2 (run,GT2), mdxGT2 (no run, GT2). There were two mdx untreated groups injected with excipient: mdxR (run, no gene therapy) and mdx (no run, no gene therapy). A third no treatment group, Wildtype (WT) received no injection and did not run. mdxRGT1, mdxRGT2 and mdxR performed voluntary wheel running for 52 weeks; WT and remaining mdx groups were cage active. Robust expression of microdystrophin occurred in diaphragm, quadriceps, and heart muscles of all treated mice. Dystrophic muscle pathology was high in diaphragms of non-treated mdx and mdxR mice and improved in all treated groups. Endurance capacity was rescued by both voluntary wheel running and gene therapy alone, but their combination was most beneficial. All treated groups increased in vivo plantarflexor torque over both mdx and mdxR mice. mdx and mdxR mice displayed ∼3-fold lower diaphragm force and power compared to WT values. Treated groups demonstrated partial improvements in diaphragm force and power, with mdxRGT2 mice experiencing the greatest improvement at ∼60% of WT values. Evaluation of oxidative red quadriceps fibers revealed the greatest improvements in mitochondrial respiration in mdxRGT1 mice, reaching WT levels. Interestingly, mdxGT2 mice displayed diaphragm mitochondrial respiration values similar to WT but mdxRGT2 animals showed relative decreases compared to the no run group. Collectively, these data demonstrate that either microdystrophin construct combined with voluntary wheel running increased in vivo maximal muscle strength, power, and endurance. However, these data also highlighted important differences between the two microdystrophin constructs. GT1, with the nNOS-binding site, improved more markers of exercise-driven adaptations in metabolic enzyme activity of limb muscles, while GT2, without the nNOS-binding site, demonstrated greater protection of diaphragm strength after chronic voluntary endurance exercise but decreased mitochondrial respiration in the context of running.

Taurine deficiency as a driver of aging

Aging is associated with changes in circulating levels of various molecules, some of which remain undefined. We find that concentrations of circulating taurine decline with aging in mice, monkeys, and humans. A reversal of this decline through taurine supplementation increased the health span (the period of healthy living) and life span in mice and health span in monkeys. Mechanistically, taurine reduced cellular senescence, protected against telomerase deficiency, suppressed mitochondrial dysfunction, decreased DNA damage, and attenuated inflammaging. In humans, lower taurine concentrations correlated with several age-related diseases and taurine concentrations increased after acute endurance exercise. Thus, taurine deficiency may be a driver of aging because its reversal increases health span in worms, rodents, and primates and life span in worms and rodents. Clinical trials in humans seem warranted to test whether taurine deficiency might drive aging in humans.

Deciphering the Molecular Mechanism of Yifei-Sanjie Pill in Cancer-Related Fatigue

Background

The incidence of cancer-related fatigue (CRF) is increasing, but its lack of clear pathogenesis makes its prevention and treatment difficult. Therefore, it is of great significance to clarify the pathogenesis of CRF and find effective methods to treat it.

Methods

The CRF model was established by intraperitoneal injection of LLC cells in ICR mice to explore the pathogenesis of CRF and verify the therapeutic effect of the Yifei-Sanjie pill (YFSJ). The active components of YFSJ were found by LC/MS, the in vitro inflammatory infiltration model of skeletal muscle was constructed by TNF-α and C2C12 myoblasts, and the results of in vivo experiments were verified by this model.

Results

Behavioral analysis results showed that YFSJ alleviated CRF; histological examination results showed that YFSJ could reverse the tumor microenvironment leading to skeletal muscle injury; ELISA and RNA-seq results showed that the occurrence of CRF and the therapeutic effect of YFSJ were closely related to the tumor inflammatory microenvironment; IHC and WB results showed that the occurrence of CRF and the therapeutic effect of YFSJ were closely related to the Stat3-related signaling pathway and autophagy.

Conclusions

YFSJ can reduce the level of inflammation in the tumor microenvironment in vivo, inhibit the abnormal activation of the Stat3/HIF-1α/BNIP3 signaling pathway induced by tumor-related inflammation, thereby inhibiting the overactivation of mitophagy in skeletal muscle, and finally alleviate CRF. Quercetin, one of the components of YFSJ, plays an important role in inhibiting the phosphorylation activation of Stat3.

Interleukin-4 improved adipose-derived stem cells engraftment via interacting with fibro/adipogenic progenitors in dystrophic mice.. [DOI: 10.21203/rs.3.rs-2321597/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Adipose-derived stem cells (ADSC) therapy is a promising therapy for dystrophinopathy. Fibro/adipogenic progenitors (FAP) are important in regulating the myogenesis of muscle satellite cells and contribute to muscle fibrosis and adipocyte infiltration. The interleukin-4 (IL4) pathway is found to be a switcher regulating the functions of FAP. The interaction between FAP and engrafted cells has not yet been studied. We used a co-culture system to investigate the possible crosstalk between FAP of dystrophic mice and IL4-overexpressed ADSC (IL4-ADSC) and control ADSC. The systemic transplantation of IL4-ADSC and control ADSC was conducted in dystrophic mice for 16 weeks and motor function and molecular improvements of mice were evaluated. Overexpression of IL4 in ADSC significantly promoted terminal myogenesis in vitro with significant increased expression of Myogenin and MyHC. Through co-culture, we discovered that myoblasts derived from control ADSC promoted adipogenic and fibrogenic differentiation of FAP, but FAP did not significantly affect their myogenesis, while overexpression of IL4 in ADSC inhibited their myotube-dependent promotion of FAP differentiation but promoted FAP to support myogenesis. Dystrophic mice delivered with IL4-ADSC-derived myoblasts had a significant better motor ability, more engrafted cells with dystrophin expression, less muscle fibrosis, and intramuscular adipocytes and macrophage infiltration than mice delivered with control-ADSC-derived myoblasts. Our results revealed the importance of focusing on the crosstalk between engrafted cells and resident FAP in cell therapy and the positive therapeutic effect of IL4 administration combined with ADSC therapy in dystrophic mice.

Upregulation of CCL5/RANTES Gene Expression in the Diaphragm of Mice with Cholestatic Liver Disease

Chronic liver diseases are a group of pathologies affecting the liver with high prevalence worldwide. Among them, cholestatic chronic liver diseases (CCLD) are characterized by alterations in liver function and increased plasma bile acids. Secondary to liver disease, under cholestasis, is developed sarcopenia, a skeletal muscle dysfunction with decreased muscle mass, strength, and physical function. CCL5/RANTES is a chemokine involved in the immune and inflammatory response. Indeed, CCL5 is a myokine because it is produced by skeletal muscle. Several studies show that bile acids induce CCL5/RANTES expression in liver cells. However, it is unknown if the expression of CCL5/RANTES is changed in the skeletal muscle of mice with cholestatic liver disease. We used a murine model of cholestasis-induced sarcopenia by intake of hepatotoxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC diet), in which we detected the mRNA levels for ccl5. We determined that mice fed the DDC diet presented high levels of serum bile acids and developed typical features of sarcopenia. Under these conditions, we detected the ccl5 gene expression in diaphragm muscle showing elevated mRNA levels compared to mice fed with a standard diet (chow diet). Our results collectively suggest an increased ccl5 gene expression in the diaphragm muscle concomitantly with elevated serum bile acids and the development of sarcopenia.

