Glucocorticoids are drugs of choice in Duchenne muscular dystrophy (DMD), prolonging patients' ambulation. Their mode of action at the protein level is not completely understood. In DMD, muscle ...tissue is replaced by fibrotic tissue produced by fibroblasts, reducing mobility. Nuclear factor of activated T-cells 5 (NFAT5) is involved in fibroblast proliferation. By treating one DMD fibroblast cell culture and one of unaffected skeletal muscle fibroblasts with methylprednisolone (MP) or hydrocortisone (HC) for 24 h or 12 d, the antiproliferative properties of glucocorticoids could be unraveled. NFAT5 localization and expression was explored by immunocytochemistry (ICC), Western blotting (WB) and RT-qPCR. NFAT5 and glucocorticoid receptor (GR) colocalization was measured by ImageJ. GR siRNA was used, evaluating GR's influence on NFAT5 expression during MP and HC treatment. Cell proliferation was monitored by IncuCyte ZOOM. In DMD fibroblasts, treatment with MP for 24 h induced dots (ICC) positive for NFAT5 and colocalizing with GR. After 12 d of MP or HC in DMD fibroblasts, NFAT5 expression was decreased (RT-qPCR and WB) and growth arrest was observed (Incucyte ZOOM), whereas NFAT5 expression and cell growth remained unchanged in unaffected skeletal muscle fibroblasts. This study may help understand the antiproliferative properties of glucocorticoids in DMD fibroblasts.
Abstract Heat shock proteins are important factors in skeletal muscle physiology and stress response. We examined the effects of chronic inflammation on the distribution of heat shock protein ...families 70 and 90 using immunofluorescence and Western blotting, in muscle biopsies from 33 idiopathic inflammatory myopathy patients aged 26–66 (dermatomyositis), 17–78 (polymyositis) and 57–80 (sporadic inclusion body myositis) years, and seven Duchenne muscular dystrophy patients (aged 3–19 years). Our results reveal the multifaceted role played by chaperones in inflammatory muscle tissue. On the one hand, regenerating, atrophic and vacuolated muscle fibers displayed upregulation of both protein families. Higher levels of chaperones in challenged fibers point to the myocyte’s attempt to restore and regenerate. On the other hand, heat shock proteins of the 90 family were strongly upregulated in macrophages and cytotoxic T-cells actively invading nonnecrotic muscle fibers of sporadic inclusion body myositis and polymyositis, probably conferring enhanced myocytotoxic capacity. Our data provide positive arguments for exploring heat shock protein 90-based therapy in inflammatory muscle disease.
Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterised by myositis-related autoantibodies plus infiltration of leucocytes into muscles and/or the skin, leading to ...the destruction of blood vessels and muscle fibres, chronic weakness and fatigue. While complement-mediated destruction of capillary endothelia is implicated in paediatric and adult dermatomyositis, the complex diversity of complement
in IIM pathology was unknown.
We elucidated the gene copy number (GCN) variations of total
,
and
and
in 1644 Caucasian patients with IIM, plus 3526 matched healthy controls using real-time PCR or Southern blot analyses. Plasma complement levels were determined by single radial immunodiffusion.
The large study populations helped establish the distribution patterns of various
GCN groups. Low GCNs of
(
=2+3) and
deficiency (
=0+1) were strongly correlated with increased risk of IIM with OR equalled to 2.58 (2.28-2.91), p=5.0×10
for
, and 2.82 (2.48-3.21), p=7.0×10
for
deficiency. Contingency and regression analyses showed that among patients with
deficiency, the presence of
became insignificant as a risk factor in IIM except for inclusion body myositis (IBM), by which 98.2% had
with an OR of 11.02 (1.44-84.4). Intragroup analyses of patients with IIM for C4 protein levels and IIM-related autoantibodies showed that those with anti-Jo-1 or with anti-PM/Scl had significantly lower C4 plasma concentrations than those without these autoantibodies.
deficiency is relevant in dermatomyositis,
is important in IBM and both
deficiency and
contribute interactively to risk of polymyositis.
Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration. Osmotic stress participates to DMD pathology and altered levels of osmolyte pathway members ...have been reported. The goal of this study was to gain insight in osmoregulatory changes in the
mouse model by examining the expression of osmolyte pathway members, including taurine transporter (TauT), sodium myo-inositol co-transporter (SMIT), betaine GABA transporter (BGT), and aldose reductase (AR) in the skeletal muscles and diaphragm of
mice aged 4, 8, 12, and 26 weeks. Necrosis was most prominent in 12 week-old
mice, whereas the amount of regenerated fibers increased until week 26 in the tibialis anterior. TauT protein levels were downregulated in the tibialis anterior and gastrocnemius of 4 to 12 week-old
mice, but not in 26 week-old mice, whereas TauT levels in the diaphragm remained significantly lower in 26 week-old
mice. In contrast, SMIT protein levels were significantly higher in the muscles of
mice when compared to controls. Our study revealed differential regulation of osmolyte pathway members in
muscle, which points to their complex involvement in DMD pathogenesis going beyond general osmotic stress responses. These results highlight the potential of osmolyte pathway members as a research interest and future therapeutic target in dystrophinopathy.