Benefits of p-coumaric acid in mice with rotenone-induced neurodegeneration

The paper examines the use of natural antioxidant and anti-inflammation substances as therapeutic candidates for brain disease. Para-coumaric acid (pCA), a phenolic compound with a variety of medicinal properties, was used against deterioration caused by various diseases. Recently, pCA has gained attention for use against cardiovascular disease but less so for neurodegenerative disease (i.e., Parkinson's disease). Therefore, the present study intended to investigate the effect of pCA against rotenone-induced Parkinson's disease-like pathology in mice. Thirty male institute of cancer research (ICR) mice were randomly divided into three experimental groups: Sham-veh, Rot-veh, and Rot-pCA100. Rotenone (Rot) 2.5 mg/kg was subcutaneously injected every 48 h in the rotenone groups. Alternately, a 100 mg/kg pCA dose was given every 48 h via intragastric gavage to the Rot-pCA100 group for 6 weeks. Motor ability was assessed at the second, fourth, and sixth week before brain collection for biochemical and histological analyses. Results indicated significant motor deficits appeared from the second to sixth week after rotenone injection. Brain analysis detected a significant effect of rotenone in the increase of malondialdehyde and tumor necrosis factor-alpha (TNF-α). This result was observed in accordance with a reduction of tyrosine hydroxylase (TH) and an increase of neuronal degeneration in the substantia nigra par compacta (SNc) and striatum. However, pCA was able to reverse all of the deterioration (i.e., reduced malondialdehyde and TNF-α) rotenone had caused, and it protected against TH and neuronal loss in the SNc and striatum. Therefore, the present study has depicted the neuroprotective effect of pCA against rotenone-induced Parkinson's disease-like pathology in mice. Benefits of pCA include anti-lipid peroxidation and anti-inflammatory effects, inhibition of neurodegeneration, and a nurturing effect on the TH level in the SNc and striatum, leading to mitigation of motor deficits.

Nintedanib Reduces Muscle Fibrosis and Improves Muscle Function of the Alpha-Sarcoglycan-Deficient Mice

Sarcoglycanopathies are a group of recessive limb-girdle muscular dystrophies, characterized by progressive muscle weakness. Sarcoglycan deficiency produces instability of the sarcolemma during muscle contraction, leading to continuous muscle fiber injury eventually producing fiber loss and replacement by fibro-adipose tissue. Therapeutic strategies aiming to reduce fibro-adipose expansion could be effective in muscular dystrophies. We report the positive effect of nintedanib in a murine model of alpha-sarcoglycanopathy. We treated 14 Sgca-/- mice, six weeks old, with nintedanib 50 mg/kg every 12 h for 10 weeks and compared muscle function and histology with 14 Sgca-/- mice treated with vehicle and six wild-type littermate mice. Muscle function was assessed using a treadmill and grip strength. A cardiac evaluation was performed by echocardiography and histological study. Structural analysis of the muscles, including a detailed study of the fibrotic and inflammatory processes, was performed using conventional staining and immunofluorescence. In addition, proteomics and transcriptomics studies were carried out. Nintedanib was well tolerated by the animals treated, although we observed weight loss. Sgca-/- mice treated with nintedanib covered a longer distance on the treadmill, compared with non-treated Sgca-/- mice, and showed higher strength in the grip test. Moreover, nintedanib improved the muscle architecture of treated mice, reducing the degenerative area and the fibrotic reaction that was associated with a reversion of the cytokine expression profile. Nintedanib improved muscle function and muscle architecture by reducing muscle fibrosis and degeneration and reverting the chronic inflammatory environment suggesting that it could be a useful therapy for patients with alpha-sarcoglycanopathy.

Calorie Restriction Rescues Mitochondrial Dysfunction in Adck2-Deficient Skeletal Muscle

ADCK2 haploinsufficiency-mediated mitochondrial coenzyme Q deficiency in skeletal muscle causes mitochondrial myopathy associated with defects in beta-oxidation of fatty acids, aged-matched metabolic reprogramming, and defective physical performance. Calorie restriction has proven to increase lifespan and delay the onset of chronic diseases associated to aging. To study the possible treatment by food deprivation, heterozygous Adck2 knockout mice were fed under 40% calorie restriction (CR) and the phenotype was followed for 7 months. The overall glucose and fatty acids metabolism in muscle was restored in mutant mice to WT levels after CR. CR modulated the skeletal muscle metabolic profile of mutant mice, partially rescuing the profile of WT animals. The analysis of mitochondria isolated from skeletal muscle demonstrated that CR increased both CoQ levels and oxygen consumption rate (OCR) based on both glucose and fatty acids substrates, along with mitochondrial mass. The elevated aerobic metabolism fits with an increase of type IIa fibers, and a reduction of type IIx in mutant muscles, reaching WT levels. To further explore the effect of CR over muscle stem cells, satellite cells were isolated and induced to differentiate in culture media containing serum from animals in either ad libitum or CR diets for 72 h. Mutant cells showed slower differentiation alongside with decreased oxygen consumption. In vitro differentiation of mutant cells was increased under CR serum reaching levels of WT isolated cells, recovering respiration measured by OCR and partially beta-oxidation of fatty acids. The overall increase of skeletal muscle bioenergetics following CR intervention is paralleled with a physical activity improvement, with some increases in two and four limbs strength tests, and weights strength test. Running wheel activity was also partially improved in mutant mice under CR. These results demonstrate that CR intervention, which has been shown to improve age-associated physical and metabolic decline in WT mice, also recovers the defective aerobic metabolism and differentiation of skeletal muscle in mice caused by ADCK2 haploinsufficiency.

Sphingosine Phosphate Lyase Is Upregulated in Duchenne Muscular Dystrophy, and Its Inhibition Early in Life Attenuates Inflammation and Dystrophy in Mdx Mice

Duchenne muscular dystrophy (DMD) is a congenital myopathy caused by mutations in the dystrophin gene. DMD pathology is marked by myositis, muscle fiber degeneration, and eventual muscle replacement by fibrosis and adipose tissue. Satellite cells (SC) are muscle stem cells critical for muscle regeneration. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that promotes SC proliferation, regulates lymphocyte trafficking, and is irreversibly degraded by sphingosine phosphate lyase (SPL). Here, we show that SPL is virtually absent in normal human and murine skeletal muscle but highly expressed in inflammatory infiltrates and degenerating fibers of dystrophic DMD muscle. In mdx mice that model DMD, high SPL expression is correlated with dysregulated S1P metabolism. Perinatal delivery of the SPL inhibitor LX2931 to mdx mice augmented muscle S1P and SC numbers, reduced leukocytes in peripheral blood and skeletal muscle, and attenuated muscle inflammation and degeneration. The effect on SC was also observed in SCID/mdx mice that lack mature T and B lymphocytes. Transcriptional profiling in the skeletal muscles of LX2931-treated vs. control mdx mice demonstrated changes in innate and adaptive immune functions, plasma membrane interactions with the extracellular matrix (ECM), and axon guidance, a known function of SC. Our cumulative findings suggest that by raising muscle S1P and simultaneously disrupting the chemotactic gradient required for lymphocyte egress, SPL inhibition exerts a combination of muscle-intrinsic and systemic effects that are beneficial in the context of muscular dystrophy.