TAR DNA-binding protein 43, mostly referred to as TDP-43 (encoded by the
gene) is strongly linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). From ...the identification of TDP-43 positive aggregates in the brains and spinal cords of ALS/FTD patients, to a genetic link between
mutations and the development of TDP-43 pathology in ALS, there is strong evidence indicating that TDP-43 plays a pivotal role in the process of neuronal degeneration. What this role is, however, remains to be determined with evidence ranging from gain of toxic properties through the formation of cytotoxic aggregates, to an inability to perform its normal functions due to nuclear depletion. To add to an already complex subject, recent studies highlight a role for TDP-43 in muscle physiology and disease. We here review the biophysical, biochemical, cellular and tissue-specific properties of TDP-43 in the context of neurodegeneration and have a look at the nascent stream of evidence that positions TDP-43 in a myogenic context. By integrating the neurogenic and myogenic pathological roles of TDP-43 we provide a more comprehensive and encompassing view of the role and mechanisms associated with TDP-43 across the various cell types of the motor system, all the way from brain to limbs.
Duchenne Muscular Dystrophy (DMD) is a debilitating muscle disorder that condemns patients to year-long dependency on glucocorticoids. Chronic glucocorticoid use elicits many unfavourable ...side-effects without offering satisfying clinical improvement, thus, the search for alternative treatments to alleviate muscle inflammation persists. Taurine, an osmolyte with anti-inflammatory effects, mitigated pathological features in the mdx mouse model for DMD but interfered with murine development. In this study, ectoine is evaluated as an alternative for taurine in vitro in CCL-136 cells and in vivo in the mdx mouse. Pre-treating CCL-136 cells with 0.1 mM taurine and 0.1 mM ectoine prior to exposure with 300 U/mL IFN-γ and 20 ng/mL IL-1β partially attenuated cell death, whilst 100 mM taurine reduced MHC-I protein levels. In vivo, histopathological features of the tibialis anterior in mdx mice were mitigated by ectoine, but not by taurine. Osmolyte treatment significantly reduced mRNA levels of inflammatory disease biomarkers, respectively, CCL2 and SPP1 in ectoine-treated mdx mice, and CCL2, HSPA1A, TNF-α and IL-1β in taurine-treated mdx mice. Functional performance was not improved by osmolyte treatment. Furthermore, ectoine-treated mdx mice exhibited reduced body weight. Our results confirmed beneficial effects of taurine in mdx mice and, for the first time, demonstrated similar and differential effects of ectoine.
Highlights • The heterogeneous group of idiopathic inflammatory myopathies (IM) needs international consensus on myopathologic classification. • Experts agreed on the basic panel of histological ...muscle biopsy stains necessary for diagnosing the different IM. • A biopsy stains and drafted a score tool to describe muscle tissue alterations in the IM.
Two siblings from consanguineous parents died perinatally with a condition characterized by generalized hypotonia, respiratory insufficiency, arthrogryposis, microcephaly, congenital brain ...malformations and hyperglycinemia. Catalytic activities of the mitochondrial respiratory complexes I and II were deficient in skeletal muscle, a finding suggestive of an inborn error in mitochondrial biogenesis. Homozygosity mapping identified IBA57 located in the largest homozygous region on chromosome 1 as a culprit candidate gene. IBA57 is known to be involved in the biosynthesis of mitochondrial 4Fe-4S proteins. Sequence analysis of IBA57 revealed the homozygous mutation c.941A > C, p.Gln314Pro. Severely decreased amounts of IBA57 protein were observed in skeletal muscle and cultured skin fibroblasts from the affected subjects. HeLa cells depleted of IBA57 showed biochemical defects resembling the ones found in patient-derived cells, including a decrease in various mitochondrial 4Fe-4S proteins and in proteins covalently linked to lipoic acid (LA), a cofactor produced by the 4Fe-4S protein LA synthase. The defects could be complemented by wild-type IBA57 and partially by mutant IBA57. As a result of the mutation, IBA57 protein was excessively degraded, an effect ameliorated by protease inhibitors. Hence, we propose that the mutation leads to partial functional impairment of IBA57, yet the major pathogenic impact is due to its proteolytic degradation below physiologically critical levels. In conclusion, the ensuing lethal complex biochemical phenotype of a novel metabolic syndrome results from multiple Fe/S protein defects caused by a deficiency in the Fe/S cluster assembly protein IBA57.
In human cells, mitochondria provide the largest part of cellular energy in the form of adenosine triphosphate generated by the process of oxidative phosphorylation (OXPHOS). Impaired OXPHOS activity ...leads to a heterogeneous group of inherited diseases for which therapeutic options today remain very limited. Potential innovative strategies aim to ameliorate mitochondrial function by increasing the total mitochondrial load of tissues and/or to scavenge the excess of reactive oxygen species generated by OXPHOS malfunctioning. In this respect, resveratrol, a compound that conveniently combines mitogenetic with antioxidant activities and, as a bonus, possesses anti-apoptotic properties, has come forward as a promising nutraceutical. We review the scientific evidence gathered so far through experiments in both in vitro and in vivo systems, evaluating the therapeutic effect that resveratrol is expected to generate in mitochondrial patients. The obtained results are encouraging, but clearly show that achieving normalization of OXPHOS function with this strategy alone could prove to be an unattainable goal.
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