Mitochondrial FAD shortage in SLC25A32 deficiency affects folate-mediated one-carbon metabolism

The SLC25A32 dysfunction is associated with neural tube defects (NTDs) and exercise intolerance, but very little is known about disease-specific mechanisms due to a paucity of animal models. Here, we generated homozygous (Slc25a32Y174C/Y174C and Slc25a32K235R/K235R) and compound heterozygous (Slc25a32Y174C/K235R) knock-in mice by mimicking the missense mutations identified from our patient. A homozygous knock-out (Slc25a32-/-) mouse was also generated. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice presented with mild motor impairment and recapitulated the biochemical disturbances of the patient. While Slc25a32-/- mice die in utero with NTDs. None of the Slc25a32 mutations hindered the mitochondrial uptake of folate. Instead, the mitochondrial uptake of flavin adenine dinucleotide (FAD) was specifically blocked by Slc25a32Y174C/K235R, Slc25a32K235R/K235R, and Slc25a32-/- mutations. A positive correlation between SLC25A32 dysfunction and flavoenzyme deficiency was observed. Besides the flavoenzymes involved in fatty acid β-oxidation and amino acid metabolism being impaired, Slc25a32-/- embryos also had a subunit of glycine cleavage system-dihydrolipoamide dehydrogenase damaged, resulting in glycine accumulation and glycine derived-formate reduction, which further disturbed folate-mediated one-carbon metabolism, leading to 5-methyltetrahydrofolate shortage and other folate intermediates accumulation. Maternal formate supplementation increased the 5-methyltetrahydrofolate levels and ameliorated the NTDs in Slc25a32-/- embryos. The Slc25a32K235R/K235R and Slc25a32Y174C/K235R mice had no glycine accumulation, but had another formate donor-dimethylglycine accumulated and formate deficiency. Meanwhile, they suffered from the absence of all folate intermediates in mitochondria. Formate supplementation increased the folate amounts, but this effect was not restricted to the Slc25a32 mutant mice only. In summary, we established novel animal models, which enabled us to understand the function of SLC25A32 better and to elucidate the role of SLC25A32 dysfunction in human disease development and progression.

Effects of moderate aerobic exercise, low-level laser therapy, or their combination on muscles pathology, oxidative stress and irisin levels in the mdx mouse model of Duchenne muscular dystrophy

This study aimed to investigate how the combined use of low-level laser therapy (LLLT) and exercise, to reduce the possible side effects and/or increase the benefits of exercise, would affect oxidative stress, utrophin, irisin peptide, and skeletal, diaphragmatic, and cardiac muscle pathologies. In our study, 20 mdx mice were divided into four groups. Groups; sedentary and placebo LLLT (SC), sedentary and LLLT (SL), 30-min swimming exercise (Ex), and 30-min swimming exercise and LLLT (ExL). After 8 weeks of swimming exercise, muscle tests, biochemically; oxidative stress index (OSI), utrophin and irisin levels were measured. Skeletal, diaphragmatic and cardiac muscle histopathological scores, skeletal and cardiac muscle myocyte diameters were determined under the light and electron microscope. While only irisin levels were increased in group SL compared to SC, it was determined that OSI, heart muscle histopathological scores decreased and irisin levels increased in both exercise groups (p < 0.05). In addition, in the ExL group, an increase in rotarod and utrophin levels, and a decrease in muscle and diaphragm muscle histopathological scores were observed (p < 0.05). It was determined that the application of swimming exercise in the mdx mouse model increased the irisin level in the skeletal muscle, while reducing the OSI, degeneration in the heart muscle, inflammation and cardiopathy. When LLLT was applied in addition to exercise, muscle strength, skeletal muscle utrophin levels increased, and skeletal and diaphragmatic muscle degeneration and inflammation decreased. In addition, it was determined that only LLLT application increased the level of skeletal muscle irisin.

Investigating the role of dystrophin isoform deficiency in motor function in Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is caused by DMD mutations leading to dystrophin loss. Full-length Dp427 is the primary dystrophin isoform expressed in muscle and is also expressed in the central nervous system (CNS). Two shorter isoforms, Dp140 and Dp71, are highly expressed in the CNS. While a role for Dp140 and Dp71 on DMD CNS comorbidities is well known, relationships between mutations expected to disrupt Dp140 and Dp71 and motor outcomes are not.

METHODS

Functional outcome data from 387 DMD boys aged 4-15 years were subdivided by DMD mutation expected effects on dystrophin isoform expression; Group 1 (Dp427 absent, Dp140/Dp71 present, n = 201); Group 2 (Dp427/Dp140 absent, Dp71 present, n = 152); and Group 3 (Dp427/Dp140/Dp71 absent, n = 34). Relationships between isoform group and North Star ambulatory assessment (NSAA) scores, 10 m walk/run velocities and rise time velocities were explored using regression analysis. Western blot analysis was used to study Dp427, Dp140 and Dp71 production in myogenic cells (control and DMD human), control skeletal muscle, DMD skeletal muscle from the three isoform groups and cerebral cortex from mice (wild-type and DMD models). Grip strength and rotarod running test were studied in wild-type mice and DMD mouse models. DMD mouse models were mdx (Dp427 absent, Dp140/Dp71 present), mdx52 (Dp427/Dp140 absent, Dp71 present) and DMD-null (lacking all isoforms).

RESULTS

In DMD boys, mean NSAA scores at 5 years of age were 6.1 points lower in Group 3 than Group 1 (P < 0.01) and 4.9 points lower in Group 3 than Group 2 (P = 0.05). Mean peak NSAA scores were 4.0 points lower in Group 3 than Group 1 (P < 0.01) and 1.6 points lower in Group 2 than Group 1 (P = 0.04). Mean four-limb grip strength was 1.5 g/g lower in mdx52 than mdx mice (P = 0.003) and 1.5 g/g lower in DMD-null than mdx mice (P = 0.002). Dp71 was produced in myogenic cells (control and DMD human) and skeletal muscle from humans in Groups 1 and 2 and mdx mice, but not skeletal muscle from human controls, myogenic cells and skeletal muscle from humans in Group 3 or skeletal muscle from wild-type, mdx52 or DMD-null mice.

CONCLUSIONS

Our results highlight the importance of considering expected effects of DMD mutations on dystrophin isoform production when considering patterns of DMD motor impairment and the implications for clinical practice and clinical trials. Our results suggest a complex relationship between dystrophin isoforms expressed in the brain and DMD motor function.

Abolishing the prelamin A ZMPSTE24 cleavage site leads to progeroid phenotypes with near-normal longevity in mice

The zinc metalloprotease ZMPSTE24 removes the last 15 amino acids of prelamin A, including a farnesylated cysteine, to produce mature lamin A. The premature aging disorder Hutchinson–Gilford progeria syndrome is caused by a permanently farnesylated prelamin A variant lacking the ZMPSTE24 cleavage site. ZMPSTE24 loss of function leads to the accumulation of farnesylated prelamin A and causes progeroid disorders. Some studies have implicated prelamin A in physiological aging. We describe mice with an amino acid substitution in prelamin A that blocks the ZMPSTE24-catalyzed cleavage. These mice develop progeroid phenotypes but, in contrast to those modeling Hutchinson–Gilford progeria syndrome or ZMPSTE24 deficiency, have near-normal lifespans, thus providing a model to study the effects of farnesylated prelamin A during aging.

Prelamin A is a farnesylated precursor of lamin A, a nuclear lamina protein. Accumulation of the farnesylated prelamin A variant progerin, with an internal deletion including its processing site, causes Hutchinson–Gilford progeria syndrome. Loss-of-function mutations in ZMPSTE24, which encodes the prelamin A processing enzyme, lead to accumulation of full-length farnesylated prelamin A and cause related progeroid disorders. Some data suggest that prelamin A also accumulates with physiological aging. Zmpste24^−/− mice die young, at ∼20 wk. Because ZMPSTE24 has functions in addition to prelamin A processing, we generated a mouse model to examine effects solely due to the presence of permanently farnesylated prelamin A. These mice have an L648R amino acid substitution in prelamin A that blocks ZMPSTE24-catalyzed processing to lamin A. The Lmna^L648R/L648R mice express only prelamin and no mature protein. Notably, nearly all survive to 65 to 70 wk, with ∼40% of male and 75% of female Lmna^L648R/L648R mice having near-normal lifespans of 90 wk (almost 2 y). Starting at ∼10 wk of age, Lmna^L648R/L648R mice of both sexes have lower body masses than controls. By ∼20 to 30 wk of age, they exhibit detectable cranial, mandibular, and dental defects similar to those observed in Zmpste24^−/− mice and have decreased vertebral bone density compared to age- and sex-matched controls. Cultured embryonic fibroblasts from Lmna^L648R/L648R mice have aberrant nuclear morphology that is reversible by treatment with a protein farnesyltransferase inhibitor. These novel mice provide a model to study the effects of farnesylated prelamin A during physiological aging.

Therapeutic potential of highly functional codon-optimized microutrophin for muscle-specific expression

High expectations have been set on gene therapy with an AAV-delivered shortened version of dystrophin (µDys) for Duchenne muscular dystrophy (DMD), with several drug candidates currently undergoing clinical trials. Safety concerns with this therapeutic approach include the immune response to introduced dystrophin antigens observed in some DMD patients. Recent reports highlighted microutrophin (µUtrn) as a less immunogenic functional dystrophin substitute for gene therapy. In the current study, we created a human codon-optimized µUtrn which was subjected to side-by-side characterization with previously reported mouse and human µUtrn sequences after rAAV9 intramuscular injections in mdx mice. Long-term studies with systemic delivery of rAAV9-µUtrn demonstrated robust transgene expression in muscles, with localization to the sarcolemma, functional improvement of muscle performance, decreased creatine kinase levels, and lower immunogenicity as compared to µDys. An extensive toxicity study in wild-type rats did not reveal adverse changes associated with high-dose rAAV9 administration and human codon-optimized µUtrn overexpression. Furthermore, we verified that muscle-specific promoters MHCK7 and SPc5-12 drive a sufficient level of rAAV9-µUtrn expression to ameliorate the dystrophic phenotype in mdx mice. Our results provide ground for taking human codon-optimized µUtrn combined with muscle-specific promoters into clinical development as safe and efficient gene therapy for DMD.

Modulation of Ryanodine Receptors Activity Alters the Course of Experimental Autoimmune Encephalomyelitis in Mice

Ryanodine receptors (RyRs), the intracellular Ca²⁺ release channels, are expressed in T lymphocytes and other types of immune cells. Modulation of RyRs has been shown to affect T cell functions in vitro and immune responses in vivo. The effects of modulation of RyRs on the development of autoimmune diseases have not been investigated. Here we studied how modulation of RyRs through administration of RyR inhibitor dantrolene or introducing a gain-of-function RYR1-p.R163C mutation affects clinical progression of experimental autoimmune encephalomyelitis (EAE) in mice, a T cell-mediated autoimmune neuroinflammatory disease. We found that daily intraperitoneal administration of 5 or 10 mg/kg dantrolene beginning at the time of EAE induction significantly reduced the severity of EAE clinical symptoms and dampened inflammation in the spinal cord. The protective effect of dantrolene on EAE was reversible. Dantrolene administration elicited dose-dependent skeletal muscle weakness: mice that received 10 mg/kg dose developed a waddling gait, while 5 mg/kg dantrolene dose administration produced a reduction in four-limb holding impulse values. Mice bearing the gain-of-function RYR1-p.R163C mutation developed the EAE clinical symptoms faster and more severely than wild-type mice. This study demonstrates that RyRs play a significant role in EAE pathogenesis and suggests that inhibition of RyRs with low doses of dantrolene may have a protective effect against autoimmunity and inflammation in humans.

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.

Benefits of betanin in rotenone-induced Parkinson mice

The present study aimed to investigate betanin's neuroprotective effect in mice with rotenone-induced Parkinson-like motor dysfunction and neurodegeneration. Forty male ICR mice were divided into 4 groups: Sham-veh, Rot-veh, Rot-Bet100 and Rot-Bet200. Rotenone at 2.5 mg/kg/48 h was subcutaneous injected in Rot groups, and betanin at 100 and 200 mg/kg/48 h were given alternately with the rotenone injections in Bet groups for 6 weeks. Motor dysfunctions were evaluated weekly using hanging wire and rotarod tests. Brain oxidative status including malondialdehyde, reduced glutathione, catalase, superoxide dismutase, with neuronal degeneration in the motor cortex, striatum and substantia nigra par compacta were evaluated. The immunohistochemical densities of tyrosine hydroxylase in striatum and in substantia nigra par compacta were also measured. We found that rotenone significantly decreased the time to fall in a hanging wire test after the 4^th week and after the rotarod test at the 6^th week (p < 0.05). The percentage of neuronal degeneration in substantia nigra par compacta, striatum and motor cortex significantly increased (p < 0.05), and the tyrosine hydroxylase density in substantia nigra par compacta and in striatum significantly decreased (p < 0.05). Betanin at 100 and 200 mg/kg significantly prevented substantia nigra par compacta, striatum and motor cortex neuronal degeneration (p < 0.05) and maintained tyrosine hydroxylase density in substantia nigra par compacta and in striatum (p < 0.05). These findings appeared concurrently with improved effects on the time to fall in hanging wire and rotarod tests (p < 0.05). Treatment with betanin significantly prevented increased malondialdehyde levels and boosted reduced glutathione, catalase and superoxide dismutase activities (p < 0.05). Betanin exhibits neuroprotective effects against rotenone-induced Parkinson in mice regarding both motor dysfunction and neurodegeneration. Betanin's neurohealth benefit relates to its powerful antioxidative property. Therefore, betanin use in neurodegenerative disease is interesting to study.

Natural History of a Mouse Model Overexpressing the Dp71 Dystrophin Isoform

Dystrophin is a 427 kDa protein that stabilizes muscle cell membranes through interactions with the cytoskeleton and various membrane-associated proteins. Loss of dystrophin as in Duchenne muscular dystrophy (DMD) causes progressive skeletal muscle weakness and cardiac dysfunction. Multiple promoters along the dystrophin gene (DMD) give rise to a number of shorter isoforms. Of interest is Dp71, a 71 kDa isoform implicated in DMD pathology by various animal and patient studies. Strong evidence supporting such a role for Dp71, however, is lacking. Here, we use del52;WT mice to understand how Dp71 overexpression affects skeletal and cardiac muscle phenotypes. Apart from the mouse Dmd gene, del52;WT mice are heterozygous for a full-length, exon 52-deleted human DMD transgene expected to only permit Dp71 expression in muscle. Thus, del52;WT mice overexpress Dp71 through both the human and murine dystrophin genes. We observed elevated Dp71 protein in del52;WT mice, significantly higher than wild-type in the heart but not the tibialis anterior. Moreover, del52;WT mice had generally normal skeletal muscle but impaired cardiac function, exhibiting significant systolic dysfunction as early as 3 months. No histological abnormalities were found in the tibialis anterior and heart. Our results suggest that Dp71 overexpression may have more detrimental effects on the heart than on skeletal muscles, providing insight into the role of Dp71 in DMD pathogenesis.

Aberrant Mitochondrial Dynamics and Exacerbated Response to Neuroinflammation in a Novel Mouse Model of CMT2A

Charcot-Marie-Tooth disease type 2A (CMT2A) is the most common hereditary axonal neuropathy caused by mutations in MFN2 encoding Mitofusin-2, a multifunctional protein located in the outer mitochondrial membrane. In order to study the effects of a novel MFN2^K357T mutation associated with early onset, autosomal dominant severe CMT2A, we generated a knock-in mouse model. While Mfn2^K357T/K357T mouse pups were postnatally lethal, Mfn2^+/K357T heterozygous mice were asymptomatic and had no histopathological changes in their sciatic nerves up to 10 months of age. However, immunofluorescence analysis of Mfn2^+/K357T mice revealed aberrant mitochondrial clustering in the sciatic nerves from 6 months of age, in optic nerves from 8 months, and in lumbar spinal cord white matter at 10 months, along with microglia activation. Ultrastructural analyses confirmed dysmorphic mitochondrial aggregates in sciatic and optic nerves. After exposure of 6-month-old mice to lipopolysaccharide, Mfn2^+/K357T mice displayed a higher immune response, a more severe motor impairment, and increased CNS inflammation, microglia activation, and macrophage infiltrates. Overall, ubiquitous Mfn2^K357T expression renders the CNS and peripheral nerves of Mfn2^+/K357T mice more susceptible to mitochondrial clustering, and augments their response to inflammation, modeling some cellular mechanisms that may be relevant for the development of neuropathy in patients with CMT2A.

Characterization of LRP4/Agrin Antibodies From a Patient With Myasthenia Gravis

BACKGROUND AND OBJECTIVE

To determine whether human anti-LRP4/agrin antibodies are pathogenic in mice and to investigate underpinning pathogenic mechanisms.

METHODS

Immunoglobulin (Ig) was purified from a patient with myasthenia gravis (MG) with anti-LRP4/agrin antibodies and transferred to mice. Mice were characterized for body weight, muscle strength, twitch and tetanic force, neuromuscular junction (NMJ) functions including compound muscle action potential (CMAP) and endplate potentials, and NMJ structure. Effects of the antibodies on agrin-elicited muscle-specific tyrosine kinase (MuSK) activation and AChR clustering were studied and the epitopes of these antibodies were identified.

RESULTS

Patient Ig-injected mice had MG symptoms, including weight loss and muscle weakness. Decreased CMAPs, reduced twitch and tetanus force, compromised neuromuscular transmission, and NMJ fragmentation and distortion were detected in patient Ig-injected mice. Patient Ig inhibited agrin-elicited MuSK activation and AChR clustering. The patient Ig recognized the β3 domain of LRP4 and the C-terminus of agrin and reduced agrin-enhanced LRP4-MuSK interaction.

DISCUSSION

Anti-LRP4/agrin antibodies in the patient with MG is pathogenic. It impairs the NMJ by interrupting agrin-dependent LRP4-MuSK interaction.

Simvastatin does not alleviate muscle pathology in a mouse model of Duchenne muscular dystrophy

Background

Duchenne muscular dystrophy (DMD) is an incurable disease, caused by the mutations in the DMD gene, encoding dystrophin, an actin-binding cytoskeletal protein. Lack of functional dystrophin results in muscle weakness, degeneration, and as an outcome cardiac and respiratory failure. As there is still no cure for affected individuals, the pharmacological compounds with the potential to treat or at least attenuate the symptoms of the disease are under constant evaluation. The pleiotropic agents, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, known as statins, have been suggested to exert beneficial effects in the mouse model of DMD. On the other hand, they were also reported to induce skeletal-muscle myopathy. Therefore, we decided to verify the hypothesis that simvastatin may be considered a potential therapeutic agent in DMD.

Methods

Several methods including functional assessment of muscle function via grip strength measurement, treadmill test, and single-muscle force estimation, enzymatic assays, histological analysis of muscle damage, gene expression evaluation, and immunofluorescence staining were conducted to study simvastatin-related alterations in the mdx mouse model of DMD.

Results

In our study, simvastatin treatment of mdx mice did not result in improved running performance, grip strength, or specific force of the single muscle. Creatine kinase and lactate dehydrogenase activity, markers of muscle injury, were also unaffected by simvastatin delivery in mdx mice. Furthermore, no significant changes in inflammation, fibrosis, and angiogenesis were noted. Despite the decreased percentage of centrally nucleated myofibers in gastrocnemius muscle after simvastatin delivery, no changes were noticed in other regeneration-related parameters. Of note, even an increased rate of necrosis was found in simvastatin-treated mdx mice.

Conclusion

In conclusion, our study revealed that simvastatin does not ameliorate DMD pathology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13395-021-00276-3.

Functional significance of gain-of-function H19 lncRNA in skeletal muscle differentiation and anti-obesity effects

BACKGROUND

Exercise training is well established as the most effective way to enhance muscle performance and muscle building. The composition of skeletal muscle fiber type affects systemic energy expenditures, and perturbations in metabolic homeostasis contribute to the onset of obesity and other metabolic dysfunctions. Long noncoding RNAs (lncRNAs) have been demonstrated to play critical roles in diverse cellular processes and diseases, including human cancers; however, the functional importance of lncRNAs in muscle performance, energy balance, and obesity remains elusive. We previously reported that the lncRNA H19 regulates the poly-ubiquitination and protein stability of dystrophin (DMD) in muscular dystrophy.

METHODS

Here, we identified mouse/human H19-interacting proteins using mouse/human skeletal muscle tissues and liquid chromatography-mass spectrometry (LC-MS). Human induced pluripotent stem-derived skeletal muscle cells (iPSC-SkMC) from a healthy donor and Becker Muscular Dystrophy (BMD) patients were utilized to study DMD post-translational modifications and associated proteins. We identified a gain-of-function (GOF) mutant of H19 and characterized the effects on myoblast differentiation and fusion to myotubes using iPSCs. We then conjugated H19 RNA gain-of-function oligonucleotides (Rgof) with the skeletal muscle enrichment peptide agrin (referred to as AGR-H19-Rgof) and evaluated AGR-H19-Rgof's effects on skeletal muscle performance using wild-type (WT) C57BL/6 J mice and its anti-obesity effects using high-fat diet (HFD)- and leptin deficiency-induced obese mouse models.

RESULTS

We demonstrated that both human and mouse H19 associated with DMD and that the H19 GOF exhibited enhanced interaction with DMD compared to WT H19. DMD was found to associate with serine/threonine-protein kinase MRCK alpha (MRCKα) and α-synuclein (SNCA) in iPSC-SkMC derived from BMD patients. Inhibition of MRCKα and SNCA-mediated phosphorylation of DMD antagonized the interaction between H19 and DMD. These signaling events led to improved skeletal muscle cell differentiation and myotube fusion. The administration of AGR-H19-Rgof improved the muscle mass, muscle performance, and base metabolic rate of WT mice. Furthermore, mice treated with AGR-H19-Rgof exhibited resistance to HFD- or leptin deficiency-induced obesity.

CONCLUSIONS

Our study suggested the functional importance of the H19 GOF mutant in enhancing muscle performance and anti-obesity effects.

VEGFR-1/Flt-1 inhibition increases angiogenesis and improves muscle function in a mouse model of Duchenne muscular dystrophy

Duchenne muscular dystrophy is characterized by structural degeneration of muscle, which is exacerbated by localized functional ischemia due to loss of nitric oxide synthase-induced vasodilation. Treatment strategies aimed at increasing vascular perfusion have been proposed. Toward this end, we have developed monoclonal antibodies (mAbs) that bind to the vascular endothelial growth factor (VEGF) receptor VEGFR-1 (Flt-1) and its soluble splice variant isoform (sFlt-1) leading to increased levels of free VEGF and proangiogenic signaling. The lead chimeric mAb, 21B3, had high affinity and specificity for both human and mouse sFlt-1 and inhibited VEGF binding to sFlt-1 in a competitive manner. Proof-of-concept studies in the mdx mouse model of Duchenne muscular dystrophy showed that intravenous administration of 21B3 led to elevated VEGF levels, increased vascularization and blood flow to muscles, and decreased fibrosis after 6-12 weeks of treatment. Greater muscle strength was also observed after 4 weeks of treatment. A humanized form of the mAb, 27H6, was engineered and demonstrated a comparable pharmacologic effect. Overall, administration of anti-Flt-1 mAbs in mdx mice inhibited the VEGF:Flt-1 interaction, promoted angiogenesis, and improved muscle function. These studies suggest a potential therapeutic benefit of Flt-1 inhibition for patients with Duchenne muscular dystrophy.

Long-term exposure to polypharmacy impairs cognitive functions in young adult female mice

The potential harmful effects of polypharmacy (concurrent use of 5 or more drugs) are difficult to investigate in an experimental design in humans. Moreover, there is a lack of knowledge on sex-specific differences on the outcomes of multiple-drug use. The present study aims to investigate the effects of an eight-week exposure to a regimen of five different medications (metoprolol, paracetamol, aspirin, simvastatin and citalopram) in young adult female mice. Polypharmacy-treated animals showed significant impairment in object recognition and fear associated contextual memory, together with a significant reduction of certain hippocampal proteins involved in pathways necessary for the consolidation of these types of memories, compared to animals with standard diet. The impairments in explorative behavior and spatial memory that we reported previously in young adult male mice administered the same polypharmacy regimen were not observed in females in the current study. Therefore, the same combination of medications induced different negative outcomes in young adult male and female mice, causing a significant deficit in non-spatial memory in female animals. Overall, this study strongly supports the importance of considering sex-specific differences in designing safer and targeted multiple-drug therapies.

Attenuated Epigenetic Suppression of Muscle Stem Cell Necroptosis Is Required for Efficient Regeneration of Dystrophic Muscles

Somatic stem cells expand massively during tissue regeneration, which might require control of cell fitness, allowing elimination of non-competitive, potentially harmful cells. How or if such cells are removed to restore organ function is not fully understood. Here, we show that a substantial fraction of muscle stem cells (MuSCs) undergo necroptosis because of epigenetic rewiring during chronic skeletal muscle regeneration, which is required for efficient regeneration of dystrophic muscles. Inhibition of necroptosis strongly enhances suppression of MuSC expansion in a non-cell-autonomous manner. Prevention of necroptosis in MuSCs of healthy muscles is mediated by the chromatin remodeler CHD4, which directly represses the necroptotic effector Ripk3, while CHD4-dependent Ripk3 repression is dramatically attenuated in dystrophic muscles. Loss of Ripk3 repression by inactivation of Chd4 causes massive necroptosis of MuSCs, abolishing regeneration. Our study demonstrates how programmed cell death in MuSCs is tightly controlled to achieve optimal tissue regeneration.

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Necroptotic cell death of MuSCs is essential for efficient muscle regeneration

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Inhibition of necroptosis exacerbates adverse crosstalk among mdx muscle stem cells

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The CHD4/NuRD complex directly represses Ripk3-dependent necroptosis

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Attenuated recruitment of CHD4 to Ripk3 locus lowers necroptosis threshold in dystrophy

Different Parts of the Chicken Embryo Egg Improve D-Galactose-Induced Aging in a Mice Model

Chick (CE) or duck embryo eggs are known for nutritional supplement foods in traditional East countries for physical fitness enhancement and postpartum conditioning for many years. In this study, we evaluated the effects of different parts of the 10-day CE (embryo: CEr, yolk: CEw, and chorioallantoic membrane: CEp) on the antifatigue and antiaging activities in a D-galactose- (D-gal) induced aging mice model. The results showed CEp obviously increased the muscle weight and the liver and muscle glycogen content and enhanced exercise performance. In the antiaging assay, CEp significantly increased the activity of superoxide dismutase (SOD) and Glutathione Peroxidase (GPx). Moreover, the immunohistochemistry results of NRF-2 and HO-1 were also detected in the livers of mice in the D-gal/CEp group. The only partially potential such as CEr might improve OFT function with TG level, and CEw had strange grip strength. Therefore, we suggest that CEp has a potent antifatigue ability and could minimize the occurrence of age-associated disorders, more than other parts of the 10 days chicken embryo egg.

Targeting TDP-43 Pathology Alleviates Cognitive and Motor Deficits Caused by Chronic Cerebral Hypoperfusion

Vascular dementia is one of the most common forms of dementia in aging population. However, the molecular mechanisms involved in development of disease and the link between the cerebrovascular pathology and the cognitive impairments remain elusive. Currently, one common and/or converging neuropathological pathway leading to dementia is the mislocalization and altered functionality of the TDP-43. We recently demonstrated that brain ischemia triggers an age-dependent deregulation of TDP-43 that was associated with exacerbated neurodegeneration. Here, we report that chronic cerebral hypoperfusion in mice (CCH) produced by unilateral common carotid artery occlusion induces cytoplasmic mislocalization of TDP-43 and formation of insoluble phosho-TDP-43 aggregates reminiscent of pathological changes detected in cortical neurons of human brain samples from patients suffering from vascular dementia. Moreover, the CCH in mice caused chronic activation of microglia and innate immune response, development of cognitive deficits, and motor impairments. Oral administration of a novel analog (IMS-088) of withaferin A, an antagonist of nuclear factor-κB essential modulator (NEMO), led to mitigation of TDP-43 pathology, enhancement of autophagy, and amelioration of cognitive/motor deficits in CCH mice. Taken together, our results suggest that targeting TDP-43 pathogenic inclusions may have a disease-modifying effect in dementia caused by chronic brain hypoperfusion.

Effects of Exercise and a High-Fat, High-Sucrose Restriction Diet on Metabolic Indicators, Nr4a3, and Mitochondria-Associated Protein Expression in the Gastrocnemius Muscles of Mice with Diet-Induced Obesity

Background

Exercise and high fat, high sucrose restriction diets are well known treatments for obesity. The aim of this study was to measure the effects of those lifestyle interventions on molecular transducers of exercise, such as Nr4a3, mitochondria-associated proteins, and muscle function.

Methods

We conducted 8 weeks of treadmill exercise and sucrose or fat restriction diets in obese mice. The mice were divided into eight groups: the normal diet (CON) group, normal diet with exercise (CONEX) group, high fat, high sucrose diet (HFHS) group, HFHS with exercise (HFHSEX) group, sucrose restriction (SR) group, SR with exercise (SREX) group, high fat, high sucrose restriction (ND) group, and ND with exercise (NDEX) group.

Results

The 8 weeks of exercise reduced body weight, improved lipid profiles (total cholesterol, triglycerides), and increased hanging time. The combination of exercise and a fat and sucrose restriction diet improved glucose tolerance and increased grip strength. The 8 weeks of intervention did not significantly affect the Nr4a3 protein level. The sucrose and fat restriction diet increased the phosphorylated protein kinase B (pAkt)/Akt ratio, and its level was lower in the HFHS group. Exercise increased the protein expression level of PGC-1α in obese conditions. Moreover, SR led reduced the phosphorylated AMP-activated protein kinase (pAMPK)/AMPK ratio and PGC-1α to the control level.

Conclusion

The 8 weeks of exercise or a sucrose and fat restriction diet improved metabolic indicators and muscle function. SR reduced pAMPK/AMPK and PGC-1α to the control level. Nr4a3 protein expression was not significantly changed by either exercise or a fat and sucrose restriction diet.

Acute motor deficit and subsequent remyelination-associated recovery following internal capsule demyelination in mice

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system (CNS), characterized by accumulated motor disability. However, whether remyelination promotes motor recovery following demyelinating injury remains unclear. Damage to the internal capsule (IC) is known to result in motor impairment in multiple sclerosis and stroke. Here, we induced focal IC demyelination in mice by lysophosphatidylcholine (LPC) injection, and examined its effect on motor behavior. We also compared the effect of LPC-induced IC damage to that produced by endothelin-1 (ET1), a potent vasoconstrictor used in experimental stroke lesions. We found that LPC or ET1 injections induced asymmetric motor deficit at 7 days post-lesion (dpl), and that both lesion types displayed increased microglia/macrophage density, myelin loss, and axonal dystrophy. The motor deficit and lesion pathology remained in ET1-injected mice at 28 dpl. In contrast, LPC-injected mice regained motor function by 28 dpl, with corresponding reduction in activated microglia/macrophage density, and recovery of myelin staining and axonal integrity in lesions. These results suggest that LPC-induced IC demyelination results in acute motor deficit and subsequent recovery through remyelination, and may be used to complement future drug screens to identify drugs for promoting remyelination.

A novel recessive mutation affecting DNAJB6a causes myofibrillar myopathy

Mutations in the DNAJB6 gene have been identified as rare causes of myofibrillar myopathies. However, the underlying pathophysiologica mechanisms remain elusive. DNAJB6 has two known isoforms, including the nuclear isoform DNAJB6a and the cytoplasmic isoform DNAJB6b, which was thought to be the pathogenic isoform. Here, we report a novel recessive mutation c.695_699del (p. Val 232 Gly fs*7) in the DNAJB6 gene, associated with an apparently recessively inherited late onset distal myofibrillar myopathy in a Chinese family. Notably, the novel mutation localizes to exon 9 and uniquely encodes DNAJB6a. We further identified that this mutation decreases the mRNA and protein levels of DNAJB6a and results in an age-dependent recessive toxic effect on skeletal muscle in knock-in mice. Moreover, the mutant DNAJB6a showed a dose-dependent anti-aggregation effect on polyglutamine-containing proteins in vitro. Taking together, these findings reveal the pathogenic role of DNAJB6a insufficiency in myofibrillar myopathies and expand upon the molecular spectrum of DNAJB6 mutations.

Dental pulp stem cells can improve muscle dysfunction in animal models of Duchenne muscular dystrophy

Background

Duchenne muscular dystrophy (DMD) is an inherited progressive disorder that causes skeletal and cardiac muscle deterioration with chronic inflammation. Dental pulp stem cells (DPSCs) are attractive candidates for cell-based strategies for DMD because of their immunosuppressive properties. Therefore, we hypothesized that systemic treatment with DPSCs might show therapeutic benefits as an anti-inflammatory therapy.

Methods

To investigate the potential benefits of DPSC transplantation for DMD, we examined disease progression in a DMD animal model, mdx mice, by comparing them with different systemic treatment conditions. The DPSC-treated model, a canine X-linked muscular dystrophy model in Japan (CXMD_J), which has a severe phenotype similar to that of DMD patients, also underwent comprehensive analysis, including histopathological findings, muscle function, and locomotor activity.

Results

We demonstrated a therapeutic strategy for long-term functional recovery in DMD using repeated DPSC administration. DPSC-treated mdx mice and CXMD_J showed no serious adverse events. MRI findings and muscle histology suggested that DPSC treatment downregulated severe inflammation in DMD muscles and demonstrated a milder phenotype after DPSC treatment. DPSC-treated models showed increased recovery in grip-hand strength and improved tetanic force and home cage activity. Interestingly, maintenance of long-term running capability and stabilized cardiac function was also observed in 1-year-old DPSC-treated CXMD_J.

Conclusions

We developed a novel strategy for the safe and effective transplantation of DPSCs for DMD recovery, which included repeated systemic injection to regulate inflammation at a young age. This is the first report on the efficacy of a systemic DPSC treatment, from which we can propose that DPSCs may play an important role in delaying the DMD disease phenotype.

CCR2 improves homing and engraftment of adipose-derived stem cells in dystrophic mice

Background

Dystrophinopathy, a common neuromuscular disorder caused by the absence of dystrophin, currently lacks effective treatments. Systemic transplantation of adipose-derived stem cells (ADSCs) is a promising treatment approach, but its low efficacy remains a challenge. Chemokine system-mediated stem cell homing plays a critical role in systemic transplantation. Here, we investigated whether overexpression of a specific chemokine receptor could improve muscle homing and therapeutic effects of ADSC systemic transplantation in dystrophic mice.

Methods

We analysed multiple microarray datasets from the Gene Expression Omnibus to identify a candidate chemokine receptor and then evaluated the protein expression of target ligands in different tissues and organs of dystrophic mice. The candidate chemokine receptor was overexpressed using the lentiviral system in mouse ADSCs, which were used for systemic transplantation into the dystrophic mice, followed by evaluation of motor function, stem cell muscle homing, dystrophin expression, and muscle pathology.

Results

Chemokine-profile analysis identified C–C chemokine receptor (CCR)2 as the potential target for improving ADSC homing. We found that the levels of its ligands C–C chemokine ligand (CCL)2 and CCL7 were higher in muscles than in other tissues and organs of dystrophic mice. Additionally, CCR2 overexpression improved ADSC migration ability and maintained their multilineage-differentiation potentials. Compared with control ADSCs, transplantation of those overexpressing CCR2 displayed better muscle homing and further improved motor function, dystrophin expression, and muscle pathology in dystrophic mice.

Conclusions

These results demonstrated that CCR2 improved ADSC muscle homing and therapeutic effects following systemic transplantation in dystrophic mice.

Mouse Models of Muscle Fibrosis

Fibrosis in skeletal muscle is the natural tissue response to persistent damage and chronic inflammatory states, cursing with altered muscle stem cell regenerative functions and increased activation of fibrogenic mesenchymal stromal cells. Exacerbated deposition of extracellular matrix components is a characteristic feature of human muscular dystrophies, neurodegenerative diseases affecting muscle and aging. The presence of fibrotic tissue not only impedes normal muscle contractile functions but also hampers effective gene and cell therapies. There is a lack of appropriate experimental models to study fibrosis. In this chapter, we highlight recent developments on skeletal muscle fibrosis in mice and expand previously described methods by our group to exacerbate and accelerate fibrosis development in murine muscular dystrophy models and to study the presence of fibrosis in muscle samples. These methods will help understand the molecular and biological mechanisms involved in muscle fibrosis and to identify novel therapeutic strategies to limit the progression of fibrosis in muscular dystrophy.

Systemic AAV8-mediated delivery of a functional copy of muscle glycogen phosphorylase (Pygm) ameliorates disease in a murine model of McArdle disease

McArdle disease is a disorder of carbohydrate metabolism that causes painful skeletal muscle cramps and skeletal muscle damage leading to transient myoglobinuria and increased risk of kidney failure. McArdle disease is caused by recessive mutations in the muscle glycogen phosphorylase (PYGM) gene leading to absence of PYGM enzyme in skeletal muscle and preventing access to energy from muscle glycogen stores. There is currently no cure for McArdle disease. Using a preclinical animal model, we aimed to identify a clinically translatable and relevant therapy for McArdle disease. We evaluated the safety and efficacy of recombinant adeno-associated virus serotype 8 (rAAV8) to treat a murine model of McArdle disease via delivery of a functional copy of the disease-causing gene, Pygm. Intraperitoneal injection of rAAV8-Pygm at post-natal day 1-3 resulted in Pygm expression at 8 weeks of age, accompanied by improved skeletal muscle architecture, reduced accumulation of glycogen and restoration of voluntary running wheel activity to wild-type levels. We did not observe any adverse reaction to the treatment at 8 weeks post-injection. Thus, we have investigated a highly promising gene therapy for McArdle disease with a clear path to the ovine large animal model endemic to Western Australia and subsequently to patients.

The role of Nrf2 in acute and chronic muscle injury

The nuclear factor erythroid 2-related factor 2 (Nrf2) is considered as a master cytoprotective factor regulating the expression of genes encoding anti-oxidant, anti-inflammatory, and detoxifying proteins. The role of Nrf2 in the pathophysiology of skeletal muscles has been evaluated in different experimental models, however, due to inconsistent data, we aimed to investigate how Nrf2 transcriptional deficiency (Nrf2tKO) affects muscle functions both in an acute and chronic injury. The acute muscle damage was induced in mice of two genotypes-WT and Nrf2tKO mice by cardiotoxin (CTX) injection. To investigate the role of Nrf2 in chronic muscle pathology, mdx mice that share genetic, biochemical, and histopathological features with Duchenne muscular dystrophy (DMD) were crossed with mice lacking transcriptionally active Nrf2 and double knockouts (mdx/Nrf2tKO) were generated. To worsen the dystrophic phenotype, the analysis of disease pathology was also performed in aggravated conditions, by applying a long-term treadmill test. We have observed slightly increased muscle damage in Nrf2tKO mice after CTX injection. Nevertheless, transcriptional ablation of Nrf2 in mdx mice did not significantly aggravate the most deleterious, pathological hallmarks of DMD related to degeneration, inflammation, fibrotic scar formation, angiogenesis, and the number and proliferation of satellite cells in non-exercised conditions. On the other hand, upon chronic exercises, the degeneration and inflammatory infiltration of the gastrocnemius muscle, but not the diaphragm, turned to be increased in Nrf2tKOmdx in comparison to mdx mice. In conclusion, the lack of transcriptionally active Nrf2 influences moderately muscle pathology in acute CTX-induced muscle injury and chronic DMD mouse model, without affecting muscle functionality. Hence, in general, we demonstrated that the deficiency of Nrf2 transcriptional activity has no profound impact on muscle pathology in various models of muscle injury.

The lncRNA H19 alleviates muscular dystrophy by stabilizing dystrophin

Dystrophin proteomic regulation in Muscular Dystrophies (MD) remains unclear. We report that a long noncoding RNA (lncRNA), H19, associates with dystrophin and inhibits E3 ligase-dependent poly-ubiquitination at Lys3584 (referred to as Ub-DMD) and its subsequent protein degradation. In-frame deletions in BMD and a DMD non-silent mutation (C3340Y) result in defects in the protein’s ability to interact with H19, causing elevated Ub-DMD levels and dystrophin degradation. Dmd C3333Y mice exhibited progressive muscular dystrophy, elevated serum CK, heart dilation, blood vessel irregularity, and respiratory failure with concurrently reduced dystrophin and increased Ub-DMD status. H19 RNA oligonucleotides conjugated with Agrin (AGR-H19) and Nifenazone competed-with/inhibited TRIM63. Dmd C3333Y animals, iPSC-derived skeletal muscle cells from BMD patients, or mdx mice subjected to exon-skipping exhibited inhibited dystrophin degradation, preserved skeletal/cardiac muscle histology, and improved strength/heart function following AGR-H19 or Nifenazone treatment. Our study paves the way to meaningful targeted therapeutics for BMD and certain DMD patients.